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E3, i194@ R. w. JENSEN TEMPERATURE AND PRESSURE CONTRO'L Filed Jan. 21, .1944 - Zßœßäì l k3 Sheets-61h59@ l É d? i' f: W E3 ßrwentof: @www Mdm/fm, Away@ 23s ma R. W. JENSEN _ ¿ma TEMPERATURE AND PRESSURE CONTROL Filed Jam 2l, 1944 3 Sheets-Sheet 2V Aug@ E3, w46@ R w JENSEN ' TEMPERATURE AND PRESSURE CONTROL 'Filed Jan. 21, 1944 , s sheets-sheet s 2,495,831 Patented Aug. 13, 1946 UNITED STATES PATENT j OFFICE p 2,405,831 TEMPERATURE AND PRESSURE CONTROL Raymond W. Jensen, Los Angeles, Calif., assignor to The Garrett Corporation, Airesearch Manu facturing Company division, Los Angeles, Calif., a corporation of California ’ ‘ ’ Application January 21, 1944, serial No. 519,159 11 Claims. 1 This _invention relates generally to oil cooling systems for internal combustion engines and to controls for regulating the flow and> temperature of oil from the cooler to the internal combustion engine within a range most satisfactory for eii'i cient operation and lubrication of the engine, es pecially of the type used for aircraft. Pressure lubricating systems for internal com bustion engines are provided with heat exchang ing means for regulating the heat of the lubricat ing oil and maintaining it within a proper and ef ñcient heat range. The heat exchanger is pro vided with a bypass passage through which the oil from the engine may circumvent the heat ex changer when for any reason the oil is prevented from passing through the cooling system. Ther mostatic valve means are often employed to con trol the ñowïof oil through the bypass passage. When such a thermostatic valve means is em (o1. 23e-s4) 2 I a device in which the control means for the valve may be adjustably regulated to adapt the same to varying conditions and to increase the sensi tivity of the same for the important purpose of extending the operating range and of making unnecessary a replacement or substitution of the control means where changing circumstances are encountered. Further objects and advantages of the invention will be brought out in the following part o1’ the speciñcation. y k „ Referring to the drawings which are for illus trative purposes only, Y Fig. 1 is a vertical sectional View showing a control fitting embodying the invention and a portion of a-cooler on which it may be mounted. Fig. 2 is a horizontal sectional view taken as> indicated by the line 2--2 of Fig. 1. Fig. 3 is a vertical sectioñ taken as indicated ployed, the cooled oil from the heat exchanger and uncooled oil from the bypass passage now past the valve` means, the operation of which is controlled by the temperature of the oil. When by the line 3-3 of Fig. 2. a pressure build-up occurs in the bypass passage, line 5-5 of Fig. 1. Fig. 4 is a vertical section taken as indicated by the line 4_4 of Fig. 3. Fig. 5 is a view mostly in section taken on the y , owing- to any'condition which impedes the free 25 Fig. 6 is an elevational view of a modified form flow of oil through the cooler, the valve is un of the invention. seated'to relieve the pressure, and held unseated until the valve is influenced to seat by the Aheat of the oil when the condition of impedance in the Fig. 7 is a section taken on the line 'I-'I of Fig. 6. i v Fig. 8 is a section taken on the line 8_8 of heat 'exchanger is corrected. A type of valve 30 Fig. 7. commonly used in lubricating systems of the class To the heat exchanger I0, which is illustrative mentioned'is known asv “sylphon valve,” which of one form or type of cooler in which the valve includes in its structure a bellows which forms arrangement herein described may be used, is a sealed expandable pressure chamber, which Yis connected a fitting I I to which is secured a, con subject to leakage and breakage ,and has a lim.. trol ñtting or housing I2, which is formed with ited operating range. v ` The present invention relates'to a valve struc ture for accomplishing temperature and pressure ‘ an inlet chamber I3 to receive the oil from the engine. The chamber I3 of the housing I2 is formed with a, port'opening I4, which registers regulation which' eliminates the use ofbellows with an opening I5 in the ñtting I‘I, providing a and hence obviates any possibility of failure 40 passageway for thehot oil from the engine to the thereof. ' ’ It’ is' an object of ‘the invention to provide a Y Iiuid'cooling system combined'with temperature and pressure control in which the possibilitylof failure of operation of the control is eliminated or reduced to'a minimum. ' ’ It is'also an objectof the invention to provide a simple, efficient, and compact flow of oil and heat exchangeriû, which, in the instance shown, is comprised of a core I6 of spaced tubes I6’ with means >for battling the circuit of