JP2005104293A - Swinging control device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swinging control device capable of swinging a working vehicle to a desired direction even under a state that either a transmission position detecting means or transmission operating means is recognized as an abnormal operating state. <P>SOLUTION: It is recognized whether or not a transmission position detecting means is in an abnormal operation. When it is recognized that the operation is in an abnormal state, a transmission state changing-over means A is changed over to a right swinging transmission shut state for shutting a transmission power transmitted from a stepless transmission device 8 for a swinging operation at a right swinging transmission state to a right side running device 1R, and at a state that the operation is commanded to keep a leftward swinging by the swinging instruction means, the transmission state changing-over means A is changed over to a leftward swinging transmission shut state for shutting a transmission power transmitted from the stepless transmission device 8 for a swinging operation at a leftward swinging transmission state to a left running device 1L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a linear transmission state in which a shift output of a continuously variable continuously variable transmission is transmitted to each of a pair of left and right traveling devices, a transmission output of the continuously variable continuously variable transmission is transmitted to a right traveling device, and A left turn transmission state in which the shift output of the continuously variable transmission for turning is transmitted to the left traveling device, and the shift output of the continuously variable continuously variable transmission is transmitted to the left traveling device and is used for the turning. A transmission state switching means capable of switching to a right-turning transmission state that transmits a shift output of the continuously variable transmission to the right traveling device, and a shift operation target of the continuously variable transmission for turning. A shift operation means; a shift position detection means for detecting a shift position of the operated body; a manually operated shift operation tool for shifting the linearly variable continuously variable transmission device by manual operation; Turning command means for commanding turning and turning left, and Moving state switching means and control means for controlling the operation of the speed change operation means, and when the control means is commanded to go straight by the turning command means, the transmission state switching means is moved to the straight-running transmission state. And the operation of the shift operation means is controlled so that the continuously variable transmission for turning has the same or substantially the same speed as the continuously variable continuously variable transmission. When the rotation is commanded, the transmission state switching means is switched to the right turning transmission state, and the operation of the shift operation means is controlled so that the turning continuously variable transmission has the turning target speed. In addition, when a left turn is commanded by the turning command means, the transmission state switching means is switched to the left turning transmission state so that the turning continuously variable transmission has a turning target speed. Control the operation of the speed change operation means It relates turning control apparatus for working vehicle that is configured to so that.

In the conventional configuration of such a turning control device for a work vehicle, when a straight travel is commanded by the turn command means, a straight travel transmission that transmits a shift output of the continuously variable continuously variable transmission to each of the pair of left and right traveling devices. When the right turn is commanded by the turn command means, the shift output of the continuously variable continuously variable transmission is transmitted to the left traveling device and the shift output of the continuously variable transmission for turning is transferred to the right. When the left turn is commanded by the turn command means, the shift output of the continuously variable transmission for straight travel is transmitted to the right travel device and the turn is made. The shift output of the continuously variable transmission is configured to be switched to the left-turn transmission state in which the continuously variable transmission is transmitted to the left traveling device (see, for example, Patent Document 1).
JP 2002-362403 A

According to the detection result of the shift position detecting means for detecting the shift position of the object to be operated, the operation of the shift operation means is controlled so that the continuously variable transmission for turning becomes the target rotational speed for turning. If an operation abnormality occurs in the shift position detecting means for detecting the shift position of the operated body, the current rotational speed and direction of the continuously variable transmission for turning cannot be determined, and the continuously variable speed for turning is determined. Since the gear cannot be shifted to the target rotational speed for turning, the rotational direction of the continuously variable transmission for straight travel and the continuously variable transmission for turning is the same, and the continuously variable transmission for turning If turning is commanded by the turning command means when the turning speed of the continuously variable transmission for turning is faster than the turning speed, the work vehicle turns in a direction opposite to the turning direction intended by the operator. there were.
Therefore, in order to avoid the work vehicle from turning in the direction opposite to the turning direction intended by the operator, the control means determines whether or not the shift position detecting means is operating abnormally, and the shift position is determined. If the detection means is determined to be abnormal by the control means, the work vehicle cannot be turned so that it can only turn straight, or it can be controlled so that it cannot turn or move straight. Can be considered.

  Further, even if an operation abnormality occurs in the shift operation means for shifting the operated body, the turning continuously variable transmission cannot be shifted to the target rotational speed for turning. As in the case of an abnormal operation, the control means determines whether or not the speed change operation means is abnormal. If the speed change means is determined to be abnormal, the work vehicle cannot turn. It is also conceivable to perform control so that only a straight traveling is possible, or a turning traveling and a straight traveling are impossible and the vehicle cannot be self-propelled.

  However, with the above configuration, when the shift position detecting means or the shift operation means becomes abnormal in operation, the work vehicle is moved to a repair shop to repair the shift position detecting means or the shift operation means. It was inconvenient because the vehicle could not be turned.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to make a work vehicle turn in a desired turning direction even when the shift position detecting means and the shift operating means are determined to be abnormal. The object is to provide a turning control device for a working vehicle.

The turning control device for a work vehicle according to the present invention has a straight transmission state in which a shift output of a continuously variable continuously variable transmission is transmitted to each of a pair of left and right traveling devices, and a shift output of the continuously variable continuously variable transmission is on the right side. To the left traveling device, and to the left traveling device the transmission output for the left continuously variable transmission is transmitted to the left traveling device. A transmission state switching means that is capable of switching to a right-turning transmission state that transmits and transmits a shift output of the turning continuously variable transmission to a right-side traveling device; and for changing the speed of the continuously variable transmission for turning A shift operation means for shifting the operated body, a shift position detecting means for detecting a shift position of the operated body, and a manually operated shift for manually shifting the linearly variable continuously variable transmission. Command the control tool to go straight, turn right, and turn left Turning command means, and control means for controlling the operation of the transmission state switching means and the speed change operation means. When the control means is commanded to go straight by the turning command means, the transmission state switching is performed. Switching the means to the linear transmission state, and controlling the operation of the shift operation means so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission, When a right turn is commanded by the turning command means, the transmission state switching means is switched to the right turning transmission state so that the turning continuously variable transmission is at the target speed for turning. When the operation of the operating means is controlled and a left turn is commanded by the turning command means, the transmission state switching means is switched to the left turning transmission state, and the continuously variable transmission for turning is used for turning. To achieve the target speed of A turning control apparatus for working vehicle that is configured to control the operation of the fast operating means,
In the first characteristic configuration, the control means determines whether or not the shift position detecting means is abnormal in operation, and when it is determined that the operation is abnormal, a right turn is commanded by the turn command means. In the state, the transmission state switching means is switched to the right turning transmission cut-off state that cuts off the transmission power transmitted from the turning continuously variable transmission to the right traveling device in the right turning transmission state, In the state where the left turn is commanded by the turn command means, the left turn that cuts off the shift power transmitted from the turning continuously variable transmission to the left travel device in the left turn transmission state. The transmission state switching means is switched to the transmission cutoff state for use.

  That is, the control means can determine whether or not the shift position detecting means is abnormal in operation, and in a state where the shift position detecting means is determined to be abnormal in operation, for example, the turning command means can turn right. When the rotation is commanded, the transmission state switching means switches to the right turn transmission cut-off state, transmits the shift output of the continuously variable transmission for straight travel to the left traveling device, and travels straight to the right traveling device. The transmission power of either the continuously variable transmission for turning or the continuously variable transmission for turning is not transmitted, and the right traveling device that does not rotate by driving acts as a resistance so that the work vehicle can travel in the right turn. . When a left turn is commanded by the turn command means, the transmission state switching means switches to the left turn transmission cut-off state, and the shift output of the continuously variable transmission for straight travel is transmitted to the right traveling device. The left traveling device is in a state where neither the straight-line continuously variable transmission nor the turning continuously variable transmission is transmitted to the left traveling device, and the left traveling device that does not drive and rotate is in resistance and the work vehicle is rotated counterclockwise. It will run in times.

