US3678806A

US3678806A - Dual diaphragm distributor

Info

Publication number: US3678806A
Application number: US29360*[A
Authority: US
Inventors: Frank M Kittredge
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1970-09-18
Filing date: 1970-09-18
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25

Abstract

A vacuum motor having two independently mounted and movable flexible diaphragms mounted in a common housing and partitioning the housing into fluid chambers, one of the diaphragms having a limited movement and at times limiting the movement of the other diaphragm, the other being connected to a means to be actuated.

Description

United States Patent Kittredge 1 July 25, 1972 [54] DUAL DIAPHRAGM DISTRIBUTOR 3,385,275 5/1968 Burnia et all. ..123/117 3,362,297 1/1968 Cripe ..92/48 X [721 Invenm Frank Kimedge, Temperance, Mlch- 3,352,209 11/1967 Cripe 92/49 x 73 A F d M t C a D b h. 2,837,1l9 Schwartz 6181 X 1 SS gm W 3,096,689 7/1963 Kytta ..92/99 x [22] Filed: Sept. 18, 1970 3,397,621 8/1968 Groves ..92/48 [21] Appl' 29360 Primary Examiner-Martin P. Schwadron Assistant Examiner-Leslie J. Payne Related Application Data Attorney-John R. Faulkner and Robert E. McCollum [62] Division of Ser. No. 858,567, Sept. 11, 1969, Pat. No.

3,599,614. [57] ABSTRACT A vacuum motor having two independently mounted and [52] US. Cl ..92/48, 92/100 movable flexible diaphragms mounted in a common housing [51] lnt. Cl ..F0lb 19/00 and partitioning the housing imo fl id chambers, one f the Field 01 Search diaphragms having a limited movement and at times limiting 1/ 369 369 7 7 the movement of the other diaphragm, the other being connected to a means to be actuated. [56] References Cited UNITED STATES PATENTS Hill ..60/54.6

8 Claims, 8 Drawing Figures PATENTED L I 3.678.806 sum 1 or 5 AT' TORNEYS PKTENTED I973 3.678.806

sum 2 or 3 INVENTOR. Few/m 44. 4777181062 ATTORNEYS 1 DUAL DIAPHRAGM DISTRIBUTOR This application is a division of Ser. No. 858,567, DUAL DIAPHRAGM DISTRIBUTOR, filed Sept. ll, 1969, now US. Pat. No. 3,599,614 issued on Aug. 17, 1971.

This invention relates, in general, to a fluid motor construction. More specifically, it relates to a dual diaphragm vacuum motor assembly contained within a single housing.

Anti-Smog regulations relating to internal combustion engine exhaust emission controls point out the desirability of a retarded ignition timing at engine idle and deceleration conditions as well as a rapid shift to normal timing at all other engine operating conditions. The retarding of the ignition timing during idle and deceleration produces a marked reduction in engine exhaust hydrocarbon emissions, whereas a rapid shift to normal ignition timing allows starting ease and minimum loss of engine performance and economy.

Devices are known in the prior art for automatically advancing or retarding the engine distributor advance plate to control the spark timing. However, these devices generally require a plurality of separate and remote elements, which increase the overall cost of the engine and complexity of the system.

The invention relates to a dual diaphragm vacuum motor assembly within a single housing that operates automatically in conjunction with other controls to properly regulate the movement of the ignition distributor spark advance and retard mechanism to provide the desired retarding or advancing of the spark at all engine operating conditions.

It is an object of the invention, therefore, to provide a dual diaphragm fluid motor assembly having a pair of coaxially mounted and axially spaced annular diaphragms mounted within a single housing for independent movement at times, and conjoint movement at other times.

It is another object of the invention to provide a vacuum motor assembly for an ignition distributor that automatically advances or retards the ignition timing as a function of the engine operating conditions as determined by the change in flow of the air-fuel mixture through the carburetor, and by the change in intake manifold vacuum ofthe engine.

It is still a further object of the invention to provide a vacuum motor assembly consisting of two coaxially mounted, independently'movable, flexible diaphragms mounted within a common housing to partition the housing into separate fluid or vacuum chambers; one being connected to a portion of an engine carburetor above the throttle valve, the other being connected to the carburetor below the throttle valve at a point leading to the intake manifold; one of the diaphragms being connected to the distributor advance plate and cooperating at times with the other diaphragm to have a limited movement in one direction while being essentially freely movable in the opposite direction; the other diaphragm having a limited movement in both directions to at times control the movement of the sparkadvance plate while at other times being ineffective to provide such control.

