The invention as disclosed here within consists of a shutoff valve for the control of gas or liquid to an appliance. The valve automatically controls the flow of gas to the appliance over a fixed or variable duration of time. A typical application positions the shutoff valve in a supply line to a cooking device or any other gas appliance that is typically manually regulated and requiring safety or conservation procedures.
In a typical scenario many homeowners have gas grills outside, and from time to time, will leave the grill on accidentally or on purpose to burn excess fat. Once returning inside their homes for dinner they then forget to turn off their grill until reuse. Many times an entire propane tank will be emptied equivalent to many dollars of fuel wasted. In their haste, many users of gas grills will find that the next time they want to use their grill there is no gas in the tank. Gas grills come in many configurations and are popular. The number of gas grills currently in use is very large. The monetary savings on lost fuel would be great if those grills had a non-operator way of turning off fuel. There may even be times when grills are placed near buildings or other flammable materials and once forgotten, heat up and start dangerous fires. What is needed is a low cost accessory device (an automatic shutoff valve, as in the spirit of this invention) to conserve fuel while assuring a level of safety. This accessory shut-off valve would be easily installed and configured to any common gas grill connecting directly to a typical propane tank. In an alternatively configuration, the automatic shut-off valve is part of the propane tank control valve assembly. Furthermore, what is needed in the spirit of forgetfulness, the automatic shut off valve works in the background, not requiring any adjustments or pre-set maintenance, ensuring conservation of propane fuel and safety at every forgetful use of the gas grill.
U.S. Pat. No. 6,289,792 to Grando, et al. discloses a whole barbecue with a cut-off valve built in requiring a preset condition by the user at every use. A mechanical clockwork timer unit is required to be set in conjunction with a single use of the cut-off valve operation. The cut-off valve additionally relies on a thermocouple installed at the burner area in its primary embodiment to burn fat off the grill. Typically the amount of time must be adjusted by the user for every use, depending on the amount of fat on the burner, or maybe guessing the time required depending on the type of meat cooked or the amount of total cooking time. Additionally, the cut-off valve is configured to open to a maximum, rapidly burning the fat as another objective of the invention.
An object of the present invention is to provide a shut-off valve assuring that if an appliance is accidentally left on, it will be automatically shut off at every use without operator intervention or interaction. Another object of the present invention provides that the shut-off device can easily install and fit to a typical propane tank used in many outdoor gas grills. The shut-off valve fits between conventional industrial connectors used by propane tank and gas grill manufacturers. The installation procedure is unchanged from the typical grill supply line connection, fitting the portable shut-off valve between the tank and supply line, the body of the shut-off being sufficiently rigid to support the supply line and the overall length of the valve small enough for an easy fit. Once installed the shut-off valve stops flow of unwanted propane at every use.
Another object of the invention provides a means to adjust the time for which the appliance can stay on when and if the user neglectfully leaves appliance on. This feature the invention allows for flexibility in cooking times.
These and other objects are met by providing a low cost and portable automatic shut-off valve that easily fits to any common gas grill, guaranteeing conservation of fuel and safety at every use. Another object of the invention is, once activated; the invention can be manually reset with a button, allowing again full operation of the grill. The manual reset is in the spirit of the invention, since the operator that neglectfully left the gas grill on will not be able to re-light the grill until he resets the shut-off device, essentially reminding him of his misdeed, and hopefully preventing a repeat performance.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.
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An electronic timer (17) receives a signal from a pressure sensor (18) via a pressure measurement port (19). The pressure measurement port is positioned approximately in the appliance feed bore passage (4b) measuring either atmospheric pressure Pa (open position-static; barbecue not in use) or flow pressure Pf (open position-dynamic; barbecue in use—flow chamber pressure measured as Pf). In a preferred embodiment of the invention, the timer connects to the solenoid, pressure sensor, and a timer selector control (20) and is electronically powered by a small battery (21) as shown in
In the preferred embodiment of the invention, the timer counts down time from the initial flow through the shut-off valve (pressure sensor measures Pf which is greater than Pa), until ultimately it automatically shuts off, according to selection on the timer selection control. The timer selector control, in the preferred embodiment, allows for a user interface for incremental time adjustments, for example 0, 1, 2, 3 hours, where 0 hours is equivalent to nullification of shut-off valve operation. These settings allow for the flexibility in different cooking times to accommodate different foods.
In an alternative embodiment of the invention the pressure sensor and pressure measurement port could be replaced with a flow nozzle where differential pressures inside the nozzle trigger similar circuit responses. Another alternative embodiment of the invention replaces the pressures sensor and pressure measurement port with the flow gate positioned approximately in the appliance feed bore passage (4b) rotating to break an electronic connection when the gas is turned on, triggering the timer.
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Under a different decision scenario, BOX 7 shows the appliance has been left on longer than allowable set duration of time (limiting operation set, for example 1 hour), and thus, the stopper piston is released shutting off gas flow in the float chamber and ultimately to the appliance. Additionally, the logic circuit resets the timer to zero (t=0), and the shut-off valve timer circuit is ready for the next time. BOX 8 represents in the user scenario that condition whereas the user returns to the appliance noticing that the appliance gas operation valve is open, and closes it. BOX 9 in the flow diagram the user would be required to push the RESET button on the shut-off valve to make operable the appliance again. The RESET button locks the stopper piston down as in
Although the invention has been described in conjunction with specific embodiments, it is evident that many alternatives and variations will be apparent to those skilled in the art in light of the foregoing description.
In an alternate embodiment the electronics can be replaced with a pressure actuated clockworks whereas said flow pressure Pf works on a mechanical bellows to preload the clockworks that pulls the release pin (15) after the set duration of time.
Another embodiment similar to the previous replaced the pressure loading mechanical bellows with a mechanical system of levers and gears working in conjunction with appliance operator valve, so that once the appliance is used the said clockworks is preloaded.
Accordingly, the invention is intended to embrace all of the alternatives and variations that fall within the spirit and scope of the appended claims.