Fluid handling – Line condition change responsive valves – Direct response valves
Reexamination Certificate
1999-10-07
2004-02-17
Rivell, John (Department: 3753)
Fluid handling
Line condition change responsive valves
Direct response valves
C137S505000
Reexamination Certificate
active
06691735
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In the current state of the art, it is known that many pressure regulators can be set for a specific pressure, e.g. 10″ (inch) Water Column (the preferred pressure for liquid propane bottled gas). Also known in the art are pressure regulators, in which a pressure spring bears on a membrane and can be set for a second specific pressure by reversing a sealing cap, which is located above the pressure spring. In the models previously described, a screwed sealing plug is designed in such a way that it makes no difference from which side of the pressure regulator the plug is screwed in or pulled out. The adjustment necessary for the regulator to operate at a second set pressure is achieved by making the sealing plug consist of two cylindrical pads each of differing lengths over a sealing component. These cylindrical pads grip within a recess in the pressure spring, so that the spring has a different length due to the amount of compression from the spring. This, in turn, bears on the membrane with a greater pressure thus creating the desired pressure.
The primary disadvantage with this earlier design is that the sealing screw, which is normally loosened by a tool and then reversed (turned over), must be reinserted in the same hole. When this is done, there is a possibility that dirt or debris can fall into the hole and become stuck under the pressure spring. In addition, if an improperly sized wrench or an incorrect tool, such as pliers, are used to loosen the sealing screw, the second uncovered threading that is used in the adjustment could be easily damaged. In either case, the adjustable pressure regulator described above could is limited since it can only be used for two predetermined pressure settings.
Other pressure regulators have an additional screw located beneath the sealing screw. This additional screw presses on a spring that bears on the membrane. After removal of the pressure spring, the second screw located under the sealing screw can be turned in or out, thus shortening or lengthening the path of the pressure spring. This results in a pressure regulator that can be adjusted very precisely to a given pressure setting.
The disadvantage with this design, however, is that the adjustment to different pressures can only be made by an expert. The expert must have specific measuring devices that can verify the desired pressure when the adjustment is made. This task is very expensive, because the gas flow pressure must be measured. This requires that all the jets through which the gas flows must be fully opened. These jets are installed behind the pressure regulator and can be closed by gas valves, normally.
The current state of the art for pressure regulators normally found on the market incorporate a pressure spring, which bears on a membrane. Various methods are used to set and control predetermined pressures, wherein a spring is pressed against a membrane to achieve a particular pressure. These predetermined pressures cannot be precisely maintained. Cost and assembly requirements yield average tolerances of ±5%. In order to further facilitate the manufacture of pressure regulators in the industry, there are efforts within the market to relax the tolerances from ±5% to ±10%.
Increasing the manufacturing tolerances of pressure regulators from ±5% to ±10% will have a detrimental effect on the final product. Gas regulators with a tolerance of ±10% that have been designed to run at 30 mbar (millibar) pressure could have an actual manufactured pressures that range from 27 mbar to 33 mbar. The effects of varying gas pressures are well known in the art.
An appliance manufacture usually specifies the performance of a gas burner at a setting of 20,000 Btu/h (British thermal unit/hour). This permits the manufacturer to calculate when a steak at this setting will be grilled well done within a specified time. The steak will neither be burned nor left almost raw. A consumer, relying on this representation, would see a big difference in how underdone or well-done his steak was cooked, if a ±10% tolerance range in the gas pressure was allowed, since the burner would operate between 18,000 Btu/h and 22,000 Btu/h in the above example. The steak could be either almost raw or burned, due to variances in the operating pressure from the predetermined design pressure.
An additional shortcoming of current designs in pressure regulators concerns the atmospheric pressure above sea level. Many manufacturers offer gas appliances for either sea level or for high altitudes, since the atmospheric pressure varies with the altitude. At higher altitudes there is less oxygen available to mix with a flammable gas used in a gas burner. To compensate for the reduced amount of oxygen at these altitudes, manufacturers typically use gas jets with different orifice diameters, which is determined by the particular altitude at which the appliance is located.
This means that the manufacturers must both produce and warehouse appliances not only for a variety of flammable gases, i.e. liquified propane, natural gas, etc., but also, they must equip these appliances with different sized gas jet orifices for various altitudes. If these design concessions are not made for the consumer, the grill may not heat up sufficiently to cook their food or conversely the grill will be too hot to cook food without burning it.
The best method of assuring that the Btu/h rates specified by the manufacturer corresponds to the actual rates at the location where the gas-burning appliance is to be used, is to use an adjustable pressure regulator. As previously mentioned, the older adjustable pressure regulators are inconvenient to use, requiring an expert with the correct measuring devices to adjust the regulator.
It is undesirable to force the consumer to expend additional funds on an expensive procedure to adjust the gas pressure, so that he can use his gas appliance. A consumer, after purchasing a new gas grill, reasonably expects that the gas grill can be used immediately. The consumer assumes that the gas grill has been correctly adjusted for the altitude that the grill is located, and the type of flammable gas that is to be used. The consumer is generally ignorant of the effects of different altitudes on grilling times or the effects of spring pressures on a membrane in their gas pressure regulator.
2. Description of the Prior Art
Prior art U.S. Pat. No. 1,485,959 discloses a Pressure Regulating Valve. This invention uses a standard threading to vary the input to the output pressure. Another object of this patent is to create a valve that has a diaphragm that more easily retains it's resiliency, even after extreme distortion. This invention uses the position of a valve within a bore to regulate the pressure. The fluid enters the valve and is directed downwards through the bore where the valve's position regulates the flow to a chamber, then to a passageway which leads to an exit port.
Prior art U.S. Pat. No. 2,076,000 discloses a Flow Controlled Device. The object of this invention is to create a regulation device for liquids that is operable in either direction. Flow control is achieved by the use of a vane and a cam. Pressure from one side of the vane will cause the vane to pivot on it's supports. A cam follower will lift a valve member from it's seat and permit escape of the liquid from a plug aperture. The plug aperture leads to a drain trap. The flow control is entirely maintained by the pivoting of the vane.
Prior art U.S. Pat. No. 3,374,803 discloses a Volume and Flow Control Device. The object of this invention is to create a simple and economical device for controlling the volume and flow of air to a motor. This device operates by means of a moveable piston. A threaded knob applies pressure to the piston through a spring, with an opposing spring maintaining piston position from below by applying an upwards pressure. The intake end has a passage that communicates with a groove between the piston and t
Brande Lewis M.
Brande and McCleary
McCleary Thomas A.
Rivell John
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