US2592945A - Automatic starting system for internal-combustion engines - Google Patents

Description

April 15, 1952 Filed Feb. l, 1945 M. P. ODE AUTOMATIC STARTING SYSTEM FOR INTERNAL-COMBUSTION ENGINES 2 SHEETS-SHEET l 521ML #ffy Patented Apr. 15, 1952 AUTOMATIC' STARTING SYSTEM FOR INTERNAL-COMBUSTION ENGINES' Malcolm. P. Odell, Minneapolis, Minn.,A assignor to Minneapolis-Honeywell Regulator Company,

Minneapolis,

Minn., a corporation of. Delaware Application February l, 1945', Scrial'No. '575,683

lliClaims. 1

This invention relates to a system. for starting the engines of an aircraft or'other internal combustion engines, requiring no attention from thel pilot other than momentary pressurel or a starting switch, thus leaving him freel to perform other functions preliminary to taking; oflf the craft while the starting cycleV of thel engine is proceeding automatically.

One object of the invention is toprovide a system which is automatic in all respects as far as starting of the engine is concerned and which includes thermostaticmeans responsive to the temperature ambient to the engine for setting into operation proper priming means, for starting the engine in asatisfactory mannen regardless of the prevailing temperature.

Another obj ectA is tuprovide, a. sequential timer for timing various steps in theA startingcycle such as the operation of an auxiliary fuel pump, al starter` for the engine, an ignition intensifier, and automatic priming means, as well as means for meshing the starter at the proper time and furnishing a signal to the operator to indicate termination of the starting cycle.

Still another object isV to provide an automatic system wherein a thermostat responsive to the temperature ambient to the engine energizes various combinations of relays, depending upon whether the temperature isA high enoughthat no priming is required or low enoughthat priming is required, certain lower ranges of temperature positioning the thermostat so that aspecialauxiliary fuel can be used for priming the engine instead of the regular engine fuel.

A further object is to provide a pump for the auxiliary priming fuel having a pressure setting arrangement which is controlled by relays for either high or low pressure output, depending upon whether the temperature is below a predetermined point such as degrees, or above that point.

Still a further object is toprovide a means to terminate the operation ofv the various elements of the starting system after a timed period, or prior to that time provided the engine starts properly, so that there is no chance of the engine becoming ilooded.

An additional object is to provide a stop. control for the starting system which can be man.- ually operated at any time .during the starting cycle in case the operator for any*v reason wishes to terminate the starting cycle.

With these and other objects in view, my invention consists the elementsl of a starting system and their arrangementand combination (Cl. 12S-187.5)

whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out inthe claims and illustrated in the accompanyingdrawings, wherein:

llig.4 1 is an electro-diagrammatic View of an automatic starting system for internal combustionv engines embodyingmy invention;

Fig. 2 isa diagram showing the circuits which come vinto play during the startingV cycle and the timingfor the various circuits;

Fig.: 3, is adiagram showing the priming of the engine with different fuels at various temperatures* and atv different pressures for certain temperature ranges.; and

Fig. 4 is a detail View of a thermostat used in myesystem.

On the accompanying drawings I have used the referencey characterli to indicate an engine of,v internal combustion type, such as an aircraft engine. The engine E is provided with a starter S, such as oneof the usual inertia type, having a; ground terminal Il common tov tivo circuits, one of; which is energized through terminal Il and controlsthe; rotation of the starter and the other of which is energized through terminal I3 and controls the engagement ofV the starter with engineE.

The; engine has an ignition intensifier or booster IB for the purpose of providing an eXtra hotl Spark. during the starting period, and this.` booster isA of conventional design. Fuel is supplied' to the engine E through a carburetor yC from; one; or more fuel tanks, one ci which is illustrated at T1, and through an engine driven fuel pump P1 connected with the power shaft lil. During starting o -i the engine an electrically driven auxiliary'pump;1:2 is operated, the motor therefor being shown at M2.

Duringl the starting of the engine it is primed through primer jets l5 `from a conduit It, and when. engine fuel from the tank T1 is. used for priming it is supplied from a branch i8. of the main.- fueli line 2? through a icy-pass valve BV. At that time the valve is opened by energiaaticn of a solenoid S1.A g

At certain low temperatures a special auxiliary priming fuel; is supplied from a tank T2' through a priming fuel conduit 22,Y and. a 4pump P3'. The pump P3 is driven by an electric. motor M3. A check valve '2.4 is provided to prevent reverse now of fuel from the conduit-s it and i2 into .the conduit 22.

