JP2698461B2 - Valve device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device that is provided in a hydraulic machine such as a construction machine and controls the driving of a hydraulic actuator, and in particular, secures a function equivalent to a counterbalance valve with a small energy loss. The present invention relates to a valve device for a hydraulic machine that can be used.

Conventional hydraulic circuits of hydraulic machines are generally disclosed in
As described in JP-A-54-129271, a hydraulic pump, an actuator for driving a load (or an inertial body) by the hydraulic oil from the hydraulic pump, for example, a hydraulic motor, and a hydraulic oil supplied to the hydraulic motor from the hydraulic pump. A valve device for controlling the flow and controlling the driving of the hydraulic motor, for example, a directional control valve, and a counter balance provided between the directional control valve and the hydraulic motor to prevent the hydraulic motor from running away due to a load in the direction of gravity. And a valve.

In the hydraulic circuit configured as described above, for example,
When the directional control valve is neutral, the hydraulic oil of the hydraulic pump is not supplied to the hydraulic motor, and the hydraulic motor tries to rotate due to the load in the gravitational direction. , The return oil cannot be discharged, and the hydraulic motor is kept stationary.

When the directional control valve is switched from neutral to one direction, the hydraulic oil of the hydraulic pump is supplied to the hydraulic motor through the main line, and an actuator driving pressure for driving the load generated in the main line, that is, the hydraulic motor The counterbalance valve is also switched in one direction by the driving pressure. As a result, the main line on the discharge side that has been cut off by the counterbalance valve communicates with the tank, the return oil discharged from the hydraulic motor is guided to the tank, and the hydraulic motor moves in the direction corresponding to the switching direction of the directional control valve. For example, the load is driven in a direction against gravity.

When the direction switching valve is switched in the reverse direction, the hydraulic oil of the hydraulic pump is supplied from the main line to the hydraulic motor, and the counterbalance valve is also switched in the reverse direction by the hydraulic motor driving pressure generated in the main line. Thereby, the main pipeline on the discharge side communicates with the tank, the return oil from the hydraulic motor is guided to the tank, and the hydraulic motor drives the load in the direction of gravity. In this case, if the amount of return oil discharged from the hydraulic motor to the discharge main line is greater than the amount of pressurized oil supplied from the supply main line, the hydraulic motor driving pressure in the supply side main line decreases. The counterbalance valve moves in the neutral direction by the force of the spring, and the discharge-side main line is narrowed, thereby limiting the amount of return oil discharged from the hydraulic motor.

In this way, when driving the load in the direction of gravity,
The counterbalance valve is operated so that the hydraulic motor drive pressure corresponding to the spring of the counterbalance valve is generated in the supply side main line, the discharge side main line is narrowed, and the return oil is restricted. The rotation does not exceed the rotation corresponding to the pressure oil supplied from the main pipeline to the hydraulic motor, and the runaway of the hydraulic motor in the load direction due to gravity is prevented. The same applies to a case where another actuator acting with an inertial force is provided instead of the hydraulic motor.

By the way, in the above-mentioned conventional hydraulic circuit, a counterbalance valve is provided in a main line connecting a hydraulic pump and a hydraulic motor, and a large oil amount is controlled by the counterbalance valve. There are many losses. Further, if the pressure loss is reduced, the size of the counterbalance valve is increased, and the manufacturing cost is increased.

Further, since the large oil amount is controlled, the flow force by the pressure oil acting on the counterbalance valve increases. Here, the conventional counterbalance valve has a configuration in which the valve element (mass) is positioned in balance with the pilot pressure (hydraulic motor driving pressure) and the spring force, so that it is essentially a spring-mass system and has a certain resonance. Have a frequency. For this reason,
When the flow force acts, it becomes unstable and it is difficult to obtain stable performance. In addition, it becomes difficult to design components corresponding to the flow force.

In addition, means other than the counterbalance valve are adopted to provide the same function as the counterbalance valve.
There is a valve device described in US Pat. No. 4,425,759. this is,
A check valve that allows only the flow of pressure oil toward the actuator is disposed in each of the two main lines connected to the hydraulic actuator, and a hydraulically controlled type is connected to the branch main line connected to the actuator in parallel with the check valve. Is connected to the return line leading to the outlet port tank. The pressure of the other main line is guided to the control unit of the pressure limiting valve, and the set pressure is changed according to the pressure of the main line.