In other words, an abnormal operation occurs in the shift position detecting means for detecting the shift position of the operated body, and the current rotational speed and direction of the continuously variable transmission for turning cannot be determined. Even if the transmission cannot be shifted to the target rotational speed for turning, when the turning is commanded by the turning command means, the transmission state switching means is moved to the traveling device on the turning center side and the continuously variable transmission for straight running and The work vehicle can be turned regardless of the rotation state of the continuously variable transmission for turning as a state where no shift output is transmitted from any of the continuously variable transmission for turning. Even if the rotation speed of the continuously variable transmission for turning is higher than the rotational speed of the continuously variable transmission for turning, the turning direction intended by the operator The work vehicle turns in the opposite direction Ukoto is eliminated.
Accordingly, it is possible to provide a turning control device for an action vehicle that can turn the work vehicle in a desired turning direction even when the shift position detecting means is determined to be abnormal in operation.

The turning control device for a work vehicle according to the present invention has a straight transmission state in which a shift output of a continuously variable continuously variable transmission is transmitted to each of a pair of left and right traveling devices, and a shift output of the continuously variable continuously variable transmission is on the right side. To the left traveling device, and to the left traveling device the transmission output for the left continuously variable transmission is transmitted to the left traveling device. A transmission state switching means that is capable of switching to a right-turning transmission state that transmits and transmits a shift output of the turning continuously variable transmission to a right-side traveling device; and for changing the speed of the continuously variable transmission for turning A shift operation means for shifting the operated body, a shift position detecting means for detecting a shift position of the operated body, and a manually operated shift for manually shifting the linearly variable continuously variable transmission. Command the control tool to go straight, turn right, and turn left Turning command means, and control means for controlling the operation of the transmission state switching means and the speed change operation means. When the control means is commanded to go straight by the turning command means, the transmission state switching is performed. Switching the means to the linear transmission state, and controlling the operation of the shift operation means so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission, When a right turn is commanded by the turning command means, the transmission state switching means is switched to the right turning transmission state so that the turning continuously variable transmission is at the target speed for turning. When the operation of the operating means is controlled and a left turn is commanded by the turning command means, the transmission state switching means is switched to the left turning transmission state, and the continuously variable transmission for turning is used for turning. To achieve the target speed of A turning control apparatus for working vehicle that is configured to control the operation of the fast operating means,
In the second characteristic configuration, when the control means determines whether or not the speed change operation means is abnormal in operation, and when it is determined that the operation is abnormal, a state in which a right turn is commanded by the turn command means Then, in the right turn transmission state, the transmission state switching means is switched to the right turn transmission cut-off state that cuts off the transmission power transmitted from the turning continuously variable transmission to the right traveling device, and In the state where the left turn is commanded by the turn command means, the left turn transmission that cuts off the transmission power transmitted from the turning continuously variable transmission to the left travel device in the left turn transmission state. The transmission state switching means is configured to be switched to a cut-off state.

  That is, it is possible to determine whether or not the speed change operation means is abnormal in operation by the control means. For example, in the state where it is determined that the speed change operation means is abnormal in operation, for example, a right turn is made by the turn command means. When commanded, the transmission state switching means switches to the right-turn transmission cut-off state, transmits the shift output of the continuously variable transmission for straight travel to the left traveling device, and transmits to the right traveling device for straight travel. The transmission power of either the continuously variable transmission or the continuously variable transmission for turning is not transmitted, and the right traveling device that does not rotate by driving acts as a resistance so that the work vehicle can travel in the right turn. When a left turn is commanded by the turn command means, the transmission state switching means switches to the left turn transmission cut-off state, and the shift output of the continuously variable transmission for straight travel is transmitted to the right traveling device. The left traveling device is in a state where neither the straight-line continuously variable transmission nor the turning continuously variable transmission is transmitted to the left traveling device, and the left traveling device that does not drive and rotate is in resistance and the work vehicle is rotated counterclockwise. It will run in times.

In other words, an abnormal operation occurs in the speed change operation means for shifting the operated body, and the operated body in the continuously variable transmission for turning cannot be accurately shifted, and the continuously variable transmission for turning is swung. Even if it becomes impossible to change the speed to the target rotational speed for turning, when turning is commanded by the turning command means, the transmission state switching means is moved straight to the traveling device on the turning center side and the continuously variable transmission for turning and The work vehicle can be turned regardless of the rotation state of the continuously variable transmission for turning in a state where no shift output is transmitted from any of the stepped transmissions, and the continuously variable transmission for straight running and the continuously variable transmission for turning Even if the rotational speed of the continuously variable transmission for turning is faster than the rotational speed of the continuously variable transmission for turning, the direction of rotation with the device is the opposite direction to the turning direction intended by the operator The work vehicle may turn Kunar.
Accordingly, it is possible to provide a turning control device for a working vehicle that can turn the work vehicle in a desired turning direction even when the shift operation means is determined to be abnormal in operation.

  In addition to the second feature configuration described above, the third feature configuration includes a double-acting fluid pressure cylinder in which the speed change operation means can operate the operated body in a forward direction and a reverse direction from a neutral position, and a fluid thereof. A fluid pressure control mechanism for switching the supply / discharge state of the working fluid with respect to the pressure cylinder, and the fluid pressure control mechanism is urged to return to the neutral position by the urging means, and from the neutral position. A spool that can be moved to a forward output position that moves in the forward direction and a reverse output position that moves in the reverse direction from the neutral position, and a working fluid is supplied to move the spool in the forward direction. A forward rotation pressure operation section, a reverse rotation pressure operation section to which a working fluid is supplied to move the spool in the reverse direction, a forward rotation pressure operation section, and a reverse rotation pressure operation section. Working fluid A pair of solenoid valves that can be switched between a supply state to supply and a discharge state to discharge the working fluid, and when the spool is in the forward output position, the fluid of the pair of output ports One forward direction output port connected to the fluid chamber for forward operation of the pressure cylinder is connected to the input port, and a backward output port connected to the fluid chamber for backward operation of the fluid pressure cylinder When the spool is in the state of being connected to the discharge port and the spool is in the reverse output position, one of the pair of output ports is connected to the fluid chamber for forward operation of the fluid pressure cylinder. And the reverse output port connected to the fluid chamber for reverse operation of the fluid pressure cylinder is connected to the input port, and the spool is in the neutral position. Each of the pair of output ports is configured not to be connected to any of the input port and the discharge port, and the control means determines whether at least one of the pair of solenoid valves is abnormal in operation. When the right turn is commanded by the turn command means, in the right turn transmission state, the right step from the continuously variable transmission for turning is determined. In the state where the transmission state switching means is switched to the right turn transmission cut-off state for cutting off the transmission power transmitted to the traveling device, and the left turn is commanded by the turn command means, the left turn transmission In the state, the transmission state switching means is switched to a left turning transmission cut-off state that cuts off the transmission power transmitted from the turning continuously variable transmission to the left traveling device. Characterized by points.

  That is, when the pair of solenoid valves is switched to the supply state or the discharge state, the spool is in the neutral position, the forward output position moved in the forward direction from the neutral position, and the reverse output position moved in the reverse direction from the neutral position. Each is operated to move, hydraulic oil is supplied and discharged at the forward output position of the spool to move the fluid pressure cylinder in the forward direction, and the fluid pressure cylinder is moved in the reverse direction when the spool is in the reverse direction. The hydraulic oil is supplied and discharged to be moved, the hydraulic oil is discharged when the spool is in the neutral position, and the fluid pressure cylinder is returned to the neutral position by the urging means.

