Work vehicle

Abstract

Provided is a work vehicle (1) capable of effectively assisting the rotational power of an engine (4) by means of the rotational power of a flywheel when a work load is large. A work vehicle (1) is provided with: an engine (4); a first flywheel (13) that rotates by receiving the rotational power of the engine (4); a transmission device (16) that selectively receives rotational power of the engine (4) and / or rotational power of the engine (4) and the first flywheel (13), shifts the speed, and outputs the rotational power; a first power transmission path (31) that transmits rotational power of the engine (4) to the first flywheel (13); and a second power transmission path (32) for transmitting the rotational power of the first flywheel (13) to the transmission device (16), the first power transmission path (31) and the second power transmission path (32) being mutually independent paths, the first power transmission path (31) being provided with a first clutch (26) for interrupting the transmission of the rotational power from the engine (4) to the first flywheel (13), and the second power transmission path (32) being provided with a second clutch (26) for interrupting the transmission of the rotational power from the engine (4) to the second flywheel (13). The second power transmission path (32) is provided with a second clutch (27) for interrupting the transmission of rotational power from the first flywheel (13) to the transmission device (16).

Description

Technical Field

[0001] The present invention relates to a working vehicle such as a tractor. Background Art

[0002] Conventionally, the technology disclosed in Patent Document 1 listed below is known.

[0003] The technology disclosed in Patent Document 1 is an energy recovery system for a vehicle powertrain having an engine, a flywheel, and a transmission device. According to this system, rotational energy can be received from the powertrain of the wheels and stored in the flywheel, and the stored rotational energy can be returned to the powertrain.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Gazette "Patent No. 5554323" Summary of the invention

[0007] Problems to be solved by the invention

[0008] In the above disclosed technology, paths capable of transmitting power are respectively formed between the engine and the flywheel and between the flywheel and the transmission. However, these paths are not independent of each other. Specifically, both of the above paths are paths through the planetary gear mechanism.

[0009] Therefore, the rotation speed of the rotation power input to the flywheel when the rotation power is transmitted from the engine to the flywheel, and the rotation speed of the rotation power output to the transmission when the rotation power is transmitted from the flywheel to the transmission, become the rotation speed determined based on the gear ratio of the planetary gear mechanism. As a result, even if the rotation power of the engine is accelerated by the planetary gear mechanism and input to the flywheel, the rotation power output from the flywheel will be decelerated by the planetary gear mechanism and output to the transmission, so the rotation energy stored in the flywheel cannot be efficiently output to the transmission. Therefore, in the case of insufficient rotation power of the engine, it is difficult to effectively assist the insufficient rotation power with the rotation power of the flywheel.

[0010] Therefore, when the above-disclosed technology is applied to a work vehicle that drives a work implement using the rotational power of an engine, the rotational power of the engine cannot be effectively assisted by the rotational power of the flywheel when the work load is large.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a working vehicle capable of effectively assisting the rotational power of an engine with the rotational power of a flywheel when a working load is large.

[0012] Technical solutions to problems

[0013] The technical means taken by the present invention to solve the above-mentioned problems are characterized by the following aspects.

[0014] The working vehicle of one embodiment of the present invention comprises: an engine; a first flywheel, which receives the rotational power of the engine and rotates; a speed change device, which selectively receives the rotational power of the engine and the rotational power of any one of the rotational power of the engine and the first flywheel and outputs it after changing the speed; a first power transmission path, which transmits the rotational power of the engine to the first flywheel; and a second power transmission path, which transmits the rotational power of the first flywheel to the speed change device, the first power transmission path and the second power transmission path are independent of each other, and a first clutch is provided on the first power transmission path to intermittently transmit the rotational power from the engine to the first flywheel, and a second clutch is provided on the second power transmission path to intermittently transmit the rotational power from the first flywheel to the speed change device.

[0015] The first power transmission path may include a speed increasing mechanism for increasing the speed of the rotational power of the engine and transmitting the speed to the first flywheel, and the second power transmission path may transmit the rotational power of the first flywheel to the transmission without passing through a speed reduction mechanism.

[0016] The work vehicle may include a third power transmission path that transmits the rotational power of the engine to the transmission device without passing through the first flywheel, wherein the third power transmission path always connects an output shaft of the engine and an input shaft of the transmission device.

[0017] The speed increasing mechanism may also be composed of a planetary gear mechanism including a sun gear, planetary gears and a ring gear, wherein the ring gear is fixed in a non-rotatable manner, the rotational power of the engine is input into the planetary gears and transmitted to the first flywheel via the sun gear, and the rotational power of the first flywheel is transmitted to the speed change device without passing through the planetary gear mechanism.

[0018] The working vehicle may further include a second flywheel connected to an output shaft of the engine, wherein the first flywheel is rotatable independently of the second flywheel.

[0019] In the work vehicle, the first flywheel may be arranged between the second flywheel and the transmission in the axial length direction of the output shaft.

[0020] The work vehicle may include a relay shaft interposed between the output shaft and the transmission device and constituting the third power transmission path, wherein the relay shaft is provided to penetrate the first flywheel.

[0021] The first clutch and the second clutch may also be arranged in parallel along the radial direction of the relay shaft.

[0022] The first clutch and the second clutch may be arranged side by side along the axial length direction of the relay shaft.

[0023] The work vehicle may also include a housing for accommodating the first flywheel, the first clutch, and the second clutch. A partition wall is provided inside the housing for dividing the interior into a space for accommodating the first flywheel and a space for accommodating the first clutch and the second clutch. The first clutch and the second clutch are arranged at a position facing the partition wall.

[0024] The first clutch and the second clutch may be multi-plate clutches having a plurality of friction plates, and may be arranged on the inner circumference side of the first flywheel.

[0025] Effects of the Invention

[0026] According to the working vehicle of the present invention, when the working load is large, the rotational power of the engine can be effectively assisted by the rotational power of the flywheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic side view showing a working vehicle according to the present invention.

[0028] Figure 2 It is a diagram showing the structure of a power transmission mechanism of a work vehicle.

[0029] Figure 3 It is a diagram showing the structure of the first embodiment of the first power transmission unit.

[0030] Figure 4 It is a diagram showing the structure of the second embodiment of the first power transmission unit.

[0031] Figure 5 It is a diagram showing the structure of a third embodiment of the first power transmission unit.

[0032] Figure 6 It is a diagram showing the structure of a fourth embodiment of the first power transmission unit.

[0033] Figure 7 It is a diagram showing the structure of a fifth embodiment of the first power transmission unit.

[0034] Figure 8 It is a diagram showing the structure of a sixth embodiment of the first power transmission unit.

[0035] Fig. 9 It is a collinear diagram of the planetary gear mechanism constituting the speed increasing mechanism.

[0036] Fig.10 It is a cross-sectional view showing a part of a power transmission mechanism including a first power transmission portion according to a fifth embodiment and a transmission case accommodating the power transmission mechanism.

[0037] Fig.11 It is magnified Fig.10 Part of the diagram.

[0038] Fig.12 It is a stereoscopic view showing a first flywheel, a partition wall, a support member, a first friction plate, and a second friction plate.

[0039] Fig.13 This is a block diagram showing a schematic configuration of a control system included in a work vehicle.

[0040] Fig.14 The diagram shows the states of the engine, the first flywheel, the first clutch, and the second clutch in each operation mode executed by the control system.

[0041] Fig.15 It is a state transition diagram of the action mode executed by the control system.

[0042] Fig.16 It is a diagram showing the conditions (threshold values) for transition of the operation mode.

[0043] Fig.17 This is a flowchart showing the flow of operations when shifting from the free mode to the sticky preparation mode.

[0044] Fig.18 This is a flowchart showing the flow of actions when shifting from the viscous preparation mode to the viscous mode or the free mode.

[0045] Fig.19 This is a flowchart showing the flow of operations when shifting from the sticky mode to the charge preparation mode or the free mode.

[0046] Fig. 20 This is a flowchart showing the flow of operations when shifting from the charging preparation mode to the charging mode or the free mode.

[0047] Fig.21 This is a flowchart showing the flow of operations when shifting from the charging mode to the supercharging preparation mode or the free mode.

[0048] Fig. 22 This is a flowchart showing the flow of operations when shifting from the supercharging preparation mode to the supercharging mode.

[0049] Fig.23 This is a flowchart showing the flow of operations when shifting from the boost mode to the viscous mode or the free mode.

[0050] Fig.24AThis is an example of a screen display in which a notification is given on the screen of the display input device that the charging mode can be switched to the supercharging preparation mode, and shows the screen of the display input device in a state in which the mode cannot be switched to the supercharging preparation mode.

[0051] Fig. 24B This is an example of a screen display in which a notification is given on the screen of the display input device that the charging mode can be switched to the supercharging preparation mode, and shows the screen of the display input device in a state where the mode can be switched to the supercharging preparation mode.

[0052] Fig.25 This is an example of a timing diagram for a control system. DETAILED DESCRIPTION

[0053] Hereinafter, one embodiment of the present invention will be described with reference to the drawings as appropriate.

[0054] In the following description, Figure 1 The direction of arrow A1 is set as the front, and the direction of arrow A2 is set as the rear.

[0055] <Working vehicles>

[0056] Figure 1 1 is a schematic side view showing a working vehicle 1 of the present invention. In the case of the present embodiment, a tractor is exemplified as the working vehicle 1. However, the working vehicle 1 is not limited to a tractor, and may be other working vehicles such as a wheel loader, a small crawler loader, a backhoe, and a rice transplanter.

[0057] The work vehicle 1 includes a vehicle body 2 and a travel device 3 .

[0058] The vehicle body 2 includes an engine 4 and a transmission case 5 connected to the rear portion of the engine 4. The travel device 3 supports the vehicle body 2 in a travelable manner. The travel device 3 includes front wheels 3F and rear wheels 3R.

[0059] A lifting device 7 is provided at the rear of the vehicle body 2. A working device can be mounted on the lifting device 7. The working device mounted on the lifting device 7 is a device for working on a field, such as a tilling device or a sowing device. The lifting device 7 is composed of, for example, a three-point linkage mechanism. The lifting device 7 can raise and lower the mounted working device.

[0060] A PTO shaft (power take-off shaft) 8 is protrudingly provided at the rear of the transmission case 5. The driving force transmitted from the PTO shaft 8 can drive the working device mounted on the lifting device 7.

[0061] The transmission case 5 has a flywheel housing 9 and a gearbox 10. The flywheel housing 9 accommodates the flywheels (first flywheel 13, second flywheel 14) described later, etc. The flywheel housing 9 is arranged at the front of the transmission case 5. Hereinafter, the flywheel housing 9 is sometimes referred to as the housing 9. The gearbox 10 accommodates the speed change device 16 described later, etc. The gearbox 10 is arranged at the rear of the transmission case 5.

[0062] <Power transmission mechanism>

[0063] like Figure 2 As shown in FIG. 1 , a power transmission mechanism 6 is disposed inside the transmission case 5. The power transmission mechanism 6 is a mechanism for transmitting the rotational power of the engine 4 to the Figure 1 The shown mechanism is transmitted by the travel device 3 and the PTO shaft 8.

[0064] The power transmission mechanism 6 includes a first power transmission part 11 and a second power transmission part 12. The first power transmission part 11 is arranged inside the flywheel housing 9. The second power transmission part 12 is arranged inside the gearbox 10. The first power transmission part 11 receives the rotational power of the engine 4 and transmits it to the second power transmission part 12. The second power transmission part 12 transmits the rotational power transmitted from the first power transmission part 11 to the travel device 3 and the PTO shaft 8.

[0065] Figure 3 to Figure 8 Various embodiments of the first power transmission unit 11 are shown. Figure 3 A first embodiment of the first power transmission unit 11 is shown. Figure 4 A second embodiment of the first power transmission unit 11 is shown. Figure 5 A third embodiment of the first power transmission unit 11 is shown. Figure 6 A fourth embodiment of the first power transmission unit 11 is shown. Figure 7 A fifth embodiment of the first power transmission unit 11 is shown. Figure 8 A sixth embodiment of the first power transmission unit 11 is shown.

[0066] <First power transmission unit (basic structure)>

[0067] Next, the structure of the first power transmission unit 11 will be described.

[0068] First, the structure of the first power transmission unit 11 that is common to all the embodiments (first to sixth embodiments) (the basic structure of the first power transmission unit 11 ) will be described.

[0069] like Figure 2 to Figure 8 As shown, the first power transmission unit 11 includes a first flywheel 13 and a second flywheel 14. The first flywheel 13 and the second flywheel 14 receive the rotational power of the engine 4 and rotate.

[0070] The second flywheel 14 is formed in a disk shape. The second flywheel 14 is connected to the output shaft (crankshaft) 4a of the engine 4. Therefore, the second flywheel 14 rotates at the same speed as the speed of the engine 4. In addition, in this specification, "speed" refers to the number of revolutions per unit time (for example, rpm).

[0071] The first flywheel 13 is configured to be cylindrical and has a through hole 13d that penetrates the first flywheel 13 in the front-to-back direction. Specifically, the first flywheel 13 has an outer cylinder portion 13a, an inner cylinder portion 13b, and a connecting portion 13c. The outer cylinder portion 13a is a cylindrical portion that includes the outer peripheral surface of the first flywheel 13. The inner cylinder portion 13b is a cylindrical portion that includes the inner peripheral surface of the first flywheel 13, and is arranged on the inner side (inner peripheral side) of the outer cylinder portion 13a. The inner peripheral side of the inner cylinder portion 13b is a through hole 13d. The connecting portion 13c is formed in the shape of a disk that connects the outer cylinder portion 13a and the inner cylinder portion 13b.

[0072] Alternatively, the first flywheel 13 may be composed of only the outer cylinder 13a of the outer cylinder 13a, the inner cylinder 13b, and the connecting portion 13c. In this case, the portion corresponding to the inner cylinder 13b and the connecting portion 13c is composed of a component different from the first flywheel 13, and the different component is connected to the outer cylinder 13a and rotates integrally.

[0073] The relay shaft 17 is inserted through the through hole 13d of the first flywheel 13. The relay shaft 17 extends in the front-rear direction through the center of the first flywheel 13. The relay shaft 17 relays between the second flywheel 14 and the speed change device 16. The inner cylinder portion 13b is supported by a bearing provided on the relay shaft 17. Thus, the inner cylinder portion 13b is supported to be rotatable relative to the relay shaft 17. Thus, the first flywheel 13 can rotate around the axis of the relay shaft 17 independently of the relay shaft 17.

[0074] In addition, the inner cylinder portion 13b may be directly supported by a bearing provided on the relay shaft 17, or may be indirectly supported by a bearing provided on the relay shaft 17 via other components. In the latter case, the first flywheel 13 and other components (the support member 65 described later (see Fig.11 ) etc.), and the other components are supported by the relay shaft 17 via bearings.

[0075] The first flywheel 13 is disposed between the second flywheel 14 and the transmission 16 in the axial length direction (front-rear direction) of the output shaft 4a. The first flywheel 13 receives the rotational power of the engine 4 via the first flywheel 13 and a speed increasing mechanism 20 described later and rotates.

[0076] A first rotation speed sensor 18 for measuring the rotation speed of the first flywheel 13 is provided near the first flywheel 13. A second rotation speed sensor 15 for measuring the rotation speed of the second flywheel 14 (= the rotation speed of the engine 4) is provided near the second flywheel 14.

[0077] The first power transmission unit 11 includes a first power transmission path 31 and a second power transmission path 32 .

[0078] The first power transmission path 31 is a path for transmitting the rotational power of the engine 4 to the first flywheel 13. The second power transmission path 32 is a path for transmitting the rotational power of the first flywheel 13 to the transmission 16.

[0079] The first power transmission path 31 and the second power transmission path 32 are independent paths. Therefore, when the rotational power of the engine 4 is transmitted to the first flywheel 13, the rotational power of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31 instead of the second power transmission path 32. In addition, when the rotational power of the first flywheel 13 is transmitted to the speed change device 16, the rotational power of the first flywheel 13 is transmitted to the speed change device 16 via the second power transmission path 32 instead of the first power transmission path 31.

[0080] The first power transmission unit 11 includes a clutch device 25 including a first clutch 26 and a second clutch 27. The first clutch 26 is provided on a first power transmission path 31. The second clutch 27 is provided on a second power transmission path 32.

[0081] The first power transmission path 31 is a path that passes through the first clutch 26 but does not pass through the second clutch 27. The second power transmission path 32 is a path that passes through the second clutch 27 but does not pass through the first clutch 26.

[0082] The first clutch 26 interrupts (interrupts (OFF) or connects (ON)) the transmission of the rotational power from the engine 4 to the first flywheel 13. The second clutch 27 interrupts (interrupts or connects) the transmission of the rotational power from the first flywheel 13 to the transmission 16.

[0083] The first clutch 26 and the second clutch 27 are hydraulic clutches that are operated by supplying hydraulic oil. The first clutch 26 includes a first friction plate 26A, a second friction plate 26B, and a hydraulic piston. The second clutch 27 includes a first friction plate 27A, a second friction plate 27B, and a hydraulic piston. By driving the hydraulic piston, the first friction plates 26A and 27A can be moved, and the first friction plates 26A and 27A and the second friction plates 26B and 27B can be switched between a pressed state and a separated state.

[0084] In the first to sixth embodiments, the first friction plate 26A is pressed against or separated from the second friction plate 26B, and the first friction plate 27A is pressed against or separated from the second friction plate 27B. However, in each embodiment, the second friction plate 26B may be pressed against or separated from the first friction plate 26A, and the second friction plate 27B may be pressed against or separated from the first friction plate 27A.

[0085] The first clutch 26 is connected when the first friction plates 26A and the second friction plates 26B are in a pressure-contact state, and is disconnected when the first friction plates 26A and the second friction plates 26B are in a separated state. The second clutch 27 is connected when the first friction plates 27A and the second friction plates 27B are in a pressure-contact state, and is disconnected when the first friction plates 27A and the second friction plates 27B are in a separated state.

[0086] The first clutch 26 and the second clutch 27 each have a hydraulic control valve (not shown) for controlling the supply of working oil to the oil chamber of the hydraulic piston. The hydraulic control valve is composed of a solenoid valve controlled by the supply of electric current. The hydraulic control valve is composed of, for example, a proportional valve whose opening varies according to the current value. By supplying electric current to the hydraulic control valve, the opening and closing of the hydraulic control valve is controlled, and the supply of working oil to the oil chamber of the hydraulic piston is controlled. In this way, the action of the hydraulic piston is controlled, and the intermittent operation of the first clutch 26 and the second clutch 27 is controlled.

[0087] The first friction plates 26A and 27A are urged by springs in a return direction (a direction away from the second friction plates 26B and 27B), and when hydraulic oil is supplied to the oil chamber of the hydraulic piston, they move against the urging force of the springs and approach the second friction plates 26B and 27B.

[0088] When the first clutch 26 and the second clutch 27 are connected, first, a set amount of working oil that is balanced with the force of the spring is supplied once, thereby increasing the pressure of the working oil in the oil chamber of the piston (hereinafter referred to as the "preparation state for connection"). Then, in the preparation state for connection, when the conditions for connecting the first clutch 26 and the second clutch 27 are met, working oil with a pressure that can press the first friction plates 26A and 27A against the second friction plates 26B and 27B is continuously supplied. Thus, the first clutch 26 and the second clutch 27 are connected. That is, the connection state is transferred from the preparation state for connection. In this way, when the clutches (the first clutch 26 and the second clutch 27) are connected, the connection state is transferred after the preparation state for connection, thereby improving the responsiveness of the clutch connection.

[0089] In order to supply a set amount of hydraulic oil that is balanced with the force of the spring at a time, a single current (single-shot pulse current) is supplied to the hydraulic control valve (solenoid valve). That is, when the single-shot pulse current is supplied to the hydraulic control valve, a set amount of hydraulic oil that is balanced with the force of the spring is supplied at a time, and the connection preparation state is achieved.

[0090] Hereinafter, supplying a one-shot pulse current is referred to as one-shot execution. Also, the number of times the one-shot pulse current is supplied is referred to as one-shot execution number or the number of attempts to connect the clutch (the first clutch 26 or the second clutch 27).

[0091] like Figure 3 As shown, a first pressure sensor 28 is provided on the first clutch 26 , and a second pressure sensor 29 is provided on the second clutch 27 .

[0092] exist Figures 4 to 8 Although the first pressure sensor 28 and the second pressure sensor 29 are omitted in the second to sixth embodiments, the first pressure sensor 28 and the second pressure sensor 29 are provided in the second to sixth embodiments as in the first embodiment. Figures 4 to 8 Although the first rotation speed sensor 18 and the second rotation speed sensor 15 are omitted in the second to sixth embodiments, the first rotation speed sensor 18 and the second rotation speed sensor 15 are provided in the second to sixth embodiments as in the first embodiment.

[0093] The first pressure sensor 28 detects the pressure of the working oil in the oil circuit for supplying the working oil to the hydraulic piston of the first clutch 26 (the working pressure of the oil circuit piston). The second pressure sensor 29 detects the pressure of the working oil in the oil circuit for supplying the working oil to the hydraulic piston of the second clutch 27 (the working pressure of the oil circuit piston). The states (connected state, disconnected state) of the first clutch 26 and the second clutch 27 can be understood by the pressure of the working oil detected by the first pressure sensor 28 and the second pressure sensor 29.

[0094] like Figure 3 to Figure 8 As shown, the speed increasing mechanism 20 is provided on the first power transmission path 31. That is, the first power transmission path 31 is a path passing through the speed increasing mechanism 20. On the other hand, the second power transmission path 32 is a path not passing through the speed increasing mechanism 20. However, the speed increasing mechanism 20 may not be provided on the first power transmission path 31.

[0095] The speed increasing mechanism 20 is a mechanism for increasing the speed of the rotational power of the engine 4 and transmitting it to the first flywheel 13. The speed increasing mechanism 20 is composed of a planetary gear mechanism including a sun gear 21, planetary gears 22 and a ring gear 23. The ring gear 23 is fixed to the flywheel housing 9. Therefore, the ring gear 23 cannot rotate. The planetary gears 22 mesh with the internal teeth of the ring gear 23. The sun gear 21 meshes with the planetary gears 22. The sun gear 21 can rotate around the axis of the relay shaft 17. The planetary gears 22 can rotate (revolve) along the sun gear 21.

[0096] Fig. 9 It is a collinear diagram of the planetary gear mechanism constituting the speed increasing mechanism 20 . Fig. 9 The vertical axis is the rotation speed (rotation speed). Fig. 9 As shown by the arrow B, according to the planetary gear mechanism constituting the speed increasing mechanism 20, the rotational power input from the planetary gear 22 can be accelerated and output from the sun gear 21. The speed increasing ratio of the speed increasing mechanism 20 is a value exceeding 1 (i.e., the speed increasing ratio>1), preferably set to 2 or more, and more preferably set to 3 or more. As an example, the speed increasing ratio can be set in the range of 3 to 5.

[0097] The rotational power of the engine 4 is input into the planetary gear 22 of the speed increasing mechanism 20, transmitted from the planetary gear 22 to the sun gear 21, and then transmitted from the sun gear 21 to the first flywheel 13. Thus, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. As a result, the rotational speed of the first flywheel 13 is greater than the rotational speed (actual rotational speed) of the engine 4. (Hereinafter, unless otherwise specified, the rotational speed of the engine 4 refers to the actual rotational speed of the engine 4.) As a result, a large amount of rotational energy can be accumulated in the first flywheel 13.

[0098] As described above, by providing the speed increasing mechanism 20 on the first power transmission path 31 , the first power transmission path 31 can increase the speed of the rotational power of the engine 4 via the speed increasing mechanism 20 and transmit the rotational power to the first flywheel 13 .

