US1660987A - Engine-starting apparatus - Google Patents

Description

Feb. 2s, 192s. 1,660,987

J. BIJU R y ENGINE STARTING AIPAHATUS Filed April 28 1920 5 Sheets-Sheet l LL f INVENTOR JOSEPH BIJUR ATTORNEY Feb. 28, 1928. 1,660,987

4 J. BIJUR ENGINE STATING APPARATUS Filed April 28, 1920 i 5 Sheetsheet 2 INVENTOR JOSEPH BIJUR ATTORN EY Feb. 28, 1928. 1,660,987

J. BIJUR ENGINE `STARTING APPARATUS Filed April 28 1920 3 Sheets-Sheet 5 ATTORNEY Patented Feb. 28, 19u28.

UNITED STATES PATENT oFFicE.

JOSEPH BIJ'UR, 0F NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO ECLIPSE MACHINE' COMPANY, OF ELMIRA HEIGHTS, NEW YORK, A CORPORATION 0F NE YORK.

ENGINE-STARTING APPARATUS.

sepia-suon mea apra 2s, 1920. serial no. 377,373.

This invention relates primarily to engine starters and has its preferred application to' starters for aeronautic engines although it is useful for the starting/of engines generally that are incapable of self-starting.

Une of the objects of the invention is to provide in a starter, safety means of simple and rugged construction which shall edec tively eliminate the likelihood of injury to the engine or destruction of the mechanism under backfire of the engine without however in any way impeding the action of the starter in normal cranking operation. The invention has its preferred application to starters of the type in which the driving element remains operatively connected to the engine while the latter is idle, that is to starters' of the type that do not require shifting of a driving member into cooperation with an engine member prior to application of cranking torque. y u

lllith regard more particularly to starters of the type referred to, my invention is also concerned with simple mechanical means for easing the shock of applying the starting motor torque to the 'engine even though the full line voltage be impressed upon the idle motor..

Although of application broadly to various types of starters, my shock easing means has particular utility in connection with a specitic'form of starter of the type above mentioned in which planetary wobble gear` ing is employed and in which the wobble' gear 'element is normally free to rotate but is arranged to be restrained when cranking torque is applied.

Referring now to the accompanying drawings in which are shown one or more of various possible embodiments of the several features of my invention, Fig. 1 is a view in longitudinal section of a starter embodying one form of my invention, Fig. 2 is a fragmentary sectional view similar to Fig. 1 showing the splines disconnected by the action of the backfire release mechanism, Fig. 3 is a detail view partly in section showing one form of restraining means, Fig. 4 is a side view of the detail shown in Fig. 3,

Fig. 5 is a view similar to Fig. 3 showing another form of restraining means, Fig. 6 is a detail sectional view of another form of back-fire release, Fig. 7 is a view similar to Fig. 6 of still another form of back-fire release and Fig. 8 is a detail view of one of the clutch Ielements shown in lfig. 7.

Similar reference characters refer to similar parts throughout the several views of the drawings. l

Referringnow to Fig. 1 of the drawings, I have shown the end of a-cranlrshaft 1 provided with internal splines 2 and a starter comprising an electric motor 3 and a driving shaft t having spline teeth 5 rigid thereon and cooperating between the splines'Z in the end of the crankshaft for torque transmission` In Fig. 1 the `teeth 5 and splines 2 are shown in thenormal meshing position which they occupy both during cranlring and when the starter is' idle. Torque `.is transmitted from the motor 3 to the shaft et by transmission mechanism now to be described, said mechanism being sustained and enclosed in a housing lvl which housing also supports motorB. Upon the end of the motor shaft, there is a driving pinion@ meshing with a gear 7 lzeyed as at 8 to a shaft 9. Upon shaft 9 there is lreyed or otherwise rigidi secured an eccentric 10 which mounts pre erably upon ball bearings 11 a planetary spur gear of the wobble type shown at 12. 'Ihe internal gear 13 with which gear 12. cooperates is mounted upon a pair of ball been ings la and lll disposed respectively near the end of the shaft 9 and within the wall of housing ltl. The internal gear 13, transmits the torque to the driving shaft 4 preferably through safety mechanism which will be described more fully below. In normal operation the safety mechanism acts substantially as a rigid connection between internal gear 13 and shaft 4,' and may be so regarded in the consideration `of the general assembly and the normal operation.

In normal opera-tion of planetary wobble gearing, means `is ordinarily provided to prevent rotation of the wobble gear, limitlng its movement to one of shifting without rotation in a circular path determined by the eccentric.- For this purpose I provide the following means. Mounted upon shaft 9 preferably on a ball bearing 15, I provide a wheel 16 having a rim 17 overlapping the 'opening 38.

wobble gear 12 and wheel 16, but allows the shifting or wobbling movement of the former about its eccentric mount.

