US2511908A - Engine starter unit - Google Patents

Description

June 20, 1950 w. A. FoRBEss 2,511,908

ENGINE STARTER UNIT 2 Sheets-Sheet 1 Filed Oct. 29, 1947 INVENTOR. WALTER A. FORBESS BY z r nw A v-ra RNEV Patented June 20, 1950 ENGINE STARTER UNIT Walter A. Forbcss, Indianapolis, Ind., assignor, by mesne assignments, to The Marquette Metal Products Company, Cleveland, Ohio, a corporation of Ohio Application October 29, 1947, Serial No. 782,922

8 Claims. 1

This invention relates to a spring clutch device designed to provide, for example, an improved mechanism for effecting manual starting of internal combustion engines of the type used on small motor-boats and power machinery such as lawn-mowers, .cultivators, and the like, thus indicating the general object hereof.

Another object is to provide a simple and effective one-way driving and two-way overrunning clutch mechanism.

Hand starter mechanisms of the type shown hereby comprise a drive wheel which may be in the form of a sheave for a starting cord or chain or may be a pinion in mesh with a starter gear sector adapted to turn the engine crank shaft. The wheel has a one-way driving (e. g. ratchet) connection with the crank shaft for rotation thereof in the engine starting direction only; and, in more modern types, there is a retriever spring for the wheel to return the cord, chain or other operating means to initial position. The present invention resides principally in the illustrated clutch arrangement for associating the starter wheel with the engine crank shaft while enabling the crank shaft to overrun the wheel as the engine starts and to become instantly released from the wheel in the event of engine backfire, and also to allow free return of the wheel to initial position after each operation thereof. The above indicates further objects hereof.

Other objects include provision of a self-releasing overrunning clutch mechanism, particularly for engine starting purposes, wherein the mechanism is a self-contained clutch unit adapted to be positioned and/or supported on its working axis wholly by the shaft (e. g. engine crank shaft) with which the unit is associated, this phase of the invention including a simple and effective means for adjusting the clutch mechanism unit along the axis of such shaft to proper operating position and locking it firmly in such position by readily accessible and easily manipulatable means.

The invention further includes a special adaptation of the clutch unit, according to the object just outlined, for light duty internal combustion engines (e. g. outboard marine type) wherein certain necessary force reactance portions of the unit may be secured to the engine housing by light weight and simple attachment means requiring no precision connections with such hous- The present application'is a continuation-inpart of my prior application, Serial No. 743,252

2 filed April 23, 1947, which application has been abandoned in favor of the present one.

Other objects and features of the invention will become apparent from the following description of the preferred forms shown in the drawings.

In the drawings, Fig. 1 is a central sectional assembly view of an engine showing only a portion of the engine housing and crank shaftwith the starting mechanism hereof, in one form, mounted thereon. Fig. 2 is a sectional view taken on the line 2--2 of Fig. 1. Fig. 3 is a sectional view similar to Fig. 2 illustratin a modified form of friction spring. Fig. 4 is a central sectional assembly View of a modified form of the starting mechanism hereof.

Referring more particularly to Fig. l, the crankshaft I. has a keyed attaching taper for mounting a flywheel 2 thereon. The engine housing embodies a flanged portion 3 upon which is mounted an inner cover plate or spider memher 4, having a flanged hub portion 4a, and concentric of the crankshaft I. An attaching nut 5 is threaded to the top end of-crankshaft I, as at 6, forming a part of the starter clutch mechanism. The nut 5 may have top spanner sockets or other suitable means for engagement with a wrench. The nut 5 has a smooth, hardened cylindrical drum surface I which extends upwardly within a smooth internal drum surface 8 formed in the hub portion 4a of plate 4. These opposing radially-spaced drum surfaces 1 and 8 are concentric with the crankshaft. i

Mounted above and upon the plate member 4 is a hood or housing cap I0, secured to the engine housing by bolts or other suitable means. A central boss portion I2 of the hood rigidly and adjustably carries a vertical pilot stub shaft or pin I3, the lower reduced end of which freely enters a socket I4 formed in the top surface ofthe nut 5. The starter wheel 20 is in the form of a sheave having a peripheral slot 2| to receive a pull cord-or cable 22 which extends outwardly through a suitable aperture (not shown) in the housing cap I0 and terminates in a suitable grip or handle. The wheel has a' hub portion 23, the upper main part of which is centrally apertured to receive the pilot stub shaft or pin I3, the latter being mounted in said aperture on a bearing bushing 24 (cf. Fi 4, part 24). The bushing 24 is secured in lace in the hub by a snap ring 24'- and the bushing is internallythreaded to the pilot stub shaft for vertical adjustment of the wheel by turning of the stub shaft as will .be apparent. The bushing has a lower supporting shoulder 24" engagingthe wheel hub opposite the snap ring 26'. A lower end member 23' of the hub 23 may rest upon the top surface of nut 5 in light running contact therewith as determined by the adjustment of the stub shaft.

