US1727793A - Starter for automobiles - Google Patents

Description

Sept. 10, 1929.

w. c. STARKEY STARTER FOR- AUTOMOBILES Original Filed May l6, 1925 abtomag Patented Sept. 10, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM CARLETON STAIRKEY, OF INDIANAPOLIS, INDIANA, A$SIGNOR TO L. G. B. DEVICES CORPORATION, OF INDIANAPOLIS, INDIANA, A CORPORATION OF INDIANA.

STARTER FOR AUTOMOBILES.

Original application flled lay 16, 1925,

It is the object of my invention to provide a simple and efiicient starting drive for an internal combustion engine, as of an automoile. More specifically, it is the object of my invention to provide between a starter motor and such an engine a releasable drive which will eliminate strains incident to drives now in common use, by producing a releasable meshing of the motor-driven pinion with a gear on the engine shaft before the motor has gained momentum; which will permit the free overrunning of the motor-driven pinion when the engine starts in operation under its de-meshed from the engine gear; and which desirably will permit a release of the drive upon excess stress even in the driving direction, so that if a backfire of the engine occurs the starter motor may continue to rotate in its normal or forward direction and thus the strain which is ordinarily put. upon the starter motor and other parts upon a backfire is eliminated.

In attaining these objects, I mount on a shaft driven by the starter motor an axially shiftable pinion which by its axial movement may be meshed with and de-meshed from a gear on the engine; and provide this pinion as part of a unit which is shiftable in its entirety along the starter-motor-driven shaft and which preferably embodies a special form of coiled-spring clutch which transmits power from the starter-motor-driven shaft to the pinion in one direction while permitting free overrunning of the pinion when necessary; and desirably make this coiledspring clutch of such character that the stress which it transmits even in one direction from the starter-motor-driven shaft to the pinion is limited in amount, so that when such stress tends to exceed that amount the clutch releases itself and permits free relative rotation of the pinion and the starter-motor-drivon shaft even in the direction in which the driving stress is normally transmitted.

The unit consisting of the pinion and the member splined on the starter-motor-driven shaft is desirably interassociated with the own power, until the motor-driven pinionis starter-motor switch so that the movement Serial No. 30,762. Divided and this application filed latch 15, 1926. Serial No. 94,728.

of the switch shifts such unit. The startermotor switch is so arranged that such shifting normally occurs to produce meshing of v the starter-motor-driven pinion and engine gear before the starter-motor-shaft is closed; 5 but allows the closing of the switch first if the teeth of such pinion and ear at any time happen to be so nearly in irect alinement that the pinion teeth cannot enter the spaces between the gear teeth, as sometimes occurs.

I prefer to employ the form of clutch illustrated and described to connect together the pinion and the members splined on the starter-motor-driven shaft, but this particular form of clutch is not essential to my present invention in its broader aspect. The particular form of coil-spring clutch illustrated and described in this application forms the subject-matter of the claims of my co-pending patent application Serial No. 30,7 62, filed May 16, 1925, Patent No. 1,617,775, of which this application is a division.

The accompanying drawing illustrates my invention: Fig. 1 is a side elevation of a start ing drive embodying my invention, some of 7 the parts being broken away or in section in order better to illustrate the construction; Fig. 2 is an enlarged longitudinal section through the drive itself, to show the coiled- I spring clutch and the associated parts; Fig. 3 is a section on the line 33 of Fig. 2; Fig. 4-. is an elevation of the coiled spnn of the clutch; Fig. 5 is a longitudinal section similar to Fig. 4, with a coiled spring of material of smaller cross-section, by reason of which slipping may occur on excess load even in the direction in which power is normally transmitted; and Fig. 6 is a sectional detail of the shifter switch. 1

The engine 10 may have-the usual fly-wheel 11, on which is the usual ring-gear 12. The engine 10 may be any type of internal combustion engine; it is shown as an automobile engine, associated with a well-known type of transmission device 13, controlled b pedals 14 which project through the floor card 15 of the drivers compartment of the automobile.

The starter motor 16 may also be of an suitable or convenient-construction, and 18 I supplied with current from a battery 17, as is I may also serve as a limit-stop to limit the movement in one direction of the drive unit along the shaft 18.

The engine and-starter motor, per se, may be of any standard or desirable construction.

On the projecting end of the starter-motordriven shaft 18 I mount my improved drive unit. This consists fundamentally of two parts and 21, which may move together axially as a unit, but under some circumstances are fixed relatively to each other to rotate together as a unit while under other circumstances they may rotate relatively to each other.

The member 20 is loose on the startermotor-driven shaft 18, so that it is free both to slide thereon and to rotate thereon. This member 20 is provided with pinion teeth 22 'Ywhich may co-operate with the teeth of the ring-gear 12. Under normal conditions the pinion 22 is in the position shown in full lines in Fig. 2, so that it is out of the plane of the ring-gear 12 and so is de-meshed therefrom.

