US2713094A - Preset ignition contacts for combustion engine distributor - Google Patents

Description

July 12, 1955 1... s. zoccx-a: $713,094

PRESET IGNITION CONTACTS FOR COMBUSTION ENGINE DISTRIBUTOR Filed Aug. 27, 1955 L G %VVENT0R.h 1:011. OCC 1.

HTTOR EY Patented July 12, 1955 ice PRESET EGNITTQN CONTACT S FOR COMBUSTION ENGTNE DISTRIBUTOR Leon G. Zocchi, Milford, Mass.

Application August 27, 1953, Serial No. 376,794

2 @iaims. (Cl. 200-410) My invention relates to the distributor head of a combustion engine which comprises a rotary cam arranged to make and break the electrical contact between two ignition points or contacts. In the standard apparatus, one contact or breaker point is held stationary on a contact plate which is mounted on the distributor housing for adjustment relative to the cam. The other breaker point or contact is mounted on a pivoted arm which resiliently urges its contacts towards the stationary contact. The arm has a cam follower engaging the rotary cam and it is moved thereby to break the contact between the points. In such construction, the distance of separation of the contact points, when the cam follower on the contact arm is located on the high point of the cam, is regulated by means of a gauge of exact dimensions. The gauge is placed between the contact points and the contact plate carrying the parts is then adjusted into position so that the contacts will open at the high point of the cam to the exact thickness of the gauge plate. This construction is such that when the cam is rotated at very high speed, the inertia of the swinging contact arm causes it to swing out of contact with the high point of the cam and not maintain contact with the cam. Consequently, the timing relationship of the cam and points becomes inaccurate and the motor tends to miss at high speeds.

The primary object of this invention is to overcome such problems and to provide a distributor having cam actuated ignition contacts which are pre-set in an exact relationship for the high point of the cam, and wherein the movable contact cannot swing beyond a pre-set position and the cam follower remains substantially in contact with the cam high point, so that it is unnecessary to employ any gauge to adjust the positions of the contact points when installed. Further objects will be apparent in the following disclosure.

Referring to the drawings illustrating two embodiments of this invention:

Fig. 1 is a fragmentary top plan view of a distributor plate and its rotary cam in association with the pre-set ignition contact mechanism in which the cam follower is located opposite the low point of the rotary cam and the ignition points are in contact;

Fig. 2 is a similar view of the same mechanism but showing the relative positions of the cam and cam follower when the contact points are separated to the maximum predetermined distance;

Fig. 3 is a fragmentary elevation taken on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary View of a modification of the stop parts which limit the throw of the movable contact point, and

Fig. 5 is a fragmentary view taken at right angles to Fig. 4.

Referring first to Figs. 1 to 3 inclusive, the distributor head comprises a carrier plate on which the contact device is mounted. A rotary steel cam 11 of required shape is suitably mounted to be perpendicular to the plate and so arranged that the high points 12 as well as the low faces of the cam will contact a cam follower 14 mounted on the swinging arm 15. The parts are arranged to separate the breaker contact point 16 on the arm 15 from a stationary point 17 carried by the plate 10 and to allow their return into contact when the follower is opposite each of the low points of the cam. This cam follower 14 may be made of suitable insulating material, such as a standard fibre composition. The stationary contact point 17 is suitably mounted on a contact holder plate 18 carried by the housing plate 10, such as by means of a rivet 19 passing through and secured in electrical contact with an upstanding arm or lug 20 integral with and perpendicular to the fiat base plate 18.

The swinging arm 15 is pivotally mounted on a vertical post 22 by means of a suitable construction such as illustrated. The arm may be channel shaped adjacent the post or provided with parallel tapering flanges 23 secured to the body portion of the plate 15 which terminates near the pivot post. The spaced flanges 23 have circular plates 24 carrying therebetween a cylindrical fibre sleeve 25. This sleeve is rotatably mounted on a stationary metal bearing post 26 that is secured as by riveting to the base plate 18 and perpendicular thereto. The cam follower i4 is an L-shaped piece of fibre board or other suitable substance suitably secured between the flanges 23 on the plate 15, as by means of a metal rivet 28. The arm 15 is spring pressed to urge the electrical contacts 16 and lli together. The spring may comprise a flat resilient strip 3%) of suitable steel or other material and a copper strip 31 which efficiently conducts electrical current. The metal spring 30 passes around the pivot end of the bottom plate of the arm 15 and hooks under the bottom plate. The copper strip 31 passes around the outside of the fibre sleeve 25 and is shaped to lie against the face of the swinging arm 15 and beneath the fibre cam follower 14 and be secured in position at that end by means of the rivet 28. The other ends of the spring 3t? and the strip 31 are in contact, and each is provided with an elongated slot 33 through which a binder post 35 passes. This binder post is a threaded brass rivet mounted on a lug 36 which is perpendicular to and stands up from an edge portion of the base plate 3, as shown.

The metal binder post 3..) carries the electrical current to the movable contact member 16 on the arm 15, the copper strip 31 being provided to insure a high conductivity. A wire 37 is clamped by the nut 38 on the threaded post 35 against a metal plate 48 secured in electrical contact with the post 35. A metal washer 39 on the inner end of the post 35 maintains contact with an outer metal contact head 46 on the post. The two parts 38 and 4b as well as the post 35 are insulated from the upstanding lug 36 by means of a U-shaped fibre strip il which has aligned slots and is mounted on the post around the lug 36, as illustrated. The lug 36 has an enlarged hole therethrough in which the brass threaded post 35 is mounted out of contact electrically with the lug. The washers and 39 straddle the slot in the fibre and hold the parts in place. Various other constructional arrangements may be made for the purpose of preventing any short circuit and insuring a proper mounting for the end of the spring and suitable passage of electrical current from a suitable condenser and primary coil to the post 35. It will thus be seen that when the cam 11 rotates, the cam follower 14 will be forced to separate the movable contact 16 from the stationary contact 17 and to break the circuit between the wire 37 and the contact 17 which is in electrical circuit with the ground formed by the contact plate housing and associated motor parts.

