USRE23497E - Starter jaw actuxtmeimexhanism i - Google Patents

Description

May 20, 1952 R. w. STELZEL STARTER JAW ACTUATING MECHANISM Original Filed Nov. '7.

INVENTOR.

' RODER/CK w. $54251. BY

Reissue c l May 20, 1952 Roderick W. Stelzel, Hohokfls,."N. "1.; .assignor to Bendix Aviation CorporationfTteibOrm-N. J..;' a corporationof Delaware" Original No. 2,572,532, datedO'ctober 23;.1951,'Se-- rial No. 125,923,, November 7', .1949. Applies..- tion for reissue February -18, 1952,-..Se'rial. No.

6 Claims.

Matter enclosed inheavy brackets appears intheoriginal-patent. hutsfo'rms :no ,part of this reissue-specification; matter printed initalics indicates."the-additions madeby reissue.-

The present invention-relates to engine starters and particularlyto starter jaw advancing mech-- :anism.

In engine starters some means are necessary to advance the starter jaw into engagement with the engine jaw upon energization of the starter.

One method used is a friction ring .in'contact with the starter jaw to hold the jaw momentarily against rotation-to enable the.:screw shaft and spline nut to .coactto move the jawinto. engagement. Also the frictionring serves to hold the starter jaw inwits retracted .position when v.the

engine .is' running; This method .has numerous disadvantages, someof-which are that. friction means are present duringthe operation of .the

, starter, the. friction ring becomes worn and. does not have sufficient frictionto holdthe jaw-against rotation and to hold the jaw in. its .retracted position ..when the engine is -running. This .is. especiallya disadvantage whensthe. starter is;

mounted with the :j aws downward as, is required in many installations; Also the. frictionmeans do not perform satisfactorily.when.low..temperaturesare encountered.

'Itis-anwobject 0f-m'y invention. to provide a positive j awadvancing mechanism. incorporating positive iholding means that will, overcomethe above difiiculties.

Another object .of' the. .invention isto. provide animproved-starter.

Another object .-is to :providean. improved starter for operation at low temperatures.

Another object is to provide an improved .jaw

. advancing. mechanism I for use. in engine starters.

Another object is-t0-pr0vide means -for-..pre-' venting. ;.the j aws from becomingengaged .by vibrationlwhen the. engine is running;

The above and other objects and featuresof the invention will. appear more :fully. hereinafter from. a-cons-iderationof the following. description taken. in connection with the... accompanying 1 drawings wherein. one embodiment of the inven- .tionis illustrated-by way of example In the drawing The single figure is .a sectional viewof .an.en-=

rginestarter embodying-one form of-the invention.

Referring to the drawing,v the device therein shown comprises a. starter assemblyincludin nm general, a motor-l havingadriving-shaft.2.rotatably supported by a bearing} mountedin .end

wall I of 1 motor housing 5.- A pinion -fi,.-:shown.as

integral .-with:-theshafti meshes-.withmlanet ears l.= The. planet-{gears .--'l are. rotatablysuppontedfiby .ball. bearings. :13 .mounted on:.=stub shafts .Sqcarm'ed 'z-hyaspider page; I 0. The. planetzgearsfl. jmeslrwithz :azring: gear I I, shown as. integral with .gearhousingr': I 2.; The Ig.ear.;honsingx12 is secured :to a the motor housing bystuds-l '3: and nuts. I 4 as shown or by other'suitable. means:

; Integral with the spider';-cag e-.lll-:isa 1pinion gear 3 ['5 adaptedto .engage'rplanet.gears-16 which also engage the ringgearJL: The: gears--l-5are :supported'by bearings i1 mounted .on 'stubshafts t8 "carried zbygawdrum.memberl9. The drum 10 .lmember' or barrel-His rotatably mountedvinrthe housing l2 byibearingifl.

The :barrel. i9 is :connected-Pforthe transmission of J rotary -motion to axially stationary-spline nut -12! :throughta torquemlimiting disc packi 21!.

