US2609695A - eng engine - Google Patents

Description

Sept. 9, 1952 J. E. Bux'oN 2,609,695

ENGINE STARTER GEARING Filed Dec. 22, 1950 www,

35 I INVENTOR.

WITNESS: I BY A oRNE X necessary Wear remain self operative. y

Patented Sept. 9, 1952 ENGINES STARTER filename.v 'l .James E. Buxton, Elmira, N. Y., assignor to Bendix Aviation Corpo 4Delaware ration, a corporation of Application December 22, 1950,'ser1a1No. 202,224

1 f The present invention relates to engine starter gearing, and more particularly to that type in which a 4pinion is automatically` traversed into mesh with an engine gear, and demeshing is opposed until the engine is reliably self-operative.

, '.Many approaches have been made to the .problem of providing a self-contained anti-kick- `out drive, most' of which rely on various types of centrifugal latches which are responsive to `engine speed, or to starting motor speed to permit demesh `of the drive pinion from the engine gear.

#Such drives in which disengagement is controlled by engine speed have the advantage that demeshing will take place reliably at a predetermined engine speed regardless of whether or not the operator holds the starting circuit closed after the engine res. It is necessary, however, to design the latch to release at Ia speed considerably higher than the normal idling speed of the engine, sin-ce the enginespeed in a false start,

l that is, one in which the engine fails to continue `self-operative, may substantially exceed its idling speed. A-highspeed setting for -a positive type of latch is 'disadvantageous however, since 1t tends to make the drive noisy and to cause un- It` is desirable, therefore, that the latch means be so constituted that it resis-ts disengagement of the drive responsive to weak explosions of the eng-ine, as when it is cold or flooded with excessive fuel, but will permit immediate disengagement responsive to a vigorous engine explosion even at low rotational speeds.

It is an object `of the present invention to provide a novel sta-rter drive of the above type which is simple in construction and quiet in operation. f l

- l 4lit is another object to provide such 4a Ddevice Ainl whichth-e pinion and its associated parts 4are permitted to overrun freely when the engine fires,

but the drivin-g connection is resumed promptly and without shock in c-ase the engine does not l Ttis a further object to provide such a device in-l which `the pinion is hel-d in mesh with the engine gear vby a detent which is withdrawn by centrifugal force when the rotary vspeed of the :pinion exceeds a predetermined minimum.

It is another object to provi-de such .a device in which the deten't is arranged to yield in response toitorque caused by a vigorousexplosion of the engine even though the rotational-speed is insuf- `Aiicient by? itself to cause disengagement of the deteri-t.

Further objects and advantages will be ap- 5 Claims.

. l 2 i I parent from the following description taken .in connection with the accompanying drawing', in whichz' Fig. l is a side elevation partly broken away yand in section of a preferred embodiment ofthe invention showing the parts in idle position;

, Fig.` 2` is a similar view showing the parts in the positions assumed when the engine res and causes the pinion to overrun the drive; and p Fig. 3 is a view similar to Fig. l of a second embodiment of the invention.

In Fig. l of the drawing there is illustrated a fpower shaft I, which may be the extended armature shaft of a starting motor, on which a sleeve 2 is rigidly mounted as by means of a cross pin 3. The sleeve 2 is` form-ed for a portion of its length with a non-circular cross-section such as a double D section, and-an angular plate 4 is slidably mounted thereon,v being retained by a split lock ring li.A Sleeve 2 has `a reduced cylindrical extension `6 lon which a driving clutch member I is slidably and 'rotatably mounted, the longitudinal `travel `thereof being limited on the one hand by the shoulder B formed by a reduction in diameter of the sleeve, and on the other hand by a lock ring 9 seated in a groove formed in the sleeve and accommodated by a counterbore II inthe clutch member. A driven anchor plate I2 is non- `rotatably mounted on the clutch member I'I against a shoulder I3 thereon, and ya torsion drive spring I4 has its out-turned end-s I5, I5 engaging in radi-al slots in the anchor plates v 4. and I2 so as to yieldably connect the driving clutch member 'I tothe sleeve 2 and power shaft I.

A screw shaft I'I isslidably journalled on the reduced portion 6 of sleeveZ, and is provided with overrunning clutch teeth I8 cooperating with the teeth I9 of driving clutch member 1. Means for limiting the movement of screw shaft Il away from the `driving clutch member is provided in the form of a stop ring 20 anchored on the end Vof the sleeve 2 by means of -a lock wire 2|. .A

an engine l gear 25. Means foractuating the pinion is provided comprising a control nut 26 threaded on the screw shaft I1 having radiallugs 21 entering slots 28 in a barrel member t28 Vand retained by` a lock ring 30, the barrel being `rigidly connected to the pinion, 2liv as ,indicated ati.

. The idle Vpositimof the control nut is defined Yby the ends 32 of the threads of the screw shaft (Fig. 2), while the meshing movement of the control nut is limited by its engagement with the washer 23 of the stop ring 20.

A detent member in the form of a ball 33 is mounted in the control nut 26 and is pressed into engagement with the screw shaft by a spring 34 which bears at its outer end in a cup member 35. This detent is arranged to perform the function of an anti-drift member to yieldingly retain the drive in idle position, and also to resist demeshing of the pinion from the enginelgea'r in case of a false start.

