• Valve and solenoid valve operated by very small force

    Date: 2011-12-9 9:52:57
    The present invention relates to a valve and a solenoid valve for opening and closing the flow of fluid in a fluid pipe. Particularly, the present invention is concerned with small-sized opening/closing valve and solenoid valve capable of being operated by very small force and electric power, using a dry cell or the like.

    The present invention concerns an improved technique relating to a valve constructed so that a partial opening is made between a valve body and a valve seat in a closed state of the valve to eliminate a back pressure of fluid acting on the valve body and thereafter the valve is fully opened, a valve capable of operating positively without the leakage of fluid even when the back pressure is very low, and a solenoid valve using those valves. The present invention can contribute to the reduction in size of a valve driving electromagnet, power saving and the stabilization of operation.

    Heretofore, as an automatic open/close controlling valve for gas appliances such as city gas appliances, there has been used a small-sized solenoid valve which is operated using a dry cell or the like. Calculation will now be made about the force required for opening and closing a 28 mm dia. in a city gas pipe for example used at an end user. For example, in a solenoid valve wherein fluid of gas pressure of 500 mm in terms of water column is opened and with a 28 mm dia. valve, a back pressure of about 300 g is exerted on the back of the valve in a closed state. An electromagnet for opening and closing such a valve requires a valve holding spring force of 250 g, so it has heretofore been necessary to use a large-sized electromagnet having an initial pull-up force of 550 g and a stroke of 6 mm or so.

    Thus, in the prior art, a large-sized electromagnet is required because of a great influence of the valve back pressure, so it is impossible to adopt a power source of a very small capacity such as a dry cell for example and the use of a commercial power source is unavoidable, thus resulting in increase of the equipment cost.

    There has been proposed a technique of attaching a small pilot valve for pressure equalizing to a valve, opening pilot valve prior to opening of the valve to eliminate the difference between upstream pressure and downstream pressure, thereby decreasing the force required for valve opening and closing to reduce the differential force of the valve. According to such technique, there have been known a construction wherein a pilot valve is disposed in a by-pass, and a construction wherein a valve element itself is formed with a pilot valve to provide a two-stage motion structure for a valve stem of a valve body between pilot valve open and valve body open.

    It is the object of the present invention to solve the above-mentioned problems of the prior art and provide an improved valve capable of being operated and closed with a very small force or a very small power source such as a battery without the need of using such a separate valve as has been referred to above, and also provide an improved technique relating to a solenoid valve using such improved valve.

    As to the valve stem supporting means used in the present invention, no limitation is made to the above two embodiment of solenoid valve. Various other constructions may be adopted if only the valve stem slides in linear contact with the movable iron core in the circumferential direction of the valve stem.

solenoid valve
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