JP3207731B2 - Relief valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve which increases the relief pressure when the temperature of a fluid is lower than a predetermined value, and decreases the relief pressure when the temperature of the fluid exceeds a predetermined value.

[0002]

2. Description of the Related Art There have been proposed various valves which operate according to temperature by utilizing characteristics of a shape memory alloy. For example, Japanese Patent Publication No. 2-41679 discloses a temperature responsive valve as shown in FIG. That is, a fluid inlet 52 is formed at one end of the valve casing 51, a fluid outlet 53 is formed at the other end, and a valve seat 61 is provided adjacent to the inlet 52.
The valve head 62 of the valve body 55 is disposed so as to be able to approach / separate from 1.
The intermediate portion of the valve body 55 has a prismatic shape so that fluid can pass between the outer periphery and the inner periphery of the valve casing 51. Then, a partition 58 having a plurality of holes 59 is connected to the outlet 5.
3 and a shape memory alloy spring 57 is disposed between the partition wall 58 and the rear end of the valve body 55. In addition, the valve head 62
And a bias spring 56 disposed between the valve seat 61 and
A valve is configured.

In this valve, at a predetermined temperature or lower, the biasing force of the bias spring 56 exceeds the biasing force of the shape memory alloy spring 57, and the valve body 55 is slid rearward, and the valve seat 61 is moved.
Is opened to allow the fluid to flow from the inlet 52 to the outlet 53. When the temperature exceeds a predetermined temperature, the urging force of the shape memory alloy spring 57 overcomes the urging force of the bias spring 56 due to the shape restoring force of the shape memory alloy, causing the valve body 55 to slide forward, and the valve seat 61 The opening is closed by a valve head 62 to prevent fluid from flowing in from the inlet 52.

[0004] However, the above-mentioned valve merely uses the shape restoring force of the shape memory alloy to open and close the valve in accordance with the temperature of the fluid. In addition, the valve closes when the temperature of the fluid is high. It is what constitutes.

[0005] For example, in a relief valve attached to a cooling oil supply pipe of an engine, when the oil temperature is low, the viscosity of the oil is high. When this happens, the oil viscosity tends to decrease and the oil pressure tends to decrease even with the same amount of supplied oil.Therefore, if controlled at a constant relief pressure, a large amount of oil will be relieved when the oil temperature is low, and the There was a possibility that the oil supply was insufficient. Therefore, there has been a demand for the development of a relief valve that can be adjusted so that the relief pressure increases when the oil temperature is low and the relief pressure decreases when the oil temperature is high.

[0006]

However, at present, it has not been attempted yet to develop a relief valve having the above-mentioned action using a shape memory alloy spring.

In order to develop the above-described relief valve, it is conceivable to construct the valve shown in FIG. 6 by reversing the arrangement of the shape memory alloy spring and the bias spring of the valve shown in FIG. Can be

That is, the valve shown in FIG. 6 has a fluid inlet 7 at one end face of a valve casing 71 which is generally cylindrical.
2, a fluid outlet 73 is formed in the side wall, the other end face is closed by a plate 74, and a valve body 75 having a spherical tip is disposed inside so as to be movable in the axial direction. A flange 76 is formed on the outer periphery of the rear end of the valve element 75, and a shape memory alloy spring 77 is interposed between the flange 76 and an end face on the inlet 72 side of the valve casing 71, and the flange 76 and the valve casing 71 are formed. The bias spring 78 is interposed between the other end face of the plate 74 and the plate 74.

The biasing force H ₂ of the bias spring 78 is set to be always greater than the biasing force H ₁ of the shape memory alloy spring 77, and the valve body 75 is applied to the inner surface of the inlet 72 by the force of H ₂ −H ₁ . I try to energize. Biasing force H ₁ of the shape memory alloy spring 77 is small in the following transformation point of the shape memory alloy, are made larger by the shape restoring force of the shape memory alloy exceeds the transformation point.

[0010] Figure 7, the load of H ₂ bias spring 78, shows the relationship of the load H ₁ and the temperature of the shape memory alloy spring 77, the load of H ₂ bias spring 78 is a constant change temperature However, the load H of the shape memory alloy spring 77
₁ changes around the transformation point T. As a result, at a point lower than the transformation point T, the output load pressing the valve body 75 against the inner surface of the inlet 72 becomes a difference indicated by A in the figure, and the transformation point T
Where the load exceeds the above, the output load becomes the difference indicated by B in the figure. This makes it possible to change the relief pressure at the transformation point T.

However, the valve described above has the following problems. That is, since the output load for pressing the valve body 75 against the inner surface of the inlet 72 is determined by H ₂ −H ₁ , the shape memory alloy spring 77 and the bias spring 7
8, the elastic force of the shape memory alloy spring 77 in particular tends to vary depending on the shape memory processing conditions, so that it is difficult to obtain an accurate relief pressure. there were.

