JPH0645111Y2 - Pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a combined pressure control valve having a pilot poppet and a check poppet.

[Conventional technology]

An example of this type of conventional valve will be described with reference to the pressure control valve (Japanese Patent Publication No. 62-29665) shown in FIG. The check (valve) poppet 52 slidably accommodated in the casing 51 is provided with a relief poppet 53 that alternately connects and disconnects the pressure supply port 54 and the relief port 55, and a valve body 63 behind the relief poppet 53. The pilot poppet 62, which is biased by the pilot spring 60, contacts the valve seat 61 of the valve body 63, the piston poppet 56 is slidably inserted into the relief poppet 53, and the collar portion 57 has the relief poppet 53 and the valve. It is pressed against the check poppet 52 via the relief poppet 53 by a spring 59 provided in the back pressure chamber 58 formed between the body 63 and the body 63.

The pilot poppet 62 opens when the pressure in the back pressure chamber 58 exceeds the set pressure of the pilot spring 60, and reduces the pressure in the back pressure chamber 58. As a result, the piston poppet 56 moves against the spring 59 due to the differential pressure across the piston poppet 56, and part of the pressure oil in the pressure supply port 54 flows into the back pressure chamber 58 through the through hole 64 of the piston poppet 56. . Piston poppet on the move
The through hole 64 of 56 is the projection 65 at the tip of the pilot poppet 62.
When closed with, the pressure oil flowing into the back pressure chamber 58 is only the pressure oil from the annular gap between the relief poppet 53 and the piston poppet 56, and the pressure in the back pressure chamber 58 further decreases, and the relief poppet 53 Opens and enters a steady relief state.

[Problems to be solved by the device]

The pilot poppet 62 is the piston poppet as described above.
Since the protruding portion 65 that closes the through hole 64 of 56 is provided so as to project, the diameter is larger than that of a normal pilot poppet. A composite type pressure control valve (Japanese Patent Laid-Open No. 57-15160) shown in FIG. 4 which is a partial improvement of the conventional valve shown in FIG. 3 is a pilot poppet 76 in a pilot housing 71 provided in a check poppet 52.
The piston poppet 72 that moves by opening the valve is received by the tip end of the cylindrical stopper 74 of the pilot housing 71, and the through hole 73 of the piston poppet 72 is inserted into the stopper 74 and abuts the tip of the pilot poppet 76. By closing the guide poppet 75, the pressure in the back pressure chamber 78 is further reduced, the relief poppet 53 is opened, and the steady relief state is established. In this case also, the pilot poppet 76 is larger than the guide poppet 75 that closes the through hole 73, and has a larger diameter than a normal pilot poppet.

As described above, in this type of composite pressure control valve, not only the size of the check poppet is increased, but also the pilot poppet is increased in size as described above, resulting in a further increase in size.

The present invention has been made in view of the above points, and it is an object of the present invention to reduce the size of a composite type pressure control valve of this type and to achieve stability of relief pressure control.

[Means for Solving the Problems]

To achieve this object, in the pressure control valve of the present invention, a relief plunger that is inserted into a check poppet to open and close communication between the pressure supply port and the relief port, and is slidably inserted into the relief plunger. Includes a plunger piston that abuts the inner end of the relief plunger with a spring and connects the pressure supply port to the internal back pressure chamber, and a pilot poppet that opens when the pressure exceeds a predetermined pressure and connects the back pressure chamber to the low pressure side relief port. In the pressure control valve, when the initial relief operation is started on the outer peripheral surface of the plunger piston that does not collide with the pilot poppet, a groove that enters the relief plunger is formed, and an oil passage that always communicates this groove with the back pressure chamber is formed. It is characterized by being formed.

