JPH028503A - Pressure liquid directional control valve device - Google Patents

Abstract

PURPOSE:To perform satisfactory speed control in either case of meter-in or meter-out, by opening a meter-out poppet valve prior to a meter-in poppet valve, and hereafter controlling lift quantity of both poppet valves. CONSTITUTION:Meter-in poppet valves 36a, 36b and meter-out poppet valves 42a, 42b are provided in a valve constructing body 14, meter-out pilot valve bodies 15a, 15b and meter-in pilot spools 96a, 96b are connected to respective poppet valves 36a, 36b, 42a, 42b, and pressure regulating valves 52a, 52b are connected to respective pilot spools 43a, 43b, 96a, 96b. At controlling flow, the meter-out poppet valves 42a, 42b are opened prior to the meter-in poppet valves 36a, 36b with pressure regulating valves 52a, 52b, and hereafter lift quantities of both poppet valves 42a, 42b, 36a, 36b are controlled. Consequently, satisfactory speed control can be always performed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pressure hydraulic control valve device that controls the driving direction and speed of an actuator by pilot operation.
More specifically, the present invention relates to improving the controllability of the lift amount of a meter-out poppet valve and simplifying the pressure fluid circuit inside the valve structure.

[Prior art] Generally speaking, this type of valve device is disclosed in Japanese Patent Application Laid-Open No. 10300-1983.
A "hydraulic control device" described in Publication No. 1 is known.

In other words, in this hydraulic control device, when the pilot spool of the meter-in poppet valve operates, the pressure in the secondary passage increases, and this pressure operates the pilot spool of the meter-out poppet valve to lift and open the meter-out poppet valve. After that, when the actuator speed increases and the flow rate on the supply side becomes insufficient and the pressure in the secondary passage decreases, the meter-out pilot spool returns to its original position, closing the meter-out poppet valve and braking the actuator. , in which case the meter-out poppet valve is configured to act as a counterbalance.

[Problem to be solved by the invention]

However, in conventional pressure liquid directional control valve devices, the opening degree of the proportional control valve located on the supply side responds to the input signal;
The opening degree (lift amount) of the meter-out poppet valve provided on the discharge side depends on the pressure on the actuator port side of the load. Therefore, vibrations are likely to occur due to load fluctuations, etc.
As a preventive measure, for example, by narrowing the orifice of the make-out poppet valve, a damping effect can be obtained, but this has the disadvantage that the responsiveness of the valve operation is impaired.

Furthermore, the pressure fluid circuit in the valve component of the conventional control valve device is logically controlled by pilot pressure, and therefore has the disadvantage of having a complicated circuit configuration. Furthermore, when a pressure liquid directional control valve device equipped with a load sensing device is used, cavitation tends to occur in the supply side passage to the actuator during make-out flow rate control due to the nature of the load sensing mechanism.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to open a meter-out poppet valve before a meter-in poppet valve by inputting an electrical signal, and then open both poppet valves without using the complicated structure found in the prior art. An object of the present invention is to provide a hydraulic directional control valve device capable of controlling the reflow/drawing of an actuator according to the magnitude of an electric signal and performing good speed control of an actuator in both meter-out and meter-in cases.

