JPH04282072A - Travel control device for hydraulically-driven vehicle - Google Patents

Abstract

PURPOSE:To improve the safety by comparing the main lines of hydraulic transmission devices in relation to a right and a left travel devices to select the high pressure side main line, and inputting high pressure side oil pressure to driving actuators. CONSTITUTION:Hydraulic pumps 2L, 2R are driven to make the pressure of the first main lines 4L, 4R of hydraulic transmission devices 6L, 6R high and to make the pressure of second main lines 5L, 5R low, and hydraulic motors 3L, 3R are driven/rotated normally to perform a travel by a left and a right travel devices 7L, 7R. At this time, shuttle valves 131L, 131R are moved in the directions of arrow marks by the pressure from lines 130L, 130R, then the first main lines 4L, 4R are communicated with high pressure lines 132L, 132R, and a second shuttle valve 140 is moved onto one side by the pressure difference between the high pressure lines 132L, 132R. When the pressure of the line 132L is high, for instance, the shuttle valve 140 is moved in the direction of an arrow mark, and the pressure of the first high pressure line 132L acts upon driving actuators 10L, 10R through input circuits 11b, 11b. Load difference, generated according to the road surface state, between the left and right travel devices 7L, 7R can be thereby corresponded to.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control system for hydraulically driven vehicles used in ski slope maintenance vehicles, asphalt finishers, transport vehicles, automatic guided vehicles, agricultural machines, and the like.

0002

2. Description of the Related Art Conventionally, a hydraulically driven vehicle such as a ski slope maintenance vehicle is described in, for example, Japanese Utility Model Application Publication No. 171412/1983. As shown in FIG. 4, this conventional hydraulically driven vehicle has capacity control elements 1L and 1R, and a pair of variable hydraulic pumps 2L and 2 driven by an engine (not shown).
R and a pair of hydraulic motors 30L and 30R, respectively.
Main lines 4L, 4R and second main lines 5L, 5
A pair of hydraulic transmission devices 6L, 6 connected by R to form a closed circuit.
A left and right traveling device 7 is connected to the output shaft of each hydraulic motor 30L, 30R in these hydraulic transmission devices 6L, 6R.
By interlocking L and 7R, these left and right traveling devices 7L and 7R
The capacity control elements 1L and 1R in the variable hydraulic pumps 2L and 2R are configured to be driven independently.
Throttle change-over valves 8L and 8R are provided to control the tilting of the travel devices 7L and 7R, and by operating these throttle change-over valves 8L and 8R, the capacity control elements 1L and 1R are controlled, and the rotation direction and rotation speed of the traveling devices 7L and 7R are controlled. I'm trying to control it.

[0003] Also, conventionally, each of the hydraulic transmission devices 6L, 6R
As shown in FIG. 3, the hydraulic motors 30L and 30R in FIG. The rods of drive actuators 10L and 10R consisting of rod-type cylinders are connected, and the input circuits 11a and 11a of the head chambers 10a and 10a in these drive actuators 10L and 10R are operated by a capacity control command signal, and the drive actuator 10L is operated by a capacity control command signal.
, 10R, and the first main lines 4L, 4R and the second main line 5L in each of the hydraulic transmission devices 6L, 6R,
5R and connecting lines 130L and 130R connected to the first
Main line 4L, 4R and second main line 5L, 5R
Shuttle valves 131L, 131R select one of the high-pressure side main lines by comparing the pressure with
High voltage selection circuits 13L and 13R are provided, and the high voltage lines 132L and 132R are connected to the respective input circuits 11a and 1 of the drive actuators 10L and 10R.
1b, and by the operation of the control valve devices 12L and 12R based on the capacity control command signal, the high pressure selection circuit 13L
, 13R is supplied to each of the drive actuators 10L, 10R, and these drive actuators 10L, 10R are driven to advance to adjust the tilt of the displacement control elements 9L, 9R in each hydraulic motor 3L, 3R. A travel control device has also been developed in which the amount of rotation is reduced and each of the hydraulic motors 3L, 3R is driven at high speed to independently drive the left and right travel devices 7L, 7R at high speed.

