JP2010202028A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To forcibly stop an engine of a working vehicle in the event of a certain error to provide increased driving stability and to enable the engine to be forcibly stopped regardless of the loaded condition of the engine, the working vehicle including the engine having a fuel stop solenoid, an electric speed-change actuator for changing the speed of an HST (HydroStatic Transmission), an electric motor for right and left turns, an electric actuator for a working clutch, and a control unit. <P>SOLUTION: When executing fail control to forcibly stop the engine, the control unit of the working vehicle determines that the engine is in a condition of high load if the vehicle is traveling forward according to a signal from a transmission actuation side sensor or a transmission output side sensor and if a working unit is driven according to a signal from a working clutch operation side sensor or a working clutch actuation side sensor. A predetermined period of time after the electric actuator for the working clutch is actuated in such a way to shut off power to a working clutch mechanism, the fuel stop valve is powered to forcibly put the engine into a state in which output is stopped. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, a pair of left and right differential mechanisms that synthesize the rotational power from the HST and the rotational power from the pair of left and right turning electric motors and output them to the pair of left and right traveling devices are inserted in the traveling system transmission path. In addition, a work clutch mechanism is inserted in the work machine system transmission path, and a shift clutch electric actuator for operating the output adjustment member of the HST, the pair of turning electric motors, and a work clutch electric for switching the transmission state of the work clutch mechanism The present invention relates to a work vehicle such as a snowplow configured such that an actuator is controlled by a control device.

  A pair of left and right differential mechanisms for synthesizing the rotational power from the HST and the rotational power from the pair of left and right electric motors for output to the traveling system transmission path and outputting them to the pair of left and right traveling devices and the work machine system A work clutch mechanism is inserted in the transmission path, and the shift electric actuator for operating the output adjustment member of the HST, the pair of swing electric motors, and the work clutch electric actuator for switching the transmission state of the work clutch mechanism are control devices. There has been proposed a work vehicle that takes the form of a snowplow that is configured to be operated and controlled by (see, for example, Patent Document 1 below).

  Specifically, the working vehicle includes an engine, a pair of left and right traveling devices, an HST that operatively inputs rotational power from the engine, a pair of left and right electric motors for turning, and the traveling rotational power from the HST and the correspondence. Actuating a pair of left and right differential mechanisms for synthesizing and outputting the turning rotational power from the turning electric motor to the corresponding traveling device, a manipulating speed change operation member, and the HST output adjustment member An electric actuator for shifting, a shift operation side sensor for detecting an operation state of the shift operation member, a shift operation side sensor for detecting an operation state of the output adjustment member, and a shift output side for detecting the output state of the HST A pair of left and right turning operation members that can be manually operated, a pair of left and right turning operation side sensors that detect an operation state of the pair of turning operation members, A pair of left and right turning output side sensors for detecting the output state of the turning electric motor, a working clutch mechanism inserted in a working system transmission path from the engine to the working portion, and a manually operable working clutch operating member, A work clutch operation side sensor for detecting the operation state of the work clutch operation member, a work clutch electric actuator for switching the transmission state of the work clutch mechanism, and a work clutch operation side sensor for detecting the transmission state of the work clutch mechanism And the control device, while controlling the operation of the electric actuator for the work clutch so that the transmission state of the work clutch mechanism is switched according to the operation state of the work clutch operation member, The shift power is changed so that the output state of the HST changes according to the operation state of the shift operation member. The actuator is controlled so that the output state of the pair of left and right turning electric motors is controlled according to the operation state of the pair of left and right turning operation members. Has been.

Since the working vehicle does not need to be operatively connected with a mechanical link structure between the operation member and the corresponding actuator, the degree of freedom in design can be improved, but there is an error in the electrical system and the like. If this occurs, there may occur a situation where the actuator becomes in an uncontrollable state.
In particular, when a serious error among various errors occurs, it is desirable to force the engine to be in a drive stop state from the viewpoint of traveling safety.

By the way, the engine has a fuel stop solenoid inserted in the fuel supply line, and when the fuel stop solenoid is energized, the engine in which the fuel supply line is cut off is put in an output stop state. There are things.
In this type of engine, when the engine is in a high load state, the flow of fuel in the fuel supply line becomes stronger than the cutoff force of the fuel stop solenoid, and the fuel stop solenoid is energized. There may be a situation where the fuel supply line cannot be shut off.

JP 2008-055924 A

  The present invention has been made in view of the prior art, and includes an engine having a fuel stop solenoid that cuts off a fuel supply line when energized, an HST that operatively inputs rotational power from the engine, and a pair of left and right turnings. An electric motor, a pair of left and right differential mechanisms for synthesizing rotational power from the HST and the pair of turning electric motors, a work clutch mechanism inserted in a transmission path from the engine to a working unit, and the HST A predetermined error in a work vehicle comprising: a speed-changing electric actuator for actuating an output adjusting member; a control device for controlling operation of the pair of electric motors for turning and the work clutch electric actuator for actuating the work clutch mechanism; At the time of occurrence, the engine is forcibly stopped to increase the driving safety and And an object thereof is to provide a reliably perform working vehicle forced output stop of the engine regardless of the load state of the engine.

  In order to achieve the above object, the present invention has a fuel stop solenoid inserted in a fuel supply line, and is configured such that the fuel supply is cut off by energization of the fuel stop solenoid and the output is stopped. An engine, a pair of left and right traveling devices, an HST that operatively inputs rotational power from the engine, a pair of left and right turning electric motors, a running rotational power from the HST and the corresponding turning electric motor A pair of left and right differential mechanisms for synthesizing and outputting the turning rotational power of the two to the corresponding traveling device, a manually operated speed change operation member, and a speed change electric actuator for operating the HST output adjustment member, A speed change operation side sensor for detecting an operation state of the speed change operation member, a speed change operation side sensor for detecting an operation state of the output adjustment member, and the output of the HST A shift output side sensor for detecting a state, a pair of left and right turning operation members capable of being manually operated, a pair of left and right turning operation side sensors for detecting an operation state of the pair of turning operation members, and the pair of left and right turning electric motors A pair of left and right turning output side sensors for detecting the output state of the motor, a work clutch mechanism inserted in a work system transmission path from the engine to the work part, a work clutch operation member capable of being manually operated, and the work clutch A work clutch operation side sensor that detects an operation state of the operation member, a work clutch electric actuator that switches a transmission state of the work clutch mechanism, a work clutch operation side sensor that detects a transmission state of the work clutch mechanism, and the work For the working clutch, the transmission state of the working clutch mechanism is switched according to the operating state of the clutch operating member. While controlling the operation of the dynamic actuator, the shift operation is performed so that the actual HST output based on the detection signal from the shift operation side sensor or the shift output side sensor matches the HST target output based on the detection signal from the shift operation side sensor. Left and right turning electric motors based on detection signals from the pair of left and right turning operation side sensors. And a control device that performs normal control for controlling the operation of the pair of left and right electric motors for turning so as to coincide with a target output, wherein the control device performs the normal control during the execution of the normal control. Although the control signal is output to the electric motor for shifting according to the change of the detection signal from the shift operation side sensor, it is predetermined. When a first error that does not cause a change in the detection signal from the shift operation side sensor occurs in time, the fuel stop solenoid is energized to perform fail control for forcibly stopping the engine from outputting. When the fail control is executed, the control device is configured such that the vehicle is traveling forward based on a signal from the shift operation side sensor or the shift output side sensor and the work clutch operation side sensor or the work Based on the signal from the clutch operating side sensor, it is determined that the engine is in a high engine load state when the working unit is being driven, and the engine clutch is in a power shut-off state in the engine high load condition. The fuel stop valve is energized after a predetermined time has elapsed since the operation of the electric actuator for the work clutch. Jin providing forced working vehicle to output stop state.

