JPH05221337A - Controller of travelling hydraulic circuit in hydraulic traveling vehicle - Google Patents

Abstract

PURPOSE:To carry out smooth rectilinear travelling and slewing and turn by providing throttles, the openings of which change in work positions, according to the strokes of the directional control valves, at proper places of communication paths which connects the connection circuits between control valves and pressure control valves with each other, that is, inside each directional control valve. CONSTITUTION:Communication paths 23 and 24 are provided, which connects the connection circuits 15A and 158 between right and left directional control valves 5A and 5B and right and left pressure compensating valves 11A and 11B with each other. These are connected through throttles 21A and 21B, and 22A and 22B the openings of which change according to the strokes of the spools 5PA and 5PB of the directional control valves 5A and 5B. And in case that the spools 5PA and 5PB of the right and left directional control valves 5A and 5B are operated with different strokes, the openings of the throttles 21A and 21B, and 22A and 228 are decided according to the strokes of the right and left spools 5PA and 5PB in that condition. It slews or turns by controlling the speeds of right and left travelling hydraulic motors 7A and 78 this way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a hydraulic circuit for traveling in a hydraulically traveling vehicle, and more particularly to a shovel and a roller for traveling by driving left and right rollers by a hydraulic traveling motor.
For hydraulically driven vehicles such as da, crane, and other construction machinery,
In addition to enabling straight running of the hydraulic running motors on both the left and right sides, it also enabled smooth turns or curved runs of the same.
The present invention relates to a control device for a traveling hydraulic circuit in a hydraulic traveling vehicle.

[0002]

2. Description of the Related Art A conventional hydraulic traveling motor drives excavators, loaders, cranes, which drive left and right crawlers.
For traveling in hydraulic traveling vehicles that enables straight traveling of the hydraulic traveling motors on the left and right sides of other hydraulic traveling vehicles such as construction machinery, and smooth turning or bending traveling thereof. As a control device for the hydraulic circuit, there is, for example, one disclosed in Japanese Patent Laid-Open No. 3-54077.

This is a variable displacement pump which corresponds to the straight passage control circuit device of a hydraulic traveling vehicle shown in FIG. 11 to be described later, from which the communicating passage shut-off valve 18 is removed from the communicating passage 17 (see FIG. 11). A pump circuit 3 to which 1 is connected,
The left and right hydraulic traveling motors 7A and 7B of the hydraulic traveling vehicle are connected to the return circuits 9A and 9B connected to the tank T via the respective directional switching valves 5A and 5B, and the respective directional switching is performed. Pressure compensating valves 11A and 11B are provided between the valves 5A and 5B and the homp circuit 3, respectively, and the higher load pressure of the traveling hydraulic motors 7A and 7B is set to the shuttle valve 13.
The left and right connection circuits 15 that lead to the discharge amount control device 2 of the variable displacement pump 1 via the valve and connect the directional switching valves 5A and 5B to the pressure compensation valves 11A and 11B.
A and 15B are connected to each other by a communication passage 17.

According to the straight traveling control circuit device in the hydraulic traveling vehicle, the left and right directional control valves 5A and 5B are provided with splines.
When the same amount is operated to the forward rotation position by operating the valves 5PA and 5PB by the same amount, the left and right traveling hydraulic motors 7A and 7B are forwardly rotated at the same speed and the vehicle goes straight. If there is a processing error, the flow rate to either one of the hydraulic motors 7A or 7B increases, and the other hydraulic motor 7 passes through the communication passage 17.
The pressure oil flows to the circuit B or 7A, which reduces the flow rate to one hydraulic motor 7A or 7B, so that the rotation speed decreases and the flow rate to the left and right hydraulic motors 7A and 7B decreases. As a result, the straight traveling performance of the hydraulic traveling vehicle is maintained.

However, in this device, when the hydraulic traveling vehicle is turned rightward, for example, the right traveling hydraulic motor 7 is used.
The stroke of the spool 5PB of the B direction switching valve 5B is reduced, and the flow rate of the right connection circuit 15B is set to the left connection circuit 15.
By making the flow rate much smaller than the flow rate of A and sufficiently exceeding the amount of pressure oil flowing from the left connecting circuit 15A to the right connecting circuit 15B via the communication passage 17, a flow rate difference is generated between the connecting circuits 15A and 15B. Although the left traveling hydraulic motor 7A rotates at a higher speed than the right traveling hydraulic motor 7B, the hydraulic traveling vehicle turns to the right, but at this time, the pressure of the left connecting circuit 15A is changed via the communication passage 17. Since the oil flows to the right side connection circuit 15B, there is a dislike that the operability of turning or curving is deteriorated.

Further, as shown in FIG. 11, between the pump circuit 3 to which the variable displacement pump 1 is connected and the return circuits 9A and 9B connected to the tank T, the left and right hydraulic traveling motors of the hydraulic traveling vehicle are provided. 7A, 7B to the respective directional control valves 5A,
5B, and each of the directional control valves 5A,
The pressure compensating valve 11 is provided between the 5B and the homp circuit 3, respectively.
A and 11B are provided so that the higher load pressure of each of the traveling hydraulic motors 7A and 7B is guided to the discharge amount control device 2 of the variable displacement pump 1 through the shuttle valve 13, and each of the directions described above. Switching valves 5A, 5B and pressure compensation valves 11A, 11B
And the connection circuits 15A, 15B are mutually connected by a communication passage 17, and a communication passage cutoff valve 18 with a spring is provided in the communication passage 17 to connect the left and right connection circuits 15A, 1B.
When the pressure difference of 5B becomes equal to or higher than the pressure set by the spring of the communication passage shutoff valve 18, the shutoff valve 18 causes the communication passage 1
It has already been proposed that the operation of the vehicle is cut off to improve the operability at the time of turning or curving while maintaining the good straight traveling performance of the vehicle (actual flat 3-5).
(See Japanese Patent No. 0589).

[0007]

However, in the conventional straight traveling control circuit device in the hydraulic traveling vehicle as disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-54077, the traveling hydraulic motors 7A which are flat and left and right, When the hydraulic traveling vehicle travels straight in a place where the load pressure on 7B is substantially the same, even if there is some processing error in each of the directional control valves 5A, 5B, one traveling mode is set via the communication passage 17. -Part of the pressure oil of the connection circuit 15A or 15B to the motor 7A or 7B,
Connection circuit 15B to the other traveling hydraulic motor 7B or 7A
Or, let it flow to 15A, and hydraulic drive motors 7 on both left and right sides.
Since it is possible to maintain the same rotational speed of A and 7B and to expect the straight traveling of the hydraulically traveling vehicle, in this one, the left and right direction changeover valves 5A and 5B are operated with a stroke difference to hydraulically travel. When the vehicle is turning or traveling in a curved manner, the operating stroke of the left and right directional control valve 5A or 5B is set so that the difference in flow rate between the left and right connecting circuits 15A and 15B becomes large enough to exceed the flow rate passing through the communication passage 17. -It was necessary to increase the torque, and there was the dislike that the operability during turning or curving was correspondingly reduced.

