CA1046365A - Condition responsive control device - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A condition responsive control device is disclosed for affecting operation of a choke control system in response to variable ambient and system temperatures, as well as the use of such a device in a system in which it is desired to adjust an operating parameter of the system in response to such tempera-tures. The device includes an ambient temperature sensing switch which remains de-energized in response to ambient temperatures below a first preselected temperature level and is energized in response to temperatures in excess of this level so as to trans-mit an electrical signal in response to energization. The device also includes a system temperature sensing switch which remains unactuated in response to system temperatures below a second preselected temperature level and is actuated in response to temperatures above this level so as to effect an operation parameter of the system. A self-regulating heating element is thermally coupled to the system temperature sensing switch and is adapted to generate heat at a substantially constant tempera-ture level in response to electrical energization thereof. The heating element is electrically coupled to the ambient tempera-ture sensing switch and is energized in response to the electrical signal to effect accelerated heating of the system temperature sensing switch to said second preselected temperature level.

Description

~046365 The present invention relates generaily to a condition responsive control device and more particularly ls directed to a device ior sensing ambient temperature as .
well as system temperature for affecting operation o~ a system - in response thereto. ~ -Numerous systems are presently utilized in which lt is desirable to control or adjust an operating parameter oi . the system in response to an internal condition of the system such as temperature, speed, etc. while similarly sensing an external parameter such as ambient temperature so as to achieve a desired mode oi operation oi the system. Particularly in the automotive field a great need has arisen in recent years in attempting to reduce exhaust pollutants to regulate the ratio :. .
oi iuel to air in the fuel-air mixture being supplied by thR
carburetor so as to achieve the largest ratio oi air to iuel ~hlch is possible, while permitting smooth running o~ the engine ~ithout da~aGe or stalling. Such a need has become particularly lmportant since conventional choke assemblies provided ior use ~th conventio~al internal combustion engines ior initially ~0 walntaining a higher ratio of iuel to air while the engine is , : In a cold condition and in particular when ambient tempe~atures ~re relatively low while increasing the ratio oi a~r to iuel in ;~ ~ . the mlxture as the engine approaches its normal operating t~perature have sufiered irom certain deiiciencies, and have not functloncd to suificiently reduce the level of undesired ~mpuritIes in the exhaust gas. Although various systems have .: . . . .

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been proposcd for controlling the choke operation for accomplishin~ improved operation in reducin~ exhaust pollu-tants certain problems continue to arise. For example,'in situations in which the ambient temperature is at a level above approximately 60F. it is desirable to deliver a fuel to air mixture to the engine which has a somewhat higher ratio o~ fuel to air than the engine requires when it has reached its normal operating temperature for only a very ' ' small time interval in comparison ~ith situations involving a lower ambient temperature. ~ouever, due to the ~elative lnability of the choke assembly to compensate ~or the increased ambient temperature as compared with a relatively cold ambient : tempèrature o~ perhaps 0F., conventionai automotive choke assemblies are somewhat incapable oi accomplishing this function in as short a period oi time as may be desirable due to the inherent time delay of the choking system so that the fuel to air ~ixture contains a hi~her ratio o~ ~uel to air for a ~anger period o~ time than is necessary and increas~ emission Or undesired materials ln the exhaust gas results. In order eoalleviate this problem certain proposals have'been made ~or hoating the temperature responsive mechanism o~ the choke ~ssombly but have been generally unsuccess~ul due to the intro- ' duction of additional complex mechanisms and systems. ~or oxample, it has been proposed to util'ize a resistance heater.
2S Houever, the introductlon o~ such an element requires additional . -8witchin~ mechanisms for'energizil~g and de-energizing the ' . . .
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~0~365 resistance heater. In addition, a resistance heater is often sensitive to variations in voltage, current, etc., as well as being affected by the adverse environmental situation in the engine compartment and improper system operation often results.
The present application is a division of ~anadian application Serial No. 145,921 filed June 28, 1972.
