Work vehicle

Abstract

To provide a work vehicle that can move and travel well even in a narrow and limited work area or a work area or the like in which a traveling road surface is inclined.SOLUTION: A work vehicle comprises: a plurality of support mechanisms A configured to support a plurality of traveling wheels 2, located at front and rear positions on both left and right sides, respectively such that positions of the traveling wheels are individually changeable with respect to a vehicle body 1; a plurality of steering mechanisms capable of individually changing directions of the plurality of traveling wheels 2; travel drive means configured to individually rotationally drive the plurality of traveling wheels 2; and a control device C configured to control operations. The control device C controls the operation of the plurality of steering mechanisms in accordance with a travel mode commanded by travel mode command means MS.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a work vehicle suitable for moving on sloping ground, uneven ground with irregularities, etc.

Background Art

[0002] Conventionally, as such a work vehicle, four traveling wheels driven by a hydraulic motor are supported with respect to a vehicle body via a folding link mechanism that can be expanded and contracted by operating a hydraulic cylinder, and the height of the traveling wheels is changed. Thus, there is a vehicle configured to be able to travel while maintaining the posture of the vehicle body even on sloping ground or the like. And in this work vehicle, as a turning travel mode when performing turning travel, only a turning travel mode in which the directions of only the left and right traveling wheels located on the front side or the rear side are changed to perform turning travel has been used (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional configuration, when performing turning travel, always, only the left and right traveling wheels on either the front side or the rear side are turned to travel. With this configuration, there is little risk of problems when traveling on a flat ground that is widely open such as a farm field.

[0005] However, in a work vehicle suitable for moving on uneven ground, for example, it may be necessary to move in mountainous areas or orchards where the ground is sloping. In such a work area, there are many obstacles such as standing trees, and the work area is narrow and limited, or when turning travel may be performed in a work area where the traveling road surface is sloping.

[0006] In the conventional configuration described above, the vehicle's movement becomes wide when turning, which could make it difficult to move around in narrow, limited work areas or on slopes.

[0007] Therefore, there was a need to enable smooth movement and operation even in narrow, limited work areas or work areas with inclined surfaces. [Means for solving the problem]

[0008] The characteristic configuration of the work vehicle according to the present invention includes a vehicle body, a plurality of running wheels located at the front and rear on both the left and right sides of the vehicle body, a plurality of support mechanisms that support the plurality of running wheels so that their position can be changed individually relative to the vehicle body, a plurality of steering mechanisms that can change the direction of the plurality of running wheels individually, a driving means that drives the plurality of running wheels to rotate individually, a control device that controls the operation of the plurality of driving means and the plurality of steering mechanisms, and a driving mode command means that commands the control device to switch between a plurality of driving modes in which the operating modes of the steering mechanisms are mutually different, wherein the control device controls the operation of the plurality of steering mechanisms according to the driving mode commanded by the driving mode command means. Furthermore, the driving mode command means is a push-type switch that commands switching of the driving mode with a press operation shorter than the set time, and commands switching to a mode different from the driving mode with a press operation longer than the set time. It lies in that point.

[0009] According to the present invention, the operator commands an appropriate driving mode using the driving mode command means according to the differences in the work situation at the time. The control device switches to the commanded driving mode and controls the operation of the multiple driving means and multiple steering mechanisms.

[0010] As a result, for example, in a wide, open work area, the vehicle can move smoothly while ensuring driving stability by making gentle turns. On the other hand, in a narrow, limited work area, it can perform work maneuvers that are appropriate to the work situation at the time, such as making sharp turns or moving diagonally to avoid collisions with obstacles.

[0011] Therefore, it becomes possible to ensure smooth movement and operation even in narrow, limited work areas or on sloping ground.

[0012] In the present invention, the mode different from the driving mode is an operation mode, and it is preferable that the driving mode command means commands switching between the remote control operation mode and the machine-side operation mode by pressing the button for a longer duration than the set time. In the present invention, the vehicle body is provided with a loading section located on the upper surface and capable of loading luggage, and an operating section located behind the loading section, and the driving mode command means is preferably provided in the operating section. In the present invention, it is preferable that the control device is switchable between a plurality of driving modes, namely a two-wheel steering mode in which only the left and right driving wheels located on the front or rear side are changed in direction, and a four-wheel steering mode in which the left and right driving wheels on both the front and rear sides are changed in direction.

[0013] With this configuration, when traveling in a wide, open work area, the vehicle switches to two-wheel steering mode. In this mode, only the left and right wheels located at the front or rear change direction, while the other wheels do not change direction, making it possible to perform relatively gentle turns with a larger turning radius.

