US1874841A - Engine starter - Google Patents

Description

Aug. 30, 1932. ABELL 1,874,841

ENGINE STARTER Filed Oct. 25, 1928 1 NV EN TOR.

ddm 7? I 5 ATTORNEY,

Patented Aug. 30, 1932 UNITED STATES aoLLm arms, or xmrox, ilassacnusms PATENT ,0

FFICE I ENGINE STARTER Application filed October 33,1988; Serial Io. 814,505.

stages of rotative motion of the starting motor.

In commercial engine starters of the t pe above mentioned, the motive power is ur-.

nished by electric motors that have exceedingly rapid acceleration, so rapid in fact that the teeth of the starting pinions and the engine gears with which the pinions cooperate are subjected to violent impacts when'their end faces butt one against another as the pinion moves axially toward its operative position. When tooth-butting occurs it is commonly followed by clashing of the pinion and the engine gear, in the course of which the pinion takes on the accelerative rotation of the starting motor so quickly that the teeth of the pinion, instead of working into the spaces between the teeth of the engine gear, ride over the ends of the latter teeth and cause mutilation of the teeth. Various devices have been proposed to avoid mutilation of the teeth from this cause but they have not proved to be entirely satisfactory for one reason or another. y Y

Again, even when the pinion of an engine starter goes into mesh with an engine gear without causing any mutilation of the teeth, the train of mechanism is subjected to a sudden and violent strain at the instant of picking up the load and also, in some cases,-when back-firing of the engine occurs, unless some yielding or cushioning connection is interposed between the starting motor and the startin pinion. Various devices have here tofore been proposed to relieve this condition but they too have not been entirely satisfactory.

With the foregoing considerations in view,

insure prompt meshing of the starting pinan object of the present invention is to pro-1 ion and the engine gear followin toothbutting, so that the teeth of the pinion will not overrun the teeth of the e e gear. Another object of theinvention is to Brovide an improved engine starter that wi be relatively quiet in operation, evenin the event of momentary arresting-of the starting pinion by the teeth of the engine gear when the pinion is moving from its initial position to its operative position. y

Still another object of the invention is to provide an improved enginestarter that will yield sufliciently, when occasion requires, to relieve the starting motor and its shaft from excessive or injurious stresses at the instant of picking u the load and at times when backring of t eengine occurs. y

To these ends a novel feature of the 'inven-. .tion consists 'in an axialiy blage comprising essentia y two cooperative friction clutch members of which the driven movable assemmember is provided with .a starting pinion,

the formation and arrangement of the parts forming the clutch being such that they are forced with increasing ressure one against the other as the assemb a'ge moves from its initial position to its operative position. As j shown, the axially movable assemble is opposed, in its movement from its initial position to its operative ition, by a compression spring arrange to develop increasing drivin power of the clutch parts. This spring 1s preferably under no initial compresman, its complete relaxation, when the assemblage is out of gear, bein desirable to prolong its resilient life, to acilitate declutch-' ing when the assemblage moves out of gear after efl'ecting operation of the 0 inc, and to facilitate the first stages of axial movement of the assemblage when the latter is set in operation to start the engine. 7

In the illustrated construction'the spring abovereferred to is'also utilized, to return than that of the starting motor. Moreover,

provision is made for utilizing the repelling action of this spring to guard against demeshing of the pinion when, for example, the expansive action of unfired compressed gases in the cylinders of the engine causes pulsating rotation of the engine gear prior to actual eration of the engine under its own power.

This cam is provided with two distinct operative faces arranged in stepped relation, thefirst of which has a sufficient range of action to shift the starting pinion from its inoperative position to its operative position. and

- the second of which is effective to apply supplemental increments of clutching force to the members of the aforesaid cone clutch and thereby to develop the clutching power in proportion to the resistance of the engine to the starting effort. i

I Referring to the drawing, 1

Fig. 1 is a side elevation of an engine starter embodying theseveral features of the present invention, the parts being shown in their initial or inoperative positions, relative to a gear of'an internal combustion engme; f

. Fig.2 illustrates the starting mechanism in longitudinal section, and in this figure also the parts stand in their initial or inoperative. positions; v V Fig. 3 is a side elevation of one of the parts comprisin the startingpinion and the driven member 0 the friction clutch;

. Fi 4-is an end elevation of the part shown in F1g.3;" I

- Fig. 5 is a development of a portion of the cam member which is also the'driving mem-. ber of the friction clutch; and

Fig. 6 is an elevation of a resilient wire ring for locking'the set screw by which the operating member of the starting mechanism is secured to'the shaft of the startin motor.