The invention of the parent application provides a condition responsive control device for affecting operation of a temperature dependent system in response to variable ambient temperature and system temperature comprising: an ambient temperature sensing switch means including a thermostat coupled to a source of electrical power and being adapted to shift from a rest state to an actuated state in response to a sensed temperature in excess of a first preselected temperature level and which remains de-energized in response to ambient tempera-tures below the first preselected level, a system temperature sensing switch means which remains de-energized in response to sensed system temperatures below a second preselected level and which 18 energized in response to temperatures above the second preselected level, the ~ystem da~

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~0~365 temperature ~ensing ~wltch belng adapted to affect 2n operatlng parameter of the system in response to energization thereof, aelectively energizable heating means thermally coupled to the system temperature sensing switch, the heating mean~
Including a self-regulatlng heatlng element adapted to generate heat at a substantially constant temperature in response to - electrlcal energization thereof and having a steeply-sloped posltive temperature coefficient of reslstance at temperatures above an anomaly temperature, the anomaly temperature being in excess of the second preselected temperature level, the heating element belng electrically couplable to the ambient temperature ~enslng switch and belng energized by an electrical s~gnal transmlttet in response to energization of the ambient tempera-ture senslng switch means ~o as to accelerate the heating of the system temperature sensing switch means to tbe second pre-selected temperature level in response to elevated ambient temperatures, the thermo~tat being connected to the self-regulating heating element only when it lts actuated state for energizlng the heatin8 element and comprisin~ a member formed of thermostat material having a plurality of metal laminae h-ving unequal coefficients-of thermal expansion, the member havlng a generally diac-shaped configuration and being adapted to teflect lnto an overcenter posltion ~n its actuated state to eatabllsh an electrical connection between the source of ~l-ctrical power and the heatin8 element, a conductive member coupled to the source of electrical power provided ad~acent one urface of tho thermostat member, the heatin8 element bein8 arrang-d adJacent an oppo~lte surface thereof, and the thermostat ~-~ber includlng a generally centrally located aperture, a movable contact member supported adJacent the one surfaco of th- thermostat membor and lncludlng a contact portlon accommodated withln the aperture and extending to the opposlte urface of the thermostat membor, the contact portion belng . ' ~1, .

, . . ~ .. - . . ,. : . . ; , , , , . , ,: . . : -~04~3~5 dapted to shift lts posltion with deflectlon of the thermostat member, and a ~tationary contact member supported intermediste the heating element and the contact portion, the stationary contact member bein8 in continuous electrical contact with the heatlng element ant in selective disengagement with the contact portion when the thermostat member is in a rest position and in engagement with the contact portion when the thermostat member is in its actuated state, thereby effecting electrical energization of the heating element in response to deflection of the thermostat member On the other hand the invention of the present applica-tion provides a temperature responsive device adapted for u~e in reducing pollutants in the exhaust gas emitted by an internal combustion engine powered by a combustible fuel-air mixture comprising a casing adapted to be csrried on the engine, the casing having a bottom and a side wall defining a generally cup-shaped casing chamber, having an aperture extending through the casing bottom, and having a flange inside the casing chamber upstanding from the casing bottom around the aperture, a fixedly mounted conductive contact member disposed within the aperture, an ambient temper-ture sensing switch compri~ing a thermostat member having a plurality of metal laminae having unequal co-fflclents of tbermal expansion carried ad~acent the apeTtureat one surface of the casing bottom in a positlon normally spaced from one end of the fisedly mounted conductive contact member and adapted to electrically engage the one end of tbe contact m-mber upon deflection of the thermostat member in response to the occurrence of a preeelected ambient temperature at the casing, ; means electrlcally connectlng the thermostat member to a source ' -- 4a -dapl~

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~0~365 o~ electrical power for selectively connecting the fixedly mounted contact member ~o the source of electrical power only upon the deflection of the thermostat member in response to the preselected ambient temperature as the casing, a thermally and electrically cond~ctlve metal plate secured to the casing agalnst the casing flsnge over the casing aperture to be electrically connected to electrical ground, an engine temperature sensing thermally respons-lve means mounted within the casing chamber to be thermally coupled to the engine for sensing the temperature thereof, the thermally respongive means comprising a member formed of thermostat material having a plurality of metal laminae having unequal coefficients of thermal expansion and being formed in a continuous co$1 having a plurality of convolution- including a coil origin fixedly secured ; to the plate and a coil terminus adaptet to move in response to an elevated temperature of the coil at the casing, the ter~inus being adapted to be coupled to a valve for ad~usting the ratio of the fuel-air mixture powering the engine, and a self-regulating ~ electrical heating element secured to one side of the plate to L, b- surrounted by the casing flange in electrical contact with an opposlte end of the fixedly mounted contact member and in thermal ~'` communication with the en8ine temperature sensing coil, the heating `~ element being adapted to generate heat at the casing at a sub-'~ ~tantially constsst temperature in response to electrical esergiza-' tlon thereof upon the deflection of the thermo~tat member and having a positive temperature coefficient of resistasce and a harply defined transitlon tempersture above which its resistance iscreases abruptly, whereby the deflection of the thermostat member in respoose to the occurrence of the preselected ambient temperature at the casing effects selected heating of the en8ine ~,` ` .
