JPH09105473A - Relief valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform regulation so that when temperature is low, a relief pressure is increased and when temperature is high, the relief pressure is decreased. SOLUTION: A valve seat 19 having an opening part 20 communicated with an inlet 13 is slidably arranged inside the inlet 13 of a valve casing 12 having an inlet 13 and an outlet 14 for fluid. A valve body 22 to open and close the opening part 20 is arranged on the opposite side to the inlet 13 of the valve seat 19. A relief valve has a valve seat spring 17 made of a shape memory alloy to press the valve seat 19 to the inlet 13 side; and a valve spring 23 to press the valve body 19 in a direction in which the opening part 20 is closed. A pressure is received in such a state that at least a part of the surface on the inlet 13 side of the valve seat 19 is exposed to a space communicated with the inlet 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve in which a relief pressure is increased when the temperature of a fluid is below a predetermined value and is reduced when the temperature of the fluid exceeds a predetermined value.

[0002]

2. Description of the Related Art Various types of valves that operate according to temperature have been proposed by utilizing the characteristics of shape memory alloys. 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 element 55 is arranged so as to be able to come into contact with and separate from 1.
The intermediate portion of the valve body 55 has a prismatic shape, and fluid can pass between the outer periphery thereof and the inner periphery of the valve casing 51. Then, the partition wall 58 having the plurality of holes 59 is connected to the outlet 5
The shape memory alloy spring 57 is arranged between the partition wall 58 and the rear end of the valve body 55. Also, the valve head 62
And a bias spring 56 between the valve seat 61 and
This is what constitutes a valve.

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

However, the above-mentioned valve merely opens and closes the valve in accordance with the temperature of the fluid by utilizing the shape restoring force of the shape memory alloy, and the action of closing the valve when the temperature of the fluid is high. It is what makes up.

By the way, 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, and therefore the oil pressure tends to be high even with the same amount of oil supplied, and the oil temperature is high. If this happens, the viscosity of the oil will decrease, and the oil pressure will tend to decrease even with the same amount of oil supplied.Therefore, if the oil pressure is controlled at a constant level, a large amount of oil will be relieved when the oil temperature is low, and There was a possibility that the oil supply would be insufficient. Therefore, it has been desired to develop a relief valve that can be adjusted so that the relief pressure becomes high when the oil temperature is low and becomes low when the oil temperature is high.

[0006]

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

When attempting to develop a relief valve as described above, it is conceivable to reverse the arrangement of the shape memory alloy spring and the bias spring of the valve of FIG. 5 to form a valve as shown in FIG. To be

That is, in the valve shown in FIG. 6, a fluid inlet 7 is provided on one end surface of a valve casing 71 which is cylindrical as a whole.
2, a fluid outlet 73 is formed on 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 thereof 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 body 75, and a shape memory alloy spring 77 is interposed between the flange 76 and the end surface of the valve casing 71 on the inlet 72 side. A bias spring 78 is interposed between the plate 74 and the other end face of the plate 74.

The biasing force H ₂ of the bias spring 78 is set so as to always be larger 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 urge. The biasing force H ₁ of the shape memory alloy spring 77 is small below the transformation point of the shape memory alloy, and increases above the transformation point due to the shape restoring force of the shape memory alloy.

[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 On the other hand, the load H of the shape memory alloy spring 77
₁ changes at the transformation point T as a boundary. As a result, at a position 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
Above, the output load becomes the difference indicated by B in the figure. This makes it possible to change the relief pressure with the transformation point T as a boundary.

However, even the above valve has the following problems. That is, since the output load that presses the valve body 75 against the inner surface of the inlet 72 is calculated by H ₂ −H ₁ , the shape memory alloy spring 77 and the bias spring 7 are obtained.
The elastic force of No. 8 must be adjusted strictly, and in particular, the elastic force of the shape memory alloy spring 77 tends to vary depending on the shape memory processing condition, so that it is difficult to obtain an accurate relief pressure. there were.

Therefore, an object of the present invention is a relief valve which can be adjusted so that the relief pressure becomes high when the temperature is low and becomes low when the temperature is high, and the load accuracy of the shape memory alloy spring is so high. Even if it does not have, it is to provide what can obtain an exact relief pressure.

