US3792400A

US3792400A - Temperature responsive actuator

Info

Publication number: US3792400A
Application number: US00324310A
Authority: US
Inventors: T Hayes; J Bechtel
Original assignee: Johnson Service Co
Current assignee: Johnson Service Co; Johnson Controls International Inc
Priority date: 1973-01-17
Filing date: 1973-01-17
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

A temperature responsive actuator made up of a bellows-like arrangement of bimetal spherical washers which are arranged in pairs with their concave surfaces in opposing relation. One end of the bellows-like arrangement is attached to a frame member and the other end is coupled to a controller rod which extends axially through the center of the bimetal washer arrangement. A heat control means for supplying heat internally of the bimetal washer arrangement is provided which is energized by a control signal from a remotely located temperature sensor element.

Description

United States Patent [191 Hayes et a1.

[ TEMPERATURE RESPONSIVE ACTUATOR [75] Inventors: Thomas Edward Hayes; Jon Harold Bechtel, both of Goshen, 1nd.

[73] Assignee: Johnson Service Company,

Milwaukee, Wis.

[22] Filed: Jan. 17, 1973 [2]] Appl. No.: 324,310

[52] US. Cl 337/38, 60/23, 73/3635, 337/95, 337/102, 337/335, 337/370, 337/377 [51] Int. Cl. H0lh 71/16 [58] Field of Search. 60/23; 73/3623, 363.3, 363.5; 337/38, 95, 335, 370, 377, 102

[56] References Cited UNITED STATES PATENTS 2,736,501 2/1956 Widell 73/3635 X 3,044,295 7/1967 Shivers 337/335 X [451 Feb. 12, 1974 3,107,532 10/1963 Lingnau 73/3635 X Primary Examinerl3ernard A. Gilheany Assistant Examiner-F. E. Bell Attorney, Agent, or Firm-Johnson, Dienner, Emrich, Verbeck & Wagner [57] ABSTRACT A temperature responsive actuator made up of a be]- lows-like arrangement of bimetal spherical washers which are arranged in pairs with their concave surfaces in opposing relation. One end of the bellows-like arrangement is attached to a frame member and the other end is coupled to a controller rod which extends axially through the center of the bimetal washer arrangement. A heat control means for supplying heat internally of the bimetal washer arrangement is provided which is energized by a control signal from a remotely located temperature sensor element.

13 Claims, 18 Drawing Figures PATENTEB FEB I 2l974 MET-80F? PATENTEB FEB I 21974 SHEET t 0F 7 PATENTED FEB] 2M4 sum 6 or 7 HOT DECK ROOM UNDER CONTROL PAIENI FEB 1 21924 sum 7 or 7 BACKGROUND OF THE INVENTION The present invention relates generally to temperature responsive controls, and more particularly to a temperature responsive actuator having a heat control means which transmits heat to a temperature responsive element in response to a command signal from a remotely located temperature sensor.

One of the design objectives of the present invention is to provide an actuator which will operate from a command signal delivered from a remotely located thermostat to supply heat on demand to a heater internal of a temperature sensor means, whereby the heat transmitted to the temperature sensor means causes it and an associated control rod to move in one direction. Two other design criteria embodied in this invention are its capability of being quickly installed and its relatively maintenance-free operation.

Another object of this invention is to provide a temperature responsive actuator of the type which operates a control rod that has a high stall force compared to prior art actuators. Because a damper or valve occasionally becomes stuck, such as between season shutdown, the actuator must have sufficient force to initially unstick the damper or valve. This unsticking force is substantially larger than the normal force required to normally operate the valve or damper, and as a consequence most bimetal prior art actuators do not have sufficient force rating to provide this initial unsticking operation. This invention inherently has a high stall force of sufficient magnitude to permit unsticking of a valve or damper.

SUMMARY OF THE INVENTION A temperature responsive actuator constructed in accordance with the principles of this invention comprises a plurality of bimetal spherical washers disposed in a bellows-like arrangement. The bimetal washers are arranged in pairs with their concave surfaces in opposing relation and a retainer means pivotally supports the outer peripheral edge of each washer pair. A plurality of annular spacers are used to anchor the inner peripheral edges of the washers. One end of the bimetal washer arrangement is secured to an upstanding wall member. A control rod is slidably disposed through the center of the bimetal washer arrangement and through a second upstanding wall member. The control rod is fastened to the free end of the bimetal washer arrangement. A control means supplies heat internally of the bimetal washer arrangement in response to a control signal from a remotely located temperature sensor.