Further, in the structure shown in FIG. 11, the communication passage 17 is provided with a communication passage cutoff valve 18 which closes the communication passage 17 at a predetermined pressure, so that the communication passage 17 is closed by the cutoff valve 1.
Until it is closed by 8, while maintaining the operability in the straight traveling state of the hydraulic traveling vehicle, the operating directions of the spools 5PA, 5PB of the left and right direction change-over valves 5A, 5B are reversed or the left and right directions are changed. After the stroke difference between the spools 5PA and 5PB is increased, the pressure difference between the upper and lower sides of the spool of the communication passage shutoff valve 18 (FIG. 11) exceeds the set pressure of the spring. Although the passage 17 is closed by the switching valve 18 to independently drive the left and right hydraulic traveling motors 7A and 7B, the operability of turning or curving of the hydraulic traveling vehicle can be secured. Is allowed to flow from one connection passage 15A or 15B through the same communication passage 17 to the other connection passage 15B or 15A until the communication passage 17 is shut off by the shutoff valve 18, in other words,
In the case where the traveling direction of the hydraulic traveling vehicle is slightly changed, the flow from the one connection passage 15A or 15B through the communication passage 17 to the other connection passage 15B or 15A is still allowed. In the same manner as the one described in Japanese Patent Laid-Open No. 3-54077, the left and right directional control valves 5A and 5B are spun so that a flow rate difference is generated to the extent that the flow rate exceeds the flow rate in the communication passage 17.
It is necessary to increase the operation stroke difference between the rules 5PA and 5PB. In this state, the left and right hydraulic traveling motors 7
The left and right directional control valves 5A and 5B are provided so that a large amount of pressure oil can be supplied so that the difference in the amount of pressure oil supplied to A and 7B exceeds the amount of oil that passes through the shutoff valve 18 of the communication passage 17. There is a problem that the operating stroke of the spool 5PA5PB needs to be increased, and therefore the operability of turning or curving of the hydraulic traveling vehicle is still low.

The present invention has been made by paying attention to the problems in the prior art as described above, and includes a left and right direction changeover valve and a left and right pressure compensation valve of a hydraulic traveling vehicle traveling by the left and right traveling hydraulic motors. A throttle portion or a switching valve is provided in the communication passage that connects the respective connection circuits, and the opening degree of the throttle portion or the switching valve, and hence the degree of throttling of the communication passage by the switching valve, is set to the left and right traveling hydraulic pressures. By changing the operation of the directional control valve of the motor according to the stroke of the lever, or in the communication passage, an electromagnetic valve having a throttle portion whose opening degree changes according to the communication position and the stroke. Switch valve
The detection signal of the pressure sensor provided in the spool operation circuit of each of the directional control valves is applied to the controller, and the controller is applied.
The La-microcomputer calculates the stroke of the electromagnetic switching valve corresponding to the strokes of the left and right directional switching valves, and the output signal of the spool stroke of the electromagnetic switching valve. By controlling the
An object of the present invention is to provide a control device for a traveling hydraulic circuit in a hydraulic traveling vehicle that can solve the above problems.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides left and right traveling between a pump circuit to which a variable displacement pump is connected and a return circuit to which a tank is connected. The hydraulic motors are connected through the respective directional control valves, and pressure compensation valves are provided between the respective directional control valves and the homp circuit, so that the traveling hydraulic pressure control valves are provided.
While the load pressure of the higher one is guided to the discharge amount control device of the variable displacement pump via a shuttle valve, the connection circuits of the directional switching valves and the pressure compensating valves are mutually connected by a communication passage, and The directional switching valves are provided at appropriate places in the communication passage, and the directional control valves are closed at their neutral positions, and at their respective operating positions, throttle portions whose opening varies according to the stroke of the directional control valve are interposed. Further, the connection circuits of the directional switching valves and the pressure compensating valve are connected to each other by a communication passage, and the neutral closing portion and the opening degree of the directional control valve are connected to each other in the communication passage. A switching valve with a throttling portion that changes is provided, and a spool of the switching valve with a throttling portion is interlocked with a spool of the directional switching valve by an appropriate interlocking device, or a spool of the switching valve with a throttling portion.
Pressure oil in the pilot circuit for operating the operation lever of the directional control valve is applied to the valve to switch the valve, and the opening degree is changed in accordance with the stroke difference between the neutral communication portion and each directional control valve in the communication passage. Is provided with an electromagnetic switching valve having a throttle portion, and a pressure sensor is provided in the operation circuit of each of the directional switching valves, a detection signal from the pressure sensor is applied to the controller, and a micro computer of the controller is used. , Calculating a drive signal of a spool stroke of the electromagnetic switching valve corresponding to a detection signal by the pressure sensor, and outputting the calculated drive signal of the spool stroke of the electromagnetic switching valve of the electromagnetic switching valve. It is a control device for a hydraulic circuit for traveling in a hydraulic traveling vehicle, which is applied to a spool drive unit to adjust the spool stroke to secure turning or curving traveling of the hydraulic traveling vehicle.

(Operation of the Invention) Since the present invention has the above-mentioned structure, the operation levers for the left and right directional control valves are
If the steering wheel is operated equiangularly from its neutral position in the forward (left) or reverse (right) direction, the left and right spools move an equal amount, the left and right traveling hydraulic motors rotate at a constant speed, and the hydraulic traveling vehicle travels straight. However, at this time, if for some reason there is a flow rate difference between the left and right connecting circuits that connect the left and right directional control valves and the pressure compensating valve, it is provided in the communication passage that connects the two connecting circuits. A part of the pressure oil flows from one side of the connection circuit to the other side via the throttle section or the throttle section of the switching valve, so that the flow rate of the pressure oil in the left and right connection circuits becomes equal and The traveling hydraulic motors 7A and 7B on both sides rotate at the same speed to ensure the straight traveling of the traveling vehicle, and the hydraulic traveling vehicle turns or bends depending on the operation angles of the left and right directional control valves. In the case of, the opening degree of the throttle portion or the throttle portion of the switching valve interposed in the communication passage, The operating angle of the operating lever of the left and right directional control valves, and the change in response to the operating lever when applied to the pressure oil in the pilot passage by the operation of the operating lever. The flow rate of the pressure oil is limited, and an electromagnetic switching valve having a neutral communication portion and a throttle portion whose opening changes according to the stroke is provided in the communication passage, and a spool operation circuit of each directional switching valve is provided. The detection signal of the provided pressure sensor is applied to the controller, and the directional switching valve is turned on by the microcomputer of the controller.
Calculating the spool stroke of the electromagnetic switching valve corresponding to the stroke of the electromagnetic switching valve, and applying the calculated output signal of the spool stroke to the spool driving portion of the electromagnetic switching valve. Thus, the spool of the directional control valve is moved to change the throttle opening, the flow rate of the pressure oil flowing through the communication passage is limited, and the left and right traveling hydraulic pressures are controlled via the left and right connection circuits and the directional control valve. The difference in the flow rate of the pressure oil supplied to the motor is maintained, and the desired turning or curving traveling operability of the hydraulic traveling vehicle is ensured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a control device for a hydraulic circuit for traveling in a hydraulically traveling vehicle according to the present invention will be described below with reference to FIGS.
This will be described with reference to 0. In addition, the same name and the same reference numeral are used for the portions common to the control device for the traveling hydraulic circuit in the conventional hydraulic traveling vehicle shown in FIG.

(First Embodiment) FIG. 1 shows a control circuit diagram of a first embodiment of the present invention, and FIG. 2 is a schematic longitudinal sectional view of a directional control valve of the first embodiment. In FIGS. 1 and 2, 1
Is a variable displacement pump, 2 is a discharge amount control device for the variable displacement pump 1, 3 is a pump circuit, 5A and 5B are left and right directional control valves, 5PA and 5PB are left and right directional control valves 5A and 5B, and 7A. , 7B are left and right traveling hydraulic motors, 9A, 9
B is a left and right return circuit, 11A and 11B are left and right pressure compensating valves, 12 is a pilot passage connecting the left and right pressure compensating valves 11A and 11B via a shuttle valve 13, 15A and 1A.
Reference numeral 5B is a left and right connection circuit that connects the left and right direction switching valves 5A and 5B and the left and right pressure compensation valves 11A and 11B, respectively. In the above configuration, the left and right direction switching valves 5A and 5B are provided with throttle portions 21A, 21B, 22A, 22B, which will be described later, at the neutral closed portion and the forward or backward (stroke) position, and the throttle portions are the same. 21A, 21B, 22A, 22B
12 is substantially the same as the straight traveling control circuit device in the conventional hydraulic traveling vehicle shown in FIG.

