JPH09280400A - Pressure control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure control valve in which a pressure gradient and a valve sealing characteristic can be ensured. SOLUTION: This pressure control valve is comprised of a valve element 36, a valve seat 39 where the valve element 36 is seated, a control spring 41 for biasing the valve element 36 toward the valve seat 39. When pressure of control fluid acted on the valve element 36 exceeds a pressing force of the control spring 41, the valve is opened to cause control fluid to overflow. It is comprised of a stopper 41 to which the valve element 36 is contacted when the valve element 36 is arranged around the valve seat 39 and closes the valve seat 39 and a holding part 35 for holding the valve element 36 in a universal joint. The valve seat 39 is formed by synthetic resin and the valve seat 39 is formed with an extremity end 39A projecting out of as stopper 41 at the valve element 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control valve which is provided in a fluid flow path and controls the pressure of a control fluid flowing in the fluid flow path by causing an overflow, and more specifically, the pressure of the control fluid is high. The present invention relates to a pressure control valve effective.

[0002]

2. Description of the Related Art A pressure control valve is provided in a fluid flow path for controlling the pressure of a control fluid flowing in the fluid flow path. There are various types of such pressure control valves, but the overflow type pressure control valve is most commonly used so that the control fluid overflows and returns to the tank when the pressure of the control fluid exceeds a predetermined value. . The conventionally known overflow type pressure control valve is a pressure valve that controls the pressure of the control fluid to a relatively low pressure.
There are various problems in applying this as it is to a high pressure control valve, and it cannot be said to be sufficient.

This will be explained with reference to FIG. 16. In a conventional pressure control valve, an overflow passage 2 is formed inside a valve casing 1, and a valve body 3 and a valve seat 4 for opening and closing the overflow passage 2 are provided. Has been. The valve body 3 is made of steel, and the valve seat 4 is also made of steel. Valve body 3
Is pressed toward the valve seat 4 by the control spring 5.

The operation will be described. When the pressure of the control fluid acts on the valve body 3 via the inlet end 2A of the overflow passage 2 and the pressure of the control fluid becomes larger than the pressing force of the control spring 5, The valve body 3 is separated from the valve seat 4, and the control fluid exits the outlet end 2B via the overflow passage 2 and is returned to the tank (not shown).

When the pressure of the control fluid acting on the valve body 3 becomes smaller than the pressing force of the control spring 5, the valve body 3
Seats on the valve seat 4 to stop the control fluid flowing through the overflow passage 2.

[0006]

However, the above-mentioned FIG.
In the conventionally known pressure control valve as shown in (1), when it is used as a pressure control valve for high pressure, there are the following problems. That is, the valve body 3 and the valve seat 4 are both steel (SUS etc.)
Therefore, it is necessary to perform ultra-precision machining that provides ultra-precision accuracy (because of the need to provide surface roughness and flatness) to ensure the sealing performance when the valve body 3 is seated on the valve seat 4, In addition to high costs, there are restrictions on processing manufacturers.

Further, if one of the valve body 3 and the valve seat 4 is made of an elastic body such as synthetic resin, the deterioration of the sealing property is reduced, but the elastic body changes with time when a large load is applied for a long period of time. As a result, the sealing property is deteriorated. In order to reduce the load acting on this elastic body and suppress the change over time, if the valve body is supported by a pressure adjusting spring and the valve seat is also supported by a weak spring, it is possible to seal with a weak load. On the other hand, if such a structure is adopted, the structure becomes complicated and large in size, and the number of parts increases and the cost becomes high.

Furthermore, when a conventionally known pressure control valve is used as a valve for controlling the pressure of a very high control fluid of 10 megapascals (MPa) or more, the pressure gradient and the sealing performance of the valve over time are improved. It is necessary to suppress it within a predetermined required numerical value range, but with the structure of the valve body 3 and the valve seat 4 of the conventionally known metals or a combination of the metal and the elastic body, there is a problem that sufficient valve performance cannot be obtained. there were.

Therefore, an object of the present invention is to provide an overflow type valve structure which is effective as a valve for controlling the pressure of a high-pressure control fluid by improving the drawbacks of the above-mentioned conventionally known pressure control valve structure. It is in.

[0010]

The features of the present invention are as follows. That is, it is composed of a valve body, a valve seat on which the valve body is seated, and a control spring for urging the valve body toward the valve seat, and the pressure of the control fluid acting on the valve body pushes the control spring. In a pressure control valve of a type that opens when a pressure is exceeded to overflow control fluid, a stopper that is provided around the valve seat and that contacts the valve body when the valve body closes the valve seat; A pressure control characterized by comprising a holding portion for universally holding the body, the valve seat being formed of a synthetic resin, and the valve seat having a tip portion projecting to the valve body side with respect to the stopper. valve.