0004

[Problems to be Solved by the Invention] However, in the traveling control device shown in FIG. High pressure side main line 4L, 4R or 5
L and 5R are selected, and the displacement control elements 9L and 9R in each hydraulic motor 3L and 3R are individually tilted and controlled by the two independent self-pressures of these high-pressure side main lines to adjust the rotational speed of each hydraulic motor 3L and 3R. Therefore, when a hydraulically driven vehicle is running, if there is a difference in the load between the left and right traveling devices 7L and 7R due to uneven road surfaces, the hydraulic pressure transmission that drives the high-load traveling device 7L or 7R is activated. The closed circuit pressure in the device 6L or 6R is lower than the pressure in the low load side traveling device 7L.
Or, the pressure becomes higher than the closed circuit pressure in the hydraulic transmission device 6L or 6R that drives the hydraulic motor 7R, and the hydraulic motor 3L, 3
A difference occurs in the responsiveness of the capacity control elements 9L and 9R in R, and this difference in responsiveness of the capacity control elements 9L and 9R causes a speed difference between the hydraulic motors 3L and 3R, as well as between the left and right traveling devices 7L and 7R, and the vehicle It was dangerous as it would swing from side to side.

The present invention was devised in view of the above points, and an object thereof is to control the displacement control element in each hydraulic motor by the self-pressure of the closed circuit in each hydraulic transmission device, and to improve the responsiveness of this displacement control element. without any difference in
An object of the present invention is to provide a travel control device that allows a vehicle to travel stably.

[0006]

[Means for Solving the Problems] The present invention provides variable hydraulic pumps 2L and 2R having capacity control elements 1L and 1R.
and a variable hydraulic motor 3L with capacity control elements 9L and 9R,
A pair of hydraulic transmission devices 6L and 6 connected with 3R in a closed circuit.
R, the left and right traveling devices 7L, 7R are independently driven by the respective hydraulic motors 3L, 3R, and each of the hydraulic transmission devices 6L is connected to each capacity control element 9L, 9R of each of the hydraulic motors 3L, 3R. , 6R are provided, and the input circuit 11 of these drive actuators 10L, 10R is provided.
a, 11b, a control valve device 12 that operates in response to a capacity control command signal and controls the drive of the actuators 10L, 10R;
A traveling device for a hydraulically driven vehicle provided with L and 12R,
Connected to the first main lines 4L, 4R and second main lines 5L, 5R in the closed circuit of each of the hydraulic transmission devices 6L, 6R, and connected to the first main lines 4L, 4R and the second main lines 5L, 5R. A first high voltage selection circuit 13L, 13R is provided for comparing the pressures and selecting the high voltage side main line, and a second high voltage selection circuit is provided for comparing the pressures of the first high voltage selection circuits 13L, 13R and selecting the high voltage side selection circuit. A selection circuit 14 is provided, and this second high voltage selection circuit 14 is connected to the input circuits 11a and 11 of the drive actuators 10L and 10R.
b.

[0007]

[Operation] When the vehicle is running by driving each hydraulic pump 2L, 2R, a capacity control command signal causes the hydraulic motors 3L, 3R to move through the control valve devices 12L, 12R.
At this time, when one of the first main lines 4L, 4R and the second main lines 5L, 5R becomes high pressure and the other becomes low pressure, the high pressure side main line changes to each first high pressure. Selected by the selection circuits 13L and 13R, furthermore, the circuit which becomes high voltage among these first high voltage selection circuits 13L and 13R is selected by the second high voltage selection circuit 14, and the highest voltage selected by the second high voltage selection circuit 14 is selected. Each drive actuator 10L, 10R is driven by the pressure, and each displacement control element 9 in each hydraulic motor 3L, 3R is driven.
L and 9R are controlled, and the driving speed of each hydraulic motor 3L and 3R can be controlled. In this way, the highest main line pressure in the closed circuit in each hydraulic transmission device 6L, 6R is selected, and each drive actuator 10L, 10R is operated by the same selected pressure, so that the road surface when the vehicle is running is controlled. Due to unevenness etc., the left and right traveling devices 7L, 7
Due to a difference in the load on the R side, each hydraulic transmission device 6L, 6R
Even if a difference occurs in the pressure in the closed circuit, it is possible to prevent a difference in response between the respective capacity control elements 9L and 9R, prevent the vehicle from swinging from side to side, and enable stable running. It will become.

[0008]

[Embodiment] Figs. 1 and 2 show a traveling control device of the present invention applied to a crawler type hydraulically driven vehicle. In the figures, parts having the same structure as those in Figs. 3 and 4 described above are designated by the same reference numerals. I will explain.

