JP2020001442A - Work vehicle - Google Patents

Abstract

To meet a desire for enabling a vehicle to run with the attitude of a vehicular main body being stabilized although on a road surface with concavities and convexities, and for enabling the vehicle body to smoothly turn and run without an excessive load.SOLUTION: A work vehicle includes: a plurality of bent linkage mechanisms 4 that supports each of a plurality of running wheels 2 to a vehicular main body 1 so as to be freely movable upwardly and downwardly; attitude changing operation means 5 capable of changing the attitude of each of the plurality of bent linkage mechanisms 4; a plurality of turning operation means for supporting each of the plurality of bent linkage mechanisms 4 to the vehicular main body so as to enable a direction change around a vertical axial center; and controlling means 13 for controlling the action of the attitude changing operation means 5 and that of the turning operation means. When a direction change operation is given to either the right and left running wheels 2 located at the front section or the right and left running wheels 2 located at the rear section, the controlling means 13 controls the action of the attitude changing operation means 5 in such a way that the weight-center position of the vehicular main body 1 is displaced toward the opposite side to the side at which the direction changing operation is performed in the vehicle back-and-forth direction.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 each supported on a vehicle body via a link mechanism having two joints capable of swinging about a horizontal axis and capable of bending and extending, and the link mechanism is driven by an electric motor. There has been one that is configured to be able to bend and extend and that the traveling wheel is supported in a state where the direction in the left-right direction is fixed (for example, see Patent Document 1).

JP-A-9-142347

  In the above-described conventional configuration, by changing the height of each of the plurality of traveling devices while bending and extending the link mechanism, it is possible to travel in a state where the posture of the vehicle body is stabilized even on a road surface having a lot of unevenness. However, the link mechanism swings around the horizontal axis and bends and stretches, and the direction of the traveling wheel is constant even when the height changes.

  As a result, when turning the vehicle body in one of the right and left directions, the vehicle body is turned with a speed difference between the left and right traveling wheels, or the vehicle body is provided by using a separately provided robot arm (articulated manipulator). Needs to be changed. In such a configuration, the traveling wheels run while skidding, which is disadvantageous in that the turning operation cannot be performed smoothly, and an excessive force may be applied along the lateral direction, and durability may be reduced. There is.

  Therefore, it has been desired to be able to smoothly and smoothly turn the vehicle body while being able to travel in a state where the posture of the vehicle body is stabilized even on a road surface having a lot of unevenness. .

  The characteristic 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 body, and a plurality of bending link mechanisms for supporting the plurality of traveling wheels individually on the vehicle body so as to be able to move up and down. Posture changing means for individually changing the postures of the plurality of refraction link mechanisms; and a plurality of turning operations for supporting the plurality of refraction link mechanisms on the vehicle body so as to be able to change the orientation about the longitudinal axis. Means, and control means for controlling the operation of the attitude changing operation means and the turning operation means, wherein the control means comprises: the left and right traveling wheels located on the front side or the left and right traveling wheels located on the rear side. When changing the direction of any of the traveling wheels, the position change operation device is controlled so that the center of gravity of the vehicle body moves toward the side opposite to the direction in which the direction change operation is performed in the vehicle longitudinal direction. Lies in controlling the operation.

  According to the present invention, the posture of the vehicle body is stabilized even on a rough road surface by changing the postures of the plurality of refraction link mechanisms and vertically moving the plurality of traveling wheels with respect to the vehicle body. It is possible to run in a state where the vehicle is in a closed state. In addition, by changing the direction of the refraction link mechanism around the longitudinal axis, the left and right directions of the traveling wheels with respect to the vehicle body can be changed. When turning to the left or right, by turning the running wheels in the turning direction, the running drive can be performed in a state where no excessive lateral force is applied to the running wheels.

