JP2020001441A - Work vehicle - Google Patents

Abstract

To provide a work vehicle that is able to ensure satisfactory ground drive for a plurality of running wheels even in a case where a vehicle body runs in a very rough work place while maintaining a proper position.SOLUTION: A work vehicle comprises: a plurality of running drive devices 6 that separately drive a plurality of running wheels 2; a raising/lowering support mechanism 4 that separately supports the plurality of running wheels 2 on a vehicle body such that the wheels are freely raised or lowered; a plurality of position change operation means 5 capable of separately changing respective positions of the plurality of raising/lowering support mechanisms 4; control means that controls operations of the position change operation means 5; and idle rotation detection means Q that detects whether each running wheel 2 is in a state of idle rotation. When the idle rotation detection means Q detects that the running wheel 2 is in the state of idle rotation, the control means controls the corresponding position change operation means 5 such that the raising/lowering support mechanism 4 lowers this running wheel 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a work vehicle suitable for traveling on a road surface having a lot of unevenness.

  Conventionally, four traveling wheels are supported on a vehicle body via a link mechanism which has two joints and is configured to be able to bend and extend, and the link mechanism is configured to be able to bend and extend by a driving force of an electric motor. Some wheels are individually driven to rotate by an electric motor (for example, see Patent Document 1).

JP-A-9-142347

  The wheel supporting structure in the above-described conventional configuration enables the vehicle to run while maintaining the vehicle body in an appropriate posture while bending and extending the link mechanism even when the traveling road surface has irregularities. However, in the above-described conventional configuration, when traveling on uneven terrain with a lot of irregularities, for example, even when one of the traveling wheels enters the concave portion and idles, the link mechanism maintains the posture as it is, The vehicle body is supported by other traveling wheels, and the traveling wheels have disadvantages such as a long idling state, and there is room for improvement.

  Therefore, there has been a demand for a work vehicle capable of securing a good ground drive state with a plurality of running wheels even when the vehicle body travels on a work site with many irregularities while maintaining an appropriate posture. .

  The feature configuration of the work vehicle according to the present invention includes a plurality of traveling wheels located on each of the front and rear sides on the left and right sides of the vehicle main body, a plurality of traveling driving devices that respectively drive the plurality of traveling wheels, and a plurality of traveling drives. An elevating and lowering support mechanism for individually supporting the running wheels on the vehicle body so as to be able to freely ascend and descend, a plurality of attitude changing operation means capable of individually changing the attitudes of the plurality of elevating and lowering support mechanisms, and an operation of the attitude changing operation means. Control means for controlling, and idling state detecting means for detecting whether or not the traveling wheel is in an idling state, wherein the controlling means is that the traveling wheel is in an idling state by the idling state detecting means. The point is that when detected, the lifting and lowering support mechanism controls the operation of the attitude change operation means so as to lower the traveling wheel.

  According to the present invention, by moving a plurality of traveling wheels up and down individually with respect to the vehicle main body by the elevating support mechanism, even when traveling on a work land with many irregularities such as uneven terrain, the vehicle main body is It is possible to travel while maintaining an appropriate posture. And, while driving a plurality of traveling wheels individually by a plurality of traveling driving devices, and traveling on a work land with many irregularities, when the idling state detecting means detects that the traveling wheel is in an idling state. The operation of the attitude change operation means is controlled so as to lower the traveling wheel.

  The state in which the running wheels are idling is, for example, a state in which the running wheels enter a concave portion on the ground and are raised, or a state where the running wheels are on the ground but slippery on a slippery road surface. It can be considered that the user is in a state where the user is in a state where the user is in a state of being. Therefore, in such a case, the traveling wheels are lowered to touch the ground so that the driving force can be transmitted. As a result, even when the vehicle body is traveling on a work site with a lot of unevenness while maintaining a proper posture, it is possible to avoid a situation in which the traveling wheels run idle and to maintain a good ground drive state. be able to.

  In the present invention, the traveling drive device is configured by a hydraulic motor, and a pressure sensor that detects an internal pressure of a hydraulic oil supply passage in the hydraulic motor, and the internal pressure is previously determined based on detection information of the pressure sensor. It is preferable that the idling state detecting means is constituted by a judging means for judging that the traveling wheel is in an idling state when the value falls below a set value.