[0014] When driving in a narrow, limited work area, the vehicle switches to four-wheel steering mode. In this driving mode, the direction of both the left and right wheels at the front and rear can be changed, making it possible to drive while making sharp turns with a small turning radius. As a result, even in work environments with many obstacles such as trees, the vehicle can drive smoothly with little risk of collision with obstacles.

[0015] In the present invention, it is preferable that the vehicle can be switched to a super-pivot turning mode as the driving mode, which changes the direction of the left and right driving wheels on both the front and rear sides so that the center of the vehicle body is the turning center in a plan view.

[0016] With this configuration, in super-pivot turning mode, the vehicle body can rotate (spin turn) around its central point to change its orientation. Therefore, the orientation of the vehicle body can be changed within a limited, narrow area without moving the vehicle body forward or backward.

[0017] In the present invention, it is preferable that the driving mode can be switched to a diagonal driving mode in which the left and right driving wheels on both the front and rear sides are oriented in the same direction.

[0018] According to this configuration, in the diagonal running mode, the vehicle body can move parallel in a diagonal direction with respect to the longitudinal direction of the vehicle body. For example, when there are obstacles in front of or behind the vehicle body and it is impossible to perform turning running, it is possible to move while avoiding the obstacles by moving the vehicle body in a diagonal direction.

[0019] In the present invention, the support mechanism is provided with a plurality of folding link mechanisms having one end supported by the vehicle body and the other end supporting the traveling wheels, and a plurality of hydraulic cylinders for changing the posture of the folding link mechanism individually. It is preferable that the traveling driving means is a hydraulic motor and the steering mechanism is a hydraulic cylinder for turning operation.

[0020] According to this configuration, each of the position change operation of the traveling wheels with respect to the vehicle body, the direction change operation of the traveling wheels, and the rotational drive operation of the traveling wheels is performed by hydraulic operation. Since a work vehicle traveling on uneven ground may be affected by moisture, mud, etc., if various operations are performed using an electric motor or the like, it is easily affected by the adverse effects of moisture and the like. However, in the case of operating by hydraulic operation as in this configuration, it is difficult to be affected by moisture and the like and it is possible to continue a good operating state for a long time.

Brief Description of the Drawings

[0021] [Figure 1] [[ID=第十九]]It is a side view of the work vehicle. [Figure 2] It is a plan view of the work vehicle. [Figure 3] It is a rear view of the work vehicle. [Figure 4] It is a side view of the support mechanism. [Figure 5] It is a plan view of the support mechanism. [Figure 6] It is a control block diagram. [Figure 7] It is a view showing a turning running state. [Figure 8] It is an explanatory view when the string member is attached. [Figure 9] This is a side view showing the usage state when the string component is attached. [Figure 10] This is a flowchart of the control operation. [Figure 11] This is a side view of the vehicle when driving on an incline. [Figure 12] This is a diagram showing the operation control unit of the second embodiment. [Figure 13] This is a flowchart of the control operation of the second embodiment. [Figure 14] This diagram shows the turning and driving state in super-tight turning mode. [Figure 15] This figure shows the driving state of another embodiment. [Modes for carrying out the invention]

[0022] Embodiments of the work vehicle of the present invention will be described based on the drawings. In the following description, the direction of arrow FW in the drawings will be referred to as "forward", the direction of arrow BK as "rear", the direction of arrow RH as "right", the direction of arrow LH as "left", the direction of arrow UP as "up", and the direction of arrow DW as "down".

[0023] [First Embodiment] The first embodiment will be described below. As shown in Figures 1 to 3, the work vehicle is equipped with a vehicle body 1 that is roughly rectangular in shape in plan view and supports the entire vehicle, a plurality of running wheels 2 that support the vehicle body 1, a plurality of auxiliary wheels 3 provided corresponding to each of the plurality of running wheels 2, a support mechanism A that supports the plurality of running wheels 2 so that their positions can be changed relative to the vehicle body 1, and a plurality of hydraulic motors 4 as driving means for driving each of the plurality of running wheels 2 individually.

[0024] The running wheels 2 are located at the front and rear on both the left and right sides of the vehicle body 1. In this embodiment, the work vehicle is equipped with four running wheels 2: left front, right front, left rear, and right rear. It is also equipped with four support mechanisms A: left front, right front, left rear, and right rear. Each support mechanism A comprises a bending link mechanism 5 as a vehicle body support and a plurality of hydraulic cylinders 6, 7 as attitude-changing actuators that can individually change the attitude of the bending link mechanism 5.

