US2688054A

US2688054A - Ignition control device

Info

Publication number: US2688054A
Application number: US54973A
Authority: US
Inventors: Martin J Berlyn; Ernest E Stansfield
Original assignee: American Bosch Arma Corp
Current assignee: Ambac International Corp
Priority date: 1948-10-16
Filing date: 1948-10-16
Publication date: 1954-08-31
Anticipated expiration: 1971-08-31

Description

Aug. 31, 1954 M. J. BERLYN ETAL IGNITION CONTROL DEVICE 2 Sheets-Sheet 1 Filed Oct. 16, 1948 v m w M s o VLN w mm. A 36 J5 mm N A V. MR

Aug. 31, 1954 M. J. BERLYN EFAL IGNITION CONTROL DEVICE 2 Sheets-Sheet 2 Filed Oct. 16, 1948 INVENTORS. BEELYN T E A M E'ENEST STANSF'IELD,

.A'TTOPNEX Patented Aug. 31, 1954 IGNITION CONTROL DEVICE Martin J. Berlyn, Enfield, Conn., and Ernest E. Stansfield, Springfield, Mass., assignors to American Bosch Corporation,

Springfield,

Mass, a corporation of New York Application October 16, 1948, Serial No. 54,973

10 Claims. 1 This invention relates to ignition timers for internal combustion engines and has particular reference to timers of the type which embody a movable circuit breaker plate or supporting means.

An object of the invention is to provide a new and improved supporting means for the circuit breaker assembly which may be moved in angular relation to the cam to provide variation of spark timing in relation to engine crank position. Another object of the invention is to provide a pivot arrangement for the circuit breaker supporting means or plate which will reduce to a minimum the amount of wobble of the supporting plate resulting from normal wear in said pivot which wobble may cause erratic spark timing and variations in spark timing resulting in rough running of the motor and in extreme cases detonation.

Another object is to provide a pivot arrangement of the type set forth above which shall have a high length-diameter ratio and wherein the use of ball bearings is obviated.

Another object of the invention is to provide an arrangement of the type set forth wherein the pivot for the circuit breaker supporting means is displaced from the cam shaft axis by such an amount that the diameter of its pivot is entirely independent from the diameter of the camshaft and the bearing for the camshaft.

Another object of the invention is to provide a relatively economical yet efiicient circuit breaker supporting means.

Other objects and advantages of the invention will be apparent from the following specification taken in connection with the accompanying drawings. The preferred embodiment has been shown by way of illustration only and it will be understood that changes may be made in the details of construction and arrangement of parts without departing from the scope of the invention.

In prior ignition timers of the type which embodied a movable circuit breaker plate or supporting means, ithas been customary to employ a bearing which surrounds the camshaft. In such constructions it has been usual to employ ball bearings in an attempt to obviate any wobble or looseness in the bearing which might cause erratic spark timing and variations in spark timing resulting in rough running of the motor and in extreme cases detonation.

As ball bearings are expensive, they have added considerably to the cost of such ignition timing devices and yet where attempts to avoid the use of such ball bearings have been made, the resulting constructions have not been found satisfactory in operation because of the inherent looseness or wobble between the parts resulting from normal wear thereof and which resulted in the various difiiculties mentioned above. Where a ball bearing was not employed, the length of the pivot about which the circuit breaker supporting plate was pivoted was limited by restrictions on the overall height of the assembly, and with the pivot surrounding the camshaft as was previously employed, a very unfavorable length-diameter ratio for said pivot was obtained.

We have found that by displacing the pivot for the breaker supporting plate away from the camshaft axis by an amount making the diameter of the pivot entirely independent from the diameter of the camshaft and its bearing, that it is possible to obtain a satisfactory length-diameter ratio of such pivot and to thereby overcome the inherent difficulty of taking the wobble out of the pivot bearing Without the necessity of employing expensive ball bearings. We have found that this can be successfully achieved by positioning the pivot for the breaker supporting plate at such distance from the axis of the camshaft that L the distance between the center of the pivot and the center of the camshaft is greater than half the sum of the diameters of the camshaft and pivot bearing but not so great as to affect unduly the amount of contact separation when the internupter supporting plate is moved through the normal timing range, yet with the camshaft and pivot bearings completely separate.

