US2219480A - Centrifugal control for ignition timer - Google Patents

Description

Oct. 29, 1940- H. L. HARTZELL El AL CENTRIFUGAL CONTROL FOR IGNITION TIMER Filed July 22, 1937 wgmggimmv NTOR Herman L. HarlzE/Z m. 3m w m AWN m In w E Patented Oct. 29, 1940 UNITED STATES PATENT OFFICE Herman L. Hartzell and Dalphin L. Hittle, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application July 22, 1937, Serial No. 155,030

16 Claims.

This invention relates to speed responsive mechanism for controlling the time of igniting a fuel charge in internal combustion engines.

It is an object of this invention to provide means for altering the time of cut-in of speed responsive control mechanism.

Another object of this invention is to provide means for adjusting the spring tension of centrifugal control mechanism.

Another object of this invention is to provide means in an ignition timer for adjusting the point of automatic cut-in of ignition advance by speed responsive means without disrupting operative assemblies.

Still another object of this invention is to provide centrifugal mechanism for the control of ignition timing, that is embodied within a housing, and made accessible for adjustment through the wall of the housing, without disturbing any of the parts of the operable assembly.

Further objects and advantages of the present invention will be apparent fromthe following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Fig. 1 is a vertical sectional view of an ignition timer-distributor incorporating the instant invention, it being a View substantially as indicated by the line and arrow I--l of Fig. 2.

Fig. 2 is a transverse sectional View through the ignition timer substantially as indicated by the line and arrows 2-2 of Fig. 1.

Fig. 3 is a fragmentary View, with parts shown in section, substantially as indicated by the lines and arrows 3-3 of Fig. 2 and Fig 4.

Fig. 4 is a sectional View substantially as indicated by the lines and arrows 4-4 of Figs. 2 and 3.

Fig. 5 is a sectional view similar to Fig. 4, it being a view substantially as indicated by the line and arrows 5-5 of Fig. 2.

Fig. 6 is a fragmentary sectional View substantially as indicated by the line and arrows 66 of Fig. 2.

Fig. '7 is a fragmentary View in plan, illustrating a modification of the tension adjusting means, it being a view substantially as indicated by the arrow 1 of Fig. 9.

Fig. 8 is a fragmentary sectional view of the same, substantially as indicated by the lines and arrows in Figs. '7 and 9.

9 is a fragmentary elevational view, substantially as indicated by the arrow 9 in Fig. 7, and the line and arrows 98 in Fig. 8.

In ignition timers for automotive engines, it is now common to provide centrifugal mechanism, that couples a driving shaft with a circuit 6 breaker actuating cam, in such a manner that the cam will be driven with the shaft, and that the angular relation between the shaft and cam will be altered in accordance with variations of shaft rotation. With an attempt to alter the 10 timing so as to obtain the greatest efi'iciency from the fuel consumed, it is the practice to advance the cam with respect to the driving shaft as the speed of the driving shaft increases. For the greatest eificiency it is essential that the centrif- 15 ugal mechanism begin to advance the cam upon the shaft at certain relative speeds of the shaft. However, due to slight discrepancies in the contributing parts as manufactured, several ignition timers when finally assembled, though their contributing parts he made by the same tools, and with the same degree of care, the completed assemblies will vary as to the point in the speed curve at which the centrifugal mechanisms vw'll cut-in and begin to advance the cam with respect to the driving shaft. Careful study of the situation, and calibration of the operative functions of the timer elements, disclose that this variation of cut-in for specific units, may cover a range of 4 to 6 degrees of advance at the same speeds of engine rotation This means that the automobile manufacturer, though he specifies that the ignition timer shall have a cutin, or in other words begin to advance the timing in response to speed, at some specific engine 5 speed, he may expect to find on test and calibration, if the vehicle is equipped With a timer of the prior art, that the cut-in actually takes place so much below or above the specified speed to effect as much as 2 or 3 degrees variation in timing on either side of the desired timing curve.

Applicants have discovered that the manufacturers specification can be critically complied with by constructing the ignition distributor, or the centrifugal mechanism therefor, in accordance with the disclosure herein presented. The manufacturers specifications are satisfied, and the objects herein stated are accomplished, by fashioning a centrifugal control mechanism for the circuit breaker actuating cam that embraces an adjustable spring support, whereby the point of cut-in of the centrifugal fly-weights can be adjusted. It has been discovered, that though the centrifugal mechanism may embrace a plurality of fly-weights, each of which is spring opposed to an in position, or to a position of rest, it is sufiicient to provide an adjustable spring support for one of the fiy-weight restricting springs. Sufficient adjustment of the spring tension, restraining the outward movement of the fly-weights, can be accomplished by the single adjustable spring support so as toeffect a satisfactory adjustment of the point of cut-in for the entire centrifugal assembly.

