Traveling vehicle

Abstract

To provide a traveling vehicle capable of using engine output without waste for respectively driving right and left traveling devices by hydraulic pressure of hydraulic fluid fed from a non-feedback type pump, facilitating steering wheel operation in consideration of a steering wheel angle corresponding to the size of a curve, and traveling on the curve at a proper speed without excessively reducing the speed on the curve.SOLUTION: The control unit 40 receives a signal of the steering wheel angle from the steering wheel angle detection unit 14a to detect that the traveling machine 10 is traveling on a curve, and controls the operation of the hydraulic control units 33L, 31R so that the control pressure of the swash plate of the non-feedback pump 31L, connected to the hydraulic motor 32L, 32R that drives the left or right traveling device 20L, 20R on the outer side of the curve increases according to the magnitude of the steering wheel angle. 33R.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle that travels by driving left and right traveling devices using hydraulic oil pressure sent from a non-feedback pump. [Background technology]

[0002] Conventionally, there are traveling vehicles called forwarders that travel by driving crawler-type traveling devices. Some of these traveling vehicles are equipped with a non-feedback pump (hydraulic pump), and the traveling vehicle travels by driving the left and right traveling devices with the hydraulic pressure of hydraulic oil sent from the non-feedback pump connected to the engine. Technologies related to traveling vehicles described in Patent Documents 1 and 2 are known as traveling vehicles equipped with such non-feedback pumps.

[0003] The technology of Patent Document 1 is a traveling vehicle configured to drive a pair of left and right traveling crawlers of a traveling work machine using separate left and right hydraulic drive means consisting of a hydraulic pump and a hydraulic motor, and to control the rotation speed of each left and right hydraulic motor by increasing or decreasing the output signal value to an electric actuator for the hydraulic pump, thereby performing steering control for straight travel and left and right turns. The steering control device in this traveling vehicle is provided with control means that determines the output of the hydraulic pumps on the inside and outside of a turn so that the sum of the drive forces of the left and right traveling crawlers during turn control is always constant, and further controls the drive force (rotation speed) with an electric signal.

[0004] The technology of Patent Document 2 is a hydraulically steered work vehicle that is configured to transmit engine power to left and right drive wheels via at least a torque converter and a differential steering means, and to transmit power of a hydraulic motor operated by pressurized oil from a hydraulic pump driven by the engine to the left and right drive wheels via the differential steering means. The work vehicle is provided with speed ratio calculation means that calculates the speed ratio of the torque converter, and pump absorption torque control means that controls the absorption torque of the hydraulic pump based on the speed ratio calculated by the speed ratio calculation means.

[0005] A non-feedback pump is a swash plate type piston pump that controls the discharge volume by changing the volume (amount pushed out in one stroke) according to the range of piston movement by tilting the swash plate. The volume decreases at high pressures, a phenomenon known as a block characteristic, which suppresses the load on the engine and prevents stalling.

[0006] However, when a crawler-type traveling device travels along a curve, the non-feedback pump of the traveling device on the outside of the curve becomes high pressure, while the non-feedback pump of the traveling device on the inside of the curve becomes low pressure or reverse pressure, and most of the engine output is consumed only to drive the traveling device on the outside of the curve.As a result, although there is surplus engine output, it cannot be fully used, which leads to a decrease in traveling speed.

[0007] In the technology of Patent Document 1, the steering control device is equipped with a control means that determines the output of the hydraulic pumps on the inside and outside of the turn so that the sum of the driving forces of the left and right traveling crawlers during turning control is always constant. However, because the sum of the driving forces is always constant, the steering angle according to the size of the curve is not taken into consideration, and even if the vehicle can gain speed on a curve, it may be difficult to steer and make the turn.

