US3499128A - Contact breaker assemblies - Google Patents

Description

March 3, 1970 Filed May 13, 1968 W. L. FRY

CONTACT BREAKER ASSEMBLIES 4 Sheets-Sheet 1 ATTORN'EYS CONTACT BREAKER ASSEMBLIES Filed May 13, 1968 4 Sheets-Sheet 2 INVE NTOR Mai-93% March 3, 1970 w, FRY 3,499,128

CONTACT BREAKER ASSEMBLIES Filed May 13, 1968 4 Sheets-Sheet 5 INVE NTOR Wi /y March 3, 1970 w. L. FRY

CONTACT BREAKER ASSEMBLIES 4 Sheets-Sheet 4 Filed May 13, 1968 INVENTOR N 06% United States Patent 3,499,128 CONTACT BREAKER ASSEMBLIES William Lawrence Fry, Birmingham, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England Filed May 13, 1968, Ser. No. 728,399 Claims priority, application Great Britain, June 12, 1967, 26,9'75/ 67 Int. Cl. H01h 19/00 US. Cl. 200-19 1 Claim ABSTRACT OF THE DISCLOSURE A contact breaker assembly for use in an ignition dis tributor is in the form of a self contained unit and includes a contact plate adapted to be mounted for pivotal movement within the distributor. A fixed contact is supported on a tag upstanding from the contact plate, and a sleeve is secured to the contact plate and pivotally supports an insulating heel member. The heel member carries the movable contact of the contact breaker assembly, the movable contact being engageable with the fixed contact. One end of a leaf spring is secured to the insulating heel member, and the other end of the leaf spring is anchored to the contact plate the spring urging the heel member to pivot in a direction to bring the movable contact into engagement with the fixed contact.

This invention relates to contact breaker assemblies for use in ignition distributors of the kind comprising a casing, a cam shaft journalled for rotation in the casing, a timing plate angularly movable with respect to the shaft to adjust the ignition timing of the distributor in use, a pivot post upstanding from the timing plate, a contact breaker assembly carried by said timing plate, the contact breaker assembly including a contact plate which is pivotally engaged with said pivot post and which carries a fixed contact, a heel member carrying a movable contact which is movable into and out of engagement with the fixed contact in response to rotation of the cam shaft and a leaf spring having one end thereof engaged with the cam follower and its other end anchored to the contact plate, the spring urging the movable contact into engagement with the fixed contact, the arrangement being such that pivotal movement of the contact plate with respect to the timing plate adjusts the gap between the contacts.

In conventional contact breaker assemblies for use in distributors of the kind specified the heel member is pivotally engaged with the pivot post carried by the timing plate and when it is desired to fit a new contact breaker assembly it is necessary to disconnect the electrical connections to the movable contact, release a locking screw which secures the contact plate to the timing plate, disengage the contact plate and the heel member from the pivot post, then engage the new contact plate and the new heel member with the pivot post, replace the locking screw and finally re-connect the electrical connections to the movable contact.

This procedure is cumbersome since it is diflicult to manoeuvre the contact plate and the heel member into alignment with each other and with the pivot post against the action of the leaf spring, within the confines of distributor casing. It is an object of the present invention to provide a contact breaker assembly for use in a distributor of the kind specified, which is simple to replace by comparison with conventional contact breakers.

According to the invention a contact breaker assembly for use in an ignition distributor of the kind specified, comprises a self-contained unit including a contact plate having a hole therein, a fixed contact supported on the contact plate, a sleeve secured to said contact plate and extending at right angles thereto coaxial with said hole, an insulating heel member pivotally supported on said sleeve, means for maintaining the heel member in position on the sleeve said means being such that the heel member can be engaged as a snap fit on said sleeve, during construction of the assembly, a movable contact supported on heel member, a leaf spring having one of its ends secured to said heel member, and an insulating member carried by the contact plate and to which the other end of the leaf spring is anchored so that the spring urges the movable contact into engagement with the fixed contact, the arrangement being such that when the contact breaker assembly is mounted in a distributor of the kind specified said pivot post extends into said hole in the contact plate to render the assembly pivotable with respect to the timing plate.

