US2146953A - Heater - Google Patents

Description

E. E.. H ANs 1&5. 14, 1939.

HEATER Filed July 51, 1955 5 sheets-sheet 1 Inl/$1 Feb. l14, 1939. E; EH-ANS V2,146,953

HEATER Filed July 5l, 1955 3 Sheets-Sheet 2 INVENTOR.

ATTORNEY.

Feb; 14, 1939. E. EA HANS l 2,146,953

HEATER Filed July 51, 1935 s sheets-sheet' INVENTOR.

ATTORNEY.

Patented Feb. 14, 1939 HEATER Edmund E. mns, Detroit, Mich.

Application July 31,

Claims.

This invention relates to heaters, and particularly to heaters of the type now being used in the modern automobile for heating the passenger compartment of the same.

In the past it was necessary for the driver of an automobile to wait a considerable length of time before the water used as a cooling medium in the internal combustion engine, became hot enough to provide heat within the driving compartment. Of late this problem has'become even greater on account of the eillcient means now being provided in the modern automobile for keeping the engine cool, such as larger radiators, larger water jackets and aluminum heads which tend to keepthe cooling medium at a lower temperature.

To offset the above, various types of auxiliary heating units have come into use, of which thel 30 another small amount of .water to ow in the heating chamber. As long as steam is generated, the heating system functions properly. These units operate eciently when enough heat in the generating compartment is supplied, from the exhaust of the engine, to generate steam. It is an obvious conclusion that the heat of the exhaust depends upon the speed of the engine. At speeds of twenty miles an'hour or.1ess an insuflcient amount of heat to generate steam is supplied by the engine. Because any heat received in the driving compartment is dependent upon the amount of st'eam generated in the heating unit, practic-ally no heat will be supplied when running at a speed from twenty miles an hour or less. The result would be that driving in the city where a number of stops must be made, due to traflic signals, a spasmodic heating arrangement will be had wherein a hot blast of air will be effected when accelerating or cruising at speeds higher than twenty miles an hour, and a comparatively cold blast is received as soon as the foot is taken oi the throttle to slow down or stop. This, of course, is undesirable.

Another disadvantage of the above described the pressure in the generating unit, and allows 1935, serial No. 34,027

system isthat during the course of operation, water, when generated into steam, will be distilled and a residue will be formed in the heating chamber. A certain amount of this residue will. circulate throughout theheating unit back into the cooling system of the engine and then back again into the inlet of the heaterl where the check valves are usually situated. This clogs up the check valves and necessitates cleaning, usually at approximately every one thousand to fifteen hundred miles. t

The present invention consists of an auxiliary heating unit so situated that the intense heat of the exhaust-coming from each cylinder of the engine will be combined before passing through the heating chamber to obtain a uniform heat. The amount of heat allowed to pass through the heating chamber may be regulated by a valve incorporated in the novel heater. The volume of water supplied in the generating unit 'is regulated so that the heating system is balanced. That is, the amount of heat supplied from the engine at low speeds is sucient to heat the steady ow of water passing through the generator. speeds the flow of liquid is such that at no time At higher v will there be any danger of generating pure steam rather than a combination of steam and water. This assures the maximum amount of heat obtainable without the danger of creating too great a pressure in the heating system.

The principal object of the present invention is to provide a new and improved heater for an automobile wherein auxiliary means is used to heat a small portion of the cooling medium thereby supplying heat quickly to the `driving compartment of said automobile.

A further object is to provide a new and improved car heater wherein the operator may control, from the driving compartment, the amount of heat from the exhaust manifold being supplied to the housing containing the heating coils so that the temperature in the driving compartmnt may be gradually increased or decreased according to the desire of the operator.

A still further objectof the present invention is to provide a new and improved 'car heater wherein the radiator and fan for same are located in the driving compartment of the car and the means for operating the fan is located on the engine side of the dash under the hood, thereby eliminating all motor noise from the driving compartment. Y

`Another object is to provide a new and improved radiator and fan housing construction so designed that the radiator'may be quickly detached therefrom to facilitate the use of the fan only for use in hot weather.

A further object. is to provide a new and improved heat and power control mechanism which vmay be conveniently mounted upon the driving side of the dash whereby the operator may oontrol the speed of the fan and also the amount seat.

