US2158572A

US2158572A - Automatic engine control

Info

Publication number: US2158572A
Application number: US654724A
Authority: US
Inventors: Myron S Curtis
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-02-01
Filing date: 1933-02-01
Publication date: 1939-05-16
Anticipated expiration: 1956-05-16

Description

May 16, 1939- M. s. CURTIS 2,158,572

AUTOMATIC ENG I NE CONTROL Filed Feb. l, 1933 77e, di

BY M um 7 ATTORNEY Patented May 16, 1939 UNITED STATES PATENT lOFFICE Myron S. Curtis, Pawtucket, R. I., asslgnor to William Wallace Potter, Pawtucket, R. I.

application February 1, 1933, serial No. 654,724

Claims;

-As a satisfactory exempliiication of my invention, I will take the case of an internal combustion engine which usually has a carburetor for furnishing an explosive mixture to the engine.

5 This carburetor is commonly furnished with an air admission, or, as it is usually called, a choke valve, for regulating the amount of air supplied to the carburetor, which regulation is necessary to provide a. proper mixture, and a throttle valve )0 for regulating the amount of mixture supplied to the engine, and hence the speed of the same.

The engine is also commonlysupplied with a starting motor and a manually operated switch to f control it for cranking the engine.

There is. a certain nicety of control necessary in starting an engine, particularly if it is cold, and in keeping it nmning until it is warmed" up. The operator must properly manipulate the choke and throttle valves, while operating the cranking motor, and this manipulation is beyond the ability of the average driver. The result is that the engine is either flooded, or too rich a mixture is used resulting in washing the lubricating oil from the engine walls at the time when it is most necessary and in crank case dilution, or the engine stalls due to lean mixture or improper Y throttle opening, and the operation of the engine is in general unsatisfactory until it is warmed up.

Also with the present day multi-cylinder engines an with small flywheel inertia, there is danger of the engine stalling while idling, this danger being particularly prevalent with free wheeling, and with present design engine noise has been so far eliminated that often the iirst knowledge the operator has of a-stalled engine is its failure to pick up speed when he opens the throttle.

It is therefore, desirable that the operation of adjusting the choke and thr'ottle valves for a proper mixture, and the operation of the self- 40 starter, be removed as far as possible from the necessity of operator control, that is to say, that the engine will be always running and kept running with the proper mixture as long as the ignition switch is on, and will remain stopped when the ignition switch is off.

There have been separate devices invented for controlling the mixture, and for starting the engine. My invention combines into one unit, `the l complete control of mixture, anti-stall, and starting, and I accomplish this control by a combination of intake, manifold pressure, mixture temperature, and throttle opening, which three conditions, as will be hereinafter explained, are those to be considered for a proper operation of the engine.

(Cl. 29o-37) By my invention, provision is also made automatically to make operation of the starting motor impossible under conditions which would be hurtful or otherwise objectionable, as for example, when the engine is running, when it is en- 5 gaged with its driven member vor whenthe ignition timing is so far advanced as to present the danger of pre-ignition when starting, with the consequence that the engine will run backwards.

I do not restrict myself to an embodiment of 10 my invention which will contain al1 or any number of the features or the devices before mentioned or hereinafter to be described, but my invention is to be understood as consisting in whatever is described by or is included within the l5 terms or scope or legal meaning of the appended claims. I

Referring to the drawing, which for the purpose of clarity of illustration, is somewhat diagrammatical,

The figure is an elevation of enough of a gas engine to illustrate an embodiment of my invention.

I illustrate my invention as applied to a carburetor I0, of the so-called downdraft type, and 25 which is bolted to the intake manifold II, from which the mixture flows to the` engine. Air enters the carburetor through port I2, the amount of air supplied being controlled by the choke valve I3, which is shown of the balanced butter- 30 fly type. It may, however, be of any type. The suppy of mixture from the carburetor to the engine is controlled by the throttle valve I4, which is manually operated in the usual manner. Fuel is fed to the carburetor from a. float chamber 35 through jets in the ordinary manner. As the method of feeding fuel forms no part of my invention, the float chamber and jets are not illustrated.