[0099] On the other hand, the speed increasing mechanism 20 is not provided on the second power transmission path 32. Assuming that the second power transmission path 32 is set as a path via the speed increasing mechanism 20 provided on the first power transmission path 31, the speed increasing mechanism 20 functions as a speed reducing mechanism. Specifically, the rotational power of the first flywheel 13 is input to the sun gear 21 and transmitted to the first flywheel 13 via the planetary gear 22. Therefore, the rotational power of the first flywheel 13 is decelerated and transmitted to the speed change device 16. In contrast, in the case of an embodiment of the present invention, since the speed increasing mechanism 20 is not provided on the second power transmission path 32, the rotational power of the first flywheel 13 is not decelerated and transmitted to the speed change device 16. Therefore, it can be said that the speed reducing mechanism is not provided on the second power transmission path 32.

[0100] In this way, since no speed reduction mechanism is provided on the second power transmission path 32, the second power transmission path 32 transmits the rotational power of the first flywheel 13 to the speed change device 16 without passing through the speed reduction mechanism. Therefore, the second power transmission path 32 can transmit the rotational power of the first flywheel 13 to the speed change device 16 without speed reduction.

[0101] In the first to sixth embodiments, no mechanism is provided on the second power transmission path 32 to increase the rotational power of the first flywheel 13 and transmit it to the transmission 16. Therefore, the rotation speed of the first flywheel 13 is equal to the rotation speed of the input shaft 16a of the transmission 16.

[0102] To summarize, “the first power transmission path 31 and the second power transmission path 32 are independent paths” can be specifically said to be “the first power transmission path 31 is a path passing through the speed increasing mechanism 20, and in contrast, the second power transmission path 32 is a path not passing through the speed increasing mechanism 20 provided on the first power transmission path 31”.

[0103] However, a speed increasing mechanism different from the speed increasing mechanism 20 provided on the first power transmission path 31 (a speed increasing mechanism independent of the speed increasing mechanism 20) may be provided on the second power transmission path 32. In this case, the second power transmission path 32 can increase the speed of the rotational power of the first flywheel 13 and transmit it to the speed change device 16. Therefore, the speed of the input shaft 16a of the input speed change device 16 becomes higher than the speed of the first flywheel 13.

[0104] like Figure 3 to Figure 8 As shown, the first power transmission unit 11 has a third power transmission path 33 .

[0105] The third power transmission path 33 is a path for transmitting the rotational power of the engine 4 to the speed change device 16 without passing through the first flywheel 13. In addition, the third power transmission path 33 is a path for transmitting the rotational power of the engine 4 to the speed change device 16 without passing through any of the first clutch 26 and the second clutch 27. That is, no clutch for interrupting the path is provided on the third power transmission path 33. Therefore, the third power transmission path 33 always connects the output shaft 4a of the engine 4 and the input shaft 16a of the speed change device 16.

[0106] The third power transmission path 33 includes a relay shaft 17 between the output shaft 4a of the engine 4 and the speed change device 16. The relay shaft 17 passes through the through hole 13d of the first flywheel 13. Therefore, the third power transmission path 33 is formed by passing through the through hole 13d of the first flywheel 13. The third power transmission path 33 connects the output shaft 4a of the engine 4 and the input shaft 16a of the speed change device 16 in a straight line via the second flywheel 14 and the relay shaft 17.

[0107] One end (front end) of the relay shaft 17 is connected to the second flywheel 14. The other end (rear end) of the relay shaft 17 is connected to the input shaft 16a of the transmission 16. Thus, the relay shaft 17 connects the second flywheel 14 and the transmission 16.

[0108] like Figure 2 As shown, the first flywheel 13, the second flywheel 14, the first clutch 26, and the second clutch 27 are accommodated inside the flywheel housing 9. The flywheel housing 9 has a first wall 9a, a second wall 9b, and a peripheral wall 9c. The first wall 9a and the second wall 9b are arranged relative to each other. The first wall 9a is arranged on the engine 4 side (front side). The second flywheel 14 is arranged near the inner surface (rear surface) of the first wall 9a. The second wall 9b is arranged on the speed change device 16 side (rear side). The speed change device 16 is arranged near the outer surface (rear surface) of the second wall 9b. The peripheral wall 9c connects the first wall 9a and the second wall 9b. The peripheral wall 9c is arranged in a manner to surround the first flywheel 13, the second flywheel 14, the first clutch 26, and the second clutch 27 (outer peripheral side).

[0109] The first flywheel 13 can rotate independently of the second flywheel 14. Specifically, in a state where the first clutch 26 and the second clutch 27 are disconnected, the first flywheel 13 can rotate independently of the second flywheel 14. In a state where the first clutch 26 and the second clutch 27 are disconnected, once the first flywheel 13 rotates, it can continue to rotate even when the second flywheel 14 stops.

[0110] The above is the basic structure of the first power transmission unit 11 (a structure common to all the embodiments).

[0111] Next, before describing the structure other than the basic structure of the first power transmission part 11 , the structure of the second power transmission part 12 will be described in order to understand the overall structure of the power transmission mechanism 6 .

[0112] <Second Power Transmission Unit>

[0113] Below, refer to Figure 2 The structure of the second power transmission unit 12 will be described.

[0114] The second power transmission unit 12 includes a speed change device 16 .

[0115] The transmission 16 is a hydrostatic continuously variable transmission (HST). The transmission 16 has a hydraulic pump P1 and a hydraulic motor M1. The hydraulic pump P1 and the hydraulic motor M1 are connected by an oil circuit (circulating oil circuit) through which the working oil flows. The hydraulic pump P1 is a variable capacity pump capable of changing the discharge amount of the working oil. The hydraulic pump P1 is driven by power input from an input shaft 16a of the transmission 16 to discharge the working oil. The hydraulic motor M1 is driven by the working oil discharged from the hydraulic pump P1. The hydraulic motor M1 can adjust the driving speed steplessly by increasing or decreasing the amount of working oil supplied from the hydraulic pump P1.

[0116] The rotational power is transmitted from the first power transmission unit 11 to the speed change device 16. The speed change device 16 selectively receives the rotational power of the engine 4 and the rotational power of the engine 4 and the first flywheel 13, changes the speed of the rotational power and outputs it. That is, the speed change device 16 receives the rotational power of the engine 4, changes the speed of the rotational power and outputs it, and receives the rotational power of the engine 4 and the first flywheel 13, changes the speed of the rotational power and outputs it.

[0117] Specifically, when the second clutch 27 is disconnected, the speed change device 16 receives only the rotational power of the engine 4, changes the speed, and outputs it. At this time, the rotational power of the engine 4 is transmitted via the third power transmission path 33. When the second clutch 27 is connected, the speed change device 16 receives the rotational power of the engine 4 and the first flywheel 13, changes the speed, and outputs it. At this time, the rotational power of the engine 4 is transmitted via the third power transmission path 33, and the rotational power of the first flywheel 13 is transmitted via the second power transmission path 32.

[0118] The transmission 16 includes a first output shaft 16b and a second output shaft 16c. The first output shaft 16b is a shaft for outputting power to the PTO shaft 8. The second output shaft 16c is a shaft for outputting power to the travel device 3.

[0119] The second power transmission unit 12 includes a clutch unit 41 and a speed change unit 42 .

[0120] The clutch unit 41 includes a PTO clutch 43 .

[0121] The PTO clutch 43 can intermittently output the rotational power output from the first output shaft 16b. When the PTO clutch 43 is connected, the rotational power output from the first output shaft 16b can be taken out from the first transmission shaft 44, and the PTO shaft 8 is rotated by the taken out rotational power. When the PTO clutch 43 is disconnected, the rotational power output from the first output shaft 16b is not taken out from the first transmission shaft 44, so the rotation of the PTO shaft 8 stops.

[0122] The speed change portion 42 includes a PTO speed change portion 45 and a travel speed change portion 46 .

[0123] The PTO speed change unit 45 can change the speed of the rotational power taken out from the first transmission shaft 44 and output it to the PTO shaft 8. The first torque sensor 35 is provided between the PTO speed change unit 45 and the PTO shaft 8. The first torque sensor 35 can detect the torque acting on the PTO shaft 8.

[0124] A power relay unit 40 is provided between the travel speed change unit 46 and the second output shaft 16c. The power relay unit 40 transmits the power output from the second output shaft 16c to the travel speed change unit 46. A second torque sensor 36 is provided on the second transmission shaft 50 that takes out the power from the power relay unit 40. The second torque sensor 36 can detect the torque acting on the second transmission shaft 50.

[0125] The travel speed change unit 46 changes the speed of the rotational power transmitted from the second output shaft 16c of the transmission 16 via the second transmission shaft 50 and transmits it to the travel device 3. The travel speed change unit 46 is provided with a third rotation speed sensor 37. The third rotation speed sensor 37 can detect the rotation speed of the rotational power transmitted to the travel device 3.

[0126] The travel speed change unit 46 includes a gear change mechanism 48 and a differential gear 49. The gear change mechanism 48 can change the speed of the rotational power taken out from the second transmission shaft 50 and transmit it to the differential gear 49. The differential gear 49 transmits the rotational power transmitted from the gear change mechanism 48 to the rear wheels 3R ​​of the travel device 3.

[0127] <First Power Transmission Unit (Specific Structure)>

[0128] Next, the specific structure of the first power transmission unit 11 will be described.

[0129] The specific structure of the first power transmission unit 11 is Figure 3 to Figure 8 Since there are different parts in the first to sixth embodiments shown, each embodiment will be described.

[0130] <First Embodiment>

[0131] First, based on Figure 3 The specific structure of the first power transmission part 11 of the first embodiment will be described. Hereinafter, the first power transmission part 11 of the first embodiment will be referred to as a "first power transmission part 11A".

[0132] In the first power transmission unit 11A, the first clutch 26 and the second clutch 27 are arranged in the axial length direction (front-rear direction) of the relay shaft 17. The first clutch 26 is arranged on the second flywheel 14 side (front side). The second clutch 27 is arranged on the speed change device 16 side (rear side). The first clutch 26 is arranged near the first wall 9a of the flywheel housing 9. The second clutch 27 is arranged near the second wall 9b of the flywheel housing 9. In addition, the second clutch 27 is arranged on the inner peripheral side of the first flywheel 13.

[0133] The first clutch 26 is a single-plate clutch having a first friction plate 26A and a second friction plate 26B. The first friction plate 26A is formed in a disk shape or an annular shape. The second friction plate 26B is formed in an annular shape.

[0134] The first friction plate 26A of the first clutch 26 is mounted on one end side (the second flywheel 14 side) of the relay shaft 17 and is movable along the axial length direction of the relay shaft 17. The second friction plate 26B of the first clutch 26 is mounted on the planetary gear 22 of the speed increasing mechanism 20.

[0135] The second clutch 27 is also a single-plate clutch, and has a first friction plate 27A and a second friction plate 27B. The first friction plate 27A is formed in a disk shape or an annular shape. The second friction plate 27B is formed in an annular shape.

[0136] The first friction plate 27A of the second clutch 27 is mounted on the other end side (speed change device 16 side) of the relay shaft 17 and is movable along the axial length direction of the relay shaft 17. The second friction plate 27B of the second clutch 27 is mounted on the first flywheel 13.

[0137] The first power transmission path 31 of the first power transmission unit 11A transmits the rotational power of the engine 4 to the second flywheel 14 , the relay shaft 17 , the first clutch 26 , the planetary gear 22 , the sun gear 21 in sequence, and then to the first flywheel 13 .

[0138] The second power transmission path 32 of the first power transmission unit 11A is a path for transmitting the rotational power of the first flywheel 13 to the second clutch 27 and the relay shaft 17 in sequence, and then to the speed change device 16 .

[0139] The third power transmission path 33 of the first power transmission portion 11A is a path for transmitting the rotational power of the engine 4 to the speed change device 16 via the relay shaft 17 .

[0140] Next, the operation of the first power transmission unit 11A will be described.

[0141] The rotational power output from the output shaft 4a of the engine 4 is transmitted to the second flywheel 14. As a result, the second flywheel 14 rotates, and the relay shaft 17 connected to the second flywheel 14 also rotates. At this time, the rotation speed of the engine 4, the rotation speed of the second flywheel 14, and the rotation speed of the relay shaft 17 are the same. The rotational power transmitted from the output shaft 4a to the relay shaft 17 is transmitted from the relay shaft 17 to the input shaft 16a of the speed change device 16.

[0142] Thus, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the transmission 16 via the relay shaft 17 constituting the third power transmission path 33. The rotational power is always transmitted via the third power transmission path 33 regardless of the intermittent operation of the first clutch 26 and the second clutch 27.

[0143] When the first clutch 26 is in the connected state and the second clutch 27 is in the disconnected state, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31. Specifically, the rotational power transmitted from the output shaft 4a of the engine 4 to the second flywheel 14 and the relay shaft 17 is transmitted from the first friction plate 26A of the first clutch 26 to the second friction plate 26B. As a result, the planetary gear 22 rotates, and the sun gear 21 rotates with the rotation of the planetary gear 22. Then, since the sun gear 21 is connected to the first flywheel 13, the first flywheel 13 rotates together with the sun gear 21. In this way, the rotational power of the engine 4 is transmitted to the first flywheel 13 via the first clutch 26 and the speed increasing mechanism 20.

[0144] Here, the rotational power of the engine 4 is accelerated when being transmitted from the planetary gear 22 to the sun gear 21. Therefore, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. Thus, the first flywheel 13 rotates at a rotational speed greater than the rotational speed of the engine 4. As a result, high rotational energy can be accumulated in the first flywheel 13.

[0145] When the first clutch 26 is in the disconnected state and the second clutch 27 is in the connected state, the rotational power of the first flywheel 13 is transmitted to the speed change device 16 via the second power transmission path 32. Specifically, the rotational power of the first flywheel 13 is transmitted from the second friction plate 27B of the second clutch 27 to the first friction plate 27A. Thus, the rotational power of the first flywheel 13 is transmitted from the first friction plate 27A to the relay shaft 17, and from the relay shaft 17 to the input shaft 16a of the speed change device 16. At this time, the rotational power of the first flywheel 13 is transmitted to the input shaft 16a of the speed change device 16 without being reduced (not via a reduction mechanism).

[0146] According to the power transmission mechanism 6 including the first power transmission portion 11A, the following effects can be achieved.

[0147] By connecting the first clutch 26 and disconnecting the second clutch 27, the rotational power of the engine 4 can be increased in speed and transmitted to the first flywheel 13. Therefore, high rotational energy can be accumulated in the first flywheel 13.

[0148] In addition, by setting the first clutch 26 to the disconnected state and the second clutch 27 to the connected state, the rotational power of the first flywheel 13 can be transmitted to the speed change device 16 without deceleration. Therefore, the high rotational energy accumulated in the first flywheel 13 can be transmitted to the speed change device 16. At this time, the rotational power output from the output shaft 4a of the engine 4 can also be transmitted to the speed change device 16 via the third power transmission path 33. Thus, the rotational power of the engine 4 and the rotational power of the first flywheel 13 are both transmitted to the speed change device 16. Therefore, when the load of the working device connected to the PTO shaft 8 increases and the rotational power of the engine 4 is insufficient, the rotational power of the engine 4 can be effectively assisted by the rotational power of the first flywheel 13. Thus, it is possible to prevent or suppress the rotation speed of the engine 4 from decreasing when the load of the working device connected to the PTO shaft 8 increases.

[0149] The first power transmission parts 11 of the first to sixth embodiments each have unique features, but the features of the first power transmission part 11A of the first embodiment are as follows.

[0150] In the case of the first power transmission unit 11A of the first embodiment, the first clutch 26 is arranged near the first wall 9a of the flywheel housing 9, and the second clutch 27 is arranged near the second wall 9b of the flywheel housing 9. Therefore, an oil path for supplying working oil to the first clutch 26 can be provided along the first wall 9a, and an oil path for supplying working oil to the second clutch 27 can be provided along the second wall 9b. As a result, it is easy to provide an oil path for supplying working oil to the first clutch 26 and the second clutch 27. That is, the oil path is excellent in establishment.

[0151] In addition, by providing a bearing on the first wall 9a of the flywheel housing 9, one end side of the relay shaft 17 is rotatably supported. In addition, by providing a bearing on the second wall 9b of the flywheel housing 9, the other end side of the relay shaft 17 or the input shaft 16a of the speed change device 16 connected to the other end side is rotatably supported. Thus, both end sides of the relay shaft 17 can be reliably and easily supported in a rotatable manner. That is, the shaft support is excellent in establishment.

[0152] In addition, since the first clutch 26 and the second clutch 27 are formed of a single-plate clutch, the clutch and the structure associated with the clutch can be simplified, and the number of components can be reduced. In other words, the present invention is excellent in that the number of components can be reduced.

[0153] <Second Embodiment>>

[0154] Next, based on Figure 4 The specific structure of the first power transmission part 11 of the second embodiment will be described. Hereinafter, the first power transmission part 11 of the second embodiment will be referred to as a "first power transmission part 11B".

[0155] In the first power transmission unit 11B, the first clutch 26 and the second clutch 27 are arranged on the side (rear side) of the transmission 16 in the axial length direction (front-rear direction) of the relay shaft 17. The first clutch 26 and the second clutch 27 are arranged in a staggered manner in the front-rear direction. Specifically, the first clutch 26 is arranged in front of the second clutch 27. The rear portion of the first clutch 26 and the front portion of the second clutch 27 are located at a position where they overlap in the front-rear direction.

[0156] The first clutch 26 is disposed on the outer circumference side (the side away from the relay shaft 17 ). The second clutch 27 is disposed on the inner circumference side (the side close to the relay shaft 17 ). That is, the second clutch 27 is disposed on the inner circumference side than the first clutch 26 .

[0157] The first clutch 26 is disposed on the inner peripheral side of the first flywheel 13. The first clutch 26 is located at a position overlapping the first flywheel 13 in the front-rear direction. Only the front portion of the second clutch 27 is located at a position overlapping the first flywheel 13 in the front-rear direction.

[0158] The first clutch 26 is disposed on the inner circumference side of the speed increasing mechanism 20 (the inner circumference side of the sun gear 21 ). The second clutch 27 is disposed in front of the speed increasing mechanism 20 .

[0159] The first clutch 26 is a multi-plate clutch having a plurality of first friction plates 26A and a plurality of second friction plates 26B. The first friction plates 26A and the second friction plates 26B are arranged alternately in the front-rear direction. The first friction plates 26A and the second friction plates 26B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 26A and the second friction plates 26B.

[0160] The first friction plate 26A is mounted on the first flywheel 13. The first friction plate 26A is movable along the axial length direction of the relay shaft 17. The second friction plate 26B is mounted on the sun gear 21 of the speed increasing mechanism 20.

[0161] The second clutch 27 is also a multi-plate clutch, and has a plurality of first friction plates 27A and a plurality of second friction plates 27B. The first friction plates 27A and the second friction plates 27B are arranged alternately in the front-rear direction. The first friction plates 27A and the second friction plates 27B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 27A and the second friction plates 27B.

[0162] The first friction plate 27A is mounted on the first flywheel 13. The first friction plate 27A is movable along the axial length direction of the relay shaft 17. The second friction plate 27B is connected to the planetary gear 22 of the speed increasing mechanism 20.

[0163] The first power transmission path 31 of the first power transmission unit 11B transmits the rotational power of the engine 4 to the second flywheel 14 , the relay shaft 17 , the planetary gear 22 , the sun gear 21 , the first clutch 26 in sequence, and then to the first flywheel 13 .

[0164] The second power transmission path 32 of the first power transmission portion 11B is a path for transmitting the rotational power of the first flywheel 13 to the speed change device 16 via the second clutch 27 .

[0165] The third power transmission path 33 of the first power transmission unit 11B transmits the rotational power of the engine 4 to the transmission 16 via the relay shaft 17. The third power transmission path 33 transmits the rotational power of the engine 4 to the transmission 16 without passing through either the first clutch 26 or the second clutch 27.

[0166] Next, the operation of the first power transmission unit 11B will be described.

[0167] The rotational power output from the output shaft 4a of the engine 4 is transmitted to the second flywheel 14. As a result, the second flywheel 14 rotates, and the relay shaft 17 connected to the second flywheel 14 also rotates. At this time, the rotation speed of the engine 4, the rotation speed of the second flywheel 14, and the rotation speed of the relay shaft 17 are the same. The rotational power transmitted to the relay shaft 17 is transmitted to the input shaft 16a of the speed change device 16.

[0168] Thus, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the transmission 16 via the third power transmission path 33. The rotational power is always transmitted via the third power transmission path 33 regardless of whether the first clutch 26 and the second clutch 27 are disconnected.

[0169] When the first clutch 26 is in the connected state and the second clutch 27 is in the disconnected state, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31. Specifically, the rotational power transmitted from the engine 4 to the second flywheel 14 is transmitted from the second flywheel 14 to the planetary gear 22 via the relay shaft 17. As a result, the planetary gear 22 rotates, and the sun gear 21 rotates with the rotation of the planetary gear 22. The sun gear 21 is connected to the second friction plate 26B of the first clutch 26. Therefore, the rotational power of the sun gear 21 is transmitted to the second friction plate 26B, and is transmitted from the second friction plate 26B to the first flywheel 13 via the first friction plate 26A.

[0170] Here, the rotational power of the engine 4 is accelerated when being transmitted from the planetary gear 22 to the sun gear 21. That is, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. Therefore, the first flywheel 13 rotates at a rotation speed greater than the rotation speed of the engine 4. Thus, high rotational energy can be accumulated in the first flywheel 13.

[0171] In addition, when the first clutch 26 is in the disconnected state and the second clutch 27 is in the connected state, the second power transmission path 32 is connected, so the rotational power of the first flywheel 13 is transmitted to the speed change device 16. Specifically, the rotational power of the first flywheel 13 is transmitted from the first friction plate 27A of the second clutch 27 to the second friction plate 27B. As a result, the rotational power of the first flywheel 13 is transmitted from the second friction plate 27B to the input shaft 16a of the speed change device 16 via the relay shaft 17. At this time, the rotational power of the first flywheel 13 is transmitted to the input shaft 16a of the speed change device 16 without deceleration (not via the speed reduction mechanism). Therefore, the high rotational energy of the first flywheel 13 can be directly input to the speed change device 16.

[0172] When the first clutch 26 and the second clutch 27 are both in the disconnected state, since the first power transmission path 31 and the second power transmission path 32 are disconnected, the rotational power of the engine 4 is not transmitted to the first flywheel 13, and the rotational power of the first flywheel 13 is not transmitted to the speed change device 16.

[0173] The first power transmission unit 11B can achieve the same effects as those of the first power transmission unit 11A described above.

[0174] The features of the first power transmission portion 11B of the second embodiment are as follows.

[0175] Since the first clutch 26 and the second clutch 27 of the first power transmission unit 11B of the second embodiment are composed of a multi-plate clutch, high power transmission performance can be obtained between the first friction plates 26A, 27A and the second friction plates 26B, 27B. Therefore, the clutch device 25 has a superior power transmission performance compared to the first power transmission unit 1A.

[0176] In addition, since the clutch device 25 has excellent power transmission performance, power can be reliably transmitted to the first flywheel 13, and high rotational energy can be accumulated in the first flywheel 13. Therefore, the first flywheel 13 has excellent rotational energy accumulation performance compared with the first power transmission unit 1A.

[0177] <Third Embodiment>

[0178] Next, based on Figure 5The specific structure of the first power transmission part 11 of the third embodiment will be described. Hereinafter, the first power transmission part 11 of the third embodiment will be referred to as a "first power transmission part 11C".

[0179] In the first power transmission unit 11C, the first clutch 26 and the second clutch 27 are arranged in a radial direction (a direction away from the axis of the relay shaft 17) of the relay shaft 17. The first clutch 26 is arranged on the outer peripheral side (the side away from the relay shaft 17). The second clutch 27 is arranged on the inner peripheral side (the side close to the relay shaft 17). In other words, the second clutch 27 is arranged on the inner peripheral side of the first clutch 26. The first clutch 26 and the second clutch 27 are arranged near the second wall 9b of the flywheel housing 9. Specifically, the first clutch 26 and the second clutch 27 are arranged at a position facing the second wall 9b.

