JP2001012403A - Hydraulic driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a flow amount of pressure oil to be supplied to respective actuators in a hydraulic driving device even in the case where load pressure of the actuator related to an upstream side directional changeover valve is high, while the load pressure of the actuator in related to a downstream side directional changeover valve is low. SOLUTION: A parallel passage 22 branched from a discharge passage 2a of a hydraulic pump 2 is connected to a downstream side of a check valve 23b on a flow passage connected to a supply port of a directional changeover valve 4b, as a passage for supplying pressure oil to the downstream side directional changeover valve 4b, other than a center bypass passage 7 for tandem- connection. The parallel passage 22 is then parallely connected to an upstream side directional changeover valve 4a. A pressure control valve 8 for controlling pressure difference across the directional changeover valve 4a is arranged on the parallel passage 22, as an auxiliary control valve for controlling a flow amount of the pressure oil passing through the parallel passage 22 according to an operation rate of an operation lever 6y for controlling the downstream side directional changeover valve 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive device provided in a hydraulic machine such as a hydraulic shovel or the like, and more particularly to a tandem connection in which at least a part of a multiple direction switching valve having a center bypass passage is connected in parallel. The present invention relates to a hydraulic drive device capable of supplying pressure oil to an actuator in both parallel connections.

[0002]

2. Description of the Related Art A hydraulic drive device in which at least a part of a multiple direction switching valve connected in tandem by a center bypass passage is connected in parallel so that pressure oil can be supplied to an actuator in both the tandem connection and the parallel connection is known. FIG. 2 of JP-A-8-105078 and Japanese Patent No. 263
This is described in FIG.

In the hydraulic drive system shown in FIG. 2 of JP-A-8-105078, a direction connected to a discharge passage of a variable displacement hydraulic pump and located on an upstream side in a center bypass passage of a multiple direction switching valve. The switching valve and a direction switching valve located on the downstream side are connected via a parallel passage, and a throttle valve (fixed throttle) is arranged in the parallel passage.

By providing the throttle valve on the parallel passage as described above, the operating lever of the upstream directional switching valve can be operated during the combined operation of the actuator that simultaneously operates the upstream directional switching valve and the downstream directional switching valve. Even when the center bypass passage is closed by fully operating the device and pressure oil is not supplied from the center bypass passage to the direction switching valve on the downstream side, pressure oil is supplied from the parallel passage to the direction switching valve, and Supply of pressure oil to the actuator of the switching valve can be secured.

In the hydraulic drive system shown in FIG. 1 of Japanese Patent No. 2639554, the supply pressure of the supply port of the direction switching valve on the upstream side is guided to the parallel passage instead of the throttle valve in the valve opening direction. A configuration in which a load control valve that controls a supply pressure so that a load pressure of an actuator related to an upstream direction switching valve is guided in a valve closing direction and a differential pressure between the supply pressure and the load pressure is kept constant; Has become.

[0006] By providing the pressure control valve on the parallel passage as described above, the operation of the upstream directional switching valve can be controlled during the combined operation of the actuator that simultaneously operates the upstream directional switching valve and the downstream directional switching valve. When the lever device is fully operated to close the center bypass passage, and there is no supply of pressure oil from the center bypass passage to the directional switching valve on the downstream side, even if the actuator related to the directional switching valve on the upstream side is on the low pressure side, Since the pressure difference between the supply pressure and the load pressure of the directional control valve on the upstream side (the pressure difference before and after the meter-in variable throttle of the directional control valve) is kept constant, the flow rate of the pressure oil supplied to the actuator is also reduced to the load pressure. Regardless, the remaining flow rate, which is kept constant and the flow rate of the hydraulic oil supplied to the actuator is subtracted from the discharge flow rate of the hydraulic pump, is switched from the parallel passage to the downstream direction. Supplied to that, it can be secured supply of pressure oil to the actuator of the downstream directional control valve.

[0007]

However, in the above-mentioned conventional hydraulic drive, the load pressure of the actuator related to the upstream directional switching valve is high and the load pressure of the actuator related to the downstream directional switching valve is low. The following problems occur during the combined operation of the actuator.

In the hydraulic drive system shown in FIG. 2 of JP-A-8-105078, the operation lever device is fully operated so that the speed of the actuator related to the directional control valve on the upstream side is increased, and the center bypass passage is opened. Even if the pressure oil is not closed from the center bypass passage to the downstream side, most of the discharge flow rate of the hydraulic pump is supplied to the actuator having a low load pressure related to the directional control valve on the downstream side via the parallel passage and the throttle valve. As a result, sufficient pressure oil cannot be supplied to the actuator related to the direction switching valve on the upstream side, and the combined operability is reduced.

