JPH0468507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a directional control valve that sends return oil from an actuator to a supply side as required.

(Conventional directional control valve) The conventional directional control valve shown in FIGS. 1 and 2 has actuator ports 2 and 3 formed in the valve body 1, and one actuator port 2 is connected to the bottom side chamber 5 of the cylinder 4. At the same time, the other actuator port 3 is connected to the rod side chamber 6.

The valve body 1 thus constructed is provided with a spool 7, and when the spool 7 is in the neutral position as shown in FIG. The ether ports 2 and 3 are in a relationship in which communication with the supply flow path 11 and the tank flow path 12 is cut off.

This supply channel 11 communicates with a parallel feeder 13 via a load check valve 14.

Further, a control body 16 is installed on one side of the spool 7, that is, on the right side in the drawing.

FIG. 2 shows an enlarged view of the configuration of the control body 16 portion.

That is, this control body 16 has a large diameter part 17 at its outer end facing into the pressure chamber 18, and by the action of a spring 19 provided in this pressure chamber 18, the poppet part 20 is normally formed on the spool 7. It is brought into pressure contact with the valve seat 21. Also poppet part 2
The protrusion 22 protruding from 0 faces into the communication chamber ₂₃ , and the pressure receiving area a2 on the pressure chamber 18 side is made larger than the pressure receiving area _a1 of the poppet portion 20 on the communicating chamber 23 side. An oil passage hole 24 is formed in the control body 16, and the pressure chamber 18 and the communication chamber 23 are always in communication through the oil passage hole 24.

Further, the communication chamber 23 is connected to the other actuator port 3 through a through hole 25 formed in the spool 7.
or the supply channel 11.

That is, in the illustrated state where the spool 7 is in the neutral position, the through hole 25 communicates with the other actuator port 3, while when the spool 7 is switched to the left in the drawing, it communicates with the supply flow path 11. ing.

Furthermore, when the poppet portion 20 of the control body 16 is in pressure contact with the valve seat 21, a switching hole 26 and a tank flow path port 27 are formed at opposing positions between the poppet portion 20 and the large diameter portion 17. ing. The switching hole 26 and the tank flow path port 27 are always in communication via a flow path 28 formed between the control body 16 and the spool 7, and are connected to the other actuator port 3 and the tank flow path 12. holds the following relational position.

That is, in the neutral position shown, the switching hole 26
communicates with the tank flow path 12, while the tank flow path port 27 crosses the opening of the tank flow path 12 and is completely closed. Then, when the spool 7 is switched to the left in the drawing, the switching hole 26 communicates with the other actuator port 3, and the tank flow path port 27 communicates with the tank flow path 12.

When the spool 7 is switched to either the left or right side, communication between the pump ports 8 and 9 and the tank port 10 is cut off, and either one of the actuators is connected via the first or second annular grooves 29 and 30. The port communicates with the supply channel 11 .

If the spool 7 is now moved to the right in the drawing, the supply channel 11 and the other actuator port 3 communicate with each other via the second annular groove 30, and the actuator port 2 communicates with the other actuator port 3 through the third annular groove 31.
It communicates with the tank flow path 12 via.

The pressure oil from the pump therefore flows into the rod side chamber 6, the oil in the bottom side chamber 5 returns to the tank and the cylinder 4 moves the rod in the opposite direction to the arrow 15.

Next, when the spool 7 is switched to the left in the drawing, one actuator port 2 communicates with the supply channel 11 via the first annular groove 29, but the other actuator port 3 and the tank channel 12 is communicated with as follows.

That is, since the switching hole 26 communicates with the other actuator port 3 and the tank flow path port 27 communicates with the tank flow path 12, the other actuator port 3 communicates with the switching hole 26, the flow path 28, and the tank flow path 12. It communicates with the tank flow path 12 via the tank flow path port 27 .

Moreover, at this time, the supply pressure in the supply flow path 11 is
The supply pressure flows into the bottom side chamber 5 of the cylinder and also flows into the communication chamber 23 and the pressure chamber 18 because the through hole 25 communicates with the supply flow path 11 .