(Means for Solving the Problems) A pressure fluid directional control valve device according to the present invention includes a variable displacement pump, an actuator having a pair of pressure fluid inlets and inlets, and a valve structure for driving and controlling the actuator. The valve structure has a pressure liquid inlet connected to the discharge port of the variable displacement pump, a pair of actuator boats connected to the pressure liquid outlet of the actuator, and one of the actuator ports. A discharge port for discharging the pressure fluid discharged from the actuator into the tank is provided, and a pair of primary passages communicating with the pressure fluid inlet are provided so as to be able to communicate with the primary passages via a valve. a pair of secondary passages, a pair of meter-in pilot spools that adjust the pilot flow rate that passes through the orifice and flows from the primary passage to the secondary passage; and a meter-in pilot spool that controls the lift amount by adjusting the pilot flow rate; A pair of meter-in poppet valves that control the flow rate from the passage to the secondary passage, and a load check valve that opens when the pressure reaches a set pressure so that the pressure liquid whose flow rate is controlled by the meter-in poppet valve flows out only to the actuator port. , a pair of meter-out pilot spools for adjusting a pilot flow pile passing through the orifice and flowing from the actuator port to the tank; and an outlet passage leading from the actuator port to the discharge port, the lift m being controlled by adjusting the pilot flow pile. The variable displacement pump is provided with a pair of meter-out poppet valves that control outflow to the pump, and a pair of drive sources that generate an output in response to an electrical input signal, and the variable displacement pump is provided with a high-pressure side of the pair of secondary passages. A load sensing device is provided to detect the pressure of the variable displacement heavy pump and adjust the discharge amount of the variable displacement heavy pump so that the discharge pressure of the variable displacement pump becomes a constant pressure higher than the detected high pressure side pressure, and the load sensing device detects the pressure of the variable displacement pump or the A pressure regulating valve is provided that uses the pressure of the next passage as a primary pressure and that uses a pressure proportional to the output of the drive source as a secondary pressure, and controls the meter-in pilot spool and the meter-out pilot spool using the secondary pressure. The opening of the meter-out poppet valve is controlled by the meter-in poppet valve by causing the flow of pressurized fluid passing through the orifice provided in the meter-in poppet valve to precede the flow of pressure fluid passing through the orifice provided in the meter-in poppet valve. It is characterized by being configured to precede the opening of the valve.

Further, in the pressure liquid directional control valve device, it is preferable to provide a back pressure generating device that generates back pressure on the outlet passage side between the outlet passage and the discharge port to the tank.

Furthermore, a pilot pump may be provided to provide a pilot pressure of the primary pressure to the pressure regulating valve.

[Function] According to the pressure liquid directional control valve device according to the present invention, the pressure liquid discharged from the variable displacement pump is caused to flow from the primary passage to the secondary passage by the opening of the meter-in poppet valve via the pressure compensating spool. After the load check valve is opened and the pressure fluid flows out from the actuator port on the pressure fluid supply side and is supplied to the actuator, the pressure fluid discharged from the actuator is transferred to the tank via the meter-out poppet valve that is opened. leaked to.

In this case, the electric input signal activates the drive source to move the pressure regulating valve, and the pressure regulating valve obtains a secondary pressure proportional to the output of the drive source, thereby controlling the meter out pilot spool. After opening the variable orifice of the meter-out pilot spool of the lever to open the meter-out poppet valve, the meter-in pilot spool on the pressure fluid supply side is controlled by the action of the secondary pressure to open the meter-in poppet valve. I can do it.

[Embodiments] Next, embodiments according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of a pressure fluid directional control valve device according to the present invention, and is a sectional view of a main part of the pressure fluid directional control valve device.

In the figure, 10 is a variable displacement pump, 12 is an actuator capable of reciprocating, and 14 is a valve structure. A meter-out pilot valve body 15a incorporating a pilot control system for controlling.

15b.

Further, 16 is a pressure fluid (hereinafter referred to as pressure oil) inlet connected to the discharge boat 18 of the variable oversleeping pump 10, 2o is a tank, 22 is a pressure oil outlet connected to the tank 20, and 24
are outlet passages connected to the pressure oil outlet 22, 26a and 26b;
shows a pair of actuator ports through which pressure oil is supplied to the actuator 12 or discharged oil from the actuator 12 flows in, and these ports are provided in the valve body 15 of the valve structure 14. Further, a valve chamber 28 is formed in the pressure oil inlet 16, and a variable throttle 32 is provided in the valve chamber 28.
A pressure compensating spool 30 provided with a pressure compensating spool 30 is inserted so as to be movable in the vertical direction in the figure.

On both sides of this pressure compensating spool 30 are the variable throttles 32.
A pair of primary passages 34 communicating with the pressure oil inlet 16 via
a and 34b are provided. Furthermore, the primary passage 34
a.

34b each have a pair of meter-in poppet valves 36a.
, 36b are provided, and a pair of secondary passages 38a, 38b through which pressure oil whose flow rate is controlled thereby flows is provided on the downstream side thereof, and further downstream thereof is the secondary passage 38a.

38b to said actuator port 26a.

Pressure oil flows out only to actuator port 26b.
Load check valves 40a and 40b are provided to cut off the backflow from the flowcharts a and 26b. Also, the load check valve 40a.

The pressure oil that has passed through 40b is transferred to the actuator port 26.
a, 26b, and a pressure oil outlet 2 that communicates with the tank 20 from the actuator ports 26a, 26b.
A pair of meter-out poppet valves to control the flow to 2
2a, 42b are the actuator ports 26a, 26
It is provided near b. The various valves incorporated into the valve body 15 in this way are a meter-out pilot valve body 15a, which will be described later.

