CA1144438A

CA1144438A - Reciprocating motor with adjustable stroke

Info

Publication number: CA1144438A
Application number: CA000351587A
Authority: CA
Inventors: Benjamin C. Benjamin; Charles A. Detweiler
Original assignee: Schmelzer Corp
Current assignee: Schmelzer Corp
Priority date: 1979-07-30
Filing date: 1980-05-09
Publication date: 1983-04-12
Also published as: FR2462741A1; DE3028937A1; JPS5620741A

Abstract

ABSTRACT OF DISCLOSURE

A reciprocating vacuum break or vacuum control motor for carburetor controls in which the length of stroke of the motor may be selected automatically to offer one or the other of two different lengths of stroke.

Description

1144~38 This invention relates to vacu~ break devices or reciprocating vacuum motors for controlling carburetors on internal combustion engines, and more particularly to such devices in which the length of stroke can be controlled.
Vacuum break devices which are used with carburetor control devices are typically provided with an adjusting arrangement by which the length of stroke of the device can be set at the time that the engine receives its final tuneup during manufacture.
Usually, the vacuum break device operates at the same adjustment throughout the lifetime of the vehicle. It has been found, however, that when the vacuum break devices are adjusted, for some predetermined condition at the time the automobile is manufactured, that over a period of time the engine operating conditions change sufficiently so that the length of stroke of the vacuum break device should be readjust-ed to modify the choke control in order to avoid excessive and undesirable emissions. Usually, such an adjustment requires a slight lengthening of the stroke of the vacuum break device so that the carburetor choke valve is moved an additional few degrees of arc toward a more open position to make the air fuel mixture leaner. It is desirable that such an adjustment occurs automatically, and also that the adjustment be of some pre-determined amount to avoid errors such as those that might occur by making manual adjustments and which could result in excessive emissions.
With such devices which must operate to achieve their purpose infrequently, it is desirable that the arrangement can be operated to test its condition, and also that relatively 30 --movable parts are cycle~ frequently to insure that relatively movable parts will be operable at the time that their function is needed. _ -~

With this in mind, it is an object of the invention to provide a recipxocating vacuum break device or vacuum motor for carburetors of internal combustion engines in which the length of stroke can be automatically varied in response to a control signal.
Another object of the invention is to provide such a vacuum break device wherein relatively movable parts required to carry out a function relatively infrequently are moved relative to each other frequently during the course of usual operations so that they are freely movable relative to each other at the time that their function is required.
A vacuum motor or vacuum break device for carbure-tors is provided which operates in two stages and in which a housing has a pair of movable walls dividing the housing into a control chamber between the two walls and an actuating cham-ber to one side of the control chamber with the chambers being isolated from each other. ~n output member is connected to one of the movable walls and projects from the housing for connection through linkage to controls on a carburetor such as a choke valve so that the choke valve is moved in response to movement of the movable walls and housing. The movable walls are connected to each other to determine both their minimum and maximum spacing. Vacuum is supplied to the control cham-ber to determine the minimum spacing of the movable walls and the supply of vacuum to the actuating chamber causes movement of the movable walls as a unit with each other in either the maximum spaced or minimum spaced positions relative to each other. As a result the OUtpllt member and therefore the con-nected carburetor control are moved a minim~n distance when vacuum is supplied onl~ to the actuating chamber and are moved 3~

a maximum distance when vacuum is supplied to both the actuating chamber and the control chamber.
These and other objects of the invention will be apparent from the following description and from the drawings in which:
Figure 1 shows a vacuum control motor in relation to an engine manifold and a carburetor;
Figure 2 is a cross sectional view at an enlarged scale of the vacuum motor seen in Figure l;
Figure 3 is a cross sectional view ~imilar to Figure

