JP2002031103A - Directional selector valve having flow dividing compensation, and hydraulic circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control valve having the flow dividing compensation on a return passage in a directional selector valve having the flow dividing compensation which can prevent the flow-out of the pressure oil from a detection passage of the maximum signal pressure, and simplify and miniaturize a valve structure. SOLUTION: A pair of load check valves are disposed on a pair of actuator passages 11 and 12, and a pair of normal-close type control valves 21a and 21b are disposed on return passages 11 and 12 for connecting actuators 6 and 7 to a tank 5 not via the directional selector valve 8. Signal passages 15a and 15b for detecting the downstream pressure of meter-in variable restrictions 9a and 9b of the directional selector valve as the signal pressure on the upstream side of the load check valves and check valves 24a and 23b having springs for detecting the signal pressure as the maximum signal pressure when the signal pressure is higher than the maximum signal pressure are provided. The pressure of the signal passages 15a and 15b is applied to the valve- opening direction of the control valves, and the maximum signal pressure and the force of the springs 23a and 23b are applied to the valve-opening direction of the control valves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional control valve device provided in a hydraulic device such as a hydraulic shovel or a hydraulic crane, and more particularly to a diverter having a pair of control valves on a return passage from each actuator to a tank. The present invention relates to a direction switching valve device with compensation and a hydraulic circuit device.

[0002]

2. Description of the Related Art In order to supply hydraulic pressure discharged from a hydraulic pump to a hydraulic actuator, a plurality of directional control valves are connected in parallel to a discharge path of the hydraulic pump, and the directional control valves are connected to the hydraulic oil from the actuator. May be connected to the tank so as to be able to be discharged, and the plurality of direction switching valves may be switched. However, when a plurality of directional control valves are connected in parallel as described above, in a combined drive in which a plurality of actuators are simultaneously driven, the pump discharge flow rate is supplied to the low-load-side actuator with preferential hydraulic pressure, and the high-load-side actuator is Driving is no longer compensated.

To solve this problem, for example, Japanese Patent Application Laid-Open Nos. 4-185903 and 11-20
As described in, for example, Japanese Patent Application Publication No. 1104, a direction switching valve device in which a pair of control valves are disposed on a meter-out passage (return passage) from an actuator to a tank has been proposed. The pair of control valves control the downstream pressure of the meter-in throttle of the directional control valve related to the low-pressure side actuator by the control valve on the low pressure side by the control valve on the meter-out side to be approximately equal to the load pressure of the high pressure side actuator during the combined driving, The control valve has a shunt function, and the shunt function of the control valve can smoothly perform the combined driving.

In the prior art described in Japanese Patent Application Laid-Open No. 4-185903, the directional control valve is disposed downstream of the load check valve on the meter-in side for supplying pressure oil to the actuator. The downstream side is connected to a detection path for the maximum load pressure (highest signal pressure) via a check valve, and a drain passage connected to the tank via a throttle is formed in the detection path for the maximum load pressure. For this reason, when an external force acts on the actuator while the directional control valve is switched, or when the discharge pressure of the hydraulic pump does not reach the drive pressure level of the actuator, the pressure oil from the actuator through the drain passage is discharged from the actuator. The outflow cannot be prevented, resulting in a problem that the operation of the actuator is deteriorated and the workability and safety of the working machine driven by the actuator are deteriorated.

On the other hand, in the prior art described in Japanese Patent Application Laid-Open No. 11-201104, a pair of control valves are provided on the upstream side of the meter-out throttle of the directional control valve, that is, on a pair of actuator passages connecting the directional control valve to the actuator. A valve is arranged, and the control valve of the pair of control valves, on the side where the actuator passage becomes the meter-in flow path, functions as a load check valve, and the control valve on the side of the actuator passage, which becomes the meter-out flow path, functions as a branch control valve. In addition to the configuration, the downstream pressure of the meter-in throttle is detected as a signal pressure at a position upstream of the control valve functioning as a load check valve, and the detected pressure is guided to a detection path of a maximum load pressure (a maximum signal pressure). Therefore, it is possible to prevent the hydraulic oil from flowing out of the actuator through the detection path and the drain path of the maximum signal pressure.

[0006]

As described above, Japanese Unexamined Patent Application Publication No.
In the directional control valve device described in Japanese Patent Application Laid-Open No. 185903 and Japanese Patent Application Laid-Open No. 11-201104, combined driving can be smoothly performed by a flow dividing function of a control valve disposed on a meter-out passage (return passage). Kaihei 11
In the directional switching valve device described in Japanese Patent Application Laid-Open No. 201101104, it is possible to prevent the pressure oil from flowing out from the detection path of the maximum signal pressure, and to improve workability
Safety can be ensured.

However, in any of the above-mentioned prior arts, a control valve for controlling a flow dividing is arranged on a meter-out passage connected from an actuator to a tank via a meter-out throttle of a direction switching valve. As a result, two throttle elements, ie, a control valve and a meter-out throttle of the directional control valve, are located in the meter-out passage, and there is a problem that the valve structure becomes complicated and large.

SUMMARY OF THE INVENTION An object of the present invention is to dispose a control valve having a flow dividing function on a return passage, so that pressure oil can be prevented from flowing out from a detection passage having the highest signal pressure, and the valve structure can be simplified and downsized. An object of the present invention is to provide a directional switching valve device and a hydraulic circuit device with shunt compensation.

[0009]

(1) In order to achieve the above object, the present invention provides a directional switching valve with a shunt compensation having a directional switching valve arranged to connect between a hydraulic pump and an actuator. In the apparatus, a pair of load check valves disposed on a pair of actuator passages connecting the directional control valve to the actuator, and a pair of return passages connecting the actuator and the tank without passing through the directional control valve. A pair of normally closed control valves disposed on the pair of return passages, wherein a first control pressure is applied in a valve opening direction and a second control pressure and a spring force are applied in a valve closing direction; First detection means for detecting, as a signal pressure, a downstream pressure of a pair of meter-in variable throttles of the direction switching valve at a position upstream of the load check valve;
The first signal detecting means is provided between the first detecting means and the detection path of the highest signal pressure, and when the signal pressure detected by the first detecting means is higher than the signal pressure of the detecting path of the highest signal pressure, the signal pressure is raised to the highest signal pressure. And a signal pressure detected by the first detection means as the first control pressure only in a control valve of the pair of control valves, which is a meter-out side when the direction switching valve is operated, among the pair of control valves. A first signal transmitting unit that guides, and a second signal transmitting unit that guides the maximum signal pressure detected by the second detecting unit as the second control pressure to each of the pair of control valves.

Thus, the pair of load check valves, the return passage, the pair of control valves, the first detecting means, the second detecting means, the first signal transmitting means and the second signal transmitting means are provided, and when the direction switching valve is operated. The signal pressure detected by the first detection means is guided to the control valve on the meter-out side as the first control pressure in the valve opening direction, and the second detection pressure is supplied to each of the pair of control valves as the second control pressure in the valve closing direction. By guiding the detected maximum signal pressure, the pair of control valves allows the control valve on the meter-out side to output the maximum signal pressure (the high-pressure side) (Downstream pressure of the meter-in throttle of the directional control valve associated with the actuator), thereby exerting a branching function.

Further, the first signal transmission means is configured to guide the first control pressure in the valve opening direction only to the control valve on the meter-out side, so that the control valve on the meter-in side is kept closed by at least a spring. Therefore, even if the return passage is connected to the tank without passing through the direction switching valve and the control valve is installed on this return passage, pressure oil flows out of the actuator through the return passage to the tank through the return passage. There is no. The first detecting means detects the downstream pressure of the pair of meter-in variable throttles of the direction switching valve as a signal pressure at a position on the upstream side of the pair of load check valves. The outflow of pressurized oil can also be prevented.

Further, in the prior art, a control valve for diverting control is arranged on a meter-out passage connected to a tank from an actuator via a meter-out throttle of a direction switching valve. In this case, two throttle elements, ie, a control valve and a meter-out throttle of a directional control valve, are located, and the valve structure is complicated and large.
However, as a result of the study by the present inventor, since the flow area of the meter-out passage is adjusted by the control valve, the meter-out restriction of the directional control valve at this time is only a part of the pressure drop in the passage. It has been found that there is no practical role, that is, in this type of directional control valve, a configuration having a meter-in throttle is necessary and sufficient.