This construction is aimed primarily at ignition for engines operating on a four stroke cycle and it is, therefore, only necessary to vary the spark timing by an angle measured at the interrupter camshaft center equal to one-half crankshaft spark timing range as measured on the engine crankshaft. Since the timing range normally desired does not exceed thirty crankshaft degrees, then this range does not call for an adjustment of over fifteen degrees in either direction relative to the interrupter camshaft and within this small angle the offset of the pivot for the breaker plate from the center of the breaker camshaft causes no significant change in the breaker point opening. Also, where the follower block is positioned on the midposition of advance and retard, that is, on the line passing through the centers of the breaker support plate pivot center and the camshaft center, that the minimum variations will be obtained.

We have also found that it is possible with such construction to provide a breaker supporting plate made of a minimum amount of material 3 which allows a maximum amount of movement of the plate and yet may be constructed at a relatively low cost because of the amount of material needed and because of the small bearing required to obtain a satisfactory length-diameter ratio and also that, if desired, a lip on the breaker plate may be providedrtoengage an undercut internal circumferential guide in" the periphery of the.

housing for further steadying the plate and relieving the pivot for the plate of some of the bearing load.

Referring to the drawings:

Fig. 1 is a plan view of the" ignition distributor with the distributor cap removedandillustrating the invention as applied tota-di'stributorof the engine suction control type;

Fig. 2 is a sectional view takenon line 2-2 of- Fig. 1 looking in the direction of the arrows;

Fig. 3 is a sectional view taken on line 3---3-- of Fig. 1 looking in the direction of the arrows;

Fig; 4-iis asection'al :view taken online 4 -4 of Fig. 1 looking-in the direction of'the arrows; and Fig. 5 isa-plan view of thebreaker supporting plate.

Referring" more particularly to the drawings whereinsimilar reference characters; designatecorresponding parts throughout the several views,

the construction shown embodying the invention comprises the usual timer or'distributor housing. I in which is positioned the supportingplate 2..

which is provided with the integral peripheral spaced flanges S and the screws' l which extend through aligned openings in the wall of the housing l and flanges-'3 and secure the plate 2 in posi-- of substantially U-shapefor the reasonthatsuch:

shape-will require a amount of material with theresultant reduction in cost ofmanufacture and atthesametime allow a maximum. amount of movement for advancin and--retard+ ing the spark.

The breaker support arm 5-is provided-with the bushing 8 which may comprise abushing hav ing an enlarged 'headii and-'a reduced portion ex tending through arr-opening inthe breaker support 5 with said bushing beingsecured in position in said openingby-brazing or other suitable means. The bushing-eds adapted to receive the stud Ea which may be secured to the supporting plate 2 by having a portion thereof extending through anopeningin the saidsupportin plate 2 and said portion lii'being: riveted. over tosecure said stud'to said plate whereby said stud--91], will form a pivot post for the circuit breaker'support- 5 about which said support may beadjusted: foradvancing or. retarding the spark as-hereinafter described.

On the breaker support arm Eismounted the circuit breaker 'l which is mounted for pivotal movement about the pivot. II and whichhas the contact 12 adaptedtoengage the contact l3 on..

the contact supporting bracket I4 which .is. .se-.-

cured to the breaker support 5 by the screw I5.

and adapted to be adjusted by means; of. the eccentric stud. Iii for adjusting. the relativeposition of the contacts 12 and l3; 17 may also be mounted on'the breaker support The spring. bracket.

4 5 for the securing thereto of one end of the circuit breaker spring I8.

While one form of circuit breaker has been shown by way of illustration, it is pointed out that other types of circuit breakers might be employed such as the so called pivotless" type, or the contact I'3and circuit breaker 1'-might be mounted oni=a.eseparate bracketiwherein. the contacts l3 and I2 are positioned in permanent alignment and adapted for adjustment as a unit and said bracket ma then be secured on said support5:

The circuit breaker! is provided with the usual camffollower'or striking block I9 adapted to engage the camnfi inithe usual manner.