:15 The disc pack 3:22. acomprises a plurality .of- "friction'fdiscs :alternately-zsphhed to;zthednnerfaoenof thefbarrelxlfi sand thepouter .face ofthe spline nut ;2 l The. discs of:- theapack 2-2: are forced into frictional engagement:- withveaohother-byza plurality of circumferentiallyspaced:springs 2-3 compressed :between: a flange-:24 onythe spline. nut "2 i :and an adj1istahle nut22ithreadcd into the. barrel -9 and .set so that "the .disc .pack 5:22 :will; slip -:at: a.pr.ede- .terminedtorque:

-25 The tlong lea-dcinternal=a threads of: i-the'spline The :piniongear :15 has :a :shaft 3 0 extending.

axially :therefrom intogthe .barrel. l9 Thexshaft .3fl1i5: sccured;to"the;gear: l.5 by ;a key- 31.01 111 any other suitable manner such -;as .isplines forarotation .:therewith.: The rshaft. 13.0 --.-terminates :in .an enlarged 'portiomorhead 1'12 and is. axially. positio'ned. by 'means :of ra:retaining-xring=-33 adapted 0 .-to:fit in. a groove" 34 inathe ishaft. "and thrust washers 35 'ipositionedz-between the head'z32 and the.-.radial .walll'of vthe:loarrel":i9: The'sscrew-s'haft 2 6 haszan: internally-helical "threaded portion 3 6 -:terminatingsin"a circumferential groove '31. The

.-.end of the screw -shafts adjacent-.to the groove 31 has a chamfer 3B. The; headi82chas a plurality ofii=holes 3 5.-'space'd. aroundtitscircumference and extending rradially :inwardthereof: The holes .39 :aret-so positioned. .invrelationrto :each other 59 that-the centers-lines-thereof' form arr-angle equal to gthe; pitch tangle s'of the helical .threaded por- --ti'on =36... .A-.-- ba1l-J.-l.ll-:.adaDted to mesh:-;with the .threaded;;nortion.-.36 .-is;secured.in-.-eachhole .39 :by peening the efilge emfzgthezhole35.0mm.anypther 3 radially outward into engagement with the threaded' portion 36. A plurality of balls 42 adapted to mesh with the circumferential groove 31 when the shaft 26 is in its retracted position are mounted in the head 32 in holes 43 spaced circumferentially around the head 32. The balls 42 are retained in the holes 43 by peening or in any other suitable manner. Springs 44 urge the balls 42 radially outward into operative position.

The clutch jaw 21 is retained in operative position relative to the screw shaft 35 by a mesh rod 45 secured to the clutch jaw 27 byanut 46. The mesh rod 45 extends axially into'the screw shaft 26 and terminates in a circumferential flange 41. A flange 48 of screw shaft 26 extending radially inwardly coacts with the flange 41 to limit the outward movement of the mesh rod 45. A spring 49 coaots with the flange 43 to bias the jaw 21 outward.

An oil seal 50 surrounds the outer circumfer- -ence of the clutch jaw 21 and is held in position by a bracket clamped between the flange 52 on the gear housing [2 and engine crank case 53 by means of studs 54 and nuts 55 or in any other suitable manner.

In operation, when the motor I is'energized rotary motion is imparted to the barrel I3 by means of the planetary gear system which includes the pinion The shaft 39 being keyed to the pinion I5 rotates therewith. The balls 45) coact with the helical threaded portion 36 providing a screw-like action which causes the balls 42 to be ratcheted out of circumferential groove 31, the force of the springs 4| being greater than that of the springs 44 and drives the screw shaft axially outward. This action is accelerated by the balls 42 pressing on the chamfer or ramp 38 thus giving the screw shaft a snap action. When the jaw 21 is in its engaged position, the balls 49 will have traveled out of the helical threaded portion 36 into the circumferential groove 31. The outward travel of the balls 40 being limited by the peening will have a clearance from the sides and bottom of the circumferential groove 37, thus eliminating all friction and dragof-these parts when the engine is being cranked. Should the jaws abut before meshing, the springs 41 will yield and permit the balls 40 to ratchet over the threads 36. Also undue resistance to axial movement of the starter jaw 21 will cause the balls 40 to ratchet in like manner. Inasmuch as the speed of rotation of the shaft 30 is greater than that of the barrel IS, the jaw 21 is moved into engagement with a relatively small amount of rotation of the barrel; The long lead splined connection between the spline nut 2| and the screw shaft 26 permits the 'screw shaft 26 to be pushed along the splines by the screw-like action of the connection between the shaft 30 and the screw shaft 26.