[0025] The vehicle body 1 is roughly rectangular in plan view, and a flat loading section 8 capable of loading cargo is provided on the upper surface of the vehicle body 1. The loading section 8 is formed in a roughly rectangular shape in plan view and extends from the right end to the left end of the vehicle body 1. The loading section 8 is configured so that cargo can be placed on it. Examples of cargo that can be placed on the loading section 8 include agricultural machinery, agricultural materials such as fertilizers and chemicals, harvested produce and harvesting baskets, and pallets on which these are placed.

[0026] The vehicle body 1 is equipped with a hydraulic supply source 9 located below the loading section 8 that supplies hydraulic fluid to the hydraulic cylinders 6 and 7 and the hydraulic motor 4, a control device C that adjusts the supply state of hydraulic fluid from the hydraulic supply source 9 to control the operation of the hydraulic cylinders 6 and 7 and the hydraulic motor 4, a battery 11 for power supply, and the like.

[0027] The hydraulic power source 9 includes an engine 9a, a hydraulic pump 9b driven by the engine 9a, a hydraulic oil tank 9c, a fuel tank 9d for storing fuel for the engine 9a, and the like. The hydraulic power source 9 is supported by the underframe 10. The fuel tank 9e is located at a high position on the front of the vehicle body 1. The battery 11 is charged by a generator driven by the power of the engine 9a.

[0028] The control device C is equipped with a hydraulic control valve 12 that adjusts the supply state of hydraulic fluid from the hydraulic supply source 9, and an ECU (Electronic Control Unit) 13 that controls the operation of the hydraulic control valve 12. The ECU 13 is equipped with a microcomputer and can perform various controls according to the control program.

[0029] [Support mechanism] As described above, the support mechanism A comprises an articulated link mechanism 5 and a plurality of hydraulic cylinders 6 and 7. As shown in Figure 1, the four running wheels 2 are individually supported relative to the vehicle body 1 via the articulated link mechanism 5 so as to be able to move up and down.

[0030] As shown in Figures 4 and 5, the articulated link mechanism 5 includes a base end 14 supported by the vehicle body 1, a first link 15 whose upper end is supported at the lower part of the base end 14 so as to be rotatable around a horizontal axis X1, and a second link 16 whose one end is supported at the lower end of the first link 15 so as to be rotatable around a horizontal axis X2 and whose other end is supported by a running wheel 2.

[0031] A support bracket 17 supporting the running wheel 2 is supported by a boss portion 18 provided at the swing-side end of the second link 16 so as to be able to swing around the vertical axis Y. A hydraulic cylinder 20 for turning operation as a steering mechanism (hereinafter referred to as the slewing cylinder) is provided extending from the bracket 19 at one end of the second link 16 to the arm portion 17a provided on the support bracket 17.

[0032] Each of the multiple articulated link mechanisms 5 is equipped with multiple hydraulic cylinders 6 and 7 that can individually change the orientation of each articulated link mechanism 5. Specifically, there is a first hydraulic cylinder 6 that can change the swinging orientation of the first link 15 relative to the vehicle body 1, and a second hydraulic cylinder 7 that can change the swinging orientation of the second link 16 relative to the first link 15.

[0033] When the first hydraulic cylinder 6 is extended or retracted while the operation of the second hydraulic cylinder 7 is stopped, the first link 15, the second link 16, and the running wheel 2 each oscillate together around the horizontal axis X1 of the pivot connection point to the base end 14 while maintaining a constant relative posture. When the second hydraulic cylinder 7 is extended or retracted while the operation of the first hydraulic cylinder 6 is stopped, the second link 16 and the running wheel 2 oscillate together around the horizontal axis X2 of the connection point between the first link 15 and the second link 16, while maintaining a constant posture of the first link 15.

[0034] Auxiliary wheels 3 are rotatably supported at the intermediate bending points of each of the multiple bending link mechanisms 5. The auxiliary wheels 3 are made of wheels with a smaller diameter than the running wheels 2. The pivot shaft that pivotally connects the first link 15 and the second link 16 is extended so as to protrude outward in the width direction of the vehicle body, and the auxiliary wheels 3 are rotatably supported at the extended protruding portion of the pivot shaft.

[0035] By operating the swivel cylinder 20, the travel wheels 2 can be rotated around the vertical axis Y relative to the articulating link mechanism 5, thereby enabling a swivel operation.