To adapt the temperature responsive actuator of the present invention for use in a multizone heatingcooling system, a switch means is provided which is actuated by the bimetal washer arrangement expanding or contracting to a predetermined axial length to provide a remote command signal to either the control system for the heating or cooling units.

BRIEF DESCRIPTION OF DRAWINGS For a better understanding of this invention, reference may be made to the accompanying drawings, in which:

FIG. I is a front perspective view of a temperature responsive actuator constructed in accordance with the principles of this invention;

FIG. 2 is a top plan view of the temperature responsive actuator of FIG. 1 with the cover removed;

FIG. 3 is an end view of the FIG. 2 illustration taken from the left side with the left end plate removed;

FIG. 4 is a cross sectional view taken along the line 4-4 of FIG. 2 and looking in the direction of the arrows;

FIG. 5 is a cross sectional view taken along the line 55 of FIG. 2 and looking in the direction of the arrows;

FIG. 6 is a side elevational view of the heat control means used in the temperature responsive actuator of FIG. 1;

FIG. 7 is a cross sectional view taken along the line 77 of FIG. 6 and looking in the direction of the arrows;

FIG. 8 is a cross sectional view taken along the line 8-8 of FIG. 6 and looking in the direction of the arrows;

FIG. 9 is a perspective view of the slide member used in the FIG. 1 embodiment with the switch actuator member shown prior to assembly on the switch actuator member;

FIGS. 10 through 12 show, respectively, an end switch, a frame support for the end switch, and a mounting bracket for mounting the end switch and associated frame member;

FIG. 13 is a front perspective view of one of the insulated boards on which the end switches are mounted;

FIG. 14 is a perspective view of a terminal connector which is mounted on the insulated board of FIG. 13;

FIG. 15 is a schematic diagram of a heat control system using the temperature responsive actuator shown in FIGS. 1 through 5;

FIG. 16 is a schematic diagram of a multizone heating-cooling system using the temperature responsive actuator shown in FIGS. 1 through 5; and

FIGS. 17 and 18 are greatly magnified views of the top portion of two adjacent bimetal washers showing their relative positions under the extreme cold and hot conditions, respectively.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now to FIGS. 1 through 5 there is shown a temperature responsive actuator embodying the principles of this invention and generally designated by the reference numeral 20. Temperature responsive actuator 20 is assembled in an elongated housing 22 comprising a frame member 24 and removable elongated cover member 26. The frame member 24 has a generally rectangular base plate 28 and a pair of

upstanding end plates

30 and 32. The frame member 24 is adapted to be mounted to a support member by four laterally projecting feet 34 which extend outwardly from the four corners of the base plate 28. The cover member 26 has a generally U-shaped cross section and is formed with an intumed edge portion 36 at its two ends to provide a sliding relationship with the

end plates

30, 32.

Contained within the housing 22 is a temperature sensor means 40 which is responsive to changes in the heat generated by a heat control means 42 (FIG. 6) for axially repositioning the location of a control rod 44. The temperature sensor means 40 comprises a plurality of bimetal spherical washers 48 arranged together in a bellows-like arrangement and disposed coaxially with the control rod 44. The bimetal washers 48 have central circular openings 50 therethrough and arranged in flexible diaphragm pairs 46 having their concave surfaces in opposing relation. The inner .peripheral edges 52 (FIGS. 5 and 16) of adjacent diaphragm pairs 46 are anchored in a pair of annular grooves 54 formed around the peripheral surface at the ends of cylindrical spacer elements 56. The concave and convex surfaces of each bimetallic washer 48 are of metallic materials having dissimilar coefficients of thermal expansion, with the inner or concave surface having a higher coefficient of thermal expansion relative to the outer convex surface so that the bimetallic disc tends to flatten during a rise in temperature of the medium surrounding the disc. The outer peripheral edge 58 of washers 48 is interconnected to the adjacent pairs 46 by means of annular ring members 60 which are formed with their central peripheral section 62 depressed radial inwardly to thereby define a pair of spaced annular seats 64 which receive the outer peripheral edge of the washer 48. By virtue of this arrangement, the outer peripheral edge is free to pivot within the annular seat 64 as the diaphragm pairs 46 expand and contract (See FIGS. 17-18).