Another feature of the present invention is that it comprises a valve body, a valve seat on which the valve body is seated, and a control spring for urging the valve body toward the valve seat. A pressure control of a type that has a body for accommodating a valve seat, a control spring, etc. and a cover, and opens when the pressure of the control fluid acting on the valve body exceeds the pressing force of the control spring to overflow the control fluid. In the valve, an annular recess formed in the peripheral edge of the body or an annular recess formed in the peripheral edge of the cover, and a seal ring disposed in the recess, the peripheral edge of the body and the cover. It is located where the periphery is crimped with the seal ring sandwiched therebetween.

Still another feature of the present invention is that the valve body is held by a ball portion, and the ball portion is held by a spherical holding portion.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments of the present invention,
The various performances required for the pressure control valve that controls the pressure of the high-pressure control fluid and the necessary specifications that must be clarified during product development are explained.

The pressure control valve to which the present invention is applied is an overflow type pressure control valve for controlling the pressure of the control fluid flowing through the fluid flow path to a very high pressure of 10 MPa or more. In the case of such a pressure control valve that controls the pressure of the high-pressure control fluid, for example, as shown in FIGS. 1 and 2, it is necessary to secure the pressure gradient characteristic and the valve sealing characteristic within a predetermined range.

That is, the characteristic shown in FIG. 1 shows an example of the characteristic of the pressure gradient. Here, the vertical axis represents the pressure P (MPa) of the control fluid, and the horizontal axis represents the flow rate Q (l / h) of the control fluid per unit time. When the control pressure of the control fluid is 10 MPa and the flow rate of the control fluid is changed in the range of 40 liters to 100 liters, it is required that the variation of the control pressure be within the maximum variation range of 0.5 MPa. . Explaining this in more detail, when the control fluid is the fuel of a high-pressure injection type engine, the fuel flow rate is 40 liters in the range from the minimum engine load (when idling) to the maximum (full load or acceleration). To 100 liters,
When such a fuel flow rate is changed, the fluctuation of the adjustment pressure is 0.5
It is desired to suppress the pressure to the range of MPa.

The characteristic shown in FIG. 2 shows the sealing characteristic of the pressure control valve, and shows how much control fluid leaks out when the valve body is seated on the valve seat.
In the characteristics shown in the figure, assuming that the valve body is closed at 9 MPa, 6
It is desired that the pressure be maintained at 8.1 MPa even after 0 second (sec) has elapsed.

In the above description, the specific numerical values described above are examples, and the present invention is not limited to these numerical values.

From the above viewpoint, the characteristics of the pressure control valve shown in FIG. 1 in which the conventionally known valve body and valve seat are both made of metal are shown in FIGS. 3 and 4. The pressure gradient characteristic and the sealing characteristic as shown in FIG. That is,
With reference to FIG. 3, in the pressure gradient characteristic, when the flow rate fluctuates between 40 liters and 100 liters, the fluctuation rises by 1.2 MPa.

On the other hand, in the seal characteristic, the pressure becomes 0 MPa in a very short time as shown in FIG. Such deterioration of the sealing characteristics depends on the machining accuracy and mounting accuracy of the valve body and the valve seat, but it is interpreted as a problem before that because both the valve body and the valve seat are made of metal. Is appropriate.

From the above, it has been found that a desirable result cannot be obtained by a conventionally known combination of a valve body and a valve seat made of metals. Then, the structure of the valve body and the valve seat as shown in FIG. 5 was proposed. That is, the valve body 11 and the valve seat 1
2 are both SUS, and the structure of the valve body 11 is opened at the tip 11
A sleeve structure having A was adopted. That is, the inside of the cup-shaped sleeve 11B is filled with the closing body 11C, and the opening 11A is formed in the bottom wall 11D at the tip of the sleeve 11B. According to the structure of the valve body 11 shown in FIG. 5, the bottom wall 11
Since D is elastically deformable, as a result, the valve body 1
1 has elasticity, and the sealing property when seated on the valve seat 12 is improved.

