Transmission, work vehicle, and control device

Abstract

To provide a transmission device, a work vehicle and a control device capable of smoothly switching a gear through preventing a failure in a gear shift of a sub-transmission device.SOLUTION: A transmission device comprises a main transmission device 20 and a sub-transmission device 21. The transmission device also has: a sub-transmission switch 15 which outputs a sub-transmission switching command; and a sub-transmission operation mechanism 30 which performs switching operation of the sub-transmission device 21. The sub-transmission operation mechanism 30 has: an operation member which transfers switching operation to the sub-transmission device 21; a linkage mechanism 32 which operates the operation member on the basis of the sub-transmission switching command; and a transmission position determination section 6a which determines a transmission position of a shift stage. When determining a failure in switching from a current first shift stage to a targeted second shift stage, the transmission device performs the switching operation to return the shift stage to a retrial shift stage positioned in an inverse direction of the second shift stage and performs the switching operation to the second shift stage once again after causing the main transmission device 20 to drive the sub-transmission device 21.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a transmission that changes the power of a work vehicle, a work vehicle equipped with the transmission, and a control device that controls the transmission.

Background Art

[0002] A work vehicle such as a harvester is configured to transmit the power from an engine to a traveling device such as a pair of crawlers after changing the speed by a transmission. The transmission includes, for example, a main transmission for changing the power in the forward or reverse direction, and a sub-transmission for changing the power shifted by the main transmission in a gear-switching manner.

[0003] For example, the harvester disclosed in Patent Document 1 includes a main transmission, a gear-switching sub-transmission, a manual sub-transmission operation tool for instructing the switching of the transmission state of the sub-transmission, and a transmission operation mechanism for switching the state of the sub-transmission based on the operation of the sub-transmission operation tool. The transmission operation mechanism includes a sub-transmission arm which is an operating member for performing gear shifting in the sub-transmission, and a transmission cylinder which is an actuator for operating the operating member. The sub-transmission switches the transmission state by sliding a shift gear which is spline-fitted to the input shaft in a state of rotating integrally with the input shaft in the axial direction of the input shaft. Further, the harvester includes a main transmission lever as a main transmission operation tool for operating the main transmission, and a sub-transmission switch as a sub-transmission operation tool.

[0004] In the harvester of Patent Document 1, when the sub-transmission switch is turned on but the switching cannot be confirmed, it is considered that the shift gear is not properly engaged and is bounced back, so an abnormal process is executed. In the abnormal process, the transmission cylinder is operated so that the sub-transmission arm moves to the original position, and the transmission state in which the shift gear was engaged before the transmission operation is restored.

Prior Art Documents

Patent Documents

[0006] In conventional technology, such as the harvesting machine described in Patent Document 1, when the auxiliary transmission's gear shift is performed using the auxiliary transmission switch, if the shift gear does not mesh properly and the shift fails, the shift gear returns to its previous position, meaning that the auxiliary transmission's gear shift was not performed. Therefore, the operator has to re-operate the auxiliary transmission switch, which places a burden on the operator. Furthermore, even if the auxiliary transmission switch is re-operated, the mechanism of the auxiliary transmission remains in its original state, so there is a problem in that the likelihood of the shift gear meshing properly is low.

[0007] The present invention aims to provide a transmission, a work vehicle, and a control device that suppress gear shift failures in the auxiliary transmission and enable smooth gear switching. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a transmission comprising: a main transmission for changing the speed of power in the forward or reverse direction; and a sub-transmission for changing the speed of power changed by the main transmission in a gear-switching manner, wherein the transmission comprises: a sub-transmission command unit that outputs a gear-switching command for the sub-transmission; and a sub-transmission operation mechanism that performs a gear-switching operation of the sub-transmission based on the gear-switching command from the sub-transmission command unit, wherein the sub-transmission operation mechanism includes: an operating member that transmits the gear-switching operation to the sub-transmission; a linkage mechanism that operates the operating member based on the gear-switching command; and the gear-switching operation based on the operating state of at least one of the operating member and the linkage mechanism. The transmission comprises a gear position determination unit that determines the gear position, and when the sub-transmission operating mechanism performs a gear position switching operation based on the gear switching command that switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, if the gear position determination unit determines that the switch to the second gear has failed based on the result of determining the gear position, as a corrective action, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the sub-transmission is driven by the main transmission, the sub-transmission is switched back to the second gear.

[0009] To solve the above problems, the work vehicle of the present invention is equipped with the above-described transmission device.

[0010] To solve the above problems, the present invention provides a transmission comprising: a main transmission for shifting power in the forward or reverse direction; and a sub-transmission for shifting the power shifted by the main transmission in a gear-switching manner, wherein the transmission comprises: a sub-transmission command unit that outputs a shift switching command for the sub-transmission; and a sub-transmission operation mechanism that performs a shift switching operation of the sub-transmission based on the shift switching command from the sub-transmission command unit, wherein the sub-transmission operation mechanism comprises: an operating member that transmits the shift switching operation to the sub-transmission; a linkage mechanism that operates the operating member based on the shift switching command; and a shift position determination unit that determines the shift position of the shift position based on the operating state of at least one of the operating member and the linkage mechanism, wherein the sub-transmission is shifted in a predetermined shift direction In the case where the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command to switch from the current first gear to the target second gear, if the gear shift position determination unit determines that the switch to the second gear has failed based on the gear shift position determination result, the corrective action is as follows: In manual driving, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear; on the other hand, in automatic driving, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, the sub-transmission is switched back to the second gear.

[0011] To solve the above problems, the present invention provides a control device for controlling a transmission comprising a main transmission for changing the speed of power in the forward or reverse direction, and a sub-transmission for changing the speed of power changed by the main transmission in a gear-switching manner, wherein the control device includes a sub-transmission command unit that outputs a gear shifting command for the sub-transmission to a sub-transmission operating mechanism that performs a gear shifting operation of the sub-transmission, the sub-transmission operating mechanism includes an operating member that transmits the gear shifting operation to the sub-transmission, a linkage mechanism that operates the operating member based on the gear shifting command, and a gear shift that determines the gear shift position based on the operating state of at least one of the operating member and the linkage mechanism The system comprises a position determination unit, and when the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, if the gear shift position determination unit determines that the switch to the second gear has failed based on the gear shift position determination result, the system performs a remedial operation to return the sub-transmission to a retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, it controls the sub-transmission to perform the switch to the second gear again. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a transmission, a work vehicle, and a control device that suppress failures in gear shifting of the auxiliary transmission and enable smooth gear switching. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing a work vehicle according to an embodiment of the present invention. [Figure 2] This is a perspective view showing a transmission for a work vehicle according to an embodiment of the present invention. [Figure 3] This is a power transmission system diagram showing a work vehicle according to an embodiment of the present invention. [Figure 4]It is a plan view showing a sub-speed switch of a work vehicle according to an embodiment of the present invention. [Figure 5] It is a perspective view showing a sub-speed operation mechanism of a work vehicle according to an embodiment of the present invention. [Figure 6] It is a side sectional view showing a second link member of a sub-speed operation mechanism of a work vehicle according to an embodiment of the present invention. [Figure 7] It is a side view showing a part of a first link member of a sub-speed operation mechanism of a work vehicle according to an embodiment of the present invention. [Figure 8] It is a block diagram showing a control equipment of a work vehicle according to an embodiment of the present invention and its periphery. [Figure 9] In a work vehicle according to an embodiment of the present invention, it is a graph showing the correlation between the motor position of a sub-speed operation mechanism and the arm position of a sub-speed device. [Figure 10] In a work vehicle according to an embodiment of the present invention, it is a flowchart showing an operation example of performing a switching operation of a sub-speed device in the case of a manual mode. [Figure 11] In a work vehicle according to an embodiment of the present invention, it is a flowchart showing an operation example of performing a switching operation of a sub-speed device in the case of an automatic mode.