In the hydraulic drive device shown in FIG. 1 of Japanese Patent No. 2639554, the operating lever device 6 is designed to increase the speed of the actuator associated with the upstream directional control valve.
When the center a bypass passage is closed by fully operating a so that the pressure oil does not flow downstream from the center bypass passage, if the discharge flow rate of the hydraulic pump is sufficient, the excess flow rate of the discharge flow rate is increased by the parallel passage and Although supplied to the actuator related to the downstream direction switching valve via the pressure control valve, the flow rate of the pressure oil discharged from the hydraulic pump and the flow rate of the pressure oil supplied to the actuator of the upstream direction switching valve are appropriately balanced. In the state, a state occurs in which there is no flow rate of the pressure oil supplied to the actuator of the downstream direction switching valve, and the combined operability is reduced.

[0010] An object of the present invention is to provide an operator with a combined operation of an actuator even when the load pressure of the actuator related to the upstream directional control valve is high and the load pressure of the actuator related to the downstream directional control valve is low. It is an object of the present invention to provide a hydraulic drive device capable of securing the flow rate of the pressure oil supplied to each actuator in accordance with the operation situation required by the above.

[0011]

(1) In order to achieve the above object, the present invention provides a variable displacement hydraulic pump, a plurality of actuators driven by pressure oil discharged from the variable displacement hydraulic pump, A multiple direction switching valve having a center bypass passage for controlling a flow of pressure oil supplied from the variable displacement hydraulic pump to the plurality of actuators; In a hydraulic drive device having a parallel passage for connecting a direction switching valve located on the upstream side and a direction switching valve located on the downstream side in a center bypass passage of the switching valve in parallel, the downstream direction is provided on the parallel passage. An auxiliary control valve for controlling a flow rate passing through the parallel passage according to an operation amount of an operation lever for operating the switching valve is provided.

By providing the auxiliary control valve on the parallel passage as described above, the load pressure of the actuator related to the directional control valve on the upstream side is high and the load pressure of the actuator related to the directional control valve on the downstream side is low. However, the flow rate of the pressure oil to be supplied to each actuator can be ensured according to the operation situation requested by the operator.

(2) In the above (1), preferably,
The auxiliary control valve is configured such that a supply pressure of the upstream direction switching valve is guided in a valve opening direction, a load pressure of an actuator related to the upstream direction switching valve is guided in a valve closing direction, and the downstream direction is changed. The pressure control valve controls the supply pressure such that the differential pressure between the supply pressure and the load pressure decreases as the operation amount of the operation lever of the switching valve increases.

By configuring the auxiliary control valve with a pressure control valve in this way, the load pressure of the actuator related to the directional switching valve on the upstream side is high and the load pressure of the actuator related to the directional switching valve on the downstream side is low. Even if there is, a flow rate corresponding to the pressure difference between the supply pressure and the load pressure controlled by the pressure control valve is supplied from the upstream directional switching valve to the corresponding actuator, and the excess flow rate is responded from the downstream directional switching valve. And the differential pressure between the supply pressure and the load pressure of the upstream directional control valve decreases as the operation amount of the operation lever of the downstream directional control valve increases. The flow rate of the pressure oil supplied from the directional switching valve on the side to the corresponding actuator decreases,
The flow rate of the pressure oil supplied to the corresponding actuator from the direction switching valve on the downstream side increases, and the flow rate of the pressure oil supplied to each actuator can be secured according to the operation situation requested by the operator.

(3) In the above (1), the auxiliary control valve is a variable throttle valve whose throttle amount is adjusted in accordance with an operation amount of an operation lever of the downstream direction switching valve; The downstream pressure is guided in the valve opening direction, the load pressure of the actuator related to the upstream direction switching valve is guided in the valve closing direction, and the downstream pressure of the variable throttle valve becomes the same as the load pressure. And a pressure control valve for performing such control.

By forming the auxiliary control valve with the variable throttle valve and the pressure control valve in this manner, the pressure on the downstream side (outlet pressure) of the variable throttle valve is the same as the load pressure of the actuator related to the direction switching valve on the upstream side. So that the differential pressure across the variable throttle valve is controlled to be the same as the differential pressure across the meter-in variable throttle of the directional switching valve on the upstream side. As a result, the discharge flow rate of the hydraulic pump is controlled by the directional switching valve. Are distributed according to the opening area ratio of the meter-in variable throttle and the variable throttle valve. For this reason, even when the load pressure of the actuator related to the upstream direction switching valve is high and the load pressure of the actuator related to the downstream direction switching valve is low,
The discharge flow rate of the hydraulic pump is distributed from the upstream and downstream direction switching valves to the respective actuators, and the throttle amount of the variable throttle valve is changed according to the operation amount of the operation lever of the downstream direction switching valve. In addition, the discharge flow rate from the hydraulic pump is distributed and controlled according to the operation amount of the operation lever, and the flow rate of the pressure oil supplied to each actuator can be secured according to the operation situation requested by the operator.

(4) In the above (2) or (3), preferably, there are a plurality of directional control valves on the upstream side,
Means are provided for detecting the maximum load pressure of the plurality of actuators associated with the plurality of directional control valves, and the load pressure guided in the valve closing direction of the pressure control valve is the maximum load pressure.