However, in the first embodiment, the left and right spools 5PA and 5PB of the left and right direction switching valves 5A and 5B are
Throttle portion 21A, 2 in the neutral closed portion and the forward or backward position
1B and 22A, 22B, and the narrowed portions 21A, 21B and 22A, 22B are formed on the left and right spools 5PA, 5PB so that their axial cross sections are wedge-shaped. -Le 5PA, 5PB strobe-
The diaphragm parts 21A, 21B and 22A, 22
It is formed so that the opening of B changes. Although only the throttle portions 21A and 21A of the left direction switching valve 5A are shown in FIG. 2, the throttle portion 2 of the spool 5PB of the right direction switching valve 5B is shown.
2A and 22B are also formed in a wedge shape having the same shape and size.
Reference numerals 23 and 24 denote throttle portions 21A and 21B of the left spool 5PA of the left direction switching valve 5A and the right spool 5 of the right direction switching valve 5B.
A communication passage 23 that connects the throttle portions 22A and 22B of the PB,
24.

(Operation of First Embodiment) Spools 5PA, 5PB of the left and right directional control valves 5A, 5B by the operation lever.
Is moved from the neutral position in FIG. 1 to the right side by the same stroke, the pressure oil of the variable displacement pump 1 is transferred to the pump circuit 3,
Left and right pressure compensation valves 11A and 11B, left and right connection circuit 15
The left and right traveling hydraulic motors 7A, 7B are normally rotated through the A, 15B, the left and right direction switching valves 5A, 5B, etc., so that the hydraulic traveling vehicle travels in a straight forward direction. In this state, it is assumed that the directional control valves 5, 5 have some processing errors, for example, the dimensions of the spools 5PA, 5PB and the housing lands of the directional control valves 5A, 5B, and the strokes of the spools 5PA, 5PB. −
Further, if the spring forces of the left and right pressure compensating valves 11A and 11B are varied to some extent, the flow rate to one traveling hydraulic motor 7A (or 7B) is changed to the other traveling hydraulic motor 7B. (Or 7A), a part of the pressure oil flows to the connection circuit 15B of the other hydraulic motor 7B (or 7A) via the communication passage 23 or 24, so that one hydraulic motor The flow rate to 7A (or 7B) is reduced and the number of rotations is reduced, and as a result, both traveling hydraulic motors 7A, 7B
The same flow rate to and the same pressure ensure the straight running condition. This point is almost the same as the conventional example shown in FIG.

However, in the first embodiment, the communication passage 2 for connecting the left and right connection circuits 15A, 15B of the left and right direction switching valves 5A, 5B and the left and right pressure compensation valves 11A, 11B.
3, 24 are spools 5 of the left and right directional control valves 5A, 5B.
The cross sections formed on the PAs and 5PBs have a wedge shape and are connected through the throttles 21A, 21B, 22A and 22B whose opening changes according to the stroke of the spools 5PA and 5PB. Spool 5P of switching valve 5A, 5B
When A and 5PB are stroked differently, the apertures of the diaphragm portions 21A, 21B, 22A and 22B are adjusted according to the strokes of the left and right spools 5PA and 5PB in that state.

That is, the left and right direction changeover valves 5A for turning or turning the hydraulically traveling vehicle in a required direction,
5B spool 5PA, 5PB different from each other
When moved, a difference in the flow rate of the pressure oil flowing through the left and right connecting circuits 15A and 15B occurs, and the left connecting circuit 1 that flows a large amount thereof.
A part of the pressure oil of 5A tries to flow to the right side connection circuit 15B on the small amount side through the communication passages 23 and 24. At that time,
The openings of the throttle portions 21A, 21B, 22A, 22B are changed and throttled according to the strokes of the spools 5PA, 5PB of the directional control valves 5A, 5B, so that the communication passages 23, 24 are closed. The flow rate of pressure oil through it is correspondingly limited, so that the speed of the left traveling hydraulic motor 7A is changed to the right traveling hydraulic motor.
The vehicle travels faster or later than the motor 7B and makes the desired turning or curving traveling of the hydraulic traveling vehicle.

(Second Embodiment) FIG. 3 is a control circuit diagram of a second embodiment of the control device for the traveling hydraulic circuit in the hydraulic traveling vehicle according to the present invention. In addition, the first shown in FIGS.
The same names and reference numerals are used for the portions common to the embodiment and the conventional example shown in FIG. In FIG. 3, 1 is a variable displacement pump, 2 is a discharge amount control device of the variable displacement pump 1,
3 is a pump circuit, 5A and 5B are left and right direction switching valves, 5P
A and 5PB are spools of the left and right directional control valves 5A and 5B,
7A and 7B are left and right traveling hydraulic motors, 9A and 9B are left and right return circuits, 11A and 11B are left and right pressure compensation valves, and 12
The left and right pressure compensation valves 11A and 11B, and the shuttle valve 13
Pilot passages, 15A, 15B, which are connected via the left and right direction switching valves 5A, 5B and left and right pressure compensation valves 11A,
11B is a left and right connection circuit for connecting with 11B respectively. The above-described configuration is substantially the same as the straight traveling control circuit device in the conventional hydraulic traveling vehicle shown in FIG. 12, and the left / right direction switching of the first embodiment shown in FIGS. 1 and 2 is performed. From the valves 5A and 5B, the stop part at the neutral position and the throttle parts 21A, 21B, 22A, 2 provided at the stroke position.
2B and 2 and the communication passage 2 related to these
The third embodiment is the same as the first embodiment except that points 3 and 24 are omitted.

However, in the second embodiment, the connection circuits 15A and 15B for connecting the left and right direction switching valves 5A and 5B and the left and right pressure compensation valves 11A and 11B, respectively, are connected to the communication passage 1
In connecting with 7, the neutral cutoff portion 31A is provided in the same communication passage 17.
A, 31BA and diaphragm 3 that changes according to stroke
Left and right switching valves 31A and 31B including 1AB, 31AC, 31BB and 31BC are provided, and the left and right switching valves 31A and 31B are connected by communication passages 23 and 24, and
The spools of the left and right switching valves 31A and 31B are connected to the operating levers of the spools 5PA and 5PB of the left and right direction switching valves 5A and 5B by connecting members 33A and 33B, respectively.

(Operation of the Second Embodiment) The left and right running hydraulic pressures are set to the forward and reverse positions by operating the spools 5PA and 5PB of the left and right directional control valves 5A and 5B of the second embodiment in the same stroke. When the motors 7A and 7B are rotated, the hydraulic traveling vehicle travels straight, and even if there is some processing error in the left and right directional control valves 5A and 5B, the communication passage 17 connecting the left and right connecting circuits 15A and 15B is connected. Through one side to the other through
The point that the straight traveling is ensured in a balanced manner is that the spool 5 of the left and right direction switching valves 5A and 5B is the same as in the first embodiment.
According to the movement of PA and 5PB, the throttle portions 31AB and 31 provided in the switching valves 31A and 31B interposed in the communication passage 17 are provided.
The throttle openings of AC, 31BA and 31BB are the same as those of the spool 5
It is adjusted in accordance with the stroke of PA, 5PB, the amount of pressure oil passing through the communication passage 17 is limited, and the turning or bending traveling property of the oil hydraulic traveling vehicle is secured. Similar to the example.