[0036] The hydraulic fluid is supplied and discharged by the hydraulic control valves corresponding to the multiple first hydraulic cylinders 6, multiple second hydraulic cylinders 7, and the slewing cylinder, thereby changing the position of each running wheel relative to the vehicle body. Furthermore, the flow rate of the hydraulic fluid is adjusted by the hydraulic control valve 12 corresponding to the hydraulic motor 4, thereby changing the rotational speed of the hydraulic motor 4, and thus the rotational speed of the running wheels 2.

[0037] [Sensor] This work vehicle is equipped with various sensors. As shown in Figure 6, each of the four second hydraulic cylinders 7 is equipped with a head-side pressure sensor S1 and a cap-side pressure sensor S2. The head-side pressure sensor S1 detects the internal pressure of the oil chamber in the head-side chamber of the second hydraulic cylinder 7. The cap-side pressure sensor S2 detects the internal pressure of the oil chamber in the cap-side chamber of the second hydraulic cylinder 7.

[0038] Each of the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7 is equipped with multiple stroke sensors S3 capable of detecting the extension and retraction amount. The extension and retraction amount of each hydraulic cylinder 6, 7 is a detected value corresponding to the swing position of the first link 15 and the second link 16 that are being operated.

[0039] The vehicle body 1 is equipped with a tilt sensor S4 that detects the tilt state of the vehicle body. The tilt sensor S4 is an inertial measurement device with a well-known configuration. It is configured using an IMU (Inertial Measurement Unit). The IMU has a three-axis accelerometer and a gyroscope, and can detect changes in the attitude of the vehicle body 1, specifically, tilt in the longitudinal and lateral directions.

[0040] A rotation sensor S5 is provided near the travel wheel 2 to detect the rotational speed of the travel wheel 2, which is driven by a hydraulic motor 4. Based on the rotational speed of the travel wheel 2 detected by the rotation sensor S5, the supply of hydraulic fluid to the hydraulic motor 4 is controlled so that the rotational speed of the travel wheel 2 reaches a target value. A pressure sensor S6 is provided to detect the pressure of the hydraulic fluid supplied to the hydraulic motor 4. Based on the hydraulic fluid pressure detected by the pressure sensor S6, the supply (pressure) of hydraulic fluid to the hydraulic motor 4 is controlled so that the driving torque of the travel wheel 2 reaches a target value. Each of the four slewing cylinders 20 is equipped with a stroke sensor S7 capable of detecting the extension and retraction amount.

[0041] [Operation Control Panel] A driver control unit 21 is provided at the rear of the loading section 8 of the vehicle body 1. The driver control unit 21 can be manually operated by the driver from outside the vehicle. The vehicle can be operated by the driver using the driver control unit 21. In addition to operation with the driver control unit 21, the vehicle can also be operated remotely using a wireless remote control device RC.

[0042] The driver control unit 21 is supported by a support frame 22. The support frame 22 is located on both the left and right sides and extends in a cantilevered manner from the rear end of the vehicle body 1 toward the rear. A roughly rectangular box-shaped storage case 23 is provided that spans both the left and right support frames 22.

[0043] The rear end of the support frame 22 is fixedly equipped with a handle section 24 that can be manually gripped and operated by the driver from the outside of the vehicle body. The handle section 24 is formed by bending a round pipe into a loop shape when viewed from the front. The driver can support the vehicle by gripping and operating the handle section 24 with one hand, while operating switches described later with the other hand.

[0044] The rear end of the storage case 23 is equipped with an operation panel 25 that is tilted downwards. The operation panel 25 is equipped with three operation switches SW1, SW2, and SW3 arranged horizontally. The first operation switch SW1, located on the left, has the function of switching the driving mode when the vehicle is running, and also the function of switching between a manual operation mode in which the vehicle is operated by the operation unit 21 and a remote operation mode in which the vehicle is operated by the remote control device RC. Therefore, the first operation switch SW1 corresponds to the driving mode command means MS.

[0045] The second control switch SW2, located in the middle of the left and right sides, has the function of switching the control mode when controlling the vehicle's attitude. The third control switch SW3, located on the right side, has the function of switching the target speed when the vehicle is traveling.

[0046] The above operating switches SW1, SW2, and SW3 are momentary push switches. They are normally in the off state, become on while being pressed, and return to the off state when the press is released. The specific operations based on the operation of each operating switch SW1, SW2, and SW3 will be explained later.