  Preferably, the control device performs the fail control when the first error or the second error in which no detection signal is input from both the shift operation side sensor and the shift output side sensor occurs within a predetermined time. Configured to perform. In this case, when executing the fail control, the control device presumes that the vehicle is traveling forward if there is no detection signal input from both the shift operation side sensor and the shift output side sensor. Can be configured as follows.

  Preferably, the control device is based on an HST target output based on the first error, the second error, or a detection signal from the shift operation side sensor and a detection signal from the shift operation side sensor or the shift output side sensor. The fail control may be executed when any of the third errors exceeding the predetermined range occurs even when the displacement from the HST actual output has passed a predetermined time.

  Preferably, the control device is configured to execute the fail control when any of the first to third errors or a fourth error in which a detection signal from the shift operation side sensor exceeds a predetermined range occurs. Can be done.

Preferably, the control device includes a turning electric motor target output based on the first to fourth errors or a detection signal from the turning operation side sensor and a turning electric motor actual based on the detection signal from the turning output side sensor. The fail control may be executed when any of the fifth errors exceeding a predetermined range occurs even if the displacement with the output has passed a predetermined time.
In this case, the control device sets the work clutch electric actuator so that the work clutch mechanism is in a power shut-off state when the engine is in a high load state when the fail control based on the first to fourth errors is performed. Energizing the fuel stop valve after a lapse of a predetermined time from the operation to forcibly stop the output of the engine, and in the case of an engine high load state when performing the fail control based on the fifth error, The fuel stop valve is operated after a predetermined time has elapsed since the work clutch electric actuator is operated so that the work clutch mechanism is in a power cut-off state and / or the shift electric actuator is operated so that the HST is in a neutral state. The engine is configured to forcibly stop the output by energizing the .

In the working vehicle according to the present invention, when a predetermined error occurs during the execution of the normal control, the control device performs a fail control that energizes the fuel stop solenoid to forcibly stop the output of the engine. It is configured. Therefore, traveling safety can be improved.
Further, in the work vehicle according to the present invention, the control device operates the electric actuator for the work clutch so that the work clutch mechanism is in a power cut-off state when the engine is in a high load state when the fail control is performed. And / or after the lapse of a predetermined time since the shifting electric actuator is operated so that the HST is in a neutral state, the fuel stop valve is energized to forcibly stop the output of the engine. Yes. Therefore, regardless of the load state of the engine, the engine can be reliably stopped when a predetermined error occurs.

FIG. 1 is a schematic side view of a working vehicle according to an embodiment of the present invention. FIG. 2 is a schematic plan view of the working vehicle shown in FIG. FIG. 3 is a transmission schematic diagram of the working vehicle shown in FIGS. 1 and 2. FIG. 4 is a system block diagram of the control device in the working vehicle shown in FIGS. FIG. 5 is a part of a flowchart of a control program stored in the control device. FIG. 6 is the remaining part of the flowchart.

Hereinafter, an embodiment of a working vehicle according to the present invention will be described with reference to the accompanying drawings.
1 to 3 are a schematic side view, a schematic plan view, and a transmission schematic diagram, respectively, of the working vehicle 1 according to the present embodiment.

As shown in FIGS. 1 and 2, the working vehicle 1 according to the present embodiment is in the form of a walking snowplow.
Specifically, the working vehicle 1 includes a body frame 10, an engine 20 supported by the body frame 10, a pair of left and right traveling units 30L and 30R, a front side of the body frame 10, and the engine. A working unit 40 driven by the rotational power from 20, a transmission 50 inserted in a transmission path from the engine 20 to the traveling units 30L, 30R, and an operation disposed on the rear side of the body frame 10 Part 70.

  In the working vehicle 1 in the form of the snow remover, the working unit 40 is a snow removing unit that collects and discharges snow on the traveling road surface.

  Specifically, as shown in FIGS. 1 to 3, the working unit 40 includes a scraping auger 41 disposed on the front side of the machine body frame 10 and an auger housing 42 surrounding the scraping auger 41. And a blower housing 43 extending rearward in communication with the auger housing 42, a blower 44 built in the blower housing 43, and a shooter 45 disposed above the blower 44.

The scraping auger 41 is rotationally driven around the rotational axis along the body width direction by the rotational power transmitted from the engine 20, and collects snow on the travel path in the center of the body width direction to collect the snow inside the blower housing 43. It is configured to send toward the blower 44.
Specifically, the auger auger 41 is operatively connected to the engine 20 and is supported by the auger drive shaft 41a supported by the auger housing 42 so as to be rotatable about the axis line along the body width direction. And a protrusion 41b provided in a spiral shape on the outer peripheral surface of the drive shaft 41a.

The auger housing 42 surrounds the raking auger 41 with the front lower part opened.
The blower housing 43 accommodates the blower 44 in a state where the base end side is connected to the body frame 10 and the distal end side is connected to the auger housing 42.

  The blower 44 is driven by the rotational power transmitted from the engine 20, and is configured to jump the snow transported from the scraping auger 41 into the blower housing 43 toward the shooter 45. .

The shooter 45 acts as a discharge guide for snow blown by the blower 44.
Specifically, the shooter 45 is a cylindrical member whose base end is connected to the blower housing 43.
In the present embodiment, the shooter 45 is connected to the upper surface of the blower housing 43 so as to be rotatable about a rotation axis along a substantially vertical direction, and in a substantially horizontal direction with respect to the proximal end member. And a tip end side member connected to be rotatable about a rotation axis along the direction of the axis, and a discharge direction and a discharge angle of the snow discharged through the shooter 45 can be adjusted.

As shown in FIG. 3, the working unit 40 receives rotational power from the engine 20 via a work machine transmission mechanism 100.
Specifically, as shown in FIGS. 1 and 2, the engine 20 includes an engine body 21 supported by the body frame 10 behind the working unit 40, and an engine output projecting forward from the engine body 21. And a shaft 22.
The work machine transmission mechanism 100 operatively connects the engine output shaft 22 and the input shaft 40a of the working unit 40.