However, in the second embodiment, the left and right connection circuits 15A and 15B for connecting the left and right direction switching valves 5A and 5B and the left and right pressure compensation valves 11A and 11B, respectively, are
Left and right switching valves 31A, 31 provided in the connecting passage 17 to be connected
B is the spool 5PA of the left and right direction switching valves 5A, 5B,
Since it is connected to the 5PB by the left and right connecting members 33A and 33B, respectively, the left and right switching valves 31A and 31B are connected to each other.
Left and right direction change valves 5A, 5B spools 5PA, 5
While moving according to the stroke of PB, the opening degree of the throttle portion changes corresponding to the stroke of the spool, and the amount of pressure oil flowing through the communication passages 23, 24 changes.
31AC, 31BA, 31BB is restricted according to the opening degree, and as a result, the stroke difference of the spools 5PA, 5PB of the left and right directional control valves 5A, 5B is imparted, and the turning or curving of this hydraulic traveling vehicle is performed. During traveling, the flow rate of the pressure oil from one connection circuit 15A or 15B to the other connection circuit 15B or 15A is limited, and operability during desired turning or curving is ensured.

(Third Embodiment) FIG. 4 is a control circuit diagram of a third embodiment of the control device for the traveling hydraulic circuit in the hydraulic traveling vehicle according to the present invention. Note that the same names and reference numerals are used for parts common to the second embodiment shown in FIG. In FIG. 4, 1 is a variable displacement pump, 2 is a discharge amount control device for the variable displacement pump 1, 3 is a pump circuit, 5A and 5B are left and right direction switching valves, 5PA and 5PB are left and right direction switching valves.
A and 5B spools, 7A and 7B are left and right traveling hydraulic motors.
, 9A and 9B are left and right return circuits, 11A and 11B are left and right pressure compensation valves, and 12 is left and right pressure compensation valves 11A and 11
B is a pilot passage connecting the shuttle valve 13 to each other, and 15A and 15B are left and right connection circuits that respectively connect the left and right directional switching valves 5A and 5B and the left and right pressure compensation valves 11A and 11B. This is almost the same as the second embodiment shown in FIG.

Reference numeral 40 is a switching valve. The switching valve 40 includes left and right direction switching valves 5A and 5B and left and right pressure compensation valves 11A and 11A.
A neutral communication portion 40A, which is provided in a communication passage 17 that connects the left and right connection circuits 15A and 15B that connect B with each other, connects the switching passage 40 with the neutral communication portion 40A, and the switching valve 40. There are variable throttle parts 40B and 40C whose opening degree changes in accordance with the stroke of the rule. 43A, 43B
Is a left / right operation lever for operating the left / right directional control valves 5A, 5B, 43AA, 43BB is a left / right operation lever 43A,
Left and right pilot valves operated by 43B, 44A,
44B and 45A, 45B are left and right operation levers 43A,
The direction of 43B to the neutral, left side or right side, and the operation amount are set to the spools 5PA, 5PA of the left and right direction switching valves 5A, 5B.
This is a pilot passage for transmitting the PB and the spool of the switching valve 40 at the same time.

(Operation of Third Embodiment) Left and right operation levers-4
When 3A and 43B are operated to the left and right, an operation pressure is generated based on the operation direction and the operation angle, and the left and right pilot valves 4
3AA, 43BB, pilot passages 44A, 44B, 4
Left and right direction switching valves 5A, 5B via 5A, 45B, etc.
5PA and 5PB of the switching valve 40 and the spool of the switching valve 40 provided in the communication passage 17 are simultaneously transmitted to the spools of the switching valve 40 in the operating direction of the operating levers 43A and 43B. And a value corresponding to the difference in the operation angle moves upward or downward. Therefore, the throttle portion 40B or 40 of the switching valve 40
The opening degree of C changes (is throttled) accordingly, and the throttle oil flowing in the communication passage 17 is given a corresponding throttle resistance.

Therefore, the left and right operation levers 43A, 4
When the hydraulically traveling vehicle is turned or travels in a curved line by operating the 3B at different angles, the left and right directional control valves 5A, 5B.
Spools 5PA and 5PB are different strokes, and the left and right connecting circuits 15A and 15B and the left and right hydraulic traveling modes are
Different amounts of pressure oil flow to the rotors 7A and 7B. At this time,
Based on the different operation angles of the left and right operation levers 43A and 43B, one of the connection circuits 15A or 15 having a large flow rate.
A part of the pressure oil of B flows to the other connecting circuit 15B or 15A through the communication passage 17, but the switching valve 40 provided in this communication passage 17 is responsive to the stroke of the spool. Due to the flow resistance corresponding to the changing opening of the throttle unit 40B or 40C, the flow amount is restricted and the required operability is ensured during the turning or curving operation of the hydraulic traveling vehicle.

The openings of the throttles 40B and 40C of the switching valve 40 change according to the strokes of the spools 5PA and 5PB of the left and right direction switching valves 5A and 5B, and the operation lever is changed. When -43A and 43B are displaced in the same direction by the same amount, the pilot passage 44A (or 44B),
Since the pilot passages 45A (or 45B) have the same pressure (when the pilot passages 44A and 45A are under pressure, the pilot passages 44B and 45B both have substantially the same tank T pressure), the switching valve 40 The spool also selects its neutral position, and when the spool of the switching valve 40 is in the neutral position, the communication passage 17 communicates with the spool, and the left and right direction switching valves 5A, 5B, etc. have some working error. Even when there are such problems, the straight traveling performance of the hydraulic traveling vehicle is ensured.

(Modification of Third Embodiment) FIG. 5 shows a switching valve 46.
In the explanatory view of FIG. 4, this switching valve 46 connects the left and right direction switching valves 5A, 5B and the left and right pressure compensation valves 11A, 11B in the third embodiment shown in FIG.
In the switching valve 40 provided in the communication passage 17 between 5A and 15B, the switching valve 40 is fully closed at the maximum switching position shown in FIG.

Therefore, the left and right directional control valves 5A, 5B
When the hydraulic traveling vehicle is turned or curved by operating the spools 5PA and 5PB of No. 1, when the difference between the operation amounts or the operation directions of the left and right operation levers 43A and 43B becomes maximum, The spool of the switching valve 46 moves downward or upward (FIG. 5) from the neutral communication position 46A against the spring force thereof to the closed position 46B or 46C, and the communication passage 17 forms the communication passage 17. To completely block and shut off. Therefore, when the hydraulic traveling vehicle is turning or traveling in a curved manner, the left and right connection circuits 1 via the communication passage 17 are provided.
The flow of pressure oil from one of the 5A and 15B to the other is completely blocked, and the left and right operation levers 43A and 4B in this state are completely blocked.
The operability of 3B is further improved as compared with the third embodiment.

(Other Modification of Third Embodiment) FIG. 6 is an explanatory view showing a changeover valve 48 of another modification of the changeover valve 40 of the third embodiment shown in FIG. 4, and this changeover valve 48. Is the switching provided in the communication passage 17 between the left and right connecting circuits 15A and 15B for connecting the left and right directional switching valves 5A, 5B and the left and right pressure compensating valves 11A, 11B in the third embodiment of FIG. Valve 4
It is used instead of 0. This switching valve 48 corresponds to the switching valve 46 of the modified example of the third embodiment shown in FIG. 5 in which the relationship between the neutral position 46A closing portion and the upper and lower positions 46B and 46C communicating portions is reversed, The neutral position 48A is the closed portion, and the maximum moving position 4 above and below (FIG. 6)
8B and 48C are configured as open parts.