[0180] The first clutch 26 and the second clutch 27 are arranged between the first flywheel 13 and the speed change device 16 in the front-to-back direction. The first clutch 26 and the second clutch 27 are located at positions offset from the first flywheel 13 in the front-to-back direction. In other words, the first clutch 26 and the second clutch 27 do not overlap with the first flywheel 13 in the front-to-back direction. The outer diameter of the clutch device 25 composed of the first clutch 26 and the second clutch 27 is smaller than the outer diameter of the first flywheel 13.

[0181] The first clutch 26 is a multi-plate clutch having a plurality of first friction plates 26A and a plurality of second friction plates 26B. The plurality of first friction plates 26A and the plurality of second friction plates 26B of the first clutch 26 are arranged alternately in the front-rear direction. The first friction plates 26A and the second friction plates 26B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 26A and the second friction plates 26B.

[0182] The first friction plate 26A is mounted on the relay shaft 17 so as to be movable in the axial length direction of the relay shaft 17. The second friction plate 26B is mounted on the planetary gear 22 of the speed increasing mechanism 20.

[0183] The second clutch 27 is also a multi-plate clutch, and has a plurality of first friction plates 27A and a plurality of second friction plates 27B. The first friction plates 27A and the second friction plates 27B are arranged alternately in the front-rear direction. The first friction plates 27A and the second friction plates 27B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 27A and the second friction plates 27B.

[0184] The first friction plate 27A is mounted on the relay shaft 17 so as to be movable in the axial length direction of the relay shaft 17. The second friction plate 27B is mounted on the sun gear 21 of the speed increasing mechanism 20.

[0185] The first power transmission path 31 of the first power transmission unit 11C transmits the rotational power of the engine 4 to the second flywheel 14 , the relay shaft 17 , the first clutch 26 , the planetary gear 22 , the sun gear 21 in sequence, and then to the first flywheel 13 .

[0186] The second power transmission path 32 of the first power transmission unit 11C is a path that transmits the rotational power of the first flywheel 13 to the second clutch 27 and the relay shaft 17 in sequence, and then transmits it to the speed change device 16 .

[0187] The third power transmission path 33 of the first power transmission unit 11C transmits the rotational power of the engine 4 to the transmission 16 via the relay shaft 17. The third power transmission path 33 transmits the rotational power of the engine 4 to the transmission 16 without passing through either the first clutch 26 or the second clutch 27.

[0188] Next, the operation of the first power transmission unit 11C will be described.

[0189] The rotational power output from the output shaft 4a of the engine 4 is transmitted to the second flywheel 14. As a result, the second flywheel 14 rotates, and the relay shaft 17 connected to the second flywheel 14 also rotates. At this time, the rotation speed of the engine 4, the rotation speed of the second flywheel 14, and the rotation speed of the relay shaft 17 are the same. The rotational power transmitted from the output shaft 4a to the relay shaft 17 is transmitted from the relay shaft 17 to the input shaft 16a of the speed change device 16.

[0190] Thus, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the transmission 16 via the relay shaft 17 constituting the third power transmission path 33. The rotational power is always transmitted via the third power transmission path 33 regardless of the intermittent operation of the first clutch 26 and the second clutch 27.

[0191] When the first clutch 26 is in the connected state and the second clutch 27 is in the disconnected state, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31. Specifically, the rotational power transmitted from the output shaft 4a of the engine 4 to the second flywheel 14 and the relay shaft 17 is transmitted from the first friction plate 26A of the first clutch 26 to the second friction plate 26B. As a result, the planetary gear 22 rotates, and the sun gear 21 rotates with the rotation of the planetary gear 22. Then, since the sun gear 21 is connected to the first flywheel 13, the first flywheel 13 rotates together with the sun gear 21. In this way, the rotational power of the engine 4 is transmitted to the first flywheel 13 via the first clutch 26 and the speed increasing mechanism 20.

[0192] Here, the rotational power of the engine 4 is accelerated when being transmitted from the planetary gear 22 to the sun gear 21. That is, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. Therefore, the first flywheel 13 rotates at a rotation speed greater than the rotation speed of the engine 4. Thus, high rotational energy can be accumulated in the first flywheel 13.

[0193] When the first clutch 26 is in the disconnected state and the second clutch 27 is in the connected state, the rotational power of the first flywheel 13 is transmitted to the speed change device 16 via the second power transmission path 32. Specifically, the rotational power of the first flywheel 13 is transmitted from the second friction plate 27B of the second clutch 27 to the first friction plate 27A. Thus, the rotational power of the first flywheel 13 is transmitted from the first friction plate 27A to the relay shaft 17, and from the relay shaft 17 to the input shaft 16a of the speed change device 16. At this time, the rotational power of the first flywheel 13 is transmitted to the input shaft 16a of the speed change device 16 without being reduced (not via a reduction mechanism).

[0194] The first power transmission unit 11C can achieve the same effects as those of the first power transmission unit 11A described above.

[0195] The features of the first power transmission unit 11C of the third embodiment are as follows.

[0196] Since the first clutch 26 and the second clutch 27 of the first power transmission unit 11C of the third embodiment are composed of multiple-plate clutches, high power transmission performance can be obtained between the first friction plates 26A, 27A and the second friction plates 26B, 27B. That is, the clutch device 25 has excellent power transmission performance.

[0197] In addition, since the first clutch 26 and the second clutch 27 are arranged in a radial direction of the relay shaft 17, both the first clutch 26 and the second clutch 27 can be arranged near the second wall 9b of the flywheel housing 9. Therefore, an oil path for supplying working oil to the first clutch 26 and an oil path for supplying working oil to the second clutch 27 can be provided along the second wall 9b. Therefore, it is easy to provide an oil path for supplying working oil to the first clutch 26 and the second clutch 27. That is, the oil path is excellent in establishment.

[0198] In addition, by providing a bearing on the first wall 9a of the flywheel housing 9, one end side of the relay shaft 17 is supported in a rotatable manner. And, by providing a bearing on the second wall 9b of the flywheel housing 9, the other end side of the relay shaft 17 or the input shaft 16a of the speed change device 16 connected to the other end side is supported in a rotatable manner. Thus, both end sides of the relay shaft 17 can be reliably and easily supported in a rotatable manner. That is, the shaft support is excellent in establishment.

[0199] In addition, since the first clutch 26 and the second clutch 27 are arranged in the radial direction of the relay shaft 17 near the second wall 9b, the components for supporting the first clutch 26 and the second clutch 27 can be shared, and the number of components can be reduced.

[0200] <Fourth Embodiment>

[0201] Next, based on Figure 6 The specific structure of the first power transmission part 11 of the fourth embodiment will be described. Hereinafter, the first power transmission part 11 of the fourth embodiment will be referred to as a "first power transmission part 11D".

[0202] In the first power transmission unit 11D, the first clutch 26 and the second clutch 27 are arranged in the axial length direction (front-rear direction) of the relay shaft 17. The first clutch 26 is arranged at the rear part (speed change device 16 side) of the axial length direction of the relay shaft 17. The second clutch 27 is arranged at the front part (second flywheel 14 side) of the axial length direction of the relay shaft 17. The first clutch 26 is arranged near the second wall 9b of the flywheel housing 9. The second clutch 27 is arranged near the first wall 9a of the flywheel housing 9.

[0203] The outer diameters of the first clutch 26 and the second clutch 27 are smaller than the outer diameters of the first flywheel 13. The first clutch 26 and the second clutch 27 are arranged on the inner circumference of the first flywheel 13. Specifically, the first clutch 26 and the second clutch 27 are arranged on the inner circumference of the outer cylinder portion 13a of the first flywheel 13.

[0204] The first clutch 26 is disposed between the speed increasing mechanism 20 and the speed change device 16 in the front-rear direction. The speed increasing mechanism 20 is disposed between the first clutch 26 and the second clutch 27 in the front-rear direction.

[0205] At least a portion of the first clutch 26 and the second clutch 27 is located at a position overlapping the first flywheel 13 in the front-rear direction. Specifically, the first clutch 26 is located as a whole at a position overlapping the first flywheel 13 in the front-rear direction. The front portion of the second clutch 27 is located at a position overlapping the first flywheel 13 in the front-rear direction.

[0206] The first clutch 26 is a multi-plate clutch having a plurality of first friction plates 26A and a plurality of second friction plates 26B. The first friction plates 26A and the second friction plates 26B are arranged alternately in the front-rear direction. The first friction plates 26A and the second friction plates 26B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 26A and the second friction plates 26B.

[0207] The first friction plate 26A is mounted on the relay shaft 17 so as to be movable in the axial length direction of the relay shaft 17. The second friction plate 26B is mounted on the planetary gear 22 of the speed increasing mechanism 20.

[0208] The second clutch 27 is also a multi-plate clutch, and has a plurality of first friction plates 27A and a plurality of second friction plates 27B. The first friction plates 27A and the second friction plates 27B are arranged alternately in the front-rear direction. The first friction plates 27A and the second friction plates 27B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 27A and the second friction plates 27B.

[0209] The first friction plate 27A is mounted on the relay shaft 17 and is movable along the axial length direction of the relay shaft 17. The second friction plate 27B is mounted on the first flywheel 13.

[0210] The first power transmission path 31 of the first power transmission unit 11D transmits the rotational power of the engine 4 to the second flywheel 14 , the relay shaft 17 , the first clutch 26 , the planetary gear 22 , the sun gear 21 in sequence, and then to the first flywheel 13 .

[0211] The second power transmission path 32 of the first power transmission unit 11D is a path for transmitting the rotational power of the first flywheel 13 to the second clutch 27 and the relay shaft 17 in sequence, and then to the speed change device 16 .

[0212] The third power transmission path 33 of the first power transmission unit 11D transmits the rotational power of the engine 4 to the transmission 16 via the relay shaft 17. The third power transmission path 33 transmits the rotational power of the engine 4 to the transmission 16 without passing through either the first clutch 26 or the second clutch 27.

[0213] Next, the operation of the first power transmission unit 11D will be described.

[0214] The rotational power output from the output shaft 4a of the engine 4 is transmitted to the second flywheel 14. As a result, the second flywheel 14 rotates, and the relay shaft 17 connected to the second flywheel 14 also rotates. At this time, the rotation speed of the engine 4, the rotation speed of the second flywheel 14, and the rotation speed of the relay shaft 17 are the same. The rotational power transmitted from the output shaft 4a to the relay shaft 17 is transmitted from the relay shaft 17 to the input shaft 16a of the speed change device 16.

[0215] Thus, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the transmission 16 via the relay shaft 17 constituting the third power transmission path 33. The rotational power is always transmitted via the third power transmission path 33 regardless of the intermittent operation of the first clutch 26 and the second clutch 27.

[0216] When the first clutch 26 is in the connected state and the second clutch 27 is in the disconnected state, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31. Specifically, the rotational power transmitted from the output shaft 4a of the engine 4 to the second flywheel 14 and the relay shaft 17 is transmitted from the first friction plate 26A of the first clutch 26 to the second friction plate 26B. As a result, the planetary gear 22 rotates, and the sun gear 21 rotates with the rotation of the planetary gear 22. Then, since the sun gear 21 is connected to the first flywheel 13, the first flywheel 13 rotates together with the sun gear 21. In this way, the rotational power of the engine 4 is transmitted to the first flywheel 13 via the first clutch 26 and the speed increasing mechanism 20.

[0217] Here, the rotational power of the engine 4 is accelerated when being transmitted from the planetary gear 22 to the sun gear 21. That is, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. Therefore, the first flywheel 13 rotates at a rotation speed greater than the rotation speed of the engine 4. Thus, high rotational energy can be accumulated in the first flywheel 13.

[0218] When the first clutch 26 is in the disconnected state and the second clutch 27 is in the connected state, the rotational power of the first flywheel 13 is transmitted to the speed change device 16 via the second power transmission path 32. Specifically, the rotational power of the first flywheel 13 is transmitted from the second friction plate 27B of the second clutch 27 to the first friction plate 27A. Thus, the rotational power of the first flywheel 13 is transmitted from the first friction plate 27A to the relay shaft 17, and from the relay shaft 17 to the input shaft 16a of the speed change device 16. At this time, the rotational power of the first flywheel 13 is transmitted to the input shaft 16a of the speed change device 16 without being reduced (not via a reduction mechanism).

[0219] The first power transmission unit 11D can achieve the same effects as those of the first power transmission unit 11A described above.

[0220] The features of the first power transmission unit 11D of the fourth embodiment are as follows.

[0221] Since the first clutch 26 and the second clutch 27 of the first power transmission unit 11D of the fourth embodiment are composed of a multi-plate clutch, high power transmission performance can be obtained between the first friction plates 26A, 27A and the second friction plates 26B, 27B. That is, the clutch device 25 has excellent power transmission performance.

[0222] In addition, since the first clutch 26 and the second clutch 27 are composed of a multi-plate clutch and arranged in the axial length direction of the relay shaft 17, the outer diameter of the clutch device 25 can be reduced while maintaining high power transmission performance and arranged on the inner peripheral side of the first flywheel 13. As a result, the axial length (length in the front-to-back direction) of the first flywheel 13 can be extended, so the inertia moment of the first flywheel 13 can be increased, and the rotational energy that can be stored in the first flywheel 13 can be increased. That is, the first flywheel 13 has excellent storage performance of rotational energy.

[0223] In addition, since the first clutch 26 and the second clutch 27 are arranged in the axial length direction of the relay shaft 17, the outer diameter of the clutch device 25 composed of the first clutch 26 and the second clutch 27 can be reduced compared with the first power transmission parts 11B and 11C. As a result, the drag torque (friction torque that generates rotation) of the clutch device 25 can be reduced.

[0224] In addition, since the first clutch 26 is arranged near the second wall 9b and the second clutch 27 is arranged near the first wall 9a, an oil passage for supplying hydraulic oil to the first clutch 26 can be provided along the second wall 9b, and an oil passage for supplying hydraulic oil to the second clutch 27 can be provided along the first wall 9a. Therefore, it is easy to provide an oil passage for supplying hydraulic oil to the first clutch 26 and the second clutch 27. That is, the oil passage is excellent in establishment.

[0225] <Fifth Embodiment>

[0226] Next, based on Figure 7 The specific structure of the first power transmission part 11 of the fifth embodiment will be described. Hereinafter, the first power transmission part 11 of the fifth embodiment will be referred to as a "first power transmission part 11E".

[0227] A partition wall 9d is provided inside the flywheel housing 9 that accommodates the first power transmission unit 11E of the fifth embodiment. The partition wall 9d is provided between the first wall 9a and the second wall 9b. One surface of the partition wall 9d faces the first wall 9a. The other surface of the partition wall 9d faces the second wall 9b.

[0228] The partition wall 9d divides the interior of the flywheel housing 9 into a space 51 for accommodating the first flywheel 13 and a space 52 for accommodating the first clutch 26 and the second clutch 27. Hereinafter, the space 51 for accommodating the first flywheel 13 is referred to as the "first space 51", and the space 52 for accommodating the first clutch 26 and the second clutch 27 is referred to as the "second space 52".

[0229] The first space 51 is provided at the front part (the engine 4 side) of the flywheel housing 9. In the first space 51, the second flywheel 14 is accommodated in addition to the first flywheel 13. The second space 52 is provided at the rear part (the speed change device 16 side) of the flywheel housing 9. In the second space 52, in addition to the first clutch 26 and the second clutch 27, the speed increasing mechanism 20 is also accommodated.

[0230] In the first power transmission unit 11E, the first clutch 26 and the second clutch 27 are arranged in a radial direction (a direction away from the axis of the relay shaft 17) of the relay shaft 17. The first clutch 26 is arranged on the outer peripheral side (the side away from the relay shaft 17). The second clutch 27 is arranged on the inner peripheral side (the side close to the relay shaft 17). That is, the second clutch 27 is arranged on the inner peripheral side of the first clutch 26.

[0231] The first clutch 26 and the second clutch 27 are arranged near the partition wall 9d of the flywheel housing 9. Specifically, the first clutch 26 and the second clutch 27 are arranged at positions facing the partition wall 9d.

[0232] The first clutch 26 and the second clutch 27 are arranged between the first flywheel 13 and the speed change device 16 in the front-to-back direction. The first clutch 26 and the second clutch 27 are located at positions offset from the first flywheel 13 in the front-to-back direction. In other words, the first clutch 26 and the second clutch 27 do not overlap with the first flywheel 13 in the front-to-back direction. In addition, the first clutch 26 and the second clutch 27 are arranged between the first flywheel 13 and the speed increasing mechanism 20 in the front-to-back direction.

[0233] The first clutch 26 is a multi-plate clutch having a plurality of first friction plates 26A and a plurality of second friction plates 26B. The first friction plates 26A and the second friction plates 26B are arranged alternately in the front-rear direction. The first friction plates 26A and the second friction plates 26B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 26A and the second friction plates 26B.

[0234] The first friction plate 26A is mounted on the first flywheel 13. Specifically, the first friction plate 26A is connected to the first flywheel 13 via a support member 65 (see Fig.11 ) is mounted on the first flywheel 13. The first friction plate 26A is movable along the axial length direction of the relay shaft 17. The second friction plate 26B is mounted on the sun gear 21 of the speed increasing mechanism 20. Specifically, the second friction plate 26B is mounted via a mounting member 69 (see Fig.11 ) is installed on the sun gear 21.

[0235] The second clutch 27 is also a multi-plate clutch, and has a plurality of first friction plates 27A and a plurality of second friction plates 27B. The first friction plates 27A and the second friction plates 27B are arranged alternately in the front-rear direction. The first friction plates 27A and the second friction plates 27B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 27A and the second friction plates 27B.

[0236] The first friction plate 27A is mounted on the first flywheel 13. Specifically, the first friction plate 27A is connected to the first flywheel 13 via a support member 65 (see Fig.11 ) is mounted on the first flywheel 13. The first friction plate 27A can move along the axial length direction of the relay shaft 17. The second friction plate 27B is connected to the planetary gear 22 of the speed increasing mechanism 20. Specifically, the second friction plate 27B is connected to the planetary gear 22 via the connecting member 60 and the planetary carrier 24. The connecting member 60 connects the relay shaft 17 and the input shaft 16a of the speed change device 16. The planetary carrier 24 supports the planetary gear 22.

[0237] The first power transmission path 31 of the first power transmission unit 11E transmits the rotational power of the engine 4 to the second flywheel 14 , the relay shaft 17 , the connecting member 60 , the planetary carrier 24 , the planetary gear 22 , the sun gear 21 , the first clutch 26 in sequence, and then to the first flywheel 13 .

[0238] The second power transmission path 32 of the first power transmission unit 11E is a path for transmitting the rotational power of the first flywheel 13 to the second clutch 27 and the connecting member 60 in sequence, and then to the speed change device 16 .

[0239] The third power transmission path 33 of the first power transmission unit 11E transmits the rotational power of the engine 4 to the transmission 16 via the relay shaft 17 and the connector 60. The third power transmission path 33 transmits the rotational power of the engine 4 to the transmission 16 without passing through either the first clutch 26 or the second clutch 27.

[0240] Next, the operation of the first power transmission unit 11E will be described.

[0241] The rotational power output from the output shaft 4a of the engine 4 is transmitted to the second flywheel 14. As a result, the second flywheel 14 rotates, and the relay shaft 17 connected to the second flywheel 14 also rotates. At this time, the rotation speed of the engine 4, the rotation speed of the second flywheel 14, and the rotation speed of the relay shaft 17 are the same. The rotational power transmitted to the relay shaft 17 is transmitted to the input shaft 16a of the speed change device 16 via the connecting member 60.

[0242] Thus, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the transmission 16 via the third power transmission path 33. The rotational power is always transmitted via the third power transmission path 33 regardless of whether the first clutch 26 and the second clutch 27 are disconnected.

[0243] When the first clutch 26 is in the connected state and the second clutch 27 is in the disconnected state, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31. Specifically, the rotational power transmitted from the engine 4 to the second flywheel 14 is transmitted from the second flywheel 14 to the planetary gear 22 via the relay shaft 17, the connecting member 60, and the planetary carrier 24. As a result, the planetary gear 22 rotates, and the sun gear 21 rotates with the rotation of the planetary gear 22. The sun gear 21 is connected to the second friction plate 26B of the first clutch 26. Therefore, the rotational power of the sun gear 21 is transmitted to the second friction plate 26B, and is transmitted from the second friction plate 26B to the first flywheel 13 via the first friction plate 26A.

[0244] Here, the rotational power of the engine 4 is accelerated when being transmitted from the planetary gear 22 to the sun gear 21. That is, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. Therefore, the first flywheel 13 rotates at a rotation speed greater than the rotation speed of the engine 4. Thus, high rotational energy can be accumulated in the first flywheel 13.

[0245] In addition, when the first clutch 26 is in the disconnected state and the second clutch 27 is in the connected state, the second power transmission path 32 is connected, so the rotational power of the first flywheel 13 is transmitted to the speed change device 16. Specifically, the rotational power of the first flywheel 13 is transmitted from the first friction plate 27A of the second clutch 27 to the second friction plate 27B. As a result, the rotational power of the first flywheel 13 is transmitted from the second friction plate 27B to the input shaft 16a of the speed change device 16 via the connector 60. At this time, the rotational power of the first flywheel 13 is transmitted to the input shaft 16a of the speed change device 16 without deceleration (not via a speed reduction mechanism). Therefore, the high rotational energy of the first flywheel 13 can be directly input to the speed change device 16.

[0246] When the first clutch 26 and the second clutch 27 are both in the disconnected state, since the first power transmission path 31 and the second power transmission path 32 are disconnected, the rotational power of the engine 4 is not transmitted to the first flywheel 13, and the rotational power of the first flywheel 13 is not transmitted to the speed change device 16.

[0247] The first power transmission unit 11E can achieve the same operational effects as those of the first power transmission unit 11A described above.

[0248] The features of the first power transmission portion 11E of the fifth embodiment are as follows.

[0249] Since the first clutch 26 and the second clutch 27 of the first power transmission unit 11E of the fifth embodiment are composed of a multi-plate clutch, high power transmission performance can be obtained between the first friction plates 26A, 27A and the second friction plates 26B, 27B. That is, the clutch device 25 has excellent power transmission performance.

[0250] In addition, since the first clutch 26 and the second clutch 27 are arranged along the radial direction of the relay shaft 17, the length in the front-to-back direction can be shortened. As a result, the axial length (length in the front-to-back direction) of the first flywheel 13 can be extended. Therefore, the moment of inertia of the first flywheel 13 can be increased, and the rotational energy that can be accumulated in the first flywheel 13 can be increased. That is, the first flywheel 13 has excellent performance in accumulating rotational energy.

[0251] In addition, since the first clutch 26 and the second clutch 27 are arranged at positions facing the partition wall 9d of the flywheel housing 9, an oil passage for supplying working oil to the first clutch 26 and the second clutch 27 can be provided along the partition wall 9d. Therefore, it is easy to provide an oil passage for supplying working oil to the first clutch 26 and the second clutch 27. That is, the oil passage is excellent in establishment.

[0252] In addition, by providing a bearing on the first wall 9a of the flywheel housing 9, one end side of the relay shaft 17 is supported in a rotatable manner. And, by providing a bearing on the second wall 9b of the flywheel housing 9, the other end side of the relay shaft 17 or the input shaft 16a of the speed change device 16 connected to the other end side is supported in a rotatable manner. In addition, by providing a bearing on the partition wall 9d, the middle part of the relay shaft 17 is supported in a rotatable manner. Thus, the two end sides and the middle part of the relay shaft 17 can be reliably and easily supported in a rotatable manner. That is, the shaft support is excellent in establishment.

