Power transmission

Abstract

To provide a power transmission device including a motor as a driving power source and capable of satisfying traveling performance of a vehicle and a driving state required for PTO.SOLUTION: A power transmission device includes: a differential mechanism 13 having at least three rotary elements of a first rotary element S to which a motor 2 is connected, a second rotary element C connected to a driving wheel, and a third rotary element Rr connected to PTO; a first brake forbidding rotation of the second rotary element C; and a second brake Br forbidding rotation of the third rotary element Rr. The power transmission device is configured to be able to set a first deceleration stage so as to make a rotational frequency of the first rotary element S higher than a rotational frequency of the third rotary element Rr by engaging the first brake and releasing the second brake Br, and to set a second deceleration stage so as to make the rotational frequency of the first rotary element S higher than a rotational frequency of the second rotary element C by engaging the second brake Br and releasing the first brake.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power transmission device capable of transmitting torque of a driving force source to drive wheels and to a power take-off device that transmits torque to a device provided outside a vehicle, such as a mounting device. [Background technology]

[0002] Patent Documents 1 to 3 describe a power transmission device configured to transmit engine power to a power take-off device. This power transmission device includes an engine, a torque converter with a lock-up clutch connected to the output shaft of the engine, a speed change mechanism connected to the torque converter, a gear connected to the input shaft of the speed change mechanism, and a gear that meshes with the gear and inputs torque to the power take-off device.

[0003] The power transmission device described in Patent Document 1 is configured to output auxiliary power to the outside by engaging a clutch inside the power take-off device depending on the position of the shift lever and the on / off state of the power take-off switch.

[0004] Furthermore, the power transmission device described in Patent Document 2 is configured to engage the lock-up clutch when the engine speed is equal to or higher than a predetermined speed when the shift lever is in the neutral range or the parking range and the power take-off switch is on, and to release the lock-up clutch when the engine speed is below the predetermined speed.

[0005] Furthermore, the power transmission device described in Patent Document 3 is configured to switch on the clutch of the power take-off device when the speed change mechanism is in any of the neutral range, first forward gear, second forward gear, and reverse range.

[0006] Patent document 4 describes a safety device that is configured to operate the mounting device only when the vehicle is not running by arranging in series a neutral switch that is turned on when the transmission gear is in neutral, and a PTO switch that is turned on when the mounting device PTO switch is on, on the power line connecting the chassis ignition and the mounting device control device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2004-204888 A [Patent Document 2] Japanese Patent Application Publication No. 7-304348 [Patent Document 3] JP 2003-28285 A [Patent Document 4] Japanese Patent Application Publication No. 9-12299 Summary of the Invention [Problem to be solved by the invention]

[0008] The power transmission devices described in Patent Documents 1 to 3 are configured to transmit power from an engine as a driving power source for traveling to a power take-off device for driving a mounting device or the like. On the other hand, an electric vehicle equipped with a motor as a driving power source for traveling has different characteristics of a driving power source from a vehicle equipped with an engine as a driving power source. That is, a motor as a driving power source is usually configured to operate at a higher rotation speed and lower torque than an engine. Therefore, when a motor is provided as a driving power source, in order to satisfy the driving performance required of the vehicle and the rotation speed or torque required for input to the power take-off device, it is not possible to immediately adopt a power transmission device provided with an engine as a driving power source, and there is room for development of a power transmission device using a motor as a driving power source.

[0009] This invention has been made in light of the above technical problems, and aims to provide a power transmission device that is equipped with a motor as a driving force source and is capable of satisfying the vehicle's driving performance and the operating conditions required of a power take-off device. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a power transmission device that is configured to enable a vehicle to travel using power output from a motor as a driving power source, and to transmit the power output from the motor to a power take-off device for transmitting the power to a device external to the vehicle. It is a place a differential mechanism having at least three rotating elements, namely a first rotating element connected to the motor, a second rotating element connected to a drive wheel, and a third rotating element, and in which the three rotating elements are connected to be able to rotate differentially; a first brake that prohibits rotation of the second rotating element, a second brake that prohibits rotation of the third rotating element, and an output side rotating member that rotates integrally with the third rotating element and is connected to the power take-off device, and torque is output from the motor in a state in which rotation of the second rotating element is prohibited by the first brake and rotation of the third rotating element is permitted by the second brake. and a travel mode in which torque is transmitted from the motor to the drive wheels by setting a second reduction gear stage in which the rotation speed of the first rotating element is higher than the rotation speed of the third rotating element and torque is transmitted from the motor to the drive wheels while outputting torque from the motor in a state in which rotation of the third rotating element is prohibited by the second brake and rotation of the second rotating element is permitted by the first brake. The differential mechanism further includes a fourth rotating element and a third brake that prohibits rotation of the fourth rotating element, and is configured to be able to set another driving mode in which torque is transmitted to the drive wheels and the vehicle travels by outputting torque from the motor in a state in which rotation of the fourth rotating element is prohibited by the third brake. The present invention is characterized in that