The wheel hub part 23 provides a smooth, cylindrical hardened external drum surface 25 having approximately the'same diameter as-the'drum surface I of the nut 5. Outwardly from the hub the wheel 20 is suitably formed to provide an attachment for a terminal eye 30 of a spiral re'.- trieving spring 3| which has another terminal eye on its opposite end attached in any suitable manner (not shown) to the housing. I01. Theispiral;

spring 3! returns the wheelZiDand cordor cable 22 to initial inactive position after each starting operation.

Bridging and surrounding the drumportions:lv and 25 of the nut and starter wheel hub respectively is a coiled clutch spring 40 which'is'nor mally prestrained into an expanded condition such, that the inside clutching faces 48a of the spring coilsdl which surround"; the drum are maintained out of contact therewith The coils 42 which surround the'wheel hu-b druinz 25 may be normally'intight engagement with said drum as :aiself-energizing torque-transmitting: attachment or may be normally'spaced therefrom; as desired; Intlieu ofsuch attachment, or in ad? dition thereto, as .a suitable means. forpositively. connecting the clutch spring with the: wheel so that. the :spring:always turns therewith; .the upper end'tof" the spring-may berformed. into a toe. ltxinserted into-an" axial opening. 44'. in the wheelEi]:

Lying outwardly" of. the eluted spring 40: and

supported for restrained rotationby:the 'non ro tating drum surface 8 of the plate member hub his an energizer member. in theuform of a sleeve 50'having atop flange 5| resting on the'topzedge ofrt'he' plate member: hubAa. The sleeve150 has a' smooth external circular surface conforming to the drum surface'il of "hub 4a within whichit is free'to rotate; The lower endof the sleeve'5fl: has-an inturned'flange 52 providing an axial support-forthe spring 40- and is provided with a radial notch; as at=5.3.'for'receivingan energizer toe'portion 45 of the clutch=spring.=-

A peripheral slot 54' is" formed in the outer surface of sleeve 5'0" for receivinga clutch ener gizingfrictionmeans shown in-Fig. 2 in'the form of F a generally curved leaf spring55 of the Marcel. 'or'wave type. There maybe more than one such spring per starter assembly andth'e design of Spring may bemodifiedas will be explaineds The-inner cylindricali surface 56 of sleeve 5!! retains the clutchspring against undesired outwardi uncoiling movement so" that regardless: of the amount of outward prestressin the clutch spring, the inner clutching-surfaces 40a Will be. maintained 1 very' closely-= spaced 1 radially with: ref? erence to the drum surface- 1 at all times while the starter wheel gis -notbeing operated and/or during normal operation of the engine. Thus the engine"cranh-shaft is always free to turn by engine power in either direction without restraint- Icy-the clutch, yet "the-:clut'clris in readiness for immediate non-lagging operation by"- the wheel 20-= inthe starting directionoffrotationthereof.

The spring member or members: 55'- located in the slot 54' of the energizer sleeveprovides or provide a. slight frictional drag 'thereon with rel'ation to the inner surface 8 of: the stationary. hub member ia, the amountt thereofbeing predetermined and governed by the design and resistanceito fi'exure on part of-theaspring employed;

The-spring 55- instead ofrbeing of the Marcel such that when the wheel 26 is turned in the necessary direction to start the engine, the restraintimposed-on-the clutching coils 4! through the intermediary of the spring 55, sleeve 56 and energizer'toe 45 will'cause the coils 4] to contract againstithe. drumsurface I progressively from the energizing end upwardly and along the spring. This clutch spring energizing principle is well known in spring clutches. The clutch is eelreleasing (or) upon return rotation of wheel 2!] by retriever spring 31,. (b) upon-overrunning of the engineshaftwhenthe engine starts, and (c) as will be-more'fully explained, upon counter-rotationcaused-by. backfire of the engine. When the clutch spring-2 isin gripping position, the coils thereof are out'of: contact with the inner surface of the sleeve fifl and in contact with both the drum surfaces I and: 25.- One or more of the clutch spring coils adjacent the energizer toe.45 may be reduced-incross section,-,as by.means of slotting at 46; tosincreasathe fieXi-bility,,hence delicacy of operationvof .the. energizing. coil or. coils:

Rotation-of. the .wheelv 20. inthe starting direction (clockwise. as. viewed fromlhe outer end of the orankshaft,, in. the structure illustrated) causesimmediate gripping of the drum surface I. so long, as.tensi-on.is maintained on the pull cord...22.. Assoon as the engine starts to operate under its.own power, thedrum surface 1 overrunsthe. clutch spring, the latter being sell-deenergizing due to the outward prestress in the coils 4i and inherent tendency of the clutch springto releaseload in one direction.

