Work vehicle

Abstract

To provide a work vehicle desired to be able to appropriately maintain the posture of a vehicle body regardless of differences in loading states of cargoes and reduce wasteful fuel consumption in an engine.SOLUTION: A work vehicle includes: a plurality of travel devices configured to be driven by hydraulic systems for running 4 and each disposed at front and rear positions on both right and left sides of a vehicle body; a plurality of support mechanisms supported by the vehicle body and configured to be driven by hydraulic systems for changing posture 6, 7 to support the travel devices such that the positions of the travel devices can be changed with respect to the vehicle body; an engine 9a configured to drive a hydraulic pump 9b; loading state detection means SJ configured to measure a loading state of cargoes loaded on a loading part; and change adjustment means HT configured to change and adjust a driving state of the engine 9a depending on differences in loading states of the cargoes detected by the loading state detection means SJ.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a work vehicle suitable for moving over uneven terrain. [Background technology]

[0002] A conventional work vehicle as described above has four traveling wheels driven by a hydraulic motor supported on the vehicle body via an articulating link mechanism that can be extended and retracted by operating a hydraulic cylinder, and by changing the height of the traveling wheels, the vehicle body can be driven while maintaining its posture even on uneven terrain (see, for example, Patent Document 1). This work vehicle is equipped with a hydraulic pump driven by an engine as a hydraulic supply source that supplies hydraulic oil to the hydraulic cylinders and hydraulic motor, and the engine output is always set to a high output close to maximum output. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-1440 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned work vehicle is used in a work mode in which the vehicle body is maintained in a horizontal position and a load is loaded on top of the vehicle body. Conventionally, the engine output is always set to a high output close to maximum output, so it can be used well even when the vehicle is located on uneven ground and a load is loaded.

[0005] However, in the above-mentioned conventional configuration, there is not always any cargo on top of the vehicle body, and there are also cases where there is no cargo. Even in such a case, the engine operates at high power, which unnecessarily increases the amount of fuel consumed per unit time, which may shorten the duration of work before the stored fuel is consumed, and also has other disadvantages such as increased noise.

[0006] Therefore, there has been a demand for a vehicle that can maintain a good posture of the vehicle body regardless of the load condition, while suppressing unnecessary fuel consumption by the engine. [Means for solving the problem]

[0007] Work according to the present invention Car a vehicle body having a loading section capable of loading luggage; a plurality of traveling devices driven by a traveling hydraulic device and positioned at the front and rear of each of the left and right sides of the vehicle body; a plurality of support mechanisms supported by the vehicle body and driven by an attitude changing hydraulic device to support the traveling devices so that their positions can be changed relative to the vehicle body; a hydraulic pump that supplies hydraulic oil to the traveling hydraulic device and the attitude changing hydraulic device; an engine that drives the hydraulic pump; loading condition detection means that measures the loading condition of the luggage loaded on the loading section; and change adjustment means that change and adjust the driving state of the engine depending on the loading condition of the luggage detected by the loading condition detection means. The loading status detection means measures the variation in the loading location of the luggage relative to the loading section as the loading status, and the change adjustment means determines the magnitude of the load caused by the luggage based on the detection result of the loading status detection means, and adjusts the engine output as the driving state of the engine so that if the load is large, the engine output is increased, and as the load is smaller, the engine output is decreased.

[0008] According to the present invention, the loading status of the luggage loaded in the loading section is detected by the loading status detection means. In other words The load condition caused by the load of luggage is detected, and the change / adjustment means adjusts the driving state of the engine according to the difference in the luggage loading condition. If the load is unevenly distributed relative to the loading section, an uneven load is applied to the vehicle body, increasing the load load when maintaining the vehicle body's position and increasing the driving load on the engine. Therefore, in this configuration, the uneven distribution of the load is measured as the loading condition. As a result, if the load is balanced and centered relative to the loading section, it is possible to reduce unnecessary fuel consumption by the engine compared to when the load is unevenly distributed.

[0009] According to this configuration,When the load of the luggage is large, the engine output is increased, so that the posture of the vehicle body can be maintained well. ,workman Engine output By making it small By reducing the driving load on the engine, it is possible to suppress unnecessary fuel consumption by the engine. At this time, since the load of the luggage is small, it is possible to maintain the posture of the vehicle body even if the engine output is reduced. By changing the engine output in this way, it is possible to appropriately suppress the fuel consumption of the engine when the load is light.