When the drive-unit 2021 is shifted forward on the shaft 18, however, the pinion teeth 22 are broughtinto mesh with the teeth of the ring-gear 12, as is indicated in dotted lines in Fig. 2; the bearing 19 may serve as a limitstop to limit this forward movement of the drive unit. The forward ends of the pinion teeth 22 are'desirably beveled, to facilitate meshing with the teeth of the ring-gear 12, a'nd the entrance ends of the ring-gear teeth may be similarly beveled if desired; as is against relative axial movement other than is suflicle'nt for clearance.

standard drives.

construction in starter-motor The member 21 of the drive unit is asso- ,ciated with the starter-motor-driven shaft 18, as bysplines23, so that it cannot turn relatively to said shaft but may be shifted along the shaft. This longitudinal shifting is always of the two members 20 and 21 as a unit, for they are interlocked in any suitable way This interlocking against relative axial movement may be obtained in any convenient way, as by having the rear end of the member 20 telescoped within the forward end of the member 21, and interlocked against separation by a split retainer ring 24 suitably located in a circum ferential groove on the inside of the hollow open forward end of the member 21., v

The shaft 18 of the The two members 20 and 21 are connected by an overrunning clutch preferably of the type claimed in my aforesaid prior patent application in which the two members 20 and 21 have mating circular recesses 26 and 27 in their abutting ends. A coiled clutch-spring 28 is located in these recesses, and extends across the transverse plane of separation between the two members 20 and 21 and into both recesses 26 and 27. The outer surface of this clutch-spring 28 is in frictional cooperation with the internal surfaces of the recesses 26 and 27. In consequence, when there is a tendency to rotate the two members 20 and 21 in one direction with relation to each other, the friction of the recess walls on the outer surface of the clutch-spring tends to unwind such clutch-spring and force the clutch-spring surface more tightly into engagement with the walls of the recesses 26 and 27, thus locking the two members 20 and 21 together against relative rotation in that direction; whereas when there is a tendency to rotate such two- members 20 and 21 in the other direction with relation to each other, the friction of the recess walls on the outer surface of the clutch-spring tends to wind up said clutch spring more tightly, and thus releases the two members 20 and 21 from the clutch-spring and so from each other and permits relative rotation between said two members in that direction. The locking together of the two members 20 and 21 by the clutch-spring 28 is when the starter motor 16 is turning in the proper direction to start the engine 10, or clockwise in Fig. 3, and the engine is resisting such turning, as by its friction and compression; while the releasing of the two members for relative rotation between them occurs when the speed of the shaft 18 is less than the speed at which the pinion 22 is turned by the ring-gear 12 after the engine has started in operation under its own power; the coiled-spring clutch in the latter case permitting overrunning of the member 20 with respect to the member 21.

.For shifting the driveunit 2021 axially, I provide a shifter fork 30, which has inwardly projecting pins 31 which project into a circumferential groove 32 in one of the members 20 or 21; the groove 32 is probably most conveniently provided in the member 21, as illustrated. The shifter fork 30 may be hung on a suitable pivot 83, and is connected by a link 34 to the downwardly extending arm of a bell-crank 35. The rearwardly extending arm of such bell-crank 35 lies beneath and normally substanatially in contact with a pin 36 carried by a shifter switch 37.

This shifter switch, in the form shown, con- J sists of a tube 38 slidably mountedin a casing 39 and carrying at its lower end a crossconnector 40 for connecting two switch contacts 41 and 42 which are connected by con ductors' 43 and 44 to the battery 17 and the starter motor 16 in the usual way, the other terminals of such battery and starter motor being grounded. The head 45 at the upper end of the pin 36 lies within the tube 38, and is held from downward movement out of said tube by an inturned flange 46 at the lower 38 is depressed the cross-connector 40 does not engage the switch contacts 41 and 42 until after there has been sufficient movement of the tube 38 normally to produce meshing of the pinion 22 with the ring-gear 12, The downward movement of the tube 38 and pin 36, and the meshing-producing movement of the drive unit 21, are opposed by a spring 48, which when the operators heel is released from the shifter switch 37 acts to raise such shifter switch and to withdraw the drive unit from mesh with the ring-gear 12. This spring 48 is shown, for example, as a tension spring acting on the depending arm of the bell-crank but this is merely a convenient arrangement for the spring, and not a necessary one.

In normal operation, the parts are in the position shown in Fig. 1 and in full lines in Fig. 2. The pinion 22 is outof mesh with the ring-gear 12. This is the condition when all the partsare at rest, and also when the engine 10 is in normal operation.

