US2691703A - Ignition timer and method of contact point adjustment - Google Patents

Description

oct. 12, 1954 IGNITION TIMER AND METHD 0F CONTACT POINT ADJUSTMENT Filed March 15, 1951 MAM, u.,

i ttornegs Patented Oct. 12, 1954 OFFICE IGNITION' TIMER AND. METHOD OF CONTACT POINT ADJUSTMENT LuciusD. Watkins, Milwaukee, Wis., assignor'to- Outboard. Marine.` & Manufacturing Company, Waukegan, Ill., a corporation r of. Delaware Application March 15, 1951', SerialfNo. 2155817 17 Claims. 1.;

This. invention relates to, anfignition. timeri and method ofcontact pointiadjustment.

It is the object of the invention to.. facilitate breaker. point and. timing adjustment by releasi-` ably mounting the. entire breaker assembly for bodily adjustment. Des-irably the. assembly is subject to the action of.: a. spring which is not sufficiently strong to open. thecontacts. against the bias of the breaker spring,. and which urges the entire assembly towardthe: breaker camv so that, given a proper rotative datum position. of. the cam, thel assembly will;automaticallyyengage the cam follower withV the cam. in a position which necessarily represents, afl properly timed setting, and in which saidy assembly can thereupon be xed. f

The invention. further contemplates a. means. for indicating, or establishingtheA proper datum position for the camA byv means. oiv adetent'- nor.- mally out of engagement with a cam-connected rotor, but movable toA a. position. for such engagement in the same operation which releases. the breaker assembly for-free movement in response to the aforesaid spring.

From a method standpoint, the invention. is characterized by the :factV that adjustment is made by the bodily movement of the breaker mechanism with the: points closed, such. adjustment being made in a direction having a sub*- stantial component radially of the cam, tolbring. the cam follower into; engagementwith; apredetermined portion; of` the, cam intermediate its positions of minimum and. maximum cam dis;- placement, and thereuponclamping the. breaker mechanism against furtherA movement having a component radially of the cam, so thatdisplacement ofthe cam follower from;the-selectedpoint on the cam to the peak thereof. willl necessarily represent a given opening ofi thepoints..

For convenience. of. illustration, the. invention is shown in conjunction With-the fly Wheelmagneto and timer plate of. a two-cycle engine, but the invention is by no means limited'to this application.

In the drawings:

Fig. 1. is a plan view off an engine fly wheell with portions brokenaway ton expose thebreaker assembly and. cam..

Fig. 2 is a view in side-elevation of. the: engine crank shaft bearings and. y Wheel,4 portions beingv broken away to; the l planey indicated' at 2 2 in Fig. 1.

Fig. 3 is ay fragmentary detailv View` onv thesection similar to that of Fig.. 2q showing. thebreaker assembly carriage. released.l for. Seli-ad- 2 justment,` andthe; detentV raised to interact with the'iiy Wheel.

Fig.. 4. isA anv inverted plan view fragmentarily illustrating the springdetent in engagement with the: flyv wheel.

Fig; 5 is a view fragmentarily illustrating a modified embodiment ofy the invention on a section similarto:that` of Fig. 2.

A portion of. an engine crank case is illustrated atv t" in Fig'. 2.y From it projects a bearing sleeve 'i within which a bushing 8 rotatably supports crank. shaft. 9 In this type oi engine, the crank shaft. also serves-v as a cam shaftv (having the cam llllmounted thereon); Rotation is clockwise as viewed in Fig, 1.

Rotatable upon the outside of thev bearingsieeve 'l is theusual timer. platev H, the collar or hub |21 of.- Whch is rotatably itted tobearing sleeve l. For timing purposes, the plate ll is usually adjustable angularly, a fragment of the handle I3A beingv shown to. exemplify this feature. For the-purposesof` the present inventiomthe plate l la may be regarded asxed.

At its'upper, end', the shaft 9 carries the rotor |4- which, in this device, comprises a fly wheel magneto. Forstartingfpurposes, a starting pulley IE-is carried on the top of the fly wheel. Interiorly of therim: I6 of the rotor or ily wheel Misa magnetV l1 which,r however,.forms no part of the present invention. At. one point, the rim I6 of the ily wheel I4 has a shoulder which is here. provided by a marginal notch I8, for purposes.- hereinafter to be. described.