[0010] Therefore, it is possible to maintain the vehicle body in a good position regardless of the load condition of the luggage, and also to suppress unnecessary fuel consumption by the engine.

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017] The present invention Related work vehicles teeth, a vehicle body having a loading section capable of loading luggage; a plurality of traveling devices driven by a traveling hydraulic device and positioned at the front and rear of each of the left and right sides of the vehicle body; a plurality of support mechanisms supported by the vehicle body and driven by an attitude changing hydraulic device to support the traveling devices so as to be able to change their positions relative to the vehicle body; a hydraulic pump that supplies hydraulic oil to the traveling hydraulic device and the attitude changing hydraulic device; a loading status detection means that measures the loading status of the luggage loaded in the loading section; and a change adjustment means that changes and adjusts the supply amount of the hydraulic oil in accordance with differences in the loading status of the luggage detected by the loading status detection means, wherein the loading status detection means measures variations in the loading location of the luggage relative to the loading section as the loading status, The change adjusting means determines the magnitude of the load caused by the luggage based on the detection result of the loading condition detecting means, and adjusts the supply amount of the hydraulic oil to be large if the load is large, and adjusts the supply amount of the hydraulic oil to be small as the load becomes smaller. It is characterized by:

[0018] According to the present invention, the load condition detection means detects the load condition of the cargo loaded on the loading section, i.e., the load condition caused by the cargo being loaded, and the varying / adjusting means adjusts the supply amount of hydraulic oil according to the load condition of the cargo. If the load is unevenly distributed relative to the loading section, an uneven load is applied to the vehicle body, increasing the load load when maintaining the vehicle body's position and increasing the driving load on the engine. Therefore, in this configuration, the uneven distribution of the load is measured as the loading condition. As a result, if the load is balanced and centered relative to the loading section, it is possible to reduce unnecessary fuel consumption by the engine compared to when the load is unevenly distributed. According to this configuration, when the luggage load is heavy, the amount of hydraulic oil supplied from the hydraulic pump is increased, thereby enabling the posture of the vehicle body to be maintained well. On the other hand, when the luggage load is light, the amount of hydraulic oil supplied from the hydraulic pump is reduced, thereby reducing the drive load. By changing the amount of hydraulic oil supplied by the engine-driven hydraulic pump in this way, the drive load on the engine that drives the hydraulic pump is reduced, and engine fuel consumption under light loads can be suppressed. At this time, since the load of the luggage is small, it is possible to maintain the posture of the vehicle body even if the amount of hydraulic oil supplied is small. Therefore, it is possible to maintain the vehicle body in a good position regardless of the load condition of the luggage, and also to suppress unnecessary fuel consumption by the engine.

[0019] The present invention Related work vehicles teeth, a vehicle body having a loading section capable of carrying luggage; a plurality of travel devices that are driven to travel by a hydraulic motor and are located at the front and rear of both the left and right sides of the vehicle body; a plurality of support mechanisms that are supported by the vehicle body and driven by hydraulic cylinders to support the travel devices so that their positions can be changed relative to the vehicle body; and a hydraulic pump that supplies hydraulic oil to the hydraulic motor and the hydraulic cylinder. a pressure oil supply line that supplies the hydraulic oil from the hydraulic pump to the plurality of hydraulic motors and the plurality of hydraulic cylinders; and an unloading valve that is switchable between an open state in which the pressure oil supply line is blocked to return the hydraulic oil from the hydraulic pump to a reservoir, and a blocked state in which the hydraulic oil is supplied to the plurality of hydraulic motors and the plurality of hydraulic cylinders through the pressure oil supply line. a load status detection means for measuring the load status of the luggage loaded on the loading section; and a change / adjustment means for changing and adjusting the supply amount of the hydraulic oil according to the load status of the luggage detected by the load status detection means; the varying / adjusting means is capable of interval operation for alternately switching the unloading valve between the closed state and the open state at a set period, determining the magnitude of the load caused by the luggage based on the detection result of the loading state detection means; If the load is large, the distance at which the shielding state is achieved is of long The amount of hydraulic oil supplied is then increased. The smaller the load, the greater the distance that the open state is reached. of long Therefore, the amount of hydraulic oil supplied is reduced. By performing the interval operation, the supply amount of the hydraulic oil is adjusted. It is characterized by:

[0020] According to the present invention, the loading condition detection means detects the loading condition of the cargo on the loading section, such as the weight of the cargo or the unevenness of the cargo loading location on the loading section, and the load burden caused by the cargo being loaded. Then, the changing and adjusting means adjusts the supply amount of hydraulic oil according to the difference in the cargo loading condition. According to this configuration, the varying / adjusting means performs interval operation to alternately switch the unloading valve between the closed state and the open state at set intervals.