According to the present invention, when the directional control valve is returned to the neutral position and the actuator is stopped, the control valve on the meter-out side restricts the flow passage area of the return passage to exhibit the meter-out flow control function. Since the return passage does not pass through the directional control valve, the directional control valve does not have a meter-out restrictor, so that the valve structure can be simplified and downsized.

(2) In the above (1), preferably,
The detection path for the highest signal pressure is connected to a tank via a drain passage provided with a throttle, and the second detection means is configured to output the highest signal from a signal path to which the signal pressure detected by the first detection means is led. A check valve mechanism that is connected to the pressure detection path only so as to be openable and that also functions as pressure generating means, wherein an open differential pressure of the check valve mechanism is set to a value larger than an open differential pressure of the control valve. ing.

As a result, the control valve on the meter-out side when the directional control valve is operated alone (or on the highest load driving side in the combined operation) is always fully opened, and the control valve on the meter-out side is more than necessary. Pressure loss can be prevented from increasing.

(3) In the above (1), preferably, the second detecting means is built in the pair of control valves, and each of the control valves shuts off the flow path of the return passage. A control position in the valve opening direction controlled by the first control pressure, having a minimum stroke position, a maximum stroke position for fully opening the flow path of the return passage, and an intermediate stroke position for variably narrowing the flow path of the return passage. And the second
A valve whose stroke is adjusted by a control pressure and a control force in a valve closing direction by a spring; and wherein the second detecting means detects a signal pressure detected by the first detecting means at a minimum stroke position of the control valve. Block the path and the detection path of the maximum signal pressure, and communicate the detection path of the signal pressure and the detection path of the maximum signal pressure at the maximum stroke position of the control valve, and at the intermediate stroke position of the control valve, The detection path for the signal pressure and the detection path for the highest signal pressure are shut off.

Thus, the control valve on the meter-out side can detect the signal pressure detected by the first detecting means at the maximum stroke position as the highest signal pressure, and the second detecting means is built in the control valve, so that the highest signal The configuration of the pressure detection path can be simplified.

(4) In the above (3), preferably,
The detection path of the maximum signal pressure is connected to the tank via a drain passage provided with a restriction, and the control valve restricts the detection path of the signal pressure and the detection path of the maximum signal pressure at the maximum stroke position. The throttle that operates at the maximum stroke position of the control valve is set such that the control force of the control valve in the valve opening direction is greater than the control force of the control valve in the valve closing direction.

As a result, the control valve on the meter-out flow path side when the directional control valve is operated alone (or on the highest load drive side during combined operation) is always switched to the maximum stroke position (fully open state), and that state is maintained. It is possible to prevent an unnecessary increase in pressure loss due to the control valve on the meter-out side.

(5) To achieve the above object,
The present invention provides a hydraulic circuit device having a plurality of directional switching valves arranged to connect between a hydraulic pump and a plurality of actuators, respectively, wherein each of the plurality of directional switching valves corresponds to the plurality of actuators. A pair of load check valves disposed on a pair of actuator passages connected to the actuator, a pair of return passages connecting each of the plurality of actuators and the tank without passing through the plurality of direction switching valves, And a pair of normally closed type in which a first control pressure is applied in a valve opening direction and a second control pressure and a spring force are applied in a valve closing direction. A control valve, provided at each of the plurality of directional control valves, the directional control valve at a position upstream of the pair of load check valves; A first detecting means for detecting a downstream pressure of the pair of meter-in variable throttles as a signal pressure; and a first detecting means provided between the first detecting means and a detecting path of the highest signal pressure corresponding to each of the plurality of directional control valves. A second detecting means for detecting when the signal pressure detected by the first detecting means is higher than the signal pressure of the detection path of the highest signal pressure as the highest signal pressure; and A first control pressure for guiding the signal pressure detected by the first detection means as the first control pressure only to the control valve which is on the meter-out side when the direction switching valve is operated, of the pair of control valves; A second signal which is provided corresponding to each of the plurality of direction switching valves and guides the highest signal pressure detected by the second detection means as the second control pressure to each of the pair of control valves. Transmission means And things.

Thus, as described in the above (1), the control valve having the flow dividing function is arranged on the return passage, so that the pressure oil can be prevented from flowing out from the detection passage of the maximum signal pressure, and the valve structure is reduced. It can be simplified and downsized.

[0022]

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

FIG. 1 is a hydraulic circuit diagram showing a hydraulic circuit device provided with a directional control valve device with a flow dividing according to a first embodiment of the present invention.

In FIG. 1, reference numerals 70 and 71 denote directional switching valve devices with branching compensation according to the present embodiment. These directional switching valve devices 70 and 71 are respectively provided with parallel oil from the discharge passage 3 of one of the hydraulic pumps. Directional switching valve 8, connected to paths 4 and 4,
The directional control valves 8 and 8 are connected to actuators (hydraulic cylinders) 6 and 7 via a pair of actuator passages 11 and 12, respectively. The direction switching valve devices 70 and 71 are respectively connected to the actuator passages 11 and
12 having return passages 10a and 10b branching from
These return passages 10a, 10b bypass the respective directional control valves 8, 8, and are connected to the tank 5 via a common tank line 10.

The direction switching valve device 70 includes a pair of load check valves 1 disposed on the actuator passages 11 and 12.
4a, 14b, and the load check valves 14a, 1
Reference numeral 4b is connected to the downstream side of the meter-in throttles 9a, 9b of the direction switching valve 8 via the flow paths 13a, 13b. The return passages 10a and 10b are connected to the actuator passage 1 downstream of the load check valves 14a and 14b.
1 and 12 and return paths 10a and 10b
Above is a pair of pressure control valves (hereinafter simply referred to as control valves) 2
1a and 21b are arranged.

The directional control valve 8 is connected to signal paths 16a and 16b for detecting the pressure downstream of the meter-in throttles 9a and 9b at the time of the switching operation, and to drain oil paths 18a and 18b when the operation of the directional control valve 8 is neutral. Signal paths 17a, 17
b, and the drain oil passages 18 a and 18 b are connected to the tank 5. When the directional control valve 8 is switched, the pressure downstream of the meter-in throttles 9a and 9b is
Or 7 as a signal pressure corresponding to the load pressure of signal path 16a or 1
6b, the tank pressure is guided to the signal path 15b or 15a by the signal paths 17a, 17b when the operation of the directional control valve 8 is neutral.

The signal paths 15a, 15b are
5a, 25b are connected to the maximum signal pressure detection path 30 via check valves 24a, 24b.
The check valves 24a and 24b are connected to the detection path 30 so as to be openable.
, The highest signal pressure is detected. The detection path 30 is connected to the tank 5 via a drain passage 30c having a throttle 31.

The maximum signal pressure detected by the detection path 30 is guided to the displacement control unit 2 of the hydraulic pump 1, and the displacement control unit 2 changes the discharge pressure of the hydraulic pump 1 to the maximum signal pressure (≒ the maximum load pressure). Hydraulic pump 1 so that it becomes higher by a certain pressure than
The variable displacement control, which is generally called load sensing control, is performed to control the discharge displacement. Further, the maximum signal pressure detected in the detection path 30 is also guided to an unload valve 72 connected to the discharge path 3 of the hydraulic pump 1, and the direction switching valves 8, 8
When the operation is neutral, the discharge pressure of the hydraulic pump 1 is set to the unload state. Further, the maximum signal pressure relating to the load sensing control of the hydraulic pump 1 is brought into the unload state when the operation of each of the directional control valves 8 is neutralized by the drain passage 30c.

The pair of control valves 21a, 21b provided on the pair of return passages 10a, 10b are of a normally closed type, and signal paths 15a, 15b are provided to the pressure receiving portions of the control valves 21a, 21b in the valve opening direction. Are connected to the first signal paths 22a and 22b, a control force is applied in the valve opening direction, and a second signal path connected to the detection path 30 to the pressure receiving portion of the control valves 21a and 21b in the valve closing direction. The control valves 30a and 30b are connected, and a control force in the valve closing direction is applied together with the springs 23a and 23b. The stroke of the control valves 21a and 21b is adjusted by the control force in the valve opening direction and the control force in the valve closing direction. , The position is switched.

The springs 25a of the check valves 24a, 24b,
The pretension of 25b is controlled by the spring 23 of the control valves 21a and 21b.
It is set so as to be larger than the pretension of a and 23b. As a result, the check valves 24a and 24b also function as pressure generating means for setting the open differential pressure of the check valves 24a and 24b to a value larger than the open differential pressure of the control valves 21a and 21b, and the control valves 21a and 21b are normally closed. Even if the maximum signal pressure acts in the valve closing direction, the control valves 21a and 21b are surely opened when the signal pressure is led to the first signal paths 22a and 22b, and the meter-out side is closed. The control valves 21a and 21b can prevent an unnecessary increase in pressure loss.