In the present embodiment, the work machine transmission mechanism 100 is a pulley / belt transmission mechanism as shown in FIGS.
Specifically, as shown in FIGS. 1 and 3, the work machine transmission mechanism 100 includes a work machine drive pulley 101 supported on the engine output shaft 22 so as not to rotate relative to the engine output shaft 22, and an input of the work machine 40. It has a work machine driven pulley 102 supported by a shaft 40a so as not to rotate relative to the shaft 40a, and a work machine endless belt 103 wound around the drive and driven pulleys 101 and 102.

  In the present embodiment, as shown in FIG. 1, the engine output shaft 22 is supported by a bracket 11 connected to the body frame 10 at an intermediate portion via a bearing (not shown), The work machine drive pulley 101 is supported by a portion of the engine output shaft 22 that is located on the front side of the bracket 11.

Furthermore, as shown in FIGS. 1 and 3, the work vehicle 1 according to the present embodiment includes a work clutch mechanism 105 that selectively engages and disengages the transmission state of the work machine transmission mechanism 100.
The work clutch mechanism 105 is disposed, for example, between the engine output shaft 22 and the work machine system drive side pulley 101, and the work machine system drive side pulley 101 is rotated relative to the engine output shaft 22. The clutch engaged state to be disabled and the clutch disengaged state in which the work machine drive side pulley 101 is rotatable relative to the engine output shaft 22 are configured.

The transmission 50 is supported by the body frame 10 on the rear side of the engine 20.
As shown in FIGS. 1 to 3, the transmission 50 includes a HST 510 for continuously changing the rotational power from the engine 20, a pair of left and right electric motors for turning 520 </ b> L and 520 </ b> R, a running rotational power from the HST 510, and A pair of left and right differential mechanisms 530L and 530R that synthesize and output the turning rotational power from the corresponding turning electric motors 520L and 520R to the corresponding traveling units 30L and 30R, and the differential mechanisms 503L and 530R. And a mission case 550 that accommodates.

  As shown in FIG. 3, the HST 510 includes a pump shaft 511 operatively connected to the engine 20, a hydraulic pump 512 supported by the pump shaft 511 so as not to rotate relatively, and a pair of HST lines connected to the hydraulic pump 512. Hydraulic motor 514 fluidly connected via 519, a motor shaft 513 that supports the hydraulic motor 514 in a relatively non-rotatable manner, and at least one of the hydraulic pump 512 and the hydraulic motor 514 that is a variable displacement type (this In the embodiment, the hydraulic pump 512 includes an output adjusting member 515 that changes the suction / discharge amount and the suction / discharge direction of a variable volume member.

  In the present embodiment, the HST 510 is supported on the rear end surface of the transmission case 550, and the pump shaft 511 includes a traveling system transmission shaft 115 and a traveling system first transmission mechanism that extend forward from the transmission case 550. The engine output shaft 22 is operatively connected through 110.

Specifically, the transmission case 115 that has a rear end connected to the pump shaft 511 so as not to rotate relatively around the axis and a front end extended forward from the transmission case 550 is supported by the transmission case 550. Has been.
As shown in FIG. 1, the traveling system transmission shaft 115 has a front end supported by the bracket 11.

The traveling system first transmission mechanism 110 operatively connects the engine output shaft 22 and the traveling system transmission shaft 115.
In the present embodiment, as shown in FIGS. 1 and 3, the traveling system first transmission mechanism 110 is a pulley / belt transmission mechanism.

Specifically, as shown in FIGS. 1 and 3, the traveling system first transmission mechanism 110 includes a traveling system drive pulley 111 that is supported on the engine output shaft 22 so as not to be relatively rotatable, and the traveling system transmission shaft 115. And a traveling system driven pulley 112 supported so as not to rotate relative to the driving system, and a traveling system endless belt 113 wound around the driving and driven pulleys 111 and 112.
In the present embodiment, the traveling system drive pulley 111 is supported by a portion of the engine output shaft 22 located on the rear side of the bracket 11 as shown in FIG.

In the present embodiment, the hydraulic pump 512 and the hydraulic motor 514 are of an axial piston type.
Therefore, the output adjusting member 515 is movable to change the suction / discharge amount and the suction / discharge direction of the variable volume member (the hydraulic pump 512 in the present embodiment) according to the tilt position around the swing axis. A swash plate (not shown) and a control shaft 515a (see FIG. 2) connected to the movable swash plate so that the movable swash plate tilts around the swing shaft in response to rotation about its own axis. ).
Note that reference numeral 515b in FIG. 2 denotes a control arm supported on the control shaft 515a so as not to be relatively rotatable.

The output adjusting member 515 operates as follows.
When the movable swash plate is positioned at a neutral position around the swing axis, the hydraulic pump 512 does not discharge pressure oil even when the pump shaft 511 is driven to rotate about the axis, and therefore the hydraulic motor 514 And the HST neutral state where the rotation of the motor shaft 513 is stopped appears.

When the movable swash plate is tilted from the neutral position to one side around the swing axis, the hydraulic pump 512 is set to the tilt angle of the movable swash plate in a direction corresponding to the tilt direction of the movable swash plate. A corresponding amount of pressure oil is discharged, so that the hydraulic motor 514 and the motor shaft 513 correspond to the tilt angle of the movable swash plate in the first rotation direction corresponding to the tilt direction of the movable swash plate. It rotates at the rotation speed.
That is, when the movable swash plate is tilted from the neutral position to one side around the swing shaft, the motor shaft 513 moves in one of the vehicle forward direction and the vehicle reverse direction (for example, the forward direction). Rotates at a rotation speed according to the tilt angle.

When the movable swash plate is tilted from the neutral position to the other side around the swing shaft, the hydraulic pump 512 is set to the tilt angle of the movable swash plate in a direction corresponding to the tilt direction of the movable swash plate. A corresponding amount of pressure oil is discharged, whereby the hydraulic motor 514 and the motor shaft 513 correspond to the tilt angle of the movable swash plate in the second rotation direction according to the tilt direction of the movable swash plate. It rotates at the rotation speed.
That is, when the movable swash plate is tilted from the neutral position to the other side around the swinging shaft, the motor shaft 513 is moved in the other of the vehicle forward direction and the vehicle reverse direction (for example, the reverse direction). Rotates at a rotation speed according to the tilt angle.

Next, the pair of left and right differential mechanisms 530L and 530R will be described.
The pair of left and right differential mechanisms 530L and 530R are symmetrical with respect to each other with respect to the center plane in the longitudinal direction of the working vehicle 1.
Accordingly, in the drawing, the same reference numerals with the last letters L and R are used for the components of the left differential mechanism 530L and the right differential mechanism 530R, respectively.