On thebreakersupport 5 and adjacent the free end thereof is secured the stud 2B to which is secured one end of the'coil spring 2! and said spring 21x hasits. opposite end secured to the stud 22 which is secured to thesupporting plate 2 and extends through. an enlarged opening- 23-..adjacent the free end of-the breaker support ii.- The-open.

ing 23 should be-of such size as to allow'mo-vement of the breaker. supports-for advancingaor-v retarding the spark as hereinafterdescribed.v

A-suction device isutilizedfor advancingand retarding the spark. The. suction device. com

prises a. flexible diaphragm 24 backed up by a:- compression coil spring 25-which are mounted in" the housing 26- which" is connected'to. the car fixed. tothe diaphragm, 2 3.

usual manner.

The breaker supportShas the lip 3ilwh'ich e111" gages an undercut, internal.circumferentiaLguide in theperiphery of .the housin .v I. For conven-. ience inmanufacturethis. guide 3'l.has been. shown as formed in the peripheral flang 3-2ionthesupport 2 although it could be iormeddirectly in the wallof. the housing. tiffdsired. Thisarrangement provides -a constructionwherein the. breaker, support .5 i is further steadied and. the pivot S-relieved of some of thebearing load.

The length of the pivot. for thebreaker support. 5 and form ofthe stud. Bc'tandbirshingfiis limited. by restrictions on the overall height ofithe.as sembly and'as it is desirable. for the .pivot't'o have a' high length-diameter ratio so asto reduc to a minimum theamount of wobble otthe supportingplate resulting from. normal wear in. that pivot; itis necessary, toemploy a pivot of smalldiameter. If this'pivot were concentric with the. camshaft; the pivot'diameterv wouldiinecessaril'yl be greaterthan the camshaft "diameter thus g'iv-t ing a very unfavorable length-diameter ratiofor this pivot; We"have;'..therefore; found ith'at' a favorable length diamet'er ratio can be obtainedby displacin the pivot for the. breaker supp'orting, plate 5' away from the camshaft axis by an". amountmak'ingthe diameter of this pivot entire- 1y independent from the diameter ofthe camshaft and its bearing'.

The distance between the" center. ofv the" pivot".

9a and'the center offtheshaft fia for 'theicam-G should'be greater than ,one-half'fthe. sum of..-the

diameters of the camshaft and pivot bearihgbfut not-so great as to unduly affct'the amount of housing I and preferably such. that: at tnemidit portion of advance and retard the follower block is on the line passing through the centers of the pivot 9a and the camshaft center.

One distinct advantage from the standpoint of reduction of cost in employing the small pivot is that only a small bearing would be required even if a ball bearing is employed and the customary large ball bearin surrounding the camshaft, which is expensive and which also had poor length-diameter ratio, would be eliminated.

The present construction is designed primarily for engines operating on a four-stroke cycle and it is, therefore, only necessary to vary the spark timing by an angle measured at the breaker camshaft center equal to one-half the crankshaft spark timing range as measured on the engine crankshaft. Since the timing range normally desired does not exceed thirty crankshaft degrees, then the range does not call for an adjustment of over fifteen degrees with reference to the breaker camshaft. Within this small angle the offset of the pivot So for the breaker support or plate 5 from the center of the breaker camshaft causes no significant change in the breaker point opening.

On the under side of the breaker support 5 is secured the terminal clip 33 to which is secured one end of the grounding lead 34 which has its opposite end secured to the terminal clip 35 which, in turn, is secured to the upper surface of the supporting plate 2.

The coil springs 2| and normally retain the circuit breaker support 5 and circuit breaker 1 in a retarded position and this is also the case when there is sufficient load on the engine that there will be little if any suction exerted on the diaphragm 24 through the conduit 2'! from the carburetor. The result is that due to this retardation of the spark, the engine does not knock during acceleration or idling or operation of the engine under considerable load. However when the operation of the engine is at sufficient speed and without tremendous load on the engine, sufficient suction will be exerted from the carburetor through the conduit 21 on the diaphragm 24 as to move said diaphragm 24 against the action of the spring 25 and to cause the connecting rod 28 to move the breaker support 5 to such position as to advance the spark.