MODE FOR CARRYING OUT THE INVENTION

[0014] As an embodiment of the present invention, the work vehicle 1 will be described with reference to the drawings. FIG. 1 is a perspective view showing the work vehicle 1 of the present embodiment.

[0015] The work vehicle 1 is a vehicle that can perform work while traveling in a field, such as a harvester, a tractor, a transplanter, a combine, etc. In the present embodiment, an example of the work vehicle 1 that functions as a harvester such as a combine for harvesting crops or a vegetable harvester will be described. The work vehicle 1 is provided with a traveling unit 3, a control unit 4, a power unit 5, and a control device 6 (see FIG. 8) with respect to a traveling body 2, and a harvesting unit (not shown) for harvesting crops is detachably provided with respect to the work vehicle 1.

[0016] The work vehicle 1 is configured to be capable of traveling while performing operations such as harvesting by a work unit such as a harvesting unit. The work vehicle 1 is configured to travel in either a manual mode or an automatic mode. In the manual mode, the traveling unit 3 is operated and travels according to the operation of the control unit 4 by the operator. On the other hand, in the automatic mode, it is controlled by the control device 6 according to a pre-stored program, and the traveling unit 3 is operated and travels.

[0017] The traveling unit 3 is disposed below the traveling body 2 and supports the traveling body 2. The traveling unit 3 includes a pair of left and right crawlers 10 and a transmission 11 (transmission device). The pair of crawlers 10 receives power from the power unit 5 and is driven to perform traveling and the like of the work vehicle 1. The transmission 11 transmits the power from the power unit 5 to the pair of crawlers  10.

[0018] As shown in FIGS. 2 and 3, the transmission 11 includes a main transmission device 20 for shifting the power from the power unit 5 in the forward or reverse direction, and a sub-transmission device 21 for shifting the power from the main transmission device 20 to any one of a plurality of speed stages. In other words, the sub-transmission device 21 shifts the rotational speed of the pair of crawlers  10 to any one of a plurality of speed stages. In the present embodiment, the transmission device composed of the transmission 11 may include, in addition to the main transmission device 20 and the sub-transmission device 21, a control device 6, a main transmission lever 14 and a sub-transmission switch 15 of the control unit 4, and a sub-transmission operation mechanism 30. The details of the transmission 11 will be described later.

[0019] The control unit 4 is located on the front right side of the vehicle body 2. The control unit 4 is equipped with controls for controlling the movement of the work vehicle 1 around the driver's seat 12, which is the seat where the operator sits. The control unit 4 includes controls such as a steering wheel 13, which is a steering control device for instructing the turning of the work vehicle 1, and a main gear lever 14 (main gear control unit) and a sub-gear switch 15 (sub-gear control unit), which are gear shifting devices for instructing changes in the forward and reverse speed of the work vehicle 1. In other words, the work vehicle 1 moves by operating the vehicle body 3 in response to the operation of the steering wheel 13, the main gear lever 14, and the sub-gear switch 15. The control unit 4 may also be equipped with a mechanism for operating harvesting operations by the harvesting unit, and a display unit (not shown) such as a monitor for displaying and outputting various information to the operator.

[0020] The main gear lever 14 outputs a main gear switching command in response to the operator's operation and transmits it to the main transmission 20 of the transmission 11. The sub-gear switch 15 is an electrical switching device that outputs a sub-gear switching command (gear switching command) in response to the operator's operation and transmits it to the sub-gear 21 of the transmission 11. The sub-gear switch 15 accepts a switching operation to switch the power output from the main transmission 20 (the rotational speed of the pair of crawlers 10) to one of several gears such as high speed (travel), medium speed (standard), neutral, and low speed. As shown in Figure 4, the sub-gear switch 15 has a high-speed button 15a, a medium-speed button 15b, a neutral button 15c, and a low-speed button 15d, and outputs a sub-gear switching command indicating high-speed switching, medium-speed switching, neutral switching, or low-speed switching in response to the respective operation. Furthermore, the high-speed button 15a, medium-speed button 15b, neutral button 15c, and low-speed button 15d output sub-speed switching commands in response to the pressing operation, and are equipped with LED lamps or the like that should light up when the speed is shifted to high, medium, neutral, or low.

[0021] The power unit 5 is located below the control unit 4 and is mounted on the vehicle body 2. The power unit 5 is equipped with an engine 16, which is the power source, and transmits the power generated by the engine 16 to the transmission 11 of the vehicle body 3.

[0022] Next, the transmission 11 will be described. In the transmission 11, the main transmission 20 changes the power from the engine 16 in the forward or reverse direction, and is composed of a continuously variable transmission that continuously changes the rotational speed of the power in the forward or reverse direction.

[0023] The main transmission 20 is, for example, a hydrostatic continuously variable transmission equipped with a hydraulic pump and a hydraulic motor, and has an input shaft that rotates upon receiving power transmitted from the engine 16, and transmits power to the pump shaft of the hydraulic pump via the input shaft. The main transmission 20 supplies hydraulic fluid from the hydraulic pump to the hydraulic motor by the power transmitted to the pump shaft. The hydraulic motor has a motor shaft that outputs rotational power in accordance with the hydraulic fluid.

[0024] The main transmission 20 controls the opening and closing of the solenoid valve 20a on the hydraulic pump according to the amount of operation of the main transmission lever 14, thereby changing the discharge direction and amount of hydraulic fluid from the hydraulic pump to the hydraulic motor, and adjusting the rotation direction and rotation speed of the motor shaft of the hydraulic motor. The main transmission 20 can also adjust the rotation direction and rotation speed of the motor shaft of the hydraulic motor by controlling the opening and closing of the solenoid valve 20a on the hydraulic pump, which is controlled by the control device 6. The main transmission 20 transmits the rotational power of the motor shaft of the hydraulic motor to the auxiliary transmission input shaft 24 of the auxiliary transmission 21 via the transmission gear 23.

