KR102523878B1 - Control apparatus for working vehicle - Google Patents

Abstract

A control device for a work vehicle capable of stabilizing the behavior of the work vehicle when a servo mechanism is abnormal.
The left HST 33 and the right HST 34 include a hydraulic pump 41 driven by power of the engine 31 and a hydraulic motor 42 driven by hydraulic oil discharged from the hydraulic pump 41. am. Corresponding to each of the left HST 33 and the right HST 34, a servo mechanism 66 for controlling the inclination angle of the pump swash plate of the hydraulic pump 41 is provided. When an abnormality such as failure occurs in the servo mechanism 66, a fail safe operation is executed. In the fail safe operation, as an abnormality of the servo mechanism 66 corresponding to one of the left and right pair of traveling devices is detected, the left HST 33 and the right HST 33 corresponding to each of the left and right pair of traveling devices are operated as a fail safe operation. Output from both HST 34 is stopped.

Description

Control device for work vehicle {CONTROL APPARATUS FOR WORKING VEHICLE}

The present invention relates to a control device for work vehicles such as a combine.

Conventionally, a combine equipped with a hydro static transmission (HST) is widely known. The hydrostatic continuously variable transmission is equipped with a hydraulic pump and a hydraulic motor. In a combine equipped with a hydrostatic continuously variable transmission, a hydraulic pump is driven by engine power, a hydraulic motor is driven by oil discharged from the hydraulic pump, and the power of the hydraulic motor is transmitted to the left and right crawlers.

A hydraulic circuit including a hydraulic pump and a hydraulic motor has, for example, a circuit configuration of a closed circuit, and a servo piston that changes an angle of a swash plate is attached to the hydraulic pump and provided. By changing the angle of the swash plate of the hydraulic pump, the discharge direction and flow rate of oil from the hydraulic pump change, and the rotation direction and rotation speed of the hydraulic motor change. In the driving method of the servo piston, a shift lever provided on the control panel of the steering wheel is mechanically connected to the servo piston and supplied to a pressure control valve composed of a mechanical type that operates the servo piston by operating the shift lever and two proportional pressure reducing control valves. There is an electronic control type (electronic servo type) in which the servo piston is moved by the hydraulic pressure supplied to the servo piston from these pressure control valves by controlling the current.

Japanese Unexamined Patent Publication No. 2009-30693

In a hydrostatic continuously variable transmission employing an electronic control type, if the servo mechanism including the servo piston and pressure control valve fails, the angle of the swash plate of the hydraulic pump becomes uncontrollable, and furthermore, the power transmitted from the hydraulic motor to the crawler becomes uncontrollable. As a result, the behavior of the combine becomes unstable.

An object of the present invention is to provide a control device for a work vehicle capable of stabilizing the behavior of the work vehicle when a servo mechanism is abnormal.

In order to achieve the above object, a control device for a work vehicle according to the present invention includes an engine, a pair of left and right traveling devices, a pump driven by power of the engine, and a motor driven by hydraulic oil discharged from the pump. A control device used in a work vehicle equipped with a continuously variable transmission and a servo mechanism that controls the angle of a pump swash plate, and a power transmission device that transmits motor power to a pair of left and right traveling devices, wherein the servo mechanism is abnormal. and fail-safe means for executing a fail-safe operation for stabilizing the behavior of the work vehicle in response to detection of an abnormality by the abnormality detection means.

According to this configuration, a power transmission device is interposed between the engine and the pair of left and right traveling devices. The power transmission device includes a continuously variable transmission including a pump driven by engine power and a motor driven by hydraulic oil discharged from the pump, and a servo mechanism that controls the angle of the pump swash plate. By controlling the angle of the pump swash plate, the discharge direction and flow rate of oil from the pump are controlled, and the rotation direction and rotation speed of the motor are controlled.

When an abnormality such as a failure occurs in the servo mechanism and the abnormality is detected, a fail safe operation for stabilizing the behavior of the work vehicle is executed. Therefore, it is possible to stabilize the behavior of the work vehicle when the servo mechanism is abnormal.

The continuously variable transmission and the servo mechanism may be provided correspondingly to each of the pair of left and right traveling devices. In this case, the fail-safe means detects an abnormality in the servo mechanism corresponding to one of the left and right pair of traveling devices by the abnormality detection means, and as a fail-safe operation, the continuously variable transmission corresponding to each of the left and right pair of traveling devices. You may control the servo mechanism corresponding to each of a pair of left and right traveling devices so that output from both sides of may stop. Thus, the body of the work vehicle can be stopped, and the behavior of the work vehicle can be stabilized by stopping the body.

The traveling device includes an axle to which power is transmitted from the power transmission device, a continuously variable transmission and a servo mechanism are provided corresponding to each of the left and right pair of traveling devices, and the power transmission device comprises a pair of left and right traveling devices. A structure may be provided with clutches engaged in order to match the rotational speeds of the respective axles. In this case, the fail-safe means engages the clutch as a fail-safe operation in response to detecting an abnormality in the servo mechanism corresponding to one of the left and right pair of traveling devices by the abnormality detecting means, thereby A servo mechanism corresponding to the other side of the pair of left and right traveling devices may be controlled so that output from the continuously variable transmission corresponding to the other side continues. This makes it possible to drive the motor of the continuously variable transmission corresponding to the normally operating servo mechanism, and the machine can be driven while the behavior of the work vehicle is stabilized by the power from the motor.

The servo mechanism includes a servo piston interlocking with the pump swash plate, a forward control valve supplying hydraulic pressure to the servo piston to position the servo piston within a predetermined forward range, and a servo piston to position the servo piston within a predetermined backward range. It is provided with a reverse control valve for supplying hydraulic pressure, and when the servo piston is located within the forward range, the pump swash plate forms an angle at which hydraulic oil in the forward direction is discharged from the pump, and when the servo piston is located within the reverse range, the pump swash plate It is provided so as to form an angle at which hydraulic oil in the backward direction is discharged from the pump, and the pump outputs power in the direction in which the work vehicle moves forward by supplying the hydraulic oil in the forward direction, and the work vehicle moves backward by supplying the hydraulic oil in the backward direction. It may be structured to output power in the direction to do. In this configuration, the fail-safe means permits control of the reverse control valve as a fail-safe operation when an abnormality in the forward control valve is detected by the abnormality detection means, and the abnormality in the reverse control valve is detected by the abnormality detection means. In this case, control of the forward control valve may be permitted as a fail-safe operation. Thus, forward travel of the aircraft by control of the normally operating forward control valve is possible, and backward travel of the aircraft is enabled by control of the normally operating reverse control valve. Therefore, the body can be driven while the behavior of the work vehicle is stabilized.

The work vehicle may further include an operating member provided to be operable between a forward position on one side and a reverse position on the other side relative to the neutral position. In this case, the control device comprises: position detecting means for detecting the position of the operating member, swash plate angle detecting means for detecting the angle of the pump swash plate, and the angle of the pump swash plate according to the position of the operating member detected by the position detecting means. A configuration further including control means for controlling the servo mechanism so as to match the target angle, and the abnormality detection means, when the deviation between the target angle and the angle detected by the swash plate angle detection means is equal to or greater than a certain level is maintained for a certain period of time, You may detect that the servo mechanism is abnormal.

