US2720299A - Engine starter jaw meshing device - Google Patents

Description

Oct. 11, 1955 R. J. NIEMELA 2,720,299

ENGINE STARTER JAw MESHING DEVICE Filed oct. 14, 195o FEM/@ INVENTOR.

REINO J, NIEMELA ATTORN EY United States Patent Ofiice 2,729,299 Patented Oct. 11, 1955 ENGINE STARTER `TAW MESHING DEVICE Reino I. Niemela, Cleveland, Ohio, assigner to Jack & Heintz Precision Industries, Inc., Cleveland, Ohio, a corporation of Delaware Application October 14, 1950, Serial No. 190,179

1 Claim. (Cl. 192-104) This invention relates to engine starter assemblies and has for one of its primary objects to provide an improved means for effecting engagement and disengagement of the jaws of the engine starter and the engine crankshaft.

' It has heretofore been the conventional practice to so mount the starter that its jaw remains normally out of perature conditions causing congealed lubricants. It

often occurs that the starter jaw extension operation fails and even when the starter jaw is fully extended it meets head-on with the teeth of the engine crankshaft jaw so as to fail to mesh properly for effecting the proper engine cranking operation which causes increased impact torque. Moreover, in many instances, after cranking and engine firing has been eifected, the starter jaw retraction operation fails, both as `to retraction and also as to prevention of the undesired subsequent starter jaw extension into mesh with the engine crankshaft jaw which latter is rotating under high speed while the engine is running. This causes the jaws to ratchet which results in destruction of the jaw teeth and engine bearings.

It is therefore one of the primary objects of my invention to provide in an engine starter assembly means whereby the starter jaw is normally in engagement with the engine jaw so as to be in position to initiate the; cranking operation upon energization of the starter motor and to also provide an automatic means for disengaging the starter and engine jaws.

It is `therefore one of the primary objects of my invention to provide in an engine starter assembly means whereby the starter jaw is normally in engagement with the engine jaw so as to bein position to initiate the cranking operation upon energization of the starter motor and to also provide an automatic means for disengaging the starter and engine jaws.

Another object is to provide such an automatic jaw disengaging means that normally permits jaw engagement at rest and during the cranking operation, but which in response to a predetermined speed of rotation of the crankshaft of the engine after the latter has been started, acts to positively disengage the jaws.

Another object is to provide such a speed responsive jaw disengaging means in the form of a centrifugally responsive clutch that disengages the jaws and maintains them disengaged as long as the speed of rotation of the engine crankshaft is equal to or greater than a predetermined speed.

A further specific object is to provide such a jaw disengaging centrifugal clutch, as a separate self-contained package, that may be conveniently secured to and carried by the engine crankshaft, without redesign of the latter, and that will permit ready attachment of the starter with the two jaws initially in mesh with no need of any starter jaw extension or retraction means being incorporated in the engine starter.

With the foregoing and other objects in view, the invention resides in the combination of parts and in the details of construction hereinafter set forth in the following specification and appealed claim, certain embodiments thereof being illustrated in the accompanying drawings, in which:

Figure l is a View in longitudinal section taken through one end of the engine crankshaft, the centrifugal spring clutch, its jaw and that of the starter in mesh with each other;

Figure 2 is a similar View showing the clutch centrifugally operated, in response to engine speed, to disengage the two jaws;

Figure 3 is a fragmentary view in section taken through the engine flange and starter pad, showing the crankshaft and starter shaft and the meshing jaws in side elevation;

Figure 4 is an end view of the clutch, partly broken away to show the centrifugally responsive balls; and

Figure 5 is a view in perspective of the adjacent jaws, shown unmeshed.

Referring more particularly to the drawings, for purposes of illustration, I have omitted showing the engine starter, itself, but have shown the driven. starter cranking shaft 1 carrying a dog type jaw 2. The starter construction itself may be of the type disclosed in either of the United States patents to Ralph M. Heintz for Starter Jaw Meshing Mechanism No. 2,513,937, July 4, 1950, and No. 2,509,767, May 30, 1950, with the exception of the actual starter jaw and engine jaw meshing mechanisms to which my invention is directed in making an improvement thereon. At 3, I have shown one end of the hollow engine crankshaft. Without any redesign of the hollow crankshaft, I secure a plug 4, maintained against longitudinal movement by a snap ring 5.

As shown in Figure 3, the engine crankshaft 3 is rotatably supported for rotation in a bearing 6 in the engine flange 7. The starter shaft 1 is supported for rotation in a bearing 8 in a starter pad 9 that is releasably secured to the engine ange 7 by screw bolts 10 and nuts 11.

The automatic centrifugal jaw engaging and disengaging clutch comprises a main hollow sleeve 12 provided with external longitudinal splines in the hollow crankshaft 3, so as to permit longitudinal movement, but prevent relative rotation of, the clutch sleeve 12 in the hollow crankshaft 3. Integral with sleeve 12 is an enlarged head 13 to which is secured by a snap ring 14 a relatively stationary ring 15. The front, or right, face of this ring 1S is provided with a compound angular ramp 16. Slidably mounted on the head 13 is a concave ring 17. The front, or right, end of the clutch head 13 terminates in a jaw 18, to mesh with jaw 2 carried by a starter shaft 1. The front end of ring 17 is provided with a spider frame including four radial ribs 19 joined to a common apertured center ring 20. The front face segments 18 of the clutch head is provided with slots 21 to loosely receive the ribs 19 and also to receive the prongs 2 of the starter jaw.