One end of the temperature sensing means 40 is fixed to the end plate 30 of housing 22 by means of four screws 68 inserted through four openings in the end plate 30 and screwed into an aligned threaded aperture formed at the outer-ends of a bracket 70. This bracket 70 is anchored on the right endmost spacer 56. A collar 72 is anchored on the left endmost spacer 56 and is provided with a radial threaded aperture extending between its central opening 74 (FIG. 5) and its outer peripheral surface. A threaded bolt 76 (FIG. 2) is screwed through this threaded radial opening and tightened against control rod 44 to connect the control rod 44 to the left hand end on temperature sensing means 40. Y

The heat control means 42 comprises a heater assembly 78 (FIG. 6) having a generally cylindrical cross sectional configuration with an outer diameter less than the diameter of the opening through the center of temperature sensing means 40. The heater assembly 78 comprises a heat resistance element 79 spirally wound around a tubular insulative body 82, such as a ceramicv tive body 80.

Referring to FIGS. 2 and 5, the heater assembly 78 is disposed coaxially within the temperature sensing means 40 and has a nose portion 96 projecting through an opening 94 formed in the center section of end plate 30. The nose portion 96 of the tubular insulative body has the radial flutes 82 removed and the right end of the flutes serve as a stop against the inside surface of the end plate 30. The heater assembly 78 is retained in place by means of a retainer ring 98 which is fastened over the nose portion 96 of the tubular insulative body 82.

To conduct the heat from the heat control means 42 to the extended end of the temperature sensor means 40 and to guide the temperature sensing means and center the heater assembly 78 during expansion and contraction, a cylindrical tube 100 made of good heat conductive material, such as brass, is telescoped over the heater end cup 92 and its left end, as viewed in FIG. 5, is attached to the collar 72. With this arrangement, the tube 100 slides over the heater assembly 78 as the stack of diaphragm pairs 46 shorten during heating.

As illustrated in FIG. 5, the control rod 44 extends axially through the housing 22 and is slidably'supported by bushing 102 mounted in center opening 104 of end plate 102 and by the inner cylindrical bore 106 of the heater assembly 108. A clevis-type coupler 110 (FIG. 1) is attached on the threaded end portion 112 of the rod 44. As previously mentioned, the rod is interconnected to the free end of the temperature sensor means 40 by tightening clamp bolt 76 (FIG. 2). It will be appreciated that since the entire actuator 20 is externally symmetrical, reverse operation of the actuator is .obtained by releasing set screw 76, removing the rod 44 and inserting the rod intovthe opposite end of housing 22 as indicated by the dotted clamp 110 in FIG. 1.

Referring to FIG. 15, there is shown a schematic diagram of a heat control system in which the temperature responsive actuator 20 in this invention is used to control a hot deck-cold deck mixing damper 120 disposed within a duct 122. The heat resistance element 79 of the heater assembly 78 is electrically connected inseries with a room thermostat 124 across an AC source 126. The room thermostat 124 has a fixed contact 128 and a movable contact 130 which is repositioned by bimetal element 132 in response to room temperature changes. When the movable contact 130 closes with the stationary contact 128, the heat resistance element 79 isenergized and the resulting increase in temperature within temperature sensor means 40 causes the contraction of bimetal washers 48 and the control rod 44 is pulled inwardly of the housing 22. This inward movement of the control rod 44 opens the dampers 136 in the hot deck section of the duct 122 and simultaneously closes the dampers 138 in the cold deck section. When the bimetal element 132 reaches the contact break temperature due to the heating effect of anticipating resistor 129 (FIG. 15)

contacts

128 and 130 open to deenergize-the heating element 79. When the room temperature reaches the desired setting, the

contacts

128 and 130 open to deenergize the heating element 79. The cooling of the heating element 79 causes the expansion of the bimetal pairs 48 to extend the control rod 44 outwardly of the housing 22 and simultaneously open the cold deck damper 138 wider and swing the hot deck dampers 136 towards the closed position.