Therefore, the left and right directional control valves 5A, 5B
When the hydraulic traveling vehicle is turned or curved by operating the spools 5PA and 5PB of No. 1, when the difference between the operation amounts or the operation directions of the left and right operation levers 43A and 43B becomes maximum, The spool of the switching valve 46 moves downward or upward (FIG. 6) from its neutral closed position 48A against its spring force to an open (communication) position 48B or 48C, and this communication passage 17 is the same. The pilot passages 45A, 45B so that they are completely opened by the switching valve 48.
However, this switching valve 48 is in reverse relation to the switching valve 46 of FIG.
Connected to the spool. It should be noted that the switching valve 48 moves from the neutral position 48A to the upper position 48B or the lower position 48C.
In the intermediate position where the fully open passages 48B and 48C are moved to
Since the throttle valve is substantially throttled according to the stroke of the spool of the switching valve 48, if the switching valve 48 is provided, the communication passage 1 can be provided when the hydraulic traveling vehicle turns or bends.
The flow of pressure oil from one of the left and right connecting circuits 15A and 15B to the other via 7 is completely blocked, and the operability of the left and right operation levers 43A and 43B in this state is substantially the same as that of the third embodiment. We can expect similar effects.

(Fourth Embodiment) FIG. 7 is a circuit diagram of a control device for a hydraulic circuit for traveling in a hydraulic traveling vehicle according to a fourth embodiment of the present invention, and FIG. 8 is a left / right operation in the fourth embodiment of the present invention. The hydraulic pressure in the pilot passages 51A, 51B, 52A, 52B based on the operation of the levers 43A, 43B is detected by the pressure sensors 53A, 53B, 54A, 54B,
By applying the detection signal to the controller 57, the microcomputer 57A of the controller 57 is applied.
6 is a flow chart of the operation of the arithmetic circuit of the stroke which requires the spool of the electromagnetic switching valve 50 in the communication passage 17. Note that the same names and reference numerals are used for the parts common to those of the third embodiment shown in FIG.

In FIG. 7, 1 is a variable displacement pump, 2 is a discharge amount control device for the variable displacement pump 1, 3 is a pump circuit,
Reference numerals 5A and 5B are left and right directional control valves, 5PA and 5PB are left and right directional control valves 5A and 5B, 7A and 7B are left and right traveling hydraulic motors, and 9A and 9B are left and right return circuits.
A and 11B are left and right pressure compensating valves, 12 is a communication passage that connects the left and right pressure compensating valves 11A and 11B via the shuttle valve 13, and 15A and 15B are left and right direction switching valves 5A and 5B.
And the left and right pressure compensating valves 11A and 11B, respectively, the left and right connection circuits, 43A and 43B are left and right operation levers, 43AA and 43BB are left and right pilot valves, and these structures are the third as shown in FIG. It is similar to the embodiment.

Reference numeral 50 is an electromagnetic switching valve provided in the communication passage 17,
The electromagnetic switching valve 50 includes a neutral communication portion 50A and a variable throttle portion 50B whose opening changes according to the movement of the spool. 51A, 51B, 52A, 52B are pilot passages, and the pilot passages 51A, 51B, 52A,
The reference numeral 52B designates the left and right operation levers 43A, 43B for neutral, left or right operation, and the left and right pilot valves 43AA, 43A.
It is transmitted to the spools 5PA and 5PB of the left and right directional control valves 5A and 5B via 43BB.

53A, 53B, 54A and 54B are pressure sensors provided in the pilot passages 51A, 51B, 52A and 52B, and 55A, 55B, 56A and 56B are pilot passages 51A, which are detected by the pressure sensors 53A, 53B, 54A and 54B. A transmission line for transmitting the pressure detection values P ₁ , P ₂ , P ₃ , P ₄ of 51B, 52A, 52B to the controller 57 as detection value signals, 57A is a controller 57.
This micro computer 57A is a pilot passage 51A, 51B, 52 transmitted from pressure sensors 53A, 53B, 54A, 54B.
A spool stroke of the electromagnetic switching valve 50 in response to the detected value signals P ₁ , P ₂ , P ₃ , P ₄ of the pressure values of A and 52B is calculated. Reference numeral 58 transmits the stroke information of the spool of the electromagnetic switching valve 50 calculated by the microcomputer 57A of the controller 57 to the drive unit above the spool of the electromagnetic switching valve 50 (FIG. 7). Signal line.

(Operation of the Fourth Embodiment) Left and right operation levers-4
The left and right pilot valves 43AA and 43BB are operated according to the operation direction and the operation amount of the 3A and 43B, and the operation information in response to the operation is pilot passages 51A, 51B and 52.
It is transmitted to the spools 5PA and 5PB of the left and right direction switching valves 5A and 5B through A and 52B, and the spool 5P is transmitted.
It is the same as the third embodiment in that A and 5PB are moved in the required directions by the required strokes.

However, in the fourth embodiment, the pilot passages 51A, 51B, 52A and 52B are added to the above operation.
Oil pressure of the pressure sensor 53A, 53B, 54A, 54B
The pressure signals of the detected values P ₁ , P ₂ , P ₃ , P ₄ are transmitted to the controller 57 via the signal lines 55A, 55B, 56A, 56B, and are detected by the controller 57.
According to a required conditional expression or the like regarding turning or curving traveling operability of the hydraulic traveling vehicle stored in advance in the storage unit of
The operation lever is controlled by the microcomputer 57A.
The stroke of the electromagnetic switching valve 50 corresponding to the operation amount and operation direction of 43A and 43B is calculated, and the calculated stroke signal of the same spool is transmitted to the transmission line 5
8 is transmitted to the spool drive unit (upper side in FIG. 6) of the electromagnetic switching valve 50, and the spool of the electromagnetic switching valve 50 is moved downward against its spring (FIG. 6) to the required stroke. Move it.

Due to the movement of the spool of the electromagnetic switching valve 50, the opening of the throttle portion 50B is changed to the direction switching valves 5A and 5A.
It is adjusted according to the operation direction and the operation amount difference of the B spools 5PA, 5PB, the flow amount of the pressure oil in the communication passage 17 is correspondingly limited, and one of the left and right connecting circuits 15A or 15B is connected to the other. A resistance corresponding to the opening degree of the throttle portion 50B of the electromagnetic switching valve 50 is added to the pressure oil flowing to the connection circuit 15B or 15A, so that the operability during turning or curving of the hydraulic traveling vehicle is reduced. It is improved as in the third embodiment.

The electromagnetic switching valve 50 has a neutral position 50.
A is formed as a neutral communication passage, and at the neutral position 50A, the left and right connecting circuits 15A and 15B are connected to each other by a communication passage 17
And the neutral communication passage 50A of the electromagnetic switching valve 50, and resistance is not added to the pressure oil flowing in the communication passage 17 in this state, so that the straight traveling performance of the hydraulic traveling vehicle is The same as in the third embodiment is secured.

Next, the pilot passages 51A, 51B, 52 which change based on the operation of the operation levers 43A, 43B.
A, 52B hydraulic pressure sensors 53A, 53B, 54
The detection values P ₁ , P ₂ , P ₃ , P ₄ detected by A and 54B are used as detection value signals on the signal lines 55A, 55B, 56A and 56B.
To the controller 57, and the microcomputer 57 causes the operating lever to be operated in accordance with a required conditional expression or the like regarding turning or curving traveling operability of the hydraulic traveling vehicle stored in advance in the storage unit. The stroke calculation procedure of the spool of the electromagnetic switching valve 50 corresponding to the operation amount and operation direction of −43A and 43B will be described with reference to the flowchart of FIG.

