US2307636A - Heat responsive device - Google Patents

Description

Jan. 5, 1943. I R, E; NE'WELL I 2,307,636

HEAT RESPbNSIVE DEVICE- Filed Aug. 3, 1940 INVENTOR. ROBERT EV,"NWELL.

A TTORNE Y.

' the thermostatic s'r'r as 3 Claims.

This invention relates to heat responsive devices, and more particularly to such devices for controlling valves, switches and the like thermostatically; I

In devices of this character usingan expansible and contractible power element as part. of the thermostatic control it is often desirable to a'r-,

range this element in opposed relationship with the member which it actuates. For example, the expansive movement of the power element may be used to force valve or switch members to a closed position instead of merely relieving pressure on these members and permitting springs or other yleldable devices to close them. However, in such arrangements the temperature at which the power element isdesigned to close the valve or switch may be exceeded, causing additional expansion of the element and consequent damage to the parts.

The present invention will be described in connection with a thermostatic valve usedin connection with a domestic gas range but it is to be understood that it is not limited to the use of a valve as the controlling member and it also may be applied to the control of other. types of heating apparatus.

It is an object or the invention to prevent damage to the valve and other parts when the temperature at which the valve is set to close is exceeded.

Another object of the invention is to permit dismantling of the valve and associatedparts as a unit for cleaning and repair so that replacement is facilitated.

Other objects and advantages wili'become apparent from the following description taken in connection with the accompanying drawing which is a front elevation partly in section of a thermostatic valve embodying the invention.

Referring more particularly to the drawing. valve includes a'. main casing It provided with an inlet I2 for gas or other fluid andhaving anend casing ll detachably secured thereto as by means of the screws lb. The end casing It is provided with an outlet It for the gas or other fluid which flows. from the inlet 52 through both casings. At'the opposite end of control assembly for the device in this arrangement comprises a bulb 28, which is located in the oven of the range, and tube 30 operatively connected to an expansible and contractible power element 32 housed within the end casing M. In

a this instance, the end of the tube 30 adjacent the power element 32 is secured in sealing engagement with a stud 3% which projects from the end casing I l and is secured thereto by means of the nut 3b. The inner end of stud- 3% abuts the power element 32 and is provided with an aperture 38 afiording communication between the tube 30 the main casing It is a spud piece 2t forming a support for an operating shaft 22 carrying the v usual dial 2t.

The thermostatic valve thus far described is designed to be housed behind the front panel 28 of a domestic gas range, with the dial 241 and part of the spud piece 29 projecting through the front panel for convenient operation. The thermal and the interior of the power element. This thermal control assembly comprising the bulb 28, tube 36 and power element 32 are filled with a liquid which upon changes in temperature sensed by the bulb 28 will serve to expand and contact the power element 32 as is well known to those skilled in the art.

The operating shaft 22 is suitably bored to receive th end of a valve shaft it which is adapted for longitudinal movement therein, be-- ing prevented from relative rotation by means of a driving pin 52 projecting therefrom into engagement with a slot it formed at the end of the operating shaft 22. The valve shaft lil is provided, intermediate its ends, with an enlarged portion it having a ball face formed on one side thereof. The end 58 of the valve shaft W which projects beyond the enlargement $5 is reduced in diameter and has a threaded thimble El -i secured on the end thereof. It will be understoodthat the thimble 5!; maybe dispensed with if desired and the threads be formed directly on the reduced end 68. The shoulder formed by the junction of the enlarged portion 56 with the valve shaft 38 is designed to afford an abutment for one end of a coil spring 52, the other end of which may abut a portion of the casing ill.

Communication through the casing between the, inlet opening 52 and outlet i8 is controlled by a valve member 54 which is loosely mounted on reduced end 68 of valve shaft it and is adapted to engage a valve seat 56 formed on the casing it. The engagement of valve member M with the valve shaft dB is efiected by the provision of a ball seat 58 on the valve member 56 which-seat is preferably ground and lapped into sealing en gagement with the ball face of enlargement'ts.

This arrangement permits the valve member to I move bodilyIand also tilt on the shaft 38 with-- out danger of leakage between these parts.

From the details of construction so far describedlit will be apparent that movement of the power element 32 when undergoing expan-- 48 of the valve shaft 40.

. other, due to the fact that the expansive movement of the power element 32 is in a direction tending to force the valve member 54 toward the valve seat 56. This invention is particularly directed toward provision of means for actuating the valve member thermostatically under these conditions without damage thereto or to the associated parts.