  According to this configuration, the traveling wheels are driven by the hydraulic motor. Hydraulic motors have better water resistance and dust resistance than electric motors.For example, even in a work environment where there are many fine dusts such as dust generated by traveling and floating dust generated from crops, It is less likely that such an operation will adversely affect the operation and cause a malfunction.

  With a configuration driven by a hydraulic motor, when the traveling wheels are idling, the internal pressure of the hydraulic oil supply path is reduced as compared to an appropriate driving state. Therefore, utilizing this fact, when the internal pressure detected by the pressure sensor falls below a preset value, it is determined that the motor is idling.

  Therefore, even if fine dust, moisture, or the like may fall, it is less likely to be adversely affected by this and cause an operation failure or the like, and the idling state can be easily detected.

  In the present invention, a driving speed detecting means for detecting a driving speed of the traveling driving device, a traveling speed detecting means for detecting an actual traveling speed of the vehicle body, and the traveling drive detected by the driving speed detecting means When the drive speed of the device is higher than the actual traveling speed detected by the traveling speed detecting device by a set amount or more, the discriminating device for discriminating that the traveling wheel is in an idling condition is provided by the idling condition detecting device. Is preferably configured.

  According to this configuration, if the driving speed of the traveling drive device is higher than the actual traveling speed of the vehicle body, there is a high possibility that the traveling wheels are idling. Therefore, the driving speed and the traveling speed detecting unit detect the driving speed and the actual traveling speed, and if the driving speed is higher than the actual traveling speed by a set amount or more, the traveling driving device is driven by the traveling driving device. It can be determined that the wheels are idling.

  Therefore, by comparing the actual speeds of the traveling wheels and the vehicle body, it is possible to reliably detect whether or not the traveling wheels are idling.

It is an overall side view of a work vehicle. FIG. 2 is an overall plan view of the work vehicle. It is a top view of a refraction link mechanism. It is a side view of a bending link mechanism. It is a top view showing the left turning state by a turning mechanism. FIG. 5 is a plan view showing a right turning state by the turning mechanism. It is a control block diagram. It is a side view at the time of changing the attachment state of an exterior frame. It is a side view at the time of changing the attachment state of an exterior frame.

  Hereinafter, an embodiment of a work vehicle according to the present invention will be described with reference to the drawings.

  1 and 2 show a work vehicle according to the present invention. In this embodiment, when defining the longitudinal direction of the vehicle body, it is defined along the traveling direction of the vehicle body, and when defining the lateral direction of the vehicle body, the left and right are defined in a state viewed from the vehicle body traveling direction. That is, the direction indicated by the reference numeral (A) in FIG. 1 is the vehicle front-rear direction, and the direction indicated by the reference numeral (B) in FIG. 2 is the vehicle left-right direction.

  As shown in FIGS. 1 and 2, the work vehicle includes a vehicle body 1 that supports the entire vehicle and has a substantially rectangular shape in plan view, a plurality of (specifically, four) traveling wheels 2, and a plurality of traveling wheels. 2, a plurality of auxiliary wheels 3 provided corresponding to each of the two, a plurality of traveling wheels 2, and a bending link mechanism 4 as a lifting and lowering support mechanism for supporting the plurality of traveling wheels 2 on the vehicle main body 1 so as to be freely changeable in position. And a hydraulic motor 6 as a plurality of traveling drive devices for individually driving a plurality of traveling wheels 2. The bending link mechanism 4, the traveling wheel 2, and the auxiliary wheel 3 are provided on each of the front and rear sides of the vehicle body 1, one pair each on the right and left sides.