The travel control device shown in FIGS. 1 and 2 has capacity control elements 1L and 1R consisting of swash plates, and adjusts the discharge amount and changes the discharge direction by controlling the tilting of the capacity control elements 1L and 1R. A pair of variable hydraulic pumps 2L and 2R that enable
and a pair of variable hydraulic motors 3L, 3R having displacement control elements 9L, 9R consisting of oblique shafts, and whose drive speeds can be controlled by tilting control of these displacement control elements 9L, 9R, respectively, are connected to the first main line. 4L, 4R and the second main lines 5L, 5R are connected to form a pair of closed circuit hydraulic transmission devices 6L, 6R, and the left and right lines are connected to the output shafts of the respective hydraulic motors 3L, 3R in these hydraulic transmission devices 6L, 6R. By interlocking the traveling devices 7L and 7R, and driving the respective hydraulic pumps 2L and 2R by starting the engine E, the left and right traveling devices 7L and 7R are independently driven. In addition, the rods of drive actuators 10L and 10R each consisting of a single-rod type cylinder are connected to each capacity control element 9L and 9R of each of the hydraulic motors 3L and 3R, and each head chamber 1 of each of the drive actuators 10L and 10R is
The input circuits 11a and 11a communicating with the actuators 10L and 10a are operated by a capacity control command signal, and the actuators 10L,
The first main lines 4L, 4R and the second main lines 5L, 5 in each of the hydraulic transmission devices 6L, 6R are interposed with control valve devices 12L, 12R that control the drive of the hydraulic transmission device 10R.
The pressures of the first main lines 4L, 4R and the second main lines 5L, 5R are compared and the pressure of either one is High pressure side main line 4L
, 4R or 5L, 5R first shuttle valve 131
L, 131R, and these first shuttle valves 131L, 13
A first high voltage selection circuit 13L, 13R consisting of a first high voltage line 132L, 132R connected to 1R is provided, and is interposed between the first high voltage line 132L, 132R,
A second shuttle valve 140 that compares the pressures of these first high pressure lines 132L and 132R and selects either one of the high pressure side selection circuits 13L or 13R, and the second shuttle valve 14
A second high voltage selection circuit 14 is provided, which includes a second high voltage line 141 connected to
The high pressure line 141 is connected to each drive actuator 10L.
, 10R are connected to input circuits 11a, 11a communicating with the head chambers 10a, 10a and input circuits 11b, 11b communicating with the rod chambers 10b, 10b.

[0010] Furthermore, the control valve devices 12L and 12R include:
The spools 12a, 12a operated by the capacity control command signal (external command pressure), and the spools 12a, 12a.
The spools 12a, 1 are provided with pressing springs 12b, 12b that oppose the movement of the spools 12a, 12b against the pressing springs 12b, 12b.
2a, the second high voltage selection circuit 1
4 is communicated with the head chambers 10a, 10a of the drive actuators 10L, 10R, and the head chambers 10a, 1
The drive actuators 10L, 10R are moved forward based on the area difference between the pressure receiving surfaces of the rod chambers 10a and 10b, 10b.

Further, each of the hydraulic pumps 2L and 2R can control its discharge amount within a range of, for example, 0 to 75 cc/rev, and each of the hydraulic motors 3L and 3R has a
The inflow amount can be controlled in the range of 110 to 50 cc/rev, and when the discharge amount of each of the hydraulic pumps 2L and 2R is within the capacity control range of 0 cc/rev to a maximum of 75 cc/rev, each of the control valve devices 12L , 12
R is set not to operate, the displacement control elements 9L and 9R of the hydraulic motors 3L and 3R are set to the maximum inclination angle, and the rotational speed of each of the hydraulic motors 3L and 3R is made to correspond to the discharge amount of each hydraulic pump 2L and 2R. Yes, each hydraulic pump 2L
, 2R reaches the maximum discharge amount (75 cc/rev), each spool 12a, 12a is operated by a predetermined amount against the pressure springs 12b, 12b by the external command pressure, and the second
The actuator 10 is driven by the pressure of the high voltage selection circuit 14.
L and 10R are advanced in response to external command pressure, the amount of tilting of the capacity control elements 9L and 9R is reduced, and the inflow amount of each hydraulic motor 3L and 3R is changed from the maximum of 110cc/rev to the minimum of 50cc/rev. Each hydraulic motor 3L
, 3R are increased, and the traveling devices 7L and 7R are rotated at high speed.