Other objects, features and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating the preferred embodiment thereof, wherein;

FIG. I illustrates, schematically, an internal combustion engine spark timing control mechanism embodying the invention;

FIG. 2 is a cross-sectional view of the vacuum motor illustrated in FIG. 1;

FIGS. 3 and 4 are end elevational views, with parts broken away and in section, taken on planes indicated by and viewed in the direction of the arrows 3-3 and 4-4, respectively, of FIG. 2; and,

FIGS. 5, 6, 7, and 8 are cross-sectional views similar to FIG. 2 illustrating the parts therein in various operative positions corresponding, respectively, to engine starting and wide open throttle positions, engine idling position, part throttle operation, and engine deceleration operation.

FIG. 1 shows, schematically, those portions of an internal combustion engine that are interrelated with the vacuum motor assembly of the invention to provide for an automatic retardation or advancement of the engine distributor ignition timing. More specifically, 10 indicates, in general, an ignition distributor of the centrifugal advance type having an ignition timing advance plate 12. The plate surrounds the conventional rotor cam 14 and is pivoted for movement about a point 16 fixed to the stationary distributor housing, not shown. Rotor cam 14 cooperates with a set of breaker points 18 by means of an actuator 20 secured to one arm of the breaker points set, as shown. Advance plate 12 is pivotally secured at 22 to a reciprocatable actuating rod 24 that is adapted to be moved in a manner to be described by the dual diaphragm vacuum motor assembly 26 embodying the invention.

At the opposite sides of the vacuum motor assembly is shown a portion 28 of a carburetor of the conventional downdraft type. It has the usual air-fuel induction passage 30 containing a fixed area ventun' 32 and a conventional throttle valve 34 pivotally mounted on a portion of the carburetor housing to control flow from manifold 36.

In general, vacuum motor assembly 26 includes two flexible diaphragms, each of which forms a fliuid or vacuum chamber with the housing to provide various control movements of the advance plate actuating rod 24. The chamber closest to the distributor is connected by a hose or line 38 directly to the vacuum of the engine intake manifold through carburetor port 40 that opens into the carburetor below throttle valve 34. It will be clear, of course, that port 40 could be located to open directly into intake manifold 36. The other vacuum motor chamber is connected by a hose or line 42 through a shuttle valve controlled mechanism 44 and a port 46 to a point in carburetor induction passage 30 above throttle valve 34, it is in its idle position.

Shuttle valve 44, referred to as a deceleration control valve, or decel valve, is controlled in its movement by the level of the intake manifold vacuum, abranch line 47 connecting the intake manifold vacuum in line 38 to act on the valve. Below a predetermined intake manifold vacuum, the valve connects carburetor port 46 to vacuum motor hose 42, vacuum above this point moving the shuttle valve to connect intake manifold vacuum in branch line 47 to hose 42.

Decel valve 44, in this case, comprises a reciprocable valve alternately seatable against two

ports

48 and 49 as a function of the differential force between intake manifold vacuum in line 47 applied to one side of a diaphragm 50 opposed by the force of a tension spring 51. As stated previously, the valve determines whether carburetor port pressure in line 46 or intake manifold vacuum in line 47 will be applied to the vacuum motor chamber connected to hose or line 42.

The manifold vacuum level necessary to actuate the shuttle valve, in this case, would occur only during deceleration operation of the engine, at which time a higher than normal intake manifold vacuum is present in the system.

FIGS. 2 through 4, which are essentially to scale, show the details of construction of vacuum motor assembly 26. More specifically, the vacuum motor has an outer housing 52, that includes a bell-like, hollow, left hand portion 53, and a donutshaped, right hand portion 54, the latter having a stepped diameter central opening 56. Axially between the two housing portions is a ring-like spark advance stop plate 58 contiguous to a ring-like spark retard stop plate 60. The latter has a stepped inner diameter 62 defining, with stop plate 58, an annular groove 64. Projecting into and axially movable within groove 64 is the bent edge 66 of a washer-like diaphragm retainer 68. The latter retainer, together with a cup-shaped apertured retainer 70, is clamped to an annular flexible diaphragm 72 having a central aperture 74. The diaphragm extends across the hollow interior of the housing and is sealingly mounted at its outer edge between stop plate 60 and the flange on housing portion 54.