  The vehicle body 1 is provided with a rectangular frame-shaped body frame 7 that supports the whole, a hydraulic supply source 8 that sends out hydraulic oil toward the posture changing operation unit 5, and a hydraulic supply source 8 that supplies the hydraulic oil to the posture changing operation unit 5. And a valve mechanism 9 for controlling the operating oil. Although not described in detail, the hydraulic supply source 8 includes an engine and a hydraulic pump driven by the engine, and these are integrally connected. The hydraulic supply 8 is mounted and supported by a support 10 connected to the lower side of the vehicle body frame 7, and is provided in a state of being located at the lower abdomen of the vehicle body 1. The hydraulic supply source 8 sends out and supplies hydraulic oil to the posture changing operation means 5 via a valve mechanism 9 by a hydraulic pump driven by an engine. Although not shown, by removing the support base 10 from the vehicle body frame 7, the hydraulic supply source 8 and the support base 8 are integrally slid from the vehicle body 1 to the lateral side in a connected state. It is possible to remove it, and it is possible to attach it by sliding it laterally by attaching the support base 10 to the vehicle body frame 7 again.

  The valve mechanism 9 is provided in a state of being mounted and supported on the upper side of the vehicle body frame 7, and includes a plurality of hydraulic control valves 11 for supplying and discharging hydraulic oil to the attitude changing operation means 5 or adjusting the flow rate. The upper part of the valve mechanism 9 is covered by a storage case 12. A control device 13 that controls the operation of the valve mechanism 9 is provided above the storage case 12.

  On the upper side of the body frame 7, for example, when the vehicle body 1 falls down, an exterior frame 14 for protecting the valve mechanism 9 stored in the storage case 12, the control device 13 provided above, and the like is provided. Have been. The exterior frame 14 is provided on both front and rear sides, and has a shape in which a rod-like body is bent substantially in a U shape in plan view and is bent in a substantially L shape in side view. Left and right ends are attached and fixed to the ends. The front and rear exterior frames 14 are provided such that their upper sides are close to each other, and have a shape that covers the outer peripheral sides of the valve mechanism 9, the control device 13, and the like.

  As shown in FIG. 8, the front and rear exterior frames 14 are mounted so that the upper side faces outward in the front-rear direction, and a wide mounting plate is mounted above the front and rear exterior frames 14 to be used as a truck for carrying cargo. can do. In addition, as shown in FIG. 9, by attaching the exterior frame 14 so that the upper side faces one side in the front-rear direction, the exterior frame 14 can be used as a handle for a worker to grasp by hand.

Next, a support structure for supporting the traveling wheels 2 on the vehicle body 1 will be described.
A plurality of (specifically, four) traveling wheels 2 are supported on the vehicle main body 1 via the refraction link mechanism 4 so as to be individually movable up and down. The refraction link mechanism 4 is supported by the vehicle body frame 7 via a revolving mechanism 16 so as to be rotatable around a vertical axis Y.

  The turning mechanism 16 is connected to the vehicle body frame 7 and supports the refracting link mechanism 4 in a freely rotatable manner. A hydraulic cylinder (hereinafter referred to as a swing cylinder) 18 is provided.

  In addition, as shown in FIGS. 3 and 4, the vehicle-body-side support portion 17 is provided on the side of the pair of upper and lower rectangular tubular front-rear frame bodies 19 provided on the lateral portions of the vehicle body frame 7. A connecting member 20 that is fitted and engaged in a state of being sandwiched from the outside and is removably bolted, an outer-side pivot bracket 21 located at an outer side portion of the connecting member 20 in the vehicle longitudinal direction, and a connecting member. 20 comprises an inner pivot bracket 22 located at an inner location in the vehicle longitudinal direction, and a vertical pivot shaft 23 supported by the outer pivot bracket 21. The refracting link mechanism 4 is rotatably supported around the axis Y of the lens.

  The refraction link mechanism 4 has a base end 24 supported by the vehicle body-side support portion 17 in a state where the position in the vertical direction is fixed and rotatable around the longitudinal axis Y, and one end of the base end 24. A first link 25 rotatably supported around a horizontal axis X1 at a lower portion of the first link 25, and one end supported at the other end of the first link 25 rotatably around a horizontal axis X2 and the other end And a second link 26 on which the traveling wheel 2 is supported.

  In addition, the base end portion 24 is provided in a rectangular frame shape in a plan view, and is rotatable around the vertical axis Y via the rotation support shaft 23 at a position biased inward in the vehicle width direction. In addition, it is supported by the outer-side pivot support bracket 21 of the vehicle-body-side support portion 17. The pivot cylinder 18 has one end rotatably connected to the inner pivot bracket 22 and the other end at a position where the base end 24 is displaced laterally with respect to the pivot 23. It is rotatably connected.