Referring to FIGS. 17 and 18, there is shown the relative position of adjacent bimetal disc 48 as the sensed temperature changes from a cold condition (FIG. 17) to a hot condition (FIG. 18). It will thus be appreciated that by virtue of the pivotal connection between the ring elements 60 and the outer peripheral edges 58, the outer free end of the bimetal washers 48 are able to swing over center to an equal bow in the opposite direction and thereby provide the maximum possible extension and retraction of the control rod 44.

One significant advantage of using the abovedescribed bimetal washer arrangement is its ability to initially unstick a damper or valve at extreme control rod positions, which generally occur between season shutdown. Because the bimetal washers 48 have greatest compliance when near their flat shape and the greatest stiffness when curved, the temperature responsive actuator of this invention has its greatest force potential at the extreme limits of the control rods travel.

The temperature responsive actuator built in accordance with the principles of this invention has a slow operation as compared to the normal cycle rate of a self-cycling thermostat -its average time for full travel is approximately 25 minutes while a self-cycling thermostat usually cycles six or seven times per hour. As a consequence, during one thermostat cycle the temperature responsive actuator of this invention moves only a small amount and eventually assumes some average position proportional to the thermostat percentage-on time.

The versatility of this invention is greatly enhanced by the inclusion of a switch means 150 which cooperates with the movement of the temperature sensor means 40. In the embodiment shown in FIG. 2, the switch means 150 comprises two pairs of end switches 152, 154, which are mounted, respectively, on insulating

boards

156, 158 that extend parallel to the control rod 44 on opposite sides of the temperature sensor means 40.

The insulating

boards

156, 158 are identical in construction. For purposes of illustration, circuit board 156 is shown in FIG. 13 in which a plurality of mounting holes for the pair of switches 152 is provided at one end, and a plurality of mounting apertures 164 are provided at the other end for receiving terminal connectors 166 (FIG. 14). The pair of switches 152 (FIG. comprises a conventional microswitch having an actuating lever 168 and three terminal connections 170. Switches 152 are mounted on the board 156 at opposite ends of an elongated slot 172 by means of a pair of upper and lower mounting brackets 174 (FIG. 12). The pair of mounting brackets 174 permits an accurate positioning and holding of the set of switches 152 relative to slot 172. The switches 152 are fastened to a support member 175 having a pair of offset flanges 176 at its two ends that fit under the upper and lower pair of brackets 174 as depicted in FIG. 3. The bracket 174 (FIG. 12) has a pair of end fingers 178 which fit in the two end openings 160 and a screw 180 (FIG. 3) inserted through the central opening 182 can be tightened into the middle threaded aperture 160 until the flange portion 176 of the bracket 174 is held in a fixed position. By virtue of this arrangement, it is possible to position the switches 152 relative to the oval slot 172.

On the side of insulating board 156 opposite to the set of switches 152 there is provided a switch actuator slide member 186 (FIG. 9) having a switch actuator member 188 which projects through oval slot 172 (FIG. 2). Slide 186 has a flat plate portion 190 which slides against the insulating board 156 and a right angle flange portion 192 at its upper end which rides along the upper edge 194 of the insulating board 156. The switch actuating member' 188 has a generally cylindrical body portion 196 of a diameter less than the width of the slot 172 and a reduced diameter threaded end portion 198 which screws into the threaded aperture 200 provided in the flat plate portion 190 of the slide member. An integral collar 202 of a diameter larger than the width of the slot 172 retains the switch actuating member 188 in the oval slot 172.

The slide 186 is adapted to follow the expanding and contracting movements of the temperature sensor means 40 by means of a follower member 210 which is constantly urged against the side of the left end washer 48 by a pair of parallel spring members 212 stretched between upper and lower dog-ears 214 and a pair of upper and lower mounting posts 216 mounted through upper and lower openings 218 in insulating board 156.

One switch 220 is positioned relative to the switch actuator 196 so that its switch actuator 168 is engaged when the temperature sensor means 40 reaches a certain predetermined high temperature. Likewise, the other switch 222 is positioned to be contacted when the temperature sensor means 40 reaches a certain predetermined low temperature. The insulating board 156 is supported in an upright relation to the base plate 24 by means ofa pair of spaced upstanding eyelets 224 which are punched out of the base plate 24.

