US2308979A - Engine starter gearing - Google Patents

Description

Jan. '19, 1943.

ENGINE STARTER GEARING 2 Sheets-Sheet 1 Filed April 27, 1940 5 151413 2.7 R 7 V I r I Iillllllll 6 mg fi mm 25 2 13 4F. 25

INVENTOR. BY flan-'11). clones ATTORNEY.

B. w. JONES 2,308,979

Jan. 19, 1943. B. w. JONES 2,308,979

ENGLENE STARTER GEARING Filed April 27. 1940 2 Sheets-Sheet 2 I INVENTOR. flair/LU. c/Aanes ATTORNEY.

Patented Jan. 19, 1943 ENGINE STARTER GEARING Burr W. Jones, Elmira Heights, N. Y., assignor to I Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April 27,1940, Serial No. 331,997

7 Claims.

This invention relates to engine starter gearing l and more particularly to a starter drive utilizing a cushioning member of elastically deformable material.

It is an object of the present invention to provide a novel engine starter drive which is efiicient and reliable in operation and simple and compact in construction.

It is another object to provide such a device in which the overall dimensions of the drive are reduced to permit installation in restricted spaces without weakening the drive or rendering it less resistive to bending moments.

It is another object to provide such a device the inboard meshing type in which the engine drive pinion is journalled directly on the armature shaft of the starting motor, and the traversing and driving means for the pinion are mounted on reduced portions of said shaft which are not subjected to bending stresses.

It is another object to provide such a device in which a reduced portion of the shaft provides a shoulder, and the interior of the pinion is provided with an abutment adapted to engage the shoulder to define the operative position ofthe pinion, thus securing a shorter and more compact form of drive.

It is a further object to provide such a device in which the drive is assembled as a unitary structure which is readily mounted or replaced in the v In Fig. l of the drawings a power shaft I which may be the extended armature shaft of a starting motor, not illustrated, is provided with a reduced cylindrical extension 2 terminating in aportion 3 which is further reduced and of non-circular cross section. A pinion 4 having a radial flange I0 fixed thereon is slidably journalled on the shaft l for movement into and out of engagement with a member such as a ring gear 5 of an engine to be started. The interior bore 6 of the pinion I is arranged to have a free running fit onthe shaft position until re-energization of the starting motor.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevation partly in section of a preferred embodiment of the invention, showing the parts in idle position;

Fig. 2 is a similar view showing the parts in driving position;

Fig. 3 is an end View of the structure shown in Fig. 1;

Fig. 4 is a section taken substantially on the line 44 of Fig. 2;

Fig. 5 is a side elevation partly in section of a second embodiment of the invention arranged to provide a drive of short overall length;

Fig. 6 is a similar view showing the parts in driving position;

Fig. '7 is an end view of the structure illustrated l and is provided with an internal abutment 1 bearing freely on the reduced extension 2 of shaft I, and adapted to come into engagement with a shoulder 8 on the shaft formed at the junction of the reduced extension 2 with the main part of the shaft l For purposes of wear resistance, the shoulder 8 is preferably formed as illustrated by a hardened ring 9 pressed on the reduced cylindrical extension against the end of the main part 1 of the power shaft.

A screw shaft H is fixed on the end of the reduced extension 2 of the power shaft in any suitable manner. As here illustrated, the screw shaft is formed with a portion l2 conforming to the non-circular extension 3 of the power shaft, abutting against a shoulder l3 formed at the junction of the non-circular extension 3 with the cylindrical extension 2, and locked in position by 'means ofa split lock ring l4 seated in a groove in the non-circular extension 3. A nut memberv I5 is mounted on the screw shaft I l and is provided with a radial flange 16 at one end. A cylindrical block of elastically deformable material I] is mounted on the reduced portion 2 of the power shaft between the flange ll! of the pinion and the flang I6 of the nut l5, and is maintained in slight compression therebetween by means of an enclosing sleeve IS, the ends of which are spun over the flanges l0 and I6 as illustrated at l9 and 21. In order to reduce frictional wear of the cushion block I1, wear rings or thimbles 22 and 23 are preferably employed to form bearings for the block on the extension 2 of the power shaft and against the pinion and nut.

The screw shaft H and nut member I5 are threaded for only a portion of their respective lengths whereby the nut is permitted to run off the ends of the threads on the screw shaft, thus permitting the pinion to overrun the. power shaft when the engine starts. Re-entry spring 24 bearing against the end of the nut and seated on a thimble 25, is provided to insure reengagement of the threads on the screw shaft and nutupon actuation of the power shaft. I Preferably, the

thimble 25 is provided with an inturned flange tion. As here illustrated, the anti-drift member comprises a plurality of spring arms 21 which bow outwardly to engage the interior of the nut, and a body portion 28 (Figs. 4 and 9) having an opening of non-circular cross section conforming to the cross section of the extension 3 of the power shaft. The body 28 of the clip is preferably interposed between the portion l2 of the screw shaft and the inwardly extending flange 25' of the re-entry spring thimble 25.