  A support shaft 27 provided at one end of the first link 25 is rotatably supported and supported on both left and right sides of the base end 24. The first link 25 is supported by a lower portion of the base end 24. 27 are rotatably connected around the axis.

  As shown in FIG. 4, the first link 25 has a base end side arm portion 25b and another end side arm portion 25a. At one end of the first link 25, a base arm 25b extending diagonally upward and outward is integrally formed. The other end of the first link 25 is integrally formed with the other end arm 25a extending diagonally upward and outward.

  As shown in FIG. 3, the second link 26 includes a pair of left and right band-shaped plate bodies 26a and 26b, and is formed in a forked shape in plan view. A connecting portion of the second link 26 to the first link 25 is provided by a pair of plate bodies 26a and 26b. A connection support shaft 28 for connecting to the first link 25 is rotatably supported in a region sandwiched between the pair of plate bodies 26a and 26b. The traveling wheel 2 is supported at the swing-side end of the second link 26 opposite to the connection point to the first link 25. As shown in FIG. 4, the swing-side end portion of the second link 26 is formed with an L-shaped extending portion 26A that extends substantially in an L-shape in a direction away from the vehicle body 1. The traveling wheel 2 is supported at the extension side end.

  As shown in FIG. 2, the traveling wheel 2 is supported in a state where the traveling wheel 2 is located on the outer side of the vehicle body in the left-right direction with respect to the bending link mechanism 4. More specifically, the second link 26 is supported at the swinging end of the second link 26 so as to be located outside the vehicle body in the left-right direction. The hydraulic motor 6 is supported at the swing-side end of the second link 26 in a state of being located on the vehicle body inner side in the left-right direction (opposite to the traveling wheels 2).

  A posture changing operation unit 5 is provided for each of the plurality of bending link mechanisms 4, which can change the posture of the bending link mechanism 4. As shown in FIGS. 3 and 4, the posture changing operation means 5 includes a first hydraulic cylinder 29 capable of changing the swing posture of the first link 25 with respect to the vehicle body 1, and a second link 26 with respect to the first link 25. A second hydraulic cylinder 30 capable of changing the swinging posture is provided. The first hydraulic cylinder 29 and the second hydraulic cylinder 30 are collectively arranged near the first link 25, respectively.

  The first link 25, the first hydraulic cylinder 29, and the second hydraulic cylinder 30 are arranged in a state where they are located between the pair of plate bodies 26a, 26b of the second link 26 in plan view. The first hydraulic cylinder 29 is provided on the inner side in the vehicle longitudinal direction with respect to the first link 25 and is provided along the longitudinal direction of the first link 25. One end of the first hydraulic cylinder 29 is interlockingly connected to a lower portion of the base end 24 via an arcuate first interlocking member 31. One end of the first hydraulic cylinder 29 is interlockingly connected to a base end portion of the first link 25 via another second interlocking member 32. Both ends of the first interlocking member 31 and the second interlocking member 32 are pivotally connected so as to be relatively rotatable. The other end of the first hydraulic cylinder 29 is operatively connected to the other end side arm 25 a formed integrally with the first link 25.

  The second hydraulic cylinder 30 is provided on the opposite side of the first hydraulic cylinder 29, that is, on the outer side in the vehicle longitudinal direction with respect to the first link 25, and substantially along the longitudinal direction of the first link 25. Have been. One end of the second hydraulic cylinder 30 is operatively connected to a base arm 25 b formed integrally with the base of the first link 25. The other end of the second hydraulic cylinder 30 is interlockingly connected via a third interlocking member 34 to an arm 35 integrally formed at the base end of the second link 26. The other end of the second hydraulic cylinder 30 is also interlockingly connected to a swing end side portion of the first link 25 via another fourth interlocking member 36. The third interlocking member 34 and the fourth interlocking member 36 are pivotally connected at both side ends so as to be relatively rotatable.