When engine backfire occurs, an instantaneoustorque is produced .on the rotating clutch unit and'starter. wheel 20 in a direction contrary to thetorque. being exerted by the operator on the starter'wheel, as through the, cord or cable 22. An extremely strong operator is'incapable of resisting the instantaneous jerk on the cable; and. the resulting momentary slackening of pull by the operator is always of sufiicient duration to enable the clutch spring to be de-energized, i. e., to expand to its normal prestressed condition out of-gripping relationship to the drum surface 'I of the: engine fiywheell Fig, 4 illustrates a modified form of engine starting mechanism-embodying the invention and in'operation and'general construction is similar to the form according to-Fig; 1. Similar-menibersand? par-ts are identified by the numerals heretoforeg-iven, tliedifierences in construction being pointed out and described below.

In themodified construction the starter wheel 20 and theclut'ch mechanismitself (except: for the fiywheel nut I05 whichserves as' the driven clutch drum) comprise: a self-sustaining unitary assemblyrwhichzis piloted foroperating location solely byi the:crank shaft: I, but is readily and bodily movableifor: assembly and? adjustment along the axis of i the crank shaft: Attachment of the unit in operating position requires no precisionmachining operations in. order to; enable the. engine and f starter assembly to: be substan'e asrnoos:

tially completedwith assurance that the princi pal clutch parts will be certainto befconcentric as required and fully operable without strain or wear.

The wheel bearing bushing 24 (essentially the same as in the previously. described construction) determines the plane of operation ofthe starter wheel through the connection of the bushing with the pilot stub shaft I I3. Asshown the lower, pilot end, of thestub shaft enters a'bearing bushing II6 fixed centrally in the-nut I05. The wheel in turn through a depending circular hollow skirt or flange portion I and'inside. lower snap ring I02 engaged in a peripheral slot interseating the inner bore IOI of the flange, supports the working parts of the clutch unit. The bore IOI contains, for easy rotation therewithin, a ring or sleeve I04 having circumferentially spaced tongues I08, the lower ends of which slidably rest on" the snap ring I02. The sleeve I04 is fixed against rotation to serve as a counterpart for the drumportion 4a of the plate or spider 4 of the previously described construction. In order to hold the sleeve I04 against turning relative to the engine housing a ring I01 having upstanding tongues mating with those of the sleeve'IM as splines extends upwardly within the skirt portion I00. The ring I01, below the skirt, has a radially extending arm portion I09 (partially shown) which may be secured in any suitable manner, not necessarily rigidly, to any appropriate part of the engine housing.

The top of the drum-forming ring or sleeve I04 supports the spring energizing and retaining sleeve I50 through contact with a top flange Il of said sleeve; and preferably the flange slightly clears the adjacent overhanging wall or web of the wheel 20 to avoid frictional contact with the wheel. The bottomfof the spring retainer sleeve I50 is flanged inwardly at I52 to provide a bottom support for the clutchspring, the flange being apertured to receive the energizer toe;45 of the spring. The bottom peripheral surface of the sleeve I50 is grooved to receive a snap ring III for holding the reactanc'e ring I01'and its arm I09 in operatingpos'ition and outof contact with the engine flywheel. The springretainer sleeve I50 is peripherally grooved to retain the drag spring 55 or 65 for operation as previously described and the clutch unit as a whole functions as does the unit of Figs. 1 to 3. The working parts are held concentrically of the crankshaft by their mutually telescoping arrangement as will be evident from Fig.4. 7

For the purpose of adjusting thevertical position of the clutch unit andto provide a lateralsupport for the upper endportioh' of the-stub shaft II 3 the top-end of thestub shaft has "a spherical formation I60 generally complementary to a socket I6I in a tubular metalpart I62 having a head or flange formation I63 with a rotationpreventing finger I64 thereon engaging a vertical slot in the bore I65 of the boss I2 of'the cover cap I0. Surmounting the flange I63 is a stubadjusting plate I61 having a tongue and slot connection at I68 with the spherical formation; I60. The plate andflange may be secured vjtogetl'ier after assembly on the spherica-lend of'the stub shaft, thus providing a universal adjusting head for said shaft.