To this end, the valve member 54 is provided on the side opposite the ball seat 58 with a 'nose portion 60 forming an abutment for a cup-shaped washer 62 loosely mounted on the projecting end One end ofcoil spring 84 is housed within the washer 62 and the other end projects into the enlarged end 65' of a cap member 66. The cap member 66 is adapted to telescope on a collar 12- having threaded engagement with the thimble 50. The spring 64 serves to force the end'of the cap member 66 into constant. engagement withv the power element 32. Diametrically opposite slots 68 are provided in the cap member 66 and adapted to receive in sliding engagement a pin 10 projecting from the collar Rotation of the collar 12 with the thimble 50 is prevented by the extension of the pin I into suitable diametrically opposite slots I4 formed in a guide member 16 surrounding the cap member 66.

When overshooting" occurs in the use of this thermostatic valve the additional movement of the power element 32 cannot cause damage to the valve member 54 or associated parts. When such movement occurs, the power element 32 merely urges the cap member 66 to the left as viewed in the drawing, causing compression of the spring 64. Such compression will occur whenever the valve member is seated as will be apparent. As soon as the additional heat causing overshooting is dissipated the parts will resume normal The guide member I6 is provided with oppositely disposed flanges 18 which engage in suitable slots 80 formed in the end casing l4 and serve to anchor this member 16 against'movement therein. Prefera'bly, the ends of the flanges 18 which engage in the slots 80 are reversely bent or otherwise affixed in the end casing l4 to afford secure connection of the guide member 16 therein.

In the operation of the device, the dial 24 is rotated to any desired setting, which rotation will serve to move the thimble 50 of the valve shaft 40 longitudinally into the collar 12 and thus cause movement of the valve member 54 away from its seat. This manual adjustment of the device permits gas to flow from the inlet l2 past the valve and through the outlet I8 to the point of relationship and the setting of the thermostat is not impaired.

Another advantage of the construction of the device is that the end casing l4 can be removed from the main casing it, together with the valve stem 40 and all the associated parts as a unit, in order that these parts may be cleaned or repaired. It will be observed that upon removal of the screws Is there is no obstruction to the detachment of the end casing i4 from the main casing ill. Also, due to this construction, the relationship of the parts is not disturbed when the end casing is again assembled, thus facilitating assembly of the control.

I claim 1. In a thermostatic structure for controllingthe temperature of an oven and the like, a staagainst rotation, a cap member abutting said thermally responsive means and telescopically mounted on said adjustment means, means on said cap cooperating with said anchor means to limit said telescopic movement, and a coil spring use, such as the oven of a domestic gas range.

When the temperature of the oven as sensed by the bulb 28 reaches that for which the dial has been set, the power element 32. will expand, forcing the cap member 66 to the left, as viewed in the drawing. .Due to the fact that the spring 84 is fact that the stove manufacturer has not located the bulb element 28 inrthe zone of greatest heat in the oven. Consequently, when the portion of the oven in which the bulb is located reaches the temperature for which the dial is set and the power element moves the .valve to its seat, there may then be additional heat applied to the bulb as the heat flows thereto from the hotter portion of the oven. This occurrence is known as over shooting" and is commonly encountered in the use of devices of this character.

Consequently,

supported on said adjustment means between said movable element and cap for absorbing movements of the thermally responsive means due to additional heat being applied thereto after the elements are engaged, I r

2. In a thermostatic structure for controlling the temperature of an oven and the like, a main casing, an end casing detachably mounted on said main casing, a valve seat in said main casing, and a thermostatic valve assembly cooperating with said seat to maintain selected temperatures in the oven, said assembly comprising a valve member engageable with said valve seat. a valve shaft supported for rotation in said main casing and projecting through said valve member, thermally ref sponsive means supportedin said end casing and spaced from the projecting end of said shaft. adjustment means having threaded engagement with said projecting end for positioning said valve member with respect to said seat, a guide member anchored in said end casing and extending around said adjustment means, an abutment member for said thermally responsive means and slidably mounted between said adjustment means and guide member, a limit stop projecting from said adjustment means through said abutment and guide members for restraining relative rotation and for limiting slidable movement between said oneness adjustment means and abutment member, and a yieldable member extending from said abutment member to said valve member for absorbing movements of the thermally responsive means after having a portion projecting through said movable element and spaced therefrom to permit relative angular movement, sealing means eflective between saidmovable element and manually actuable means for preventing leakage of fuel through said space when said elements are engaged, ad-

justment mesns carried by said projection for positioning said movable element with respect to seid stationary element upon operation of said manually actuable means, and yieldable means extending from. said movable element'to said thermally responsive means for transmitting movements of the latter to said movable element and for absorbing movements ofsaid thermally responsive means after said elements are engaged,

said yieldable means being operable by said thenmally responsive means independent of said adjustznent means and projection when said elements are engaged whereby soid sealing means remains eiiective during said movements.

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