JPS598684B2 - fluid control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid control device in which the operating speeds of a plurality of actuators are individually or simultaneously made to correspond to the opening of a flow direction control valve, independently of changes in load. By always making the set pressure of the pump discharge fluid correspond to the load pressure, loss of power and heat generation of the fluid can be suppressed to a minimum, and surplus fluid can be effectively used to connect a separate actuator to the above-mentioned actuator. It is characterized by pressure compensation control independent of operation.

Conventionally, when a circuit is configured in which a flow rate regulating valve with a pressure compensation valve is provided in each parallel circuit branched from a single pump, and pressure compensation control is performed for each actuator provided in each of these parallel circuits, it is difficult to process surplus fluid. was a problem.

That is, the loads applied to each actuator vary individually, and it is inevitable that one load will be larger or smaller than the other.

For this reason, there is no preferred method for handling the surplus flow other than installing a main relief valve on the outlet side of the pump, which takes into account the minimum safety level of the fluid circuit or various control equipment.

Therefore, a surplus flow is generated, and the surplus flow is always bypassed at the set pressure of this IJ valve.
Therefore, there was a drawback that the loss of power and the heat generation of the fluid were very large.

In view of these points, the present invention installs a flow rate directional control valve with a pressure compensation valve in each parallel circuit branched from a single pump and connected to a plurality of actuators, and a bypass circuit provided in parallel with these parallel circuits. A bypass type pressure control valve is installed in the bypass type pressure control valve, and the back pressure chamber of the bypass type pressure control valve is connected to the downstream side of the flow rate adjustment section in each of the above-mentioned flow rate directional control valves with pressure compensation valves via a shuttle valve. By this,
When operating a single load, the pressure corresponding to that load is guided to the back pressure chamber of the bypass type pressure control valve, and when operating multiple loads, the pressure corresponding to the heavier load is guided to the back pressure chamber of the bypass type pressure control valve. the inlet operating pressure of the bypass type pressure control valve;
In other words, the pump pressure always corresponds to the load to reduce power loss and heat generation of the fluid, and the surplus bypass fluid from the bypass type pressure control valve is merged with the discharge fluid of the separate second pump. The bypass fluid is effectively used to control a separate actuator in a pressure compensated manner.

Embodiments of the present invention will be described below based on the drawings.

The present invention includes a pressure supply source consisting of a first pump 40 and a second pump 41, and a plurality of flow rate adjustment mechanisms C1 and C with pressure compensation valves.
2..., one bypass type pressure control valve 31, and one bypass type pressure compensation valve equipped flow rate adjustment valve 45
It consists of

That is, the parallel circuit Sat6b, 7 of the first pump 40 includes a plurality of flow rate adjustment mechanisms with pressure compensation valves CIFC2...
... and a bypass type pressure control valve 31, and further, pressure reducing type pressure control valves 20, 20' are respectively provided on the pump side of the flow rate directional control valves 1, 1' in each flow rate adjustment mechanism with a pressure compensation valve. , the pressure is applied to the control valves 20, 20' (7
) The circuits 8a and 8b branched from the back pressure chamber are connected to the shuttle valve 1.
20 and the outlet side of the shuttle valve 12 is connected to the back pressure chamber of another bypass type pressure turbidity valve 31 via the circuit 9.

A specific example of the pressure compensation valve-equipped flow rate adjustment mechanisms C1 and C2 described above has a structure as shown in FIG.

That is, the flow rate adjustment mechanisms C1 and C2 with pressure compensation valves are four-way all-port block type neutral vent amplifiers. It consists of a flow direction control valve 1 with a load passage and a pressure reducing type pressure control valve 20 with a pilot relief valve.

The flow directional control valve 1 has an inlet in the housing 2 which communicates with a pump 40 via a pressure control valve 20. Port P'
, A port A, B port B, and T port T, and direction control is performed between these four ports }P', A, B, and T.

In other words, when the spool 3 provided inside the housing 2 is held at the neutral position (the state of the imaginary line), each of these ports
Communication between P', A, B, and T is completely cut off, and by positioning the spool 3 at the position indicated by the solid line, a flow rate adjustment section 5 can be formed between the spool land 4 and the corner of the housing 2, In the flow from the inlet port P' to the A port, a flow rate corresponding to the opening degree of the flow adjustment section 5 can be obtained.

Therefore, the actuator 10 connected between the A and B ports can be operated at a speed corresponding to the flow rate.

Furthermore, when the spool 3 is moved to the right from the neutral position, a flow rate adjustment section 5' is formed by the spool land 4 and the corner of the housing, so that the actuator 10 can be controlled in the opposite direction.

On the other hand, the pressure reducing type pressure control valve 20 with a pilot valve has a P port P connecting the pump 40 to a housing 21, a plunger 22 inside the housing, and a plunger 22 inside the housing.
A pilot relief valve 23 is provided on the right side of 2.