The rst function is accomplished by means of the formation of an nclined ramp 36 on the screw shaft in position to be engaged by the detent at the start of the meshing movement of the pinion and controlnut. The second function is secured by reducing the diameter of the screw shaft adjacent the cranking position of the detent 33, and forming an inclined shoulder 3l over which the detent must be forced in order for the demeshing action to take place. This shoulder 3l, as best seen in Fig.

`2, is slightly less in height than the radius of the detent 33 so that longitudinal pressure of the control nut caused by a vigorous explosion of Vthe engine will tend to force the detent over the shoulder even though the rotational speed of the parts is at that time insu-lcient to withdraw the detent from the screw shaft.

In operation, starting with theparts in the positions illustrated in Fig. 1,'rotation of the power shaft I is transmitted through the sleeve 2, anchor plate 4, spring I4, anchor plate I2 to the driving clutch 7, which is engaged with the end of the screw shaft Il by reason of the expansion of spring 22. The screw shaft III is thus rotated, vcausing the control nut 26 to move to the right and push the pinion 24 into mesh with the engine gear 25. During this operation the detent 33 passes over the shoulder 36 on the screw shaft, A`and toward the end of the meshing movement it vdrops down behind the shoulder 37. When the longitudinal movement of the control nut 26 is arrested by the stop ring 2Q, the screw shaft Il vis forced to the left compressing the overrunning lclutch teeth I8-I9 against the resistance of the drive spring I 4.

When the engine rires, if the explosion is weak lthe pinion 24 starts to overrun the power shaft,

thus per-mitting the screw shaft to move to the right, compressing the clutch spring 22 until the overrunning clutch teeth Iii-I9 are disengaged, thus permitting the pinion, barrel, nut and screw shaft to overrun. At this time further demeshing movement of the pinion is arrested by the engagement of the detent 33 against the shoulder 3'! on the screw shaft.V If the engine continues to fire and the rotational speed of the npinion reaches a predetermined value, the detent 33 is withdrawn by centrifugal force and the parts permitted to return to idle position. On the other hand, if the initial explosion is a vigorous one, vthe detent 33 will be immediately forced over the shoulder 3'I and demeshing will take place even prior to the attainment of sufficient v'rotational speed to withdraw the detent by centrifugal force.

cause the pinion 24 to be indexed into proper registry with the tooth spaces of the engine gear, after which the spring I4 will expand and snap the pinion into mesh.

In Fig. 3 of the drawing there is illustrated an embodiment incorporating a separate mesh-enforcing spring for overcoming tooth abutment. As there shown, the lugs 21 of the control nut 26 are longitudinally slidable in the slots 28 in the barrel 29, and a spring 4I is located in the barrel and yieldably presses the control nut 26 against the retaining ring 30 in the barrel. In case of tooth abutment in this embodiment of the invention, the longitudinal pressure caused by arresting themeshing movement of the pinion causes the spring 4I to be compressed by the control Vnut 26, the lugs 21 thereof sliding in the slots 28' until sufficient torque is built'up to index the pinion, whereupon the meshing action proceeds.

' In this embodiment, the drive spring .I4 is preferably maintained under pressure by the lock ring 9, the counterbore for the lock ring being 4omitted from the driving clutch member 'I' for this purpose. This permits a desirable shortening of the drive, and improves the mesh-enforcing action by the reduction in the inertia of the parts entering into the meshing operation.

Although but two embodiments of the invention have been shown and described, it will be understood that other embodiments are possible. and that changes may be made in the design and arrangement of the parts without departingfrom the spirit of the invention.

I claim:

l. In an engine starter drive, a power shaft, 'a sleeve xed thereon at one end, a driving overrunning clutch member slidably `journaled on said sleeve, means including an elastic cushioning member connecting the driving clutch mem.- ber to the sleeve, thrust means limiting the longitudinal movement of said clutch member away from said; cushioning member, a driven clutch member and screw shaft slidably journaled on the sleeve, a stop member on the free end of the sleeve, a vcompression springY on the sleeve between the screw shaft and stop member, a pinion slidably journaled on the power shaft for movement into andv out ofk mesh with an engine gear, a control nut threaded on the screw shaft, a barrel member connecting the nut and pinion, said screw shaft having a peripheral recess defined at one end by a shoulder, and a yielding detent in lthe control nut positioned to enter said recess when the pinion is engine gear.

2. An engine starter drive as set forth in claim 1 inY which the shoulder of the screw shaft and the detent are so formed that acceleration of the control nut with respect to the screw shaft tends to make the shoulder cam the detent out of the recess. Y Y f 3. An engine starter drive as set .forth in claim 1 inV which the detent is formed with a substantially spherical engaging surface, the center of which is farther from the axis of the rdrive 'than the top of the shoulder on' thescrewnshaft, so as to ride over the shoulder when suiiicient force. is applied tothe control nut in the direction to demesh the pinion.

4. An engine starter drive asset forth inclaim 1 in which the screw shaft is formed with a moved into mesh with-the Y peripheral recess defined Vby an inclined shoulder in position to receive the 5 6 5. An engine starter drive as set forth in claim REFERENCES CITED 1 in Whlch the control nut is slidably but non' The following references are of record in the rotatably mounted in the barrel, including further lock means holding the control nut in the me of thls patent' barrel and a compression spring in the barrel 5 UNITED STATES PATENTS pressing the control nut against the lock means. Number Name Date 1,210,028 Adams Dec. 26, 1916 JAMES E. BUXTON. 2,343,967 FitzGerald Mar. 14. 1944

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