US2167891A - Engine starter drive - Google Patents

Description

Aug. 1,4939. c. 5. JAMES 2,157,391

' ENGINE STARTER D'RIVE Filed Nov. 15, 1936 4 Sheets-Sheet 1 TEJRNEY.

' Aug. 1, 1939. c. s.JAN1-:s

ENGINE STARTER DRIVE Filed Nov. 13, 1936 4' Sheets-Sheet 2 INVENTOR.

V ATTORNEY.

Aug. 1, 1939. c. s. JANES ENGINE STARTER DRIVE 4 Sheets-Sheet 3 Filed Nov. 13, less INVENTOR.

Aug. 1, 1939.

c. s. JANES ENGINE STARTER DRIYE Fild Nov. 15, 1936 4 Sheets-Sheet 4 INVENTOR.

Blirdonffidmea BY 7123f W "ITORNEY.

Patented Aug. 1, 1939 ENGINE STARTER DRIVE Clinton S. Janes, Elmira, N. Y., assignor, by mesne assignments, to Bendix Aviation Corporation, South Bend, Ind., a corporation oi. Delaware Application November 13, 1936, Serial No. 110,749

12 Claims.

This invention relates to an engine starter drive and more particularly to a transmission of the type which automatically connects a starting motor to an engine upon energiza'tion of the motor, and disconnects the same after the engine has become self-operative.

Starter drives of conventional type which are disengaged by the overrunning of the drive pinion when the engine starts are subject to the condition that if the engine should stall after the pinion is demeshed by the initial explosions, it is necessary to deenergize the starting motor and allow it to decelerate in order to secure reengagement of the pinion and resumption of the cranking operation by reenergizing the starting motor. 1

In some cases, especially when this condition of false starting is'prevalent and persistent, it is preferred to utilize a form of transmission which is not disengaged by the initial explosions ,of the engine, but merely overruns and resumes cranking as soon as the engine slows down to a speed corresponding to that of the starting motor.

It is an object of the present invention to provide a novel engine starter drive of" the automatic mesh and demesh type, in which the engagement of. the parts is maintained irrespective of false starts or abortive explosions of the engine. I

It is a further object to provide such a device in which engagement of the drive-is maintainedduring acceleration of the starting motor, irrespective of acceleration of the engine member due to self-operation thereof. It is another object to provide such a device in which the pinion is permitted to overrun the starting motor during periods of rapid acceleration of the engine unember, while remaining in meshed relation with the engine member. It is another object'to provide such a device in which meshing of'the drive is accomplished by acceleration of the starting motor, and demeshing is controlled mainly by deceleration thereof.

It is a further object to provide such a device embodying automatic braking means fdr the starting motor when it is deenergized.

It is another object to provide such a device embodying novel provisions for indexing the pin- Further objects and advantages will be appar 5:; cut from the following description taken in con- 'fixed to the power shaft in any suitable manner nection with the accompanying drawings in which:

Fig. 1 shows a side elevation partly in section of a preferred embodiment of the invention;

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

Fig. 3 is a similar view showing the parts in the positions assumed during overrunning of the engine member while the drive pinion is in engagement therewith; 10

Fig. 4 is a section taken substantially on the line 4-4 of Fig. 1;

Fig. 5 is a view similar to Fig. 1 showing the parts in the positions assumed in case during the meshing operation a tooth of the pinion abuts 15 against a tooth of the engine member;

Fig. 6 is an expanded detail in perspective of the traversing nut and barrel members;

Fig. '7 is an expanded view in perspective of the pinion and its associated parts including the screw and nut member;

Fig. 8 is a side elevation partly in section of a second embodiment of the present invention; Fig. 9 is a similar view showing the parts in driving position; 25

Fig. 10 is a similar view showing the parts in ,the positions assumed during overrunning of the engine member; f

Fig. 11 is a section taken substantially on the line of Fig. 8;

Fig. 12 is a view similar to Fig. 8 showing the parts in the positions assumed in case of tooth abutment between the pinion and engine member;

Fig. 13 is an expanded detail in perspective 35 V showing the barrel and traversing pinion, the barrel being broken away for the sake of clarity; and

