JPH0253641B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a composite valve that combines a pressure compensating valve and a directional control valve to control the operating direction and speed of an actuator, and the present invention relates to a composite valve that controls the operating direction and speed of an actuator during unloading operation of a hydraulic pump. This has been improved to reduce pressure loss.

(Prior Art) A conventional art to which the present invention pertains is shown in FIG. 3 (Utility Model Application No. 54-97594). This technique will be explained below.

The devices shown in Figure 3 each have a large pressure loss during unloading operation of the hydraulic pump compared to the present invention. (Incidentally, the reason why the pressure loss during unloading operation of the hydraulic pump is kept to a small value is to minimize unnecessary power loss.) The conventional technology will be discussed below with a focus on this point. Moreover, the pressure compensating valve of the reference according to the same technical field as the present invention can be used in combination with the directional control valve 2, regardless of the load fluctuation of the actuator A.
The purpose is to supply the actuator A with a flow rate corresponding to the amount of operation of the directional switching valve 2.
To achieve this purpose, a pressure compensation valve 4 is provided between the pressure fluid source 1 and the tank 3 to adjust the amount of oil discharged into the tank 3 from a portion of the pressure oil discharged from the pressure fluid source 1. It has a function of keeping the differential pressure across the throttle 9 formed by the directional switching valve 2 connected to the pressure fluid source 1 constant regardless of load fluctuations of the actuator A.

In order for the conventional technology to perform such a function, the pressure compensating valve 4 has a spool 36 that controls between the pressure fluid source 1 and the tank 3, and the pressure chamber 39 and the spool are connected via this spool 36. Spring 4 pushing 36
The pressure chamber 39 is provided opposite to the spring chamber 52 in which the throttle 9 is provided, and the hydraulic pressure (discharge pressure of the pressure fluid source 1) on the upstream side of the throttle 9 is applied to the pressure chamber 39. The structure is such that the hydraulic pressure (load pressure of actuator A) is applied.

In the pressure compensation valve 4 having such a configuration, when the directional control valve 2 is operated and the hydraulic pressure on the upstream and downstream sides of the throttle 9 acts on the pressure chamber 39 and the spring chamber 52, the pressure difference before and after the throttle 9 is reduced. The spool 36 controls the amount of hydraulic pressure discharged from the pressure fluid source 1 into the tank 3 so as to control the amount to a constant value (a value larger than the pressure loss of the directional control valve 2) according to the pushing force of the spring 49. It operates to control the

In the above-described operation of the pressure compensation valve 4, when the directional control valve 2 is operated, the spring chamber 5 of the pressure compensation valve 4
The load pressure of the actuator A acts on the actuator A, and the discharge oil pressure of the pressure fluid source 1 at this time has a value corresponding to the sum of the load pressure and the pushing force of the spring 49. At this time, the difference between the discharge oil pressure of the pressure fluid source 1 and the load pressure of the actuator A must be set to a pressure that exceeds the pressure drop of the directional control valve 2. The spring 49 provided in the spring chamber 52 functions to make the hydraulic pressure discharged from the pressure fluid source 1 into a pressure that exceeds this pressure drop.

(Problems to be Solved by the Invention) In the conventional technology described above, even when the directional control valve 2 is in the neutral position, the discharge oil pressure (unload pressure) of the pressure fluid source 1 is equivalent to the pushing force of the spring 49. There is growing pressure to do so. This pressure is not the pressure necessary for actuator A to operate. In other words, there is a power loss.

The present invention solves the above-mentioned problems of the prior art.

(Technical Means for Solving the Problems) The technical means of the present invention for solving the above problems is to connect the pressure compensating valve 4 to the control unit 30 that controls the connection between the pressure fluid source 1 and the tank 3. , a pilot valve section 31 which is provided with a spring chamber 52 having a spring 49 for setting the differential pressure of the directional control valve 2, and a control section 3.
0 pressure chamber 40 is controlled by a pilot valve section 31, and a shutoff valve 5 is installed between the pressure chamber 40 and the tank 3.
are interposed between the pilot valve section 31 and the shutoff valve 5.
and, when the directional control valve 2 is in the neutral position, the tank 3
connected to the pilot passage 51 connected to the load side of the actuator A when in the switching position,
When the load pressure of the actuator A acts on the pilot passage 51, the shutoff valve 5 closes the control section 30.
The structure is such that the pressure chamber 40 and the tank 3 are isolated from each other.