After proper manipulation of the adjusting head assembly I62--I68 to secure free and effective operation of the clutch unit the stub shaft is then locked in adjusted position as by a single screw I69 extending through an eccentric hole 6, in adecorative cover cap I10 through aligned radial slots in the flange I63 and plate I61 into threaded engagement, selectively, with one of a series of openings I H (one shown) spaced circumferentially about. the boss I2 of the cover, beinglocated equal distances from the center of the boss. The adjusting and locking arrangement holds the top. end of the stub shaft II3 firmly without imposing any bending strain on it, thus cooperatingwith the pilot bushing I I6 in holding the wheel bushing 24 solidly in place. The only wear in the operation of the starter is between the bushing 24 and the starter wheel.

While the clutch spring as shown is of the internally gripping or contractingtype, the 'arrangement of parts may be reversed so that the drum surface carried bythe crank shaft lies outside the spring for expansion clutching action thereof, inwhich case the energizing element herein represented by the sleeve "50 would lie inside the spring against a suitable non-rotating external surface portion of the engine assembly with the friction spring 55 or 65 interposed therebetween.

I claim: v 1. In a starter mechanism for an internal combustion engine having a drum member fastened to the engine crank shaft, a driving member coaxial with and rotatable independently of said drum member, said mechanism comprising an overrunningself-releasing friction clutch means operatively connected to the driving member and normally out of contact with the drum but arranged to engage the same for starting the engine, a rotatable clutch-energizing unit including friction-operated rotation-restraining means coaxially of said driving member, the restraim'ng means of the clutch energizing unit becoming automatically operative to render. the clutch means effective consequent upon the driving member being rotated in its engine starting direction, the driving member, energizing unit and clutch means being maintained concentrically of the crank shaft principally by a pilot connection between the driving member and thecrankshaft.

2. In a starter mechanism for an internal combustion engine having a drum member arranged to turn the engine crank shaft, a driving member coaxial with and rotatable independently of said drnm member, said mechanism comprising an overrunning self-releasing spring clutch means operatively connected to the driving member and normally out of contact with the drum but arranged to engage the same for starting the errgine, a= rotatable clutch-energizing and clutch spring-containing sleeve member coaxially of said driving member, a non-rotatable sleeve member telescoping "the first mentioned sleeve member andjforming aradial bearing support therefor, a peripheral channel inone of the sleeve members and a normally non-circular leaf spring supported in'and' principally by the defining walls of the channel and operative to render the energizing sleevemember effective when the driving member isrotated in the engine starting 'direction of rotation thereof. 1

3. A clutch device adapted for use in an internal combustion -engine starter mechanism having a rotary driven drum member arranged to turn the engine crank shaft and a coaxial driving drum member rotatable independently of said driven drum member, said device comprising; a coiled clutch spring with coils embracing the driving drum member and anchored thereto at 7? one: end on the'Lrspring; the latter? having:- coils; tel'escoping-tbut normally? out of 1 contactwith :the: drivemdrunr, a clutchien'ergizingmember adapted; tovbe supportedfor frictionally resisting rotation' coaxia-ily with said? drurm membersby a non-- rotar-yi: member; said:' energizing; member being" connected to an: energizing-portion of" the spring: in: a manner to initiate=gripping of the. driven drum member by the: clutch spring consequent:-

uponrotation of the driving. drum. member. in: the engine; starting direction of rotation. thereof only; 4

4. Arspringe clutch" device. comprising. a driving. drum: and a coaxiahdrivene drum, both of. circular cross section, means. supporting. saiddrumsfor rotation-independently of.-each-other,-a coiled. clutch. spring; telescoping .bothdrums and. drivingly' anchored to the. driving. drum said. spring. havingr clutching. coils peripherally close to. but. prestressed out. of. clutching contact withth'e. driven drum, .an .energizersleeve of circular form. aroundthespring, telescoping the. same, andsupporting all.the. coils thereof which-lie. adjacent the driven drum concentric with the drivendrum and out of contact therewith, said sleeve being connected .with.a terminalcoil of the spring remotelyof. the. driving drum, and non-rotary. meanscontinuallyfrictional-1y restrainingthe .energizer. sleeve against. free turning movement, whereby the.sleeve acts to energizethe spring into .grippingcontact with. the driven drum when the.driving.drum-is.turned in.one direction but the. drivendrum. is free toturn in either. direction unrestrained by. the clutch.