[0025] The auxiliary transmission 21 changes the power from the main transmission 20 to one of several gears via the auxiliary transmission input shaft 24. In other words, it changes the rotational speed of the pair of crawlers 10 to one of several gears. The auxiliary transmission 21 is composed of a gear-switching type transmission and has several auxiliary gears such as a high-speed gear 26, a medium-speed gear 27, and a low-speed gear 28, which are switched by an auxiliary transmission shifter 25, and also has an auxiliary transmission output shaft 29 that outputs rotational power. In the auxiliary transmission 21, the direction of gear shifting for the multiple gears is high speed, medium speed, neutral, and low speed in that order, with the direction from the low-speed side to the high-speed side being the acceleration direction and the direction from the high-speed side to the low-speed side being the deceleration direction.

[0026] For example, the sub-transmission shifter 25 slides against the high-speed gear 26, medium-speed gear 27, and low-speed gear 28, thereby switching the connection between the sub-transmission input shaft 24 and the sub-transmission output shaft 29 via the high-speed gear 26, medium-speed gear 27, or low-speed gear 28. When the sub-transmission 21 shifts to high speed, medium speed, or low speed, the sub-transmission gear switching is successful if the sub-transmission shifter 25 is engaged with the high-speed gear 26, medium-speed gear 27, or low-speed gear 28. On the other hand, the sub-transmission gear switching fails if the sub-transmission shifter 25 is not engaged with the high-speed gear 26, medium-speed gear 27, or low-speed gear 28. When the sub-transmission 21 shifts to neutral, the sub-transmission shifter 25 is not engaged with any of the high-speed gear 26, medium-speed gear 27, or low-speed gear 28, but the sub-transmission gear switching is not a failure and is considered a success.

[0027] The auxiliary transmission 21 controls the auxiliary transmission shifter 25 in response to the operation of the auxiliary transmission switch 15, thereby switching the output rotational speed of the auxiliary transmission output shaft 29 to one of several gears: high speed (travel), medium speed (standard), neutral, or low speed. The work vehicle 1 is equipped with an auxiliary transmission operating mechanism 30 that performs gear switching operations on the auxiliary transmission 21 based on an auxiliary transmission switching command from the auxiliary transmission switch 15.

[0028] The sub-transmission operating mechanism 30 connects the sub-transmission input shaft 24 to the sub-transmission output shaft 29 via the high-speed gear 26 in response to a high-speed sub-transmission switching command from the sub-transmission switch 15, connects the medium-speed gear 27 to the sub-transmission output shaft 29 in response to a medium-speed sub-transmission switching command from the sub-transmission switch 15, disconnects the sub-transmission gear from the sub-transmission input shaft 24 and the sub-transmission gear from the sub-transmission output shaft 29 in response to a neutral sub-transmission switching command from the sub-transmission switch 15, and connects the low-speed gear 28 to the sub-transmission output shaft 29 in response to a low-speed sub-transmission switching command from the sub-transmission switch 15. As a result, the sub-transmission device 21 transmits the rotational power transmitted from the motor shaft of the hydraulic motor of the main transmission device 20 to the sub-transmission output shaft 29 via the high-speed gear 26, medium-speed gear 27, or low-speed gear 28. Further details of the sub-transmission operating mechanism 30 will be described later.

[0029] The power shifted by the auxiliary transmission 21 is output via the auxiliary transmission output shaft 29 and transmitted to the left and right axles 17 via various gears and rotating shafts. Further, it is transmitted to the left and right drive sprockets provided on the axles 17, and each drive sprocket drives the left and right crawlers 10 to move the work vehicle 1.

[0030] As shown in Figure 5, the sub-transmission operating mechanism 30 comprises an operating drive unit 31, a linkage mechanism 32, an operating member 33, and an operating position detection unit 34. The operating drive unit 31 operates the linkage mechanism 32 based on a sub-transmission switching command from the sub-transmission switch 15. The operating drive unit 31 can also operate the linkage mechanism 32 under control of a sub-transmission switching command from the control device 6.

[0031] For example, the operating drive unit 31 is composed of a sub-transmission drive motor that rotates the drive output shaft 40 based on a sub-transmission speed switching command, and a drive arm 41 is rotatably attached to the drive output shaft 40. The operating drive unit 31 rotates the drive output shaft 40 to one of several drive positions, such as high-speed drive position, medium-speed drive position, neutral drive position, and low-speed drive position, in order to rotate the drive output shaft 40 to switch the sub-transmission 21 to one of several gear stages, such as high-speed, medium-speed, neutral, and low-speed. The operating drive unit 31 is equipped with a drive position detection unit 35 that detects the rotation angle and rotation position of the sub-transmission drive motor, and detects the motor position of the sub-transmission drive motor (i.e., the drive position of the drive output shaft 40) based on the detection result.

[0032] The linkage mechanism 32 is configured to operate the operating member 33 based on a sub-speed change command, and for example, converts the oscillating motion of the drive arm 41 into vertical motion and transmits it to the operating member 33. The linkage mechanism 32 includes, for example, a first link member 43 connected to the drive arm 41 and performing vertical motion in accordance with the oscillating motion of the drive arm 41, a connecting member 44 provided near the midpoint between the drive arm 41 and the operating member 33 and performing oscillating motion in accordance with the vertical motion of the first link member 43, and a second link member 45 connected to the connecting member 44 and performing vertical motion in accordance with the oscillating motion of the connecting member 44. One end of the connecting member 44 is connected to the first link member 43, the other end of the connecting member 44 is connected to the second link member 45, and furthermore, the central part of the connecting member 44 is pivotally supported by a rotating support shaft 44a provided on the linkage mechanism 32. The connecting member 44 swings around the pivot shaft 44a, thereby transmitting the motion of the first link member 43 to the second link member 45. The linkage mechanism 32 causes the operating member 33 to swing in response to the up-and-down movement of the second link member 45, as the second link member 45 acts on the operating member 33. For example, when the drive arm 41 swings downward, the linkage mechanism 32 causes the operating member 33 to swing upward, and when the drive arm 41 swings upward, it causes the operating member 33 to swing downward.

[0033] As shown in Figure 6, the second link member 45 has a link spring 46 that expands and contracts in its extension direction at an intermediate position. When the sub-transmission 21 switches the sub-transmission gear, the linkage mechanism 32 applies a predetermined swinging force to the operating member 33. The link spring 46 has greater rigidity than the force required on the operating member 33 for the sub-transmission 21 to switch gears when the sub-transmission 21 successfully switches gears. Also, the link spring 46 has less rigidity than the force that the operating member 33 receives from the sub-transmission 21 when the sub-transmission 21 fails to switch gears. As a result, when the second link member 45 moves downward to switch gears, if the gear change is smooth, the link spring 46 does not compress and swings the operating member 33 downward. Similarly, when the second link member 45 moves upward to switch gears, if the gear change is smooth, the link spring 46 does not compress and swings the operating member 33 upward. On the other hand, if the operating member 33 cannot swing due to a switching failure of the sub-transmission 21 despite the vertical movement of the second link member 45, the link spring 46 expands and contracts to prevent damage or deformation of the linkage mechanism 32.