It will bc seen that unless the spur gear 12 is restrained against rotation a starting of the electric motor 3 will cause the eccentric to revolve the wobble gear about the vinterior of the internal gear 13 while rotating it about the eccentric 10, the internal gear being held against rotation by the resistance of the engine to which it is connected through the safety mechanism-and the shaft 4. For rendering the wobble gearing operative to transmit torque, I provide means for restraining the wheel 16 against rotation and I thereby limit the wobble gear to a simple movement of translation in a circular path about the eccentric 10, by virtue of the universal plate 20 in a manner made clear above.

By preference the means for restraining the wheel 16 against rotation aiidthe switch for turning current into the motor are interconnected in the specific manner best shown in Fig. 4. Referring to Fig. 4 a pair of switch terminals are shown atf22 and 23 adapted to be bridged by a flexible switch blade 24 which is in the path of a blade or eccentric 25 keyed upon a shaft 26 which in turn is journalled in the housing H, an operating handle 28 being keyed to the end of the shaft. Keyed upon the shaft 26 I `provide one or preferably two clutching members in the form of pawls 29, the teeth 30 of which are adapted to cooperatewith ratchet teeth 16"upon the periphery of wheel 16. Preferably each pawl is'yielding in character land comprises a base member 32 keyed to the shaft 26 and having a socket 33 in which is slidably mounted the shank 34 of the pawl tooth 30, a coil compression ,spring 35 encircling said shank and being interposed between the base 32 and a flange 36 integral upon said shank. A cap 37 is preferably threaded upon the base 32 enclosing the spring 35 and the flange 36, the tooth projecting from said cap through an A coil spring 39 encircles the shaft 26 and is secured thereto at one end 'and at the other end to housing II, said Ispring biasing the pawls to a position out of contact with the ratchet teeth 16 and biasing the eccentric 25 away from the switch. In the embodiment described, the

eccentric 25 and the pawls 29 are preferably disposed upon the shaft 26 in such relative.

angular position that the switch 24 is closed as the pawl tooth 30 is brought into contact with one of the teeth.

In operation, the handle 28 is normally rotating in order to transmit torque through pinion 6, gear 7, shaft 9, eccentric 10, spur gear 12, internal gear 13 and through the safety mechanisms by way of the teeth 5 to the splines 2 in the crankshaft end. By virtue of the resistance of the engine to breaking loose, the internal gear 13 is held against rotation and consequently as pointed out heretofore the wobble gear tends to revolve within the internal gear while rotating about its eccentric mount. A limited rotation of the wobble gear is permitted as the wheel 16 which is connected thereto by the universal plate.20 can rotate therewith against the resistance of pawl spring 35 until the latter is compressed.

The pawl or pawls thus gradually and yieldingly arrest the ratchet wheel 16 so that the concurrent rotation of the spur gear 12 is also gradually and yieldingly arrested until the normal wobbling thereof without rotation takes place. At the beginning of the starting operation therefore the spur gear will rotate about its axis in a direction imposed upon it by the resistance to rotation of internal gear 13 and against the resistance of spring or springs 35 until the ratchet wheel 16 is restrained against further movement by the compression of said spring. Thus in the process of cranking, the rotation of the wobble gear is gradually arrested or the wobble gear is gradually rendered fully effective for transmitting force, and the cranking torque is thus gradually or yieldingly applied from the motor to the engine.'y When the engine starts firing, handle 28 is released, and spring/39 snaps the pawls or clutching arms to inoperative position and the eccentric 25 away from switch blade 24 to permit the latter to open. The engine cannot rotate the motor after firing even if the switch were held closed, as any such rotation would'l cause pawl teeth 30 to click over ratchet teeth 16. The transmission is thus irreversible.. i