Upon the engine starting, the jaw 29 overrides the jaw 21 forcing it inward wherein the balls 40 will override the threads 36.- Upon the jaw 21 and screw shaft returning to the retracted position, the balls 42 engaged the groove 31 and prevent movement from the retracted position when the engine is running.

Thus a positive drive to effect axial movement of the screw shaft is provided which insures positive meshing under all conditions and also provide positive means for retainingthe jaw in its retracted position when the engine is running.

This last feature is desirable,-especially when the starter is mounted with the jaw downward as is necessary for some installations.

Although only one embodiment of the invention has been illustrated and described, various tionary rotatable spline nut, a screw shaft connected forlrotation with and axial movement relative to said spline nut, said screw shaft having an internally threaded portion, and an annular groove adjacent thereto, a shaft member concentric with and extending into said screw shaft, said shaft member having first ball receiving openings at spaced intervals. along a helical path corresponding to the pitch of said internally threaded portion, first balls positioned in said openings, first spring means for resiliently biasing said balls into engagement with said internally threaded portion, second ball receiving openings in said shaft spaced circumferentially around said shaft, second balls positioned in said second openings, second spring means for biasing said second balls into engagement with said annular groove to hold said screw shaft in a retracted position, said first spring means being greater than said last spring means whereby upon rotation of said shaft said screw shaft is actuated to an extended position. 7

2. The combination as defined in claim 1 and including a conical ramp portion of said screw shaft, said ramp portion being positioned to coact with said second spring biased balls when said screw shaft is in a partially extended posimember for actuating said screw shaft to-urge said starter jaw axially to an engine engaging position, yieldable means for drivably connecting said member to said screw shaft, said last means being adapted to release said connection when the opposition to axial movement of said starter jaw exceeds a predetermined maximum, holding means for retaining said screw shaft in a retracted position, saidlast means being adapted to yield in response to actuation of said screw shaft.

4. The combination as defined in claim 3 and including a ramp portion of said screw shaft adapted to coact with said holding means when said screw shaft is extended to aid linear movement of said screw shaft.

5. In an engine starter, the combination of an assembly comprising rotatable driving means, an axially stationary rotatable spline nut, a planet gear assembly for connecting said spline nut to said driving means, a screw shaft interposed in said splined nut and having mating splines thereon, a starter jaw member splined to said screw shaft for rotation and biased for axial movement therewith, said screw shaft having an internal helical threaded portion and an internal annular roove, a shaft member concentric with said screw shaft and extending therein, and connected to said driving means for rotation at a different rate than said spline nut, means including a plurality of spring biased balls associated with said shaft threaded portion to provide a screw action for moving said screw shaft axially to an engine engaging position, said spring bias balls being yieldable to permit ratcheting over said helical threads when opposition to said axial movement exceeds a predetermined maximum value, a second plurality of spring biased balls associated with said shaft member and adapted to engage said annular groove when said screw shaft is in a retracted position, said second spring biased balls being yieldable above a predetermined maximum.

6. [For use] The combination in an engine starter of the type having an axially stationary rotatably splined nut, a screw shaft splined to said spline nut for rotation with and axial movement relative thereto, a starter jaw connected for rotation with and yieldably biased for axial movement with said screw shaft; of [a] jaw advancing means comprising a screw shaft having an internal helical threaded portion. an internal annular groove portion and a ramp portion, a shaft member concentric with said screw shaft and having an enlarged portion extending therein, first yieldable means for connecting said screw shaft and said enlarged portion to provide a screw action for actuating said screw shaft axially to an extended position, second yieldable means for engaging said annular groove portion for retaining said screw shaft in a retracted position, said second yieldable means being adapted to yield to said screw action to permit linear movement of said screw shaft and to coaet with said ramp portion upon linear movement to provide a snap action to said screw shaft.

RODERICK W. STELZEL.

No references cited.

Images