  When the spool moves to the neutral position, each of the pair of output ports is not connected to either the discharge port or the discharge port, and the fluid pressure cylinder is held in that state. Even if one of them becomes abnormal in operation, the object to be operated in the continuously variable transmission for turning cannot be accurately shifted, and the continuously variable transmission for turning cannot be shifted to the target rotational speed for turning. When it is determined that at least one of the pair of solenoid valves is operating abnormally, the transmission state switching means includes a continuously variable transmission for straight travel and a continuously variable transmission for swing. Thus, the work vehicle is prevented from turning in the direction opposite to the turning direction intended by the operator.

  In addition to the second feature configuration described above, the fourth feature configuration includes a double-acting fluid pressure cylinder in which the speed change operation means can operate the operated body in a forward direction and a reverse direction from a neutral position, and the fluid A fluid pressure control mechanism for switching the supply / discharge state of the working fluid with respect to the pressure cylinder, and the fluid pressure control mechanism is urged to return to the neutral position by the urging means, and from the neutral position. A spool that can be moved to a forward output position that moves in the forward direction and a reverse output position that moves in the reverse direction from the neutral position, and a working fluid is supplied to move the spool in the forward direction. A forward rotation pressure operation section, a reverse rotation pressure operation section to which a working fluid is supplied to move the spool in the reverse direction, a forward rotation pressure operation section, and a reverse rotation pressure operation section. Working fluid A pair of solenoid valves that can be switched between a supply state to supply and a discharge state to discharge the working fluid, and when the spool moves to the forward output position, One forward output port connected to the fluid chamber for forward operation of the fluid pressure cylinder is connected to the input port, and the backward output port connected to the fluid chamber for backward operation of the fluid pressure cylinder When the spool moves to the reverse output position, one of the pair of output ports is connected to the fluid chamber for forward operation of the fluid pressure cylinder. A reverse output port connected to a discharge port and connected to a fluid chamber for reverse operation of the fluid pressure cylinder is connected to an input port, and the spool is When moved to the position, each of the pair of output ports is configured to be connected to the discharge port, and the control means is an on-failure in which one of the pair of solenoid valves is fixed in the supply state. When the other side is in an off-failure state that is fixed in the discharged state, it is determined that the operation is abnormal, and in the state in which a right turn is commanded by the turn command means, the right turn transmission state The transmission state switching means is switched to the right turning transmission cut-off state for cutting off the transmission power transmitted from the turning continuously variable transmission to the right traveling device, and the turning command means makes a left turn. In the commanded state, the transmission state switching means is switched to the left turning transmission cut-off state that cuts off the transmission power transmitted from the turning continuously variable transmission to the left traveling device in the left turning transmission state. Cut It is characterized by being configured to be replaced.

  That is, when the pair of solenoid valves is switched to the supply state or the discharge state, the spool is in the neutral position, the forward output position moved in the forward direction from the neutral position, and the reverse output position moved in the reverse direction from the neutral position. Each is operated to move, hydraulic oil is supplied and discharged at the forward output position of the spool to move the fluid pressure cylinder in the forward direction, and the fluid pressure cylinder is moved in the reverse direction when the spool is in the reverse direction. The hydraulic oil is supplied and discharged to be moved, the hydraulic oil is discharged when the spool is in the neutral position, and the fluid pressure cylinder is returned to the neutral position by the urging means.

  When the spool moves to the neutral position, each of the pair of output ports is connected to the discharge port, and the hydraulic cylinder is returned to the neutral position by the biasing means. Even if the operation of the continuously variable transmission for turning cannot be accurately controlled and the continuously variable transmission for turning cannot be changed to the target rotational speed for turning, When it is determined that both of the solenoid valves are operating abnormally, the transmission state switching means has a speed change between the continuously variable transmission for straight traveling and the continuously variable transmission for turning. By switching to the transmission cut-off state in which the output is not transmitted from either, the work vehicle does not turn in the direction opposite to the turning direction intended by the operator.

  In addition to any one of the first to fourth feature configurations described above, the fifth feature configuration is movable between a rectilinear command position commanding straight travel and a turn command position commanding swivel travel, and A turn command means is provided that can be moved and operated over the entire range of a predetermined operation area at the turn command position, and the turn command means is used as a target speed for turning in a direction away from the straight command position in the turn command area. It is characterized in that it is configured to command a lower speed as the movement amount is larger.

  In other words, since the target speed for turning in the continuously variable transmission for turning becomes lower as the distance in the direction away from the rectilinear command position increases, the amount of operation in the direction away from the rectilinear instruction position increases. Accordingly, the turning radius of the work vehicle becomes smaller, the feeling of the operation of the travel command means and the turning of the work vehicle can be easily matched, and the work vehicle can be improved in operability.

[First embodiment]
Hereinafter, the case where the control valve and the shift operation device according to the present invention are applied to a shift operation device in a combine will be described with reference to the drawings.

  FIG. 1 shows an overall side view of a combine that is an example of a work vehicle. The combine is set at the front of a traveling machine body 2 that is driven by a pair of left and right crawler type traveling devices 1R and 1L. A threshing device 4 that cuts the straw and conveys it backwards is connected so as to be able to move up and down, and the threshing device 4 that receives the harvested cereal mash from the cutting and transportation device 3 and performs threshing / sorting processing to the traveling machine body 2 It is comprised by mounting the grain tank 5 which stores the grain from the apparatus 4, and forming the boarding operation part 6 in the front location of the grain tank 5. FIG.

Next, the transmission structure of this combine is demonstrated.
As shown in FIG. 2, the continuously variable transmission 7 for linear travel that can change the traveling speed in a straight traveling state and the traveling speed of the traveling device that is located on the turning center side during turning traveling can be varied for turning. Of the continuously variable transmission 8 and a transmission case 9 to which the power from the continuously variable transmissions 7 and 8 is input and the power to the left and right traveling devices 1R and 1L is output. Has been.
The linearly variable continuously variable transmission 7 and the continuously variable continuously variable transmission 8 include variable hydraulic pumps 7A and 8A driven by power from an engine mounted on a combine body, and variable hydraulic pumps 7A, 7A, It is constituted by a hydrostatic continuously variable transmission (HST) having a well-known structure constituted by a pair with hydraulic motors 7B and 8B that are rotationally driven by oil supplied from 8A. Incidentally, the power of the engine is transmitted to the transmission shaft 12 of the variable hydraulic pumps 7A and 8A via the transmission belt 10 and the transmission pulley 11.

  The transmission case 9 includes therein an output shaft 20 of the continuously variable transmission 7 for linear movement and an output shaft 21 of the continuously variable transmission 8 for turning. Power from 20, 21 is transmitted to the pair of left and right traveling devices 1R, 1L, while power from the output shaft 20 of the continuously variable continuously variable transmission 7 is transmitted to the cutting and conveying device 3. . A right output gear 21a and a left output gear 21b are fixed to the output shaft 21 of the continuously variable transmission 8 for turning.

  A pair of large and small output gears 20a, 20b for sub-shifting and an output gear 20c for driving the cutting unit are fixed to the output shaft 20 of the continuously variable transmission 7 for linear movement. The auxiliary transmission shaft 22 supports an auxiliary transmission small-diameter gear 22a and a large-diameter gear 22b that are always meshed with the output gears 20a and 20b, and is relatively rotatably supported. A sub-shift gear shift gear 22d that rotates integrally with the transmission shaft 22 is slidably fitted in the axial direction. A sub-transmission device is configured in which the sub-shift gear 22d is slid and operated so that it can be shifted in two steps. An output gear 22e is fixed to the auxiliary transmission shaft 22, and a center gear 24 provided integrally with the support shaft 23 is always in mesh with the output gear 22e.

