JP2001099104A - Hydraulic circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent driving pressure in the initial stage of driving of an inertial body from suddenly rising and to avoid running away of load without needing a counter balance valve, in a hydraulic circuit device having a load sensing system. SOLUTION: In a control valve 2-1 of a load sensing system, inlet ports 18a, 18b, outlet ports 20a, 20b and oil passages 19a, 19b as internal passages are formed on a main spool 13 of a spool valve 12, the inlet ports 18a, 18b are normally opened to meter-in actuator ports Ain, Bin, and the outlet ports 20a, 20b are opened to a return port R to provide a depressure circuit when the main spool 13 is in the neutral position shown in the figure. When the main spool 13 is stroked from the neutral position shown in the figure, the outlet ports function as bleed-off variable throttle parts to be throttled by a housing land part according to the stroke and then full closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit device provided with a load sensing system mounted on a hydraulic machine such as a hydraulic shovel that supplies and drives a discharge oil of one hydraulic pump to a plurality of hydraulic actuators.

[0002]

2. Description of the Related Art A hydraulic circuit device mounted on a hydraulic machine such as a hydraulic shovel has a center bypass type control valve having a bleed-off circuit and a closed center type control valve having no bleed-off circuit. Some are provided. In the latter case, a load sensing system for controlling a discharge oil amount of a hydraulic pump so as to basically supply a flow rate required by a control valve is generally employed. When the purpose is to simplify the hydraulic equipment, the latter is advantageous because there is no bleed-off circuit. However, since it does not have a bleed-off circuit, the pressure transiently rises suddenly when driving a hydraulic actuator that receives the inertial load of a large inertial body, and this causes a problem that rapid acceleration occurs and smooth starting characteristics cannot be obtained. is there.

That is, since the load sensing system controls the amount of oil discharged from the hydraulic pump so as to supply the flow rate required by the control valve, the hydraulic actuator operates like a turning motor that turns the upper body of a hydraulic shovel. In the case of an actuator that drives an inertial body, the amount of oil discharged by the hydraulic pump cannot be consumed by the rotation of the inertial body in the initial stage when the inertial body is driven by the hydraulic actuator, so that the hydraulic actuator is driven by the hydraulic pump. Since the discharge pressure suddenly becomes high and an excessive driving force acts on the inertial body, it is difficult to smoothly drive the inertial body.

Therefore, a hydraulic circuit device disclosed in Japanese Patent Application Laid-Open No. 5-288202 has been proposed to reduce the flow rate of supply to an actuator with an increase in drive pressure and to suppress a steep rise in pressure. In this hydraulic circuit device, a plurality of operation valves each having a variable restrictor for meter-in flow rate control are provided in a discharge path of a hydraulic pump, and a pressure compensation valve (division valve) is provided between each operation valve and the hydraulic actuator.
And a load sensing system that controls the discharge pressure of the hydraulic pump to be higher than the maximum load pressure by a predetermined value based on the maximum load pressures of the plurality of actuators. In addition, at least one operation valve includes a variable throttle unit for controlling the meter-in flow rate and a variable throttle unit for controlling a meter-out flow rate provided in an oil passage connecting an outlet side of the pressure compensating valve to the tank. The variable throttle unit for flow rate control and the variable throttle unit for meter-out flow rate control are configured to overlap and open at the initial stage of operation of the operation valve. In this way, by opening the two variable throttle portions so as to overlap at the initial stage of the operation of the operation valve, as described above, when an oil amount that cannot be consumed by the hydraulic actuator occurs at the initial stage of driving the inertial body, the meter-out flow control is performed. The pressurized oil is returned to the tank via the variable throttle section for the pump, so that a rapid pressure increase can be avoided.

In a hydraulic circuit device provided with a load sensing system, a control valve described in International Patent Application Publication No. WO 98/31940 is one in which a flow dividing valve and a hold check valve are combined to simplify the configuration as a valve assembly. . In this device, the valve body of the flow dividing valve is partially incorporated in the hollow valve body of the hold check valve, and the load pressure detection oil passage of the control valve is formed as an internal passage (oil passage slit) of the flow dividing valve. And by giving a check valve function using its internal passage,
The check valve as a valve element is not required, and the configuration of the entire control valve is simplified.

[0006]

However, the above prior art has the following problems.