- A still further object is to provide a new and improved coil chamber for a water heater so designed that there are two shells one nested withintheotherinsuchawaythatthehotexhaust gases from the exhaust manifold may pass between the. coils and upon leaving the inner shell, again pass overtheoutside of said heatins inner shell so that none ofthe heat from the exhaust manifold is dissipated until it has again passed over the outside of 'the inner shell to atmosphere. The inner shell also acts asa heat retainer. The shell may be of any suitable heat Y retaining material so that when the motor gencrates an abundance of heat due to rapid acceleration, this heat retaining material will absorb heat and give it up to heating coils when engine is again idling at-low speed.

By using several U shaped heating tubes the heat is' applied to each U tube moderately so that the heating liquid in it will not be disturbed or become overheated thereby eliminating steam pockets or separation of heating liquid which- 1 would cause the heating system to go dead.

Still further objects of my invention may be J enumerated as follows:

`sure-against leakage-of exhaust gas.

(1) v'llo' provide a unitary casting comprising inlet and outlet gas-ports with a suitable valve therebetween' which operatively directs the now `of gas through a aenerator'and back to the outlet port or directly to the outlet port to thus in- (2) To provide a non-coking valve structure which wm he gas tight 1h either or its extreme positions but which will -free itself from any car bon accumulation. The non-coking result is due to the close proximity of the valve to the engine exhaust manifold, while the increased 'emciency is due to the novel breached valve' seats employed.

(8) To provide a small but certain ilow of water Ato the generator at `all times when the heater -is being used and to automatically increase the i'iow when the heat supplied to the generator is suiiicient to heat a greater amountA of water.

'Ibis insures against the generation 0f Steam at high .speeds while preventing thev circulation of relatively cold water through the heater radiator when the unit is first started.'

v(4) To provide a by-pass'armind the heater radiatorl for summer conditions which will prevent damage to thegenerato'r and still prevent hot water from entering the' heater radiator.

(5) To provide a sediment chamber inthe inlet line to the generator and thus prevent the accumulation'of rust and sediment therein. f The above and other objects will appear more -fully from 'thefollowing more detailed description Yand by reference to the accompanyi drawings wherein: n

guests l ing coils omitted;

Fig. rl is a section taken substantially on the line 1--1 of Fig. 6 with the heating coils in place;

Fig. 8 is a section taken substantially on the line 8 8 of Fig. 7;

Fig. 9 is a section taken substantiels; oh the line 9 9 of Fig. '7;

Fig. 10 is a section taken substantially on the line il-II of Fis. 9;

Fig. 11 is afragmentary perspective view illusti'ating the position and construction of the control valve more adequately than previously shown;

Fig, `1-2 is an optional construction of one of the inlet ports to the heating mechanism as shown in Fig. 1;

Fig. 13 is a central sectional view of the control button for the valve illustrated in Figs. 7, 9, l0 and 11;

Fig. 14 is the -saine as Fig. 131 different position of the button;

Fig, 15 is a section taken substantially on line iB-Ii of Fig, 14;-

Fig. 16 .is a central sectional view of the motor and illustrates more fully the construction of the motor housing;;

1 Fig. 17 is a central sectional view of the inner shell motor housing showing the opening at the portion opposite the brushes;

Fig. 18 is a'detail showingthe U-tubeconnection:

but showing a Fig. 19 is a central sectional view of the by-l pass valve shown in Fig. 1; and

Fig. 20 is a section taken substantially on line IB-i in Fis. l:

Referring now to the drawings, the-numeral 25 designates la hose coupling used to connect the cooling radiator and the top of the water jacket 2C of the conventional internal combustion engine. A conventional water circulating pump is attached to the water jacket 26 in the usual manner. The pump is driven by a fan belt, not shown, which rotates in V shaped pulley H0 to which is keyed a' pump rotating member HI shown in Fig. 19 of the drawings. Conveniently connected into the hose connection 25 is a flexible hose or conduit 2'I preferably constructed of rubber, said conduit being coupled to the small pump chamber nut 29. The pump chamber 29 contains the pumping means shown more ln detail in Pigs. 2, 3 and 4 of the drawings, wherein the numeral 30 designates e. universal joint for coupling the vane 3| to the amature shaft 32 of themotor 12, the vane 3| being rotatably secured to the shaft 33 and journaled in the bearing 3l.' Leading from the pump chamber 2! is conduit Si, also preferably of rubber, which leads into chamber 3B. and chamber being shown more clearly in detail in Fig. 5 of the drawings, wherein is shown tightly seated a trap 39, the upper portion of which has a small upright tube 31 with an orifice I8 located inthe top of said tube. The

