US3769471A

US3769471A - Distributor breaker plate assembly

Info

Publication number: US3769471A
Application number: US00164731A
Authority: US
Inventors: G Beard
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1971-07-21
Filing date: 1971-07-21
Publication date: 1973-10-30
Anticipated expiration: 1990-10-30
Also published as: DE2235795A1; AU4415072A; CA954396A; GB1352106A; IT961364B; ZA724199B; BR7204570D0; BE786535A; FR2146866A5

Abstract

A breaker plate assembly for an ignition distributor includes a base plate and a circuit breaker mounting plate. A link is pivotally connected to the base plate at one point on the link and is pivotally connected to the mounting plate at another point on the link. Pin and slot means associated with the base plate and mounting plate control movement of the mounting plate relative to the base plate. A set of circuit breaker contact points actuated by a cam follower is attached to the mounting plate. Because of the structure used, the cam follower moves concentrically with respect to a rotatable cam that actuates the cam follower. Concentric movement of the cam follower maintains the ignition dwell time substantially constant during advancement and retardation of the ignition timing.

Description

United States Patent 1 Beard Oct. 30, 1973 DISTRIBUTOR BREAKER PLATE Primary ExaminerLaurence M. Goodridge ASSEMBLY Attorney-Keith I... Zerschling et al. 75 Inventor: Garr E. Beard Livonia, Mich. I 1 y 57 ABSTRACT [73] Asslgnee: ri Company Dearbom A breaker plate assembly for an ignition distributor MIC includes a base plate and a circuit breaker mounting [22] Filed: July 21, 1971 plate. A link is pivotally connected to the base plate at one point on the link and is pivotally connected to the [21] Appl' l64731 mounting plate at another point on the link. Pin and slot means associated with the base plate and mount- 52 us. Cl 200/31, 123/117 A, 123/1465 A s plate control movement of mounting Plate [51] Int. Cl. H0111 19/62 ative t0 the base p A set of i i reaker c n ac [58] Field of Search 123/117 A, 146.5 A; points actuated y a cam follower is attached to the 200/19, 31, 31 A, 31 DP mounting plate. Because of the structure used, the cam follower moves concentrically with respect to a [5 6] References Cited rotatable cam that actuates the cam follower. Concen- UNITED STATES PATENTS tric movement of the cam follower maintains the ignition dwell time substantially constant during advancegzagfg 'g ment and retardation of the ignition timing.

: 8 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to a breaker assembly for use in an ignition distributor for a spark ignition engine. More particularly, the invention concerns a breaker plate assembly having moveable means for advancing or retarding the ignition timing during engine operation in response to changing operating conditions. Typically, movement of the breaker plate assembly in spark ignition eninges is obtained with a vacuum motor responsive to engine intake manifold vacuum.

. The usual ignition distributor for a spark ignition engine comprises a distributor housing having a rotatable shaft journaled therein. The shaft at its upper portion has a cam attached to it for actuating a cam follower attached to the moveable arm of a circuit breaker that includes a pair of contact points, one of which is mounted on the moveable arm-Rotation of the arm alternately opens and closes the circuit breaker contact points. When the'points open, an electrical impulse results and, through theaction of the engine ignition coil, a spark is produced in a combustion chamber. The number of degrees of cam rotation during which the contact points remain closed is referred to as the dwell time and is of considerable importance. It is desirable for a number of reasons to maintain this dwell time constant during the advancement and retardation of the ignition timing.

In order to obtain a constant dwell time, it is necessary that the cam follower attached to the moveable arm of the circuit breaker move concentrically with respect to the axis of the distributor cam during the advancement and retardation of the ignition timing.

Distributor breaker plate assemblies which will produce concentric movement of the circuit breaker cam follower relative to the axis of the rotatable cam are well known in the art. However, because of cost and reliability considerations, such prior art devices have been unsuitable for general production usage. For this reason, the usual breaker plate assembly has comprised a circuit breaker mounting plate pivotally connected to a base plate fixed with respect to the distributor housing. The pivotal connectionubetween the two plates necessarily has been off the axis of the rotatable distributor cam and movement of the mounting plate relative to the base plate about this pivotal connection to advance or retard ignitiontiming has resulted in a change in dwell time. The novel breaker plate assembly of the invention may be made interchangeable with this usual prior art device, and it may be manufactured at a comparable cost.