In this valve device, the pressure oil of the hydraulic pump is supplied from one main line to the actuator via a check valve by switching of the direction switching valve, and the pressure oil discharged from the actuator to the other main line is a pressure oil. It is discharged to the tank through the restriction valve. At this time, if the amount of return oil discharged from the actuator to the discharge-side main line is greater than the amount of pressurized oil supplied from the supply-side main line, the actuator drive pressure in the supply-side main line decreases, and the pressure increases. The set pressure of the restriction valve is increased, and the discharge-side main line is restricted, thereby limiting the amount of return oil discharged from the hydraulic motor.

However, also in this valve device, the arrangement of the check valve and the pressure limiting valve in the main line is the same as that of the above-described counterbalance valve, and the same problem as described above with the counterbalance valve is obtained. Occurs.

On the other hand, as a valve device for controlling the flow of the pressure oil supplied to the hydraulic actuator and controlling the drive of the actuator, a seat-type main valve and a pilot circuit having a pilot valve for controlling the opening of the main valve are used. What is USP 4,535,8
No. 09 is described. In this valve device,
The main valve is an inlet port and an outlet port, a seat type valve body,
The pilot circuit comprises a variable throttle that changes the opening degree in accordance with the displacement of the valve body, and a back pressure chamber that communicates with the inlet port through the variable throttle to urge the valve body in the valve closing direction. The main valve is closed when the pilot valve is fully closed, and the opening of the main valve is changed according to the throttle amount of the pilot valve. However, this valve device is not provided with means for providing a function equivalent to that of the above-described counterbalance valve.

The present invention has been made in view of the above-described circumstances in the related art, and an object of the present invention is to provide a valve device that can secure a function equivalent to that of a counterbalance valve by controlling a small flow rate and obtain stable performance. Is to do.

DISCLOSURE OF THE INVENTION To achieve this object, the present invention provides a hydraulic pump,
A hydraulic device having a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump; and a valve device for controlling driving of the actuator, wherein a meter-in guides the hydraulic oil discharged from the hydraulic pump to the actuator. A circuit, and a meter-out circuit for guiding return oil from the actuator to a tank, wherein the meter-out circuit controls a return valve from the actuator, a main valve, and a pilot circuit including variable throttle means; Control means for changing the throttle amount of the variable throttle means in accordance with the drive pressure of the actuator, wherein the main valve is an inlet port and an outlet port, a sheet-type valve body that opens and closes between the inlet port and the outlet port, A variable throttle that increases or decreases the opening in accordance with the displacement of the valve element, via the inlet port and the variable throttle. A back pressure chamber for controlling the displacement of the valve element in accordance with the degree of opening of the variable throttle means of the pilot circuit, wherein the valve element is closed when the pilot circuit is closed; The opening degree of the valve body is changed according to the amount.

By configuring the meter-out circuit of the valve device in this way, the throttle amount of the variable throttle means in the pilot circuit of the meter-out circuit changes according to the load in the direction of gravity or the driving pressure of the actuator that drives the inertial body, Since the opening of the main valve body is variably controlled in accordance with the change in the throttle amount of the variable throttle means, the same function as the counterbalance valve can be secured by controlling the small flow rate flowing through the pilot circuit. And the flow force acting on the variable throttle means can be kept small. The main valve through which return oil from the actuator passes is a sheet-type valve element, a variable throttle that increases or decreases the opening according to the displacement of the valve element, or a valve element according to the opening degree of the variable throttle means of the pilot circuit. Unlike the conventional counterbalance valve, which consists of a back pressure chamber that controls the displacement of the valve and a pure hydraulic pressure, and a spring / mass system that positions the valve element (mass) by balancing pilot pressure and spring force.
Since there is no resonance point, stable performance can be ensured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a hydraulic circuit including a valve device according to a first embodiment of the present invention, and FIG. 2 is a hydraulic circuit including a valve device according to a second embodiment of the present invention. FIG.
FIG. 3 is a circuit diagram showing a hydraulic circuit including a valve device according to a third embodiment of the present invention, and FIG. 4 is a circuit diagram showing a hydraulic circuit including a valve device according to the fourth embodiment of the present invention. FIG. 5 is a circuit diagram showing a hydraulic circuit including a valve device according to a fifth embodiment of the present invention, FIG. 6 is a sectional view showing the structure of the valve device, and FIG. FIG. 8 is a sectional view showing a structure of a valve device according to a sixth embodiment of the present invention, and FIG. 8 is a sectional view showing a structure of a valve device according to a seventh embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

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

In FIG. 1, a hydraulic circuit is constituted by a hydraulic pump 1, a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump 1, for example, a hydraulic motor 2, and a tank 3, and the hydraulic pump 1 and the tank 3 Motor 2
And a meter-in circuit 4 for controlling pressure oil supplied from the hydraulic pump 1 to the hydraulic motor 2 and a meter-out circuit 5 for controlling return oil from the hydraulic motor 2 to the tank 3. A valve device 6 constituting the first embodiment is provided.