The; entire. breaker mechanism is mounted on a carriage lvwhchis capable of free movement onthe timer plate Ily to and from the axis of cam shaftS. Forthe purposes of the present disclosure, the carriage 20 comprisesV a` plate pivoted ona study 2l which projects upwardly from timer plate Il and about which the plate 20. oscillates freely exceptA when clamped to the plate. In. order that it may be clamped to the plateduringy normalfoperation, thereis a clamping bolt, '11.2.- screw-threaded through the timer plate Il, as shownin-Hig. 2, and passing through a slot 2.3. inthe-carriage- Zgnsuch slot being generallyv arcuate.- about the'center of,y oscillation on stud. 2l.. Thel nut 24- adjustably fixed to bolt 2i? engagesuthe clamping-,washer 25.l when the screw is turneddownwardlysin `timer plate il toclarnp thecarriage 20:' to the-.timer plate. By screw.- ingy the bolt. 22 upwardly, as viewed in Fig. 2, the fclampingipressure may., be, released sufficiently. to.y permit thezcarriage. to oscillate freelyv upon itspivot, stud. 21|; subject to the bias of the E torsion spring 26 which is coiled about the stud and has its end 21 engaged with anchorage 28 and its free end 29 engaged with a margin of carriage '20.

The iixed contact point 30 is mounted rigidly on the carriage and provided with wire terminal 35, the point and terminal being insulated at 32 from the carriage. The movable contact point 33 is carried by spring 34 from a spring anchorage 35 fixed to the carriage. The points may be sepa-rated by the cam l when the nose of the cam registers with a cam follower 36 engaged with spring 34, whereby the spring 34 is flexed to disengage contact point 33 from engagement with contact point 39. In the present device, the cam follower 35 comprises a push rod reciprocable in the bearings 3?, 38 provided by theY carriage. It is, however, broadly immaterial how motion is transmitted through the cam follower to the movable contact point, since it will be obvious that a variety of mechanical arrangements can be used to obtain the advantages of the present invention, so long as the breaker mechanism is mounted on a carriage for bodily movement to and from the cam. The relative strength of the springs 23 and 34 should be such, however, in relation to the structure used, that the spring will not exert suiiicient thrust or torque upon the carriage 25 so that the reaction of the pressure of cam follower 3G upon cam I0 will open the points. Bearing in mind that the relative strength of these two springs may be varied according to the mechanisms used to transmit cam motion to the moving point, this relationship may be described generically by saying that the effective strength of spring 3d to resist the opening of the contacts is greater than the effective strength of spring 25 exerted in a direction to effect such opening.

In the ordinary breaker mechanism, fixedly mounted on a timer plate or equivalent, the proper setting of the points involves first, the adjustment of the cam nose into registry with the Cain follower, so that the latter is moved to the position which it occupies when the points are most widely separated. One of the points, usually the relatively fixed point, is mounted on a screw which is then adjusted to a specied spacing from the open movable point, such spacing being determined by a thickness gage, and requiring a substantial amount of technical skill for its proper achievement. Moreover, the adjustment of points must either be made through a hole in the fly wheel, or the fly wheel has to be rei loved to give access to the pa-rts requiring adjustment. This operation is performed at the time the parts are initially assembled and the same operation must be repeated each time the points are trued, or each time sufficient wear occurs to affect proper timing.

The present invention eliminates completely all need for technical skill, and for the use of any gage. The cam is rst positioned to a predetermined ignition position or breaker point opening position. Even lthis establishment of the relative positions of the parts is desirably accomplished automatically through the use of a detent ill confined between a-nges 4i, 42 on the under surface of the timer plate H and having its free end pivotally movable into engagement with the shoulder provided by the notch i8 on the lower margin of the rim i6 of the fly wheel I4. The detent is normally held disengaged from the y wheel by the compression spring 43, as shown in Fig. 2. This spring urges the detent downwardly against the washer 44 on the screw 22. When the screw 22 is turned upwardly in a direction to uncla-mp the carriage 20 for oscillatory movement under the torque of spring 26, the same upward releasing movement of the screw which unclamps the carriage carries the detent 40 up into a position where, as the fly wheel is rotated, the detent will engage in notch I8. Accordingly, when the operator releases the carriage, all he has to do is to rotate the iiy wheel until the detent engages in the notch, whereupon the cam nose I0 will automatically be in the precise position required for proper timing.

Meantime, the carriage 20 will have been oscillated by spring 26 to a position such that cam follower 36 engages the side of the cam. With the cam in the position determined by the detent 43, the relationship between the cam follower and the cam will automatically be such as to achieve exactly the displacement of the contact point 33 which is required for properly timed breaker operation. This is true for the reason that the effective strength of spring 34 is greater than the effective strength of spring 26. Thus, no matter how long or how short may be the contact points 30 and 33, the spring 34 will hold them together at the time the cam follower 36 is engaged with the side of the cam so that the separation ultimately effected by the cam will be exactly that degree of separation required for proper operation.