It is controlled by a pilot control system built into 15b. Note that the meter-out pilot valve bodies 15a and 15b have the same structure and are symmetrical.

Meter-out pilot valve body 15a.

15b includes a meter-out pilot spool 43a,
43b is slidably incorporated into this meter-out pilot spool 43a.

At one end of 43b is a spring 94 that communicates with the tank 2o.
4a and 44b are provided.

Inside the spring chambers 44a and 44b are small springs 46a whose mounting force is determined by a spring constant.

46b and a large spring 48 with zero mounting force and a large spring constant.
a, 48bS are interposed, and spring chambers 44a, 4
Caps 50a, 50b connecting r11 to 4b and the large spring 48a.

There is a gap 1 between the free end of 48b. 1ta
ib is formed. This gap! , l is before la
1b Meter out pilot spool 43a.

■Groove-shaped variable orifices 85a, 8 carved in 43b
5b is the spring 144a.

The stroke is set to be approximately the same as the stroke 128°'2b until opening at 44b.

In addition, meter out pilot spools 43a, 43b
Spring chamber 44a in.

On the opposite side of 44b is a pilot passage 54a on which the secondary pressure of pressure regulating valves 52a and 52b acts.

54b. The pressure regulating valves 52a, 52b
Solenoids 55a and 55bl, which are driving sources for operating the pressure regulating valves 52a and 52b, are provided on one end side, and the one end is normally operated by the biasing force of weak springs 56a and 56b that bias the pressure regulating valves 52a and 52b. The actuating shafts 58a and 58b of the solenoids 55a and 55b are kept in contact with each other. That is, the state shown in the figure is the pressure regulating valve 52a.

52b is an operating shaft 58a of the solenoids 55a, 55b by the springs 56a, 56b.

58b side, and the pressure regulating valves 52a, 5
Solenoid 55a in 2b.

Secondary pressure is acting on the end face opposite to 55b.

A land 60a is provided at the center of the pressure regulating valves 52a, 52b.
, 60b are provided, and rooms are formed on the left and right with these lands 60a and 60b as boundaries. Furthermore, the pressure regulating valve 5
2a.

A pilot passage 62 is provided in one of the chambers formed in 52b.
a, 62bIOfi communication, this pilot passage 62a
, 62b communicate with the primary passages 34a, 34b, and the other room has drain passages 64a, 64 communicating with the tank 20.
b is communicating.

Pressure regulating valve 52a in the state shown in the figure.

The lands 60a, 60b of 52b block the pilot passages 62a, 62b on the primary pressure side and the pilot passages 54a, 54b on the secondary pressure side, and the pilot passages 54a, 54b on the secondary pressure side are connected to the drain passage 64a.

64b.

66, 68 is a Settle valve, and 66 is a pair of secondary passages 38a.
, 38b transmits the pressure on the high pressure side to the pilot passage 70, and 68 transmits the pressure on the high pressure side of the pilot boat 74 connected to the high pressure side of the pair of secondary passages of the valve body 72 provided separately from the valve component 14. The higher pressure between the pressure and the pilot passage 70 pressure is transmitted to the pilot boat 78 of the load sensing device 76.

The load sensing device 76 provided in the variable displacement pump 10 is a device that adjusts the pump discharge so that the discharge pressure of the variable displacement pump is higher than the pressure of the pilot boat 78 of the load sensing device 76 by a preset constant pressure. (In this case, the preset constant pressure is referred to as sensing pressure).

However, when the valve body 72 and the valve component 15 are operated simultaneously, when the load pressure on the valve body 72 is greater than the load pressure on the valve component 15, the pressure compensating spool 30 is moved to the primary passage 34a.

34b is received by the stepped portion formed on the spool 30 in the valve chamber 28, and the pressure of the secondary passages 38a, 38b is received by the lower end surface, so the pressure compensating spool 30 always maintains this spool 30. The pressure fluid inlet 16 and the primary passage 34a are moved downward by the variable throttle 32 against the upwardly biased spring 8o.

34b is narrowed, so the primary passage 34a.

34b can be reduced.