The meter-in circuit 4 of the valve device 6 includes a main line 8 connected to the discharge line 7 of the hydraulic pump 1, a main valve 9 of a seat type,
It comprises pilot circuits 11 a and 11 b having a pilot valve 10 for controlling the opening of the main valve 9, and a main line 13 connected to the supply side main line 12 of the hydraulic motor 2. The main valve 9 has an inlet port 14 and an outlet port 15, a seat-type valve body 16, a variable throttle 17 comprising a slit for changing the opening degree according to the displacement of the valve body 16, and a variable throttle 17 at the inlet port 14. And a back pressure chamber 18 that urges the valve body 16 in the valve closing direction (upward in the figure) through a valve. Pilot circuits 11a and 11b are connected between the back pressure chamber 18 of the main valve and the outlet port 15. And the pilot valve 10
When the valve is fully closed, the main valve 9 is closed, and the opening of the main valve 9 is changed in accordance with the throttle amount of the pilot valve 10.

In a valve structure composed of a combination of the main valve 9 and the pilot circuits 11a and 11b having the pilot valve 10 configured as described above, the main valve 9 has a flow rate substantially proportional to the pilot flow rate flowing through the pilot circuits 11a and 11b. Flowing through
It is known from US Pat. No. 4,535,809. As a result, the pilot flow rate is controlled by the throttle amount of the pilot valve 10, and a large flow rate that is approximately proportional to the pilot flow rate is supplied to the hydraulic motor 2 through the main valve 9.

The meter-out circuit 5 of the valve device 6 includes a main line 21 connected to the discharge-side main line 20 of the hydraulic motor 2, a sheet-type main valve 22, and a variable throttle for controlling the opening of the main valve 22. It comprises a pilot circuit 24a, 24b having a valve 23 and a main line 26 connected to a return line 25 leading to the tank 3. Main valve 22
Are configured similarly to the main valve 9, and the same members are denoted by the same reference numerals. The pilot circuits 24a and 24b are connected to the back pressure chamber 18 of the main valve 22.
The main valve 22 is closed when the variable throttle valve 23 is fully closed, and the opening of the main valve 22 is changed according to the throttle amount of the variable throttle valve 23. .

In the valve structure including the combination of the main valve 22 and the pilot circuits 24a and 24b having the variable throttle valve 23, the valve structure 9, 10, 1 of the meter-in circuit 4 described above is used.
1a, 11b, the pilot flow rate is controlled by the throttle amount of the variable throttle valve 23, and a large flow rate substantially proportional to the pilot flow rate is discharged to the tank 3 through the main valve 22.

The variable throttle valve 23 of the meter-out circuit 5 is provided with control means for changing the throttle amount of the variable throttle valve 23 in accordance with the driving pressure of the hydraulic motor 2.
A first pressure receiving portion 28 provided at one end of the variable throttle valve 23 and through which a driving pressure of the hydraulic motor 2 is introduced via a pipe 27 connected to the main pipe 13 of the meter-in circuit 4; A second pressure receiving portion 30 provided at the other end, to which the outlet pressure of the main valve 22 is introduced via a line 29 connected to the main line 26, and a spring disposed on the same side as the second pressure receiving portion 30 It consists of 31. That is, the first pressure receiving portion 28, the second pressure receiving portion 30, and the spring 31
Are arranged such that the force of the pressure of the first pressure receiving portion 28, the force of the pressure of the second pressure receiving portion 30, and the force of the spring 31 act opposite to each other.

Here, the pressure receiving area of the first pressure receiving portion 28 is defined as am,
Assuming that the pressure receiving area of the pressure receiving portion 30 is az, these pressure receiving areas are set to am = az, and the variable throttle valve 23 has a predetermined differential pressure between the driving pressure of the hydraulic motor 2 and the outlet pressure of the main valve 22. The throttle amount is controlled to be equal to or higher than the pressure. This will be described below.