[0008] In the technology of Patent Document 2, the work vehicle controls the absorption torque of the hydraulic pump based on the speed ratio calculated by a speed ratio calculation means that calculates the speed ratio of the torque converter, but the steering angle according to the size of the curve is not taken into consideration, so even if the vehicle can gain speed on a curve, it may be difficult to steer and make the turn.In addition, although the absorption torque of the hydraulic pump is optimally controlled according to the driving load, the transmission of power to the left and right drive wheels uses a torque converter and a mechanical differential steering means, and the hydraulic pressure to each of the left and right drive wheels is not adjusted individually, so the control of either one is not adjusted appropriately. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 9-215406 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-273902 Summary of the Invention [Problem to be solved by the invention]

[0010] In view of the above, the present invention aims to provide a vehicle that can use engine output without waste to drive each of the left and right traveling devices using the hydraulic pressure of the hydraulic oil sent from a non-feedback pump, that takes into account the steering angle according to the size of the curve, that is easy to steer, and that can travel around curves at an appropriate speed without slowing down too much on curves. [Means for solving the problem]

[0011] According to an embodiment of the present invention, a traveling vehicle is provided that travels by driving left and right traveling devices respectively by hydraulic pressure of hydraulic oil sent from a non-feedback type pump, the left and right non-feedback pumps supplying hydraulic oil by the power of the prime mover; left and right hydraulic motors respectively driven by the hydraulic pressure of the hydraulic oil supplied from the left and right non-feedback pumps; left and right travel devices respectively connected to and driven by the left and right hydraulic motors; left and right hydraulic control units respectively connected to the left and right non-feedback pumps and controlling the swash plate angle by pressure; operation handles for operating the forward / reverse movement, left and right curve travel and turning of the traveling vehicle; a handle angle detection unit connected to the operation handles and detecting the handle angle of the operation handle; and a control unit for controlling the operation of the left and right hydraulic control units, The control unit receives a steering wheel angle signal from the steering wheel angle detection unit to detect that the vehicle is traveling around a curve, and controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pump connected to the hydraulic motor that drives the traveling device on either the left or right side of the outside of the curve increases according to the magnitude of the steering wheel angle.

[0012] According to this configuration, the traveling vehicle includes left and right non-feedback pumps that supply hydraulic oil using power from a prime mover, left and right hydraulic motors that are driven by the hydraulic pressure of the hydraulic oil supplied from the left and right non-feedback pumps, left and right traveling devices, left and right hydraulic control units connected to the left and right non-feedback pumps, respectively, and controlling the swash plate angle using pressure, an operating handle, a steering angle detection unit that detects the steering angle of the operating handle, and a control unit that controls the operation of the left and right hydraulic control units. The control unit receives a steering angle signal from the steering angle detection unit to detect that the traveling vehicle is traveling around a curve, and controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pump connected to the hydraulic motor that drives either the left or right traveling device on the outside of the curve increases according to the magnitude of the steering angle. This takes into account the steering angle according to the magnitude of the curve, making it easy to operate the steering wheel and allowing the vehicle to travel around the curve at an appropriate speed without slowing down too much.

[0013] Furthermore, the traveling vehicle is equipped with left and right hydraulic motors that are respectively driven by the hydraulic pressure of the hydraulic oil sent from the left and right non-feedback pumps, left and right traveling devices, and left and right hydraulic control units that are respectively connected to the left and right non-feedback pumps and control the swash plate angle by pressure, so that the left and right traveling devices can be driven by the hydraulic pressure of the hydraulic oil sent from the non-feedback pumps and the engine output can be used without waste.

[0014] Preferably, the control unit detects that the vehicle is traveling around a curve, and controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pump connected to the hydraulic motor that drives the traveling device on the outside of the curve exceeds the maximum value when traveling straight and rises to an upper control pressure limit.

[0015] With this configuration, the control unit detects that the vehicle is traveling around a curve and controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pump connected to the hydraulic motor that drives the traveling device on the outside of the curve exceeds the maximum value when traveling straight and rises to the upper control pressure limit.This prevents a decrease in the volume through which the piston of the non-feedback pump can move, and makes maximum use of engine output without waste.

[0016] Preferably, the construction machine is one of a construction machine having a crawler-type traveling device, a construction machine equipped with a work attachment, and a construction machine that turns by using a speed difference between the left and right traveling devices.