When, with the engine 10 at rest, it is desired to start such engine, the operator steps on the shifter switch 37. The resultant depression of the tube 38and pin 36 acts to turn the bell-crank 35 against the spring 48, and to shift the drive unit 20-21 forward, or to the left in Figs. 1 and 2, to the dottedline position shown in Fig. 2. This produces meshing of the pinion 22 with the ring-gear 12; unless the pinion teeth and the ring-gear teeth happen to register substantially exactly so that the entry of the pinion teeth into the spaces-between the ring-gear teeth is prevented. In the latter case, the ends of the pinion teeth and the ring-gear teeth bear against each other, and the spring 47 is compressed to let the tube 38 descend even though the pin 36 is held from descending. The

bevels on the ends of the teeth tend to promote meshing of the teeth; and such bevels are desirably in the proper direction that their camming action on each other tends to rotate the member 20 in the direction in which the spring 28 permits it to turn freely.

. At the last part of the downward movement of the shifter switch, the cross-connector 40 I engages the switch contacts 41 and 42 to complete the starter-motor circuit; whereupon the pinion and ring-gear happen to have regother. Thus the teeth of the pinion and ring under its own power, the ring-gear 12 starts the starter motor starts at once to rotate. Ordinarily this starter-motor rotation does not start until after the pinion teeth and gear teeth are fully in mesh; but if the teeth of istered so that such meshing has been prevented, the meshing occurs as soon as the starter motor has turned the pinion 28 half a tooth-pitch, as by that time the spring 47, which is stronger than the spring 48, will have expanded to force down the pin 36 and move the drive unit forward as soon as the pinion teeth and the ring-gear teeth have been moved slightly out of line with each gear, as well as all the other parts, are prevented from receiving the shock which occurs in certain present-day drives, because the meshing of the teeth occurs before the pinion has gained any material amount of speed.

Upon the startmg of the starter motor 16, with the teeth of the pinion and ring-gear already in mesh, or in mesh within half a tooth-space, power is transmitted from the starter-motor-driven shaft 18 and member 21 through the clutch-spring 28 to the member 20 in such a direction that the friction of the parts tends to unwind the clutch-spring 28. This looks the two parts 20 and 21 togethcr; and the power thus received by the member 20 is transmitted by its pinion teeth 22 to the ring-gear 12, to turn over the engine 10.

As soon as the engine 10 starts to operate to rotate more rapidly than while it was being driven by the starter motor, and drives the pinion 22 and part 20 with correspondingly increased speed. In consequence, the member 20 runs ahead of the member 21; which is permitted because this tendency to relative rotation between the parts 20 and 21 tends to wind up the clutch-spring 28 and thus to release it from such members to permit such relative rotation in that direction. Ordinarily as soon as this occurs, the operator releases the shifter switch 37, whereupon the spring 48 raises such shifter switch and moves the drive unit to the rear (or to the right in Figs. 1 and 2) to the full-line position shown, to de-mesh the pinion teeth 22 from the ring-gear 12. However, if the operator fails to do this immediately, no harm ensues, because the interaction of the clutchspring 28 with the recesses 26 and 27 permits the free overrunning of the member 20 ahead of the member 21.

In case of a backfire of the engine 10 as it is being started, power is transmitted from the member 20 to the member 21 tending to drive the starter motor 16 backward; for with this back drive of the member 20 upon a backfire there is the same clutch-springunwinding tendency to relative rotation between the members 20 and 21 as there is when power is transmitted for said driving from the member 21 to the member 20. This may put a great strain on the parts, particularly on the starter motor. I may avoid this, however, by making the cross-section of the clutch-spring 28 smaller, as is indicated in Fig. 5, so that it has less ability to transmit power. That is, I have found by experiment that by making the clutch-spring 28 of smaller cross-section, its capacity to transmit power even in the spring-unwinding direction is thereby reduced; and, as a result, the capacity of the clutch spring to transmit power even in the spring-unwinding direction may be reduced to a point below that which is reached upon a backfire of the engine, with the result that though the member 20 may turn backward the starter motor itself and its shaft 18 and the member 21 may continue to rotate forward. This reduction in crosssectional area of the clutch-spring 28 will depend upon its diameter, upon the size of the engine, and upon the power of the starter motor, and will vary with different installations. \Vhether with or without the reduced cross-sectional area, it is not essential that the individual turns of the clutch-spring 28 should be square, although it is illustrated as square in Fig. 2, as such cross-section may take other shapes as desired.

I claim as my invention 2- l. A. starter drive, comprising a startermotor-driven shaft, apower-receiving gear connected with an internal combustion engine, a pinion shiftable into and out of mesh with said power-receiving gear, a driving connection between said shaft and said pinion, said driving connection including an overrunning clutch, a switch for controlling the circuit of-thestarter motor, and a yieldable inion-shifting connection between said switch and said pinion whereby opening and closing of the switch produces shifting of the pinion.