Accordingly, even when there are a plurality of directional control valves on the upstream side, the combined operation of the actuators related to them and the actuators related to the directional control valve on the downstream side may be difficult.
The operations described in the above (2) and (3) are obtained, and the flow rate of the pressure oil supplied to each actuator can be ensured in accordance with the operation situation requested by the operator regardless of the magnitude of the load pressure of the actuator.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, a variable displacement hydraulic pump 2
And a fixed displacement hydraulic pump 3 is a hydraulic pump driven by a power source 1 such as an engine. The hydraulic oil discharged from the hydraulic pump 2 is supplied to actuators 5a and 5b, and the actuators 5a and 5b are driven. . A directional control valve 4 is provided between the hydraulic pump 2 and the actuators 5a and 5b.
a, 4b are arranged to control the flow (direction and flow rate) of the pressure oil supplied to the actuators 5a, 5b, respectively.

The direction switching valves 4a and 4b are configured as open center type multiple valves having a center bypass passage 7, and are connected to the center bypass passage 7 in tandem. That is, the supply ports of the direction switching valves 4a and 4b are connected to the center bypass passage 7 via the check valves 23a and 23b, and the center bypass passage 7 is connected to the discharge passage 2a of the hydraulic pump 2 to switch the direction on the downstream side. Pressure oil is preferentially supplied to the direction switching valve 4a on the upstream side of the valve 4b.

As a pressure oil supply passage for the directional switching valve 4b on the downstream side, a parallel passage 22 branched from the discharge passage 2a of the hydraulic pump 2 is provided in addition to the center bypass passage 7 for tandem connection. The parallel passage 22 is connected to the downstream side of the check valve 23b on the flow path connected to the supply port of the direction switching valve 4b, and the direction switching valve 4b is connected in parallel with the direction switching valve 4a on the upstream side. The pressure control valve 8 is provided in the parallel passage 22.

The directional control valves 4a and 4b are of a pilot operated type, and the pressure oil discharged from the hydraulic pump 3
is supplied to a pilot valve (pressure reducing valve; not shown) in the operation lever devices 6a and 6b through the control lever device 6a.
The switching operation is performed by the pilot pressure generated in the pilot passage 61 or 62 and the pilot passage 63 or 64 in accordance with the operation state (operation direction and operation amount) of the operation levers 6x and 6y of a and 6b. In the pilot passages 63 and 64, a shuttle valve 25 for selecting the higher one of the respective pressures and detecting the pilot pressure is provided.

The pressure control valve 8 includes a downstream directional switching valve 4b.
And an auxiliary control valve for controlling the flow rate passing through the parallel passage 22 in accordance with the operation amount of the operation lever 6y for operating the control lever 6y. Hereinafter, the details of the pressure control valve 8 will be described.

The pressure control valve 8 has a spring 25 for urging the valve body 24 in the valve closing direction, and the supply pressure of the direction switching valve 4a on the upstream side is guided by the parallel passage 22 and the supply pressure detection passage 26. A first pressure receiving portion 27 for urging the valve 24 in the valve opening direction;
The load pressure of the actuator 5a related to the direction switching valve 4a on the upstream side is guided by the load pressure detection passage 28, and the valve body 24
And a second pressure receiving portion 29 for urging the valve in the valve closing direction.
The pilot passage 63 detected by the shuttle valve 25,
There is a third pressure receiving portion 31 that guides the higher pressure of the valve 64, that is, the pilot pressure through the pilot pressure detection passage 30 and urges the valve body 24 in the valve opening direction.

The spring 25 determines the differential pressure between the supply pressure of the direction switching valve 4a (discharge pressure of the hydraulic pump 2) and the load pressure of the actuator 5a, that is, the reference pressure of the differential pressure before and after the meter-in variable throttle of the direction switching valve 4a. And the third pressure receiving unit 31
The reference pressure is reduced according to the pilot pressure in the pilot pressure detection passage 30 (the operation amount of the operation lever 6y of the direction switching valve 4b).

FIG. 2 shows the characteristics of the pressure control valve 8. In this example, the reference pressure of the spring 25 is set to 1.96 MPa. In this way, the reference pressure is set by the spring 25, and the reference pressure is corrected so as to be reduced according to the pilot pressure of the pilot pressure detection passage 30 (the operation amount of the operation lever 6y of the direction switching valve 4b). Direction switching valve 4
The differential pressure between the supply pressure and the load pressure, that is, the differential pressure before and after the meter-in variable throttle of the direction switching valve 4a, is controlled to decrease as the operation amount of the operation lever 6y of b increases.

That is, the pressure control valve 8 is connected to the direction switching valve 4a.
The pressure difference between the supply pressure (discharge pressure of the hydraulic pump 2) and the load pressure of the actuator 5a (the pressure difference before and after the meter-in variable throttle of the direction switching valve 4a) is the set value of the spring 25 (reference pressure).
The parallel passage 2 is set to be equal to a value obtained by subtracting a correction value of the pilot pressure detection passage 30 by the pilot pressure from the pilot passage.
2, the supply pressure of the direction switching valve 4a is controlled.