[0011] In addition, The present invention relates to a power transmission device that is capable of traveling using power output from a motor as a driving force source, and that is configured to transmit the power output from the motor to a power take-off device for transmitting the power output from the motor to a device external to the vehicle, the power transmission device having at least three rotating elements, namely a first rotating element to which the motor is connected, a second rotating element to which a driving wheel is connected, and a third rotating element, the power transmission device including a differential mechanism in which the three rotating elements are connected to be able to rotate differentially, a first brake that prohibits rotation of the second rotating element, a second brake that prohibits rotation of the third rotating element, and an output side rotating member that rotates integrally with the third rotating element and is connected to the power take-off device, and by outputting torque from the motor in a state in which rotation of the second rotating element is prohibited by the first brake and rotation of the third rotating element is permitted by the second brake, the rotation speed of the first rotating element is increased to a value equal to or larger than the rotation speed of the third rotating element. and a driving mode in which a second reduction stage is set at a rotation speed of the first rotating element higher than the rotation speed of the second rotating element by outputting torque from the motor while the second brake is used to prohibit rotation of the third rotating element and the first brake is used to allow rotation of the second rotating element, thereby transmitting torque from the motor to the drive wheels.The differential mechanism is configured to be able to set at least two modes: a PTO mode in which a first reduction stage is set at a rotation speed higher than the rotation speed of the second rotating element, and torque is transmitted from the motor to the drive wheels for driving, and the differential mechanism includes a stepped pinion type planetary gear mechanism having a sun gear, two ring gears with different numbers of teeth, and a carrier as rotating elements, and the first rotating element includes the sun gear, the second rotating element includes the carrier, and the third rotating element includes one of the two ring gears.

[0012] In addition, in this invention, the differential mechanism may further include a fourth rotating element and a third brake that prohibits rotation of the fourth rotating element, and may be configured to be able to set another driving mode in which torque is transmitted to the drive wheels and driving is performed by outputting torque from the motor while rotation of the fourth rotating element is prohibited by the third brake.

[0013] In addition, in this invention, the differential mechanism may be configured to be capable of setting a third reduction stage in which, when the fourth rotating element is stopped, the rotational speed of the first rotating element becomes higher than the rotational speed of the second rotating element and the reduction ratio, which is the rotational speed of the second rotating element relative to the rotational speed of the first rotating element, is smaller than the second reduction stage.

[0014] In the present invention, the differential mechanism is The first rotating element, the second rotating element, and the third rotating element may be arranged in this order, or the first rotating element, the third rotating element, and the second rotating element, on a collinear diagram showing a relationship between the relative rotational speeds of the first rotating element, the second rotating element, and the third rotating element. stomach. Effect of the Invention

[0015] According to this invention, the vehicle is provided with a differential mechanism in which at least three rotating elements are connected to be capable of differential rotation: a first rotating element to which a motor is connected, a second rotating element connected to a drive wheel, and a third rotating element that rotates integrally with an output rotating member connected to a power take-off device so as to be able to transmit torque; a first brake that prohibits rotation of the second rotating element; and a second brake that prohibits rotation of the third rotating element. The vehicle is configured to be able to set at least two modes: a PTO mode in which torque is transmitted from the motor to the power take-off device by setting a first reduction gear stage in which the rotation speed of the first rotating element is higher than that of the third rotating element by outputting torque from the motor while the first brake prohibits rotation of the second rotating element and allows rotation of the third rotating element by the second brake, and a travel mode in which torque is transmitted from the motor to the drive wheels by outputting torque from the motor while the second brake prohibits rotation of the third rotating element and allows rotation of the second rotating element by the first brake, setting a second reduction gear stage in which the rotation speed of the first rotating element is higher than that of the second rotating element. That is, the vehicle can travel by amplifying the torque of the motor and transmitting it to the drive wheels by making the third rotating element function as a reaction element, and can amplify the torque of the motor and transmit it to the power take-off device by making the second rotating element function as a reaction element. Therefore, in a power transmission device equipped with a motor that operates at high rotation speed and low torque as a driving force source, the vehicle can travel while satisfying driving performance such as the required driving force, and can transmit the rotation speed and torque required by the power take-off device. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view for explaining an example of a power transmission device according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram showing an example of a shift drum for switching between modes. [Diagram 3]6A and 6B are nomographic diagrams for explaining the rotation speed of each rotating element in a transmission, where FIG. 6A is a nomographic diagram showing the rotation speed of each rotating element when each driving mode is set, and FIG. 6B is a nomographic diagram showing the rotation speed of each rotating element when each stopping mode is set. [Figure 4] FIG. 4 is a skeleton diagram for explaining another example of a power transmission device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A cross-sectional view for explaining an example of a power transmission device according to an embodiment of the present invention is shown in Fig. 1. The power transmission device 1 shown in Fig. 1 includes a motor 2 as a driving force source. This motor 2 can be configured similarly to a motor as a driving force source provided in a conventionally known electric vehicle or hybrid vehicle, and can be configured, for example, by a three-phase AC motor, more specifically, by a permanent magnet synchronous motor or an induction motor.