[0017] With this configuration, the running gear can be either a crawler-type construction machine, a construction machine equipped with a work attachment, or a construction machine that turns by using the speed difference between the left and right running gear, so it is suitable for construction machines that run using left and right running gear driven by hydraulic motors, and in various construction machines, the steering angle can be taken into account according to the size of the curve, making it easy to operate the steering and allowing the machine to run around curves at an appropriate speed without slowing down too much. [Effects of the Invention]

[0018] To provide a traveling vehicle which can use engine output without waste to drive the left and right traveling devices respectively by the hydraulic pressure of the working oil sent from a non-feedback pump, can take into consideration the steering angle according to the size of the curve, can easily operate the steering wheel, and can travel around a curve at an appropriate speed without slowing down too much on the curve. [Brief explanation of the drawings]

[0019] [Figure 1] 1A is a plan view of a vehicle according to an embodiment, and FIG. 1B is a side view of the left side of the vehicle according to an embodiment. [Figure 2] 1 is an explanatory diagram of a main part of a traveling vehicle according to an embodiment. [Figure 3] 1 is an explanatory diagram of a circuit configuration of a hydraulic control system provided in a traveling vehicle according to an embodiment. [Figure 4] 1A is a diagram showing the relationship between the solenoid current of a proportional control valve and the stroke volume of a non-feedback pump, and FIG. 1B is a diagram showing the block characteristics of a non-feedback pump according to an embodiment. [Figure 5] (A) is a diagram explaining the flow of action of the proportional control valve, the swash plate of the non-feedback pump, and the discharge volume. (B) is a schematic diagram explaining the change in oil pressure of the non-feedback pump (distribution of engine output) when a typical vehicle is traveling around a curve. [Figure 6] 1 is a diagram illustrating changes in hydraulic pressure of left and right non-feedback pumps when a typical vehicle is traveling on a curve and when traveling in a straight line. FIG. [Figure 7] FIG. 2 is a control flow diagram of a traveling vehicle according to an embodiment. [Figure 8] 10A and 10B are diagrams illustrating current control of a proportional control valve for the outside of a curve when a traveling vehicle according to an embodiment is traveling on a curve. [Figure 9] 1A is an operational diagram illustrating the change in oil pressure (distribution of engine output) of the non-feedback pump when a vehicle of a comparative example is traveling around a curve, and FIG. 1B is an operational diagram illustrating the change in oil pressure (distribution of engine output) of the non-feedback pump when a vehicle of an embodiment is traveling around a curve. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present invention with reference to the accompanying drawings. The operation diagrams show a traveling vehicle 10 conceptually (schematically). [Example]

[0021] 1 and 2, the traveling vehicle 10 is a type known as a forwarder that travels by driving left and right crawler-type traveling devices 20L, 20R (L indicates left and R indicates right, the same applies below). The traveling vehicle 10 includes a main body 11, a prime mover (engine) 12 provided in the main body 11 as a power source, left and right traveling devices 20L, 20R provided on the left and right sides of the main body 11 in the vehicle width direction, an operation room (cabin) 13 provided at the front of the main body 11, an operation handle 14 provided in the operation room 13 for driving the left and right traveling devices 20L, 20R to control the traveling vehicle 10 to move forward and backward, turn left and right, and turn, and a lift-up type loading platform 15 provided at the upper rear of the main body 11 on which cargo such as lumber is placed.

[0022] The left and right traveling devices 20L, 20R are equipped with a rubber crawler 21 in the form of a caterpillar belt, a sprocket 22 that receives power and drives the crawler 21, a track roller 23 that smoothly rotates the crawler 21, and a rear idler 24 that supports the crawler 21 and follows it.

[0023] In addition, the traveling vehicle 10 travels by driving the left and right traveling devices 20L, 20R using the hydraulic pressure of the hydraulic oil sent from the left and right non-feedback pumps 31L, 31R, respectively, and is equipped with a hydraulic system 30 consisting of hydraulic equipment, etc.

[0024] The hydraulic system 30 includes a prime mover (engine) 12, left and right non-feedback pumps (hydraulic pumps) 31L, 31R that send hydraulic oil using the power of the prime mover 12, left and right hydraulic motors 32L, 32R that are driven by the hydraulic pressure of the hydraulic oil sent from the left and right non-feedback pumps 31L, 31R, respectively, and left and right traveling devices 20L, 20R that are connected to and driven by the left and right hydraulic motors 32L, 32R, respectively.