[0034] The first link member 43 is attached to the drive arm 41 by fastening members 47, such as bolts, which are rotatably inserted between the tip of the drive arm 41 and the upper end of the first link member 43, and is rotatable relative to the drive arm 41. Alternatively, as shown in Figures 7(a) and 7(b), the first link member 43 may have an elongated hole 48 at its upper end, which is longer in its extension direction, so that the fastening members 47 can be slidably inserted into the elongated hole 48.

[0035] Here, when the operating drive unit 31 swings the drive arm 41 attached to the drive output shaft 40 downward in order to rotate the drive output shaft 40 to a predetermined drive position, the fastening member 47 presses downward against the lower side of the inner circumferential surface of the elongated hole 48, as shown in Figure 7(b), thereby moving the first link member 43 downward. When the drive output shaft 40 reaches the drive position, the operating drive unit 31 reverses the sub-transmission drive motor to reverse the drive output shaft 40 and the drive arm 41, so that the fastening member 47 moves upward away from the lower side of the inner circumferential surface of the elongated hole 48 and is positioned in the middle of the elongated hole 48, as shown in Figure 7(a). Also, when the operating drive unit 31 swings the drive arm 41 attached to the drive output shaft 40 upward in order to rotate the drive output shaft 40 to a predetermined drive position, the fastening member 47 presses upward against the upper side of the inner circumferential surface of the elongated hole 48, thereby moving the first link member 43 upward. Then, when the drive output shaft 40 reaches the drive position, the operating drive unit 31 reverses the sub-transmission drive motor, thereby reversing the drive output shaft 40 and the drive arm 41, and moves the fastening member 47 so that it is positioned in the middle of the elongated hole 48, separated downward from the upper side of the inner circumferential surface of the elongated hole 48. In other words, the operating drive unit 31 rotates the drive output shaft 40 until it is slightly beyond the drive position by a predetermined amount of play, and then reverses the drive output shaft 40 to the drive position.

[0036] The operating member 33 transmits the gear shifting operation to the sub-transmission 21. The operating member 33 is composed of an operating arm that swings between multiple operating positions, such as a high-speed (driving) operating position, a medium-speed (standard) operating position, a neutral operating position, and a low-speed operating position, and is switched to one of the operating positions by the linkage mechanism 32. The operating member 33 operates the sub-transmission shifter 25 according to the operating position of the operating member 33, switching the sub-transmission gear connected to the sub-transmission input shaft 24 or sub-transmission output shaft 29 of the sub-transmission 21.

[0037] For example, when the operating member 33 is switched to the high-speed operating position, the sub-transmission shifter 25 connects the high-speed gear 26 to the sub-transmission input shaft 24; when the operating member 33 is switched to the medium-speed operating position, the sub-transmission shifter 25 connects the medium-speed gear 27 to the sub-transmission output shaft 29; when the operating member 33 is switched to the neutral operating position, the sub-transmission shifter 25 disconnects the sub-transmission gear from the sub-transmission output shaft 29; and when the operating member 33 is switched to the low-speed operating position, the sub-transmission shifter 25 connects the low-speed gear 28 to the sub-transmission output shaft 29. The sub-transmission operating mechanism 30 is equipped with an operating position detection unit 34, such as an angle sensor, which detects the rotation angle of the operating member 33, and detects the arm position of the operating member 33 (i.e., the operating position of the operating member 33) based on the detection result.

[0038] The control device 6 controls various components and functions of the work vehicle 1 (particularly the auxiliary transmission 21 and the auxiliary transmission operating mechanism 30), and is composed of a computer such as a CPU. As shown in Figure 8, the control device 6 is connected to a storage unit 7, which is composed of a storage medium such as ROM or RAM. The storage unit 7 stores programs and data for controlling various components and functions, and the control device 6 controls the various components and functions by executing calculations based on the programs and data stored in the storage unit 7. The control device 6 operates as a gear shift position determination unit 6a by executing the programs stored in the storage unit 7.

[0039] The gear shift position determination unit 6a determines the gear shift position of the sub-transmission 21 based on the operating state of the operating member 33. The gear shift position determination unit 6a is composed of, for example, a program executed by the control device 6.

[0040] For example, since the operating position of the operating member 33 corresponds to the shift position of the sub-transmission 21, the shift position determination unit 6a determines the shift position of the sub-transmission 21 as the operating state of the operating member 33 based on the detection result of the operating position detection unit 34. Alternatively, since the drive position of the drive output shaft 40 of the operating drive unit 31 corresponds to the operating position of the sub-transmission switch 15, the shift position determination unit 6a may determine the shift operation position of the operating drive unit 31 as the operating state of the linkage mechanism 32 based on the detection result of the drive position detection unit 35.

[0041] Alternatively, since the operation of the linkage mechanism 32 corresponds to the shifting of the sub-transmission 21, the shift position determination unit 6a may determine the shift position of the sub-transmission 21 based on the detection result of the operating state of the linkage mechanism 32. In addition, the shift position determination unit 6a may determine the shift position of the sub-transmission 21 by combining the operating position of the operating member 33 and the operating state of the linkage mechanism 32.

[0042] Furthermore, the control device 6 is connected to the running section 3, the control section 4, and the power section 5 of the work vehicle 1. For example, the control device 6 is connected to the controls of the control section 4, such as the steering wheel 13, the main gear lever 14, and the sub-gear switch 15, and controls the running section 3 and the power section 5 by inputting the amount of operation of each control device. In particular, the control device 6 is connected to the solenoid valve 20a of the main gearbox 20 in the transmission 11 of the power section 5, and controls the drive of the main gearbox 20 by controlling the solenoid valve 20a. In addition, the control device 6 is connected to the operating drive section 31 of the sub-gear operating mechanism 30 that operates the sub-gearbox 21, and controls the sub-gearbox 21 to shift gears in response to a sub-gearbox switching command.

[0043] When the sub-transmission switch 15 is operated and a sub-transmission switching command indicating high-speed switching, medium-speed switching, neutral switching, or low-speed switching is output, the control device 6 controls the operation drive unit 31 to operate the sub-transmission drive motor so that the drive output shaft 40 of the operation drive unit 31 rotates to the drive position corresponding to the target gear indicated by the sub-transmission switching command. At this time, the control device 6 may accept the sub-transmission switching command if the vehicle speed of the work vehicle 1 operated by the travel unit 3 is near 0, but may not accept the sub-transmission switching command if the vehicle speed is not near 0.