Means are provided through the timer housing wall for effecting adjustment of the movable spring support, such that it will not be necessary to even partially uncouple the centrifugal assembly or any other part ofthe operative assembly. Upon finding that the assembled adjustment is in error, the mechanism is allowed to come to rest, and the centrifugal assembly is rotated until the spring support adjusting means is aligned with the housing aperture, whereupon the adjustment is made Without disturbing any part of the operable assembly.

With particular reference to the drawing It indicates the housing of a timer distributor whose bottom wall i2 provides a central boss M, forming a bearing for a drive shaft H5. The shaft 56 carries a weight plate It that rotates therewith and supports pivot posts 20 and 22, upon each of which fly-weights 2 3 have a pivotal support. The fly-weights here comprise flat\ hook-like members, wherein the pivotal point is situated at the bight of themember, so as to leave relatively massive portion of the weight 26 disposed and relatively equally spaced on opposite sides of the rotation center, with shorter and less massive cam portions 28, extending from the opposite side of the pivot point. Cooperating with the cam portion 28, there is a cam bar 30 mountedupon one end of a sleeve 32 carrying a circuit breaker operating cam 34. The cam assembly is piloted upon the drive shaft M5, by reason of which the upper end of the shaft is reduced in diameter as indicated at 36. When so positioned, the cam bar 30, which supports a pair of spring posts 38, is disposed with its end members lying over the weight base l8 and between the arms 28 and 26 of the fly-weights.

Disposed over the fly-weights and cam bar there is provided a holddown means, that comprises a shallow cup member Ml, whose wall or skirt portion provides flats or stop portions 52 adapted to engage the end of the fly-weights when they fly outward to their limits, and thus define stops marking the limits of the timer advance by means of the centrifugal mechanism. The holddown means is securely mounted upon the base plate 58 by means of spacer studs 44, secured to the base plate in close proximity to the pivot posts 2!] and 22, the spacer studs being reduced in cross section at MS to be received by appropriate apertures in the bottom wall of the holddown cup 40. The cup 40 is also apertured as at to permit of assembling of the parts, and

permit the extension of the spring post 38.

After assembling the centrifugal mechanism with the holddown plate, spring supporting means are aflixed, which in this instance comprise clip members and 52, disposed over the reduced portion 46 of the spacers, where they are retained as by riveting at 5 3.

Situated above the centrifugal mechanism, a circuit breaker supporting plate 56 is fixed to the wall of the timer housing ill by lugs 58 and screws 6!]. Auxiliary plates 62 and 64 provide a pivotal support for a circuit breaker lever 66 having electrical communication with a terminal post 68 by means of a connector strap 18, the terminal 68 being insulatingly supported bybushings and washers through the housing wall 19, and for providing communication with electrical circuits by means of a lead 12. The circuit breaker 66 is adapted to be actuated by the cam 34, all as in the usual manner, and well known by those experienced in the art. The cam shaft 32 provides driving relation for a rotor M having constant communication with a central distributor terrninal 16 through a spring urged contact l8, and

adapted to come into close proximity to each one of a row of circular terminals 89, all as is the usual practice. I

The spring supports 56 and 52 are adapted to support one end of fly-weight springs 82, each of which has a second support upon a spring post 33 carried by the cam bar 39, so that a contacting relation is urged between the faces of the cam bar 39 and the cam portions 28 of the flyweights. Upon increasing speed of rotation of the shaft iii, a point will be reached where the mass of the fly-weights 26 will overcome the resistance offered by the springs 82, whereupon the cam 3 will be altered in its angular relation with respect to the base plate it. In order to provide for accomplishing a definite point of cut-in of this fly-weight mechanism, one of the spring supports is provided with means for movement, or for varyinng the stress placed upon its respective spring.