In FIG. 1, 15 is the hydraulic pump 2L,
A charge pump installed in parallel with 2R, and a manual throttle switching valve 8L in the discharge line 16 of this charge pump 15.
and 8R are provided, and the tilting direction and tilting amount of the capacity control elements 1L and 1R are controlled by operating the throttle switching valves 8L and 8R. Further, 17L and 17R are bypass lines provided on the pump side of the first high pressure selection circuits 13L and 13R in the first and second main lines 4L, 4R, 5L, and 5R, and 18 to 21 are bypass lines 17L and 17R, respectively. First and second check valves provided in the discharge line 1 between the check valves 18 and 19 and between the check valves 20 and 21 in the bypass lines 17L and 17R.
6 are connected. Further, 22 is a relief valve provided in the discharge line 16, and 23L and 23R are used to control the tilting amount of the capacity control elements 9L and 9R in the control valve device 12L.
, 12R.

The present invention is constructed as described above, and the engine E drives each hydraulic pump 2L, 2R, the first main line 4L, 4R of each hydraulic transmission device 6L, 6R is set to high pressure, and each second main line 4L, 4R is set to high pressure. By setting the lines 5L, 5R to low pressure, each hydraulic motor 3L, 3R is driven to rotate in the normal direction, and the left and right traveling devices 7L, 7R are operated forward. Also, at this time, connection lines 130L, 13 are connected to the first main lines 4L, 4R and the second main lines 5L, 5R.
First shuttle valves 131L, 131 communicating via 0R
R moves in the direction of the arrow in FIGS. 1 and 2, and each first main line 4L, 4R communicates with the first high voltage line 132L, 132R. In this case, when the pressure of the first high pressure line 132L is higher than the pressure of the second high pressure line 132R, the second shuttle valve 140 operates in the direction of the arrow in FIGS. 1 and 2, and the first high pressure line 132L is selected. This first high pressure line 132
The pressure of L is transmitted from the second high pressure line 141 to the input circuit 11b.
, 11b, it acts on the rod chambers 10b, 10b of each drive actuator 10L, 10R. In this system, when the spools 12a, 12a of each control valve device 12L, 12R are operated against the pressure springs 12b, 12b by external command pressure, the second shuttle valve 140 of the second high pressure selection circuit 14 operates. The pressure of the selected first high pressure line 132L is transferred to the input circuit 11 via each control valve device 12L, 12R.
a, 11a act on the head chambers 10a, 10a of each drive actuator 10L, 10R, and this head chamber 10a
, 10a and the rod chambers 10b, 10b cause the drive actuators 10L, 10R to move forward, the amount of tilting of the capacity control elements 9L, 9R becomes smaller, and each hydraulic motor 3L, 3R is The left and right traveling devices 7L and 7R can be controlled at a high speed according to the command by the command pressure, and can change the speed of the left and right traveling devices 7L and 7R. In this case, the amount of tilting of the capacity control elements 9L, 9R is fed back to each of the control valve devices 12L, 12R via the feedback rods 23L, 23R, and these control valve devices 12L, 12R are controlled according to a command from an external command pressure. It can be operated accurately and the tilting speed of the capacity control elements 9L and 9R can be controlled.

As described above, each hydraulic transmission device 6L, 6R
The first and second main lines 4L, 4R, 5L,
The main line with the highest pressure among the 5R is selected, and each drive actuator 10L, 10R is advanced by the self-pressure of one of the selected main lines,
Since the displacement control elements 9L and 9R are tilted and controlled, when the displacement control command signal operates the control valve devices 12L and 12R to change the speed of the travel devices 7L and 7R, the left and right travel devices 7L and 7R may shift due to irregularities in the road surface, etc. When a difference occurs in the pressure in the closed circuit between the hydraulic transmission devices 6L and 6R due to a difference in the load between the two sides, for example, the pressure in the closed circuit of the hydraulic transmission device 6L is different from that in the closed circuit of the hydraulic transmission device 6R. Even if the internal pressure becomes higher than the internal pressure, the responsiveness of each of the displacement control elements 9L and 9R can be made the same, and a difference in the rotational speed of each hydraulic motor 3L and 3R can be prevented, so that the vehicle can move left and right. You can avoid being dumped.

