US3004713A - Combination valve and safety pilot - Google Patents

Description

Oct. 17, 1961 J. o. THORSHEIM 3,004,713

COMBINATION VALVE AND SAFETY PILOT Filed Nov. 21, 1957 A ssaaad INVENTOR.

JOSEPH O. THORSHEIM ATTORNEY United States Patent 3,004,713 COMBINATION VALVE AND SAFETY PILOT Joseph 0. Thorsheim, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Filed Nov. 21, 1957, Ser. No. 697,964 2 Claims. (Cl. 236-68) This invention relates to a combination valve and safety pilot and, more particularly, to a fluid pressure operated valve that is adapted to be actuated by two condition responsive controllers.

It is generally and broadly well known in the heating controls art to provide a valve which is controlled by means responsive to room temperature and also responsive to the presence or absence of a pilot flame to cause closure of the valve in the event the room temperature reaches the desired level or the pilot flame becomes extinguished.

One of the objects of this invention is to provide a much simpler, inexpensive, reliable and generally better fuel control device of the above-mentioned type.

It is another object of this invention to provide a combination valve and safety pilot with a fluid power actuator that is fail safe. 7

Another object of the invention is to provide a fluid power actuator for a valve that provides negative feedback, to decrease the opening and closing time constant for the valve under the control of a condition responsive means.

Still other objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying draw ing wherein the only figure of the drawing shows the invention in vertical cross-section and with portions thereof broken away.

The invention comprises a valve body 1 having a threaded inlet 2, a threaded outlet 3, and a valve seat 4 surrounding an opening 5 in a partition 6 between the inlet and outlet. A plate '7, secured to the body 1 by bolts 8 closes the open bottom of the valve body while a plate 9 is secured to the top of the body 1 by bolts 10 to seal the open top of the valve body.

A bellows 11 is brazed or otherwise secured at its open end 26 to the cover plate 9 and is similarly secured at its other closed end to a valve stem 12 which, in turn, is swivelly connected to a valve disc 13 by a conventional ball and socket connection 14-45. The valve disc 13 has a washer-shaped rubber valve seat 16 cemented or otherwise secured in a recess in the valve disc to provide a gas tight seal with the valve seat 14 and also to provide electrical insulation between the valve disc and the valve seat. The normal position of the free end of the bellows would be closer to the fixed end were it not for the fluid in the bellows.

A capillary tube 17 extends through a small opening 18 in the plate 9 to a bulb 19. The bulb 19, capillary tube 17 and bellows 11 may be completely filled with a liquid that does not vaporize at pilot burner flame temperature or it may be partially filled with a liquid that vaporizes at or slightly below the temperature to be sensed by the bulb 19. As illustrated, the bulb 19 has a heat conducting rod 20 extending therefrom that is adapted to be positioned in front of a pilot burner so as to sense the presence or absence of flame at the pilot burner to expand or contract the bellows, respectively.

The other end of the bellows 11, which is connected to the valve 13, is free to move in the outlet chamber to open and close the valve l3 upon expansion and contraction of the bellows 11.

The fluid in the bellows 11 is adapted to be expanded by the supplying of heat to the bellows in the form of electric current. A lead wire 21 is electrically connected to the movable end of the bellows 11 through the valve stem 12 and to a terminal member 22 extending through a terminal block 23. The block 23 is secured over an opening 24 in the side wall of the valve body by means of bolts 25. As the fixed end of the bellows is electrically connected to the cover 9, current can be made to pass through the bellows 11 from a power source 29, lead 2211 the terminal 22, lead 21, bellows 11, plate 9, terminal 27 connected to the plate 9, lead 27a, thermostat 28, lead 28a and power source 29.

The apparatus is illustrated as having a pilot burner flame playing on the heat conducting rod 20 and with the room thermostat in satisfied or open contact condition. Assuming that the valve is connected to a source of gas and to a main burner of a furnace, by pipes not shown, the fluid in the bulb 19 has been expanded as much as it will be by the pilot flame but still not enough to cause movement of the valve 13 from the valve seat 4. Should the roomtherrnostat circuit be closed, as by a drop in temperature around the room thermostat, electric current will pass through the bellows 11 from the movable end thereof to the closed end thereof and cause heating and further expansion of the fluid, to additionally expand bellows 11. This additional expansion is suflicient to cause lifting of the valve 13 from the valve seat 4, to permit gas to flow from the source of supply to the main burner. The valve will remain open until the main burner has supplied suificient heat to the space surrounding the thermostat to cause the thermostat control circuit to be broken. Upon the discontinuance of the flow of current, the bellows 11 will cool and cause closing of the valve 13.