The pump Phas a pressure regulating means in the form of arelief valve RV, the opening cf whichv is normallyopposed by a pair of' spings 26 and 28. The pressure at which the pump operates is thus relatively high (60 to 75 pounds per square inch). The pressure of the spring 28 may be relieved from `the relief valve RV by energizing a solenoid S2, whereupon the spring 26 only is operable and reduces the operating pressure of the pump P3 to 30 or 40 pounds per square inch.

For controlling the solenoid S1, the motor M3 and solenond S2, relays R1, R2 and R3 are provided, and these relays, together with solenoids S1 and S2, pump P3, motor M3, by-pass valve BV, and relief valve RV, comprise a priming system PS for the engine. The relays are controlled by a thermostat T and a cam C3 mounted on a timer or cam shaft 3i! of a sequence timer ST.

For driving the sequence timer, a, motor M is provided. The timer shaft 30 also has cams C1, C2, C4, C5 and C6 thereon. The cam Cl controls energization of the starter S, the cam C2 controls energization of the booster pump motor M2, solenoid S4 and motor M, the cam C4 controls energization of the starter meshing solenoid S3, the cam C5 controls energization of the ignition booster IB, and the cam C*3 controls energization of the signal light 32.

rlhese cams have lobes of such length that they perform their various functions over time periods illustrated in Fig. 2. These periods are arbitrary, and may be varied somewhat in relation to each other, but it has been found by experiment at all temperatures that the periods illustrated in Fig. 2 are quite satisfactory, providing special priming fuels are used at low temperatures, such as those indicated in Fig. 3 below 20 F.

The thermostat T, shown in detail in Fig. 4, comprises a bimetal coil 34 or some equivalent temperature sensing element which is located preferably adjacent the engine so as to be responsive to the temperature ambient to the engine. Location in the carburetor air induction system is probably best. The bimetal coil 34 has a contact arm 36 engageable with contact sectors 35, 38, 40 and 42 at the approximate temperatures indicated on Figs. 1 and 4. The contact sectors 38, 40, and 42 are connected with relays R3, R1 and R2, respectively, which relays each include a holding switch 44 for retaining the relay energized after its energization is initiated by the thermostat and until such time as the circuit to the coils of the relays is broken by a starting relay R. A thermostat cut-out switch 'I2 iS connected between the sector 35 of the thermostat T and ground and is adapted to be manually actuated.

With respect to the construction of the thermostat T the segments 42, 33 and 40 are preferably adjustable as by mounting them by means of screws 3l through slots 39. With such an arrangement the segment 38 can extend counterclockwise as far as necessary since when the thermostat arm 36 goes below --30 it stays on this contact. However, the clockwise end of the segment 38 must be accurately positioned to correspond to the position of the arm 36 at -30. Similarly, the clockwise end of segment 42 may be located anywhere, and the position of its counter-clockwise end must be accurately located. Thus there are two points which must be set with considerable accuracy in the construction of the thermostat in order to have it operate at the two specied temperatures, namely, 30 and 20. It is also important that the clockwise end of segment 40 be accurately located. This counterclockwise end, however, may overlap the segment 42 to any extent, as there can be no circuit through the relay coil R1 unless there is also one through the relay coil R2. In other words, after the arm 36 leaves the segment 42 it can still remain in contact with the segment 40 without effecting energization of the relay coil R1. This permits of a comparatively simple arrangement of thermostat segments which may be adjusted at three critical points, namely, 30", 20 and without having to adjust the length of the segment*I 40, and this is made possible by the particular relay arrangement used. It is only when the arm 36 engages both segment 46 and segment 42 that-a circuit for the energization of relay R1 .becomes set up, and the counter-clockwise projection of segment 40 beyond the counterclockwise end of segment 42 is a matter of indifference. Segment 40 can accordingly be made any convenient length, and an accurate machining job is dispensed with.

The arm 36 may be provided with contact iingers 35H, 315a and lilla for proper engagement with the various segments 35, 30 and 42, and 40. The bimetal element 34 may have one of its ends anchored to the arm 36 as by rivets 33, and its other end anchored to a stationary post 3l. This post, as well as the contact segments, are mounted on a suitable base 29 of insulating material.

The cam shaft 36 of the sequential timer is normally rotated counter-clockwise, as by a spring 45, so that a stop arm 48 carried by the shaft engages a stationary stop pin 50. The shaft is rotated in the opposite direction by the timer motor Mthrough driving and driven clutch discs 52 and 54. The discs are meshed by energization of a solenoid S4, the solenoid being energized whenever the motor M is energized and deenergized when the motor is deenergized.