  The left differential mechanism 530L corresponds to a first element that operatively inputs rotational power from the HST 510 and a second element that operatively inputs rotational power from the corresponding left turning electric motor 520L. And a third element that outputs rotational power to the left traveling unit 30L.

  Similarly, the right differential mechanism 530R includes a first element that operatively inputs rotational power from the HST 510, and a second element that operatively inputs rotational power from the corresponding right turning electric motor 520R. And a third element that outputs rotational power to the corresponding right traveling unit 30R.

  In the work vehicle 1 having such a configuration, the rotational power input from the electric motors 520L and 520R to the second elements of the corresponding differential mechanisms 530L and 530R is used as the braking rotational power for turning. Works. That is, by inputting rotational power from the left and right turning electric motors 520L, 520R to the corresponding second elements of the differential mechanisms 530L, 530R, the first pair of left and right differential mechanisms 530L, 530R A rotational speed difference is generated between the three elements, and thereby the left or right turn of the working vehicle 1 appears.

  In the present embodiment, as shown in FIG. 3, the sun gear 531L (531R), the ring gear 535L (535R) and the carrier 534L (534R) act as the first to third elements, respectively.

  That is, the differential mechanism 30L (30R) revolves around the sun gear 531L (531R) operatively connected to the motor shaft 513 of the HST 510 and the sun gear 531L (531R). The planetary gear 532L (532R) meshing with the 531R) and the planetary gear 532L (532R) so as to be relatively rotatable and revolving around the sun gear 531L (531R) according to the revolution of the planetary gear 532L (532R). A carrier 534L (534R) and the ring gear 535L (535R) having internal teeth meshing with the planetary gear 532L (532R) and operatively connected to the corresponding electric motor 520L (520R) corresponding to the outer peripheral surface. I have.

  In the present embodiment, the sun gear 531L (531R) is operatively connected to the motor shaft 513 via the traveling system second transmission mechanism 120 housed in the mission case 550.

  Specifically, as shown in FIG. 3, the traveling system second transmission mechanism 120 includes a first transmission shaft 121 accommodated in the transmission case 550 along the body width direction, and both end portions along the body width direction. A second transmission shaft 125 in which the sun gears of the pair of left and right differential mechanisms are supported so as not to rotate relative to each other; an upstream transmission mechanism 122 that operatively connects the motor shaft 513 and the first transmission shaft 121; And a downstream transmission mechanism 126 that operatively connects the first and second transmission shafts 121 and 125.

In the present embodiment, the motor shaft 513 is along the vehicle longitudinal direction.
Therefore, the upstream transmission mechanism 122 is engaged with the drive side bevel gear 122a, which is supported on the end of the motor shaft 513 that is inserted into the transmission case 550 so as not to be relatively rotatable, and the drive side bevel gear 122a. And a driven bevel gear 122b supported by the first transmission shaft 121 so as not to rotate relative to the first transmission shaft 121.
The drive-side bevel gear 122a has a small diameter and the driven-side bevel gear 122b has a large diameter so that rotational power is transmitted from the motor shaft 513 to the first transmission shaft 121 at a reduced speed.

The downstream transmission mechanism 126 includes a drive-side sprocket 126a supported so as not to rotate relative to the first transmission shaft 121, a driven-side sprocket 126b supported so as not to rotate relative to the second transmission shaft 125, and the drive. A side sprocket 126a and a chain 126c wound around the driven side sprocket 126b.
The driving side sprocket 126a has a small diameter and the driven side sprocket 126b has a large diameter so that rotational power is transmitted from the first transmission shaft 121 to the second transmission shaft 125 at a reduced speed.

Preferably, a brake mechanism 130 that can selectively apply a braking force to a transmission path from the motor shaft 513 to the sun gears 531L and 531R of the pair of left and right differential mechanisms 530L and 530R is provided.
In the present embodiment, as shown in FIG. 3, the brake mechanism 130 is configured to selectively apply a braking force to the first transmission shaft 121.

In the present embodiment, the ring gear 535L (535R) is operatively connected to the output shaft 522L (522R) of the corresponding electric motor 520L (520R) for turning.
Specifically, the pair of left and right electric motors 520L and 520R for turning are respectively the electric motor main bodies 521L and 521R supported on the outer surface of the mission case 550, and the output in which the tip portion is inserted into the mission case 550. It has shafts 522L and 522R.

  A warm-up gear 523L (523R) is provided on the output shaft 522L (522R) of the turning electric motor 520L (520R) so as not to be relatively rotatable, and the ring gear of the corresponding differential mechanism 530L (530R) is provided. A gear that meshes with the warm-up gear 523L (523R) is provided on the outer peripheral surface of the 531L (531R).

The pair of left and right turning electric motors 520L and 520R are driven by electric power from the generator 25 and the battery 26 provided in the work vehicle 1.
FIG. 4 shows a system block diagram of the following control device 400 provided in the work vehicle 1.
That is, as shown in FIG. 4, the working vehicle 1 includes a generator 25 that generates electric power by the rotational power of the engine 20, and a battery 26 that stores electric power generated by the generator 25. The pair of turning electric motors 520L and 520R operate using the battery 26 (and the generator 25) as a drive source. Reference numeral 28 in FIG. 4 is a starter for starting the engine 20.

A traveling drive shaft 31L (31R) of the corresponding traveling unit 30L (30R) is connected to the carrier 534L (534R).
In the present embodiment, the traveling unit 30L (30R) has a crawler traveling device.

Specifically, as shown in FIGS. 1 to 3, the traveling unit 30 </ b> L (30 </ b> R) is connected to the carrier 534 </ b> L (534 </ b> R) of the corresponding differential mechanism 530 </ b> L (530 </ b> R) along the body width direction. The travel drive shaft 31L (31R), the drive sprocket 32L (32R) supported so as not to rotate relative to the travel drive shaft 31L (31R), and the travel drive shaft 31L (31R) are separated in the longitudinal direction of the body. A traveling driven shaft 33L (33R) disposed along the width direction of the machine body at a predetermined position, a driven sprocket 34L (34R) supported so as not to rotate relative to the traveling driven shaft 33L (33R), and the drive sprocket 32L (32R) and a crawler 35L (35R) wound around the driven sprocket 34L (34R).
Of course, the traveling unit 30L (30R) may have a wheel-type traveling device instead of the crawler-type traveling device.

As shown in FIG. 2, the pair of left and right traveling portions 30L and 30R further includes a pair of left and right track frames 38L and 38R.
The corresponding traveling drive shaft 31L (31R) can rotate about its axis via a bearing (not shown) on one side of the track frame 38L (38R) in the longitudinal direction of the vehicle body (rear side in the present embodiment). And the corresponding travel driven shaft 33L (33R) is inserted through a bearing (not shown) on the other side in the longitudinal direction of the machine body (front side in the present embodiment). Has been.