Fig. 14 is a similar view of the pinion and its associated parts.

as indicated at 4 and 5, and has slidably mounted thereon a screw shaft 6 incorporating a driven head I in spaced relation:tof;-;the driving head 3.- A pair of anchor members 'fi'l-and 9 in the form 50 of spirally shaped discsfare non-rotatably mounted on the driving and-"driven heads respectively and are provided with openings H and [2 (Figs. 4 an 2) adapted to receive the outturned ends l3 d ll offa drive spring I5 which thereby con- I having a threaded connection with the screw shaft and also having a second threaded connection with the pinion; The threaded connection between the barrel and the screw shaft 6 is formed by a nut l9 rigidly fixed in one end of the barrel It as by means of radial projections 2i on the nut located in slots 22 of the barrel and retained therein by means such as a split thrust ring 23.

The threaded connection between the barrel and pinion comprises a nut member 24 having radial projections 25, located in the slots 22 of the barrel and held against longitudinal movement in the barrel by engagement against the shoulders 26 at the ends of the slots 22 on one side, and by the spacing and reenforcing cylinder member 21 surrounding the middle portion of the barrel l8 and spacing the nut members 2| and 25 in the barrel. I

A screw member 28 is fixed to the pinion in any suitable manner as by means of splines 29 (Fig. 7) in the screw member engaging in the spaces 3| between the extended portions of the teeth 32 of the pinion. A thrust ring 33 is 10- cated on the pinion back of the screw member 28, and the parts are retained in assembled position by suitable means such as a bushing 34 having a shoulder 35. abutting against the ends of the splines 29' and being spun outwardly into the flared portion of the pinion as indicated at j'l in Fig. 1 in order to clamp the parts together. It will be noted that the screw member 28 is provided with a smooth portion 38 (Fig. 7)

on which the nut 24 rests when the parts are in idle position whereby the pinion is free to overrun the nut member 24.

A stop nut 39 is fixed onthe end of the sleeve 2 beyond the screw shaft 0, and a thrust disc ii is interposed between the end of the screw shaft 6 and the stop nut. -A thrust'ring 42 is looselymounted on the screw shaft to limit the travel of the nut I 9 to the left with respect to the sleeve 2, whereby furthertrayel of the nut- IS on the screw shaft 6 after engagement with the thrust ring 42 causes-the-screw shaft 8 to move to the right and compress the drive spring It as illustrated in Fig. 2.

Means for yieldably the nut I! in idle position is provided -intthe form. of an anti-drift spring 4 ocated between said nut and periphery of the thrust 'disc I. The screw shaft! is preferably provided witha smooth portion 45 at the-idle position of the nut 19 so as to. permit nut with the I screw shaft when tbelatter is accelerated.

barrel It and its associated parts to overrun the -Mean s are provided for initial entry of thenut "into the threads'of the screw shaft in the form of a reentry spring 46 located between thenut fl and the flange 44 of the thrust disc ,and means for insuring reentry of the nut'lf'in' the threads of the screw member 2! is provided in the form of a spring member 41 (Fig. '7) located between the nut 21 and the thrustringlt;

'01 its parts. This.

In the operation of this embodiment of the invention, starting with the parts in the positions illustrated in Fig. i, rotation of the power .shaft I when the starting motor isenergized causes the screw shaft 6 to rotate therewith by virtue of the driving connection through the its associated members, due to their inertia, do not immediately partake of this rotation, they are traversed by the threaded action of the nut I! on the screw shaft 8 until said nutengages the thrust ring 42, at which time the pinion It is placed in initial engagement with the engine gear ll as illustrated in Fig. 3. Since the further threaded action of 'the nut I! on the screw shaft 6 is resisted by the compression of the drive spring IS, the barrel I8 is caused to rotate, and

since the pinion I6 is prevented from rotation by its engagement with the engine gear II, the

pinion is projected into full mesh with the flywheel gear by the threaded engagement between the nut 24 and screw member 28 as illustrated in Fig. 2. When the pinion It has reached the end of its traversal in the barrel llas defined by the engagement of the thrust ring I! with the shoulder ill on the end of the barrel, the