[0021] If the interval between the shut-off states within the set cycle becomes longer, the interval between the open states becomes shorter. In this case, the amount of hydraulic oil supplied to the multiple hydraulic motors and multiple hydraulic cylinders through the pressure oil supply line increases, which increases the driving load on the engine.

[0022] On the other hand, if the interval between the open states within the set cycle becomes longer, the interval between the closed states becomes shorter. In this case, the amount of hydraulic oil supplied to the multiple hydraulic motors and multiple hydraulic cylinders through the pressure oil supply line decreases, and the driving load on the engine becomes smaller.

[0023] The control device performs interval operation so that the interval between the blocked state is longer when the load is heavy and the interval between the open state is longer as the load becomes lighter.As a result, the engine driving load is reduced as the load becomes lighter, and engine fuel consumption at light loads can be suppressed. In the present invention, it is preferable that the loading status detection means measures the weight of the luggage as the loading status. If the weight of the luggage loaded on the loading section is heavy, the load caused by the luggage will be heavy, and if the weight is light, the load will be light. Therefore, in this configuration, the weight of the luggage to be loaded is measured and the amount of hydraulic oil supplied is changed and adjusted according to the measured luggage weight. As a result, if the luggage weight is light, it is possible to reduce unnecessary fuel consumption by the engine. In the present invention, it is preferable that the loading status detection means measures, as the loading status, variations in the loading positions of the luggage relative to the loading section. If the load is unevenly distributed relative to the loading section, an uneven load is applied to the vehicle body, increasing the load load when maintaining the vehicle body's position and increasing the driving load on the engine. Therefore, in this configuration, the uneven distribution of the load is measured as the loading condition. As a result, if the load is balanced and centered relative to the loading section, it is possible to reduce unnecessary fuel consumption by the engine compared to when the load is unevenly distributed. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] 10 is a flowchart of a control operation. [Figure 8] 10 is a flowchart of a control operation. [Figure 9] 10 is a flowchart of a control operation. [Figure 10] FIG. 10 is a hydraulic circuit diagram of a hydraulic oil supply unit according to another embodiment. [Figure 11] 10 is a flowchart of a control operation according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] An embodiment of the present invention will be described with reference to the drawings. In the following description, the direction of the arrow FW shown in the drawings will be referred to as "front," the direction of the arrow BK as "rear," the direction of the arrow RH as "right," the direction of the arrow LH as "left," the direction of the arrow UP as "up," and the direction of the arrow DW as "down."

[0026] As shown in Figures 1 to 3, the work vehicle is equipped with a vehicle body 1 that is approximately rectangular in plan view and supports the entire vehicle, a plurality of running wheels 2 that serve as running devices that support the vehicle body 1, a plurality of auxiliary wheels 3 that are 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 that serve as running hydraulic devices that drive each of the plurality of running wheels 2.

[0027] The traveling wheels 2 are located at the front and rear of both the left and right sides of the vehicle body 1. In this embodiment, the work vehicle is equipped with four traveling wheels 2, located at the left front, right front, left rear, and right rear. It also has four support mechanisms A, located at the left front, right front, left rear, and right rear. The support mechanisms A include a bending link mechanism 5 and a plurality of hydraulic cylinders 6, 7 as attitude-changing hydraulic devices that can individually change the attitude of the bending link mechanism 5.

[0028] The vehicle body 1 is generally rectangular in plan view, and is provided on the upper surface of the vehicle body 1 with a flat loading section 8 on which cargo can be loaded. The loading section 8 is a generally rectangular section 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 supplies such as fertilizer and chemicals, harvested crops and harvest baskets, and pallets on which these are placed.