  When the first hydraulic cylinder 29 is expanded and contracted in a state where the operation of the second hydraulic cylinder 30 is stopped, each of the first link 25, the second link 26, and the traveling wheel 2 is integrated while maintaining the relative posture constant. Specifically, it swings around the horizontal axis X1 at the pivotal connection point with respect to the base end portion 24. When the second hydraulic cylinder 30 is extended and retracted in a state where the operation of the first hydraulic cylinder 29 is stopped, the second link 26 and the traveling wheel 2 are integrally formed while the posture of the first link 25 is kept constant. It swings around the horizontal axis X2 at the connecting point between the first link 25 and the second link 26.

  The auxiliary wheel 3 is supported by the intermediate bending portion of each of the plurality of bending link mechanisms 4 so as to be freely rotatable. The auxiliary wheel 3 is configured by a wheel having substantially the same outer diameter as the traveling wheel 2. A connection support shaft 28 that pivotally connects the first link 25 and the second link 26 is formed to extend so as to protrude outward from the second link 26 in the vehicle width direction. The auxiliary wheel 3 is rotatably supported at an extended projecting portion of the connection support shaft 28.

  As shown in FIGS. 5 and 6, each of the refraction link mechanism 4, the traveling wheel 2, the auxiliary wheel 3, and the posture changing operation means 5 integrally rotates around the axis Y of the rotation support shaft 23. It is freely supported by the outer pivot bracket 21. Then, by expanding and contracting the swivel cylinders 18, they are integrally rotated. From the straight running state in which the traveling wheel 2 faces in the front-rear direction, the turning operation can be performed by about 45 degrees in each of the left turning direction and the right turning direction.

  Although not shown, when the bolt connection of the connecting member 20 to the front-rearward frame body 19 is released, each of the turning mechanism 16, the bending link mechanism 4, the traveling wheel 2, the auxiliary wheel 3, and the attitude changing operation means 5 is provided. , Can be removed from the vehicle body 1 in a state of being integrally assembled. In addition, by connecting the connecting member 20 to the front-rearward frame body 19 by bolts, the above-described devices can be attached to the vehicle body 1 in a state of being integrally assembled.

  Hydraulic oil is supplied from the hydraulic supply source 8 to the first hydraulic cylinder 29 and the second hydraulic cylinder 30 of each of the plurality of bending link mechanisms 4 via the valve mechanism 9. In the valve mechanism 9, hydraulic oil is supplied and discharged by the hydraulic control valve 11, and the first hydraulic cylinder 29 and the second hydraulic cylinder 30 can be operated to expand and contract. The hydraulic control valve 11 is controlled by the control device 13.

  In addition, by adjusting the flow rate of the hydraulic oil by the hydraulic control valve 11 corresponding to the hydraulic motor 6, the rotation speed of the hydraulic motor 6, that is, the rotation speed of the traveling wheel 2 can be changed. The hydraulic control valve 11 is controlled by the control device 13 based on control information input by manual operation or control information set and stored in advance.

  As shown in FIG. 7, each of the four first hydraulic cylinders 29 and the four second hydraulic cylinders 30 is provided with a stroke sensor S1 capable of detecting a telescopic operation amount. The amount of expansion / contraction operation of each of the hydraulic cylinders 29 and 30 is a detection value corresponding to the swing position of the first link 25 and the second link 26 to be operated, and the detection result of each stroke sensor S1 is input to the control device 13. Is done.

  As shown in FIG. 1, the vehicle body 1 is provided with an acceleration sensor S2 including, for example, a triaxial acceleration sensor. The front, rear, left and right inclinations of the vehicle body 1 are detected based on the detection result of the acceleration sensor S2, and the attitude of the vehicle body 1 is controlled based on the result. That is, the supply of the hydraulic oil to each of the first hydraulic cylinder 29 and the second hydraulic cylinder 30 is controlled so that the posture of the vehicle body 1 becomes the target posture.

  The traveling wheel 2 is provided with a rotation sensor S3 as driving speed detecting means for detecting a rotation speed of the traveling wheel 2 driven by the hydraulic motor 6. Supply of hydraulic oil to the hydraulic motor 6 is controlled based on the rotation speed of the traveling wheel 2 detected by the rotation sensor S3 such that the rotation speed of the traveling wheel 2 becomes a target value.

