US2569401A - Engine starter gearing - Google Patents

Description

sept. 25, 1951 J. E. BUXTON 2,569,401

ENGINE STARTER GEARING Filed June 2, 1950 A ORNE Y Patented Sept. 25, 1951 'ferries Claims 1 fsilheapresent. invention relates' to enginerstarter gearing; andvmore.I particularly tofth'atity'pe of fidrive. which engages .an engine gear automatical- .s1-ly whenthestarting-motoriis energizedgfand' disengages when theengineistarts.

.".tIt is kan objectsot the present invention to provide a novel engine starter drive which is eiicient and reliablein'oper'ation, small in size, and simple fand economicalzin construction.

It is another object to provide suchaidevice inlv cluoling an. `elastic connection which is arranged to slip when overloaded so as to protect the drive from-excessive stresses.

` Itis-another objectto--provide such 'a device in which the elastic connection is axially yieldable to assist in securing proper meshing of the gearing in case of tooth abutment between the drive pinion and engine gear.

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

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

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

In Fig. l of the drawing there is illustrated a power shaft i on which a screw shaft 2 is xedly mounted as by means of a cross pin 3 which is retained by a thimble 4 seated against a shoulder 5 on the screw shaft. A pinion 6 is slidably journalled on the power shaft for longitudinal movement into and out of mesh with a gear 'I of the engine to be started.

Means for actuating the pinion from the'screw shaft is provided, comprising a control nut 8 threaded on the screw shaft and seated against a shoulder 9 formed at the termination of the threads of the screw shaft. A cylindrical member II having a radially inwardly directed ange I2 is xedly connected to the pinion 6 as indicated at I3. The control nut 8 has a radial ange I4, and a spring member I5 is seated at one end on the control nut 8 against the ange I4, and at its other end within the cylindrical member I I against the ange I2. The central convolutions of the spring I5 are normally spaced from each other as indicated at I6 so as to make the spring longitudinally compressible.

The dimensions of the parts are such that the' spring engages the interior of the cylindrical member Il and the exterior of the nut 8 with suicient friction to transmit normal cranking loads.

flThe-spring'is so`-3Wou'nd, as indicated, that when #crankingL torquefi`s-y `transmitted therethrough it "fete'nding'to relievethe frictional engagementbetween the spring and the cylindrical member II *sthatslippage takes place upon predetermined l overload/oft thevv drive.

thelcontroliiut-andvlhas 'i-ts' open end rig-idly connected?to-thefcylindrical'vmember II in anysuitable way, as shown at i8. The barrel `jmer'nber has a shoulder I9v which normally engages the `"fthe."spri-n'gi I-5-un'der initial longitudinal lcompression between the anges I4 and I2.

Barrel I1 has a terminal flange 2| resting on the power shaft I and positioned to engage the end of the screw shaft 2 when the drive is in cranking position. Preferably a thrust ring 22 is interposed to reduce wear and to define the meshed position of the pinion 6.

Means normally maintaining the drive in idle position is provided in the form of an anti-drift spring 23 located within the barrel, bearing at one end against the thrust ring 22 and at its other end seated on thethimble 4 against a flange 24 thereof.

Means for limiting the compression of spring I5 is provided in the form of a spacing ring or cylinder 25 located within the barrel I1 between the ange I4 of the control nut and a thrust ring 26 which bears against the end of the cylindrical member I I, so as to limit the travel of the control nut toward the pinion 6.

In operation, starting with the parts in the positions illustrated in Fig. 1, rotation of the power shaft I in the direction of the arrow (a) by the starting motor, not illustrated, causes the control nut 8 to be traversed to the right, which longitudinal movement is transmitted through the spring l5 to the cylindrical member Il, pinion 6 and barrel I1. Should the teeth of pinion 6 abut against the teeth of engine gear 1, the spring I5 is longitudinally compressed by the control nut 8 until sufficient torque is built up to index the pinion teeth into registry with the tooth spaces of the engine gear, whereupon the pinion is snapped into initial-mesh with the engine gear by expansion of the spring I5, and the meshing movement of the pinion proceeds until the movement of the ange 2I is arrested by engagement of the thrust ring 22 against the end of screw shaft 2.

The movement of the control nut 8 is continued until the flange I4 engages the stop ring 25, at

which time the spring I is compressed firmly between the flanges I4 and I2, as shown in Fig. 2. Torque is then built up and transmitted through the spring I5 to rotate the pinion 6 and crank the engine. Should the initial torque due to the inertia of the parts exceed a predetermined overload, the spring I5 wraps down slightly, relieving its frictional connection with th'e interior of the :cylindrical member Ii, thus permitting slippage to take place until the excessive torque is dissipated; whereupon cranking proceeds normally without slippage.

When the engine starts, the acceleration of the pinion `6 by the engine gear I returns the par-ts to idle position with the assistance of the anti-drift spring 23, the backward movement of the control nut 8 being arrested by the shoulder 9 on the screw shaft. When this engagement takes place, the torque transmitted by the momentum of `the overrunning parts tends to unwrap the spring I5 which permits the spring to slip on the control nut v8, and thus cushion the impact and prevent rebounding of the parts such as might cause undesired engagement of the pinion `6 with the engine gear 1. v

Although but one embodiment of the invention has been shown and described in detail, it will be understood that various changes may be made in the precise design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive a power shaft, a screw shaft xed thereon, a pinion slidably jour- 4 nalled on the power shaft for movement into and out of mesh with an engine gear, a cylinder fixed to the pinion, a control nut on the screw shaft, a coiled spring tightly engaging the periphery of the nut at one end, and at its other end frictionally engaging the interior of said cylinder, and a barrel member xedly connected at one end to said cylinder and having a flange at its other end positioned to engage the end of the screw shaft when the pinion is in fully meshed position.

2. An engine starter drive as set forth in claim 1 in which the control nut and cylinder are provided with radial anges engaging the ends of the spring, and the barrel is provided with a shoulder normally engaging the control nut flange and thus maintaining the spring under initial compression.

3. An engine starter drive as set forth in claim 2 in which the medial portion of the spring is provided With longitudinally spaced convolutions rendering the spring endwise compressible.

4. An engine starter drive as set forth in claim 3 including means for positively limiting the end- -wise compression of the spring.

JAMES E. BUXTON.

REFERENCES CITED UNITED STATES PATENTS Name Date Brockway June 14, 1932 Number

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