An alternative form of clutching member is shown in Fig. n5. l At 31 is shown the plain or untoothed periphery of a wheel corresponding to ratchet wheel 16, and a friction clutch wheel 40 keyed as at 42 upon a pivoted spring metal clutching arm 41 corresponds to yielding pawl 29. In the fragmentary view of Fig. 5 at the right, the arm 1s shown in inoperative position. The arm llt) 41 preferably occupies an angular position relative to the switch operating eccentric 25, somewhat similar to that shown in Fig. 4 except that by preference the switch will be closed before the friction Wheel comes into contact with the Wheel 31.. Thus'the motor will be started at full speed Without the delivery of torque tothe engine, and as the friction whe-el 40l is gradually brought into tightening engagement With the Wheel 3l it brings about a gradual slackening of the rotary movement thereof against the yield of the spring arm, and a coincident retardation of the rotation of the wobble gear until when the wheel 31 has been completely arrested and the wobble gear is limited to its translating movement about the eccentric, the full torque of the motor is applied to the engine. 'lhus cranking torque is gradually and yieldingly applied to the engine. .The friction Wheel when in the operative position shown in Fig. 5 forms part of an underset toggle, the point of tangency of the friction Wheel With the Wheel 31 being toward the side from which the line joining the center of Wheel 31 to the axis of arm 41 is approached in the process of setting said clutching means. Wheel 40can thus readily be wedged against Wheel `31 to effect the necessary tightening and the arm 41 can yet be easily releasable by the action of spring 39 when the hand is taken ofi the handle A28. Except as above described, the form of 1nvention shown in Fig. 5 is identical with l that shown in Figs. 3 and 4.' It is apparent that a clutching member similar to that shown in Fig. 3 might be used in the species of Fig. 5, a wheel, however, preferably taking the place of the projecting tooth portion.

ln the operation ofthe forms of device thus far describe-d, particularly in cranking airplane engines, and 'especially when the engine has been heated by running or by repeated starts, pre-ignition may occur, the explosion commencing before the end of the compression stroke, or in other Words before top dead center is reached. This pheno1nenen known as back-fire manifests itself in a rotation of the engine to a limited extent in a reverse direction. Such rotation in the type of construction disclosed would in the absence of special precaution impart to the internal gear a positive rotation in the direction opposite to that in which it is urged by the electric motor. This rotation tends to be imparted by the internal gear to the spurV or wobble gear 12 and from that gear to the ratchet Wheel 16 or smooth wheel 31. As the pawls 29 and friction Wheel 40 respectively 1n the two species lock the corresponding ratchet or smooth Wheel against reverse rotation some part of the starter must break, either one or more of the ears or the pawls or friction Wheels or the ous- The back-ire rdease device.

One form of this device is shown in Fig. 1. In this construction a nut is threaded upon threads 51 integral with the shaft 4, said nut having lugs 52 interfitting notches 52 in a hub 53 integral with the internal gear 18 and enclosing a plurality of strong dished washers 55 encircling the shaft 4. A stop nut 56 is threaded upon the free. end or shaft 4 and locked in position by a lock nut 57. |The nut 50 is held in place upon the hub 53 by means of a threaded cap 58 in 'turn locked in position by a lock nut 58'. rlhe stop 56 or its lock nut 57 is in close proximity to a shoulder 59 also preferably formed integrally with internal gear 13 in order to prevent any'substantial movement of the shaft 4 toward the right.'

In normal cranking, the torque is trans- Vmitted to internal gear 13 in the manner already described and from said internal gear through notches 52 to lugs 52 on the nut 50 and from said nut through 'threads 51 to the shaft 4. The safety mechanism acts in normal operation of the starter as above noted, Vsubstantially in the manner of a rigid connection between internal gear 13 and shaft 4.

Should a back-lire occur, the shaft 4 vrill tend to be rotated thereby in a direction op posite to thedirection of rotation imparted by the motor 3'. As a consequence the'thread 51 Will feed forwardly Within the nut 50 until the teeth 5 on the shaft are disengaged from the corresponding splines in the crankshaft as shown in Fig: 2. This action takes place against the resistance of dished Washers 55, which are compressed by the stop flange 5G as the saine moves toward the left with the shaft 4. As shown in Fig. 2 the engine is disconnected from the starter and the reverse back-lire rotation of the engine consequently cannot be imparted to the starter. The dished washers 55 compressed as in Fig. 2 will in their expansion urge the sto flange 56 and with it the shaft 4 toget er with the teeth carried thereby toward the right when the teeth are properly aligned llG to permit reengagement thereof. If the i back-lire persists, alternate demeshing and remeshing will continually take place in the manner already indicated until the condition of 'baclefire ceases. Then the back-lire 1s over, normal cranking proceeds in the manner already clearly described.

By preference the disengagement takes place by displacement of shaft 4 toward the interior of the hollow crankshaft end, thus rendering the construction shorter than if the op osite arrangement were employed.

It s ould be noted that when the engine starts rotating under its own power any tendency for threads 51 to be urged out of the nut 50 is prevented by contact of locking nut 57 with the adjacent part of the internal gear 13.