Consequently, all that the operator now has to do is to re-clamp the carriage 20 to the timer plate in the position to which the carriage has adjusted itself. Screwing the screw 22 downwardly in the timer plate simultaneously clamps the carriage in adjusted position and retracts the detent 4U out of the path of the fly wheel, leaving the parts free for operation conventionally.

To achieve this result, the operator has been required only to loosen the screw 22, rotate the fly wheel until the detent 4G engages and thereupon tighten the screw 22.

In the construction shown in Fig, 5, a prying action has been substituted for a. screwing action as a means of releasing the carriage and operating the detent. The timer plate is here designated as H0. It has a depending lug at 43 with a notch 41 in which the free of the detent 400 is pivoted. The bolt 220 is freely reciprocable through the slot 23 of carriage 26 and through a hole 48 in the timer disk I I0. Its head 49 clampingly engages the carriage while a nut 50 on its lower end supports the detent 400 against the compression of the spring 43. By simply inserting a screwdriver or other lever 5I beneath bolt 220, and fulcruming the point of the screwdriver upon the shoulder 52 of boss 46, it is possible to lift the bolt to engage the detent 400 in the notch I8 of the fly wheel rim, while simultaneously freeing the carriage 2U for self-adjustment as above described. In this device, as in that shown in Figs. l to 4, the operator has only to unclamp the carriage, rotate the ny wheel to the appropriate cam position, and re-clamp the carriage. In both devices shown, an additional feature consists in the automatic determination of the correct cam position by means of a detent which becomes effective to engage a shoulder on the fly wheel rim coincidentally with the unclamping of the carriage and is retracted to an inoperative position when the carriage is again clamped to the timer plate. v

Assuming that the timer plate is relatively osacer-,vea

cillatable, as in the exempliiication shown,. its oscillation will serve to advance or retard the spark in the usuall manner without in any way affecting the setting of the points aszautomatically self-determined by the movement of the carriage to engage the cam follower with aselected portion of the cam at af time when the points are closed.

I claim:

1. In an ignitionV timer comprising a cam and. a breaker mechanism including ay cam follower and relatively fixed and: movablevv contact points, the latter being connectedtobe actuatedy by the cam follower away from'A the fixed point, the improvement which comprises a carriage upon which said breaker mechanism ismounted: for bodilyA movement in a directionrv whichlincludes-f a substantial component of cam follower movement radially of the cam, means'guiding the carriage for such movement, a spring biasing the carriage for movement of the cam follower toward the cam, and a spring biasing the movablecontact point toward the xed contact point, and the effect of which to prevent separation of said points is greater thanv theeffect ofA said first mentioned spring in a point separating direction, whereby the movement of the-carriage effected by the iirst mentioned spring will advance the cam follower into contact with the cam, without separating said points, and means for releasably clamping the carriage in the: position in which it is thus advanced, as determined by engagement of the cam follower with,v the cam.

2. In an ignition timer which includes a cam, a timer plate oscillatable coaxially with the cam. and breaker mechanism having a cam follower, a movable contact point connected to be actuated by the cam follower, a fixed point from which said movable point is separated when actuated by the cam follower, and a contact spring biasing the movable contact point toward the fixed contact point aforesaid; the improvement which comprises a carriage upon which said spring and points and cam follower are unitarily mounted, means guiding said carriage for movement in a direction having a substantial component in which said cam follower is advanced toward said cam, a spring biasing said carriage for the advance of the cam follower toward the cam and less effective through said cam follower to separate said points than is the first mentioned spring to bias the movable point into engagement with the fixed point, and means for securing the carriage to the timer plate in the position to which it is adjusted by the last mentioned spring, the carriage and cam follower and the said points and the spring first mentioned being unitarily oscillatable with the timer plate coaxially with the cam when the carriage is thus secured to said plate.

3. The device of claim 2 in further combination with means for establishing a predetermined angular adjustment of the cam respecting said plate,

4. The device of claim 3 in which said establishing means comprises physically engageable parts respectively connected with the cam and said plate for determining positively the desired angular position of the cam relative to the plate.

5. The device of claim 4 in which one of said parts comprises a ily wheel provided with a shoulder and the other of said parts comprises a detent movably mounted on the plate to be advanced and retracted from the path of said iiy wheel shoulder and connected with said carriage securing meansto` be advanced inthe release of' said carriage securing. means and retracted in` the movement of said meanswhi'ch secures the carriage to theplate.