[0018] The motor 2 shown in FIG. 1 is a permanent magnet synchronous motor. That is, the motor 2 is composed of an annular rotor 3 and an annular stator 4 arranged concentrically with the rotor 3 and provided with a predetermined gap from the outer circumferential surface of the rotor 3. The rotor 3 is composed of a plurality of cylindrical steel plates laminated in the axial direction of the motor 2, and a permanent magnet 5 is embedded in the outer circumferential side of the rotor 3, as in the conventional motor 2. Similarly, the stator 4 is composed of a plurality of cylindrical steel plates laminated in the axial direction of the motor 2. Furthermore, the stator 4 has a plurality of stator teeth protruding on the inner circumferential side formed at a predetermined interval in the circumferential direction, and a coil 6 is wound around each of the stator teeth.

[0019] The motor 2 configured as described above is accommodated in a cylindrical front housing 7. The outer periphery of the stator 4 is fixed to a predetermined position in the front housing 7 by bolts (not shown) or the like. A cylindrical rotor shaft 8 is connected to the inner periphery of the rotor 3 by spline engagement or the like. An annular partition wall 9 is formed on the output side (the right side in FIG. 1) of the front housing 7, and the rotor shaft 8 is rotatably held by the partition wall 9 via a ball bearing 10.

[0020] In the example shown in FIG. 1, annular plates 11 are arranged to clamp the laminated steel plates from both sides in the axial direction of the rotor 3, and nuts 12 are tightened onto the rotor shaft 8 to position the plates 11 and maintain the clamping pressure.

[0021] A transmission 13 is provided for varying and outputting the output torque of the motor 2 configured as described above. This transmission 13 corresponds to the "differential mechanism" in the embodiment of the present invention, and in the example shown in Fig. 1, is configured similarly to a conventional stepped pinion type planetary gear mechanism. That is, the transmission 13 is configured by a sun gear S, a front ring gear Rf, a rear ring gear Rr, a front pinion gear Pf meshed with the sun gear S and the front ring gear Rf, a rear pinion gear Pr integrated with the front pinion gear Pf and meshed with the rear ring gear Rr, and a carrier C that holds the front pinion gear Pf and the rear pinion gear Pr so that they can rotate and revolve, and the four rotating elements of the sun gear S, the front ring gear Rf, the rear ring gear Rr, and the carrier C are configured to be able to rotate differentially with respect to each other. In addition, the sun gear S corresponds to the "first rotating element" in an embodiment of the present invention, the carrier C corresponds to the "second rotating element" in an embodiment of the present invention, the rear ring gear Rr corresponds to the "third rotating element" in an embodiment of the present invention, and the front ring gear Rf corresponds to the "fourth rotating element" in an embodiment of the present invention.

[0022] The sun gear S is formed at the tip of a sun gear shaft 14 that is spline-engaged with the inner periphery of the rotor shaft 8, and a front ring gear Rf is disposed concentrically with the sun gear S. A front support plate 15 formed in an annular shape is connected to the inner periphery of the front ring gear Rf on the input side (left side in FIG. 1) in the axial direction so as to be integrally rotatable therewith by spline engagement, and an inner periphery of the front support plate 15 is fitted to the sun gear shaft 14 so as to be relatively rotatable therewith. The inner periphery of the front support plate 15 is located between the sun gear S and the partition wall 9, and thrust bearings 16, 17 for positioning the front support plate 15 are provided between the partition wall 9 and the front support plate 15, and between the front support plate 15 and the sun gear S, respectively.

[0023] A front pinion gear Pf meshes with the sun gear S and the front ring gear Rf. A plurality of front pinion gears Pf are provided at predetermined intervals in the circumferential direction of the sun gear S and the front ring gear Rf.

[0024] A pinion shaft 18 extending toward the output side (the right side in FIG. 1) in the axial direction is formed integrally with the front pinion gear Pf, and a rear pinion gear Pr is formed on the pinion shaft 18. The rear pinion gear Pr is formed with a smaller diameter than the front pinion gear Pf, and the rear ring gear Rr meshes with the rear pinion gear Pr. In other words, the rear ring gear Rr is disposed alongside the front ring gear Rf in the axial direction, and is formed with a smaller diameter than the front ring gear Rf.