[0253] Furthermore, since the first clutch 26 and the second clutch 27 are arranged side by side in the radial direction of the relay shaft 17 near the partition wall 9d, the components for supporting the first clutch 26 and the second clutch 27 can be shared, and the number of components can be reduced.

[0254] As described above, the first power transmission unit 11E of the fifth embodiment is excellent in power transmission performance, rotational energy storage performance, oil path establishment, shaft support establishment, and reduction in the number of parts. Therefore, it is possible to achieve a good balance between performance-related features (power transmission performance, rotational energy storage performance) and structure-related features (oil path establishment, shaft support establishment, and reduction in the number of parts) at a high level.

[0255] <Sixth Embodiment>

[0256] Next, based on Figure 8 The specific structure of the first power transmission part 11 of the sixth embodiment will be described. Hereinafter, the first power transmission part 11 of the sixth embodiment will be referred to as a "first power transmission part 11F".

[0257] A partition wall 9d is provided inside the flywheel housing 9 that accommodates the first power transmission unit 11F of the sixth embodiment. The partition wall 9d is provided between the first wall 9a and the second wall 9b. One surface of the partition wall 9d faces the first wall 9a. The other surface of the partition wall 9d faces the second wall 9b.

[0258] The partition wall 9 d partitions the interior of the flywheel housing 9 into a first space 51 for accommodating the first flywheel 13 and a second space 52 for accommodating the first clutch 26 and the second clutch 27 .

[0259] The first space 51 is provided at the front part (the engine 4 side) of the flywheel housing 9. In the first space 51, the second flywheel 14 is accommodated in addition to the first flywheel 13. The second space 52 is provided at the rear part (the speed change device 16 side) of the flywheel housing 9. In the second space 52, in addition to the first clutch 26 and the second clutch 27, the speed increasing mechanism 20 is also accommodated.

[0260] In the first power transmission unit 11F, the first clutch 26 and the second clutch 27 are arranged in a radial direction (a direction away from the axis of the relay shaft 17) of the relay shaft 17. The first clutch 26 is arranged on the outer peripheral side (the side away from the relay shaft 17). The second clutch 27 is arranged on the inner peripheral side (the side close to the relay shaft 17). In other words, the second clutch 27 is arranged on the inner peripheral side of the first clutch 26. The first clutch 26 and the second clutch 27 are arranged near the partition wall 9d of the flywheel housing 9. Specifically, the first clutch 26 and the second clutch 27 are arranged at a position facing the partition wall 9d.

[0261] The first clutch 26 and the second clutch 27 are arranged between the first flywheel 13 and the speed change device 16 in the front-to-back direction. The first clutch 26 and the second clutch 27 are located at positions offset from the first flywheel 13 in the front-to-back direction. In other words, the first clutch 26 and the second clutch 27 do not overlap with the first flywheel 13 in the front-to-back direction. In addition, the first clutch 26 and the second clutch 27 are arranged between the first flywheel 13 and the speed increasing mechanism 20 in the front-to-back direction.

[0262] The first clutch 26 is a multi-plate clutch having a plurality of first friction plates 26A and a plurality of second friction plates 26B. The first friction plates 26A and the second friction plates 26B are arranged alternately in the front-rear direction. The first friction plates 26A and the second friction plates 26B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 26A and the second friction plates 26B.

[0263] The first friction plate 26A is mounted on the first flywheel 13 and is movable in the axial length direction of the relay shaft 17. The second friction plate 26B is mounted on the sun gear 21 of the speed increasing mechanism 20.

[0264] The second clutch 27 is also a multi-plate clutch, and has a plurality of first friction plates 27A and a plurality of second friction plates 27B. The first friction plates 27A and the second friction plates 27B are arranged alternately in the front-rear direction. The first friction plates 27A and the second friction plates 27B are formed in an annular shape. The relay shaft 17 passes through the center of the first friction plates 27A and the second friction plates 27B.

[0265] The first friction plate 27A is mounted on the first flywheel 13 and is movable along the axial length direction of the relay shaft 17. The second friction plate 27B is mounted on the planetary gear 22 of the speed increasing mechanism 20. The second friction plate 27B is connected to the planetary gear 22 of the speed increasing mechanism 20 via the connecting member 60 and the planetary carrier 24. The connecting member 60 connects the relay shaft 17 and the input shaft 16a of the speed changing device 16. The planetary carrier 24 supports the planetary gear 22. The second friction plate 27B is arranged on the outer peripheral side of the first friction plate 27A.

[0266] The first power transmission path 31 of the first power transmission unit 11F transmits the rotational power of the engine 4 to the second flywheel 14 , the relay shaft 17 , the connecting member 60 , the planetary carrier 24 , the planetary gear 22 , the sun gear 21 , the first clutch 26 in sequence, and then to the first flywheel 13 .

[0267] The second power transmission path 32 of the first power transmission unit 11F is a path for transmitting the rotational power of the first flywheel 13 to the second clutch 27 and the connector 60 in sequence, and then to the speed change device 16 .

[0268] The third power transmission path 33 of the first power transmission unit 11F transmits the rotational power of the engine 4 to the transmission 16 via the connector 60 and the relay shaft 17. The third power transmission path 33 transmits the rotational power of the engine 4 to the transmission 16 without passing through either the first clutch 26 or the second clutch 27.

[0269] Next, the operation of the first power transmission unit 11F will be described.

[0270] The rotational power output from the output shaft 4a of the engine 4 is transmitted to the second flywheel 14. As a result, the second flywheel 14 rotates, and the relay shaft 17 connected to the second flywheel 14 also rotates. At this time, the rotation speed of the engine 4, the rotation speed of the second flywheel 14, and the rotation speed of the relay shaft 17 are the same. The rotational power transmitted to the relay shaft 17 is transmitted to the input shaft 16a of the speed change device 16 via the connecting member 60.

[0271] Thus, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the transmission 16 via the third power transmission path 33. The rotational power is always transmitted via the third power transmission path 33 regardless of whether the first clutch 26 and the second clutch 27 are disconnected.

[0272] When the first clutch 26 is in the connected state and the second clutch 27 is in the disconnected state, the rotational power output from the output shaft 4a of the engine 4 is transmitted to the first flywheel 13 via the first power transmission path 31. Specifically, the rotational power of the engine 4 is transmitted from the second flywheel 14 to the planetary gear 22 via the relay shaft 17, the connecting member 60 and the planetary carrier 24. As a result, the planetary gear 22 rotates, and the sun gear 21 rotates with the rotation of the planetary gear 22. The sun gear 21 is connected to the second friction plate 26B of the first clutch 26. Therefore, the rotational power transmitted to the sun gear 21 is transmitted from the second friction plate 26B to the first friction plate 26A, and from the first friction plate 26A to the first flywheel 13.

[0273] Here, the rotational power of the engine 4 is accelerated when being transmitted from the planetary gear 22 to the sun gear 21. That is, the rotational power of the engine 4 is accelerated and transmitted to the first flywheel 13. Therefore, the first flywheel 13 rotates at a rotation speed greater than the rotation speed of the engine 4. Thus, high rotational energy can be accumulated in the first flywheel 13.

[0274] In addition, when the first clutch 26 is in the disconnected state and the second clutch 27 is in the connected state, the second power transmission path 32 is connected, so the rotational power of the first flywheel 13 is transmitted to the speed change device 16. Specifically, the rotational power of the first flywheel 13 is transmitted from the first friction plate 27A of the second clutch 27 to the second friction plate 27B. As a result, the rotational power of the first flywheel 13 is transmitted from the second friction plate 27B to the input shaft 16a of the speed change device 16 via the connector 60. At this time, the rotational power of the first flywheel 13 is transmitted to the input shaft 16a of the speed change device 16 without deceleration (not via a speed reduction mechanism). Therefore, the high rotational energy of the first flywheel 13 can be directly input to the speed change device 16.

[0275] When the first clutch 26 and the second clutch 27 are both in the disconnected state, since the first power transmission path 31 and the second power transmission path 32 are disconnected, the rotational power of the engine 4 is not transmitted to the first flywheel 13, and the rotational power of the first flywheel 13 is not transmitted to the speed change device 16.

[0276] The first power transmission unit 11F can achieve the same effects as those of the first power transmission unit 11A described above.

[0277] The features of the first power transmission unit 11F of the sixth embodiment are as follows.

[0278] Since the first clutch 26 and the second clutch 27 of the first power transmission unit 11F of the sixth embodiment are composed of multiple-plate clutches, high power transmission performance can be obtained between the first friction plates 26A and 27A and the second friction plates 27B. That is, the clutch device 25 has excellent power transmission performance.

[0279] In addition, since the first clutch 26 and the second clutch 27 are arranged along the radial direction of the relay shaft 17, the length in the front-to-back direction can be shortened. As a result, the axial length (length in the front-to-back direction) of the first flywheel 13 can be extended. Therefore, the moment of inertia of the first flywheel 13 can be increased, and the rotational energy that can be accumulated in the first flywheel 13 can be increased. That is, the first flywheel 13 has excellent performance in accumulating rotational energy.

[0280] In addition, since the first clutch 26 and the second clutch 27 are arranged at a position facing the partition wall 9d of the flywheel housing 9, an oil passage for supplying working oil to the first clutch 26 and the second clutch 27 can be provided along the partition wall 9d. Therefore, it is easy to provide an oil passage for supplying working oil to the first clutch 26 and the second clutch 27. That is, the oil passage is excellent in establishment.

[0281] In addition, by providing a bearing on the first wall 9a of the flywheel housing 9, one end side of the relay shaft 17 is supported in a rotatable manner. And, by providing a bearing on the second wall 9b of the flywheel housing 9, the other end side of the relay shaft 17 or the input shaft 16a of the speed change device 16 connected to the other end side is supported in a rotatable manner. In addition, by providing a bearing on the partition wall 9d, the middle part of the relay shaft 17 is supported in a rotatable manner. Thus, the two end sides and the middle part of the relay shaft 17 can be reliably and easily supported in a rotatable manner. That is, the shaft support is excellent in establishment.

[0282] Furthermore, since the first clutch 26 and the second clutch 27 are arranged side by side in the radial direction of the relay shaft 17 near the partition wall 9d, the components for supporting the first clutch 26 and the second clutch 27 can be shared, and the number of components can be reduced.

[0283] As described above, the first power transmission unit 11F of the sixth embodiment is excellent in power transmission performance, rotational energy storage performance, oil circuit establishment, shaft support establishment, and reduction in the number of components. Therefore, a good balance can be achieved between performance-related features (power transmission performance, rotational energy storage performance) and structure-related features (oil circuit establishment, shaft support establishment, and reduction in the number of components).

[0284] However, the fifth embodiment is superior in terms of oil passage establishment, shaft support establishment, and reduction in the number of parts. This is due to the difference in the specific structure of the clutch device 25 between the fifth embodiment and the sixth embodiment.

[0285] In the sixth embodiment (refer to Figure 8 ), from the outer peripheral side (the side away from the axis of the relay shaft 17) toward the inner peripheral side (the side close to the axis of the relay shaft 17), the portion supporting the first friction plate 26A, the portion supporting the second friction plate 26B, the portion supporting the second friction plate 27B, and the portion supporting the first friction plate 27A are arranged in order. Figure 7 ), a portion supporting the first friction plate 26A, a portion supporting the second friction plate 26B, a portion supporting the first friction plate 27A, and a portion supporting the second friction plate 27B are arranged in sequence from the outer peripheral side to the inner peripheral side.

[0286] Due to this structural difference, the fifth embodiment can simplify the support structure of the clutch device 25 and reduce the number of components compared to the sixth embodiment. In addition, the fifth embodiment can easily form an oil path for supplying working oil to the first clutch 26 and the second clutch 27 compared to the sixth embodiment.

[0287] In the fifth embodiment, a portion 80 extending rearward from the inner cylinder portion 13b of the first flywheel 13 along the relay shaft 17 may be provided on the inner circumferential side of the portion supporting the second friction plate 26B (see Figure 7 ), a bearing (a fifth bearing 66 described later (see Fig.11 )). Thus, the relay shaft 17 can be supported rotatably and easily. The portion 80 corresponds to the support member 65 described later (see Fig.11 ) at the rear.

[0288] <Detailed Structure of Fifth Embodiment>

[0289] Next, based on Fig.10 , Fig.11A detailed structural description will be given of a first power transmission portion 11E of a fifth embodiment, which is a particularly preferred embodiment among the first power transmission portions 11 of the first to sixth embodiments described above.

[0290] Fig.10 It is a cross-sectional view showing a power transmission mechanism 6 including a first power transmission portion 11E according to the fifth embodiment and a part of a transmission case 5 accommodating the power transmission mechanism 6 . Fig.11 It is magnified Fig.10 Part of the diagram.

[0291] like Fig.10 As shown, the transmission case 5 has a front portion 5A, a middle portion 5B and a rear portion 5C. The front portion 5A is located at the front of the transmission case 5. The middle portion 5B is connected to the rear of the front portion 5A. The rear portion 5C is connected to the rear of the middle portion 5B.

[0292] A front wheel drive shaft 63 for transmitting rotational power to the front wheels 3F is disposed at the lower portion of the transmission case 5 and passes through the transmission case 5. The front wheel drive shaft 63 passes through the front section 5A, the middle section 5B, and the rear section 5C and extends in the front-rear direction.

[0293] The front portion 5A, the middle portion 5B, and the front portion of the rear portion 5C constitute the flywheel housing 9. The rear portion of the rear portion 5C constitutes the front portion of the transmission 10. The rear portion 5C has a structure that combines the rear portion of the flywheel housing 9 and the front portion of the transmission 10.

[0294] The front portion 5A includes a first cylindrical portion 91 and a first wall 9a. The first cylindrical portion 91 covers the periphery of the second flywheel 14. The first wall 9a is the first wall 9a of the flywheel housing 9 and is disposed in front of the second flywheel 14.

[0295] The middle portion 5B has a second cylindrical portion 92 and an intermediate wall 95. The second cylindrical portion 92 is connected to the rear portion of the first cylindrical portion 91 of the front portion 5A. Specifically, the second cylindrical portion 92 is connected to the rear portion of the first cylindrical portion 91 by a bolt B1. The second cylindrical portion 92 covers the periphery of the first flywheel 13 and the periphery of the front portion of the clutch device 25 (the first clutch 26 and the second clutch 27). The intermediate wall 95 is provided between the first flywheel 13 and the second flywheel 14. The intermediate wall 95 divides the first space 51 into a space in which the first flywheel 13 is arranged and a space in which the second flywheel 14 is arranged.

[0296] The rear portion 5C has a third tubular portion 93, a second wall 9b, and a fourth tubular portion 94. The third tubular portion 93 is connected to the rear portion of the second tubular portion 92 of the middle portion 5B. Specifically, the third tubular portion 93 is connected to the rear portion of the second tubular portion 92 by a bolt B2. The third tubular portion 93 covers the periphery of the speed increasing mechanism 20. The second wall 9b is the second wall 9b of the flywheel housing 9, and is disposed at the rear of the speed increasing mechanism 20.

[0297] The first tubular portion 91, the second tubular portion 92, and the third tubular portion 93 constitute a peripheral wall 9c of the flywheel housing 9. The interior of the flywheel housing 9 is partitioned into a first space 51 and a second space 52 by a partition wall 9d.

[0298] like Fig.10 As shown, the partition wall 9d is fixed to the intermediate wall 95. Specifically, the intermediate wall 95 is inserted into the mounting hole 9e (see Fig.12 ) is fixed relative to the partition wall 9d.

[0299] In addition, if Fig.11 As shown, a first bearing 61 and a second bearing 62 are mounted on the intermediate wall 95. The first bearing 61 rotatably supports the front portion of the relay shaft 17. The second bearing 62 rotatably supports the front portion of the first flywheel 13.

[0300] like Fig.11 , Fig.12 As shown, the first flywheel 13 has an outer cylinder portion 13a, an inner cylinder portion 13b and a connecting portion 13c. The length of the connecting portion 13c in the front-to-back direction is smaller than the length of the outer cylinder portion 13a and the inner cylinder portion 13b in the front-to-back direction. That is, the thickness of the connecting portion 13c is smaller than the thickness of the outer cylinder portion 13a and the inner cylinder portion 13b.

[0301] The first flywheel 13 has a first recess 13e and a second recess 13f. The first recess 13e is recessed in front of the connecting portion 13c and between the outer tube portion 13a and the inner tube portion 13b. The second recess 13f is recessed in the rear of the connecting portion 13c and between the outer tube portion 13a and the inner tube portion 13b.

[0302] The second bearing 62 is disposed in the first recessed portion 13e. The third bearing 64 is disposed in the second recessed portion 13f. The first flywheel 13 is rotatably supported by the second bearing 62 and the third bearing 64.

[0303] like Fig.11 As shown in FIG. 1 , a support 65 is disposed on the outer peripheral side of the relay shaft 17. The support 65 supports the first flywheel 13 so as to be rotatable relative to the relay shaft 17. Fig.11 , Fig.12As shown, the support member 65 has a first portion 65a, a second portion 65b, a third portion 65c, a fourth portion 65d, a fifth portion 65e, and a sixth portion 65f.

[0304] The first portion 65a is cylindrical, and the relay shaft 17 passes through it. The rear portion of the first portion 65a is supported by the fifth bearing 66 installed on the outer peripheral surface of the relay shaft 17. Thus, the support member 65 can rotate relative to the relay shaft 17. The middle portion of the first portion 65a in the front-to-back direction is supported by the sixth bearing 67 installed on the inner peripheral surface of the partition wall 9d. Thus, the support member 65 can rotate relative to the partition wall 9d. The first flywheel 13 is installed at the front portion of the first portion 65a. The first flywheel 13 and the front portion of the support member 65 are splined together. Therefore, the first flywheel 13 can rotate relative to the relay shaft 17 and the partition wall 9d as a whole with the support member 65.

[0305] The second portion 65b extends outward (in a direction away from the relay shaft 17) from the rear of the first portion 65a. The second portion 65b is formed in a disc shape. The third portion 65c extends rearward from the outer peripheral end of the second portion 65b. The third portion 65c is formed in a cylindrical shape. The fourth portion 65d extends rearward from between the outer peripheral end and the inner peripheral end of the second portion 65b. The fourth portion 65d is formed in a cylindrical shape with a smaller diameter than the third portion 65c. The fourth portion 65d is arranged on the inner peripheral side of the third portion 65c.

[0306] The fifth portion 65e extends forward from the outer peripheral end of the second portion 65b. The fifth portion 65e is formed into a cylindrical shape. The diameter of the fifth portion 65e is substantially equal to the diameter of the third portion 65c. The sixth portion 65f extends forward from between the outer peripheral end and the inner peripheral end of the second portion 65b. The sixth portion 65f is formed into a cylindrical shape having a smaller diameter than the fifth portion 65e. The diameter of the sixth portion 65f is substantially equal to the diameter of the fourth portion 65d.

[0307] like Fig.11 , Fig.12 As shown in FIG. 1 , the partition wall 9d includes a wall portion 96, a cylinder portion 97, a first protrusion 98, and a second protrusion 99. The wall portion 96 is formed in a disk shape and partitions the first flywheel 13 and the clutch device 25. Fig.11 As shown, an oil passage 70 for supplying hydraulic oil to the clutch device 25 is formed in the wall portion 96. A supply pipe 71 is connected to the oil passage 70. The hydraulic oil can be supplied to the oil passage 70 through the supply pipe 71 from the outside of the flywheel housing 9.

[0308] The oil passage 70 is composed of a main oil passage 70a, a first branch oil passage 70b, and a second branch oil passage 70c. The main oil passage 70a extends from the outer peripheral side to the inner peripheral side of the partition wall 9d. A supply pipe 71 is connected to the end of the outer peripheral side of the main oil passage 70a. The first branch oil passage 70b and the second branch oil passage 70c branch from the main oil passage 70a and extend rearward.

[0309] The main oil passage 70a is a passage for receiving hydraulic oil from the outside of the flywheel housing 9 through the supply pipe 71. The first branch oil passage 70b is an oil passage for supplying the hydraulic oil supplied to the main oil passage 70a to the first clutch 26. The second branch oil passage 70c is an oil passage for supplying the hydraulic oil supplied to the main oil passage 70a to the second clutch 27.

[0310] The cylinder 97 is formed in a cylindrical shape. The sixth bearing 67 is interposed between the inner peripheral surface of the cylinder 97 and the outer peripheral surface of the first portion 65a of the support member 65. The cylinder 97 includes a front cylinder 97a extending forward from the inner peripheral end of the wall 96 and a rear cylinder 97b extending rearward from the inner peripheral end of the wall 96. The third bearing 64 is interposed between the outer peripheral surface of the front cylinder 97a and the first flywheel 13.

[0311] The first protrusion 98 extends rearward from the wall portion 96. The first protrusion 98 is formed in a cylindrical shape. The second protrusion 99 extends rearward from between the outer peripheral end and the inner peripheral end of the wall portion 96. The second protrusion 99 is formed in a cylindrical shape with a smaller diameter than the first protrusion 98. The second protrusion 99 is arranged on the inner peripheral side of the first protrusion 98.

[0312] like Fig.11 As shown, the relay shaft 17 and the input shaft 16a of the speed change device 16 are connected by a connector 60. External splines are formed on the outer peripheral surface of the rear portion of the relay shaft 17 and the outer peripheral surface of the front portion of the input shaft 16a. Internal splines are formed on the inner peripheral surface of the connector 60. The relay shaft 17 and the input shaft 16a are connected via the connector 60 by meshing the external splines with the internal splines. As a result, the connector 60, the relay shaft 17, and the input shaft 16a rotate integrally.

[0313] The connector 60 is arranged at the rear of the support member 65. The connector 60 has a cylindrical connector 60a and an extension portion 60b extending from the front of the connector 60a to the outside (in the direction away from the relay shaft 17) and then extending to the front. The inner spline mentioned above is formed on the inner circumferential surface of the connector 60a. The outer end of the extension portion 60b is formed into a cylindrical shape with a larger diameter than the connector 60a. The outer circumferential surface of the extension portion 60b is opposite to the inner circumferential surface of the fourth portion 65d.

[0314] The sun gear 21 of the speed increasing mechanism 20 is supported on the outer peripheral surface of the connecting portion 60a via the seventh bearing 68. Thus, the sun gear 21 can rotate relative to the connecting member 60. A mounting component 69 is fixed to the sun gear 21. The mounting component 69 has a fixed portion 69a fixed to the sun gear 21 and a front extension portion 69b extending forward from the fixed portion 69a. The fixed portion 69a is formed in a disc shape. The front extension portion 69b is formed in a cylindrical shape.

[0315] The planetary gears 22 of the speed increasing mechanism 20 are supported by the planetary carrier 24. An internal spline is formed on the inner circumference of the planetary carrier 24. The internal spline of the planetary carrier 24 meshes with the external spline formed on the outer circumference of the connecting portion 60a. Thus, the planetary carrier 24 can rotate together with the connecting member 60 and the relay shaft 17.

[0316] The ring gear 23 of the speed increasing mechanism 20 is mounted on the annular support member 72. The annular support member 72 is fixed to the middle portion 5B of the flywheel housing 9. Specifically, the annular support member 72 is fixed to the middle portion 5B by bolts B4. Thus, the ring gear 23 is fixed to the flywheel housing 9 in a non-rotatable manner.

[0317] The first friction plates 26A and the second friction plates 26B of the first clutch 26 are arranged behind the second portion 65b of the support 65. The first friction plates 26A and the second friction plates 26B are arranged between the third portion 65c of the support 65 and the front extension 69b of the mounting member 69.