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~o~ s temperature sensing coll and selected movement of the coll terminus.
Varlous advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description and accompanying drawings wherein:
Pigure 1 is a perspective exploded view of a control device in accordance with the present invention;
Figure 2 is a vertical sectional view of the device of Pigure'l;

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~igure 3 is a iragmentary partially exploded perspective view partially cut-away of a portion oi a con-ventional lnternal combustion engine provided with a control , device ln accordance with the present invention; and S ~igure 4 is a partially diagrammatic electrical schematic circuit diagram illustrative o~ the function of a control device in accordance with the present invention. . -Referring generally to the drawings and initially to Figs. 1 and 2 a control device in accordance with the present invention is designated generally by the re~erence numeral 10. ~ery generally, the devlce 10 includes an ambient temperature switch means 12 which remains in an unactuated or de-energized state in response to ambient temperatures belo~
~ ~irBt pr~gelec~d t~ .pQr-~ A lc-~cl and ~;hich is e~r~
or actuated in response to a temperature level in excess o~
thls level. The ambient temperature switch means is adapted to be coupled to a source o~ electrical power (not shown) ~or transmltting an energizing electrical sigDal when lt is in an actuated condition. In addition, a system temperature switch means 14 ls provided adapted to be maintained in thermal communication with the system being controlled or adjusted.
~ho system temperature sensing s~itch means 14 remains de-~nergized or unactuated in response to sensed system tempcra-tures below a second preselected temperature level and i9 energi~ed or actuated in response to temperatures above this ' secoDd preselected temperature level so as to a~ect an .

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operating parameter o~ the system in response to energization.
~he device ~urther includes a selectively energizable self-regulating hcating element 16 thermally coupled to the system temper~ture sensing switch means 14 and adapted to generate heat at a substantially constant temperature in response to electrical energization thereof. The heating element 16 has a steeply sloped'positive temperature coefficient of resistance - at temperatures above an anomaly temperature in excess o~ the second preselected temperature level. The heating element is ~ coupled to the ambient temperature switch means 12 only when the ambient temperature switch means is in its actuated condi-~ , tion such that actuation o~ the ambient te~perature suitch 12 ; eiiects the energization oi the heating element thereby effect-ing accelerated heating of the system temperature switch means lS 14 in response to elevated ambient temperatures. , ' ~ore particularly, the ambient temperature sensing ,, switch means 12,preferably comprises a thermostat member, - ha~ing a plurality o~ metal laminae (as particularly shown in ~ Flg. 2), which is adapted to be maintained in continuous ,l 20 eiectrical contact with the source Or electrical power and , ' ~blch remains ln its unactuated state uhen the ambient tempera-ture ls belo- a iirst preselected temperature level but ~Ihich 1B actuated in response to ambient temperatures above this .
~j temperature level to eiiect the establishment oi a bridgi~
i 85 electrical contact betweeD the source oi electrical power and ' the h-atin~ element 16. As a result electricil signals are . . ~.

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transmitted to the heating element 16 to effect eleetrical energization thereof, thereby causing the application Or additional heating to the temperature sensin~ switch means 14.
The thermostat member 12 preferably comprises a generally dise-shaped thermostat member, which in the illustrated embodiment has an upper surface of a generally convex shape.