From the foregoing it will be seen that we have provided relatively simple, efficient and economical supporting means for the breaker assembly whereby said assembly may be moved in angular relation to the cam to provide variations of spark timing in relation to engine crank position while eliminating the possibility of any erratic timing and variations in the spark timing and rough running of the motor due to any wobble or loose movement of the breaker assembly.

Having described our invention, we claim:

1. In a device of the character described, a supporting plate having an aperture, a camshaft extending through said aperture, a cam on said shaft and adapted to be rotated thereby, a breaker supporting member pivotally mounted on said supporting plate, a pivot on said plate for said member, said pivot being eccentrically displaced and spaced from said camshaft axis, a breaker contact supporting arm pivotally mounted on said breaker supporting member, a pivot for said breaker contact supporting arm, said pivot being offset from said pivot for said breaker supporting member, and a separate adjustable contact bracket on said breaker supporting member and supporting a contact adjacent the contact on said breaker contact supporting arm and means on said breaker contact supporting arm adapted to engage said cam for effecting operation of said breaker upon rotation of said cam and means for automatically effecting pivotal adjustment of said breaker supporting member and breaker supported thereby as a unit.

2. In a device of the character described, a supporting plate having an aperture, a camshaft extending through said aperture, a cam on said shaft and adapted to be rotated thereby, a breaker supporting member pivotally mounted on said supporting plate, a pivot on said plate for said member, said pivot being eccentrically displaced and spaced from said camshaft axis, a breaker contact supporting arm pivotally mounted on said breaker supporting member, a pivot for said breaker contact supporting arm, said pivot being offset from said pivot for said breaker supporting member, and a separate adjustable contact bracket on said breaker supporting member and supporting a contact adjacent the contact on said breaker contact supporting arm and means on said breaker contact supporting arm adapted to engage said cam for effecting operation of said breaker upon rotation of said cam and means for automatically effecting pivotal adjustment of said breaker supporting member and breaker supported thereby as a unit, the distance between the center of the pivot for the breaker supporting member and the center of said camshaft being greater than half the sum of the diameters of the camshaft and pivot bearings.

3. In a device of the character described, a supporting plate having an aperture, a camshaft extending through said aperture, a cam on said shaft and adapted to be rotated thereby, a breaker supporting member pivotally mounted on said supporting plate, a pivot on said plate for said member, said pivot being eccentrically displaced and spaced from said camshaft axis, a breaker contact supporting arm pivotally mounted on said breaker supporting member, a pivot for said breaker contact supporting arm, said pivot being offset from said pivot for said breaker supporting member, and a separate adjustable contact bracket on said breaker supporting member and supporting a contact adjacent the contact on said breaker contact supporting arm and means on said breaker contact supporting arm adapted to engage said cam for effecting operation of said breaker upon rotation of said cam and means for automatically effecting pivotal adjustment of said breaker supporting member and breaker supported thereby as a unit, the distance between the center of the pivot for the breaker supporting member and the center of said camshaft being at least one-half the sum of the diameters of the pivot and camshaft and not greater than the internal radius of the housing containing the support.

4. In a device of the character described, a supporting plate having an aperture, a camshaft extending through said aperture, a cam on said shaft and adapted to be rotated thereby, a breaker supporting member pivotally mounted on said supporting plate, a pivot on said plate for said member, said pivot being eccentrically displaced and spaced from said camshaft axis, a breaker contact supporting arm pivotally mounted on said breaker supporting member, a pivot for said breaker contact supporting arm, said pivot being offset from said pivot for said breaker supporting; member; and a: separate adjustable contact bracket ron said breaker supportingmems berr and supporting .a' conta'etaadjacent" the contactzon said breakercontact supporting arm and means :-on said breaker: contact-supporting arm adapted to: engage saidicam for effecting operation 'ofsaidabreakerxupon rotation of said cam and means for automatically efiecting pivotal adjustment .of said breaker supporting. member an'cliubrealzer;- supported thereby as -a unit, said breaker supporting member: having a peripheral portiomengagingea portion'zrof theperiphery of.-

th'e'shousin'g .for further: steadying said '.member.