[0318] The first friction plate 26A of the first clutch 26 is annular, and its outer peripheral portion is supported by the third portion 65c of the support member 65. Specifically, a plurality of protrusions 26A1 (see Fig.12 ) is embedded in the plurality of cutouts 65g formed in the third portion 65c (refer to Fig.12 ). Thus, the first friction plate 26A cannot rotate relative to the support member 65, but can move in the front-rear direction along the notch 65g.

[0319] The second friction plate 26B of the first clutch 26 is annular, and the inner peripheral portion is supported by the front extension portion 69b of the mounting member 69. The second friction plate 26B is fixed to the front extension portion 69b so as to be immovable.

[0320] The hydraulic piston 73 of the first clutch 26 (hereinafter referred to as the "first hydraulic piston 73") is arranged between the partition wall 9d and the second portion 65b of the support member 65. Specifically, the first hydraulic piston 73 is arranged in a space surrounded by the wall portion 96 of the partition wall 9d, the first protrusion 98, the second protrusion 99, the second portion 65b of the support member 65, the fifth portion 65e, and the sixth portion 65f. An opening 65h is formed in the second portion 65b of the support member 65 (see Fig.11 , Fig.12 ), the top end of the first hydraulic piston 73 protrudes from the opening 65h. The top end of the first hydraulic piston 73 is close to the first friction plate 26A located at the front.

[0321] The hydraulic oil is supplied from the first branch oil passage 70b to the base end side of the first hydraulic piston 73. When the hydraulic oil is supplied from the first branch oil passage 70b, the first hydraulic piston 73 moves rearward to press the first friction plate 26A, and the first friction plate 26A is pressed against the second friction plate 26B.

[0322] The first hydraulic piston 73 is urged forward by the first spring 74. Therefore, when hydraulic oil is not supplied from the first branch oil passage 70b, the first hydraulic piston 73 moves forward by the urging force of the first spring 74. When the first hydraulic piston 73 moves forward, the first friction plate 26A separates from the second friction plate 26B.

[0323] The first friction plates 27A and the second friction plates 27B of the second clutch 27 are arranged behind the second portion 65b of the support 65. The first friction plates 27A and the second friction plates 27B are arranged between the fourth portion 65d of the support 65 and the outer peripheral surface of the extended portion 60b of the connector 60.

[0324] The first friction plate 27A of the second clutch 27 is annular, and its outer peripheral portion is supported by the fourth portion 65d of the support member 65. Specifically, a plurality of protrusions 27A1 (see Fig.12 ) is embedded in the plurality of cutouts 65i formed in the fourth portion 65d (see Fig.12 ). Thus, the first friction plate 27A cannot rotate relative to the support member 65, but can move in the front-rear direction along the notch 65i.

[0325] The second friction plate 27B of the second clutch 27 is annular, and the inner peripheral portion is supported by the extended portion 60b of the connecting member 60. The second friction plate 27B is fixed to the extended portion 60b so as to be immovable.

[0326] The hydraulic piston 75 of the second clutch 27 (hereinafter referred to as the "second hydraulic piston 75") is arranged between the partition wall 9d and the second portion 65b of the support member 65. Specifically, the second hydraulic piston 75 is arranged in a space surrounded by the wall portion 96 of the partition wall 9d, the cylinder portion 97, the second protrusion 99, the first portion 65a of the support member 65, the second portion 65b, and the sixth portion 65f. An opening 65j is formed in the second portion 65b of the support member 65 (see Fig.11 , Fig.12 ), the top end of the second hydraulic piston 75 protrudes from the opening 65j. The top end of the second hydraulic piston 75 is close to the first friction plate 27A located at the front.

[0327] The hydraulic oil is supplied from the second branch oil passage 70c to the base end side of the second hydraulic piston 75. When the hydraulic oil is supplied from the second branch oil passage 70c, the second hydraulic piston 75 moves rearward to press the first friction plate 27A, and the first friction plate 27A is pressed against the second friction plate 27B.

[0328] The second hydraulic piston 75 is urged forward by the second spring 76. Therefore, when hydraulic oil is not supplied from the second branch oil passage 70c, the second hydraulic piston 75 moves forward by the urging force of the second spring 76. When the second hydraulic piston 75 moves forward, the first friction plate 27A separates from the second friction plate 27B.

[0329] <Control system>

[0330] Fig.13 1 is a block diagram showing a schematic configuration of a control system 100 provided in the work vehicle 1 of the present invention. The control system 100 is a control system that can be provided in the above-mentioned work vehicle 1. That is, the control system 100 can be applied to the work vehicle 1 provided with the first power transmission unit 11 of all the above-mentioned embodiments (first to sixth embodiments).

[0331] The control system 100 includes a control device 110 , an information acquisition unit 120 , a display input device 130 , and an operation unit 140 .

[0332] The controller 110 includes an ECU (Electronic Control Unit). The controller 110 receives various information and signals sent (input) from the information acquisition unit 120 to perform calculations, and sends a control signal for controlling the operation of the operation unit 140 to the operation unit 140 based on the calculation results.

[0333] The control device 110 has a calculation unit 111, a storage unit 112, and a communication unit 113. The calculation unit 111 is composed of a CPU, etc., and reads out various programs stored in the storage unit 112 to perform various calculations and processes. The storage unit 112 stores programs executed by the calculation unit 111 and various data. The storage unit 112 is composed of a ROM (read-only memory), a RAM (random access memory), etc. In addition, the storage unit 112 can also be an external storage device connected to the control device 110. The communication unit 113 communicates between the control device 110 and the information acquisition unit 120, the display input device 130, and the action unit 140 through telecommunication lines or wirelessly, and transmits and receives various information or various signals.

[0334] The information acquisition unit 120 acquires information related to the operation of the work vehicle 1 and transmits it to the control device 110. The information acquisition unit 120 includes a first pressure sensor 28, a second pressure sensor 29, a first rotation speed sensor 18, a second rotation speed sensor 15, and an accelerator opening sensor 19.

[0335] As described above, the first pressure sensor 28 detects the pressure of the working oil in the oil circuit for supplying working oil to the hydraulic piston of the first clutch 26 (the working pressure of the oil circuit piston). The second pressure sensor 29 detects the pressure of the working oil in the oil circuit for supplying working oil to the hydraulic piston of the second clutch 27 (the working pressure of the oil circuit piston).

[0336] The first rotation speed sensor 18 measures the rotation speed of the first flywheel 13. The second rotation speed sensor 15 calculates the rotation speed (actual rotation speed) of the engine 4 by measuring the rotation speed of the second flywheel 14. The accelerator opening sensor 19 detects the indicated injection amount (indicative value of the injection amount of the fuel injection valve (injector)) according to the amount of depression of the accelerator pedal.

[0337] In addition, although Fig.13 Although not shown in the figure, the information acquisition unit 120 may also include the first torque sensor 35, the second torque sensor 36, and the third rotation speed sensor 37 mentioned above.

[0338] The display input device 130 is configured to display various information and accept human operation. The display input device 130 is, for example, a touch panel display device. The display input device 130 is, for example, arranged near the driver's seat of the work vehicle 1 .

[0339] The calculation unit 111 includes a load factor calculation unit 111 a , a torque factor calculation unit 111 b , a drop rate calculation unit 111 c , and an operation mode determination unit 111 d .

[0340] The load factor calculation unit 111a calculates the load factor (hereinafter sometimes referred to as "load factor") of the engine 4. Specifically, the load factor calculation unit 111a calculates the load factor based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount corresponding to the boost pressure stored in the storage unit 112. Specifically, the load factor calculation unit 111a calculates the load factor using the calculation formula "indicated injection amount / limited injection amount corresponding to the boost pressure×100".

[0341] The "boost pressure" is the pressure of the compressed air forcibly fed into the engine 4 by the supercharger. The "limited injection amount" is a value determined so that the amount of fuel injected by the fuel injection valve (injector) cannot exceed this value. The "limited injection amount corresponding to the boost pressure" is a limited injection amount determined corresponding to the boost pressure. The limited injection amount is set to increase in accordance with an increase in the boost pressure. The "limited injection amount corresponding to the boost pressure" is stored in the storage unit 112.

[0342] The torque rate calculation unit 111b calculates the torque rate (hereinafter sometimes referred to as "torque rate") of the engine 4. Specifically, the torque rate calculation unit 111b calculates the torque rate based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount of the full load curve stored in the storage unit 112. Specifically, the load rate calculation unit 111a calculates the torque rate using the calculation formula of "indicated injection amount / limited injection amount of the full load curve×100".

[0343] The “limited injection amount of the full load curve” is a limited injection amount determined according to the full load curve (the full load curve with the engine speed on the horizontal axis and the fuel injection amount on the vertical axis) of the engine 4 . The “limited injection amount of the full load curve” is stored in the storage unit 112 .

[0344] The descent rate calculation unit 111c calculates the descent rate of the engine 4 (hereinafter sometimes referred to as the "descent rate"). Specifically, the descent rate calculation unit 111c calculates the descent rate based on the actual speed of the engine 4 detected by the second speed sensor 15 (hereinafter sometimes referred to as the "actual speed") and the target speed of the engine 4 stored in the storage unit 112 (hereinafter sometimes referred to as the "target speed"). Specifically, the descent rate calculation unit 111c calculates the descent rate using the calculation formula "actual speed / target speed×100". In addition, the target speed of the engine 4 refers to the speed of the engine 4 predetermined in accordance with the throttle opening, etc.

[0345] The action mode determination unit 111d determines an action mode (described later) of the control system 100 based on the information (detection value, etc.) obtained by the information acquisition unit 120, the values ​​calculated by the load factor calculation unit 111a, the torque rate calculation unit 111b, and the reduction rate calculation unit 111c, etc. The controller 110 sends a control signal to the action unit 140 based on the action mode determined by the action mode determination unit 111d.

[0346] The operation unit 140 operates according to a control signal sent from the control device 110. The operation unit 140 includes a first clutch 26 and a second clutch 27.

[0347] The first clutch 26 is operated based on the first control signal sent from the control device 110. The first control signal is a control signal for driving the hydraulic piston (first hydraulic piston 73) of the first clutch 26, and includes an indicated pressure of the working oil for driving the hydraulic piston of the first clutch 26 (hereinafter referred to as "first indicated pressure"). The working pressure of the hydraulic piston of the first clutch 26 is determined by the first indicated pressure included in the control signal sent from the control device 110. The first clutch 26 is connected or disconnected by driving the hydraulic piston based on the first indicated pressure.

[0348] The second clutch 27 is operated based on the second control signal sent from the control device 110. The second control signal is a control signal for driving the hydraulic piston (second hydraulic piston 75) of the second clutch 27, and includes an indicated pressure of the working oil for driving the hydraulic piston of the second clutch 27 (hereinafter referred to as "second indicated pressure"). The working pressure of the hydraulic piston of the second clutch 27 is determined by the second indicated pressure included in the control signal sent from the control device 110. The second clutch 27 is connected or disconnected by driving the hydraulic piston based on the second indicated pressure.

[0349] The control device 110 controls the intermittent operation of the first clutch 26 and the second clutch 27 to switch between the plurality of operation modes. Specifically, the control device 110 switches the operation mode by controlling the intermittent operation of the first clutch 26 and the second clutch 27, or notifies the operator of the work vehicle 1 that the operation mode can be switched.

[0350] like Fig.14 As shown, the plurality of operation modes include free mode, charging preparation mode, charging mode, boost preparation mode, boost mode, stick preparation mode, stick mode, and engine off mode. Each operation mode will be described below.

[0351] <Free Mode>

[0352] The free mode is a mode of the operating state immediately after the engine 4 is started. In the free mode, the engine 4 is started but has not reached the idle speed. The first clutch 26 and the second clutch 27 are disconnected. Since the first clutch 26 and the second clutch 27 are disconnected, the first flywheel 13 stops. However, when the free mode is switched from other operating modes, the first flywheel 13 may rotate due to inertia.

[0353] <Charge Mode>

[0354] The charge mode is a mode in which rotational energy is accumulated in the first flywheel 13 .

[0355] In the charging mode, the engine 4 rotates at a target speed that exceeds the idle speed. However, when the load of the engine 4 increases due to the work load, etc., it may sometimes be less than the target speed. In the charging mode, the speed of the first flywheel 13 is greater than the speed (actual speed) of the engine 4, but less than the target speed of the first flywheel 13. The target speed of the first flywheel 13 is a speed greater than the speed of the engine 4. Specifically, the target speed of the first flywheel 13 is the speed obtained by multiplying the actual speed of the engine 4 by the speed increase ratio of the speed increase mechanism 20. For example, when the speed increase ratio of the speed increase mechanism 20 is 3, it becomes "target speed of the first flywheel 13 = actual speed of the engine 4 × 3". In the following description, in order to distinguish the target speed of the first flywheel 13 from the target speed of the engine 4, it is sometimes referred to as the "first target speed".

[0356] In the charging mode, the first clutch 26 is connected and the second clutch 27 is disconnected. By connecting the first clutch 26, the first flywheel 13 and the engine 4 are connected via the first path provided with the speed increasing mechanism 20.

[0357] The first path is a path (power transmission path) that connects the engine 4 and the first flywheel 13, and is provided with the speed increasing mechanism 20 and the first clutch 26. Figure 2 In the illustrated embodiment (first embodiment of the first power transmission unit 11 ), the first path is a path from the output shaft 4 a of the engine 4 to the first flywheel 13 via the second flywheel 14 , the relay shaft 17 , the first clutch 26 , and the speed increasing mechanism 20 .

[0358] When the first flywheel 13 and the engine 4 are connected via a first path provided with a speed increasing mechanism 20, the rotational power of the engine 4 is accelerated by the speed increasing mechanism 20 and transmitted to the first flywheel 13. Thus, the rotational speed of the first flywheel 13 is greater than the rotational speed of the engine 4, and the rotational power of the engine 4 can be effectively accumulated in the first flywheel 13.

[0359] <Charge Ready Mode>

[0360] The charging preparation mode is a mode in the preparation stage before transitioning to the charging mode. The charging preparation mode is a mode to be switched before transitioning to the charging mode.

[0361] In the charging preparation mode, the engine 4 rotates at a target speed. However, when the load of the engine 4 increases due to the operating load, etc., it is sometimes less than the target speed. In the charging preparation mode, the rotation speed of the first flywheel 13 is less than the target speed (first target speed) of the first flywheel 13. The rotation speed of the first flywheel 13 is greater than the rotation speed (actual speed) of the engine 4 or is the same as the rotation speed (actual speed) of the engine 4. In the charging preparation mode, the first clutch 26 is in a midway state of switching from a disconnected state to a connected state, and the second clutch 27 is disconnected. When the first clutch 26 switches from a disconnected state to a connected state, it is transferred to the charging mode.

[0362] The intermediate state of the first clutch 26 switching from the disconnected state to the connected state refers to a state in which the first friction plate 26A of the first clutch 26 is pushed by the hydraulic piston (first hydraulic piston 73) and approaches the second friction plate 26B, but is not in a state capable of transmitting power. In other words, a single trigger is implemented to prepare the first clutch 26 for connection. Hereinafter, this state is referred to as the "ineffective stroke elimination" state of the first clutch 26. In addition, in Fig.14 In the process, the status is marked as "invalid trip eliminated".

[0363] <Boost mode>

[0364] The supercharging mode is a mode in which the rotational power of the engine 4 is assisted by the rotational power of the first flywheel 13 when the rotational speed of the first flywheel 13 is greater than the rotational speed (actual rotational speed) of the engine 4 .

[0365] In the boost mode, the engine 4 rotates at a target speed. However, when the load on the engine 4 increases due to the work load, etc., it may sometimes be less than the target speed. In the boost mode, the rotation speed of the first flywheel 13 is greater than the rotation speed (actual speed) of the engine 4. This is because, in the charging mode executed before the transition to the boost mode, the rotation speed of the first flywheel 13 is greater than the rotation speed (actual speed) of the engine 4. In addition, because in the boost mode, the work load, etc. imposes a load on the engine 4, the actual speed of the engine 4 is reduced. The work load occurs, for example, when the working device is connected to the PTO shaft 8 of the working vehicle 1 and power is transmitted from the PTO shaft 8 to the working device to drive the working device.

[0366] In the supercharging mode, the first clutch 26 is disconnected and the second clutch 27 is connected. The second clutch 27 is switched from the half clutch state to the connected state in the supercharging mode. By connecting the second clutch 27, the first flywheel 13 and the engine 4 are connected via the second path.

[0367] The second path is a path (power transmission path) that connects the engine 4 and the first flywheel 13, in which the speed increasing mechanism 20 is not provided but the second clutch 27 is provided. Figure 2 In the illustrated embodiment (first embodiment of the first power transmission unit 11 ), the second path is a path from the output shaft 4 a of the engine 4 to the first flywheel 13 via the second flywheel 14 , the relay shaft 17 , and the second clutch 27 .

[0368] When the first flywheel 13 and the engine 4 are connected via the second path, since the rotation speed of the first flywheel 13 is greater than the rotation speed of the engine 4, the rotation power of the first flywheel 13 can be used to assist the rotation power of the engine 4. That is, the supercharging mode is an operation mode in which the rotation power of the first flywheel 13 is used to assist the rotation power of the engine 4 when the rotation speed of the first flywheel 13 is greater than the rotation speed (actual rotation speed) of the engine 4.

[0369] <Boost preparation mode>

[0370] The supercharging preparation mode is a mode in the preparation stage before shifting to the supercharging mode. The supercharging preparation mode is a mode that is switched before shifting to the supercharging mode. The supercharging preparation mode is a mode that is shifted when the load of the engine 4 increases due to an increase in the operating load, etc. By shifting to the supercharging preparation mode, the rotational energy accumulated in the first flywheel 13 in the charging mode is transferred to the supercharging mode for assisting the engine 4.

[0371] In the supercharging preparation mode, the engine 4 rotates at the target speed. However, when the load of the engine 4 increases due to the operating load, etc., it may sometimes be less than the target speed. In the supercharging preparation mode, the speed of the first flywheel 13 is the first target speed and is greater than the speed (actual speed) of the engine 4. In addition, the first clutch 26 is connected and the second clutch 27 is in a midway state from the disconnected state to the connected state (a state in which the invalid stroke is eliminated). When the second clutch 27 is switched to the connected state, it is transferred to the supercharging mode.

[0372] The midway state of the second clutch 27 switching from the disconnected state to the connected state refers to a state in which the first friction plate 27A of the second clutch 27 is pushed by the hydraulic piston (the second hydraulic piston 75) and approaches the second friction plate 27B, but is not in a state capable of transmitting power. In other words, it is a state in which a single trigger is implemented to prepare the second clutch 27 for connection. Hereinafter, this state is referred to as the "ineffective stroke elimination" state of the second clutch 27. In addition, in Fig.14 In the process, the status is marked as "invalid trip eliminated".

[0373] <Sticky Mode>

[0374] The stick mode is a mode in which, when the rotation speed of the first flywheel 13 is equal to or lower than the rotation speed (actual rotation speed) of the engine 4 , the inertial force of the first flywheel 13 is used to prevent the rotation speed of the engine 4 from dropping suddenly.

[0375] In the viscous mode, the engine 4 rotates at a target speed. However, when the load of the engine 4 increases due to the operating load, etc., it may be less than the target speed. In the viscous mode, the rotation speed of the first flywheel 13 is less than the rotation speed (actual speed) of the engine 4. Specifically, when the boost mode is transferred to the viscous mode, the rotation speed of the first flywheel 13 during the viscous mode transfer is the same as the rotation speed (actual speed) of the engine 4. When the viscous mode is transferred from other operation modes, the rotation speed of the first flywheel 13 during the viscous mode transfer is less than the rotation speed (actual speed) of the engine 4.

[0376] In the viscous mode, the first clutch 26 is disconnected and the second clutch 27 is connected. The second clutch 27 is changed from the half-clutch state to the connected state in the viscous mode. By connecting the second clutch 27, the first flywheel 13 and the engine 4 are connected via the second path.

[0377] When the first flywheel 13 and the engine 4 are connected via the second path, the first flywheel 13 and the engine 4 are driven to rotate. Therefore, when a high load is applied to the engine 4, the inertia force of the first flywheel 13 can prevent the rotation speed of the engine 4 from dropping sharply.

[0378] Since the rotation speed of the first flywheel 13 is lower than the rotation speed of the engine 4, in the stick mode, the rotation power of the first flywheel 13 cannot be used to assist the rotation power of the engine 4, but the rotation speed of the engine 4 can be prevented from dropping sharply. Therefore, in the case where the first flywheel 13 does not have enough rotation energy to assist the rotation power of the engine 4, in the stick mode, the rotation power can be used to prevent the rotation speed of the engine 4 from dropping sharply (making the engine 4 sticky).

[0379] <Sticky Ready Mode>

[0380] The sticky preparation mode is a mode in the preparation stage before transitioning to the sticky mode. The sticky preparation mode is a mode to be switched before transitioning to the sticky mode.

[0381] In the viscous preparation mode, the engine 4 rotates at the target speed. However, when the load of the engine 4 increases due to the work load, etc., it may be lower than the target speed. In the viscous preparation mode, the speed of the first flywheel 13 is lower than the speed (actual speed) of the engine 4. In addition, the first clutch 26 is disconnected and the second clutch 27 is in the middle of switching from the disconnected state to the connected state (the state in which the invalid stroke is eliminated). When the second clutch 27 is switched to the connected state, the mode is transferred to the viscous mode.

[0382] <Engine off mode>

[0383] The engine off mode is a mode in which the engine 4 is in an off state (a state in which the spark plug is not ignited), but the first flywheel 13 is rotating while reducing speed.

[0384] In the engine off mode, the spark plug of the engine 4 is in an unfired state, but the engine 4 rotates by inertia while decelerating. In addition, the first flywheel 13 also rotates by inertia while decelerating.

[0385] In the engine off mode, the first clutch 26 and the second clutch 27 are connected. Therefore, the first flywheel 13 is connected to the engine 4 via the first clutch 26 and the second clutch 27. Since the first flywheel 13 has a large inertia force, it will continue to rotate for a while even if the engine 4 is in the off state, but by connecting to the engine 4 via the first clutch 26 and the second clutch 27, the rotation is braked, so the rotation can be stopped in advance.

[0386] However, in the engine off mode, when the rotation speed of the first flywheel 13 is sufficiently low (for example, when the engine 4 is stopped immediately after starting), both or either of the first clutch 26 and the second clutch 27 may not be connected. This is because, when the rotation speed of the first flywheel 13 is sufficiently low, the first flywheel 13 will stop in a short time even if the rotation is not braked. The case where the rotation speed of the first flywheel 13 is sufficiently low is, for example, the case where the rotation speed of the first flywheel 13 is less than the idle speed of the engine 4.

[0387] <About the transition (switching) of the operation mode>

[0388] Next, the transition of the operation mode will be described.

[0389] Fig.15 It is a state transition diagram about action mode.

[0390] Free mode can be transferred from all other action modes except Boost Ready mode. Charge mode can be transferred from Charge Ready mode. Charge Ready mode can be transferred from Viscous mode. Viscous mode can be transferred from Viscous Ready mode and Boost mode. Viscous Ready mode can be transferred from Free mode. Boost mode can be transferred from Boost Ready mode. Boost Ready mode can be transferred from Charge mode. Engine Off mode can be transferred from all action modes.

[0391] The following describes the conditions for transition of the operation mode.

[0392] Fig.16 The conditions (threshold values) for transitioning the operation mode are shown. Figures 17 to 23This is a flowchart showing an example of the flow (steps) of transition of the operation mode.

[0393] <Transition from free mode to sticky preparation mode>

[0394] based on Fig.17 The transition from the free mode to the sticky preparation mode is described.

[0395] First, the transition to the free mode is automatically performed by starting the engine 4, or when a predetermined condition (described later) is satisfied in another operation mode (see Figure 18 to Figure 21 , Fig.23 ) performs a transition to the free mode. The transition from other action modes to the free mode will be described later.