As described above, pressure oil is supplied to the bottom side chamber 5 of the cylinder, and the rod side chamber 6 communicates with the tank flow path 12, so that the rod of the cylinder 4 moves in the direction of the arrow 15.

The directional control valve thus constructed is used, for example, to control the arm cylinder of a power shovel. When the bucket of the power shovel is lowered in the air, a counter load acts on the cylinder 4 in the direction of arrow 15.

Therefore, the bottom side chamber 5 becomes a negative pressure, and the communication chamber 23 and the pressure chamber 18 communicating with this bottom side chamber 5
also becomes negative pressure. When the pressure inside the pressure chamber 18 becomes negative, the control body 16 moves against the spring 19 due to the pressure inside the flow passage 28, and the valve seat 21 is opened.

When the valve seat 21 opens, the return oil from the rod side chamber 6 flows into the supply channel 11 through the communication hole 23 and the communication hole 25, and joins with the oil from the pump. That is, the returned oil from the rod side chamber 6 is supplied to the bottom side chamber 5 to compensate for the shortage and prevent cavitation.

On the other hand, when the power shovel is excavating, the pressure inside the bottom chamber 5 becomes high.
This high pressure is also introduced into the communication chamber 23. The high pressure introduced into the communication chamber 23 in this manner is also introduced into the pressure chamber 18 through the oil passage hole 24 . As a result, the communication chamber 23 and the pressure chamber 18 have the same pressure, but as described above, since the pressure receiving area a ₂ is larger than the pressure receiving area a ₁ , the control body 16 maintains the valve seat 21 in a closed state.

Therefore, in this case, the return oil from the rod side chamber 6 does not flow to the supply channel 11, but all flows to the tank channel 12.

The disadvantages of the conventional directional control valve as described above are:
When the valve seat 21 opens, a fluid force is generated in the seat portion, which causes the oil regeneration flow rate to become unstable.

In other words, since fluid force is generated in the valve seat 21, the control body 16 moves, and the opening area of the valve seat 21 is not constant.
There was a drawback that the regeneration flow rate became unstable.

(Objective of the Present Invention) An object of the present invention is to provide a directional control valve in which the regeneration flow rate is always constant even if a fluid force is generated.

(Embodiments of the present invention) This invention improves the structure of one side of the spool, and the rest is the same as the conventional one, so only the essential parts are shown in the drawings for each embodiment below.

In the first embodiment shown in FIG. 3, a valve hole 32 is formed at one end of the spool 7, and a control body 33 is installed inside the valve hole 32.

When the control body 33 is installed in the valve hole 32 as described above, a spring chamber 34 is formed between the outer end of the control body 33 and the valve hole, and a spring 35 provided in the spring chamber 34 is formed. A spring force of 1 is applied to the control body 33.

The control body, which receives the spring force of the spring 35 as described above, usually has its inner end pressed against a step 36 formed in the valve hole 32 so as to face the communication chamber 37 .

The control body 33 has an oil hole 38 formed along its axis, and one end of the oil hole 38, that is, the end opposite to the spring chamber 34, is opened, and the inner peripheral edge of the opening is opened. The oil passage hole 38 is connected to the spring chamber 34 through a communication hole 40 formed on the opposite side of the seat portion 39 .

Further, an annular recess 41 is formed on the outer periphery of the control body 33, and a protrusion 42 is formed at the outer end of the annular recess, that is, at the end on the spring chamber 34 side.

Furthermore, the annular recess 41 connects to the oil passage hole 38 through a connection hole 43 formed in the control body 33.
is in constant communication with

The control body 33 has an annular recess 41
always corresponds to the switching hole 26 formed in the spool 7, while the raised part 42 corresponds to the tank flow path port 27 when the control body 33 is in pressure contact with the step part 36. .

An on-off valve 44 made of a ball is brought into pressure contact with the seat portion 39 of the control body 33 constructed as described above.

The on-off valve 44 is connected from the oil passage hole 38 to the communication chamber 37.
It only allows flow to the control unit 3.
3 is in pressure contact with the step portion 36, the spring 45 causes the seat portion 39 to come into pressure contact with the seat portion 39.