Next, the operation of this embodiment configured as described above will be described.

First, the independent operation of the actuator 5a or 5b will be described.

The hydraulic oil discharged from the hydraulic pump 2 is guided to the supply port of the direction switching valve 4a via the discharge passage 2a and the check valve 23a, and the operator operates the operation lever 6x of the operation lever device 6a, and the pilot When the pilot pressure is generated in the passage 61 or 62, the direction switching valve 4a is switched by the pilot pressure, and the flow rate and the flow direction of the pressure oil supplied to the actuator 5a are controlled.

The hydraulic oil discharged from the hydraulic pump 2 is supplied to the discharge passage 2a, the center bypass passage 7, the check valve 2, and the like.
3b, the discharge passage 2a, and the parallel passage 2
2, through two passages through the pressure control valve 8, the passage is guided to the supply port of the direction switching valve 4b, and the operator operates the operation lever 6y of the operation lever device 6b, and the pilot pressure is supplied to the pilot passage 63 or 64. Is generated, the direction switching valve 4b is switched by the pilot pressure, and the flow rate and the flow direction of the pressure oil supplied to the actuator 5b are controlled.

Next, the combined operation of the actuators 5a and 5b will be described together with the operation of the pressure control valve 8.

Operation lever device 6 on actuator 5a side
It is assumed that the operation lever 6x of a is fully operated, the center bypass passage 7 is closed, and the flow supply path to the downstream directional switching valve 4b via the center bypass passage 7 is closed. In this state, when the operating lever 6y of the operating lever device 6b on the side of the actuator 5b is operated to generate pilot pressure in the pilot passage 63 or 64,
The direction switching valve 4 b is switched by the pilot pressure, and the pilot pressure is guided to the third pressure receiving portion 31 on the valve opening side of the pressure control valve 8.

On the other hand, the supply pressure (discharge pressure of the hydraulic pump 2) of the direction switching valve 4a is guided to the first pressure receiving portion 27 on the valve opening side of the pressure control valve 8, and is supplied to the second pressure receiving portion 29 on the valve closing side. Indicates the load pressure of the actuator 5a, and the pressure control valve 8
Operates as shown in FIG. That is, the pressure difference between the supply pressure of the directional control valve 4a and the load pressure of the actuator 5a (the differential pressure before and after the meter-in variable throttle of the directional control valve 4a) is determined from the set value (reference pressure) of the spring 25 by the pilot pressure detection passage 30.
Is controlled to be the same as the value obtained by subtracting the correction value based on the pilot pressure. Therefore, if the flow rate of the pressure oil supplied to the actuator 5a is going to flow more than necessary, the supply pressure of the direction switching valve 4a (upstream pressure of the pressure control valve 8)
Rises, the pressure control valve 8 opens, and the actuator 5a
The surplus flow rate of the pressure oil supplied to the actuator 5b can be supplied to the actuator 5b.

Here, the pilot pressure in the pilot pressure detecting passage 30 is constant if the operation amount of the operation lever 6y of the operation lever device 6b is constant, and the pressure control valve 8 is used to control the meter-in variable throttle of the direction switching valve 4a. The differential pressure is also controlled to be constant, and a constant flow rate is supplied to the actuator 5a, while the remaining flow rate (excess flow rate) of the discharge flow rate of the hydraulic pump 2 is supplied to the actuator 5b.

When the pressure in the pilot pressure detecting passage 30 increases in accordance with the operation amount of the operation lever 6y of the operation lever device 6b, the pressure control valve 8 reduces the pressure difference between the front and rear of the meter-in variable throttle of the direction switching valve 4a. Control is performed so as to have a small value, the flow rate of the pressure oil supplied to the actuator 5a decreases, and the excess flow rate supplied to the actuator 5b increases.

That is, by controlling the pressure difference between the supply pressure and the load pressure of the direction switching valve 4a (the pressure difference before and after the meter-in variable throttle), the flow rate corresponding to the pressure difference is controlled from the upstream direction switching valve 4a. The excess flow rate is supplied to the corresponding actuator 5a, the surplus flow rate is supplied from the downstream direction switching valve 4b to the corresponding actuator 5b, and the upstream side increases as the operation amount of the operation lever 6y of the downstream direction switching valve 4b increases. , The pressure difference between the supply pressure and the load pressure of the directional control valve 4a decreases, and accordingly, the flow rate of the pressure oil supplied from the directional control valve 4a on the upstream side to the corresponding actuator 5a decreases, and the flow rate in the downstream direction decreases. Control is performed to increase the flow rate of the pressure oil supplied from the switching valve 4b to the corresponding actuator 5b.

The flow distribution control by the pressure control valve 8 described above is obtained regardless of the magnitude of the load pressure of the actuators 5a and 5b. When the load pressure of the actuator 5a is high and the load pressure of the actuator 5b is low, the actuators 5a and 5b are controlled. Also during the combined operation of the operation lever 5b, a flow rate according to the operation amount of the operation lever 6y of the operation lever device 6b can be supplied to the actuator 5b, and the actuator 5b can be driven.