A starting push-button 53 is provided as an initiating control for the sequence timer, and for energizing a starting relay R, shown in its normal or unenergized position. The connections to the relay include a holding circuit which will here- .after be more fully described when describing the operation of the starting system. The timing period can be terminated at any time by a stop push button at 58 which breaks the circuit 'to the motor M and declutches the disc 52 from the disc 54 so that the cam shaft 30 may return to the initial position shown in Fig. l. The current may be supplied from any suitable source, such as a battery B through a master switch 60.

For automatically breaking the circuit of the relay R a tachometer switch TS is provided. This switch closes at about 800 R. P. M. of the engine and eiects deenergization of the coil of the relay l'tv by opening the delay switch DS. The delay switch includes a temperature responsive element such as a bimetal bar 62 thereof which warps upwardly by heat from a heater H. The heater is adjusted so that the delay switch operates about ten seconds after closure of the tachometer switch. The current from the battery B through the contacts of the relay R is supplied to the various circuits of the cams on the cam shaft 36 by a brush 64 contacting the cam shaft to transmit current to the shaft and through the shaft to each cam. The various circuits are believed clearly illustrated in Fig. 1 so that they will need no further description except as referred to'in the operation of the system which follows:

From the above it will be evident that the starting system for engine E includes as major components starter S, ignition booster IB, auxiliary pumpV P2, and priming system PS, controlled jointly by sequence-timer ST and thermostat` T.

Practical operation Assuming that the temperature ambient-tov the engine E is in the range of 20? to 100?, the thermostat T will be in the positionillustrated in Fig. l. The engine may now be started by'clos.- ing the master switch 60 and then pressing on the starting button e to initiate operation. of the sequential timer. The current from the battery B reaches the starter switch and from there passes through the normally closed stopswitch 58 to the motor M by wayv of wire59 and to'. the solenoid S4 by way of branch wire Bland returns to ground as in all circuits of the system. This results in the motor M rotating and thesolenoid S4 engaging the clutch 52-54 so that-fthe cam shaft 30 starts rotating clockwise.`

Current through the starter switch 561 also passes through wire 66, delay switch DS, bimetalv element t2 and relay R, returning by way ofthev ground. This closes the starting relay R sothat current from the master switch `60 is supplied through wires tl and 'li and the contacts 600i the relay R to the timer switch brush Bil-byway of wire lil. Current is supplied from the-master switch S to the coils of the relays R2 and R3iby wires 6l and tt. R3 is open at contact 38 of the-thermostat, but the circuit for the coil of relay R2 is closed at contact 42, from which the current iicwsfthrough contact arm 3S, contact 35, and to ground through thermostat cut-out switch l2 which is normally closed.

l Energization of the relay R2 depresses the bridging contact thereof from the position show-n in Fig. l so that current from wirev 68 is supplied to relay R1 and returns through theelement's'll, 35, 35 and i2 to ground. This operation. of relay R2 prevents energization of the motor M3 for the auxiliary fuel pump P3 and sets up a circuit for the priming solenoid S1 through wires 14`and16. The wire 'le is connected with thecontact wiper for the cam C3 so that the solenoid S1 is energized only when the cam C3 lreaches the proper position (illustrated in Fig. 2 as twenty-live secends after the beginning of the starting cycle).

.The cams C1 and C2, it will beV noted, arein position to Contact their wipersat theA beginning of the starting cycle. Accordingly, the current through the relay R and the brush 64 Vpasses through wires I8 and 80 to the starteriS. and the booster pump motor M2, respectively, forenergizing them. Current also ilows through wires 80 and S3 to energize motor M and 'solenoid S4. This results in initiation of rotation of camshaft 30, moving arm 48 away from stop 50. Thus in the temperature range of 20 to 100, the starting cycle involves the following steps:

The booster pump P2-andvthe starters vare energized at the beginning of the starting cycle. Priming is accomplished by energizing the booster pump and the solenoid S1 for opening the by-pass valve BV so that as theengine is rotating `it will beprimed with engine fuel from the-tank` T1 through the conduit I6 to the priming jets I 5. The priming starts twenty-uve seconds after-'the beginning of the starting cycle. Five second's'later the ignition booster IB is energized througha- Wire 82V from cam C5, and the starter ismeshed with The circuit for the'coil of relay' cams C5, C1 and C4, respectively, passing their cam wipers.