In the hydraulic circuit device described in Japanese Patent Application Laid-Open No. 5-288202, in order to avoid a sudden increase in driving pressure at the initial stage of driving the inertial body, the hydraulic circuit device overlaps with a variable throttle unit for meter-in flow rate control at the initial stage of operation. A variable throttle unit for controlling the meter-out flow rate, which is opened at the same time, is provided. But,
Since the metering-out flow control variable throttle section is provided in the oil passage connecting the outlet side of the pressure compensating valve to the tank,
When the operation valve is neutral, the outlet side of the hydraulic actuator is in a state of communicating with the tank via the oil passage and the variable throttle unit for meter-out flow rate control, and there is a possibility that the load may run away. For example, when the vehicle body is inclined on a slope or the like, when the operation valve is neutralized and the revolving unit is to be stopped at a predetermined angle, the revolving unit has its own weight because the suction side of the revolving motor communicates with the tank. It turns. In order to avoid such load runaway, a counterbalance valve between the operating valve and the actuator is usually incorporated. That is,
In order to apply the hydraulic circuit device described in JP-A-5-288202 to a turning system, it is necessary to newly add a counterbalance valve. However, adding a counterbalance valve like this not only increases costs,
It affects the operation of the actuator during normal work, and the operability is reduced, such as the movement of the actuator being jerky.

The control valve described in International Publication WO98 / 31940 has a valve assembly in which a flow dividing valve and a hold check valve are combined, and various functions are incorporated therein, so that the configuration of the entire control valve is simplified. There are advantages. However, no measures have been taken against a sudden rise in pressure when driving an actuator that receives a large inertial load.If the inertial load of the inertial body to be driven is large, a sudden rise in pressure occurs at the beginning of driving the actuator. The problem is not solved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic circuit device having a load sensing system, which can prevent a sudden increase in drive pressure at the time of initial drive of an inertial body, and can avoid runaway of a load without requiring a counterbalance valve. It is to provide a hydraulic circuit device which can be used.

[0010]

(1) In order to achieve the above object, the present invention provides a hydraulic pump, a plurality of actuators driven by hydraulic oil discharged from the hydraulic pump, and a plurality of actuators. A plurality of control valves for controlling the flow rate of the hydraulic oil supplied to the load, a control pressure based on a maximum load pressure of the plurality of actuators, and a load for controlling a discharge pressure of the hydraulic pump to be higher than the control pressure. A plurality of control valves, wherein each of the plurality of control valves is provided with a spool valve formed with a variable throttle section for meter-in flow rate control, and a hold located downstream of the variable throttle section for meter-in flow rate control of the spool valve. A hydraulic circuit device including a check valve and a meter of said spool valve of at least one of said plurality of control valves. A branch oil passage branched from an oil passage between the variable throttle portion for controlling the flow rate and the hold check valve, and a downstream end connected to a low-pressure circuit; and a branch oil passage provided in the branch oil passage, wherein the spool valve is neutral. A bleed-off variable throttle unit that has an opening area that decreases as the stroke from the position decreases and that partially overlaps with the variable throttle unit for meter-in flow rate control.

By providing the bleed-off variable throttle portion in the branch oil passage in this way, the inertia body is provided at the stroke portion which is opened by overlapping with the meter-in flow rate control variable throttle portion after the start of the stroke of the spool valve. When an excessive amount of oil that cannot be consumed by the actuator is generated at the initial stage of the driving, the pressurized oil is recirculated (bleed) to the tank through the bleed-off variable throttle unit, so that a sudden increase in the driving pressure can be avoided. Also, by branching the branch oil passage from an oil passage between the variable throttle portion for meter-in flow rate control of the spool valve and the hold check valve, the variable throttle portion for bleed-off is opened when the spool valve is neutral. Since the backflow of the pressure oil from the actuator is also prevented, the runaway of the load can be avoided without the need for the counterbalance valve.

(2) In the above (1), preferably,
Means for detecting, as the load pressure, the pressure of an oil passage between the variable throttle unit for meter-in flow rate control of the spool valve and the hold check valve when the load pressure of the actuator to which it is related is the maximum load pressure. Provide.

Thus, the pressure modulated by bleeding the surplus oil amount from the oil passage between the variable throttle portion for meter-in flow rate control of the spool valve and the hold check valve is detected as the load pressure, and the load sensing control is performed. Since the means controls the pump discharge pressure to be higher than the control pressure based on the modulated pressure, the pump pressure is adjusted to the modulated pressure in the oil passage between the variable restrictor for meter-in flow rate control of the spool valve and the hold check valve. Accordingly, the discharge pressure of the hydraulic pump gradually increases, and a sudden increase in drive pressure can be prevented by controlling the pump discharge pressure in addition to the bleeding of the pressure oil.

(3) In the above (1), preferably, a flow dividing valve is disposed in an oil passage between the variable restricting portion for controlling the meter-in flow rate of the spool valve and the hold check valve. The branch oil passage is branched at the inlet side of the branch.

With this arrangement, the flow dividing valve is arranged downstream of the variable throttle portion for controlling the meter-in flow rate of the spool valve, and when a plurality of spool valves are simultaneously operated, each spool valve is independent of the load pressure of each actuator. Pressure oil can be supplied at a shunt ratio proportional to the opening area of the meter-in throttle,
As described above, the flow rate can be distributed in proportion to the opening area, and as described in the above (1), it is possible to prevent a sudden increase in the driving pressure at the initial stage of the driving of the inertial body. You can avoid runaway.

