US2985727A

US2985727A - Full pressure ignition distributor

Info

Publication number: US2985727A
Application number: US768415A
Authority: US
Inventors: Eugene C Bettoni; Ernest R Larges
Original assignee: Holley Carburetor Co
Current assignee: Holley Performance Products Inc
Priority date: 1958-10-20
Filing date: 1958-10-20
Publication date: 1961-05-23
Anticipated expiration: 1978-05-23

Description

May 23, 1961 E. c. BETTONI ETAL 2,985,727

FULL PRESSURE IGNITION DISTRIBUTOR Filed 001;. 20, 1958 2 Sheets-Sheet 1 May 23, 1961 E. c. BETTONI EI'AL 2,985,727

FULL PRESSURE IGNITION DISTRIBUTOR Filed Oct. 20, 1958 2 Sheets-Sheet 2 TEELQ INVENTORS 5064'! C. Bil-row United States Patent FULL PRESSURE IGNITION DISTRIBUTOR Eugene C. Bettoni, Birmingham, and Ernest R. Larges,

Detroit, Mich., assignors to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Oct. 20, 1958, Ser. No. 768,415

18 Claims. (Cl. 200-31) The present invention relates to a full pressure ignition distributor, and more particularly to a distributor of this type responsive to variable engine conditions to effect a controlled spark advance.

More specifically, it is an object of the present invention to provide an ignition distributor comprising a shaft adapted to be driven at a speed dependent upon engine speed, a cam connected to said shaft for rotation therewith but with provision for relative angular adjustment, and means responsive to a variable pressure within the engine intake system for effecting controlled relative angular adjustment between the shaft and cam.

More specifically, it is an object of the present invention to provide a distributor comprising a shaft, an expansible chamber connected to said shaft for rotation therewith, said chamber including a wall movable axially of said shaft, an ignition timing cam disposed in axial alignment with said shaft, adjusting cam means fixed to said movable wall and a cam follower fixedly connected to said timing cam and operable by the adjusting cam means to effect angular adjustment of the timing cam.

Still more specifically, it is an object of the present invention to provide a drive shaft, a housing fixed to said shaft at one end thereof, a pilot fixed to said housing in alignment with said shaft, a timing cam mounted on said pilot for adjustment about the axis thereof, a pressure chamber within said housing including a movable wall, adjusting cam means fixedly secured to said movable wall, said adjusting cam means including inclined cam surfaces, and drive means fixedly connected to said timing cam and engageable with said camming surfaces to effect angular adjustment of said timing cam upon movement of said movable wall and adjusting means.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

Figure l is a vertical sectional view of an ignition distributor, including a diagrammatic illustration of its connection to a carburetor.

Figure 2 is a plan view of the distributor with the distributor cap and distributor arm removed.

Figure 3 is a fragmentary elevational view showing some details of the construction.

Figure 4 is a plan view of an expansible chamber housing included in the construction.

Figure 5 is a fragmentary sectional view on the line 5-5, Figure 4.

The ignition distributor comprises a housing which receives a drive shaft 12 adapted to be connected to a rotating part of the internal combustion engine associated with the distributor. Ordinarily, the shaft 12 is connected to rotate at half engine speed as is well understood in the art. The housing 10 includes an enlarged upwardly upon cup-shaped portion 14 adapted to receive part of the operating mechanism of the distributor as will subsequently be described. It is also provided with a passage 16 for connection through an external passage diagrammatically indicated at 18, to a source of variable fluid pressure within the internal combustion engine. This source of variable fluid pressure is herein indicated as comprising the intake passage 20 containing the usual choke valve 22, venturi 24, and throttle valve 26. Located within the throat of the venturi 24 is a fuel supply nozzle (not shown). As well understood, fiow of air through the venturi causes a venturi depression or partial vacuum at this point. An air passage 28 is connected through a restriction 30 to the throat of the venturi and through a restriction 32 to the intake passage 20 at a point just above the throttle plate 26 when the throttle plate is closed. When the throttle plate is closed as shown, a pressure not substantially below atmospheric pressure exists at the restriction 32. However, when the throttle plate opens so that an edge thereof passes to a position upstream from the restriction 32, manifold vacuum is applied to the restriction 32 and the pressure within the passage 28 drops materially.