The direction switching valve device 71 is also a direction switching valve device 70.
It is configured similarly to.

The operation of the directional control valve devices 70 and 71 of the present embodiment configured as described above will be described.

When the directional control valves 8 and 8 are at the neutral position in the drawing and none of the actuators 6 and 7 are driven, the pressure in the maximum signal pressure detecting path 30 is changed to the drain path 30.
c, the tank pressure is reached. For this reason, the discharge flow rate of the hydraulic pump 1 is controlled to the minimum flow rate (minimum tilt) by the regulator 2, and the discharge pressure of the hydraulic pump 1 is higher than the tank pressure by the unload valve 72 by the unload set differential pressure. The pressure is controlled. The control valves 21a and 21b are provided with springs 23a and 23b.
, And performs a load holding function together with the load check valves 14a and 14b.

From such a state, for example, when the directional control valve 8 of the directional control valve device 70 is switched to the right in the drawing in order to drive the actuator 6 alone in the extension direction,
The discharge oil of the hydraulic pump 1 is guided to the flow path 13a through the parallel oil passage 4, the meter-in throttle 9a of the direction switching valve 8, and the downstream pressure of the meter-in throttle 9a is transmitted to the signal line 15b through the signal line 16a. And the direction switching valve device 70
A circuit is formed in which the actuator passage 11 is on the meter-in side and the actuator passage 12 is on the meter-out side.

The return path 10 is connected to the signal path 15b.
b, the signal path 22b of the control valve 21b is connected, so that the downstream pressure of the meter-in throttle 9a guided to the signal path 15b is guided as a signal pressure in the valve opening direction of the control valve 21b, and is also transmitted to the signal path 15b. The introduced downstream pressure of the meter-in throttle 9a opens the check valve 24b pre-tensioned by a spring 25b, and the tank 5 through the maximum signal pressure detection path 30 and the throttle 31.
Is formed, the pressure of the signal path 15b (downstream pressure of the meter-in throttle 9a) is reduced by the pressure conversion value of the pretension of the spring 25b, and the reduced pressure is applied to the detection path 30 by the maximum signal pressure. And the highest signal pressure is guided as the signal pressure in the valve closing direction of the control valve 21b.

Here, as described above, the check valve 24b
Of the spring 23b of the control valve 21b is set larger than the pretension of the spring 23b of the control valve 21b.
And the pre-tension setting of the spring 25b, the control valve 21b is configured such that the maximum signal pressure acts in the valve closing direction.
When the signal pressure is guided to the first signal path 22b, the valve is opened, and a circuit is formed that is connected from the meter-out side actuator passage 12 to the tank 5 via the return passage 10b and the tank line 10.

At the same time, the maximum signal pressure is guided to the tilt control device 2 of the hydraulic pump 1 and the unload valve 72 via the detection path 30, and the discharge pressure of the hydraulic pump 1 starts to increase.

Here, at the beginning of the switching operation of the direction switching valve 8, the discharge pressure of the hydraulic pump 1 is at the minimum pressure as described above, and is not at a pressure at which the actuator 6 can be driven. Therefore, the load check valve 14a remains closed.

As described above, when the discharge pressure of the hydraulic pump 1 starts to increase, the increased discharge pressure of the hydraulic pump 1 is again guided to the signal paths 16a and 15b, and further to the detection path via the check valve 24b. At 30, the signal pressure is detected as the maximum signal pressure, and the discharge pressure of the hydraulic pump 1 further increases. This is repeated, and when the discharge pressure of the hydraulic pump 1 rises to a pressure sufficient to drive the actuator 6 to extend, the load check valve 14a is opened to allow the actuator 6 to perform the intended extension drive.

In the other control valve 21a, even if the directional control valve 8 is operated, the signal pressure is not guided to the signal path 15a and the maximum signal pressure is guided via the signal path 30a. , The control valve 21a keeps the valve closed state.

For example, when the directional control valve 8 of the directional control valve device 70 is switched to the left in the drawing in order to drive the actuator 6 alone in the contraction direction, the discharge oil of the hydraulic pump 1 Meter-in throttle 9 for directional control valve 8
b to the flow path 13b, the downstream pressure of the meter-in throttle 9b is guided to the signal path 15a via the signal path 16b, the actuator passage 12 of the direction switching valve device 70 is connected to the meter-in side, and the actuator passage 11 is connected to the A circuit on the meter-out side is configured.

The return path 10 is connected to the signal path 15a.
Since the signal path 22a of the control valve 21a on a is connected, the downstream pressure of the meter-in throttle 9b guided to the signal path 15a is guided as a signal pressure in the valve opening direction of the control valve 21a, and is also transmitted to the signal path 15a. The introduced downstream pressure of the meter-in throttle 9b opens the check valve 24a pretensioned by a spring 25a, and the tank 5 is connected via the maximum signal pressure detection path 30 and the throttle 31.
Is formed, the pressure in the signal path 15a (downstream pressure of the meter-in throttle 9b) is reduced by the pressure converted value of the pretension of the spring 25a, and the reduced pressure is applied to the detection path 30 by the maximum signal pressure. And the maximum signal pressure is guided as the signal pressure in the valve closing direction of the control valve 21a.

Here, as described above, the check valve 24a
Of the spring 25a of the control valve 21a is set larger than the pretension of the spring 23a of the control valve 21a.
Even if the control valve 21a is configured so that the maximum signal pressure acts in the valve closing direction due to the setting relationship of the pretension of the spring 25a and the spring 25a,
When the signal pressure is led to the first signal path 22a, the valve is opened, and a circuit is formed that is connected from the meter-out side actuator passage 11 to the tank 5 via the return passage 10a and the tank line 10.

At the same time, the maximum signal pressure is guided to the tilt control device 2 of the hydraulic pump 1 and the unload valve 72 via the detection path 30, and the discharge pressure of the hydraulic pump 1 starts to increase.

Accordingly, similarly to the above, when the discharge pressure of the hydraulic pump 1 does not reach a pressure sufficient to drive the actuator 6 to contract, the load check valve 14b is closed and the discharge pressure of the hydraulic pump 1 is reduced. When the pressure rises to a value sufficient to drive the actuator 6, the load check valve 14b is opened, and the intended contraction drive of the actuator 6 can be performed.

As described above, the control valve 21a (or 21b) which is arranged on the meter-out side at the time of the single operation (or the highest load driving side at the time of the composite operation) is provided with the spring 23 of this control valve.
a (or 23b) and the spring 25a (or 25b)
Is fully open due to the above pre-tension setting relationship with
It is possible to prevent an unnecessary increase in pressure loss on the meter-out side.

Next, for example, in order to perform a combined drive, the directional control valve 8 of the directional control valve device 71 is operated to further drive the actuator 7 in the extending direction from the operating state of the actuator 6 alone in the extending direction, for example. And At this time,
If the load pressure of the actuator 7 is
Above the load pressure.

The switching operation of the direction switching valve 8 corresponding to the driving of the actuator 7 in the extension direction constitutes a circuit in which the actuator passage 11 of the direction switching valve device 71 is on the meter-in side and the actuator passage 12 is on the meter-out side. , The control valve 2 in conjunction with this switching operation.
The connection of each signal path 1a is made in the same manner as in the case of the above-described direction switching valve device 70, and the connection from the actuator passage 12 on the meter-out side to the return passage 10b, the tank line 1
A circuit is formed that is connected to the tank 5 via 0.

As described above, the hydraulic pump 1 has a discharge pressure based on the load pressure of the actuator 6 which is on the low load side. Therefore, the load check valve 14a on the actuator 7 side operates immediately after the start of the composite operation. It cannot be opened, so the flow path 1 downstream of the meter-in throttle 9a of the direction switching valve 8
The discharge oil of the hydraulic pump 1 is directly guided to 3a,
a rises to the discharge pressure of the hydraulic pump 1, and this pressure is also guided to the detection path 30 through the signal path 16a, the signal path 15b, and the detection check valve 24b, so that the maximum signal pressure rises. For the first time, the displacement control of the hydraulic pump 1 by the load sensing control is readjusted.