This upper surface is maintained in electrical communication with a eonductive plate 18 disposed in spaced relationsh~p with the upper sur~ace of the thermostat member 12 and main-tained in electrical communication therewith by a spring-like eontaet member 20 disposed in contact with and intermediate *he eonvex surface oi thermostat member 12 and the conductive plate 18. The eonductive plate further includes a projecting lug or terminal 21 adapted to be connected to a source o~ elec-~5 trieal power and, i~ desired, an insulating protective plate 22 ~ay be seeured above the conductive plate 18 by a plurality of serews 24 or the like. The thermostat member 12 includes a genorally eentrally loeated aperture 26 which is adapted to . .
aeeo~odate a depending member 28 of the spring eontaet 20.
? A ¢onduetive eontaet member 30 whieh may eomprise a eonduetive headed rivet, or the like, is disposed adjaeent - the opposite concave surface of the thermostat member 12 in axial registry with the aperture 26 and with dependin~ member 28 of the spring eontaet but in seleetive disengagement therewith, while the dise thermostat 12 remains in its unae-tuated condition. As shown, partieularly in ~ig. 2 the .
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1~46365 .
depending member 28 extends throu6h the aperture 2~ and .remains spaced from the contact member 30, while the ther-mostat member 12 remalns in its unactuated condition but is adapted to eng~ge the contact member 30, when the th~rmostat S membcr 12 dei'lects into its overcenter position (shown in phantom) in response to a sensed ambient temperature level in excess of the first preselected temperature level, thereby establishing electrical communication between the contact ~ember 30 and the conductive plate 18.
The thermostat member 12, as we,ll as the conductive plate 18 and the spring contact 20 are all supported within , . an upwardly pro~ecting housing 32 on a sur~ace Or a support casing 34. ~he casing 34 also includes a generally centrally - located aperture 36 within the portion thereof surrounded by , , 15 the housing 32, which accommodates the conductive contact ~ember 30. The contact member 30 extends through this aperture 36 with one end thereof being secured against the sur~ace oi the casing as shown in selective disengagement with the depending member 28 oi the spring contact 20 and its opposite end extending through the inner sur~ace oi' the casing ~here-it contacts and is secured against another conductive contact member 38 which is also preierably fabricated o~ a._ ~pring~ e materlal. The contact member 38 includes an aperture 39 ior receiving the member 30~ which is preferably 2S crimped thereagainst to maintain the member 38 in position, . . . . .

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The opposite end of contact member 38 bears against a contact sur~ace o~ the heating element 16 so that electrical contact 1B maintained between heating element 16 and the contact member 30, Thus, upon deflection or actuation of thermostat - .
member 12 ~nto engagement with the contact member 30 bridging electrical contact is established betw~een the conductive p?ate 18 and the contact suriace of the heating element 16. , The heating element 16 preferably comprises a self-regulating positive temperature coefiicient of resistance thermistor having a steeply-sloped positive temperature ; eoeiiicient oi resistance at temperatures above an anomaly or transitlon temperature, whereby application oi electrical energization thereto causes the heating element to seli-heat and reach ~ pradetermined temperature level wh~ch remains sub~tantially constant responsive, to continuous electrical onergization thereoi as a'result Or the substantial increase ln resistance of the heating element at this bemperature level.
Sueh an element is qulte advantageous since it heats up to thl~ temperature level relatively rapidly and then retains ~ :' ao that temperature in responsa to contlnued energlzation. A
. partleularly advantageous heating element comprlses a eeramie . . .
~a~er eomprising semieondueting barium titanate,' sueh as Ea 997La 003Tio3. As shown the heating element 16 is preier-ably aounted on a thermally eonduetive heat-sink member 40 ~S ~hiCh is ln eleetrieal contaet with a contaet suriace thereoi . : o~poslte to the contact suriace whiCh contacts the sprlng ~ . , - , ; , , - :
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104~3~5 - ~-CODtaCt member 38. The hcat sink member 40 is preferably fabricated of a material having a relatively high thermal conductivity and a substantial thermal inertia, such as zinc, and, as shown, includes a pair of mounting studs 42 which are adaptcd to be received within accommodating aper-tures 44 in the casing 34 so as t~ fa~ilitate mounting oi the heating element 16 and the heat-sink 40 within the casing.