(Function) In the present invention having the above configuration, when the directional control valve 2 is in the neutral position, the pressure compensation valve
A pressure chamber 40 is directly connected to the tank 3 by a shutoff valve 5. When the directional control valve 2 is operated, the load pressure of the actuator A causes the cutoff valve 5 to open in the pressure chamber 4.
Since the space between the pressure chamber 40 and the tank 3 is closed, the pressure chamber 40
is controlled by the pilot valve section 31. For this reason,
The unloading hydraulic pressure of the present invention is applied to the pressure chamber 4 of the control section 30 regardless of the pressure drop of the directional control valve 2.
0 (the pushing force of this spring 41 is
When the oil pressures in the pressure chambers 40 and 39 become equal, it is sufficient to operate the spool 36 in a direction that throttles the pressure fluid source 1 and the tank 3. ) can be set to a low value equivalent to the pressing force of . In this manner, the present invention automatically increases the oil pressure of the pressure fluid source 1 when the directional control valve 2 is operated, so that the unloading oil pressure when the directional control valve 2 is in the neutral position is reduced to an extremely small value. It is something that can be done.

<Example> Hereinafter, an explanation will be given with reference to FIG. 1 showing a circuit diagram of an example of the present invention and FIG. 2 showing a circuit diagram including a sectional view.

In FIG. 1, A is an actuator. In this actuator, a pressure fluid source 1 (hereinafter referred to as pump 1) is connected to a directional control valve 2 via discharge circuits 8a and 8b, and load passages 20a and 2
It is connected via 0b. When the spool 16 of the directional control valve 2 is operated, a throttle 9a or 9 is created between the load passage 20a or 20b and the discharge circuit 8b.
b, and connects the pilot passage 51 to the load side of the load passage 20a or 20b. A pressure compensation valve 4 is provided between the discharge circuit 8a and the tank 3.
is provided. This pressure compensating valve 4 has a pressure chamber 39 connected to the discharge side of the pump 1 and a spring chamber 40 having a spring 41.
A part of the discharged pressure fluid is discharged into the tank 3 from the control section 30, and the spring chamber 52 is arranged between the spring chamber 40 of the control section 30 and the tank, and the spring chamber 52 is connected to the pilot passage 51. The pilot valve section 31 has a pilot valve section 31. The spring chamber 40 of this pressure compensating valve 4 is connected to a tank via a shutoff valve 5 . This shutoff valve 5 closes the gap between the spring chamber 40 and the tank 3 by the load pressure of the pressure chamber 51 to which the pilot passage 51 is connected, and when the pilot passage 51 is connected to the tank, the spring chamber 40 is closed to the tank 3 communicate with.

