JPH047403Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a ball valve that is attached to a fluid piping of a fluid system to open and close a fluid passage to control the flow.

In a ball valve, a valve ball placed inside a valve casing is rotated by a valve shaft that passes through the valve casing in an airtight manner, and an annular valve seat placed on the inlet side, outlet side, or both of the inlet and outlet sides of the valve ball is rotated. They work together to open and close fluid passages.

In particular, the present invention relates to a sealing structure between the outer periphery of the annular valve seat and the wall surface of the valve casing.

BACKGROUND ART A conventional sealing structure between an annular valve seat and a valve casing is disclosed in, for example, Japanese Patent Application Laid-Open No. 52-94528. This is a device in which an annular groove is formed on the outer periphery of the annular valve seat, and an O-ring is placed in the annular groove to create an airtight seal between the outer periphery of the annular valve seat and the cylindrical wall surface of the valve casing facing the valve casing. It is. Synthetic resin or synthetic rubber is usually used as the material for the annular valve seat and O-ring.

Problems to be Solved by the Present Invention The structure described above has the problem of leakage occurring within a short period of time after use when used in a place where heating and cooling are repeated. That is, when an O-ring made of synthetic rubber is repeatedly heated and cooled, it expands at high temperatures and the compression allowance becomes large, and contracts and becomes smaller at low temperatures. Therefore, it is necessary to design it so that sufficient sealing force can be obtained even during low-temperature shrinkage. This is because the compression allowance becomes larger than necessary at high temperatures, and permanent deformation accumulates, making it impossible to seal.

The technical problem of the present invention is therefore to make it possible to maintain a good sealing effect between the annular valve seat and the valve casing over a long period of time even when subjected to repeated heating and cooling.

Means for Solving the Problems The technical means of the present invention taken to solve the above problems is to arrange a valve ball having a through hole in a valve casing that forms a fluid passage, thereby making the valve casing airtight. An annular valve seat made of synthetic resin or synthetic rubber is placed in the fluid passageway, and the valve ball is rotated by the valve shaft that passes through the valve shaft, and the annular valve seat is made of synthetic resin or synthetic rubber and works together with the valve ball to open and close the fluid passageway by coming into contact with the valve ball. In this case, an annular groove is formed on the inner periphery or side surface of the annular valve seat, a temperature-responsive member such as a bimetal or a shape memory alloy is arranged in the annular groove, and the temperature-responsive member connects the outer periphery of the annular valve seat to the wall of the valve casing. It is designed to be strongly biased at low temperatures and weakly biased at high temperatures.

Effect The operation of the above technical means is as follows.

An annular valve seat made of synthetic resin or synthetic rubber expands thermally at high temperatures and contracts at low temperatures. On the other hand, a temperature responsive member such as a bimetal or a shape memory alloy biases the annular valve seat against the valve casing strongly at low temperatures and weakly at high temperatures. Therefore, although the sealing member expands at high temperatures, the biasing force of the temperature responsive member is weak, so that the compression amount of the annular valve seat does not become large and permanent deformation does not occur. Since the pressure to contract is strong at low temperatures, the necessary compression amount is ensured and no leakage occurs.

Effect of invention The present invention produces the following specific effects.

Even if the valve seat member repeatedly expands and contracts due to heating and cooling, the temperature-responsive member changes the biasing force according to the temperature change, so the annular valve seat always performs sealing with the optimum compression margin. Therefore, wear and permanent deformation do not occur, resulting in a long service life.

Embodiment An embodiment illustrating a specific example of the above technical means will be described (see FIG. 1).

The valve casing is formed by a body 1 and an end piece 3 which is threadedly connected to the body 1. Inlet 4 to main body 1 and end member 3
An outlet 5 and a valve chamber 6 are provided to form a fluid passage.

A valve ball 7 is rotatably arranged within the valve chamber 6.
A through hole 8 and a guide hole 9 are formed perpendicularly in the valve ball 7, and a parallel keyway 10 is provided above the guide hole 9.

An annular valve seat 1 is provided on the inlet 4 side and the outlet 5 side of the valve ball 7.
Place 1 and 12. Both valve seats 11 and 12 are made of synthetic resin such as Teflon, and are urged toward the valve ball 7 by coiled shape memory alloys 15 and 16 via liners 13 and 14. Annular grooves are formed on the inlet side surface of the valve seat 11 and on the outlet side side of the valve seat 12, and shape memory alloys 17 and 18 in the shape of end bands are arranged in the annular grooves. Shape memory alloys 15, 16 are annular valve seats 11, 1
2 is strongly biased against the valve ball 7 when the temperature is low and weakly when the temperature is high. The shape memory alloys 17 and 18 urge the outer circumferences of the annular valve seats 11 and 12 against the wall surface of the end member 3 strongly at low temperatures and weakly at high temperatures.

A bearing hole 19 is formed in the main body 1, and a valve shaft 20 is rotatably arranged. The valve stem 20 passes through the guide hole 9 of the valve ball 7 and is inserted into the holding hole 21 of the main body 1 with a bush 22.
mating through. A packing 23 is interposed between the valve shaft 20 and the bearing hole 19, a liner 24 is interposed between the valve stem 20 and the bearing hole 19, and a disc spring 25 is used to bias the valve 26 against the flange 26. An O-ring 27 is interposed on the outer periphery of the packing 23. A handle 28 is fixed to the upper end of the valve stem 20 with a bolt 29. The valve stem 20 is prevented from popping out by a snap spring 31 via a disc 30.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a ball valve according to an embodiment of the present invention. 1...Main body, 3...End member, 4...Inlet, 5...
... Outlet, 6 ... Valve chamber, 7 ... Valve ball, 8 ... Through hole, 11, 12 ... Annular valve seat, 15, 16, 1
7, 18... Shape memory alloy, 20... Valve stem.

Claims (1)

[Scope of utility model registration request] A valve ball having a through hole is placed in a valve casing that forms a fluid passage, and a valve shaft that passes through the valve casing in an airtight manner rotates the valve ball, making contact with the valve ball to open and close the fluid passage. In cases where an annular valve seat made of synthetic resin or synthetic rubber that works together with a valve ball is placed in the fluid passage, an annular groove is formed on the inner circumference or side surface of the annular valve seat, and a bimetal or shape memory material is formed in the annular groove. A ball valve in which a temperature-responsive member such as an alloy is arranged so that the temperature-responsive member biases the outer periphery of the annular valve seat against the wall of the valve casing, strongly at low temperatures and weakly at high temperatures.