  The support shaft 23 has a straight transmission state in which the speed change output of the continuously variable transmission 7 for straight travel is transmitted to each of the pair of left and right traveling devices 1L and 1R on both sides of the center gear 24, and the straight travel A left-turn transmission state in which the transmission output of the continuously variable transmission is transmitted to the right traveling device and the transmission output of the continuously variable transmission for turning is transmitted to the left traveling device; and the linearly variable continuously variable transmission Is provided with transmission state switching means 27 that can be switched to a right-turning transmission state that transmits the transmission output of the right-hand side to the left-side traveling device and the transmission output of the continuously variable transmission for turning to the right-side traveling device. Yes.

  The transmission state switching means 27 includes a left and right outer gear portion 25a that is always meshed with the left output gear 21a, and a right gear device that has a right outer gear portion 25b that is always meshed with the right output gear 21b. A pair of multi-plate friction clutches 25, 25 and a pair of left and right meshing clutches 27, 27 formed between both side surfaces of the center gear 24 and the shift gear 26 facing the both sides. The left friction clutch 25 constitutes a left clutch that can be switched to a state in which transmission between the continuously variable transmission 8 for turning and the left traveling device 1L is cut off, and the right friction clutch 25 A left clutch is configured that can be switched to a state in which transmission between the continuously variable transmission 8 for turning and the right traveling device 1R is cut off.

  The left and right shift gears 26 can be shifted in the direction of the axis of rotation, and when the shift operation is performed, the meshing clutch 27 meshes with the transmission and the meshing clutch 27 enters a state where transmission is not engaged. The friction plate in the shift gear 26 is configured to be shiftable with respect to the main body of the shift gear 26. When the clutch 27 is in a transmission cut-off state, the multi-plate friction clutch 25 is in pressure contact and is transmitted. It is configured to be switchable between a state where it is engaged and a state where transmission where the multi-plate friction clutch 25 is not pressed is cut off.

  That is, the power transmission to the pair of left and right traveling devices 1L, 1R is a transmission state in which the power from the straight transmission 7 is transmitted and the friction clutch 25 is in pressure contact in the transmission state in which the meshing clutch 27 is engaged. Then, when the power from the turning continuously variable transmission 8 is transmitted and both the meshing clutch 27 and the friction clutch 25 are in the transmission cut-off state, the continuously variable transmission 7 for straight traveling and the continuously variable transmission for turning. No power is transmitted from either of them.

The left and right shift gears 26 and 26 are urged into a transmission state in which the meshing clutches 27 and 27 mesh with each other by the pressing force of the pressure springs 29 and 29, respectively. By shifting the hydraulic cylinders 31L and 31R for shutting off against the pressing force of the clutch 29, the switching operation can be switched to the transmission cut-off state where the meshing clutches 27 and 27 are not engaged. The operation of the shutoff hydraulic cylinders 31L and 31R is configured by switching the shutoff solenoid valves 63 and 64 as shown in FIG.
In this transmission cut-off state, the friction plate in the shift gear 26 is shifted by the steering hydraulic cylinders 30L and 30R, so that the operation can be switched to the transmission state in which the friction clutches 25 and 25 are pressed.
The shift gear 26 is transmitted to the pair of left and right traveling devices via the final gear 35. The shift gear 26 is configured to always mesh with the relay gear 34 of the transmission system to the traveling device regardless of whether the meshing clutch 27 is meshed or not.

  The linearly variable continuously variable transmission device 7 is configured to be able to perform a stepless speed change operation from the neutral position in each of the forward rotation direction and the reverse rotation direction. A main speed change lever 14 is provided as a manually operated speed change operation tool for operating the device 7, and the main speed change lever 14 can be swung by a manual operation over a predetermined front and rear operation range along the front and rear direction. It is configured. As shown in FIG. 3, the straight traveling swash plate 13 of the variable hydraulic pump 7 </ b> A is linked to the main transmission lever 14 via the hydraulic servo mechanism SV, and based on the operation command of the main transmission lever 14, the straight traveling swash plate 13. By changing the angle, the output state on the hydraulic motor 7B side is changed steplessly. In other words, if there is a manual operation on the main transmission lever 14, the shift operation can be lightly operated by performing an assist operation with the hydraulic operation force by the action of the hydraulic servo mechanism SV. .

  As shown in FIG. 8, when the shift lever 14 is in the neutral range and the neutral state is commanded, the straight traveling swash plate 13 becomes neutral and the hydraulic motor 7B does not rotate and is maintained in the stopped state. If the command from the speed change lever 14 is a speed change command to the forward speed increase side or the reverse speed increase side, the angle of the straight traveling swash plate 13 is forward rotated by the hydraulic servomechanism SV according to the operation command of the main speed change lever 14. (Forward acceleration direction) or reverse direction (reverse acceleration direction) is tilted by the command amount by the main shift lever 14 by the hydraulic operating force, and the hydraulic motor 7B moves in the forward or reverse direction at a speed according to the command. A speed change operation is performed so as to be rotationally driven.

  On the other hand, like the continuously variable continuously variable transmission 7 for the turning, the continuously variable transmission 8 for turning is configured to be capable of a variable speed operation in both the forward direction and the reverse direction. However, the turning continuously variable transmission 8 does not shift manually, but the turning swash plate 15 of the variable hydraulic pump 8A (an example of an object to be changed) is a hydraulic turning operation mechanism. 16 (an example of a speed change operation means), and by changing the swash plate angle by the turning operation mechanism 16, the output state on the hydraulic motor 8B side is changed. As shown in FIG. 3, the turning operation mechanism 16 is a double-acting transmission hydraulic cylinder 17 (an example of a fluid pressure cylinder) that is interlocked and connected to a turning swash plate 15 in a continuously variable transmission 8 for turning. And a hydraulic pressure control unit VU (an example of a fluid pressure control mechanism) for switching the operation oil supply / discharge state with respect to the transmission hydraulic cylinder 17. The shifting hydraulic cylinder 17 is configured as a double-acting type that can be operated from the neutral position in the forward direction and in the reverse direction, and is urged to return to the neutral position by the urging force of the pair of left and right springs 17a and 17b. It becomes the composition which is done.

Next, the configuration of the hydraulic control unit VU will be described.
As shown in FIG. 4, the hydraulic control unit VU includes a hydraulic pilot control valve 36 that controls the hydraulic pressure supply state so as to drive the shift hydraulic cylinder 17 in the forward and reverse directions from the neutral shift position. It is configured. The control valve 36 includes a spool 37 that can be moved to a forward output position moved in the forward direction from the neutral position, and a reverse output position moved in the reverse direction from the neutral position, and the spool 37 is moved to the neutral position. And a pair of coil springs 38 and 39 as urging means for urging and returning to the pilot oil passage, and a relief valve 49 for the pilot oil passage.

  Further, the control valve 36 is supplied with hydraulic oil for moving the spool 37 in the forward direction and is supplied with hydraulic oil for moving the spool 37 in the reverse direction. A reverse pressure operation section 41 to be supplied is provided, and a forward pressure solenoid valve 42 for pilot pressure control for controlling the supply state of hydraulic oil to the forward pressure operation section 40, and a reverse pressure operation section 41. A reverse pressure solenoid valve 43 for pilot pressure control that controls the supply state of hydraulic fluid to the engine is switchable between a supply state for supplying hydraulic fluid and a discharge state for discharging hydraulic fluid, and is urged to return to the discharge state. It is provided in the state.

  That is, the pair of pilot pressure control solenoid valves 42 and 43 stop supplying the hydraulic oil supplied from a hydraulic pump (not shown) to the pressure operating units 40 and 41 and the supply from the hydraulic pump. Thus, the solenoid valves 42 and 43 for controlling the pilot pressure are springs. It is configured to be urged to return to the discharge state by 45 and 46, and by energizing and energizing the solenoids 47 and 48, the valve body is operated against the urging force of the springs 45 and 46 to enter the supply state. It is configured to switch. Therefore, when the energization is stopped, the pilot pressure control solenoid valves 42 and 43 are always in the discharged state, and the state is maintained.