It should here be mentioned that the start button 56 need not be held in all during the starting cycle. Instead, a holding circuit for the relay R is set-up when the relay is in the operated position. This holding circuit may be traced from the vmaster switch 60 through wires El and 1I, the contact v6i) of the relay, the wire 10, the brush 64, .the sequence motor shaft 30, the cam C2, the wires 60, 63 and 59, the stop switch 58, the wire 66, and the delay switch DS, together with its bimetal bar 62, to one side of the coil of the relay R., the other side being grounded. Thus the holding circuit is through the stop switch 58 so vthat Whenever it is opened the holding circuitis broken.

The-engine should now be started, but if it has not. `or if, for any reason, the operator wishes to stop the starting cycle, the stop button 58 may be momentarily depressed, which breaks the holding circuit for relay R, thus permitting the cam shaft30 to return to its initial position for an, other start.

If the .enginezdoes not start, the motor `M .continues to rotate, and at H0 seconds the cam C6 engages its .cam wiper for energizing the signal 32 to Warn the pilot that the starting cycle is about completed and it is time for him to change his carburetor mixture control from autorich to autolean At theend of seconds, the priming circuit is broken at the cam C3 so that current is no longer supplied to the solenoid S1. At the same time the circuit to signal light 32 is broken by cam C, while circuits are broken by cam C2 which deenergize booster pump motor M2, motor M, and solenoid Si. The energization of solenoid S4 is eiective to release cam shaft 30 from motor M so that it can return to its initial position, with arm 48 against stop 50, under the influence. of spring 68.

If the engine does start and reach a speed of 800 R. P. M., heater I-I is energized by tachometer switch TS, and if the engine speed is maintained for l0 seconds, the circuit to relay R is interrupted byoperation of delay switch DS, putting the entiresystem out of operation. In this case light 32 is never energized.

After the starting cycle is initiated by depression of the starting button 56 it may be desirable to deenergize the circuit through the thermostat T to prevent a shift in the thermostat to a different range causing a lock-in of another relay in additionY to those initially energized. They, of course, are held by their holding switches 44 so that .current is no longer needed from the thermostat. This is accomplished by manually opening the thermostat cut-out switch l2. This also prevents any vibration caused by the starting of one engine on -a multi-engine aircraft from ai'- fecting the thermostat of another engine when its contact arm 36 is adjacent the position ci change from one temperature rangeto another. This switch operates independently of the startingswitch. If the pilot or operator of the system does not want to cut off the thermostat T he does not open the switch '12, and the thermostat remains operative in the circuit so as to respond to any change in temperature conditions which might occur, for instance, between a false or attempted start and a second start. The false start may have raised the temperature of the engine somewhat so as to position the thermostat ina different temperature range.

Irl-'the event that the temperaturer isat'or'above 100, the priming of the engine during starting is unnecessary. This is taken care of by the contact sector 42 only being in electrical engagement with the contactor arm 3S so that onlyk the relay R2 is energized. The relay R2, when energized, cannot then energize the relay R1 because there is no circuit from the lower end of the coil of relay Rl through the contact sector 40. Accordingly, the only element of the priming mechanism which is energized is the booster pump motor M2 through the cam C2 so that a fuel supply is provided during the starting period and until the engine has attained suilicient speed for the main fuel pump P1 to efficiently supply the requirements of the engine.

If the temperature range is between 30 and 20 the contactor arm 35 is free of all sectors of the thermostat, with the possible exception of sector 4B. However, the relay R1 can be energized only when the switch of the relay R2 is closed against the lower contacts thereof in addition to the circuit established across the arm 3; and the sector 40. Therefore, none of the relays R1, R2 and R3 is energized, and this results in the priming circuit from the wire 16 passing through the bridging contact of the relay R2 in its upper position, and a wire Si) to the motor M3 which drives the auxiliary primary fuel pump P3. The pump will accordingly pump priming fuel from the tank T2 through the conduits 22 and i5 and the check Valve 24 to the priming jets of the engine, thus providing a more volatile fuel for easier starting at this temperature.

The solenoid S2 will also be energized at this time because the bridging contact of the relay R3 remains in its raised position and, therefore, current from the wire 16 can flow to the solenoid S2 by way of wires 'il and l. rlhis compresses the spring 28 so that only the spring 23 opposes opening of the relief valve, and the spring 2S may have an effective pressure of 30 to 4G pounds, which is indicated as Low Pressure in Fig. 3. ln other respects the timing cycle is the same, that is, the booster pump P2 is operated its usual length of time, the ignition booster and the starter meshing circuits are energized their usual length of time, and priming is had over the usual time period. The signal 32 also lights during its usual last ten seconds of the starting cycle.