lower portion of the trap contains the opening ,-said opening being considerablylarger than thc opening 38. The lower end of the trap chamber 36 is ksecured to the coil head 4|c. The tube housing 4| is securedto head 4|c in any suitable` manner as shown in detail in Fig. 7,-a plurality of tubes 43 being shown in cross section in Fig; 8 of the drawings. The tubes 43 run the entire length of the inner shell 4|a near the top inner periphery thereof, turn and are brought back along the lower inner periphery thereof, and are sealed to outlet head 4|c.

The tube housing 4| is constructed of two shells 4|, 4|a, shell 4|a being-nested within shell 4| i'n concentric relationship, inner shell 4|a terminating at 4|b. An air space 45 .is provided between the tubes 43 and space 46 is provided between the inner shell 41a and the outer shell 4| to allow the hot exhaust gases from the manifold 48 to pass into the inner chamber 4|a and be tween the tubes 43, out the end of inner tube 4|a at 4Ib and back in the direction of the arrows shown in Fig. '7 of the drawings, between the outer periphery of the inner shell 4la and the inner periphery of outer shell 4| through opening 41 and into the conduit 53 leading to the muier, not shown. The main body of the heater 49a has a depending flange 49h having apertures therein to align with apertures in theflangcd portion of the exhaust manifold of any well known make of car, adapted to receive coupling means.

The heat control valve body member 49a illustrated in Figs. '1, 9, l0, 11 of the drawings is constructed to seat valve 50 in the following manner: sector shaped openings 49-c and 49-d, as shown in Figure 9, are provided in the respective sides of the body member 49`a, which openings are provided with bevel seats. 58a, 58h, 50c, and 56d, as shown best in Fig. 11 of the drawings. The longitudinal seats of valve 50 are at 58F and 58E. 'I'here is also provideda longitudinal seal at 50G which provides` a seal for valve stem 5I. Valve 58 and stem 5| are butt welded forming one body. These seals and 'seats are broached with a tool to provide perfect alignment for seal of valve 58.4 The length of valve 50 is less than the overall width of body member 49a at this location allowing liberal clearance for free operation of valve. The sector-shaped openings 49e and 49d are closed with two plates 53a and 54 in Figs. 9y and 10. These plates are provided lwith aligned holes through which a shaft 52 passes and forms a bearing in which the valve 58 pivots. 'Ilhe valve 5,0 is interposed between the tube chamber 4| and the conduit 53 leading to the muffler. Leading fromv the outlet 44 is the conduit 54a which connects the heating tubes 43 with the radiator 55. The'radiator 55 has a small inlet compartment v55a at the top and a large outlet 55h at the bottom. The 4conduit 56 leads threaded lugs 60, 6|. The radiator 55 is also provided with screw threaded lugs 62, 63 by means of which radiator 55 may be quickly secured to .the fan housing 59 by merely inserting the screws 64, 65. The motor for operating the fan 66 is housed in the housing 61. IThe fan 66 is rotatably secured by means of the screw 69, to one end o-f the armature shaft 32, said shaft being journaled .in the bearing 18 and is located 4in close proximity to the back of the radiator core 55. As shown most clearly in Figs, 1 and 16 of the drawings, it will be understood that the fan 66 is on the drivers side of the dash 1| and the motor 12 and pump 29 are located on the other side .of the dash 1| under the hood of the car. The locating of the motor and pump away from the driving compartment prevents any noise created by the operation of these elements from entering the passenger compartment.

The motor housing 61 is constructed in three parts, an inner sleeve 13 as indicated in detailed drawing Fig. 17 which has an opening 14 aligned with the commutator brushes 15. A sleeve 16 is also provided with two circular reduced portions, the larger of the two act as an enclosure and support for couplingmeans, while the smaller threaded portion receives the pump chamber 29 and also acts as a support and seal for the same.` The sleeve 16 is telescopically engaged over the inner housing 13 and abutsv against the portion of the housing 61 nearest the dash 1|. The housing 61 is held as a unitary assembly by means of a band 68, Fig. 1, which is tightened by the screw 66a. The section 61 of the housing is provided with a reduced portion 18 adapted to pass through an opening in the dash 1|. 18 is threaded at its outer extremity to receive anut 19 which holds the fan housing 59 over the reduced portion 18 securely against the dash 1|, thereby bringing the entire motor and fan assemblyinto one unitary compact structure..