Accordingly, an object of the present invention is to provide a relief valve which can be adjusted so that the relief pressure increases when the temperature is low and decreases when the temperature is high, and the load accuracy of the shape memory alloy spring is so high. It is an object of the present invention to provide a device capable of obtaining an accurate relief pressure even if it is not provided.

[0013]

In order to achieve the above object, a relief valve according to the present invention comprises a valve casing having a fluid inlet and an outlet, and a valve casing having a fluid inlet formed inside the valve casing. And a valve seat having an opening communicating with the fluid inlet, and a valve seat disposed on a side of the valve seat opposite to the fluid inlet, and movable to open and close the opening of the valve seat. A valve body, a valve seat spring made of a shape memory alloy that presses the valve seat toward the fluid inlet side of the valve casing, and a valve spring that presses the valve body in a direction to close an opening of the valve seat. At least a part of a surface of the valve seat on the fluid inlet side is exposed in a space communicating with the fluid inlet of the valve casing.

According to the relief valve of the present invention, a valve seat spring made of a shape memory alloy has an extremely small elastic force at a temperature lower than its transformation point. For this reason, when the fluid flows in from the fluid inlet and a fluid pressure equal to or less than the relief pressure but equal to or greater than the predetermined value is applied to the valve seat, both the valve seat spring and the valve spring are compressed, and the valve seat is closed by the valve casing. It moves to the opposite side of the fluid inlet. Therefore, the relief pressure in this state is a pressure necessary for further compressing the compressed valve spring, that is, a high pressure.

Next, when the temperature of the fluid rises and the shape memory valve seat spring is heated until it exceeds its transformation point,
Due to the shape restoring force of the shape memory alloy, the elastic force of the valve seat spring is significantly increased, and the valve seat is moved to the fluid inlet side and pressed. As a result, the valve spring extends. Therefore, the relief pressure in this state is a pressure required to compress the elongated valve spring, that is, a low pressure.

As described above, when the temperature of the fluid is low, the relief pressure can be increased, and when the temperature of the fluid is high, the relief pressure can be decreased.

Further, the valve seat spring made of a shape memory alloy has a low elastic force so that the valve seat can be moved to the side opposite to the fluid inlet below its transformation point, and above its transformation point. In, the output load may be adjusted so as to have a high elastic force so that the valve seat can be pressed against the fluid inlet side, and the relief pressure is determined only by the elastic force of the valve spring, The load accuracy of the valve seat spring made of shape memory alloy is not so required.

[0018]

FIG. 1 shows an embodiment of a relief valve according to the present invention. In the figure, (a) is a cross-sectional view in a low temperature state, and (b) is a cross-sectional view in a high temperature state.

That is, the relief valve 11 has a valve casing 12 having a cylindrical shape as a whole, a fluid inlet 13 is formed on one end face, a fluid outlet 14 is formed on a side wall, and the other side. Is closed. Inside the valve casing 12, an enlarged diameter portion 16, an intermediate portion 17, and a reduced diameter portion 18 are sequentially formed from the inlet 13 side.

A valve seat 19 is slidably contacted with the inner wall of the enlarged diameter portion 16 and has an inlet 13 at the center thereof.
An opening 20 having a smaller inner diameter than the opening 20 is formed.
Is formed in a tapered shape. The upper end movement position of the valve seat 19 is regulated by the end surface of the valve casing 12,
The lower end movement position is regulated by the intermediate portion 17 of the valve casing 12.

The intermediate portion 17 includes the valve seat 19 and the reduced diameter portion 1.
8, a valve seat spring 21 made of a shape memory alloy is interposed, and urges the valve seat 19 toward the end face of the valve casing 12 on the inlet 13 side. The shape memory alloy valve seat spring 21 is memorized in an expanded shape, and when it exceeds the transformation point, the urging force is increased by the shape restoring force. The transformation point is determined according to the use of the relief valve 11.

In the intermediate portion 17, a ball valve 22 is provided.
The valve seat 19 is arranged in contact with the lower edge of the opening 20. The ball valve 22 and the valve casing 12
A valve spring 23 is interposed between the lower end surface 15 and the ball valve 22 so that the ball valve 22 is connected to the valve seat 19.
Is pressed against the lower edge of the opening 20.

Next, the operation of the relief valve 11 will be described. First, when the fluid does not flow, FIG.
As shown in FIG. 2, the valve seat 19 includes the valve seat spring 21 and the valve spring 2.
3 and is pressed against the end face of the valve casing 12 on the inlet 13 side.