In addition, in order to ~acilitate connection o~ the device a semi-circular conductive ground strap member 46 is secured to the upper sur~ace of the casing 34 and supported on the ri~ thereoi. This member includes a plurality of apertures 48 in registry with the apertures 44 on the casing for receivin~
the studs 42 therethrough so as to facilitate maintenance o~ the - heat sink member ard a contact surface o~ the heating element 16 at ground potential, while the other contact sur~ace is connectable to the source oi electrical power. In addition, a rlgid member 50 depends ~rom the opposite sur~ace of the heat slnk member 40 and includes a ælot 52 therein for mounting the systcm temperature sensing switch means 14 in thermal .
co~unication with the heating element 16; Thus~ the heat generated by the heating element 16 is efficiently transierred to the system temperature sensin~ s~Yitch 1~ and the substantial thormal lnertia of the heat-sin~ member 40 causes the system temperature switch 14 to retain its elevated temperature level ior a substantial period o~ time subsequent to removal o~
heatinG so as to ~aintain the system tempcrature sYitch means 1~ at an elevated temperature and hence in an actuated condition ''' ` 10 . , - , .
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! . ,, ' , ' . ' . , ~ . ' ' . ~ . ' , , ' ` ' , ', , . , , ', ' " -' ' ' `,' ' ' ' ' ;-` " '. ' ` ~ i'.'. '.' ' ' ~046365 ~ubsequent t~ a decrease in system tcmperature which is advantageous in lnstances in which the system is shut down and cools, but in which it is desired that the system temperature sensing switch 14 remain in an actuated condition 80 as to ei'fect the desired adjustment of an operating para- :
~eter oi' the system in a minimal time interval.
The system temperature sensing switch means 14 prei~erably comprises a thermally actuatable movable member, such as a member i'ormed oi' thermostat material having a plur-ality oi' metal laminae havin~ di~i'erent coel'i'icients oi thermal .
expansion. In this connection the system temperature sensing switch means 14 prei'erably comprises a member in the i'orm o~' . a ~piral of at least one continuous convolution and is illus-- trated haYing a plurality of convolutions with its origin 54 lS . being rigidly mounted within the slot 52 so as.to restrain . movement thereoi', while its terminus 56 is adapted to be mechani-.. oally lin~ed to a valve assembly or the li~e, as will be ~ubQequently explained, and is permitted to mo~e relative to th0 orl~ln 54 in response to an elevated sensed temperature 1 20 level. Thus, the device 10 is adapted to be mounted such that ~ the thermostat member 14 is in thermal communication with the i . system the parameter oi' ~hich is being adjusted or controlled, and ~ince the reaction ol' the thermostat member 14 in certain lnstances may be insu~iciently rapid to afi'ect operation in a 25 . . desired time lnterval, such as when ambient temperature is ~bove a certain level and operation should be more rapidly -~ .
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1~)4~3~5 aiiected, the ambient temperature sensing thermostat 12 deilects thereby effecting energization oi the heatin~ element 16, which applies additional heating to the thermostat member 14, thereby causing it to operate at a substantially accelerated rate, whereby the relative movement of its terminus 56 occurs at an accelerated rate in order to affect system operation in the desired manner Referring now to Fig. 3 one oi the particularly advantageous uses o$ the device lO in accordance with the present invention is illustrated. ~ore particularly, the - dsvice is shown employed in conjunction with a typical conven-tional internal combustion engine for adjusting the ratio of iuel to air in the fuel-air mixture being delivered by the . , . - , .
carburetor ior adjustin~ the fuel-air mlxture valve of the carburetor in response to varying ambient and engine temperature conditions. In accordance with the present inventio~b a solu-tlon is provided ior the problem o~ reducing the undesired l~purities or pollutants in the exhaust gas of such an engine particularly ln situations ln which the engine is in its warm-up .
phase starting irom a cold condition. In such situaions an , . . ~ . . .
unacceptably hi~h level oi pollutant emission is known to occur du~ to thc rich i'uel to air ratio required. In this connection lt i8 normally desirable to provide a cho~ing action, when 6tar.t~ng a cold en~ine, by virtue oi vhich the ratio o~ ~uel to air ls increased ln order to prevent stalling and ~is~ire .
