US2317327A - Engine starter drive - Google Patents

Description

c. s. JANES ENGINE STARTER DRIVE April 20, 1943.

Filed May 20, 1940 2 Sheets-Sheet l R Y wm wm d i m w &, W

' m which the inertia of Patented Apr. 20, 1943 ENGINE! STARTER DRIVE Clinton S. Janos, Elmira Heights, N. Y'., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application May 20, 1940*, Serial No. 336,249

9 Claims.

The present invention relates to an engine starter drive and more particularly to gearing for connecting a starting motor to a member of an engine to be started.

In connection with the provision of starting equipment for internal combustion engines and more particularly automotive power plants, space limitations are becoming more and more restrictive, particularly as respects the overall length of the drive gearing. The prevalent location of the starting motor at the side of the engine, with the starter drive engaging a ring gear on the engine flywheel, brings the drive gear into close proximity with the floor boards of the vehicle, and frequently necessitates the formation of a clearance recess in the floor, or even a lengthening of the wheel base of the car to accommodate the drive.

Moreover, in engine drives of the type in which a pinion is automatically traversed into mesh with an engine gear by the initial acceleration of. a screw shaft, it is sometimes found that fouling of the screw threads and bearing surfaces with congealed lubricant or foreign matter, delays or even prevents the traversal of the pinion. Increasing the inertia of the pinion by attaching counterweights thereto is not an entirely satisfactory solution of this difficulty since the inertia which resists rotation of the pinion also tends to resist traversal thereof. Moreover, increasing the inertia of the pinion and its associatedparts tends to aggravate rebounding of the pinion toward the engine gear when it is thrown out of mesh.

It is an object of the present invention to provide a novel starter drive which is small and compact, particularly as regards overall length, without sacrificing mechanical strength or durability.

It is another object to provide such a device in which the moving parts are enclosed and protected from the accumulation of foreign matter. It is another object to provide such a, device incorporating provisions to insure traversal of the pinion on rotation of the drive shaft.

It is another object to provide such av device the pinion as respects rotation is increased without increasing its inertia as respects longitudinal movement.

It is a further object to provide such a device in which means are incorporated to prevent rebounding of the pinion toward. the engine gear when it is thrown out ofmesh.

It. is another object. to provide such a device in which, the energy of rebound of .the pinion is dissipated frictionally.

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

Fig. 1 is a sectional view partly in side elevation of a starter drive embodying a preferred form of the invention;

Fig. 2 is an end view thereof from the right in Fig. 1;v

Fig. 3 is a side elevation partly in section of the same structure showing the parts in cranking position;

Fig. 4 is a section line 4-4 of Fi 1;

Fig. 5 is a sectional view partly in side elevation of a second embodiment of the invention;

Fig. 6 is a view similar to Fig. 5, showing the parts in cranking position;

Fig. '7 is an. end view from the right of the structure shown in Figs. 5 and 6; and.

Fig. 8 is a section taken substantially on the line 8-8 of Fig. 5.

In Fig. 1 of the drawings there is illustrated a power shaft l which may be the extended armature shaft of the starting motor, not shown. A driving head member 2 is rigidly mounted on the end of the power shaft I by any suitable means such as a cross pin 3 retained by a lock ring 4. Driving head 2 is provided with a radial flange 5 rigidly fixed thereon in any suitable way as by brazing or welding.

A pinion 6 is slidably journalled on the power shaft for longitudinal movement into and out of engagement with a member such as a gear i of an engine to be started. A screw shaft 8 is fixed in any suitable manner as by welding or brazing on the end of the pinion 5, and a nut member 9 normally in telescopic relation with the pinion 3 is provided with a smooth portion H normally bearing on the periphery of the screw shaft 8, and with internal threads 12 adapted to engage the threads of the screw shaft upon relative rotation thereof. A driven head in the form of a radial flange I3 is formed on the nut 9 or rigidly mounted thereon in any preferred manner, and a yielding driving member l4 here shown in the form of a coiled spring is provided for connecting the driving and driven heads. As here illustrated, the connection is formedby means of slots l5 and I6 formed in the driving. and driven heads respectively and adapted to receive outturned ends I! and I3 of the drive spring M.

A barrelmember l9 enclosing the. moving parts of the drive is provided with an inturnedflange taken substantially on the 2| engaging and forming an abutment for the flange of the driving head 2. A thrust plate 22 is mounted in the opposite end of the barrel l9, being retained therein a by means of a split lock ring 23. Thrust plate 22 is normally engaged by the driven head l3 of the nut member 9 whereby the barrel serves to maintain the drive spring l4 under slight compression. Screw shaft 8 is provided with a shoulder 24 adapted to engage the thrust plate 22 when the pinion 6 is fully meshed with the engine gear 1 so that said plate acts as an abutment to define the operative position of the pinion. As the shoulder 24 of the screw shaft is thrust against the plate 22 by the screw jack action of the screw shaft and nut during the.

cranking operation, torque is frictionally transmitted from the drive head 5 through the barrel l9 and plate 22 to the screw shaft and pinion. The torque transmitted by the frictional clutch connection so constituted is supplemental to the torque transmitted through the spring |4.