First and second pressure receiving portions 28 and 30 acting on the variable throttle valve 23
The balance between the force of the pressure and the force of the spring 31 is as follows: the drive pressure of the hydraulic motor 2 is Pm, the outlet pressure of the main valve 22 is Pz,
Assuming that the spring constant of the spring 31 is Kz, the displacement of the spring 31 is z, and the initial value of the displacement is zo, Pm · am = Pz · az + Kz (zo + z) (1) Here, since am = az, substituting this relationship into equation (1) gives Pm−Pz = (Kz / am) · (zo + z) ≧ (Kz / am) · zo (2) That is, the control means including the first pressure receiving portion 28, the second pressure receiving portion 30 and the spring 31 controls the driving pressure of the hydraulic motor 2.
The differential pressure between Pm and the outlet pressure Pz of the main valve 22 is equal to a predetermined pressure (Kz / a
The drive of the variable throttle valve 23 is controlled so as to be not less than m) · zo.

Next, the operation of the valve device thus configured will be described.

While the hydraulic pump 1 is driven, the meter-in circuit 4
When the pilot valve 10 is operated to move upward from the state shown in the figure, the pilot valve 10 is opened, and the valve element 16 of the main valve 9 moves downward in the figure and opens according to the throttle amount. For this reason, the pressure oil discharged from the hydraulic pump 1 is guided to the hydraulic motor 2 via the main lines 7 and 8, the main valve 9 and the main lines 13 and 12. At this time, the flow rate passing through the main valve 9 is a flow rate substantially proportionally multiplied by the pilot flow rate determined according to the throttle amount of the pilot valve 10 as described above.

Further, the driving pressure of the hydraulic motor 2 in the main pipe line 13 is guided to the first pressure receiving portion 28 of the variable throttle valve 23 via the pipe line 27, the variable throttle valve 23 is opened, and the main valve 22 Is moved to the left in the figure and opened. Thereby, the return oil of the hydraulic motor 2 is guided to the tank 3 through the main pipelines 20, 21, the main valve 22, and the main pipelines 26, 25, and the hydraulic motor 2 is driven to move the load in the direction shown by the broken line. .

Here, when the drive pressure Pm of the hydraulic motor 2 becomes larger than the sum of the outlet pressure Pz of the main valve 22 and the force of the spring 31 from the state shown in FIG. 1, the throttle amount of the variable throttle valve 23 of the meter-out circuit 5 Decreases (the opening increases), and the pilot circuits 24a and 24b
When the pilot flow rate of the hydraulic motor 2 increases and the driving pressure Pm of the hydraulic motor 2 becomes smaller than the sum of the outlet pressure Pz of the main valve 22 and the force of the spring 31, the throttle amount of the variable throttle valve 23 of the meter-out circuit 5 decreases. (Opening decreases), and the pilot circuit 24a,
The pilot flow through 24b is reduced. For this reason, as described above, the flow rate which is approximately proportional to the pilot flow rate flows through the main valve 22, so that the flow rate passing through the main valve 22 is reduced in the same manner as the pilot flow rate, and the discharge of the return oil of the hydraulic motor 2 is restricted. Is done.

Looking at this from the above equation (2), when the driving pressure Pm of the hydraulic motor 2 increases and the differential pressure Pm−Pz between the driving pressure Pm and the outlet pressure Pz of the main valve 22 increases, The displacement of the spring 31, that is, the displacement z of the variable throttle valve 23 increases, the throttle amount in the variable throttle valve 23 decreases, and the return flow rate flowing from the main pipe line 20 to the tank 3 via the main valve 22 increases. When the drive pressure Pm of the hydraulic motor 2 decreases and the differential pressure between the drive pressure Pm and the outlet pressure P of the main valve 22 decreases, the displacement z of the variable throttle valve 23 decreases, and the variable throttle valve 23 decreases. The throttle amount at 23 increases, and the tank 3 moves from the main line 20 through the main valve 22.
The return flow flowing out to is reduced.

At this time, the variable throttle valve 23 is controlled such that the pressure difference between the drive pressure Pm of the hydraulic motor 2 and the outlet pressure Pz of the main valve 22 becomes equal to or higher than a predetermined pressure (Kz / am) · zo. As a result, cavitation and runaway due to driving of the hydraulic motor 2 do not occur, and stable driving performance of the hydraulic motor 2 can be secured.

In the first embodiment configured as described above, the main valve
22, and pilot circuits 24a and 24b including a variable throttle valve 23,
First pressure receiving portion 28, second pressure receiving portion 30, spring 31, and conduits 27 and 2
The meter-out circuit 5 having the control means for the variable throttle valve 23 composed of the valve 9 can ensure the same function as that of the counterbalance valve.
a, 24b to control the small flow rate flowing through the main pipeline 8,1
No counterbalance valve or alternative means is provided in 2,13,20,21,26.