(4) In the above (3), preferably,
When the load pressure of the actuator associated with the shunt valve is the maximum load pressure, the pressure in the oil passage between the variable restrictor for meter-in flow rate control of the spool valve and the hold check valve is defined as the load pressure. Provide a check valve function to detect.

Accordingly, as described in the above (2), the discharge pressure of the hydraulic pump is moderated in accordance with the modulated pressure of the oil passage between the variable throttle portion for controlling the meter-in flow rate of the spool valve and the hold check valve. In addition to the bleeding of the pressure oil, the control of the pump discharge pressure can prevent a sudden increase in pressure.

Further, since the flow dividing valve is provided with a check valve function, the valve function is centralized, and the control valve can be made compact and simple.

(5) In the above (1), preferably, the branch oil passage is constituted by an internal passage as a pressure oil drain circuit of the spool valve, and the bleed-off variable throttle portion is provided in the internal passage. Provide at the exit port.

[0020] Thus, the branch oil passage and the variable bleed-off throttle can be configured by using the pressure relief circuit, and the bleed-off circuit can be configured without increasing the cost.

(6) Further, in the above (1), preferably, a return oil passage branched from between the hold check valve and the hydraulic actuator is provided, and the return oil passage is provided in the spool valve. Connected to the tank via a variable throttle for flow control.

With this arrangement, as described in the above (1), the pressure oil in the oil passage between the variable throttle portion for meter-in flow rate control of the spool valve and the hold check valve is bleed, and the return from the actuator is performed. Oil can be returned to the tank.

[0023]

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

In FIG. 1, reference numeral 1 denotes a variable displacement hydraulic pump which constitutes a hydraulic source of a hydraulic circuit device according to the present embodiment. The hydraulic pump 1 has a variable displacement mechanism, for example, a swash plate 1a. The displacement (displacement volume) of the hydraulic pump 1 is controlled by operating the displacement controller 8 to adjust the tilt angle.
Is changed, and the discharge flow rate of the hydraulic pump 1 is controlled. The discharge oil passage 1b of the hydraulic pump 1 has a plurality of control valves 2-
, A plurality of hydraulic actuators 3-
Are supplied to the plurality of actuators 3-1, 3-2,... To drive these actuators.
By operating the respective control valves 2-1, 2-2,..., The actuators 3-1, 3-2,.
Are controlled, and the driving direction and driving speed of the actuators 3-1 to 3-2 are controlled.

The displacement controller 8 is a load sensing control regulator, which controls the pressure of the discharge oil passage 1b of the hydraulic pump 1,
That is, the plurality of actuators 3-1 and 3--3 detected as control pressures in the discharge pressure of the hydraulic pump 1 and the load pressure detection oil passage 7 are provided.
2, the maximum load pressure (described later) is led, and the displacement of the hydraulic pump 1 is controlled so that the discharge pressure of the hydraulic pump 1 becomes higher than the control pressure (the maximum load pressure) by a predetermined value. The predetermined value in this case is, for example, 1 set by the spring 8a of the capacity controller 8.
It is about 5 bar.

A main relief valve 9 is connected to the discharge oil passage 1b of the hydraulic pump 1, and regulates the maximum value of the discharge pressure of the hydraulic pump 1.

The details of the control valves 2-1, 2-2,... Will be described using the control valve 2-1 as a representative.

The control valve 2-1 includes various valve elements such as a spool valve 12 as a direction control valve, flow dividing valves 22a and 22b, and hold check valves 32a and 32b. The spool valve 12 includes a pump port P connected to the discharge oil passage 1b of the hydraulic pump 1 via the parallel oil passage 10, a return port R connected to the tank T via the return oil passage 11, and a meter-in actuator port Ain. , Bin
And meter-out actuator ports Aout, Bout
, And a main spool 13 for switching the connection between these ports. The main spool 13 has a variable throttle unit for meter-in flow rate control, which is located between the pump port P and the meter-in actuator ports Ain and Bin. The notches 14a and 14b are formed, and the notches 15a and 15b are formed between the meter-out actuator ports Aout and Bout and the return port R and constitute variable throttle portions for controlling the meter-out flow rate.
The main spool 13 has inlet ports 18a, 18
b and outlet ports 20a and 20b, and the inlet port 1
Oil passages 1 as internal passages connecting 8a, 18b and outlet ports 20a, 20b in the main spool 13, respectively.
9a and 19b are formed. Inlet port 18a,
18b is a meter-in actuator port Ain, Bin
And the outlet ports 20a and 20b open to the return port R when the main spool 13 is at the neutral position in the drawing to provide a pressure relief circuit, and the main spool 1
When the stroke 3 is moved from the illustrated neutral position, it is narrowed down by the housing land according to the stroke, and then functions as a bleed-off variable throttle (to be described later) that is fully closed.