The land 24 on the left side of the plunger 22 and the housing 2
A pressure control section Y is formed between the corner of the plunger 22 and the pilot relief valve 23.
It is set in a normally open state by 6 forces.

Furthermore, a passage 27 is formed inside the plunger 22 to guide the rear pressure of the pressure control section Y to the left end of the plunger 22, and the back pressure chamber 25 is connected to the flow direction control valve 1.
The back pressure chamber 25 is connected to the T port T when the spool 3 is in the neutral state by connecting to the pilot passage 28 and the vent passage 29 opened on both sides of the flow rate adjustment parts 5, 5'.
When the spool 3 is displaced, a load 11 is applied to the actuator 10 through the pilot passage 28 to the back pressure chamber 25.
It is configured to apply a corresponding pressure of .

Therefore, when the actuator 10 is operated at a flow rate corresponding to the opening degree of the flow rate adjusting section 5 as shown in FIG.
The force added to the plunger 2 is acting on the plunger 2.
The corresponding pressure of the load 11 and the resistance pressure of the flow rate regulator 5 act additively on the left end of the plunger 22 via the passage 2T.
to the right to make the pressure control section Y close.

In other words, depending on the opening degree of the pressure control section Y, the flow rate adjustment section 50
It performs a pressure reducing action so that the differential pressure before and after and the force of the spring 26 are balanced, and performs control to always keep the differential pressure before and after the flow rate adjustment section 50 constant.
The excess fluid is diverted through the circuit 7 to a bypass type pressure control valve 31, which will be described later.

As a result, even if the load 11 on the actuator 10 changes, the pressure reducing type pressure control valve 20 maintains the differential pressure before and after the flow rate adjustment section 5 constant, so that the operating speed of the actuator 10 can be adjusted by changing the displacement of the spool 3. It can be held at a value depending on the

On the other hand, in a specific example of the bypass type pressure control valve 31, a pump 40 is connected to a housing 32 via a circuit 7 as shown in FIG.
A plunger 34 is provided inside the housing, and a pilot relief valve 35 is provided to the left of the plunger 34.

A diversion control section 2 is formed between the land of the plunger 340 and the corner of the housing. It is set in a normally closed state by the force of spring 37.

Furthermore, a so-called bypass line 38 is connected to the port g formed at the rear of the shunt control section 2, and a pilot passage 39 branched from the front of the shunt control section Z is connected to the chamber 36a at the right end of the plunger 34. Plunger 34
A circuit 9 communicates with the rightmost chamber 36a to apply pressure supplied from the pump to the chamber, and is also connected to the back pressure chamber 36.
A load pressure is applied to the back pressure chamber 36 through the back pressure chamber 36.

Therefore, when the load pressure acting on the back pressure chamber 36 is lower than the set pressure of the pilot relief valve 35, the pressure fluid flowing into the housing from the port 33 combines the fluid pressure in the back pressure chamber 36 and the spring 3γ force. The divided flow control section 2 uses the added value.
Bypass more.

Note that when the load pressure acting on the back pressure chamber 36 is greater than the set pressure of the pilot relief valve 35, the fluid control pressure corresponds to the relief set pressure.

On the other hand, as shown in FIG. 1, a check valve 44 is installed at the confluence of the bypass line 38 and the discharge line 42 of the second pump 41 connected to the first pump 40 by a single shaft so that the bypass flow becomes a free flow. are doing.

The check valve 44 has a second pump pressure lower than the discharge pressure of the first pump 40.
This helps prevent backflow when the discharge pressure of the pump 41 increases.

On the other hand, a flow rate adjustment mechanism 45 with a pressure compensation valve connected to a confluence line 43 between the bypass line 38 and the discharge line 42
is equipped with a bypass type pressure control valve 47 with a pilot relief valve on the pump side of the flow direction control valve 46.

The structure of the flow direction control valve 46 is a four-way all-port block type neutral pent unload type, which is exactly the same as that shown in FIG.

Further, the bypass type pressure control valve 47 is the same as the control valve shown in FIG.

As explained based on FIG. 3, such a normally closed pressure control valve applies load pressure to the back pressure chamber 36, and always adds the load pressure and the spring 37 pressure to the pressure in front of the pressure control section 2. The excess flow is bypassed to maintain the specified value.

Therefore, the flow rate adjustment mechanism 45 with a pressure compensating valve can always maintain the flow rate passing through the flow direction control valve 46 constant in accordance with the spool 3 by the action of the bypass type pressure control valve 470.

The illustrated embodiment is constructed as described above, and its operation will be explained below.

When the two flow rate directional control valves 1 and 1' are both set to be closed, the back pressure chamber of the bypass type pressure control valve 31 is connected to the circuit 9, the shuttle valve 12, or one of the circuits 8
a or 8b and directly to the tank 13 via the pent unload passage 29.