One example of the invention is illustrated in the accompanying drawings wherein:

FIGURE 1 is a fragmentary plan view of a contact breaker assembly with the spring thereof disengaged from the contact plate,

FIGURE 2 is a sectional view on the line 2-2 in FIG- URE 1 showing the assembly supported on the timing plate of a distributor,

FIGURE 3 is a plan view of the contact plate shown in FIGURE 1,

FIGURE 4 is a view similar to FIGURE 1 with the contact plate omitted,

FIGURE 5 is a sectional view showing the spring anchorage, and

FIGURE 6 is a part sectional plan view of an ignition distributor incorporating the contact breaker assembly shown in FIGURE 1.

Referring to the drawings, the contact breaker assembly includes an arcuate conductive contact plate 11 having a hole 12 adjacent one end thereof. Adjacent the hole 12, the plate is formed with an integral upstanding tag 13 which has secured thereto the fixed contact 14 of the assembly. A hollow sleeve 15 having an outwardly directed flange 16 at its lower end is welded to the plate 11 so as to extend at right angles thereto, coaxial with the hole 12, and adjacent its upper, free end the sleeve 16 is formed with a pair of diametrically opposite part circumferential ribs 17.

Pivotally engaged with the sleeve 15 is a moulded synthetic resin contact breaker heel 18 having integral therewith a cam follower portion 19. The heel 18 is formed at one end with a pair of arcuate resilient arms 21 which define between them a substantially circular hole 22, the diameter of which is fractionally less than that of the sleeve 15. Moreover, the inner surfaces of the arms 21 are so shaped that the circumference of the hole 22 includes three flats 23 spaced apart from one another by approximately In order to engage the heel 18 with the sleeve 15 the sleeve 15 is inserted into the hole 22 defined between the arms 21 and the heel 18 is urged downwardly towards the plate 11. As the heel 18 is urged downwardly the arms 21 flex apart so that the heel 18 can ride over the ribs 17 of the sleeve 15. When the heel 18 passes the ribs 17 the arms 21 spring towards each other so that the three flats 23 engage the sleeve 15. The ribs 17 are so positioned with respect to the plate 11 that they resist upward movement of the heel 18 relative to the plate 11 in use and moreover the arcuate spaces defined between the flats 23 and the sleeve 15 act as lubricant reservoirs in use.

Partially surrounding the heel 18 and secured thereto by a rivet is a generally U-shaped metal shell 20, the heel 18 including shoulders 20a at the roots of the portion 19 and one of the arms 21 respectively against which the shell abuts to locate the shell 20 in position on the heel 18. One limb of the shell 20 is extended and carries the movable contact 24 of the assembly at its free end, and furthermore one end of a leaf spring 25 is secured to the shell 20 by the rivet which secures the shell 20 to the heel 18 and the spring 25 is thereby electrically connected to the contact 24. The end of the spring 25 remote from the heel 18 is bent to define a loop 26 and the loop 26 is engaged with a generally cylindrical insulating member 27 which is a snap fit on a tag 28 bent up from the plate 11. Thus the spring 25 is anchored to the plate 11 and urges the heel 18 to pivot about the sleeve 15 in a direction to engage the contact 24 with the contact 14.

-In use the assembly is supported on the timing plate 29 of an ignition distributor which in turn is pivotally mounted on a base plate 30a secured to the casing 30 of the distributor. The cam shaft 30b of the distributor extends through the plate 30a and the plate 29 and the plate 29 is rotatable relative to the cam shaft to vary the ignition timing of the distributor. In conventional distributors the plate 29 has secured thereto an upstanding post and the assembly is engaged with the plate 29 with the post extending upwardly through the hole 12 in the plate 11 and into the sleeve 15. The plate 11 is formed with an arcuate slot 31 struck from the centre of the hole 12 and in use a screw 31a extends through the slot 31 into engagement with plate 29 the screw 31a being tightened to clamp the plate 11 to the plate 29. The plate 11 is pivotable about the post to move the contacts 14, 24 towards or away from the cam shaft so as to vary the operating gap between the contacts 14, 24, the screw being tightened to clamp the plate 11 in position relative to the plate 29.