  Then, when the left and right traveling wheels located on the front side of the vehicle main body are traveling and the direction change operation is performed to turn, the center of gravity of the vehicle main body is on the opposite side to the side on which the direction change operation is performed. That is, the posture changing operation means operates so as to move toward the rear side of the vehicle body. When the left and right traveling wheels located on the rear side are turned by the direction change operation, the posture changing operation means is operated so that the center of gravity of the vehicle body moves toward the front side of the vehicle body.

  The load on the vehicle body on the traveling wheel on the side opposite to the direction to be changed increases, but the load on the vehicle body on the traveling wheel on the direction to be changed decreases. As a result, it is possible to reduce the reaction force from the ground on the traveling wheel whose direction is to be changed, and it is possible to smoothly perform the direction changing operation.

  Therefore, it is possible to smoothly and smoothly perform the turning movement of the vehicle body while being able to travel in a state where the posture of the vehicle body is stabilized even on a road surface having a lot of unevenness. .

  In the present invention, the control means is configured such that the refraction link mechanism located on the side where the direction changing operation is performed in the vehicle body front-rear direction is supported by the refraction link mechanism and the traveling wheel grounded. The posture changing operation means is operated so as to separate the vehicle body, and the bending link mechanism located on the side opposite to the side on which the direction changing operation is performed in the vehicle longitudinal direction is supported by the bending link mechanism. It is preferable that the attitude changing operation means is operated so that the vehicle body approaches the traveling wheel that is grounded.

  According to this configuration, on the side on which the direction change operation is performed, the vehicle body moves upward away from the traveling wheels that are in contact with the ground. On the other hand, on the side opposite to the side on which the direction changing operation is performed, the vehicle body moves downward approaching the traveling wheels that are in contact with the ground. As a result, the vehicle body is inclined forward and backward with the side on which the direction changing operation is performed is located on the upper side and the side opposite to the side on which the direction changing operation is performed is positioned on the lower side. That is, the vehicle main body assumes a posture inclined forward and backward with the position on the side on which the direction changing operation is performed is positioned on the upper side. When the vehicle body tilts back and forth in this manner, the position of the center of gravity of the vehicle body tilts and moves to the lower side.

  In addition, when the vehicle is inclined forward and backward, the load on the vehicle body applied to the traveling wheel on which the direction change operation is performed is smaller than the load applied evenly when the vehicle is in the horizontal posture. In other words, if the front and rear posture of the vehicle body is a horizontal posture, the load is equally applied to the front traveling wheels and the rear traveling wheels, respectively, but when the vehicle body is inclined forward and backward, The load concentrates on the bending link mechanism on the side opposite to the side on which the direction changing operation is performed, and accordingly, the load on the bending link mechanism on the side on which the direction changing operation is performed is reduced. As a result, it is possible to further reduce the load received from the ground on the traveling wheel whose direction is changed.

  In the present invention, the bending link mechanism has a first link whose one end is rotatably supported on the vehicle body around a horizontal axis, and a first link whose one end is connected to the other end of the first link. A second link rotatably pivoted around the other end and having the traveling wheel supported at the other end, wherein the turning operation means can change the orientation of the first link around the longitudinal axis. It is preferable that a turning support portion supported by the vehicle body and a hydraulic cylinder for turning operation for changing the direction of the first link and the second link integrally around the longitudinal axis be provided. It is.

  According to this configuration, the height of the traveling wheel with respect to the vehicle body changes by changing the rocking posture of the first link with respect to the vehicle body and changing the rocking posture of the second link with respect to the first link. Then, each of the first link, the second link, and the traveling wheels supported by the second link are integrally supported by the vehicle body via the turning support portion so as to be rotatable around the longitudinal axis. .

  Even if the rotation operation is performed about the vertical axis, the relative attitude of each of the first link, the second link, and the traveling wheel always maintains the same attitude. However, the operation of changing the position of the refraction link mechanism to change the height of the traveling wheel with respect to the vehicle body can be performed.

  Therefore, for each of the plurality of traveling wheels, the turning operation and the elevating operation with respect to the vehicle body can be smoothly performed separately.