pinion is forced to takeup the rotation of the drive spring l5. Inasmuch as the barrel l8 and barrel and consequently transmits this rotation the barrel It, as illustrated in Fig. 3, until the screw member 2truns out of the nut 24, whereupon the pinion is permlttedto overrun freely as long as it is driven by the engine gear faster than the rotation of the barrel, It will be noted. however, that the pinion It remains in engagement with the flywheel I! so that if the engine does not continue to fire, the pinion will be again moved into full engagement with the engine gear and cranking will beresumed as soon as the dywheel gear slows down to aspeed corresponding with that of the power shaft I. This toe hold" of the pinion in the engine gear while it is overrunning the barrel, is maintained by reason of the fact that the starting motor is rapidly accelerating due to the temporary relief of the cranking load, so that the barrel is firmly held-by its rotative inertia in its. fully traversed position as shown in Fig. 3.:

When atrue start of the engine issecuredand it continues to be self-operative, d

lofthestarting motorduetotheopeningofits cranking circuitby the operator orbyasuitable automatic starter control, causes the starting motor to decelerate quite rapidly due to the friction by reason of the momentum of the barrel and its associated parts.- in conjunction with the effect of the anti-drift s ring is and the rotativedrag of the screw member 28 as it overruns the barrel, comes the barrel to overrun the deceleratingserewshsft l thelperiphery thereof. If it should be deemed de- 7 sirable to still further increase the momentum of those parts, it may readily be done in any suitable way as by increasing the thickness of the barrel l8 or of the cylinder'ZI.

Means are preferably provided for yieldably maintaining the pinion It in its idle position in the form of an anti-drift spring therefor.

If, during the meshing operation, the teeth of the pinion It should abut against the ends of the teeth of the flywheel gear as illustrated in Fig. 5, traversal of the barrel is resisted by this abutment. The screw shaft .6 is thus forced back, compressing the drive spring l5, thus causing the progressive tightening of the threaded engagement between the nut and screw shaft and transmission of torque to the barrel to index the pinion. The frictional engagement between the nut 24 and the thrust ring 33 on the, pinion is ordinarily sufficient to, transmit this torque to index the pinion, but if this purely frictional engagement between the nut and thrust ring he found insufficient under somecircumstances, it may be preferred to form serrations or other positive clutching means upon these elements to transmit the indexing torque as illustrated at 5| and 52. It will be noted, of course, that the reentry spring maintains these serrations out of engagement during the over-running of the pinion. i

The embodiment of the invention illustrated in Figs. (Mo 14 inclusive differs from that previously described mainly in the novel form of indexing means provided for insuring proper mesh of the starting pinion with the engine'member. As illustrated iniFig. 8, a power shaft 6| has a sleeve 62 suitably fixed thereon, which sleeve carries a screw shaft 63 driven from the sleeve by means of a drive spring Bl, all as previously described except that the drive spring 64 is close wound without the spaces between the convolutions provided in the drive spring i5 of the first embodiment, and the longitudinal motion of the screw shaft 63 is limited to only that sufficient to close the clutch formed by the opposing surfaces of the drive head 65 and driven head 66 against the interposed thrust washer 61.

A pinion 88 is freely mounted on the power shaft GI in position to move into and out of engagement with an engine gear 69, and has fixed thereto a screw member 1| threaded into the end of a barrel member I2 and suitably retained therein as by means of a split thrust ring 13 in the end of the barrel. This thrust ring is seated in a circular groove adjacent the end of the barrel, and may, if desired, be further held in place by spinning over the end of the barrel as shown in Figs. 12 and 13. The barrel is provided with a smooth portion I4 adjacent the threaded portion which permits the screw member Ii to run .off the ends of the threads and overrun freely.

Means for driving the barrel from the screw shaft 63 is provided .in the form of a nut I5 an- ,the nut 'IIi in idle position in the form of an antidrift spring I! bearing against saidnut and the the threads-of the screw shaft 83. A second pog sitioning spring 83 located, between the. screw member II and the thrust ring 82 yieldably urges the screw member ll into initial engagement with the threads in the interior of the barrel I2 during overrunning of the pinion as illustrated in 19 Fig. 10.

In this embodiment of the invention, the pinion 68, when in normal position as illustrated in Fig.