[0025] The hydraulic system 30 also includes left and right hydraulic control units 33L, 33R connected to the left and right non-feedback pumps 31L, 31R, respectively, and controlling the swash plate angle by pressure, an operating handle 14 for operating the forward / reverse movement, left and right curve driving, and turning of the traveling vehicle 10, a steering angle detection unit 14a connected to the operating handle 14 and detecting the steering angle of the operating handle 14, and a control unit 40 for controlling the operation of the left and right hydraulic control units 33L, 33R.

[0026] The control unit 40 receives a steering wheel angle signal from the steering wheel angle detection unit 14a to detect that the traveling vehicle 10 is traveling on a curve, and controls the operation of the hydraulic control units 33L, 33R so that the control pressure of the swash plates of the non-feedback pumps 31L, 31R connected to the hydraulic motors 32L, 32R that drive either the left or right traveling device 20L, 20R on the outside of the curve increases according to the magnitude of the steering wheel angle.

[0027] The control unit 40 also receives a steering wheel angle signal from the steering wheel angle detection unit 14a to detect that the traveling vehicle 10 is traveling on a curve, and controls the operation of the hydraulic control units 33L, 33R so that the control pressure of the swash plates of the non-feedback pumps 31L, 31R connected to the hydraulic motors 32L, 32R that drive the traveling devices 20L, 20R on the outside of the curve exceeds the maximum value when traveling straight and rises to the control pressure upper limit.

[0028] Next, the hydraulic system 30 will be described. Only the main components shown in the drawings will be described. Furthermore, for components that are the same on both sides, only the left component will be described, and the right component will be assigned the same reference numeral and description thereof will be omitted.

[0029] As shown in Figures 2 and 3, the hydraulic system 30 includes a left non-feedback pump 31L driven by the prime mover 12, left and right hydraulic control units 33L connected to the left non-feedback pump 31L and controlling the swash plate angle by pressure, a left hydraulic motor 32L driven by the hydraulic pressure of the hydraulic oil sent from the left non-feedback pump 31L, and a left sprocket 22 (left traveling device 20L) connected to and driving the left hydraulic motor 32L.

[0030] The non-feedback pump 31L is a variable displacement hydraulic pump, and the flow rate (discharge flow rate) of the hydraulic oil discharged from the discharge port can be changed by controlling the tilt angle of the swash plate with the hydraulic control unit 33L.

[0031] The hydraulic control unit 33L includes an actuator (hydraulic cylinder) 34L connected to the non-feedback pump 31L to switch the forward / reverse direction and adjust the tilt angle of the swash plate, a left front proportional control valve 35L and a left rear proportional control valve 36L that control the operation of the actuator 34L, and a throttle check valve 37L provided between these proportional control valves 35L, 36L and the actuator 34L.

[0032] The traveling device 20L portion of the hydraulic system 30 is equipped with a left hydraulic motor 32L, an actuator 41L for releasing the parking of the left hydraulic motor 32L, a solenoid valve 44 for releasing the parking, a pressure switch 45 connected to the solenoid valve 44, a mode switching actuator 46L for switching between high and low speed modes of the left hydraulic motor 32L, a mode switching valve 47L for switching the supply of hydraulic oil to the mode switching actuator 46L, a mode switching solenoid valve 48 for sending hydraulic oil to the mode switching valve 47L, and a pressure sensor.

[0033] In addition, the lift-up type cargo bed 15 (see Figure 1), which is a working device of the hydraulic system 30, is equipped with a gear pump 51 that discharges hydraulic oil from an oil tank 50, and a dump switching valve 53 that switches the return of hydraulic oil from the gear pump 51 to a dump cylinder 52 that lifts up the cargo bed 15.

[0034] Next, the flow of hydraulic oil and the HST will be explained. The non-feedback pump 31L and travel motor (hydraulic motor) 32L form a closed circuit (HST: hydrostatic transmission). The hydraulic oil discharged at high pressure from the non-feedback pump 31L turns the travel motor 32L, then comes out of the travel motor 32L at low pressure and returns to the non-feedback pump 31L, before being discharged again at high pressure from the non-feedback pump 31L. This circuit is constantly pressurized at a constant pressure by the hydraulic oil discharged from the gear pump 51 through the charge valve. A certain amount of hydraulic oil in the circuit is returned to the oil tank 50 through flushing valves 42L and 43L, and that amount is replaced with clean hydraulic oil by the gear pump 51.