[Action]

When the pressure in the back pressure chamber 10 becomes equal to or higher than a predetermined pressure, the pilot poppet 18 opens to reduce the pressure in the back pressure chamber 10. As a result, the pilot oil from the pressure supply port 8 flows out to the low pressure side relief port through the groove portion 14 of the plunger piston 7, the oil passages 15 and 15 ', the back pressure chamber 10 and the pilot poppet 18, and the plunger piston 7 is located before and after that. The movement starts against the spring 11 due to the differential pressure generated at. At the same time, the relief plunger 6 moves due to the differential pressure before and after the relief plunger 6, and the relief operation is started in this state. Then, the groove portion 14 immediately enters the relief plunger 6, and the pilot oil flowing into the back pressure chamber 10 is only the pilot oil from the annular gap between the relief plunger 6 and the plunger piston 7, so that the amount of the pilot oil is reduced. However, a steady relief operation state is set. In this relief pressure control, the time during which the pilot oil flows in from the oil passages 15 and 15 'is shortened to some extent to prevent a rapid pressure increase and prevent a large pressure change in an excessive state. Furthermore, since the pilot poppet 18 does not collide with the plunger piston 7, the relief plunger 6
Can be prevented from opening excessively and the stability of relief pressure can be improved. That is, since the pilot poppet 18 further opens when it collides with the plunger piston 7, the pressure in the back pressure chamber 10 drops significantly, the relief plunger 6 opens excessively, and the pressure in the pressure supply port 8 rapidly increases. Although it will drop significantly and it will take time to stabilize, this can be avoided in the present invention.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a valve body screwed to a casing 2, 3 is a check poppet which is attached to one end side of the valve body 1 so as to be able to move forward and backward and abuts against a valve seat 5 by a spring 4, and a relief plunger 6 Is inserted so that it can move back and forth freely. The relief plunger 6 opens and closes the communication between the pressure supply port 8 and the relief port 9 through the through holes 3a and 3b of the check poppet 3, and the plunger piston 7 is inserted in the retractable manner. The plunger piston 7 is a spring 11 compressed in a back pressure chamber 10 into which the check poppet 3 is inserted so as to move back and forth.
As a result, the collar portion 12 is brought into contact with the concave portion 13 of the relief plunger 6 so that the relief plunger 6 is passed through the through hole 3a of the check poppet 3.
Groove 14 is formed on the outer peripheral surface of the tip end portion protruding to the through hole 3a while contacting the inner end on the side, and the slit-shaped oil passage 15 is formed by forming the groove portion 14 and the back pressure chamber 10 in the outer peripheral surface longitudinal direction. , 15 are in communication. At the position of the back pressure chamber 10 facing the plunger piston, there is a through hole 26 in which the tip of the pilot poppet 18 pressed against the valve seat 17 by the pilot spring 16 is located. The pilot chamber 19 communicates with the low pressure relief port through the through hole 20 and the like, and the pilot spring 16 is adjusted by the adjusting spring 21 screwed into the valve body 1.

In the state before starting the relief operation (the state shown in the figure), the distance l ₁ between the end surface 22 of the relief plunger 6 on the pressure supply port side and the side end of the groove portion 14 of the plunger piston 7 on the pressure supply port 8 side is the same as that of the plunger piston 7. Back pressure chamber facing this
10 It is smaller than the distance from the wall.

Now, when the pressure in the pressure supply port 8 exceeds the initial set load of the pilot spring 16, the pilot poppet 18 lifts and the pressure in the back pressure chamber 10 decreases. This causes the pilot oil in the pressure supply port 8 to
14, the oil passages 15, 15, the back pressure chamber 10, the pilot chamber 19, and the through hole 20 to flow out to the low-pressure relief port, and the plunger piston 7 lifts against the spring 11 due to the differential pressure across the same. At the same time, the relief plunger 6 is lifted by the differential pressure before and after the relief plunger 6, and the relief operation is started in this state.
When the plunger piston 7 is lifted by l ₁ , the only pilot oil that flows into the back pressure chamber 10 is the pilot oil from the annular gap 24 between the plunger piston 7 and the relief plunger 6. The operation at this time will be described in detail below.

The pressure P of the pressure supply port 8 is the load W _{1 of the} pilot spring 16.
When the pressure set in is reached, the pilot poppet 18 lifts at (π / 4) d ₁ ² × P ₁ = W ₁ and the pilot oil flows through the oil passage between the plunger piston 7 and the relief plunger 6. It flows from 15, 15 to the back pressure chamber 10, the pilot chamber 19, and the through hole 20.