When a fluid having a temperature equal to or lower than the transformation point of the shape memory alloy valve seat spring 21 flows into the inlet 13 and a fluid pressure equal to or lower than the relief pressure but exceeding a predetermined value is applied to the valve seat 19, the valve is closed. Since the elastic force of the seat spring 21 is extremely small,
Both the valve seat spring 21 and the valve spring 23 are compressed, and the valve seat 19 moves to the side opposite to the inlet 13.

Once the valve seat 19 separates from the end face of the valve casing 12 on the inlet 13 side, the pressure receiving area changes from S2 to S3.
And the valve seat 19 moves until it abuts on the intermediate portion 17 of the valve casing 12, and the state shown in FIG.

[0026] As a result, the valve spring 23 is compressed to a length represented by L _1, the required relief pressure to push down the ball valve 22 becomes higher. In the figure, S1 is the ball valve 2
The relief pressure is determined only by the elastic force of the valve spring 23 because the area S1 does not always change.

Next, when the temperature of the fluid rises and the temperature of the valve spring 21 made of a shape memory alloy exceeds its transformation point, the elastic force of the valve spring 21 remarkably increases due to the shape restoring force of the shape memory alloy. As a result, the valve seat 19 is pressed against the end face of the valve casing 12 on the inlet 13 side, and the state shown in FIG.

As a result, the valve spring 23 is extended to the length indicated by L ₂ , and the relief pressure required to push down the ball valve 22 decreases.

Therefore, when the temperature of the fluid is low, the relief pressure can be increased, and when the temperature of the fluid is high, the relief pressure can be decreased.

When the load on the valve seat spring 21 is F1 and the load on the valve spring 23 is F2, at a temperature below the transformation point, F1 + F2 is set to be smaller than the fluid pressure below the relief pressure applied to S1 + S2. , F1 may be set, and at a temperature exceeding the transformation point, F1 + F2
However, F1 may be set so as to be higher than the fluid pressure equal to or lower than the relief pressure applied to S1 + S3.

Therefore, the load accuracy of the valve seat spring 21 is:
Below the transformation point, it is small enough to satisfy the above conditions,
If the temperature exceeds the transformation point, it may be adjusted so as to be sufficiently large so as to satisfy the above conditions, and the production thereof is relatively easy.

Next, another embodiment of the relief valve according to the present invention will be described with reference to FIG. In the figure, (a) is a cross-sectional view in a low temperature state, and (b) is a cross-sectional view in a high temperature state. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The relief valve 31 also has a cylindrical valve casing 12 as a whole. A fluid inlet 13 is formed on one end face of the valve casing 12, an outlet 14 is formed on a side wall, and the other end face is formed. 15 is closed. The inside of the valve casing 12 expands in diameter behind the inlet 13 and forms a straight cylindrical space as it is. The sleeve 32 is inserted into the lower half of the closed end surface 15 side to reduce the diameter. An opening 32 a communicating with the outlet 14 is provided in the sleeve 32.
Are formed. The major difference between this embodiment and the third embodiment lies in the shapes of the valve seat 33 and the valve element 37.

FIG. 3 shows the shape of the valve seat 33, wherein (a) is a plan view, (b) is a front view, and (c) is a bottom view. The valve seat 33 has a disk-shaped pedestal 34, and an opening 35 is provided at the center thereof. On the lower surface of the pedestal 34, four columns 36 are suspended, and the upper half peripheral surface of the valve body 37 is in sliding contact with the inside of these columns 36.

4A and 4B show the shape of the valve element 37. FIG. 4A is a plan view, FIG. 4B is a front sectional view, and FIG.
Is a bottom view. The valve body 37 has a columnar shape as a whole, and a flange 38 is formed slightly below the middle thereof. In addition, a flow path 39 is formed which opens at two places in the upper part of the peripheral wall, extends downward through the center of the columnar main body, and opens at the lower end surface.

Referring again to FIG. 2, the valve seat spring 21 made of a shape memory alloy is interposed between the lower surface of the pedestal 34 of the valve seat 33 and the upper end of the sleeve 32.
Is interposed between the lower surface of the flange 38 of the valve body 37 and the lower end surface 15 of the valve casing 12.

In the relief valve 31, when the fluid pressure is equal to or lower than the relief pressure, the valve body 37 is pressed by the valve spring 23 until the flange 38 comes into contact with the support 36 of the valve seat 33.

The operation of the relief valve 31 is substantially the same as that of the relief valve 11 of the above embodiment. That is, when a fluid having a temperature equal to or lower than the transformation point of the valve seat spring 21 made of a shape memory alloy flows into the inlet 13 and a fluid pressure lower than the relief pressure but exceeding a predetermined value is applied to the valve seat 33, the valve seat spring 21
Is remarkably small, both the valve seat spring 21 and the valve spring 23 are compressed, and the valve seat 33 moves until the valve seat spring 21 comes into close contact with the side opposite to the inlet 13, and FIG.
The state shown in FIG. In this state, since the valve spring 23 is compressed, the relief pressure increases.