In the present embodiment, the pair of left and right traveling portions 30L and 30R can move relative to the body frame 10 around the traveling drive shafts 31L and 31R by a hydraulic cylinder device 90 provided in the work vehicle 1. It is like that.
Specifically, as shown in FIG. 2, the pair of track frames 38L and 38R are connected to each other via a connecting frame 39 at a portion near the other side in the longitudinal direction of the machine body (the front side in the present embodiment). .
The hydraulic cylinder device 90 has one end connected directly or indirectly to the body frame 10 and the other end connected to the connecting frame 39.

  As shown in FIGS. 1 and 2, the operation unit 70 changes the output state of the HST 510 and the handle frame 71 erected on the body frame 10 so as to extend rearward and upward from the body frame 10. In order to change the output states of the shift operation member 72 that can be manually operated directly or indirectly on the handle frame 71 and the pair of left and right electric motors 520L and 520R for turning independently, A pair of left and right turning operation members 73L and 73R that are directly or indirectly provided on the frame 71 and that can be manually operated are provided.

The speed change operation member 72 is preferably a neutral position where the HST 510 is set in a neutral state to stop the traveling of the work vehicle 1, a forward-side highest speed position where the vehicle speed of the work vehicle 1 is maximized on the forward side, A predetermined forward maximum working speed position that is slower than the forward maximum speed position, a reverse maximum speed position at which the vehicle speed of the working vehicle 1 is maximum on the reverse side, and a predetermined reverse maximum operating speed that is slower than the reverse maximum speed position. Each position can be locked.
The preferred embodiment can be easily realized, for example, by forming a shift gate (not shown) for guiding the speed change operation member 72 in a step shape having step portions at the respective operation positions.

In the present embodiment, as shown in FIGS. 1 and 2, the speed change operation member 72 is provided in an operation box 700 supported by the handle frame 71.
The operation box 700 is further provided with a work clutch operation member 74 for manually operating the work clutch mechanism 105.

The pair of left and right turning operation members 73L and 73R are provided on the handle frame 71 in a state of being separated from each other in the body width direction.
Specifically, the handle frame 71 has a pair of left and right support frames 710L and 710R having a lower end supported by the body frame 10 and an upper end serving as a grip.

  The pair of left and right turning operation members 73L and 73R are connected to the gripping portions of the support frames 710L and 710R corresponding to the base ends so as to be swingable around the support shaft along the body width direction, respectively. The free end portion comes into contact with and separates from the grip portion in accordance with an artificial operation.

Preferably, a return spring (not shown) is provided that urges the free end of the turning operation member 73L (73R) in a direction away from the gripping portion of the corresponding support frame 710L (710R).
In such a configuration, the turning operation is performed by bringing the turning operation member 73L (73R) close to the gripping portion of the corresponding support frame 710L (710R) against the biasing force of the return spring by an artificial operation force. The member 73L (73R) is positioned at the operating position, and the turning operation member 73L (73R) is positioned at the non-operating position by releasing the manual operation force.
In addition, the code | symbol 26a in FIG. 1 is the battery stand constructed by the said support frames 710L and 710R.

Next, the control structure of the working vehicle 1 according to the present embodiment will be described.
As shown in FIG. 4, the working vehicle 1 further includes a speed change operation side sensor 410 that detects an operation state of the speed change operation member 72, a speed change electric actuator 80 that operates the output adjustment member 515 of the HST 510, and A shift output side sensor 420 that detects the output state of the HST 510, a shift operation side sensor 425 that detects the operation state of the output adjustment member 515, and a pair of left and right that detects the operation state of the pair of turning operation members 73L and 73R. Rotation operation side sensors 430L and 430R, a pair of left and right turning output side sensors 440L and 440R for detecting the output state of the pair of left and right turning electric motors 520L and 520R, and an operation state of the work clutch operation member 74 are detected. The working clutch operating side sensor 460 to be switched and the transmission state of the working clutch mechanism 105 are switched. The working clutch electric actuator 600, the working clutch operating side sensor 470 for detecting the transmission state of the working clutch mechanism 105 directly or indirectly, the shifting electric actuator 80, the pair of turning electric actuators 520L, 520R. And a control device 400 for controlling the operation of the working clutch electric actuator 600.

The transmission electric actuator 80 and the work clutch electric actuator 600 may take various forms as long as the operation is controlled by a control signal from the control device 400.
For example, the shift electric actuator 80 and the work clutch electric actuator 600 may be an electric motor or a combination of an electromagnetic valve and a hydraulic actuator.
The shift electric actuator 80 and the work clutch electric actuator 600 operate using the battery 26 (and the generator 25) as a drive source.

  The control device 400 controls the operation of the work clutch electric actuator 600 so that the transmission state of the work clutch mechanism 105 is switched in accordance with the operation state of the work clutch operation member 74, and the shift output side sensor 420. (Or control the operation of the shift electric actuator 80 so that the HST actual output based on the detection signal of the HST operation side sensor 425 matches the HST target output based on the detection signal of the shift operation side sensor 410 and the left and right The actual output of the left and right turn electric motor based on the detection signals of the pair of turn output side sensors 440L and 440R is matched with the target output of the left and right turn electric motor based on the detection signals of the pair of left and right turn operation side sensors 430L and 430R. The left and right turning electric motors 520L and 520R are controlled to operate. It is configured to perform control.

  Specifically, the control device 400 stores a calculation unit 401 (hereinafter referred to as a CPU) including a control calculation unit that executes calculation processing based on signals input from the various sensors and the like, and stores a control program, control data, and the like. ROM, an EEPROM in which setting values are stored without being lost even when the power is turned off, and an EEPROM in which the setting values can be rewritten, a RAM that temporarily holds data generated during calculation by the calculation unit, etc. And a storage unit 402 including

The control device 400 includes, as the control data stored in the storage unit 402, shift control data regarding the HST target output according to the operation state of the shift operation member 72, and the pair of left and right turning operation members 73L and 73R. And turn control data related to the target output of the left and right turn electric motor according to the operation state.
The shift control data and the turning control data are, for example, a control conversion formula or an LUT (Look Up Table).

The shift operation side sensor 410 is, for example, a potentiometer that detects an operation position of the shift operation member 72 or a sensor that cumulatively detects an operation direction and an operation amount of the shift operation member 72.
The speed change operation side sensor 425 is connected to, for example, a potentiometer 426 that detects an operation position of the electric actuator 80 for speed change, or an operation position of the output adjustment member 515 (the control shaft 515a or the control shaft 515a. The potentiometer 427 detects the position of the control arm 515b.
The shift output side sensor 420 is, for example, a rotation sensor that detects the rotation direction and the rotation speed of any rotation member on the transmission path from the motor shaft 513 to the second transmission shaft 125.

The pair of left and right turning operation side sensors 430L and 430R, for example, cumulatively calculate the operation amount of the potentiometer sensor that detects the operation position of the pair of left and right turning operation members 73L and 73R or the turning operation members 73L and 73R. It is a sensor to detect.
The pair of left and right turning output side sensors 440L and 440R are, for example, rotation sensors that detect the rotation speed of the output shafts 522L and 522R.