[0029] The vehicle body 1 is provided below the loading section 8 with a hydraulic supply source 9 that sends hydraulic oil to the hydraulic cylinders 6, 7 and the hydraulic motor 4, a plurality of hydraulic control valves 10 that adjust the supply state of hydraulic oil from the hydraulic supply source 9, an ECU (Electronic Control Unit) 11 that controls the operation of the hydraulic control valves 10, a battery 12 for power supply, and the like. The hydraulic supply source 9 is provided with a hydraulic pump 9b driven by an engine 9a. The hydraulic supply source 9 also includes a hydraulic oil tank 9c, a radiator 9d, and the like. The hydraulic supply source 9 is supported by an underframe 24. A fuel tank 9e is provided at a high position on the rear side of the vehicle body 1. In addition, a speed governor 9f for the engine 9a is provided, and the ECU 11 is configured to control the operation of the speed governor 9f to change and adjust the engine output.

[0030] The ECU 11 is equipped with a microcomputer and is capable of executing various controls according to a control program. The multiple hydraulic control valves 10 and the ECU 11 constitute a control device C. The battery 12 is charged by a generator driven by the power of the engine 9a. Reference numeral 13 in the figure denotes an operating handle that can be gripped and operated by an operator.

[0031] [Support mechanism] As described above, the support mechanism A includes the articulating link mechanism 5 and a plurality of hydraulic cylinders 6, 7. As shown in Fig. 1, a plurality of (specifically, four) traveling wheels 2 are supported via the articulating link mechanism 5 with respect to the vehicle body 1 so as to be able to move up and down individually.

[0032] As shown in Figures 4 and 5, the bending link mechanism 5 includes a base end portion 14 supported by the vehicle body 1, a first link 15 having an upper end portion supported on the lower portion of the base end portion 14 so as to be rotatable about a horizontal axis X1, and a second link 16 having one end portion supported on the lower end portion of the first link 15 so as to be rotatable about a horizontal axis X2 and having the running wheel 2 supported on the other end portion.

[0033] A support bracket 17 that supports the traveling wheel 2 is supported by a boss portion 18 provided at the swing side end of the second link 16 so as to be swingable around the vertical axis Y. A hydraulic cylinder 20 for swing operation (hereinafter referred to as a swing cylinder) is provided across a bracket 19 on one end side of the second link 16 and an arm portion 17a provided on the support bracket 17.

[0034] A plurality of hydraulic cylinders 6, 7 are provided corresponding to the plurality of articulating link mechanisms 5, respectively, and capable of individually changing the posture of the articulating link mechanisms 5. That is, a first hydraulic cylinder 6 is provided that can change the swing posture of the first link 15 relative to the vehicle body 1, and a second hydraulic cylinder 7 is provided that can change the swing posture of the second link 16 relative to the first link 15.

[0035] When the first hydraulic cylinder 6 is extended or retracted with the operation of the second hydraulic cylinder 7 stopped, the first link 15, the second link 16, and the traveling wheel 2 swing together around the horizontal axis X1 of the pivotal connection point with respect to the base end 14 while maintaining a constant relative posture. When the second hydraulic cylinder 7 is extended or retracted with the operation of the first hydraulic cylinder 6 stopped, the second link 16 and the traveling wheel 2 swing 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.

[0036] An auxiliary wheel 3 is rotatably supported at an intermediate bending portion of each of the plurality of bending link mechanisms 5. The auxiliary wheels 3 are configured as wheels with approximately the same outer diameter as the running wheels 2. A support shaft that pivotally connects the first link 15 and the second link 16 is formed to extend 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 support shaft.

[0037] By operating the turning cylinder 20, the traveling wheel 2 can be turned around the vertical axis Y relative to the articulating link mechanism 5, thereby enabling the vehicle to be turned.

[0038] The hydraulic control valve 10 corresponding to the hydraulic motor 4 adjusts the flow rate of the hydraulic oil, so that the rotation speed of the hydraulic motor 4, that is, the rotation speed of the traveling wheels 2, can be changed.

[0039] [Sensor] This work vehicle is equipped with various sensors. As shown in Fig. 6, each of the four second hydraulic cylinders 7 is provided 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.

[0040] A plurality of stroke sensors S3 capable of detecting the amount of extension / contraction operation are provided for each of the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7. The amount of extension / contraction operation of each hydraulic cylinder 6, 7 is a detected value corresponding to the swing position of the first link 15 and second link 16, which are the objects of operation.

[0041] The vehicle body 1 is provided with an inclination sensor S4 for detecting the inclination state of the vehicle body. The inclination sensor S4 is an inertial measurement unit (IMS) having a well-known configuration. The IMU has a three-axis acceleration sensor and a gyro sensor, and can detect changes in the attitude of the vehicle body 1, specifically, tilt in the front-rear and left-right directions.