Referring nowv to Figs. l, 13, 14 and 15 of the drawings, a control mechanism is shown to operate the valve 50 and consists of a Bowden wire 88 secured to the control lever 52 and terminates at the instrument panel 8|. -The operating mechanism on the instrument panel consists of Va control for the motor 12 consisting of a rheostat 82. The rheostat 82 is controlled in combination with the push pull button 83 of the Bowden wire 80. A clamping member 84 is provided to eliminate the necessity of drilling a hole in the dash 8| to secure the control assembly to s aid dash.- The clamping mechanism 84 has an adjusting screw 85 to fasten the assembly rmly to the dash 8|. The end of the Bowden wirel terminating at the instrument panel 8| consists of a sleeve 86 passing through an aperture in the bracket 84 and has a cup shaped member 81 securely fastened at the end ofthe sleeve 86, said cup shaped member 81 being adapted to receive a cup shaped insulating member 88 wherein the rheostat windings 89 are assembled. The sleeve 86 has a circular inner periphery, and is adapted to receive a non-circular push pull rod 98, said rod Y9|) passing through the rheostat'82, said rheostat being provided with a clip 9| which is slidably secured upon the rod '90 so that said clip is anchored to the rod 90 when turning in a circular path, and slidably mounted on the rod 98 when moving longitudinally thereof. The clip 9| is conventionally insulated and comes in contact with therheostat windings 89. The clip 9| is provided at its other extremity with a sleeve 92 which passes through the insulating member 88. AA spring 93 is interposed between the inner face of the rheostat and the spring clip 9| to hold the clip against the rheostat windings 89 when The reduced portion the push pull button 83 is pulled out and the heater operating.

Referring to Fig. l2 ofthe drawings, I have shown` an optional construction of an opening shown in Fig. 5 of the drawings. The size of the restricted orifice 38 shown in Fig.v 5 can be changedA by manually changing the entire assembly and having a larger or smaller orice 38. A by-pass valve |04l is provided adjacent to radia- Vtor 55 to by-pass incoming heating liquid which enters by inlet pipe lla through valve plug opening |06 in Fig. 30, thence left to opening |01 and |08 returning throughA pipe 56. When valve plug |05 is turned anti-clockwise openingy |01 registers with opening in pipe 54a to normal operation. There is no hand lever shown on valve plug |06, any desired form of lever may be used. The optional construction shown in Fig. i12

1a shows a means of automatically controlling the size of the. opening33a,-the assembly of whichy consists of va radiator 55 in the driving compart' ment having an inlet and outlet 54a, 56 respectively. The loutlet '56 terminates in a thermostat housing 94 which has a bi-metal strip 95 secured .therein tothe inner wall, at one end, and the other end thereof connecting a plunger valve 86 g which operates in a cylindrical chamber 91 having screw threaded enclosure cap 33 at the outer end of the cylindrical chamber 31. A spring 99 is interposed betwen the cap and the plunger valve 96 to hold it normally in the position shown in Fig. ,12. The plunger valve 96 also passes through the opening 33a. 'Ihe bi-metal strip then ac'- g tuates the plunger 96 in the cylindrical chamber 91 to regulate the size of the opening 38a. The by-pass channels H2, ||3 allow a limited amount of liquid to flow constantly to the heating unit.

The manner in which my device operates is as follows:

As the internal combustion engine is started, there is also started a conventional type of water pump |09 used in most automobiles at the present time. This water pump is invariably of the centrifugal type which agitates the water at low speeds and propels it at higher speeds. The thermostat |0| locatedin the hose connection 26, is closed and has been adjusted to open at a temperature usually around 135 to 145 degrees. This temperature is merely selected as the most emcient temperature that the engine operates,