The other insulating board 158 is identically constructed to board 156 and the set of switches 154 is mounted on board 158 in exactly the same manner as set 152 is mounted on board 156. Referring to FIG. 4, the insulating board 158 has a plurality of terminals 230 at one end, and the set of switches 154 is disposed on the other end of the mounting board 158 between an elongated oval slot 232 extending lengthwise of the boards length. The set of switches 154 is adjustably mounted by means of a pair of upper and lower brackets 234. A switch actuator slide member 236 having a switch actuator member 238 projecting through oval slot 232 follows the expanding and contracting movements of the temperature sensing means 40. The switch actuator member 238 contacts switch lever 240 of switch 242 when the temperature responsive means is exposed to a certain predetermined high temperature, and similarly contacts switch lever 244 of switch 246 when the temperature sensor means is exposed to a certain low temperature condition.

The slide member 236 includes a laterally projecting follower member which abuts against the left end of the temperature sensor means 40, andthe slide member is urged towards the right, as viewed in FIG. 2, by a pair of springs 248 which are stretched between dog-ears 250 on the slide member and a pair of vertically spaced posts 252 extending horizontally from vertical insulating board 158. I

The input leads to the

electrical switches

220, 222, 242 and 246 are connected to the electrical terminals 230. Likewise, the electrical input leads 81 to the electrical heater assembly are connected to these terminals 230. The

terminal connectors

230 and 166 are also connected to electrical cables (not shown) that extend outwardly of the housing 22 through a pair of insulating grommets 264 mounted through two spaced openings in end plate 30 (See FIG.'2).

Referring to the schematic diagram of FIG. 16, there is shown a multizoned heating-cooling system which uses the above described end switches. The temperature sensor means 40 is responsive to the heat generated by heat resistance element 79 to axially reposition control rod 44. Control rod 44 is mechanically coupled to a hot deck-cold deck damper disposed within a duct 122 in the same manner as described with reference to FIG. 15, where the position of the control rod 44 and associated dampers is determined by the room thermostat 1.24.

The multizoned heating-cooling system of FIG. 15 is designed to maintain a hot deck and cold deck pair of temperatures which are proportional to the outside temperature. This outside temperature is sensed by an outside sensor 200 which provides one of the input signals to a pair of summing

amplifiers

202 and 204. The output of summing amplifier 202 is delivered to a stag ing device 206 and its variation adjust the set temperature of a refrigeration stage 208 to thereby control the temperature of cooling elements 210 located in the cold deck. Similarly, the output of summing amplifier 204 is fed to a staging device 214 and its variations adjust the temperature generated by heating stage 216 to thereby control the temperature of heating elements 218 located in the hot deck. A second input for the summing

amplifiers

202 and 204 is provided by a pair of

temperature sensor elements

220 and 222 located, respectively, in the cold and hot decks.

The closingof switches 222 and 246 of the temperature responsive actuator 20 provide two additional inputs to the summing amplifier 202. The purpose of these two signals is to provide additional cooling to a particular room or zone in response to a remote command from that particular zone. This remote command signal is provided by the closing of the switches 2 22, 246 upon the zone temperature reaching a value which occurs at the nearly full travel of the hot-cold damper control rod 44. The relative position of the

switches

222 and 246 with respect to the axial movement of the temperature sensor means 40 is adjusted so that one of the two switches closes first and then with a further small incremental movement of the temperature sensor means 40 the other switch will close to provide a second increment of cold deck set point change of the staging device 206.

Similarly the closing of

switches

220, 242 provide two additional inputs to summing amplifier 204. The relative position of

switches

220, 242 would likewise be adjusted so that one switch closes first and then a further small incremental contraction of temperature sensor means 40 would cause the other switch to close to provide two distinct hot deck set point changes.

While a preferred embodiment of the present invention has been shown and described, and particularly a specific embodiment of a temperature sensor means and heat control means employed therewith, it will be understood that the present invention contemplates other types of temperature sensor elements which serve to move a control-rod in response to heat generated by a heat control means. Accordingly, it will be obvious to those skilled in the art that changes and modifications of the described embodiment may be made without departing from the invention in its broader aspects.