The pilot oil amount q ₁ at this time is when the load of the spring 11 is w _1. And (π / 4) d ₂ ² (P ₁ -P _B1 ) = W ₁ (1) holds, and the plunger piston 7 lifts against the spring 11. Then, when lifted by l ₁ , this time the annular gap 24 between the plunger piston 7 and the relief plunger 6
From the back pressure chamber 10, the pilot oil amount q ₂ flows. That is, And (π / 4) d ₂ ² (P ₂ -P _B2 ) = W ₁ (2) holds.

Here, d ₁ : diameter of pressure receiving portion of pilot poppet 18 d ₂ : diameter of pressure receiving portion of plunger piston 7 C: flow coefficient S ₁ : total area of oil passages 15 and 15 S ₂ : area of annular gap 24 g: Acceleration of gravity P ₁ , P ₂ : pressure of pressure supply poppet 8 P _B1 , P _B2 : pressure of back pressure chamber 10 ρ: specific weight of oil S ₁ > S ₂ from equations (1) and (2), therefore q ₁ > q ₂ . Therefore, the lift amount of the pilot poppet 18 is set in
It becomes larger when passing 5 and P ₁ > P ₂ .

If the length of l ₁ is set appropriately, the pressure change from P _{1 to} P ₂ is performed in a short time, so that appropriate pressure control can be performed.

In addition, the passage area of the lifted plunger piston 7 is the oil passage.
It changes from 15 to the annular gap 24 but it is continuous,
The pressure fluctuation rate is smaller than the discontinuous one.
In addition, since the lift amount of the pilot poppet becomes large in an excessive state, and in the steady relief state it becomes an annular gap throttle,
It is possible to prevent harmful dust from entering the pilot section. or,
Since the pilot poppet 18 is not pushed open by the plunger piston 7, the pressure in the back pressure chamber 10 does not drop excessively.

When the pressure of the pressure supply port 8 is higher than the pressure of the relief port 9, the check poppet 3 is in pressure contact with the valve seat 5, but is lower than the relief port pressure due to cavitation on the pressure supply port 8 side. Then, the valve is opened against the spring 4.

In another embodiment shown in FIG. 2, an oil passage 15 'for communicating the groove 14 and the back pressure chamber 10 is formed on the central axis of the plunger piston 7, and the other construction is shown in FIG. Is the same as.

[Effect of device]

Since the present invention is configured as described above, it has the following effects.

When the initial relief operation is started on the outer peripheral surface of the plunger piston that does not condense with the pilot poppet, a groove that enters the relief plunger is formed and an oil passage that constantly connects this groove to the back pressure chamber is provided. The control can be stabilized, the pilot poppet can be downsized, and the composite pressure control valve of this type can be made compact.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of another embodiment, and FIGS. 3 and 4 are longitudinal sectional views of a main part of a conventional valve. 3 ... Check poppet, 6 ... Relief plunger,
7 ... Plunger piston, 8 ... Pressure supply port, 9
…… Relief port, 10 …… Back pressure chamber, 11 …… Spring, 14…
… Grooves, 15,15 ′ …… Oil passages, 18 …… Pilot poppets.

Claims (1)

[Scope of utility model registration request] 1. A relief plunger (6) inserted into a check poppet (3) to open and close communication between a pressure supply port (8) and a relief port (9), and slidably on the relief plunger (6). A plunger piston (7) which is inserted and contacts the inner end of the relief plunger (6) with a spring (11) and communicates the pressure supply port (8) with the internal back pressure chamber (10); In the pressure control valve including the pilot poppet (18) that opens to connect the back pressure chamber (10) to the low pressure side relief port, the outer peripheral surface of the plunger piston (7) is arranged so as not to collide with the pilot poppet (18). When the initial relief operation is started, the groove portion (14) that enters the relief plunger (6) is formed, and the oil passages (15) and (15 ') that constantly communicate this groove portion (14) with the back pressure chamber (10). The pressure control valve, characterized in that the formed.