JPS5824642B2 - Tandou Act Yueta Seigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for a single-acting actuator, such as a ram-shaped cylinder, which can actuate a load by applying fluid pressure only in one direction, and proportionally controls both vertical and vertical movements of the actuator. The invention is characterized in that it also prevents the phenomenon of natural descent when stopped.

This type of actuator is used for elevating and lowering elevators, for example.
This type of elevator is used to raise the elevator using the pump discharge pressure, but has the characteristic that the weight of the load can be used to lower the elevator.

However, since the pump is stopped when the elevator is going down, it is very difficult to control the elevator to operate at a constant speed, regardless of the magnitude of the load, as when the elevator is going up.

Furthermore, it is impossible to install a check valve in the circuit of a single-acting actuator to prevent natural downward movement when the actuator is stopped, and therefore the stopping accuracy is low.

The present invention was invented in view of the above points, and although the purpose is to create an extremely simple circuit, it not only provides speed proportional control when the actuator is ascending, but also speed proportional control even when the pump is stopped during descending. In addition, a check valve that is opened by the fluid pilot when the actuator is lowered is provided to ensure good stopping accuracy.Furthermore, even if the fluid pump is stopped, the load pressure is used to switch the flow rate directional control valve when the single-acting actuator is lowered. The reason is that it has been made possible to operate.

The configuration of the present invention includes a neutral position where the A port is opened to the T port, a first switching position where the P port is opened to the B port and a variable orifice is formed between these ports, and a first switching position where the B port is opened to the T port. , and a second switching position forming a variable orifice between these ports, the valve is a 4-point, 3-position type flow directional control valve having a check valve seal such that the direction of the actuator is free flow at the B port. A pressure reducing valve is connected and a pilot check valve is interposed between the pressure reducing valve and the single acting actuator, while a branch line branching from the P port and a connection line connecting to the A port are connected via a shuttle valve to an electromagnetic line. The control port of the electromagnetic pilot valve is connected to the pressure port of the pilot valve, and the control port of the electromagnetic pilot valve is connected to both pilot chambers of the flow direction control valve. and connects the A port side of the throttle to the pilot chamber of the pilot check valve, while connecting the flow path between the actuator and the pilot check valve via
A branch flow control type pressure compensator is interposed in a branch flow line branching from the P port, and when the spring side of the plunger in the pressure compensator is set to the first switching position, the flow direction control valve is set to the first switching position. This is a single-acting actuator control device in which the anti-spring side of the plunger is communicated with the P port.

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

The embodiment shown in FIG. 1 is constructed by incorporating a proportional control device C, a check valve sealed pressure reducing valve 4, a pilot check valve 5, a shuttle valve 6, and an electromagnetic pressure reducing valve 7 between a fluid pump 1 and a single acting cylinder 3. There is.

The flow rate proportional control device C comprises a pressure control valve 10 and a hydraulic pilot type flow rate directional control valve 30, a specific example of which is shown in FIG.

Namely. The pressure control valve 10 is composed of a pressure compensator 11 of a branch control type and a pilot relief valve 12.

The plunger 13 of the pressure compensator 11 separates the first firebox 14, the second firebox 15, and the duty chamber 16, and the primary chamber 14 communicates with the pump port P, and the pump port P is connected to the The supply line 18 of the fluid pump 1 is connected as shown in FIG.

Further, a branch port 19 is opened in the second firebox 15, and as shown in FIG. 1, the branch port 19 is connected to a return line 22 to a tank 21 via a branch line 20.

Furthermore, a spring 23 for pressure setting is installed in the back pressure chamber 16, and the pilot relief valve 12 is connected to the valve seat 2.
4 with a spring 25, and the line link 2
5 force is adjusted by a threaded rod 26.

Further, the flow rate directional control valve 30 has a four-point valve 3 having a neutral position, a first switching position, and a second switching position as shown in FIG.
This is a position type flow rate directional control valve, and in the neutral position, A port A is opened to T port 1-T, and P port P and B port B are closed.