We claim:

1. A temperature responsive actuator comprising a plurality of bimetal spherical washers disposed in a bellows-like arrangement, said washers arranged in pairs with their concave surfaces in opposing relation, a plurality of retainer means for pivotally supporting the outer peripheral edge of said washer pairs, a plurality of annular spacers rigidly supporting the inner peripheral edge of the two adjacent washers of adjacent washer pairs, frame means including a pair of upstanding wall members, one end of said bimetal washer arrangement secured to one of said wall members, a control rod axially disposed through said bimetal washer arrangement and slidably disposed through said wall members, fastening means for coupling said control rod with said other end of said bimetal washer arrangement and heat control means for supplying heat internally of said bimetal washer arrangement in response to a control signal from a remotely located temperature sensor.

2. A temperature responsive actuator as defined in claim 1, wherein said retainer means for pivotally supporting the outer peripheral edge of said washer pairs comprises an annular ring member having a pair of spaced annular grooves into which said outer peripheral edges are retained.

3. A temperature responsive actuator as defined in claim 1, wherein said heat control means comprises a heater assembly having an insulated tubular body disposed coaxially within the center said bimetal washer arrangement and having a heater element spirally wound along the outer cylindrical surface of said tubular body.

4. A temperature responsive actuator as defined in claim 3, wherein said heater assembly extends inwardly from said one end of said bimetal washer arrangement a distance substantially equal to the length of said bimetal washer assembly when in its contracted condition, and further comprising a heat conducting cylindrical member fastened to said other end of said bimetal washer arrangement and disposed within said center of i said bimetal washer arrangement toward said heater assembly, said heat conducting cylindrical member having an inside diameter larger than the outer cross sectional dimension of said heater assembly and having a sufficient length to telescope over a portion of said heater assembly to the extreme limits of expansion of said bimetal washer arrangement.

5. A temperature responsive actuator as defined in claim 1, further comprising a switch means for providing a remote command signal upon said bimetal washer arrangement expanding or contracting to a predetermined axial length.

6. A temperature responsive actuator as defined in claim 5, wherein said switch means comprises a pair of end switches disposed adjacent said bimetal washer arrangement in a spaced apart relation and switch actuator means for closing one of said switches when said bimetal washer arrangement expands to a predetermined first length to provide a first remote command signal and for closing the other of said switches when said bimetal washer arrangement contracts to a predetermined second length.

i 7. A temperature responsive actuator comprising a plurality of bimetal spherical washers disposed in a bellows-like arrangement, said washers arranged in pairs with their concave surfaces in opposing relation, a plurality of annular ring members pivotally supporting the outer peripheral edge of said washer pairs, a plurality of annular spacers rigidly supporting the inner peripheral edge of the two adjacent washers of adjacent washer pairs, a frame member having a base member and two upstanding end walls, one end of said bimetal washer arrangement secured to one of said end walls, a collar member closing the other end of said bimetal washer arrangement which together with said one end wall and said bimetal washer arrangement defines expandable and contractible chamber, control rod axially disposed through said bimetal washer arrangement and slidably disposed through openings in said end walls, fastening means for coupling said control rod with said other end of said bimetal washer arrangement, and heat control means for generating heat in said expandable and contractible chamber in response to a control signal from a remotely located thermostat.

8. A temperature responsive actuator as defined in claim 7, wherein said heat control means comprises a heater assembly having an insulated tubular body disposed coaxially within the center of said bimetal washer arrangement and having a heater element spirally wound along the outer cylindrical surface of said tubular body. I

9. A temperature responsive actuator as defined in claim 8, wherein said heater assembly extends inwardly from said one end of said bimetal washer arrangement a distance substantially equal to the length of said bimetal washer assembly when in its contracted condition, and further comprising a heat conducting cylindrical member fastened to said other end of said bimetal washer arrangement and disposed within said center of said bimetal washer arrangement toward said heater assembly, said heat conducting cyindrical member having an inside diameter larger than the outer cross sectional dimension of said heater assembly and having a sufficient length to telescope over a portion of said heater assembly to the extreme limits of expansion of said bimetal washer arrangement.

10. A temperature responsive actuator as defined in claim 7, further comprising a switch means for providing a remote command signal upon said bimetal washer arrangement expanding or contracting to a predetermined axial length.