The fail safe operation when abnormality of the servo mechanism is detected may be an operation of stopping the engine. The machine can be stopped by stopping the engine, and the behavior of the work vehicle can be stabilized by stopping the machine.

The fail safe operation may be an operation of putting the engine in an idling state, or may be an operation of stopping the engine as the position of the operating member detected by the position detecting unit coincides with the neutral position after the engine is in the idling state. When the engine is in an idling state, the running speed of the machine can be suppressed, so the running of the machine can be secured while the behavior of the work vehicle is stabilized.

In addition, the power transmission device further includes a control valve that switches the angle of the motor swash plate of the motor between a first angle at which the rotation of the motor is relatively low and a second angle at which the rotation of the motor is relatively high. In this case, the swash plate of the motor may be set to the first angle by controlling the control valve as a fail-safe operation. This makes it possible to further suppress the travel speed of the body and further stabilize the behavior of the work vehicle.

When the abnormality of the servo mechanism is detected by the abnormality detecting means, further comprising storage means for storing the fact that the abnormality has been detected, while the fail safe means stores the detected abnormality of the servo mechanism in the storage means, You may prohibit starting the engine. If the engine is started in a state where the abnormality is not resolved, there is a risk that the work vehicle exhibits an unstable behavior, but the unstable behavior of the work vehicle can be suppressed by prohibiting the start of the engine.

According to the present invention, it is possible to stabilize the behavior of the work vehicle when the servo mechanism is abnormal.

1 : is a right side view which shows the front part of a combine.
2 : is a figure which shows the structure of a part of the drive transmission system of a combine.
Fig. 3 is a cross-sectional view showing a part of the remainder of the drive transmission system, showing the drive transmission system from the hydraulic motors of the left HST and the right HST to the traveling device.
Fig. 4 is a block diagram showing main parts of the electrical configuration of a combine according to an embodiment of the present invention.
5 is a flowchart showing the flow of fail safe control.
6 is a flowchart showing the flow of fail safe control according to another embodiment.
Fig. 7 is a flowchart showing the flow of fail safe control according to another embodiment.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described in detail, referring an accompanying drawing.

<Combine>

1 is a right side view showing a front portion of a combine 1 according to an embodiment of the present invention.

The combine 1 is a work vehicle that performs reaping of grain stems and threshing from grain stems while traveling on a field. The body 11 of the combine 1 is supported by a pair of left and right traveling devices 12. In order to enable the travel of the combine 1 on the field, the travel device 12 adopts a crawler having a static driving capability.

The body 11 is provided with a steering wheel 13, a reaping device 14, a threshing device 15, and a grain tank 16.

The steering wheel 13 is disposed above the front end of the traveling device 12 . A driver's seat 17 on which an operator sits is provided on the steering wheel 13, and an operation panel 18 operated by the operator is provided on the front and left sides of the driver's seat 17, for example. The operation panel 18 is provided with a main transmission lever 21, a steering lever 22, and the like.

The main transmission lever 21 is provided so that tilting is possible in the front-rear direction. By tilting operation of the main transmission lever 21, forward and backward movement of the body 11 can be switched, and the forward or reverse speed thereof can be changed.

The steering lever 22 is provided so as to be able to tilt in the left-right and front-rear directions. By tilting the steering lever 22 in the left and right directions, the machine 11 can be switched between going straight, turning left, and turning right. Moreover, the harvesting apparatus 14 can be moved up and down by tilting operation of the steering lever 22 in the front-rear direction.

The reaping device 14 is disposed in front of the traveling device 12 . The reaping apparatus 14 equips the front end part with the cutting frame 23, and equips the back of the cutting frame 23 with the blade 24. The cutting blade 23 and the blade 24 are supported by the harvesting device frame 25F. At the rear end of the harvesting device frame 25F, a horizontal harvesting frame 25L extending in the left-right direction is provided. One end of the harvesting main frame 25M is connected to the harvesting horizontal frame 25L. The main reaping frame 25M extends rearward from the reaping transverse frame 25L, and its other end (the front is provided slackly and its rear end) is connected to the frame of the body 11 so that rotation is possible. By the tilting operation of the steering lever 22 in the front and rear direction, a cylinder (not shown) can be operated to swing the main harvesting frame 25M, and the swinging causes the cutting blade 23 and the blade 24 to It is raised and lowered from the rising position where it has risen high from the ground and the lowering position where the minute section 23 and the blade 24 are lowered close to the ground. When the body 11 moves forward with the bunchogan 23 and the blade 24 positioned in the lowered position, the root of the grain stem planted in the field is divided by the bunchogan 23, and the grain stem falls on the blade 24. is harvested by

The threshing device 15 and the grain tank 16 are arranged side by side at the rear position of the reaping device 14 while being above the travel device 12. The harvested grain stalk is conveyed to the threshing device 15 by the reaping device 14. The threshing apparatus 15 conveys suitably the bottom side of a grain culm to the rear side with a threshing feed chain, and supplies the upper side of a grain culm to a class chamber, and threshes it. And the grain is conveyed to the grain tank 16 from the threshing apparatus 15, and the grain is stored in the grain tank 16. The grain discharge auger 26 is continuously installed in the grain tank 16, and the grain stored in the grain tank 16 can be discharged outside the gas by the grain discharge auger 26.

<Stepless speed change device>

2 : is a figure which shows the structure of a part of the drive transmission system 32 of the combine 1. As shown in FIG. In FIG. 2, the power transmission system from the engine 31 to the drive transmission system 32 is shown in a structural diagram, and the configuration of the left HST 33 and the right HST 34 of the drive transmission system 32 is shown in the hydraulic circuit diagram. .

The combine 1 is equipped with an engine 31 and a drive transmission system 32 that transmits the power of the engine 31 to the travel device 12 .

The drive transmission system 32 includes a left HST (Hydro Static Transmission) 33 and a right HST 34 .

The left HST 33 connects the hydraulic pump 41 and the hydraulic motor 42 to the first flow path 43 and the second flow path 44 so that hydraulic oil circulates between the hydraulic pump 41 and the hydraulic motor 42. It has a structure of connected closed circuit. The first oil passage 43 is connected to the first port 45 of the hydraulic pump 41 and the first port 46 of the hydraulic motor 42 . The second oil passage 44 is connected to the second port 47 of the hydraulic pump 41 and the second port 48 of the hydraulic motor 42 .

In addition, a charge pump 51 is attached to the left HST 33 and provided. The charge pump 51 is a fixed displacement hydraulic pump, and discharges hydraulic oil to the charge oil passage 53 by the rotation of the pump rotary shaft 52 . The charge flow path 53 is connected to the first flow path 43 through the first check valve 54 and connected to the second flow path 44 through the second check valve 55 . In addition, the charge oil passage 53 is connected to the oil tank 57 via a charge relief valve 56 .

By the function of the charge relief valve 56, the hydraulic pressure of the charge oil passage 53 is maintained at a predetermined charge pressure. When the hydraulic pressure of the first flow passage 43 is lower than the hydraulic pressure of the charge passage 53, that is, the charge pressure, the first check valve 54 is opened, and the first check valve 54 is opened through the first check valve 54 from the charge passage 53. Hydraulic oil is supplied to the first flow path 43 . Also, when the hydraulic pressure of the second flow passage 44 is lower than the charge pressure, the second check valve 55 is opened, and the second check valve 55 flows from the charge flow passage 53 to the second flow passage 44 through the second check valve 55. oil is supplied. As a result, the hydraulic pressure of the first oil passage 43 and the second oil passage 44 is maintained above the charge pressure.