Means for insuring initial engagement of the threads of the screw shaft and nut is provided in the form of a spring 25 interposed between the driving head 2 and the pinion. Means normally maintaining the pinion and screw shaft in idle position is provided in the form of an anti-drift spring 26 surrounding the pinion and bearing against a flange 21 in the interior of the thrust plate and the'shoulder 24 of the screw shaft.

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 is transmitted through the drive head '2 and spring M to the driven head I3 and nut 9. The pinion 6 and screw shaft 8, by reason of their inertia as respects rotation, are thereby moved to the left until the shoulder 24 engages the thrust plate 22, at which time the pinion 6 is fully meshed with the engine gear. Further rotation of the nut 9 causes it to move to the right, compressing the drive spring |4 until the end of the nut engages the drive head as illustrated in Fig. 3; The spring I 4 is then wound up by the rotation of the power shaft I until sufficient torque is built up to cause rotation of the pinion 6 to crank the engine. When the engine starts, the acceleration of the engine gear I rotates the pinion 6 and screw shaft 8 faster than the nut 9 whereby the parts return to their normal positions, the screw shaft running off the ends of the threads of the nut and overrunning until its excess momentum is dissipated.

If, during the meshing operation, tooth abutment should occur between the pinion and engine gear, the tendency to jam is relieved by compression of the drive spring |4 until suiiicient friction is built up in the threads of the screw shaft and nut to index the pinion into proper registry with the tooth spaces of the engine gear, whereupon the drive spring expands and snaps the pinion into mesh and cranking proceeds as above set forth.

In the embodiment of the invention illustrated in Figs. 5 to 8, inclusive, the power shaft 3| has a drive head 32 fixed thereon in any suitable manner as by means of a pin 33. A pinion 34 is slidably journalled on the power shaft 3| for longitudinal movement into and out of engagement with a member such as a ring gear 35 of an engine to be started. A screw shaft 35 is rigidly mounted on the rear end of the pinion 34 as by brazing as indicated at 31, and a nut 38 is threaded on the screw shaft and is provided with head. A torsion drive spring 4| surrounds the screw shaft 36 and nut 38 and is provided with outturned ends 42 and 43 arranged to enter radial slots 44 and 45 in the driving head 32 and driven head 39 respectively so as to anchor the ends of the spring to said heads.

A barrel 46 is arranged to surround and enclose the elements of the drive and is provided at one end with a thrust ring 41 adapted to abut against the driving head 32. A thrust plate 48 is mounted in the opposite end of the barrel ad-- I jacent the normal position of thedriven head 39.

As here shown, thrust plate 48 is frictionally connected for rotation with the barrel by virtue of a look ring 49 and washer 5| which retain the thrust plate in the barrel, and a spring washer 52 which bears at its rim against a shoulder 53 in the interior of the barrel and is dished as indicated so as to press the thrust plate 52 against the washer 5|. Thrust plate 48 is preferably provided with internal teeth 54 (Fig. 8) which engage slidably between the teeth of the pinion 34 so as to spline the thrust plate to the pinion. The barrel 46 is thus splined to the pinion 34 through its frictional clutch connection with the thrust plate 48.

The forward end of the screw shaft 36 is arranged to engage the abutment plate 48 when the pinion is fully engaged with the ring gear as illustrated in Fig. 6. An annular recess 55 is preferably provided in the forward end of the screw shaft 36 in order to hous an anti-drift spring 56 which surrounds the pinion and bears at its ends against the abutment plate 48 and screw shaft 36 in order to normally maintain the pinion in idle position.

In the operation of this embodiment of the invention, starting with the parts in the positions illustrated in Fig. 5, actuation of the power shaft 3| by a starting motor, not illustrated, causes rotation of the driving head 32 which is transmitted through spring 4| to the driven head 39 and nut 38. Pinion 34 and screw shaft 36 are initially prevented from rotation both by their own inertia and by the inertia of the abutment plate 48 and barrel 46 which are in effect splined to the pinion. The rotation of the nut 38 therefore threads the pinion and screw shaft to the left, causing the pinion to engage the ring gear 35 until the end of the screw shaft 36 engages the abutment plate 48 as illustrated in Fig. 6. During this engaging movement, it will be noted that the abutment plate 48 and barrel 46 are not required to move longitudinally so that their inertia while effective to prevent rotation of the pinion and a radial flange 39 at one end forming a driven 7.5

screw shaft so as to enforce traversal thereof, does not impede such traversal since at this time the abutment plate and barrel act in effect as a stationary detent splined to the pinion.