[0025] A carrier C is provided to rotatably hold the pinion shaft 18. The carrier C shown in FIG. 1 includes an annular carrier plate 19 facing the tip end surface of the pinion shaft 18, and a cylindrical first support shaft portion 20 is formed at a position corresponding to the pinion shaft 18 in the circumferential direction of the carrier plate 19, and the tip end of the pinion shaft 18 is rotatably held by the first support shaft portion 20 via a needle bearing 21. A ball bearing 22 is fitted in a portion between the front pinion gear Pf and the rear pinion gear Pr in the axial direction of the pinion shaft 18, and a second support shaft portion 23 that fits into an outer race of the ball bearing 22 is formed on the carrier C. That is, the pinion shaft 18 is rotatably held by the carrier C via the needle bearing 21 and the ball bearing 22.

[0026] The carrier C is configured to function as an output element of the transmission 13. Accordingly, a cylindrical output shaft 24 is integrally formed on the inner periphery of the carrier plate 19. A thrust bearing 25 is interposed between the input side of the output shaft 24 and the sun gear S. Ball bearings 26, 27 are fitted to a portion on the output side of the position where the carrier plate 19 is formed. The ball bearings 26, 27 are fitted to a cylindrical rear cover 28 that abuts against an opening of the front housing 7. A connecting shaft 30 having a flange portion 29 is spline-engaged with the tip of the output shaft 24, and the connecting shaft 30 is connected to driving wheels via a propeller shaft and a differential mechanism with a final reduction gear (not shown).

[0027] A shaft 31 for driving an oil pump (not shown), etc. is inserted into the hollow portions of the output shaft 24, the sun gear shaft 14, and the rotor shaft 8, and the shaft 31 and the output shaft 24 are spline-engaged.

[0028] The transmission 13 configured as described above is configured to function as a reducer that increases and outputs the output torque of the motor 2 by engaging either the front ring gear Rf or the rear ring gear Rr. That is, the transmission 13 shown in Fig. 1 includes a front brake Bf that fixes the front ring gear Rf by connecting the front ring gear Rf to the rear cover 28, and a rear brake Br that fixes the rear ring gear Rr by connecting the rear ring gear Rr to the rear cover 28. The front brake Bf corresponds to the "third brake" in the embodiment of the present invention, and the rear brake Br corresponds to the "second brake" in the embodiment of the present invention.

[0029] Specifically, it comprises a cylindrical fixed shaft 32 that is fixed in the rotational direction by spline engagement with the inner circumferential surface of the rear cover 28, a cylindrical front sleeve Sf that is spline engaged with the fixed shaft 32 and configured to be engageable with the front ring gear Rf, and a cylindrical rear sleeve Sr that is spline engaged with the fixed shaft 32 and configured to be engageable with the rear ring gear Rr.

[0030] On the inner peripheral surface of the input side of the fixed shaft 32, first front spline teeth 33 are formed so as to be spaced a predetermined distance from the outer peripheral surface of the front ring gear Rf, and on the inner peripheral surface of the output side of the fixed shaft 32, first rear spline teeth 34 are formed so as to be spaced a predetermined distance from the outer peripheral surface of the rear ring gear Rr.

[0031] A front sleeve Sf is movably inserted between the inner peripheral surface of the input side of the fixed shaft 32 and the outer peripheral surface of the front ring gear Rf. The front sleeve Sf is a cylindrical member provided concentrically with the front ring gear Rf, and second front spline teeth 35 that constantly mesh with the first front spline teeth 33 are formed on the outer peripheral surface. Dog teeth 36 are formed on the inner peripheral surface of the tip side (output side) of the front sleeve Sf, and dog teeth 37 that mesh with the dog teeth 36 are formed on the outer peripheral surface of the front ring gear Rf. A front shift fork Ff that can move in the axial direction is engaged with the outer peripheral surface of the input side of the front sleeve Sf by operating the shift drum D shown in FIG. 2.

[0032] Therefore, by driving the shift drum D to move the front shift fork Ff and the front sleeve Sf in the axial direction, the dog teeth 36, 37 formed on the front sleeve Sf and the front ring gear Rf mesh with each other, and as a result, the rotation of the front ring gear Rf is prohibited. On the other hand, by releasing the meshing, the rotation of the front ring gear Rf is permitted. In other words, the fixed shaft 32 and the front sleeve Sf are configured to function as a front brake Bf.

[0033] Similarly, a rear sleeve Sr is movably inserted between the inner peripheral surface of the output side of the fixed shaft 32 and the rear ring gear Rr. The rear sleeve Sr is a cylindrical member provided concentrically with the rear ring gear Rr, and second rear spline teeth 38 that constantly mesh with the first rear spline teeth 34 are formed on the outer peripheral surface. Dog teeth 39 are formed on the inner peripheral surface of the tip side (input side) of the rear sleeve Sr, and dog teeth 40 that mesh with the dog teeth 39 are formed on the outer peripheral surface of the rear ring gear Rr. When the shift drum D is operated, a rear shift fork Fr that can move in the axial direction engages with the outer peripheral surface of the input side of the rear sleeve Sr.