[0047] An operating lever 29 for commanding the movement of the vehicle is provided on the upper side of the middle section of the storage case 23. The operating lever 29 is composed of a rod-shaped member that extends vertically. The operating lever 29 is a so-called joystick-type operating device and is supported so that it can be swung in both the forward / backward and left / right directions from a neutral position in an upright position. The operating lever 29 is biased to return to the neutral position by a spring (not shown). Therefore, when the operator releases their hand, the operating lever 29 returns to the neutral position and the movement of the vehicle stops.

[0048] As shown in Figure 6, the base end of the operating lever 29 is equipped with a front-to-back position sensor 30 capable of detecting front-to-back swinging of the operating lever 29 from its neutral position, and a left-to-right position sensor 31 capable of detecting left-to-right swinging from its neutral position. The detection results of each of these sensors 30 and 31 are input to the ECU 13, which will be described later. The front-to-back position sensor 30 and the left-to-right position sensor 31 are configured using potentiometers, and by determining the level of the potentiometer corresponding to the amount of operation of the operating lever 29, it is possible to detect whether a swing operation has been performed to the front, rear, left, or right from the neutral position.

[0049] As shown in Figure 8, a gripping part 29A is provided at the top of the operating lever 29, and a connector 32 is provided midway up or down the operating lever 29 as a connecting part to which one end of a string member can be connected. The connector 32 is formed in the shape of a ring. A string member HU can be connected to this connector 32 so that the driver can pull it from a location away from the vehicle body. Note that the configuration of the connector 32 is not limited to this, and for example, one end of the string member HU may be directly tied to a connecting part such as a hole or hook (neither of which is shown) provided on the operating lever 29, or a connector provided on one end of the string member HU may be connected.

[0050] As shown in Figure 9, when the driver pulls the string member HU from a point in front of the vehicle body 1, the operating lever 29 is swung forward. When the driver pulls the string member HU from a point in rear of the vehicle body 1, the operating lever 29 is swung backward. When the driver pulls the string member HU from a point in right side of the vehicle body 1, the operating lever 29 is swung to the right. When the driver pulls the string member HU from left side of the vehicle body 1, the operating lever 29 is swung to the left.

[0051] An emergency stop switch 33 is provided between the operating lever 29 and the operating panel 25. When the emergency stop switch 33 is pressed, it forcibly stops the operation of the engine 9a and stops the vehicle from moving.

[0052] [Regarding vehicle control] The ECU13 includes a non-volatile memory (not shown) for storing programs corresponding to the functional units described later, and a CPU (not shown) for executing said programs. The functions of each functional unit are realized when the program is executed by the CPU. The ECU13 includes a posture control unit 100 and a driving control unit 101 as functional units.

[0053] The attitude control unit 100 performs attitude control to control the vehicle's posture to a desired state based on detection information from various sensors. There are two control modes for attitude control: position control mode and pressure control mode. Switching between position control modes is performed by operating the second operation switch SW2.

[0054] In position control mode, the operation of the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7 is controlled based on the detection information from the tilt sensor S4 and the stroke sensor S3, so that the tilt angle in the longitudinal direction and the tilt angle in the lateral direction of the vehicle body 1 from the horizontal position corresponds to the horizontal position, so that the loading section 8 of the vehicle body 1 is in a horizontal position. Specifically, the hydraulic control valves 12 corresponding to the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7 are switched and controlled. As a result, for example, as shown in Figure 11, the vehicle body can maintain a nearly horizontal position even when traveling on an incline, and can move without tipping over even if harvesting containers, equipment, etc. are loaded on the loading section.

[0055] In pressure control mode, the thrust of the second hydraulic cylinder 7 is calculated based on the detected values ​​of the head-side pressure sensor S1 and the cap-side pressure sensor S2. The operation of the four second hydraulic cylinders 7 is then controlled by switching the hydraulic control valve 12 so that the detected thrust becomes a preset target value. This control maintains the ground contact reaction force of the running wheels 2 at an appropriate value. As a result, the running wheels 2 move up and down while following the unevenness of the ground, and the vehicle can travel smoothly on uneven terrain while maintaining an appropriate ground contact state and supporting the vehicle body 1 without any of the running wheels 2 slipping or having their rotation hindered.

[0056] Switching between control modes in attitude control is performed by operating the second operation switch SW2. That is, each time the second operation switch SW2 is pressed, it alternates between position control mode and pressure control mode.

