US2762224A

US2762224A - Engine starter coupling mechanism

Info

Publication number: US2762224A
Authority: US
Publication date: 1956-09-11
Anticipated expiration: 1973-09-11

Description

'Sept. 11, 1956 H. HOEFENER EI'AL 2,762,224

ENGINE STARTER COUPLING MECHANISM Filed May 23, 1955 FIG. 1

INVENTORS HE NR) TROEGE/P HOWARD HOEF 5 NE A AITOR/VE) United rates tuatent Q ENGINE STARTER COUPLING MECHANISM Howard Hoefener, Teaneclr, and Henry Troeger, Ramsey,

N. 1., assignors to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application May 23, 1955, Serial No. 510,446

7 Claims. (Cl. 74-7) This invention concerns new and useful improvements in engine starters. It is more particularly concerned with engine starter mechanism for coupling the starter to the engine and for automatically uncoupling the same.

The mechanism of the present invention finds particular use in association with high speed engines, such as might run at a speed of 18,000 R. P. M. At this high speed conventionally used restoring springs are apt to bind, and are ineffective to restore the starter jaw mechanism after the engine has started.

A general object of the invention is to provide starter mechanism suitable for association with such high speed engines.

A further object of this invention is to provide novel and improved means for restoring the starter jaw of starter mechanism associated with high speed operating engines.

A still further object of the invention is to provide an inertia fiyweight type mechanism for efiecting engagement of a starter jaw with an associated engine and for effecting subsequent restoration of the starter jaw.

The invention further lies in its particular construction,

in the arrangement of its elements, and in their particular combinations and cooperative association with one another to effect the purposes intended. The foregoing and other objects and advantages of this invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings, wherein an embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawings are for purposes of illustration and description and are not to be construed as defining the limits of the invention.

In the drawings:

Fig. l is a longitudinal section through engine starter mechanism embodying the invention; and

Fig. 2 is a fragmentary left end view of Fig. 1.

In describing the invention in further detail, reference is directed to the drawings, wherein there is disclosed a starter main drive shaft 1 supported for rotation in proper bearings 2 and adapted to be driven by suitable motor means, not shown. An elongated barrel member 3 surrounds the drive shaft, and is engaged for rotation with the latter by a suitable slip clutch 4, here of the discpack type. A member 5 fixed upon the drive shaft and forming part of the slip clutch provides a radial flange 6 that serves as a backing plate for the clutch pack. Surrounding the left end of the drive shaft is an elongated cylindrical axial extension 7 of member 5. Sleeving extension 5 and axially slidable thereon is the shaft end 8 of a starter coupling member 9. The jaw head 10 of the latter is engageable with an opposed complementary jaw head 11 of an associated high speed type engine drive shaft. The starter jaw shaft 8 is slidably engaged at the left end thereof by straight splines at 12 with complementary splines of a surrounding screw member 14. The screw member is in turn engaged, as at 15, by external helical threads with complementary threads in- 2,762,224 Patented Sept. 11, 1956 ternally of a surrounding extension 16 of the barrel member. By this structure, it is clear that rotation of the barrel member will carry the screw member 14 and the starter member 9 about with it.

Novel means generally indicated at 18 is operable to exert a dragging action upon the sore" member 14 as the barrel member rotates. This effects axial advancemen of the screw member to the left.

This movement of the screw member operates to advance the starter jaw head into engagement with the associated engine jaw. To effect this, the right end of the starter shaft carries a heavy ring 19 which limits against a snap ring 21 fitted in the interior wall of the screw member. A coil spring 22 about the starter shaft, limited at one end by the splines 12 of the screw and starter shaft and limited at the other end by the heavy ring 19, holds the starter jaw in its normal position. In this position the ring 19 is limited against the snap ring 21 of the screw member. By this structure it is plain, that leftward advancement of the screw member will slide the starter jaw member along with it.

The novel means indicated at 18 for effecting axial advancement of the screw member and of the associated starter, also serves to effect return of these members. This screw advancement and return means comprises a plurality of heavy lugs 23 pivotedly mounted in radial slots 24 formed in a thickened rib 25 projecting from the marginal end of the left face of a radial end flange 26 of the barrel member. The lugs 23 are four in number, spaced equally apart, though only two are shown in Fig. 1. These cooperate with the screw member to cause the latter to be advanced for engine starting operations and to be returned during starter disengagement operations.

A lug 23 comprises a pair of unitary broad faced

stub arms

27, 28 substantially at right angles to one another. The lug pivots at its apex corner on a pin 29. Lug arm 28 has formed in its free end a segment of teeth 31 which are normally engaged with relatively broader straight splines or teeth 32 formed about the left end portion of the screw member. As shown in Fig. 2, the center of gravity CG of the lug is located in the body portion thereof at a point removed from the pivot point. The force of gravity acting on the lug weight tends to rotate it clockwise about its pivot (Fig. 2), thereby exerting a pressure trying to turn the screw member engaged therewith in the opposite direction. 1

In the operation of the device, upon rotation of the main shaft 1, the barrel and screw members are carried around with it, here counter-clockwise (arrow Fig. l). The heavy lugs 23, because of their inertia, do not accelerate as rapidly as the barrel member and, as a result, the lugs turn on their pivots in the direction of the arrow (Fig. 2). This eifects a dragging action upon the screw member, whereupon the latter is caused to travel axially outward. As the screw member so moves, the starter jaw is advanced by it into engagement with the opposed engine jaw. Whereupon, continued acceleration of the main drive shaft cranks the engine.