At the same time, the signal path 30 connected to the pressure-receiving portion for operating the control valve 21b in the valve closing direction on the return path 10b on the meter-out side of the actuator 6 on the low load side.
b, the increased maximum signal pressure is guided via the signal path 30b connected to the detection path 30, so that the return path 1
The return oil from 0b is throttled by the control valve 21b, and is controlled to rise so that the load pressure of the actuator 6 on the low load side becomes substantially equal to the maximum signal pressure. Then, the discharge pressure of the hydraulic pump 1 increases to the drive pressure level of the actuator 7 on the high load side.

When the discharge pressure of the hydraulic pump 1 rises in this way, the load check valve 14a of the direction switching valve device 71 is opened, and the intended extension drive of the actuator 7 can be performed.

The control valve 21b on the return passage 10b on the meter-out side of the directional control valve device 70 has a pressure on the downstream side of the meter-in throttle corresponding to the switching direction of the directional control valve 8, that is, the load pressure of the actuator 6. The discharge control is performed on the meter-out side so as to be approximately equal to the maximum load pressure, and thus the actuators 6 with different load pressures are controlled.
7, the pressure on the downstream side of the meter-in throttle 9a of the direction switching valve 8 of the direction switching valve device 70 is changed by the control valve 21b due to the restriction of the passage area from the low load side actuator 6 to the tank line by the control valve 21b. Since the pressure rises to the same level as the pressure on the downstream side of the meter-in throttle of the direction switching valve 8 of the valve device 71, the discharge flow rate of the hydraulic pump 1 is distributed according to the opening area ratio of the meter-in throttle of each of the direction switching valves 8, 8. be able to.

Further, when an inertial load acts during driving of the actuator 6 (or 7) or when the directional control valve 8 is returned to the neutral position to stop the actuator 6 (or 7), the actuator 6 (or 7) The pressure of the actuator passage 11 (or 12) and the passage 13a (or 13b) is reduced to near the tank pressure by the pump action, or the signal path 15b (or 15a) is changed to the signal path 17a (or 17b) in the directional control valve 8. And the signal line 15b (or 15a) becomes the tank pressure through the control valve 21b.
(Or 21a) is operated in the valve closing direction by the spring 23b (or 23a) to reduce the opening area of the return passage 10b (or 10a). As a result, a brake pressure is applied to the meter-out side actuator passage 11 (or 12), and the actuator 6 (or 7) can be decelerated and stopped. Further, if the opening / closing portion of the control valve 21b (or 21a) is configured as a variable throttle that variably changes the opening area according to the stroke similarly to the meter-out throttle of the conventional directional control valve, the control valve 21
b (or 21a) can have the same meter-out flow control function as the conventional meter-out throttle of the directional control valve, and the actuator 6 (or 7) can be smoothly decelerated and stopped.

As described above, according to the present embodiment, the pair of control valves 21a and 21b are arranged such that the meter-out control valve 21b is the meter-in throttle of the direction switching valve 8 related to the low-pressure side actuator 6 during combined driving. 9a is converted to the maximum signal pressure (the directional control valve 8 related to the high-pressure side actuator 7).
(Downstream pressure of the meter-in restrictor 9a) to achieve the flow dividing function.

Further, when an external force acts on the actuators 6, 7 or when the discharge pressure of the hydraulic pump 1 has not yet reached the driving pressure level of the actuators 6, 7 when the operation of the directional control valves 8, 8 is started. , Meter-in side control valve 21
a (or 21b) is held in a closed state by at least the spring 23a (or 23b), so that the return passages 10a and 10b are
Even if the control valves 21a and 21b are installed on the return passages 10a and 10b, the pressure oil flows out of the actuator 5 to the tank 5 from the actuator through the return passage 10a (or 10b). There is no. The signal paths 15a, 15b are located downstream of the meter-in throttles 9a, 9b and the load check valves 14a, 14b.
Since the pressure on the upstream side of 14b is detected as the signal pressure, the outflow of the pressure oil from the actuator side via the drain passage 30c connected to the maximum signal pressure detection path 30 can be prevented. Safety deterioration can be prevented.

The return passage 1 connects the actuators 6, 7 and the tank 5 without passing through the directional control valves 8, 8.
Since a pair of control valves 21a and 21b are arranged on 0a and 10b, and the control valves 21a and 21b are provided with a meter-out flow control function, a meter-out restrictor is eliminated from the directional control valves 8 and 8, and the valve structure is simplified. And miniaturization.

FIG. 2 shows the directional control valve device 7 of FIG.
It is a figure which shows an example of the valve structure of 0,71. The same parts as those shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

In FIG. 2, a first spool hole 101 is provided in the casing body 100, and a spool 111 of the directional control valve 8 is fitted into the first spool hole 101.

Further, pump ports 104a and 104b are formed in the first spool hole 101 of the casing body 100, and meter-in actuator ports 105a and 105b and drain ports 106a and 106b are formed outside thereof.
Are formed, and the signal pressure ports 107a, 107
b is formed, and the pump ports 104a and 104b are connected to the discharge path 3 of the hydraulic pump 1, and the drain port 106a
Is connected to the tank 5 (not shown) and the pump port 10
The 4a and the meter-in actuator port 105a and the pump port 104b and the meter-in actuator port 105b are communicated and blocked by meter-in throttle notches 120a and 120b formed on the land (large diameter) of the spool 111.

Further, oil holes 112 and 113 are formed in the spool 111 in the axial direction.
a, 112b, and 112c have fine holes 113 in the oil holes 113.
a, 113b, and 113c are formed in communication with each other. Of these, the fine holes 112a and 113a are respectively connected to the actuator ports 105a and 105b, and the fine holes 112b and
3b are the signal pressure ports 107b and 107a, respectively.
Further, the small holes 112c and 113c are respectively connected to and blocked from the drain ports 106a and 106b in accordance with the operation state of the spool 111.

The signal pressure port 107a is connected to the signal pressure port 107 via a check valve 24a having a spring 25a.
b is configured to be communicable with a detection hole 110 via a check valve 24b having a spring 25b, and the detection hole 110 is formed in the casing main body of another directional switching valve device from inside the casing main body 100. The through hole is connected to a similar detection hole to form a part of the maximum signal pressure detection path 30, and is connected to the tank 5 via a drain passage 30 c having a throttle 31.

Further, the casing body 100 includes actuator ports 202a, 202b and flow paths 13a, 13b which constitute a part of the actuator passages 11, 12,
Tank ports 203a and 203b, which form a part of the return passages 10a and 10b, and signal paths 22a and 22b are formed. The actuator ports 202a and 202b open on the outer surface of the casing body 100 and are connected to the actuator 6 by piping. , The flow paths 13a and 13b open to the meter-in actuator ports 105a and 105b, respectively. The tank ports 203a and 203b are connected to the tank 5 via the tank line 10, and the signal paths 22a and
Reference numeral 22b is open to the signal pressure ports 107a and 107b, respectively.

In the casing body 100, a pair of second spool holes 201 are formed in parallel with the first spool holes 101.
a, 201b, and the second spool hole 201
a, 201b, the valve body 210a of the control valve 21a, 21b,
210b is fitted, and the valve bodies 140a, 140b of the load check valves 14a, 14b are fitted between the spool 111 and the valve bodies 210a, 210b in parallel with these.

The valve body 1 of the load check valves 14a and 14b
40a, 140b are provided so as to communicate / block the inflow ports 108a, 108b and the outflow ports 109a, 109b, and the inflow ports 108a, 108b are connected to the flow paths 13a, 1b.
3b via meter-in actuator port 105
a, 105b and the outflow ports 109a, 109
b communicates with the actuator ports 202a and 202b.

The valve bodies 210a, 210 of the control valves 21a, 21b
10b is located across the actuator ports 202a, 202b and the tank ports 203a, 203b,
Restricted portions 211 are provided at the lands of the valve bodies 210a and 210b.
a, 211b are formed, and the throttle portions 211a, 211b are formed.
By b, the actuator port 202a communicates with the tank port 203a and the actuator port 202b communicates with the tank port 203b.

The valve body 210 of the control valves 21a and 21b
a and 210b are connected to the first pressure receiving chambers 204a and 204a, respectively.
04b and the second pressure receiving chambers 205a and 205b provided with the springs 23a and 23b.
04a and 204b are connected to signal pressure ports 107a and 107b via signal paths 22a and 22b, and the second pressure receiving chambers 205a and 205b are connected to the maximum signal pressure detection path 30 via signal paths 30a and 30b.

The operation of the embodiment shown in FIG. 2 will be described.