5. A starterv mechanism for an internal combustion engine. having a crankshaft and supporting. housing, said. mechanism comprising. a circular nutthreaded on the free end of the cranleshaft, a circular member connected with thelhousinglinlamanner to preventlthe member from.turning, said member. lying in surrounding and spaced. relation to the nut,.a. starter wheel havinga circular hub. portion extending approximately intoabutment with the outer. end of the nut, .a coiled clutch spring bridgingthehub por-:, tion andnut, .said spring being connected 'at one end to. the wheel to turn alwaystherewith and. having, clutching coils prestressed. out of clutchrelation to thenut, .and] a sleeve frictionally mounted. within said circular member and connected withthe opposite end of the spring to energize the spring into clutching relation to the nut when the wheel is turned in the enginestari. 1g direction.

6. A- starter" mechanism" for an internal combustion enginehaving' a crank shaft and sup porting housing, said mechanism comprising a circular nut threaded on the free end of" the crank shaft, a circular non-rotating 'ring connected' with the" housing surrounding and in spaced relation'to the nut; a starter wheelh'aving a hub portion extending'sub'stantially into abutment with the outer end ofthe' nut-and: approx ima'tely of "the" same diameter as the nut; a coiled clutch spring bridging J the hub" portion and nut; said spring being co rot'atively"connected with the wheel and having clutching coilsfprestressedr out of clutching relation to the nut; a sleeve mounted within said circular. ring 1 and connected".

With'l the: opposite: end: of: the"- clutch: spring. to? energizesaidlspring intoficlutchingrelation t'o the: nutiwhen the wheelis .turnedin the engine tstart ing direction, and friction detent means between said sleeve: and isa'id :circular ring lying and contained; im ai continuous peripheral groove in one ofithose'elementsf'-for= resisting rotation of said. sleeve: with i relationtto said ring.

7: Nmanualtypestart'en mechanism for an=in-' ternal: combustion engine: having a crankshaft and? supporting: housing, said' mechanism com prising a".rotatablesstarter member having a hub portloneaiitnreadedf stub'shaft extending through the-huhportion; a; bearing sleeve-for the starter membenon the stubishaft threads and connected tovth'erhub so' thata'xial'movement of the sleeve" axially adjustsf-theihub'in reference to the crankshaft, a pilot I connection between the stub shaft and crankshaftiso." that the. latter radially sup ports one end ofwthe stub shaft,= adjusting means on! the housing,- connected to the stub shaft for holding it against-turning, means providing acir-' cula'r clutch drumi surface co-rotative with the crankshaft; a helical-clutchspring connected at. oneend': with the=starten member and surround-- ing but normally-kout ofl clutching contactwiththeudrumi surface; an=energizer sleeve around-the clutch spring and-connected to its-opposite end,- and means supportingtheenergizer sleeve for 'rotation: concentricr with-the clutch spring while frictionallyi restraining'rotation of the sleeve to 1 cause the clutch spring -toygrip-thev drum surface. whernthe. startermember isturned in the engine starting directions- 8'. A starter-1 mechanism for aninternal combustiomengine havingza crankshaft andsupporting housing; means" providing. a circular clutch drum? surface on. and-concentric with the crank shaft',--astubishaftadapted for operativeengagement with the crankshaft for radial support, means for: connecting thestub shaft to the .hous-- in'g,. atstartert member rotatably carried bythe: stub shaft, a-circularflange. onthe starter member: coneentrice with the stub shaft; a circularv drum lmemberl radiallysupported by: thercircularl flange 1 and adapted forconnection to. the housing? for preventing rotation of the drum member, ahelical .clutch spring: generallyconcentric with and normally out of: contact with the drum surF face. of saidlfirstmentioned means but frictionallyengageable therewith, one end of theclutchspringbeing co-rotative with the starter member inlthe.engine-startingdirection-oflrotation thereof, energizing-means for: the spring connectedtoits? opposite. end 4 and operativelyassociated frictionally with the drum-memberfor causing the spring-to grip said drum. surface'of. said. firstmentionedrmeans, and turnthe crankshaft.

WALTER. A. FORBESS.

REFERENCES" CITED 'I h'er following: referencesr are of record'- in. the fileF-Of thlsipaitenti; v

onrrnn STATES PATENTS" Number.- Name; Date.

1361;584- Readelier etlalI. Junefl, 1932' 1,985,126 Wemp Dec. 18, 1934 2;004',650 CollyearletIalI June 11', 1935'

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