6. In anl ignition timer comprising acam, a cam follower and relatively fixed" and movable contact points, the latter being provided with a spring biasing ittoward' the former and being operated by said follower in a direction to displace it from contact with the fixed point against the bias of said spring, the improvement which com-v prises the combination of'a carriage upon which the nxed point is mounted and havingmeans sup-n porting the follower and spring and movable point, a support for the carriage, a pintle connected with the` support and upon which the carriage is pivot'ed for oscillatory movement, the said cam follower beingv supported on thel carriage for engagementwith saidy camy onr a radius of the cam which is remote from a radius of said cam drawn to said pintle, whereby the said cam follower will move to and from the caml in the course of carriage oscillation upon said pintle, a spring connected between the support and the carriage to bias the carriage in a direction of oscillation which advancesthe cam follower toward the cam, the effect of said spring upon the movable contact point where the cam follower engages the cam being less effective to open said' point than is the first mentioned spring to bias the movable contact point into engagement with the fixed contact point, and meansforclamping the carriage to said supportv in the 'positionl to which the carriage is adjusted by the spring first mentioned and determined by the closed position of the movable contact point.

7. The device of claim 6 in which said clamping means includeV a boltr extending through the support and carriage and axially movable to and from carriage clamping position.

8. The device of claim '7 in further combination with cam setting means which comprises a rotatable part connected with the cam and provided with a shoulder and a detent mounted on said support and having means interlocking it therewith against angular displacement with said part, said detent being movable to and from the path of rotation of said shoulder and being connected with said bolt for advance to said path when said bolt moves axially for the release of the carriage and for movement from said path when said bolt moves axially for the clamping of said carriage.

9. The device of claim 8 in which said detent is provided with a third spring seated against said support and biasing it toward its retracted position.

10. The device of claim 9 in which said bolt is screwthreaded to said support and operated ax ially by rotating it upon its threads.

11. The device of claim 9 in which said bolt is freely reciprocable to said support and carriage and biased to clamping position by the spring of said detent.

12. The device of claim 9 in which said support comprises a timer plate oscillatable substantially co-axially with said cam.

13. The device of claim 12 in which the shouldered part connected with said cam comprises a iiy wheel.

14. A timer comprising in combination a shaft provided with a cam, a timer plate angularly adjustable substantially coaxially with the shaft, a fly wheel connected with the shaft and having a depending margin encircling said plate and provided with a shoulder determinative of a selected cam position when engaged by an appropriate detent, a detent mounted on the timer plate for movement to and from the path of said shoulder, a clamping bolt axially movable through the timer plate and connected with said detent to control the position thereof, a carriage mounted on the timer plate and having a slot through which said bolt passes, the said bolt being adapted in one position of axial adjustment to clamp the carriage to the plate, breaker mechanism mounted in its entirety upon the carriage and comprising relatively xed and movable points, a spring supporting the movable contact point and biasing it toward the xed contact point, and a cam follower cooperating with the cam and arranged to transmit motion from the cam to the movable contact point to effect separation thereof from the xed contact point against the bias of said spring, the said carriage being provided with means mounting the ixed contact point, the spring, and the cam follower, and a pintle connected with the timer plate and upon which the carriage is mounted for oscillation, the said pintle being disposed on a projected radius of said cam remote from the radius of said cam upon which said cam follower engages said cam, whereby the oscillatory movement of the carriage upon the pintle will advance and retract the cam follower from the cam, and a spring lightly biasing the carriage in a direction to advance the cam follower to the cam, the carriage being free for movement in said direction when released from clamping engagement by said bolt, and the spring last mentioned being less eiective through said cam follower upon the movable contact point in a direction to open said point than is the spring first mentioned in its bias of said movable con- 8 tact point toward closed position respecting the fixed contact point.

15. In an ignition timer mounted for coaction with a cam having a path of movement, the combination with a carriage having releasable means for fixing its position respecting the path of the cam and having a xed and movable contact, a contact spring biasing said movable contact toward said fixed contact and a cam follower actuated by said cam to oppose said Contact spring, of a mounting on which the carriage is pivotal toward and away from the path of said cam, a carriage spring biasing said carriage toward said cam against the bias of said contact spring, said springs being of different strength with the contact spring sufficiently stronger than the carriage spring to insure closure of said contacts when both are permitted to freely react against said cam follower.

16. The device of claim 15 in further combinaation with means for establishing a predetermined angular adjustment of the cam respecting the carriage, said means comprising parts connected to said cam and carriage which releasably interlock in said predetermined angular adjusted position.

17. The device of claim 16 wherein said releasable means for iixing the position of the carriage respecting the path of the cam further comprises means to releasably interlock said parts on release of said carriage.y

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,577,437 Andrew Mar. 23, 1926 2,129,953 Mack Sept. 13, 1938

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