Next, when the temperature of the fluid rises and the temperature of the valve spring 21 made of a shape memory alloy exceeds its transformation point, the elastic force of the valve spring 21 remarkably increases due to the shape restoring force of the shape memory alloy. As a result, the valve seat 33 is pressed against the reduced diameter portion of the valve casing 12 on the inlet 13 side, and the state shown in FIG. In this state, since the valve spring 23 is extended, the relief pressure is reduced.

When a fluid pressure higher than the relief pressure is applied in any of the above states, the valve body 37 is pushed down, and the fluid passes through the opening 35 of the valve seat 33 and passes through the support 36.
Flows into the flow path 39 of the valve element 37 through the gap of
Through the inner space of the valve casing 12 from the lower end opening of the valve casing 12 and flows out from the outlet 14.

[0041]

In the relief valve 31 shown in FIG. 2, the inner diameter of the inlet 13 of the valve casing 12 is 4 mm, the inner diameter of the enlarged portion below the inlet 13 is 65 mm, and the inner diameter of the opening 35 of the valve seat 33 is 3 mm. .

The wire diameter of the valve seat spring 21 made of a shape memory alloy is 0.7 mm, the coil diameter is 5.3 mm, and the free length is 9.
5 mm, the length in the state of (a) was 4.6 mm, the length in the state of (b) was 6.3 mm, and the transformation point was 60 ° C.

Further, the material of the valve spring 23 is SUS304.
WPB, wire diameter 0.4 mm, coil diameter 3.6 mm, free length 21 mm, length in the state of (a) 13.4 m
m, the length in the state of (b) was 15.5 mm, and the spring constant was 0.05.

Water was introduced as a fluid into the thus obtained relief valve 31, and the relief pressure at a temperature below the transformation point was measured. As a result, it was 5 kgf / cm ² . The relief pressure measured at a temperature exceeding the above transformation point was 3.5 kgf / cm ² .

[0045]

As described above, according to the present invention,
Provided is a relief valve that utilizes the characteristics of a shape memory alloy to increase the relief pressure when the temperature of a fluid is equal to or lower than a predetermined value, and to decrease the relief pressure when the temperature of the fluid exceeds a predetermined value. Can be. Further, even if the load accuracy of the shape memory alloy is not so high, an accurate relief pressure can be obtained, and the design and manufacturing are easy.

Since the relief valve of the present invention has the above characteristics, for example, a hydraulic control valve for engine cooling oil,
It can be used for various applications such as hydraulic control of a torque converter and a relief valve of a water heater.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a relief valve according to the present invention, in which (a) is a sectional view in a low temperature state, and (b) is a sectional view in a high temperature state.

FIGS. 2A and 2B are diagrams showing another embodiment of the relief valve of the present invention, wherein FIG. 2A is a sectional view in a low temperature state, and FIG. 2B is a sectional view in a high temperature state.

FIG. 3 is a view showing a valve seat of the relief valve of FIG. 2;
(A) is a plan view, (b) is a front view, and (c) is a bottom view.

FIG. 4 is a view showing a valve body of the relief valve of FIG. 2;
(A) is a plan view, (b) is a front sectional view, and (c) is a bottom view.

FIG. 5 is a sectional view showing an example of a conventional temperature responsive valve.

FIG. 6 is a cross-sectional view showing a relief valve in which a relief pressure changes according to temperature, and showing an example other than the present invention.

FIG. 7 is a table showing temperature-load characteristics of a shape memory alloy spring and a bias spring of the relief valve of FIG. 6;

[Explanation of symbols]

 11, 31 Relief valve 12 Valve casing 13 Fluid inlet 14 Fluid outlet 19, 33 Valve seat 22 Ball valve 37 Valve element 21 Valve seat spring 23 Valve spring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 17/00-17/168 F16K 31/64-31/70

Claims (1)

(57) [Claims] 1. A valve having a valve casing having an inlet and an outlet for fluid, and an opening inside the fluid inlet of the valve casing slidably disposed in the valve casing and communicating with the fluid inlet. A seat, a valve body disposed on a side of the valve seat opposite to the fluid inlet, the valve body being movable to open and close the opening of the valve seat, and pressing the valve seat against the fluid inlet side of the valve casing. A valve seat spring made of a shape memory alloy, and a valve spring that presses the valve element in a direction to close an opening of the valve seat, wherein a space communicating with the fluid inlet of the valve casing has the valve seat. A relief valve, wherein at least a part of the surface on the fluid inlet side is exposed.