The left HST 33 includes a hydraulic pump 41, a hydraulic motor 42, a first flow path 43, a second flow path 44, a first check valve 54, a second check valve 55, and a charge It is configured as an integrated HST in which the relief valve 56 and the like are housed in a single case.

The hydraulic pump 41 is a variable displacement swash plate type piston pump, and includes a cylinder block, a plurality of radially arranged pistons in the cylinder block, and a pump swash plate on which the pistons slide. The hydraulic pump 41 and the charge pump 51 have a pump rotating shaft 52 in common, and the cylinder block is provided so as to integrally rotate with the pump rotating shaft 52 .

In order to change the inclination angle of the pump swash plate of the hydraulic pump 41, an electronically controlled servo piston 58 is provided. The servo piston 58 has a first pressure chamber 62 to which hydraulic pressure is supplied from the forward pressure control valve 61 and a second pressure chamber 64 to which hydraulic pressure is supplied from the reverse pressure control valve 63. . In addition, the servo piston 58 has a rod 65 that moves linearly by the differential pressure between the first pressure chamber 62 and the second pressure chamber 64, and the direct movement of the rod 65 causes the pump swash plate to The inclination angle of is changed. The servo mechanism 66 which controls the inclination angle of the pump swash plate of the hydraulic pump 41 is comprised by the servo piston 58, the forward pressure control valve 61, and the reverse pressure control valve 63.

The larger the inclination angle of the pump swash plate with respect to the axis of the pump rotation shaft 52 of the hydraulic pump 41 (the rotation axis of the cylinder block), the smaller the amount of hydraulic oil discharged from the hydraulic pump 41, and the inclination angle of the pump swash plate is 90 When it is °, discharge of the hydraulic oil from the hydraulic pump 41 stops. Further, when the inclination angle of the pump swash plate exceeds 90° (when the inclination is reversed), the discharge direction of the hydraulic oil from the hydraulic pump 41 is reversed from that when the inclination angle is less than 90°.

The hydraulic motor 42 is a variable displacement swash plate type piston motor, and includes a motor rotation shaft 71, a cylinder block 72 (see FIG. 3) that rotates integrally with the motor rotation shaft 71, and a cylinder block 72. A plurality of radially arranged pistons 73 (see Fig. 3) and a motor swash plate 74 capable of pressing the pistons 73 (see Fig. 3) and the like are provided. When the inclination angle of the motor swash plate 74 with respect to the axis of the motor rotation shaft 71 of the hydraulic motor 42 (the rotation axis of the cylinder block) is constant, the amount of hydraulic oil supplied to the hydraulic motor 42, that is, the hydraulic pump ( As the amount of hydraulic oil discharged from 41) increases, the number of revolutions of the motor rotational shaft 71 increases.

In addition, when the amount of hydraulic oil supplied to the hydraulic motor 42 is constant, the rotation speed of the motor rotary shaft 71 decreases as the inclination angle of the motor swash plate 74 increases. In order to change the inclination angle of the motor swash plate 74 of the hydraulic motor 42, a sub-transmission piston 75 is provided. A low-speed selector valve 76 and a high-speed selector valve 77 are connected to the sub-shift piston 75 . The low-speed selector valve 76 is turned on and the high-speed selector valve 77 is turned off, and hydraulic pressure is supplied from the low-speed selector valve 76 to the sub-shift piston 75, so that the rod 78 of the sub-shift piston 75 ) is located at the low speed position, and the inclination angle of the motor swash plate 74 becomes relatively large. On the other hand, when the low-speed selector valve 76 is turned off and the high-speed selector valve 77 is turned on, hydraulic pressure is supplied from the high-speed selector valve 77 to the sub-shift piston 75, thereby reducing the load of the sub-shift piston 75. 78 is located at the high-speed position, and the inclination angle of the motor swash plate 74 is relatively small. Therefore, by switching on/off of the low-speed selector valve 76 and the high-speed selector valve 77, the position of the motor swash plate 74 is changed to the position on the high-speed side where the rotational speed of the motor rotational shaft 71 is relatively large, and the motor It is possible to switch to the second position on the low speed side where the number of revolutions of the rotating shaft 71 becomes relatively small.

Since the right HST 34 has the same configuration as the left HST 33, the same reference numerals as those of each part are attached to parts corresponding to the respective parts of the left HST 33 with respect to the right HST 34, omit the explanation.

Power of the engine 31 is input to each pump rotation shaft 52 of the left HST 33 and the right HST 34 . Specifically, on the output shaft 81 of the engine 31, a pulley 82 is provided so as not to be relatively rotatable. The drive transmission system 32 includes an input shaft 83 extending in parallel with the output shaft 81 of the engine 31 . On the input shaft 83, a pulley 84 is provided so as not to be relatively rotatable. Between the pulleys 82 and 84, an endless belt 85 is wound and hung. In addition, an input gear 86 is provided on the input shaft 83 so as not to be relatively rotatable. An intermediate gear 87 is engaged with the input gear 86, and a pump gear 88 provided non-rotatably with the pump rotation shaft 52 of the right HST 34 is engaged with the intermediate gear 87. The pump gear 88 meshes with a pump gear 89 provided non-rotatably relative to the pump rotational shaft 52 of the left HST 33 .

As a result, the power of the engine 31 is transmitted from the output shaft 81 to the pulley 84 through the pulley 82 and the belt 85, and the input shaft 83 is rotated integrally with the pulley 84. Then, the power (rotation) of the input shaft 83 is transmitted from the input gear 86 through the intermediate gear 87 to the pump gear 88 of the right HST 34, integrally with the pump gear 88 thereof. The pump rotation shaft 52 of the right HST 34 is rotated in a predetermined direction. In addition, the power of the input shaft 83 is transmitted from the input gear 86 to the pump gear 88 of the right HST 34 through the intermediate gear 87, and from the pump gear 88 to the pump gear 89 , and integrally with its pump gear 89, it rotates the pump rotating shaft 52 of the left HST 33 in a direction opposite to the predetermined direction. Therefore, when the inclination angle of the pump swash plate of each hydraulic pump 41 of the left HST 33 and the right HST 34 is the same, the motor rotation shaft 71 of the hydraulic motor 42 of the left HST 33 and The motor rotation shafts 71 of the hydraulic motor 42 of the right HST 34 rotate in opposite directions to each other.

3 is a cross-sectional view showing a part of the drive transmission system 32, and shows the configuration from the hydraulic motor 42 of the left HST 33 and the right HST 34 to the traveling device 12. As shown in FIG.

Each of the hydraulic motors 42 of the left HST 33 and the right HST 34 have motor rotational shafts 71 arranged on the same axis (having a common axis), and the axis is aligned with the left and right axles 91L, 91R), they are arranged symmetrically with each other.

In the following description, the motor rotation shaft 71 of the left HST 33 is referred to as "motor rotation shaft 71L", and the motor rotation shaft 71 of the right HST 34 is referred to as "motor rotation shaft 71R". do.