The choke valve I3 is fastened to a shaft I5 to 40 the squared end of which is fastened the choke lever I6. The valve is normally held closed by coil spring I'I, one end of which is fastened to lever I6 and the other end to the carburetor body. Choke valve I3 is opened by, and accord- 45 ing to the degree of engine suction, the motion of an engine vacuum actuated diaphragm I8` transmitted by diaphragm rod I9 to a pin 2U fixed on lever I6. The diaphragm is held on rod I9 by flanges 2I and 22, nut 23 and collar 2l, the l0 latter serving as a limit stop by abutting the adjacent end wall 25 of the diaphragm chamber when the diaphragm is moved to that position by spring 26, when there is no engine vacuum. The diaphragmis tightly clamped' at'its outer rim at a point between wall 25 and the opposite end wall 21, and the space between the latter and the diaphragm is connected by pipe 28 with the carburetor or intake manifold on the enigne side of the throttle so that the vacuum acting on diaphragm I8 is that existing in the intake manifold.

A lever 29 is pivoted on stud 30 fast in body I0 and .has an arm 3| encircling rod I9, and which arm is held against stop pin 32 by spring 33. The other arm 34 of lever 29 has a slip joint connection with throttle arm 35, by means of the rod.

36 being longitudinally slidable in holes in one end of link 31 and having a stop collar 38 on this end. An adjustable connection is provided between rod 31 and throttle arm 35 by means of a threaded rod 39 screwed into the other end of link 31'. With this slip joint connection, it is apparent that rotation of lever 29 in a clockwise direction can move arm 35 to open the throttle I4, but/the throttle is free to open or close beyond this position without affecting lever 29.

Rod 36 has slidably mounted upon it flanged sleeve 40 held by spring 4| against the end of arm 42 of choke lever I6 spring 4| being of such length that with choke valve I3 closed and throttle I4 slightly opened sleeve 40 will approximately touch arm 42. The length and strength of spring 4| is varied to suit different carburetors. Throttle lever 35 is provided with the customary stop 43 and stop screw 44.

For controlling theposition of choke valve I3, according to mixture temperature, I provide a thermostat 45, which is preferably of the bimetal coil spring type, although I do not limit myself to this type, and which I have shown with the outer end 46 in intimate contact with the intake manifold casting so that the'position of the thermostat arm 41 reects the temperature of the mixture. However, the thermostat can be located at any desired place. The other inner end 48 of the thermostat coil is fastened to shaft 49 to which is fastened arm 41, and the thermostat coil is so arranged that heating it causes arm 41 to move in a clockwise direction. I preferably shroud thermostat 45 with a cover 50 which in this case I have designed to provide also a support for the shaft 49 and a means. for clamping the thermostat to the intake manifold. Arm 41 is connected by rod and adjustable connection 52 with lever 53 pivoted on stud 54. A stop pin 55 limits movement of lever 53 in a counter-clockwise direction. A pin 56 on lever 53 coacts with jaw face 51 of lever I6 to provide "a yielding stop against opening movement of choke valve I3, when the thermostat is cold, the position of pin 56, and hence the degree of resistance to opening, depending on the temperature of the thermostat. When the thermostat becomes hot pin 56 coacts with jaw face 58 of lever I6 and forms a positive stop against the closing of choke valve I3.

Rod I9 has a lug 64 which upon movement of rod I9 to the right under action of intake suction, engages the free end of a spring leaf 65, on which is an electric contact point 66 that by coaction with a contact point 61 on spring leaf 68 makes and breaks a circuit.' These two contacts are held together by the tension of the two spring leaves. This adds yielding resistance to the movement of rod I9, and further movement of said rod to the right moves leaf 65 away from leaf 68, but due to its spring tension leaf`68 will follow leaf 65 until it strikes an adjustable stop screw 69, when its motion will end and contact between points 66 and 61 will be broken bythe further movement of leaf 65. Similarly, move- Driven by the engine 83 is a generator 84l equipped with the usual battery cut out 85, which prevents current flowing back from the battery through the generator and also prevents the generator from charging the battery until the voltage has reached a predetermined value. The generator 84 is electrically connected through this battery cut out and by

wires

86 and 81 with a storage battery 8B, and this battery is also electrically connected by wires 81, |0|, 89, 90 and switch 8| with starting motor 9| so that when switch 8|, which is normally held open by spring 82, is closed by current being supplied to solenoid 12, the starting motor is operated, thus cranking the'engine.