[0035] The hydraulic oil for each valve is sent from the oil tank 50 through a strainer 66 and an oil passage 67 to the gear pump 51, and from the gear pump through an oil passage 68 to the front left proportional control valve 35L and the rear left proportional control valve 36L via a filter 69 and various valves. After passing through the filter 69, the hydraulic oil passes through an oil passage 71, and a portion of it is sent from the parking release solenoid valve 44 through an oil passage 72 to the left actuator 41L, and a portion of it is sent from the mode switching solenoid valve 48 through an oil passage 73 to the left mode switching valve 47L. The hydraulic oil sent to the left actuator 41L returns through the oil passage 72, passes through the switched solenoid valve 44, and passes through an oil passage 74 to return to the oil tank 50.

[0036] The pressure sensor, valves, switches, etc. are electrically connected to the control unit 40 (electrical wiring is not shown), and their operations are controlled.

[0037] Next, the relationship between the solenoid current of the proportional control valve and the stroke volume of the non-feedback pump will be explained. As shown in Figure 4(A), the stroke volume [cm ] of the non-feedback pump changes over a certain range of solenoid current [A] including 0. 3 / rev] is 0, but when the solenoid current exceeds a certain range including 0, the stroke volume increases in proportion to the increase in solenoid current. Also, when a non-feedback pump becomes highly pressurized, even if the solenoid current remains the same, the block characteristics cause the stroke volume to decrease and the discharge volume to decrease. A decrease in the discharge volume of a non-feedback pump results in a decrease in the speed of the running equipment (vehicle).

[0038] Next, the blocking characteristics of the non-feedback pump (pump) according to the embodiment will be described. Engine output ≥ power to rotate the pump = circuit pressure x discharge flow rate. If either the circuit pressure or flow rate remains constant and the other increases, the power to rotate the pump will exceed the engine output and the engine will stop. If the maximum power to rotate the pump is set to 100, block control reduces the discharge flow rate as the circuit pressure increases to prevent the engine from stopping, and prevents the power to rotate the pump from increasing above 100. Non-feedback pumps perform the above control by utilizing the characteristic that when the circuit pressure becomes high, the swash plate is pushed by the pressure and returned in the direction of decreasing the discharge rate.

[0039] Next, the flow of action of the proportional control valve, the swash plate of the non-feedback pump, and the discharge amount will be explained. As shown in FIG. 5(A), in a non-feedback pump, in STEP 1 (STEP is indicated as S in the figure), the proportional control valve is operated by the current from the control unit 40, in STEP 2 the swash plate control pressure of the non-feedback pump (the pressure that tilts the swash plate) is determined, and in STEP 3 the pump tilt angle determines the discharge amount of hydraulic oil, and this discharge amount determines the speed of the traveling device (traveling vehicle).

[0040] Next, we will explain the change in oil pressure of the non-feedback pump (distribution of engine output) when a typical vehicle is traveling around a curve. As shown in Figure 5(B), when a typical traveling vehicle 100 travels on a straight section of the road, the pressure PL of the non-feedback pump of the left traveling device 20L and the pressure PR of the non-feedback pump of the right traveling device 20R are both large (large pressure).

[0041] When a typical traveling vehicle 100 reduces the speed of the right traveling unit 20R and travels around a curve, the pressure PL of the non-feedback pump of the traveling unit 20L on the outside of the curve is large (large pressure), but the pressure PR of the non-feedback pump of the traveling unit 20R on the inside of the curve is small (small pressure) or becomes negative (counter pressure). This reduces the combined speed of the outside traveling unit 20L and the inside traveling unit 20R, and the speed of the traveling vehicle 100 as a whole is also slowed down.