[0013]

In order to achieve the above object, a relief valve of the present invention comprises a valve casing having a fluid inlet and an outlet, and a valve casing inside the fluid inlet of the valve casing. And a valve seat slidably arranged with an opening communicating with the fluid inlet, and arranged on the opposite side of the valve seat from 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 of closing the 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, the valve seat spring made of a shape memory alloy has an extremely small elastic force at a temperature below its transformation point. For this reason, when the fluid flows in from the fluid inlet and a fluid pressure equal to or lower than the relief pressure but equal to or higher than a predetermined value is applied to the valve seat, both the valve seat spring and the valve spring are compressed, and the valve seat moves toward the valve casing. Moves away from the fluid inlet. Therefore, the relief pressure in this state becomes a pressure required to further compress 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,
The elastic force of the valve seat spring is remarkably increased by the shape restoring force of the shape memory alloy, and the valve seat is moved and pressed toward the fluid inlet side. As a result, the valve spring expands. Therefore, the relief pressure in this state is a pressure required to compress the stretched valve spring, that is, a low pressure.

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

Further, the valve seat spring made of a shape memory alloy has a low elastic force below the transformation point so that the valve seat can be moved to the side opposite to the fluid inlet, and above the transformation point. In the above, the output load may be adjusted so that the valve seat has a high elastic force so that it 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 shape memory alloy valve seat spring is not so required.

[0018]

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

That is, the relief valve 11 has a valve casing 12 having a cylindrical shape as a whole, and has a fluid inlet 13 formed on one end face thereof, a fluid outlet 14 formed on the side wall thereof, and the other side thereof. The end surface 15 of 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 movably disposed in the enlarged diameter portion 16 so as to be slidably in contact with the inner wall thereof, and the inlet 13 is provided at the center thereof.
An opening 20 having an inner diameter smaller than that of the opening 20 is formed.
The lower edge portion is formed in a tapered shape. The valve seat 19 has its upper end moving position 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.

In the intermediate portion 17, the valve seat 19 and the reduced diameter portion 1 are provided.
The valve seat spring 21 made of a shape memory alloy is interposed between the valve seat 19 and the valve 8, and the valve seat 19 is biased toward the end surface of the valve casing 12 on the inlet 13 side. The shape memory alloy valve seat spring 21 is memorized in an elongated shape, and when the temperature exceeds the transformation point, the biasing force is increased by the shape restoring force. The transformation point is determined according to the application of the relief valve 11.

A ball valve 22 is provided in the intermediate portion 17,
The valve seat 19 is arranged in contact with the lower edge of the opening 20. Then, the ball valve 22 and the valve casing 12
A valve spring 23 is interposed between the valve spring 23 and the lower end surface 15 of the ball valve 22.
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, as shown in FIG.
As shown in FIG. 2, the valve seat 19 has a valve seat spring 21 and a valve spring 2
Under the urging force of No. 3, the valve casing 12 is pressed against the end surface of the valve casing 12 on the inlet 13 side.

When a fluid having a temperature below the transformation point of the shape memory alloy valve seat spring 21 flows in through the inlet 13 and a fluid pressure below the relief pressure but above a predetermined value is applied to the valve seat 19, the valve seat 19 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 is separated from the end surface of the valve casing 12 on the inlet 13 side, its pressure receiving area is S2 to S3.
, The valve seat 19 moves until it abuts on the intermediate portion 17 of the valve casing 12, and the state shown in FIG.

As a result, the valve spring 23 is compressed to the length indicated by L ₁ , and the relief pressure required to push down the ball valve 22 is increased. In the figure, S1 is a ball valve 2
The area S1 is a pressure receiving area applied to No. 2, and since the area S1 does not always change, the relief pressure is determined only by the elastic force of the valve spring 23.

Next, when the temperature of the fluid rises and the temperature of the shape memory alloy valve seat spring 21 exceeds its transformation point, the elastic force of the valve seat spring 21 remarkably increases due to the shape restoring force of the shape memory alloy. As the valve seat 19 is raised, the valve seat 19 is pressed against the end surface 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 is reduced.