In a modification shown in FIGURE 2 the post secured to the plate 29 is dispensed with and the plate 29 is stamped to form a short upstanding post 32. When the contact breaker assembly is engaged with the plate 29 the post 32 extends into the hole 12 in the plate 11 to render the plate pivotable on the plate 29.

The plate 29 is earthed in use and the member 27 is provided with an integral screw threaded spigot 27a. An annular terminal electrically connected through the primary winding of an ignition coil to a DC. source is engaged with the spigot 27a so that it rests on the loop 26 of the spring 25 and a nut is engaged with the spigot 27a and screwed down to clamp the terminal firmly in contact with the loop 26. Thus the contact 24 is connected to the DC. source through the spring 25, the terminal and the primary winding of the ignition coil and the contact 14 is earthed through the plate 11. The portion 19 of the heel 18 rides on the shaft of the distributor so that as the cam shaft rotates the movable contact 24 is moved into and out of engagement with the contact 14 so as to make and break the circuit to the primary winding of the coil. The high tension electrical pulses generated in the secondary winding of the ignition coil by the make and break of the circuit to the primary winding are of course directed to the sparking plugs of an internal combustion engine by the distribution part of the ignition distributor.

In a further modification (not shown) the sleeve 15 is formed with a circumferential groove in place of the ribs 17 and the hole 22 is formed with a circumferential rib which engages as a snap fit in the groove when the heel 18 is positioned on the sleeve 15. Moreover the contact 24 is domed and the contact 14 is flat and of larger diameter than the contact 24 thereby providing a greater margin for error in the positioning of the contact 24 relative to the contact 14 than is present in conventional contact breaker assemblies.

In use, it is found that there is a tendency for the plate 11 to tilt relative to the plate 29 when the screw 31a is tightened to clamp the plate 11 to the plate 29. In order to minimise tilting of the plate 11, the plate 11 is provided, adjacent the slot 31 with a downwardly directed projection 33 which engages the plate 29 asthe plate 11 is clamped to the plate 29. Conveniently, the projection 33 is formed by half shearing an area of the plate 11 adjacent the edge thereof.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A contact breaker assembly for use in an ignition distributor comprising, a self contained unit including a contact plate having an aperture therein, a fixed contact supported on the contact plate, a sleeve secured to said contact plate and extending at right angles thereto coaxial with said aperture, an insulating heel member having a pair of curved resilient arms which define between them a hole, said sleeve extending through said hole so as to mount said heel member for pivotal movement, an outwardly extending surface on said sleeve said surface maintaining the heel member in position on the sleeve and being such that the heel member can be engaged with the sleeve as a snap fit, during construction of the assembly, as permitted by flexure of said curved resilient arms, a movable contact supported on the heel member, a conductive leaf spring having one of its ends secured to the heel member, and an insulating member carried by the contact plate, the insulating member being engaged as a snap fit with a part integral with the contact plate and the insulating member having the other end of the leaf spring anchored thereto so that the leaf spring urges the movable contact into engagement with the fixed contact, the arrangement being such that when the contact breaker assembly is mounted in a distributor, a pivot post extends into said aperture in the contact plate to render the assembly pivotable with respect to a timing plate of the distributor.

References Cited UNITED STATES PATENTS 2,696,534 12/ 1954 Mallory 200-30 2,727,104 12/1955 Filko 200-30 2,769,046 10/1956 Russell 200-31 2,896,035 7/1959 Harrington et al 200-30 3,003,043 10/1961 Meyer et al 200-19 XR ROBERT S. MACON, Primary Examiner I R. SCOTT, Assistant Examiner U.S. Cl; X.R.

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