[0396] In the free mode, the engine 4 is started, and the first clutch 26 and the second clutch 27 are in the disconnected state. Since the first clutch 26 and the second clutch 27 are in the disconnected state, the rotational power of the engine 4 is not transmitted to the first flywheel 13, and the first flywheel 13 stops. However, as described above, when the free mode is shifted from other operation modes, the first flywheel 13 may rotate due to inertia.

[0397] When the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 and the load factor of the engine 4 is less than the prescribed value X1 (%), the transition from the free mode to the viscous preparation mode is performed. That is, when the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition AA1) and the load factor of the engine 4 is less than the prescribed value X1 (second condition AA2) are satisfied, the transition from the free mode to the viscous preparation mode is performed. The prescribed value X1 is stored in the storage unit 112.

[0398] Here, when the transition to the free mode is automatically performed by starting the engine 4, the first flywheel 13 has not yet rotated. On the other hand, when the transition to the free mode is performed from other operation modes (see Figure 18 to Figure 21 , Fig.23 ) is executed, the first flywheel 13 rotates at a speed smaller than the speed (actual speed) of the engine 4. For example, when the viscous mode is transferred to the viscous preparation mode via the free mode, the first flywheel 13 rotates at a speed smaller than the speed (actual speed) of the engine 4.

[0399] After the transition to the free mode, the calculation unit 111 of the control device 110 determines whether the first condition AA1 is satisfied (S3). Specifically, the calculation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition AA1 is satisfied.

[0400] When the first condition is satisfied, the calculation unit 111 determines whether the second condition AA2 is satisfied (S4). Specifically, the calculation unit 111 (load factor calculation unit 111a) calculates the load factor based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount corresponding to the boost pressure stored in the storage unit 112, and compares the load factor with the specified value X1, thereby determining whether the second condition AA2 is satisfied (S4).

[0401] When the first condition AA1 and the second condition AA2 are satisfied at the same time, the operation unit 111 (action mode determination unit 111d) determines to transfer to the viscous preparation mode. As a result, a control signal for transferring to the viscous preparation mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the free mode to the viscous preparation mode (S5). At this time, based on the control signal (single-shot pulse current) sent from the control device 110, the second hydraulic piston 75 of the second clutch 27 is driven, the first friction plate 27A moves, and the second clutch 27 becomes a midway state from the disconnected state to the connected state (a state in which the invalid stroke is eliminated). When at least one of the first condition AA1 and the second condition AA2 is not satisfied ("No" in S3 or "No" in S4), the control system 100 does not transfer to the viscous preparation mode.

[0402] The reason why the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition AA1) is used as a condition in the transition from the free mode to the viscous preparation mode is that if the rotation speed of the first flywheel 13 is greater than the rotation speed (actual rotation speed) of the engine 4, the load applied to the engine 4 increases. In addition, the reason why the load factor of the engine 4 is less than the predetermined value X1 (second condition AA2) is used as a condition is that when the transition from the viscous preparation mode to the viscous mode is made in a state where the load factor of the engine 4 is high, the load applied to the engine 4 increases.

[0403] <Transition from sticky preparation mode to sticky mode>

[0404] based on Fig.18 The transition from the viscous preparation mode to the viscous mode will be described.

[0405] When the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4, the torque rate of the engine 4 is less than the specified value Y1 (%), and the actual rotation speed of the engine 4 is at the target rotation speed, the transition from the viscous preparation mode to the viscous mode is executed. That is, when the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition BB1), the torque rate of the engine 4 is less than the specified value Y1 (second condition BB2), and the actual rotation speed of the engine 4 is at the target rotation speed (third condition BB3) are all satisfied, the transition from the viscous preparation mode to the viscous mode is executed. The specified value Y1 is stored in the storage unit 112.

[0406] After the transition to the viscous preparation mode, the calculation unit 111 of the control device 110 determines whether the first condition BB1 is satisfied (S6). Specifically, the calculation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition BB1 is satisfied.

[0407] When the first condition BB1 is satisfied, the operation unit 111 determines whether the second condition BB2 is satisfied (S7). Specifically, the operation unit 111 (torque rate calculation unit 111b) calculates the torque rate based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount of the full load curve stored in the storage unit 112, and compares the torque rate with the specified value Y1 to determine whether the second condition BB2 is satisfied (S7).

[0408] When the second condition BB2 is satisfied, the calculation unit 111 compares the target speed of the engine 4 stored in the storage unit 112 with the speed (actual speed) of the engine 4 calculated by the second speed sensor 15 to determine whether the third condition BB3 is satisfied ( S8 ).

[0409] When the first condition BB1, the second condition BB2 and the third condition BB3 are all satisfied, the operation unit 111 (action mode determination unit 111d) decides to transfer to the viscous mode. As a result, a control signal for transferring to the viscous mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the viscous preparation mode to the viscous mode (S10). At this time, the second clutch 27 switches from the state of eliminating the invalid stroke to the connection state through the half-clutch state based on the control signal (second control signal) from the control device 110. When at least one of the first condition BB1, the second condition BB2 and the third condition BB3 is not satisfied ("No" in S6, "No" in S7 or "No" in S8), it does not transfer to the viscous mode.

[0410] In the transition from the above-mentioned viscous preparation mode to the viscous mode, the reason why the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition BB1) is that in the viscous preparation mode, the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4. In addition, the reason why the torque rate of the engine 4 is less than the specified value Y1 (second condition BB2) is that if the transition to the viscous mode is performed in a state where the torque rate of the engine 4 is high, the load applied to the engine 4 becomes large. In addition, the reason why the actual rotation speed of the engine 4 is at the target rotation speed (third condition BB3) is that the transition to the viscous mode is performed after confirming that the actual rotation speed of the engine 4 is stable at the target rotation speed. The third condition BB3 can prevent the transition to the viscous mode in a state where a load is applied to the engine 4 due to the work load or the like (a state where the actual rotation speed of the engine 4 is less than the target rotation speed).

[0411] <Transition from sticky preparation mode to free mode>

[0412] based on Fig.18 The transition from the sticky preparation mode to the free mode is described.

[0413] When the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 and the number of attempts to connect the second clutch 27 (number of single triggers) within the prescribed time T1 reaches the prescribed number N1, the transition from the viscous preparation mode to the free mode is executed. That is, when the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition CC1) and the number of attempts to connect the second clutch 27 (number of single triggers) within the prescribed time T1 reaches the prescribed number N1 (second condition CC2) is satisfied, the transition from the viscous preparation mode to the free mode is executed. The prescribed time T1 and the prescribed number N1 are stored in the storage unit 112. The prescribed time T1 is measured by a timer (not shown), and the measured value is sent to the control device 110.

[0414] In other words, the second condition CC2 is when the number of single-trigger implementations for connecting the second clutch 27 within the specified time T1 reaches the specified number N1. The number of single-trigger implementations for connecting the second clutch 27 is the number of single-trigger pulse currents supplied to the hydraulic control valve (solenoid valve) driving the second hydraulic piston 75, and the second hydraulic piston 75 pushes the first friction plate 27A of the second clutch 27.

[0415] After switching to the viscous preparation mode, the calculation unit 111 of the control device 110 determines whether the first condition CC1 is satisfied (S6). Specifically, the calculation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition CC1 is satisfied.

[0416] When the first condition CC1 is satisfied, the operation unit 111 determines whether the second condition CC2 is satisfied (S9) when at least one of the second condition BB2 and the third condition BB3 is not satisfied (when the condition for transitioning to the sticky mode is not satisfied). Specifically, the operation unit 111 counts the number of single-trigger executions (single-trigger count) within the specified time T1, and determines whether the single-trigger count within the specified time T1 has reached N1 times (S9).

[0417] When the first condition CC1 and the second condition CC2 are satisfied, the operation unit 111 (action mode determination unit 111d) determines to transfer to the free mode. As a result, a control signal for transferring to the free mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the viscous preparation mode to the free mode (S11). At this time, the second clutch 27 is switched from the state of eliminating the invalid stroke to the disconnected state based on the control signal (second control signal) from the control device 110. When at least one of the first condition CC1 and the second condition CC2 is not satisfied ("No" in S6 or "No" in S10), the control system 100 does not transfer to the free mode.

[0418] In the viscous preparation mode, a one-shot (supply of a one-shot pulse current) for connecting the second clutch 27 is performed at a predetermined time interval, but even if the one-shot is performed a predetermined number of times N1 within the predetermined time T1, if the condition for transitioning to the viscous mode is not satisfied, the one-shot is terminated and the preparation state for connecting the second clutch 27 is released. As a result, the transition to the free mode is not performed without transitioning to the viscous mode.

[0419] For example, when the operating load increases and the torque rate increases in the viscous preparation mode, when the viscous preparation mode is shifted to the viscous mode, the rotation speed of the engine 4 may drop sharply because the engine 4 and the first flywheel 13 are connected via the second clutch 27. In this case, in the viscous preparation mode, when the condition for shifting to the viscous mode is not satisfied (the torque rate is less than Y1%) even at the stage where the single trigger is performed a predetermined number of times N1 within a predetermined time T1, the engine speed can be prevented from dropping sharply by controlling not to shift to the viscous mode (shifting to the free mode).

[0420] The reason why the rotation speed of the first flywheel 13 is lower than the rotation speed (actual rotation speed) of the engine 4 (first condition CC1) is a condition for the transition from the viscous preparation mode to the free mode is that in the viscous preparation mode, the rotation speed of the first flywheel 13 is lower than the rotation speed (actual rotation speed) of the engine 4. In addition, the reason why the number of attempts to connect the second clutch 27 within the prescribed time T1 (the number of single-shot implementations) reaches the prescribed number N1 (second condition CC2) is a condition that, when the condition for transitioning to the viscous mode is not satisfied even at the stage where the prescribed number N1 of single-shots are implemented within the prescribed time T1, it is determined that the transition to the viscous mode should be abandoned in order to prevent the engine speed from dropping rapidly as described above.

[0421] <Transition from Sticky Mode to Charge Ready Mode>

[0422] based on Fig.19 The transition from the stick mode to the charge preparation mode will be described.

[0423] When the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 and the load factor of the engine 4 is less than the prescribed value X2 (%), the transition from the viscous mode to the charging preparation mode is performed. That is, when the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (first condition DD1) and the load factor of the engine 4 is less than the prescribed value X2 (second condition DD2), the transition from the viscous mode to the charging preparation mode is performed. The prescribed value X2 is stored in the storage unit 112.

[0424] After the transition to the viscous mode, the calculation unit 111 of the control device 110 determines whether the first condition CC1 is satisfied (S12). Specifically, the calculation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition DD1 is satisfied.

[0425] When the first condition DD1 is satisfied, the calculation unit 111 determines whether the second condition DD2 is satisfied (S13). Specifically, the calculation unit 111 (load factor calculation unit 111a) calculates the load factor based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount corresponding to the boost pressure stored in the storage unit 112, and compares the load factor with the specified value X2 to determine whether the second condition DD2 is satisfied (S13).

[0426] When the first condition DD1 and the second condition DD2 are satisfied, the operation unit 111 (action mode determination unit 111d) decides to transfer to the charge preparation mode. As a result, a control signal for transferring to the charge preparation mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the viscosity mode to the charge preparation mode (S14). At this time, based on the control signal (first control signal) sent from the control device 110, the first hydraulic piston 73 of the first clutch 26 is driven, the first friction plate 26A moves, and the first clutch 26 becomes a midway state (a state where the invalid stroke is eliminated) of switching from the disconnected state to the connected state. In addition, the second clutch 27 is switched from the connected state to the disconnected state based on the control signal (second control signal) sent from the control device 110. When at least one of the first condition DD1 and the second condition DD2 is not satisfied ("No" in S12 or "No" in S13), the charge preparation mode is not transferred.

[0427] In the transition from the above-mentioned viscous mode to the charging preparation mode, the reason why the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (first condition DD1) is that, by making the rotation speed of the first flywheel 13 the same as the actual rotation speed of the engine 4, it can be judged that the rotation speed of the first flywheel 13 is ready to be increased to be greater than the actual rotation speed of the engine 4. In addition, the reason why the load rate of the engine 4 is less than the specified value X2 (second condition DD2) is that, when the load rate of the engine 4 is low, it is not necessary to use the rotation power of the first flywheel 13 to assist the rotation power of the engine 4, and therefore it is judged that the transition preparation to the charging mode should be performed to prepare for future assistance and accumulate rotation power in the first flywheel 13.

[0428] <Transition from sticky mode to free mode>

[0429] based on Fig.19 The transition from the sticky mode to the free mode is described.

[0430] When the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 and the torque rate of the engine 4 is equal to or greater than the prescribed value Y2 (%), the transition from the viscous mode to the free mode is performed. That is, when the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition EE1) and the torque rate of the engine 4 is greater than or equal to the prescribed value Y2 (second condition EE2), the transition from the viscous mode to the free mode is performed. The prescribed value Y2 is stored in the storage unit 112.

[0431] After the transition to the viscous mode, the calculation unit 111 of the control device 110 determines whether the first condition EE1 is satisfied (S12). Specifically, the calculation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition EE1 is satisfied. In addition, in the viscous mode, since the rotation speed of the first flywheel 13 does not exceed the rotation speed (actual rotation speed) of the engine 4, in the case where "engine speed = rotation speed of the first flywheel" is not satisfied in step 12 executed after the transition to the viscous mode, "engine speed> rotation speed of the first flywheel" is satisfied.

[0432] When the first condition EE1 is satisfied, the operation unit 111 determines whether the second condition EE2 is satisfied (S15). Specifically, the operation unit 111 (torque rate calculation unit 111b) calculates the torque rate based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount of the full load curve stored in the storage unit 112, and compares the torque rate with the specified value Y2 to determine whether the second condition EE2 is satisfied (S15).

[0433] When the first condition EE1 and the second condition EE2 are satisfied, the operation unit 111 (action mode determination unit 111d) determines to shift to the free mode. As a result, a control signal for shifting to the free mode is sent from the control device 110 to the action unit 140, and the control system 100 shifts from the viscous mode to the free mode (S16). At this time, the second clutch 27 switches from the connected state to the disconnected state based on the control signal (second control signal) from the control device 110. When at least one of the first condition EE1 and the second condition EE2 is not satisfied ("No" in S12 or "No" in S15), the control system 100 does not shift to the free mode.

[0434] In the transition from the above-mentioned viscous mode to the free mode, the reason why the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition EE1) is that in the viscous mode, the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4. In addition, the reason why the torque rate of the engine 4 is greater than or equal to the predetermined value Y2 (second condition EE2) is that in the viscous mode, when the load (torque rate) of the engine 4 increases sharply due to the application of a work load, the transition to the free mode is performed to reduce the load of the engine 4.

[0435] <Transition from Charge Ready Mode to Charge Mode>

[0436] based on Fig. 20 The transition from the charging preparation mode to the charging mode will be described.

[0437] When the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 and the torque rate of the engine 4 is less than the specified value Y3 (%), the transfer from the charging preparation mode to the charging mode is performed. That is, when the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (first condition FF1) and the torque rate of the engine 4 is less than the specified value Y3 (second condition FF2), the transfer from the charging preparation mode to the charging mode is performed. The specified value Y3 is stored in the storage unit 112.

[0438] After the transition to the charging preparation mode, the calculation unit 111 of the control device 110 determines whether the first condition FF1 is satisfied (S17). Specifically, the calculation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition FF1 is satisfied.

[0439] When the first condition FF1 is satisfied, the operation unit 111 determines whether the second condition FF2 is satisfied (S13). Specifically, the operation unit 111 (torque rate calculation unit 111b) calculates the torque rate based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount of the full load curve stored in the storage unit 112, and compares the torque rate with the specified value Y3, thereby determining whether the second condition FF2 is satisfied (S18).

[0440] When the first condition FF1 and the second condition FF2 are met, the operation unit 111 (action mode determination unit 111d) decides to transfer to the charging mode. As a result, a control signal for transferring to the charging mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the charging preparation mode to the charging mode (S19). At this time, based on the control signal (first control signal) sent from the control device 110, the first clutch 26 switches from the state of eliminating the invalid stroke to the connection state. When at least one of the first condition FF1 and the second condition FF2 is not met ("No" in S17 or "No" in S18), it does not transfer to the charging mode.

[0441] In the transition from the charging preparation mode to the charging mode, the reason why the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (first condition FF1) is that, by the rotation speed of the first flywheel 13 reaching the same as the rotation speed (actual rotation speed) of the engine 4, it can be judged that the rotation speed of the first flywheel 13 is ready to be increased to be greater than the actual rotation speed of the engine 4. In addition, the reason why the torque rate of the engine 4 is less than the specified value Y3 (second condition FF2) is that it is not preferable to transfer to the charging mode in a state where the load (torque rate) of the engine 4 is high in order to increase the load of the engine 4, and it is preferable to transfer to the charging mode in a state where the load (torque rate) of the engine 4 is low, so as to accumulate rotational energy in the first flywheel 13.

[0442] <Transition from Charge Ready Mode to Free Mode>

[0443] based on Fig. 20 The transition from the charge preparation mode to the free mode is described.

[0444] When the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 and the number of attempts to connect the first clutch 26 within the specified time T2 (the number of single triggers) reaches the specified number N2, the transfer from the charging preparation mode to the free mode is executed. That is, when the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (first condition GG1) and the number of attempts to connect the second clutch 27 within the specified time T2 (the number of single triggers) reaches the specified number N2 (second condition GG2), the transfer from the charging preparation mode to the free mode is executed. The specified time T2 and the specified number N2 are stored in the storage unit 112. The specified time T2 is measured by a timer (not shown), and the measured value is sent to the control device 110.

[0445] In other words, the second condition GG2 is when the number of single-shot implementations for connecting the first clutch 26 within the specified time T2 reaches the specified number N2. The number of single-shot implementations for connecting the first clutch 26 is the number of single-shot pulse currents supplied to the hydraulic control valve (solenoid valve) driving the first hydraulic piston 73, which drives the first hydraulic piston 73 to push the first friction plate 26A.

[0446] After the transition to the charging preparation mode, the operation unit 111 of the control device 110 determines whether the first condition GG1 is satisfied (S17). Specifically, the operation unit 111 compares the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 with the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15 to determine whether the first condition GG1 is satisfied.

[0447] When the first condition GG1 is satisfied, the operation unit 111 determines whether the second condition GG2 is satisfied (S20) when the second condition FF2 is not satisfied (when the condition for transferring to the charging mode is not satisfied). Specifically, the operation unit 111 counts the number of single triggers implemented within the specified time T2, and determines whether the number of single triggers within the specified time T2 reaches N2 times (S20).

[0448] When the first condition GG1 and the second condition GG2 are met, the operation unit 111 (action mode determination unit 111d) decides to transfer to the free mode. As a result, a control signal for transferring to the free mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the charging preparation mode to the free mode (S21). At this time, the first clutch 26 switches from the state of eliminating the invalid stroke to the disconnected state based on the control signal (first control signal) from the control device 110. When at least one of the first condition GG1 and the second condition GG2 is not met ("No" in S17 or "No" in S20), it does not transfer to the free mode.

[0449] In the charging preparation mode, a one-shot (supply of a one-shot pulse current) for connecting the first clutch 26 is performed at a predetermined time interval, but even if the one-shot is performed a predetermined number of times N2 within the predetermined time T2, if the condition for transitioning to the charging mode is not satisfied, the one-shot is terminated and the connection preparation state of the first clutch 26 is released. As a result, the transition to the free mode is not performed without transitioning to the charging mode.

[0450] In the transition from the charging preparation mode to the free mode, the reason why the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (first condition GG1) is that in the charging preparation mode, the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4. In addition, the reason why the number of attempts to connect the second clutch 27 within the prescribed time T2 (the number of single triggers) reaches the prescribed number N2 (second condition GG2) is that even if the prescribed number N2 of single triggers are implemented within the prescribed time T2, if the conditions for transitioning to the charging mode are not met, the transition to the charging mode should be abandoned.

[0451] <Transition from Charging Mode to Boost Preparation Mode>

[0452] based on Fig.21 The transition from the charging mode to the supercharging preparation mode will be described.

[0453] When the rotation speed of the first flywheel 13 is a target rotation speed (first target rotation speed NA) greater than the rotation speed (actual rotation speed) of the engine 4 and the load factor of the engine 4 is less than the prescribed value X3 (%), the transfer from the charging mode to the supercharging preparation mode is performed. That is, when the rotation speed of the first flywheel 13 is the first target rotation speed NA greater than the rotation speed (actual rotation speed) of the engine 4 (first condition HH1) and the load factor of the engine 4 is less than the prescribed value X3 (second condition HH2), the transfer from the charging mode to the supercharging preparation mode is performed. The prescribed value X3 is stored in the storage unit 112.

[0454] The target speed (first target speed) NA of the first flywheel 13 is "the actual speed of the engine 4×the speed-increasing ratio a (a>1) of the speed-increasing mechanism 20". For example, when the speed-increasing ratio a=3, the target speed of the first flywheel 13=the actual speed of the engine 4×3. That is, in this case, the target speed of the first flywheel 13 is 3 times the actual speed of the engine 4. The speed-increasing ratio a is stored in the storage unit 112.

[0455] After the transition to the charging mode, the operation unit 111 of the control device 110 determines whether the first condition HH1 is satisfied (S22). Specifically, the operation unit 111 determines whether the first condition HH1 is satisfied based on the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18, the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15, the first target rotation speed NA stored in the storage unit 112, and the speed increase ratio a.

[0456] When the first condition HH1 is satisfied, the operation unit 111 determines whether the second condition HH2 is satisfied (S23). Specifically, the operation unit 111 (load factor calculation unit 111a) calculates the load factor based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount corresponding to the boost pressure stored in the storage unit 112, and compares the load factor with the specified value X3, thereby determining whether the second condition HH2 is satisfied (S23).

[0457] When the first condition HH1 and the second condition HH2 are satisfied, the operation unit 111 (action mode determination unit 111d) decides to transfer to the boost preparation mode. As a result, a control signal for transferring to the boost preparation mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the charging mode to the boost preparation mode (S24). At this time, based on the control signal (single-shot pulse current) sent from the control device 110, the second hydraulic piston 75 of the second clutch 27 is driven, the first friction plate 27A moves, and the second clutch 27 becomes a midway state from the disconnected state to the connected state (a state in which the invalid stroke is eliminated). When at least one of the first condition HH1 and the second condition HH2 is not satisfied ("No" in S22 or "No" in S23), the mode is not transferred to the boost preparation mode.

[0458] In the transition from the charging mode to the supercharging preparation mode, the reason why the rotation speed of the first flywheel 13 is set to the first target rotation speed NA (first condition HH1) which is greater than the rotation speed (actual rotation speed) of the engine 4 is that, when the rotation speed of the first flywheel 13 reaches the first target rotation speed NA, it can be determined that the rotational energy of the amount that can assist the engine 4 is accumulated in the first flywheel 13. In addition, the reason why the load factor of the engine 4 is set to be less than the specified value X3 (second condition HH2) is that, when the load factor of the engine 4 is small, it can be determined that the engine 4 does not need to be assisted (it is sufficient to prepare for the transition to the supercharging mode instead of the transition to the supercharging mode).

[0459] <Transition from Charge Mode to Free Mode>

[0460] based on Fig.21 The transition from the charging mode to the free mode is explained.

[0461] When the rotation speed of the first flywheel 13 is greater than the rotation speed of the engine 4 (actual rotation speed) and less than the first target rotation speed NA and the torque rate of the engine 4 is equal to or greater than the specified value Y4, the transfer from the charging mode to the free mode is performed. That is, when the rotation speed of the first flywheel 13 is greater than the rotation speed of the engine 4 (actual rotation speed) and less than the first target rotation speed NA (first condition JJ1) and the torque rate of the engine 4 is greater than the specified value Y4 (second condition JJ2), the transfer from the charging mode to the free mode is performed. The first target rotation speed NA and the specified value Y4 are stored in the storage unit 112. As described above, the target rotation speed NA of the first flywheel 13 is "the actual rotation speed of the engine 4 × the speed increase ratio a (a>1) of the speed increase mechanism 20".