[0042] A rotation sensor S5 is provided near the traveling wheels 2 to detect the rotation speed of the traveling wheels 2 driven by the hydraulic motor 4. Based on the rotation speed of the traveling wheels 2 detected by the rotation sensor S5, the supply of hydraulic oil to the hydraulic motor 4 is controlled so that the rotation speed of the traveling wheels 2 becomes a target value. A pressure sensor S6 is provided to detect the pressure of the hydraulic oil supplied to the hydraulic motor 4. Based on the pressure of the hydraulic oil detected by the pressure sensor S6, the supply (pressure) of hydraulic oil to the hydraulic motor 4 is controlled so that the drive torque of the traveling wheels 2 becomes a target value. A stroke sensor S7 capable of detecting the extension / retraction operation amount is provided for each of the four swing cylinders 20.

[0043] [ECU] The ECU 11 (Electronic Control Unit) includes a non-volatile memory (not shown) that stores programs corresponding to the functional units described below, and a CPU (not shown) that executes the programs. The functions of the functional units are realized by the CPU executing the programs.

[0044] The ECU 11 has, as its functional units, an attitude control unit 100, a driving control unit 101, a weight calculation unit 102, and a drive load adjustment unit 103. When the vehicle is traveling with the four traveling wheels 2 in contact with the ground, the driving control unit 101 controls the operation of the hydraulic motor 4 for each of the four traveling wheels 2 so that the rotational speed of the traveling wheels 2 detected by the rotation sensor S5 reaches a target speed and the drive torque detected by the pressure sensor S6 reaches a target value. Specifically, the ECU 11 performs a switching operation of the hydraulic control valve that supplies and discharges hydraulic oil to and from the hydraulic motor.

[0045] When the vehicle body is moving, the posture control unit 100 executes horizontal control, which controls the operation of the support mechanism A so that the loading section 8 of the vehicle body 1 is in a horizontal posture, based on the detection information of the inclination sensor S4. In the horizontal control, the posture control unit 100 controls the operation of the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7 so that the tilt angles in the front-to-rear direction and the left-to-right direction from the horizontal posture of the vehicle body 1 become values ​​corresponding to the horizontal posture, based on the detection information of the inclination sensor S4 and the detection information of the stroke sensor S3.

[0046] To explain further, the target operating amounts of the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7 required to bring the loading section 8 to a horizontal position are calculated from the inclined position of the loading section 8 detected by the inclination sensor S4, and the operation of the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7 is controlled so that the actual operating amounts detected by the stroke sensor S3 become the target operating amounts. Specifically, the control unit 10 switches the hydraulic control valve 10 that supplies and discharges hydraulic oil to the four first hydraulic cylinders 6 and the four second hydraulic cylinders 7.

[0047] The actual operation amount of each hydraulic cylinder 6, 7 detected by the stroke sensor S3 indicates the state of change in the relative posture of the link to be operated with respect to the vehicle body member. That is, based on the detection value of the stroke sensor S3, it is possible to determine the swing posture of the first link 15 with respect to the vehicle body 1, the swing posture of the second link 16 with respect to the first link 15, etc. As a result, it is possible to determine the height from the ground contact part of the traveling wheel 2 to the vehicle body 1.

[0048] While the vehicle is stopped, the weight calculation unit 102 determines the load status of the luggage loaded on the loading unit 8 based on the detection results of the pressure sensors S1, S2 and the stroke sensors S3, and calculates the weight of the luggage and the variation in the loading location of the luggage on the loading unit 8. Therefore, the pressure sensors S1, S2, the stroke sensors S3, and the weight calculation unit 102 constitute a load status detection means SJ that measures the load status of the luggage loaded on the loading unit 8.

[0049] The weight calculation will be explained. Based on the detection value of the stroke sensor S3, the swinging posture of the first link 15 relative to the vehicle body 1, the swinging posture of the second link 16 relative to the first link 15, etc. can be determined, so it is possible to determine the height from the contact point of the running wheel 2 in each support mechanism A to the vehicle body 1.

[0050] Furthermore, based on the detection results of the pressure sensors S1 and S2, it is possible to detect the pressure acting on the hydraulic cylinders 6 and 7 via the links 15 and 16 of the support mechanism A when the running wheel 2 touches the ground. A force acting in the vertical direction at the contact point where the running wheel 2 touches the ground acts on the first hydraulic cylinder 6 via the first link 15, and also acts on the second hydraulic cylinder 7 via the second link 16.