Solenoid 12 is electrically connected with battery 88 through wire 13, spring leaf 68, contacts 61 and 66, spring leaf 65, wire 19, ignition switch |14, wire 80, timing switch |02, wire |03, reversing switch |04, thence to solenoid switch |15, either through wire |05, gear lever switch 19 and wires 92 and 93, or through wires"|05 and 94, clutch switch 18, and wires 95 and 93, and from switch |15 to battery 88, through Wires |00 and 81. Ignition switch |14 is operated manually to start the engine. Timer switch |02 is normally held closed by spring |06, but may be opened by finger |01 fastened to the inner head |08. This timer head is customarily rotated either by hand or automatically to advance or retard the spark, the rotation to advance the spark being in the direction shown by the arrow. It is therefore apparent that advancement of the spark beyond a predetermined point will open switch |02. Reversing switch |04 is of the well known type where the switch bar |04 is frictionally connected through disc |09 with a rotating part of the engine, which normally rotates in the direction shown by the arrow, so that the switch is frictionally held closed when the engine is rotating in its normal direction, and is held closed by gravity when the engine is stopped. Reversal of the rotation of the engine, however, opens switch |04 by friction disc |09, the degree of openingbeinglimited by stop pin ||0. Switch 19 is so operated by the gear shift lever 96 that it is closed when the gears are in neutral and at other times is open and switch 18 is so operated by the clutch pedal 91 that it is closed when the clutch is disengaged and open when the clutch is engaged. Switch |15 is normally held closed by the spring |16, and may be opened by a solenoid 11, which latter takes current from generator 84 through wires 98 and 99. When the engine is running and the generator is furnishing current, solenoid 11 is excited by this current and opens switch |15 against the resistance of spring |16, so that switch |15 is open when the engine is running. Thus when contacts 66 and 61 are touching, ignition switch |14 is closed, timer switch |02 is closed, reversing switch |04 is closed, switch |15 is closed, and either switch 18 or switch 19 is closed, an electrical circuit is formed through solenoid 12, closing switch 8| and operating the starting motor, but opening any of these switches will break the current, thus allowing switch 8| to open. I do not limit myself to a structure that contains all these switches, for instance, any or all of

switches

11, 18, 19, |02,

|94 and |15 may be omitted from the control clrcuit.

As hereinbefore described rod I9 is free to slide in arm 3| of lever 29, but continued movement of the rod to the right under action of intake suction and against the pressure of spring 26 causes lug 63, on rod I9, to engage arm 3| so that further movement to the right of rod I9 moves lever 29 counter-clockwise and also brings spring 33 into cooperation with spring 26 to resist movement of rod I9.

I will now describe briefly, the operation. The throttle stop screw 44 is adjusted with relation to stop 43 to give the desired idling speed when the engine is hot, and connection 39 is adjusted so that when lever arm 3| abuts stop pin 32 the throttle is open considerably more than at normal idling speed. Assume the engine stopped and cold, then lever 53 is held against stop 55 by thermostat 45. As there is no vacuum in the manifold, rod I9 is held by spring 26 in its extreme left position with collar 24 against chamber wall choke valve I3 is held shut and spring 33 holds arm 3| against stop 32 and, thus by rod 36, collar 39, link 31 and connection 39, holds throttle I4 open, with the contacts 66 and 61 touching, all as illustrated.

As the engine is stopped, switch |04 is closed and if the spark is properly retarded switch |02 is closed. u

The ignition switch |14 is now closed by the operator. With the engine stopped, no current flows through solenoid 11, and switch |15, is, therefore, closed by spring |16. If either the clutch is out, thus closing switch 19, or the gears are in neutral thus closing switch 19, a circuit is formed through solenoid 12, when contacts 66 and 61 touch thus closing switch 9|, energizing the starter motor 9| which cranks the engine; but if both the clutch is in and the gears engaged, no circuit will be made, and the cranking motor will not be started. The cranking of the engine causes a low vacuum in the intake manifold whch is communicated through pipe 29, to the diaphragm and thereby overcomes the resistance of spring 26, moving rod I9 to the right until lug 64 abuts spring leaf 65, the extra resistance of this spring leaf preventing farther movement of rod I9, as the low vacuum is not enough to overcome this extra resistance. This 'Y movement of rod I9 to the right tends through spring 62 and pin 20 to move lever I6 counterclockwise, thus opening the choke and, as there is a slight amount'of play between pin 56 and jaw face 51, a slight opening is obtained before thermostat lever 53 begins to offer resistance. At cranking speed, the movement oi' diaphragm I9 will tend to be intermittent due to the alternate suction and compression strokes of the engine pistons, hence choke valve I3 will have a slight utter. When the engine is very cold the thermostat holds lever 53 hard against its stop pin 55, and pin 56 offers so much resistance to movement of lever I6 that spring 62 is compressedand the choke opens but slightly. If the engine is warmer, however, lever 53 offers less resistance to movement of ,arm I6 and spring 62, either does not compress at all, or but slightly, thus giving a greater choke opening for cranking when the engine is warm than when it is very cold. Thus regulation of the cranking opening of the choke valve is accomplished by vthe degree of antagonism between thermostat lever 53 and spring 62.