The clutch assembly is secured in place in the plug 4 in the hollow crankshaft by means of a screw bolt 22, whose left end screws into the plug. The other end of the bolt 22 extends through ring 20 and is provided with a retaining head 23. Surrounding bolt 22 is a compression coil spring 24, whose expansive force may be adjusted by a nut 25 screw-threaded on bolt 22. Arranged so as to be retained, and in surface contact with, the ring 17 and the ramp 16 of ring 15, are a series of cir- 3 cularly arranged metal balls 26, under the resilient force of spring 2,4.

With the clutch assembly thus assembled and slidably secured in the crankshaft plug, and the crankshaft being rotatably supported by bearing 6 in the engine ange 7, the starter pad 9, carrying the starter shaft 1, is secured to the engine flange, as shown in Figure 3. As shown both in Figures l and 3, when this connection is made, the two jaws 2 and 18 are initially in mesh. Thus, when the conventional vstarter motor is energized, its shaft 1 is rotatably driven, and, inasmuch as its jaw 2 is in mesh with jaw 18, the clutch assembly and the engine crankshaft are rotatably driven. There is no problem of extending the starter jaw into mesh with the engine jaw, as is the case in conventional jaw meshing apparatus, because the starter is clamped` on in such a manner that the jaws are initially in mesh. Thus in the engine cranking cycle, and up until the time the engine tires, as long as the motor remains energized, the cranking operation continues.

I have found that it is imperative that some means be provided for discontinuing cranking after the engine fires and attains a speed greater than that of the starter drive shaft. This I propose to accomplish by means that is automatically responsive to the speed of rotation of the engine after the latter has red and is self-driven. Accordingly, in order to accomplish this, I further propose to provide means whereby the jaws become automatically disengaged upon a predetermined engine speed, greater than that of the starter drive shaft, and automatically engaged below such predetermined engine speed. This is attained by the provision of the clutch assembly above described. In detail, the particular engine crankshaft speed responsive centrifugal clutch assembly unit is so designed that, after engine firing, and high engine speed is attained, the centrifugal balls 26 exert radially outward force. They ride outwardly on the inner face of ring 17 and also angularly outwardly on the compound ramp 16 of ring 15, as shown in Figure 2. The resultant eiect of this centrifugal action is to spread the two rings 1S and 17 apart, forcing ring 15 and the clutch sleeve 12, 13 to the left, against the action of spring 24. This releases jaw 1'8 from mesh with starter jaw 2. Thus the engine crankshaft is relieved from the drag of the starter shaft. Moreover, this is true even if the operator inadvertently continued to keep the starter operating.

It follows that when the engine stops, or when 1it reaches a predetermined low speed of crankshaft rotation, the centrifugal action on the balls lessens, permitting them to radially recede, assisted by the action of spring 24, to again bring the jaws 2 and 18 into mesh again, as shown in Figures 1 and 3.

It is to be understood that, While I have shown dog type jaws, yI may prefer to employ ratchet type jaws. In my preferred embodiment illustrated it will be seen that the starter, itself, need not contain any means for extending or retracting its jaw. The starter jaw is merely carried by the motor driven shaft for pure rotational drive and does not move linearly in either direction. This eliminates heavy, expensive and complicated jaw meshing mechanism and its attending mechanical features. The starter is merely clamped into position with its jaw initially in mesh to drive the engine crankshaft directly and immediately upon organization of the starter motor.

My preferred embodiment disclosed comprehends the use of an automatic clutch assembly, in the form of a simple, light, inexpensive and eicient unit, as a separate package. Its use calls for no redesign of the starter or engine. It may be merely removably secured to the hollow engine crankshaft. The clutch unit, whether made and sold as a separate package or initially secured to the starter or engine crankshaft, still calls for no redesign of either.

I claim:

In combination in an engine starting apparatus, a rotary and linearly stationary starter cranking shaft and a toothed jaw rigidly carried thereby, a rotary engine crankshaft and a complementary toothed jaw detachably longitudinally slidably splined therein, spring means for initially and normally slidably extending the teeth of said engine jaw axially directly into mesh with the teeth of said starter jaw to normally engage said jaws, and actuating means mounted independently of the teeth of said jaws and centrifugally responsive to a speed of rotation of said engine crankshaft in excess of that of said starter cranking shaft for retracting said engine crankshaft jaw out of mesh with said starter cranking jaw, lsaid actuating means being carried solely by said engine crankshaft jaw and comprising a pair of rings with opposed generally concave faces, one of which is ramped, and a series of balls therebetween, one of said rings being rigid with said engine jaw and the other ring being under resilient tension of said spring means against said balls, said balls being normally urged radially inwardly in said clutch means as said spring means normally forces said engine crankshaft jaw slidably into mesh with said starter cranking jaw, said balls, in response to a predetermined speed of rotation of said engine crankshaft, after engine firing, being adapted to be centrifugally thrown radially outwardly up the ramp of one of said ring faces to spread the clutch rings apart and slidably retract said engine crankshaft jaw axially away from and out of mesh with said starter cranking jaw.

References Cited in the le of this patent UNITED STATES PATENTS 1,105,408 Dechamps July 28, 1914 1,145,656 Apple July 6, 1915 1,219,698 Brackett Mar. 20, 1917 1,490,505 Breese Apr. 15, 1924 1,739,150 Honigmann Dec. 10, 1929 1,753,825 Ford Apr. 8, 1930 2,464,675 Dodge Mar. 15, 1949 2,587,712 Dodge Mar. 4, 1952

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