[0051] The weight of the entire vehicle acts in the vertical direction at the ground contact point of each running wheel 2. At this time, the vertical force acting on the running wheel 2 (hereinafter referred to as ground contact pressure) acts as internal pressure in the oil chambers of each of the hydraulic cylinders 6, 7 via the support mechanism A. Therefore, the ground contact pressure at each support mechanism A can be calculated using the detection information from the pressure sensors S1, S2 and the stroke sensor S3.

[0052] The driving load adjusting unit 103 changes and adjusts the driving state of the engine 9a depending on the load condition. That is, it controls the operation of the speed governor so that the output rotation speed of the engine 9a becomes a rotation speed according to the load condition. Therefore, the driving load adjusting unit 103 constitutes a changing and adjusting means HT.

[0053] Next, the control operations of the weight calculation unit 102 and the driving load adjustment unit 103 by the ECU 11 will be described with reference to the flowcharts of FIGS.

[0054] As an initial setting, the ECU 11 controls the speed governor 9f so that the engine 9a is driven at the rated speed (step #01). When the vehicle is traveling with a load loaded, the engine 9a is driven at the rated speed. Then, after the vehicle stops traveling (step #02), the ECU 11 executes a load weight measurement process (step #03).

[0055] 9, in the load weight measurement process, the ground contact pressure of each support mechanism A is calculated using the detection information from the pressure sensors S1, S2 and the stroke sensor S3 (step #31). At this time, it is assumed that the loading unit 8 has been placed in a horizontal position by the horizontal control, but if the loading unit 8 is not placed in a horizontal position even after the horizontal control is executed, the information from the tilt sensor S4 may also be taken into account.

[0056] The weight of the entire vehicle is calculated by adding up the ground contact pressures of the multiple running wheels 2 (step #32). Next, the weight of the cargo loaded on the loading section 8 is calculated by subtracting the weight of the vehicle body, which has been measured and known in advance, from the weight of the entire vehicle (step #33).

[0057] Furthermore, the position of the center of gravity of the cargo in the loading section is predicted based on the contact pressures found at the contact points of the four running wheels 2, and the variation in the loading position is measured (step #34). In further explanation, by comparing the variations in the contact pressures of the four running wheels 2, the center of gravity position in a plan view of the entire vehicle can be found, and it is possible to determine how the loading position varies from the appropriate loading position located in the center of the loading section.

[0058] For example, even if the loading section 8 is in a horizontal position, if the cargo is loaded unevenly on the loading section 8, the ground contact pressure of the running wheel 2 on the uneven side will be greater than the ground contact pressure of the running wheel 2 on the opposite side.

[0059] Next, the driving load adjustment process is executed (step #04). As shown in Fig. 9, in the driving load adjustment process, the magnitude of the load caused by the luggage is determined based on the measurement results of the load weight measurement process (step #41). The load is determined according to the weight of the luggage and the variation in the loading position. The heavier the luggage, the greater the load, and the greater the variation in the loading position, the greater the load.

[0060] If it is determined that the load is large and high, the engine is maintained at the rated speed (steps 41 and 42). Even when the vehicle is mainly loaded with cargo, the engine is driven at the rated speed with high output, allowing for smooth travel.

[0061] If it is determined that the load is small and low, the engine speed is reduced to an intermediate value (step #43). The intermediate value is a speed state intermediate between the rated speed and the idling speed. When the load is light, reducing the engine output can minimize wasteful fuel consumption.

[0062] If it is determined that the load is no load, that is, that no luggage is loaded on the loading section 8, the engine rotation is reduced to the lower limit value (idling rotation or rotation close to it) (step #44). If no luggage is loaded, reducing the output of the engine 9a to a minimum or close to it can suppress fuel consumption and reduce noise.

[0063] When the engine rotation speed is reduced to an intermediate value, or when the engine rotation speed is reduced to the lower limit value, once the vehicle starts moving (step #45), a driving load is applied due to the driving of the running wheels 2, so the engine 9a is returned to a state where it is driven at the rated rotation speed (step #46).

[0064] By changing and adjusting the driving state of the engine 9a in this way according to differences in load, it is possible to suppress unnecessary fuel consumption by the engine 9a, and also to suppress noise from the engine 9a, thereby contributing to an improvement in the working environment.