When the characteristics of the pressure control valve having the structure shown in FIG. 5 are examined, the pressure gradient characteristics and sealing characteristics shown in FIGS. 6 and 7 are obtained. That is, in the pressure gradient characteristic shown in FIG. 6, the flow rate of the control fluid is from 40 liters to 100 liters.
When fluctuating between liters, the control pressure fluctuates by 1.2 MPa, which is the same as the conventionally known pressure control valve structure shown in FIG. However, in the sealing characteristics shown in FIG. 7, the pressure did not become 0 MPa even after 60 seconds passed after the valve body was closed, and although the sealing characteristics were improved, the characteristics were not yet sufficient. . Note that the pressure control valve having the structure shown in FIG. 5 is, depending on the control pressure and required performance,
Even with this method, the performance is such that it can be sufficiently commercialized.

From these results, in order to improve the sealing characteristics, it is necessary to thoroughly reconsider the material itself of the valve body or the valve seat as a problem before the machining accuracy and the mounting accuracy of the valve body and the valve seat. It turns out that the required specifications cannot be obtained without it.

On the other hand, regarding the pressure gradient, it has already been known that the characteristics can be improved by reducing the contact area between the valve body and the valve seat. For example, when the valve seat is made of synthetic resin, the contact area between the valve body and the valve seat increases due to the plastic deformation of the valve seat over time. Therefore, it is necessary to suppress an increase in the contact area due to the change over time of the valve element or the valve seat (for example, plastic deformation when used for a long time).

Therefore, in the most preferred embodiment of the present invention, a material having improved sealing characteristics was selected. Furthermore,
We proposed a structure that does not change with time such as plastic deformation of the material. In addition, the initial contact area was selected so as not to impair the sealing property.

The structure of a preferred embodiment of the present invention will be described below with reference to FIG. The peripheral edge of the cover 32 is caulked to the peripheral edge of the body 31 via a seal ring 33. A valve guide 34 is slidably provided in an internal space surrounded by the body 31 and the cover 32. The valve guide 34 includes a hemispherical ball holding portion 3
4A are formed. Three holding claws 35 are provided so as to project from the peripheral edge of the hemispherical ball holding portion 34A, and the holding claws 35 hold a ball 37 to which a valve body 36 is fixed in a universal shape. Therefore, the ball 37 comes into contact with the inner surface of the hemispherical ball holding portion 34A and is held by the elasticity of the three holding claws 35.
As shown in FIG. 9, the holding claw 35 has a punch 34C formed in the bottom wall 34B of the cup-shaped valve guide 34, and the claw piece formed by the punch 34C is bent to form the holding claw 35.

A control fluid passage 38 is provided in the body 31, and a ring-shaped valve seat 39 is provided on the outer periphery of the passage 38. The valve seat 39 has a thin end portion 39A and a thin end portion 39B for improving the seating of the valve element 36. A stopper 40 is provided on the outer periphery of the valve seat 39. The tip of the valve seat 39 is formed so as to project toward the valve body 36 side more than the tip of the stopper 40. A control spring 41 is provided in contact with the cover 32 and the valve guide 34, and the control spring 41 causes the valve element 36 to move to the valve seat 39.
And pressed by the stopper 40.

A part of the control fluid passage 38 is provided in the body 31.
Has a structure projecting in a pipe shape, and a seal ring 42 is provided on the outer periphery of the pipe portion 38A.
The pipe portion 38A is the inlet end of the control fluid. At the end of the cover 32, a pipe portion 38B protruding like a pipe is formed.
Is formed, and the pipe portion 38B serves as the outlet end of the control fluid passage 38.

An annular recess 31A is formed on the periphery of the body 31, and the seal ring 33 is formed in the recess 31A.
Is provided, thereby preventing the seal ring 33 from being displaced when caulking at the peripheral edge of the cover 32, thereby improving the sealing property.

Details of the contact portion between the valve element 36 and the valve seat 39 will be described with reference to FIGS. 10 and 11. FIG.
The state where the valve body 36 has just contacted the valve seat 39 is shown, and Δh in the figure shows the length by which the tip end 39A of the valve seat 39 projects from the stopper 40. In FIG. 10, t represents the wall thickness of the tip portion 39A of the valve seat 39. As described above, the wall thickness t has a great influence on the pressure gradient, and it is known that the thinner the wall thickness t, the smaller the pressure gradient.

In FIG. 11, the valve element 36 comes into contact with the stopper 40 to compress a part of the tip portion 39A of the valve seat 39, and
6 shows a state in which the valve seat 39 is closed. In this state, the deformation of the tip portion 39A is small, so that the amount of the time-dependent plastic deformation of the tip portion 39A of the valve seat 39 is reduced.