oil therethrough, anda muff or enveloping jacket Il. Entry of the oil to the core I6 from the jacket or muff'is af forded by `anopening I8. y The aforementioned port or opening I5 is in direct communication with said muff or jacket I1, through a port I9 in temperature control which is light and susceptible the fitting II as shown-in Fig. 5. The port open to complete interchangeability with other valves 50 ing Il in the chamber I3, under normal condi or- control means employed- in similar capacities. A further object` of the inventionv is to provide a, control means having a greater operating range than valves similarly employed. ` A furtherobject of the invention is to provide ‘ tions, is open, but under extraordinary condi tions, as, for instance, in case of sudden pressure build-up of the oil, it is arranged to be closed to cause a relief of the pressure by bypassing it from said chamber I3 'through a bypass I9' into a valve 2,405,831 3 chamber 20, from which it travels through an outlet 2| from said chamber 20 to the engine, directly or indirectly. For effecting this relief from sudden pressure of the oil, a double valve 22 is provided in the chamber I3, and comprises a valve member 23 on one end of a stem 24 and a cylindrical »valvez25‘iat the -other end thereof." The ~ cylindrical Valve 25‘is held normally seated'on itsu seat 25 by a compression spring 21 disposed in the cylindrical hollow 28 of said valve 25 and con-i tained Within a chamber 29 vin-*saldwñtting ¿12, said chamber being provided With a cap 3D against 4 tively thereto and therewith. This piston 40 is connected by rods or posts 4I with a supporting slide member 42 which is slidably disposed within a cylinder of a cap 43 secured to said housing I2. A spring 44, positioned in the cylinder of the cap 43 exerts a pressure upon said slide member 42 tofhold'thefsame lagainst .a seat: 45 in-.theîcap 43 and‘to hold the associatedelements` of the valve structure in set position. As stated, the valve 39 is‘mounted on the piston 40. It has independent movement-'relativelythereto and such independ ent movement is effected by a thermal responsive which the compression of saiddspringL-Z'Ioccurs; means;¿sucl-rl asaafbi-'metallic coil 46, connected The seat 26 for said valve 25'isxima 'port-‘or open ing 3| in said chamber 29 and Whenithe valve- 25”.’ is unseated, said port establishes communication between the chamber I3 and '.th’ecbypass ,chamberi at‘its outer’endto the end of links 4l which are pivotallyl mounted‘j'in arms 48 of the valve 39. 'The opposite ends of said links 41 are pivotally connected to‘linklmembers 49 which are secured to> said.. piston 40. The inner end of the b1 I9', as shown in Figs. 1 and 2. The cylindrical ._ valve 25 is provided with. guide members 32,"extending beyond the face thereof, and these guide metallic' coil 4B is secured to a bar or other mem ber 59, which is fixedly mounted on the rods 4I. mem-bers -`cooperate- ~Withl the cylindrical: portion . off-the valve and-thelopeninglSI»tomaintain the sa'me; and its# companion f «valve A»23' »l in f , position. The thermostatic runit C orl 2 coilf» -4 6 ’ Y responds ~to the Viniluence 4of hot land~coldïoil~or other» Iiluid-ß and, moving'jn“ either one Lor'fanother“direetionç carries >with it' the valve 39 independently:off-the»When;Y for any reason;- af-pressureldevelops inthe > chamber I3 which'Y is »inexcess of .the pressure re- » 25 mount"thereof 'ori piston 40e-that' is,` independ-'e sisted is' lifted-- by i against said spr-ing ^ the»-2tension' 1;» the» cylindrical of » saidilspring valvef.1221"?` from its seat 26, while, concurrently, th’e~valv’e«23lA at»the«other»end¢ofethe»stem 24 ¿isseated inf-the ently "of the ' piston 40'1‘iand = 'its-*asseciated-.fpartsf which in association'with Athe-valve 39d' constitute.:V a pressure'responsive-means: Inforderto use-all of- the ,power 1 developed L fromvthe» »use--of- ’af-bl* port or opening-I4’.i Tlfi-isaelevati‘on-oirthe double »09 valve 22 opens communication betweenlthe:cham»l - metal; it is highlyimportant that'thefvalve ywhich' is Ainfluenced by‘such'bi-meta-l ‘ibex'balancedùthat' ber»4 I3 'andthe-bypassepassage :l 9! ,' and «thus-'re lieves the pressure, in consequencewvl'iereoff thev valves- 23iandy 25' underH the urge-of thespring 21 return to `normal position;~ as» shown .in- Fig. 1. Thehousing. I2 ~is-formed A'Withï-a `bypass cham-. is,zthat. pressures 'be-‘equal Von -alll~`sides~ or ‘parts ber 33l-which- has ‘= an' lopening-'orv` port 33 'L- andY a of the valve;A For'thisï-purposœthe piston'lllrh’as the' same ‘diameter fas the-«valve‘seat- 5 I~,» andthe innerdiameter of >the'valve 39 is nalso of- theI samei diameter.V The‘va-lve member 39 -is cylindrical? shown, and'is‘ffo‘rmeclîwithA a~ central 4lopening; 52‘» which isdiametricallyssmaller thanthefdiametri-L through. This `bypass chamben-33`f is essentially cal ‘extent" or“ the ‘inner-"Wal'lí‘orrface vof the Yvalve a pressure chamber, as explained¢hereinaiterî~fand 39;:and' with4 an`annular internalfshoulderfüï communicates with a-bypass ~-passage 35 :insaid ñtting II, this bypass passage~35 >lbeing-fin corn'.