[0065] [Another embodiment] (1) The loading condition detecting means may be configured as follows. Instead of the pressure sensors S1 and S2, a torque sensor or a load cell that detects the drive torque applied to each link 15 and 16 of the support mechanism A may be used, or a sensor that directly detects the vertical ground contact pressure applied to the rotation axis of the traveling wheel 2 may be used. Also, instead of the stroke sensor S3, a potentiometer or a rotary encoder that detects the rotation angle of the joint portion of each link 15 and 16 of the support mechanism A may be used.

[0066] (2) The load magnitude is not limited to being determined in three stages, but may be determined in two stages, four or more stages, or continuously. The driving load adjustment process may be configured to switch the output of the engine 9a in two stages, four stages, continuously, or the like, depending on how the load magnitude is determined.

[0067] (3) The driving load adjusting section (changing / adjusting means) may be configured as follows instead of the configuration for changing / adjusting the output of the engine 9a. 10, an unloading valve 22 is provided in a pressure oil supply path 21 that supplies hydraulic oil from a hydraulic pump 9b to a plurality of hydraulic motors 4 and a plurality of hydraulic cylinders 6, 7, and 20. The unloading valve 22 can be switched between an open state in which the pressure oil supply path 21 is shut off and the hydraulic oil from the hydraulic pump 9b is returned to a reservoir (hydraulic oil tank 9c), and a closed state in which the hydraulic oil is supplied to a plurality of hydraulic devices through the pressure oil supply path 21. In the figure, reference numeral 23 denotes a relief valve, and 9g denotes an oil filter.

[0068] The drive load adjustment unit 103 may be capable of interval operation to alternately switch the unloading valve 22 between a closed state and an open state at a set period, and may adjust the amount of hydraulic oil supplied by performing interval operation in which the interval between the closed state is longer when the load is heavy and the interval between the open state is longer when the load is lighter.

[0069] That is, the following process is executed as the driving load adjustment process in step #04 in the above embodiment. As shown in FIG. 11, in the driving load adjustment process, the magnitude of the load caused by the luggage is determined based on the measurement result of the loaded weight measurement process, as in the above embodiment (step #401).

[0070] If it is determined that the load is large and high, the unloading valve 22 is maintained in the closed state (step #402). That is, in this case, in the interval operation, the time in the closed state is 100% and the time in the open state is 0%. Even when the vehicle is mainly loaded with cargo, the unloading valve 22 is closed, so all of the pressure oil from the hydraulic pump 9b is supplied to multiple hydraulic devices, making it possible to maintain a good posture and travel.

[0071] If it is determined that the load is small and low, an interval operation is performed in which the unloading valve 22 is alternately switched between the closed state and the open state at a fixed interval (step #403). When the load is light, a portion of the pressure oil from the hydraulic pump is returned to the reservoir (hydraulic oil tank 9c), thereby minimizing wasteful consumption of fuel.

[0072] If it is determined that the load is unloaded, i.e., that no cargo is loaded on the loading section 8, the unload valve 22 is maintained in the open state (step #404). In other words, in this case, in the interval operation, the time in the closed state is 0% and the time in the open state is 100%. If no cargo is loaded, the supply of hydraulic oil to the multiple hydraulic devices is stopped, thereby reducing the load on the engine 9a, suppressing fuel consumption and reducing noise.

[0073] When the unloading valve 22 is operated at intervals and when the unloading valve 22 is maintained in an open state, when the vehicle starts moving (step #405), a driving load is applied due to the driving of the running wheels 2, so the unloading valve 22 is returned to a state where it is maintained in a closed state (step #406).

[0074] In this configuration, determining the magnitude of the load is not limited to dividing it into three stages, but may also be divided into two stages, four or more stages, or continuously divided. In the case of continuously dividing it into stages, the driving load adjustment process may be configured to continuously change the ratio of the time in the blocked state to the time in the released state during interval operation between a blocked state maintained state in which the time in the blocked state is 100% and the time in the released state is 0% to a released state maintained state in which the time in the blocked state is 0% and the time in the released state is 100%.

[0075] (4) In the weight calculation process, for example, the total weight may be calculated by adding up the vertical ground contact pressures applied to the rotation axis of the traveling wheels 2, and the calculation method can be changed in various ways.

[0076] (5) As the tilt sensor S4, various sensors such as a weight-type tilt sensor or an optical fiber gyro may be used instead of an inertial measurement unit (IMU).

[0077] (6) The support mechanism A may be a mechanism having one link or three or more links, and may be provided with an electric actuator instead of a hydraulic cylinder.