[0057] The driving control unit 101 switches the vehicle's driving state to a desired driving state based on the operation command from the driving operation unit 21. Although not shown in the figures, the remote control device is equipped with an operating tool that has a similar function to the operating lever 29 on the driving operation unit 21, and can command the movement of the vehicle body remotely.

[0058] The driving control unit 101 switches the vehicle's driving state based on the operation state of the operating lever 29 provided on the driving operation unit 21, that is, based on the detection results of the front-rear position sensor 30 and the left-right position sensor 31. Specifically, when the front-rear position sensor 30 detects that the operating lever 29 has been operated forward, the vehicle drives straight ahead. When the front-rear position sensor 30 detects that the operating lever 29 has been operated backward, the vehicle drives straight backward. When the left-right position sensor 31 detects that the operating lever 29 has been operated to the right, the vehicle turns to the right. When the left-right position sensor 31 detects that the operating lever 29 has been operated to the left, the vehicle turns to the left.

[0059] The travel control unit 101 is configured to allow the operation of the slewing hydraulic cylinder 20 to be switched between multiple travel modes that differ from each other, and controls the operation of multiple hydraulic motors 4 and multiple slewing cylinders 20 so that the vehicle sles and travels in the travel mode commanded based on a command from the first operation switch SW1.

[0060] Furthermore, the driving control unit 101 can switch between several driving modes for turning, including a two-wheel turning mode (two-wheel steering mode) in which only the left and right driving wheels 2 located at the front or rear are changed in direction, and a four-wheel turning mode (four-wheel steering mode) in which the direction of both the left and right driving wheels 2 at the front and rear is changed.

[0061] In other words, the driving control unit 101 switches the driving mode for turning when the vehicle turns, according to the operation state of the first operation switch SW1. Specifically, each time the first operation switch SW1 is pressed for a short time, it switches between the two-wheel turning mode and the four-wheel turning mode.

[0062] In two-wheel turning mode, as shown in Figure 7, only the left and right wheels located at the front in the direction of travel are steered in the direction instructed to turn (hereinafter referred to as two-wheel steering state 2WS). The left and right wheels 2 located at the rear do not change direction. In four-wheel turning mode, as shown in Figure 7, the left and right wheels located at the front in the direction of travel are steered in the direction instructed to turn. On the other hand, the left and right wheels 2 located at the rear in the direction of travel are steered in the opposite direction to the direction instructed to turn (hereinafter referred to as four-wheel steering state 4WS). By steering in this way, it is possible to turn with a small turning radius.

[0063] During turning, the corresponding slewing cylinder 20 is operated to change the direction of the relevant driving wheel 2. That is, the hydraulic control valve 12 for the slewing cylinder 20 is controlled. Furthermore, for each of the four driving wheels 2, the operation of the hydraulic motor 4 is controlled so that the rotational speed of the driving wheel 2 detected by the rotation sensor S5 becomes the target speed, and the drive torque detected by the pressure sensor S6 becomes the target value.

[0064] The driving control unit 101 switches the driving operation mode according to the operation state of the first operation switch SW1. That is, each time the first operation switch SW1 is pressed and held, it switches between a vehicle-side operation mode in which the vehicle is driven by the operation of the driving operation unit 21, and a remote control operation mode in which the vehicle is driven by the operation of the remote control device RC.

[0065] In manual operation mode, the vehicle can be made to travel straight or turn in the target direction by operating the control lever 29. In remote control operation mode, the vehicle can be made to travel straight or turn in the target direction by operating the remote control device RC.

[0066] The driving control unit 101 switches the driving speed according to the operation state of the third operation switch SW3. That is, each time the third operation switch SW3 is pressed for a short time, it switches between a low-speed mode, in which the target speed when the vehicle moves is set to the low-speed setting, and a high-speed mode, in which the target speed is set to the high-speed setting. The low-speed setting is set to a speed similar to that of a person walking, for example. The high-speed setting is set to a speed faster than the low-speed setting, for example, a speed similar to that of a person jogging.

[0067] The control contents of the driving control unit 101 will be explained below based on the flowchart in Figure 10. If the first operating switch SW1 is turned ON, and the ON operation time Tx is shorter than the first set time Ts1 (for example, 1 second), the turning mode is switched (steps #1, #2, #3). That is, if it is set to 2-wheel turning mode at that time, it is switched to 4-wheel turning mode. Also, if it is set to 4-wheel turning mode, it is switched to 2-wheel turning mode.

[0068] If the time Tx during which the first operation switch SW1 was ON is longer than the first set time Ts1 and shorter than the second set time Ts2 (for example, about 10 seconds), the operation mode is switched (steps #4, #5). That is, if the aircraft-side operation mode is set, the remote control operation mode is set. Also, if the remote control operation mode is set, the aircraft-side operation mode is set.