  The control valve 36 is provided with a pair of output ports OP1 and OP2 that are individually connected to a pair of hydraulic oil chambers 17A and 17B (an example of a fluid chamber) of the hydraulic cylinder 17 for shifting. In the neutral position as shown, each of the pair of output ports OP1 and OP2 is configured not to be connected to either the input port IP or the discharge port DP. Therefore, the shift hydraulic cylinder 17 is in a state of maintaining the shift position at that time.

When the spool 37 reaches the forward output position, one forward output port OP1 connected to the hydraulic fluid chamber 17A for forward operation of the shifting hydraulic cylinder 17 out of the pair of output ports OP1 and OP2. Is connected to the input port IP, and the reverse output port OP2 connected to the hydraulic oil chamber 17B for reverse operation of the shifting hydraulic cylinder 17 is connected to the discharge port DP. Therefore, the shifting hydraulic cylinder 17 is moved in the forward direction (forward acceleration direction).
When the spool 37 reaches the reverse output position, the forward output port OP1 is connected to the discharge port DP, and the reverse output port OP2 is connected to the input port IP. Therefore, the shifting hydraulic cylinder 17 is operated to move in the reverse direction (reverse acceleration direction).

  If the shifting operation of the continuously variable transmissions 7 and 8 is described, for example, as shown in FIG. 5, the shifting positions of the swash plates 13 and 15 are in a neutral region having a predetermined width including the neutral position N. For example, the shift output (travel speed) becomes zero, and when the shift position of the swash plates 13 and 15 is rotated in a predetermined direction from the neutral range, the travel speed in the forward direction is increased steplessly. When 13 and 15 are operated in a direction opposite to the predetermined direction from the neutral zone, the traveling speed in the backward direction is increased steplessly.

The boarding operation unit 6 can be moved and operated between a neutral position (straight running position) for commanding straight traveling and a turning command position for commanding swiveling, and over the entire range of a predetermined operation region at the turning operation position. A swiveling lever 56 (an example of a swiveling command unit) that can be moved and operated is provided. As shown in FIG. 3, the output rotation speeds of the turning lever sensor 57 (an example of the turning command means) composed of a rotary potentiometer that detects the operation position of the turning lever 56, and the pair of continuously variable transmissions 7 and 8, respectively. Rotation sensors 58 and 59 that detect by counting the number of teeth of the output gear 22e and the right output gear 21a, and a potentiometer type that detects the swash plate angle of the straight traveling swash plate 13 of the continuously variable transmission 7 for straight traveling. There are a linear shift position sensor 60, a potentiometer-type shift position sensor 61 for detecting the slope angle of the continuously variable transmission 8 for turning, a turning mode switching operation tool 62 for switching the turning mode to three stages by dial operation, and the like. The turning operation mechanism 16 and the steering hydraulic cylinders 30R and 30L and the shut-off hydraulic cylinder 30R are provided based on the input information. Control device H of the microcomputer utilized as control means for controlling the operation of 31L is provided.
The straight shift position sensor 60 outputs a voltage corresponding to the angle (inclined position) of the straight travel swash plate 13 in the straight forward continuous transmission 7, and the voltage is A / D converted. The straight shift detection value is input to the control device H, and the turning shift position sensor 61 outputs a voltage corresponding to the angle (tilting position) of the turning swash plate 15 in the turning continuous transmission 8. The voltage is A / D converted and input to the control device H as a detection value for turning.

  Next, turning control by the control device H will be described. As shown in the flowchart of FIG. 6, first, abnormal operation of the pair of electromagnetic valves 42 and 43 and the turning shift position sensor 61 in the turning operation mechanism 16 is detected. An abnormality determination control for determining is performed, and when at least one of the pair of solenoid valves 42 and 43 is determined to be abnormal in operation, the abnormality is set. If the turning lever 56 is turned to the left or right from the neutral position when the main speed change lever 14 is operated and the vehicle travels straight in a state where no abnormality is set, the turning center side, that is, the turning direction is changed. If it is right, the right turning hydraulic cylinder 31R is actuated and the right steering hydraulic cylinder 30R is actuated to transmit the shifting power of the turning continuously variable transmission 8 to the right traveling device 1R. Switch to the transmission mode. That is, when the right friction clutch 25 is in the transmission state, the right traveling device which is the turning center side is driven by the continuously variable transmission 8 for turning, and the left meshing clutch 27 is in the transmission state. As a result, the traveling device on the left side opposite to the turning center side is switched to a transmission state driven by the continuously variable transmission 7 for straight travel. The continuously variable transmission for turning so that the left and right traveling devices 1R, 1L have the same rotation direction and the speed ratio of the rotation speeds corresponds to the turning radius commanded by the turning lever 56. The target shift position is obtained.

  If the turning lever 56 is turned to the left or right from the neutral position when the main speed change lever 14 is operated and the vehicle is traveling straight in the abnormally set state, the turning center side, that is, the turning direction is changed. If it is right, the right cutoff hydraulic cylinder 31R is activated and the right steering hydraulic cylinder 30R is deactivated, so that the straight traveling continuously variable transmission 7 and turning continuously variable transmission are transferred to the right traveling device 1R. No. 8 is switched to the right-turning transmission cut-off state in which no transmission power is transmitted. That is, when the right friction clutch 25 and the meshing clutch 27 are both in the transmission cut state, the right traveling device on the turning center side is switched to the free rotation state, and the left meshing clutch 27 is in the transmission entering state. The traveling device on the left side opposite to the turning center side is switched to a transmission state driven by the continuously variable transmission 7 for straight travel.

  The processing for obtaining the target shift position will be described. As shown in FIG. 8, the relationship between the amount of movement of the turning lever 56 in the turning command operation area in the direction away from the rectilinear command position and the speed ratio corresponding to the turning radius is shown. It is determined and stored as a relationship corresponding to a quadratic function. On the other hand, the target shift position of the continuously variable transmission 8 for turning, that is, the target swash plate position, is obtained from the detected value for straight travel from the straight shift position sensor 60 and the function having the relationship shown in FIG. . Then, the shift operation is performed by controlling the operation of the turning operation mechanism 16 so that the detected value for turning from the turning position sensor 61 for turning becomes the target shift value. Incidentally, the speed change position of the continuously variable transmission 7 for straight traveling is adjusted by manual operation with respect to the speed change lever 14.

  9, the line L1 in FIG. 9 indicates the speed of the reference continuously variable transmission, the line L2 indicates the change in the target rotational speed in the slow turning mode, and the line L3 indicates the signal. A change in the target rotation speed in the ground turning mode is shown, and a line L4 shows a change in the target rotation speed in the super turning mode, and the turning mode designated by the turning mode switching operation tool 62 is selected. become. In other words, in the gentle turning mode indicated by the line L2, when the turning lever 56 is operated to the maximum operating position, the turning side traveling device is about 1/3 of the traveling speed V of the opposite side traveling device. A change characteristic of the speed ratio of the left and right traveling apparatuses 1R and 1L with respect to the operation position of the turning lever 56 is set in advance so as to be decelerated to the speed. In the belief turning mode indicated by the line L3, when the turning lever 56 is operated to the maximum operating position, the operation position of the turning lever 56 is decelerated until the traveling speed of the turning side traveling device becomes zero. The speed ratio of the left and right traveling devices 1R, 1L is preset. Also, in the super turning mode indicated by the line L4, when the turning lever 56 is operated to the maximum operating position, the running speed of the turning side traveling device rotates in the opposite direction to the drive rotation direction of the opposite side traveling device. The speed ratio of the left and right traveling apparatuses 1R and 1L with respect to the operation position of the turning lever 56 is set in advance so that the speed is the same as the speed of the opposite traveling apparatus.