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. FIG. 3 is a schematic plan view of the work vehicle in a turning state. It is a schematic side view of a work vehicle in a turning state. FIG. 3 is a schematic plan view of the work vehicle in a straight traveling state. It is a schematic side view of a work vehicle in a straight traveling state.

  Hereinafter, embodiments 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, a refraction link mechanism 4 as a vehicle body supporting portion for supporting the vehicle body 1 so as to be capable of individually changing the position, and a refraction link mechanism 4. And a plurality of hydraulic motors 6 for individually driving a plurality of traveling wheels 2 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 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 10 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. On the upper side of the storage case 12, a control device 13 is provided as control means for controlling the operation of the valve mechanism 9.

  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 bending link mechanism 4 is supported by the body frame 7 so as to be rotatable around a vertical axis Y via a turning mechanism 16 as turning operation means.

  The turning mechanism 16 includes a vehicle body-side support portion 17 (see FIGS. 3 and 4) as a turning support portion that is connected to the vehicle body frame 7 and rotatably supports the refraction link mechanism 4, and a refraction link mechanism 4. A turning hydraulic cylinder (hereinafter referred to as a turning cylinder) 18 for turning operation 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.

  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 of the second hydraulic cylinders 30 is controlled based on the calculation result. You.

  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.

  The traveling wheel 2 is provided with a rotation sensor S6 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 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. 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. Although not shown, the control device 13 also controls the hydraulic oil for the plurality of hydraulic motors 6.

  When the traveling vehicle is stopped, the control device 13 detects the four first hydraulic cylinders 29 and the four second hydraulic cylinders 30 by the stroke sensors S3 provided in the respective hydraulic cylinders 29, 30. The hydraulic control valve 11 is switched so as to operate the hydraulic cylinders 29 and 30 so that the expansion / contraction operation amount detected by the operation becomes the 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. Position control is performed to switch the hydraulic control valve 11 to operate each hydraulic cylinder 29 so that the detected value corresponds to the posture. On the other hand, 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 that is set and stored in advance.

  Further, when the turning operation is commanded, the control device 13 sets the expansion / contraction operation amount detected by the stroke sensor S3 provided in the turning cylinder 18 to a detection value corresponding to the target turning angle. The swing control for operating the swing cylinder 18 by switching the hydraulic control valve 11 is executed.

  The control device 13 controls the left and right traveling wheels 2 located on the front side or the left and right traveling wheels 2 located on the rear side when performing turning control while the work vehicle is moving and traveling. When any one of the direction changing operations is performed, the operation of the posture changing operation means 5 is performed so that the center of gravity of the vehicle body 1 moves toward the side opposite to the direction in which the direction changing operation is performed in the vehicle longitudinal direction. Control.

  Specifically, the control device 13 causes the refraction link mechanism 4 located on the side of the vehicle body front-rear direction on which the direction changing operation is performed to separate the vehicle body 1 from the traveling wheels 2 that are in contact with the ground. The refraction link mechanism 4, which activates the posture changing operation means 5 and is located on the side opposite to the side on which the direction changing operation is performed in the longitudinal direction of the vehicle body, moves the vehicle body 1 with respect to the traveling wheels 2 which are grounded. The posture changing operation means 5 is operated so as to approach the position.

  In addition, for example, as shown in FIG. 10, when the turning cylinder 18 is operated so that the left and right running wheels 2 on the front side in the vehicle body traveling direction turn leftward as shown in FIG. The left and right front hydraulic cylinders of the left and right bending cylinders 4 support the traveling wheels 2 on the front side of the vehicle body so that the base end of the second link 26 swings upward. The left and right rear sides of the left and right refraction link mechanisms 4 supporting the traveling wheels 2 on the rear side of the vehicle body, respectively, so that the base end side of the second link 26 swings downward. The second hydraulic cylinder 30 is operated. As a result, the vehicle body 1 is switched to the front-back inclined position in which the front side is raised and the rear side is lowered. Then, as shown in FIGS. 12 and 13, the center of gravity of the vehicle body 1 is directed to the side opposite to the side in which the direction change operation is performed in the vehicle body front-rear direction, as compared with the case where the vehicle is traveling straight. Will move.