As described above, according to the present embodiment, the load pressure of the actuator 5a related to the upstream direction switching valve 4a is high, and the load pressure of the actuator 5b related to the downstream direction switching valve 4b is low. However, the flow rate of the pressure oil to be supplied to each of the actuators 5a and 5b can be ensured according to the operation situation requested by the operator.

A second embodiment of the present invention will be described with reference to FIGS. In FIG. 3, the same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 3, the hydraulic drive device of the present embodiment includes a variable throttle valve 71 in the parallel passage 22 and a pressure control valve 81 located downstream of the variable throttle valve 71.

The variable throttle valve 71 is of a pilot operation type that moves in conjunction with the direction switching valve 4b. When the operation lever 6y of the operation lever device 6b is in the neutral position, the variable throttle valve 71 is in the closed position (opening degree 0). When operated, the switching operation is performed according to the operation status of the operation lever 6y so that the opening degree (opening area) increases according to the operation amount.

FIGS. 4A and 4B show the opening characteristics of the variable throttle valve 71. FIG. FIG. 4A shows a case where the variable throttle valve 71 is set to open at the same time as the lever input of the operation lever 6y. FIG. 4B shows a state after the lever input of the operation lever 6y is inputted to some extent. This is a case where the variable throttle valve 71 is set to open.

The pressure control valve 81, in combination with the variable throttle 71, serves as an auxiliary control valve for controlling the flow rate passing through the parallel passage 22 according to the operation amount of the operation lever 6y for operating the downstream direction switching valve 4b. Constitute.

That is, the pressure control valve 81 is
The pressure on the downstream side is guided by the pressure detection passage 32, and the load pressure of the first pressure receiving portion 34 for urging the valve body 33 in the valve opening direction and the load pressure of the actuator 5a related to the direction switching valve 4a on the upstream side are detected by the load pressure detection. A variable throttle valve 71 which is guided by the passage 35 and urges the valve body 33 in the valve closing direction.
Is controlled to be the same as the load pressure.

Here, the inlet pressure of the variable throttle valve 71 is the same as the supply pressure of the direction switching valve 4a (the inlet pressure of the meter-in variable throttle of the direction switching valve 4a).
Is controlled so that the pressure (outlet pressure) on the downstream side of the valve becomes equal to the load pressure of the actuator 5a.
1 is controlled so as to be equal to the differential pressure across the meter-in variable throttle of the directional control valve 4a. As a result, the discharge flow rate of the hydraulic pump 2 is controlled by the meter-in variable throttle and the variable throttle of the directional control valve 4a. The distribution is performed according to the ratio of the opening area to the valve 71. That is, by changing the opening area of the variable throttle valve 71 according to the operation amount of the operation lever 6y, the discharge flow rate from the hydraulic pump 2 is distributed and controlled according to the operation amount of the operation lever 6y.

The combined operation of the actuators 5a and 5b according to the present embodiment configured as described above will be described.

Operation lever device 6 on the actuator 5a side
It is assumed that the operation lever 6x of a is fully operated, the center bypass passage 7 is closed, and the flow supply path to the downstream directional switching valve 4b via the center bypass passage 7 is closed. In this state, when the operation lever 6y of the operation lever device 6b on the side of the actuator 5b is operated to switch the direction switching valve 4b, the variable throttle valve 71 is also switched in conjunction with the operation, and the operation amount of the operation lever 6y is changed. The opening degree.

On the other hand, the pressure on the downstream side of the variable throttle valve 71 is guided to the first pressure receiving portion 34 on the valve opening side of the pressure control valve 81, and the load pressure of the actuator 5a is supplied to the second pressure receiving portion 36 on the valve closing side. The pressure control valve 81 operates as described above, and the discharge flow rate of the hydraulic pump 2 is distributed according to the degree of opening of the variable throttle valve 71 and the meter-in variable throttle of the direction switching valve 4a. .

The flow distribution control by the combination of the variable throttle valve 71 and the pressure control valve 81 is performed by the actuator 5a.
The operation of the operation lever 6y of the operation lever device 6b can be obtained regardless of the magnitude of the load pressure of the operation lever device 6b even when the actuator 5a has a high load pressure and the actuator 5b has a low load pressure. The flow rate according to the amount can be supplied to the actuator 5b, and the actuator 5b can be driven.

Here, the opening degree of the variable throttle valve 71 is shown in FIG.
If the setting is made as shown in (a), the flow rate is supplied to the actuator 5b simultaneously with the lever input of the operation lever 6y. FIG. 4B shows the opening of the variable throttle valve 71.
With this setting, the flow rate is supplied to the actuator 5b after the lever input of the operation lever 6y is input to some extent.

Since the directional control valves 4a and 4b are connected in tandem and have a structure in which the pressure oil is supplied preferentially to the actuator 5a, the operation lever 6x is fully operated, and the actuator 5b is operated in this state. If it is desired to move, the speed of the actuator 5a should be kept as low as possible.

