JP2020001444A - Maintenance vehicle - Google Patents

Abstract

To provide a maintenance vehicle capable of maintaining an adequate posture of a vehicle body even in a rugged work field in a work environment high in risk such as intrusion of fine dust or moisture and also capable of traveling to move in such a state as stabilizing with low gravity center.SOLUTION: A maintenance vehicle comprises: a vehicle body 1 with a base; plural traveling wheels 2 located at the front and rear, respectively in both left and right sides of the vehicle body 1; plural inflection linkages 4 supporting plural traveling wheels 2 individually liftably to the vehicle body; hydraulic operation type attitude change operation means 5 capable of changing individually the attitudes of plural inflection linkages 4; and a hydraulic supply source 8 delivering a hydraulic fluid toward the operation means 5. The hydraulic supply source 8 is arranged in such a state as being located in the lower side of the base 7 in the vehicle body 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a work vehicle suitable for traveling on uneven terrain.

  Conventionally, four running wheels are each supported on a main body via a link mechanism having two joints and configured to be able to bend and extend, and the link mechanism is provided with an electric motor and a reduction mechanism, and the driving force of the electric motor is provided. In some cases, the link mechanism is configured to be able to bend and extend (see, for example, Patent Document 1).

JP-A-9-142347

  The wheel support structure in the above-described conventional configuration enables the vehicle to travel while maintaining the body in an appropriate posture while bending and extending the link mechanism even when the traveling road surface has irregularities. Thus, it is conceivable to apply such a wheel support structure to, for example, an agricultural work vehicle traveling in a field, an orchard, a mountain range, or the like. However, the wheel support structure in the above-described conventional configuration has been difficult to employ in these work vehicles.

  In the case of agricultural work vehicles, in the vicinity of the work vehicle, a large amount of fine dust such as dust generated during traveling and floating dust generated from crops caused by harvesting work may be generated, which may be caused by rainwater or morning dew. In some cases, moisture may adhere. In the above-described conventional configuration, the link mechanism for supporting the traveling wheels is driven to bend and stretch by the built-in electric motor. Therefore, when fine dust or moisture enters the link mechanism, the electric motor and the deceleration are reduced. Failure may occur in the mechanism or the like.

  Therefore, in a work environment where there is a great risk of intrusion of fine dust and moisture, the vehicle body can maintain an appropriate posture, even in a work place with a lot of unevenness, and has a low center of gravity and is stable. There has been a demand for a work vehicle capable of moving and traveling in a state where the vehicle is running.

  The characteristic configuration of the work vehicle according to the present invention includes a vehicle body having a base, a plurality of traveling wheels located on each of the front and rear sides on the left and right sides of the vehicle body, and a plurality of the traveling wheels that can be individually raised and lowered. A plurality of bending link mechanisms supported by the vehicle body, a hydraulically operated posture changing operation means capable of individually changing the postures of the plurality of bending link mechanisms, and a hydraulic supply for sending hydraulic oil toward the posture changing operation means And the hydraulic pressure supply source is provided in a state of being located below the base in the vehicle body.

  According to the present invention, it is possible to change the height of each of the plurality of running wheels with respect to the vehicle body by changing the attitude of the refraction link mechanism by the attitude changing operation means, which is useful when traveling on uneven ground. Even when the vehicle body is stably supported on the ground by a plurality of traveling wheels, it is possible to travel with the vehicle body maintained in an appropriate posture.

  Since the posture changing operation means is of a hydraulic operation type, it generally has waterproofness and dustproofness as compared with an electric type. For this reason, even if moisture or dust adheres to the surface, there is little risk of adversely affecting the operation and causing malfunction or the like. Therefore, even in a work environment in which fine dust, moisture, or the like may enter, the posture changing operation can be favorably performed.

  In the apparatus having the hydraulically operated attitude change operation means, a hydraulic supply source for supplying hydraulic oil to the attitude change operation means is required. The hydraulic supply source includes a drive device such as an engine or an electric motor, and a drive device. And a hydraulic pump driven by the motor. A hydraulic supply source equipped with a large device such as an engine or an electric motor is a large device and has a large weight. Such a large and heavy hydraulic supply source is provided under the base in the vehicle body.

  As described above, since the hydraulic supply source, which is a heavy-weight device, is provided below the base, that is, on the lower abdomen of the vehicle body, the position of the center of gravity of the vehicle body is lowered. In other words, when traveling on a work site with a lot of unevenness, the vehicle can be moved and moved in a stable state with a low center of gravity by lowering the position of the center of gravity of the vehicle body as much as possible.