and is variable to suit the eillcient' operation of Y the engine. v o

.Applicant has discovered through experimentation that pump |03 passes the water through the thermostat |0|- opening more rapidly than through hose passage 21 after temperature of cooling medium in motor is normal, thereby reducing its flow or stopping it entirely because thermostat valve is then in an open position. The only beneiit derived from pump I 09 is on sudden acceleration, spasmodic pressure might occur in line 21. Little, if any, beneilt is derived from pump |09 until the car has passed a road speed of thirty miles per hour or more. At higher speeds the pressure in line 21 will increase, thereby allowing more water -to pass through pump 29 and passageway 35. Should pump 29 be eliminated there would be no assurance of constant heat below thirtymiles per hour. The purpose of the thermostat 95 is' to regulate lthe iiow of water to the generator so that only a small amount is supplied to the generator when .the discharged water from the radiator 55 is 65\}below a predetermined temperature and to in- .crease the flow when suiilcierit heat is being supplied tov maintain the discharged water at about 160 F. When the engine is first started, the thermostat 95 keeps the valve 96 closed so that 7othe orifice 38l is partially restricted. 'I'his allows the water. which flows throughthe generator to be heated much hotter than if no restriction were provided. However, after the engine is warmed upand the car is operating at a higher speed, a greater flow of water is required to be circulated las inany conventional rheostat.

through the generator to prevent the formation of steam. This is accomplished by the valve 96v which opens when the discharge from the radistor reaches a given temperature. A

Thus, an adequate but restricted supply of water is fed to the generator when the heat supplied thereto is small and a greater supply is fed when more heat is directed to the generator. This is accomplished without reference to the engine circulating pump |09, the speed of which may not in any way be proportional to the amount oi heat directed to the generator.

The water, after passing through the outlet M, iiows through the tubing 43 to the conduit 54-a andinto the radiator core 55. The fan 66 when operating causes 'a steady stream of air to ow through the radiator core 55, the hot fluid passing through the radiator core in turn warms the air being blown into the passenger compartment of the automobile. 'Ihe position of valve 50, Fig. 7, determines the quantity of exhaust gas passing around the inner tubes lla, which in turn heats the tubing I3 containing the fluid. The hot exhaust gases flow in the direction of the arrows in Fig. '7, leave the inner shell -la at Ib and return through passageways 46 which are deilned between the `outer shell 4| and the outer cylindrical wall of theinner shell Ila. 'I'his unique construction provides a double insulation and the gas does not dissipate all of its heat when it is being passed back toward the conduit'll and to the muiiier. Should the operator wish to dispense with the heat being passed through the `by bolts passing through flange 49h, thereby bringing the heating unit as close to the main exhaust manifold as possible 'and at the same time being interposed with .a control valve 50. In this manner it is also protected from heat being generated through the body of the heating unit 09a when the valve 50 isclosed. In summer weather it is not necessary to disconnect the inlet and outlet connection `of the heating liquid to the radiator and the driving compartment because the heat cut-off is complete and there is no possible way in which the heat can penetrate into this heating unit because it is separate from the main engine manifold and also is insulated by the outer shell 4|.

'Ihe push pull button as shown most clearly in Figs. 13, 14 and 15 consists of the button 33 which is provided forthe valve 50 and is pulled out to set valve 50 in the position shown in Fig. '7 of the drawings. The spring 93 then pushes the clip 9| against the rheostat windings 89 as indicated in Fig. 13. In order to adjust the speed of the motor 13 the push pull button 83'may then be rotated clockwise or anti-clockwise to rotate the clip 9| around the windings 89 thereby either increasing or decreasing the electrical resistance During the warm months when the heater is not in use, the core 55 may be removed by simply removing the screws 63, 64 and uncoupling the conduits at |02 and inserting therein the U-shaped tube shown downwardly to just'ride on the shoulder 92 to close the valve 50, as shown in the dotted line` position of Fig, 7. This by-passes the exhaust gases directly to the muiiler. By pushing the push pull button 83 so thatit just touches the sleeve 92, contact between the clip 9| and the rheostat windings 89 may still be made. To shut oit the motor push pull button 83 may then be pushed against the insulating housing 88 thereby pushing the clip 9| away from the rheostat windings 89 and breaking the circuit. 4

This invention provides constant ow of heat at low engine speed. Heat generated by exhaust gases around-heating coil is delivered to heat radiating unit byl electric liquid pump. The electric motor is of novel construction with few parts designed to provide a rigid mounting for radiator, fan housing constituting simple supporting and coupling means. Opposite electric motor cover also provides part `of liquid pump support with coupling means between motor and pump. Positive liquid circulating means provides greater heating eiciency and comfort. By removing motor housing 16, provision is made for accessibility and quick service to commutator through housing 'I3 and opening 14.