[0462] After transferring to the charging mode, the operation unit 111 of the control device 110 determines whether the first condition JJ1 is satisfied (S22). Specifically, the operation unit 111 determines whether the first condition JJ1 is satisfied based on the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18, the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15, the first target rotation speed NA stored in the storage unit 112, and the speed increase ratio a. In addition, in the charging mode, since the rotation speed of the first flywheel 13 is greater than the actual rotation speed of the engine 4 and does not exceed the first target rotation speed NA, in step 22 performed after the charging mode is transferred, when "engine speed × a (a>1) = rotation speed of the first flywheel" is not satisfied, "the rotation speed of the first flywheel 13 is greater than the actual rotation speed of the engine 4 and less than the first target rotation speed NA" is satisfied.

[0463] When the first condition JJ1 is satisfied, the operation unit 111 determines whether the second condition JJ2 is satisfied (S25). Specifically, the operation unit 111 (torque rate calculation unit 111b) calculates the torque rate based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount of the full load curve stored in the storage unit 112, and compares the torque rate with the specified value Y4, thereby determining whether the second condition JJ2 is satisfied (S25).

[0464] When the first condition JJ1 and the second condition JJ2 are met, the operation unit 111 (action mode determination unit 111d) decides to transfer to the free mode. As a result, a control signal for transferring to the free mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the charging mode to the free mode (S26). At this time, the first clutch 26 switches from the connected state to the disconnected state based on the control signal (first control signal) from the control device 110. When at least one of the first condition JJ1 and the second condition JJ2 is not met ("No" in S22 or "No" in S25), it does not transfer to the free mode.

[0465] In the transition from the above-mentioned charging mode to the free mode, the reason why the rotation speed of the first flywheel 13 is greater than the rotation speed of the engine 4 (actual rotation speed) and less than the first target rotation speed NA (first condition JJ1) and the torque rate of the engine 4 is greater than the specified value Y4 (second condition JJ2) is that when a large load is applied to the engine 4 during the process of accumulating the rotational energy that can assist the engine 4 in the first flywheel 13, the mode is transferred to the free mode to reduce the load applied to the engine 4.

[0466] <Transition from Boost Preparation Mode to Boost Mode>

[0467] based on Fig. 22 The transition from the supercharging preparation mode to the supercharging mode will be described.

[0468] When the rotation speed of the first flywheel 13 is a first target rotation speed NA greater than the rotation speed (actual rotation speed) of the engine 4, the load rate of the engine 4 is greater than the prescribed value X4 (%), and the reduction rate of the engine 4 is greater than the prescribed value Z, the transition from the supercharging preparation mode to the supercharging mode is performed. That is, the transition from the supercharging preparation mode to the supercharging mode is performed when the rotation speed of the first flywheel 13 is a first target rotation speed NA greater than the rotation speed (actual rotation speed) of the engine 4 (first condition KK1), the load rate of the engine 4 is greater than the prescribed value X4 (second condition KK2), and the reduction rate of the engine 4 is greater than the prescribed value Z (third condition KK3) are all satisfied. The first target rotation speed NA, the prescribed value X3, and the prescribed value Z are stored in the storage unit 112. As described above, the target rotation speed NA of the first flywheel 13 is "the actual rotation speed of the engine 4×the speed increasing ratio a (a>1) of the speed increasing mechanism 20".

[0469] After the transition to the supercharging preparation mode, the calculation unit 111 of the control device 110 determines whether the first condition KK1 is satisfied (S27). Specifically, the calculation unit 111 determines whether the first condition KK1 is satisfied based on the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18, the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15, the first target rotation speed NA stored in the storage unit 112, and the speed increase ratio a.

[0470] When the first condition KK1 is satisfied, the operation unit 111 determines whether the second condition KK2 is satisfied (S28). Specifically, the operation unit 111 (load rate calculation unit 111a) calculates the load rate based on the indicated injection amount detected by the accelerator opening sensor 19 and the limited injection amount corresponding to the boost pressure stored in the storage unit 112, and compares the load rate with the specified value X4, thereby determining whether the second condition KK2 is satisfied (S28).

[0471] When the second condition KK2 is satisfied, the operation unit 111 determines whether the third condition KK3 is satisfied (S29). Specifically, the operation unit 111 (the decrease rate calculation unit 111c) calculates the decrease rate based on the actual speed of the engine 4 detected by the second speed sensor 15 and the target speed of the engine 4 stored in the storage unit 112, and compares the decrease rate with the specified value Z, thereby determining whether the third condition KK3 is satisfied (S29).

[0472] When the first condition KK1, the second condition KK2, and the third condition KK3 are all satisfied, the operation unit 111 (action mode determination unit 111d) decides to transfer to the boost mode. As a result, a control signal for transferring to the boost mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the boost preparation mode to the boost mode (S30). At this time, the second clutch 27 switches from the state of eliminating the invalid stroke to the connected state through the half-clutch state based on the control signal (second control signal) from the control device 110. That is, the second clutch 27 switches from the connected preparation state to the connected state. When at least one of the first condition KK1, the second condition KK2, and the third condition KK3 is not satisfied ("No" in S27, "No" in S28, or "No" in S29), it does not transfer to the boost mode.

[0473] In the transition from the above-mentioned supercharging preparation mode to the supercharging mode, the reason for taking the rotation speed of the first flywheel 13 to be the first target rotation speed NA (first condition KK1) which is greater than the rotation speed (actual rotation speed) of the engine 4 as a condition is that, by the rotation speed of the first flywheel 13 reaching the first target rotation speed NA, it can be judged that the rotational energy of the amount that can assist the engine 4 is accumulated in the first flywheel 13. In addition, the reason for taking the load rate of the engine 4 to be greater than the prescribed value X4 (second condition KK2) and the decrease rate of the engine 4 to be greater than the prescribed value Z (third condition KK3) as conditions is that, if the load of the engine 4 is not reduced under the condition that such conditions are met, the engine may stop, and therefore it can be judged that the rotational power of the first flywheel 13 needs to be used to assist the rotational power of the engine 4.

[0474] <Transition from boost mode to viscosity mode>

[0475] based on Fig.23 The transition from the supercharging mode to the viscous mode will be described.

[0476] When the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4, the transition from the supercharging mode to the viscous mode is performed. In other words, when the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (condition LL1), the transition from the supercharging mode to the viscous mode is performed.

[0477] After the transition to the supercharging mode, the calculation unit 111 of the control device 110 determines whether the condition LL1 is satisfied (S31). Specifically, the calculation unit 111 determines whether the condition LL1 is satisfied by comparing the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 and the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15.

[0478] If the condition LL1 is satisfied, the mode is shifted to the viscous mode (S32). At this time, the states of the first clutch 26 and the second clutch 27 do not change from the supercharging mode, but the rotation speed of the first flywheel 13 changes from a state greater than the actual rotation speed of the engine 4 to a state less than the actual rotation speed of the engine 4. If the condition LL1 is not satisfied (if "No" in S31), the mode is not shifted to the viscous mode.

[0479] The reason why the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4 (condition LL1) in the transition from the above-mentioned supercharging mode to the viscous mode is that since the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4, it can be determined that the rotation power accumulated in the first flywheel 13 cannot assist the rotation power of the engine 4 (the rotation energy that can be supplied to assist the engine is exhausted). That is, since it can be determined that the engine cannot be assisted in the supercharging mode, the supercharging mode is transferred to the viscous mode. As a result, although the rotation power of the engine 4 cannot be assisted, the engine 4 can be made viscous, and a sharp drop in the rotation speed of the engine 4 can be suppressed.

[0480] <Transition from Boost Mode to Free Mode>

[0481] based on Fig.23 The transition from the boost mode to the free mode will be described.

[0482] When the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4, the load factor of the engine 4 is less than the specified value X5 (%), and the actual rotation speed of the engine 4 is less than the target rotation speed, the transfer from the supercharging mode to the free mode is executed. That is, when the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition MMM1), the load factor of the engine 4 is less than the specified value X5 (second condition MM2), and the actual rotation speed of the engine 4 is less than the target rotation speed (third condition MM3) are all satisfied, the transfer from the supercharging mode to the free mode is executed. The specified value X5 and the target rotation speed of the engine 4 are stored in the storage unit 112.

[0483] After the transition to the supercharging mode, the calculation unit 111 of the control device 110 determines whether the first condition MM1 is satisfied (S33). Specifically, the calculation unit 111 determines whether the first condition MM1 is satisfied by comparing the rotation speed of the first flywheel 13 measured by the first rotation speed sensor 18 and the rotation speed (actual rotation speed) of the engine 4 calculated by the second rotation speed sensor 15.

[0484] When the first condition MM1 is satisfied, the operation unit 111 determines whether the second condition MM2 (S34) is satisfied. Specifically, the operation unit 111 (load rate calculation unit 111a) calculates the load rate based on the indicated injection amount detected by the throttle opening sensor 19 and the limited injection amount corresponding to the boost pressure stored in the storage unit 112, and compares the load rate with the specified value X5, thereby determining whether the second condition MM2 (S34) is satisfied.

[0485] When the second condition MM2 is satisfied, the operation unit 111 determines whether the third condition MM3 is satisfied (S34). Specifically, the operation unit 111 determines whether the third condition MM3 is satisfied by comparing the actual speed of the engine 4 detected by the second speed sensor 15 with the target speed of the engine 4 stored in the storage unit 112 (S35).

[0486] When the first condition MM1, the second condition MM2 and the third condition MM3 are all satisfied, the operation unit 111 (action mode determination unit 111d) decides to transfer to the free mode. As a result, a control signal for transferring to the free mode is sent from the control device 110 to the action unit 140, and the control system 100 transfers from the boost mode to the free mode (S36). At this time, the second clutch 27 switches from the connected state to the disconnected state based on the control signal (second control signal) from the control device 110. In the case where at least one of the first condition MM1, the second condition MM2 and the third condition MM3 is not satisfied (the case of "No" in S33 or "No" in S34 or "No" in S35), it does not transfer to the free mode.

[0487] In the transition from the above-mentioned supercharging mode to the free mode, the reason why the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4 (first condition MM1) is that since the rotation speed of the first flywheel 13 is less than the rotation speed (actual rotation speed) of the engine 4, it can be judged that the rotation power of the first flywheel 13 cannot be used to assist the rotation power of the engine 4 (the supercharging mode cannot be maintained). In addition, the reason why the load rate of the engine 4 is less than the specified value X5 (second condition MM2) is that in the process of assisting the rotation power of the engine 4 by the rotation power of the first flywheel 13 in the supercharging mode, when the load applied to the engine 4 is reduced and no assistance is required, it is still necessary to prevent the engine 4 from being assisted by the rotation power of the first flywheel 13 even though the load of the engine 4 is light. In addition, the reason why the actual rotation speed of the engine 4 is less than the target rotation speed (third condition MM3) is that in the supercharging mode, the actual rotation speed of the engine 4 is recovering from a reduced state (increasing), so the actual rotation speed of the engine 4 is less than the target rotation speed.

[0488] <Transition to Engine Off Mode>

[0489] The transition to the engine shutdown mode is performed by a flameout operation by an operator riding on the work vehicle 1, etc. When in an operation mode other than the engine shutdown mode, the engine 4 is turned off (the spark plug is not ignited) by performing a flameout operation, etc., and the transition is made to the engine shutdown mode. When the transition is made to the engine shutdown mode, when one of the first clutch 26 and the second clutch 27 is not connected, the clutch is connected based on a control signal (a first control signal or a second control signal) from the control device 110. As a result, the first clutch 26 and the second clutch 27 are connected. However, as described above, in the engine shutdown mode, when the rotation speed of the first flywheel 13 is sufficiently low (for example, below the idle speed of the engine 4), one or both of the first clutch 26 and the second clutch 27 may not be connected.

[0490] <Additional explanation on the transition of operation mode>

[0491] Next, additional explanation will be given on the transition of the above-mentioned operation modes.

[0492] from Fig.15 As can be seen from the above description, in the control system 100, although it is possible to transfer from the free mode to the viscous preparation mode and then to the viscous mode, it is not possible to transfer from the free mode to the charging preparation mode and then to the charging mode. The transfer to the charging mode requires the transfer from the viscous mode via the charging preparation mode. That is, in order to transfer from the free mode to the charging mode, it is necessary to pass through the viscous mode. The reason is explained below.

[0493] In the charging mode, by connecting the first clutch 26, the rotation speed of the first flywheel 13 is greater than the rotation speed (actual rotation speed) of the engine 4 (for example, when the speed increase rate = 3, it is 3 times the engine speed), so a large load is applied to the engine 4. Therefore, if the free mode is transferred to the charging mode without passing through the viscous mode, a large load will be suddenly applied to the engine 4. On the other hand, in the viscous mode, by connecting the second clutch 27, the rotation speed of the first flywheel 13 becomes less than the rotation speed (actual rotation speed) of the engine 4, so the load applied to the engine 4 is small. Therefore, by temporarily transferring from the free mode to the charging mode via the viscous mode, it is possible to prevent the engine 4 from being suddenly applied with a load.

[0494] In the work vehicle 1, it is desirable that the first flywheel 13 rotates at a higher speed than the engine 4 so as to assist the engine 4 when the load of the engine 4 increases due to an increase in the work load, etc. For this purpose, it is necessary to increase the speed of the rotational power of the engine 4 and transmit it to the first flywheel 13 by switching to the charging mode. However, if the charging mode is switched to when the work load is large, the load of the engine 4 increases and hinders the work. Therefore, in the control system 100, while confirming whether the load of the engine 4 is a load that does not hinder the work, the free mode is switched to the charging mode via the viscous mode, thereby gradually increasing the speed of the first flywheel 13.

[0495] As described above, as conditions for the transfer of the action mode, there are cases where the load rate of the engine 4 is used and cases where the torque rate is used. This point is explained below. The reason why the torque rate is sometimes used instead of the load rate is that even when the load on the engine 4 is small, the load rate is 100% when the speed of the engine 4 increases. For example, when transferring from the charging preparation mode to the charging mode, the first clutch 26 becomes connected, the speed of the first flywheel 13 increases, and thus the speed of the engine 4 increases. At this time, if "the load rate is less than the specified value" is used as the condition (threshold) when transferring from the charging preparation mode to the charging mode, it cannot be transferred to the charging mode. On the other hand, the torque rate will not reach 100% even if the speed of the engine 4 increases when the load on the engine 4 is small. Therefore, if "the torque rate is less than the specified value" is used as the condition (threshold) when transferring from the charging preparation mode to the charging mode, it can be transferred to the charging mode.

[0496] In this way, when the speed of the engine 4 increases under a light workload (when the speed of the first flywheel 13 increases), the load rate and the torque rate diverge. When the speed of the engine 4 increases, the torque rate is used instead of the load rate as a condition for the shift of the action mode, thereby enabling the shift of the action mode to be reliably performed even when the speed of the engine 4 increases under a light workload.

[0497] Therefore, it is preferred to use the load rate as a condition for shifting the action mode when the engine 4 is in a state of increasing speed (a state of increasing speed of the first flywheel 13), and to use the torque rate as a condition for shifting the action mode when the engine 4 is in a state of not increasing speed (a state of not increasing speed of the first flywheel 13).

[0498] The load rates X1, X2, X3, X4, and X5 as the conditions (thresholds) for the above-mentioned action mode transition may all be the same value, or may be partially or completely different values. In addition, the torque rates Y1, Y2, Y3, and Y4 may all be the same value, or may be partially or completely different values. In addition, the prescribed times T1 and T2 may be the same time or different times. In addition, the single trigger times N1 and N2 may be the same number of times or different numbers of times.

[0499] As described above, except for the transition to the engine OFF mode, the transition to each operation mode (switching between a plurality of operation modes) is performed when predetermined conditions are satisfied.

[0500] In order to switch between the plurality of operation modes, the control device 110 performs intermittent control on the first clutch 26 and the second clutch 27. Here, "performing intermittent control on the first clutch 26 and the second clutch 27" includes: the control device 110 sends a control signal (first control signal, second control signal) for intermittently switching the first clutch 26 and / or the second clutch 27, and a method (first method) of switching the intermittent state of the first clutch 26 and / or the second clutch 27 according to the control signal; and the control device 110 notifies the operator that the first clutch 26 and / or the second clutch 27 can be switched, and the operator performs a predetermined operation based on the notification, thereby switching the intermittent state of the first clutch 26 and / or the second clutch 27 (second method). In the control system 100, either the first method or the second method can be adopted.

[0501] Although the first method and the second method can be used for the transfer of all the above-mentioned operation modes (except the transfer to the engine off mode), the second method is particularly suitable for the transfer from the charging mode to the supercharging preparation mode.

[0502] The following describes the case where the second method is applied to the transition from the charging mode to the supercharging preparation mode. In this case, in the charging mode, when the rotation speed of the first flywheel 13 reaches the first target rotation speed (first condition HH1) and the load factor of the engine 4 is less than the specified value X3 (second condition HH2), the control device 110 notifies the operator that the charging mode can be switched (transferred) to the supercharging preparation mode.

[0503] In this case, after the action mode determination unit 111d of the control device 110 determines to switch from the charging mode to the supercharging preparation mode, it notifies the operator that the mode can be switched (transferred) to the supercharging preparation mode. The control device 110 does not automatically send a control signal for transferring to the supercharging preparation mode to the action unit 140 based on the decision of the action mode determination unit 111d, but sends a control signal for transferring to the supercharging preparation mode to the action unit 140 based on the operation of the operator. That is, the control device 110 first notifies the operator that the mode can be switched to the supercharging preparation mode, and when the operator performs an operation for switching to the supercharging preparation mode in response to the notification, the control signal for transferring to the supercharging preparation mode is sent to the action unit 140.

[0504] For example, notification that the charging mode can be switched to the supercharging preparation mode is made by displaying it on the screen of the display input device 130 . Fig.24A , Fig. 24B An example of screen display when a notification that the mode can be switched from the charging mode to the supercharging preparation mode is given by displaying on the screen of the display input device 130 is shown. Fig.24A and Fig. 24B The case where the display input device 130 is a touch panel type display device is shown.

[0505] Fig.24A A screen 131A of the display input device 130 is shown in a state where the charging mode cannot be switched to the supercharging preparation mode (a state where any one of the first condition HH1 and the second condition HH2 is not satisfied) in the charging mode. In this state, the screen 131A only displays that the charging mode is in execution (charging in progress). In this state, the operator cannot perform the switching operation from the charging mode to the supercharging preparation mode. An indicator 132 indicating the progress of charging (the accumulation status of the rotational energy to the first flywheel 13) is displayed on the screen 131A. In the illustrated example, the indicator 132 indicates the progress of charging according to the length of the bar graph 132b in the display frame 132a. The progress of charging is calculated by (actual speed of the first flywheel 13 / target speed of the first flywheel 13). By observing the indicator 132, the operator can easily grasp the progress of charging.

[0506] Fig. 24BThe screen 131B of the display input device 130 is shown in a state where the charging mode can be switched to the boost preparation mode (a state where both the first condition HH1 and the second condition HH2 are satisfied) under the charging mode. In this state, on the screen 131B, the indicator 132 indicates that the charging is 100% (the actual speed of the first flywheel 13 reaches the target speed). In addition, the display 133 of "transfer to boost preparation mode" is performed. The display 133 is a notification that it is possible to switch from the charging mode to the boost preparation mode. In this state, the operator can perform a switching operation from the charging mode to the boost preparation mode by touching the display 133 of "transfer to boost preparation mode". That is, the control device 100 sends a control signal to the second clutch 27 based on the operator's touch operation on the display 133.

[0507] In addition, the notification method for switching from the charging mode to the supercharging preparation mode is not limited to the method of performing the notification by displaying on the screen of the display input device 130. For example, a method of notifying by lighting or flashing a light such as an LED, or a method of notifying by sound may also be adopted. In addition, the method for the operator to perform the switching operation from the charging mode to the supercharging preparation mode in response to the notification is not limited to the method of touching the screen of the display input device 130, and may be performed by, for example, operating an operation switch (operation button, etc.) provided separately from the display input device 130.

[0508] Fig.25 is an example of a timing diagram of the control system 100 .

[0509] Below, based on Fig.25 An example of transition of the operation mode of the control system 100 is described. Fig.25 The figure shows a case where the load factors X1 to X5 , which are conditions for the operation mode transition, are all the same value and the torque factors Y1 to Y4 are all the same value.

[0510] When the engine 4 is started, it is transferred to the free mode, and the speed (actual speed) of the engine 4 increases as time passes. At this time, the indicated pressure (first indicated pressure) of the first clutch 26 and the indicated pressure (second indicated pressure) of the second clutch 27 are 0, and the first clutch 26 and the second clutch 27 are in a disconnected state. Therefore, the speed (actual speed) of the first flywheel 13 is 0. In addition, the load factor and torque rate of the engine 4 increase as the engine 4 is started, and decrease when the engine 4 reaches the target speed.

[0511] When the speed of the first flywheel 13 is lower than the speed (actual speed) of the engine 4 (0), and the load factor of the engine 4 decreases and becomes lower than the predetermined value X1, the free mode is shifted to the viscous preparation mode. In the viscous preparation mode, the first clutch 26 is kept disconnected, but the second clutch 27 is in a state of eliminating the invalid stroke by implementing a one-shot (adding a one-shot pulse current).

[0512] When the actual speed of the engine 4 reaches the target speed and the speed of the first flywheel 13 is less than the speed (actual speed) (0) of the engine 4, if the torque rate of the engine 4 is less than the predetermined value Y1, the viscous preparation mode is shifted to the viscous mode. In the viscous mode, the first clutch 26 is kept disconnected, but the second clutch 27 is connected. By connecting the second clutch 27, the first flywheel 13 rotates and increases in speed.

[0513] In the viscous preparation mode, when the torque rate of the engine 4 is low (less than the specified value Y1), a control signal is sent to switch the second clutch 27 from the connection preparation state to the connection state, and the second clutch 27 is switched to the connection state, thereby transferring to the viscous mode.

[0514] When the second clutch 27 is in the connected state, the rotation speed (actual rotation speed) of the engine 4 is temporarily reduced by connecting the first flywheel 13 to the engine 4, but then returns to the target rotation speed. In addition, when the second clutch 27 is in the connected state, the first flywheel 13 starts to rotate and increases to the same as the actual rotation speed of the engine 4. At this time, the load factor and torque rate of the engine 4 become high. The descent rate of the engine 4 temporarily increases when the second clutch 27 is in the connected state, and then decreases.

[0515] In the viscous mode, when the speed of the first flywheel 13 reaches the same speed as the speed (actual speed) of the engine 4, the load rate and torque rate of the engine 4 are reduced. When the load rate is less than the specified value X2, it is difficult to cause a sharp drop in the speed of the engine 4, so the viscous mode is transferred to the charging preparation mode. In the charging preparation mode, the first clutch 26 is in a state of eliminating the invalid stroke by implementing a single trigger (adding a single trigger pulse current), and the second clutch 27 is switched from the connected state to the disconnected state.

[0516] When the rotation speed of the first flywheel 13 is the same as the rotation speed (actual rotation speed) of the engine 4, when the torque rate of the engine 4 is less than the specified value Y3, the charging preparation mode is transferred to the charging mode. In the charging mode, the first clutch 26 is connected and the second clutch 27 is disconnected. By connecting the first clutch 26, the rotation speed (actual rotation speed) of the engine 4 is temporarily reduced, but then returns to the target rotation speed. In addition, by connecting the first clutch 26, the rotation speed of the first flywheel 13 exceeds the actual rotation speed of the engine 4 and increases.