8, is protruded from the barrel to its maximum I extent. This is accomplished, as there illustrated, 15

by extending the stop nut 11 by the formation thereon of a conical clutch element 84 arranged to engage in a conical seat 85 formed in the end" of the pinion bushing 86. During the demeshing of the drive, the extension 84 of the stop nut limits the traversal of the pinion which is thus retarded with respect to the barrel, causing the pinion to thread itself out of the barrel to its idle or extended position shown in Fig. 8. The positioning spring 83 assists this action and yieldably maintains the pinion in its extendedposition.

In the operation of this embodiment of the invention, rotation of the power shaft 6! transmitted throughthe drive spring to the screw shaft 63 causes the nut I5 to be traversed along 30 the screw shaft into engagement with the thrust member I8, thus moving the pinion 88 into driving engagement with the engine gear 69 as illustrated in Fig. 9. Further rotation of the power shaft causes the pinion to be rotated to crank 3| the engine. When the engine starts, the acceleration of the flywheel gear causes the pinion starting motor due to the release of the cranking 45 load thereon. If the engine fails to continue in operation, the pinion will be moved back into driving engagement therewith by the threaded engagement between the screw member II and the barrel I2,whereupon cranking will be re- 50 sumed until a true start is secured. Thereupon deenergization of the starting motor and consequent deceleration of the power shaft 6| cooperates with the spring I9 and the overrunning drag of the pinion to cause the barrel I2 to be traversed back to idle position where it will overrun the screw shaft until the momentum of the parts is dissipated. During .this return movement of the barrel I2, the pinion i8 is threaded out to its normal position by the cooperation of the clutchw ing surfaces 84 and 85 in conjunction with the action of the spring 83 as above setforth.

If. during the meshing operation of this embodiment of the invention, tooth abutment shouldoccur between thepinion B8 and engine gear 69, the longitudinal movement of the pinion 68 will be temporarily arrested, whereupon the threaded connection between the pinion and barrel is effective by reason of the continued longitudinal movement of the barrel to index the pinion'into proper registry with the flywheel teeth, whereupon the expansion of the spring 83 will insure proper engagement of the pinion and engine gear teeth. It will be understood that the pitch of the threads of the barrel I2 and pin- A reentry spring II located be- Thereafter 9 moving the pinion into driving engagement with ion screw member H is sumciently steep to secure effective mesh-enforcing action thereof,

while readily permitting the overrunning action of the pinion when the engine fires. It is to be understood that the formation 0 the threads integrally with the barrel is merely an optional arrangement permitting a reduction in the diameter of the barrel, and that the threads may be formed on a separate nut member such as illustrated at 24 in the first embodiment of the invention, if so desired.

In connection with either of the embodiments of the invention illustrated, it may, under some circumstances, be desirable to provide automatic means for increasing the rate of deceleration of the starting motor when it is deenergized in order to more positively control the demeshing action of the barrel It or 12. One form of such means is illustrated in Figs. 8 and 12 in the form of a brake cylinder II surrounding the drive spring 6. in frictional engagement therewith and prevented from rotation by being mounted on any suitable fixed support such as the frame of the starting motor 80. It will be readily appreciated that during the transmission of torque.

from the power shaft II to the screw shaft 63, the drive spring '4 will be wound up by the torque exerted whereby its diameter will be decreased and the friction between the periphery of the spring and the brake member will be relieved. However, when the starting motor is deenergized and the screw shaft with its associated parts tends to overrunthe starting motor, the spring will be expanded into frictional engagement with the brake cylinder, thus causing of the starting motorand engines, a power shaft, a pinion mounted thereon for movement into and out of engagement with a member of an engine to be started, and means responsive to acceleration of the power shaft for er'shaft for moving the pinion out of engagement with the engine member and returning it to idle position.

2. In an engine starter drive, a power shaft, a barrel member threaded thereon, a stop member limiting longitudinal movement of the barrel on the shaft, and a pinion threaded in the barrel and movable thereby into and out of engagement with a member of an engine to be started, said pinion being arrangedato run off ber limiting longitudinal movement of the barrel 4 on the shaft, a pinion threaded in the barrel, normally projecting therefrom, and movable thereby into and out of engagement with. a member of an engine to be started, said pinion being arranged to telescope into the barrel and run of! the threaded connection therewith responsive to 1 acceleration of the engine member, and means for reengaging the threaded connection of the pinion in the barrel and causing the pinion to project' from the barrel when the barrel returns to idle position.