A thermostat control means in Fig. 12 governs the inow of heating liquid from temperature of outgoing liquid from heat radiatingI unit. There is also provided a smallpassageway which acts as .a by-pass into heat generating unit providing constant ow of liquid into same supplying suili-` cient liquid for quick heating after car has been driven but a few blocks and maintaining a constant heat. Heating liquid thereafter is maintained at near boiling point at a speed of from twenty to thirty miles per hour. As the speed is increased the heating liquid correspondingly rises, thereby increasing the temperature of the outgoing liquid fromy the radiator heating unit at which point the thermostat responds and opens the inlet valve to the heat generating unit,

' thereby increasing the ingoing liquid lin proportion to the speed increase resulting in greater heat flow to heat radiating unit causing a higher temperature to be blown through heatradiating unit and at the same time preventing the system from generating steam. With,A this automatic heat control any desired anti-freezing liquid may be usedv successfully.

The foregoing automatic liquid control may be used in place of manual'control means as shown in Fig. 1 and Fig. 13 or both may be used. However it may be understood that my heat generating unit may be used for liquid heating or steam generating with or without liquid automatic control. The liquid pump providesa constant pressure against the orifice or jet in Fig. 5. The small opening prevents reversing of the liquid inlet to heat generating unit. 'l Y Referring to Fig. 1 ofthe drawings: The radiator 55 has an inlet compartment 55 compara- 'tively small in size so that a minimum amount of liquid is stored within the heating system. This assures a faster heating in thedriving compartment when starting because a lesser amount of cold liquid will have to be forced from the top of radiator and thereby allows the incoming hot liquid to heat the radiator faster.

Ywhile I have described and illustrated a satisfactory installation that has proven highly successful in practical operation, it will be understood that the invention is not limited to sper ing coils in said heating chamber, for the purpose described.

2. A heater particularly adapted for use with an internal combustion engine, an exhaust manifold, a heating chamber communicating with said exhaust manifold, said heating chamber having an auxiliary chamber therearound and valve means interposed between said exhaust.

manifold and said heating chamber to control the ow of exhaust gases through said heating chamber and auxiliary chamber, and heating coils in said heating chamber, for the purpose described.

, 3. A heat exchanger adapted to be fixed to an engine exhaust manifold comprising, a housing having inlet and outlet gas receiving chambers therein with a port forming communication therebetween, a heating unit having a circuitous passagewaytherein, said unit being secured to said housing with the intake end of said passageway communicating with said inlet chamber and with said outlet end of said passageway communicating with said outlet chamber, an exhaust pipe secured 'to said outlet chamber, a valve mounted in said housing which in one position closes said port and deects the exhaust gases.

from said inlet chamber through said passage- `way to said outlet chamber, and which in another position closes said inlet chamber from said passageway and opens said port-to thus deect the exhaust gases directly from said inlet chamber to said outlet chamber and a heat transfer element disposed within said passageway.

4. A heat exchanger adapted to be xed to an engine exhaust manifold comprising, a housing having inlet and outlet chambers therein with a port forming communication therebetween said inlet chamber directly receiving exhaust gas from said manifold, an exhaust pipe secured to said outlet chambena heating unit comprising a pair ofv tubes extending from said housing, the outer ends oi' said tubes being in communication with each other and the inner ends of said tubes com-v municating with s aid inlet and outlet chambers, respectively, a valvemounted in said housing which' in one position closes said port and deilects the exhaust gases from said inlet chamber through said-tubes to said outlet chamber, and

' which in another position closes said inlet chamber from said heating unit and uncovers said port to thus deflect the exhaust gases from said inlet chamber to said outlet chamber, and a heat transfer element disposed in one of said tubes, for the purposes described.

5. A heat exchanger adapted to be xed to an engine exhaust manifold comprising, a housing having inlet and outlet chambers therein with a port forming communication therebeexhaust gas from said manifold. an exhaust pipe secured to said outlet chamber, a. heating unit comprising a pair ot concentric tubes extendins from said housing, the outer'end of the outer 'of said tubes being closed and communicating with the outer endot the inner of said tubes to form a return passageway therearound, the inner ends of said -1nner and outer tubes communicating with said inlet and outlet chambers, respectively. a valve mounted in said housing which in one poe tween, and said inlet chamber directly receiving

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