Therefore, instead of operating the operation lever 6b and supplying hydraulic oil to the direction switching valve 4b from the parallel passage 22 at the same time, the opening of the variable throttle valve 71 is opened after the operation amount of the operation lever 6y is input to some extent. FIG. 4 (b)
It is preferable to set as follows.

When the operator operating the machine operates the operation lever 6y and the actuator 5b does not move, the operator operates to increase the operation amount of the operation lever 6y. When such an operation is performed, the actuator 5
This is a case in which it is desired to move the actuator 5b even when the speed of a decreases. Therefore, it is preferable that the setting is made as shown in FIG.

A third embodiment of the present invention will be described with reference to FIG. In the figure, the same members as those shown in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 5, the present embodiment is different from the second embodiment in that a tandem connection between a directional control valve 4a and a directional control valve 4b arranged in a center bypass passage 7 is provided. The third direction switching valve 4c is arranged as a part.

The directional control valve 4c has a supply port connected to the center bypass passage 7 via a check valve 23c.
The flow (direction and flow rate) of the pressure oil supplied to the actuator 5c is controlled.

The directional control valve 4c is of a pilot operated type, and pressurized oil discharged from the hydraulic pump 3 is supplied to the discharge passage 3c.
is supplied to the operation lever device 6c via the switch a, and the switching operation is performed by the pilot pressure generated in the pilot passages 65 and 66 according to the operation state (operation direction and operation amount) of the operation lever 6z of the operation lever device 6c.

A load pressure detection passage 35a for detecting the load pressure of the actuator 5a and a load pressure detection passage 35b for detecting the load pressure of the actuator 5c are arranged. The load pressure detection passages 35a and 35b are guided to a shuttle valve 37. ing.

The shuttle valve 37 is connected to the load pressure detection passage 35
actuators 5a, 5 transmitted by a, 35b
The higher pressure among the load pressures of c is selected and output to the load pressure detection passage 35, and this pressure is guided to the second pressure receiving portion 36 of the pressure control valve 81 as in the second embodiment. .

The hydraulic oil discharged from the hydraulic pump 2 is guided to the supply port of the direction switching valve 4c via the discharge passage 2a and the check valve 23c.
When the pilot pressure is generated in the pilot passage 65 or 66, the direction switching valve 4c is switched by the pilot pressure, and the flow rate and the flow direction of the pressure oil supplied to the actuator 5c are controlled.

The combined operation of the actuators 5a, 5b, 5c according to the present embodiment configured as described above will be described.

Actuator 5a and actuator 5b
Operation and actuator 5c and actuator 5
The composite operation of b is the same as in the second embodiment.

Assume that the actuators 5a and 5c are operated in a combined manner by the operation lever devices 6a and 6c. In this state, when the operation lever 6y of the operation lever device 6b on the side of the actuator 5b is operated to switch the direction switching valve 4b, the variable throttle valve 71 is also switched in conjunction with this operation, and
The opening degree corresponds to the operation amount of the operation lever 6y.

On the other hand, the higher one of the load pressures of the actuators 5 a and 5 c is transmitted to the load pressure detection passage 35, and the first pressure receiving portion 34 on the valve opening side of the pressure control valve 81 is located downstream of the variable throttle valve 71. Of the second pressure receiving portion 36 on the valve closing side.
The pressure of the load pressure detection passage 35 is led to the pressure control valve 8.
Reference numeral 1 denotes a differential pressure between the variable throttle valve 71 and the supply pressure of the direction switching valve 4a (discharge pressure of the hydraulic pump 2) and the actuator 5
Since the pressure is controlled so as to be equal to the pressure difference between the load pressure on the high pressure side of the hydraulic pump 2 and the flow pressure of the hydraulic oil supplied to the actuators 5a and 5c and the opening of the variable throttle valve 71, It will be distributed to the flow rate determined by the degree.

The flow distribution control by the combination of the variable throttle valve 71 and the pressure control valve 81 is performed by the actuator 5
a, 5c and the actuator 5b are obtained irrespective of the magnitude of the load pressure. When the load pressure of the actuator 5a or 5c is high and the load pressure of the actuator 5b is low, the operation is also performed during the combined operation of the actuators 5a, 5c and the actuator 5b. The flow rate according to the operation amount of the operation lever 6y of the lever device 6b can be supplied to the actuator 5b, and the actuator 5b can be driven.

Therefore, in the present embodiment configured as described above, the same effect as that of the second embodiment can be obtained even in the combined operation when there are a plurality of upstream actuators.

A fourth embodiment of the present invention will be described with reference to FIGS. In the figure, the same members as those shown in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 6, the present embodiment is provided with a variable throttle valve 71A for changing the opening degree by an electric signal, instead of the variable throttle valve 71 of the second embodiment.