  As described above, the configuration is such that the attitude of the refraction link mechanism 4 is changed by the hydraulic cylinders 29 and 30 as the hydraulically driven attitude change operation means 5, and the traveling drive is also performed by the hydraulic motor 6. Therefore, it is less affected by moisture, fine dust, etc., and is suitable for agricultural work.

  In this work vehicle, as shown in FIG. 1, a normal traveling mode is a four-wheel traveling state in which all four traveling wheels 2 are in contact with the ground and all four auxiliary wheels 3 are levitated from the ground. Although not described in detail, as the traveling mode, various traveling modes can be adopted by changing the posture of the bending link mechanism 4 in addition to this mode.

Next, operation control of the vehicle body 1 in the four-wheel running mode will be described.
FIG. 7 shows a control block diagram. The control device 13 includes, for example, a microcomputer or the like, and can execute various controls according to a control program. Then, the control device 13 sets the posture of the vehicle body 1 in an appropriate state according to the work situation at that time based on control information input by manual operation or control information set and stored in advance. An attitude control unit 100 is provided as control means for executing control so that

  The posture control unit 100 controls each of the four hydraulic cylinders 29 and the four second hydraulic cylinders 30 for each of the hydraulic cylinders 29 in both the state where the traveling vehicle is stopped traveling and the state where the traveling vehicle is traveling. , 30 so that the hydraulic control valve 11 is switched to operate the respective hydraulic cylinders 29, 30 so that the expansion / contraction operation amount detected by the stroke sensor S1 provided by the stroke sensor S1 becomes a detection value corresponding to the target posture. Execute control.

  The control device 13 adjusts the traveling speed of the vehicle body 1 to an appropriate speed based on control information input by a manual operation or control information set and stored in advance according to the work situation at that time. A traveling drive control unit 101 for controlling the plurality of hydraulic motors 6 is provided. The traveling drive control unit 101 controls the operation of the hydraulic motor 6 such that the rotation speed of the traveling wheel 2 detected by the rotation sensor S3 becomes the target speed set in advance based on the above-described control information. I do.

  This work vehicle is provided with an idling state detecting means Q for detecting whether or not the traveling wheel 2 is idling, for example, when traveling on uneven terrain having a lot of irregularities. The idling state detecting means Q detects a pressure sensor S4 for detecting an internal pressure of the hydraulic oil supply passage in the hydraulic motor 6 and, based on information detected by the pressure sensor S4, when the internal pressure falls below a preset value. A determination unit (determination unit 102) that determines that the traveling wheel 2 is in the idling state is configured.

  In addition, as shown in FIGS. 1 and 7, a pressure sensor S4 for detecting the internal pressure of the hydraulic oil supply passage corresponding to each of the four hydraulic motors 6 is provided. Has been entered. Then, the control device 13 compares the input detection value (internal pressure) of the pressure sensor S4 with a preset set value, and determines whether the detected value (internal pressure) of any of the pressure sensors S4 is the set value. When the vehicle speed is lower than the predetermined value, a determination unit 102 is provided as determination means for determining that the corresponding traveling wheel 2 is spinning.

  When there is a traveling wheel 2 determined to be idling by the determination unit 102, the attitude control unit 100 operates the second hydraulic cylinder 30 so as to lower the traveling wheel 2 and detects the pressure sensor S4. When the value (internal pressure) returns to or above the set value, the operation of the second hydraulic cylinder 30 is stopped.

  In addition, the traveling wheel 2 idles when the traveling wheel 2 is lifted off the ground due to the presence of a concave portion on the ground or traveling on a slippery road surface. At this time, it is assumed that the load pressure on the hydraulic motor 6 is greatly reduced. Such a change in the load pressure is detected by the pressure sensor S4, and when the detected value of the pressure sensor S4 falls below the set value, the operation of the second hydraulic cylinder 30 is controlled, so that the traveling wheel 2 is properly driven. This is a state in which force is exerted, and the idling state can be eliminated. As a result, the traveling wheels 2 move up and down while following the unevenness of the ground, and each of the traveling wheels 2 maintains an appropriate ground contact state without idling or hindering rotation. It is possible to drive well on uneven terrain while supporting the vehicle.