At its upper end the shaft 12 is fixedly secured to a casing 34 comprising a lower shell 36 and an upper shell 38 between the peripheral edges of which is clamped a flexible diaphragm 40. The space between the diaphragm 40 and the lower shell 36 comprises an expansible and contractable chamber 42 and this chamber communicates through a passage 44 extending longitudinally of the shaft 12 to a transversely extending passage 46 which is always in communication with the passage 16 through an annular fitting 48 having continuous

annular recesses

50 and 52 communicating by a plurality of radially extending passages 54.

The central portion of the flexible diaphragm 40 is gripped between backing plates 56 herein illustrated as riveted together, the upper backing plate having fixedly secured thereto a pair of segmental cylindrical plates 58. The upper shell 38 of the casing 34 is provided with a pair of arcuate slots 60 through which the segmental plates 58 extend. Located between the lower shell 36 of the casing 34 and the lower backing plate 56 is a compression spring 62. It will be apparent that when the chamber 42 is subjected to a higher vacuum, as occurs when it is placed in communication with the engine manifold, the diaphragm and backing plates together with the segmental cylindrical plates 56 move downwardly.

Referring now to Figures 4 and 5 there is illustrated means for guiding the segmental cylindrical plates 58 in straight line relationship upon changes in the pressure condition existing within the chamber 42. For this purpose at adjacent ends of the slots 60 there are provided guide plates 64 herein shown as riveted to the upper shell 38 of the casing 34 by the rivets 66. Each of the guide plates includes a pair of upturned ears 68 which are positioned to extend along the ends of the arcuate slots 60 and so to engage the vertical edges of the segmental cylindrical plates 58.

As best seen in Figure 3, the segmental cylindrical plates 58 are each provided with an angularly extending camming slot 70 whose function will presently be described.

Fixedly secured to the upper shell 38 of the casing 34 is a pilot shaft 72. Adjacent its lower end the pilot shaft 72 is provided with a diametrically extending laterally elongated through opening 74.

Piloted on the pilot shaft 72 is the cam unit 76 including the timer cam 78. Extending diametrically through an opening in the lower portion of the cam unit 76 is an adjusting pin 80. The central portion of the pin is received in the opening 74 in the pilot shaft 72, this opening being laterally enlarged to permit angular adjustment of the cam unit 74 relative to the pilot shaft 72.

The ends of the pin 80 extend outwardly through the slots 70 in the adjusting cam plates 58.

From the foregoing it will be apparent that expansion and contraction of the chamber 42, with the resultant vertical movement of the flexible diaphragm 4t) and its backing plate 56, results in vertical movement of the adjusting cam plates 58. This in turn effects angular adjustment of the cam assembly 76 about the axis of the pilot shaft 72 and drive shaft 12. It will moreover be apparent that in any intermediate position of adjustment, the pin 80 serves to couple the timing cam assembly 76 to the drive shaft 12 against relative axial movement.

It will be understood that the timing cam 78 cooperates with a breaker arm 82 which is carried by a mounting plate 83 and which is caused to swing about its pivot axis to open and close contacts 84. Mounted on the upper shell 38 of the casing 34 are a pair of posts 86 and tension springs 88 are connected between the posts 86 and the ends of the pin 80, as best seen in Figure 2. The upper open end of the cup-shaped portion 14 of the housing is closed by the distributor cover 90 carrying a plurality of contacts one of which is indicated at 92, which are adapted to be connected sequentially by contact element 94 carried by the distributor arm 96 in the usual manner.

The ignition distributor herein is referred to as a full pressure distributor because adjustment of the timing of the spark is accomplished solely by variations in pressures existing within the engine. It is recognized that the degree of vacuum or venturi depression existing within the throttle of the venturi is a function of the speed of the engine since venturi depression is generally proportional to the velocity of air flow therethrough. In the same Way, it is recognized that the value of the manifold .vacuum existing in the manifold of the engine and in general at all points in the intake passage below the throttle plate is variable in accordance with the load on the engine. Accordingly, by providing a partial vacuum variable in accordance with venturi depression and a combination of venturi depression and manifold vacuum, there is provided pressure responsive means for controlling spark advance or timing in accordance with engine speed or a combination of engine speed and load. This is accomplished by a construction characterized by its simplicity, its sensitivity to small variations in pressure, the positive and rugged driving connection between the drive shaft and the timing cam, and the simplicity with which a particular adjusting cam shape may be provided. The separate cam adjusting plates 58 may have the inclined and preferably curved cam slots 70 machined therein very simply. V