  Therefore, in a work environment where there is a great risk of intrusion of fine dust, moisture, etc., the vehicle body can maintain an appropriate posture even in a work place with a lot of unevenness, and has a low center of gravity and is stable. It is now possible to move and travel in a state where it has been done.

  In the present invention, a support frame for supporting the hydraulic pressure source is provided in a state located below the base and connected to the base, and the support frame supports the hydraulic pressure source. It is preferable that the base can be attached to and detached from the base by being moved in the lateral direction of the vehicle body in this state.

  According to this structure, the hydraulic pressure source can be stably supported by the support frame connected to the base and having sufficient support strength. Further, since the support frame can be attached to and detached from the base by moving the support frame along the lateral direction of the vehicle body, compared to a configuration in which only the hydraulic supply source is attached and detached in a narrow area below the vehicle body, The work of attaching and detaching can be easily performed, and the maintenance work such as inspection and repair can be performed in a state where the hydraulic supply source is detached from the vehicle body and the work is easy.

  In the present invention, it is preferable that the support frame is configured to be capable of holding the posture of the entire vehicle body in a state where the lower end portion is in contact with the ground.

  According to this configuration, when the position of the work vehicle is held in a stopped state, the posture of the bending link mechanism is changed so that the plurality of traveling wheels float above the ground, and the support frame is grounded. Thus, the vehicle body can be supported on the ground in a state where movement is prevented while maintaining the posture of the entire vehicle body.

  In the present invention, it is preferable that the hydraulic supply source includes an engine and a hydraulic pump driven by the engine.

  According to this configuration, the hydraulic pump is driven by the large power of the engine, and a sufficient amount of hydraulic oil can be supplied to the posture changing operation means, so that the posture changing operation can be performed smoothly and quickly.

  In the present invention, the refraction link mechanism has a first link having one end rotatably supported on the base around a horizontal axis, and a first link having one end mounted on the other end of the first link. A second link rotatably supported around the other end and the traveling wheel supported at the other end, wherein the attitude changing operation means can change the swing attitude of the first link with respect to the base. Preferably, there are provided a first hydraulic cylinder and a second hydraulic cylinder capable of changing a swing posture of the second link with respect to the first link.

  According to this configuration, the first link and the second link are rotatably connected around the horizontal axis to form a bending link mechanism, and the first hydraulic cylinder changes the swing posture of the first link with respect to the vehicle body. Then, the posture of the bending link mechanism is changed by changing the swing posture of the second link with respect to the first link by the second hydraulic cylinder. Since the two postures of the pivotally connected links are individually changed by the two hydraulic cylinders, the posture change operation can be performed smoothly.

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 of a support frame. It is a top view of a support frame. It is a front view of a support 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.

  The work vehicle is provided corresponding to each of the vehicle body 1, which supports the entire vehicle, has a substantially rectangular shape in plan view, a plurality of (specifically, four) traveling wheels 2, and the plurality of traveling wheels 2. A plurality of auxiliary wheels 3, a plurality of traveling wheels 2, and a refraction link mechanism 4 as a vehicle body supporting portion for supporting the vehicle body 1 so as to be capable of changing their positions separately, and a hydraulically driven type capable of changing the refraction link mechanism 4. An attitude change operation means 5 and a plurality of hydraulic motors 6 for driving the plurality of traveling wheels 2 separately are provided. 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 includes a body frame 7 as a rectangular frame-shaped base for supporting the whole, a hydraulic supply source 8 for sending hydraulic oil toward the posture changing operation means 5, and a posture changing operation means from the hydraulic supply source 8. And a valve mechanism 9 for controlling the hydraulic oil supplied to the valve 5. 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 frame 10 connected to the lower side of the vehicle body frame 7, and is provided in a state of being located at a 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.

  In addition, as shown in FIGS. 8, 9, and 10, the support frame 10 includes a pair of left and right bottom receiving members 10A formed by bending a round pipe material into a substantially U shape in side view, and front and rear sides of the bottom receiving member 10A. The end portions are connected to each other, and a pair of front and rear lateral support members 10B made of a round pipe material provided so as to extend to both left and right sides are integrally connected to form a frame. A pair of front and rear engine supports 10C are placed and connected by bolts over the left and right bottom receiving members 10A.