[0044] The control device 6 stores the gear position of the auxiliary transmission 21 in the storage unit 7. For example, the control device 6 stores the neutral position as the initial state of the gear position of the auxiliary transmission 21. Furthermore, when the gear position determination unit 6a determines that the gear position of the auxiliary transmission 21 has changed, the control device 6 updates and stores the gear position of the auxiliary transmission 21 to the changed position. In other words, the control device 6 stores the gear position in which the auxiliary transmission 21 has successfully switched between the auxiliary transmission gears (high-speed gear 26, medium-speed gear 27, or low-speed gear 28).

[0045] However, even when the operating drive unit 31 is driven, the meshing between the sub-transmission shifter 25 and the sub-transmission gears such as the high-speed gear 26, medium-speed gear 27, or low-speed gear 28 may be poor, and the sub-transmission shifter 25 may not be able to move to the normal meshing position with the sub-transmission gear and may stop in a jammed position, that is, the sub-transmission device 21 may become jammed and the shifting may fail.

[0046] In response, the control device 6 can recognize the current gear position (first gear) by determining the gear position of the sub-transmission 21 using the gear position determination unit 6a. Furthermore, when the sub-transmission switch 15 is operated and a sub-transmission switching command indicating high-speed switching, medium-speed switching, neutral switching, or low-speed switching is output, the control device 6 can recognize the target gear position (second gear) based on the sub-transmission switching command. Moreover, after driving the operation drive unit 31 in response to the sub-transmission switching command from the sub-transmission switch 15, the control device 6 can determine whether the sub-transmission 21 has successfully switched to the target gear position or failed by comparing the current gear position determined by the gear position determination unit 6a with the target gear position indicated by the sub-transmission switching command.

[0047] Alternatively, the control device 6 can determine whether the sub-transmission 21 is jammed based on the correlation between the motor position of the sub-transmission drive motor of the operating drive unit 31 detected by the drive position detection unit 35 (i.e., the drive position of the drive output shaft 40) and the arm position of the operating member 33 detected by the operating position detection unit 34 (i.e., the operating position of the operating member 33). Figure 9 shows a correlation diagram between the drive position of the drive output shaft 40 and the operating position of the operating member 33. This correlation diagram is a graph with the drive position of the drive output shaft 40 on the vertical axis and the operating position of the operating member 33 on the horizontal axis. In this correlation diagram, if the coordinates indicated by the detected drive position and operating position are within the jammed determination area, it is determined that the sub-transmission 21 is jammed. If the coordinates indicated by the detected drive position and operating position are within the error determination area, it is determined that the shifting of the sub-transmission 21 is an error.

[0048] If the control device 6 determines that the sub-transmission 21 has failed to switch to the target gear, it controls a corrective operation to resolve the failure of the sub-transmission 21. For example, if the control device 6 starts driving the operating drive unit 31 in response to a sub-transmission switching command, and the current gear has not reached the target gear, i.e., the sub-transmission shifter 25 has stopped in the jammed position for a predetermined error time (e.g., 0.6 seconds) or longer, it determines that the switching has failed and performs a corrective operation. The control device 6 continues to drive the operating drive unit 31 until a predetermined shift completion time (e.g., 0.7 seconds) or longer has elapsed since the current gear reached the target gear, and once the shift completion time has elapsed, it determines that the switching was successful and terminates the operation of the operating drive unit 31.

[0049] As an action to resolve a switching failure of the sub-transmission 21, the control device 6 controls the sub-transmission operating mechanism 30 to perform a switching operation on the sub-transmission 21 to return to the gear position one position before the target gear position, which is used as a gear position for retrying. Here, the gear position one position before the target gear position is the gear position located in the opposite direction to the target gear position when switching from the current gear position to the target gear position fails in a predetermined gear direction. The control device 6 should perform the switching operation to return to the gear position one position before the target gear position after determining that the switching failure of the sub-transmission 21 has occurred and a predetermined stop time (for example, 0.1 seconds) has elapsed.

[0050] For example, if the target gear is set to low speed and the system fails to switch from high speed to low speed in the deceleration direction, the control device 6 controls the sub-transmission operating mechanism 30 to return to neutral, which is one gear before low speed in the deceleration direction. Also, if the target gear is set to neutral and the system fails to switch from high speed to neutral in the deceleration direction, the control device 6 controls the sub-transmission operating mechanism 30 to return to medium speed, which is one gear before neutral in the deceleration direction.

[0051] When the work vehicle 1 is being driven manually in manual mode and a resolution operation is performed, the control device 6 returns to the gear position one position before the target gear position (the gear position for retrying) and ends the resolution operation. The control device 6 should also notify the operator that a switching failure has occurred in the auxiliary transmission 21 (auxiliary transmission error) and that the switching of the auxiliary transmission 21 needs to be redone by lighting a lamp, displaying on the screen, or outputting an audible signal. At this time, before redoing the switching of the auxiliary transmission 21, it is advisable to operate the main transmission lever 14 to drive the main transmission 20, thereby changing the meshing of the auxiliary transmission shifter 25 and auxiliary transmission gears (high-speed gear 26, medium-speed gear 27, or low-speed gear 28) of the auxiliary transmission 21. When the main transmission 20 is driven, the auxiliary transmission 21 will slip if the gear position for retrying is neutral, but will move the work vehicle 1 forward or backward if the gear position for retrying is anything other than neutral.

[0052] On the other hand, when the work vehicle 1 is driving automatically in automatic mode and a resolution operation is performed, the control device 6 controls the sub-transmission operating mechanism 30 to return to the gear position one step before the target gear position (the gear position for retrying), and then perform a retry operation to the target gear position. As a retry operation, the control device 6 controls the main transmission 20 to automatically drive the sub-transmission 21, and further controls the sub-transmission operating mechanism 30 to perform a switching operation to switch to the target gear position on the sub-transmission 21 again.

[0053] After performing a retry, the control device 6 determines, in the same manner as described above, whether the sub-transmission 21 successfully switched to the target gear or failed to switch. If the retry operation results in a switching failure, the control device 6 can repeat the retry operation. If the control device 6 is unable to obtain a successful switch of the sub-transmission 21 and the number of switching failures exceeds a predetermined threshold (for example, 5 times), it controls the driving unit 3 to stop the automatic driving of the work vehicle 1, and also notifies the operator of the switching failure of the sub-transmission 21 (sub-transmission error) by lighting a lamp, displaying on the screen, or outputting an audible signal.