II. A temperature responsive actuator as defined in claim 10, wherein said switch means comprises a pair of end switches disposed adjacent said bimetal washer arrangement in a spaced apart relation and switch actuator means for closing one of said switches when said bimetal washer arrangement expands to a predetermined first length to provide a first remote command signal and for closing the other of said switches when said bimetal washer arrangement contracts to a predetermined second length.

12. A temperature responsive actuator as defined in claim 11, wherein said switch means further comprises an insulated board mounted on said base wall transversely between said end walls and having an elongated slot extending lengthwise, said end switches mounted on said board at opposite ends of said slot with actuating levers in opposing relation, and wherein said switch actuator means comprises a slide member slidingly mounted on said board and having a follower member disposed to engage said other end of said bimetal washer arrangement, spring means for biasing said slide member to urge said follower member to abut against said other end of said bimetal washer, and a switch actuating member carried by said slide member and projecting through said elongated slot for making engagement with said actuating levers.

13. A temperature responsive actuator as defined in claim 10, wherein said switch means comprises two pairs of end switches disposed, each pair disposed adjacent said bimetal washer arrangement in a spaced apart relation, and switch actuator means for closing one switch of one pair when-said bimetal washer arrangement expands to a predetermined first length to provide a first remote command signal for closing one switch of the other pair when said bimetal washer arrangement expands a further incremental distance beyond said first length to provide a second remote command signal for closing the other switch of said one pair when said bimetal washer arrangement contracts to a predetermined second length to provide a third remote command signal, and for closing the other switch of the other pair when said bimetal washer arrangement contracts a further incremental distance beyond said second length.

Claims

4. A temperature responsive actuator as defined in claim 3, wherein said heater assembly extends inwardly from said one end of said bimetal washer arrangement a distance substantially equal to the length of said bimetal washer assembly when in its contracted condition, and further comprising a heat conducting cylindrical member fastened to said other end of said bimetal washer arrangement and disposed within said center of said bimetal washer arrangement toward said heater assembly, said heat conducting cylindrical member having an inside diameter larger than the outer cross sectional dimension of said heater assembly and having a sufficient length to telescope over a portion of said heater assembly to the extreme limits of expansion of said bimetal washer arrangement.

7. A temperature responsive actuator comprising a plurality of bimetal spherical washers disposed in a bellows-like arrangement, said washers arranged in pairs with their concave surfaces in opposing relation, a plurality of annular ring members pivotally supporting the outer peripheral edge of said washer pairs, a plurality of annular spacers rigidly supporting the inner peripheral edge of the two adjacent washers of adjacent washer pairs, a frame member having a base member and two upstanding end walls, one end of said bimetal washer arrangement secured to one of said end walls, a collar member closing the other end of said bimetal washer arrangement which together with said one end wall and said bimetal washer arrangement defines expandable and contractible chamber, control rod axially disposed through said bimetal washer arrangement and slidably disposed through openings in said end walls, fastening means fOr coupling said control rod with said other end of said bimetal washer arrangement, and heat control means for generating heat in said expandable and contractible chamber in response to a control signal from a remotely located thermostat.

8. A temperature responsive actuator as defined in claim 7, wherein said heat control means comprises a heater assembly having an insulated tubular body disposed coaxially within the center of said bimetal washer arrangement and having a heater element spirally wound along the outer cylindrical surface of said tubular body.

11. A temperature responsive actuator as defined in claim 10, wherein said switch means comprises a pair of end switches disposed adjacent said bimetal washer arrangement in a spaced apart relation and switch actuator means for closing one of said switches when said bimetal washer arrangement expands to a predetermined first length to provide a first remote command signal and for closing the other of said switches when said bimetal washer arrangement contracts to a predetermined second length.

13. A temperature responsive actuator as defined in claim 10, wherein said switch means comprises two pairs of end switches disposed, each pair disposed adjacent said bimetal washer arrangement in a spaced apart relation, and switch actuator means for closing one switch of one pair when said bimetal washer arrangement expands to a predetermined first length to provide a first remote command signal for closing one switch of the other pair when said bimetal washer arrangement expands a further incremental distance beyond said first length to provide a second remote command signal for closing the other switch of said one pair when said bimetal washer arrangement contracts to a predetermined second length to provide a third remote command signal, and for closing the other switch of the other pair when said bimetal washer arrangement contracts a further incremental distance beyond said second length.