[0517] When the speed of the first flywheel 13 reaches the first target speed NA which is greater than the speed (actual speed) of the engine 4 and the load factor of the engine 4 is less than the specified value X3, the charging mode is transferred to the supercharging preparation mode. In the supercharging preparation mode, the first clutch 26 is maintained in the connected state, and the second clutch 27 is in a state of eliminating the invalid stroke by implementing a single trigger (adding a single trigger pulse current).

[0518] exist Fig.25 2 shows a state where, after the transition to the supercharging preparation mode, the load rate, torque rate, and drop rate of the engine 4 increase sharply due to the sharp increase in the work load of the work vehicle 1, and the rotation speed (actual rotation speed) of the engine 4 decreases. In this state, it is necessary to use the rotation power of the first flywheel 13 to assist the rotation power of the engine 4. Therefore, it is necessary to transition from the supercharging preparation mode to the supercharging mode.

[0519] The transition from the supercharging preparation mode to the supercharging mode is performed when the rotation speed of the first flywheel 13 reaches the first target rotation speed NA (at Fig.25 In the initial stage of the supercharging preparation mode, the first target speed is reached, the load rate of the engine 4 is greater than a predetermined value X4 (%), and the reduction rate of the engine 4 is greater than a predetermined value Z.

[0520] In the supercharging mode, the first clutch 26 is switched to the disconnected state, and the second clutch 27 is switched to the connected state. As a result, the rotational power of the first flywheel 13 is transmitted to the engine 4, and the rotational power of the engine 4 is assisted by the rotational power of the first flywheel 13. As a result, the rotational speed (actual rotational speed) of the engine 4 increases, and the load rate, torque rate, and droop rate of the engine 4 decrease. In addition, the rotational speed of the first flywheel 13 decreases as the assisting time increases.

[0521] exist Fig.25, the state of switching from the boost mode to the engine shutoff mode is shown. When the engine is shut off in the boost mode, the engine 4 and the first flywheel 13 gradually decelerate while rotating by inertia. In the engine shutoff mode, the first clutch 26 and / or the second clutch 27 are in a connected state, and the first flywheel 13 is connected to the engine 4 via the first clutch 26 and / or the second clutch 27. Therefore, the first flywheel 13 with a large inertia force can be stopped in a short time. In addition, Fig.25 2 shows a case where only the second clutch 27 is in the connected state, but both the first clutch 26 and the second clutch 27 may be in the connected state.

[0522] <Effect>

[0523] The characteristic structure of the work vehicle 1 of the above-described embodiment and the effects based on the structure are as follows.

[0524] The working vehicle 1 comprises: an engine 4; a first flywheel 13, which receives the rotational power of the engine 4 and rotates; a speed change device 16, which selectively receives the rotational power of the engine 4 and the rotational power of either the engine 4 or the first flywheel 13, changes the speed and outputs the rotational power; a first power transmission path 31, which transmits the rotational power of the engine 4 to the first flywheel 13; a second power transmission path 32, which transmits the rotational power of the first flywheel 13 to the speed change device 16, the first power transmission path 31 and the second power transmission path 32 are independent of each other, a first clutch 26 is provided on the first power transmission path 31, and a second clutch 27 is provided on the second power transmission path 32, which intermittently transmits the rotational power from the engine 4 to the first flywheel 13.

[0525] According to this structure, the first power transmission path 31 for transmitting the rotational power of the engine 4 to the first flywheel 13 and the second power transmission path 32 for transmitting the rotational power of the first flywheel 13 to the speed change device 16 are configured as mutually independent paths, so when a speed change mechanism is provided on one path, the speed change mechanism does not affect the other path. Therefore, the rotational power output from the engine 4 can be accelerated in the first power transmission path 31 and transmitted to the first flywheel 13, and the transmitted rotational power can be output to the speed change device 16 in a non-decelerated manner in the second power transmission path 32. In addition, since clutches (first clutch 26 and second clutch 27) for intermittently transmitting the rotational power are provided on each path, it is possible to switch between a state in which the rotational power of the engine 4 is transmitted to the first flywheel 13 and a state in which the rotational power of the first flywheel 13 is output to the speed change device 16. Thus, when the operating load is small, the rotational power of the engine 4 is stored in the first flywheel 13 as rotational energy, and when the operating load of the engine 4 is large, the rotational power of the first flywheel 13 can be used to assist the rotational power of the engine 4.

[0526] The first power transmission path 31 is provided with a speed increasing mechanism 20 for increasing the speed of the rotational power of the engine 4 and transmitting it to the first flywheel 13 . The second power transmission path 32 transmits the rotational power of the first flywheel 13 to the transmission 16 without passing through a speed reducing mechanism.

[0527] According to this structure, the rotational power of the engine 4 can be accelerated by the speed increasing mechanism 20 and transmitted to the first flywheel 13, and the rotational power of the first flywheel 13 can be output to the speed change device 16 without deceleration, so that high rotational energy can be accumulated in the first flywheel 13 and the high rotational energy can be directly transmitted to the speed change device 16. Therefore, when the workload is large, the rotational power of the first flywheel 13 can be used to effectively assist the rotational power of the engine 4.

[0528] The work vehicle 1 also includes a third power transmission path 33 for transmitting the rotational power of the engine 4 to the transmission 16 without passing through the first flywheel 13 . The third power transmission path 33 always connects the output shaft 4 a of the engine 4 and the input shaft 16 a of the transmission 16 .

[0529] According to this configuration, the rotational power of the engine 4 can be transmitted to the transmission 16 through the third power transmission path 33 without passing through the first flywheel 13 , so that the rotational power of the engine 4 can be input to the transmission 16 independently of the rotation of the first flywheel 13 .

[0530] In addition, the speed increasing mechanism 20 is composed of a planetary gear mechanism including a sun gear 21, planetary gears 22 and a ring gear 23. The ring gear 23 is fixed in a non-rotatable manner. The rotational power of the engine 4 is input into the planetary gears 22 and transmitted to the first flywheel 13 via the sun gear 21. The rotational power of the first flywheel 13 is transmitted to the speed change device 16 without passing through the planetary gear mechanism.

[0531] According to this structure, by transmitting the rotational power of the engine 4 from the planetary gear 22 to the sun gear 21, it can be accelerated and input to the first flywheel 13. In addition, by transmitting the rotational power of the first flywheel 13 to the speed change device 16 without passing through the planetary gear mechanism, the rotational power of the first flywheel 13 can be output to the speed change device 16 without reducing speed.

[0532] Furthermore, the work vehicle 1 includes a second flywheel 14 connected to the output shaft 4 a of the engine 4 , and the first flywheel 13 is rotatable independently of the second flywheel 14 .

[0533] According to this structure, when the first clutch 26 and the second clutch 27 are disconnected, the first flywheel 13 can be rotated regardless of the rotation of the second flywheel 14. Thus, even when the second flywheel 14 stops or decelerates, the rotation of the first flywheel 13 can be maintained without being affected by the second flywheel 14.

[0534] Furthermore, the first flywheel 13 is disposed between the second flywheel 14 and the transmission 16 in the axial length direction of the output shaft 4 a of the engine 4 .

[0535] According to this structure, the radial size (outer diameter) of the power transmission mechanism 6 can be reduced, and power transmission from the second flywheel 14 to the first flywheel 13 and power transmission from the second flywheel 14 to the speed change device 16 can be smoothly performed.

[0536] The work vehicle 1 also includes a relay shaft 17 interposed between the output shaft 4 a of the engine 4 and the transmission 16 to form a third power transmission path 33 . The relay shaft 17 is provided to penetrate the first flywheel 13 .

[0537] According to this configuration, since the third power transmission path 33 is formed by the relay shaft 17 that passes through the first flywheel 13 , the third power transmission path 33 can be formed in a short distance and in a straight line without using a complicated mechanism.

[0538] In addition, according to the structure in which the first clutch 26 and the second clutch 27 are arranged in the radial direction of the relay shaft 17, the first clutch 26 and the second clutch 27 can be arranged in parallel along the wall of the housing 9. As a result, an oil path for supplying working oil to the first clutch 26 and an oil path for supplying working oil to the second clutch 27 can be provided along the wall. Therefore, it is easy to provide an oil path for supplying working oil to the first clutch 26 and the second clutch 27.

[0539] In addition, the first clutch 26 and the second clutch 27 are arranged in the axial length direction of the relay shaft 17, so that the outer diameter of the clutch device 25 composed of the first clutch 26 and the second clutch 27 can be reduced. Therefore, the inner diameter can be reduced while maintaining the outer diameter of the first flywheel 13, thereby increasing the inertia moment.

[0540] In addition, the work vehicle 1 has a housing 9 that accommodates a first flywheel 13, a first clutch 26, and a second clutch 27. A partition wall 9d is provided inside the housing 9 to divide the interior into a space for accommodating the first flywheel 13 and a space for accommodating the first clutch 26 and the second clutch 27. The first clutch 26 and the second clutch 27 are arranged at a position facing the partition wall 9d.

[0541] According to this structure, the oil passage for supplying the hydraulic oil to the first clutch 26 and the second clutch 27 can be provided along the partition wall 9d. Therefore, the oil passage for supplying the hydraulic oil to the first clutch 26 and the second clutch 27 can be easily provided.

[0542] The first clutch 26 and the second clutch 27 are multi-plate clutches having a plurality of friction plates, and are arranged on the inner peripheral side of the first flywheel 13 .

[0543] According to this structure, since the first clutch 26 and the second clutch 27 are composed of a multi-plate clutch, the outer diameter can be reduced while maintaining high power transmission performance. In addition, by arranging the first clutch 26 and the second clutch 27 on the inner peripheral side of the first flywheel 13, the axial length (length in the front-to-back direction) of the first flywheel 13 can be extended. Therefore, the inertia moment of the first flywheel 13 can be increased, and the rotational energy that can be accumulated in the first flywheel 13 can be increased.

[0544] In addition, the working vehicle 1 comprises: an engine 4; a flywheel 13 (the meaning of the first flywheel 13: the same below) that rotates by receiving the rotational power of the engine 4; a first clutch 26, which is arranged on a first path that connects the engine 4 and the flywheel 13, and makes the transmission of the rotational power through the first path intermittent; a second clutch 27, which is arranged on a second path that connects the engine 4 and the flywheel 13, and makes the transmission of the rotational power through the second path intermittent; a speed increasing mechanism 20, which is arranged on the first path, and when the first clutch 26 is in a connected state, increases the speed of the engine's rotational power and transmits it to the flywheel 13; a control device 110, which performs control related to the intermittence of the first clutch 26 and the second clutch 27 in order to switch a plurality of action modes, and the plurality of action modes include: a supercharging mode in which the rotation speed of the flywheel 13 is greater than the rotation speed of the engine 4, the first clutch 26 is disconnected and the second clutch 27 is connected; and a viscous mode in which the rotation speed of the flywheel 13 is less than the rotation speed of the engine 4, the first clutch 26 is disconnected and the second clutch 27 is connected.

[0545] According to this structure, the rotational power of the flywheel 13 can be efficiently used not only when the rotational speed of the flywheel 13 is high enough to assist the rotational power of the engine 4, but also when the rotational speed of the flywheel 13 is not high enough to assist the rotational power of the engine 4. Specifically, in the supercharging mode, the rotational speed of the flywheel 13 is high enough to assist the rotational power of the engine 4, so the rotational power of the engine 4 can be assisted by the rotational power of the flywheel 13. In the viscous mode, the rotational speed of the flywheel 13 is not high enough to assist the rotational power of the engine 4, but the inertial force of the flywheel 13 can prevent the rotational speed of the engine 4 from dropping sharply.

[0546] In addition, the plurality of operation modes include a charging mode in which the rotation speed of the flywheel 13 is lower than the target rotation speed and higher than the rotation speed of the engine 4 , the first clutch 26 is connected, and the second clutch 27 is disconnected.

[0547] According to this configuration, in the charging mode, by increasing the speed of the rotational power of the engine 4 and transmitting it to the flywheel 13 , high rotational energy can be accumulated in the flywheel 13 .

[0548] In addition, the multiple action modes include a mode that is switched before transferring to the viscous mode, namely a viscous preparation mode. In the viscous preparation mode, the rotation speed of the flywheel 13 is less than the rotation speed of the engine 4, the first clutch 26 is disconnected, and the second clutch 27 is in an intermediate state of switching from a disconnected state to a connected state.

[0549] According to this configuration, in the viscous preparation mode, since the second clutch 27 is in the midway state of switching to the connected state, preparations for shifting to the viscous mode are made, and the shift to the viscous mode can be smoothly performed.

[0550] In addition, the multiple action modes include a mode that is switched before transferring to the boost mode, namely, a boost preparation mode. In the boost preparation mode, the rotation speed of the flywheel 13 is the target rotation speed and is greater than the rotation speed of the engine 4, the first clutch 26 is connected, and the second clutch 27 is in an intermediate state of switching from a disconnected state to a connected state.

[0551] According to this configuration, in the supercharging preparation mode, since the second clutch 27 is in the midway state of being switched to the connected state, it is possible to prepare for the shift to the supercharging mode and smoothly perform the shift to the supercharging mode.

[0552] In addition, the plurality of action modes include a mode that is switched before transferring to the charging mode, namely, a charging preparation mode, in which the rotation speed of the flywheel 13 is less than the target rotation speed, the first clutch 26 is in the middle of switching from the disconnected state to the connected state, and the second clutch 27 is disconnected.

[0553] According to this configuration, in the charge preparation mode, the first clutch 26 is in the middle of switching to the connected state, so that preparation for the transition to the charge mode can be made and the transition to the charge mode can be smoothly performed.

[0554] The plurality of operation modes include a free mode in which the engine 4 is started, the first clutch 26 and the second clutch 27 are disconnected, and the flywheel 13 is stopped.

[0555] According to this configuration, in the free mode, the first clutch 26 and the second clutch 27 are disconnected to separate the flywheel 13 from the engine 4 , so that the load applied to the engine 4 can be reduced.

[0556] The plurality of operation modes include an engine off mode in which the spark plug of the engine 4 is not ignited, the first clutch 26 and the second clutch 27 are connected, and the flywheel 13 is decelerated.

[0557] According to this structure, in the engine off mode, the flywheel 13 can be quickly decelerated by connecting the first clutch 26 and the second clutch 27 to the engine 4. Therefore, even after the engine 4 is turned off, the flywheel 13 can be prevented from continuing to rotate for a long time due to inertia.

[0558] When the rotation speed of the flywheel 13 is lower than the rotation speed of the engine 4 and the load factor of the engine 4 is lower than a predetermined value, the control device 110 switches from the free mode to the viscosity preparation mode.

[0559] According to this configuration, when the rotation speed of the flywheel 13 is low and the load on the engine 4 is small, preparation for shifting to the viscous mode can be performed, so that the shift to the viscous mode can be performed smoothly.

[0560] When the rotation speed of the flywheel 13 is lower than the rotation speed of the engine 4 , the torque rate of the engine 4 is lower than a predetermined value, and the actual rotation speed of the engine 4 is at the target rotation speed, the control device 110 switches from the viscous preparation mode to the viscous mode.

[0561] According to this structure, when the speed of the flywheel 13 is lower than the speed of the engine 4, the load of the engine 4 is small, and the actual speed of the engine 4 has not decreased, the speed of the flywheel 13 can be increased by shifting to the viscous mode. Thus, when there is no need to assist the engine 4, the speed of the flywheel 13 can be increased to the speed of the engine 4 to prepare for the shift to the charging mode for further increasing the speed of the flywheel 13.

[0562] When the rotation speed of the flywheel 13 is lower than the rotation speed of the engine 4 and the number of attempts to engage the second clutch 27 within a predetermined time reaches a predetermined number, the control device 110 switches from the viscous preparation mode to the free mode.

[0563] According to this configuration, in the viscous preparation mode, the load on the engine 4 increases due to an increase in the workload, and so when the mode cannot be shifted to the viscous mode, the mode can be shifted to the free mode to reduce the load on the engine 4 .

[0564] In addition, when the rotation speed of the flywheel 13 is the same as the rotation speed of the engine 4 and the load factor of the engine 4 is less than a predetermined value, the control device 110 switches from the viscous mode to the charging preparation mode.

[0565] According to this configuration, in a state where the load on the engine 4 is light, preparations for shifting to the charging mode can be made in order to accumulate rotational energy in the flywheel 13 , so that the shift to the charging mode can be smoothly performed.

[0566] When the rotation speed of the flywheel 13 is lower than the rotation speed of the engine 4 and the torque rate of the engine 4 is equal to or higher than a predetermined value, the control device 110 switches from the viscous mode to the free mode.

[0567] According to this configuration, when the load on the engine 4 increases due to an increase in the work load or the like, the load on the engine 4 can be reduced by shifting from the viscous mode to the free mode, thereby preventing interference with the work.

[0568] In addition, when the rotation speed of the flywheel 13 is the same as the rotation speed of the engine 4 and the torque rate of the engine 4 is less than a predetermined value, the control device 110 switches from the charging preparation mode to the charging mode.

[0569] According to this configuration, when the load on the engine 4 is light and the rotation speed of the flywheel 13 is high, the mode can be shifted to the charging mode in order to store rotational energy in the flywheel 13 .

[0570] Furthermore, when the rotation speed of the flywheel 13 is equal to the rotation speed of the engine 4 and the number of attempts to connect the first clutch 26 within a predetermined time is reached, the control device 110 switches from the charging preparation mode to the free mode.

[0571] According to this configuration, in the charge preparation mode, the load on the engine 4 increases due to an increase in the workload, and so when the mode cannot be shifted to the charge mode, the mode can be shifted to the free mode to reduce the load on the engine 4 .

[0572] When the rotation speed of the flywheel 13 is a target rotation speed greater than that of the engine 4 and the load factor of the engine 4 is less than a predetermined value, the control device 110 switches from the charging mode to the supercharging preparation mode or notifies that the mode can be switched to the supercharging preparation mode.

[0573] According to this structure, the speed of the flywheel 13 is increased to be sufficient to assist the engine 4, but when the load of the engine 4 is small, preparations can be made to switch to the supercharging mode in order to cope with the increase in the load of the engine 4. Thus, when the load of the engine 4 increases, the transition to the supercharging mode can be smoothly performed.

[0574] When the rotation speed of the flywheel 13 is greater than the rotation speed of the engine 4 and less than the target rotation speed, and the torque rate of the engine 4 is greater than or equal to a predetermined value, the control device 110 switches from the charging mode to the free mode.

[0575] According to this configuration, when the rotation speed of the flywheel 13 is increased, if the load on the engine 4 increases due to an increase in the workload, etc., the load on the engine 4 can be reduced by shifting to the free mode.

[0576] When the rotation speed of the flywheel 13 is a target rotation speed greater than the rotation speed of the engine 4, the load factor of the engine 4 is greater than a predetermined value, and the deceleration rate of the engine 4 is greater than a predetermined value, the control device 110 switches from the supercharging preparation mode to the supercharging mode.

[0577] According to this structure, when the speed of the flywheel 13 is increased to a state sufficient to assist the engine 4 (a state in which high rotational energy is accumulated in the flywheel 13) and the load of the engine 4 increases, it is possible to switch to the supercharging mode and use the rotational power of the flywheel 13 to assist the rotational power of the engine 4.

[0578] In addition, when the rotation speed of the flywheel 13 becomes the same as the rotation speed of the engine 4, the control device 110 switches from the supercharging mode to the viscous mode.

[0579] According to this structure, in the supercharging mode, the rotational power of the flywheel 13 is used to assist the rotational power of the engine 4. As a result, when the rotational power of the flywheel 13 decreases and cannot be assisted, the rotation speed of the engine 4 can be prevented from dropping sharply by switching to the viscosity mode.

[0580] When the rotation speed of the flywheel 13 is lower than the rotation speed of the engine, the load factor of the engine 4 is lower than a predetermined value, and the actual rotation speed of the engine 4 is lower than the target rotation speed, the control device 110 switches from the supercharging mode to the free mode.

[0581] According to this configuration, in the supercharging mode, when the load on the engine 4 decreases due to a decrease in the workload and the assist of the engine 4 is no longer required, the flywheel 13 is prevented from assisting the engine 4 when the load on the engine 4 is small by shifting to the free mode.

[0582] The embodiments of the present invention have been described above, but the embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0583] Description of Reference Numerals

[0584] 1: Operation vehicle

[0585] 4: Engine

[0586] 4a: Output shaft of the engine

[0587] 9: Housing (flywheel housing)

[0588] 9d: Dividing wall

[0589] 13: First flywheel

[0590] 14: Second flywheel

[0591] 16: Speed ​​change device

[0592] 16a: Input shaft of the transmission

[0593] 17: Relay shaft

[0594] 20: Speed ​​increasing mechanism

[0595] 21: Sun gear

[0596] 22: Planetary gear

[0597] 23: Ring gear

[0598] 26: First Clutch

[0599] 27: Second clutch

[0600] 31: First power transmission path

[0601] 32: Second power transmission path

[0602] 33: Third power transmission path

Claims

1. A working vehicle, wherein: have: engine; A first flywheel receives the rotational power of the engine and rotates; a transmission device that selectively receives the rotational power of the engine and the rotational power of the engine and the first flywheel, changes the speed of the rotational power, and outputs the rotational power; a first power transmission path for transmitting the rotational power of the engine to the first flywheel; as well as The second power transmission path transmits the rotational power of the first flywheel to the speed change device. The first power transmission path and the second power transmission path are independent of each other. A first clutch is provided on the first power transmission path for intermittently transmitting the rotational power from the engine to the first flywheel. The second power transmission path is provided with a second clutch for interrupting the transmission of the rotational power from the first flywheel to the transmission device.

2. The work vehicle according to claim 1, wherein: A speed increasing mechanism is provided on the first power transmission path to increase the speed of the rotational power of the engine and transmit it to the first flywheel. The second power transmission path transmits the rotational power of the first flywheel to the speed change device without passing through a speed reduction mechanism.

3. The working vehicle according to claim 1 or 2, wherein: A third power transmission path is provided for transmitting the rotational power of the engine to the transmission device without passing through the first flywheel. The third power transmission path constantly connects the output shaft of the engine and the input shaft of the transmission.

4. The work vehicle according to claim 2, wherein: The speed increasing mechanism is composed of a planetary gear mechanism including a sun gear, planetary gears and a ring gear. The ring gear is fixed in a non-rotatable manner, The rotational power of the engine is input to the planetary gear and transmitted to the first flywheel via the sun gear. The rotational power of the first flywheel is transmitted to the speed change device without passing through the planetary gear mechanism.

5. The work vehicle according to claim 1, wherein: A second flywheel connected to an output shaft of the engine is provided, and the first flywheel is rotatable independently of the second flywheel.

6. The work vehicle according to claim 5, wherein: The first flywheel is arranged between the second flywheel and the speed change device in the axial length direction of the output shaft.

7. The work vehicle according to claim 3, wherein: A relay shaft is provided between the output shaft and the transmission device to constitute the third power transmission path, The relay shaft is disposed to pass through the first flywheel.

8. The work vehicle according to claim 7, wherein: The first clutch and the second clutch are arranged side by side in a radial direction of the relay shaft.

9. The work vehicle according to claim 7, wherein: The first clutch and the second clutch are arranged side by side in the axial length direction of the relay shaft.

10. The work vehicle according to claim 8, wherein: The working vehicle includes a housing that accommodates the first flywheel, the first clutch, and the second clutch. A partition wall is provided inside the housing to partition the inside into a space for accommodating the first flywheel and a space for accommodating the first clutch and the second clutch. The first clutch and the second clutch are arranged at positions facing the partition wall.

11. The work vehicle according to claim 9, wherein: The first clutch and the second clutch are multi-plate clutches including a plurality of friction plates, and are arranged on the inner peripheral side of the first flywheel.

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