[0054] When the control device 6 automatically drives the main transmission 20 during a retry operation, it controls the solenoid valve 20a of the main transmission 20 to rotate the main transmission 20 (motor shaft of the hydraulic motor) by a small amount, and transmits that power to the auxiliary transmission 21 via the transmission gear 23, causing the auxiliary transmission 21 (auxiliary transmission input shaft 24) to rotate by a small amount. The small rotation in the main transmission 20 and auxiliary transmission 21 is simply the rotational angle required for the engagement of the auxiliary transmission shifter 25 and the auxiliary transmission gear (high-speed gear 26, medium-speed gear 27, or low-speed gear 28) of the auxiliary transmission 21, and may be as small as several tens of degrees.

[0055] Next, an example of the operation to switch the auxiliary transmission 21 when the work vehicle 1 is in manual mode will be explained with reference to the flowchart in Figure 10.

[0056] First, the operator operates the sub-transmission switch 15 to switch the sub-transmission 21 to a predetermined gear (step S1).

[0057] Furthermore, if the vehicle speed of the work vehicle 1 is not near 0 (Step S2: No), the control device 6 will not accept the sub-transmission switching command and will terminate its operation.

[0058] On the other hand, if the vehicle speed of the work vehicle 1 is near 0 (Step S2: Yes), the control device 6 receives a sub-transmission switching command and drives the operating drive unit 31 (sub-transmission drive motor) of the sub-transmission operating mechanism 30 according to the sub-transmission switching command corresponding to the operation of the sub-transmission switch 15 (Step S3). The sub-transmission operating mechanism 30 operates the linkage mechanism 32 in response to the drive of the operating drive unit 31 and operates the sub-transmission device 21 by the operating member 33 so that it reaches the target gear indicated by the predetermined sub-transmission switching command.

[0059] The control device 6 determines the current gear position of the sub-transmission 21 based on the determination result of the gear position determination unit 6a. If it has not been a predetermined time since reaching the target gear position (step S4: No, step S5: No), it continues to drive the operating drive unit 31 (step S6). On the other hand, if it has been a predetermined time since reaching the target gear position (step S4: No, step S5: Yes), the control device 6 determines that the sub-transmission gear has been successfully switched, stops driving the operating drive unit 31, stores the current gear position as the gear position of the sub-transmission 21 in the storage unit 7, and terminates the operation.

[0060] On the other hand, if the current gear of the sub-transmission 21 has not reached the target gear, and the jammed state of the sub-transmission 21 continues for a predetermined error time or longer after the operation of the operating drive unit 31 has started (Step S4: Yes), the control device 6 determines that the switching has failed and stops the operation of the operating drive unit 31 for a predetermined stop time or longer (Step S7). Furthermore, as a resolution operation, the control device 6 controls the sub-transmission operating mechanism 30 to return the sub-transmission 21 to the gear one gear before the target gear (the gear for retry) (Step S8), and terminates the operation.

[0061] Next, an example of the operation to switch the auxiliary transmission 21 when the work vehicle 1 is in automatic mode will be explained with reference to the flowchart in Figure 11.

[0062] In this example of operation, the operation up to driving the operating drive unit 31 of the sub-transmission operating mechanism 30 (steps S11 to S13) is the same as the operation in manual mode (steps S1 to S3), so the explanation is omitted. Also, in this example of operation, the operation up to successfully switching the sub-transmission gear (steps S14: No, S15: No, S16, S15: Yes) is the same as the operation in manual mode (steps S4: No, S5: No, S6, S5: Yes), so the explanation is omitted.

[0063] If the current gear of the sub-transmission 21 has not reached the target gear, and the jammed state of the sub-transmission 21 continues for a predetermined error time or longer after the operation drive unit 31 has started to drive (Step S14: Yes), the control device 6 determines that the switching has failed and stops the operation drive unit 31 for a predetermined stop time or longer (Step S17).

[0064] Here, if the number of switching failures of the auxiliary transmission 21 is less than a predetermined threshold (step S18: No), the control device 6 first controls the auxiliary transmission operating mechanism 30 to return the auxiliary transmission 21 to the gear position one step before the target gear position (the gear position for retrying) as a corrective action (step S19). Furthermore, the control device 6 rotates the main transmission 20 slightly to rotate the auxiliary transmission 21 slightly and drive the work vehicle 1 slightly (step S20), and then stops the main transmission 20 and stops the auxiliary transmission 21 (step S21). The control device 6 then moves to step S13 and drives the operating drive unit 31 of the auxiliary transmission operating mechanism 30 in order to perform a retry operation to the target gear position.

[0065] On the other hand, if the number of switching failures of the sub-transmission 21 exceeds a predetermined threshold (step S18: Yes), the control device 6 notifies the sub-transmission error (step S22) and terminates its operation.

[0066] As described above, according to this embodiment, the transmission 11 of the work vehicle 1 is a transmission that includes a main transmission 20 for changing the power in the forward or reverse direction, and a sub-transmission 21 for changing the power changed by the main transmission 20 in a gear-switching manner. This transmission includes a sub-transmission switch 15, which is a sub-transmission command unit that outputs a sub-transmission switching command for the sub-transmission 21, and a sub-transmission operating mechanism 30 that performs a gear shift switching operation of the sub-transmission 21 based on the sub-transmission switching command from the sub-transmission switch 15. The sub-transmission operating mechanism 30 includes an operating member 33 that transmits a gear shift switching operation to the sub-transmission 21, a linkage mechanism 32 that operates the operating member 33 based on the sub-transmission switching command, and a gear shift position determination unit 6a that determines the gear shift position based on the operating state of the operating member 33. Then, for example, when the sub-transmission operating mechanism 30 performs a gear shift operation based on a sub-transmission switching command from the control device 6 to switch the sub-transmission 21 from the current first gear to the target second gear in a predetermined gear shift direction, if the gear position determination unit 6a determines that the switch to the second gear has failed based on the gear position determination result, as a corrective action, the sub-transmission 21 is switched back to a retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission 20 drives the sub-transmission 21, the sub-transmission 21 is switched to the second gear again.

[0067] When shifting gears using the auxiliary transmission 21 of the transmission 11 of the work vehicle 1 via the linkage mechanism 32, the auxiliary transmission gear of the auxiliary transmission 21 may not mesh properly, resulting in a shift failure. In contrast, in the present invention, after returning the auxiliary transmission gear to a gear for retry, the auxiliary transmission 21 is driven by the main transmission 20, and then the retry operation to the target gear is performed. As a result, the meshing of the auxiliary transmission gear is shifted before the shift operation is performed again, making it easier for the auxiliary transmission gear to mesh and thus avoiding shift failures.

[0068] Furthermore, according to this embodiment, the main transmission 20 is composed of a continuously variable transmission, and in the disengagement operation, the sub-transmission 21 is driven to rotate by the drive of the continuously variable transmission.

[0069] As a result, the operation of the work vehicle 1 that resolves the switching failure of the auxiliary transmission 21 is a minute rotation of the auxiliary transmission 21, and therefore the movement of the work vehicle 1 can be minimized.