The drawings and the foregoing specification constitute a description of the improved full pressure ignition distributor in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

1. An ignition distributor comprising a drive shaft, a casing fixed to one end of said shaft, a movable wall within said casing forming a pressure chamber therewith, a pilot shaft fixed to said casing in alignment with said drive shaft, a timing cam havng an opening receiving said pilot shaft, an adjusting cam carried by said movable wall and extending to a position laterally outwardly from said timing cam, said pilot shaft having a laterally enlarged diametrically extending through opening, a pin received in this opening and movable circumferentially therein but retained against relative movement axially of said pilot shaft, said pin extending through and radially beyond said timing cam and into engagement with said adjusting cam.

2. An ignition distributor comprising a drive shaft, a casing fixed to one end of said shaft, a movable wall within said casing forming a pressure chamber therewith,

a pilot shaft fixed to said casing in alignment with said drive shaft, a timing cam having an opening receiving said pilot shaft, an adjusting cam carried by said movable wall and extending to a position laterally outwardly from said timing cam, said pilot shaft having a laterally enlarged diametrically extending through opening, a pin received in this opening and movable circumferentially therein but retained against relative movement axially of said pilot shaft, said pin extending through and radially beyond said timing cam and into engagement with said adjusting cam, said adjusting cam having an inclined cam slot receiving an end portion of said pin to effect angular adjustment of said timing cam upon pressure changes in said chamber and to provide a rigid driving connection between said drive shaft and timing cam in all positions of adjustment.

3. An ignition distributor comprising a shaft, a tubular timing cam angularly adjustable on said shaft, means to prevent relative movement between said shaft and cam axially of said shaft, an adjusting cam movable axially of said shaft, said means also connecting said timing and adjusting cams to effect angular adjustment of said timing cam upon movement of said adjusting cam axially of said shaft.

4. An ignition distributor comprising a shaft, a tubular timing cam angularly adjustable on said shaft, means to prevent relative movement between said shaft and cam axially of said shaft, a pair of adjusting carns adjacent opposite sides of said timing cam movable axially of said shaft, said means also connecting said timing and adjusting cams to effect angular adjustment of said timing cam upon movement of said adjusting cams axially of said shaft.

5. An ignition distributor comprising drive means comprising aligned drive and pilot shafts and an interposed casing, a pressure responsive chamber in said casing including a flexible wall movable axially of said shafts, a pair of segmental cylindrical adjusting cams connected to said movable Wall and having portions disposed to extend adjacent opposite'sides of said pilot shaft, a timing cam piloted on said pilot shaft, means acting between said pilot shaft and timing cam effective to prevent relative axial movement therebetween while providing for relative circumferential movement, cam follower means acting between said timer cam and said adjusting cams elfective to provide angular adjustment of said timer cam on said pilot shaft upon movement of said movable wall. r 6. An ignition distributor comprising drivle means comprising aligned drive and pilot shafts and an interposed casing, a pressure responsive chamber in said casing including a flexible wall movable axially of said shafts, a pair of segmental cylindrical adjusting cams connected to said movable wall and having portions disposed to extend adjacent opposite sides of said pilot shaft, a timing cam piloted on said pilot shaft, said pilot shaft having a laterally enlarged diametrically extending opening, a pin extending through said opening and having portions fixed in said timing cam and end portions extending therebeyond into cooperating engagement with said adjusting cams.

7. An ignition distributor comprising drive means comprising aligned drive and pilot shafts and an interposed casing, a pressure responsive chamber in said casing including a flexible wall movable axially of said shafts, a pair of segmental cylindrical adjusting cams connected to said movable Wall and having portions disposed to extend adjacent opposite sides of said pilot shaft, a timing earn piloted on said pilot shaft, said pilot shaft having a laterally enlarged diametrically extending opening, *a pin extending through said opening and having portions fixed in said timing cam and end portions extending therebeyond into cooperating engagement with said adjusting cams, said adjusting cams having inclined slots receiving said end portions of said pin and effective to transmit torque to said timing cam and to effect angular adjustment thereof.