SUMMARY OF THE INVENTION In accordance with the invention, a breaker plate assembly for use in an ignition distributor having a housing adapted to receive a rotatable shaft and associated cam and having means for advancing or retarding the spark in response to engine operating conditions comprises a base plate adapted for stationary mounting with respect to the distributor housing. The base plate has a central opening therein to permit the rotatable shaft to pass therethrough. A circuit breaker mounting plate that may also have an opening therein to permit passage of the rotatable shaft therethrough also is provided. A circuit breaker is attached to the mounting plate. The circuit breaker has a set of contact points,

the set of contact points including a cam follower for opening and closing the contact points in response to rotation of thecam. A link is pivotally connected at one point thereon to the base plate and at another point thereon to the circuit breaker mounting plate. Guide pin and slot means associated with the base plate and with the mounting plate are provided for guiding the movements with respect to the base plate of the mounting plate and the link about the pivotal connections. The guide pin is positioned within the slot. The guide pin may be located in the base plate and the slot in the circuit breaker mounting plate, or, vice versa. A device, such as a hole or upstanding post, is provided in the mounting plate for the attachment of the distributor means for advancing or retarding the ignition spark in response to engine operating conditions.

Preferably, the mounting plate and link are positioned on opposite sides of the base plate and resilient means are provided for urging the mounting plate and link toward the base plate. Also, it is preferred that the link be constructed from a plastic material and that it be positioned within a recess in the base plate.

These and other constructional features of the breaker plate assembly of the invention are described in detail in the following specification and in the drawlngs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a distributor assembly incorporating a breaker plate assembly constructed in accordance with the invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 and illustrates the breaker plate assembly with the circuit breaker contact points removed except for the cam follower;

FIG. 3 is a view taken along the line 3-3 of FIG. 2 and illustrates the breaker plate assembly;

FIG. 4 is a view taken along the line 44 of FIG. 2 and illustrates the breaker plate assembly with the circuit breaker mounting plate removed; and

FIG. 5 is a view taken along the line 5-5 in FIG. 2 and illustrates the link used in the breaker plate, assembly.

DETAILED DESCRIPTION OF THE INVENTION With reference now particularly to FIGS. 1 and 2, a distributor shaft 12 is mounted rotatably within a distributor housing 14 by means of bearing 16. A cam 18 is carried by the shaft 12 and is rotatable therewith. Rotation of the shaft 12 is'obtained by the rotation of the gear 20 that meshes with another gear (not shown) driven by the engine.

Distributor means for advancing and retarding ignition timing in response to engine operating conditions is designated generally by the numeral 22. This means may be a dual diaphragm vacuum motor of the type described in US. Pat. Application Ser. No. 858,567, filed Sept. 11, 1969, and assigned to the Ford Motor Company. The vacuum motor 22 has an actuating rod 24 that moves back and forth along the axial centerline 26 of the vacuum motor in response to changing engine operating conditions.

The breaker plate assembly of the invention includes a base plate 28, a circuit breaker mounting plate 30, and a link 32. The link and both the mounting plate and base plate have openings therein for the passage of the shaft 12 and associated cam 18 therethrough. The base plate 28 and mounting plate 30 preferably are made from metal stampings, and the'link 32 preferably is made from a plastic material. Glass-filled nylon has been found to be a suitable material for the link 32.

The base plate 28 of the breaker plate assembly is attached in a fixed or stationary manner to the distributor housing 14 along an annular ledge or shoulder 34 with screws 36 (FIG. 1). The mounting plate 30 of the breaker plate assembly carries a circuit breaker 38 having a set of contacts 40. One of the circuit'breaker contacts is fixed with respect to the mounting plate, while the other contact is on a moveable arm 42 which pivots about the point 44. The moveable pivot arm 42 has a cam follower 46 positioned in engagement with the rotatable cam 18. In a conventional manner, a capacitor 48 is connected throughits lead wire 50 to a terminal 52 located on the circuit breaker 38. The terminal 52 is connected electrically to the contact on the moveable arm 42. The fixed contact is connected electrically through the lead wire 54 to the distributor housing. A lead wire 56 also is attached to the terminal 52 and has a connector 57 for attachment to an ignition coil (not shown).

Means for the attachment of the actuating rod 24 of the vacuum motor 22 to the mounting plate 30 is provided by an upstanding post 58 affixed to the mounting plate 30. This permits movements of the actuating rod 24 to be transmitted to the mounting plate 30.