Now, as the associated engine starts, it soon attains a high rate of speed, sufficient to carry on without the aid of the starter mechanism, whereupon the motive power to the main drive shaft 1 of the starter is caused to be cut off in suitable manner. As the associated engine is advanced to this high rate of speed, which may be 18,000 R. P. M., the lugs 23 tend to swing centrifugally in a counter-clockwise direction (Fig. 2). As the faster rotating engine jaw releases itself from the starter jaw, the reaction efiected on the screw member by the centrifugally acting lugs causes the screw member to be returned to disengaged position in the barrel member.

It is to be noted that projecting from the inner face (Fig. 1) of each lug is a pin 33. The periphery of a ring spring 34 limits against the underside of each pin. This serves to effect a slight radially directed tension through the pins upon the lugs, whereby chattering of the lugs, which might otherwise occur in engine startingoperations, is avoided' While an embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention, as the same will now be understood by those skilled in the art; and it is our intent therefore to claim the invention not only as shown and described, but also in all such forms and modifications thereof as may be reasonably construed to be within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a high speed engine starter mechanism including a main drive shaft, a barrel surrounding the shaft, and slip clutch means engaging the barrel with the main drive shaft for rotation with the latter, an axially slidable starter jaw member, screw means helically engaged in an end of the barrel and arranged to advance axially out of the latter to slide the jaw member upon a drag being placed upon the screw means as the barrel member rotates, and weighted toothed means pivoted to the barrel member and cooperable with complementary toothed means about the screw to exert a drag upon the latter so as to advance the screw member axially upon rotation of the barrel member.

2. In a high speed engine starter mechanism includ ing a main drive shaft, a barrel member surrounding the shaft, slip clutch means engaging the barrel for rotation with the shaft, starter advancing screw means helically engaged to the barrel member and adapted to advance out of the latter upon a drag being exerted on the screw as the barrel member rotates, means for exerting such drag comprising a toothed lug member pivoted to the barrel member and engaged with complementary teeth about the screw member, the toothed lug having a center of gravity continually exerting while at rest a force upon the screw member in a direction opposed to the directional rotation of the barrel member.

3. In starter mechanism including a drive clutch barrel member, a screw member helically engaged in the latter, and means for advancing the screw out of the barrel member, said latter means comprising a plurality of equally spaced toothed segments pivoted about the barrel member and engaging complementary teeth about the screw member, and a weighted arm unitary with the body portion of each toothed segment normally tending to pivot the toothed segment in a direction opposed to the directional rotation of the barrel member.

4. In the combination of a driven barrel member, a

screw member helically engaged integral to the barrel member, and a flange formed'about an end of the barrel member, a plurality of lugs spaced equally from one another about the end face of the flange and pivoted to the latter, each lug comprising a pivot apex corner, a toothed segment arm and an arm at right angles to the latter, the center of gravity of the lug being in the body of the lug removed from the pivot point, and the toothed portion of the segment arm being engaged with a complementary toothed surface of the screw member, the force of gravity acting on the lug tending to urge the screw member in a particular angular direction relative to the barrel mem-.

her.

5. In engine starter mechanism of the character described including a driven barrel member having an end flange and a starter advancing screw helically engaged internally to the barrel member, heavy toothed lug means pivoted about the face of the end flange and engaged with pinion teeth about an end of the screw member,

the toothed lug means having a center of gravity 01f vertical position relative to the pivot point of the lug means when the toothed lug means and pinion teeth are engaged.

6. For use in association with a barrel member of the character described and for engagement with the pinion teeth of a starter advancing screw of the character described helically engaged in the barrel member; a heavy lug, having an apex pivot pin corner and a pair of stub arms at right angles to one another, one of the arms having a toothed segmentengageable with the pinion teeth of the starter advancing screw, and the center of gravity of the lug being in a web portion of the lug between the arms and removed from the pivot pin corner.

7. In the barrel member of a clutch pack of the character described including a screw member helically engaged at one end in an end of the barrel member and having pinion teeth in the, peripheral surface of its opposite end, an annular thickened. rib marginally about the end face of a flange of. the barrel member, a plurality of slots radially through the rib member, and a heavy lug member in each .slot pivoted on a pin crosswise of each slot, the lugmember having a pivot point eccentric to the axis of the lug and having atoothed segment in an end thereof engageable with the pinion teeth, the weight of the lug tending to urge the toothed segment angularly in a particular direction and thereby to ,urge the screw member angularly in the opposite direction.

No references cited.