Therefore, when fluid is discharged from the first pump 40 in such a state, the fluid discharged from the first pump 40 is in the /J direction of the highest load,
That is, it is supplied to the bypass type pressure control valve 31 via the circuit 7, and the entire amount is bypassed from the bypass line 38 to the discharge line 42 of the second pump 41 at the set pressure of the spring 37 of the bypass type pressure control valve 31.

Next, a description will be given of the operation of operating the actuator 14 via, for example, the flow rate adjustment mechanism C1 with a pressure compensation valve on the right side.

When the flow rate directional control valve 1 is displaced from the neutral position, the pent unload passage 29 is closed, and a pressure corresponding to the load of the actuator 14 is first applied to the back pressure chamber of the pressure reducing type pressure control valve 20, and then The same negative pressure is applied to the back pressure chamber of the bypass type pressure control valve 31 via the shuttle valve 12.

Therefore, the fluid discharged from the first pump 40 begins to be supplied toward the actuator 14, and the operating speed of the actuator 14 can be controlled to a constant level by the pressure compensation function described based on FIG. .

Moreover, in performing the above control, excess fluid can be bypassed to the discharge line 42 of the second pump 41 via the bypass type pressure control valve 31 at a pressure corresponding to the load.

Furthermore, even if the load of the actuator 14 changes during such control, the corresponding pressure of the load is always applied to the back pressure chamber of the bypass type pressure control valve 31 via the shuttle valve 12. It has become.

Therefore, the inlet operating pressure of the bypass type pressure control valve 310 always has the characteristic of corresponding to the load.

Next, when both flow rate directional control valves 1, 1' are opened, the load pressure of the two actuators 14, 14' acts on both sides of the shuttle valve 120 via the circuit B a t 8 b. The larger of the two load pressures acts on the back pressure chamber of the bypass type pressure control valve 31.

Even if the relative magnitudes of the loads on the two actuators 14, 14' are reversed, the directional control of the shuttle valve 12 ensures that the inlet operating pressure of the bypass type pressure control valve 310 always corresponds to the heavier one of the two actuators. .

Furthermore, even when the discharge amount of the first pump 40 cannot satisfy the control amounts of the two actuators, that is, when the flow rate is insufficient, the operating pressure at the inlet of the bypass type pressure control valve 310 corresponds to the one with the heavier load.

In this case, there will be no bypass surplus flow, but since the inlet operating pressure is reliably maintained at the pressure corresponding to the heavier load, the fluid discharged from the first pump 40 will be lighter without pressure interference. The heavier load side is supplied with priority, and the residual fluid is supplied in an uncontrolled manner to the heavier load side.

Each pressure reducing type pressure control valve 20, 20' is equipped with a pilot relief valve 23, 23', respectively. In FIG. 2, when the pressure in the back pressure chamber 25 rises above a predetermined pressure, the pilot relief valve 23 opens and Control section Y is completely closed.

Therefore, the front pressure of the actuator 10 is controlled by the pressure set by the pilot relief valve 23.

Therefore, by individually adjusting the set pressure of the pilot relief valve of each flow rate adjustment mechanism 20, 20', the maximum control pressure of each actuator can be set to a different value.

As described above, when a single load is operated, the inlet operating pressure of the bypass type pressure control valve 310 always corresponds to changes in the load, and when multiple loads are operated, it always corresponds to the largest load. It is something to do.

Therefore, compared to a fixed bypass system such as the conventional IJ IJ-7 valve, which takes into account the minimum safety level of the circuit and control equipment, the power loss is small and the amount of heat generated by the fluid can be suppressed.

On the other hand, when the flow direction control valve 46 of the flow rate adjustment mechanism 45 with pressure compensating valve connected to the discharge line 42 of the second pump 41 is set to the neutral position, the entire amount of fluid discharged from the second pump 41 is under pressure. It is bypassed to tank 13 via control valve 47.

If the bypass line 38 of the bypass type pressure control valve 31
If there is a surplus flow in the second pump 41, the surplus flow is transferred to the second pump 41.
It joins with the discharge fluid of and is bypassed by the bypass type pressure control valve 47.

Therefore, when the flow rate directional control valve 46 is displaced from the neutral position in the flow rate adjustment mechanism 45 with pressure compensation valve, the second pump 4
The fluid discharged from the bypass line 38 begins to be supplied to the actuator 48, and when surplus fluid is generated in the bypass line 38, the operating flow rate of the actuator 48 is ensured by joining with the surplus fluid.

The fluid discharged from the first pump 40 is the actuator 1
4 and 14', and only the surplus fluid is bypassed to the bypass line 38.