With particular reference now to FIG. 2, it may be seen that the link 32 provides two pivot points for movement of the mounting plate 30 relative to the stationary base plate 28. One of the pivot points is located at 60 and pivotally connects the link 32 to the base plate 28. The pivot point 60 comprises a slotted boss 62 which is integral with the link 32. The slotted boss 62 mates with a flanged aperture 64 in the base plate 28. The other pivot point 65 on the link 32 is formed by an integral pivot pin 66 that extends through an opening in the base plate 28 to permit the formation of a pivotal connection at 68 between the link 32 and the mounting plate 30. Associated with and surrounding the pivot pin 66 is a coil spring 70 which is held in position by a spring retainer 72. The spring 70 urges both the link 32 and the mounting plate 30 toward the base plate 28. Thus, it may be seen that base plate 28 is stationary with respect to'the distributorhousing 14, the link 32 is pivotally connected at 60 with the base plate 28, and the link 32 also is pivotally connected by means of the pivot pin 66 with the mounting plate 30. Preferably, the pivot points 60 and 65 are located substantially opposite one another with respect to the openings in the link, base plate, and mounting plate through which the rotatable shaft 12 and cam 18 pass.

It is preferred that the link 32 be positioned within a recessed portion 74 in the base plate 28. Also, it is preferable that the mounting plate 30 be spaced from the base plate 28 to minimize contact therebetween. Three plastic buttons 76, one of which may be seen in section in FIG. 2 and all of which may be seen in FIG. 3, are attached to the mounting plate 30 for this purpose. The plastic button which may be seen in FIG. 2 is positioned within a recess in the mounting plate 30. The other buttons are not recessed.

With particular reference now to FIG. 3, there is shown a view of the full breaker plate assembly with the capacitor and points removed. The positions of the cam 18 and cam follower 46 are shown with dot-dash lines.

It may be seen that the mounting plate 30 has an-opening 78 through which the shaft 12 and its associated cam 18 may pass. Connected'with the opening 78 is a rectangularly-shaped opening 80. Opening 80 permits movement of the mounting plate without interference with the link-to-base plate pivotal connection formed by the slotted boss 62 and the flanged aperture 64.

The mounting plate 30 has a slot 82 in which a guide pin 84 affixed to the base plate 28 moves. Movement of the slot 82 along the guide pin 84 provides control of the movements of both the mounting plate 30 and link 32 relative to the stationary base plate 28, this movement occurring about both of the pivot points 60 and 65. It is the pin and slot means 82 and 84 which, through proper choice of slot shape and location, can be made to provide concentric movement of the cam follower 46 relative to the axis of the rotatable cam 18. As was previously stated, this movement is provided by the vacuum motor actuator rod 24 attached to the upstanding post 58 on the mounting plate 30, the movement being imparted in response to changing engine operating conditions.

In practice, the guide pin 84 may be located in the mounting plate 30, rather than in the base plate 28. In such case, the guide slot 82 would be located in the base plate 28. The location for the pin and slot means associated with the base plate and the mounting plate is not critical. However, the shape of the slot is dependent upon the location chosen for the pin. Thus, a point may be chosen on the base plate for the location of the pin and the mounting plate may then be moved about the pivot points 60 and 65 so that a desired path is taken by the cam follower 46. As this desired path is taken, a locus of points for the slot is determined. Generally, the locus of points will describe a curved path for the slot 82. However, when the slot is located approximately as shown in FIG. 3, the locus is very nearly a straight line. An elongated and straight slot thus may be used.

Threaded holes 86 and 88 provide means for the attachment of the circuit breaker contact point assembly 38 to the mounting plate 30. Threaded hole 90 provides a means for the attachment of the capacitor 48 to the mounting plate 30. As is conventional, a locating boss 94 is provided to establish the location of the capacitor 48. A cutout 92 in the mounting plate 30 permits it to move without interference with the screw 36 used to attach the base plate 28 to the distributor housing 14.

With reference now to FIG. 4, it may be seen that the base plate 28 has a central opening 96 through which the shaft 12 and associated cam 18 may pass. A rectangularly-shaped opening 98 also is provided. Opening 98 permits passage of the pivot pin 66 through the base plate 28 and permits unrestricted movement of the pivot pin 66, this pivot pin providing the pivotal connection between the link 32 and the mounting plate 30 as was previously described. The openings 96 and 98 are located in the recessed portion 74 of the base plate 28. In FIG. 4, this recessed portion 74 appears as a raised area.

Apertures

100, 102, and 104 in the base plate 28 are provided to permit unrestricted movement of screws or the like used to attach the capacitor and circuit breaker to the mounting plate 30. A portion of the link 32, which is positioned within the recess 74 in the base plate 28, may be seen through the aperture 104.