[0034] Therefore, by driving the shift drum D to move the rear shift fork Fr and the rear sleeve Sr in the axial direction, the dog teeth 39, 40 formed on the rear sleeve Sr and the rear ring gear Rr mesh with each other, thereby prohibiting the rotation of the rear ring gear Rr. On the other hand, by releasing the meshing, the rotation of the rear ring gear Rr is permitted. In other words, the fixed shaft 32 and the rear sleeve Sr function as the rear brake Br.

[0035] The front shift fork Ff and the rear shift fork Fr may be configured to be moved by the same shift drum D, or a shift drum may be provided corresponding to each of the shift forks Ff, Fr.

[0036] In addition, in order to prevent the front sleeve Sf and the front ring gear Rf from unintentionally meshing with each other when there is a large difference in rotational speed between the front sleeve Sf and the front ring gear Rf, it is preferable that the dog teeth 36 formed on the front sleeve Sf and the dog teeth 37 formed on the front ring gear Rf are formed so that the tips of the dog teeth 36, 37 that face each other in the axial direction are tapered, and that an elastic member that is compressible in the movement direction of the front sleeve Sf is provided between the front shift fork Ff and the front sleeve Sf, or between the shift drum D and the front shift fork Ff.

[0037] Similarly, in order to prevent the rear sleeve Sr and the rear ring gear Rr from unintentionally meshing with each other when there is a large difference in rotational speed between them, it is preferable that the dog teeth 39 formed on the rear sleeve Sr and the dog teeth 40 formed on the rear ring gear Rr are formed so that their opposing tips in the axial direction are tapered, and that an elastic member compressible in the movement direction of the rear sleeve Sr is provided between the rear shift fork Fr and the rear sleeve Sr, or between the shift drum D and the rear shift fork Fr.

[0038] The above-described transmission 13 engages either the front brake Bf or the rear brake Br to transmit the torque of the motor 2 to the output shaft 24. That is, the sun gear S functions as an input element, either the front ring gear Rf or the rear ring gear Rr functions as a reaction element, and the carrier C functions as an output element.

[0039] Moreover, the power transmission device 1 in the embodiment of the present invention is configured so that power can be output from the above-mentioned speed change device 13, more specifically, the rear ring gear Rr to a power take-off device (hereinafter, referred to as PTO) not shown. Specifically, as shown in Fig. 1, an output side rotating member 44 is connected to the rear ring gear Rr, the output side rotating member 44 being configured of a cylindrical portion 41 formed so as to surround the outer periphery of the carrier C, an annular wall portion 42 connected to the output side end portion of the cylindrical portion 41, and a cylindrical output shaft portion 43 protruding in the axial direction from the radial center portion of the wall portion 42, and an output gear 45 is formed on the outer periphery of the output shaft portion 43.

[0040] The rear cover 28 is formed with a cylindrical shaft 46 that protrudes towards the transmission 13, and the inner periphery of the wall portion 42 is located between the carrier plate 19 and the cylindrical shaft 46. A thrust bearing 47 for positioning the wall portion 42 and allowing relative rotation with the carrier plate 19 is provided between the carrier plate 19 and the wall portion 42. The output shaft portion 43 is rotatably held on the cylindrical shaft 46 via two ball bearings 48, 49.

[0041] A countershaft 50 is provided parallel to the central axis of rotation of the transmission 13, and a PTO gear 51 that meshes with the output gear 45 is connected to the countershaft 50. This PTO gear 51 is a gear for inputting power to a PTO (not shown), and is configured so that torque is transmitted to the PTO via the PTO gear 51 and a clutch mechanism (not shown).

[0042] A parking brake or parking lock mechanism (hereinafter simply referred to as a parking brake) (not shown) is provided to selectively stop rotation of rotating members between the drive wheels and the transmission 13, such as the connecting shaft 30 or a propeller shaft connected to the connecting shaft 30. That is, by engaging the parking brake, rotation of the carrier C is prohibited. This parking brake corresponds to the "first brake" in the embodiment of the present invention.

[0043] Therefore, when the above-mentioned transmission 13 outputs torque from the motor 2 with the rotation of the carrier C prohibited by the parking brake and with the brakes Bf, Br released, the sun gear S functions as an input element, the carrier C functions as a reaction element, and the rear ring gear Rr functions as an output element, so that the torque of the motor 2 is amplified according to the gear ratio of the transmission 13 and transmitted to the PTO.

