JPS5824642Y2 - Switching valve device that controls flow rate and back pressure - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a switching valve device for controlling flow rate and back pressure.

Switching valves that can adjust the flow rate are conventionally known as switching valves used in hydraulic actuator control devices, but when this type of switching valve is used in control devices such as winches, it is necessary to prevent dead weight from falling separately from the switching valve. It is necessary to install a counterbalance valve to prevent the winch from falling under its own weight, which makes the piping complicated and troublesome. (In this case, the pump flow rate is insufficient and an anti-cavitation circuit must be installed separately to prevent cavitation from occurring.The anti-cavitation circuit is designed to reduce the circuit resistance by increasing the diameter of the piping and shortening the length of the piping.) The configuration and layout of the control device is required!1l
There was the inconvenience of being taken by JR.

The purpose of the present invention is to eliminate such inconveniences, and includes an inflow port 5, an outflow port 7, and two actuator connection ports 8, 9. In the switching valve device, a switching spool 10 switches and controls a flow path connecting between the inflow port 5 and the switching spool 10. A connection passage 15 is provided to connect the return passage 12 to the return passage 12, and sliding in one direction narrows the passage area of the connection passage 15 and reduces the return flow. One channel opening/closing spool 16 is interposed which opens the channel area of the channel 12 and widens the connecting channel 15 and narrows the return channel 12 by sliding toward the other. The elastic force of the spring 18 to cause the sliding movement toward the other side, and the variable force formed in the return flow path 12 by the switching spool 10 to cause the sliding movement to the other direction, and which changes depending on the moving distance of the switching spool 10. The differential pressures generated before and after the constricted portions 13 and 14 of 13 and 14 are made to act oppositely to each other.

In the drawing, 1 is a hydraulic pump, 2 is an actuator such as a hydraulic cylinder, 3 is a flow port 5 connected to the pressure oil supply pipe 4 of the pump 1, an outflow port 7 connected to a tank 6, and the actuator 2. A switching valve device is shown that includes actuator connection ports 8 and 9 to be connected, and a spool 10 that selectively connects the inflow port 5 and the outflow port 7 to the actuator connection ports 8 and 9, and the spool 10
from the neutral position 20 shown in FIG.
When switched to the right switching position 22, the inflow port 5 communicates with the actuator connection port 8, and the outflow port 7 communicates with the actuator connection port 9. When switched to the right switching position 22, ports 5 and 9, ports 7 and 8 are connected. are connected to each other.

As shown in FIGS. 2 and 3, the switching spool 10 is provided with a notched constriction portion 13.14 to facilitate squeezing the fluid flowing out from the actuator connection port 8 or 9 into the return flow path 12, as shown in FIGS. 2 and 3. did.

When the flow path opening/closing spool 16 is slid to the left in the valve chamber 17 against the spring 18 on the left side thereof, the flow path area of the return flow path 12 is gradually closed and the flow rate flowing therethrough is throttled. At the same time, the flow area of the connecting flow path 15 is gradually increased from zero, but on the contrary, when the spool 16 is slid to the right by the spring 18, the area of the flow path 12 is increased and at the same time the flow path 1 is increased.
5 area decreases.

Thus, the connecting channel 15 is completely closed by sliding the spool 16 to the right, but the return channel 12 is not completely closed by the channel opening/closing spool 16.

The switching spool 10 moves from the neutral position 20 to the left/right switching position 2.
1°22, a pressure drop occurs before and after the throttle part 13 or 140, but the pressure in front of both the throttle parts 13°14 is transferred to the chamber at one end of the flow path opening/closing spool 16 via the pilot introduction passage 23. 24 and rear pressure is applied to the chamber 26 provided with the spring 18 via the pylon and the introduction passage 25, and the differential pressure before and after the constriction part 13.14 causes the passage opening/closing spool 16 to act on the spring 18 It is made to slide on the left side, that is, to widen the connecting channel 15 and to narrow the channel 12.

Therefore, the flow path opening/closing spool 16 is operated by this differential pressure and the spring 18.
If the flow rate flowing through the constriction part 13 or 14 is excessive and the pressure drop is too large, the flow path opening/closing spool 16 further narrows the return flow path 12 and the flow rate flowing therein is stopped. The constriction portion 13.14 slides to reduce the
When the flow rate flowing through is small and the pressure drop is small, spring 1
8, the spool 16 slides to the right 5 and returns to the return flow path 12.
The spool 16 comes to rest at a position corresponding to the pressure drop due to the flow rate.

The operation of the device of the present invention will be explained below.

When the switching spool 10 is located at the neutral position 20 and the discharge amount of the hydraulic pump 1 is zero, the flow path opening/closing spool 16 is pressed by the spring 18 to close the valve chamber 17 as shown in FIGS. 1 and 2. is in the right end position 30, and the connection passage 15 is closed. However, when the pump 1 is activated and fluid starts to be supplied from the inflow port 5, the pressure in the closed pressure oil supply passage 11 is increased by the switching spool 10. acts on the chamber 24 of the channel opening/closing spool 16 through the pilot introduction path 23.

Since the chamber 26 is equal to the tank pressure, the spool 16
slides to the left and reaches the position shown at 31 in FIG. 1, the connecting flow path 15 is opened and the flow rate of the pump 1 is unloaded.

Subsequently, as shown in the third diagram, even if the switching spool 10 is switched to position 21 in order to lift the load W with the hydraulic cylinder 2, the flow path opening/closing spool 16 initially unloads the flow rate of the pressure oil supply flow path 11. Although the hydraulic cylinder 2 does not operate because of this, there is also no flow from the connection port 9 to the return flow path 12, so the pressure acting on the chambers 24 and 26 at both ends of the flow path opening/closing spool 16 does not change much. Only the elastic force acts on the spool 16, and the spool 16 slides to the right.