In this case, the primary passages 34a, 34b and the secondary passages 38a, 38 required to make the pressure compensating spool 30 Fr1ll.
By setting the differential pressure (pressure compensating spool control pressure) between the two pressure points slightly higher than the load sensing pressure, even if the load pressure on the valve body 72 side becomes large, the meter-in poppet valve 36a, The flow rate through 36b does not increase and the speed of actuator 12 by valve arrangement 15 changes little.

On the other hand, 82a and 82b are relief pistons, which act to prevent the pressure in the actuator ports 26a and 26b from exceeding a predetermined pressure.

Next is the meter-out poppet valve 42a.

The operating principle of the meter-out pilot spools 43a and 43b that control the lift of the meter-out pilot spool 42b will be explained in detail.

The operating shafts 58a, 58b are actuated by the electric signals input to the solenoids 55a, 55b, and the pressure regulating valves 52a, 52b are actuated.
(to the right in FIG. 1) to apply the pressure in the pilot passages 62a, 62b on the primary pressure side to the end surfaces of the meter-out pilot spools 43a, 43b opposite to the springs 44a, 44b.

As a result, the meter out pilot spool 43a,
43b is a biased orifice 85a whose opening degree is variable according to the pressurizing pressure.

85b and meter out pilot spool 438.
43b to the tank 20.

Also, meter-out poppet valve 42a by pressure exerted by actuator 12 on actuator port 26a or 26b.

The pressure oil in the back chambers 84a and 84b of 42b is transferred to the meter-out pilot spool 43a.

43b to tank 20 via variable orifice 858.85b and meter-out poppet valves 42a, 42b.
is lifted, and the pressure oil is returned to the tank 20. In this case, when the meter-out poppet valves 42a, 42b lift, the variable orifices 86a, 86b open and the opening area increases according to the amount of lift of the meter-out poppet valves 42a, 42b. However, the meter-out poppet valve 42a,
Annular area on actuator port 26a, 26b side of 42b ・・・・・・・・・・・・・・・・・・−
...Pressure receiving area on the A1 back chamber 84a, 84b side...
A2 actuator port 26a, 26b pressure
・・ ・・ ・・ ・・ ・・ ・・
... ... ... ... P1 back chamber 84a, 84
Pressure of b......P2 meter out pilot spool 43a.

Pressure acting on the end face of P 43b...Opening area constant of variable orifices 85a, 85b of variable orifices 86a, 86b......
...K (=A2/A1), and the spring 88a
, 88b is small, so it is ignored, and considering the equilibrium state, Pl /P2 = A2 /A1 = K...
・(1), variable orifices 85a, 85b and 86
The flow rates passing through a and 86b are equal, (flow rate) 2 C
/) Since (opening area) 2 x (pressure difference), a12 X (Pl-P2) = a22XP2,
Meter-out poppet valve 42a.

Variable orifice 86a determined by lift m of 42b
, 86b is uniquely determined by the area a2 of the variable orifices 50a, 50b, which is determined by the pressure P acting on the end faces of the meter-out pilot spools 43a, 43b.

Next is the meter poppet valve 36a.

The lift recovery tl1 mechanism of 36b will be explained focusing on the valve on the right side in FIG.

Now, the operating shaft 58b moves in accordance with the input electric signal applied to the solenoid 55b, and the movement of the pressure regulating valve 52b causes the pilot pressure in the pilot passage 54b on the secondary pressure side to be applied to the meter-in pilot spool 96a via the pilot passage 90b. Meter-in pilot boat 92 on the back
transmitted to a. As a result, the meter-in pilot spool 96a is biased in response via the piston 94a, increasing the elastic force of the spring 98a and increasing the pressure in the annular chamber 100.
The hole 102a of a is opened. The pressure oil that has passed through the orifice 104a of the meter-in poppet valve 36a on the primary passage 34a side flows far to the secondary passage 38a through the hole 106a, and the pressure and spring that are maintained in the back chamber 108a depend on the degree of opening of the hole 1028. 98a to close the meter-in poppet valve 36a is transmitted through the primary passage 34a.
The meter-in-poppet valve 36a lifts until it balances with the force trying to open the valve at a pressure of . In this equilibrium state, the force of the spring 98a that the meter-in pilot spool 96a receives is proportional to the lift amount of the meter-in poppet valve 36a.

Therefore, the amount of lift of the meter-in poppet valve 36a is proportional to the force output from the output shaft 58b in response to the input electric signal.