[0042] Next, the changes in the hydraulic pressure of the left and right non-feedback pumps when a typical vehicle is traveling on a curve and on a straight line will be described. As shown in Figure 6, when a typical vehicle enters a curve, the pressure of the non-feedback pump is high on the outside of the curve and low or reverse pressure on the inside of the curve, and the output of the prime mover (engine) is consumed almost exclusively for driving the outside, leaving some output to spare. At this time, if the outside circuit pressure increases due to running resistance, the volume of the outside pump decreases due to the block characteristics, even though there is still some engine output to spare, causing the speed of the vehicle to decrease. Also, when the vehicle enters a straight line, the speed on the inside increases, and the overall speed of the vehicle 100 returns to maximum speed.

[0043] Next, a control flow of a traveling vehicle according to the embodiment will be described. As shown in FIG. 7, in the traveling vehicle 10 of the embodiment, when a lever input to the operating handle 14 is detected (STEP 4), it is determined whether the traveling vehicle 10 is traveling on a curve (STEP 5), and if NO, the control pressures of the left and right non-feedback pumps 31L, 31R are at steady-state values ​​(STEP 6), and if YES, the allowable control pressures of the non-feedback pumps 31L, 31R that drive the hydraulic motors 32L, 32R on the outside of the curve are increased (STEP 7).

[0044] Next, the current control of the proportional control valve for the outside of the curve when the vehicle according to the embodiment is traveling on a curve will be described. As shown in Figure 8, the lower part of the figure shows the pump pressure. When the traveling vehicle enters a curve, the pressure of the non-feedback pump becomes high on the outside of the curve and low or reverse pressure on the inside of the curve. At this time, the current value of the proportional control valves 35, 36, which are connected to the operation of the non-feedback pumps 31L, 31R on the outside of the curve, is increased compared to when traveling straight. This suppresses a decrease in the volume of the non-feedback pumps 31L, 31R on the outside of the curve and prevents a decrease in traveling speed. That is, the system detects that the traveling vehicle 10 is traveling around a curve from the lever input of the operating handle 14, and increases the current value of the proportional control valves 35, 36, which are connected to the operation of the non-feedback pumps 31L, 31R on the outside of the curve, compared to when traveling straight, thereby suppressing a decrease in volume at high pressure and preventing a decrease in traveling speed.

[0045] Next, the change in oil pressure of the non-feedback pump (the distribution of engine output) and its operation when the traveling vehicle 100 of the comparative example travels around a curve will be described. As shown in Figure 9(A), when the comparative example traveling vehicle 100 is traveling straight on the traveling path 80, the oil pressure PL of the left traveling device 20L is 100 (a numerical value indicating a ratio), and the oil pressure PR of the right traveling device 20R is 100, and the total is 200, and the engine output is being used to the maximum.

[0046] When the traveling vehicle 100 of the comparative example enters the curve 81, the hydraulic pressure PL of the left traveling device 20L on the outside of the curve remains at 100, but the hydraulic pressure PR of the right traveling device 20R on the inside of the curve becomes 50, and the total becomes 150, so that the engine output is not fully used (a state in which there is some reserve power), but when the traveling resistance increases and the hydraulic pressure PL exceeds 100, the speed of the traveling device 20L decreases due to the block characteristics, and the traveling speed of the traveling vehicle 100 slows down.

[0047] Next, the change in oil pressure of the non-feedback pump (the distribution of engine output) when the vehicle 10 of the embodiment is traveling around a curve will be described together with its operation. As shown in Figure 9(B), when the vehicle 10 of the embodiment is traveling straight on the roadway 80, the oil pressure PL of the left traveling device 20L is 100 (a numerical value indicating a ratio), and the oil pressure PR of the right traveling device 20R is 100, for a total of 200, and the engine output is being used to the maximum.

[0048] When the traveling vehicle 10 of this embodiment enters the curve 81, the hydraulic pressure PR of the right traveling unit 20R on the inside of the curve becomes 50, generating excess power. When it is detected that the traveling vehicle 10 is traveling on a curve, the hydraulic pressure of the non-feedback pump 31L connected to the hydraulic motor 32L that drives the traveling unit 20L on the outside of the curve exceeds the maximum value of 100 for traveling straight, but the system suppresses the blocking characteristic and controls the excess power 25 so that it can be used by the traveling unit 20L on the outside of the curve.