For example, when the spool 111 is in the illustrated neutral state, the signal pressure port 107b is
12, a drain port 106a through a pore 112c,
The signal pressure port 107a is connected to the drain port 106b through the small hole 113b, the oil hole 113, and the small hole 113c, and the tank pressure is led to the signal pressure ports 107a and 107b.

Therefore, the signal pressure at the time of neutrality can be set to the tank pressure, and the maximum signal pressure related to the load sensing control can be set to the unload state. Also, the control valves 21a, 21
b first pressure receiving chambers 204a, 204b, second pressure receiving chamber 205
a and 205b are supplied with the tank pressure.
a, 21b of the valve body 210a, 210b is provided with a spring 23a,
The control force in the valve closing direction by the valve port 23a is applied to the actuator ports 202a and 202b and the tank port 203.
a and 203b are shut off.

In such a state, for example, if a pilot pressure is input to drive the actuator 6 alone in the extension direction and the spool 111 switches the stroke to the right in the figure, the discharge oil of the hydraulic pump 1 1
04a, the meter-in actuator port 105a via the meter-in throttle notch portion 120a, the flow path 13a, and the inflow port 108a of the load check valve 14a.
In addition, the meter-in throttle notch portion 120 is provided through a fine hole 112a, an oil hole 112, and a fine hole 112b in the spool 111.
a is introduced to the signal pressure port 107b and the signal path 22b, the flow path 13a and the actuator port 202a which are a part of the actuator path 11 are on the meter-in side, and the actuator port 202b which is a part of the actuator path 12 is the A circuit on the meter-out side is configured.

The first pressure receiving chamber 204b of the control valve 21b is connected to the signal path 22b, and the downstream pressure of the meter-in throttle notch 120a led to the signal path 22b is used to open the valve body 210b of the control valve 21b. In addition to being guided as the signal pressure in the direction, the downstream pressure of the meter-in throttle notch portion 120a guided to the signal pressure port 107b opens the check valve 24b preloaded by the spring 25b, and the maximum signal pressure detection path 30,
The flow of the pressure oil reaching the tank 5 via the throttle 31 is formed, and the pressure of the signal pressure port 107b (the meter-in throttle 10
2a) is reduced by the pressure conversion value of the pretension of the spring 25b, and the reduced pressure is detected as the highest signal pressure in the detection path 30, and the highest signal pressure is detected by the second signal of the control valve 21b.
The pressure is guided to the pressure receiving chamber 205b as a signal pressure in the valve closing direction. As a result, the actuator 210 that has opened to the meter-out side due to the setting relationship of the pretension between the spring 23b and the spring 25b is opened even if the maximum signal pressure is applied in the valve closing direction to the valve body 210b of the control valve 21b. A circuit is formed from the port 202b to the tank 5 via the tank port 203b, which is a part of the return passage 10b, and the tank line 10.

At the same time, the maximum signal pressure is guided to the tilt control device 2 of the hydraulic pump 1 and the unload valve 72 via the detection path 30, and the discharge pressure of the hydraulic pump 1 starts to increase.

Here, at the beginning of the switching operation of the spool 111, the discharge pressure of the hydraulic pump 1 is at the minimum pressure and not at a pressure at which the actuator 6 can be driven. For this reason, the valve element 140a of the load check valve 14a remains closed.

When the discharge pressure of the hydraulic pump 1 starts to increase as described above, the increased discharge pressure of the hydraulic pump 1 is again conducted to the signal pressure port 107b through the fine holes 112a, the oil holes 112, and the fine holes 112b. Then, it is further detected as the highest signal pressure in the detection path 30 via the check valve 24b, and the discharge pressure of the hydraulic pump 1 further increases. This is repeated, and when the discharge pressure of the hydraulic pump 1 rises to a pressure sufficient to drive the actuator 6 to extend, the load check valve 14a
By opening the valve body 140a, the intended extension of the actuator 6 can be driven.

The valve body 210a of the other control valve 21a
, The signal path 22 is operated even when the spool 111 is operated.
Since the signal pressure is not led to a and the maximum signal pressure is led via the signal path 30a, the valve body 210a keeps the shut-off state between the actuator port 202a and the tank port 203a.

For example, if a pilot pressure is input to drive the actuator 6 alone in the contraction direction and the spool 111 switches the stroke to the left side in the drawing,
The discharge oil of the hydraulic pump 1 is guided to the meter-in actuator port 105b, the flow path 13b, the inflow port 108b of the load check valve 14b through the pump port 104b, the meter-in throttle notch 120b, and the pores 112b in the spool 111. The downstream pressure of the meter-in throttle notch portion 120b is guided to the signal pressure port 107a and the signal path 22a through the oil hole 113 and the small hole 113b, and the flow path 13b which is a part of the actuator path 12.
In addition, a circuit is configured in which the actuator port 202b is on the meter-in side and the actuator port 202a, which is a part of the actuator passage 11, is on the meter-out side.

The first pressure receiving chamber 204a of the control valve 21a is connected to the signal path 22a. The downstream pressure of the meter-in throttle notch 120b led to the signal path 22a is used to open the valve body 210a of the control valve 21a. In addition to being guided as the signal pressure in the direction, the downstream pressure of the meter-in throttle notch portion 120b guided to the signal pressure port 107a opens the check valve 24a pre-expanded by the spring 25a, and the maximum signal pressure detection path 30,
A pressure oil flow to the tank 5 via the throttle 31 is formed, and the pressure of the signal pressure port 107a (the meter-in throttle 10
2b) is reduced by the pressure conversion value of the pretension of the spring 25a, and the reduced pressure is detected as the highest signal pressure in the detection path 30, and the highest signal pressure is detected by the second valve of the control valve 21a.
It is guided to the pressure receiving chamber 205a as a signal pressure in the valve closing direction. As a result, due to the setting relationship of the pretension between the spring 23a and the spring 25a, the valve element 210a of the control valve 21a opens even if the maximum signal pressure is applied in the valve closing direction, and the actuator on the meter-out side is opened. A circuit is formed from the port 202a to the tank 5 via the tank port 203a, which is a part of the return passage 10a, and the tank line 10.

At the same time, the maximum signal pressure is guided to the tilt control device 2 of the hydraulic pump 1 and the unload valve 72 via the detection path 30, and the discharge pressure of the hydraulic pump 1 starts to increase.

Therefore, as described above, if the discharge pressure of the hydraulic pump 1 does not reach a pressure sufficient to drive the actuator 6 to contract, the valve element 140 of the load check valve 14b
b closes and when the discharge pressure of the hydraulic pump 1 rises to a pressure sufficient to drive the actuator 6 to contract.
By opening the valve body 140b of the load check valve 14b, the intended contraction drive of the actuator 6 can be performed.

Also in the case of the combined drive, the load check valve is provided in the direction switching valve devices 70 and 71 on the high load pressure side and the low load pressure side in accordance with the switching direction of the spool 111 as described with reference to FIG. 14a of valve body 140a or valve body 140b of load check valve 14b, control valve 21
b of the valve element 210b or the valve element 210a of the control valve 21a,
The check valve 24b or 24a operates, and the discharge flow rate of the hydraulic pump 1 can be distributed according to the opening area ratio of the meter-in throttle of the spool 111 of the direction switching valve devices 70 and 71.

As described above, according to the present embodiment, FIG.
The functions of the direction switching valve devices 70 and 71 shown in the hydraulic circuit diagram can be achieved, and the same effects as in the embodiment shown in FIG. 1 can be obtained. The spool 111 of the directional control valve 8 has no meter-out throttle, and the meter-in throttle notch 12
Since only the shafts 0a and 120b are formed, the axial length of the spool 111 can be shortened, the signal lines for the control valves 21a and 21b can be simplified, and the valve structure can be simplified and downsized.

FIG. 3 is a hydraulic circuit diagram showing a hydraulic circuit device having a directional control valve device according to a second embodiment of the present invention. The same components as those shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

In FIG. 3, the direction switching valve devices 70A and 71A according to the present embodiment are different from those shown in FIG.
Instead of providing the check valves 24a, 24b and the springs 25a, 25b as shown in FIG.
The point is that a pair of control valves 26a and 26b provided in the a and 10b are used to provide them.