The operation lever devices 6a and 6b have displacement sensors 10a and 10b for detecting the operation amounts of the operation levers 6x and 6y.
10b, detection signals of the displacement sensors 10a and 10b are guided to the controller 11, and the controller 11 performs a predetermined calculation process based on the signals, and
A current is output to the A electromagnetic operation unit 71a. Variable throttle valve 7
1A is switched by the current, and the flow rate of the pressure oil supplied from the parallel passage 22 to the direction switching valve 4b, that is, the actuator 5b is changed according to the switching state.

FIG. 7 shows the processing functions of the controller 11. The controller 11 includes operation units 11a, 11b, 11
c, 11d.

In the calculation section 11a, when the lever input value X1 is the value at the time of the fine operation and the half operation with respect to the lever input value X1 of the operation lever device 6a, the target opening area a1 is 0, and the lever input value X1 is The relationship between X1 and a1 is set so that the target opening area a1 increases when the value becomes larger than that, and the target opening area a1 of the variable throttle valve 71A is obtained from the lever input value X1 of the operation lever device 6a.

In the calculating section 11b, when the lever input value X2 of the operation lever device 6b is 0, the target opening area a2 is 0 when the lever input value X2 is 0. The relationship between X1 and a2 is set so that the target opening area a2 increases, and the variable throttle valve 7 is determined by the lever input value X2 of the operation lever device 6b.
A target opening area a2 of 1A is obtained.

The calculating section 11c selects the smaller one of the calculated target opening areas a1 and a2, and sets this as the target opening area a of the variable throttle valve 71A.

The relationship between the target opening area a and the target supply current A is set so that the target supply current A increases as the target opening area a increases with respect to the target opening area a. Target opening area a derived by
To calculate the target supply current A to the variable throttle valve 71A,
The variable throttle valve 71A is switched by the target supply current A.

The operation of the present embodiment configured as described above will be described.

When the operator operates the operating lever 6y of the operating lever device 6b alone, there is no lever input value X1 of the operating lever device 6a in the controller 11, so that the variable throttle valve 71A selected in the calculating section 11c.
Is the target opening area a1, that is, 0. Accordingly, no inflow pressure oil is generated from the parallel passage 22 to the direction switching valve 4b, and the center bypass passage 7 is supplied to the direction switching valve 4b.
Pressure oil is supplied only from the
The pressure oil supply is the same as that of a normal open center type directional control valve without 2.

When the operator simultaneously operates the operating levers 6x and 6y of the operating lever devices 6a and 6b, when the operating lever 6x of the operating lever device 6a is minutely operated or half-operated, the target opening in the calculating section 11a of the controller 11 is performed. The area a1 = 0 is calculated, and the controller 1
Variable throttle valve 71A selected by the first arithmetic unit 11c
Has a target opening area a of 0. Therefore, the inflow pressure oil from the parallel passage 22 is not generated to the direction switching valve 4b, and the pressure oil is supplied only from the center bypass passage 7, so that the tandem-connected direction switching valves 4a and 4b.
A composite operation which maintains the priority supply order of the pressure oil is possible.

The operation lever 6 of the operation lever device 6a
When x is a full operation or an operation close to the full operation, the target opening area a
A value corresponding to X1 other than 0 is calculated as 1 and the calculation unit 1
At 1b, a value corresponding to X2 is calculated as the target opening area a2, and the smaller value of the calculation units 11a and 11b is selected as the target opening area a by the calculation unit 11c of the controller 11. In this case, since the value of the target opening area a is not 0, the parallel passage 22 is connected to the direction switching valve 4b.
Pressure oil supply from the center bypass passage 7 and the pressure oil supply from the center bypass passage 7, especially the operation lever 6x of the operation lever device 6a.
During the full operation, the supply of pressure oil from the center bypass passage 7 to the direction switching valve 4b is stopped, but the inflow pressure oil from the parallel passage 22 is generated. At this time, the pressure control valve 81 operates in the same manner as in the second embodiment, and the discharge flow rate of the hydraulic pump 2 is controlled by the variable throttle valve 71A.
Is distributed according to the degree of opening of the meter-in variable throttle of the direction switching valve 4a, so that there is no problem that pressure oil is not supplied to one of the actuators during the combined operation.

The above-described variable throttle valve 71A and pressure control valve 81
Distribution control by the combination of
a and 5b are obtained irrespective of the magnitude of the load pressure, and the load pressure of the actuator 5a is high.
In the combined operation of the actuators 5a and 5b when the load pressure is low, the flow rate according to the operation amount of the operation lever 6y of the operation lever device 6b can be supplied to the actuator 5b,
The actuator 5b can be driven.

As described above, also in this embodiment, the load pressure of the actuator 5a related to the upstream direction switching valve 4a is high, and the load pressure of the actuator 5b related to the downstream direction switching valve 4b is low. Also, the hydraulic oil discharged from the hydraulic pump 2 can be distributed so that the target supply flow rates of the actuators 5a and 5b can be secured by the inputs of the operation levers 6x and 6y, and each of the actuators 5a and 5b can be distributed according to the operation situation requested by the operator. , 5b can be secured.