[0044] That is, the above-mentioned transmission 13 can set three driving modes, namely, a drive mode in which the front brake Bf is engaged and the rear brake Br and the parking brake are released, an extra-low mode in which the front brake Bf and the parking brake are released and the rear brake Br is engaged, and a disconnect mode in which the front brake Bf, the rear brake Br, and the parking brake are released, as well as two stopping modes, namely, a parking mode in which the front brake Bf, the rear brake Br, and the parking brake are engaged, and a PTO mode in which the front brake Bf and the rear brake Br are released and the parking brake is engaged.

[0045] Fig. 2 shows an example of a shift drum D for switching between the above-mentioned driving modes and stopping modes. The shift drum D shown in Fig. 2 is configured so that the front shift fork Ff and the rear shift fork Fr move by changing the rotation angle by a predetermined angle. In Fig. 2, the rotation angle of the shift drum D is shown in the up-down direction, the engagement position and release position of the front shift fork Ff are shown on the left side of the figure, and the engagement position and release position of the rear shift fork Fr are shown on the right side of the figure, with the engagement position indicated by a "●" symbol and the release position indicated by a "○" symbol.

[0046] As shown in FIG. 2, the shift drum D is rotated in one direction to switch the mode in the order of the parking (Park Lock) mode, the drive mode, the disconnect mode, and the extra low (Extra Lo) mode. When the shift drum D is rotated so that the rotation angle of the shift drum D becomes larger than the rotation angle at which the extra low mode is set, the mode is switched to the parking mode as shown in FIG. 2, and when the shift drum D is rotated in the opposite direction, the mode is switched from the lower side to the upper side in FIG. 2. That is, the drive mode and the extra low mode are switched via the disconnect mode or the parking mode. In other words, the mode can be switched from a state in which either the drive mode or the extra low mode is set to the disconnect mode or the parking mode by simply rotating the shift drum D in either direction by a predetermined angle.

[0047] As described above, the PTO mode is set by releasing the front brake Bf and the rear brake Br and engaging the parking brake, and the disconnection mode is set by releasing the front brake Bf, the rear brake Br, and the parking brake. Therefore, the rotation angle of the shift drum D is the same in the PTO mode and the disconnection mode, so in FIG. 2, the PTO mode is shown together with the disconnection mode.

[0048] FIG. 3(a) shows a nomogram for explaining the rotation speed of each rotating element in the transmission 13 when each driving mode is set, and FIG. 3(b) shows a nomogram for explaining the rotation speed of each rotating element in the transmission 13 when each stop mode is set. Each nomogram shows the relationship of the relative rotation speed of each rotating element, and lines representing each rotating element are drawn parallel to each other with an interval of the gear ratio, and the distance from a base line perpendicular to these lines is shown as the rotation speed of each rotating element. Here, ρ1 in FIG. 3 is the gear ratio Zs / Zrf obtained by the number of teeth Zs of the sun gear S relative to the number of teeth Zrf of the front ring gear Rf, and ρ2 is the gear ratio Zs / Zrr obtained by the number of teeth Zs of the sun gear S relative to the number of teeth Zrr of the rear ring gear Rr, and ρ1 is a value larger than ρ2, and further, ρ1 and ρ2 are values ​​smaller than "1".

[0049] If the rotating elements in the transmission 13 described above were shown on a collinear diagram, as shown in Figures 3(a) and 3(b), they would be arranged in the order of sun gear S, carrier C, rear ring gear Rr, and front ring gear Rf from the left in the diagram, and if the gear ratio between the sun gear S and carrier C is "1," the distance between the carrier C and rear ring gear Rr would be ρ2, and the distance between the carrier C and front ring gear Rf would be ρ1. Note that each of the pinion gears Pf, Pr is arranged to the right of the front ring gear Rf.

[0050] As shown in FIG. 3(a), the rotation speed of the sun gear S (i.e., the rotation speed of the motor 2) when the drive mode (solid line) is set is lower than the rotation speed of the sun gear S when the extra-low mode (dash line) is set. That is, the reduction ratio is smaller when the drive mode is set than when the extra-low mode is set. Therefore, assuming that the torque of the motor 2 is Tm, when the drive mode is set, a torque of ((1+ρ1) / ρ1)Tm is transmitted to the output shaft 24, and when the extra-low mode is set, a torque of ((1+ρ2) / ρ2)Tm is transmitted to the output shaft 24. That is, the transmission 13 is configured to be able to drive and run by switching between two driving modes, high and low, for reduction gears. This extra-low mode corresponds to the "driving mode" in the embodiment of the present invention, and the reduction gear when the extra-low mode is set corresponds to the "second reduction gear" in the embodiment of the present invention. The drive mode corresponds to the "other driving mode" in the embodiment of the present invention, and the reduction gear when the drive mode is set corresponds to the "third reduction gear" in the embodiment of the present invention. When the disconnection mode (broken line) is set, the transmission of torque between the motor 2 and the drive wheels is cut off, so that the motor 2 can be rotated at any rotation speed or stopped.