The flow dividing valves 22a, 22b and the hold check valves 32a, 32b are located downstream of the notches 14a, 14b for controlling the meter-in flow, respectively, and are connected to the oil ports 23a, 2 connected to the actuator ports Ain, Bin of the meter-in.
3b is connected between the actuator ports 33a and 33b for connection to the actuator 3-1, and the flow dividing valves 22a and 22b are connected to the hold check valves 32a and 32b.
b.

As shown in FIG. 2, the flow dividing valve 22a has a valve body 26 that changes the opening area between the inlet port 24 and the outlet port 25 by stroke in the housing.
6 is provided with a control room 27 at the back thereof. The working end of the valve body 26 in the valve opening direction is located at the inlet port 24, and the working end of the valve body 26 in the valve closing direction is located in the control chamber 27. The valve body 26 is balanced by the pressure in the control chamber 27 and the pressure in the inlet port 24. By controlling the pressure in the inlet port 24 to be equal to the pressure in the control chamber 27, the differential pressure across the notch 14a for controlling the meter-in flow of the spool valve 12 is controlled.

An oil passage slit 28 opening to the outlet port 25 is formed in the outer periphery of the valve body 26,
8 does not open at the end of the valve body 26 at the end of the valve body 26, and when the valve body 26 is in the closed position, the wrap amount X that blocks communication between the oil passage slit 28 and the control chamber 27. Is formed, and when the valve body 26 strokes from the closed position shown in the drawing by the lap amount X or more, the oil passage slit 28 opens into the control chamber 27. Control room 27 is oil passage 3
0 is connected to the load pressure detection oil passage 7.

Here, the oil passage slit 28 and the oil passage 30
Opens when the load pressure of the hydraulic actuator 3-1 to which it is related is the highest load pressure, and guides the pressure between the flow dividing valve 22a and the hold check valve 23a to the control chamber 27. The pressure guided to the control chamber 27 is further guided to the load pressure detecting oil passage 7 via the oil passage 30 and transmitted to the displacement controller 8 of the hydraulic pump 1. In other words, the oil passage slit 28 and the lap portion 29 are connected to the hydraulic actuator 3-
It has a check valve function that opens only when the load pressure of No. 1 is the maximum load pressure and detects the pressure between the flow dividing valve 22a and the hold check valve 23a as the load pressure.

The same applies to the flow dividing valve 22b.

The hold check valves 32a and 32b are located on the outlet port 25 side of the flow dividing valves 22a and 22b, respectively, and the outlet port 31 of the hold check valves 32a and 32b is connected to actuator ports 33a and 33b for connection. I have. The hold check valves 32a and 32b are closed while the pressure at the outlet port 25 of the flow dividing valves 22a and 22b is lower than the pressure at the actuator ports 33a and 33b, and prevent the backflow of the pressure oil from the actuator ports 33a and 33b.

Actuator ports 33a, 3 for connection
3b is a flow dividing valve 22a, 22b, respectively, as described above.
And the hold check valves 32a, 32b and the oil passages 23a,
The spool valve 12 is connected to the meter-in actuator ports Ain and Bin via 23b. The connection actuator ports 33a and 33b are connected to meter-out actuator ports Aout and Bout of the spool valve 12 via oil passages 34a and 34b, respectively. That is, there are two oil paths connecting the spool valve 12 and the actuator ports 33a, 33b, one of which is a flow dividing valve 22a, 22b and a hold check valve 32a,
32b, a meter-in system of oil passages 23a and 23b and meter-in actuator ports Ain and Bin.
One is a meter-out system of oil passages 34a, 34b and meter-out actuator ports Aout, Bout.

The main spool 13 is connected to the actuator ports Ain and Bin of the meter-in system as described above.
The inlet ports 18a, 18b formed at the opening are open,
The inlet ports 18a, 18b are connected to outlet ports 20a, 20b via oil passages 19a, 19b, and the outlet ports 20a, 20b function as a bleed-off variable throttle with respect to the return port R. The opening area for the return port R is reduced according to

FIG. 3 shows a notch 14 for meter-in flow rate control.
The relationship between the opening characteristics of the outlet ports 20a and 20b (variable bleed-off diaphragms) is shown. Notches 14a and 14b for meter-in flow rate control are
When the main spool 13 is in the neutral position, it is fully closed, the main spool 13 is stroked from the neutral position and opens when the stroke becomes S1, and thereafter, the opening area increases as the stroke increases. The outlet ports 20a and 20b (variable bleed-off restricting portions) are fully opened when the main spool 13 is at the neutral position, and the opening area for the return port R is reduced as the main spool 13 strokes from the neutral position, thereby reducing the stroke S2. And fully closed. here,
As shown in the drawing, S2> S1, and between the strokes S1 and S2, the notches 14a, 14b and the outlet ports 20a, 2
0b overlaps and opens.