[0069] When the third operating switch SW3 is turned ON, if the ON operation time Tx is shorter than the first set time Ts1 (for example, 1 second), the target speed is changed (steps #6, #7, #8). That is, if low-speed mode is set at that time, it switches to high-speed mode. Also, if high-speed mode is set, it switches to low-speed mode.

[0070] With the driving control mode set in this manner, the vehicle is moved based on commands from the operating lever 29 or the remote control device RC.

[0071] In other words, when forward movement is commanded, the operation of the hydraulic motor 4 is controlled to make the vehicle move in a straight line forward (steps #9, #10). At this time, the driving wheels 2 are driven at the set target speed. When reverse movement is commanded, the vehicle is made to move in a straight line backward (steps #11, #12). The target speed is the same as in the case of forward movement.

[0072] When commanded to turn right, the vehicle turns towards the front right side (steps #13, #14). At this time, if the 2-wheel turning mode is set, as shown in Figure 7, only the left and right wheels located at the front of the direction of travel are steered in the direction of the turn command (2WS). If the 4-wheel turning mode is set, as shown in Figure 7, the left and right wheels 2 located at the front of the direction of travel are steered in the direction of the turn command, and the left and right wheels 2 located at the rear of the direction of travel are steered in the opposite direction to the direction of the turn command (4WS). In addition, to ensure smooth turning, it is advisable to set the speed of the inner wheel 2 of the turn to a slightly lower speed than the target speed.

[0073] When commanded to turn left, the vehicle turns towards the front left side (steps #15, #16). In this case, similar to turning right, the vehicle will turn in either the two-wheel turning mode or the four-wheel turning mode, whichever is set.

[0074] When performing a turning maneuver, the steering angle of the driving wheels from the straight-ahead position may be changed according to the magnitude of the tilt angle to the left or right from the neutral position of the operating lever 29, or the steering angle may be changed from the straight-ahead position by a preset amount based on the operation to the left or right from the neutral position of the operating lever 29.

[0075] [Second Embodiment] Next, a second embodiment will be described. In this embodiment, the configuration of the driving operation unit 21 and the control contents of the control device C (driving control unit 101) differ from those of the first embodiment, while the other configurations are the same as in the first embodiment. Therefore, only the differing configurations will be described, and the same configurations will not be described.

[0076] As shown in Figure 12, unlike the first embodiment, the operation panel 25 of the operating unit 21 is equipped with a fourth operation switch SW4 as a switch for commanding the switching of the turning mode. This fourth operation switch SW4 is configured as a momentary push switch. In this embodiment, a fifth operation switch SW5 for switching the operating mode is also provided, but the explanation of switching this operating mode will be omitted in the following operation description.

[0077] Furthermore, the driving control unit 101 can switch to a four-wheel turning mode, which is a super-tight turning mode in which the direction of the left and right driving wheels on both the front and rear sides is changed so that the center of the vehicle body is the turning center in a plan view.

[0078] The control contents of the driving control unit will be explained below based on the flowchart in Figure 13. When the control operation starts, the low-speed mode and the two-wheel turning mode are initially set as the driving modes (step #20). Then, when the fourth operation switch SW4 is turned ON, if the time Tx during which the ON operation was performed is shorter than the first setting time Ts1 (for example, 1 second), the system switches to high-speed mode and changes the target speed for driving to the high-speed setting (steps #21, #22, #23). If the time Tx during which the fourth operation switch SW4 was turned ON is longer than the first setting time Ts1 and shorter than the second setting time Ts2 (for example, about 10 seconds), the driving mode for turning is switched to the pivot turning mode (steps #24, #25). Therefore, in this embodiment, the fourth operation switch SW4 corresponds to the driving mode command means MS.

[0079] If the fourth operation switch SW4 is turned ON for a longer period Tx than the second set time, the system will switch to maintenance mode, which involves performing maintenance work on the vehicle without performing any actual work (step #26).

[0080] In this embodiment, when turning, the vehicle is operated in a super-pivot turning mode. That is, as shown in Figure 14, the left and right driving wheels 2 at both the front and rear are steered so that the center Q of the vehicle body in a plan view becomes the turning center. Each driving wheel 2 is then driven to rotate so that the vehicle turns along the direction commanded with the center Q of the vehicle body as the turning center.