At the first switching position, P port P is opened to B port B, A port A is opened to T port 1-T, and P and B ports P
, B, a variable orifice 40a is formed between them.

Furthermore, in the second switching position, P port P is changed to A port) A,
The B port B is opened to the T port T, and a variable orifice 40b is formed between the B and T ports B and T. Specifically, the structure is as shown in FIG. 2.

That is, the housing 31 has a port 32 that communicates with the P port P via one firebox 14 of the pressure control valve 10, a T port T that connects the return line 22, and two A,
B ports A and B are formed, and 3 lands 3 are formed inside.
Spools 39 of 6, 37, and 38 types are provided to form a center AR connection type.

By displacing the spool 39 to the left, a variable orifice 40a is formed between the corner of the land 36 and the corner of the housing 31, and by displacing the spool 39 to the right, the corner housing of the land 38 is formed. 31, and a feedback passage 41 with one end opened near the variable orifice 40 on the B port side is connected to the back pressure chamber 16 via a throttle 42. are doing.

Further, the spool 39 is formed with a switching portion 44 of a vent passage 43 that communicates the back pressure chamber 16 and the T port 1-T, and the secondary side of the pilot relief valve 12 is connected to the T port via a drain circuit 45. (po) T is connected.

A check valve-sealed pressure reducing valve 4 is connected to the B port 1-B of the flow direction control valve 30, and the pressure reducing valve 4 and the single acting cylinder 3 are connected via a pilot check valve 5.

These check valves 4a and 5 are both installed so that free flow occurs in the direction from the pump to the actuator, and the pressure reducing valve 4b has a constant secondary pressure.

Further, a connection line 8 having one end connected to the A port A of the flow direction control valve 30 and a branch line 9 having one end connected to the outlet side of the fluid pump 1 in front of the P port P are connected to both ends of the shuttle valve 6. The outlet line 6a of the shuttle valve 6 is connected to the inlet of the electromagnetic pressure reducing valve 7.

A specific example of the electromagnetic pressure reducing valve 7 is a 4-port yTI'AIB! as shown in FIG. The main body 27 has a four-land type spool 28, and a solenoid 34, 34 is provided at both ends of the spool via centering springs 29, 29 and a bushing rod 33, as shown in FIG.

Therefore, when an electromagnetic force is applied from one of the spools 28 to displace the spool 28 as shown by the arrow in FIG. 3, the control fluid flowing into the pilot chamber 35 acts on the electromagnetic force. Thus, a control (depressurized) fluid corresponding to the electromagnetic force can be obtained by the action of the electromagnetic force and the control pressure that opposes it.

The pilot lines 46a and 46b, which have one end connected to the A' port and the A' port of the electromagnetic pressure reducing valve 7, are connected to the pilot chamber 47a of the flow direction control valve 30.

47b.

Further, a throttle 48 is provided in the connection line 8, and a circuit connected to the A port A side of the throttle 48 is connected to the pilot check valve 5.
connected to the pilot chamber of the throttle valve 6 of the throttle 48.
The circuit connected to the side is connected to the single-acting cylinder 3 via a 2-point, 2-position on-off valve 49.

It is connected to the flow path between the pilot check valves 5.

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

When the fluid pump 1 is driven, the discharge pressure of the fluid pump 1 is always guided to the electromagnetic pressure reducing valve 7 via the branch line 9 and the shuttle valve 6.

When the pressure reducing valve T is placed in the neutral position, no differential pressure is generated in the pilot chambers 47a, 47b at both ends of the flow direction control valve 30, and therefore the spool 39 is held neutrally by the centering spring rings 50, 50. be done.

In FIG. 2, the spool 39 is shown displaced to the left from the neutral position, but when the spool 39 is in the neutral position, the circuit between the fluid pump 1 and the single-acting cylinder 3 is interrupted, and In turn, the vent passage 43 is opened by the switching part 44.

In other words, the state is as shown in FIG.