That is, the inlet ports 18a, 18b, the oil passage 1
9a, 19b, outlet ports 20a, 20b are notches (variable restrictors) 1 for controlling the meter-in flow rate of the spool valve 12.
4a, 14b and the oil passages 23a, 23b between the hold check valves 32a, 32b.
And a branch oil passage connected to the outlet ports 20a, 2
Reference numeral 0b denotes a notch (variable throttle portion) provided in the branch oil passage for reducing the opening area as the spool valve 12 strokes from the neutral position and for controlling the meter-in flow rate.
A bleed-off variable aperture unit which partially overlaps with the apertures 14a and 14b constitutes an aperture.

An example of the actual configuration of the control valve 2-1 will be described with reference to FIGS. In the figure, parts that are the same as the parts shown in FIGS. 1 and 2 are given the same reference numerals.

In FIG. 4, reference numeral 101 denotes a casing into which a main spool 13 of a spool valve 12 is slidably inserted. Spool 13
Is provided with a land 104-1 at the center portion thereof, and two lands 104-2 and 104-3 are provided on both sides thereof. The center land 104-1 is provided with the notches 14a and 14b for meter-in flow control having both functions of flow control and direction control, and the lands 104-2 and 104-2 on both sides thereof have notches. Not provided, and notches 15a, 15b for meter-out flow rate control are provided on lands 104-3, 104-3 outside thereof.

The central land 104-1 of the casing 101
The pump port P is formed in a portion where
The pump port P is connected to a discharge oil passage 16 of the hydraulic pump 1 (see FIG. 1) via a parallel oil passage 10.
The meter-in actuator ports Ain and Bin are formed on both outer sides of the pump port P of the casing 101, and the meter-out actuator ports Aout and Bout are formed further outside thereof. Return ports Ra and Rb that are the above-described return ports R
Is formed, and a central land 104-of the main spool 13 is formed.
1 and the lands 104-2, 104-2 are located at the actuator ports Ain, Bin.
Portions between the second and fourth lands 104-3 and 104-3 are located at actuator ports Aout and Bout, and the lands 104-3 and 104-3 are located at return ports Ra and Rb. The return oil passage 11 is connected to the return ports Ra and Rb.

The oil passages 23a and 23b extend downward from the actuator ports Ain and Bin, and the inlet ports 24 of the flow dividing valves 22a and 22b are located at the lower ends thereof.
Actuator ports Aout, Bo outside 3a, 23b
The oil passages 110a, 110b extend downward from the ut in the figure, and the outlet ports 31 of the hold check valves 32a, 32b are located at the lower ends thereof, and the flow dividing valves 22a, 22b and the hold check valve 32a are located between the inlet port 24 and the outlet port 31. ,
32b combined valve assemblies 56a, 56b
Is arranged. Also, the actuator port Aou
The oil passages 34a and 34b extend from t and Bout upward in the figure, and reach the connection actuators 33a and 33b. An outwardly flowing relief valve 7 is provided between the connecting actuator ports 33a, 33b and the return ports Ra, Rb.
0a and 70b are provided.

The details of the valve assemblies 56a and 56b will be described with reference to FIG.

In FIG. 5, the flow dividing valve 22a has the above-mentioned valve element 26. One end of the valve element 26 is located at the inlet port 24, and the other end is located at the control chamber 27. The hold check valve 32a has a hollow spool-shaped valve body 60 located at the outlet port 31, and the valve body 26 of the flow dividing valve 22a is partially slidably mounted inside the valve body 60 of the hold check valve 32a. And the flow dividing valve 22 is disposed between the valve body 26 and the valve body 60.
The outlet port 25a is formed as an intermediate chamber.

The valve body 60 of the hold check valve 32a is
A large diameter portion 61 having an outer diameter D2 and an inner diameter d2 and an outer diameter D3 (<
D2) and a small diameter portion 62 having an inner diameter d3 (<d2), and a sheet portion 63 is provided at a tip of the large diameter portion 61. The large diameter portion 61 is slidably fitted to the casing 101, and the small diameter portion 62 is slidably fitted to the inner diameter portion of the sleeve 64 inserted into the casing 101. A load pressure chamber 65 is formed between the boundary between the large diameter portion 61 and the small diameter portion 62 and the end face of the sleeve 64, and a load pressure is guided from the outlet port 31 to the load pressure chamber 65 on the outer periphery of the large diameter portion 61. A plurality of slits 66 are formed.

The valve body 60 is urged by a spring 79 whose base end is supported by an inner step portion of the sleeve 64 so that the seat portion 63 comes into contact with an edge portion between the intermediate chamber 25 and the outlet port 31. I have.

Further, the outer diameter D3 of the small diameter portion 62 of the valve body 60 and the inner diameter d2 of the large diameter portion 61 (= the stem portion 53 of the flow dividing valve 22a)
(Described later) are manufactured to have the same dimensions, thereby eliminating the influence of the force acting on the valve body 60 due to the hydraulic pressure in the control chamber 27.