When the directional control valve 2 is operated in the above configuration, the load pressure of the actuator A is transferred to the pilot valve portion 31 and the cutoff valve 5 via the pilot passage 51.
It acts on Then, the shutoff valve 5 shuts off the spring chamber 40 and the tank, and the hydraulic pressure in the spring chamber 40 of the control valve section 30 is controlled by the pilot valve 31.
At this time, the hydraulic pressure in the spring chamber 40 of the control valve section 30 is
Therefore, the discharge fluid pressure of the pump 1 is maintained so that the differential pressure across the throttle of the directional control valve 2 is higher than the load pressure by the amount obtained by the spring 49. The flow rate from the pump 1 to the actuator A is controlled to a value according to the operation amount of the directional switching valve, regardless of load fluctuations on the actuator. Note that the control section 30 of the pressure compensation valve 4
The pressing force of the spring 41 in the spring chamber 40 causes the spool 36 to move to the second position when the pressure fluid ceases to act.
Since it is intended to hold the position in the figure, it is set to an extremely weak value. Similarly, the spring 62 of the shutoff valve 5
Since the pressing force is to hold the spool 57 in the illustrated position when the pilot pressure decreases, it may be a weak value. The pressing force of the spring 49 of the spring chamber 52 of the pilot valve portion 31 determines the differential pressure across the throttle formed by the directional control valve 2. Note that the spring 41 provided in the spring chamber 40 of the control section 30 also functions in the same way as the spring 49, but as is clear from FIG.
6, the amount of deflection during control increases. Due to the characteristics of the pressure compensation valve, the spring that determines the differential pressure before and after the throttle formed by the directional control valve needs to be a spring whose pressing force changes little with respect to the amount of deflection (lower spring constant). If the spring 41 were to perform the same function as the spring 49, it would be necessary to increase the size of the spring in order to reduce the change in pressing force with respect to the amount of deflection. However, the spring 49 is
The amount of movement can be made extremely small (because the opening area of the ball valve 50 for lift is large). For this reason, the spring force for setting the differential pressure across the throttle formed by the directional switching valve 2 is provided by the spring 49.

Next, the configuration of each component will be explained using a circuit diagram including a cross-sectional view shown in FIG.

The composite valve is a pressure fluid source 1 (hereinafter referred to as pump).
A directional control valve 2 is disposed between the discharge side of the pump 1 and the actuator (not shown) and forms a restriction between the discharge side of the pump 1 and the actuator A, and a directional control valve 2 is disposed between the discharge side of the pressure fluid source 1 and the tank. 3, a pressure chamber on which the fluid pressure on the upstream side of the throttle formed by the directional control valve 2 acts, and a spring chamber with a spring on which the load pressure on the load side (downstream side) of the actuator A acts. and a pressure compensation valve 4 that controls the difference in fluid pressure between the upstream side and the downstream side of the throttle formed by the directional control valve 2 to a constant value, and a spring chamber of the pressure compensation valve 4 and a tank 3. A cutoff valve 5 is disposed between the spring chamber and the tank 3 and is operated by fluid pressure downstream of the throttle of the directional control valve 2 to cut off the connection between the spring chamber and the tank 3.

The directional control valve 2 includes a plurality of land portions 10a, 10.
b, 11a, 11b and 12, and annular groove 13a,
13b, 14a, 14b and an internal passage 15, and the lands 10a, 10b, 11a, 11b, 12 of this spool 16 are slidably fitted into the spool 16, and a plurality of passages (to be described later) are opened inside the spool 16. hole 17, supply passage 18 and load check valve 1
It has 9. The plurality of passages opening into the inner hole 17 are load passages 20 connected to the actuator.
a, 20b, and tank passage 2 connecting to tank 3
1, a bridge passage 22 connected to the supply passage 18 via a load check valve 19, and first unload passages 23a, 23b connected to the discharge side of the pump 1.
When a directional control valve is connected to the rear stage, a first unload passage 24 is connected to the rear stage, and a second unload passage 24 is connected to the tank 3 when a directional control valve is not connected to the rear stage. Note that one of the pilot passages 26a and 26b is connected to a pressure compensation valve 4 and a cutoff valve 5, which will be described later, and the other
Connected to the annular grooves 25a and 25b.

This directional control valve 2 having each passage and a spool is configured so that when the spool 16 is in the neutral position shown in FIG. The first and second unloading passages 23a, 23
b, 24 are connected to the annular grooves 14a, 14b, and the pilot passages 26a, 26b are connected to the spool 1.
It is connected to the tank passage 21 via the internal passage 15 of 6. Next, when the spool 16 is started to be operated from the neutral position to the right, the lands 11a and 12 close the first and second unload passages 23, 23b and 24, and the pilot passage 26a moves to the load passage 20a.
The pilot passage 26 is connected to the tank passage 2.
It is blocked from 1. The annular groove 13b is the load passage 2
0b and the tank passage 21 are connected. Then, when moving further, the bridge passage 22 and the load passage 20a
are connected via the aperture 9a of the land portion 11a and the annular groove 13a. In this position, the pressure fluid supplied from the pump 1 to the supply passage 18 flows into the actuator A via the load check valve 19, the bridge passage 22, the throttle 9a, and the load passage 20a. The discharge fluid from the actuator A is transferred to the load passage 20b, the annular groove 13b, and the tank passage 21.
Flows into tank 3 via. Furthermore, at this time,
The load pressure of the load passage 20a acts on the pilot passage 26a.