[0049] The control pressure of the swash plate of the non-feedback pump 31L connected to the hydraulic motor 32L that drives the traveling device 20L on the outside of the curve may be increased above the maximum value during straight traveling, so that the total hydraulic pressure on the outside and inside of the curve increases up to the engine output upper limit 200. This allows the engine output to be used effectively, and a decrease in the traveling speed of the traveling vehicle 10 can be suppressed.

[0050] Next, the operation and effects of the traveling device 10 of the embodiment described above will be explained. In an embodiment of the present invention, a traveling vehicle 10 includes left and right non-feedback pumps 31L, 31R that supply hydraulic oil using the power of a prime mover 12, left and right hydraulic motors 32L, 32R that are driven respectively by the hydraulic pressure of the hydraulic oil supplied from the left and right non-feedback pumps 31L, 31R, left and right traveling devices 20L, 20R, left and right hydraulic control units 33L, 33R that are connected respectively to the left and right non-feedback pumps 31L, 31R and control the swash plate angle using pressure, an operating handle 14, a handle angle detection unit 14a that detects the handle angle of the operating handle 14, and a control unit 40 that controls the operation of the left and right hydraulic control units 33L, 33R. The control unit 40 receives a steering wheel angle signal from the steering wheel angle detection unit 14a to detect that the traveling vehicle 10 is traveling around a curve, and controls the operation of the hydraulic control units 33L, 33R so that the hydraulic pressure of the non-feedback pumps 31L, 31R connected to the hydraulic motors 32L, 32R that drive either the left or right traveling device 20L, 20R on the outside of the curve increases according to the magnitude of the steering wheel angle.This takes into account the steering wheel angle according to the magnitude of the curve, making it easy to operate the steering wheel and allowing the vehicle to travel around the curve at an appropriate speed without slowing down too much.

[0051] Furthermore, the traveling vehicle 10 is equipped with left and right hydraulic motors 32L, 32R that are driven by the hydraulic pressure of the hydraulic oil sent from the left and right non-feedback pumps 31L, 31R, respectively, left and right traveling devices 20L, 20R, and left and right hydraulic control units 33L, 33R that are connected to the left and right non-feedback pumps 31L, 31R, respectively, and that control the swash plate angle by pressure, so that the left and right traveling devices 20L, 20R can be driven by the hydraulic pressure of the hydraulic oil sent from the non-feedback pumps 31L, 31R, respectively, and the engine output can be used without waste.

[0052] Furthermore, the control unit 40 detects that the traveling vehicle 10 is traveling on a curve, and controls the operation of the hydraulic control units 33L, 33R so that the control pressure of the swash plates of the non-feedback pumps 31L, 31R connected to the hydraulic motors 32L, 32R that drive the traveling devices 20L, 20R on the outside of the curve exceeds the maximum value when traveling straight and rises to the upper control pressure limit.This prevents a decrease in the volume through which the pistons of the non-feedback pumps 31L, 31R can move, and makes it possible to use the engine output to the maximum extent possible without waste.

[0053] Furthermore, since the traveling device 10 is either a crawler-type construction machine, a construction machine equipped with a work attachment, or a construction machine that turns by using the speed difference between the left and right traveling devices, it is suitable for construction machines that travel using the left and right traveling devices by driving the hydraulic motors 32L, 32R, and in various construction machines, the steering angle according to the size of the curve is taken into consideration, making it easy to operate the steering and allowing the machine to travel around curves at an appropriate speed without slowing down too much.

[0054] In the embodiment, the traveling vehicle 10 is a forwarder that travels by driving a crawler-type traveling device, but this is not limited to this, and the traveling vehicle 10 may also be a construction machine with a crawler-type traveling device, a construction machine equipped with a work attachment, or a construction machine that turns by using the speed difference between the left and right traveling devices.

[0055] In addition, in the embodiment, the traveling devices 20L, 20R are rubber crawler type, but this is not limited to this, and they may also be made of steel plates cut into strips and joined together to form a ring that is hung on the front and rear sprockets and rear idlers.