Immediately the engine starts firing, the firing vacuum (which is much greater than the starting vacuum) is enough to overcome the resistance of spring leaf 65, and the rod I9 is moved farther to the right, breaking contacts 66 and 61, thus cutting out the starting motor circuit. also provide for breaking the starting motor circuit when the engine begins ilring by solenoid 11, which is energized by the generator voltage when the engine starts firing, and thus opens switch |15. 'I'his movement of rod I9 also opens the choke still more, the amount of opening depending upon the degree of vacum and the resistance which the thermostat offers through arm 53 and pin 56 to the movement of lever I6, this resistance being greater the colder the engine. If the engine is warm at starting the thermostat offers but little resistance, and if it isl at its normal running temperature the thermostat has rotated lever 53 sulciently clockwise to hold the choke valve positively wide open.

After the engine has been started the idlingvacuum in the chamber 21, when the engine is idling, is enough to overcome the resistance of spring 33, by lug 63 coacting with arm 3|. This rotates lever 29 counter-clockwise, thus allowing throttle I4 to close toward its normal idling position from starting position, the degree of closure depending on the temperature through the resistance oiered by thermostat arm 53. Thus, the idling speed with a cold engine will be greater than that with a warm or hot engine.

When the throttle is operated manually to increase the engine speed, opening the throttle causes the vacuum to suddenly drop temporarily. This allows the choke valve to close as the rod I9 will move to the left to permit lever I6 to move clockwise depending on the condition of the thermostat 45, which action may give too rich a mixture. However, as the throttle is opened, sleeve 40 is pushed by spring 4| against arm 42 on lever I6 tending to move it anti-clockwise to open the choke, and thus overcome the eiect due to the vacuum drop. This opening of the choke being resisted by thermostat arm 53, it will be seen that a proper running mixture is attained through the co-operation of intake manifold pressure, engine temperature and throttle opening, and none of these elements can be left out of consideration andfstill have a proper mixture. The temporary lowering of the vacuum by opening the throttle may allow rod I9 to move far enough so that lug 64 will no longer hold contacts 66 and 61 apart. To prevent their closing under this condition and thus operating the starting motor, sleeve 40, when the throttle is opened, moves finger 14 counter-clockwise and, by lug 16 on iinger 14, holds contacts 66 and 61 apart. It will thus be seen that the starting motor cannot be energized while the throttle is open and unless the vacuum is less than the firing vacuum.

If the engine while idling either hot or cold tends to stall, the vacuum immediately drops to a degree where diaphragm I9 is unable to overcome the resistance of spring 33, which immediately rotates lever 29, clockwise, thus opening the throttle valve and preventing stalling.

If the operator has before starting the engine, advanced the spark to a point where there is danger of the engine reversing upon starting, switch |02 is opened by finger |01 on timer head |09, thus breaking the starting circuit, or if the engine does reverse upon starting, switch |04 is opened by friction disc |09, breaking the starting circuit. Y

lli)

What i claim is:

i. An internal combustion engine having an intake manifold, a throttle valve and ignition means including a switch for the latter, a' starter motor for the internal combustion engine, means controlling the running of the starter motor and operation of said throttle valve sequentially by variations in pressure in the intake manifold of the engine caused by operation of the latter, a generator driven from the engine, and means independent and separate from said pressure actuated controlling means and affected in its operation by the amount of voltage generated by said generator for rendering said starter motor ineffective when the generator produces a voltage and upon drop of said voltage the starter motor control means is placed in condition for effective operation of the starter motor by the aforesaid variation in manifold pressure.I