(A) Each pressure sensor 53A, 53B, 5
Pilot passages 51A, 5 detected by 4A, 54B
The pressures of 1B, 52A and 52B are detected by the detected value signal P ₁ ,
As P _2, P _3, P ₄ control - enter to La 57A.
The detected value signals P ₁ , P ₂ , P ₃ , P ₄ are approximately proportional to the operation amounts of the left and right operation levers 43A, 43B, and
Left and right direction change valves 5A, 5B spools 5PA, 5PB
It is almost proportional to the stroke. The left and right operation levers
Operate 43A and 43B at the same angle to the left and right to move the left and right driving modes.
When the switches 7A and 7B are controlled to operate in the same direction (forward or backward), P ₃ rises with the detection value signal P ₁ or P ₄ rises with P ₂ .

(B) Whether any of the detected value signals P ₁ , P ₂ , P ₃ , P ₄ is larger than P ₀ (≈0), that is,
It is determined whether the running motor 7A or 7B is under operation control. When any of the detection value signals P ₁ , P ₂ , P ₃ , and P ₄ is larger than P ₀ (≈0), it is determined that the vehicle is running,
Go to (C).

(C) Whether the detected value signals P ₁ and P ₃ are both greater than P ₀ , that is, the left and right running motors 7A and 7
It is determined whether or not B is controlled so that it is actuated in the same direction, for example, the forward direction, and if it is the same direction, go to (D).

(D) Whether the detection value signal P ₁ = P ₃ , that is, whether or not the operating speeds of the left and right traveling motors 7A and 7B are controlled in the same manner, that is, whether or not the vehicle is running straight. , If it is straight ahead, go to (E).

(E) The electromagnetic switching valve 50 is fully opened to keep the left and right traveling motors 7A and 7B at the same rotational speed to maintain straightness.

(F) Whether both the detection value signals P ₂ and P ₄ are larger than P ₀ . That is, the left and right running motors 7A, 7
Whether both B are controlled so as to be operated in a direction opposite to the determination condition of (C), for example, backward. If they are the same, go to (G).

(G) Similar to (D), the detected value signal P ₂
= P ₄ , that is, whether or not straight ahead control is performed. If it is straight ahead, go to (E).

(H) When the detection value signals P ₁ ≠ P ₃ and P ₂ ≠ P ₄ in (D) and (G), respectively, and therefore, if it is not judged that the straight traveling control is performed, the detection value signals P ₁ and P ₃ Or, depending on the pressure difference between P ₂ and P ₄ , the throttle portion 50B of the electromagnetic switching valve 50
Narrow the opening. That is, the curving controllability is improved.

(I) According to (C) and (F), when both the detection value signals P ₁ and P ₃ are not larger than P ₀ and the detection value signals P ₂ and P ₄ are not larger than P ₀ , left and right It is determined that the traveling motors 7A, 7B of FIG. 6 are stopped or operated so as to be operated in the opposite direction, and the electromagnetic switching valve 50 is fully closed or the throttle amount is maximized as shown in FIG. (See section 50B), ensuring independence of the operation of the left and right running motors 7A, 7B.

(Modification of Fourth Embodiment) FIG. 9 shows an electromagnetic switching valve 6 which is a modification of the electromagnetic switching valve 50 (FIG. 7) of the fourth embodiment.
0 is an explanatory diagram showing the electromagnetic switching valve 60. The electromagnetic switching valve 60 connects the left and right direction switching valves 5A, 5B and the left and right pressure compensation valves 11A, 11B in the fourth embodiment shown in FIG. It is used instead of the switching valve 50 provided in the communication passage 17 between 15A and 15B, and has a neutral communication portion of the lower position 60A and a closed portion of the upper position 60B in FIG.

Therefore, the electromagnetic switching valve 60 operates the spools 5PA and 5PB of the left and right directional switching valves 5A and 5B to turn the hydraulic traveling vehicle in a turning or curving manner. The pressure sensors 53A and 53A are in a state in which the difference between the operation amounts or the operation directions of the 43A and 43B is maximum.
When the detected information is detected by B, 54A, and 54B and the detected information is applied to the controller 57, the microcomputer 57A calculates the spool stroke of the electromagnetic switching valve 60, and the operation signal based on the calculated value. Is applied to the spool driving portion of the switching valve 60 through the line 58, and for example, the spool is pressed against the spring force from the neutral communication position 60A to close it (FIG. 9) to close it. Position 6
0B, and the communication passage 17 is completely closed and shut off by the switching valve 60. Therefore, when the hydraulic traveling vehicle is turning or traveling in a curved manner, the left and right connection circuits 1 via the communication passage 17 are provided.
The flow of pressure oil from one of the 5A and 15B to the other is completely blocked, and the left and right operation levers 43A and 4B in this state are completely blocked.
The operability of 3B is further improved as compared with the fourth embodiment.

(Other Modification of Fourth Embodiment) FIG. 10 is an explanatory view of a changeover valve 70 of another modification of the changeover valve 50 of the fourth embodiment shown in FIG. In the fourth embodiment, the left and right connection circuits 15 for connecting the left and right direction switching valves 5A, 5B and the left and right pressure compensation valves 11A, 11B.
It is used in place of the switching valve 50 provided in the communication passage 17 between A and 15B, and its lower position 70 in FIG.
A is closed, and the upper position 70B is open.

Therefore, the left and right direction switching valves 5A, 5B
When the hydraulic traveling vehicle is turned or curved by operating the spools 5PA and 5PB of the above, the left and right operation levers-4
The difference in the operation amount or the operation direction of 3A, 43B is detected by the pressure sensors 53A, 53B, 54A, 54B, and, for example, when the maximum value information of these differences is transmitted to the controller 57, the micro computer. 57A is applied to the drive unit of the spool of the electromagnetic switching valve 70, and the spool of the electromagnetic switching valve 70 resists the spring force and moves upward from the communicating portion at the lower position 70A. Position 70
Switching to the closed portion of B, the communication passage 17 is opened by the switching valve 70. That is, the electromagnetic switching valve 70 of this modified example
The spool serves as a neutral block 70A and a moving communication portion 70B, and the flow of pressure oil from one of the left and right connection circuits 15A and 15B to the other via the communication passage 17 is allowed, and the hydraulic traveling is performed. When the vehicle is turning or traveling in a curve, the spool of the electromagnetic switching valve 70 is set to the neutral closing position 70A, the left and right connecting circuits 15A and 15B are closed and cut off, and the left and right operation levers 43A and 43B are used to make a turn. The forward operability is secured.

(Embodiment) (1) The left and right traveling hydraulic motors of a hydraulic traveling vehicle are connected via respective directional switching valves between a pump circuit connected to a variable displacement pump and a return circuit connected to a tank. At the same time, a pressure compensating valve is provided between each of the directional control valves and the hoop circuit, and the higher load pressure of each traveling hydraulic motor is guided to the discharge amount control device of the variable displacement pump via a shuttle valve. In addition, a communication passage interconnecting the connection circuits connecting the respective directional control valves and the pressure compensating valve is provided in the spool of the directional control valve, and the opening degree is changed according to the stroke. By connecting to the changing throttle, the operating levers of the left and right directional control valves of the left and right traveling hydraulic circuits are connected.
Adjustable in response to a difference in the amount of operation to one or both of the forward and reverse sides.