In the above structure, according to the present invention, a soft synthetic resin such as ethylene trifluoride (trade name Teflon), polyester (trade name Hytrel), polyamide (trade name Nylon 6) is used as the material of the valve seat 39. Adopted.
In the present invention, the above-mentioned synthetic resins are preferable examples, the present invention is not limited to the above-exemplified synthetic resins, and further the present invention excludes rubber materials such as synthetic rubber. is not. Further, in the present invention, as the material of the valve element 36, a hard synthetic resin can be used in addition to metal (SUS or the like).

Next, the contact area between the valve element 36 and the valve seat 39 of the present invention will be described. With reference to FIG. 12, the thickness (t) of the tip of the valve seat is set to three types of 0.2 mm, 0.3 mm, and 0.4 mm, and the length (Δh) of the tip of the valve seat protruding from the stopper is set. The initial length was 0.05 mm, the atmospheric conditions of the experiment were normal temperature (20 ° C) and high temperature (100 ° C),
The change in Δh dimension (shrinkage due to plastic deformation) over 200 hours was measured. In this case, two materials of ethylene trifluoride (trade name Teflon) and polyester (trade name Hytrel) were used as experimental materials for the valve seat.

As a result, as shown in FIG. 12, when the thickness t of the tip of the valve seat is 0.4 mm or 0.3 mm, it is 20
It was found that the protrusion length (Δh) of 0.01 mm or more was maintained even after the lapse of 0 hours, and a good result was obtained. On the other hand, it was found that when the thickness t of the tip of the valve seat was 0.2 mm, the protrusion length (Δh) was about 0.01 mm after 200 hours, particularly in a high temperature state. In the characteristic line of the figure, the solid line shows the case of ethylene trifluoride (trade name Teflon), and the broken line shows the case of polyester (trade name Hytrel).

Therefore, in consideration of the dimensional error in manufacturing the parts and the variation in the dimensions at the time of mounting, the wall thickness t of the tip portion is 0.3 m.
It has been concluded that it is preferable to employ a valve seat of m or 0.4 mm. It should be noted that the present invention is not limited to the above numerical values, and the numerical value range can be appropriately changed depending on the design specifications and the atmospheric conditions used.

Next, the operation of the pressure control valve of the present invention will be described with reference to FIGS. In the steady state, the valve body 36 closes the valve seat 39 by the pressing force of the control spring 41. In this state, as shown in FIG. 11, the tip portion 39A of the valve seat 39 is deformed and is in contact with the valve body 36. Now, the pressure of the control fluid acting on the passage 38 is increased, and the pressure acts on the control spring 41 acting on the valve body 36.
When the pressing force of is exceeded, the valve element 36 leaves the valve seat 39. Then, the control fluid is returned to a tank or the like (not shown) via the passage 38. When the pressure of the control fluid decreases due to the overflow, the pressing force of the control spring 41 causes the valve element 36 to close the valve seat 39. By repeating the above operation, the control fluid is maintained at a predetermined pressure.

As shown in FIG. 11, according to the structure of the present invention, the movement of the valve body 36 is restricted by the contact of the valve body 36 with the stopper 41, and as a result, the valve seat 3
The deformation of the tip portion 39A of 9 is suppressed to a slight amount.
Therefore, the plastic deformation of the tip portion 39A of the valve seat 39 is reduced, and the sealability is sufficiently secured even after long-term use.

Further, since the area of the front end portion 39A of the valve seat 39 which contacts the valve body 36 is small, a desired pressure gradient can be obtained.

When the pressure gradient and valve sealability of the pressure control valve of the present invention constructed as described above were measured, the results shown in FIG. 13 were obtained. That is,
The pressure gradient and the sealing property of the valve in the initial stage could be kept within the set values. Further, even in the pressure gradient after using 20,000 times, it could be maintained within the set value range in both the high temperature state and the normal temperature state. Further, the sealing property of the valve after being used 20,000 times was not within the range of the initial set value, but was within the range in which it could be sufficiently used as a product.

The configuration described above is one embodiment of the present invention, and the present invention is not limited to the above-mentioned embodiments, and the following structures can be adopted, for example. For example, as shown in FIG. 14, an inclined surface 36A may be formed at the lower edge of the valve body 36 to guide the flow of the control fluid ejected from the valve seat 39 to reduce the pressure loss. . Thus, by making the structure of the valve body 36 into the shape of an inverted truncated cone, the disc-shaped valve body 36 shown in FIG.
Compared with, the characteristic of the pressure gradient is improved.

Furthermore, as shown in FIG.
The holding structure of the seal ring 33 held by the peripheral edge of the cover 1 and the cover 32 is not held in the recess 31A formed in the peripheral edge of the body 31 as shown in FIG.
An annular recess 32A may be formed on the peripheral edge of the cover 32 side to hold it.