In the operation of this embodiment of the invention, starting with the parts in the positions illustrated in Fig. 1, rotation of the power shaft l causes rotation of the screw shaft ll, whereby the nut member I5 is traversed to the left, moving the pinion 4 into mesh with the engine gear 5 by thrust transmitted through the cushion block ll. When the abutment l of the pinion engages the shoulder 8 on the power shaft, further traversal of the pinion is prevented and the nut member l5 compresses the block [1 of elastically deformable material between the flanges l6 and I until sufficient torque is built up to cause rotation of 'theengine gear 5. When the engine starts, the consequent acceleration of the pinion 4 causes the nut IE to be threaded back off the end of the threads on thescrew shaft ll. Sleeve I 8 cooperates with flanges 1'9 and IE to couple the pinion to the nut member and withdraw the pinion from meshing position, whereupon the "nut member and its associated parts overrun freely until their momentum is dissipated. Thereafter, the parts are maintained in idle position by the anti-drift member :26. When the power shaft l is again actuated, the reentry spring 24 assures engagement of the threads of the nut and :screw shaft.

In Figs. "to 9 of the drawings there is illustrated an embodiment of the invention in which the parts are telescoped in order to shorten the overall dimensions of the drive. The various elements of the drive are the same as illustrated in Figs. 1 to 4 and are similarly numbered with the exception that the block I! of elastically deformable material is in this casemounted on the body portion of the nut member l5 as in the first embodiment of the invention, or may be fixed thereon in any suitable manner. Itwill be readily appreciated that this arrangement while it increases the diameter of the drive to some extent, permits the drive to be formed considerably shorter and consequently made adaptable to installations requiring short drives.

The operation of this embodiment 'is the :same as the first embodiment of the invention.

Although but two embodiments of the invention have been shown and describedindetail, it will be understood that other embodiments are possible and various changes may be made'inithe design and arrangement o'f'the partswithout departing from the spirit of the invention :as defined in the claims'appended hereto.

What is claimed is:

1. In an engine starter drive, a power shaft having a reduced cylindrical portion defined by a shoulder, a pinion having a radial flange slidably journalled on the power shaft for engagement with an engine gear and having an internal abutment adapted to engage said shoulder when inoperative position, said power shaftlhaving :a

further extended portion of non-circular contour, a screw shaft mounted thereon and conforming thereto, locking means preventing 1ongitudinal movement of the screw shaft on the power shaft, a nut threaded thereon having a radial flange, a hollow cylinder of elastically deformable material journalled on the reduced portion of the power shaft between said flanges, and a sleeve enclosing the flanges and maintaining them in initial engagement with the cylinder of elastically deformable material.

2. An engine starter drive including a power shaft having a reduced cylindrical extension and a further reduced extension of non-circular cross section, a flanged pinion slidably journalled on the shaft having an internal shoulder bearing on the reduced portion, a screw shaft fixed on the extended portion of the power shaft having a bore conforming to the non-circular extension thereof, a flanged nut member on the screw shaft, a cylindrical block 01' elastically deformable material frictionally engaging the flanges of the nut member and pinion and compressed therebetween when the longitudinal movement of the pinion is arrested, and a sleeve having a swivel connection with the nut member and pinion and maintaining the cylindrical block in initial compression therebetween.

3. A starter drive according to claim 2 in which the screw shaft is provided with a smooth portion adjacent the idle position of the nut, and friction means mounted thereon to engage the nut and retain it in idle position.

4. A starter drive according to claim 2 in which the screw shaft is provided with a reduced portion adjacent the idle position of the nut member, and a spring clip fixed to the screw shaft adapted .to engage frictionally in the interior of the nut member to retain it in idle position.

5. An engine starter drive as set forth in claim 3 including further means for normally spacing the cylinder of elastically deformable material from .the power shaft to facilitatesliding thereon while permitting the cylinder to grip the Power shaft when compressed by the screw jack action of the screw shaft and nut so as to transmit torque directly from the power shaft to the pinion.

6. 'In an engine starter drive a power shaft having a reduced extension of non-circular cross section, a pinion slidably journalled on'the'power shaft for movement into and out of engagement witha member of an engine to be started, means for actuating the pinion from the power shaft including a screw shaft fixed on the non-circular extension and a nut thereon yieldably connected to the pinion, and an anti-drift member for the pinion fixed on the non-circular extension and frictionally engaging the interior of the nut when in idle position.

'7. In an engine starter drive a power shaft having a reduced extension of non-circular cross section, a pinion slidably journalled on the power shaft for movement into and out of engagement with a member of an engine to be started, means for actuating the pinionfrom the power shaft including a screw shaft fixed on the non-circular extension and a nut thereon yieldably connected to the pinion, and an anti-drift member for the pinion in the form of a washer ,having an opening conforming to the non-circular extension and fixed thereon and having a spring arm frictionally engaging the interior of the nut when in idle position,

BURR W. JONES.

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