A spring 78 normally biases the diaphragm 72 to the position shown locating flange edge 66 against the face of advance stop plate 58. The diaphragm, together with the walls of houspassage 30 to the engine intake ing portion 54, defines a fluid or vacuum chamber 80. Chamber 80 is connected to intake manifold vacuum hose 38, as best seen in FIG. 4.

A second flexible annular diaphragm 82 is sealingly mounted between housing portions 53 and stop plate 58, and extends across the housing to define with it a fluid or vacuum chamber 84. Chamber 84, as best seen in FIG. 3, is connected to hose 42, leading to shuttle valve 44 in FIG. 1. The two housing portions and stop plates and diaphragms are fixedly secured together by means of an annular cap plate 85.

Distributor advance plate actuating rod 24 is fixedly secured to what will be termed primary diaphragm 82 by means of two cup-

shaped plates

86 and 88 so that movement of the diaphragm in either direction will cause a corresponding movement of the distributor advance plate 12 (FIG. 1). The radially outermost bent edge 90 of plate 88 at times is adapted to abut the inner edge of what will be termed the secondary diaphragm stop plate 68 to limit movement of the primary diaphragm in one direction, for a purpose to be described later. A spring 92 normally biases the primary diaphragm 82 and rod 24 to the right to seat or abut edge 90 against plate 68.

The forces of secondary chamber spring 78 is chosen to be greater than that of spring 92 so that, all other conditions being equal, the secondary stop member 66 is positioned against the face of the advance plate 58, as shown.

The invention will be more fully understood by reference to FIGS. 5 through 8 illustrating, progressively, the various modes of operation. FIG. 5 illustrates the operation when the internal combustion engine either is off and ready to start, or operating at wide open throttle conditions. Taking first the engine off or starting conditions of operation, and referring also to FIG. 1; with the engine off, there is no airflow through the carburetor into the intake manifold, and the pressure level at both ports 46 and 40 and in both

hoses

42 and 38 is atmospheric. Thus, atmospheric pressure forces acting on

diaphragms

72 and 82 permit secondary diaphragm spring 78 to seat stop flange 68 against the face of advance plate 58, the primary advance spring 92 seating primary diaphragm 82 as shown with the flange edge 90 against stop flange 68. Actuating rod 24, therefore, is positioned at this time to provide the spark timing desired for starting of the engine.

It will also be seen that the position shown in FIG. 5 corresponds to wide open throttle operating conditions. That is, at wide open throttle, intake manifold vacuum is essentially at atmospheric pressure. Also, throttle valve 34 is rotated wide open and port 46, therefore, also is essentially at atmospheric pressure; therefore, the same pressure conditions exist in the primary and

secondary diaphragm chambers

84 and 80 as at engine starting, and actuating rod 24 remains in the same position shown and described.

Assume now that the engine has been started, and throttle pedal 34 is in the closed position shown in FIG. 1, for idle speed operation. Referring to FIG. 6, intake manifold vacuum at this time is high and reflected in the hose 38 (FIG. 4) to secondary diaphragm chamber 80. The manifold vacuum is sufficient at this time to overcome the force of spring 78 and pull diaphragm 72 to the right until the stop 66 abuts the face of retard stop plate 60. Simultaneously, the intake manifold vacuum being below the level sufficient to actuate decel valve 44, and carburetor spark port 46 being essentially at atmospheric pressure, atmospheric pressure is applied through hose or line 42 to primary diaphragm 82 to move it to the right until it is stopped by abutment against the secondary diaphragm stop 68. Thus, actuating rod 24 will have been moved to the maximum retard position shown.