The above describes how the flow rate of the pressure fluid supplied to the actuator A at the intermediate operating position is controlled by the throttle amount of the throttle 9a. And further spool 1
6 to the right, a fully operated position is reached where the load passage 20 and bridge passage 22 are connected via the annular groove 13a. At this time, the connection relationships of the other passages are the same as in the intermediate operation position. On the other hand, spool 1
6 to the left, the load passage 20a is connected to the tank passage 21, the load passage 20b is connected to the bridge passage 22, and in the intermediate operating position, the throttle 9
Since this case is almost the same as the above case except that b narrows down the gap, that is, the connection relationship of the passages is reversed, detailed explanation thereof will be omitted.

The pressure compensating valve 4 is connected to a control section 30 having a function of discharging the discharge pressure fluid of the pump 1 to the tank 3, and is connected to the control section 30, and is configured to adjust the pressure compensating valve 4 according to the load acting on the actuator connected to the directional switching valve. It consists of a pilot section 31 on which pressure fluid (hereinafter referred to as load pressure) acts.

The control unit 30 controls a discharge circuit 8a connected to the discharge side of the pump 1 and a supply passage 18 of the directional control valve 2.
An annular groove 32 connected to the discharge circuit 8b connected to the tank 3, an annular groove 32 connected to the tank 3, and an inner hole 37 into which a spool 36 having two land parts 34a, 34b and a small diameter part 35 is slidably fitted. A pressure chamber 39 formed by the inner hole 37 of the main body 38 and the spool 36 and connected to the annular groove 32 via the internal passage 42 of the spool 36 and a tension force that constantly presses the spool 36 to the left. The ball valve 5 of the pilot section 31 is connected to the annular groove 32 through an internal passage 42 and is
A spring chamber 40 is formed with a passage 43 that is closed at 0 and a spring chamber 40 that is open. The pilot section 31 is connected to the control section 30
an inner hole 47 formed integrally with the main body 38 and into which the plunger 46 is slidably fitted, and a passage 51.
It communicates with the tank 3 through the inner hole 47 and is formed with an inner hole 48 in which the ball valve 50 is located.
9 is formed by a spring chamber 52 in which the spring 9 is stretched.

The spool 36 of this pressure compensating valve 4 is connected to the pressure chamber 3.
9, the pressing force due to the fluid pressure acting inside the spring chamber 40, and the pressing force due to the fluid pressure acting inside the spring chamber 40.
It operates by the difference between the sum of the pressing forces of 1 and 1, and forms a diaphragm between the annular grooves 32 and 33. Then, the fluid pressure in the spring chamber 40 is controlled by the pilot plunger 3.
1.

The cutoff valve 5 disposed between the spring chamber 40 of the pressure compensation valve 4 and the tank 3 is connected to the spring chamber 40 of the pressure compensation valve 4.
A main body 45 has an annular groove 55 connected to the tank 3, an annular groove 56 connected to the tank 3, and an inner hole 58 into which the spool 57 is slidably fitted, and the inner hole 58 of the main body 45 and the land 59 of the spool 57 are connected to each other. A pressure chamber 61 is thus formed and connected to the pilot passage 51.
and a spring chamber 64 which is formed by an inner hole 58 and a land 60, is constantly connected to the tank 3 via an internal passage 63 of the spool 57, and has a spring 62 tensioned therein. In this shutoff valve 5, the spool 57 moves to the left due to the fluid pressure in the pilot passage 51, thereby shutting off between the spring chamber 40 of the pressure compensating valve 4 and the tank 3. Note that 70 is a relief valve provided between the discharge circuit 8a of the pump 1 and the tank 3, and controls the discharge fluid pressure of the pump 1.