Therefore, the energy loss due to the pressure loss caused by the counterbalance valve can be suppressed, the valve device can be downsized, and the manufacturing cost can be reduced. Furthermore, since the variable throttle valve 23 controls a small flow rate, the flow force acting on the small throttle valve 23 is small, and the main valve 22 through which the return oil from the hydraulic motor 2 passes passes through the valve body 16, the variable throttle 17, and the back pressure chamber 18. Unlike a conventional counterbalance valve, which is constructed in a pure hydraulic manner and has a spring-mass system that positions the valve element (mass) in balance with the pilot pressure and spring, it has no resonance point, so the flow force acts. However, stable performance can be ensured.

A second embodiment of the present invention will be described with reference to FIG. The valve device 6A according to the second embodiment is slightly different from the above-described first embodiment only in the configuration of the meter-out circuit 5A. That is, the meter-out circuit 5A of the second embodiment is provided with a pilot valve 41 for controlling the operation of the main valve 22 in series with the variable throttle valve 40 in the pilot circuits 24a and 24b. The circuit can be closed. Further, the variable throttle valve 40 does not completely close the pilot circuit at the time of its maximum throttle.

In the second embodiment configured as above, when each of the pilot valve 10 of the meter-in circuit 4 and the pilot valve 41 of the meter-out circuit 5A is operated to move upward from the state shown in the figure, the first The flow rate control for driving the hydraulic motor 2 is performed in substantially the same manner as in the embodiment. When the driving pressure of the hydraulic motor 2 decreases, the variable throttle valve 40 is connected to the pilot circuit 24 of the meter-out circuit 5A.
In order to reduce the pilot flow rate flowing through the pilot circuits 24a and 24b, the transient operation of the return oil of the hydraulic motor 2 is suppressed, and the counter balance is controlled. Functions equivalent to those of the valve can be secured.

Further, in the present embodiment, in the meter-out circuit 5A, when the pilot valve 41 is operated, the pilot circuits 24a and 24b are not completely closed. Hunting due to the change can be prevented beforehand, and stable performance can be secured.

A third embodiment of the present invention will be described with reference to FIG. The valve device 6B according to the third embodiment is slightly different from the above-described second embodiment only in the configuration of the meter-out circuit 5B. That is, the meter-out circuit 5B of the third embodiment is connected to the second pressure receiving portion 30 provided at the end of the variable throttle valve 40 on the side where the spring 31 is located, via the pipe line 42. But the same downstream pressure of the main valve, but not the outlet pressure of the main valve 22 in the valve device 6B,
It is configured to guide the tank pressure in the return line 25 outside the valve device 6B.

Also in the present embodiment, the variable throttle valve 40 operates in accordance with the decrease in the driving pressure of the hydraulic motor 2, the throttle amount of the pilot circuit of the meter-out circuit 5B increases, and the same function as the counterbalance valve is performed. Further, in this embodiment, since the tank pressure can be considered to be substantially constant at this time, since Pz on the left side of the above-mentioned equation (2) is constant, the driving pressure Pm of the hydraulic motor 2 becomes equal to or more than a constant value. Can be controlled as follows.

A fourth embodiment of the present invention will be described with reference to FIG. In the valve device 6C according to the fourth embodiment, a meter-in circuit 4C and a meter-out circuit 5C equivalent to the meter-in circuit 4 and the meter-out circuit 5A in the second embodiment shown in FIG.
And a combination of a meter-in circuit 4D and a meter-out circuit 5D having the same configuration as those of the meter-in circuit 4C and the meter-out circuit 5C, respectively. The main valve of the meter-in circuit 4D has an inlet port connected to the hydraulic pump 1 via the discharge line 50, and an outlet port connected to the hydraulic motor 2 via the main line 51, a part of the main line 21 and the main line 20. The main pipeline 51 is provided with a check valve 52 for preventing the flow of the pressure oil from the hydraulic motor 2. Meter-out circuit 5D
The main valve 22 has an inlet port connected to the hydraulic motor 2 through a part of the main line 13 and the main line 12, and an outlet port connected to the main line 2.
The main line 13 is provided with a check valve 53 for blocking the flow of pressure oil from the hydraulic motor 2 through the main line 13 and the tank 3.