The element indicated at 10 in fig. 1 is a portion of the casin of an electric starting motor, this element urnishing a bearing for a starting shaft 12 such as the armature shaft of the motor. The element indicated at 14 in F igs.'1 and 2 represents a portion of the fly-Wheel of an internal combustion engine,

and the element indicated at 16 represents a portion of a'spur gear carried by the flywheel. The starting shaft 12 projects past the engine gear 16 to support the elements of the'autom'atic starting mechanism hereinafter described. The, outboard end of the shaft 12 is provided with a shoulder 18 and with a smooth, cylindric extension 20 of smaller diameter than the main body of the shaft. 2 An 0 erating unit 22 is fixed to the outer end of t e extension 20 bya key 24 and a set screw 26, the key being arranged to transmit rotation of 'pression spring 46 and by:

the shaft to the unit 22, and the set screw being arranged to prevent axial movement of the unit 22. For the latter purpose a socket 28 (Fig. 2) is formed in one side of the extension 20 to receive the inner end of the set screw. The unit 22 comprises a hub or sleeve portion and preferably two diametrically opposite lugs or stud portions 30, 30 projecting radially therefrom. The hub portion of the unit 22 is provided with a circumferential groove in register with the set screw 26, the purpose of the groove bein to receive a split locking ring 32 (Fig. 6) o resilient wire for holdin' the set screw, against unscrewing. The wire of which the ring 32 is made is of a'size to occupy a screw-driver slot formed in the outer end of the set screw.

The lugs or studs 30 formed on the operating unit 22 are preferably cylindric in form. They cooperate with cam surfaces formed on a sleeve 34. This sleeve is one member of an axially movable assemblage that also includes an inner sleeve 36. The sleeve 36 is provided at one end with spur teeth forming a starting pinion 38 and at the other end with a coneshaped portion 40 that constitutes the driven part of a frictional cone clutch. One end of .the sleeve 34 surrounds thecone portion 40 and is provided with an internal cone-shaped surface 42 to rovide a friction clutch by which rotation 1s transmitted from the sleeve 34 to the sleeve 36. The two members of'the cone clutch are maintained in the nested relation shown in Fig. 2 by springs hereinafter described. i

The driven member 36 of the clutch is bored at its outboard end to receive the extension 20 of the starting shaft and is counterbored.

to provide a chamber 44. The inboard end of the sleeve 36 is supported by a lar er poratively to the shaft, and also to provide for relative rotation of this sleeve and the shaft.

It is to be observed that the pinion portion of the sleeve 36 always bears on the larger portion of the shaft 12 and is not only centered thereby throughout the axial travel of the sleeve but is braced thereby against transaxial stresses brought into play by the tendency of the pinion teeth to recede from the engine ear .16 under rotational effort. This utilizatlon of the larger portion of the shaft to sustain the trans-axial stresses is especially desirable to relieve the relatively slender extension 20 from the common causes of bending, of which backfiringis one. The chamber 44 is occupied by a relatively strong comrelatively weak compression spring 48, th of which encircle the extension 20. A flanged washer 5,0 is preferably interposed between the two springs to engage the shoulder 52 of the sleeve 36 and thereby put the heavy spring 46 light spring 48 to heavy stress. The washer is freeto slide axially on the extension and nevertheless eifectiveto maintain the pinionv 38 out of contact with the engine gear 16 and to prevent end-shake of the driving member 34 and the driven member 36 of the clutch.

is The member 34of the axially movable assemblage is provided with duplicate cam surfaces to cooperate respectively with the lugs or studs 30. Each of these cam surfaces, as

shown, comprises two inclined steps 54 and ion 38 from its inoperativeposition to its operanve position in meshed relationwith the engine gear 16, and also to apply a consid-v erable rotative effort to the pinion through the members that form the clutch. The step 56 iseflective to develop supplemental pressure of the clutch membersone against the other after the pinion 38 has been shifted to its operative position. The break or landing between the steps 54 and 56 of the cam includes a convex hump or shoulder '58 and a concave depression 60. l The two steps of the.