In Fig. 6 isy shoW`n an alternative form of back-fire release. The hub 53A upon the internal gear is secured to a flange G5 formed integrally upon the driving shaft 4A and shearing pins 66 preferably two in number are employed to establish a driving connection between the hub 53A and the shaft 4A. These shearing pins are preferably disposed in corresponding hardened steel bushings 67 formed in the hub'and in the shaft flange. A cap 69 may bethreaded upon the hubC for retaining the flange against displacement therefrom while the pins; are unbroken. The pins are made of such strength that they will transmit at least the highest cranking torque evolvedh by the starter or required by the engine. The shearing pins are formed however to be too Weak to stand the greater torque encountered upon back-tire when the engine exerts a transverse force upon the shearing pins in a direction opposite tothat exerted by the motor. Upon breakage of the shearing pins the engine can only rotate the shaft 4A but it cannot impart any torque to the gearing or to the motor and thus upon cessation of the back-tire it is merely necessary to screw off the cap 69, remove the broken shearing pins 66 replacing them by new pins and to reapply the cap, when the starter is again operative for further use. By preference the shearing pins have each a longitudinal axial hole 7() to facilitate removal of a broken end4 from the hub. The modification just described thus provides a back-re release including shearing pins that are readily accessible for replacement upon breakage.

In Figs. 7 and 8 I have shown a third alternative form of back-lire release embodying a friction clutch. In this construction the driving shaft 4B has slidably keyed thereto as at 71 a cone 72. Upon the cone are keyed as at 7 3 a plurality of hardened steel friction clutch elements 74 preferably in the general form of semi-aliuli or semi-disks of graduated internal diameter to fit over the cone 72. A stop 7 'is threaded and locked upon the free end of shaft 4B and limits movement ofthe clutch disk members toward the right. Near thefleft end of the shaft 4B is threaded a stop nut 76 held in place by lock nut 77 and a coil spring 78 encircling shaft 4B reacts against stop nut 76 to press the cone 72 toward the stop 75. rIhe peripheries of the disk ele.. ents 74 are preferably convex in cross-section and generally V-shaped as shown at 80, there belng corresponding V-shaped grooves 81 in hub 53B. The nut 76 is'- adjustable to tighten the spring 78 for wedging the peripheries 80 of the cone into the hub member 53B to bring about a frictional engagement between said members sufficient to transmit cranking torque and insuflicient to transmit the greater reverse back-fire torque.

1. The combination of an engine having a rotatable shaft with an end provided with engaging means, and a starter drive including a rotatable and longitudinally movable shaft having complementary engaging means, which two means are normally in driving engagement, and also including means responsive to a back fire of the engine andthe consequent driving thereby of the starter drive for longitudinally moving such shaft and thereby disengaging it from the engine shaft.

2. The combination of an engine having a rotatable shaft with a hollow end provided internally with splines, and a starter drive including a rotatable and longitudinally movable shaft having at one end splines normally in driving engagement with the splines of the engine shaft and also including means responsive to, a vback fire of the engine and the consequent drivin@ thereby of the starter drive for longitudinally moving such shaft and thereby disengaging it from the engine shaft.

3.' The combination of an engine having a rotatable shaft with an end provided with engaging means, and a starter drive including a rotatable and longitudinally movable shaft having complementary engaging means, which two means are normally in driving engagement, and also including threaded means effective upon a backward movement of the shaft to move such shaft longitudinally in a direction to disengage it from the engine shaft.

4. The combination of an engine having a *rotatable shaft with an end provided with engaging means, and a starter drive including a rotatable and longitudinally movable shaft having complementary engaging means, which two means are normally in driving engagement, and also including threaded means effective upon a backward movement of the engine shaft to move the starter drive shaft longitudinally in a direction to disengage it from the engine shaft and spring means tending to resist such disengaging action.

5. The combination of claim 2 in which the parts are constructed and arranged to cause the shaft splines to be urged toward the interior -of the engine shaft for disengagement from the engine shaft splines.

6. The combination, with a member of the engine tobe started, of a starter including a longitudinally shif'table rotatable drive shaft normally drivingly engaging said engine member, means acting upon .aback-fire a back fire of such engine, and means to prenally in a direction to disengage said shaft and engine member, and spring means to resist said disengaging action.