-N Which.`> cooperates `~with' ' thecaforementioned" pis: munication» Withlthe »muff f I'Iî andi arranged -`to cause the oil to circumvent the-heat exchanger rection, to-wit:` . away from its 'seatiâlg ton 4 Il; to.limit"the >movement- 4thereof‘ìin one ïdi’-The-ex# terior 'diameter' of the ‘,valve greater than-that:~ of' the, seat“‘5l',gand",the end ‘thereof “is tapered. and rformedivith a spherical face Y54, which fa'- |021 When.- for~any reason; the»\circuitf-ofßoil through the core I6 of the heat exchangerilßí’ is.4 obstructed.' »the oil travels through- orearoundrone area of the muri and, being prevented from-pass The piston'.4ll“'is.„also provided with‘aspherical ing throu'ghetl’ieppeningflß »tothe core` lëfcon periphery 40’ì'to enablathe valve 39‘to rotate and; tinues its‘travel through the muflî I'I, and even» seatïitselïifîit‘ is' not'on center. Y The ,slide _mem cilitates, itsA seating under“V adverse. conditions. tuallyeenters `the bypass chambere33; - throughV the b‘er, 42‘hasvan opening_„55"to provide fojr ,a balance bypass `pa-ssageâ 5 ing Aor lport 33L~inathe housing» I 2 .'-~ The »circuit of ofjfpressure . so th`at`any increase „in .pressure ,oc-_ casioned7 byanyA failure , in_th‘e`- cooler or.. heat 'ex the~oil «is vindicated by'A arrowed linesein Fig;V 1, A as «is A changerwilLbe exerted Íagainst‘thepiston 4Il‘and also the travel ofÃ oil throughltheeoreof the-heat» thus move the valve 391mm> it'sí,seat,î..regardless theï‘hoi-ising~ "I I ‘andthe open For purposes or' description;- said Y»chamber 33» of the pressure at _which the.spring ¿44' set.. Whenan >impedance .or restriction, to„the.,f1ow. may-‘be consideredl a-~--byp2iSS.l Alchamberì 2û~of~ thel *housing` I2- receivesecooledoil Vfromf-the- heat of 'Íoilj is‘roiîëred ¿by the ,heat " exchanger .0n forA exchanger.- v ~ exchanger`v I0«'through‘»a aportfßSv/hich is-provided Withwthe check- `-valve»3Iì-’~. The oil travels »from said*l chamber ~-I Sblzlru‘ougli'`l` theeoutletv port v2 I; for return~by-ganydesired 'course-'to theaengine: ln‘this `»ch'am-ber12 (luis - arranged »a thermostati other reasons,- a pressure „builds „11min the bypass chamber 33 beyond'a determined limit,‘andiab'0ve„ such limit the springg‘lß will be compressed; thus’ causingthe -.entire .valve y_structure gto .be .,moved. from 1 itsseat 5 I1 and .relieving pressure, .from the heat exchanger. .. cally controlledyvalve structure; generally indi- 65 cated- by-- 31,1 for controlling=the~flow lof uncooled In" the unseated ` position _ ot fthe ,valve .39;1tlie iluid „pressure ~, in . the ,bypassrcliamber ,3321s. bal-' oil through~the~ openingfSß,A which is a communi ancedfagainst. the ,piston 4B .îandjunder this .con eating`-port~-between~the bypass chamberßß and dition,A ‘the bi-metallic .thermostaticr coilI.4Ii,'.Í,be-. ingjníluenced- by, the. .,h‘eat of „the .oil to expand. easilyäopferates the valve member,39"to seating thet chamberiû. ` Thieçvalvev ‘structureß‘l` com prises apressure’responsive unitjanda thermoà statically' operated valve; Vas hereinafter described. The valve structure 3'I'îhas~a valve member adapted to engage theY seat surrounding, theopen ing 38 ’for closingthis opening. `‘The valve mem’ b‘er 39 ‘ismounted upon'a piston'f48 ‘to'move'rela 75 position: Reduced oil temperature will cause the thermostat `to contract and ‘thereby to-‘open the valve; In thefopen‘ position' of -the‘ valve',-- the thermostat will be influenced«bythe-temperature of‘the' oil‘fiowing through‘th‘e chamber' 33fwhich amasar ls uncooled, and the oil passing into the valve chamber 3U, which is cooled, and obviously the provided'with'perforations 68.- When this keyl or lever 66 isV moved in a circular plane in either one valve 39 will remain open until the desirable .op direction or another, the tension of the coil 58 erating temperature of the oil is reached, at which time the valve will seat and cause all of the oil to iiow through the heat exchanger It to and through the valve chamber 2D. ' The invention as herein described provides a through the medium ofthe shaft S4 to which the dead end thereof is connected, may be regulated in accordance with the range required to operate the valve. It is obvious, therefore, that this regu lationis of considerable importance in a device device which is light in Weight, is interchange of this type to accommodate the action of the >bi able with the “sylphon” valve