The above described features may be of suitable or standard construction, except as modified by my invention. In order that the contact plates 16 and 17 may be separated only to a preset distance and cannot be thrown beyond that distance, I shape the rivet head 40 and/or the adjacent head 42 of the rivet 28 such that the parts 40 and 4-2 form a stop and will substantially contact at the time when the cam follower 14 is on the high point 12 of the cam. The heads 40 and 42 are each of a predetermined size or thickness, so that the arm 15 can be thrown outwardly only to the exact distance required for a proper separation of the electrically conductive breaker contact points 16 and 17. This insures that the follower 14 will not leave contact with the cam to a material extent on the outward movement of the arm 15. Thus, the swinging arm 15 is brought to a full stop at the maximum separation of the points 16 and 17 and it is ready then to be urged by the spring 31 into contact with the low parts of the rotating cam between the high points 12. The breaker points 16 and 17 will return into contact when the follower 14 reaches the low point of the cam and then be separated by an exact predetermined distance as the cam revolves.

In order to assemble the contact plate 18 correctly on the distributor head plate 10, the contact plate 18 is provided with two elongated slots 45 adjacent its two ends within which the large headed screws 46 are mounted. These screws are threaded into the base plate and the heads are shaped to extend beyond the sides of the slot and clamp the two ends of the plate 18 in place. Hence it is merely necessary to place the contact plate 18 on the carrier plate 10 and, with the screws 46 loose, to adjust the position of the plate 18 until the stops 40 and 42 are in contact when the cam follower 14 just touches the high point of the cam. Upon setting the two screws 46 tightly in place, the plate 18 will be definitely located and the contact arm may swing through the correct and predetermined distance. It will be understood that plate 10 is customarily rotated through a. small angle to advance or retard the ignition.

It will now be appreciated that various types of stop may be employed to limit the swing of the arm and to. provide for an exact size of gap between the breaker points of the electrical make and break device used with a gasoline combustion motor, and wherein that gap is preset at the factory to a maximum adjustment. One suitable modification is illustrated in Figs. 4 and 5. In this modification, the movement of the swinging arm 15 may be limited by means of a stop 50 placed behind the outer end of the arm 15 and correctly located so that the breaker points 16 and 17 may be opened only to a predetermined distance. This stop 59 may be made as the inturned end of an upstanding lug 52 which is formed on the end of the swinging arm 15. The stop is so located relative to the arm 15 as not to interfere with the cap ployed for manufacturing the parts in the shop and provide the required gap of breaker point spacing.

' The primary feature of such construction lies in the employment of a stop which limits the outward throw of the spring pressed breaker point arm 15 under the high speed impact of the high points 12 of the rotary cam and wherein the stop is exactly located so that when the arm 15 has been thrown to its maximum distance it yet remains in contact with the cam high point 12 and the contact members 16 and 17 will be exactly spaced as required for the most efficient operation of the electrical ignition system. The spring 30 returns the contact points into engagement while the cam follower is opposed to but slightly out of contact with the lowest point of the cam, and the follower has merely to separate the contacts by the required gap, such as 0.020 inch, as it passes to the high point of the cams. This insures an adequate separation of the breaker points and an efficient spark at the spark plugs in the explosion chamber.

The advantages inherent in this construction will be readily apparent, and it will be appreciated many modifications may be made in the construction within the scope of this invention. Hence the above disclosure is to be intended as a description of the preferred embodiments of the invention and not as imposing limitations on the appended claims.

I claim:

1. In a combustion motor electrical make and break device including a rotary cam, a carrier plate, a stationary electrical contact carried by the plate, a movable contact, a resiliently urged pivoted arm carrying and moved by a follower for the cam, the movable contact being mounted on the arm for movement into and out of engagement with the stationary contact as the cam rotates, a fixed rigid, non-adjustable and non-resiliently mounted stop carried on the plate which engages and limits the maximum outward movement of the arm and predetermines the distance of separation of the contacts, and means for locating the relative positions of the plate and cam so that the follower is on a high point of the cam when the stop engages the arm.

2. In a combustion motor electrical make and break device including a rotary cam, a carrier plate, a stationary electrical contact on the plate, a swinging arm, a movable electrical contact on the arm, a pivot mount for the arm on the plate which provides for movement of the movable contact to and from engagement with the stationary contact, a spring carried by the plate which engages the arm and urges the arm contact towards engagement with the stationary contact, a cam follower on the arm moved by the cam to swing the arm, a stationary lug on the plate, a fixed stop engageable by the arm which is non-adjustably and non-resiliently fixed on the lug so that the stop is exactly positioned to provide a predetermined maximum gap between the contacts and limit the outward movement of the arm, and means for adjusting the position of the plate relative to the cam so that the follower touches the high point of the cam when the stop engages and prevents further movement of the arm.

References Cited in the file of this patent UNITED STATES PATENTS 1,426,873 Hunt Aug. 22, 1922 2,274,816 Winther Mar. 3, 1942 FOREIGN PATENTS 691,368 France July 8, 1930

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