[0041]

According to the present invention constructed and operated as described above, the following effects can be obtained. Since the plastic deformation of the tip portion of the valve seat is reduced, the desired pressure gradient can be obtained for a long period of time, and at the same time, the desired sealing property can be secured.

By appropriately selecting the synthetic resin, the pressure control valve most effective for the pressure gradient and the sealing property can be provided.

Further, by appropriately selecting the wall thickness of the tip portion of the valve seat, it becomes possible to provide a pressure control valve which is more effective in the pressure gradient and the sealing property.

When an annular recess is formed on the periphery of the body or cover, the seal ring does not shift during the caulking work, so that the caulking work is easy and the sealing property of the caulking portion is ensured.

[Brief description of drawings]

FIG. 1 is a characteristic diagram for explaining a pressure gradient.

FIG. 2 is a characteristic diagram for explaining the sealability of a valve.

FIG. 3 is a characteristic diagram for explaining a pressure gradient of the conventionally known pressure control valve shown in FIG.

FIG. 4 is a characteristic diagram for explaining the valve sealability of the conventionally known pressure control valve shown in FIG.

FIG. 5 is a partial cross-sectional view showing an example of a structure in which the valve body has elasticity.

FIG. 6 is a characteristic diagram for explaining a pressure gradient of the structure shown in FIG.

FIG. 7 is a characteristic diagram for explaining the sealability of the valve having the structure shown in FIG.

FIG. 8 is a sectional view showing a pressure control valve according to an embodiment of the present invention.

FIG. 9 is a plan view for explaining the ball holding portion of FIG.

FIG. 10 is an enlarged cross-sectional view of a valve body and a valve seat.

FIG. 11 is an enlarged cross-sectional view showing a state in which the valve body closes the valve seat.

FIG. 12 is a diagram showing a result of measuring shrinkage of the tip portion of the valve seat when the wall thickness of the tip portion is changed.

FIG. 13 is a diagram showing the results of measuring the pressure gradient and the sealing property of the valve according to the structure of the present invention at the initial stage and after 20,000 times of use.

FIG. 14 is a partial cross-sectional view showing another embodiment of the structure of the valve body according to the present invention.

FIG. 15 is a partial cross-sectional view showing another embodiment of the caulking portion structure according to the present invention.

FIG. 16 is a cross-sectional view showing an example of a conventionally known pressure control valve.

[Explanation of symbols]

 11 valve body 11A opening 11B sleeve 11C closing body 11D bottom wall 12 valve seat 31 body 31A recess 32 cover 33 seal ring 34 valve guide 34A ball holding portion 34B bottom wall 34C punching 35 holding claw 36 valve body 36A inclined surface 37 ball 38 Passage 38A Pipe part 38B Pipe part 39 Valve seat 39A Tip part 39B Lower end side 40 Stopper 41 Control spring

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area F16K 1/34 F16K 1/34 E

Claims (4)

[Claims] 1. A valve body, a valve seat on which the valve body is seated, and a control spring for urging the valve body toward the valve seat. The pressure of a control fluid acting on the valve body is controlled. In a pressure control valve of a type that opens when a pressure force of a spring is exceeded to overflow control fluid, a stopper that is provided around the valve seat and that contacts the valve body when the valve body closes the valve seat. A holding portion for universally holding the valve body, the valve seat being formed of a synthetic resin, and the valve seat having a tip portion projecting to the valve body side with respect to the stopper. Pressure control valve. 2. A valve body, a valve seat on which the valve body is seated, and a control spring for urging the valve body toward the valve seat, and the valve body, the valve seat, the control spring, etc. are accommodated. A pressure control valve having a body and a cover that open when the pressure of the control fluid acting on the valve body exceeds the pressing force of the control spring to overflow the control fluid. A pressure control valve, comprising: an annular recess; and a seal ring disposed in the recess, wherein the peripheral edge of the body and the peripheral edge of the cover are caulked with the seal ring sandwiched therebetween. 3. A valve body, a valve seat on which the valve body is seated, and a control spring for urging the valve body toward the valve seat. The valve body, the valve seat, the control spring, etc. are accommodated. A pressure control valve having a body and a cover that open when the pressure of the control fluid acting on the valve body exceeds the pressing force of the control spring to overflow the control fluid. A pressure control valve comprising an annular recess and a seal ring disposed in the recess, and the peripheral edge of the cover and the peripheral edge of the body are caulked with the seal ring sandwiched therebetween. 4. The pressure according to any one of claims 1 to 3, wherein the valve body is held by a ball portion, and the ball portion is held by a spherical holding portion. Control valve.