According to this sliding, the connection flow path 15 is gradually narrowed, so that the pressure in the pressure oil supply flow path 11 increases and the hydraulic cylinder 2 is operated.

A return flow rate is generated in the return flow path 12 at the same time as the hydraulic cylinder 2 is operated, but when the flow rate increases and the pressure drop caused by the constriction part 14 of the switching spool 10 becomes thick, the flow path opening/closing spool 16 has a constriction part. The pushing force due to the differential pressure before and after the spring 14 exceeds the springing force of the spring 180, and the spool 16 is slid to the left at position 1 where the pushing force and the springing force are balanced.

When in this position, a flow rate corresponding to the opening area of the throttle part 14 stably flows, and the excess flow rate to the cylinder 2 is discharged to the tank via the connection flow path 15 and the outflow port 12, and the flow rate is controlled. be done.

Therefore, when the moving distance of the switching operation of the switching spool 10 is changed, the area of the constriction section 14 changes accordingly, and the flow path opening/closing spool 16 moves to a position corresponding to the differential pressure generated by the constriction section 14 for connection. The amount discharged into the tank 6 via the flow path 15 is controlled, in other words, the operating speed of the hydraulic cylinder 2 is controlled.

Switching spool 10 to operate cylinder 2 in the load direction
When switching from the neutral position 20 to the position 22, the flow path opening/closing spool 16 is initially at the position 30, so the load pressure of the cylinder 2 cannot be maintained and the load W of the cylinder 2 tries to fall at a high speed. Since the flow rate flowing from the connection port 8 to the return passage 12 through the constriction part 13 increases, the passage opening/closing spool 16 slides to the left due to the increased pressure difference before and after the constriction part 13, and the return passage 12 increases. As a result of throttling, the flow rate flowing through the spool 16 is reduced as described above, and the spool 16 comes to rest at a point where the differential pressure across the throttle portion 13 and the elastic force of the spring 18 are balanced.

As a result, the flow rate in the return flow path 12 becomes constant and the back pressure is controlled, and the hydraulic cylinder 2 descends at a constant speed according to the switching distance of the switching spool 10, and the constant speed can be arbitrarily set by moving the spool 10. It will be possible.

If the spool 10 is operated greatly, the opening degree of the crest 13 will increase, the return flow path 12 will be opened wide by the spool 16, and the cylinder 2 can be lowered at a speed close to the dead weight lowering speed of the load W, but in this case Even if the flow rate of the pump 1 to the cylinder 2 becomes insufficient, the flow rate from the tank return is replenished from the return flow path 12 to the pressure oil supply flow path 11 via the connection flow path 15, thereby preventing the occurrence of cavitation.

Incidentally, if the neutral position 20 of the switching spool 10 is constructed in a tandem center shape as shown in FIG. Since it is located at position 30, when the switching spool 10 is at the neutral position 20, the discharge amount of the pump 1 can be constantly unloaded.

In this way, according to the present invention, the flow rate flowing from the actuator connection port to the return flow path is throttled by the switching spool, and the differential pressure before and after the switching spool is applied to the flow path opening/closing spool interposed between the connection flow path and the return flow path. By sliding the flow path opening/closing spool to one side, the return flow path is gradually narrowed against the spring, and the connecting flow path is gradually opened, and when the flow path opening/closing spool is slid to the other side, the return flow path is opened against the spring. The flow rate and back pressure can be automatically controlled to any value by simply sliding the switching spool, regardless of whether the actuator operates in the forward or reverse direction. Since there is no need to provide a special flow control valve or back pressure control valve in the circuit, the entire circuit can be simplified, and the tank return flow is replenished from the return flow path to the pressure oil supply flow path via the connection flow path. There is an advantage that there is no need to install an anti-cavitation circuit whose distance in the tank 1 is limited, and the control device can be arranged relatively freely.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a diagram of the switching valve device, Fig. 2 is a cutaway side view, Fig. 3 is a cutaway side view of the operating state of Fig. FIG. 7 is a diagram of a switching valve device showing another embodiment. 3...Switching valve device, 5...Inflow port, 7...Outflow port, 8, 9...Actuator connection port, 1
0...Switching spool, 11...Pressure oil supply channel, 12
...Return channel, 13, 14... Comparison portion, 15... Connection channel, 16... Channel opening/closing spool, 18... Spring, 23° 25... Pilot introduction channel.

Claims (1)

[Scope of utility model registration request] A switching valve that includes an inflow port 5, an outflow port 7, and two actuator connection ports 8, 9, and controls switching of a flow path connecting the actuator connection ports 8, 9 and the inflow/outflow port 5.7 using a switching spool 10. In the device, a pressure oil supply passage 11 from the inflow port 5 to the switching spool 10 is provided.
and a return flow path 12 from the switching spool 10 to the outflow port 7.
Sliding in one direction narrows the flow area of the connecting flow path 15 and opens the flow area of the return flow path 12, and sliding in the other direction narrows the flow area of the connecting flow path 15. A single channel opening/closing spool 16 is interposed that widens the return channel 15 and narrows the return channel 12, and the elastic force of the spring 18 is applied to cause the channel opening/closing spool 16 to slide in the one direction, and in the other direction. The differential pressure generated before and after the variable constriction portion 13, 14 formed in the return flow path 12 by the switching spool 10 and varying according to the moving distance of the switching spool 10 is made to act against each other in order to cause the sliding movement. A switching valve device that controls flow rate and back pressure.