[0070] Furthermore, according to this embodiment, the sub-transmission command unit, the sub-transmission switch 15, is composed of an electrical switching device.

[0071] This allows the operator to easily select the target gear even when the sub-transmission 21 has multiple gears.

[0072] Furthermore, according to this embodiment, if the transmission, for example, after repeating the clearance operation a predetermined number of times by the control device 6, determines that the transmission has failed to switch to the second gear based on the gear position determination result by the gear position determination unit 6a, it will notify the error without performing the clearance operation.

[0073] This allows the system to automatically repeat the corrective operation even if a switching failure occurs in the sub-transmission 21. Furthermore, if the switching failure of the sub-transmission 21 is not resolved even after repeating the corrective operation, the system can notify the operator of this fact.

[0074] In the above-described embodiment, as an operation to resolve a switching failure of the sub-transmission 21, the control device 6 performs a switching operation on the sub-transmission 21 to return to the gear position one position before the target gear position as a gear position for retrying. However, the present invention is not limited to this example. For example, if the current gear position of the sub-transmission 21 is not neutral, and a switching failure to the target gear position occurs, the control device 6 sets the current gear position as the gear position for retrying. On the other hand, if the current gear position of the sub-transmission 21 is neutral, and a switching failure to the target gear position occurs, the control device 6 sets the gear position before switching to the current gear position (i.e., the previous gear position) as the gear position for retrying. In this example, the control device 6 stores not only the current gear position but also previous gear positions (at least the previous gear position) in the storage unit 7 as a history of the gear positions of the sub-transmission 21.

[0075] This ensures that, if the sub-transmission 21 has a neutral gear, when a shifting failure occurs, the sub-transmission 21 is returned to a gear other than neutral, for example, the previous gear, thereby reliably retrying the engagement of the sub-transmission gear of the sub-transmission 21 and improving the reliability of the operation to resolve shifting failures.

[0076] In the embodiment described above, the sub-transmission 21 was described as having four gear stages, including neutral, consisting of high speed, medium speed, neutral, and low speed, but it is not limited to this example. The sub-transmission 21 may be configured to have two or more gear stages, and may be configured to have multiple gear stages, such as a first gear, second gear, third gear, fourth gear, and fifth gear, with each stage represented by a numerical value or level.

[0077] In the embodiments described above, an example was explained in which the work vehicle of the present invention is composed of harvesting machines such as combine harvesters and vegetable harvesters. However, the present invention is not limited to this example, and the work vehicle of the present invention may be any vehicle that can move while performing work. For example, it may be composed of other agricultural machinery such as tractors, rice transplanters, and lawnmowers, or other work vehicles other than agricultural machinery.

[0078] Furthermore, the present invention may be modified as appropriate, provided that it does not contradict the gist or idea of ​​the invention as can be read from the claims and the specification as a whole. Transmissions, work vehicles, and control devices that involve such modifications are also included in the technical concept of the present invention.

[0079] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0080] <Note 1> A transmission comprising a main transmission for changing the power in the forward or reverse direction, and a sub-transmission for changing the power changed by the main transmission in a gear-switching manner, A sub-transmission command unit that outputs a gear shifting command for the aforementioned sub-transmission device, A sub-transmission operating mechanism that performs a gear shifting operation on the sub-transmission based on a gear shifting command from the sub-transmission command unit, Equipped with, The aforementioned sub-transmission operating mechanism is An operating member that transmits the gear shift switching operation to the auxiliary transmission, A linkage mechanism that operates the operating member based on the gear shift command, A gear shift position determination unit that determines the gear shift position of the gear shift based on the operating state of the operating member, Equipped with, A transmission characterized in that, when the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, if the gear shift position determination unit determines that the switch to the second gear has failed based on the gear shift position determination result, as a corrective action, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, the sub-transmission is switched back to the second gear.

[0081] <Note 2> The aforementioned main transmission is composed of a continuously variable transmission. The transmission according to Appendix 1, characterized in that, in the aforementioned resolution operation, the sub-transmission is driven by the drive of the continuously variable transmission to rotate a small amount.

[0082] <Note 3> The transmission according to Appendix 1 or 2, characterized in that, in the clearance operation, if the first gear is not in the neutral position, the first gear is set as the gear for retrying, while if the first gear is in the neutral position, the gear before switching to the first gear is set as the gear for retrying.

[0083] <Note 4> The transmission according to any one of the appendices 1 to 3, characterized in that the sub-transmission command unit is composed of an electrical switching device.

[0084] <Note 5> The transmission according to any one of the appendices 1 to 4, characterized in that, after repeating the aforementioned resolution operation a predetermined number of times, if the gear position determination unit determines that a failure to switch to the second gear has occurred based on the result of determining the gear position, it notifies the error without performing the aforementioned resolution operation.

[0085] <Note 6> A work vehicle equipped with a transmission as described in any of the appendices 1 to 5.

[0086] <Note 7> A transmission comprising a main transmission for changing the power in the forward or reverse direction, and a sub-transmission for changing the power changed by the main transmission in a gear-switching manner, A sub-transmission command unit that outputs a gear shifting command for the aforementioned sub-transmission device, A sub-transmission operating mechanism that performs a gear shifting operation on the sub-transmission based on a gear shifting command from the sub-transmission command unit, Equipped with, The aforementioned sub-transmission operating mechanism is An operating member that transmits the gear shift switching operation to the auxiliary transmission, A linkage mechanism that operates the operating member based on the gear shift command, A gear shift position determination unit that determines the gear shift position of the gear shift based on the operating state of at least one of the operating member and the linkage mechanism, Equipped with, When the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, and the gear shift position determination unit determines that the switch to the second gear has failed, the transmission is characterized in that, as a corrective action, during manual driving, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, while during automatic driving, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, the sub-transmission is switched back to the second gear.

[0087] <Note 8> The aforementioned main transmission is composed of a continuously variable transmission. The transmission according to Appendix 7, characterized in that, in the aforementioned resolution operation, the sub-transmission is driven by the drive of the continuously variable transmission to rotate a small amount.

[0088] <Note 9> The transmission according to Appendix 7 or 8, characterized in that, in the clearance operation, if the first gear is not in the neutral position, the first gear is set as the gear for retrying, while if the first gear is in the neutral position, the gear before switching to the first gear is set as the gear for retrying.

[0089] <Note 10> The transmission according to any one of the appendices 7 to 9, characterized in that the sub-transmission command unit is composed of an electrical switching device.

[0090] <Note 11> The transmission according to any one of the appendices 7 to 10, characterized in that, after repeating the aforementioned resolution operation a predetermined number of times, if the gear position determination unit determines that a failure to switch to the second gear has occurred based on the result of determining the gear position, it notifies an error without performing the aforementioned resolution operation.

[0091] <Note 12> A work vehicle equipped with a transmission as described in any of the appendices 7 to 11.