[0078] (7) The traveling wheels 2 may be driven by an electric motor, an engine, or the like. [Industrial Applicability]

[0079] The present invention can be applied to a work vehicle that is suitable for traveling on uneven, rough terrain. [Explanation of symbols]

[0080] 1 Vehicle body 2 Running gear 4. Hydraulic system for travel 5 Hydraulic motor 6,7 Hydraulic system for changing attitude 9a engine 9b Hydraulic pump 21 Pressure oil supply path 22 Unloading valve HT change adjustment method SJ Loading status detection means

Claims

1. a vehicle body having a loading section capable of loading luggage; a plurality of traveling devices that are driven by a traveling hydraulic device and are located at the front and rear of both the left and right sides of the vehicle body; a plurality of support mechanisms supported by the vehicle body and driven by an attitude changing hydraulic device to support the traveling device so as to change its position relative to the vehicle body; a hydraulic pump that supplies hydraulic oil to the traveling hydraulic device and the attitude changing hydraulic device; an engine that drives the hydraulic pump; a loading status detection means for measuring the loading status of the cargo loaded on the loading section; a change / adjustment means for changing / adjusting the driving state of the engine in accordance with the difference in the load state of the luggage detected by the load state detection means, The loading status detection means measures the variation in the loading positions of the luggage relative to the loading section as the loading status, The change adjustment means determines the magnitude of the load caused by the luggage based on the detection results of the loading status detection means, and adjusts the engine output as the driving state of the engine so that if the load is large, the engine output is increased, and as the load becomes smaller, the engine output is decreased.

2. a vehicle body having a loading section capable of loading luggage; a plurality of traveling devices that are driven by a traveling hydraulic device and are located at the front and rear of both the left and right sides of the vehicle body; a plurality of support mechanisms supported by the vehicle body and driven by an attitude changing hydraulic device to support the traveling device so as to change its position relative to the vehicle body; a hydraulic pump that supplies hydraulic oil to the traveling hydraulic device and the attitude changing hydraulic device; a loading status detection means for measuring the loading status of the cargo loaded on the loading section; and a change / adjustment means for changing and adjusting the supply amount of the hydraulic oil in accordance with the difference in the load status of the luggage detected by the load status detection means, The loading status detection means measures the variation in the loading positions of the luggage relative to the loading section as the loading status, The change adjustment means determines the magnitude of the load caused by the luggage based on the detection results of the loading status detection means, and adjusts the amount of hydraulic oil supplied to be large if the load is large, and adjusts the amount of hydraulic oil supplied to be small as the load becomes smaller.

3. a vehicle body having a loading section capable of loading luggage; a plurality of travel devices that are driven to travel by hydraulic motors and are located at the front and rear of both the left and right sides of the vehicle body; a plurality of support mechanisms supported on the vehicle body and driven by hydraulic cylinders to support the traveling device so as to change its position relative to the vehicle body; a hydraulic pump that supplies hydraulic oil to the hydraulic motor and the hydraulic cylinder; a pressure oil supply passage for supplying the hydraulic oil from the hydraulic pump to the plurality of hydraulic motors and the plurality of hydraulic cylinders; an unloading valve that is switchable between an open state in which the pressure oil supply path is blocked to return the hydraulic oil from the hydraulic pump to a reservoir, and a blocked state in which the hydraulic oil is supplied to the plurality of hydraulic motors and the plurality of hydraulic cylinders through the pressure oil supply path; a loading status detection means for measuring the loading status of the cargo loaded on the loading section; and a change / adjustment means for changing and adjusting the supply amount of the hydraulic oil in accordance with the difference in the load status of the luggage detected by the load status detection means, The change adjustment means is capable of interval operation to alternately switch the unload valve between the closed state and the open state at a set period, and determines the magnitude of the load caused by the luggage based on the detection results of the loading status detection means, and adjusts the amount of hydraulic oil supplied to a large amount by lengthening the interval for the closed state if the load is large, and adjusts the amount of hydraulic oil supplied to a large amount by lengthening the interval for the open state as the load becomes smaller, thereby adjusting the amount of hydraulic oil supplied to a small amount.

4. 4. The work vehicle according to claim 3, wherein said load condition detection means measures the weight of said luggage as said load condition.

5. 4. The work vehicle according to claim 3, wherein the loading condition detection means measures, as the loading condition, variations in the loading positions of the cargo relative to the loading section.

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