That is, when the solenoid 55b receives an electrical input signal and a force is applied to the right end surface of the pressure regulating valve 52b by the output shaft 58b, the pressure regulating valve 52b moves to the left against the spring 56b, and is moved to the primary pressure side. Pilot passage 62b
Since the secondary pressure side pilot passage 54b and the secondary pressure side pilot passage 54b are in communication with each other and the secondary pressure side pilot passage 54b and the drain passage 64b are narrowed, the pressure of the secondary pressure side pilot passage 54b is upper bound, and the pressure of this pilot passage 54b is equal to the above-mentioned level. Pressure regulating valve 5
2b, the pressure regulating valve maintains equilibrium when the pressure in the secondary pressure side pilot passage 54b becomes equal to (output of the solenoid)/(pressure receiving area of the pressure regulating valve).

Therefore, the pressure in the secondary pressure side pilot passage 54b can be made proportional to the output of the solenoid 55b.

The pressure in the secondary pressure side pilot passage 54b acts on the lower end surface of the meter-out pilot spool 43b, bends the spring 461), moves the meter-out pilot spool 43b upward, and the variable orifice 85b opens into the spring chamber 44b. . Due to this opening, the pressure oil in the actuator port 26b flows into the tank 20 through the variable orifice 86b, the hole 110b, the back chamber 84t), the pilot passage 112b, the variable orifice 85b, and the spring chamber 48b, and there is a differential pressure in front of the orifice 86b. , and a lift force is generated in the meter-out poppet valve 42b.

When the pressure in the secondary pressure side pilot passage 54b further increases, the large spring 48b comes into contact with the bottom surface of the cap 50b due to the upward movement of the meter-out pilot spool 43b, and the force of this large spring 48b is also applied to the meter-out pilot spool 43b. Next pressure side pilot passage 5
The amount of movement of the meter-out pilot spool 43b gradually increases as the pressure of the meter-out pilot spool 43b increases.

As mentioned above, the meter-out poppet valve 42b has the opening area a1 of the variable orifice 86b and the variable orifice 85.
The variable orifice 86b increases in accordance with the lift amount of the meter-out poppet valve 43b, and the variable orifice 85b is connected to the meter-out pilot spool. Since the amount of movement of the meter-out poppet valve 42b increases by fP, the amount of lift of the meter-out poppet valve 42b can be controlled by adjusting the pressure of the secondary pressure side pilot passage 54b.

After the meter-out poppet valve 42b is lifted to form a flow path from the actuator port 26b to the outlet passage 24, the pressure in the secondary pressure-side pilot passage 54b reaches a predetermined value (the spring 98 of the meter-in poppet valve 36a).
When the mounting force (a)/pressure receiving area of the piston 94a is exceeded, the secondary pressure side pilot passage 54b is connected to the meter-in pilot boat 92a, so the meter-in poppet valve 36a is moved to the meter-in pilot spool by the acting force of the piston 94a. 96a to open the secondary passage 38.
The hole 106a communicating with the tank 20 is closed, and the pilot oil flows from the primary passage 34a through the orifice 104a, the back chamber 108a, the pilot passage 102a, and the annular chamber 100a, and the meter impoppet valve 36a is opened according to the principle described above. The lift area can be controlled.

As a result, the flow rate proportional to the opening area of the meter-in-poppet valve 36a determined by the lift valve is adjusted to the primary passage 34a.
It flows out from the air to the secondary passage 38a, and further lifts the load check valve 40a to flow out from the actuator port 26a and actuate the actuator 12.

Next, a second embodiment will be explained with reference to FIG. For convenience of explanation, the same reference numerals are given to the same parts as in the structure of the first embodiment shown in FIG. 1, and the explanation thereof will be omitted.

In the figure, reference numeral 120 designates a check valve that allows pressure oil to flow out from the outlet passage 24 to the pressure oil outlet 122 that discharges it into the tank 20, and also blocks oil from flowing from this outlet 122 to the outlet passage 24. Exit passage 24 with power
This causes back pressure and lag.

As described above, the 0-dosensing device 76 adjusts the discharge amount of the variable discharge pump 1o so that the pressure in the primary passages 34a, 34b is greater than the pressure in the secondary passages 38a, 38b by a certain value. For example, when raising the boom of a power excavator, if meter-in flow control is performed, the flow rate control can be performed satisfactorily, but if meter-out flow control is performed to lower the boom, the boom will be lowered. The speed becomes excessive and the supply flow rate of the pump is insufficient, causing the meter impoppet valve 36a.