The work clutch operation side sensor 460 is, for example, a potentiometer that detects the operation position of the work clutch operation member 74 or a contact switch that detects an ON / OFF signal according to the operation position of the work clutch operation member 74. .
The work clutch operating side sensor 470 is, for example, a potentiometer 471 that detects the operating position of the work clutch electric actuator 600 or the presence / absence of rotation of a transmission member from the driven side of the work clutch mechanism 105 to the work implement 40 This is a sensor 472 that detects.

  The control device 400 is configured to execute fail control for forcibly stopping the output of the work vehicle 1 by forcibly stopping the engine 20 when the following predetermined error occurs during execution of the normal control. Yes.

  That is, as described above, in the work vehicle 1 according to the present embodiment, the actuator including the speed change electric actuator 80, the pair of left and right turning electric motors 520L and 520R, and the work clutch electric actuator 600, Rather than being operatively connected to the corresponding operation members 72, 73L, 73R, 74 by a mechanical link structure, the control device 400 performs electrical operation based on the operation of the corresponding operation members 72, 73L, 73R, 74. The operation is controlled.

  In the working vehicle 1 having such a configuration, an effect that the degree of freedom in design can be improved by eliminating the need for the mechanical link structure. On the other hand, if an error occurs in the electric system, the operation member 72 is provided. , 73L, 73R, 74 even if the actuator is properly operated, the actuator can be in an uncontrollable state.

  In view of this point, the working vehicle 1 according to the present embodiment is configured such that the control device 400 performs fail control that forcibly puts the engine 20 into the output stop state when a predetermined error occurs. .

Specifically, as shown in FIG. 4, the engine 20 has a fuel stop solenoid 20a inserted in a fuel supply line. When the fuel stop solenoid 20a is energized, the fuel supply line is cut off and the engine 20 is stopped.
Accordingly, the control device 400 performs control so that the fuel stop solenoid 20a is energized when a predetermined error occurs.
The electric power applied to the fuel stop solenoid 20a is supplied from the battery 26 (or the generator 25).

The predetermined error is determined in advance from the viewpoint of traveling safety, and is stored in the storage unit 402 as error data.
Specifically, the predetermined error includes
The shift operation side sensor 425 (or the shift output side) within a predetermined time despite the fact that a control signal is output to the shift electric motor 80 according to the change of the detection signal from the shift operation side sensor 410 A first error in which no change occurs in the detection signal from the sensor 420),
A second error in which no detection signal is input from both the shift operation side sensor 425 and the shift output side sensor 420 within a predetermined time;
The displacement between the HST target output based on the detection signal from the shift operation side sensor 410 and the actual HST output based on the detection signal from the shift output side sensor 420 (or the shift operation side sensor 425) has passed a predetermined time. But the third error, which is beyond the predetermined range,
The fourth error that the detection signal from the shift operation side sensor 425 (or the shift output side sensor 420) exceeds a predetermined range, and the turning electric motor based on the detection signals from the turning operation side sensors 430L and 430R. A fifth error is included in which the displacement between the motor target output and the actual output of the turning electric motor based on the detection signals from the turning output side sensors 440L and 440R exceeds the predetermined range even after a predetermined time has elapsed.

  If any of these first to fifth errors occurs, the driving safety may be impaired. Therefore, the control device 400 applies power to the fuel stop solenoid 20a to forcibly stop the output of the engine 20. State.

Note that, in the third error, traveling safety is particularly impaired when the actual HST output over-rotates the HST target output.
Similarly, in the fifth error, the traveling safety is particularly impaired when the actual output of the turning electric motor is excessively rotated with respect to the turning electric motor target output.

If the predetermined time is set too short, an error is erroneously detected. Therefore, the predetermined time for each error can be set according to the importance of each error with respect to traveling safety.
The predetermined time in the first error may be set to, for example, 0.5 seconds based on the time required to operate the output adjustment member 515 from one side of the operable range to the other side.
Comparing the third error, which makes vehicle speed control of the work vehicle impossible, and the fifth error, which makes turn control of the work vehicle impossible, the fifth error that may cause an unexpected turn is traveling. This is important in terms of safety.
Therefore, the predetermined time in the fifth error is set shorter than the predetermined time in the third error. For example, the predetermined time in the third error may be 2 seconds, and the predetermined time in the fifth error may be 1.5 seconds.
In addition, the predetermined range in the third and fifth errors and the predetermined range in the fourth error are set to values that are not possible as the values of the HST actual output or the actual electric motor for turning.
The predetermined time and the predetermined range are stored in an EEPROM in which the set value is not lost even if the power is turned off and the set value can be rewritten, and can be changed as necessary and / or desired. Is done.

  By the way, in the embodiment in which the engine 20 is provided with the fuel stop solenoid 20a that cuts off the fuel supply by energization as in the present embodiment, the fuel stop solenoid 20a when the engine 20 is in a high load state. Even if energized, the fuel supply line may not be shut off.

  That is, when the engine 20 is in a high load state and a large amount of fuel is flowing through the fuel supply line, the fuel flow exceeds the shut-off force by the fuel stop solenoid 20a. Even if power is supplied to 20a, there may occur a situation where the engine 20 cannot be stopped.

  Therefore, in the working vehicle 1 according to the present embodiment, the control device 400 determines whether or not the engine 20 is in a high load state when executing the fail control, and the engine 20 is in a high load state. In this case, the process of energizing the fuel stop solenoid 20a is executed after a predetermined time has elapsed since the load on the engine 20 was reduced.

  Specifically, the control device 400 determines that the vehicle is traveling forward based on a signal from the shift operation side sensor 425 or the shift output side sensor 420 and the work clutch operation side sensor 460 or the work clutch operation side. Based on a signal from the sensor 470, when the working machine 20 is being driven, the engine 20 is determined to be in a high load state.

When the second error occurs, the control device 400 cannot input detection signals from both the shift operation side sensor 425 and the shift output side sensor 420, and is the vehicle traveling forward? No judgment can be made.
Therefore, the control device 400 presumes that the vehicle is traveling forward when there is no input of detection signals from both the shift operation side sensor 425 and the shift output side sensor 420 when executing the fail control. It is configured as follows.

  As a specific means for reducing the load of the engine 20, the control device 400 controls the operation of the work clutch electric actuator 600 so that the work clutch mechanism 105 is in a power cut-off state, and / or The shift electric actuator 80 is controlled to operate so that the HST 510 is in a neutral state.

Note that when an error related to the shift operation side sensor 425 or the shift output side sensor 420 has occurred, it is not possible to execute control to make the HST 510 neutral.
Accordingly, when the engine is in a high load state when the fail control based on the first to fourth errors is performed, the control device 400 causes the work clutch electric motor to be in a power cut-off state. The fuel stop valve 20a is energized after a predetermined time has elapsed since the actuator 600 was operated, so that the engine 20 is forcibly stopped.