The pilot valve 10 of the meter-in circuit 4C and the pilot valve 41 of the meter-out circuit 5C are provided integrally and are linked to each other.
The meter-out circuit 5D of the 4D pilot valve 10 and the pilot valve 41 of the 5D are provided integrally with each other so as to be linked with each other.

In the fourth embodiment configured as described above, for example, when the pilot valve 10 of the meter-in circuit 4C is operated, the pilot valve 41 also moves in conjunction therewith, and these pilot valves 10, 4
The opening degree of the main valves 9, 22 according to the operation amount (throttle amount) of 1 is obtained. Accordingly, the pressure oil discharged from the hydraulic pump 1 is supplied to the hydraulic motor 2 via the main line 7, the main valve 9, and the main lines 13, 12, and the return oil from the hydraulic motor 2 is supplied to the main lines 20, 21, Valve 2
2. Returned to tank 3 via main line 26 and return line 25,
The hydraulic motor 2 rotates in a direction indicated by a solid line. Also,
When the pilot valve 10 of the meter-in circuit 4D is operated, the pilot valve 41 also moves in conjunction therewith, and these pilot valves 10, 4
The opening degree of the main valves 9, 22 according to the operation amount (throttle amount) of 1 is obtained. Therefore, the pressure oil discharged from the hydraulic pump 1 is
50, the main valve 9, and the hydraulic fluid supplied to the hydraulic motor 2 via the main conduits 51, 21, and 20, and the return oil from the hydraulic motor 2 is supplied to the main conduit 12, the main valve 2
2. Returned to tank 3 via main line 26 and return line 25,
The hydraulic motor 2 rotates in a direction indicated by a broken line.

Here, assuming that a load in the direction of gravity or an inertial force acts while the hydraulic motor 2 is rotating in the direction of the arrow indicated by the solid line,
When the flow rate flowing through the main line 20 increases due to these loads and inertia force, and the driving pressure of the main line 12 decreases, the driving pressure is changed via the line 27 to the variable throttle valve of the meter-out circuit 5C. The variable throttle valve 40 moves to increase the throttle amount, and performs the same function as a counterbalance valve.

A fifth embodiment of the present invention will be described with reference to FIGS. In the valve device 6E according to the fifth embodiment, the configuration of the control means of the variable throttle valve 23 in the meter-out circuit 5E is the first.
This is different from the first embodiment shown in the figure. That is, in the fifth embodiment, the control means of the variable throttle valve 23 controls the first pressure in which the back pressure of the back pressure chamber 18 of the main valve 22 is introduced via the line 60.
Pressure receiving portion 61, a second pressure receiving portion 63 into which the inlet pressure of the main valve 22 is introduced through a pipe 62, and a hydraulic motor 2 through a pipe 27.
Pressure receiving portion 64 into which the driving pressure of the second pressure is introduced, and a variable throttle valve
A first pressure receiving portion 61, a second pressure receiving portion 63, a third pressure receiving portion 64, and a spring 31;
The variable throttle valve 23 is provided so that the force of the pressure of 61, the force of the spring 31, and the force of the pressure of the second and third pressure receiving portions 63 and 64 act opposite to each other.

The pressure receiving portion located in the back pressure chamber 18 of the valve body 16 of the main valve 22
65, the pressure receiving area is Ac, the pressure receiving area of the pressure receiving section 66 located at the inlet boat 14 of the main valve body 16 is As, and the pressure receiving area of the pressure receiving section 67 located at the outlet port 15 of the main valve body 16 is Az, which is variable. When the pressure receiving area of the first pressure receiving section 61 of the control means of the throttle valve 23 is ac, the pressure receiving area of the second pressure receiving section 63 is as, and the pressure receiving area of the third pressure receiving section 64 is am, the main valve valve Ratio of pressure receiving area of body 16 Ac: As; Az
These pressure receiving areas are set such that the ratio ac: as: am of the pressure receiving areas of the first to third pressure receiving portions of the variable throttle valve control means is substantially equal. That is, the pressure receiving areas of the above Ac, As, Az ac, as, am are set so that K is a constant and ac / Ac = as / As = am / Az = K (3).