cam are inclined in the same. general direction but are offset from alinement wlth each other, the hump 58 and the depression 60 pro-' viding a surface of ogee curvature connecting .the steps to lead the cooperative stud portion 30 from one step to the other and vice 0 versa. t v A portions 30 occupythe positionsindicated at a, a in Fig. 5. The inertia of the transmis-. sion couple 34, 36 prevents rotation of these parts during the first stagesof rotation of the operating unit 22; Consequently, when the starting motor isiset in operation, the first efi'ect of the stud portions is to shift the transmission couple axially'as these stud portions progress along theacam'surfaces 54. If the teeth of thestarting pinion 38, butt the teeth of the engine. gear 16 the member 34 takes on rotation ofgtheoperating unit and transmits this rotation through the friction clutch 42, to the pinion.- At this stage the pressure of the frictional clutching surfaces one against the other-is effective to clear the teeth of the pinionfrom the ends of the teeth of the engine gear, whereupon the pinion teeth find slightentrance between the teeth of the engine gear before the nextcontact of teeth occurs. Now, the rotation of the pinion is arrested ,by the engine gear, and the arresting effect is passed along-to the driving member 34 by the friction sursprings 56, the step 54 being effective to shift the pin faces of the clutch, asfnmalaioiitf the teeth resulting since the clutching pressure, at this instant is very light and the clutch members may slip without much-drivingefa fort.

.- During this stage of the operation the in- 3 7o ternal shoulder 52 of the driven member 36v advances vto the washer 50, thereby putting the light spring 48.;under compression, but the shoulder does not reach thewa'sher until after the pinion has, enteredintomeshed a relation with the engine gear and beenarg rested thereby. q 1 V 1" Now the stud portions 30 continue to: ad I Vance along the cam surfaces 54, thereby causing the shoulder, 52 to engage the washer 50 and thereby put the heavyspring 46 under compression. This stage ofcompressioncon tinues until the :stud portions 30 ride over the'humps 58 of the cam member, and at that point the clutching effect of the conical portionsv42, 40 is nearly, if not, quite, sufiicient to cause rotation of the enginewheell 14 In any eventythe studvport ions 30 pass thehumps 58v and advance along'the second- 9 ary cam surfaces 56 until thelconvolfitions of the heavy spring 46 become'entirely' closed 4 and positively arrest the-axial movementof the transmission couple 34, 36-. Atgthis point of the operation the positions of the stud V y portions relative to the camsis' tha-tindicated Now, the driving member 34 of the transl vmissi infi ouple is positively rotated by the, stud port1ons30 but the driven member 36 j is drivensolely, by the frictionofthe clutch mg surfaces 42.140 so that no sudden shock or impact can ever occur as a result of picky ing up the load or as a result of back-firing 1 v When the parts occupy their initlalrposn' l .v I tions as shown in Figs. 1 and 2, thestud oftheengine. v

If, for'anv, reason -the load-on the start ingpinion. is in excessof theclutching'power I of the members-34; and 36, the member 34 Wlll slip relatively to; the. member 36 even thoughthe' coo'oerativeefiect of the stud pore, 11a

tions 30 and the cam steps 56 tends constantly towedge the member 34 more tightly against H the driven member of the clutch Again,

in the event of. reverse rotation of theengine gear 16. in consequenceof back-vfiring, the members of the friction clutch will slip V relatively to eachotherswithout subjecting anypart, of the mechanism to injurious strain; 1 It frequently happens that an'internal combustion 'engineydoes i not start immediately under its own powerieven' though power irns pulses mavj occur in onevor more of its cylinf?" ders. In such a case, theuneven action of the engine :causespulsations in the rotation 126 thereby.- These pulsations are passed along" K; through the driven member 36 to the zdriv- 13"? the spring 46 fully on the inclined cam steps 56. At the same time the repelling action of the heavy spring 46 tends to return the pinion 38 to its initial position, but to guard against demeshing of the pinion and gear under the conditions ust described, the cam member is provided with the humps 58. Under such conditions the stud portions 30 may take positions such as that indicated at 0 in Fig. 5,.and may waver between positions I; and a, but so long as the starting effort of the shaft 12 continues the humps 58 are effective to prevent .demeshing. The reaction of the heavy spring 46 is instrumental in preventing the stud portions from runningback over the humps 58.

On the other hand, as soon as the engine starts to operate normally under its own power, it drives the fly-wheel' and the gear 16 at a speed so much greater than the speed of the starting pinion 38 that it causes the humps 1 58 to overrun the stud portions 30, whereupon the stud portions run down on the steps 54 of the cam member and permit the spring 46 to demesh the pinion and return the parts to their initial positions. The stud portions are thus returned to the positions indicated at ain Fig. 5,"and the speed of rotation of the cam member" 34 is positively checked to a speed exactly equal to that of the stud portions, thus freeing the driven member 40 of theclutch from the driving surface 42. The springs 46 and 48, having been relaxed during the process of demeshingthe pinion,.leave'the clutch members free from clutching pressure, but since they completely fill the axial dimension of the chamber 44 from the shoulder 18 to the shoulder 52, they not only prevent endshake of the member 36 but also cause the clutch'member 40 to support the sleeve 34 in concentric relation to the starting shaft.