These provisions incorporate specific fashioning of the form of the spring clips, in that they are fashioned of sheet metal to provide lightness of construction, and are thence bentinto angular cross section to provide for rigidity of construction. As hereinbefore described, it is not necessary that both spring clips be of the adjustable type, though both of them may be adjustable if so desired. The illustrations in Figs. 3 and 4, show one form of the non-adjustable spring clips, wherein the member 50 comprises a flange 84 apertured to receive the end of the spacer stud M and also to receive the protruding end of the pivot post 20, after it extends through the holddown plate ill. Riveting of the end of the spacer stud M at 54 retains the clip in place. A second flange 86 is provided on the clip that stands upwardly to extend away from the holddown plate ill, and at a point substantially over the end of the protruding pivot post 20, it is prolonged and laterally notched to provide a spring receiving portion 88, substantially as illustrated in Figs. 2, 3 and 4.

The adjustable spring support is illustrated more in detail in Figs. 5 and 6, where the spring clip 52 is illustrated as having a body portion or flange that is apertured to receive the reduced portion of the spacer stud where it is loosely riveted at 56, and an upstanding flange 90 similarly ends in a spring receiving portion 92. The end of the spring receiving clip 52 opposite the spring receiving portion 92 is extended to provide a depending flange 94 that is adapted to be engaged by means for rocking the adjustable spring clip 3.11301]: its loose riveting connection on the spacer a 5 In Figs. 2 and 6, one form of means is illustrated for moving the adjustable spring clip, in order to variably stress the spring force applied to the fly-weights, and for holding the spring support in the altered position. The means therein illustrated, constitute a lug 96 bent up from the base plate |8,.and..is apertured to receive as'et "screw 98 to be locked in adjusted posi- 3'75 tion by a lock nut I00. It will be obvious from the showing here presented that running the screw 98 in or out will rock the spring clip about its pivot 54, and that in so doing, its respective spring 82 hooked on tothe members 38 and 92, the latter of which is a part of the movable spring clip, will be variably stressed which in turn either adds to, or detracts from, the total spring restraining force applied to the outward movement of the fly-weights. A convenient means is provided for adjusting the set screw 98 and the lock nut I98, by providing an aperture I02 in the side Wall of the timer housing III, substantally in horizontal alignment with the clip moving means, and the aperture I02 during normal operation of the timer mechanism is closed up by a cover plate I04 pivotally supported by the housing 59, by a rivet or pin I05. Further prcvisions making for the adjustment of the spring clip, embrace a recessed. or set-in portion of the holddown plate 49 to the extent indicated at I08, where clearance is provided between the depending skirt of the cup member and the supporting lug 96 to allow for the swing of the flange 94 for any adjustment that may be contemplated.

In Figs. '7, 8 and 9., a modification of the spring clip moving means is illustrated, and embrace the deformation of the holddown plate 453 depicting the form as illustrated at I I0, Where the depending flange IIZ rigidly supports a tubular sleeve I M, threaded to receive a socketed set screw I I6, providing a head IE8 whose periphery is notched at I2il to receive a cross rib I22 of a spring detent $24. This may, for convenience, be secured against the base plate I8 by means of the spacer stud 4d, and movement with respect to the base plate may be prevented by the crotched end I25 engaging the side walls of the pivot post 22. This will position the leaf spring I 24 substantially within the depending skirt of the holddown means 48, the latter of which is notched at I30 to allow for the extension of the spring portion of the member to engage the notched head of the set screw positioned outside of the holddown means. The exposed end of the set screw H5 is provided with a non-rounded socket or recess I32 for reception of a special tool, insertable through the aperture I02 of the housing ID, by which adjustment of the screw may be accomplished. When in the assembled relation, the flanged head I29 engages against the depending flange 95 which follows the movement of the screw inward or outward as respects the bushing I4, and thereby pivots about the loose conneotion 54 to variably stress the attached spring 82 as has been hereinabove described. In either instance manipulation of the set screw 98 or H6 will operate to vary the tension of the respective spring and thereby provide means for controlling the point of cut-in of the centrifugal mechanism to the extent desired.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In an ignition timer for controlling the advance of timing of an internal combustion engine, a centrifugal mechanism comprising in combination, a rotatable plate, a cam oscillatable relative to the plate, flyweights for oscillating the cam upon alteration of plate rotation, spring means supported by the plate and cam for opposing action of the flyweights, and means for altering the opposing force of said spring means, including a clip fixed to the plate supporting one end of a spring, and a set screw adapted to move the clip.