On the other hand, when the fifth error occurs, it is possible to control the HST 510 to be in a neutral state.
Therefore, when the engine control is in a high load state when the fail control based on the fifth error is performed, the control device 400 causes the work clutch electric actuator 600 to be turned off so that the work clutch mechanism 105 is in a power cut-off state. The engine 20 is forcibly stopped by energizing the fuel stop valve 20a after a predetermined period of time has elapsed since the operation and / or the electric actuator 80 for shifting is operated so that the HST 510 is in a neutral state. It is comprised so that.

The predetermined time from when the load on the engine 20 is reduced to when the fuel stop solenoid 20a is energized is appropriately set and stored in the storage unit 402 (preferably EEPROM).
For example, the predetermined time is 1 to 5 seconds.

  As shown in FIGS. 1 to 2 and 4, the working vehicle 1 according to the present embodiment further includes a traveling clutch operating member 75 for engaging and disengaging the power transmission of the traveling system transmission path, and the traveling clutch operation. A travel clutch sensor 450 that detects an operation state of the member 75 is provided.

The travel clutch operation member 75 is a deadman clutch lever provided in the operation unit 70.
Specifically, as shown in FIGS. 1 and 2, the handle frame 71 is provided with a connecting frame 711 along the body width direction that connects the free ends of the pair of left and right support frames 710 </ b> L and 710 </ b> R.

  The travel clutch operating member 75 in the form of the deadman clutch lever is a clutch separated from the connection frame 711 while being urged by a biasing member (not shown) in a direction away from the connection frame 711. The handle frame 71 is supported by the handle frame 71 so as to be swingable about a rotation axis along the vehicle width direction so that a release position and a clutch engagement position close to the connection frame can be taken.

  That is, the traveling clutch operating member 75 in the form of the deadman clutch lever is positioned at the clutch engagement position by being gripped with the connecting frame 711 against the biasing force of the biasing member, and is gripped. By being released from the state, it is located at the clutch release position by the urging force of the urging member.

  When the control device 400 determines that the travel clutch operating member 75 is positioned at the clutch release position based on a signal from the travel clutch sensor 450, the control device 400 sets the neutral state of the HST 510 regardless of the operation state of the speed change operation member 72. Operation control of the electric actuator 80 for shifting is executed as the HST target output.

Here, the control program stored in the control device 400 will be described.
5 and 6 show flowcharts of the control program.
The control program starts with the start of driving of the engine 20 (and in some cases, a manual operation to the mode selection switch).

First, the control of the traveling system in the normal control will be described.
In step 10, it is determined based on a signal from the traveling clutch sensor 450 whether or not the traveling transmission path should be in a power transmission state. If YES (that is, the traveling clutch operating member 75 is in the clutch engagement position). If YES, the process proceeds to step 11; if NO (ie, the travel clutch operating member 75 is positioned at the clutch release position), the process proceeds to step 21.

  In step 11, the HST actual output and the HST target output calculated based on the signal from the shift output side sensor 420 (and / or the HST operation side sensor 425) and the signal from the shift operation side sensor 410. It is determined whether or not the deviation between the two ranges exceeds a predetermined dead band range. If YES (that is, if the speed change operating member 72 is operated), the process proceeds to step 12; If the speed change operation member 72 is not operated), the process proceeds to step 13.

In step 12, the control device 400 outputs a control signal for driving the speed change electric motor 80 in a direction to bring the HST actual output closer to the HST target output.
The control signal is, for example, a pulse width modulation control signal having a pulse width corresponding to the magnitude of the deviation.
Note that the storage unit 402 of the control device 400 stores control data (such as an arithmetic expression or a look-up table) relating to the relationship between the magnitude of the deviation and the pulse width.

  In step 13, the left and right turning electric motor actual outputs and the left and right turning calculated based on the signals from the left and right turning output side sensors 440L and 440R and the signals from the left and right turning operation side sensors 430L and 430R. It is determined whether or not the deviation between the electric motor target outputs exceeds a predetermined dead band range. If YES (that is, if the left and right turning operation members 73L and 73R are operated), the routine proceeds to step 14. In the case of NO (that is, when the left and right turning operation members 73L and 73R are not operated), the process proceeds to Step 50 described later.

In step 14, the control device 400 generates a control signal for driving the left and right turning electric motors 520L and 520R in a direction to bring the left and right turning electric motor actual outputs closer to the left and right turning electric motor target outputs. Output.
The control signal is, for example, a pulse width modulation control signal having a pulse width corresponding to the magnitude of the deviation.
Note that the storage unit 402 of the control device 400 stores control data (such as an arithmetic expression or a look-up table) relating to the relationship between the magnitude of the deviation and the pulse width.

  If NO in step 10 (that is, if the travel clutch operating member 75 is located at the clutch release position), the process proceeds to step 21 as described above.

  In step 21, whether or not the deviation between the HST actual output and the HST neutral output calculated based on the signal from the shift output side sensor 420 (and / or the HST operation side sensor 425) exceeds the dead band range. In the case of YES (ie, when the HST 510 is not in a neutral state), the process proceeds to Step 22, and in the case of NO (ie, when the HST 510 is in a neutral state), the process proceeds to Step 23.

In step 22, the control device 400 outputs a control signal for driving the shift electric motor 80 in a direction to bring the HST actual output closer to the HST neutral output that is the HST target output.
The control signal is, for example, a pulse width modulation control signal having a pulse width corresponding to the magnitude of the deviation.
Note that the storage unit 402 of the control device 400 stores control data (such as an arithmetic expression or a look-up table) relating to the relationship between the magnitude of the deviation and the pulse width.

In step 23, the control device 400 outputs a control signal for stopping the left and right turning electric motors 520L and 520R.
Thereafter, the process proceeds to step 50 below.

Next, control of the work machine system in the normal control will be described.
In step 30, it is determined based on a signal from the work clutch operation side sensor 460 whether or not the work machine system transmission path should be in a power transmission state. If YES (that is, the work clutch operation member 74 is engaged with the clutch). If it is located at the union position), the process proceeds to step 31. If NO (that is, the work clutch operating member 74 is located at the clutch release position), the process proceeds to step 32.

In step 31 and step 32, the control device 400 causes the work clutch electric actuator 600 to engage or disengage, respectively.
Thereafter, the process proceeds to step 50 below.

Next, the fail control will be described.
In step 50, it is determined whether at least one of the first to fifth errors has occurred.

If NO in step 50 (that is, if none of the first to fifth errors has occurred), the process proceeds to step 60.
In step 60, it is determined whether or not to end the control program. Whether to end the control program is determined based on, for example, whether the engine 20 has stopped.
If YES in step 60, the control program is terminated. If NO, the process returns to step 10 and step 30.