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

When the load on the valve seat spring 21 is F1 and the load on the valve spring 23 is F2, F1 + F2 is smaller than the fluid pressure below the relief pressure applied to S1 + S2 at a temperature below the transformation point. F1 + F2 should be set to F1 + F2 at a temperature exceeding the transformation point.
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 to satisfy the above condition, and its production 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 when the temperature is low, and (b) is a cross-sectional view when the temperature is high. Note that the substantially same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

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

FIG. 3 shows the shape of the valve seat 33. In the figure, (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. Four struts 36 hang down on the lower surface of the pedestal 34, and the upper half peripheral surface of the valve body 37 is slidably contacted with the inside of these struts 36.

FIG. 4 shows the shape of the valve element 37. In FIG. 4, (a) is a plan view, (b) is a front sectional view, and (c).
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 that opens at two locations in the upper portion of the peripheral wall, extends downward through the central portion of the cylindrical body, and opens at the lower end surface.

Referring again to FIG. 2, the shape memory alloy valve seat spring 21 is interposed between the lower surface of the pedestal 34 of the valve seat 33 and the upper end of the sleeve 32, and the valve spring 23.
Is interposed between the lower surface of the flange 38 of the valve element 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 element 37 is pressed by the valve spring 23 until the flange 38 comes into contact with the column 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 below the transformation point of the shape memory alloy valve seat spring 21 flows in from the inlet 13 and a fluid pressure below the relief pressure but above a predetermined value is applied to the valve seat 33, the valve seat spring 21
Since the elastic force of the valve seat spring is extremely small, both the valve seat spring 21 and the valve spring 23 are compressed, and the valve seat 33 moves to the side opposite to the inlet 13 until the valve seat spring 21 comes into close contact.
The state shown in FIG. In this state, since the valve spring 23 is compressed, the relief pressure becomes high.

Next, when the temperature of the fluid rises and the temperature of the valve seat spring 21 made of shape memory alloy exceeds its transformation point, the elastic force of the valve seat spring 21 remarkably increases due to the shape restoring force of the shape memory alloy. As the valve seat 33 is raised, 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 expanded, the relief pressure becomes low.

In any of the above states, when a fluid pressure higher than the relief pressure is applied, the valve element 37 is pushed down, and the fluid passes through the opening 35 of the valve seat 33 and the column 36.
Flow into the flow passage 39 of the valve body 37 through the gap of
Will pass through the inner space of the valve casing 12 from the lower end opening thereof and will flow out from the outlet 14.

[0041]

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

The wire diameter of the shape memory alloy valve seat spring 21 is 0.7 mm, the coil diameter is 5.3 mm, and the free length is 9.
The length in the state of 5 mm, (a) was 4.6 mm, the length in the state of (b) was 6.3 mm, and the transformation point thereof 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 (a) 13.4 m
In the state of m and (b), the length was 15.5 mm and the spring constant was 0.05.

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

[0045]

As described above, according to the present invention,
(EN) A relief valve that utilizes the characteristics of shape memory alloys to increase the relief pressure when the temperature of a fluid is below a predetermined value and to reduce the relief pressure when the temperature of the fluid exceeds a predetermined value. You can 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 purposes such as hydraulic control of a torque converter and relief valve of a water heater.

[Brief description of the drawings]

1A and 1B are views showing an embodiment of a relief valve of the present invention, in which FIG. 1A is a sectional view in a low temperature state, and FIG. 1B is a sectional view in a high temperature state.

2A and 2B are views 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.

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

4 is a diagram showing a valve body of the relief valve of FIG.
(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 an example other than the present invention, which is a relief valve in which the relief pressure is changed by temperature.

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

[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 body 21 Valve seat spring 23 Valve spring

Claims (1)

[Claims] 1. A valve casing having a fluid inlet and an outlet, and a valve provided inside the fluid inlet of the valve casing, slidably disposed in the valve casing, and having an opening communicating with the fluid inlet. A seat, a valve element arranged on the opposite side of the valve seat from the fluid inlet, and movable to open and close the opening of the valve seat, and the valve seat pressed 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 of closing the opening of the valve seat, the space of the valve seat of the valve seat in a space communicating with the fluid inlet of the valve casing. A relief valve, wherein at least a part of the surface on the fluid inlet side is exposed.