The described construction is particularly effective to prevent excessive torsional stresses due to rapidity of accelerationof the starting motor under normal conditions-as well as under abnormal conditions, since, many case, the driving member 34 of the friction clutch may slip relatively to the driven member both during the operationof shifting the pinion axially to its operative position and while the pinionis held in its operative position with compressed.

Iclaim: a 1. An engine starter comprising a rotary and axially movable member provided with a starting pinion, a spring arranged to oppose movement of said member axially to its operative position, a rotary and axially movable transmission member arranged to shift said pinion member to its operative position against the stress of said spring, said members being provided with complemental friction surfaces to form a driving clutch, and a rotary operating member arranged to cooperate with said transmission member,

, oneof the two latter saidmembers being provided with a cam surface with which the other cooperates to shift said pinion member to its'operative position and to effect a starting operation through said friction surfaces in consequence of the opposition of said spring.

2. An engine starter comprising a'rotary and axially movable; member provided with a starting pinion, a spring arranged to oppose movement of said member. axially to its operative position, a rotary'and axially movable transmission member arranged to shift said pinion member to itsoperative position against the stress of said spring, saidmembers being provided with complemental conical friction surfaces to form a driving clutch, and a rotary operatingmember arranged to cooperate with said transmission member, one of the two latter said members being provided with two successively operative cam surfaces instepped relation to shift said pinmission member arranged to shift said pinion member to its operative position and thereby put said'springtunder stress, said members being provided with complemental friction surfacesforming a driving clutch,

and a rotary operating member arranged to cooperate with said transmission member, one-of the two latter said members being provided with a two-stroke cam surface with which the other cooperates to shift said'pinion member with successive individual steps to its operative position by forcing said friction surfaces one against the other.

I 4. An engine starter comprising a rotary and axially movable memberprovided with a starting pinion, a relativelyweak spring and a relatively strong spring both arranged to oppose axial movement of said pinion member from an inoperative position to its operative position, the weaker one of said springs beingefi'ective prior-to the stronger one, a rotaryand axially movable transmission member'arrangedto shift said pinion member to its operative position against the resistance of said springs, saidmembers being provided with complemental conical fric-' 5. An engine starter comprising a rotary steps being effective to build up supplementaland axially movable member provided wit clutching power of said clutch. a starting pinion, two springs arranged to In testimony whereof I have aflixed' my oppose axial movement of said pinion memsignature this 20th day of October, 1928. 5 her from an inoperative position to its oper- ROLLIN ABELL.

ative position, one of said springs being effective prior to the other, a rotary and axially movable transmission member arranged to shift said pinion member to its operative I position a ainst the resistance of said springs,

said mem rs being provided with complemental conical friction surfaces forming a driving clutch, and a rotary operating mem-. ber arranged to cooperate with said transmission member, one of the two latter said members being provided with a cam surface with which the other cooperates to shift said pinion member to its operative position by forcing said conical friction surfaces one 29 against the other. F

6. The combination with an internal combustion engine provided with a gear by which it may be started, of starting mechanism comprising a rotary and axially movable member provided with a starting pinion, a rotary and axially movable transmission member arranged to shift said pinion member axially from a non-meshing position to a meshing position with respect to said gear, said mem ao bers having complemental friction clutching 05 surfaces by which such shifting movement is imparted to the pinion member, a spring arranged to oppose such shifting of said pinion member and thereby develop increasing clutching effect of said surfaces, and a rotary I operating member arranged to cooperate with said transmission member, one of the two latter said members being provided with a cam surface with which the other cooperates to shift said pinion member to its operative position by forcing said clutching surfacesone against the other.

7. An engine starter comprising a rotary and axially movable member provided with a a 1 10 starting pinion, a rotary and axially movable transmission member arranged to abut said pinion member and move it axially to its operative position, theabutting surfaces of said members being constructed and arranged v 115 to form a friction driving clutch, a spring arranged to oppose axial movement of said pinion member to its operative position and thereby develop increasing clutching power of said clutch, and a rotary operating member arrangedto cooperate with said transmission member, one of the two latter said members being provided with two successive- 6o ly operatlve cam steps inclined in the same general direction but offset from alinement "with each other the first'of which is effective to shiftsaid pinion member to its operative position and to build up the clutching power of said clutch, and the second one of said cam no lac

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