[Another embodiment]
(1) In the above embodiment, the idling state detecting means Q is configured by the pressure sensor S4 and the determination unit 102. However, instead of this configuration, the following configuration may be employed.

  That is, a rotation sensor S3 as driving speed detecting means for detecting the driving speed of the hydraulic motor 6, a traveling speed detecting means for detecting the actual traveling speed of the vehicle body 1, and a hydraulic motor 6 detected by the rotation sensor S3. When the driving speed becomes higher than the actual traveling speed detected by the traveling speed detecting means by a set amount or more, the idling state detecting means Q is constituted by the judging means for judging that the traveling wheel 2 is idling. It may be something.

  In addition, as the traveling speed detecting means, for example, an average value of the driving speeds of the four hydraulic motors 6 provided corresponding to the four traveling wheels 2 is obtained, and the traveling speed is obtained from the average value. You may do so. Instead of this configuration, a measuring device that can determine the absolute traveling speed of the work vehicle with respect to the ground using a vehicle speed sensor using a millimeter wave radar may be used.

  Then, the control device 13 compares the drive speed of one hydraulic motor 6 to be measured with the actual travel speed of the vehicle body 1 measured by the travel speed detection means as described above, and determines that the drive speed is When the traveling speed becomes higher than the actual traveling speed by a set amount or more, a process of determining that the traveling wheel 2 is in the idling state is executed to determine the idling state.

(2) In the above-described embodiment, the ascent / descent support mechanism has been described as being constituted by the bending link mechanism 4 in which two links 25 and 26 are pivotally connected. The invention is not limited to the link mechanism, but may be a configuration in which the traveling wheels 2 are supported via a support mechanism having a cylinder structure that can expand and contract with respect to the vehicle body 1 in the vertical direction.

(3) In the above embodiment, the posture changing operation means 5 is configured to include the plurality of hydraulic cylinders 29, 30. Instead of this configuration, the posture changing operation means 5 includes a hydraulic motor, an electric motor, or the like at a pivot point between the links. May be changed.

(4) In the above embodiment, the traveling drive device is configured by the hydraulic motor 6, but instead of this configuration, the travel drive device is driven by an electric motor, or the power of the engine can be continuously changed. Various configurations may be used, such as a configuration in which each is transmitted to the traveling wheels 2 via a simple transmission mechanism.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a work vehicle suitable for traveling on a road surface having a lot of unevenness.

DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Running wheel 4 Elevating support mechanism 5 Attitude change operation means 6 Traveling drive (hydraulic motor)
REFERENCE SIGNS LIST 100 control means 102 determination means S3 drive speed detection means S4 pressure sensor Q idling state detection means

Claims (3)

A plurality of traveling wheels located on each of the front and rear sides on the left and right sides of the vehicle body,
A plurality of traveling drive devices that individually drive each of the plurality of traveling wheels,
An elevating and lowering support mechanism that supports the plurality of traveling wheels individually on the vehicle body so as to be capable of ascending and descending,
A plurality of attitude change operation means capable of individually changing the attitude of the plurality of lifting support mechanisms,
Control means for controlling the operation of the attitude change operation means,
An idle state detecting means for detecting whether or not the traveling wheel is idle is provided,
The control means includes:
A work vehicle which controls the operation of the attitude change operation means so that the lifting / lowering support mechanism lowers the traveling wheel when the traveling wheel is detected to be idling by the idling state detecting means. The traveling drive device is configured by a hydraulic motor,
A pressure sensor for detecting the internal pressure of the hydraulic oil supply passage in the hydraulic motor, and based on the detection information of the pressure sensor, when the internal pressure falls below a preset value, the traveling wheel is idle. The work vehicle according to claim 1, wherein the idling state detection unit is configured by the determination unit that determines that there is a vehicle.   Drive speed detection means for detecting the drive speed of the travel drive device, travel speed detection means for detecting the actual travel speed of the vehicle body, and drive speed of the travel drive device detected by the drive speed detection means The idling state detecting means is constituted by a judging means for judging that the traveling wheel is in an idling state when the traveling speed becomes higher than the actual traveling speed detected by the traveling speed detecting means by a set amount or more. The work vehicle according to claim 1.

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