The secondary passages 38a and 38b on the 36b side become negative pressure. In this case, the load sensing device 76
4b and secondary passage 38a.

Since the pressure difference with 38b is larger than the specified value, it is determined that the discharge amount of the variable displacement pump 10 is excessive, and the pump discharge amount is decreased. For this reason, the negative pressure on the secondary passage side is further amplified, which may cause problems such as cavitation on the supply side of the actuator 12.

However, as shown in FIG. 2, in the second embodiment, by suitably selecting the spring 124 of the check valve 120, back pressure is applied to the outlet passage 24, and the pressure at the supply side actuator port is lowered to the outlet. When the pressure drops below the pressure in the passage 24, the meter-out poppet valve 42 on the supply side is lifted and the discharged oil from the actuator 12 flows from the outlet passage 22 into the actuator port on the supply side, thereby reducing the load at the actuator port on the supply side. This can prevent the occurrence of cavitation.

Next, the third embodiment will be explained with reference to FIG.
Identical parts in FIG. 8i are given the same reference numerals and their explanations will be omitted.

In the figure, a pilot passage 130 that supplies pressure oil discharged from a discharge 0128 of a variable displacement pump 126 provided separately from the variable displacement pump 10 is connected to the primary pressure side pilot passages 62a and 62b of the pressure regulating valve 52b. , meter-in pilot spool 96a.

96b and meter-out pilot spool 43a,
Relief valve 132 provides the pressure necessary to operate 43b.
It can be set by

〔Effect of the invention〕

As explained above, the pressure fluid directional control valve device according to the present invention includes a variable displacement pump, an actuator having a pair of pressure fluid inlets and inlets, and a valve structure for driving and controlling this actuator. The structure includes a pressure fluid inlet connected to the discharge port of the variable displacement pump, a pair of actuator ports connected to the pressure fluid outlet of the actuator, and a pressure fluid discharge port connected to the actuator port. a pair of primary passages communicating with the pressure liquid inlet, and a pair of secondary passages communicating with the primary passages via a valve. a pair of meter-in pilot spools that adjust the pilot flow rate that passes through the orifice and flows from the primary passage to the secondary passage; a pair of meter-in poppet valves that control the flow rate to the
A load check valve opens when the set pressure is reached so that the pressure liquid whose flow rate is controlled by this meter-in poppet valve flows out only to the actuator port, and a pilot flow rate that passes through the orifice and flows from the actuator port to the tank is adjusted. a pair of meter-out pilot spools configured to adjust the pilot flow rate to control the lift area, and a pair of meter-out poppet valves to control the flow rate from the actuator port to the outlet passageway from the actuator port to the outlet passage; The variable displacement pump is provided with a pair of drive sources that generate an output according to the detected high pressure. A load sensing device is provided that adjusts the discharge amount of the variable displacement pump so that the pressure increases by a certain amount depending on the side pressure, and the pressure of the variable displacement pump or the primary passage is set as the primary pressure and is proportional to the output of the drive source. A pressure regulating valve is provided which uses the pressure as the secondary pressure, and
Next, the meter-in pilot spool and the meter-out pilot spool are controlled by the pressure, and the pressure liquid flows through the orifice provided in the meter-in poppet valve. By arranging the opening of the meter-out poppet valve to precede the opening of the meter-in poppet valve, the controllability of the opening timing in relation to the meter-out and meter-in poppet valves using pilot pressure is greatly improved. This has the advantage of simplifying the circuit configuration within the valve structure.

In addition, by providing a back pressure generator that generates back pressure on the outlet passage side between the outlet passage and the discharge port to the tank, the actuator port on the supply side can also be used when lowering especially heavy waste etc. by the actuator. This has the advantage that it is possible to prevent the generation of negative pressure in the air, and also to prevent the generation of cavitation.