2. An internal combustion engine having a starting motor, a valve whose position affects the fuel to the engine, means for operating said valve, means controlling the operation of said starting motor and operatively connected with the valve, means making the operation of the valve operating means dependent upon the intake manifold pressure, comprising an element acted upon by such pressure .whereby said valve operating means is automatically actuated, means responsive to engine temperature that affect the automatic operation of the valve operating means, said valve operating means being such that it may be manually operated to open said valve irrespective of its automatic operation, and manual means to modify the automatic action of the said last two mentioned means 'and actuating said starter control means to stop said starting motor.

3. An internal combustion engine having a starting motor, a carburetor having a choke valve and a throttle valve, valve moving means, an intake manifold pressure receiving element movable in one direction by such pressure and controlling said valve moving means, a plurality, of yielding resistances, an operative connection between each of the latter and said valve moving means, said resistances being arranged for successive action, and means for controlling the operation of said starter motor and arranged with respect to the valve moving means to be actuated by the latter for rendering the starter motor ineffective, when the engine is self-propelled, and for rendering the starter motor operative when the manifold pressure on the pressure receiving element is less than that produced by the normal self propulsion of the engine.Y

4. An internal combustion engine having an electric starting motor, a carburetor, a choke valve, a throttle valve, an electric circuit that includes the motor, a normally open starting switch in such circuit, a control circuit for operating said starter switch, an automatically operable normally closed switch in said control circuit, means to open the normally closed switch comprising a to and fro movable element subject to intake manifold pressure that is adapted to cause movements in the direction to open said normally closed switch, and operative connections between said member and said valves.

5. An internal combustion enginehaving an electricv starting motor, a carburetor, a choke valve, a throttle valve, an electric circuit that includes the motor, a normally open starting switch in such circuit, a control circuit for operating said starter switch an automatically operable normally closed switch in said control circuit, means to open the normally closed switch comprising a to and fro movable element subject to intake manifold pressure that is adapted to cause movements in the direction to open said normally closed switch, and operative connections between said member and said valves, including in the case of the choke valve temperature responsive means that controls the extent of opening of the choke valve, whereby such valve opens more when the engine is warm than when it is cold.

6. An internal combustion engine having a starting motor, means to put the motor at Work, a carburetor with a choke valve, engine-operated means that include a to and fro moving member subject to intake manifold pressure, a lever fixed to the choke valve, an operative connection between said member and lever, a stop for said lever movable relative to said lever, a thermostat operatively connected with said stop to move it relative to the lever, and means to stop the starting motor including an element movable to starting motor stopping position by said member.

7. An internal combustion engine having an electric starting motor, a carburetor, a choke valve, a' throttle valve, an electric circuit that includes the motor, a normally open starting switch in such circuit, a control circuit for operating said starting switch, an automatically operable normally closed switch in said control circuit, means to open the normally closed switch comprising a to and fro movable element subject to intake manifold pressure that is adapted to cause movements in the direction to open said normally closed switch, and operative connections between said member and said valves, a generator actuated from the engine, another normally closed switch in said control circuit, and means actuated by the voltage generated by said generator for opening said other switch, saidv other switch closing upon the drop in voltage produced by the generator.

8. In a vehicle, the combination of an engine, a fuel intake, a throttle valve in the fuel intake and normally positioned to furnish more than an idling fuel supply, a-starting motor and a control circuit therefore, a normally closed switch in said control circuit, whereby upon furnishing current to said circuit, said starting motor will operate; an engine-operated means for moving said throttle to an idling fuel supply position, said engineoperated means including means for opening said switch 4prior to the movement of said throttle to idling fuel position.

9. In a vehicle the combination set forth in claim 8 further characterized by a manually operable means for actuating said throttle, and means actuated by the manual opening of the throttle to prevent actuation of said starting motor.

10. In a vehicle, the combination as set forth in claim 8 further characterized by the engine actuated means being a device responsive to pressure variations in the engine manifold, manually operable means to actuate said throttle for accelerating the engine, and means for opening said Switch upon the manual operation of the throttle and to prevent closing thereof by the pressure responsive means due to pressure variations upon acceleration of the motor.

MYRON S. CURTIS.