  On the other hand, if YES in step 50 (that is, if at least one of the first to fifth errors has occurred), the process proceeds to step 51.

In step 51, it is determined whether or not the engine 20 is in a high load state.
Specifically, as described above, the control device 400 determines whether or not the load of the engine 20 is based on whether or not the work machine 20 is being driven in a state where the vehicle is traveling forward or being simulated to travel forward. Determine the state.

In the case of NO in step 51 (that is, when the engine 20 is not in a high load state), the process proceeds to step 54, the energization process is performed on the fuel stop solenoid 20a, the fuel supply line is shut off, The engine 20 is brought into an output stop state.
When the engine 20 is not in a high load state, the fuel supply line does not flow so much fuel. Therefore, the fuel supply line can be shut off by immediately energizing the fuel stop solenoid 20a.

If YES in step 51 (that is, if the engine 20 is in a high load state), the routine proceeds to step 52.
In step 52, control for reducing the load of the engine 20 is executed.
Specifically, as described above, the control device 400 controls the operation clutch electric actuator 600 so that the operation clutch mechanism 105 is in a power cut-off state, and / or the HST 510 is in a neutral state. By executing the control to operate the electric actuator 80 for shifting as described above, the load on the engine 20 is reduced.

  Then, after a predetermined time (for example, 1 to 5 seconds) has elapsed in step 53, the process proceeds to step 54.

  As described above, when the engine 20 is in a high load state when the fail control is executed, the fuel stop solenoid 20a is energized after a predetermined time has elapsed since the load of the engine 20 is reduced, so that the fuel The supply line can be reliably shut off.

DESCRIPTION OF SYMBOLS 1 Work vehicle 20 Engine 20a Fuel stop solenoid 30L, 30R Left and right traveling device 72 Shift operation member 73L, 73R Left and right turning operation member 74 Work clutch operation member 80 Shift electric motor 105 Work clutch mechanism 400 Control device 410 Shift operation side sensor 420 Shift output side sensor 425 Shift operation side sensor 430L, 430R Left and right turning operation side sensor 440L, 440R Left and right turning output side sensor 460 Work clutch operation side sensor 470 Work clutch operation side sensor 510 HST
515 Output adjustment member 520L, 520R Left and right turning electric motor 530L, 530R Left and right differential mechanism 600 Electric actuator for work clutch

Claims (5)

An engine configured to have a fuel stop solenoid inserted in a fuel supply line, wherein the fuel supply is cut off by energization of the fuel stop solenoid and the output is stopped; a pair of left and right traveling devices; The HST that inputs rotational power operatively from the engine, a pair of left and right electric motors for turning, and the corresponding running power by combining the rotational rotational power from the HST and the corresponding turning rotational power from the electric motor for turning. A pair of left and right differential mechanisms that output to the device, a manually operated speed change operation member, a speed change electric actuator that operates the output adjustment member of the HST, and a speed change operation that detects an operation state of the speed change operation member Side sensor, a speed change operation side sensor for detecting the operation state of the output adjusting member, a speed change output side sensor for detecting the output state of the HST, A pair of left and right turning operation members that can be manually operated, a pair of left and right turning operation side sensors that detect an operation state of the pair of turning operation members, and a pair of left and right that detect an output state of the pair of left and right turning electric motors A turn output side sensor, a work clutch mechanism inserted in a work system transmission path from the engine to the work part, a work clutch operation member that can be manually operated, and a work clutch that detects an operation state of the work clutch operation member An operation side sensor, a work clutch electric actuator for switching the transmission state of the work clutch mechanism, a work clutch operation side sensor for detecting the transmission state of the work clutch mechanism, and the operation state of the work clutch operation member While controlling the operation of the electric actuator for the working clutch so that the transmission state of the working clutch mechanism is switched The shift electric actuator is operated and controlled such that an actual HST output based on a detection signal from the shift operation side sensor or the shift output side sensor coincides with an HST target output based on a detection signal from the shift operation side sensor; The left and right turning electric motor actual output based on the detection signals from the pair of left and right turning output side sensors respectively match the left and right turning electric motor target output based on the detection signals from the pair of left and right turning operation side sensors. A working vehicle including a control device that performs normal control for controlling the operation of a pair of left and right electric motors for turning;
While the normal control is being executed, the control device outputs the control signal within a predetermined time in spite of outputting a control signal to the shift electric motor in accordance with a change in a detection signal from the shift operation side sensor. When a first error that does not cause a change in the detection signal from the operating side sensor occurs, fail control is performed to energize the fuel stop solenoid to forcibly stop the output of the engine.
When the fail control is executed, the control device detects that the vehicle is traveling forward based on a signal from the shift operation side sensor or the shift output side sensor, and from the work clutch operation side sensor or the work clutch operation side sensor. When the working unit is being driven, it is determined that the engine is in a high load state, and in the engine high load state, the work clutch electric motor is operated so that the work clutch mechanism is in a power cut-off state. A working vehicle characterized in that the engine is forcibly stopped by energizing the fuel stop valve after a predetermined time has elapsed since the actuator was operated.   The control device executes the fail control when either the first error or a second error in which no detection signal is input from both the shift operation side sensor and the shift output side sensor occurs within a predetermined time. Further, when executing the fail control, if there is no detection signal input from both the shift operation side sensor and the shift output side sensor, it is assumed that the vehicle is traveling forward. The working vehicle according to claim 1, wherein the working vehicle is configured.   The control device includes an HST target output based on the first error, the second error, or a detection signal from the shift operation side sensor and an actual HST output based on a detection signal from the shift operation side sensor or the shift output side sensor. 3. The work according to claim 2, wherein the fail control is executed when any of the third errors exceeding a predetermined range occurs even after a predetermined time elapses. Vehicle.   The control device is configured to execute the fail control when any of the first to third errors or a fourth error in which a detection signal of the shift operation side sensor exceeds a predetermined range occurs. The working vehicle according to claim 3.   The control device includes a first electric motor target output for turning based on the first to fourth errors or a detection signal from the turning operation side sensor, and an actual output of the turning electric motor based on the detection signal from the turning output side sensor. It is configured to execute the fail control when any one of the fifth errors exceeding a predetermined range occurs even after a predetermined time has passed, and further, the fail control based on the first to fourth errors is performed. When the engine is in a high load state, the engine is operated by energizing the fuel stop valve after a predetermined time has elapsed since the working clutch electric actuator is operated so that the working clutch mechanism is in a power cut-off state. The output is forcibly stopped, and when the fail control is executed based on the fifth error, the work class is not The fuel stop valve is operated after a predetermined time has elapsed since the work clutch electric actuator is operated so that the power mechanism is in a power cut-off state and / or the shift electric actuator is operated so that the HST is in a neutral state. The working vehicle according to claim 4, wherein the engine is forcibly put into an output stop state by energizing the motor.

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