2. In an ignition timer, having a rotatable base with a. cam oscillatable on the base and spring restrained fiyweights for oscillating the cam, means for supporting the springs comprising in combination, a sheet metal clip adapted to receive one end of the spring, means pivotally supporting the clip from the base, and selective means for moving the clip on its support for altering the tension of the spring.

3. The combination set forth in claim 2, Wherein the clip is angular in cross section, and has one flange fashioned into a spring post disposed substantially over the pivot point of the flyweights.

4. The combination set forth in claim 2, wherein the pivotal support for the clip comprises a spacer carried by the base and extends above the flyweights, and wherein the clip is loosely riveted to the end of the spacer.

5. The combination set forth in claim 2, wherein the pivotal support of the clip is substantially midway of its length, and the base provides a lug, said selective means comprising an adjusting screw carried by the lug and engageable with a part of the clip, adjustment of the screw moving the clip on its pivot.

The combination set forth in claim 2, wherein the clip provides oppositely extending flanges, one of which extends away from the base t receive the spring, and another of which extends towards the base to be engaged by the clip moving means.

7. In an ignition timer, having a rotatable base with a cam oscillatable on the base, and spring restrained flyweights for oscillating the cam, means for supporting the springs comprising in combination, spacers carried by the base and extending above the flyweights, clips secured to the ends of the spacers and extending over the flyweights, one of said clips having a flange extending toward the base, a set screw engageable with the flange and adapted to oscillate the clip about the spacer, and means for retaining the set screw in the selected position.

8. The combination set forth in claim 7, in which the set screw is supported by a lug struck up from the base, and a lock nut holds it in place.

9. In a timer having a circuit breaker and an engine operated cam for actuating the circuit breaker, the'combination of means for altering the angular relation of the cam to the circuit breaker in response to engine speed, comprising, a drive shaft, a support provided by the shaft and rotating therewith, a pair of fiyweights, a pivot post carried by the support for each fiyweight, spacers on the support extending above the flyweights, holddown means for the fiyweights carried by the spacers, a cam bar oscillatable on the shaft and spring urged to engage the fiyweights, spring supports carried by the spacers, and springs anchored to the spring supports and the cam bar maintaining engagement of the flyweights and cam bar.

10. The combination set forth in claim 9, wherein the holddown means comprises a sheet metal cup inverted over the fiyweights, and whose side walls provide stops for the outward movement of the flyweights, and wherein one of the spring supports comprises a sheet metal clip riveted to the spacer, and provides a spring post 7 Til extending above the holddown'ine'ans, said spring support being shiftable to alter the spring force resisting the cut-in of one of the flyweights.

11. The combination set forth in claim 9, wherein the spring supports, comprise clips having spring attaching lugs disposed substantially over the pivot posts.

12. In spring balanced centrifugal mechanism, means for altering the spring tension comprising in combination, a base plate supporting flyweights, spring supports carried by the base plate, one of said spring supports being movable relative to the base plate, means fixed relative to the base plate for moving the'spring support, and means for securing the spring support in the moved position.

13. The combination set forth in claim 12, wherein the securing means comprises a spring detent secured to the base plate, and a set screw with a notched head cooperating with the detent.

14. In an ignition timer, the combination comprising, a relatively stationary housing, a base plate and attached shaft rotatable therein, pivot posts carried by the plate, flyweights oscillatable on the pivot posts and spring urged to an inposition, spring supporting clips supported by and rotatable with the base plate, and means carried by the base plate for adjusting one only of the spring clips, said housing being apertured to provide access to the spring adjustment when oriented therewith.

15. In an ignition timer, the combination comprising, a relatively stationary housing, a base plate including spring urged fiyweights rotatable within the housing, spring supports carried by and rotatable with the base plate, and means including an aperture through the housing wall for adjusting one of the spring supports to vary the point of cut-in of the fly weights.

16. In an ignition timer, having a rotatable base with a cam oscillatable on the base, and spring restrained fiyweights for oscillating the cam, means for supporting the springs comprising in combination, spacers carried by the base and extending above the flyweights, clips secured to the ends of the spacers and extending over the flyweights, one of said clips having a flange extending toward the base, a holddown plate disposed over the fiyweights and having a flange portion extending in spaced relation to the clip flange, a set screw carried by one of the flanges and engageable with the other flange for oscillating the clip and a spring detent for holding the set screw in adjusted position.

HERMAN L. HARTZELL. DALPHIN L. HI'I'ILEl.

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