The outer ends of the motor rotation shafts 71L and 71R in the left-right direction are rotatably supported by the unit case 101 forming the outer shell of the drive transmission system 32 via bearings 102L and 102R, respectively. Motor output gears 103L and 103R are supported so as not to rotate relative to each other at the inner ends of the motor rotational shafts 71L and 71R in the left-right direction.

Between the motor rotation shafts 71L and 71R and the axles 91L and 91R, the first intermediate shaft 104, the second intermediate shaft 105, and the third intermediate shaft 106 are spaced apart from each other, and the axle 91L, 91R) is provided in parallel. The first intermediate shaft 104 is non-rotatably supported by the unit case 101 . The left and right ends of the second intermediate shaft 105 are rotatably supported by the unit case 101 via bearings 107L and 107R, respectively. The left and right ends of the third intermediate shaft 106 are rotatably supported by the unit case 101 via bearings 108L and 108R, respectively.

Motor output gear 103L, 103R meshes with 1st intermediate gear 111L, 111R rotatably hold|maintained by the 1st intermediate shaft 104, respectively.

On the left side of the second intermediate shaft 105, a second intermediate gear 112L and a third intermediate gear 113L are supported so as not to rotate relative to each other. On the other hand, on the right side of the second intermediate shaft 105, a third intermediate gear 113R is supported via a needle bearing so as to be relatively rotatable. Further, an annular second intermediate gear 112R is provided outside the third intermediate gear 113R so as to surround the third intermediate gear 113R. The inner peripheral portion of the second intermediate gear 112R is fixed to the third intermediate gear 113R. As a result, the second intermediate gear 112R rotates integrally with the third intermediate gear 113R. The second intermediate gears 112L and 112R mesh with the first intermediate gears 111L and 111R, respectively. The third intermediate gears 113L and 113R mesh with the fourth intermediate gears 114L and 114R, respectively.

On the third intermediate shaft 106, fifth intermediate gears 115L and 115R are supported so as not to rotate relatively. The fourth intermediate gears 114L and 114R form an annular shape and are provided so as to surround the outside of the fifth intermediate gears 115L and 115R, respectively. The inner peripheral portions of the fourth intermediate gears 114L and 114R are fixed to the fifth intermediate gears 115L and 115R, respectively. As a result, the fourth intermediate gears 114L and 114R rotate integrally with the fifth intermediate gears 115L and 115R, respectively. The fifth intermediate gears 115L and 115R mesh with the sixth intermediate gears 116L and 116R.

A through hole 117 extending above the central axis is formed in the sixth intermediate gear 116L. The right end of the axle shaft 91L is inserted into the through hole 117 from the left, and the right end is splined. At the left end of the sixth intermediate gear 116R, a columnar portion 118 having an outer diameter smaller than the inner diameter of the through hole 117 of the sixth intermediate gear 116L is formed. The columnar portion 118 is inserted through the through hole 117 from the right side, and is held by the sixth intermediate gear 116L via a needle bearing so that relative rotation is possible. Further, a circular concave portion 119 concave to the left is formed at the right end of the sixth intermediate gear 116R. The left end of the axle shaft 91R is inserted into the concave portion 119, and the left end is splined. Bearings 121L and 121R are externally fitted to the left end of the sixth intermediate gear 116L and the right end of the sixth intermediate gear 116R, respectively, and the outer races of these bearings 121L and 121R form a unit case. By being fixedly held by (101), sixth intermediate gears 116L and 116R are rotatably held by unit case 101. Further, the left end of the axle 91L and the right end of the axle 91R are rotatably held by the unit case 101 via the bearings 122L and 122R, respectively, so that the axles 91L and 91R are the unit case ( 101) is rotatably held.

The left end of the axle 91L and the right end of the axle 91R are coupled to driving wheels 123L and 123R of the traveling device 12 in a relative non-rotatable manner, respectively.

In addition, the drive transmission system 32 is provided with a center clutch 131 . The center clutch 131 is engaged and released to connect and disconnect the second intermediate shaft 105 and the third intermediate gear 113R. That is, by engaging the center clutch 131, the second intermediate shaft 105 and the third intermediate gear 113R are connected, so that the second intermediate shaft 105 and the third intermediate gear 113R rotate integrally. do. By releasing the center clutch 131, the second intermediate shaft 105 and the third intermediate gear 113 are separated, so that the third intermediate gear 113 is rotatable with respect to the second intermediate shaft 105. . The center clutch 131 is engaged and released by hydraulic pressure.

In addition, the drive transmission system 32 is provided with a parking brake 132 . The parking brake 132 is engaged and released to brake and release the second intermediate shaft 105 . That is, when the parking brake 132 is engaged, the second intermediate shaft 105 is non-rotatably braked with respect to the unit case 101 . When the parking brake 132 is released, braking of the second intermediate shaft 105 is released, so that the second intermediate shaft 105 can rotate with respect to the unit case 101 . The parking brake 132 is engaged and released by manual operation of the parking brake lever.

<Electrical Configuration>

4 : is a block diagram which shows the main part of the electrical structure of the combine 1. As shown in FIG.

In the combine 1, a single main ECU (Electronic Control Unit) 141 for comprehensive control of the whole and a plurality of ECUs 142 for individual specific control are mounted. 4 shows one of the plurality of ECUs 142 . The ECU 142 shown in FIG. 4 may be subdivided according to its functions and constituted by a plurality of ECUs 142 . All of the ECUs 141 and 142 are configurations including a micro controller unit (MCU).

The main ECU 141 is connected to each ECU 142 for individual specific control so that communication is possible. The main ECU 141 receives information that each ECU 142 acquires from detection signals of various sensors, etc., and transmits commands and information required for control by each of these ECUs 142 to each ECU 142. do. In addition, to the main ECU 141, a meter panel 151 disposed on the operation panel 18 (see FIG. 1) of the steering wheel 13 is connected as a control object, and the main ECU 141 is connected to the meter panel. Various instruments such as an odometer provided in 151 and an indicator 152 are controlled. The display 152 is made of, for example, a liquid crystal display.

The ECU 142 shown in FIG. 4 (hereinafter simply referred to as "ECU 142") includes a main gear lever sensor 153 that outputs a detection signal according to the operating position of the main gear lever 21; A steering lever sensor 154 that outputs a detection signal according to the operating position of the steering lever 22, and a left vehicle speed sensor 155 that outputs a pulse signal synchronized with the rotation of the left axle 91L as a detection signal; A right vehicle speed sensor 156 that outputs, as a detection signal, a pulse signal synchronized with the rotation of the right axle 91R is connected, and these detection signals are input.

In addition, the ECU 142 includes a forward valve current sensor 157 that outputs a detection signal according to a current value supplied to the forward pressure control valve 61 included in the left HST 33 and the right HST 34, respectively. , the reverse valve current sensor 158 outputting a detection signal according to the current value supplied to the reverse pressure control valve 63 included in the left HST 33 and the right HST 34, respectively, and the left HST 33 and A pump swash plate position sensor 159 outputting a detection signal according to the position (angle) of the pump swash plate of the hydraulic pump 41 included in each of the right HSTs 34 is connected, and these detection signals are input.