now used, elimi- 10 metallic coil to differing conditions, obviating nates the use of bellows and hence obviates the thereby the need of substitutions for this purpose possibility of the failure of such bellows by leak and the labor incident thereupon. ' ' age or breakage, has a greater operating range ' . When the lever or key B6 has been manipulated ‘and requires no threaded parts. ' to obtain the desired degree of tension of the coil, it is secured in position of adjustment by a locking A variation of the form of the invention, with 'out alteration of the sense of the disclosure here tofore made, is illustrated in the form of embodi vment shown in Figs. 6, '7, and 8, wherein like nu merals of reference indicate like parts in all of the views in the drawings. ' - -The valve structure 3i has a valve member 3Q adapted to engage the seat surrounding the open ing 38 for closing this opening. The valve mem ber 39 is mounted upon a piston @il to move rel atively thereto'and therewith as has been point ed out. This piston 43 is connected by bars 5v'ì -with a supporting slide member ¿2 which `is slid-_ -ably disposed Within a cylinder of a cap d3 se cured to said housing l2. The bars 56 are con nected to the piston 40 and the piston member v42 by any desired means, such as screws 5l, bolts, or welds. As stated, the valve 39 has independ ent movement relatively to the piston 55 and -suchindependent movement i5 effected by a thermally responsive element, such as a bi-metallic -'coil 58. The outer or free end of said coil 58 is secured to a pin 59 which is carried in the ends -of a pair of links 65. The other ends of said links 6U are pivotally connected to extensions 6i which lare provided on said ñat bars 55 and project therefrom at substantially right angles to the longitudinal axis of said bars. The intermediate V'or substantially the central portion of said links are'pivotally connected to the ends of arms 52 which are integral or associated with the valve -39 in a desirable manner. 'I‘he dead end 53 of means, such as a pin screw or bolt 69 carried in a lug 'iii on one of said ñat bars 5S, whichpin or screw 6E! is arranged to fit into or pass through one of the perforations 68 in the arcuate _flange 61; Although I have shown but one form of my 20 invention, it will be understood that _various changes and modifications may bemade without departingy from the Vspirit and scope of the in vention, and that the invention should becon. strued in accordance with thespirit and scope of the appended claims. . I claim as my invention: 1 l. A combined pressure andtemperature conf trolled valve'ìfor controlling the iloW of a Viscous fluid through a bypass port of a heat exchanger having a normal heat exchange flow path, and a bypass, including said port, for circumventing said normal iiow path, comprising: an annular valve element adapted to seat with reference to said port, a piston within said valve element and cooperating therewith to form a closure for said port, a temperature responsive connection be tween said piston and valve element `for moving the latter with reference to the piston, and yield 40 ing meansurging the piston toa predetermined position, said piston being movable against the force of said yielding means by pressure in said bypass and being adapted, when it thus moves, to operate said Valve element, through said con nection, to relieve said pressure. , ` 2. lA combined pressure and .temperature con >>the bi-metallic coil 58 is secured to a shaft 54 trolled valve for controlling the flow of a viscous which extends through said flat bars 55 and is f' yfluid through a bypass port of a heat exchanger mounted for rotation therein, the purpose of this having a normal heat exchange flow path, a valve being set out presently. _ The structure as thus defined provides a valve >which is movable relatively to the stationary pis »ton 4B by the bi-metallic coil, the expansive and `contractive effort of which is translated to the ‘end thereof, which connects with the free ends 0f the links 60. Since' the links are pivotally at ‘taohed at the other ends thereof to the exten sions 6| of the ñat bars 56, they are moved about chamber communicating with said port, and a by-. pass, including said port, for circumventing said normal viiow path, comprising: an annular valve element adapted to seat with reference to said port, a piston within Asaid valve element and co operating therewith to form a closure for'said port, a supporting member slidably mounted in said` valve chamber and carrying said piston, yielding means urging said member and piston to - such pivotal attachment and such movement is a predetermined position, and a temperature re transferred to the valve 39. The arms 52 whereof, 60 