[0051] Also, when the parking mode (broken line) is set as shown in FIG. 3(b), two or more rotating elements of the transmission 13 are fixed, and each rotating element is stopped. In contrast, in the PTO mode (solid line), only the parking brake is engaged and the carrier C is stopped. When the motor 2 is driven in this state as shown by the solid line in FIG. 3(b), the torque is amplified according to the reduction ratio of the transmission 13 and transmitted to the rear ring gear Rr and the output gear 45. Specifically, when the torque of the motor 2 is Tm, a torque of (1 / ρ2)Tm is transmitted to the rear ring gear Rr and the output gear 45, and the rear ring gear Rr and the output gear 45 rotate in the opposite direction to the motor 2. The reduction gear when the PTO mode is set corresponds to the "first reduction gear" in the embodiment of the present invention.

[0052] As described above, in the PTO mode, the amplification factor of the torque transmitted from the motor 2 to the output gear 45 is determined based on ρ2, which is the gear ratio Zs / Zrr between the sun gear S and the rear ring gear Rr, and the rotation speed ratio between the motor 2 and the output gear 45 is also determined. Similarly, in the extra low mode, the amplification factor of the torque transmitted from the motor 2 to the output shaft 24 is determined based on ρ2, which is the gear ratio Zs / Zrr between the sun gear S and the rear ring gear Rr. Therefore, the gear ratio Zs / Zrr between the sun gear S and the rear ring gear Rr is set depending on the characteristics of the motor 2, the driving force required of the vehicle when the extra low mode is set, and the rotation speed and torque input to the PTO.

[0053] The power transmission device 1 configured as described above can set a mode in which the power of the motor 2 is decelerated and transmitted to the driving wheels by engaging either the front brake Bf or the rear brake Br, and can set a mode in which the power of the motor 2 is decelerated and transmitted to the PTO gear 51 by engaging the parking brake. In other words, it is possible to satisfy the running performance such as the required driving force of the vehicle, and also to satisfy the rotation speed and torque required for the PTO.

[0054] In addition, by switching the reaction element and the output element in the stepped pinion type planetary gear mechanism, i.e., by switching the brake to be engaged, it is possible to switch between a traveling mode and a PTO driving mode. Therefore, it is possible to obtain a large reduction ratio while suppressing an increase in the axial length of the transmission 13, and to improve the mountability of the vehicle.

[0055] Furthermore, as shown in Fig. 3(a), in both the drive mode and the extra-low mode, the rotation speed of each gear (especially the pinion gears Pf and Pr) can be reduced, so that slippage on the tooth surface of each gear can be reduced, power loss can be reduced, and heat generation can be suppressed. In other words, the power required for the motor 2 can be reduced, that is, the amount of power consumption can be reduced.

[0056] 1, any differential mechanism having at least three rotating elements configured to rotate differentially may be used, and more specifically, any differential mechanism having a first rotating element connected to a motor, a second rotating element connected to a drive wheel, and a third rotating element transmitting torque to a PTO, or having the first rotating element, the third rotating element, and the second rotating element, arranged in this order on a collinear diagram showing the relationship between the relative rotational speeds of the three rotating elements. In other words, the differential mechanism is not limited to one capable of setting drive travel modes with two reduction stages, and may be configured to be capable of setting one drive travel mode and a PTO mode.

[0057] Fig. 4 shows a skeleton diagram for explaining one example, and the power transmission device 1 shown in Fig. 4 has a single-pinion planetary gear mechanism that constitutes a transmission 13. That is, the transmission 13 is made up of a sun gear S1, a ring gear R1 that is arranged concentrically with the sun gear S1, a pinion gear P1 that meshes with the sun gear S1 and the ring gear R1, and a carrier C1 that holds the pinion gear P1 so that it can rotate and revolve around its axis.

[0058] A motor 2 is connected to the sun gear S1, an output shaft 24 is connected to the carrier C1, and a PTO gear 51 is connected via an output side rotating member 44 connected to the ring gear R1. Also provided are a brake B1 that selectively prohibits rotation of the ring gear R1, and a parking brake PKB that selectively prohibits rotation of the carrier C1.