8. An ignition distributor comprising a rotary member, a timing cam, a pin connecting said cam to said member to prevent relative movement therebetween axially of said member and with provision for relative angular movement therebetween about the axis of said member, an adjusting cam concentric with, rotationally connected to and movable axially of said member, said pin being carried by said timing cam and engaging said adjusting cam to effect angular adjustment of said timing cam relative to said shaft upon movement of said adjusting cam axially of said shaft.

9. A distributor as defined in claim 8 including an expansible chamber having a movable flexible wall, said chamber being carried by said member, said adjusting cam being carried by said wall.

10. A distributor as defined in claim 9 including guide means carried by said member having guide surfaces parallel to the axis of said member and in the same radial location as said adjusting cam, said adjusting cam engaging and being guided by said guide means.

11. A full pressure ignition distributor for an internal combustion engine having a source of pressure variable with an engine operating condition which calls for a change in the timing of the spark supplied to the engine, said distributor comprising a distributor housing having therein a pair of timer contacts mounted in a fixed position, a plurality of distributor contacts, a shaft adapted to be connected to the engine and extending into said housing, a timer cam and distributor arm assembly disposed in said housing in axial alignment with said shaft, coupling means including a flexible movable wall within said housing connecting said assembly directly to said shaft for rotation therewith and for limited circumferential adjustment relative thereto.

12. A distributor as defined in claim 11 in which said coupling means further includes cooperating camming members, one of which extends transverse with respect to said shaft and is carried by said assembly, the other of said camming members being concentric with and movable axially of said shaft on movement of said flexible wall, and means connecting said assembly to said shaft to prevent movement axially thereof.

13. The structure as claimed in claim 3 wherein said shaft, adjusting cam and timing cam are concentric about a longitudinal axis and in the same plane for a portion of the length thereof and said means comprises an adjusting pin extending transversely through each of said shaft, adjusting cam and timing cam.

14. The structure as claimed in claim 4 and including 6 l a pair of guide members having surfaces parallel to the axis of said shaft and in the same radial location as said adjusting cams, said guide members being spaced angularly between said adjusting cams, said adjusting cams engaging and being guided by said guide means.

15. An ignition distributor comprising a rotatable shaft member, a timing cam member angularly adjustable on said shaft, first means connecting said members to prevent relative axial movement and to provide for relative angular movement therebetween, an adjusting cam carried by and movable axially of one of said members, guide means acting between one of said members and said adjusting cam effective to prevent relative rotation therebetween, said adjusting cam being engageable with said first means to effect relative angular movement between said timing cam and shaft upon movement of said adjusting cam axially of said members.

16. An ignition distributor comprising a rotatable shaft, a timing cam angularly adjustable on said shaft, an adjusting cam connected to said shaft for rotation therewith and movable axially of said shaft, and means connecting said timing cam and shaft operable to prevent relative axial movement therebetween and to effect angular adjustment of said timing cam relative to said shaft upon movement of said adjusting cam axially of said shaft.

17. An ignition distributor comprising a rotatable shaft having a laterally enlarged slot therethrough, a timing cam angularly adjustable on said shaft, an adjusting cam having cam surfaces inclined axially to said shaft adjacent to and movable axially of said shaft, and means extending through said slot connecting said timing cam and shaft to prevent relative axial movement therebetween and engaging said cam surfaces to effect angular adjustment of said timing cam relative to said shaft upon movement of said adjusting cam axially of said shaft.

18. .An ignition distributor comprising a rotatable shaft, a tubular timing cam sleeved over and angularly adjustable on said shaft, an adjusting cam sleeved over said timing cam and movable axially thereof, and means extending through said shaft and timing cam operable to prevent relative axial movement therebetween and engaging said adjusting cam to effect angular adjustment of said timing cam relative to said shaft on movement of said adjusting cam axially of said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,733,942 Chryst Oct. 29, 1929 1,792,072 Chryst Feb. 10, 1931 2,377,566 Mallory June 5, 1945