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10~lj365 .
oi' the engine. However, it is desirablc to reduce the ratio oi fuel to air by increasing the relative amount of air in the mixture as ~uickly as possible in order to prevent the emission of undésired impurities in the exhaust gas. Conven-tional choke assemblies have been somewhat unable to cope Yith this situation in view of the fact that a substantial time period is required before the sensed engine temperature causes the choke assembly to lean-out the fuel mixture to the desired ratio, This is particularly true in situations in which the ambient temperature air which is being supplied to the engine is o~ a temperature above approximately 60F. in which the choking action for providing a richer fuel mixture is only required for a relatively brief time interval. In accord-ance with the present invention the device 10 is adapted to lS sense ambient air temperature, as well as engine temperature, 80 as to rapidly increase the ratio of air to fuel in the fuel-air mixture being delivered by the carburetor and is particularly advantageous in reducing undesired exhaust gas lmpur~ties in situations in which the ambient temperature air ls above a preselected temperature level, when the engine does not require a rich $uel to air mixture for more than a .
very brief time interval.
~Sore particul~rly, a portion of a conventional lnternal en~ine assembly indicated generally by the reference numeral 60 is sho~Yn includin~ a carburetor 62 mounted thereon, the carburetor having a fuel~air mixture valve 64 conventionally ~ , .. . .
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referred to as the butterily valve. As shown an air cleaner 66 is mounted above the carburetor 62 and 1ncludes a fresh air inlet port 68 for supplying air to the carburetor, while the butterily valve 64 regulates or adjusts the amount of iresh 5 alr being supplied to the carburetor so as to ad~ust the fuel- -alr mixture bcing delivered by the carburetor. The device 10 1~ illustrated mouoted on the engine 60 such that the engine temperature sensing thermostat 14 is in thermal communication ~lth the engine In this regard a mounting 70 is provided ad~acent the carburetor 62 as shown ior accommodating the device 10. An air hose 72 is connected between the mounting and tbe interior of the engine block 60 ior delivering heated alr circulating within the engine to the mounting 70 and hence to the engine temperature sensing thermostat 14 such that the lS te~perature of internal engine gases may be sensed by the englne temperature sensing thermostat 14 which ls secured to -the mountlng 70. In addition, a vacuum ga~ket 74 is preferably provided to facilitate mountlng oi the device 10. As shown, a rotatably ~ounted member 76 extend~ through the mounting 70 and ~0 ~ncludos a slotted end 78 as shown adapted to recelve the t-rmlnu~ 56 o~ the thermostat member 14 thereln. The rotatably aountcd member 76 is connected to a plvotally mounted plate 80 by a linkiDE shait 82, the plate 80 in turn being connected to the butterily valve 64 ior eiiecting plvotal movement thereoi . ~5 o ~8 to e~iect opening and closlng of the valve 64, thereby . .
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: . -lQ46365 controllin~ the ratio oi air to $uel in the fuel-air mixture being delivered by the carburetor 62. It may be seen that movement Or the tcrminus 56 oi the thermostat member 14 in response to temperature changes efiects rotation oi the member 7G and hence eifects pivotal movement of the pivotally mounted plate 80 and opening and closing of the butterfly valve 64.
Thus, during operation ~hen the engine is in a relatively cold ætate and is initially started the thermostat member 14 i9 in its contracted or unactuated state and the rotatably mounted shaft 76 maintains the butterfly valve in a closed position so that a relatively rich fuel-air mixture is delivered. However, as engine temperature increases this lncreased temperature is sensed by the thermostat member 14 and the terminus 56 moveæ relative to the origin efiec;ing rotation oi' member 76 and hence opening oi the butter$1y valve 64. .In situations in ~hich the ambient temperature air is above a pre~elected temperature level and it is deslrible to ei$ect aore rapid actuatlon oi the thermostat member 14 and associated movoment 56 o$ the terminus thereo$ to e$fect opening Or the ~0 .buttor~ly valve 64 at a more rapld rate, in accordance with the present lnventlon the ambient temperature sensing dlsc thermostat . 12 doilects into its over-center position and e$$ects energiza-.tlon oi the seli-regulatlng heatlng element 16, ~hlch e$$ect8 .
: accelerated heating oi the the~mostat member 14 and thereby ~S causes actuatlon thereo~ and movement o$ the termlnus S6 to . :
ei~ect opening o~ the butter1~ valve 64 at a more rapid rate.
