Fluid handling – Line condition change responsive valves – Pilot or servo controlled
Reexamination Certificate
1999-10-05
2001-07-24
Huson, Gregory L. (Department: 3753)
Fluid handling
Line condition change responsive valves
Pilot or servo controlled
C137S066000, C137S491000, C137S613000, C251S047000
Reexamination Certificate
active
06263908
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention is directed to the field of gas controls, and in particular to an improved slow opening gas valve having an expansible auxiliary chamber connected to an expansible control chamber by a metering orifice to slow the expansion of the expansible control chamber and thereby slow the opening of the gas valve.
2) Description of the Related Art
It is well known that gas valves of the type to which the present invention relates are configured to provide gas at an outlet for ignition at a specific pressure level. In many of these gas valves, the amount of gas provided at the outlet at the time ignition takes place causes an undesirable audible ignition. This audible ignition results from the rapid opening of the gas valve which causes excessive gas build-up in the combustion chamber of for example, a furnace, before ignition. Thus, many of these “fast” open gas valves introduce too much gas before ignition takes place, thereby causing a very rough and/or audible ignition. In addition to producing this undesirable audible ignition, these gas valves may create large flames upon ignition which could be dangerous.
A variety of gas valves are known in the art for providing slow opening valves and ignition at lower gas pressures. In general, however, many of the known-gas valves do not provide a sufficient duration of continuous valve opening and further do not provide a smooth and gradual opening of the gas valve. Additionally, these gas valves are generally complex in both design and operation, thereby increasing the likelihood of problems during operation.
Some of these known valves attempt to restrict the flow of gas to the operating or control gas side of a regulator diaphragm, while others add tortuous paths to the operating side of a regulator diaphragm. Still other valves add second diaphragms to regulate operating pressure or utilize solenoids in connection with pumps to slow the opening of the valves. Finally, other known gas valves include pressure relief valves or regulated by-pass valves for controlling gas pressure.
Generally, the known gas valves which include a second diaphragm, do not use that second diaphragm to slow the opening of the valve, but utilize the diaphragm to control operating pressure or venting of the valves. Overall, these gas valves are relatively complex, which may result in problems with reliability. Further, these gas valves fail to provide both a slow and continuous smooth opening of the valve. Thus, an undesirable audible or rough ignition may still occur.
What was needed was a gas valve with a simple design, that could be produced inexpensively, and that not only provided gas flow for lower pressure ignition, but also provided gas at a continuously and smoothly increasing rate to avoid undesirable rough or audible ignitions.
SUMMARY OF THE INVENTION
In order to overcome these shortcomings and other needs in the art, the slow opening gas valve of the present invention introduces considerably less gas at the time of ignition by providing continuous gas flow both slowly and smoothly increasing, therefore allowing gas to ignite at a lower pressure with a much less audible sound.
According to one aspect of the present invention, a slow opening gas valve is constructed to allow gas to ignite at a low pressure, thus providing a much lower audible and less rough ignition, along with less rollout of gas flame upon ignition. The slow open gas valve of the present invention is of the type having an inlet, an outlet and an expansible control chamber. The gas valve is provided with a normally closed valve member for controlling flow of gas through the gas valve. A diaphragm forms a movable wall of the expansible control chamber and is operable upon expansion of the chamber to move the valve member to an open position. The improvement to the gas valve is an expansible auxiliary chamber connected to the expansible control chamber by a metering orifice, which slows the expansion of the expansible control chamber and thereby slows the opening of the valve member in the gas valve. The expansible auxiliary chamber comprises a moveable diaphragm and a control device, such as a regulator preferably comprising a biasing spring, for controlling movement of the diaphragm.
The volumes of the expansible control chamber and expansible auxiliary chamber are preferably configured to coordinate to slow the opening of the valve member and provide continuous gas flow at the outlet smoothly. The volumes of the expansible chambers are configured to provide control of the opening of the valve member, such that gas at the outlet is provided gradually. Additionally, the diameter of the metering orifice is configured to control gas flow from the expansible control chamber to the expansible auxiliary chamber, thereby slowing the opening of the valve member and providing gas at the outlet gradually and smoothly.
According to another aspect of the present invention, a slow opening gas valve with a normally closed valve member is provided with a bypass orifice which is configured to initially allow a required flow with the valve member closed, followed by a gradual and smooth opening provided by the expansible chambers and the metering orifice. This initial flow through the bypass orifice provides a “step” function followed by the desired slow opening of the valve member. This function provides optimum outlet pressure for gas ignition instantly and thereafter opens the valve member smoothly, resulting in the desired continuous gradual and slow opening.
According to still another aspect of the present invention, a slow opening gas valve is provided such that after a specified time period, determined by the volumes of the expansible control chamber and the expansible auxiliary chamber, and the size of the metering orifice, the valve member is sufficiently open to allow ignition of gas and then continues to gradually open to provide full gas flow through the valve. Therefore, the gas valve provides a desirable continuous slow and gradual opening feature which produces less gas at the time of ignition, thereby minimizing ignition noise and rollout of gas flame that normally results from typical “fast” opening gas valves.
According to yet another aspect of the present invention, a method of controlling flow of gas uses a metering orifice to control the flow of gas through a valve having a valve member and an expansible control chamber, and comprises the step of slowing the expansion of the expansible control chamber using an expansible auxiliary chamber connected to the expansible control chamber by the metering orifice, thereby slowing the opening of the gas valve. The metering orifice and the expansible auxiliary chamber are sized to provide opening of the valve member gradually and smoothly. The method may further comprise the step of slowing the opening of the gas valve using a regulator coordinating with the expansible auxiliary chamber and the step of initially allowing gas flow with the valve member closed by using a bypass orifice, followed by a gradual and smooth opening. The initial flow through the bypass orifice provides optimum ignition gas pressure instantly, followed by a continuous and smooth opening of the valve member.
Thus, the present invention provides numerous novel features and advantages over prior gas control valves. In particular, the invention provides continuous slow gas valve opening that is both smooth and gradual, thereby resulting in ignition of gas at a low pressure achieving a much quieter ignition than provided by other known gas valves. The quieter ignition of the gas valve of the present invention eliminates the undesirable sound that oftentimes can be heard throughout a house, such as when a thermostat turns on an attached furnace system. Additionally, by providing a smoother ignition, the gas valve of the present invention may prolong the life of the component parts of the furnace or other system to which it is connected. Finally, the gas valve of the present invention, by allowing ign
Love John J.
Santinanavat Mike C.
Emerson Electric Co.
Harness Dickey & Pierce
Huson Gregory L.
Krishnamurthy Ramesh
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