Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Reexamination Certificate
2001-12-07
2003-10-07
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
C137S505180, C137S505360, C251S064000
Reexamination Certificate
active
06629544
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas pressure-reducing valve. In particular, it relates to an improvement of a gas pressure-reducing valve, wherein a pressure-reducing chamber for generating a gas pressure that acts on one surface of a diaphragm is formed within a valve housing that clamps the peripheral edge of the diaphragm, a valve body that can sit on a valve seat having in its central part a valve hole communicating with the pressure-reducing chamber is fixed to one end of a valve stem penetrating the valve hole in an axially movable manner, the other end thereof being connected to the central part of the diaphragm, and a spring biasing the diaphragm in a direction that detaches the valve body from the valve seat is housed in a spring chamber formed within the valve housing, the spring chamber facing the other surface of the diaphragm.
2. Description of the Related Art
Conventionally, such a gas pressure-reducing valve is already known in, for example, Japanese Patent Application Laid-open No. 11-270718, wherein a valve housing is formed from a body and a cover fastened to the body, and the peripheral edge of a diaphragm is clamped between the body and the cover.
In the above-mentioned conventional arrangement, since a pressure-reducing chamber is formed between one surface of the diaphragm and the body, the body structure surrounding the pressure-reducing chamber becomes complicated, thereby raising the possibility that the machining precision might be degraded. Furthermore, when the diameter of the diaphragm is made small in order to satisfy a need for reducing the dimensions of the gas pressure-reducing valve, it becomes necessary to make small the diameter of the pressure-reducing chamber facing said one surface of the diaphragm, thereby changing the flow characteristics of the gas pressure-reducing valve and bringing about a situation where the gas pressure of the pressure-reducing chamber might fall below the target control pressure by a large amount.
SUMMARY OF THE INVENTION
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to provide a gas pressure-reducing valve that can enhance the machining precision by simplifying the body structure and determine the diameter of the pressure-reducing chamber regardless of the diameter of the diaphragm.
In order to accomplish the above-mentioned object, in accordance with a first aspect of the present invention, there is proposed a gas pressure-reducing valve that includes a pressure-reducing chamber for generating a gas pressure that acts on one surface of a diaphragm; the pressure-reducing chamber being formed within a valve housing that clamps the peripheral edge of the diaphragm; a valve body that can sit on a valve seat having in its central part a valve hole communicating with the pressure-reducing chamber; a valve stem penetrating the valve hole in an axially movable manner wherein one end of the valve stem is connected to the central part of the diaphragm and the other end of the valve stem is fixed to the valve body; and a spring biasing the diaphragm in a direction that detaches the valve body from the valve seat, the spring being housed in a spring chamber formed within the valve housing and the spring chamber facing the other surface of the diaphragm. In this gas pressure-reducing valve, the valve housing is formed by conjoining a body, a partition, and a cover, the body being provided with the valve seat, the partition forming the pressure-reducing chamber between itself and the body and forming a pressure action chamber between itself and one surface of the diaphragm, and the cover forming the spring chamber between itself and the other surface of the diaphragm and clamping the peripheral edge of the diaphragm between itself and the partition, and wherein the partition includes a through hole for allowing the valve stem to run through in an airtight and axially slidable manner and a communicating hole for providing communication between the pressure action chamber and the pressure-reducing chamber.
In accordance with the above-mentioned arrangement of the first aspect, the peripheral edge of the diaphragm is clamped between the cover and the partition interposed between the cover and the body, the pressure-reducing chamber is formed between the partition and the body, and the pressure action chamber that communicates with the pressure-reducing chamber is formed between one surface of the diaphragm and the partition. It is therefore possible to simplify the structure of parts of the body facing the pressure-reducing chamber thereby enhancing the precision with which the body is machined and enabling the partition to be machined easily in a state where it is separated from the body. Furthermore, although the diameter of the pressure action chamber changes in accordance with changes in the diameter of the diaphragm, the diameter of the pressure-reducing chamber which is separated from the pressure action chamber by the partition can be determined independently of a change in the diameter of the diaphragm. Even when the diameter of the diaphragm is made small in order to satisfy a need for reducing the dimensions of the gas pressure-reducing valve, it is unnecessary to decrease the diameter of the pressure-reducing chamber, thereby avoiding the occurrence of any change in the flow characteristics that would cause the gas pressure of the pressure-reducing chamber to fall below the target control pressure by a large amount. Moreover, since the gas pressure of the pressure-reducing chamber does not directly act on said one surface of the diaphragm, it is possible to prevent an excessive load from being imposed on the diaphragm when the gas pressure of the pressure-reducing chamber changes greatly, thereby protecting the diaphragm.
Furthermore, in accordance with a second aspect of the present invention, in addition to the above-mentioned first aspect, there is proposed a gas pressure-reducing valve wherein the body has a slide bore so that the valve body is slidably fitted in the slide bore. In accordance with the above-mentioned arrangement, the axial movements of the valve body and the valve stem are supported at two points; on the inner face of the slide bore of the body; and on the inner face of the through hole provided on the partition, thereby preventing the valve body and the valve stem from tilting and ensuring reliable opening and closing operations of the valve body.
Furthermore, in accordance with a third aspect of the present invention, in addition to the above-mentioned arrangement of the first aspect, there is proposed a gas pressure-reducing valve wherein the diaphragm, the valve stem and the valve body are assembled to the valve housing so that, when the diaphragm is in its natural state without any external force acting on it, the valve body is detached from the valve seat.
In accordance with the above-mentioned arrangement of the third aspect, when the diaphragm is assembled to the valve housing in its natural state without any external force acting on it, the valve body is detached from the valve seat, and when the diaphragm bends so as to seat the valve body on the valve seat in response to the action of the gas pressure of the pressure-reducing chamber, the diaphragm bends toward the spring chamber side so as to be in a state in which the diaphragm exerts a resilient force in the same direction as the direction of the spring force, that is to say, opposite to the direction in which the gas pressure of the pressure-reducing chamber closes the valve. When the valve body is detached from the valve seat to a great extent so as to increase the gas flow, the resilient force exerted by the diaphragm against the force of the gas pressure of the pressure-reducing chamber in the direction which closes the valve becomes small. It is thereby possible to minimize any adverse effect on the responsiveness resulting from the resilient force exerted by the diaphragm, and even w
Ishikawa Kazuki
Nakajima Youji
Saito Yoshio
Arent Fox Kintner & Plotkin & Kahn, PLLC
Hepperle Stephen M.
Keihin Corporation
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