In such a neutral state, the back pressure chamber 16 of the pressure compensator 11 communicates with the tank port T via the vent passage 43.

Therefore, in such a state, the fluid discharged from the fluid pump 1 is guided from the pump port P to one end of the plunger 13 via the passage 13a in FIG. communicate with.

As a result, the entire flow rate discharged from the fluid pump 1 is unloaded into the tank 21 via the diversion line 20.

The pressure loss in this case only slightly corresponds to the force of the spring 23 of the pressure compensator 11, and is extremely small.

After that, the following operation is performed to raise the single-acting cylinder 3.

That is, in the electromagnetic pressure reducing valve 7, the left solenoid 34 is energized and the right pilot chamber 47 of the flow direction control valve 30 is activated.
When a control pressure is applied to a, the spool 39 is displaced to a position where the control pressure acting on the right pilot chamber 47a and the force of the left spring 50 resisting it are balanced, as shown in FIG. 2, and the variable orifice 40a is excited. The load W can be increased by supplying the fluid discharged from the fluid pump 1 to the single acting cylinder 3 with the opening degree corresponding to the force.

At the same time, the vent passage 43 is closed by the switching part 44 by switching the spool 39 as described above, so that a pressure corresponding to the load W applied to the single acting cylinder 3 acts on the back pressure chamber 16 via the feedback passage 41. .

Therefore, the pressure compensator 11 enters the pressure compensation state as described below.

That is, the discharge pressure of the pump acts on one end of the plunger 13, and the load pressure and the spring 2 act on the back pressure chamber 16 at the other end.
3 forces are acting, and when the pump discharge pressure tends to be larger among these opposing forces, the pressure control orifice Z formed between the pump port P and the diversion port 19 is opened wide. The flow rate is adjusted to lower the pump discharge pressure, and on the other hand, when the pump discharge pressure tends to decrease, the opening degree of the pressure control orifice Z is decreased to increase the pump discharge pressure.

As a result, springs 2 are placed before and after the variable orifice 40a.
A pressure difference corresponding to the three forces is formed, and compensation is performed so that the pressure difference is always kept constant.

Therefore, no matter how the load changes, a flow rate proportional to the opening degree of the variable orifice 40a is always supplied to the single acting cylinder 3, and the load W can be increased at a constant speed.

If the load W abnormally increases during such a rising action and the pump discharge pressure increases beyond the set pressure of the pilot relief valve 12, the entire pump discharge amount will open the pressure compensator 11 and be relieved to the tank 21. The safety of the circuit can be measured by

In this case, the load is prevented from dropping naturally by the pilot check valve 5.

To stop the rising load W, the solenoid 34 of the electromagnetic pressure reducing valve 7 is demagnetized and the flow direction control valve 30 is returned to the neutral position, so that the pilot check valve 5 supports the load and allows the load to fall naturally. To prevent.

Both when the load stops and when the load increases as described above, the on-off valve 49 remains set as shown in the figure, and the fluid on the lower surface of the single-acting cylinder 3 flows through the on-off valve 49 to the connection line 8.
There will be no leakage.

In particular, the on-off valve 49 has a conical part formed at the tip of the main valve as is well known, and opens and closes the flow path by attaching and detaching this conical part to the valve seat of the housing. At position 49a, the pressure of cylinder 3 presses the conical part of the main valve against the valve seat, so cylinder 3
The amount of leakage from the connection line 8 to the connection line 8 is extremely small.

In other words, this embodiment utilizes the characteristic of the small leakage amount in the on-off valve 49. In addition to this characteristic, there is also a characteristic that allows the flow from the connection line 8 to the cylinder 3 to be a free flow. Not for use.

Note that the on-off valve 49 is required to have a small amount of leakage.

The normal position 49a is shown with the same symbol as the check valve to facilitate checking.

After that, to lower the stopped load, perform the following operation.

That is, switching is performed so that the on-off valve 49 is opened while the fluid pump 1 is stopped.