In the fifth embodiment, the first
The balance between the force of the pressure of the third pressure receiving portions 61, 63, 64 and the force of the spring 31 is as follows.
Assuming that the back pressure of the valve 22 is Pc, the inlet pressure of the main valve 22 is Ps, the spring constant of the spring 31 is Kz, the displacement of the spring 31 is Z, and the initial value of the displacement is zo, Ps · as + Pm · am = Pc · ac + Kz (Zo + z) (4) The balance of the force due to the pressure acting on the valve element 16 of the main valve 22 is Ps · As + Pz · Az = Pc · Ac (5) Here, when the expression (3) is substituted into the expression (5), Ps · as + Pz · am = Pc · ac (6) Further, when this equation (6) is substituted into the above equation (4), Pm · am−Pz · am = Kz (zo + z), ie, Pm−Pz = (Kz / am) · (zo + z) ≧ (Kz / am)・ Zo (7) That is, the same equation as the above-described equation (2) is obtained. In the fifth embodiment, the driving means of the hydraulic motor 2 is controlled by the control means including the first to third pressure receiving portions 61, 63, 64 and the spring 31. The pressure difference between the pressure Pm and the outlet pressure Pz of the main valve 22 is a predetermined pressure (Kz
The drive of the variable throttle valve 23 is controlled so as to be equal to or more than / am) · zo.

As described above, in the present embodiment, even when the main valve back pressure Pc and the inlet pressure Ps are used as the control means of the variable throttle valve 23 instead of the outlet pressure Pz, the drive of the hydraulic motor 2 is performed as in the first embodiment. The differential pressure between the pressure Pm and the outlet pressure Pz of the main valve 22 can be controlled.

In this embodiment, the pressure receiving area ratio Ac: As; Az and the pressure receiving area ratio ac: as: am are set to be equal as shown in the equation (3). In consideration of the influence of the flow force and the like, the ratio may not completely match.

A sixth embodiment of the present invention will be described with reference to FIG. The sixth embodiment is characterized in the connection relationship between the main valve 22 and the variable throttle valve 23 arranged in the meter-out circuit 70. That is, in the present embodiment, the variable throttle valve 23 is
The spool 71 constituting the valve body is coaxially slidably disposed, and the inlet pressure Ps of the main valve 22 is set to the second pressure of the variable throttle valve 23.
The means for leading to the pressure receiving portion 63 is formed as a passage 72 inside the main valve body 16. Other configurations are the same as those of the fifth embodiment shown in FIG.

In the sixth embodiment configured as described above, the same effects as those of the fifth embodiment shown in FIGS. 5 and 6 are obtained, and the variable throttle valve 23 and the main valve 22 are coaxially arranged. The provision of the relative sliding allows the overall configuration to be compact, and the simple provision of the internal passage 72 simplifies the complicated oil passage, thereby reducing the manufacturing cost.

A seventh embodiment of the present invention will be described with reference to FIG. In the seventh embodiment, a pilot valve 41 for controlling the operation of the main valve 22 in series with the variable throttle valve 23 is provided in a pilot circuit 24b in which the variable throttle valve 23 constituting the meter-out circuit 80 is disposed.
And a passage 81 for communicating the pilot circuit 24b with the back pressure chamber 18 of the main valve 22 so that the pilot circuit 24b is not completely closed when the pilot valve 41 is operated. Other configurations are the same as those of the sixth embodiment shown in FIG.

In the seventh embodiment configured as described above, the same effect as that of the sixth embodiment shown in FIG. 7 can be obtained, and the pilot circuit 24b can be completely closed when the pilot valve 41 is operated. Therefore, hunting due to a change in the driving pressure of the hydraulic motor 2 or a change in the flow rate can be prevented, and stable performance can be secured. That is, the effect of the second embodiment shown in FIG. 2 can be obtained.

Industrial Applicability Since the valve device of the present invention is configured as described above, a function equivalent to that of the counterbalance valve can be secured by controlling a small flow rate. Energy loss due to pressure loss due to the arrangement of the counterbalance valve inside can be suppressed, the valve device can be downsized, and the manufacturing cost can be reduced. Further, the flow force acting on the variable throttle means can be suppressed to a small value, and the main valve through which the return oil from the actuator passes is constituted by pure hydraulic pressure, so that stable performance can be secured.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yusaku Nozawa 2930-14 Hatorihanakan, Minori-cho, Higashiibaraki-gun, Ibaraki Pref. JP, B2) Japanese Patent Publication No. 55-631 (JP, B2) Jikken Sho 53-29912 (JP, Y2)

Claims (10)