The configuration of the link 32 may best be seen in FIG. 5. Link 32 has a central opening 106 to permit passage therethrough of the shaft 12 and its associated cam 18. As was previously described, the pivot points 60 and 65 are located at the slotted boss 62 and the pivot pin 66, the pivotal connections being located substantially opposite one another with respect to the opening 106 in the link. Link 32 has raised bosses 108, 110, 112, and 114. These bosses limit the amount of surface area of link 32 that comes into actual contact with the base plate 28. Preferably, the bosses 112 and 114 are about one-half the height of bosses 108 and 110. This permits the spring 70 surrounding the pivot pin 66 to draw in the central portion of the link 32 and applies a bias force to the pivotal connection 60.

Based upon the foregoing description of the invention, what is claimed and desired to be protected by Letters Patent is:

l. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said breaker plate assembly comprising: a base plate, said base plate having an opening therein; a circuit breaker mounting plate positioned on one side of said base plate; a link positioned on the other side of said base plate, said link being pivotally connected at a first point thereon to said base plate, said link being pivotally connected at a second point thereon to said mounting plate, said pivotal connection at said second point including a pivot pin extending through said opening in said base plate, and said link having an opening therein, said first and second pivotal points being located at substantially opposite sides of said opening in said link; and guide pin and slot means associated with said mounting plate and with said base plate for guiding the movement of said mounting plate and link relative to said base plate about said first and second pivotal connections; whereby, when said base plate is attached to said distributor and a force is applied to said mounting plate, said link pivots about said first pivotal connection between it and said base plate, said mounting plate pivots about said second pivotal connection between it and.

said link, and said second pivotal connection moves relative to saidbase plate, said movement of said second pivotal connection being guided by said guide pin and slot means associated with said mounting plate and base plate.

2. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said distributor having a housing adapted to receive a rotatable shaft and associated cam and having means for advancing or retarding said spark in response to engine operating conditions, said breaker plate assembly comprising: a base plate adapted for stationary mounting with respect to said housing of said distributor, said base plate having an opening therein to permit said rotatable shaft to pass therethrough; a circuit breaker mounting plate having an opening therein to permit passage of said rotatable shaft therethrough; a circuit breaker attached to said mounting plate, said circuit breaker having a set of contact points, said set of contact points including a cam follower for opening and closing said contact points in response to rotation of said cam; a link, said link being pivotally connected to said base plate at a first point on said link and being pivotally connected to said mounting plate at a second point on said link, said pivotal connections being located substantially opposite one another with respect to said opening in said base plate, guide pin and slot means associated with said base plate and with said mounting plate for guiding the movements relative to said base plate of said mounting plate and said link about said pivotal connections; and means in said mounting plate for the attachment of said distributor means for advancing or retarding said spark in response to engine operating conditions; whereby, when said base plate is attached to said distributor housing and a force is applied to said mounting plate by said means for advancing or retarding said spark, said link pivots about said pivotal connection between it and said base plate, said mounting plate pivots about said pivotal connection between it and said link, and said pivotal connection between said mounting plate and said link moves relative to said base plate, this pivotal connection movement being guided by said guide pin and slot means associated with said base plate and mounting plate.

3. A breaker plate assembly in accordance with claim 1, wherein said mounting plate and said link are positioned on opposite sides of said base plate and wherein said guide pin and slot means comprises a slot in said mounting plate and a pin affixed to said base plate, said pin extending into said slot for movement therein.

4. A breaker plate assembly in accordance with claim 1, wherein said mounting plate and said link are positioned on opposite sides of said base plate and wherein said pivotal connection between said link and said mounting plate comprises a pivot pin integral with said link and extending therefrom through said opening in said base plate to permit pivotal connection with said mounting plate, and means in contact with said pivot pin for resiliently urging said mounting plate and said link toward said base plate.

5. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said breaker plate assembly comprising: a base plate, said base plate having an opening therein and said base plate having a recessed portion; a circuit breaker mounting plate positioned on one side of said base plate; a link positioned within said recessed portion of said base plate and on the other side thereof, said link being pivotally connected at a first point thereon to said base plate, and said link being pivotally connected at a second point thereon to said mounting plate; and guide pin and slot means associated with said mounting plate and with said base plate for guiding movements of said mounting plate and said link relative to said base plate; whereby, when said base plate'is attached to said distributor and a force is applied to said mounting plate, said link piv ots about said pivotal connection between it and said base plate, said mounting plate pivots about said pivotal connection between it and said link, and said pivotal connection between said mounting plate and said link moves relative to said base plate, this pivotal connection movement being guided by said guide pin and slot means associated with said mounting plate and base plate.

6. A breaker plate assembly in accordance with claim 5, wherein said pivotal connection of said link with said base plate at said first point on said link comprises a slotted boss integral with said link and a flanged aperture in said base plate, said slotted boss being positioned within said flanged aperture.