5.? An ignitionwtiming, device for anengine includinga housing, 'a 'rotary cam'sin said housing, asupportwcarriedby said'housing, artimingplate pivotedsonisaid support: in an'. axis that is ecs centric withi' respect to thecaxis of. the; cam and at 'iaztgreaterz'distancesthan theimaximum. radius of..said:'cam; anxig-nition timing? circuit breaker provided with :an' element :adapted to periodical- 1y; engagezthe cam to openzthecircuit breakerv mounted on said timingplate with .said 1 element located diametrically opposite to the .plate pivotal 4 point with 2 respect to the. camsaxis;

6:..An1igni-tion timingtdevice i or an engine. including ;a housing, a rotary Vcam' inxsaidihousing, ausupport carried by saidhousing, an ignition timing circuit 1 breaker including a .cam follower, means pivoted on said-support ata point located outsiderot the maximum radius-ofathe. cam: formoving saidicircuit-breaker and cam follow-er withrespect. tothe cam, a. device'converting' engine suctionxinto movement connected to said means for moving the same, the arrangement being such that the point of application of force produced by said: device: tosaidmeansis diametrically opposite: to its pivotal point with respect .tothe cam axisiand the distance of the pivotal .pointlfrom the cam axis issgreater than theirdis'tance of the cam engagingface of said followerifrom the cam axis.

7; An ignition :timingdevice for an :engine includ-iznga housing, a rotary cam in said housing, a circuit breaker system having: a cam follower,

as. pivoted; ignition" timing plate.- for 'suppoorting' saidzicircu-it breaker system; the pivotal point of said timing. plateebeingalocated outside ofthe perimeter-sot the cam; a'.spring-loaded suctionresponsive? device. connected with said plate for m'oving the'samewith respect to said rotarycam for changing the movement to the circuit breaker cam follower, the arrangementbeing such with respect to'the cam-"axis that the movementof the circuit cam ignition timing imparting s: follower takes place in an area diametrically op.- posite to the pivotal point, and the point of con:-' nection of the plate with the suction-responsive device is located at a greaterdistance from-the camraxis than the distance of the circuit breaker:

canr'iol-lower therefrom.

8.v .An ignition timing device for an engine including a housing; a rotary cam in said housing, a support carried by said housing, a timing plate pivoted-onsaid. supportin'an' axisthat is eccentric with respect to the aXi'sJof the cam and .at a

greater ldistance than the maximum cam radius of said cam, an ignition timing circuitbreaker:

provided with an element adapted to periodical- 1y. engage the cam to. open the circuitbreaker mounted on said timing plate with said element located diametrically opposite to the plate cam. axis, and meansfor initially setting the breaker systemcam follower on said timing plate at azpointslightlydisplaced from a plane passing through the point of applicationioi force of the vacuum-actuated devicerand theplate pivotal point.

10. An ignition timing'assembly comprising a relatively stationary supporting member having acentralaaperture, a movable-ignition timing plate, means. for mounting said timing .plate on said supporting member'at a pivotal point spaced.

from? the aperture of the supporting member, a motion-transmitting device connected to the timing plate adjacent its outer periphery, and the saidzpivotal point and-l thev said pointiof connec-- tion of the motion-transmittingdevice with said plate being, diametrically opposite and located" at difierent radial (41151381110365'fIOm thE CBIItBI of the supporting member;

References (liteddnthe fileof this patent UNITED STATES PATENTS- Number Name Date.

1,445,261 Anderson Feb. 13,1923 2,035,621 Smith Mar. 31,-.1936 2,290,078 Thomas July 14, 1942. 2,348,236 Arthur May 9, v1944. 2,508,486 Berlynet a1. May. 23, 1950