[0092] <Note 13> A control device for controlling a transmission comprising a main transmission for changing the speed of power in the forward or reverse direction, and a sub-transmission for changing the speed of power changed by the main transmission in a gear-switching manner, The unit includes a sub-transmission command unit that outputs a gear shifting command for the sub-transmission to a sub-transmission operating mechanism that performs gear shifting operations for the sub-transmission. The aforementioned sub-transmission operating mechanism is An operating member that transmits the gear shift switching operation to the auxiliary transmission, A linkage mechanism that operates the operating member based on the gear shift command, A gear shift position determination unit that determines the gear shift position of the gear shift based on the operating state of at least one of the operating member and the linkage mechanism, It is equipped with, A control device characterized in that, when the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, if the gear shift position determination unit determines that the switch to the second gear has failed based on the gear shift position determination result, the control device performs a reversal operation to return the sub-transmission to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, it controls the sub-transmission to perform the switch to the second gear again.

[0093] <Note 14> The aforementioned main transmission is composed of a continuously variable transmission. The transmission according to Appendix 13, characterized in that, in the aforementioned resolution operation, the sub-transmission is driven to rotate by the drive of the continuously variable transmission.

[0094] <Note 15> The transmission according to Appendix 13 or 14, characterized in that, in the clearance operation, if the first gear is not in neutral, the first gear is set as the gear for retry, while if the first gear is in neutral, the gear before switching to the first gear is set as the gear for retry.

[0095] <Note 16> The transmission according to any one of the appendices 13 to 15, characterized in that the sub-transmission command unit is composed of an electrical switching device.

[0096] <Note 17> A transmission according to any one of the appendices 13 to 16, characterized in that, after repeating the aforementioned resolution operation a predetermined number of times, if the gear position determination unit determines that a failure to switch to the second gear has occurred based on the result of determining the gear position, it notifies an error without performing the aforementioned resolution operation.

[0097] <Note 18> A work vehicle equipped with a transmission as described in any of the appendices 13 to 17. [Explanation of Symbols]

[0098] 1. Work vehicles 3. Running section 4. Control Unit 5 Power section 6. Control device 6a Gear shift position determination unit 11. Transmission (Gearbox) 14 Main gear lever 15. Sub-transmission switch (sub-transmission command unit) 16 Engine 20 Main transmission 21. Sub-transmission 25 Sub-transmission shifter 26 High-speed gear 27 Medium-speed gear 28 Low gear 30 Sub-transmission operating mechanism 31 Operating drive unit 32 Linkage mechanism 33 Operating member 34 Gear shift position detection unit 35 Drive position detection unit

Claims

1. A transmission comprising a main transmission for changing the power in the forward or reverse direction, and a sub-transmission for changing the power changed by the main transmission in a gear-switching manner, A sub-transmission command unit that outputs a gear shifting command for the aforementioned sub-transmission device, A sub-transmission operating mechanism that performs a gear shifting operation on the sub-transmission based on a gear shifting command from the sub-transmission command unit, Equipped with, The aforementioned sub-transmission operating mechanism is An operating member that transmits the gear shift switching operation to the auxiliary transmission, A linkage mechanism that operates the operating member based on the gear shift command, A gear shift position determination unit that determines the gear shift position of the gear shift based on the operating state of the operating member, Equipped with, When the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, if the gear shift position determination unit determines that the switch to the second gear has failed based on the gear shift position determination result, as a corrective action, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, the sub-transmission is again switched to the second gear. A transmission characterized in that, in the aforementioned clearance operation, if the first gear is not in the neutral position, the first gear is set as the gear for retrying, while if the first gear is in the neutral position, the gear before switching to the first gear is set as the gear for retrying.

2. The aforementioned main transmission is composed of a continuously variable transmission. The transmission according to claim 1, characterized in that, in the aforementioned resolution operation, the sub-transmission is driven to rotate by the drive of the continuously variable transmission.

3. The transmission according to claim 1 or 2, characterized in that the sub-transmission command unit is composed of an electrical switching device.

4. The transmission according to claim 1 or 2, characterized in that, after repeating the aforementioned resolution operation a predetermined number of times, if the transmission position determination unit determines that a failure to switch to the second gear has occurred based on the determination result of the gear position, it notifies the error without performing the aforementioned resolution operation.

5. A work vehicle equipped with the transmission according to claim 1 or 2.

6. A transmission comprising a main transmission for changing the power in the forward or reverse direction, and a sub-transmission for changing the power changed by the main transmission in a gear-switching manner, A sub-transmission command unit that outputs a gear shifting command for the aforementioned sub-transmission device, A sub-transmission operating mechanism that performs a gear shifting operation on the sub-transmission based on a gear shifting command from the sub-transmission command unit, Equipped with, The aforementioned sub-transmission operating mechanism is An operating member that transmits the gear shift switching operation to the auxiliary transmission, A linkage mechanism that operates the operating member based on the gear shift command, A gear shift position determination unit that determines the gear shift position of the gear shift based on the operating state of at least one of the operating member and the linkage mechanism, Equipped with, When the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, and the gear shift position determination unit determines that the switch to the second gear has failed, as a corrective action, in manual driving, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear; on the other hand, in automatic driving, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and after the main transmission drives the sub-transmission, the sub-transmission is switched back to the second gear. A transmission characterized in that, in the aforementioned clearance operation, if the first gear is not in the neutral position, the first gear is set as the gear for retrying, while if the first gear is in the neutral position, the gear before switching to the first gear is set as the gear for retrying.

7. A control device for controlling a transmission comprising a main transmission for changing the speed of power in the forward or reverse direction, and a sub-transmission for changing the speed of power changed by the main transmission in a gear-switching manner, The unit includes a sub-transmission command unit that outputs a gear shifting command for the sub-transmission to a sub-transmission operating mechanism that performs gear shifting operations for the sub-transmission. The aforementioned sub-transmission operating mechanism is An operating member that transmits the gear shift switching operation to the auxiliary transmission, A linkage mechanism that operates the operating member based on the gear shift command, A gear shift position determination unit that determines the gear shift position of the gear shift based on the operating state of at least one of the operating member and the linkage mechanism, It is equipped with, When the sub-transmission operating mechanism performs a gear shift operation based on the gear shift switching command which switches the sub-transmission from the current first gear to the target second gear in a predetermined gear shift direction, if the gear shift position determination unit determines that the switch to the second gear has failed based on the gear shift position determination result, as a corrective action, the sub-transmission is switched back to the retry gear located in the opposite direction to the gear shift direction from the second gear, and the main transmission drives the sub-transmission, and then controls the sub-transmission to perform the switch to the second gear again. A control device characterized in that, in the aforementioned resolution operation, if the first gear is not in the neutral position, the first gear is set as the gear for retrying, while if the first gear is in the neutral position, the gear before switching to the first gear is set as the gear for retrying.

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