~:~` . . Thu~, in situations in ~hich the tempcrature oi' the a~bient air .
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104~365 ls such that the engine need not run on a rich fuel to air mixture for a prolon~ed period of time the present invention causes leaning-out of the ~uel-air mixture at an accelerated rate thereby reducing exhaust gas pollutants. Furthermore, the accelerated heating of the thermostat member 14 which is provided enables tlle thermostat member 14 to relatively closely track or analo~ue the internal engine gas temperature and respond in accordance with the level of.this temperature.
The ele~trical function of the de~ice 10 is parti-10 cular'y illustrated in a simpl.ified manner in Figure-4. Ilore particularly~ in Figure 4 a power supply 84 is shown ~hich may be generally representative of the automobile battery or alter- . :
nator whlch is connected via a switch 86 which may be generally representative of the automobile ignition switch.through a thermostat switch 88 which may be generally representative of the disc thermostat member 12 and to a thermistor element 90 -whlch may be generally represent~tive of the heating element 16. In addition, a member 92 is shown thermally coupled to the thermistor 90 and may be generally representative of the .ther~
~ostat member l4 whlch receives heat from the heating element 86 in response to energiz.ation thereo$. Thus, in operation on closure of a switch 8G the thermostat 88 is energized and if the ambient temperature is above a preselected temperature level is closed thereby su~plying electrical power to the thermistor 90 which in turn begins to sel~-heat and e~fects .
heating of the thermostat 92 so as to effect accelerated . . oper t~on thereo~, . - - .

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~04~365 Thus, a unique tcmperature responsive control device which is responsive to both ambient and systcm temperature conditions has been disclosed, as well as the use oi such a device in a particularly advantageous manner for controlling an operatin~ p~rameter of a particular system such as a conventional internal combustion engine.
Various changes and modifications in th.e above- -described device will be readily apparent to those s~illed ln the art and any of such changes or modifications are deemed to be within the spirit and scope of the present invention a8 set rorth in the appended claims.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1 A temperature responsive device adapted for use in reducing pollutants in the exhaust gas emitted by an internal combustion engine powered by a combustible fuel-air mixture comprising:
a casing adapted to be carried on the engine, said casing having a bottom and a side wall defining a generally cup-shaped casing chamber, having an aperture extending through the casing bottom, and having a flange inside the casing chamber upstanding from the casing bottom around said aperture, a fixedly mounted conductive contact member disposed within said aperture, an ambient temperature sensing switch comprising a thermostat member having a plurality of metal laminae having unequal coefficients of thermal expansion carried adjacent said aperture at one surface of said casing bottom in a position normally spaced from one end of said fixedly mounted conductive contact member and adapted to electrically engage said one end of the contact member upon deflection of the thermostat member in response to the occurrence of a preselected ambient temperature at said casing, means electrically connecting said thermostat member to a source of electrical power for selectively connecting said fixedly mounted contact member so said source of electrical power only upon said deflection of said thermostat member in response to said preselected ambient temperature as said casing, a thermally and electrically conductive metal plate secured to the casing against said casing flange over said casing aperture to be electrically connected to electrical ground, an engine temperature sensing thermally responsive means mounted within said casing chamber to be thermally coupled to the engine for sensing the temperature thereof, said thermally responsive means comprising a member formed of thermostat material having a plurality of metal laminae having unequal coefficients of thermal expansion and being formed in a continuous coil having a plurality of convolutions including a coil origin fixedly secured to said plate and a coil terminus adapted to move in response to an elevated temperature of said coil at said casing, said terminus being adapted to be coupled to a valve for adjusting the ratio of the fuel-air mixture powering said engine, and a self-regulating electrical heating element secured to one side of said plate to be surrounded by said casing flange in electrical contact with an opposite end of said fixedly mounted contact member and in thermal communication with said engine temperature sensing coil, said heating element being adapted to generate heat at said casing at a substantially constant temperature in response to electrical energization thereof upon said deflection of said thermostat member and having a positive temperature coefficient of resistance and a sharply defined transition temperature above which its resistance increases abruptly, whereby said deflection of said thermostat member in response to the occurrence of said pre-selected ambient temperature at said casing effects selected heating of said engine temperature sensing coil and selected movement of said coil terminus.