In the event that temperature is below 30", it is desirable to avoid energizing the solenoid S2 so that both springs 26 and 28 can be imposed on the relief valve RV to cause the pump P3 to operate at high pressure, as indicated in Fig. 3 (.60 to 75 pounds per square inch) This is accomplished by the Contact segment 3s being engaged by the contactor arm 36 of the thermostat T so that the relay R3 is energized to open the circuit for the solenoid S2. In respects other than high pressure for the priming fuel from the tank "I2 rather than low pressure, the starting cycle in this case is the same as when the temperature range is between 30 and 20. I

After the starting cycle has been completed, and during which time any one of the starting sequences may have been performed, depending upon the position of the thermostat T, the master switch Sii can be manually opened and left in the open position until such time as the starting system is to again be used.

From the foregoing specification it will be obvious that 1 have provided an automatic starting system for internal combustion engines wherein the basic control unit is a sequence switch controlled as to initiation by a starting switch. 'I'he starting cycle can be stopped immediately at any desired time, and the sequence switch will be automatically reset to the starting position for the cycle. Ten seconds after the engine is ring regularly the relay R is deenergized to shut down the starting mechanism and return the sequence switch to proper position for another starting cycle.

If the temperature ambient to the engine has been raised due to an incomplete start, the thermostat T may be in a position for another range of temperature. No release of any of the relays R1, R2, and R3 can take place, however, until the entire starting system is returned to its inoperative condition, due to the eiiect of holding contacts 44.

Each starting cycle is initiated in a very simple manner by a momentary depression of the starting button 5a to close the starting circuit. The switch '.'2 can thereafter be opened if desired to prevent vibration from causing improper operation of the relays R1, R2 and R3 after they are initially operated in accordance with the position of the thermostat at the time of starting. The operated relays are thereafter held in by their own holding switches to the exclusion of the remaining relay or relays, as the case may be.

Some changes may be made in the construction and arrangement of the parts of my starting system without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

1. A starting system, for an internal combustion engine having priming means and fuel supply means, comprising temperature responsive control means, means for causing variations in characteristics of the fuel supplied to said priming means, means connecting said second named means in controlled relation to said temperature responsive means for initial actuation in accordance with the response thereof, and means preventing subsequent change in the response of said control means from further aiecting said second named means.

2. A starting system, for an internal combustion engine having priming means, comprising temperature responsive control means, means for preventing operation of said priming means, means connecting said second named means in controlled relation to said temperature responsive means for initial actuation during periods when the temperature exceeds a selected value, and means preventing subsequent change in the response of said control means from altering the condition of actuation of said second named means.

3. A starting system for an internal combustion engine having priming means, a source of priming fuel, and means for maintaining at a selected upper value the pressure at which said fuel is supplied from said source, said system comprising temperature responsive control means; means for disabling said pressure maintaining means; and means connecting said disabling means in controlled relation to said temperature responsive means for actuation when the temperature is above a selected value.

4. A starting system for an internal combustion engine having priming means, a source of priming fuel at a rst selected pressure, and means for reducing to a second selected value the pressure at which said fuel is supplied from said source, said system comprising for operating said pressure reducing means, :temperature responsive control means, and means connecting said operating means in controlled rela-tion .to said temperature responsive-.means so that said priming means is supplied with said fuel at` said high pressure when the temperature is below a certain value and at said reduced pressure when the temperature is abovesaid value. A

5. A starting system, for van internal combustion engine. having primingmeans and fuel supply means, comprising temperature responsive control means, means for determining characteristics of the fuel supplied to said priming means, means connecting said second named means tosaid temperature responsive means for actuation in accordance with the response thereof, and means for preventing subsequent change in said response for causing change in the previously determined characteristics of fuel.

6. A starting system for an internal combustion engine having priming means, a source of priming fuel at high pressure, and means for reducing the pressure at which said fuel is supplied from said source, said system comprising means for operating said pressure reducing means, temperature responsive control means, means connecting said further means in controlled relation to said temperature responsive means so that said priming means is supplied with said fuel at said high pressure when the temperature is below a rst selected value, and at said reduced pressure when the temperature is within a selected range; means for preventing operation of said priming means; and means a connecting said last named means in controlled relation to said temperature responsive means fo-r actuation during periods when the temperature is above a second selected value.