Should there be a pilot flame failure while the valve is open under the control of the room thermostat, fluid will flow from the bellows 11 back into the bulb 19, to

cause closure of the valve 13 and provide safety shut 7 down. It is also to be noted that should there be any rupture of the bellows 11 while the valve is open, the escape of fluid from the bellows 11 will cause safety shut down. Therefore, the combination valve and safety pilot provides fail safe operation. If desired, a spring may be added to bias the valve closed upon rupture of the bellows or bulb instead of relying on the resilience of the bellows itself to cause closure of the valve.

Since the bellows 11 is in the stream of the gas flowing from its source of supply to the main burner, the gas constantly provides a cooling efiect to the bellows as long as the valve is open. This cooling effect provides what may be called negative feedback and tends to provide closing of the valve even though the room thermostat is calling for heat. It will also be apparent that this cooling effect of the gas flow over the bellows will also help conduct the heat away from the bellows 11 when the electrical current is cut ofl to thus provide quick shut down of the valve when the room thermostat contacts open. When the valve is closed, there will be no gas flow over the bellows so that when electrical current is supplied to the bellows 11 to cause opening of the valve, there will be quick heating of the bellows and quick opening of the valve in response to a call for heat by the room thermostat.

When the bulb and bellows are filled or partially filled with a liquid that vaporizes at the desired control temperature, the pressure of the system will be the vapor pressure corresponding to the temperature of the coolest part of the enclosure. By proper calibration, the opening of the valve can only occur when both the bulb and bellows are raised to the control temperature.

While I have disclosed the preferred embodiment of the invention, it is deemed to be obvious that modifications may be made therein without departing from the spirit of the invention. Therefore, the scope of the invention should be determined solely from the appended claims. 7

I claim: 7

1. The combination comprising a metallic valve body having an inlet and an outlet and a passage therebetween; a valve seat extending across said passage; an electrically nonconductive valve cooperable with said seat, and an expandable chamber made of metallic electrically conductive material in said passage between said seat and said outlet; means operably connecting said valve to a movable wall of said chamber; another portion of said chamber being fixed to and electrically connectedto said metallic valve body; a fluid-filled temperature responsive unit; a fluid passage between said chamber and said unit; and condition responsive'rnean's including electrical connections to said body and to said moving wall for passing a current through said wall thereby electrically heating said chamber so as to cause expansion of the fluid in said chamber; the fluid in said chamber being heated by the joint action of the temperature responsive unit and the electrical heating of said chamber by said condition responsive means; said fluid exerting suflicient expansive forces in said expandable chamber to open said valve only on the existence of the action of the temperature responsive unit and the simultaneous passage of electrical current to said expandable chamber.

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2. In a fluid flow device comprising a valve body having an inlet and an outlet and a passage therebetween; a valve seat extending across said passage; a valve cooperable with said seat; an expandable chamber in said passage and having a movable wall positioned in a direct heat exchange relationship I with the" main fluid flow through said valve body; means operably connecting said valve to said movable Wall of said chamber; saidchamber being fixed to said valve body; a fluid-filled temperature responsive unit responsive to first heating means; a fluid passage between said chamber and said unit; and second heating means heating said chamber so as to cause expansion of the fluid in said chamber tending to open said valve; the fluid in said chamber, passage, and unit being such that said chamber; can cause opening of said valve only when both first and second heating means are operable.

References Cited in the file of this patent UNITED STATES PATENTS "1,612,246 Whittingham Dec. 28, 1926 1,886,439 Wells ---1 Nov. 8, 1932 2,047,878 Machintosh July 14, 1936 2,093,693 Dillman i Sept. 21, 1937 2,758,791 Jenkins Aug. 14, 1956

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