That is, the pair of control valves 26a, 26b provided in the return passages 10a, 10b are of a normally-closed type, and are connected to the signal passages 15a, 15b to the pressure-receiving portions of the control valves 26a, 26b in the valve opening direction. The connected first signal paths 22a and 22b are connected, a control force in the valve opening direction is applied, and the second signal path 30a connected to the detection path 30 to the pressure receiving portion of the control valves 26a and 26b in the valve closing direction. , 30b are connected, and a control force in the valve closing direction is applied together with the springs 23a, 23b. The stroke of the control valves 26a, 26b is adjusted by the control force in the valve opening direction and the control force in the valve closing direction, and the position is adjusted. Is switched.

That is, at the minimum stroke position, the control valve 26a shuts off the actuator passage 11 and the return passage 10a, which are the main flow paths, and also shuts off the signal path 22a and the signal path 30a. The communication path between the actuator path 11 and the return path 10a, which are the paths, is connected to the signal path 22a and the signal path 30a.
a at the position of the intermediate stroke region, the actuator passage 11 which is the main passage and the return passage 1
0a is connected in a throttle state that causes a pressure drop corresponding to the stroke, and the signal path 22a and the signal path 30a are shut off.

Similarly, at the minimum stroke position, the control valve 26b also shuts off the actuator passage 12 and the return passage 10b, which are the main flow paths, and also shuts off the signal path 22b and the signal path 30b. Actuator passage 12 and return passage 10b as flow paths
And the signal path 22b and the signal path 30b
7a, the actuator passage 12 and the return passage 10b, which are the main passages, are connected in a throttle state that causes a pressure drop corresponding to the stroke at the position of the intermediate stroke region, and the signal passage 22b and the signal passage 30b are connected. It is configured to shut off.

Here, the throttle 2 in the control valves 26a, 26b
7a and 27b are set so that a pressure drop slightly larger than the pressure corresponding to the spring force of the springs 23a and 23b occurs. As a result, the throttles 27a, 27b of the control valves 26a, 26b are
27b functions as pressure generating means for making the control force in the valve opening direction of the control valve larger than the control force in the valve closing direction. The control valves 26a and 26b are normally closed, and the maximum signal in the valve closing direction. Even if the pressure is applied, when the signal pressure is led to the signal paths 22a and 22b, the control valves 26a and 26b are surely opened and maintained in that state, and the control valves 26a and 26b on the meter-out side are required. The above-mentioned increase in pressure loss can be prevented.

The operation of the thus-configured directional control valve devices 70A, 71A of the present embodiment will be described.

When the directional control valves 8, 8 are in the neutral position in the figure and none of the actuators 6, 7 is driven, the pressure in the maximum signal pressure detection path 30 is
c, the tank pressure is reached. For this reason, the discharge flow rate of the hydraulic pump 1 is controlled to the minimum flow rate (minimum tilt) by the regulator 2, and the discharge pressure of the hydraulic pump 1 is higher than the tank pressure by the unload valve 72 by the unload set differential pressure. The pressure is controlled. The control valves 26a, 26b are connected to the springs 23a, 23b.
, And performs a load holding function together with the load check valves 14a and 14b.

In this state, for example, when the directional control valve 8 of the directional control valve device 70A is switched to the right in the drawing in order to drive the actuator 6 alone in the extension direction, the discharge oil of the hydraulic pump 1 becomes The parallel pipe 4 is guided to the flow path 13a via the meter-in throttle 9a of the direction switching valve 8, and the downstream pressure of the meter-in throttle 9a is guided to the signal path 15b via the signal path 16a. A circuit is formed in which the actuator passage 11 is on the meter-in side and the actuator passage 12 is on the meter-out side.

The return path 10 is connected to the signal path 15b.
Since the signal path 22b of the control valve 26b on b is connected, the downstream pressure of the meter-in throttle 9a guided to the signal path 15b is guided as a signal pressure in the valve opening direction of the control valve 26b, and acts in the valve closing direction. Since the pressure in the signal path 30b is the tank pressure, the control valve 26b is switched to the valve opening position of the maximum stroke, and the actuator path 1 as the main flow path is opened.
2 and the return passage 10b, and the signal path 15b and the signal path 30b are connected via a throttle 27b. As a result, the downstream pressure of the meter-in throttle 9a guided to the signal path 15b is reduced via the throttle 27b to the maximum signal pressure detection path 3a.
0, a flow of pressure oil from the signal path 15b to the tank 5 via the throttle 27b, the maximum signal pressure detection path 30, and the throttle 31 is formed, and the pressure in the signal path 15b (downstream pressure of the meter-in throttle 9a) is The pressure is reduced by the pressure drop of the throttle 27b, and the reduced pressure is detected as the maximum signal pressure in the detection path 30, and the maximum signal pressure is guided as the signal pressure in the valve closing direction of the control valve 26b.

As described above, the throttle 27b is set so that a pressure drop greater than the pressure corresponding to the spring force of the spring 23b of the control valve 26b is generated. The control valve 26b is kept open even if the maximum signal pressure is applied in the valve closing direction, and the control valve 26b moves from the actuator passage 12 on the meter-out side to the return passage 10b and the tank The circuit connected to 5 is formed.

At the same time, the maximum signal pressure is guided to the tilt control device 2 of the hydraulic pump 1 and the unload valve 72 via the detection path 30, and the discharge pressure of the hydraulic pump 1 starts to increase.

Here, at the beginning of the switching operation of the direction switching valve 8, the discharge pressure of the hydraulic pump 1 is at the minimum pressure as described above, and is not at a pressure at which the actuator 6 can be driven. Therefore, the load check valve 14a remains closed.

When the discharge pressure of the hydraulic pump 1 starts to increase as described above, the increased discharge pressure of the hydraulic pump 1 is again guided to the signal paths 16a and 15b, and furthermore, the control valve 26
The signal pressure is detected as the highest signal pressure in the detection path 30 via the throttle 27b of b, and the discharge pressure of the hydraulic pump 1 further increases. This is repeated, and when the discharge pressure of the hydraulic pump 1 rises to a pressure sufficient to drive the actuator 6 to extend, the load check valve 14a is opened to allow the actuator 6 to perform the intended extension drive.

In the other control valve 26a, even if the directional control valve 8 is operated, the signal pressure is not guided to the signal path 15a and the maximum signal pressure is guided via the signal path 30a. , The control valve 26a keeps the valve closed state.

For example, when the directional control valve 8 of the directional control valve device 70A is switched to the left in the drawing in order to drive the actuator 6 alone in the contraction direction, the discharge oil of the hydraulic pump 1 The flow is guided to the flow path 13b through the meter-in throttle 9b of the direction switching valve 8, and the downstream pressure of the meter-in throttle 9b is guided to the signal path 15a via the signal path 16b. Meter-in side, actuator passage 12
Is formed on the meter-out side.

The return path 10 is connected to the signal path 15a.
Since the signal path 22a of the control valve 26a on the control valve 26a is connected, the downstream pressure of the meter-in throttle 9b led to the signal path 15a is led as the signal pressure in the valve opening direction of the control valve 26a, and acts in the valve closing direction. Since the pressure of the signal path 30a is the tank pressure, the control valve 26a is switched to the valve opening position of the maximum stroke and the actuator path 1 which is the main flow path is opened.
1 and the return passage 10a, and the signal path 15a and the signal path 30a are connected via the throttle 27a. As a result, the downstream pressure of the meter-in throttle 9b guided to the signal path 15a is reduced via the throttle 27a to the highest signal pressure detecting path 3b.
0, a flow of pressure oil from the signal path 15a to the tank 5 via the throttle 27a, the maximum signal pressure detection path 30, and the throttle 31 is formed, and the pressure in the signal path 15a (downstream pressure of the meter-in throttle 9b) becomes The pressure is reduced by the pressure drop of the throttle 27a, and the reduced pressure is detected as the maximum signal pressure in the detection path 30, and the maximum signal pressure is guided as the signal pressure in the valve closing direction of the control valve 26a.

Here, as described above, the throttle 27a is set so that a pressure drop larger than the pressure corresponding to the spring force of the spring 23a of the control valve 26a is generated, and the spring force of the spring 23a and the throttle 27a The control valve 26a keeps the valve open even if the maximum signal pressure acts in the valve closing direction according to the setting relationship described above. The circuit connected to 5 is formed.

At the same time, the maximum signal pressure is guided to the tilt control device 2 of the hydraulic pump 1 and the unload valve 72 via the detection path 30, and the discharge pressure of the hydraulic pump 1 starts to increase.

Therefore, similarly to the above, when the discharge pressure of the hydraulic pump 1 does not reach a pressure sufficient to drive the actuator 6 to contract, the load check valve 14b is closed and the discharge pressure of the hydraulic pump 1 is reduced. When the pressure rises to a value sufficient to drive the actuator 6, the load check valve 14b is opened, and the intended contraction drive of the actuator 6 can be performed.