Furthermore, by providing a pilot pump for supplying a pilot pressure of the primary pressure to the pressure regulating valve, there is an advantage that the adjustment of the pilot pressure on the secondary side can be further expanded.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part showing a first embodiment of a hydraulic directional control valve device according to the present invention, FIG. 2 is a cross-sectional view of a main part showing a second embodiment, and FIG. FIG. 2 is a cross-sectional view of main parts showing an example. 10... Variable displacement pump 12... Actuator 14... Valve structure 15... Valve body 15a 1
51)...meter-out pilot valve body 16...pressure oil flow rate 18...discharge boat 20...tank 22...pressure oil outlet 24...outlet passage 26a 26b...actuator port 28...
Valve v30...Pressure compensation spool 32...Variable throttle
34a, 34b...Primary passage 36a 36b
...Meter poppet valve 38a 38b - Secondary passage 40a, 40b...Load check valve 42a 42
b...Meter out poppet valve 43a, 43b...
・Meter out pilot spool 44a 44b...
・Spring chambers 46a 46b...Small springs 48a 48b...Large springs 50a 50b...Caps 52a, 52b...
Pressure regulating valves 54a 54b...Pilot passages 55a 55b...Solenoids 56a 56b...Springs 58a 58b...Operation@60a, 60b...
Lands 62a, 62b...Pilot passage 64a,
64b...Drain passages 66, 68...Sillage valve 70...Pilot passage 72...Valve body 74.78...Pilot boat 76...Load sensing device 80...Springs 82a, 82b. ...Relief pistons 84a, 84b
--- Back stiffeners 85a, 85b, 86a, 86b --- Variable orifices 88a, 88b --- Spring 90 --- Pilot passages 92a, 92b --- Meter-in pilot boat 9
4a, 94b... Piston 96a, 96b... Meter-in pilot spool 9
8a, 98b...Spring 100a, 100b
... annular chambers 102a, 102b, 106a, 106
b...holes 104a, 104b...orifice 1
08a, 108b...Back chamber 110a, 110b
... Holes 112a, 112b ... Pilot passage ... Check valve ... Spring ... Discharge port ... Relief valve 122 ... Pressure oil outlet 126 ... Variable displacement pump 130 ... pilot passage

Claims (3)

[Claims] (1) A variable displacement pump, an actuator having a pair of pressure liquid inlets and inlets, and a valve structure for driving and controlling the actuator, the valve structure being connected to the discharge port of the variable displacement pump. a pair of actuator ports connected to a pressure fluid inlet of the actuator, and a discharge port for discharging the pressure fluid discharged from the actuator into a tank at one of the actuator ports, and further A pair of primary passages communicating with the pressure fluid inlet, a pair of secondary passages provided in communication with the primary passages via a valve, and passing through an orifice from the primary passage to the secondary passage. a pair of meter-in pilot spools that adjust the pilot flow rate flowing past; a pair of meter-in poppet valves that adjust the pilot flow rate to control the lift amount and control the flow rate from the primary passage to the secondary passage; A load check valve opens when the set pressure is reached so that the pressure fluid whose flow rate is controlled by the meter-in poppet valve flows out only to the actuator port, and a pilot flow rate that passes through the orifice and flows from the actuator port to the tank is adjusted. a pair of meter-out pilot spools; a pair of meter-out poppet valves whose lift amount is controlled by adjusting the pilot flow rate to control the flow rate from the actuator port to the outlet passage; The variable displacement pump is provided with a pair of drive sources that generate an output according to the detected pressure side, and the variable displacement pump detects the pressure on the high pressure side of the pair of secondary passages, and the discharge pressure of the variable displacement pump is set to the detected high pressure side. A load sensing device is provided that adjusts the discharge amount of the variable displacement pump so that the pressure increases by a certain amount, and the variable displacement pump or the first
A pressure regulating valve is provided that uses the pressure of the next passage as a primary pressure and that uses a pressure proportional to the output of the drive source as a secondary pressure, and controls the meter-in pilot spool and the meter-out pilot spool using the secondary pressure. By causing the flow of pressure fluid passing through the orifice provided in the meter-out poppet valve to precede the flow of pressure fluid passing through the orifice provided in the meter-in poppet valve, the opening of the meter-out poppet valve is A pressure liquid directional control valve device characterized in that it is configured to be placed in advance of the entrance of a pet valve. (2) The pressure liquid directional control valve device according to claim 1, further comprising a back pressure generator for generating back pressure on the outlet passage side between the outlet passage and the discharge port to the tank. (3) The pressure liquid directional control valve device according to claim 1, further comprising a pilot pump that provides a pilot pressure of primary pressure to the pressure regulating valve.