2 showing another mode of operation; and-Figure 4 is a view similar to Figures 2 and 3 showing still another mode of operation of the motor.
Referring to the drawings, the vacuum break device embodying the invention is desiynated generally at 10 and is adapted to be supported relative to a carburetor 12 of an internal combustion engine. The vacuum break device 10 in-cludes a housing 16 from which a plunger assembly 18 pro~ects.
The plunger assembly 18 includes a slot 20 adapted to receive the end of a crank 22 connected through linkage 23 for moving a choke valve 24 from its normally closed position shown in the drawing to an open position.
The housing 16 of the vacuum break device 10 includes a front housing cover 26 and a rear housing cover 28 which are separated by an annular spacer ring 30. Preferably the front cover member 26 is stamped of metal and the center spacer ring 30 and rear cover 28 are molded of plastic material.
Disposed ~ithin the housing 16 is a forward diaphragm asse~bly 32 including a diaphra~n 34 and a rearward diaphragm assembly 36 including a diaphragm 38. The diaphragms 34 and 36

3~3 are clamped to opposed faces of the spacer ring 30 by the front and rear covers 26 and 28 which are held in assembled conditivn by a clamping ring 40 folded over the spacer ring 30 and the peripheral flanges of the covers 26 and 28. Diaphragm 34 and 38 divide the interior of the housing into a forward chamber 42, an intermediate chamber 44, and a rear chamber 46 which are isolated from each other.
The rear cover member 28 of the housing 16 has an axailly disposed adjusting screw 50 supported in the wall of the cover 28 of the vacuum break 10. The adjusting screw 50 is threaded in the rear cover 28 and is suppor-ted in complemen-tary threads so that a head 56 is available at the exterior of the housing 16 and an end 57 of the screw 54 is disposed within the chamber 46 in the interior of the housing 16 for engagement with the diaphragm assembly 36 upon movement -to the right as viewed in Figure 1.
The forward diaphragm assembly 32 includes opposed backing plates 58 and 60 which are disposed at opposite sides of the forward diaphragm 34 and are held together by a rivet portion 62 at one end of the output plunger 18. The rearward diaphragm assembly 36 includes backing plate~ 66 and 68 which are fused together by an adhesive or sonic welding or the like, to hold the backing plates 66 and 68 in fluid tight relationship with the diaphragm 38.
The diaphragm assembly 32 and 36 form moveable walls and are connected together for limited relative movement by means of a male connector 70 formed integrally with the backing plate 66 and a complementary female connector 72 having an annular fing 74 held in fixed position relati.ve to backing platc 60 and an annular groove indicated at 78. The male 11~4438 connector 70 is formed by a plurality of fingers 76 having notches 78 which recei~e an annular flange 80 of the female connector 72. The notches 78 and the annular lip or flange 80 are so dimensioned that a limitedamount of telescoping of con-nectors 70 and 72 is permitted to provi~e limited axial move-ment between the diaphragm assemblies 32 and 36.
A spring 82 is disposed between the annular ring 74 on the diaphragm 32 and the backing plate 66 on the diaphragm 36 to urge the diaphragm assemblies 32 and 36 apart from each other. A spring 84 also is disposed between the backing plate 68 and an interior wall of the cover member 28 to bias the diaphragm assembly 36 to the left as viewed in Figure 2.
The spring 84 is stronger than spring 82 so that both diaphragm assemblies are at their extreme left position under nonoperat-ing conditions.
Vacuum pressure is made available to the chamber 46by way of a vacuum inlet tube 86 formed in cover 28 and com-municating by way of a hose 88 with an intake manifold 89 indicated in Figure 1. Vacuum pressure also is made available to the intermediate chamber 44 by means of a ~acuum inlet tube 92 communicating through a tube 94 with the intake manifold 89.
A control valve 96 is disposed in the tube 94 for controlling communication from the vacuum pressure to the chamber 44. The forward chamber 42 is in continuous communication with the atmosphere by way of an opening 98 in the forward cover 26 through which the plunger assembly 18 pro~ects.
In the absence of vacuum pressure such as would occur when the internal combustion engine is not operating, all ; of the chambers 42, 44 and 46 are under atmospheric pressure, and the position of the diaphragm assemblies 32 and 36 is determined by springs 82 and 84. The diaphragm assembly 32 occupies the position seen in Figure 2 with the backing plate 58 against the internal wall of the housing cover 26. The diaphragm assemlby 36 will be positioned with backing plate 66 against flange 80 due to the action of the strong spring 84 which overcomes the spring 82.
When the internal combustion engine is started, a source of vacuum pressure is established in the manifold 89 and a differential pressure is created across the diaphragm assemb-ly 36 by the establishing of vacuum pressure in the ch;amber 46.
The differential pressure across the diaphragm assembly 36 resulting from the atmospheric pressure in the chamber 44 and the vacuum pressure in chamber 46 causes the diaphragm assembly 36 to move to the right. In the init.l:al portion of that move-ment, the diaphragm assembly 32 remains stationary and the annular flange 80 will move to the left end of the notches 78 to the position illustrated in Fiyure 3. During such initial movement, plunger 18 remains stationary. When the end of the notches 78 engage the annular flange 80, further movement of the diaphragm assembly 36 against the biasing action of the spring 84 is effective to pull the diaphragm assemlby 32 and the output plunger 18 to the right as viewed in Figure 3 until the backing plate 68 of the diaphragm assembly 36 comes into engagement with the end 57 of the adjusting screw 50. The total range of movement of the output member 18 is equal to the distance between the screw end 57 and the backing plate 68 as vlewed in Figure 2 reduced by the space of notch 78 occupied by flange 80.
During normal or initial operation of the control device 10, the control valve 96 can be maintained to isolate the chamber 44 from the intake manifold 89 and to maintain the ;3~