Moreover, in the combine 1, as a mode (swing control mode) of the turning control of the base body 11, a soft turning mode, a brake turning mode, and a spin turning mode are set. Further, a turning mode switch 161 for switching a turning control mode is provided on the operation panel 18 of the steering wheel 13 . The turning mode switch 161 is a dial switch, and in its movable area, a soft position, a brake position and a spin position corresponding to the turning control mode are set. The turning mode switch 161 has a knob that is pinched by an operator's finger and operated to turn, and outputs different signals depending on which of the soft position, brake position, and spin position the knob is located.

The ECU 142 includes a main speed lever sensor 153, a steering lever sensor 154, a left vehicle speed sensor 155, a right vehicle speed sensor 156, a forward valve current sensor 157, and a reverse valve current sensor 158. And the driving and turning of the aircraft 11 are controlled based on information obtained from detection signals of various sensors such as the turning mode switch 161 and information input from the main ECU 141 and other ECUs 142. , engine 31, forward pressure control valve 61, reverse pressure control valve 63, low-speed switching valve 76 and high-speed switching valve 77 included in each of the left HST 33 and the right HST 34 and controls the operation of the center clutch 131.

<Travel Control>

Traveling of the body 11 is controlled by the ECU 142 . In this running control, the position of the main gear lever 21 is acquired from the detection signal of the main gear lever sensor 153.

Control of the current supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 for the left HST 33 and the right HST 34, respectively, when the position of the main gear lever 21 is at the stop position. As a result, their respective openings are adjusted so that the inclination angle of the pump swash plate of the hydraulic pump 41 becomes 90°. As a result, since the hydraulic oil is not discharged from the hydraulic pump 41, the hydraulic motor 42 does not rotate, and the power of the hydraulic motor 42 is not transmitted to the axle shafts 91L and 91R. Therefore, the traveling device 12 does not operate, and the body 11 is stopped.

When the main transmission lever 21 is tilted forward from the stop position, for the left HST 33 and the right HST 34, respectively, the amount of current supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 By control, the hydraulic pressure supplied from the forward pressure control valve 61 to the first pressure chamber 62 of the servo piston 58 is higher than the hydraulic pressure supplied from the reverse pressure control valve 63 to the second pressure chamber 64. It becomes big. As a result, a differential pressure is generated between the first pressure chamber 62 and the second pressure chamber 64, and the inclination angle of the pump swash plate of the hydraulic pump 41 is smaller than 90° due to this differential pressure. As a result, hydraulic oil is discharged from the hydraulic pump 41, and the hydraulic motor 42 receives the hydraulic oil and rotates. Then, the rotation (power) of the hydraulic motor 42 is transmitted to the axle shafts 91L and 91R, so that the drive wheels 123L and 123R of the traveling device 12 rotate integrally with the axle shafts 91L and 91R in the forward direction, respectively. By doing so, the body 11 advances.

When the main transmission lever 21 is tilted rearward from the stop position, for the left HST 33 and the right HST 34, respectively, the amount of current supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 By control, the hydraulic pressure supplied from the reverse pressure control valve 63 to the second pressure chamber 64 is higher than the hydraulic pressure supplied from the forward pressure control valve 61 to the first pressure chamber 62 of the servo piston 58. It becomes big. As a result, a differential pressure is generated between the first pressure chamber 62 and the second pressure chamber 64, and the inclination angle of the pump swash plate of the hydraulic pump 41 is greater than 90° due to this differential pressure. As a result, the hydraulic oil is discharged from the hydraulic pump 41 in a direction opposite to that when moving forward, and the hydraulic motor 42 receives the hydraulic oil and rotates in the opposite direction to when moving forward. Then, the rotation (power) of the hydraulic motor 42 is transmitted to the axle shafts 91L and 91R, so that the drive wheels 123L and 123R of the traveling device 12 rotate integrally with the axle shafts 91L and 91R in the reverse direction, respectively. By doing so, the body 11 moves backward.

When the body 11 moves forward and backwards, the center clutch 131 is engaged. By engaging the center clutch 131, the second intermediate shaft 105 and the third intermediate gear 113R are connected, so that the second intermediate shaft 105 and the third intermediate gear 113R rotate integrally, The fourth intermediate gears 114L and 114R rotate at the same speed. Therefore, the fifth intermediate gears 115L and 115R rotate at the same speed, the sixth intermediate gears 116L and 116R rotate at the same speed, and the axle shafts 91L and 91R rotate at the same speed. As a result, since the left and right drive wheels 123L and 123R of the traveling device 12 rotate at the same speed, the body 11 moves forward or backward with excellent straight-line stability.

In addition, when the inclination angle of the pump swash plate of the hydraulic pump 41 is changed by controlling the current supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 during forward or backward movement, the hydraulic pump ( The amount of hydraulic fluid discharged from 41) changes, and the number of revolutions of the hydraulic motor 42 changes. Therefore, by adjusting the inclination angle of the pump swash plate of the hydraulic pump 41 according to the tilting amount of the main transmission lever 21 from the stop position, the forward and backward speeds of the body 11 can be changed steplessly. .

Further, in the drive transmission system 32, as described above, by switching on/off of the low-speed selector valve 76 and the high-speed selector valve 77, the rotational speed of the hydraulic motor 42 is relatively large compared to the high-speed stage. It is possible to switch to the lower 2nd gear, which is smaller. Therefore, it is possible to change the forward and backward speed of the body 11 even by switching between the high speed stage and the low speed stage. In addition, an auxiliary shift lever (not shown) may be provided on the control panel 18 of the steering wheel 13, and switching between high speed and low speed may be instructed by manipulating the auxiliary shift lever.

<Turn control>

When the steering lever 22 is tilted from the center straight position to the left or right turning position when the aircraft 11 is traveling straight (forward/reverse), the ECU 142 turns the aircraft 11 Turning control is initiated for

In turning control, it is discriminated from the output signal of the turning mode switch 161 whether the position of the turning mode switch 161 is a soft position, a brake position, or a spin position.

When the position of the swing mode switch 161 is the soft position, the swing control mode is set to the soft swing mode. In the normal turning control in the soft turning mode, the target turning ratio, which is the target value of the turning ratio, is set to 0.3, for example. Then, the actual turn ratio (real turn ratio) is supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 of each of the left HST 33 and the right HST 34 so that the turn ratio matches the target turn ratio. By controlling the current (inclination angle of the pump swash plate of the hydraulic pump 41), the rotational speed of the travel device 12 (one of the drive wheels 123L and 123R) on the inside of the swing is lowered.

The turning ratio is the speed ratio of the travel device 12 on the inside of the swing to the travel device 12 on the outside of the swing, and specifically, when the outside of the swing is on the left side, the rotation speed of the axle 91L on the left side is the ratio of the rotational speed of the right axle 91R, and is the ratio of the rotational speed of the left axle 91L on the inside of the swing to the rotational speed of the right axle 91R when the swing outer side is the right side. The rotational speed of the left axle 91L can be calculated from the detection signal of the left vehicle speed sensor 155, and the rotational speed of the right axle 91R can be calculated from the detection signal of the right vehicle speed sensor 156. there is. When the turning outside is left, the ratio of the rotational speed of the axle 91R calculated from the detection signal of the right vehicle speed sensor 156 to the rotational speed of the axle 91L calculated from the detection signal of the left vehicle speed sensor 155 is By obtaining, the actual turning ratio can be calculated. When the turning outside is right, the ratio of the rotational speed of the axle 91L calculated from the detection signal of the left vehicle speed sensor 155 to the rotational speed of the axle 91R calculated from the detection signal of the right vehicle speed sensor 156 is By obtaining, the actual turning ratio can be calculated.