Although the communication chamber 37, which is blocked from flowing to the oil passage hole 38 as described above, is formed with the passage hole 46,
The through hole 46 is closed when the spool 7 is in the neutral position, and communicates with the supply channel 11 when the spool 7 is moved leftward in the drawing.

However, when the spool 7 is moved to the left in FIG. 1, that is, to the state shown in FIG. flows into.

Further, the return oil in the rod side chamber 6 returns to the tank 48 through the actuator port 3, the switching hole 26, the annular recess 41, and the tank flow path port 27.

However, if a counter load in the direction of arrow 15 is applied to the arm cylinder 4 at this time, the following will occur.

That is, when a counter load is applied as described above, the pressure inside the communication chamber 37 also decreases, so that the control body 33 is always maintained in a state in which it is in pressure contact with the stepped portion 36 by the action of the spring 35.

When the control body 33 is in pressure contact with the stepped portion 36, the raised portion 42 of the control body corresponds to the tank flow path port 27, as described above. Since the raised portion 42 corresponds to the tank flow path port 27, a large pressure drop occurs when passing there.

Therefore, the pressure inside the oil passage hole 38 becomes higher, so the on-off valve 44 moves against the spring 45 and opens the seat portion 39.

When the seat portion 39 is opened, the return oil from the actuator port 3 flows into the bottom side chamber 5 via the through hole 46 and the supply flow path 11, and as described above, the tank flow path port 27 is connected to the raised portion. 42, the opening area of the tank flow path port 27 becomes substantially smaller and the flow rate returning to the tank is restricted.

Therefore, the return oil from the rod side chamber 6 is efficiently recycled to the supply channel 11.

In this case, the on-off valve 44 opens due to the difference between the pressure inside the oil passage hole 38 and the spring force of the spring 45.
After that, from actuator port 3 to supply flow path 1
The on-off valve 44 maintains a stable opening degree due to the dynamic pressure caused by the flow to 1. Further, even if fluid force is generated in the seat portion 39, the control portion body 33 contacts the step portion 36 due to the pressure difference between the spring chamber 34 and the communication chamber 37.
Stabilize. In other words, the regeneration flow rate is always constant.

When the above-mentioned counter load is not acting on the cylinder 4, the pressure in the communication chamber 37 becomes the supply pressure to the cylinder, so the control body 33 moves against the spring 35.

If the control body moves as described above, the raised portion 4
2 and the tank flow path port 27, and the opening area of the tank flow path port 27 is substantially increased, resistance to the oil returned from the rod side chamber 6 is reduced, and pressure loss is also reduced.

Next, when the spool 7 is moved to the right in the drawing, the supply channel 11 communicates with the actuator port 3 communicating with the rod side chamber 6 via the second annular groove 30, and the actuator port 2 communicating with the bottom side chamber 5. It communicates with the tank flow path 12.

Oil from pump 47 therefore flows from actuator port 3 into rod side chamber 6 and moves the piston of cylinder 4 in the direction opposite to arrow 15.

At this time, oil from the pump flows into the communication chamber 37, but the pressure acts on the on-off valve 44, so that the seat portion 39 remains closed.

In the second embodiment shown in FIG. 4, the spring chamber 34 is communicated with the tank flow path port 27, and the communication between the spring chamber 34 and the oil passage hole 38 is cut off.The other configuration is the same as that of the first embodiment. Similar to the example.

That is, the spring chamber 34 communicates with the tank flow path port 27 via the oil hole 49.

Also in this embodiment, since the communication chamber 37 becomes negative pressure during the regeneration, the control body 33 comes into contact with the stepped portion 36 and maintains a stable state.

The third embodiment shown in FIG.
A sliding portion 51 having a slightly smaller diameter is provided at the tip of the stopper 50 at 4, and this sliding portion 51 is inserted into a hole 52 formed in the control body.

A chamber 53 formed by the hole 52 and the sliding portion 51 is configured to constantly communicate with the tank flow path port 27. That is, the chamber 53 is
It communicates with an oil hole 56 that is always in communication with the tank flow path port 27 via an oil passage 54 and an annular groove 55 .