Next, for example, for the purpose of combined driving, the directional control valve 8 of the directional control valve device 71A is operated to further drive the actuator 7 in the extending direction from the operating state of the actuator 6 alone in the extending direction, for example. And At this time, it is assumed that the load pressure of the actuator 7 is higher than the load pressure of the actuator 6.

By switching the direction switching valve 8 corresponding to the driving of the actuator 7 in the extension direction, a circuit is formed in which the actuator passage 11 of the direction switching valve device 71A is on the meter-in side and the actuator passage 12 is on the meter-out side. In conjunction with this switching operation, the control valve 26a switches to the valve opening position of the maximum stroke as in the case of the above-described direction switching valve device 70, and the actuator passage 12 on the meter-out side returns from the return passage 10
b, a circuit connected to the tank 5 via the tank line 10 is formed.

Further, the hydraulic pump 1 has a discharge pressure based on the load pressure of the actuator 6 which is on the low load side as described above. Therefore, the load check valve 14a of the actuator 7 operates immediately after the start of the composite operation. It cannot be opened, so the flow path 1 downstream of the meter-in throttle 9a of the direction switching valve 8
The discharge oil of the hydraulic pump 1 is directly guided to 3a,
a rises to the discharge pressure of the hydraulic pump 1, and this pressure is increased by the signal path 16a, the signal path 15b, and the control valve 2.
Since it is also guided to the detection path 30 through the throttle 27b of 6b, the maximum signal pressure starts to increase, and the discharge displacement control of the hydraulic pump 1 by the load sensing control is readjusted.

At the same time, the signal path 30 connected to the pressure-receiving portion for operating the control valve 26b in the valve closing direction on the return path 10b on the meter-out side of the actuator 6 on the low load side.
b, the increased maximum signal pressure is guided via the signal path 30b connected to the detection path 30, so that the return path 1
The return oil from 0b is throttled by the control valve 26b, and is controlled to rise so that the load pressure of the actuator 6 on the low load side becomes substantially equal to the maximum signal pressure. Then, the discharge pressure of the hydraulic pump 1 increases to the drive pressure level of the actuator 7 on the high load side.

When the discharge pressure of the hydraulic pump 1 rises in this way, the load check valve 14a of the direction switching valve device 71 is opened, and the intended extension of the actuator 7 can be driven.

The control valve 26b on the return passage 10b on the meter-out side of the directional control valve device 70 has a pressure on the downstream side of the meter-in throttle corresponding to the switching direction of the directional control valve 8, that is, the load pressure on the actuator 6. The discharge control is performed on the meter-out side so as to be approximately equal to the maximum load pressure, and thus the actuators 6 with different load pressures are controlled.
7, the pressure on the downstream side of the meter-in throttle of the directional control valve 8 of the directional control valve device 70 is restricted by the directional control valve 26b due to the restriction of the passage area from the low load side actuator 6 to the tank line by the control valve 26b. Since the pressure rises to the same level as the pressure downstream of the meter-in throttle of the directional control valve 8 of the device 71, the discharge flow rate of the hydraulic pump 1 is distributed according to the opening area ratio of the meter-in throttle of each directional control valve 8, 8. Can be.

As described above, according to the present embodiment, the first
The same effect as that of the embodiment can be obtained.

Further, according to the present embodiment, the control valve 26b (or 26a) on the meter-out side return passage 12 (or 11) of the directional control valve 8 on the high load side during the single operation or the combined operation. Is fully opened at the maximum stroke position, the signal path 14b (or 14a) is passed through the throttle 27b (or 27a) in the control valve.
And the detection path 30b (or 30a), the detection path of the highest signal pressure can be simplified.

FIG. 4 shows the directional control valve device 7 of FIG.
It is a figure showing an example of a valve structure of a pair of control valves 26a and 26b provided in return passages of 0A and 71A. In addition,
2 and 3 are denoted by the same reference numerals and description thereof is omitted. In addition, common parts of the control valves 26a and 26b will be described by reference numerals with suffixes "a" and "b".

In FIG. 4, a second spool hole 201 is provided in the casing body 100, and a valve body 260 of the control valve 26a (or 26b) is fitted therein.

Second spool hole 2 of casing body 100
01 is an actuator port 202 which forms part of the actuator passage 11 (or 12) and the return passage 1
Tank port 20 which forms part of 0a (or 10b)
3, the port 202 and the port 203 are communicated and blocked by a throttle notch 211 formed in a land portion (large diameter portion) 260f of the control valve body 260 inserted into the second spool hole 201. You.

Further, a first pressure receiving chamber 204 and a second pressure receiving chamber 205 having a second spool hole 201 are formed so as to sandwich the actuator port 202 and the tank port 203, and a control valve inserted through the second spool hole 201 is formed. Valve element 26
The first pressure receiving chamber 204 is connected to the signal path 22a (or 22b) to apply control force in the valve opening direction to the control valve valve body 260, and the second pressure receiving chamber 204 is connected to the signal path 22a (or 22b). The pressure receiving chamber 205 is connected to a signal path 30 a (or 30 b) connected to the highest signal pressure detection path 30, and applies a control force in the valve closing direction together with the spring 23 arranged in the second pressure receiving chamber 205.

Further, an oil hole 261 communicating with the first pressure receiving chamber 204 and extending in the axial direction to near the center of another land portion (large diameter portion) 260 s of the control valve valve 260 is provided in the control valve 260. And a fine hole 262 that is provided in the land portion 210s in a direction perpendicular to the oil hole 261 and forms a fixed throttle is formed,
It constitutes a signal oil passage in the valve.

Further, one end of the valve body 260 disposed in the second pressure receiving chamber 205 and adjacent to the land portion 210s is in contact with the wall surface of the casing body 100 of the pressure receiving chamber 205,
A shoulder portion 263 functioning as a stopper for determining the minimum stroke position of the valve body 260 is provided,
At the end of the valve body 260, a protruding portion 264 that abuts on the plug 220 fastened to the casing body 100 so as to seal the second pressure receiving chamber 205 and functions as a stopper that determines the maximum stroke position of the valve body 260 is provided. Is provided.

Here, the throttle notch 211 formed in the control valve valve body 260 and the fine aperture 262 forming the fixed throttle are formed.
Smax>Ss>So> Smin where Smax: maximum stroke Smin: minimum stroke Ss: opening start distance of pore 262 So: aperture 211 opening start distance The dimensions of each part are set so as to satisfy the following relationship. Has been
This allows the aperture notch 211 to move up to the stroke So.
Until the stroke Ss, the opening of the fine hole 262 is blocked by a close sliding surface between the second spool hole 201 into which the valve body 260 is inserted and the respective land portions 210f and 210s.

In the control valve thus configured,
The control valve valve body 260 controls the valve opening direction of the signal path 22a (or 22b) guided to the first pressure receiving chamber 204 and closes the signal path 30a (or 30b) guided to the spring 23 and the second pressure receiving chamber 205. The stroke is adjusted by the control force in the valve direction.

Then, the stroke S of the control valve valve body 260
Is, for example, a minimum stroke for interrupting the connection between the actuator port 202 and the tank port 203 (So>S> Smin).
, The opening of the aperture 262, which is a fixed stop, is blocked, so that the signal path 22a (or 22b) and the signal path 3
0a (or 30b) can be cut off.

When the stroke S of the control valve body 260 is at the maximum stroke (Smax>S> Ss) for fully opening the actuator port 202 and the tank port 203, the small aperture 262 as a fixed throttle opens. , These pores 26
2 and signal path 22a (or 22b) and signal path 3
0a (or 30b) can be communicated.

Further, when the stroke S of the control valve body 260 is in the intermediate stroke range (Ss>S> So) where the pressure drop between the actuator port 202 and the tank port 203 is adjusted by the throttle function of the throttle notch 211. The opening of the aperture 262, which is a fixed stop, is blocked, so that the signal path 22a (or 22b) and the signal path 30a (or 3).
0b).

As described above, in the control valve shown in FIG.
Signal path 26 for detecting the highest signal pressure in control valve element 260
The signal path 22a (or 22b) and the signal path 3 are interlocked with the connection between the actuator port 202 and the tank port 203 by the control valve valve element 260.
Since connection / disconnection of 0a (or 30b) is performed, the signal path configuration can be realized with a simplified structure.