When the position of the turning mode switch 161 is the brake position, the turning control mode is set to the brake turning mode. In normal turning control in the brake turning mode, the target turning ratio is set to zero, for example. Then, the currents supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 of the left HST 33 and the right HST 34 are controlled so that the actual turn ratio coincides with the target turn ratio, so that the turning inner side The rotational speed of the travel device 12 can be lowered. When the target turning ratio is zero, the target speed of the traveling device 12 inside the turning becomes zero. Therefore, in normal swing control when the position of the swing mode switch 161 is the brake position, the forward pressure control valves of the left HST 33 and the right HST 34 stop the traveling device 12 inside the swing. 61 and the current supplied to the reverse pressure control valve 63 are controlled.

When the position of the turning mode switch 161 is the spin position, the turning control mode is set to the spin turning mode. In normal swing control in the spin turning mode, the rotation direction of the traveling device 12 inside the swing is reversed, and a negative sign (-) is added to the rotational speed value of the traveling device 12 inside the swing to obtain The target value of the turn ratio (target turn ratio) is set to -0.3. Then, the currents supplied to the forward pressure control valve 61 and the reverse pressure control valve 63 of the left HST 33 and the right HST 34 are controlled so that the actual turn ratio matches the target turn ratio.

<Fail safe operation>

5 is a flowchart showing the flow of fail safe control.

Fail safe control is executed by ECU 142 in order to operate combine 1 on the safe side (fail safe operation) when an abnormality such as a failure in which travel control cannot be performed normally occurs.

In this fail-safe control, the detection signals of the forward valve current sensor 157 and the reverse valve current sensor 158 affect the servo mechanisms 66 corresponding to the left HST 33 and the right HST 34 to travel control. It is discriminated whether or not an abnormality affecting ? has occurred (step S11).

In addition, below, the servo piston 58 corresponding to the left HST 33 is referred to as "left servo mechanism 66", and the servo piston 58 corresponding to the right HST 34 is referred to as "right servo mechanism". (66)”.

As an abnormality of the servo mechanism 66, for example, when there is a failure in which the signal lines of the forward valve current sensor 157 and the reverse valve current sensor 158 are disconnected, the disconnection failure occurs in the left servo mechanism 66. Disconnection failure of forward valve current sensor 157, disconnection failure of reverse valve current sensor 158 of servo 66 on the left, disconnection failure of forward valve current sensor 157 of servo 66 on the right and right A short circuit failure of the reverse valve current sensor 158 of the servo 66 of the

When no abnormality has occurred in at least one of the left or right servo mechanisms 66 (NO in step S11), fail safe control does not proceed before this.

When an abnormality occurs in at least one of the left or right servo mechanisms 66 (YES in step S11), the drive of the left HST 33 and the right HST 34 is stopped (step S12) according to the occurrence of the abnormality. ). When the driving of the left HST 33 and the right HST 34 is stopped, the body 11 is stopped.

After that, it is discriminated whether or not an instruction to transition from the normal mode to the emergency mode has been input (step S13). The normal mode is a mode in which normal travel control is executed, and the emergency mode is a mode in which the body 11 can temporarily travel when an abnormality occurs. An instruction to transition to the emergency mode is provided by operation of a control unit provided on the meter panel 151 of the steering wheel 13 (for example, a touch panel disposed overlapping the indicator 152) or a switch provided on the operation panel 18. is input to the ECU 142 by Until an instruction to transition to the emergency mode is input, driving stop of the left HST 33 and the right HST 34 is maintained, and travel of the body 11 is impossible.

When an instruction to transition to the emergency mode is input (YES in step S13), it is determined whether or not the generated abnormality is only a forward abnormality that prevents the aircraft 11 from moving forward normally (step S14). For example, when only the disconnection failure of the forward valve current sensor 157 has occurred, it is determined that only the forward abnormality has occurred.

If only the forward abnormality has occurred (YES in step S14), it is determined whether or not a forward command has been input (step S15). Specifically, from the detection signal of the main gear lever sensor 153, it is discriminated whether the main gear lever 21 tilted forward.

When the main gear lever 21 is tilted forward (YES in step S15), the center clutch 131 is engaged (step S16).

Then, among the left or right servo mechanisms 66, the left or right servo mechanisms 66 that can normally operate are controlled, and the left HST 33 or the right HST 34 corresponding to the servo mechanism 66 The hydraulic motor 42 is driven in the forward direction (step S17). For example, when only the disconnection failure of the forward valve current sensor 157 of the servo mechanism 66 on the left has occurred, the hydraulic motor 42 of the HST 34 on the right is driven in the forward direction. Since the center clutch 131 is engaged, the left and right drive wheels 123L and 123R of the traveling device 12 are driven by the power output from the hydraulic motor 42 of the left HST 33 or the right HST 34. rotates in the forward direction at the same speed. As a result, the body 11 advances.

If no forward command has been input (NO in step S15), it is determined whether or not a reverse command has been input (step S18). Specifically, it is discriminated whether or not the main gear lever 21 is tilted rearward from the detection signal of the main gear lever sensor 153.

When the main gear lever 21 is tilted rearward when forward abnormality occurs (YES in step S18), since the body 11 is capable of normal reverse travel, by the same control as the travel control in the normal mode , the hydraulic motors 42 of the left HST 33 and the right HST 34 are driven in the reverse direction (step S19). As a result, the body 11 moves backward.

When both the forward command and the reverse command are not input, that is, when the main gear lever 21 is not tilted from the stop position (No in step S18), the main switch provided on the operation panel 18 turns on the engine 31 ) is determined at the "off" position, that is, whether an engine stop operation has been performed (step S20).

When the engine stop operation is performed (YES in step S20), the engine 31 is stopped, and the fail safe control ends. If the engine stop operation has not been performed (NO in step S20), it is determined again whether or not a forward abnormality has occurred (step S14).

If the forward abnormality has not occurred (NO in Step S14), it is determined whether or not the abnormality that has occurred is only a reverse abnormality that prevents the aircraft 11 from traveling backward normally (Step S21). For example, when only the disconnection failure of the reverse valve current sensor 158 has occurred, it is determined that only the reverse abnormality has occurred.

If only the reverse abnormality has occurred (YES in step S21), it is determined whether or not a reverse command has been input (step S22). Specifically, it is discriminated whether or not the main gear lever 21 is tilted rearward from the detection signal of the main gear lever sensor 153.

When the main gear lever 21 is tilted rearward (YES in step S22), the center clutch 131 is engaged (step S23).

Then, among the left or right servo mechanisms 66, the left or right servo mechanisms 66 that can normally operate are controlled, and the left HST 33 or the right HST 34 corresponding to the servo mechanism 66 The hydraulic motor 42 is driven in the reverse direction (step S24). For example, when only the disconnection failure of the reverse valve current sensor 158 of the right servo mechanism 66 occurs, the hydraulic motor 42 of the left HST 33 is driven in the forward direction. Since the center clutch 131 is engaged, the left and right drive wheels 123L and 123R of the traveling device 12 are moved by the power output from the hydraulic motor 42 of the left HST 33 or the right HST 34. Rotate in the forward direction at speed. As a result, the body 11 advances.