4. In an engine starter drive, a power shaft, a barrel member having a threaded connection therewith for longitudinal movement with respect thereto and rotary movement thereof and therewith, and an engine driving. member mounted in said barrel projecting therefrom and movable therewith into and out of engagement with a member of an engine to be started, said driving member and barrel having an inclined connection abutment of the pinion with the engine member to index the pinion, said last means also serving to move the pinion into podtion to overrun the power shaft while remaining in operative engagement with the engine. member when the engine starts.

' 6. In an engine starter drive, a starting motor, a shaft driven thereby, a pinion moimted on said shaft for longitudinal movement into and out of engagement with a member of an engine to be started-means ve to acceleration of said shaft for moving the pinion into driving engagement and maintaining said engagement irrespective of self -operation of the engine, and responsive to deceleration of the shaft for moving the pinion out of driving engagement, and normally opem tive braking means for said shaft including an element of the moving means rotatable with said shaft, and a fixed braking element normally in engagement therewith but disengaged therefrom during energization of the starting motor.

7. In an engine starter drive, a starting motor, a shaft driven thereby, a pinion mounted on said shaft for longitudinal movement into and out of engagement with a member of an engine to be started, means responsive to acceleration of said shaft for moving the pinion into driving engagement and maintaining said engagement irrespective of self-operation of the engine, and responsive to deceleration of the shaft for moving the pinion out of driving engagement, and braking means for said shaft including an element of the v .moving means rotatable with said shaft, and a fixed braking element disenglged therefrom while the starting motor actuates thedrlve, but engaged thereby whenthe starting motor is de-.

energized and the drive tendsto overrun the startingmotor.

8.Inanenginestarterdri ve,-apowershaft,a-

pinion, and means for. operating the pinion from the power shaft including two inclined connections in series, both connections cooperating toautomatically traverse the pinion into and out of driving engagementwith a member of the engine to be'started, one-connection including discon- 2,167,891 necting means operative upon acceleration of the a power shaft,

member, and an overunning connection between the inertia member and pinion, said first overrunning connection including means responsive to acceleration and deceleration of the power an overrunning while being maintained in 00- shaft to move the pinion into and out oi mesh with a member 01' an engine to be started.

10. In an engine starter'drive, a power shaft, a pinion, an inertia member, an overrunning connection between the power shaft and inertia memher, and an overrunning connection between the inertia member and pinion, said first overrunning connection including means responsive to accelerationand deceleration of the power shaft to move the pinion intoand out of mesh with a member of an engine to be started, said second overrunning connection including means for indexing the pinion in case the meshing movement of the pinion is obstructed.

11. In an engine starter drive, a power shaft, a. screw shaft, 9. driving connection therebetween, a barrel member having a threaded connection 4 tion therebetween,

that the barrel celeration of said screw shaft.

, ber limiting longitudinal movement 5 with the screw shaft, stop means limiting longitudinal movement of screw; and a pinion power shaft, said terengaging means forming an inclined connecthe pinion being movable by the barrel into and out of engagement with a member of the engine to be started, said interengaging means being so formed that they disengage so that the pinion overruns the barrel responsive to self-operation of the'engine, and said threaded connection being so dimensioned runs off the end of' the threads and overruns the screw shaft, responsive to deslidably mounted on said 12. In an engine starter drive, a powershaft, a barrel member threaded thereon, a stop memof the barrel on the shaft, a pinion threaded in the barrel and movable thereby into and with a member of an engine to be started, vand means in the barrel limiting longitudinal movement of the pinion with respect thereto, the threaded connections between the shaft and barrel and between the barrel and pinion terminating adjacent the positions said parts as-' sume when the pinion is out of engagement with the engine member, so as to form overrunning connections therebetween.

out of engagement the barrel on the shaft pinion and barrel having in- CLINTON 8 JANES.

Images