US1995520A - Engine starter - Google Patents

Description

March 26, 1935. s fi I 1,995,520

ENGINE STARTER Filed Dec. 15, 1952 1v VEN TOR 4 BY SekeLLa/ m/ ATTORNEY Patented Mar. 26, 1935 UNITED STATES ENGINE s'maran Youston Sekella, Elmira. Heights, N. Y., assignor to Eclipse Machine Company, Elmll' corporation of New York Application December 15, 1932, Serial No. 647,447

7 Claims.

The present invention relates to engine starters and more particularly to a starting device of the type which when' actuated by a starting motor automatically engages and drives a member such as a gear on the flywheel of the engine to be started, and is automatically disengaged when the engine starts. 4

The reduction in the size and weight of flywheels for automotive engines to a point where such elements can hardly be recognized as flywheels has rendered it desirable in the interest'df quiet and efficient operation that the starting device therefor be particularly adapted to the high torque and extremely rapid accelerationsencountered. In particular it is desirable'to provide as small a drive pinion 'as possible in order to secure a suitable gear reduction, and to incorporate special means for preventing the pinion from hunting or pumping back and forth as the engine goes over the compression-points dur' cranking, and from rebounding against the en.- gine gear when it is thrown out of mesh after the engine starts.

Itis an object of the present invention to provide a starter drivewhich is particularly adapted to installations of this character, and which is eflicient and reliable in operation particularly in connection with engines having low rotational inertia.

It is another object of the invention to provide such a device which is small in'diameter and permits the use of a comparatively small driving pinion whereby it is adapted formounting in a confined space, and furnishes a high gear reduc- 35 tion from the motor in connection with' compara- Ltively small engine gears.

A further objectis to provide sucha device which includes structure for preventing the driving pinion from hunting or pumping during the cranking operation.

It is another object of the invention to provide such a device which is constructed to prevent rebounding of the pinion toward the engine gear when it is thrown out of mesh. Further objects and advantages will be ap parent from the following description taken in connection with the accompanying drawing in which: Fig. 1 is a side .view partly in section of a preferred embodiment of the invention, showing the parts in their normal .or idle position;-

Fig. 2 is a similar view showing the parts in driving position} Fig. 3 is a side view of the'device embodying a balanced form of drive spring; and

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

Referring first to Fig. 1 of the drawing, there is illustrated a power shaft 1 which may be the extended armature shaft of a starting motor, not 6 shown; and which carries and'drives the starting mechanism. A hollow screw shaft 2 is .free y journalled on the power shaft .1 and is provided at one end with a cylindrical enlargement or driven head 3 which is, arranged to be driven 10 from the power shaft 1 by'means of a yielding driving connection in the form of a spring 4 suitably anchored as by means of a bolt 5 to. the driven head 3', and by means of a bolt 6 to a driving head '7 fixed in any suitable manner to the 15 power shaft 1. The driving and driven heads 7 and 3 are preferably arranged to telescope as indicated at 8 in order to form an internalsupport for the spring 4. i

A nut member 9 is mounted on the screw shaft '20 2 in position to engage the threads 11 thereof, and is rigidly connected as by means ofa barrel member 12 to a driving member in the form of a pinion 13 which is freely joumalled directly on the power shaft 1 beyond the end of the screw 25' shaft 2. The motion of the nut 9 along the threads 11 of the screw shaft is transmitted by the barrel 12 to the pinionlB to cause said pinion to engage and disengage a member of the engine .to bestarted such as a gear member 14. .The .30 driving position of the pinion 13 is determined by suitable stop means in the form of an abutment 15 threaded on the end of the screw shaft 2 in position to engage the nut 9 and limit its travel toward the engine member. The disengag 35 ing movement of the nut 9 is limited by the termination of the threads 11 on the screw shaft which are cut away adjacent the idle position of I the nut 9 to leave a smooth portion 16 on-the screw shaft on which the nut 9 may rotate for- 40 ward freely.

The abutment 15 is provided with a radial flange 17, and a short spring 18 is provided withinthe'barrel 12 adapted to bear against the end of said barrel and the flange 17 when the nut 9 is 45 in idle position, and to thereby urge the nut into initial engagement with the ends of the screw threads 11'so as to insure the engagement of the nut with said screw threads when the screw shaft rotates forwardly. A light anti-drift spring 19 is providedin the barrel 12 between the flange 17 of the abutment 15 and the nut 9 for preventing the pinion from drifting toward the engine gear when the power shaft is' stationa y, due

to vibration or other causes.

According to the present invention means are provided for yieldingly holding the pinion 18 in engagement with the engine gear 14 during the cranking operationso as to require a positive thrust of considerable force to initiate the disengaging movement of the pinion. As here shown, this means comprises a plurality of radi; ally movable detents 21 mounted in said barrel so as to project inwardly and engage a bevelled surface 22 on the edge of flange 17. The normal position of the detents 21 is suitably determined as by means of shoulders 23 thereon, and means are provided for yieldingly urging the detents toward normal position in the form of an elas-' tic band 24 arranged to encircle the barrel 12 and bear on the outer sides of the'shoulders 23 of detents 21. The detents 21 are preferably arranged to be unequally spaced about the barml 12 as best shown in Fig. 4 in order to take advantage of the multi-lead thread 11 todistribute thewear on the flange 1'7 of the abutment 15. That is to say, since the pinion runs off the ends of the threads 11, its angular relation with respect to the screw shaft when in pinion13 and barrel 12 is prevented by'the in- 9 and barrel 12 to rotate the pinion 13 andcause driving position will depend on which thread on the shaft happens to engage any particular thread space in the nut, and hence will vary according to the law of averages. Since the detents 21 are unequally spaced around the barrel 12 no two detents will engage the same portion of the flange 17 whereby the useful life thereof is prolonged. In the example here shown the thread 11 is a triple lead thread and there are three detents 21 spaced circumferentially at angles of and around the barrel 12.