After engagement of the pinion with the ring gear, further rotation of the power shaft causes the nut 38 to move to the right, compressing the drive spring 4| until the nut comes into contact with the driving head 32 as illustrated in Fig. 6. At this time, the end thrust of the screw shaft 36 against the abutment plate 48 is transmitted through the barrel to the thrust ring 41 which bears against the drive head'32 so as to take the reaction from the compression of the drive spring 4|. After the drive Spring 4| is thus compressed,

it is wound up by the torque applied by the power shaft to overrun the nut 38 whereby the parts are returned to their idle positions. Rebounding of the pinion into attempted mesh with the ring gear 35 is effectively prevented by the frictional connection between the barrel 46 and the anchor plate 48. When the parts are thrown back to idle position, the barrel 46 continues to rotate until its momentum is dissipated by its frictional connection with the pinion, and during this interval, the pinion is firmly held in its idle position by reason of the torque thus frictionally applied thereto by the barrel.

Although but two embodiments of the invention have been shown and described in detail, it will be understood that other embodiments ar possible and various changes may be made in the design and arrangement of the parts without 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, a

pinion slidably journalled thereon for movement into and out of engagement with a member of an engine to be started, a screw shaft fixed at one end to the pinion, a nut having a driven head threaded on the screw shaft, a driving head member fixed on the power shaft, a yielding driving member compressed between the driving and driven heads by the screw jack action of the screw shaft and nut, and a barrel member enclosing the drive having thrust means at one end bearing against the driving head, and a thrust plate in the other end of the barrel against which the nut is normally maintained by the expansion of the yielding driving connection, said screw shaft having a shoulder adapted to engage the thrust plate 5 to limit the engaging movement of the pinion.

2. In a starter drive as set forth in claim 1, an anti-drift spring located on the pinion and screw shaft between the thrust plate and shoulder urging the screw shaft and pinion toward idle position.

3. An engine starter drive including a power shaft, a pinion journalled thereon for longitudinal movement into and out of engagement with an engine gear, a screw shaft fixed at one end to i the pinion, a nut threaded on the screw shaft and normally in telescopic relation with the pinion, a driving head fixed to the shaft, a driven head on the nut, an abutment defining the idle position of the nut, a yielding driving connection between i the driving and driven heads surrounding the pinion and nut, and a barrel enclosing the drive having a torque-transmitting connection with the pinion supplemental to said yielding driving connection during the cranking operation.

4. In an engine starter drive, a power shaft, a driving head having a radial flange fixed thereon, a pinion journalled on the power shaft, a screw shaft fixed to the pinion, a nut on the screw shaft having a driven head, a yielding driving connection between the driving and driven heads, and a barrel enclosing the drive having a slidable torque transmitting connection with the pinion supplemental to said yielding driving connection.

5. In an engine starter drive, a power shaft, a drive head having a radial flange fixed thereon, a pinion journalled on the power shaft, a screw shaft fixed to the pinion, a nut on the screw shaft having a driven head, a yielding driving connection between the driving and driven heads, and a barrel having a yielding torque-transmitting connection to the pinion supplemental to said yielding driving connection, said barrel having means limiting separation of the driving and driven heads.

6. An engine starter drive as set forth in claim 4 in which the yielding driving connection between the barrel and pinion includes a friction clutch.

'7. An engine starter drive as set forth in claim 4 in which the yielding driving connection between the barrel and pinion includes a friction clutch, and torque-responsive means for tightening the clutch.

8. In an engine starter drive, a power shaft, a drive head having a radial flange fixed thereon, a pinion slidably journalled on the power shaft, a screw shaft fixed to the pinion, a nut on the screw shaft having a driven head, a yielding driving connection between the driving and driven heads, and a barrel enclosing the drive having thrust means in one end engaging the driving head and a thrust plate in the other end splined to the pinion.

9. In an engine starter drive, a power shaft, a drive head having a radial flange fixed thereon, a pinion slidably journalled on the power shaft, a screw shaft fixed to the pinion, a nut on the screw shaft having a driven head, a yielding driving connection between the driving and. driven heads, a barrel enclosing the drive having thrust means in one end engaging the driving head and a thrust plate in the other end splined to the pinion, and a friction clutch connection between the clutch plate and the barrel, the screw shaft having a shoulder engaging the thrust plate to compress the friction clutch responsive to cranking torque.

CLINTON S. J ANES.

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