The operation of this embodiment will be described below.

Pump 1 with directional valve 2 in neutral position
The discharge pressure fluid is supplied to the supply passage 18, the first and second unload passages 23 via the discharge circuits 8a and 8b.
a, 23b, and 24. The supply passage 18 is
Since the bridge passage 22 is closed by the spool 16, the first and second unload passages 23a, 23
b, 24 to the tank 3, while the spring chamber 40 of the pressure compensating valve 4 is connected to the tank 3 via the shutoff valve 5, so the spool 36 of the pressure compensating valve 4 moves to the right. Then, the discharge circuit 8a is connected to the tank 3. Therefore, the discharge pressure fluid of the pump 1 is transferred to the tank 3 via the switching valve 2 and the pressure compensating valve 4.
leaks to. At this time, the fluid pressure in the discharge circuits 8a, 8b becomes a value corresponding to the tension of the spring 41 of the spring chamber 40.

Next, operate the spool 16 of the directional control valve 2 to the right, and the first and second unload passages 23a, 23b
After the bridge passage 22 and 24 are cut off, the bridge passage 22
When reaching the intermediate operating position where the load passage 20a and the load passage 20a are connected via the throttle 9a, the discharge pressure fluid of the pump 1 is transferred to the load passage 20a via the supply passage 18, the load check valve 19, the bridge passage 22, and the throttle 9a.
flows into. At this time, the fluid pressure in the load passage 20a is increased via the pilot passages 26a and 51.
It acts on the pressure chamber 61 of the shutoff valve 5 and the spring chamber 52 of the pilot section 31 of the pressure compensation valve 4. Therefore, the spool 57 of the cutoff valve 5 moves to the right to cut off the gap between the tank 3 and the spring chamber 40 of the pressure compensating valve 4. Fluid pressure spring 49 within chamber 52
The fluid pressure becomes in accordance with the pressing force of the spool 36.
moves to the left and begins to squeeze the space between the annular grooves 32 and 33.

The fluid pressure in the discharge circuits 8a and 8b of the pump 1 increases according to the amount of restriction between the annular grooves 32 and 33 of the pressure compensating valve 4, and the fluid pressure increases depending on the amount of restriction between the annular grooves 32 and 33 of the pressure compensation valve 4. aisle 2
The actuator flows in via 0a. At this time, the fluid pressure on the upstream side of the throttle 9a acts on the pressure chamber 39 via the internal passage 42 of the spool 36 of the pressure compensating valve 4, so the spool 36
2 and 33 so that the fluid pressure on the upstream and downstream sides of the pilot section 31 is maintained at a value corresponding to the pressing force of the spring 49 of the pilot section 31.

Next, even if the load increases or decreases during operation of the actuator, the load pressure is transferred to the pilot section 3 through the pilot passages 26a and 51.
1 of the spring chamber 52, the spool 36 of the pressure compensating valve 4 responds to increases and decreases in load pressure.
The fluid pressure on the upstream and downstream sides of the throttle 9a of the directional control valve 2 is operated according to the load pressure, and the differential pressure is maintained at a constant value according to the pressing force of the spring 49 in the spring chamber 52 of the pilot section 31. . Therefore, the actuator operates at a constant speed depending on the amount of operation of the spool.

The case where the spool 16 of the directional control valve 2 is operated to the right has been described above, but when the spool 16 of the directional control valve 2 is operated to the left, the pressure compensating valve 4 compensates for the difference in fluid pressure between the upstream side and the downstream side of the throttle 9b. 31 is maintained at a constant value according to the pressing force of the spring 49 in the spring chamber 52. Note that other operations are substantially the same as those described above, so detailed explanation thereof will be omitted.

In addition, in the above-mentioned embodiment, the directional control valve 2
Although this is a center bypass type directional control valve, the present invention is not limited to this structure.