The valve body 26 of the flow dividing valve 22a has a land 52 in which a metering notch 51 is formed and a stem 53, and the stem 53 is provided in the valve body 6 of the hold check valve 32a.
The control chamber 27 is formed in the valve body 60 of the hold check valve 32a so as to be slidably fitted to the large-diameter portion 61 of the hold check valve 32a. The oil passage slit 28 is formed on the outer periphery of the stem portion 53 of the flow dividing valve 22a, and the hydraulic pressure of the intermediate chamber 25 is guided to the control chamber 27 through the oil passage slit 28 when the flow dividing valve 22a operates.

The control chamber 27 communicates with a spring chamber 72 located behind the small diameter portion 62 of the hold check valve 32a. The spring chamber 72 is connected to the load pressure through the oil passage 30 provided as a small hole in the sleeve 64. It is connected to the detection oil passage 7.

A fixed plug 75 extends in the axial direction from the spring chamber 72 through the inside of the small diameter portion 62 of the valve body 60, and a base end of the fixed plug 75 is held by a sleeve 64. A spring receiving portion 76 is provided near the distal end of the fixed plug 75. The spring receiving portion 76 urges the valve element 26 of the flow dividing valve 22a against the inner wall 77 of the inlet port 24 to hold the valve element 26 in the closed position. Spring 78 is supported.

One end of the oil passage slit 28 formed on the outer periphery of the stem portion 53 of the flow dividing valve 22a opens into the intermediate chamber 25,
The other end is cut in the middle of the stem portion 53, and when the valve body 26 is in the closed position, the above-described wrap portion 29 that blocks communication between the oil passage slit 28 and the control chamber 27 is formed. The oil passage slit 28 opens into the control chamber 27 when the stroke is equal to or more than the lap amount X from the illustrated closed position.

The intermediate chamber 25 is larger than the outer diameter d1 of the land 52 and the outer diameter D2 of the large diameter portion 61 of the hold check valve 32a.
It has a smaller inner diameter D1 so that the hold check valve 32a can reliably perform the hold check function.

As described above, by integrating various valve functions in the valve assembly 56a, the control valve 2-
1 can be made compact and simple.

Returning to FIG. 4, the main spool 13 has the above-described inlet ports 18a, 18b and outlet ports 20a, 20a.
0b and oil passages 19a, 19b as internal passages are formed, and the inlet ports 18a, 18b are always open to the meter-in actuator ports Ain, Bin, respectively.
Further, the outermost land 104-
3, 104-3, the main spool 13 is located at the return ports Ra and Rb when the main spool 13 is at the illustrated neutral position, and the return ports Ra and Rb and the meter-out actuator are positioned as the main spool 13 strokes from the illustrated neutral position. Housing land 3 between ports Aout and Bout
7a, 37b annular groove 3 of predetermined width drawn into the sliding surface
8a and 38b are formed, and the outlet ports 20a and 20b open to the annular grooves 38a and 38b.

FIG. 6 shows the annular groove 38a and the outlet port 20a.
FIG. While the main spool 13 is within the stroke range of (a), the annular groove 38a is completely opened to the return port Ra, and the main spool 13 is moved to (a).
When the stroke exceeds the range, the annular groove 38a is drawn into the sliding surface of the land 37a, and the main spool 13
When the stroke exceeds the range of (b), the annular groove 38a is completely drawn into the sliding surface of the land 37a. The stroke range (b) corresponds to the stroke S2 shown in FIG. As a result, the outlet port 20 opening to the annular groove 38a
a is a combination of the main spool 1 with the annular groove 38.
When the main spool 13 is in the illustrated neutral position, the pressure relief circuit is provided. In addition, as the main spool 13 is stroked from the illustrated neutral position, the main spool 13 is narrowed by the housing land portion 37a, and the bleed-off having an opening characteristic as shown in FIG. Functions as a variable aperture unit. Exit port 20b on opposite side
The same is true for

The operation of the hydraulic circuit device configured as described above will be described.

In the control valve 2-1, when the main spool 13 of the spool valve 12 is moved, for example, to the right in the drawing, the main spool 1 is moved over a stroke S1 shown in FIG.
The notch 14a for meter-in flow control provided on the left side of FIG. 3 is opened, and the discharge oil of the hydraulic pump 1 flows from the pump port P to the actuator port Ain and the oil passage 23a via the notch 14a. At this time, the state between the pump port P and the actuator port Bin on the right side in the drawing is in a cutoff state. Also, the actuator port Bou on the right side of the figure is shown.
The t and the return port Rb communicate with each other via a notch 15b for meter-out flow rate control, and the connection between the actuator port Aout and the return port Ra on the left side in the drawing is in a cutoff state. Oilway 2
The discharge oil that has flowed into the inlet port 3a is supplied to the diversion valve 2
2a is opened, and the pressure is set in the intermediate chamber 25, the oil passage slit 2
8, the pressure is detected by the load pressure detecting oil passage 7 via the control chamber 27 and the oil passage 30, and the displacement of the hydraulic pump 1 is controlled by the displacement controller 8 so that the discharge pressure becomes higher than the detected pressure by a predetermined value.
When the discharge pressure of the hydraulic pump 1 becomes higher than the pressure of the outlet port 31 of the hold check valve 32a, the hold check valve 32a opens, and the discharge oil from the hydraulic pump 1 flows from the intermediate chamber 25 to the outlet port 31, and the actuator port It is supplied to the actuator 3-1 via 33a. Return oil from the actuator 3-1 is returned from the actuator port Bout on the right side of the drawing via the actuator port 33b to the return port Rb via a meter-out flow control notch 15b provided on the main spool 13.
From the tank to the tank T.