  When the turning lever 56 is in the neutral position, speed synchronization processing for straight traveling is executed. In this speed synchronization process, neither the left or right steering hydraulic cylinders 30R, 30L are operated, so there is no function for shifting the traveling speed of the traveling device by automatic control, but there is no function for straight-ahead shifting by a manual shifting operation. The turning of the continuously variable transmission 8 for turning based on the detection information of the rotation sensors 58 and 59 so as to always rotate in the same direction as the rotational direction of the step transmission 7 at an output rotational speed substantially the same as the output rotational speed. A process of shifting the swash plate 15 is performed.

  A process for controlling the operation of the turning operation mechanism 16 when the turning continuously variable transmission 8 is shifted will be described. For example, when the continuously variable transmission 8 for turning is shifted in the forward acceleration direction in accordance with the operation of the turning lever 56, the spool 37 in the control valve 36 is moved to the forward output position. Specifically, a pulse current that repeatedly turns on and off is supplied to the solenoid 47 in the solenoid valve 42 for pilot pressure control with respect to the pressure operation unit 40 for forward rotation every setting cycle, and according to the duty ratio. Thus, the solenoid valve 42 is switched between a supply state and a discharge state. As a result, the spool 37 is operated to move against the biasing force of the spring 39 by the electromagnetic force, and moves to the forward output position. When shifting the continuously variable transmission 8 for turning in the reverse speed increasing direction, the spool 37 in the control valve 36 is moved to the reverse output position. At this time, the pilot pressure applied to the pressure operating unit 41 for reverse rotation is operated. The control solenoid valve 43 is similarly controlled.

  When the output rotational speed of the continuously variable transmission 8 for turning reaches the target rotational speed by the speed increasing operation, the spool 37 is moved to the neutral position. As a result, the hydraulic oil is not discharged from the transmission hydraulic cylinder 17, and the transmission hydraulic cylinder 17 maintains the transmission position at that time. Note that the same processing is performed for the operation at the forward holding position even when the holding is performed at the backward holding position.

Next, the abnormality determination control for determining the operation abnormality of the turning shift position sensor 61 will be described. The turning shift position sensor 61 is set at the angle (tilt position) of the turning swash plate 15 in the turning continuous transmission 8. Accordingly, a voltage within a predetermined range is output. When a voltage outside the predetermined range is output from the shift position sensor for turning, and the voltage is A / D converted and input to the control device, the shift for turning is performed. It is determined that the position sensor 61 is operating abnormally.
As a specific example, when the voltage is output from the shift gear position sensor 61 in the range from a value exceeding 0V to a value less than 5V according to the angle of the turning swash plate 15, the turning shift is performed. When the voltage output from the position sensor 61 becomes 0 V or 5 V or more, it is determined that the turning shift position sensor 61 is abnormal in operation.

In a state where the turning shift position sensor 61 is determined to be abnormal, when the turning lever 56 is instructed to turn, the friction clutch 25 on the turning center side in the transmission state switching means A Both the meshing clutch 27 are configured to be switched to the transmission cut-off state.
In other words, when the turning gear 56 is commanded to turn while the turning shift position sensor 61 is determined to be in an abnormal operation, the shut-off hydraulic cylinder is in a non-actuated state and in a transmission state. The friction clutch 25 on the turning center side is brought into the transmission cut-off state by the operation of the shut-off hydraulic cylinder, and the meshing clutch 27 on the turning center side which is in the transmission cut-off state with the steering hydraulic cylinder in the non-operating state is maintained in the transmission cut-off state. Thus, the traveling device on the turning center side is configured to be in an idle state in which the power from both the continuously variable transmission 7 for straight traveling and the continuously variable transmission 8 for turning is cut off.
Therefore, if the turning direction is the right side, the left traveling device 1L opposite to the turning center side is driven by the continuously variable transmission 7 for straight traveling, and the right traveling device 1R on the turning center side is used for straight traveling. The free-running state becomes free to rotate without being driven by either the continuously variable transmission 7 or the continuously variable transmission 8 for turning, and the traveling device 1R on the right side of the idle state becomes a resistance and the combine is on the right side. Drive while turning.

Next, the abnormality determination control for determining the operation abnormality of the pair of electromagnetic valves 42 and 43 in the turning operation mechanism 16 will be described based on the flowchart shown in FIG.
An abnormal operation such as an on failure that is fixed in the supply state of the forward rotation solenoid valve 42 or the reverse rotation solenoid valve 43 or an off failure that is fixed in the discharge state is detected in the current state of the turning swash plate 15 of the continuously variable transmission 8 for turning. Whether the tilt position is the forward rotation side or the reverse rotation side, whether the target tilt position of the turning swash plate 15 that is the target shift value from the current tilt position of the turning swash plate 15 is the normal rotation side or the reverse rotation side, It is configured to discriminate based on whether the previous tilt position of the turning swash plate 15 (for example, the average value of the detected values for the five most recent turnings) is the forward rotation side or the reverse rotation side from the inclination position of the swash plate 15. Yes. Then, it is determined whether or not at least one of the forward rotation solenoid valve 42 and the reverse rotation solenoid valve 43 is abnormal in operation. If it is determined as abnormal operation, the friction clutch 25 on the turning center side in the transmission state switching means A is determined. Is switched to the transmission cut-off state.

  That is, when the current turning swash plate 15 is tilted in the forward rotation direction and the target tilt position is located on the forward rotation side from the tilt position of the turning swash plate 15, the current tilt position of the turning swash plate 15 is In the case where it is not on the forward rotation side from the tilt position of the past turning swash plate 15, it is determined that the normal rotation electromagnetic valve 42 is in an off failure or the reverse rotation electromagnetic valve 43 is in an on failure, and the above-described turning operation is performed. Similarly to the case where the operation abnormality of the shift position sensor 61 is determined, the friction clutch 25 and the mesh clutch 27 on the turning center side in the transmission state switching means A are switched to the transmission cut-off state.

  In addition, when the current turning swash plate 15 is tilted in the forward rotation direction and the target tilting position is on the reverse side of the tilting position of the turning swash plate 15, the current tilting position of the turning swash plate 15 is past. If the rotation swash plate 15 is not on the reverse rotation side, it is determined that the forward rotation solenoid valve 42 is on or the reverse rotation solenoid valve 43 is off. When the current turning swash plate 15 is tilted in the reverse rotation direction and the target tilting position is on the forward rotation side from the tilting position of the turning swash plate 15, the current tilting position of the turning swash plate 15 is the past turning. When the forward swash plate 15 is not on the forward rotation side, it is determined that the forward electromagnetic valve 42 is off or the reverse electromagnetic valve 43 is on. Then, when the current turning swash plate 15 is tilted in the reverse rotation direction, and the target tilt position is on the reverse rotation side from the tilt position of the turning swash plate 15, the current tilt position of the turning swash plate 15 is the past. If it is not on the reverse side of the tilt position of the turning swash plate 15, it is determined that the forward solenoid valve 42 is on or the reverse solenoid valve 43 is off.

[Second Embodiment]
Hereinafter, when the control valve spool in the hydraulic control unit of the turning operation mechanism is moved to the neutral position, the turning control device for a work vehicle according to the present invention has a state in which each of the pair of output ports is connected to the discharge port. The case where it comprises is demonstrated based on drawing.
In addition, about the thing comprised similarly to the said 1st Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and description is abbreviate | omitted.

  In the neutral position as shown in FIG. 9, the control valve 36 is configured such that each of the pair of output ports OP1 and OP2 is connected to the discharge port DP, and the transmission hydraulic cylinder 17 is neutral. Return to the position.