That is, as is clear from the description of the embodiment, when the directional control valve 2 is in the neutral position, the discharge pressure fluid of the pump 1 is caused to flow out to the tank 3 by the pressure compensating valve 4. 2. No center bypass passage is required. However, even if it is a center bypass type, no particular inconvenience will occur.

(Effects of the Invention) As described above, the present invention provides a directional control valve having a spool that forms a restriction between a pressure fluid source and an actuator, and a discharge pressure of the pressure fluid source is provided on the upstream side of the directional control valve. A compound valve equipped with a pressure compensation valve that divides a part of the fluid into a tank and controls the differential pressure across the throttle of the directional control valve to a constant value, wherein the pressure compensation valve is connected to the discharge side of the pressure fluid source. It has a pressure chamber connected to the spring chamber and a spring chamber connected through the throttle.
A control section is provided with a spool for controlling the connection between the pressure fluid source and the tank, and the hydraulic pressure in the spring chamber of the control section is controlled by a control section provided between the spring chamber of the control section and the tank, for setting a differential pressure. The directional control valve is connected to the tank when the directional control valve is in the neutral position, and when the directional control valve is in the neutral position, the actuator is activated. A pilot passage connected to the load side is connected, and a barrier is provided between the spring chamber of the control unit and the tank to close the gap between the spring chamber of the control unit and the tank by load pressure from the pilot passage. It has a configuration with a valve.

When the directional control valve is placed in the neutral position and the load pressure reaches the tank pressure, the spring chamber of the pressure compensating valve is connected to the tank via the shutoff valve. In addition, when the directional control valve is operated and load pressure acts on the pilot passage, the shutoff valve shuts off between the spring chamber of the pressure compensation valve and the tank. Controlled according to pressure, pressure compensation valve operates.

As described above, the present invention is configured such that the pressure compensating valve controls the hydraulic pressure in the spring chamber according to the load pressure in the pilot passage only when its function is necessary. Load oil pressure can be lowered. (In this regard, the conventional technology
The pressure compensating valve always secures unloading hydraulic pressure that is greater than the pressure loss of the directional control valve, and when the directional control valve is operated, this hydraulic pressure ensures the flow of pressure oil to the actuator, so directional control is possible. High unload pressure also occurs when the valve is in the neutral position. ) Furthermore, since the operation of the shutoff valve is controlled by a single pilot passage connected to the pilot valve section, it can be linked to the operation of the directional control valve, which improves the operability of the actuator and reduces power loss. It has the effect of reducing

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention. 2 is a circuit diagram including a cross-sectional view similar to the circuit shown in FIG. 1; FIG. FIG. 3 is a circuit diagram of the prior art. 1... Pressure fluid source, 2... Directional switching valve, 3...
Tank, 4...Pressure compensation valve, 30...Control unit, 3
1... Pilot section, 36... Spool, 39...
...pressure chamber, 40...spring chamber, 41...first spring,
47...Inner hole, 52...Spring chamber, 57...Spool, 58...Inner hole, 60...Land, 61...Pressure chamber, 62...Spring chamber, 5...Shutoff valve.

Claims (1)

[Scope of Claims] 1. A directional switching valve having a spool forming a restriction between the pressure fluid source and the actuator is provided, and a part of the pressure fluid discharged from the pressure fluid source is transferred to a tank on the upstream side of the directional switching valve. A compound valve comprising a pressure compensating valve that divides the flow and controls the differential pressure across the throttle of the directional control valve to a constant value, the pressure chamber connecting the pressure compensating valve to the discharge side of the pressure fluid source and the throttle. has a spring chamber connected through
A control section is provided with a spool for controlling the connection between the pressure fluid source and the tank, and the hydraulic pressure in the spring chamber of the control section is controlled by a control section provided between the spring chamber of the control section and the tank, for setting a differential pressure. The directional control valve is connected to the tank when the directional control valve is in the neutral position, and when the directional control valve is in the neutral position, the actuator is activated. A pilot passage connected to the load side is connected, and a barrier is provided between the spring chamber of the control unit and the tank to close the gap between the spring chamber of the control unit and the tank by load pressure from the pilot passage. A composite valve characterized by having a valve.