The other configurations are the same as those of the first embodiment.

Therefore, in this third embodiment, the control body 33 is connected to the spring chamber 34 side and the communication chamber 37 side.
The pressure-receiving area will be different. That is, the pressure receiving area on the communication chamber side is relatively larger by the amount of the sliding portion 51 on the spring chamber side.

Also in this case, the on-off valve 44 is connected to the oil passage hole 38.
The on-off valve 44 opens due to the difference between the internal pressure and the spring force of the spring 45, and thereafter maintains a stable opening degree due to the dynamic pressure caused by the flow from the actuator port 3 to the supply channel 11. Further, even if fluid force is generated in the seat portion 39, the control portion body 33
4 and the communication chamber 37 makes it come into contact with the step 36, so it is stabilized. In other words, the regeneration flow rate is always constant.

(Structure and effect of the present invention) The structure of the present invention forms a supply flow path communicating with the pump and a tank flow path communicating with the tank, and a first tubular shape formed on the spool according to the switching position of the spool. In a directional control valve that communicates a supply flow path with either one of the actuator ports and a tank flow path with either of the other actuator ports via a groove or a second annular groove, one side of the spool is provided. A valve hole is formed, a control body is slidably housed in the valve hole, and an annular recess is formed around the outside of the control body, and this annular recess always corresponds to a switching hole formed in the spool. On the other hand, the oil passage hole formed in the control body is always in communication with the annular recess, and the inside of the oil passage hole is open to the communication chamber side, and the oil passage is made to flow through the seat portion at the open end. An on-off valve is provided that allows flow only from the hole to the communication chamber, and the annular recess is always in communication with the switching hole formed in the spool and the tank flow path port, and the communication chamber is always in communication with the communication hole. On the other hand, only when the spool is moved in a predetermined direction, the through hole opens to the supply flow path, the switching hole communicates with one actuator port, and the tank flow path port opens to the tank flow path. It is distinctive in that it is connected to the road.

With the above configuration, the regeneration flow rate is determined only by the opening area of the on-off valve. The opening area is determined regardless of the amount of movement of the control body. That is, since the opening area described above is determined only by the pressure within the oil passage hole, even if the control unit becomes unstable due to fluid force, it will not affect the regeneration flow rate.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional directional control valve, with Figure 1 being a sectional view, Figure 2 being an enlarged sectional view of its main parts, and Figure 3 showing a first embodiment of the present invention. FIG. 4 is an enlarged sectional view of essential parts of the second embodiment, and FIG. 5 is an enlarged sectional view of essential parts of the third embodiment. 2, 3... Actuator port, 7... Spool, 11... Supply channel, 26... Switching hole, 27
... Tank flow path port, 29 ... First annular groove, 3
0... Second annular groove, 32... Valve hole, 33... Control body, 37... Communication chamber, 38... Oil passage hole, 39...
...Seat portion, 41...Annular recess, 44...Opening/closing valve, 46...Through hole, 47...Pump, 48...Tank.

Claims (1)

[Claims] 1. A supply channel communicating with the pump and a tank channel communicating with the tank are formed, and depending on the switching position of the spool, the supply channel is connected via a first annular groove or a second annular groove formed in the spool. is communicated with one of the actuator ports, and
In a directional control valve that communicates a tank flow path with one of the other actuator ports, a valve hole is formed on one side of the spool, a control body is slidably housed in the valve hole, and the control body is An annular recess is formed around the outer periphery of the spool, and the annular recess is always in a relationship corresponding to the switching hole formed in the spool, and the oil passage hole formed in the control body is always in communication with the annular recess. The oil passage hole has its inside open to the communication chamber side, and an on-off valve is provided on the seat portion at the open end to allow only flow from the oil passage hole to the communication chamber, and the annular recess is formed in the spool. The switching hole is always in communication with the tank flow path port, and the communication chamber is always in communication with the passage hole, but only when the spool is moved in a predetermined direction, the communication chamber is connected to the supply flow path port. opened to
A directional control valve in which a switching hole communicates with one actuator port, and a tank flow path port communicates with a tank flow path.