Ru.

As a result, the fluid in the cylinder 3 is transferred to the line 8 by the load W.
, 22 into the tank 21. In this case, pressure is generated on the right side of the shuttle valve 6 by the resistance of the throttle 48, and this pressure can be guided to the inlet of the electromagnetic pressure reducing valve 7.

Therefore, symmetrically with the case of rising above, the solenoid 3 on the right side
4 is excited to guide control pressure to the pilot chamber 47b on the left side of the flow rate directional control valve 30, and the P port and the A port and the B port and the T port are communicated with each other. A load pressure is generated between the valve and the throttle 48, and the pilot check valve 5 is opened.

Therefore, the single-acting cylinder 3 begins to descend due to the load.

In this case, the descending speed of the cylinder 3 is controlled as follows in accordance with the opening degree of the variable orifice 40b formed at the left corner of the rightmost land 38 of the spool 39.

That is, the pressure of the fluid pushed out from the single acting cylinder 3 increases due to resistance when passing through the variable orifice 40b of the flow direction control valve 30, thereby operating the pressure reducing valve 4b.

The constant secondary pressure type pressure reducing valve 4b responds to the secondary pressure and performs control to maintain the secondary pressure constant no matter how the primary pressure changes.

In other words, no matter how the load W changes, the pressure upstream of the flow direction control valve 30 is kept constant.

On the other hand, the rear part of the flow rate directional control valve 30 communicates with the tank 21,
Further, since the drain line of the pressure reducing valve 4b is connected to the return line 22, the pressure reducing valve 4b operates based on the return line pressure, so that the differential pressure before and after the flow direction control valve 30 is always kept constant.

Therefore, the flow rate pushed back from the single-acting cylinder 3 to the tank 21 is always maintained constant, and proportional control is performed to control the descending speed of the single-acting cylinder 3 with a flow rate proportional to the opening degree of the variable orifice 40b.

Although a cylinder is used as an example of the single-acting actuator in FIG. 1, it goes without saying that it may also be a fluid motor that winds up a load on a reel.

As described in detail above, the present invention has a neutral position where the A port is opened to the T port, a first switching position where the P port is opened to the B port and a variable orifice is formed between these ports, and a first switching position where the B port is opened to the T port. A four-point, one-three-position flow direction control valve 30 having a second switching position that opens to a port and forms a variable orifice between these ports, the actuator direction being free flow to the B port; A pressure reducing valve 4 with a check valve seal is connected, and a pilot check valve 5 is interposed between the pressure reducing valve 4 and the single acting actuator 3, while a branch line 9 branching from the P port is connected to the A port. The connecting line 8 is connected to the pressure port y of the electromagnetic pilot valve 7 via the shuttle valve 6, and the control port 1-A'B' of the electromagnetic pilot valve 7 is connected to both pilot chambers of the flow direction control valve 30. 47a and 47b, while the throttle valve 6 side of the throttle 48, which is interposed in the connection line 8, is connected to the flow path between the actuator 3 and the pilot check valve 5 via an on-off valve 49, and The A port side of 48 is connected to the pilot chamber of the pilot check valve 5, while a branch control type pressure compensator 11 is interposed in the branch line 20 branching from the P port, and the plunger in the pressure compensator 11 is connected to the pilot chamber of the pilot check valve 5. 1
When the flow direction control valve 30 is set to the first switching position, the spring side of the plunger 13 is communicated with the B port, and the opposite spring side of the plunger 13 is communicated with the P port. Variable orifice 40a that increases the load by controlling the pressure compensator 11
Since the actuator is controlled with a flow rate proportional to the opening degree, proportional control can be performed in which the rising speed of the actuator corresponds to the opening degree.

Further, when the load is lowered by the control action of the check valve sealing pressure reducing valve 4, the actuator is controlled with a flow rate proportional to the opening degree of the variable orifice 40b, so proportional control is performed in which the lowering speed of the actuator corresponds to the opening degree. be able to.