[0059] The above-mentioned transmission 13 can function as a reducer that reduces the speed of the power output from the motor 2, which has the sun gear S1 as an input element, the ring gear R1 as a reaction element, and the carrier C1 as an output element, and transmits it to the drive wheels by engaging the brake B1 and releasing the parking brake PKB, and can also function as a reducer that reduces the speed of the power output from the motor 2, which has the sun gear S1 as an input element, the carrier C1 as a reaction element, and the ring gear R1 as an output element, and transmits it to the PTO, by releasing the brake B1 and engaging the parking brake PKB. [Explanation of symbols]

[0060] 1 Power transmission device 2 Motors 13 Gearbox 24 Output shaft 30 Joint axis 32 Fixed axis 41 Cylindrical part 42 Wall 43 Output shaft 44 Output side rotating member 45 Output gear 50 Counter shaft 51 PTO gear B1 Brake Bf front brake Br Rear brake C, C1 Carrier P1,Pf,Pr Pinion gear PKB Parking brake R1, Rf, Rr Ring gear S,S1 Sun gear Sf,Sr Sleeve

Claims

1. A power transmission device configured to be capable of traveling using power output from a motor as a driving power source, and capable of transmitting the power output from the motor to a power take-off device for transmitting the power to a device external to the vehicle, a differential mechanism including at least three rotating elements, namely, a first rotating element connected to the motor, a second rotating element connected to a drive wheel, and a third rotating element, and the three rotating elements are connected to each other so as to be capable of differential rotation; a first brake that inhibits rotation of the second rotating element; a second brake that inhibits rotation of the third rotating element; an output side rotating member that rotates integrally with the third rotating element and is connected to the power take-off device, a PTO mode in which a first reduction gear stage is set so that the rotation speed of the first rotating element is higher than the rotation speed of the third rotating element by outputting torque from the motor in a state in which the first brake prohibits rotation of the second rotating element and the second brake permits rotation of the third rotating element, thereby transmitting torque from the motor to the power take-off device; and a travel mode in which a second reduction gear stage is set so that the rotation speed of the first rotating element is higher than the rotation speed of the second rotating element by outputting torque from the motor in a state in which the second brake prohibits rotation of the third rotating element and the first brake permits rotation of the second rotating element, thereby transmitting torque from the motor to the drive wheels for travel, The differential mechanism further includes a fourth rotating element. a third brake that prohibits rotation of the fourth rotating element; By outputting torque from the motor in a state where the rotation of the fourth rotating element is prohibited by the third brake, another driving mode can be set in which torque is transmitted to the drive wheels to drive the vehicle. A power transmission device characterized by:

2. A power transmission device capable of running on power output from a motor as a driving force source, and configured to transmit the power output from the motor to a power take-off device for transmitting the power to a device external to the vehicle, a differential mechanism including at least three rotating elements, namely, a first rotating element connected to the motor, a second rotating element connected to a drive wheel, and a third rotating element, and the three rotating elements are connected to each other so as to be capable of differential rotation; a first brake that inhibits rotation of the second rotating element; a second brake that inhibits rotation of the third rotating element; an output side rotating member that rotates integrally with the third rotating element and is connected to the power take-off device, a PTO mode in which a first reduction gear stage is set so that the rotation speed of the first rotating element is higher than the rotation speed of the third rotating element by outputting torque from the motor in a state in which the first brake prohibits rotation of the second rotating element and the second brake permits rotation of the third rotating element, thereby transmitting torque from the motor to the power take-off device; and a travel mode in which a second reduction gear stage is set so that the rotation speed of the first rotating element is higher than the rotation speed of the second rotating element by outputting torque from the motor in a state in which the second brake prohibits rotation of the third rotating element and the first brake permits rotation of the second rotating element, thereby transmitting torque from the motor to the drive wheels for travel, the differential mechanism includes a stepped pinion type planetary gear mechanism having a sun gear, two ring gears with different numbers of teeth, and a carrier as rotating elements; the first rotating element includes the sun gear, the second rotating element includes the carrier; The third rotating element includes one of the two ring gears. A power transmission device characterized by:

3. 3. The power transmission device according to claim 2, The differential mechanism further includes a fourth rotating element. a third brake that prohibits rotation of the fourth rotating element; By outputting torque from the motor in a state where the rotation of the fourth rotating element is prohibited by the third brake, another driving mode can be set in which torque is transmitted to the drive wheels to drive the vehicle. A power transmission device characterized by:

4. 4. The power transmission device according to claim 1 or 3, The differential mechanism is configured to set a third reduction stage in which the rotation speed of the first rotating element is higher than the rotation speed of the second rotating element when the fourth rotating element is stopped, and a reduction ratio, which is the rotation speed of the second rotating element relative to the rotation speed of the first rotating element, is smaller than that of the second reduction stage. A power transmission device characterized by:

5. 5. A power transmission device according to claim 1, The differential mechanism is configured to be arranged in the order of the first rotating element, the second rotating element, and the third rotating element, or the order of the first rotating element, the third rotating element, and the second rotating element, on a collinear diagram that indicates a relationship between the relative rotational speeds of the first rotating element, the second rotating element, and the third rotating element. A power transmission device characterized by:

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