In Fig. 3 there is illustrated a modification of the yielding driving connection in the form of a spring 4a arranged with its terminal anchorages circumferentially spaced apart. It will be appreciated that this providesa balanced structure whereby wear on the bearings and noise due to looseness of the bearings is reduced.

' In the operation of this device, starting with the parts in the position shown in Fig. 1, rotation of the power shaft 1 in the direction of the arrow (a) is transmitted through the spring 4 to the screw shaft 2 whereby the nut 9, by reason of its rotational inertia is caused to traverse along the threads 11 into engagement with the abutment 15, thereby forcing the detents 21 over the flange 17 and moving the pinion 13 to driving position as shown in Fig. 2. It will be noted that the pinion 13 is partly meshed with the engine gear 14 prior-to the engagement of the detents 21 with the flange 1'7, so that rotation of the ertia of the engine, and the detents 21 are ac-" cordingly forced over the flange l'l'into the position illustrated in Fig. 2. Further rotation of the power shaft 1 is transmitted through the nut the engine to be cranked.

During this cranking operation, minor accelerations of the engine gear 14 such as those caused by the engine passingover its compression points are ineffective to move the pinion 13 awayfrom its driving position by reason of the substantial resistance offered by the engagement of. detents 21 with the flange 17. When the engine starts, however, the rapid acceleration thereof causes the pinion 13 to overrun the power shaft 1 and force the detents 21 back overthe flange 17, whereby the :pinionis thrown back out of mesh with the engine gear. It will be understood that the rapid acceleration of the pinion and barrel at this time causes a substantial centrifugal force toact upon the detents 21 which reduces materi y the resistance of the detents 21 to the demeshing action. When the pinion 13 is thus thrown back out of mesh with the engine gear 14, the nut 9 runs off the ends of the threads 11, and the further longitudinal motion of the barrel and pinion assembly is arrested by the spring 18 so that the nut 9 when it comes to rest with respect to the screw shaft 2 is urged into initial engagement with'the threads 11 as above described.

What is claimed is:

1. In an engine starter drive, a screw shaft,

"a nut threaded thereon, a member adapted to engage and drive a member of an engine to be started, an abutment on said screw shaft limiting the travel of the nut thereon in one direction, a barrel member connecting said nut and driving member, and cooperating means on said abutment and barrel member including a yielding detent for resisting the disengaging movement of the driving member.

2. In an engine starter drive, a screw shaft, a.

nut threaded thereon, a member adapted to engage and drive a member of an engine to be started, an abutment on said screw shaft limiting the travel of the nut thereon in one direction, a barrel member connecting said nut and driving member, and cooperating means on said abutment and barrel member including a flange on said abutment and a yielding detent in said barrel arranged to contact said flange and resist disengaging movement of the driving member.

3. In an engine starter drive, a screw shaft, a nut threaded thereon, a member adapted to engage and drive a member of an engine to be started, an abutment on said screw shaft limiting the travel of the nut thereon in one direction, a barrel member connecting said nut and driving member, said nut being arranged to rim off the threads of the screw shaft when the driving member moves to idle position, and means for holding the driving member in engaging position including a plurality of yielding detents mounted on said barrel, and an element having a flange rigidly mounted on said screw shaft in position to cooperate with said detents.

4. In a starter drive a shaft, an actuating member mountedthereon for longitudinal movement with respect thereto and having an overrimning driving connection therewith, a member adapted to engage and drive a member of an engine to be started and rigidly connected to said actuatin member, and means for holding the driving mem- 5. In a starter drive, a screw shaft, a nut ber in driving position including a detent mountand drive a member of an engine to be started and rigidly connected to said nut, and means for holding the driving member in driving position shaft for engaging said detents, said screw shaft having a multi-lead thread terminating adjacent the idle position of the nut whereby the nut runs off-said thread when it is moved-to idle position, said detents being unequally spaced circumferentially of the shaft. v

6. In an engine starter drive, a power shaft, a driving head-fixed thereon, a screw shaft journalled thereon and having a driven head, a coiled drive spring surrounding said heads and anchored thereto, anut threaded on said screw shaft, a driving member journalled on the power shaft, means rigidly connecting the pinion and nut, means on the screw shaft for limiting the longitudinal movement of the nut thereon to define the driving position of the pinion, the nut being arranged to run off the threads of the screw shaft when the pinion is returned to idle position.

7. In an engine starter drive, a power shaft, a screw shaft journalled thereon and connected to be driven thereby, a nut threaded on said screw shaft, a drivingmember freely journalled on said power shaft, a barrel member rigidly connecting said nut and driving member, an abutment member on said screw shaft having an inclined flange within said barrel, a plurality of radially movable detents in said barrel in position to be forced over said flange when the driving member is moved to driving position, and yielding means for urging said detents against said flange to retain the driving member in driv- 10 ing position.

YOUSTON SEKEILA.

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