2. A starter drive, comprising a startermotor-driven shaft, a power-receiving gear connected with an internal combustion engine, a pinion shiftable axially into and out of mesh with said power-receiving gear, a driving connection between said shaft and said pinion, said driving connection including an overrunning clutch, a switch for controlling the circuit of the starter motor, and a yieldable pinion-shifting connection between said switch and said pinlon whereby opening and closing of the switch produces shifting of the pinion.

3. "A starter drive, comprising a startermotor-driven shaft, 3. member slidable thereon but rotatable therewith, a pinion slidable as a unit with said member, an overrunning clutch between said member and said pinion, a power-receiving gear connected with an internal combustion engine and into and out of mesh with which said pinion is movable by the sliding of siiid member, a switch for controlling the circuit of the starterimotor, and a yieldable pinion-shifting connection between said switch and said member whereby opening and closing of the switch produces shifting of said member and pinion.

4. A- starter drive, comprising a startermotor-driven shaft, a power-receiving gear connected with an internal combustion engine, a member connected with said shaft to rotate therewith, a pinion associated with said member, a coil-spring for clutching together said pinion and said member, said coil spring being in operative engagement with one of said'parts and extending into an axial recess in the other of such parts so that it will expand to grip the walls of such recess when said pinion and said member tend to rotate relatively in a direction to unwind said spring, saidmember and said pinion being shiftable as a unit to move the pinion into and out of mesh with said powerreceiving gear, and a pinion-shifting connection between said switch and said pinion whereby opening and closing of the switch produces shifting of the pinion.

' 5. A starterdrive, comprising a starter motor-driven shaft, a power-receiving gear connected with an internal combustion engine, a member connected with said shaft to rotate therewith, a pinion associated with said member, a coil-spring for clutching together said pinion and said member, said coil spring being in operative engagement with one of said parts and extending into an axial recess in the other of such parts so that it will expand to grip the walls of such recess when said pinion and said member tend to rotate relatively in a direction to unwind said spring, said member andsaid pinion being shiftable as a unit axially of said shaft to move the pinion into and out of mesh with said powerreceiving gear, and a pinion-shifting connec tion between said switch and said pinion whereby opening and closing of the switch produces shifting of the pinion.

6.. A starter drive, comprising a starter motor-driven shaft, a power-receiving gear connected with an internal combustion engine, a member connected with said shaft to rotate therewith, a pinion associated with said member, a coil-springfor clutching together said pinion and said member, said coil spring being in operative engagement with one of said parts and extending into an axial recess in the other ofsuchparts so that it will expand to grip the walls of such recess when said pinion and said member tend to rotate relatively in a direction to unwind said spring, said member and said pinion being shiftable as a unit to move the pinion into and out of mesh with said power-receiving gear, and a yieldable pinion-shifting connection between said switch and said pinion whereby opening and 4 o mitting devices in series, one

closing of the switch produces shifting of the pinion.

7 A starter drive, comprising a startermotor-driven shaft, a power-receiving gear connected with an internal combustion engine, a pinion shiftable into and out of mesh with said power-receiving gear, a driving connection between said shaft and said pinion, said driving connection including an overrunning 10 friction clutch'directly co-o erating with said pinion, a switch-for controlling the circuit of the starter motor, and a pinion-shifting connection between said switch and said pinion whereby opening and closing of the switch produces shifting of the pinion.

8. A starter drive as set forth in claim 4, with the addition that said helical clutchspring is arranged to release its grip when the force between the two parts it connects exceeds a certain maximum less than that produced on the backfire of the engine.

9. A starter drive as set forth in claim 3, with the addition that the driving connec- .tion between said shaft and said pinion ineludes two associated parts arranged to transmit power from one to the other when the force'between them in one direction does not exceed a certain maximum less than that produced on the backfire of the engine but to move relatively to each other without transmitting power both when the force between them exceeds such maximum in such one direction and when the force between them is in the opposite direction.

10. Incombination, an internalcombustion engine, a starter motor therefor, and a driving train for interconnecting said starter motor to said internal combustion engine, said driving train comprising two fpower-trans said powertransmitting devices including two members and a helical spring interconnecting said two members and frictionally gripping both of. them on curved surfaces and the other powertransmitting device including two members which can be moved into and out of engagement with each othef, a switch for controlling the operation of said starter motor, and operating means connecting said switch with one 7 of said two members for producing their engagement and disengagement when the switch is operated.

In witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this 3d day of March, A. D. one thousand nine hundred and twenty-six.

WILLIAM OARLETON STARKEY.

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