  A connection bracket 10D made of a laterally open channel material is connected to the upper part of the left and right end portions of the pair of front and rear lateral support members 10B. The left and right connection brackets 10D are open in the same direction, and are mounted laterally from one direction on a rectangular tubular front-rear frame 19 provided on both left and right lateral portions of the body frame 7 of the vehicle body 1. It is configured to be connected by bolts. In addition, a ground support 10E is provided below the pair of bottom receiving members 10A to support the ground receiving member 10A in a non-slip state while being grounded. Therefore, the support frame 10 is configured to be able to hold the posture of the entire vehicle body with the lower end portion in contact with the ground.

  The hydraulic supply source 8 is configured by integrally connecting an engine and a hydraulic pump, and the hydraulic supply source 8 is mounted and supported by front and rear engine supports 10C via a vibration-proof rubber G. The hydraulic pressure source 8 is provided so as to be housed under the vehicle body frame 7.

  Then, by removing the support frame 10 from the vehicle body frame 7 while supporting the hydraulic supply source 8, the hydraulic supply source 8 can be slid laterally from the vehicle body 1 and removed. By attaching the support frame 10 to the vehicle body frame 7, the support frame 10 can be slid laterally and attached.

  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.

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 bending link mechanism 4 is supported by the vehicle body frame 7 via a turning 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 arranged from the lateral outside to the rectangular tubular front-facing frame body 19 provided at the lateral portion of the vehicle body frame 7. A connecting member 20 that is fitted and engaged in a sandwiched state and is removably bolt-connected, an outer-side pivotal support bracket 21 located at a position on the outer side of the connecting member 20 in the vehicle longitudinal direction, and a vehicle body of the connecting member 20. An inner pivot bracket 22 located at an inner portion in the front-rear direction, and a vertical pivot support shaft 23 supported by the outer pivot bracket 21 are provided. The refraction link mechanism 4 is rotatably supported around Y.

  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 integrally formed while maintaining the relative posture constant. , Around the horizontal axis X <b> 1 at the pivotal connection point 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.

  This work vehicle includes various sensors. Specifically, as shown in FIGS. 1 and 7, each of the four second hydraulic cylinders 30 includes a head-side pressure sensor S1 and a cap-side pressure sensor S2. The head-side pressure sensor S1 detects the oil pressure in the head-side chamber of the second hydraulic cylinder 30. The cap-side pressure sensor S2 detects the oil pressure in the cap-side chamber of the second hydraulic cylinder 30. The detection results of the pressure sensors S1 and S2 are input to the control device 13.

  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 S3 capable of detecting an expansion / contraction 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 stroke sensor S3 corresponds to a position detection sensor. The detection result of each stroke sensor S3 is input to the control device 13.

  The mounting positions of the pressure sensors S1 and S2 are not limited to the positions described above. Each of the pressure sensors S1 and S2 only needs to be able to detect (estimate) the oil pressure of the corresponding cap-side chamber or head-side chamber, and may be provided in a pipe from the valve mechanism 9 to the corresponding cap-side chamber or head-side chamber.

  The thrust required to support the vehicle body 1 is calculated based on the detection results of these sensors S1 and S2, and the supply of hydraulic oil to each second hydraulic cylinder 30 is controlled based on the calculation result. You.

  As shown in FIGS. 1 and 2, the vehicle body 1 is provided with an acceleration sensor S5 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 S5, 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.

  As shown in FIG. 1, the traveling wheel 2 is provided with a rotation sensor S6 for detecting a rotation speed of the traveling wheel 2 driven by a 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 S6 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, the attitude change 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. Although not shown, the control device 13 also controls hydraulic oil for the plurality of hydraulic motors 6 and controls hydraulic oil for the swing cylinder 18.

  Although not described in detail, the control device 13 controls the posture of the vehicle body 1 based on control information input by manual operation or control information stored in advance according to the work situation at that time. The control is performed so as to bring the state into an appropriate state.

  When the traveling vehicle is stopped, the control device 13 determines, for the four first hydraulic cylinders 29 and the four second hydraulic cylinders 30, the stroke sensors provided in the respective hydraulic cylinders 29, 30. Position control for operating the hydraulic cylinders 29 and 30 by switching the hydraulic control valve 11 is performed so that the expansion / contraction operation amount detected in S3 becomes a detection value corresponding to the target posture.