  A process for controlling the operation of the turning operation mechanism 16 when the turning continuously variable transmission 8 is shifted will be described. For example, when the continuously variable transmission 8 for turning is shifted in the forward acceleration direction in accordance with the operation of the turning lever 56, the spool 37 in the control valve 36 is moved to the forward output position. Specifically, a pulse current that repeatedly turns on and off is supplied to the solenoid 47 in the solenoid valve 42 for pilot pressure control with respect to the pressure operation unit 40 for forward rotation, and the duty ratio is set. Change and adjust to a larger value than the value. As a result, the spool 37 is operated to move against the biasing force of the spring 39 by the electromagnetic force, and moves to the forward output position. When shifting the continuously variable transmission 8 for turning in the reverse speed increasing direction, the spool 37 in the control valve 36 is moved to the reverse output position. At this time, the pilot pressure applied to the pressure operating unit 41 for reverse rotation is operated. The control solenoid valve 43 is similarly controlled.

  When the output rotational speed of the continuously variable transmission 8 for turning reaches the target rotational speed by the speed increasing operation, the spool 37 is moved to the forward holding position. That is, the duty ratio of the pulse current for the solenoid 47 is changed and adjusted so that the holding duty ratio is smaller than the set value. As a result, the electromagnetic force of the solenoid 47 and the biasing force of the spring 39 are balanced, and the spool 37 is held at that position. As a result, the shift hydraulic cylinder 17 maintains the shift position at that time. Note that the same processing is performed for the operation at the forward holding position even when the holding is performed at the backward holding position.

  When the continuously variable transmission 8 for turning is returned to the neutral position, the solenoids 47 and 48 for the pilot pressure control solenoid valves 42 and 43 are switched to the non-energized state, respectively, and the spool 37 is moved to the springs 38 and 39. It is returned to the neutral position by the biasing force. In this neutral position, the hydraulic oil chambers 17A and 17B of the transmission hydraulic cylinder 17 are both in an oil drained state, and the transmission hydraulic cylinder 17 has the urging force of the springs 17a and 17b and the continuously variable transmission for turning. The swash plate 15 for 8 straight travels back to the neutral position by the neutral restoring force.

The abnormality determination control for determining the abnormal operation of the pair of electromagnetic valves 42 and 43 in the turning operation mechanism 50 will be described based on the flowchart shown in FIG.
An abnormal operation such as an on failure that is fixed in the supply state of the forward rotation solenoid valve 42 or the reverse rotation solenoid valve 43 or an off failure that is fixed in the discharge state is detected in the current state of the turning swash plate 15 of the continuously variable transmission 8 for turning. Whether the tilt position is the forward rotation side or the reverse rotation side, whether the target tilt position of the turning swash plate 15 that is the target shift value from the current tilt position of the turning swash plate 15 is the normal rotation side or the reverse rotation side, It is configured to discriminate based on whether the previous tilt position of the turning swash plate 15 (for example, the average value of the detected values for the five most recent turnings) is the forward rotation side or the reverse rotation side from the inclination position of the swash plate 15. Yes. Then, when one of the forward rotation solenoid valve 42 and the reverse rotation solenoid valve 43 is on-failure and the other is off-failure, it is determined that the operation is abnormal, and the transmission state switching means A has a turning center side. The friction clutch 25 is configured to be switched to the transmission cut-off state.

That is, when the current turning swash plate 15 is tilted in the forward rotation direction and the target tilting position is on the reverse side of the tilting position of the turning swash plate 15, the current tilting position of the turning swash plate 15 is past. In the case where the rotation swash plate 15 is not on the reverse rotation side, it is determined that the forward rotation solenoid valve 42 is on and the reverse rotation solenoid valve 43 is off, and the rotation shift position sensor 61 As in the case of determining the abnormal operation, the friction clutch 25 and the meshing clutch 27 on the turning center side in the transmission state switching means A are switched to the transmission cutoff state.
In addition, when the current turning swash plate 15 is tilted in the reverse rotation direction and the target tilting position is on the forward rotation side from the tilting position of the turning swash plate 15, the current tilting position of the turning swash plate 15 is past. If the forward swash plate 15 is not on the forward rotation side, it is determined that the forward electromagnetic valve 42 is in an off-failure state and the reverse rotation electromagnetic valve 43 is in an on-failure state. .

[Another embodiment]
(1) In the above embodiment, the control valve is configured as a hydraulic pilot operation type in which the spool is moved by the pilot hydraulic pressure, and the working fluid is provided in the forward pressure operation portion and the reverse pressure operation portion. However, it is not limited to supplying hydraulic oil, but may be operated using other fluids such as those operated by air pressure. The spool is not limited to the one used, and the spool may be moved by electromagnetic force using a solenoid or the like.

(2) In the above embodiment, the amount of movement of the turning lever is detected by a potentiometer, and the turning continuously variable transmission is operated steplessly as the turning lever is operated. Not only in such a configuration, for example, a command to detect the displacement of the amount of movement of the turning lever step by step with a plurality of switches, or to change the turning radius depending on the time of pressing the turn command switch. You may implement in various forms, such as a structure to do.

(3) In the above embodiment, the control valve is applied to a speed change operation device that performs a speed change operation on a continuously variable transmission for turning, but the control valve is a double-action type controlled object, For example, as long as the fluid pressure cylinder or the like is switched and controlled, the present invention can be applied to any device without being limited to the speed change operation device.

(4) In the above embodiment, the combine is exemplified as the vehicle provided with the speed change operation device. However, the combine is not limited to the combine, and may be a tractor or other farm work machine or a construction work vehicle.

Overall side view of the combine in the first embodiment Schematic configuration diagram showing the transmission structure in the first embodiment Control block diagram in the first embodiment The figure which shows the structure of the hydraulic control unit in 1st Embodiment. The figure which shows the relationship between the transmission position and transmission output in 1st Embodiment. Flowchart of control operation in the first embodiment The figure which shows the relationship between the operation position of the turning lever in 1st Embodiment, and a speed ratio. Flowchart of control operation in the first embodiment The figure which shows the structure of the hydraulic control unit in 2nd Embodiment. Flowchart of control operation in the second embodiment

Explanation of symbols

1L Left side traveling device 1R Right side traveling device 7 Continuously variable continuously variable transmission 8 Continuously variable continuously variable transmission 14 Main shift lever (transmission operation tool)
15 Swash plate (object to be operated)
16, 50 Turning operation mechanism (transmission operation means)
17 Hydraulic cylinder for shifting (fluid pressure cylinder)
17A Hydraulic oil chamber for forward operation (fluid chamber for forward operation)
17B Hydraulic oil chamber for reverse operation (fluid chamber for reverse operation)
25 Friction clutch (clutch)
37 Spool 38, 39 Coil spring (biasing means)
40 Hydraulic operation part 41 for forward rotation Hydraulic operation part 42 for reverse rotation Electromagnetic valve 43 for forward rotation Electromagnetic valve 57 for reverse rotation Swivel lever sensor (swing command means)
61 Shift position sensor (shift position detection means)
A Transmission state switching means DP Discharge port IP Input port OP1 Forward output port OP2 Reverse output port VU Hydraulic control unit (fluid pressure control mechanism)

Claims (5)