7. A breaker plate assembly in accordance with claim 6, wherein said pivotal connection of said link with said mounting plate at said second point on said link comprises a pivot pin integral with said link and extending through said opening in said base plate to permit pivotal connection with said mounting plate, and wherein said breaker plate assembly further comprises resilient means for urging said mounting plate and said link toward said base plate. a

8. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said breaker plate assembly comprising a base plate, said base plate having an opening therein; a circuit breaker mounting plate positioned on one side of said base plate; a link positioned on the other side of said base plate, said link being pivotally connected at-a first point thereon to said base plate, said link being pivotally connected at a second point thereon to said mounting plate, said pivotal connection at said second point including a pivot pin extending through said opening in said base plate and said pivotal connection at said second point having associated therewith resilient means for urging said mounting plate and said link toward said base plate; and guide pin and slot means associated with said base plate and with said mounting plate for guiding the movements relative to said base plate of said mounting plate and said link about said first and second pivot points, said slot of said guide pin and slot means being elongated and substantially straight in shape, said guide pin of said guide pin and slot means being movable in said slot; whereby, when said base plate is attached to said distributor and a force is applied to said mounting plate, said link pivots about said pivotal connection be- I tween it and said base plate, said mounting plate pivots and mounting plate.

Claims

1. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said breaker plate assemBly comprising: a base plate, said base plate having an opening therein; a circuit breaker mounting plate positioned on one side of said base plate; a link positioned on the other side of said base plate, said link being pivotally connected at a first point thereon to said base plate, said link being pivotally connected at a second point thereon to said mounting plate, said pivotal connection at said second point including a pivot pin extending through said opening in said base plate, and said link having an opening therein, said first and second pivotal points being located at substantially opposite sides of said opening in said link; and guide pin and slot means associated with said mounting plate and with said base plate for guiding the movement of said mounting plate and link relative to said base plate about said first and second pivotal connections; whereby, when said base plate is attached to said distributor and a force is applied to said mounting plate, said link pivots about said first pivotal connection between it and said base plate, said mounting plate pivots about said second pivotal connection between it and said link, and said second pivotal connection moves relative to said base plate, said movement of said second pivotal connection being guided by said guide pin and slot means associated with said mounting plate and base plate.

5. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said breaker plate assembly comprising: a base plate, said base plate having an opening therein and said base plate having a recessed portion; a circuit breaker mounting plate positioned on one side of said base plate; a link positioned within said recessed portion of said base plate and on the other side thereof, said link being pivotally connected at a first point thereon to said base plate, and said link being pivotally connected at a second point thereon to said mounting plate; and guide pin and slot means associated with said mounting plate and with said base plate for guiding movements of said mounting plate and said link relative to said base plate; whereby, when said base plate is attached to said distributor and a force is applied to said mounting plate, said link pivots about said pivotal connection between it and said base plate, said mounting plate pivots about said pivotal connection between it and said link, and said pivotal connection between said mounting plate and said link moves relative to said base plate, this pivotal connection movement being guided by said guide pin and slot means associated with said mounting plate and base plate.

7. A breaker plate assembly in accordance with claim 6, wherein said pivotal connection of said link with said mounting plate at said second point on said link comprises a pivot pin integral with said link and extending through said opening in said base plate to permit pivotal connection with said mounting plate, and wherein said breaker plate assembly further comprises resilient means for urging said mounting plate and said link toward said base plate.

8. A breaker plate assembly for use in an ignition distributor for a spark ignition engine, said breaker plate assembly comprising a base plate, said base plate having an opening therein; a circuit breaker mounting plate positioned on one side of said base plate; a link positioned on the other side of said base plate, said link being pivotally connected at a first point thereon to said base plate, said link being pivotally connected at a second point thereon to said mounting plate, said pivotal connection at said second point including a pivot pin extending through said opening in said base plate and said pivotal connection at said second point having associated therewith resilient means for urging said mounting plate and said link toward said base plate; and guide pin and slot means associated with said base plate and with said mounting plate for guiding the movements relative to said base plate of said mounting plate and said link about said first and second pivot points, said slot of said guide pin and slot means being elongated and substantially straight in shape, said guide pin of said guide pin and slot means being movable in said slot; whereby, when said base plate is attached to said distributor and a force is applied to said mounting plate, said link pivots about said pivotal connection between it and said base plate, said mounting plate pivots about said pivotal connection between it and said link, and said pivotal connection between said mounting plate and said link moves relative to said base plate, this pivotal connection movement being guided by said guide pin and slot means associated with said base plate and mounting plate.