[0081] By performing turns in this super-pivot turning mode, the vehicle's direction can be changed with a small turning radius, even in a narrow work area.

[0082] Furthermore, in this embodiment, since turning is performed in super-tight turning mode, it is preferable to automatically set the operation to be controlled by the remote control device RC when commanding turning.

[0083] [Another embodiment] The following lists other embodiments.

[0084] (1) The control device C may be configured to switch to a diagonal driving mode in which the left and right driving wheels on both the front and rear sides are turned in the same direction. That is, in the diagonal driving mode, as shown in Figure 15, steering operations are performed so that the left and right driving wheels on both the front and rear sides are turned in the same direction, and in this state the vehicle is able to move diagonally.

[0085] (2) As the driving mode command means MS for commanding the control device C to switch driving modes, instead of a push-button switch, a rotary switch having three or more switching terminals, or a configuration of three or more level discrimination control using a potentiometer may be used to enable selection of any of three or more turning driving modes. For example, the system may be configured to select any of the following: a two-wheel turning mode, a turning mode with four-wheel steering, or a turning mode with super-tight turning. In addition, the system may also be configured to enable switching to the above-mentioned diagonal driving mode.

[0086] (3) Various configurations can be adopted as means for commanding the driving mode, such as using a touch panel to command the switching instead of a push-button switch or a rotary switch.

[0087] (4) The support mechanism A may be a mechanism comprising one link or three or more links, and may also be equipped with an electric actuator as a device for changing the posture of the support mechanism A.

[0088] (5) The driving means for travel may be configured to be driven by an electric motor or an engine instead of the hydraulic motor 4.

[0089] (6) The steering mechanism may be configured to be driven by a hydraulic motor or an electric motor instead of a hydraulic cylinder. [Industrial applicability]

[0090] This invention can be applied to work vehicles suitable for moving on slopes, uneven terrain, and other similar conditions. [Explanation of symbols]

[0091] 1. Vehicle body 2 running wheels 4. Hydraulic motor (driving means) 5. Refraction link mechanism 6,7 Hydraulic cylinders for changing posture 20. Hydraulic cylinder for turning (steering mechanism) C Control device MS Driving Mode Command Means

Claims

1. The vehicle body and Multiple running wheels located at the front and rear on both the left and right sides of the vehicle body, Multiple support mechanisms that support multiple running wheels so that their positions can be individually changed relative to the vehicle body, Multiple steering mechanisms capable of individually changing the direction of each of the multiple aforementioned wheels, A driving means for individually rotating each of the multiple aforementioned driving wheels, A control device that controls the operation of multiple driving means and multiple steering mechanisms, The control device is equipped with a driving mode command means for commanding the switching of a plurality of driving modes in which the operating modes of the steering mechanism are mutually different. The control device controls the operation of the plurality of steering mechanisms in accordance with the driving mode commanded by the driving mode command means. The aforementioned driving mode command means is a push-operated switch, which commands switching the driving mode with a push operation shorter than a set time, and commands switching to a mode different from the aforementioned driving mode with a push operation longer than the set time.

2. The mode different from the driving mode is an operating mode, The work vehicle according to claim 1, wherein the driving mode command means commands switching between remote control operation mode and machine-side operation mode by pressing the button for a longer duration than the set time.

3. A loading section located on the upper surface of the vehicle body and capable of loading luggage, An operating control unit is provided, located behind the aforementioned loading section. The work vehicle according to claim 1, wherein the driving mode command means is provided in the driving operation unit.

4. As the aforementioned driving mode, The work vehicle according to claim 1, which is switchable between a two-wheel steering mode that changes the direction of only the left and right driving wheels located at the front or rear, and a four-wheel steering mode that changes the direction of the left and right driving wheels at the front and rear, respectively.

5. The work vehicle according to claim 1, which is capable of switching to a super-pivot turning mode in which the direction of the left and right wheels on both the front and rear sides is changed so that the center of the vehicle body is the pivot point in a plan view.

6. The work vehicle according to claim 1, which is capable of switching to a diagonal driving mode in which the direction of the left and right driving wheels on both the front and rear sides are changed to the same direction.

7. The support mechanism includes a plurality of articulated link mechanisms, one end of which is supported by the vehicle body and the other end of which is supported by the running wheel, and a plurality of hydraulic cylinders for changing the posture, which can individually change the posture of the articulated link mechanisms. The aforementioned driving means is a hydraulic motor, The work vehicle according to any one of claims 1 to 6, wherein the steering mechanism is a hydraulic cylinder for turning operations.

Images