Furthermore, a check valve sealing pressure reducing valve 4 and a single acting actuator 3
A pilot check valve 5 is interposed in between, and a flow path opening/closing valve 4 between the pilot check valve 5 and the single acting actuator 3 is provided.
Since the actuator is connected to the connection line 8 through the line 9, it is possible to eliminate leakage from the actuator to the tank and improve the accuracy of the actuator's stopping.Moreover, the pump can be stopped by opening the on-off valve 49 when descending. Also, the pilot check valve 5 can be opened depending on the load pressure to allow the load to be lowered.

Therefore, the present invention allows the pilot check valve 5 to be opened by the load pressure even if the pump is stopped during descent, making it possible to insert a pilot check valve to improve the static accuracy of the single-acting cylinder as an actuator.
Moreover, it has the effect of being able to perform proportional control during lifting and lowering, regardless of changes in load.

Further, the control port A' of the electromagnetic pilot valve 7 is connected to both pilot chambers 4γa, 4γb of the flow direction control valve 30.
and connect the pressure port y of the pilot valve 7 to the P port of the flow direction control valve 30 via the shuttle valve 6.
The valve can be freely switched between the actuator 3 and the pilot check valve through an on-off valve 49 on the shuttle valve side of the throttle 48 provided in the connection line 8 between the shuttle valve 6 and the A port. Since the A port side of the throttle 48 is connected to the pilot chamber of the pilot check valve 5, the electromagnetic flow direction control valve operates the flow direction control valve 30 by the electromagnetic pilot valve γ. In this case, even if the fluid pump 1 is stopped, the load pressure of the actuator 3 is used when the actuator 3 is lowered to switch the flow direction control valve 30, and a large flow rate can be controlled. During the descent, even if the fluid pump 1 is stopped, the single-acting actuator 3 can be proportionally controlled in accordance with the opening degree of the variable orifice 40b, which has the effect of saving power.

[Brief explanation of the drawing]

FIG. 1 is an overall fluid circuit diagram showing an embodiment of the present invention, and FIG.
This figure and FIG. 3 are partially enlarged cross-sectional views of the previous one. C: Proportional control device, 1: Fluid pump, 4: Check valve sealing pressure reducing valve, 5:
・Pilot check valve, 7...Solenoid pressure reducing valve,
10...Pressure control valve, 11...Pressure compensator, 30...Flow rate directional control valve, 40...
...Variable flow rate adjustment orifice, 49...Opening/closing valve, 50...Centering spring.

Claims (1)

[Claims] 1 A neutral position in which the A port is opened to the T port, a first switching position in which the P port is opened to the B port and a variable orifice is formed between these ports, and a first switching position in which the B port is opened to the T port and a variable orifice is formed between these ports. a second forming a variable orifice;
A 4-point, 3-position type flow direction control valve 30 with a switching position is connected to the B port with a check valve material reducing pressure 4 such that the direction of the actuator is free flow, and the pressure reducing valve 4 and A pilot check valve 5 is interposed between the single acting actuator 3 and the electromagnetic pilot valve 7 via a shuttle valve 6 between a branch line 9 branching from the P port and a connection line 8 connecting to the A port. connected to the pressure port p, and the control port A' of the electromagnetic pilot valve 7;
B' is both pilot chambers 47 of the flow direction control valve 30.
a, 47b, respectively, and the shuttle valve 6 side of the throttle 48 interposed in the connection line 8 is connected to the on-off valve 49.
A branch line is connected to the flow path between the actuator 3 and the pilot check valve 5 via the flow path, and connects the A port side of the throttle 48 to the pilot chamber of the pilot check valve 5, while branching from the P port. 20
A branch control type pressure compensator 11 is interposed in the pressure compensator 11, and the spring side of the plunger 13 in the pressure compensator 11 is communicated with the B port when the flow direction control valve 30 is set to the first switching position; The single-acting actuator control device is further characterized in that the anti-spring side of the plunger 13 is communicated with the P port.