In such a case, the discharge pressure of the first pump 40 corresponds to the one with the heaviest load among the three actuators 14, 14', 48, while the fluid discharged from the second pump 41 This ensures that the actuators 48 of the above are activated preferentially.

Therefore, the first pump 40 and the second pump 41 are connected to the actuators 1 4 , 1 4' and the other actuators 48
This is to ensure the absolute flow rate for the

As described above, the present invention branches out from a single pump 40 and includes a plurality of actuators 14, 14'--.
Parallel circuits 6aj6b connected to ・Flow rate adjustment mechanisms C1, C2 with pressure compensation valves, respectively.
..., and a bypass type control valve 31 is installed in a bypass circuit provided in parallel with these parallel circuits, and the back pressure chamber of the bypass type pressure control valve and the flow rate adjustment with each pressure compensation valve are installed. The downstream side of the flow rate adjusting section in the valves 1, 1', . Connected to the discharge line 42, the first pump 400 and the second pump 41
The other actuator 4 is activated by the combined fluid with the discharge fluid of
8 is subjected to pressure compensation control.

Therefore, when operating a single load with pressure compensation,
The opening value of the bypass type pressure control valve 31 is determined in response to a change in the load of the load, and when a plurality of loads are operated for pressure compensation, the opening value corresponds to the heavier load. .

Therefore, compared to the conventional bypass system using a main relief valve with a fixed opening value, the amount of power loss can be reduced, and the amount of heat generated by the fluid due to energy loss can be suppressed to a small value.

Further, the chatot valve 12 is located in either of two directions, so that the back pressure chamber of the bypass type pressure control valve 31 is communicated with either of the actuators 14, 14', so that the operation of the pressure control valve 31 is not obstructed. That's what I do.

Therefore, there is no need to open the vent path of the pressure control valve 31.

Therefore, the flow rate supplied to each actuator accurately corresponds to the opening degree of the flow direction control valves 1 and 1', and the flow rate is maintained constant even when the load changes, allowing actuator operation to be performed with high precision. There are effects that can be controlled.

Moreover, each of the flow rate adjustment mechanisms C1 and C2 is a pilot I
JIJ-Constructed of pressure reducing type pressure control valves 20 and 20' with valves, the pilot relief valve allows the maximum control pressure of each actuator to be set to a different value, and at the same time allows the surplus fluid of the first pump to be used effectively. The first pump compensates the flow rate independent of the operation of a separate actuator, and the second pump compensates the flow rate of the separate actuator to a plurality of actuator groups that are available to and supplied from the first pump. This ensures a minimum second pump flow rate independent of the group.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams of main parts. C1, C2...Flow rate adjustment mechanism with pressure compensation valve, 1
, 1'...Flow rate directional control valve, 3...Spool, 5, 5'...Flow rate adjustment section, 6a,
6 b, 7... parallel circuit, 10...
Actuator, 11...Load, 12...
...Shuttle valve, 14, 14', 4B...
Actuator, 20... pressure reducing type pressure control valve,
22... Plunger, 23... Pilot valve, 25... Back pressure chamber, 29, 29'...
... Pent unload passage, 31 ... Bypass type pressure control valve, 34 ... Plunger, 36 ...
... Back pressure chamber, 38 ... Bypass line, 3
9...Pilot passage, 41...2nd
Pump, 42...Discharge line, 43...
One confluence line, 44...Check valve, 45...
...Flow rate adjustment mechanism with pressure compensation valve, 46...
Flow rate directional control valve, 47... Bypass type pressure control valve.

Claims (1)

[Claims] 1 Parallel circuit 6a+6b branched from a single pump 40
A plurality of flow rate adjustment mechanisms C1, C2 with pressure compensating valves installed in...... and each of these flow rate adjustment mechanisms C1, C2... A plurality of actuators 14, 14', respectively connected to...
. . . and a single bypass type pressure control valve 31, each of the above-mentioned pressure compensation valve equipped flow rate adjustment mechanisms C1, C2
. . . are respectively a flow rate directional control valve 1 and a pressure reducing type pressure reducing type with a pilot relief valve on the pump side of the flow rate directional control valve 1 to keep the differential pressure before and after the flow rate directional control valve 1 constant. The back pressure chambers of each pressure reducing type pressure control valve 20, 20'...... are connected to the inlet side of both ends of the shuttle valve 120, and the outlet of the shuttle valve 12 is side is connected to the back pressure chamber of the bypass type pressure control valve 31, and among the actuator load pressures in the parallel circuit,
While the maximum load pressure is selected by the shuttle valve 12 and led to the back pressure chamber of the bypass type pressure control valve 31, a bypass line 38 separately branched from the bypass type pressure control valve 31 is connected to the other second line. Discharge line 4 of pump 41
2, and the merging line 43 is connected to another flow rate regulating valve 45 with a pressure compensation valve of the Nohama path type.