  By adopting the above-described front-rear inclination posture, the load of the vehicle body 1 on the front traveling wheel 2 that is turned is received, in other words, the traveling wheel 2 serving as a movement resistance when changing the direction is received from the ground. The load can be reduced, and the direction can be changed smoothly.

[Another embodiment]
(1) In the above embodiment, the bending link mechanism 4 located on the side of the front-rear direction where the direction changing operation is performed separates the vehicle main body 1 from the grounded traveling wheel 2 and is located on the opposite side. The configuration is such that the attitude changing operation means 5 is operated so that the bending link mechanism 4 moves the vehicle body 1 closer to the traveling wheel 2 that is in contact with the ground, but instead of this configuration, the direction changing operation is performed. The center of gravity may be moved by sliding a heavy object provided in the vehicle body 1, for example, an engine or the like, in the vehicle front-rear direction from the vehicle body 1 toward the opposite side.

(2) In the above embodiment, the stroke sensor S3 for detecting the amount of expansion / contraction operation of the turning cylinder 18 is provided. However, instead of this configuration, a rotary type sensor provided at the pivot of the first link 25 is used. It is good also as a structure which detects the expansion / contraction operation amount with a potentiometer.

(3) In the above embodiment, the turning mechanism 16 (turning operation means) is provided with the turning cylinder 18, but the turning operation may be performed by an electric motor or a hydraulic motor.

(4) In the above embodiment, the auxiliary wheel 3 is configured to be freely rotatable. However, the auxiliary wheel 3 may be configured to be rotationally driven, or may be configured without the auxiliary wheel 3.

(5) In the above-described embodiment, the traveling wheel 2 is driven by the hydraulic motor 6. However, instead of this configuration, for example, the power of the engine is supplied to the traveling wheel via a mechanical transmission mechanism such as a chain transmission mechanism. 2 may be provided.

  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 Refraction link mechanism 5 Posture change operation means 13 Control means 16 Turning operation means 17 Turning support part 18 Turning cylinder 25 First link 26 Second link

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 refraction link mechanisms for supporting the plurality of traveling wheels individually on the vehicle body so as to be capable of ascending and descending,
Attitude change operation means capable of individually changing the attitude of the plurality of refraction link mechanisms,
A plurality of turning operation means for supporting each of the plurality of refraction link mechanisms on the vehicle body so as to be able to change their orientation around a longitudinal axis,
Control means for controlling the operation of the attitude change operation means and the turning operation means,
The control means includes:
When changing the direction of one of the left and right running wheels located on the front side or the left and right running wheels located on the rear side, the center of gravity position of the vehicle body may be changed in the vehicle longitudinal direction. A work vehicle that controls the operation of the attitude change operation means so as to move toward the side opposite to the side where the operation is performed. The control means includes:
The attitude of the bending link mechanism, which is located on the side of the vehicle body front-rear direction in which the direction changing operation is performed, such that the vehicle body is separated from the traveling wheel supported by the bending link mechanism and grounded; Activating the change operation means, and
The refraction link mechanism, which is located on the side opposite to the side on which the direction changing operation is performed in the vehicle longitudinal direction, moves the vehicle body closer to the traveling wheel supported by the refraction link mechanism and grounded. The work vehicle according to claim 1, wherein the posture changing operation means is operated. In the refraction link mechanism,
A first link having one end rotatably supported on the vehicle body around a horizontal axis, and one end being pivotally connected to the other end of the first link rotatably around the horizontal axis; and The other end is provided with a second link on which the traveling wheel is supported,
In the turning operation means,
A turning support portion that supports the first link on the vehicle body so as to be able to change the direction around the vertical axis, and performs a direction changing operation about the vertical axis integrally with the first link and the second link; The work vehicle according to claim 1 or 2, further comprising a hydraulic cylinder for turning operation.

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