(57) [Claims] A valve device (6) provided in a hydraulic machine having a hydraulic pump (1) and a hydraulic actuator (2) driven by pressure oil discharged from the hydraulic pump, and controlling the driving of the actuator. ), A meter-in circuit (4) for guiding pressure oil discharged from the hydraulic pump (1) to the actuator (2), and a meter-out circuit (5) for guiding return oil from the actuator to the tank (3). The meter-out circuit has a main valve (22) for controlling return oil from the actuator, a pilot circuit (24a, 124b) including a variable throttle means (23), and a drive pressure of the actuator. Control means (27 to 31) for changing the throttle amount of the variable throttle means, wherein the main valve (22) is provided with an inlet port (14) and an outlet port (15). A seat-type valve element (16) for opening and closing between a valve and an outlet port, a variable throttle (17) for increasing or decreasing an opening in accordance with the displacement of the valve element, communicating with the inlet port via the variable throttle, A back pressure chamber (18) for controlling the displacement of the valve element (16) according to the degree of opening of the variable throttle means (23) of the circuit, and closing the valve element (16) when the pilot circuit is closed; A valve device characterized in that the opening degree of the valve element (16) is changed in accordance with the amount of throttle of the variable throttle means (23). 2. The variable throttle according to claim 1, wherein said control means (27-31) controls the pressure difference between a driving pressure of said actuator (2) and a downstream pressure of said main valve (22) to be a predetermined pressure or more. 2. The valve device according to claim 1, wherein the amount of throttle of the means (23) is changed. 3. The variable throttle means (23), wherein:
And a second pressure receiving portion (28) provided with the driving pressure of the actuator (2) and a second pressure provided on the variable throttle means and provided with a downstream pressure of the main valve (22).
A pressure receiving portion (30) and a spring (31) for urging the variable throttle means. The first pressure receiving portion, the second pressure receiving portion, and the spring are moved by the force of the pressure of the first pressure receiving portion. 2. The valve device according to claim 1, wherein the force generated by the pressure of the second pressure receiving portion and the force of the spring are arranged so as to oppose each other. 4. The valve device according to claim 2, wherein the pressure downstream of the main valve is an outlet pressure of the main valve. 5. The pressure on the downstream side of the main valve is set in the tank (3).
The valve device according to claim 2 or 3, wherein the pressure is a pressure of (a). 6. The valve device according to claim 1, wherein said pilot circuit further includes a pilot valve for controlling an operation of said main valve. 7. The meter-in circuit (4C, 4D) includes a main valve (9) for controlling pressure oil guided to the actuator (2) and a pilot circuit (11a, 11b) including a pilot valve (10). The main valve is closed when the pilot circuit is closed, and the opening degree is changed in accordance with the throttle amount of the pilot valve; and the pilot valve (10) of the meter-in circuit (4C, 4D) 7. The valve device according to claim 6, wherein a pilot valve (41) of the meter-out circuit (5C, 5D) is linked. 8. The pilot circuit (24a, 24b) is connected between a back pressure chamber (18) of the main valve and an outlet port (15). A first pressure receiving part (61) provided in the variable throttle means and provided with the back pressure of the main valve, and a second pressure receiving part (61) provided in the variable throttle means and introduced with the inlet pressure of the main valve. 63), a third pressure receiving portion (64) provided in the variable throttle means, to which the driving pressure of the actuator (2) is introduced, and a spring (31) for biasing the variable throttle means. , The first pressure receiving section,
The second pressure receiving portion, the third pressure receiving portion, and the spring are arranged such that the force of the first pressure receiving portion, the force of the spring, and the force of the second and third pressure receiving portions act opposite to each other. The valve device according to claim 1, wherein: 9. The pressure receiving area of the back pressure chamber (18) of the main valve body (16) is Ac, and the pressure receiving area of the inlet port (14) of the main valve body is A.
s, the pressure receiving area of the outlet port (15) of the main valve body is Az,
The pressure receiving area of the first pressure receiving portion (61) of the variable throttle means (23) is ac, the pressure receiving area of the second pressure receiving portion (63) is as, and the pressure receiving area of the third pressure receiving portion (64) is am
These pressure receiving areas are set so that the pressure receiving area ratio Ac: As; Az of the main valve body and the pressure receiving area ratio ac: as: am of the first to third pressure receiving sections of the variable throttle means are substantially equal. 9. The valve device according to claim 8, wherein the valve device is set. 10. The main valve body (16) and a variable throttle means (2)
3) are slidably disposed coaxially with each other, and means (72) for guiding the inlet pressure of the main valve (22) to the second pressure receiving portion (63) of the variable throttle means is provided by the main valve valve. 9. The valve device according to claim 8, wherein the valve device is provided inside the body.