(2) Left and right sides each having a neutral closed portion and a throttle portion whose opening changes according to a spool stroke in a communication passage interconnecting the connection circuits connecting the respective directional control valves and the pressure compensation valve. And the left and right switching valves are connected by a pair of communication passages, and the operation levers for the left and right switching valves and the left and right directional switching valves are connected by the left and right connecting members. ..

(3) A switching valve is provided in the communication circuit that connects the left and right connection circuits that connect the directional switching valves and the pressure compensating valve, and springs are provided on both sides of the spool of the switching valve. When the pressure difference between the left and right connecting circuits exceeds a predetermined value, the spool of the switching valve is moved against the spring, and the pressure oil in one of the left and right connecting circuits is passed through the switching valve. In a control device for a traveling hydraulic circuit in a hydraulic traveling vehicle that is caused to flow to the other connection circuit, the opening degree of the throttle portion of the switching valve provided in the communication passage is set to the stroke of the spool of the switching valve. I changed it accordingly.

(4) A connection circuit connecting each of the directional control valves and the pressure compensating valve is connected to each other by a communication passage, and a neutral closing portion and a throttle portion whose opening changes according to a stroke are provided in the communication passage. Is provided, and the spool of the directional control valve is moved in response to the stroke difference between the spools of the left and right directional control valves.

(5) A connection circuit connecting each of the directional control valves and the pressure compensating valve is connected to each other through a communication passage, and the opening degree of the communication passage is substantially changed depending on the neutral closing portion and the stroke. A switching valve having a different communication portion is provided, and the spool of the switching valve is moved in response to the stroke difference between the spools of the left and right directional switching valves.

(6) A connecting circuit connecting each of the directional control valves and the pressure compensating valve is made to communicate with each other through a communication path, and an electromagnetic switching valve is provided in the communication path to operate the left and right directional control valves. A hydraulic pressure responsive to one or both operation amounts is applied to the spool of the directional control valve via a pilot passage, and a pressure sensor is provided in the pilot passage, and a pressure detection signal by the pressure sensor is applied to the electromagnetic sensor. The spool of the throttle part of the switching valve is used to operate the left and right direction switching valves.
Is applied to a controller equipped with a microcomputer for calculating the spool stroke so that the opening corresponds to the difference in the manipulated variable, and the calculated value of the microcomputer is applied to the electromagnetic switching valve. The spool drive signal is applied to the spool drive section.

(7) The connection circuit connecting each of the directional control valves and the pressure compensating valve is communicated with each other through a communication passage, and the communication passage is closed by moving a communication portion that always opens the passage. While providing an electromagnetic switching valve having a closing portion, the hydraulic pressure responsive to the operation amount of one or both of the operation levers of the left and right directional switching valves is supplied to the spool of the directional switching valve via the pilot passage. Applying the detection signal from the pressure sensor of the pilot passage to the microcomputer of the controller, the spool stroke of the electromagnetic switching valve corresponding to the operation amount of the left and right operation levers.
Is calculated and the calculated value is used to
Drive the valve to substantially change the opening degree of the communicating portion in accordance with the stroke, and when the calculated value of the detection value of the pressure sensor is a predetermined value or more, the electromagnetic switching valve is closed. I tried to get to switch to.

(8) The connecting circuit connecting each of the directional control valves and the pressure compensating valve is made to communicate with each other through a communication passage, and the communication passage is opened by movement of a closing portion that constantly closes the communication passage. While providing an electromagnetic switching valve having an opening portion, the hydraulic pressure responsive to the operation amount of one or both of the operation levers of the left and right directional switching valves is supplied to the spool of the directional switching valve via the pilot passage. Applying the detection signal from the pressure sensor of the pilot passage to the microcomputer of the controller, the spool stroke of the electromagnetic switching valve corresponding to the operation amount of the left and right operation levers.
Is calculated and the calculated value is used to
By driving the valve, the opening of the communicating portion is substantially changed according to the stroke, and the calculated value of the detected value of the pressure sensor is switched to the open position when the calculated value is a predetermined value or more. thing.

[0061]

Since the present invention has the above-mentioned structure and operates, the following unique effects can be expected.

(1) By selecting the neutral position of the operating levers of the left and right direction changeover valves, it is possible to expect a reliable straight running property on a flat ground similar to the control device of the running hydraulic circuit in a normal hydraulic running vehicle. A connection circuit that connects each of the directional switching valves and the pressure compensating valve when the hydraulic traveling vehicle is turned or curved by operating one of the outer and left and right directional switching valves or operating both at different angles is further provided. Since the spool of the switching valve provided in the communication passage connected to each other is moved appropriately and the opening of the throttle portion is changed to limit the amount of pressure oil flowing in the communication passage, the hydraulic traveling vehicle. The operability in the turning or curving traveling state is improved while ensuring the operability in straight traveling.

(2) Since the opening degree of the throttle portion of the directional control valve provided in the passage is adjusted according to the spool stroke of the directional control valve, it is assumed that the directional control valve has some processing error. However, by operating the operating lever of the directional control valve in the same operating procedure as a conventional hydraulic traveling vehicle of the same kind, the hydraulic traveling vehicle can be turned or bent while ensuring straight running performance. Since the communication passages of the left and right directional control valves are closed or throttled in correspondence with the spool strokes of the left and right directional control valves during traveling, etc., without increasing the stroke of the operating lever of the directional control valve. The target turning or curving traveling operability of the hydraulic traveling vehicle can be secured.

(3) A switching valve whose opening changes in response to a spool stroke of the directional switching valve is provided in the communication passage, and the spool of the directional switching valve is connected to the spool of the directional switching valve. By controlling the amount of pressure oil flowing through the communication passage according to the spool stroke of the directional control valve, the rotational speeds of the left and right hydraulic traveling motors are controlled to the target of the hydraulic traveling vehicle. It is possible to easily select a turning radius suitable for a turning or curving traveling state, and expect smooth turning or curving traveling operability.

(4) The right and left connecting circuits connecting the respective directional control valves and the pressure compensating valve are further connected to the communication passages, and the throttle opening changes according to the neutral closing position and the moving stroke. The present invention can be easily applied to a control device for a traveling hydraulic circuit in an existing hydraulic traveling vehicle of the same type by providing a left and right switching valve and modifying the left and right switching valves so that the left and right switching valves communicate with each other. Will be implemented.

(5) A change-over valve with a throttle, which is provided with a connecting circuit for connecting each of the directional control valves and the pressure compensating valve in the connecting passage, and which has a variable opening, is used as an operating lever for the left and right directional control valves. One or both operating pressures are detected by a pressure sensor that detects the operating pressure in the communication passage that transmits to the spool of the directional control valve, this detection signal is applied to the controller, and the calculation is performed by this controller. , An output signal of the spool stroke of the directional control valve in response to the spool stroke of the directional control valve,
The structure is such that it is applied to the spool drive part of the switching valve to control the opening of the throttle part, so that the structure of the switching valve with a throttle and the degree of freedom in designing the spool stroke and the like are improved. ,
Moreover, the present invention can be easily implemented with respect to the existing similar type device without largely changing the structure.

(6) In the hydraulic traveling vehicle traveling by the left and right traveling hydraulic motors, the throttle of the switching valve provided in the communication passage connecting the respective connection circuits of the left and right directional switching valves and the left and right pressure compensation valves. Since the opening degree of the section is configured to be changed in accordance with the spool stroke of the directional control valve,
There is no fear of causing a direction deviation to the outside of the planned course, such as in the case of turning or curving as in the conventional example.