chamber 44 at atmospheriG pressure. The control valve 96 can be made to respond to various conditions such as temperature to cause the chamber 44 to be placed in communication with the source of vacuum or manifold 89 after some predetermined engine temperature is achieved. Also, if desired, -the valve 96 can be made to respond to the odometer drive of a vehicle so that it opens after a predetermined number of miles. The valve 96 alternatively can be made responsive to an engine hour meter so that the valve opens after some predetermined number of engine hours have been experienced.
After the engine has been opera-ted to achieve the control condition, valve 96 opens and vacuum pressure is made available not only in the chamber 46 but also in the chamber 44. Under such conditions the pressure in chambers 44 and 46 is equal but a pressure differential is created across the diaphragm assembly 32 due to atmospheric pressure in the chamber 42. Since -the starting position of the vacuum motor is with the annular flange 80 a-t the right end oF -the groove 78 the diaphragm assembly 32 and 36 to the righ-t until the backing plate 6B on diaphragm assembly 36 engages wi-th the end of the screw 50. At tha-t time, movement of the diaphragm assemblies 32 and 38 stops and the diaphragm assemblies remain at their minimum spacing, -that is with the annular flange 80 a-t the right end of the grooves 78 as viewed in Figure 4. Under these conditions of operation, -the output plunger 18 is moved an additional amount comparecL with its movement when vacuum pressure is made available only in the chamber 46. The addition-al amount of movement of the plunger 18 is equal -to the length of the notches 78 less the thickness of the annular flange 80, or the distance that flange 80 can travel in or the notches 78.
When operation of the engine is s-topped, vacuum pressure is no longer available at the intake manifold 89 and the chambers 44 and 46 return to atmospheric pressure permit-ting the return springs 82 and 84 to urge both of the diaphragm assemblies 32 and 36 to their e~treme left position as seen in Figure 2 at which they are at their minimum spacing. It will be understood that the amount of the increase in the length of stroke can be varied by cnanging the relative dimen-sions of either the flange 80 or the notches 78. In actual practice with a vacuum control d.evice 10 it was found useful to increase the length of stroke of the outpu-t member 18 by only a small amount sufficient to open the choke valve 24 an additional few degrees to make it possible to provide a leaner fuel air mi~ture. The change in adjustment can be obtained automatically in response to operation of the control valve 96.
From this it can be seen that -the control motor has one type of operation initially when vacuum is supplied only to the chamber 46 and still a different type of operation when vacuum is supplied -to both the chambers 44 and 46 after the control valve 96 has been actuated in response to some pre-determined condi-tion such as temperature, engine hours, or vehicle miles. Nevertheless, even in the early stages of operation when vacuum is not made available at the intermediate chamber 44, the various par-ts move relative to each other each time that the engine is started and stopped. In other words, tlle diaphragm assemblies 36 and 32 move relative to each other a small amount as de-termined by the amount of movement of the annular flange 80 in the notches 78. Also, both diaphragms ~149~38 move initially relative to each other and subsequently as a unit, and return to their original positions a~ter the engine has stopped. Similarly after the control valve 96 has been moved to its open position and vacuum is supplied to both of the chambers 44 and 46, the diaphragm assembly 32 and 36 initially move relative to each other and subsequently move as a unit to maintain their minimum spacing in which the annu-lar flange 80 is disposed at the right end of the notches 78 as viewed in Figure 2.
Although the length of stroke of the stem 82 of the plunger assembly 18 can be changed automatically after some predetermined time, it will be noted that it is possible for a mechanic to make any necessary adjustments by use of the adjust-ing device 50. The operation of the adjusting device 50 is available independently of whether or not the vacuum break 10 is operating in its initial phase or in its final phase.
A vacuum break 10 for carburetors of internal com-bustion engines has been provided having two modes of operation.
In the first mode the reciprocating vacuum break motor has a stroke of a given length for opening the choke of a carburetor some predetermined amount and in the second mode of operation which can be obtained after the engine has been operated some predetermined period of time, or achieves a predetermined tem-; perature, the vacuum break has another length of stroke which is longer so that the carburetor choke is moved to a more open position to obtain a leaner carburetor setting.

Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A fluid pressure motor comprising: a housing, a pair of moveable walls dividing said housing into a control chamber to one side of said control chamber, an output member having one end connected to one of said moveable walls within said housing, and having its opposite ends exterior of said housing, means connecting said moveable walls to each other for limited movement toward and away from each other between a first position in which said walls are at a minimum spacing relative to each other and a second position in which said walls are spaced apart, means biasing said walls to said first position, the other of said walls being moveable to said second position while said one of said walls and said output member remain stationary upon establishing vacuum pressure in said actuating chamber and subsequently said moveable wall members being moveable as a unit in said second position in the presence of vacuum pressure in said actuating chamber and absence of vacuum pressure in said control chamber to move said output member in a first predetermined range, said moveable wall members being moveable as a unit with each other in said first position in the presence of vacuum pressure simultaneously in both said actuating chamber and said control chamber to move said output member in a second predetermined range longer than said first stage.

2. The combination of claim 1 wherein said means connecting said moveable wall members comprises a pair of telescoping members connected respectively to said pair of wall members.

3. The combination of claim 2 wherein one of said telescoping members forms an annular flange and the other of said telescoping members forms a plurality of grooves, said annular flange being movealbe axially in said grooves.

4. The combination of claim 1 and further comprising a source of vacuum pressure, a first pressure port formed in said housing and placing said source of vacuum pressure in communication with said actuating chamber, a second pressure port communicating said control chamber with said source of vacuum pressure, and means closing communication between said source of pressure and said other chamber until vacuum pressure has been made available to said first pressure port for a pre-determined period of time.

5. The combination of claim 1 and further comprising adjusting means for limiting the amount of movement of said pair of moveable walls as a unit.

6. The combination of claim 5 wherein said means for limiting the amount of movement comprises a screw member longitudinally adjustable and disposed coaxially in the path of movement of one of said wall members.

7. The combination of claim 1 and further comprising first resilient means biasing one of said wall members in a direction in opposition to movement of said wall member in the presence of vacuum pressure in said actuating chamber and second biasing means disposed between said walls to urge said walls apart from each other.

8. The fluid pressure motor of claim 1 and further comprising a choke valve for a carburetor, said output member being connected to said choke valve for movement of the latter in said first predetermined range to a first opened position and in said second predetermined range to a second opened position larger than said first opened position, a pair of moveable walls dividing said housing into a control chamber between said walls and an actuating chamber to one side of said control chamber, said chambers being isolated in fluid tight relationship from each other, an output member connected to one of said moveable walls within said housing and having its opposite end exterior of said housing connected to said choke valve, means connecting said moveable members to each other for limited relative movement of said wall members between first and second spaced apart positions, said wall members being moveable as a unit in a maximum spaced apart relationship in the presence of vacuum pressure in said actuating chamber to move said choke valve to a first opened position, said walls being moveable as a unit with each other in a minimum spaced apart relationship in the presence of vacuum pressure in both said actuating chamber and said control chamber to move said choke valve to a second opened position greater than said first opened position.

9. The combination of claim 1 and further com-prising adjustable means engageable with one of said walls to determine said first opened position.