US2500133A - Engine starter drive - Google Patents

Description

March 7, 1950 D. L.. MILLER 2,500,133

ENGINE STARTER DRIVE Filed sept. s, 1949 l Jy IN V EN T06.

Patented Mar. 7, 1950 ENGINE STARTER DRIVE Donald L. Miller, Elmira, N. Y., assignor to Bendix Aviation Corporation, a corporation of Dela- Ware Application September 3, 1948, Serial No. 47,638

2 Claims. p 1

The present invention relates to an engine starter drive, and more particularly to starter gearing of the type which automatically connects the starting motor to an engine gear when the starting motor is energized, and disconnects the starting motor when the engine starts.

It is an object of the present invention to provide a novel engine starter drive which is efficient and reliable in operation, simple in construction, and economical to manufacture.

It is another object to provide such a device 4which incorporates a small number of parts, and is easily assembled.

It is another object to provide such a device in which the parts when assembled, are not sub-` ject to displacement or loss of adjustment in use.

The present invention is an improvement on the structure shown in Fig. 4 of applicants prior application, Serial No. 756,464 filed June 23, 1947, now Patent No. 2,481,324, and concerns especially the stop means which defines the operative position of the drive pinion.

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

Fig. l is a side elevation partly broken away and in section of a preferred embodiment of the invention;

Fig. 2 is a similar View showing the parts in cranking position; and

Fig. 3 is a detail in perspective of the screw shaft with the integral stop means for the nut formed thereon.

In Fig. 1 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 retained by a lock ring 4.

A pinion 5 is slidably journalled on the power shaft I for movement into and out of mesh with an engine gear 6. Means for traversing and rotating the pinion from the screw shaft ig provided comprising a nut member 8 threaded on the screw shaft 2 and having a splined connection as indicated at 9 with one end of a barrel II. The opposite end of the barrelY II is rigidly connected as indicated at I2 to a driving overload release clutch member I3 which is journalled on an extension I4 of the pinion against a washer I5 which abuts a shoulder I6 formed by reducing or turning down the teeth of the pinion.

A driven slip clutch member I1 is splined on the hub I4 of the pinion 5 as indicated at I8, and is pressed against the driving clutch member I3 by yielding means here shown in the form of an elastic washer I9 which is retained on the end of the pinion hub by means of a lock ring 2 I.

Means normally holding the pinion 5 and barrel I I in extended relation with respect to the nut 8 is provided in the form of a compression spring 22 within the barrel bearing at one end against the nut 8 and at its other end againsta thrust washer 23 which is fixed in the barrel by a lock ring 24. The nut 8 is retained within the barrel by a split thrust ring 25.

Means normally maintaining the parts in idle position are provided in the form of an anti-drift spring 26 bearing at one end against the nut 8 and at its other end against a thrust ring 21 seated on the end of the screw shaft 2.

As best shown in Fig. 3, the screw shaft 2 is formed with a radial flange to limit the travel of the nut 8 toward meshing position. The threads of the screw shaft are milled right through the flange so as to leave radial lugs 28, 29 and 3| which arrest the movement of the nut 8 when the pinion is in meshed position, a thrust washer 32 being preferably interposed therebetween. The lugs 28, 29 and 3| are turned down for a short distance to provide shoulders 33, 34 and 35 against which the thrust ring 21 seats.

The driving overload release clutch member I3 is provided with inclined torque transmitting teeth 36, and the driven clutch member I1 is provided with corresponding teeth 31 which are pressed together by the spring washer I9 so as to transmit torque from the barrel to the pinion. When a predetermined load is exceeded. the teeth 36, 31 wedge themselves apart against the action of the spring washer I9 and slip off the overload until normal conditions are established.

In operation, starting with the parts as illustrated in Fig. l, rotation of the power shaft I and screw shaft 2 causes traversal of the nut 8 with its associated parts to cause the pinion 5 to mesh with the engine gear 6. The longitudinal travel of the nut 8 is limited by abutment of the nut against the thrust washer 32 which accordingly defines the meshing position of the pinion by its abutment against the radial lugs 28. 29, 3| of the screw shaft. The clutch I3, I1 is preferably so loaded by the spring washer I9 that the initial shock caused by engagement of the pinion with the engine gear is cushioned by slippage of the clutch. After cranking has started, it ordinarily proceeds without slippage of the clutch unless a backfire of the engine should cause resistance to cranking to exceed the predetermined maximum, in which case the clutch will again slip in order to cushion the drive..

If tooth abutment between the pinion 5 and engine gear 6 should occur during the meshing movement of the pinion, spring 22 yields and permits the nut 8 to proceed along the screw shaft 2 until the driving torque builds up sufiiciently to index the pinion teeth into proper registry with the tooth spaces of the engine gear, after which serieel? expands emifelep the pinion into mesh, whereuponrcranking `proceeds as usual.

When the engine res, the parts are returned design arid-arrangement' ef the parts Witheet elepertine time; ilse'egirt clalm' ,e starter-drive@ pewereheft e Se eW- .Sheft 'xes meteen, e vivier-1 Slideblv xeurinalleel Onthe newer shaft for movement wie and eilt of meel; with @seeref engine te be started, a control nut threaded on the screw shaft, a driving clutch member swiveled on the pinion, a barrel member non-rotatably connected at its ends to the nut and driving clutch member, a driven clutch member splined on the pinion, yielding means holding the clutch members in engagement, yielding means transmitting longir tudinalmcveyient from thev nut to the barrel, and .rneanspositivelyconninglthe nut inathe barrel,

thev threads of said screw shaftv having radial 4shoulders in the same plane transverse to the axis of the drive, forming a stop for the control v`n'ut'to thereby dene the fully meshed position providing said dstop shoulders for the control nut.

DONALD L. MILLER.

REFERENCES CITED eine ,following refererieeeam e? '.lfeeerd @il the @ieu-0i this :intenti "UWTED STATE@ BATENTS Date Name

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