[0056] In addition, in the embodiment, when the traveling vehicle 10 enters the curve 81, the oil pressure PR of the right traveling unit 20R on the inside of the curve is set to 50 (a numerical value indicating a ratio), and the remaining pressure of 25 is used by the left traveling unit 20L on the outside of the curve, making the oil pressure PL of the traveling unit 20L on the outside of the curve 125, and the total is 175, but this is not limited to this, and as long as the control pressure of the swash plate of the non-feedback pump 31L connected to the hydraulic motor 32L that drives the traveling unit 20L on the outside of the curve can be controlled to exceed the maximum value when traveling straight, the total oil pressure of the outside and inside can be controlled to rise to a value between 200 and the engine output upper limit.

[0057] Furthermore, in the embodiment, the control unit 40 controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pumps 31L, 31R on the outside of the curve increases in proportion to the magnitude of the steering wheel angle, but this is not limited to this, and the operation of the hydraulic control unit may be controlled so that the control pressure of the swash plate of the non-feedback pumps 31L, 31R on the outside of the curve increases in stages according to the range of the magnitude of the steering wheel angle, and other methods of increasing the hydraulic pressure of the hydraulic control unit on the outside of the curve according to the magnitude of the steering wheel angle may be used as long as the driver can travel around the curve comfortably without feeling a decrease in speed of the traveling vehicle 10.

[0058] In the embodiment, the non-feedback pumps 31L, 31R are swash plate type variable displacement hydraulic pumps, but this is not limited thereto and other types of general variable displacement hydraulic pumps may be used as long as the volume can be varied. In the embodiment, the hydraulic control units 33L, 33R are configured with actuators 34L, 34R and proportional control valves 35L, 35R, 36L, 36R, but this is not limited thereto and other types of mechanisms, such as general actuators, may be used as long as the swash plate angles of the non-feedback pumps 31L, 31R can be adjusted.

[0059] That is, the present invention is not limited to the examples as long as the functions and effects of the present invention are exhibited. [Industrial Applicability]

[0060] The technology of the present invention is suitable for a vehicle that travels by driving left and right traveling devices respectively with the hydraulic pressure of hydraulic oil sent from a non-feedback pump. [Explanation of symbols]

[0061] 10...Traveling vehicle (forwarder, hydraulic excavator, construction machinery), 12...Prime mover (engine, motor), 14...Operating handle (operating lever), 14a...Steering wheel angle detection unit (angle sensor), 20L, 20R...Traveling device, 21...Crawler, 22...Sprocket, 30...Hydraulic system, 31L, 31R...Non-feedback pump (hydraulic pump), 32L, 32R...Hydraulic motor, 33L, 33R...Hydraulic control unit, 34L, 34R...Actuator, 35L, 35R...Front proportional control valve, 36L, 36R...Rear proportional control valve, 40...Control unit, 41L, 41R...Actuator, 80...Traveling path, 81...Curve

Claims

1. A vehicle that runs by driving left and right traveling devices respectively using hydraulic oil pressure sent from a non-feedback pump, the left and right non-feedback pumps supplying hydraulic oil by the power of the prime mover; left and right hydraulic motors respectively driven by the hydraulic pressure of the hydraulic oil supplied from the left and right non-feedback pumps; left and right travel devices respectively connected to and driven by the left and right hydraulic motors; left and right hydraulic control units respectively connected to the left and right non-feedback pumps and controlling the swash plate angle by pressure; operation handles for operating the forward / reverse movement, left and right curve travel and turning of the traveling vehicle; a handle angle detection unit connected to the operation handles and detecting the handle angle of the operation handle; and a control unit for controlling the operation of the left and right hydraulic control units, the control unit receives a steering wheel angle signal from the steering wheel angle detection unit to detect that the vehicle is traveling around a curve, and controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pump connected to the hydraulic motor that drives either the left or right traveling device on the outside of the curve increases in accordance with the magnitude of the steering wheel angle.

2. The vehicle according to claim 1, The control unit detects that the vehicle is traveling on a curve, and controls the operation of the hydraulic control unit so that the control pressure of the swash plate of the non-feedback pump connected to the hydraulic motor that drives the traveling device on the outside of the curve exceeds the maximum value when traveling straight and rises to an upper control pressure limit.

3. The traveling vehicle according to claim 1 or claim 2 comprises: A traveling vehicle characterized in that the traveling device is either a crawler-type construction machine, a construction machine equipped with a work attachment, or a construction machine that turns by using a speed difference between the left and right traveling devices.

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