When a reverse command is not input (NO in step S22), it is determined whether or not a forward command is input (step S25). Specifically, it is discriminated whether or not the main gear lever 21 is tilted forward from the detection signal of the main gear lever sensor 153.

When the main gear lever 21 is tilted forward at the occurrence of reverse abnormality (YES in step S25), since the body 11 is capable of normal forward travel, by the same control as the travel control in the normal mode , the hydraulic motors 42 of the left HST 33 and the right HST 34 are driven in the forward direction (step S26). Thereby, the body 11 advances.

When neither the forward command nor the reverse command is input, that is, when the main gear lever 21 is not tilted from the stop position (NO in step S25), it is determined whether an engine stop operation has been performed (step S20 ).

When the engine stop operation is performed (YES in step S20), the engine 31 is stopped, and the fail safe control ends. If the engine stop operation has not been performed (NO in step S20), it is determined again whether or not a forward abnormality has occurred (step S14).

Also, if both the forward and reverse abnormalities have occurred (NO in step S21), the fail safe control is ended.

<action effect>

According to this configuration, a drive transmission system 32 is interposed between the engine 31 and the pair of left and right traveling devices 12 . In the drive transmission system 32, a left HST 33 and a right HST 34 are provided corresponding to the pair of left and right traveling devices 12, respectively. The left HST 33 and the right HST 34 include a hydraulic pump 41 driven by power of the engine 31 and a hydraulic motor 42 driven by hydraulic oil discharged from the hydraulic pump 41. is a composition In addition, the drive transmission system 32 is provided with a servo mechanism 66 that controls the inclination angle of the pump swash plate of the hydraulic pump 41 corresponding to each of the left HST 33 and the right HST 34 . By controlling the inclination angles of the pump swash plates of the left HST 33 and the right HST 34, the discharge direction and flow rate of oil from the hydraulic pump 41 are controlled, and the rotation direction and rotation speed of the hydraulic motor 42 are controlled. controlled

When an abnormality such as failure occurs in the servo mechanism 66 and the abnormality is detected, a fail-safe operation for stabilizing the behavior of the combine 1 is executed. In the fail-safe operation, as an abnormality of the servo mechanism 66 corresponding to one of the left and right pair of traveling devices 12 is detected, as a fail-safe operation, first, the corresponding corresponding to each of the left and right pair of traveling devices 12 Outputs from both the left HST 33 and the right HST 34 are stopped. The body 11 of the combine 1 can be stopped by this, and the behavior of the combine 1 can be stabilized by the stop of the body 11.

The travel device 12 includes axles 91L and 91R to which power is transmitted from the drive transmission system 32 . And the drive transmission system 32 is equipped with the center clutch 131 engaged in order to make the rotation speed of axle 91L, 91R match. In the fail-safe operation, after the outputs of the left HST 33 and the right HST 34 are stopped, the center clutch 131 is then engaged, and the left HST 33 corresponding to the normally operating servo mechanism 66 Alternatively, its normally operating servo mechanism 66 is controlled so that the output from the right HST 34 continues. As a result, the hydraulic motor 42 of the left HST 33 or the right HST 34 corresponding to the servo mechanism 66 that operates normally can be driven, and the combine ( The body 11 can be driven while stabilizing the behavior of 1).

<Other Embodiments>

6 is a flowchart showing the flow of fail safe control according to another embodiment.

In travel control, a target swash plate angle, which is a control target value of the inclination angle of the pump swash plate of the hydraulic pump 41, is set according to the position of the main gear lever 21 acquired from the detection signal of the main gear lever sensor 153. . In addition, the actual inclination angle (actual swash plate angle) of the pump swash plate of the hydraulic pump 41 is acquired from the detection signal of the pump swash plate position sensor 159 . The forward pressure control valve 61 and the reverse pressure control valve 63 included in the servo mechanism 66 are controlled so that the deviation between the target swash plate angle and the actual swash plate angle approaches zero.

In the fail safe control shown in Fig. 6, the target swash plate angle set by the travel control is referred to by the ECU 142 (step S31). Further, the actual swash plate angle acquired in the travel control is referred to (step S32).

Then, it is determined whether or not a state in which the deviation between the target swash plate angle and the actual swash plate angle is equal to or greater than a certain level is maintained over a certain period of time (step S33).

If the deviation between the target swash plate angle and the actual swash plate angle is less than a certain level, or the deviation between the target swash plate angle and the actual swash plate angle is greater than or equal to a certain level, and the time when the constant or higher state continues does not exceed a certain amount of time ("No in step S33) "), the target swash plate angle and the actual swash plate angle are referred to again (steps S31 and S32). Then, it is judged again whether or not the state in which these deviations are equal to or higher than a certain level is maintained over a certain period of time (step S33).

If the deviation between the target swash plate angle and the actual swash plate angle is equal to or greater than a certain level is maintained over a certain period of time (Yes in step S33), failure of the forward pressure control valve 61 and the reverse pressure control valve 63 or forward movement It is determined that an abnormality has occurred in the servo mechanism 66, such as a failure in which the signal lines of the valve current sensor 157 and the reverse valve current sensor 158 are disconnected. In this case, the engine 31 is stopped (step S34).

<action effect>

In this way, when an abnormality such as a failure occurs in the servo mechanism 66 and the abnormality is detected, the engine 31 is stopped. Since the drive of the hydraulic pump 41 is stopped by the stop of the engine 31, the body 11 of the combine 1 can be stopped. By stopping the body 11, the behavior of the combine 1 can be stabilized.

<Third Embodiment>

7 is a flowchart showing the flow of fail safe control according to the third embodiment.

In the fail safe control shown in Fig. 7, the target swash plate angle set by the travel control is referred to by the ECU 142 (step S41). Also, the actual swash plate angle acquired in the travel control is referred to (step S42).

Then, it is determined whether or not a state in which the deviation between the target swash plate angle and the actual swash plate angle is equal to or greater than a certain level is maintained over a certain period of time (step S43).

If the deviation between the target swash plate angle and the actual swash plate angle is less than a certain level, or the deviation between the target swash plate angle and the actual swash plate angle is greater than or equal to a certain level, and the time when the constant or more state continues does not exceed a certain amount of time ("No in step S43) "), the target swash plate angle and the actual swash plate angle are referred to again (steps S41 and S42). Then, it is judged again whether or not the state in which these deviations are equal to or higher than a certain level is maintained over a certain period of time (step S43).

If the deviation between the target swash plate angle and the actual swash plate angle is equal to or greater than a certain level is maintained over a certain period of time (YES in step S43), it is determined that an abnormality has occurred in the servo mechanism 66. In this case, the low speed selector valve 76 provided corresponding to the hydraulic motor 42 is turned on, and the high speed selector valve 77 is turned off so that the motor swash plate 74 of the hydraulic motor 42 is located on the low speed side. It becomes (step S44). Also, the engine 31 is in an idling state (step S45).

After that, when the main gear lever 21 returns to the stop position (YES in step S46), the engine 31 is stopped (step S47).

In addition, the state of the abnormality (error) occurring in the servo mechanism 66 (for example, the size of the deviation between the target swash plate angle and the actual swash plate angle, etc.) is stored in the nonvolatile memory in the ECU 142 (step S48).

Then, starting of the engine 31 is inhibited (step S49), and the fail safe control ends.