  When the work vehicle travels on uneven terrain with a lot of irregularities, for the four first hydraulic cylinders 29, the expansion / contraction operation amount detected by the stroke sensor S3 provided in each hydraulic cylinder 29 is the target posture. Is performed to switch the hydraulic control valve 11 so as to operate each hydraulic cylinder 29 so that the detected value corresponds to the detected value.

  The operation of the four second hydraulic cylinders 30 is controlled based on the detection information of the pressure sensors S1 and S2. Specifically, the thrust of the second hydraulic cylinder 30 is calculated based on the detection value of the head-side pressure sensor S1 and the detection value of the cap-side pressure sensor S2. Then, the operation of the second hydraulic cylinder 30 is controlled by switching the hydraulic control valve 11 so that the detected thrust becomes a target value which is set and stored in advance.

  In addition, when the recess is present on the ground and the traveling wheel 2 is lifted off the ground, the ground reaction force is reduced and the traveling wheel 2 runs idle. At this time, it is assumed that the thrust of the second hydraulic cylinder 30 becomes small. On the other hand, when the traveling wheel 2 rides on the protrusion on the ground, the ground contact reaction force increases, and the rotation of the traveling wheel 2 is hindered. At this time, it is assumed that the thrust of the second hydraulic cylinder 30 increases. Such a change in the ground reaction force is detected by the pressure sensors S1 and S2, and the operation of the second hydraulic cylinder 30 is controlled such that the thrust detected based on the detection results of the pressure sensors S1 and S2 becomes a target value. Thus, the ground reaction force of the traveling wheels 2 is maintained at an appropriate value. 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 support frame 10 is detachably mounted on the vehicle body 1 by detaching or attaching the support frame 10 to or from the vehicle body frame 7 so that the hydraulic supply 8 is slid laterally. However, instead of this configuration, the hydraulic supply source 8 may be slid laterally with respect to the support frame 10 so as to be mounted and detachable.

(2) In the above-described embodiment, the support frame 10 is provided with the grounding support 10E that is grounded in a non-slip state. However, instead of this configuration, for example, a plurality of A configuration in which a caster wheel is provided and the grounding support is provided by the caster wheel may be employed. In this case, it is preferable to provide a stopper member that can be switched between a state in which the caster wheel freely rotates and a state in which the rotation is restricted.

(3) In the above embodiment, the hydraulic supply source 8 includes the engine and the hydraulic pump driven by the engine. However, the hydraulic pump 8 may be driven by an electric motor instead of the engine.

(4) In the above embodiment, the posture changing operation means 5 is configured to include the plurality of hydraulic cylinders 29, 30. However, instead of this configuration, the posture is changed by providing a hydraulic motor at a pivot point between the links. It may be.

(5) In the above embodiment, the traveling wheel 2 is driven by the hydraulic motor 6. However, instead of this configuration, the traveling wheel 2 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 uneven terrain.

DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Running wheel 4 Refraction link mechanism 5 Attitude change operation means 7 Base (body frame)
8 Hydraulic supply source 10 Support frame 25 First link 26 Second link 29 First hydraulic cylinder 30 Second hydraulic cylinder

Claims (5)

A vehicle body with a base,
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 refraction link mechanisms for supporting the plurality of traveling wheels individually on the vehicle body so as to be capable of ascending and descending,
A hydraulically operated attitude change operation means capable of individually changing the attitudes of the plurality of bending link mechanisms,
A hydraulic supply source for sending hydraulic oil toward the attitude change operation means,
A work vehicle provided with the hydraulic supply source disposed below the base in the vehicle body. A support frame that supports the hydraulic supply source is provided in a state that is located below the base and is connected to the base,
2. The work vehicle according to claim 1, wherein the support frame can be attached to and detached from the base by moving the support frame in a lateral direction of the vehicle body while supporting the hydraulic supply source. 3.   The work vehicle according to claim 2, wherein the support frame is configured to be able to hold the posture of the entire vehicle body in a state where a lower end portion is in contact with the ground.   The work vehicle according to any one of claims 1 to 3, wherein the hydraulic supply source includes an engine and a hydraulic pump driven by the engine. A first link having one end rotatably supported around the horizontal axis on the base and one end rotatable about the horizontal axis at the other end of the first link; A second link supported on the other end and the traveling wheel is supported on the other end,
A first hydraulic cylinder capable of changing a swing posture of the first link with respect to the base, and a second hydraulic cylinder capable of changing a swing posture of the second link with respect to the first link; The work vehicle according to any one of claims 1 to 4, further comprising:

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