The transmission output of the straight-line continuously variable transmission is transmitted to each of the pair of left and right traveling devices, the transmission output of the continuously variable continuously variable transmission is transmitted to the right-side traveling device, and A transmission state for turning left that transmits the shift output of the step transmission to the left traveling device, and a continuously variable transmission for transmitting the transmission output of the continuously variable continuously variable transmission to the left traveling device Transmission state switching means that can be switched to a right-turning transmission state that transmits a shift output of
A speed change operating means for speed changing the operated body for speed change of the continuously variable transmission for turning;
Shift position detecting means for detecting a shift position of the operated body;
A manually operated shift operation tool for shifting the continuously variable continuously variable transmission by manual operation;
Turn command means for commanding straight, right turn, and left turn;
Control means for controlling the operation of the transmission state switching means and the speed change operation means,
The control means is
When the rectilinear instruction is commanded by the turning command means, the transmission state switching means is switched to the linear transmission state, and the continuously variable transmission for turning is the same as or substantially the same as the continuously variable continuously variable transmission. Controlling the operation of the speed change operation means so as to be a speed,
When a right turn is commanded by the turn command means, the transmission state switching means is switched to the right turn transmission state so that the continuously variable transmission for turning has a target speed for turning. When the operation of the speed change operation means is controlled and the left turn is commanded by the turn command means, the transmission state switching means is switched to the left turn transmission state, and the continuously variable transmission for turning turns. A work vehicle turning control device configured to control the operation of the speed change operation means so as to achieve a target speed for a vehicle,
When the control means determines whether or not the shift position detecting means is abnormal in operation, and determines that the shift position detecting means is abnormal in operation, when the right turn is commanded by the turn command means, the right turn In the turning transmission state, the transmission state switching means is switched to the right turning transmission cut-off state for cutting off the shifting power transmitted from the turning continuously variable transmission to the right traveling device, and the turning command means In the state in which the left turn is commanded in the left turn transmission cut-off state in which the shift power transmitted from the turning continuously variable transmission to the left travel device is cut off in the left turn transmission state. A turning control device for a work vehicle, wherein the transmission state switching means is configured to switch the transmission state switching means. The transmission output of the straight-line continuously variable transmission is transmitted to each of the pair of left and right traveling devices, the transmission output of the continuously variable continuously variable transmission is transmitted to the right-side traveling device, and A transmission state for turning left that transmits the shift output of the step transmission to the left traveling device, and a continuously variable transmission for transmitting the transmission output of the continuously variable continuously variable transmission to the left traveling device Transmission state switching means that can be switched to a right-turning transmission state that transmits a shift output of
A speed change operating means for speed changing the operated body for speed change of the continuously variable transmission for turning;
Shift position detecting means for detecting a shift position of the operated body;
A manually operated shift operation tool for shifting the continuously variable continuously variable transmission by manual operation;
Turn command means for commanding straight, right turn, and left turn;
Control means for controlling the operation of the transmission state switching means and the speed change operation means,
The control means is
When the rectilinear instruction is commanded by the turning command means, the transmission state switching means is switched to the linear transmission state, and the continuously variable transmission for turning is the same as or substantially the same as the continuously variable continuously variable transmission. Controlling the operation of the speed change operation means so as to be a speed,
When a right turn is commanded by the turn command means, the transmission state switching means is switched to the right turn transmission state so that the continuously variable transmission for turning has a target speed for turning. When the operation of the speed change operation means is controlled and the left turn is commanded by the turn command means, the transmission state switching means is switched to the left turn transmission state, and the continuously variable transmission for turning turns. A work vehicle turning control device configured to control the operation of the speed change operation means so as to achieve a target speed for a vehicle,
The control means determines whether or not the speed change operation means is abnormal in operation, and if it is determined that the operation is abnormal, when the right turn is commanded by the turn command means, the right turn In the transmission state, the transmission state switching means is switched to the right turning transmission cutoff state that cuts off the transmission between the turning continuously variable transmission and the right traveling device, and the turning command means In the state in which the left turn is commanded, in the left turn transmission state, the transmission state is changed to the left turn transmission cut-off state in which the shift power transmitted from the turning continuously variable transmission to the left traveling device is cut off. A work vehicle turning control device configured to switch a switching means. A fluid in which the speed change operation means switches the operation fluid supply / discharge state with respect to the fluid pressure cylinder and a double acting fluid pressure cylinder capable of operating the object to be operated in a forward direction and a reverse direction from a neutral position. And a pressure control mechanism,
The fluid pressure control mechanism is
A spool that is urged to return to the neutral position by the urging means, and that can be moved to a forward output position that moves forward from the neutral position and a reverse output position that moves backward from the neutral position. And a forward pressure operating part to which the working fluid is supplied to move the spool in the forward direction, and a reverse pressure operating part to be supplied with the working fluid to move the spool in the reverse direction. And a pair of solenoid valves that can be switched between a supply state for supplying the working fluid to each of the forward pressure operation unit and the reverse pressure operation unit and a discharge state for discharging the working fluid. ,
And, when the spool is in the forward direction output position, one of the pair of output ports connected to the fluid chamber for forward operation of the fluid pressure cylinder is connected to the input port, and The reverse output port connected to the fluid chamber for reverse operation of the fluid pressure cylinder is connected to the discharge port,
When the spool is in the reverse direction output position, one of the pair of output ports connected to the fluid chamber for forward operation of the fluid pressure cylinder is connected to the discharge port, and the fluid The reverse output port connected to the fluid chamber for reverse operation of the pressure cylinder is connected to the input port,
When the spool moves to the neutral position, each of the pair of output ports is configured not to be connected to either the input port or the discharge port,
The control means is
It is determined whether or not at least one of the pair of solenoid valves is abnormal in operation, and when it is determined as abnormal in operation, the right turn is performed in a state where the right turn is commanded by the turn command means. In the transmission state, the transmission state switching means is switched to the right turning transmission cutoff state that cuts off the transmission power transmitted from the turning continuously variable transmission to the right traveling device, and the turning command means When the left turn is commanded, the transmission to the left turn transmission cut-off state in which the shift power transmitted from the turning continuously variable transmission to the left travel device is cut off in the left turn transmission state. The turning control device for a work vehicle according to claim 2, wherein the turning control device is configured to switch the state switching means. A fluid in which the speed change operation means switches the operation fluid supply / discharge state with respect to the fluid pressure cylinder and a double acting fluid pressure cylinder capable of operating the object to be operated in a forward direction and a reverse direction from a neutral position. And a pressure control mechanism,
The fluid pressure control mechanism is
A spool that is urged to return to the neutral position by the urging means, and that can be moved to a forward output position that moves forward from the neutral position and a reverse output position that moves backward from the neutral position. And a forward pressure operating part to which the working fluid is supplied to move the spool in the forward direction, and a reverse pressure operating part to be supplied with the working fluid to move the spool in the reverse direction. And a pair of solenoid valves that can be switched between a supply state for supplying the working fluid to each of the forward pressure operation unit and the reverse pressure operation unit and a discharge state for discharging the working fluid. ,
And when the spool moves to the forward output position, one of the pair of output ports connected to the fluid chamber for forward operation of the fluid pressure cylinder is connected to the input port, and The reverse output port connected to the fluid chamber for reverse operation of the fluid pressure cylinder is connected to the discharge port,
When the spool moves to the reverse output position, one of the pair of output ports connected to the fluid chamber for forward operation of the fluid pressure cylinder is connected to the discharge port, and The reverse output port connected to the fluid chamber for reverse operation of the fluid pressure cylinder is connected to the input port,
When the spool moves to the neutral position, each of the pair of output ports is configured to be connected to the discharge port,
The control means is
If one of the pair of solenoid valves is an on-failure that is fixed in the supply state and the other is an off-failure that is fixed in the discharged state, it is determined that the operation is abnormal, and the turning command means In a state where a right turn is commanded, a right turning transmission cut-off state that cuts off the transmission transmitted from the turning continuously variable transmission to the right traveling device in the right turning transmission state. In the state in which the transmission state switching means is switched and the left turn command is instructed by the turn command means, the transmission is transmitted from the continuously variable transmission for turning to the left travel apparatus in the left turn transmission state. 3. The turning control device for a work vehicle according to claim 2, wherein the transmission state switching means is switched to a left turning transmission cut-off state that cuts off the speed change power. A turn command means is provided that is movable between a straight command position that commands straight travel and a turn command position that commands turning travel, and that can be moved and operated over the entire range of a predetermined operation region at the turn command position.
The turn command means is configured to instruct a lower speed as the target speed for the turn, as the amount of movement in the direction away from the straight drive command position in the turn command area increases. The turning control device for a work vehicle according to any one of the above.

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