<action effect>

In this way, when an abnormality such as a failure occurs in the servo mechanism 66 and the abnormality is detected, the motor swash plate 74 of the hydraulic motor 42 turns to the low speed side, and the engine 31 enters an idling state. Thereby, the body 11 can be driven at a low speed. While stabilizing the behavior of the combine 1, the running of the body 11 can be ensured, and the combine 1 can be moved to a safe position.

After that, when the main gear lever 21 is returned to the stop position (neutral position), the engine 31 is stopped. In addition, the error condition is stored in the non-volatile memory, and thereafter the start of the engine 31 is inhibited until the error condition is resolved. Thereby, the unstable behavior of the combine 1 can be suppressed.

<Example of modification>

Above, several embodiments of the present invention have been described, but the present invention can also be implemented in other forms, and various design changes can be made to the above configuration within the scope of the matters described in the claims. .

1: combine (work vehicle)
12: travel device
21: main transmission lever (operating member)
31: engine
32: drive transmission system (power transmission device)
41: hydraulic pump (pump)
42: hydraulic motor (motor)
58: servo piston
61 forward pressure control valve (advance control valve)
63: reverse pressure control valve (reverse control valve)
66: servo
76: low-speed switching valve (control valve)
77: high-speed switching valve (control valve)
131: center clutch (clutch)
142: ECU (control unit, abnormality detection means, fail safe means, control means, storage means)
153 Main speed lever sensor (position detecting means)
159: pump swash plate position sensor (swash plate angle detection means)

Claims (10)

A continuously variable transmission including an engine, a pair of left and right traveling devices, a pump driven by power of the engine and a motor driven by hydraulic oil discharged from the pump, and a servo mechanism controlling the angle of the pump swash plate of the pump A control device used in a work vehicle equipped with a power transmission device for transmitting power of the motor to the pair of left and right traveling devices,
Abnormality detecting means for detecting an abnormality of the servo mechanism;
and fail-safe means for executing a fail-safe operation for stabilizing the behavior of the work vehicle in response to detection of an abnormality by the abnormality detection means;
The continuously variable transmission and the servo mechanism are provided corresponding to each of the pair of left and right traveling devices,
When an abnormality of the servo mechanism corresponding to one of the left and right pair of traveling devices is detected by the abnormality detecting means, the fail safe operation performs an operation for each of the left and right pair of traveling devices. and controls the servo mechanism corresponding to each of the left and right pair of traveling devices so that outputs from both sides of the corresponding continuously variable transmission stop. A continuously variable transmission including an engine, a pair of left and right traveling devices, a pump driven by power of the engine and a motor driven by hydraulic oil discharged from the pump, and a servo mechanism controlling the angle of the pump swash plate of the pump A control device used in a work vehicle equipped with a power transmission device for transmitting power of the motor to the pair of left and right traveling devices,
Abnormality detecting means for detecting an abnormality of the servo mechanism;
and fail-safe means for executing a fail-safe operation for stabilizing the behavior of the work vehicle in response to detection of an abnormality by the abnormality detection means;
The traveling device includes an axle to which power is transmitted from the power transmission device,
The continuously variable transmission and the servo mechanism are provided corresponding to each of the pair of left and right traveling devices,
The power transmission device includes a clutch engaged to match the number of rotations of the axles provided in each of the left and right pair of traveling devices,
When an abnormality of the servo mechanism corresponding to one of the left and right pair of traveling devices is detected by the abnormality detection means, the fail safe means engages the clutch as the fail safe operation, and controls the servo mechanism corresponding to the other side of the left and right pair of traveling devices so that an output from the continuously variable transmission corresponding to the other side of the pair of traveling devices continues. A continuously variable transmission including an engine, a pair of left and right traveling devices, a pump driven by power of the engine and a motor driven by hydraulic oil discharged from the pump, and a servo mechanism controlling the angle of the pump swash plate of the pump A control device used in a work vehicle equipped with a power transmission device for transmitting power of the motor to the pair of left and right traveling devices,
Abnormality detecting means for detecting an abnormality of the servo mechanism;
and fail-safe means for executing a fail-safe operation for stabilizing the behavior of the work vehicle in response to detection of an abnormality by the abnormality detection means;
The servo mechanism includes a servo piston interlocking with the pump swash plate, a forward control valve supplying hydraulic pressure to position the servo piston within a predetermined forward range to the servo piston, and moving the servo piston to the servo piston in a predetermined range. and a reverse control valve supplying hydraulic pressure to position the servo piston within the forward range, and when the servo piston is located within the forward range, the pump swash plate forms an angle at which the hydraulic oil in the forward direction is discharged from the pump, and the servo piston When located within the reverse range, the pump swash plate is provided at an angle at which hydraulic oil in the reverse direction is discharged from the pump,
The pump outputs power in a direction in which the work vehicle moves forward by supplying hydraulic oil in the forward direction, and outputs power in a direction in which the work vehicle moves backward by supplying hydraulic oil in the backward direction;
The fail-safe means permits control of the reverse control valve as the fail-safe operation when an abnormality in the forward control valve is detected by the abnormality detecting means, and the reverse control valve and permitting control of the forward control valve as the fail-safe operation when an abnormality of is detected. A continuously variable transmission including an engine, a pair of left and right traveling devices, a pump driven by power of the engine and a motor driven by hydraulic oil discharged from the pump, and a servo mechanism controlling the angle of the pump swash plate of the pump A control device used in a work vehicle equipped with a power transmission device for transmitting power of the motor to the pair of left and right traveling devices,
Abnormality detecting means for detecting an abnormality of the servo mechanism;
and fail-safe means for executing a fail-safe operation for stabilizing the behavior of the work vehicle in response to detection of an abnormality by the abnormality detection means;
The work vehicle further mounts an operating member provided to be operable between a forward position on one side and a reverse position on the other side relative to the neutral position,
The control device,
position detecting means for detecting the position of the operating member;
a swash plate angle detecting means for detecting an angle of the pump swash plate;
further comprising control means for controlling the servo mechanism so that an angle of the pump swash plate matches a target angle according to a position of the operating member detected by the position detection means;
The abnormality detecting means detects that the servo mechanism is abnormal when a state in which the deviation between the target angle and the angle detected by the inclined plate angle detecting means is equal to or greater than a predetermined period of time is maintained;
The fail safe means sets the engine in an idling state as the fail safe operation;
The fail safe means controls, as the fail safe operation, to stop the engine when the position of the operation member detected by the position detecting means coincides with the neutral position after putting the engine into an idling state. Device. According to claim 4,
The control device according to claim 1 , wherein the fail safe means stops the engine as the fail safe operation. According to claim 4,
The power transmission device further includes a control valve that converts an angle of a motor swash plate of the motor into a first angle at which the rotation of the motor is relatively low and a second angle at which the rotation of the motor is relatively high, ,
The control device according to claim 1 , wherein the fail safe means, as the fail safe operation, controls the control valve to set the swash plate of the motor to the first angle. According to any one of claims 4 to 6,
Further comprising storage means for storing the fact that the abnormality was detected when the abnormality of the servo mechanism was detected by the abnormality detecting means,
The control device according to claim 1 , wherein the fail safe means prohibits starting of the engine while the memory means stores the detected abnormality of the servo mechanism. delete delete delete

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