When both the spool valves 12 and 12 of the control valves 2-1 and 2-2 are simultaneously operated, the high load pressure side flow dividing valve 22a operates and the two control valves 2 and 2 are operated.
At -1, 2-2, the pressure at the inlet port 24 of the flow dividing valve 22a is controlled to be the same, and the actuators 3-1 and 3-2 are controlled.
-2 regardless of the magnitude of the load pressure.
The pressure oil from the hydraulic pump 1 can be supplied at a split ratio proportional to the opening area of the notches 14a, 14a for the meter-in flow rate control.

In the above operation process, as the main spool 13 strokes rightward in the figure, the outlet port 20a (variable bleed-off restrictor) as shown in FIG.
Has a reduced opening area and is fully closed at stroke S2. That is, between the strokes S1 and S2, both the notch 14a for controlling the meter-in flow rate and the outlet port 20a (variable bleed-off restrictor) are opened. For this reason, the actuator 3-1 is, for example, a swing body (inertia body) of a hydraulic shovel.
When an excessive amount of oil that cannot be consumed by the actuator 3-1 occurs at the initial stage of driving the revolving body, the excess flow rate is supplied from the inlet port 18a to the tank via the internal passage 19a and the outlet port 20a. Since the fluid flows back (bleeds) to T, a sharp rise in drive pressure can be avoided.

The inlet port 18a opens to the meter-in actuator port Ain, and the flow dividing valve 22a detects the pressure of the intermediate chamber 25 connected through the actuator port Ain oil passage 23a by the oil passage slit 28, and detects the load pressure. Since it is guided to the oil passage 7, the load pressure detection oil passage 7 has an inlet port 18a, an internal passage 19a, and an outlet port 2a.
The pressure modulated by bleeding the excess oil amount according to 0a is detected as the load pressure, and the displacement controller 8 controls the displacement of the hydraulic pump 1 so that the pump discharge pressure becomes higher than the modulated pressure. For this reason, the discharge pressure of the hydraulic pump 1 gradually rises in accordance with the modulated pressure, and a sudden rise in drive pressure can be prevented by controlling the pump discharge pressure in addition to the bleeding of the pressure oil.

On the other hand, the main spool 1 of the spool valve 12
When 3 is in the neutral position, the outlet port 20a (variable bleed-off restrictor) is connected to the return port R (Ra in FIG. 4).
The inlet port 18a of the oil passage 19a is open upstream of the hold check valve 32a (between the notch 14a for meter-in flow rate control and the hold check valve 32a). Does not flow out of the outlet port 20a (variable throttle portion of bleed-off) into the tank T, and the runaway of the load can be avoided without the need for a counterbalance valve.

As described above, according to the present embodiment, in the hydraulic circuit device equipped with the load sensing system, the bleed-off variable throttle section (exit port 20a) causes a sudden increase in the drive pressure at the initial drive of the inertial body. , And runaway of the load can be avoided without the need for a counterbalance valve. Further, since the bleed-off variable throttle unit is provided by using the pressure release circuit, the bleed-off circuit can be provided without increasing the cost.

Further, since the modulated pressure between the notch (variable throttle portion) 14a of the meter-in flow rate control of the spool valve 12 and the hold check valve 32a is detected, and the discharge pressure of the hydraulic pump 1 is controlled according to this pressure. Also, a sudden increase in the driving pressure can be prevented by controlling the pump discharge pressure.

Since the flow dividing valve 22a has a check valve function and the flow dividing valve 22a and the hold check valve 32a are configured as a valve assembly, the control valve 2-1 can be made compact and simple.

In the above embodiment, the capacity of the hydraulic pump 1 is set as load sensing control means so that the pump discharge pressure becomes higher than the control pressure based on the maximum load pressure (the pressure of the load pressure detecting oil passage 7) by a predetermined value. Although the displacement controller 8 for controlling is used, an unload valve is connected to the discharge oil passage of the hydraulic pump 1, control pressure is guided to the unload valve, and the hydraulic pump 1 is controlled.
The discharge pressure of the hydraulic pump 1 may be controlled so that the discharge pressure of the hydraulic pump 1 becomes higher than the control pressure by a predetermined value. The same effect can be obtained by using the control valve in such a hydraulic circuit device.