sponsive connection between said piston and valve "as explained, are pivotally associated with said >element for moving the latter with reference to links 60 intermediate their length. f For the purpose oi rendering unnecessary re lplacements or substitutions of thermal coils to ïmeet different conditions and t0 regulate the ac -tionof the coil, whereby it will respond sensitively `and to a nicety to a Wide range of requirements, the- piston, said piston being adapted to‘mov'e against the force of said yielding means in re sponse to pressure in said lbypass and being , adapted, when it thus moves, t0 operate-said valve element, through said connection, to relieveV said pressure. a , Iïhave provided means for controlling the tension 3. A combined pressure and temperature con fof ‘the coil. A means for this purpose is shown in trolled valve for controlling the Viiow of a viscous Figs. 6,- 7, and 8, and includes the aforementioned 70 fluid through a bypass port of a heat exchanger Ashaft-(ill to which, as described, the dead end 63 having a normal heat exchange flow path and a óf the con s@ is secured and which is mounted for bypass, including said port, for circumventing 'rotation in the nat bars 56. On the projecting end -said normal flow path, comprising: -an annular '~-65 of-the shaft 64 is ñtted an end of akey or lever 'valve velement adapted to seat with reference to ï-'Gûhavingat »the 'outer end an 'arcuate flange 61 75 said«-port,»-a piston within- said-Valve element and, 2,405,831 cooperating therewith to' forma closure for said port, means to `yieldingly urgesaid piston> and valve element. towardsy a port closing position,y and a temperature responsive> connection between said piston and valve element formoving the latter with reference to the piston, said piston being _yieldable in response to pressure in said bypass and adapted, Awhen it thus yields, to operate said valve element, through said connection, to relieve 8 saidport, a supporting member within said valve element-and on which said valve’element is slid ably mounted, said supporting member cooperat 4. A combined pressure and temperature con trolled valve forr controlling the ñow of a viscous ñuid through a bypass port of a heat exchanger having a normal heat exchange flow path and a ing with said valve element to form a closure for said port, means for yieldingly urging said sup porting member and valve element to a port clos ing position, a thermostatic coil, one end of which is connected to said support, and a leverl pivoted on said valve element and connected at its respec tive ends to said supporting member and the other end of said coil, said lever and coil cooperatively forming a temperature responsive connection be tween said supporting member and valve‘element for moving the latter with reference to said-sup bypass, including said port, for circumventing said porting member. ' said’pressure. normal ñow path, comprising: an -annular valve element adapted to seat with reference to said port, a. piston within said 'valve element and co operating therewith to form a closure for said 8. A combined pressure and temperature-con trolled valve for controlling the now ofv a viscous bypass, including said port, for circumventing said other end of said lever, a shaft connected to .fluid through a bypass port of a heat exchanger having a normal heat exchange flow path and port,` means to yieldingly urge said piston and 20 a bypass.` including said port, for circumventing said normal flow path, comprising: an annular valve element toward aport closing position, and valve element adapted to seat with reference to a bi-metallic coil forming a, temperature respon said port, a supporting member within said valve sive connection between said piston and valve ele element and on which said valve element is ment for moving the latter with reference to the slidably mounted, said supporting member co piston, said piston being yieldable in response to operating with said valve element to form a pressure in said bypass and adapted, when it thus closure for said port, means for yieldingly urging yields, to operate said valve element, through said said supporting member and valve element to a connection, to relieve said pressure. port closing position, a lever pivoted on said ~ y5. A combined pressure and temperature con trolled valve for controlling the flow of a viscous 30 valve element and pivoted to said supporting member at one end, a loi-metallic thermostatic fluid through a bypass port of a heat exchanger coil, the outer end of which is connected to the having a normal heat exchange now path and a the center of said coil and journaled insaid sup normal i‘low path, comprising: an annular valve element adapted to seat with reference to