(7) If the spool of the directional control valve and the spool of the directional control valve are made to interlock with each other by the connecting member, the opening degree of the throttle portion provided in the spool of the directional control valve causes the spool of the directional control valve to move. The stroke of the hydraulic traveling vehicle is changed, and the straight traveling along the longitudinal direction of the slope such as an embankment is performed by a simple operation of the required angle of the directional control valve of the hydraulic traveling vehicle in the required direction. It is possible to perform curved traveling, turning operation, etc. more easily.

(8) The pilot pressure based on the operation amount difference between the operation levers of the left and right directional control valves is detected by the pressure sensor, and the detected value is applied to the micro computer of the controller to perform the left and right operations. Since the stroke of the solenoid operated directional control valve is calculated based on the difference in the manipulated variable of the valve, it is switched.
Not only can the electromagnetic switching valve be constructed as a simple structure consisting of a communicating portion and a block, but it can also be applied to both a closed type by turning on the electromagnetic switching valve and an open type by turning on the electromagnetic switching valve. In any case, the opening of the communicating portion is substantially reduced in a range where the pressure sensor detects a small value.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a first embodiment of a control device for a traveling hydraulic circuit in a hydraulic traveling vehicle according to the present invention.

FIG. 2 shows a schematic longitudinal explanatory view of a control valve implementing the first embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram of a second embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram of a third embodiment of the present invention.

FIG. 5 is an explanatory view of a modification of the switching valve according to the third embodiment of the present invention.

FIG. 6 is an explanatory view of another modification of the switching valve according to the third embodiment of the present invention.

FIG. 7 is a hydraulic circuit diagram of a fourth embodiment of the present invention.

FIG. 8 is a diagram showing the hydraulic pressure of a pilot circuit based on the operation of the left and right operation levers according to the fourth embodiment of the present invention, detected by a pressure sensor, and applying the detection signal to the controller, thereby 6 is a flow chart of a circuit for calculating a required stroke of a spool of the electromagnetic switching valve of the communication passage by a controller.

FIG. 9 is an explanatory view of a modification of the electromagnetic switching valve according to the fourth embodiment of the present invention.

FIG. 10 is an explanatory view of another modification of the electromagnetic switching valve according to the fourth embodiment of the present invention.

FIG. 11 is a hydraulic circuit diagram of a control device for a traveling hydraulic circuit in a conventional hydraulic traveling vehicle.

[Explanation of symbols]

1 ... Variable capacity pump 2 ... Discharge rate control device 3 ... Pump circuit 5A, 5B ... Left and right direction switching valve 5PA, 5PB ... Left and right direction switching valve spool 7A, 7B. -Turn 9A, 9B ...... Return circuit 11A, 11B ...... Left and right pressure compensation valves 12 ...... Pilot passage 13 ...... Shuttle valve 15A, 15B ...... Left and right connection circuit 17 ...... Communication passage 21A, 21B, 22A, 22B ...... Throttle section 23, 24 ...... Communication passage 31A, 31B ...... Left and right switching valve (with neutral communication section and throttle section) 33A, 33B ...... Left and right connecting member 40 ...... Switching valve (neutral communication section and throttle section) 43A, 43B ...... Left and right operation levers 44A, 44B, 45A, 45B ...... Pilot passage 46 ...... Switching valve (with neutral communication part and moving closing part) 48 ...... Switching valve (neutral closing part and moving communication) Part) 50 ... Electromagnetic switching valve (with neutral communication part and throttle part) 51A, 51B, 52A, 52B ... Pilot passage 53A, 53B, 54A, 54B ... Pressure sensor 55A, 55B, 56A, 56B, 58 ... Signal line 57 ... Control -La 57A: Microcomputer 60: Electromagnetic switching valve (with neutral communication part and moving communication part) 70 ... Electromagnetic switching valve (with neutral closing part and moving communication part)

[Procedure amendment]

[Submission date] November 27, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 5]

[Figure 6]

[Figure 3]

[Figure 9]

[Figure 10]

[Figure 4]

[Figure 7]

[Figure 8]

FIG. 11

Claims (4)

[Claims] 1. Left and right traveling hydraulic motors are connected via respective directional switching valves between a pump circuit to which a variable displacement pump is connected and a return circuit to which a tank is connected, and the directional switching is also provided. A pressure compensating valve is provided between the valve and the homp circuit, and the higher load pressure of each traveling hydraulic motor is guided to the discharge amount control device of the variable displacement pump through the shuttle valve, while each of the directions The connecting circuit of the switching valve and the pressure compensating valve are mutually connected by a communication passage, and the directional switching valves are provided at appropriate places of the communication passage, closed at their neutral positions, and closed at their respective operating positions. A control device for a hydraulic circuit for traveling in a hydraulic traveling vehicle, characterized in that a throttle portion whose opening changes according to the stroke of the direction switching valve is interposed. 2. Left and right traveling hydraulic motors are connected via respective directional switching valves between a pump circuit to which a variable displacement pump is connected and a return circuit to which a tank is connected, and the respective directional switching is performed. A pressure compensating valve is provided between the valve and the homp circuit, and the higher load pressure of each traveling hydraulic motor is guided to the discharge amount control device of the variable displacement pump through the shuttle valve, while each of the directions The connection circuit of the switching valve and the pressure compensating valve are mutually connected by a communication passage, and the communication passage is provided with a neutral closing portion and a switching valve with a throttle portion whose opening changes according to the stroke of each directional switching valve. A control device for a hydraulic circuit for traveling in a hydraulic traveling vehicle, characterized in that the spool of the switching valve with a throttle portion is interlocked with the spool of the directional switching valve by appropriate interlocking means. 3. The left and right traveling hydraulic motors are connected via respective directional switching valves between a pump circuit to which a variable displacement pump is connected and a return circuit to which a tank is connected, and the respective directional switching is performed. A pressure compensating valve is provided between the valve and the homp circuit, and the higher load pressure of each traveling hydraulic motor is guided to the discharge amount control device of the variable displacement pump through the shuttle valve, while each of the directions A switching valve and a pressure compensating valve are connected to each other through a communication passage, and a neutral communication portion and a switching valve with a throttle portion whose opening changes according to the stroke of each direction switching valve are provided in the communication passage. Control of a hydraulic circuit for traveling in a hydraulic traveling vehicle, characterized in that pressure oil of an operation pilot circuit of an operation lever of the directional switching valve is applied to the spool of the switching valve with the throttle portion to perform switching. apparatus. 4. The left and right traveling hydraulic motors are connected via respective directional switching valves between a pump circuit to which a variable displacement pump is connected and a return circuit to which a tank is connected, and the directional switching is also provided. A pressure compensating valve is provided between the valve and the homp circuit, and the higher load pressure of each traveling hydraulic motor is guided to the discharge amount control device of the variable displacement pump via the shuttle valve, while the above-mentioned respective directions are provided. An electromagnetic switching valve in which a switching valve and a pressure compensating valve are connected to each other through a communication passage, and the communication passage has a throttle portion whose opening changes according to the stroke difference between the neutral communication portion and each direction switching valve. A pressure sensor is provided in the operation circuit of each of the directional control valves, the detection signal from the pressure sensor is applied to the controller, and the detection signal from the pressure sensor is responded to by the microcomputer of the controller. Electromagnetic switching A drive signal for the valve stroke is calculated, and the calculated drive signal for the spool stroke of the electromagnetic switching valve is applied to the spool drive section of the electromagnetic switching valve. A control device for a hydraulic circuit for traveling in a hydraulic traveling vehicle, characterized in that a stroke or curving traveling property of the hydraulic traveling vehicle is secured by adjusting a stroke.