As described above, several embodiments of the present invention have been described. However, these embodiments can be variously changed and modified within the spirit of the present invention. For example, in the above embodiment, the parallel passage 22 is connected to the check valve 23b of the direction switching valve 4b.
However, it may be connected to the upstream side of the check valve 23b. Even in this case, when the operation lever 6y of the operation lever device 6b is operated with respect to the direction switching valve 4b, the center bypass port of the direction switching valve 4b is closed or the opening degree becomes small. It is possible to control the distribution of the discharge flow rate of the hydraulic pump 2 during the combined operation of 5a and 5b. When this modification is adopted in the embodiment of FIG. 1, even when the actuator 5a is operated alone, the differential pressure across the meter-in variable throttle of the direction switching valve 4a is maintained at the set value of the spring 25, and the direction switching valve 4a Has the effect that pressure compensation control can be performed.

[0085]

According to the present invention, even when the load pressure of the actuator related to the directional control valve on the upstream side is high and the load pressure of the actuator related to the directional control valve on the downstream side is low, the combined operation of the actuators is possible. Sometimes, the flow rate of the pressure oil to be supplied to each actuator can be secured according to the operation situation requested by the operator.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic drive device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of a pressure control valve 8 shown in FIG.

FIG. 3 is a hydraulic circuit diagram of a hydraulic drive device according to a second embodiment of the present invention.

FIG. 4 is a view showing an example of an opening degree characteristic of the variable throttle valve shown in FIG. 3;

FIG. 5 is a hydraulic circuit diagram of a hydraulic drive device according to a third embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram of a hydraulic drive device according to a fourth embodiment of the present invention.

FIG. 7 is a functional block diagram illustrating processing functions of a controller illustrated in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Variable displacement hydraulic pump 2a Discharge passage 3 Fixed displacement hydraulic pump 3a Discharge passage 4a, 4b, 4c Direction switching valve 5a, 5b, 5c Hydraulic actuator 6a, 6b, 6c Operating lever device 6x, 6y, 6z Operation lever 7 Center bypass passage 8 Pressure control valve 10a, 10b Displacement sensor 11 Controller 11a, 11b, 11c Operation unit 22 Parallel passage 23a, 23b Check valve 24 Valve body 25 Spring 26 Supply pressure detection passage 27 First pressure receiving unit 28 Load Pressure detection passage 29 Second pressure receiving portion 30 Pilot pressure detection passage 25, 37 Shuttle valve 61, 62, 63, 64, 65, 66 Pilot passage 71, 71A Variable throttle valve 81 Pressure control valve

Continued on front page F-term (reference) 2D003 AA01 AC06 BA01 BB02 CA07 CA08 DA03 DB02 3H089 AA25 AA73 AA74 AA76 BB15 BB19 CC11 DA03 DA13 DB02 DB13 DB37 DB47 DB49 DB54 EE22 FF02 FF16 GG02 JJ01

Claims (4)

[Claims] 1. A variable displacement hydraulic pump, a plurality of actuators driven by pressure oil discharged from the variable displacement hydraulic pump, and a flow of pressure oil supplied from the variable displacement hydraulic pump to the plurality of actuators. Control,
A multiple direction switching valve having a center bypass passage, a direction branching from a discharge passage of the variable displacement hydraulic pump, and a direction switching valve located at an upstream side and a downstream direction located at a center bypass passage of the multiple direction switching valve. A hydraulic drive device having a parallel passage that connects the switching valve in parallel with the switching passage, wherein a flow rate passing through the parallel passage is controlled on the parallel passage in accordance with an operation amount of an operation lever that operates the downstream direction switching valve. A hydraulic drive device provided with an auxiliary control valve that performs the operation. 2. The hydraulic drive device according to claim 1, wherein the auxiliary control valve is configured to control a supply pressure of the upstream directional switching valve in a valve opening direction, and to control an actuator associated with the upstream directional switching valve. A pressure for controlling the supply pressure such that the load pressure is guided in the valve closing direction and the differential pressure between the supply pressure and the load pressure decreases as the operation amount of the operation lever of the downstream direction switching valve increases. A hydraulic drive device, being a control valve. 3. The hydraulic drive device according to claim 1, wherein the auxiliary control valve is a variable throttle valve whose throttle amount is adjusted in accordance with an operation amount of an operation lever of the downstream direction switching valve. The pressure on the downstream side of the throttle valve is guided in the valve opening direction, the load pressure of the actuator relating to the upstream direction switching valve is guided in the valve closing direction, and the pressure on the downstream side of the variable throttle valve is referred to as the load pressure. A hydraulic drive device comprising: a pressure control valve that controls the pressure to be the same. 4. The hydraulic drive device according to claim 2, wherein a plurality of said direction switching valves on the upstream side are provided, and means for detecting a maximum load pressure of a plurality of actuators associated with the plurality of direction switching valves is provided. A hydraulic drive device wherein the load pressure guided in the valve closing direction of the pressure control valve is its maximum load pressure.