Furthermore, the capacity control elements 1L and 1R of each of the hydraulic pumps 2L and 2R are reversed in the opposite direction with respect to the neutral position, and the second main line 5L of each hydraulic transmission device 6L and 6R is
, 5R are set to high pressure, and the first main lines 4L, 4R are set to low pressure, the respective hydraulic motors 3L, 3R are driven in reverse, and the left and right traveling devices 7L, 7R are operated backward. In this case as well, the main line with the highest pressure among the first and second main lines 4L, 4R, 5L, 5R in each hydraulic transmission device 6L, 6R is the first High voltage selection circuit 13L, 13
R and the second high voltage selection circuit 14, each drive actuator 10L, 10R is advanced by the self-pressure of one of the main lines selected in this way, and the displacement control elements 9L, 9R can be tilted and controlled. When operating the control valve devices 12L, 12R in response to a command signal to change the speed of the traveling devices 7L, 7R, a difference in load on the left and right traveling devices 7L, 7R occurs due to unevenness of the road surface, etc., and each hydraulic transmission device 6L , 6R, the responsiveness of each capacity control element 9L, 9R can be made the same, and a difference in the rotational speed of each hydraulic motor 3L, 3R can be prevented. , it is possible to prevent the vehicle from swinging from side to side.

In the embodiment described above, the capacity control elements 1L and 1R of the variable hydraulic pumps 2L and 2R may be of the swash plate type or of the slant axis type, and the variable hydraulic motors 3L, The capacity control elements 9L and 9R of 3R may be of the slanted shaft type or may be of the swash plate type. Moreover, the control valve device 1
2L and 12R have a structure that operates with external command pressure, and
The structure may be such that it operates using an external command voltage.

[0017]

As described above, according to the present invention, the first and second mains in a pair of hydraulic transmission devices 6L, 6R in which variable hydraulic pumps 2L, 2R and variable hydraulic motors 3L, 3R are connected in a closed circuit. The main line with the highest pressure among the lines 4L, 4R, 5L, and 5R is selected by the first high voltage selection circuits 13L, 13R and the second high voltage selection circuit 14, and the self-pressure of one of the selected main lines is By operating the drive actuators 10L and 10R, the capacity control elements 9L and 9R of the respective hydraulic motors 3L and 3R can be controlled. Even if a difference occurs in the pressure of the closed circuit in each hydraulic transmission device 6L, 6R due to a difference in the load, the responsiveness of each displacement control element 9L, 9R can be made the same, and each hydraulic motor 3L, This prevents differences in the rotational speeds of the 3Rs, prevents the vehicle from swinging from side to side, and enables stable driving.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a travel control device of the present invention.

FIG. 2 is an enlarged schematic explanatory diagram of only the essential parts of the travel control device of the present invention.

FIG. 3 is a schematic explanatory diagram showing a conventional travel control device.

FIG. 4 is a schematic explanatory diagram showing the conventional travel control device.

[Explanation of symbols]

1L, 1R Capacity control element 2L, 2R Hydraulic pump 3L, 3R Hydraulic motor 4L, 4R First main line 5L, 5R Second main line 6L, 6R Hydraulic transmission device 7L, 7R Traveling device 9L, 9R Capacity control element 10L, 10R Drive actuator 11a, 11b
Input circuits 12L, 12R Control valve devices 13L, 13R First high pressure selection circuit

Claims (1)

[Claims] Claim 1: A pair of variable hydraulic pumps 2L, 2R having capacity control elements 1L, 1R and a pair of variable hydraulic motors 3L, 3R having capacity control elements 9L, 9R connected in a closed circuit. The hydraulic transmission devices 6L, 6R are provided, and the left and right traveling devices 7L, 7R are independently driven by the respective hydraulic motors 3L, 3R, and the capacity control elements 9L, 9R of the hydraulic motors 3L, 3R are provided with the Each hydraulic transmission device 6L
, 6R are provided with drive actuators 10L, 10R that operate using self-pressure in a closed circuit.
A traveling device for a hydraulically driven vehicle that is provided with control valve devices 12L and 12R for controlling the drive of the 0R, and a first main line 4L in a closed circuit of each of the hydraulic transmission devices 6L and 6R,
4R and the second main lines 5L, 5R, and the first main lines 4L, 4R and the second main lines 5L, 5R.
First high voltage selection circuits 13L and 13R are provided to select the high voltage side main line by comparing the pressure with R, and the high voltage side selection circuit is selected by comparing the pressures of each of the first high voltage selection circuits 13L and 13R. A second high voltage selection circuit 14 is provided, and this second high voltage selection circuit 14 is connected to the drive actuator 1.
A travel control device for a hydraulically driven vehicle, characterized in that it is connected to input circuits 11a and 11b of 0L and 10R.