[0066]

According to the present invention, in a hydraulic circuit device equipped with a load sensing system, a rapid increase in drive pressure at the time of initial drive of an inertial body can be prevented by a variable bleed-off throttle, and a counterbalance valve is provided. The runaway of the load can be avoided without the need.

Further, since the pressure modulated by the bleed-off variable throttle section is detected and the discharge pressure of the hydraulic pump is controlled in accordance with this pressure, a sudden increase in drive pressure can be prevented by controlling the pump discharge pressure. it can.

Since the flow dividing valve has a check valve function, the control valve can be made compact and simple.

Further, since the bleed-off variable throttle section is provided by utilizing the pressure relief circuit, the bleed-off circuit can be provided without increasing the cost.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view showing a flow dividing valve portion.

FIG. 3 is a diagram showing a relationship between aperture characteristics of a variable throttle unit for meter-in flow rate control and a variable throttle unit for bleed-off.

FIG. 4 is a cross-sectional view showing an actual configuration example of a control valve.

FIG. 5 is an enlarged view showing details of a flow dividing valve and a hold check valve.

FIG. 6 is an enlarged view of an annular groove and an outlet port on one side formed in a main spool.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Hydraulic pump 1a Swash plate 1b Discharge oil passage 2-1 and 2-2 Control valve 3-1 and 3-2 Actuator 7 Load pressure detection oil passage 8 Capacity controller 10 Parallel oil passage 11 Return oil passage 12 Spool valve 13 Main Spools 14a, 14b Notches for meter-in flow rate control (variable throttle section) 15a, 15b Notches for meter-out flow rate control (variable throttle section) 18a, 18b Inlet ports 19a, 19b Oil passages 20a, 20b as internal passages Outlet ports ( Bleed-off variable throttle section) 22a, 22b Dividing valve 24 Inlet port 25 Outlet port (intermediate chamber) 26 Valve body 27 Control chamber 28 Oil passage slit 29 Lapping part 30 Oil passage 32a, 32b Hold check valve 33a, 33b For connection Actuator port 34a, 34b Oil passage

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshizumi Nishimura 650, Kandate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura Plant (72) Inventor Mitsuhisa Togasaki 650, Kanda-machi, Tsuchiura-shi, Ibaraki F-term in Tsuchiura Plant (reference) 3H089 AA27 CC01 CC08 CC11 DA03 DB03 DB33 DB47 DB49 DB75 EE07 FF07 GG02 HH05 JJ02

Claims (6)

[Claims] A hydraulic pump; a plurality of actuators driven by hydraulic oil discharged from the hydraulic pump; a plurality of control valves for controlling a flow rate of hydraulic oil supplied to the plurality of actuators; Load sensing control means for controlling a discharge pressure of the hydraulic pump to be higher than the control pressure, based on a control pressure based on the maximum load pressure of the actuator, and the plurality of control valves each include a meter-in flow rate control. And a hold check valve located downstream of the variable throttle portion for meter-in flow rate control of the spool valve, wherein at least one of the plurality of control valves is provided. However, between the variable throttle portion for meter-in flow rate control of the spool valve and the hold check valve A branch oil passage branching off from the oil passage and having a downstream end connected to the low-pressure circuit; and a branch oil passage provided in the branch oil passage for reducing an opening area as the spool valve strokes from a neutral position and for controlling the meter-in flow rate. And a bleed-off variable restrictor that partially overlaps and opens. 2. The hydraulic circuit device according to claim 1, wherein when the load pressure of the actuator to which the hydraulic circuit device is related is the maximum load pressure, the variable check portion for meter-in flow rate control of the spool valve and the hold check valve are connected. A hydraulic circuit device provided with a means for detecting a pressure of an oil passage between the two as the load pressure. 3. The hydraulic circuit device according to claim 1, wherein a flow dividing valve is disposed in an oil passage between the variable throttle section for meter-in flow rate control of the spool valve and the hold check valve.
A hydraulic circuit device wherein the branch oil passage is branched on the inlet side of the flow dividing valve. 4. The variable throttle section for meter-in flow rate control of the spool valve and the hold when the load pressure of an actuator associated with the flow dividing valve is the maximum load pressure, in the hydraulic circuit device according to claim 3. A hydraulic circuit device having a check valve function for detecting the pressure of an oil passage between the check valve and the check valve as the load pressure. 5. The hydraulic circuit device according to claim 1, wherein the branch oil passage is constituted by an internal passage as a pressure oil draining circuit of the spool valve, and the variable bleed-off restrictor is connected to an outlet port of the internal passage. A hydraulic circuit device provided in: 6. The meter-out flow control according to claim 1, further comprising a return oil passage branched from between the hold check valve and the hydraulic actuator, and the return oil passage provided to the spool valve. A hydraulic circuit device connected to the tank via the variable throttle section.