said 35 porting member, and an adjusting elementvcon nected to said shaft and adapted to 4be connected port, a piston within said valve element and co to said supporting member in any one of several operating therewith to form a closure for said positions of adjustment about the axis of said port, means for yieldingly Jui-'ging said piston and shaft. valve element towards a port closing position, a Y 9. A combined pressure and temperature con thermostatic coil, one end of which is connected 40 trolled valve for controlling the flow of a viscous to said piston, and a lever pivoted on said valve fluid through e, bypass port of a heat exchanger element and connected at its respective ends to having a normal heat exchange flow path and a said piston and the other end of said coil, said bypass, including said port, for circumventing lever and coil cooperatively forming a tempera said normal flow path, comprising: an annular ture responsive connection between said piston valve element adapted to seat with reference to and valve element for moving the latter with ref said port, a piston within said valve element and erence to the piston, said piston being yieldable cooperating therewith to form a closure for said in response to pressure in said bypass and port, said piston having` a spherical peripheral adapted, when it thus yields, to operate said valve element, through said connection, to relieve said 5 0 surface and said valve element having a cylin pressure. 6. A combined pressure and temperature con trolled valve for controlling the flow of a viscous 'ñuid through a bypass port of a heat exchanger having a normal heat exchange flow path, and a bypass, including said port, for circumventing drical inner surface cooperating therewith to , permit sliding and universally tilting movement of said valve element in to said port, means for piston and valve element tion, and a temperature seating with reference yieldingly urging said to a port closing posi responsive connection between said piston and valve element for mov ing the latter with reference to the piston, said said normal flow path, comprising: an annularv valve element adapted to seat with reference to piston being yieldable in response to pressure in said port, a supporting member within said- valve said bypass and adapted, when it thus yields, to 60 element and on which said valve element is slid operate said Valve element, through saidconnec ably mounted, said supporting member cooperat tion, to relieve said pressure. ’ing with said valve element to form a closure for 10. A combined pressure and temperature con said port, means for yieldingly urging said sup trolled valve for controlling the iiow of a viscous - porting member and valve element to a port clos through a bypass port of a heat exchanger ing position, and a temperature responsive con 65 fluid having a normal heat exchange ñow path and nection between said supporting member and a bypass, including said port, for circumventing valve element for moving the latter with refer said normal flow path, comprising: a cylindrical ence to said supporting member. tubular valve element having a spherical and 7. A combined pressure and temperature con trolled valve for controlling the flow of a viscous 70 roughly frusto-conical valve face adapted to seat in saidlport, a piston having a spherical rim viluid through a bypass port of .a heat exchanger surface fitted Within said valve element, on which -having a normal vheat exchange flowpath, and a said valve element is slidable and universally - bypass, including said port, for circumventing tiltable to accommodate the seating of said valve said` normal flow path, comprising: an annular valve element adapted to seat with reference to 75 face in said port, means f_or >yieldingly urging 9 10 said piston and valve element to a port closing 11. A valve as set forth in claim 10, wherein position, a valve chamber communicating with the rim surface of the piston has a diameter said port, a supporting member slidably mount substantially equal to the diameter of said port, ed in said chamber, means rigidly connecting and wherein said valve element has an inwardly said piston to said supporting member, and a 5 oñset end portion on which said valve face is thermo-responsive connection between said Valve formed, said offset portion forming an internal element and connecting means, for moving the shoulder serving as a stop to limit the movement valve element with reference to the piston, said of said piston in one direction within said valve piston being yieldable in response to pressure element. in said bypass and adapted, when it thus yields, 10 to operate said valve element, through said con RAYMOND W. JENSEN. nection, to relieve said pressure.