7. A starting system for aninternal combustion engine having priming means, sources of engine fuel and priming fuel at selected pressures, selective means for supplying fuel to said priming means from either of said sources, and means for reducing the pressure at which said priming fuel is supplied from the source thereof, said system comprising selective means for operating said pressure reducing means, temperature responsive control means, and means connecting said selective means in controlled relation to said temperature responsive means so that said priming means is supplied with said engine fuel during periods when the temperature is within a first selected range, with said priming fuel at reduced pressure during periods when the temperature is within a second selected range, and With said priming fuel at said selected pressure during periods when the temperature is below a selected value.

8. A starting system for an internal combustion engine having priming means, sources of engine fuel and priming fuel at selected pressures; selective means for supplying fuel to said priming means from either of said sources, means for preventing operation of said priming means, and means for reducing the pressure at which said priming fuel is supplied from the source thereof, said system comprising means for operating pressure reducing means, temperature responsive'control means, and means connecting said operating means and said third named means in controlled relation to said tempera-ture responsive means, so that said priming means vis prevented from operating during periods when the temperature is above a, rst selected value, 'and is supplied with said engine fuel during periods when Ythe temperaturer is within a first selected range, with said priming fuel 'at reduced pressure during periods when the temperature is within a second selected range, and with said-priming fuel at said'selected pressure during periods when the temperature is below a second selected Value.

9. A starting system for an internal combustion engine Vhaving priming means, means maintaining a supply of engine fuel at a selected pressureya source of priming fuel, pump means for supplying priming fuel from said source at a selected `pressure, firstmotor means operable to actuate said pump means, means for conducting said engine fuel and said priming fuel to said priming means-normally closed valve means for preventing said engine fuel from -reaching said priming means, and second motor means operable to open said Valve means, said system comprising rst and second relay means for causing and interrupting operation of said first and second motor means respectively, temperature responsive relay control means, means connecting said relay means in controlled relation to said temperature responsive means so that said rst motor means is operated during periods when the temperature is below a selected value d said second motor means is operating during periods when the temperature is within a selected range, and means interconnecting said relay means so that said second motor means can open said valve only when actuation of said pump means by operation of said first motor means is interrupted.

10. A starting system for an internal combustion engine having priming means, a source of priming fuel, pump means for supplying said priming fuel to said priming means at a first selected pressure, rst motor means operable to actuate said pump means, relief valve means for reducing to a second selected value the pressure at which said priming fuel is supplied by lsaid pump means, and second motor means operable to disable said relief valve means, said system comprising relay means for causing and interrupting operation of said motor means, temperature responsive relay control means, and means connecting said relay means in controlled relation to said temperature responsive means so that said first motor means actuates said pump during periods when the temperature is below a selected value and said second motor means di:- ables said relief valve during periods when said temperature is Within a selected range.

11. A starting system for an internal combustion engine having priming means, means maintaining a supply of engine fuel at a selected pressure, a source of priming fuel, pump means for supplying priming fuel at a selected normal pressure, first motor means operable to actuate said pump means, relief valve means for reducing to a second selected value the pressure at which said priming fuel is supplied by said pump means, second motor means operable to actuate relief valve means, means for conducting said priming fuel and said engine fuel to said priming means, normally closed valve means for preventing said engine fuel from reaching said priming means, and third, motor means operable to open said normally closed Valve means, said system com-r prising: first, second and third relay means for causing and interrupting operation of said rst, second and third motor means; temperature responsive relay control means; and means con- 11 necting said relay mea-ns in controlled relation to said temperature responsive means so that no fuel passes to said priming means during periods when the temperature exceeds a rst selected value, so that engine fuel passes to said priming means during periods when the temperature is in a first selected range, so that priming fuel at said reduced pressure passes to said priming means during periods when the temperature is in a second selected range, and so that priming fuel at said normal pressure passes to said priming means when said temperature is below a second selected value.

MALCOLM P. ODELL.

REFERENCES CITED The following references are of record in the le of this patent:

Number UNITED STATES PATENTS Name Date Van Horn Oct. 16 1923 Federle May 12, 1925 Stokes Jan. 1, 1929 Ide Mar. 19, 1929 Ross Jan. 21, 1930 Fitzsimmons Aug. 23, 1932 Igarashi Sept. 24, 1935 Flamini Nov. 9, 1937 Vroom Dec, 13, 1938 Alexander Apr. 17, 1945 Ovens Aug. 15, 1950

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