7., The combinationof an engine having a crank shaft with an end provided with engaging means, and a starter drive including a rotatable and longitudinally movable shaft having complementary engaging means, which two means are normally in driving engagement, and also including threaded meansI eective upon a backward movement of the shaft to move such shaft longitudinally in a direction to disengage it from the crank shaft and means to prevent substantial longitudinal movement of said shaft in the opposite direction in the normal operation of the parts. 0

8. An engine starter comprising a motor, a driving pinion thereon, a gear driven thereby, a shaft upon whichaid latter gear is keyed, planetary reduction gearing upon said shaft, a second shaft aligned with said rst shaft and having splines near its end, an oblique driving connection betweennsaid gearing and said second shaft to compel lon-- ,gitudinal movement of the latter upon a back-fire of the engine to be started, and means to prevent substantial movement vin the opposite direction. L

9. 'Ihe combination of an engine having splines at an end of its crankshaft, a starter t erefor comprising a motor, a driving pinion thereon, a gear driven thereby, a. shaft upon which said latter gear is keyed, planetary reduction wobble gearing upon said shaft, a second shaft aligned w1th said first shaft and having teeth near its end normally mashed with the splined end of said crankshaft, and means for automaticallyvdemeshing said teeth upon occurrence of a back-fire.

10. The combination of claim 8,- in which there is provided a threaded connection between the gearing and the threaded shaft to compel demeshdupon a back-fire, a projection l h on said shaft, s ring means between said projection andy th` threaded portion to resist i disengagement upon a back-ireand to compel reengagement when the back-tire ceases, and means adjacent said projection to prevent shlfting of said shaft in a direction opposite to that referred to.

11. The combination, with an en ine to be started, of a shaft arranged to cra such engine to Vstart the same and normally in en#v gagement with the engine, driving mechanism for said shaft including an oblique driving connection therewith to compel 1ongitu'dinal movement of thelshaft in one direction to disengage it from the engine upon vent a substantial movement of the shaft in the opposite direction.

12. The combination, with an engine to be started, of a motor, a shaft driven thereby and arranged to crank such engine to start' the same, said shaft being lnormally in engagement with the engine, a threaded driving vconnection between the motor and the shaft to compel longitudinal movement of the latter in one direction upon a back tire of the engine, and means to prevent a substantial movement of the shaft in the opposite direction. 1

13. In an engine starter, planetary reduction gearing comprising a shaft having an eccentric portion, a wobble spur gear upon said eccentric portion, an internal gear with which said ywobble gear cooperates, engine driving means connected to said internal gear, means for restraining'said spur gear against rotation and confining its movement to one of translation in a rotary path, said means comprising a wheel. having a rim encircling said internal gear, said rim having ratchet teeth, a universal plate connecting said spur gear to said wheel, a-pawl for arresting said ratchet comprising a socket, a pawl tooth slidable therein, a spring between said socket andV said tooth, and means for limiting theexpansion of said spring, a support about which said socket is pivotally mounted, and a spring for biasing said pawl away from said ratchet. l

14. In an engine starter of the type which includes a motor and planetary gearing, the

elements of which gearing. are normally inoperative and which further includes means for gradually arresting an element of said planetary gearing to yieldingly transmit cranking torque, said latter means including a pawl having a base, a pawl tooth having a vshank slidable in a socket in said base, an enlargement between the'ends of said shank, a compression spring encircling said shank vand disposed between said base and said en- \lar ement, and a cap secured to said base an spring, the point of said tooth projecting t rough an opening in said cap.

15. In combination with a member of an engine to be started, an enginestarter including arrotatable driving member at all times in engagement with the engine member while idle and while rotating in a forward direction, and means for automatically disengaging the driving member from the enginel member when the latter rotates inA a backward direction.

16. In combination with a member of an engine` to be started, an engine starter including a rotatable driving member having positive en agementat all times with the lengine mem er 4while idle and while rotating" in a forward direction, and means for automatically shifting such driving member longitudinally and out of engagement with the driving member when the latter rotates in a backward direction.

17. In combination with a toothedmember of an engine to be started, a starter inenclosing said enlargement and said cluding a driving shaft having teeth normally meshing with the teeth of the engine member, and means responsive to a baek-fire of the engine for shifting the shaft longitudinally to disengage said teeth.

18. In combination With a member of the engine to be started, a starter including a driving shaft normally in engagement With t-he engine member and having a screw threaded portion, and a nut engaging such screw threaded portion, and held against longitudinal lnoven'lent, whereby when the engine back-fires the shaft will be shifted longitudinally to disengage the shaft from the engine member.

19. In combination with a member of the engine to be started, a starter including a driving shaft normally in engagement with the engine member and having a toothed port-ion, a nut having teeth engaging such toothed portion and held against longitudinal movement, and a spring tending to hold said teeth of the shaft and nut in engagement, whereby when the engine backeires the shaft will be shifted longitudinally against the tension of said spring to disengage the shaft from the engine member.

Signed at Hoboken, in the county of Hudson and State of New Jersey this 13th day of April, 1920.

JOSEPH BIJ UR.

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