FIG. 5 is a view showing an example of the valve structure of the above-described direction switching valve devices 70A and 71A of FIG. 3 which is constructed using the control valve of FIG. The difference from the valve structure of FIG.
The detection unit of the maximum signal pressure is different from the signal path configuration using the check valves 24a and 2b and the springs 25a and 25b in FIG. The same components as those shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 5, a spool 111 is inserted into a first spool hole 101 in a casing body 100, and a port 104 described with reference to FIG.
a, 104b; 105a, 105b; 106a, 106
b; 107a and 107b are formed. However, the check valves 24a, 24b, the spring 25
a, 25b and the detection hole 110 are not provided, and the signal pressure ports 107a, 107b are connected only to the signal paths 22a, 22b.

The valve bodies 260a and 260b of the control valves 26a and 26b are fitted in the second spool holes 201a and 201b in the main body casing 100. The valve bodies 260a and 260b of the control valves 26a and 26b correspond to the control valve body 260 described with reference to FIG. 4, and the same parts as those shown in FIG. The characters “a” and “b” are shown.

The operation of the present embodiment configured as described above is similar to the operation of the control valve 26a, 26b except that the valve bodies 260a, 260b of the control valves 26a, 26b operate similarly to the control valve body 260 shown in FIG. The operation is the same as that of the embodiment shown in FIG.

Therefore, according to the present embodiment, FIG.
The functions of the direction switching valve devices 70A and 71A shown in the hydraulic circuit diagram can be achieved, and the same effects as in the embodiment shown in FIG. 3 can be obtained.

[0127]

According to the present invention, a control valve having a flow dividing function is disposed on the return passage, so that pressure oil can be prevented from flowing out from the detection passage of the highest signal pressure, and the valve structure can be simplified.
The size can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a hydraulic circuit device provided with a direction switching valve device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of the structure of the direction switching valve device shown in FIG.

FIG. 3 is a diagram showing a hydraulic circuit device provided with a direction switching valve device according to a second embodiment of the present invention.

4 is a sectional view showing an example of a structure of a control valve provided in the direction switching valve device shown in FIG.

FIG. 5 is a sectional view showing an example of the structure of the entire directional switching valve device shown in FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Variable displacement hydraulic pump 2 Tilt control part 3 Discharge path 4 Parallel oil path 5 Tank 6, 7 Actuator (cylinder) 8 Direction switching valve 9a, 9b Meter-in throttle 10 Tank line 10a, 10b Return path 11, 12 Actuator path 13a , 13b Flow paths 14a, 14b Load check valves 15a, 15b Signal paths 16a, 16b Signal paths 17a, 17b Signal paths 18a, 18b Drain paths 21a, 21b Control valves 22a, 22b Signal paths 23a, 23b Springs 24a, 24b Check valves 25a , 25b Spring 26a, 26b Control valve 27a, 27b Restrictor 30 Maximum load pressure detection path 30a, 30b Signal path 30c Drain path 31 Restrictor 70, 71 Direction switching valve device with diversion compensation 72 Unload valve 100 Casing body 101 First spool hole 1 04a, 104b Pump port 105a, 105b Meter-in actuator port 106a, 106b Drain port 107a, 107b Signal pressure port 108a, 108b Check valve inflow port 109a, 109b Check valve outflow port 110 Detection hole 111 Spool 112 Oil hole 112a, 112b, 112c Fine hole 113 Oil hole 113a, 113b, 113c Fine hole 120a, 120b Meter-in throttle notch 140a, 140b Load check valve body 201, 201a, 201b Second spool hole 202a, 202b Actuator port (part of actuator passage) 203a, 203b Tank port (part of return passage) 204, 204a, 204b First pressure receiving chamber 205, 205a, 205b Second pressure receiving chamber 210a, 10b control valve valve element 211,211a, 211b diaphragm 220,220a, 220b plug 260a, 260b control valve valve body 261 oil hole 262 aperture 263 shoulder

Claims (5)

[Claims] 1. A directional switching valve device with a diverting flow compensation having a directional switching valve arranged to connect between a hydraulic pump and an actuator, wherein the directional switching valve is provided on a pair of actuator passages connecting the directional switching valve to the actuator. A pair of load check valves disposed, a pair of return passages connecting the actuator and the tank without interposing the direction switching valve, a first return passage disposed on the pair of return passages,
A pair of normally closed control valves to which a control pressure is applied and a second control pressure and a spring force are applied in a valve closing direction; and a pair of the direction switching valves at a position upstream of the pair of load check valves. A first detecting means for detecting a downstream pressure of the meter-in variable throttle as a signal pressure; and a first detecting means provided between the first detecting means and a detection path of the highest signal pressure, wherein the signal pressure detected by the first detecting means is A second detection means for detecting a signal pressure higher than a signal pressure in a detection path of the highest signal pressure as a highest signal pressure; and only a control valve of the pair of control valves which is on a meter-out side when the direction switching valve is operated. A first signal transmitting means for guiding a signal pressure detected by the first detecting means as the first control pressure, and a highest signal detected by the second detecting means as the second control pressure to each of the pair of control valves. 2nd signal transmission leading pressure And a diverting means. 2. The directional control valve device according to claim 1, wherein the detection path for the highest signal pressure is connected to a tank via a drain passage provided with a throttle, and the second detection means includes a first detection means for detecting the first signal pressure. A check valve mechanism connected to the signal path through which the signal pressure detected by the detection means is led to only the detection path of the highest signal pressure so as to be openable and also functioning as pressure generation means; A directional switching valve device with a shunt compensation, wherein a differential pressure is set to a value larger than an opening differential pressure of the control valve. 3. The directional control valve device according to claim 1, wherein said second detecting means is incorporated in said pair of control valves, each of said control valves being a minimum for shutting off a flow path of said return passage. A stroke position, a maximum stroke position for fully opening the flow passage of the return passage, and an intermediate stroke position for variably narrowing the flow passage of the return passage,
A valve whose stroke is adjusted by the control force in the valve opening direction by the first control pressure, the second control pressure, and the control force in the valve closing direction by a spring; At the stroke position, the detection path of the signal pressure detected by the first detection means and the detection path of the maximum signal pressure are shut off, and at the maximum stroke position of the control valve, the detection path of the signal pressure and the detection path of the maximum signal pressure are blocked. A directional switching valve with shunt compensation, wherein the directional switching valve is configured to communicate with a detection path and to cut off the detection path of the signal pressure and the detection path of the maximum signal pressure at an intermediate stroke position of the control valve. apparatus. 4. The directional control valve device according to claim 3, wherein the detection path for the maximum signal pressure is connected to a tank via a drain passage provided with a throttle, and the control valve is configured to move the control valve at the maximum stroke position. The detection path of the signal pressure and the detection path of the highest signal pressure are configured to communicate through a throttle. The throttle that operates at the maximum stroke position of the control valve closes the control force in the valve opening direction of the control valve. A directional switching valve device with a shunt compensation, wherein the directional control valve device is set to be larger than a control force in a valve direction. 5. A hydraulic circuit device having a plurality of directional control valves arranged so as to connect between a hydraulic pump and a plurality of actuators, respectively, wherein each of the plurality of directional control valves corresponds to the plurality of actuators. A pair of load check valves arranged on a pair of actuator passages connected to the actuator, a pair of return passages connecting each of the plurality of actuators and the tank without passing through the plurality of direction switching valves, A pair of normally closed types arranged on the pair of return passages respectively corresponding to the plurality of actuators, wherein a first control pressure is applied in a valve opening direction and a second control pressure and a spring force are applied in a valve closing direction. A control valve provided at each of the plurality of directional control valves, and the directional control valve is disposed at a position upstream of the pair of load check valves. First detection means for detecting the downstream pressure of the pair of meter-in variable throttles of the switching valve as a signal pressure; and between the first detection means and the detection path of the highest signal pressure corresponding to each of the plurality of directional control valves. A second detecting means for detecting when the signal pressure detected by the first detecting means is higher than the signal pressure of the detection path of the highest signal pressure as the highest signal pressure; It is provided corresponding to each,
A first signal transmission unit that guides a signal pressure detected by the first detection unit as the first control pressure only to a control valve that is on a meter-out side when the direction switching valve is operated, of the pair of control valves; Provided corresponding to each of the plurality of direction switching valves,
A hydraulic circuit device comprising: a second signal transmitting unit that guides a maximum signal pressure detected by the second detecting unit as the second control pressure to each of the pair of control valves.