FIG. 7 illustrates the positions of the parts during part throttle engine operation. More specifically, when the throttle lever 34 in FIG. I is rotated counterclockwise past port 46 to provide acceleration of the engine, the intake manifold vacuum then acts through port 46 and line 42 and chamber 84 to pull primary diaphragm 82 to the left to the position indicated in FIG. 7. The exact position of the diaphragm, of course, will depend upon the position of the throttle lever. In this position, the distributor advance plate actuating rod 24 has been moved to the left to advance the timing progressively, in the normal manner. Simultaneously, the intake manifold vacuum acting in the secondary diaphragm chamber has decreased sufi'- ciently to permit spring 78 to move secondary diaphragm 72 to the left of the position indicated, that is, the advance position moving stop member 66 against the face of advance plate 58. Thus, under these circumstances, the primary diaphragm has moved independently of secondary diaphragm 72 to provide ignition timing adjustment in a normal manner. FIG. 8 illustrates the positions of the parts during an engine decelerating operating condition. At this time, the intake manifold vacuum increases to a level where decel valve 44 is actuated to cause manifold vacuum to be directed to primary diaphragm chamber 84 instead of carburetor spark port pressure or vacuum. Therefore, at this time, a high intake manifold vacuum will pull primary diaphragm 82 to the left to the position indicated in FIG. 8, and move the advance plate actuating rod 24 to advance the timing an amount dependent upon the level of the intake manifold vacuum. Simultaneously, high intake manifold vacuum acting in the secondary diaphragm chamber 80 maintains the secondary diaphragm stop flange 66 against the retard face of plate 60, as shown. Again the movement of the primary diaphragm is made independent of the movement of the secondary diaphragm.

From the foregoing, it will be seen that the invention provides a vacuum motor assembly or construction that pennits independent mounting of the two diaphragms in a common housing for independent movement at times with respect to each other while at other times providing a limited movement of one relative to the other.

While the invention has been shown and described in its preferred embodiment in the drawings, it will be clear to those skilled in the arts to which it pertains that many modifications and changes may be made thereto without departing from the scope of the invention.

I claim:

1. A fluid motor assembly comprising, a housing, a pair of flexible diaphragm members each mounted in said housing for an independent movement relative to the other and each with said housing defining a different vacuum chamber, means connecting each of said chambers to a separate source of fluid varying from a maximum essentially atmospheric pressure level to a minimum sub-atmospheric pressure or vacuum level for reciprocable movement of each of said members as a function of the changes in vacuum acting thereon, spring means biasing each of said diaphragm members towards the other, movable actuating means connected to one of said diaphragm members for movement therewith, and means on said one member of the said pair of diaphragm members engageable at times with the other of said members upon movement of said one member in one direction for limiting the movement of said one member in said one direction in a variable manner as a function of the position of said other of said members.

2. A fluid motor assembly as in claim 1, including a stop means in the path of movement of one of said pair of members providing a limited movement of said latter one diaphragm member.

3. A fluid motor assembly as in claim 1, said members being coaxially mounted and axially spaced from each other for independent axial movement at times of each of said members.

4. A fluid motor assembly as in claim 1, said spring means each having a preload of a different value.

5. A fluid motor assembly as in claim 2, including first means secured to said other of said pair of members for movement therewith, said stop means being secured to said housing and projecting into the path of movement of said first means on opposite sides thereof.

6. A fluid motor assembly as in claim 3, including first means secured to the said other of said members for axial movement therewith, said stop means being secured to said housing and projecting into the path of movement of the said first means on opposite axial sides thereof providing a limited axial movement of the said other of said members.

7. A fluid motor assembly as in claim 2, said other member including a disk with a central aperture, said one member including a disk, said actuating means being connected to a central portion of said latter one disk and movably projecting through the aperture of said other member disk.

8. A fluid motor assembly comprising, a hollow annular housing, first and second flexible diaphragm members coaxially mounted in and each extending across said housing for axial reciprocable movement and each together with said housing defining a separate fluid chamber, means connecting a separate source of fluid under pressure to each of said chambers to act on the diaphragm member associated therewith, said sources each varying in pressure from a maximum essentially atmospheric pressure level to a minimum sub-atmospheric pressure or vacuum level for movement of each of said diaphragm members as a function of the changes in pressure level in said chambers, spring means biasing each of said diaphragm members towards the other, said spring means having different force values relative to each other, said first diaphragm member including a centrally apertured disk, said second diaphragm member having movable means to be actuated secured thereto and projecting axially through the aperture of said first disk for axial movement relative to said first disk, said first disk having radial flange means secured thereto, annular stop means secured to said housing and projecting radially inwardly and straddling said flange means with axial clearance therebetween permitting limited axial movement of said first member in opposite directions, and stop flange means secured to said second disk and abuttable at times with the flange means on said first disk for limiting at times the movement of said second disk in one direction of movement, said limiting movement in said one direction varying as a function of the position of said first disk.