Temperature responsive accelerating pump for an internal combustion engine carburetor
United States Patent 3911062
An accelerating pump fuel system for an internal combustion engine carburetor. The pump component can be actuated by either a mechanical linkage actuated by a throttle lever or a vacuum motor responsive to intake manifold vacuum. A temperature responsive valve is positioned within the vacuum line between the vacuum motor and the source of intake manifold vacuum and blocks the signal to the vacuum motor at temperatures above a predetermined magnitude. Thus, under warm conditions only the mechanical linkage is responsive to the vehicle acceleration, whereas under cold conditions both the vacuum motor and the mechanical linkage are responsive to vehicle acceleration. By specifically designing the vacuum motor stroke to be longer than the mechanical linkage stroke, the accelerating pump is made to discharge a greater quantity of fuel at cold temperatures and a lesser quantity of fuel at warm temperatures. The temperature sensed by the temperature responsive valve may be engine compartment ambient temperature, intake air temperature, engine coolant temperature, or the like.
US Patent References:
Carburetor accelerating pump
Weber - � 1944 - 2355346
Two-fuel carburetor
Moseley - 1952 - 2621029
Temperature sensitive pump
Kinney et al. - 1959 - 2877996
/2899950.html
Dermond - 1959 - 2899950
Temperature responsive accelerator pump
Winkley et al. - 1967 - 3313531
Carburetor accelerating pump
Weber - � 1944 - 2355346
Two-fuel carburetor
Moseley - 1952 - 2621029
Temperature sensitive pump
Kinney et al. - 1959 - 2877996
/2899950.html
Dermond - 1959 - 2899950
Temperature responsive accelerator pump
Winkley et al. - 1967 - 3313531
Application Number:
05/491596
Publication Date:
10/07/1975
Filing Date:
08/05/1974
View Patent Images:
Export Citation:
Assignee:
Ford Motor Company (Dearborn, MI)
Primary Class:
International Classes:
F02M7/087; F02M7/00; F02M7/08
Field of Search:
261/34A,34B
US Patent References:
Primary Examiner:
Miles, Tim R.
Assistant Examiner:
Clements, Gregory N.
Attorney, Agent or Firm:
Erickson, Roger Zerschling Keith E. L.
Claims:
I claim
1. An accelerating pump fuel supply system for an internal combustion engine carburetor, said carburetor including a source of intake manifold vacuum, an induction passage, a throttle lever and an accelerating pump,
2. A fuel supply system according to claim 1,
3. A fuel supply system according to claim 1,
4. An accelerating pump fuel supply system for the carburetor of an internal combustion engine, said carburetor including a source of intake manifold vacuum, an induction passage, a throttle lever and an accelerating pump,
5. A fuel supply system according to claim 4,
6. A fuel supply system according to claim 4,
7. A fuel supply system according to claim 4,
8. A fuel supply system according to claim 4,
9. A fuel supply system according to claim 4,
1. An accelerating pump fuel supply system for an internal combustion engine carburetor, said carburetor including a source of intake manifold vacuum, an induction passage, a throttle lever and an accelerating pump,
2. A fuel supply system according to claim 1,
3. A fuel supply system according to claim 1,
4. An accelerating pump fuel supply system for the carburetor of an internal combustion engine, said carburetor including a source of intake manifold vacuum, an induction passage, a throttle lever and an accelerating pump,
5. A fuel supply system according to claim 4,
6. A fuel supply system according to claim 4,
7. A fuel supply system according to claim 4,
8. A fuel supply system according to claim 4,
9. A fuel supply system according to claim 4,
Description:
BACKGROUND AND SUMMARY OF THE INVENTION
In conventional carburetors the accelerating pump is often a mechanical device to supply extra fuel to the induction passage simultaneously with the opening of the throttle plate during a vehicle acceleration. It is recognized that an engine needs a greater amount of fuel to be delivered by the accelerator pump under cold engine or ambient temperatures than under warm engine or ambient temperatures. Furthermore, it is known in the art to vary the output of an accelerator pump as a function of engine temperature. See, for example, U.S. Pat. No. 1,981,969 granted on Nov. 27, 1934 to A. M. Prentiss.
This invention provides improved control apparatus for the accelerating pump of an internal combustion engine carburetor that reduces the length of the stroke of the accelerating pump when the temperature sensed by an element of the control apparatus exceeds a predetermined magnitude. The invention also provides apparatus in which the sensed temperature may be that of the intake air, the engine compartment ambient, engine coolant, or the like. In addition, the invention provides temperature responsive accelerating pump apparatus which can be used with existing carburetor structures without significant modification to basic carburetor structure and which is generally external to the main body portion of the carburetor. Finally, this invention provides accelerating pump fuel system which is economical to produce and install and which is reliable in service.
An accelerating fuel pump supply system for an internal combustion engine carburetor constructed in accordance with this invention includes a pump mechanism having a movable element which when displaced effects a discharge from the pump into the induction passage of the carburetor. The quantity of fuel discharged from the pump is variable in direct relation to the magnitude of displacement of the movable element of the pump. The movable element may be displaced either by a linkage connected to a throttle lever or by a vacuum motor.
The vacuum motor is responsive to changes in intake manifold vacuum and is connected by a vacuum passage to a source of intake manifold vacuum. A temperature responsive valve is positioned in the vacuum passage and opens and closes the passage in response to changes in temperature. The vacuum motor is designed to displace the movable element of the accelerating pump a greater distance than the maximum stroke resulting from actuation of connecting the throttle lever linkage. The temperature responsive valve opens when the sensed temperatures are below a predetermined temperature and closed above the predetermined temperature; thus, the accelerating pump discharge is in response to displacement of the throttle lever linkage when temperatures are above the predetermined magnitude and in response to the vacuum motor displacement when temperatures are below the predetermined magnitude. Because the stroke of the vacuum motor is greater than that of the throttle lever linkage, a proportionately greater quantity of fuel is discharged to the induction passage of the carburetor when the sensed temperature is below the predetermined magnitude than when it is above the predetermined magnitude.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 of the drawings is a side elevational view of a carburetor incorporating the invention.
FIG. 2 is a vertical cross sectional view of the accelerator pump and the vacuum motor portion of the system taken along line 2--2 of FIG. 3.
FIG. 3 is a top view of the portion of the carburetor shown in FIG. 2.
FIGS. 4 and 5 are cross sectional views of the thermostatic valve member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Carburetor 11 includes a main body or housing 12 having an induction passage 13 and a fuel bowl 14 formed therein. An accelerating pump assembly 16 is located adjacent the fuel bowl. A throttle lever assembly 17 includes a first lever 18 secured to throttle shaft 19 and a second lever 21 pivotally mounted on shaft 19 and resiliently biased into abutting engagement with lever 18 at point 22. The two levers move as a unit until the second lever 21 engages an abutment 23 on the main body 12. At this time, the second lever 21 remains fixed relative to the carburetor body while further opening movement of the first lever 18 results in torsional windup of spring 24.
The accelerator pump assembly 16 is a conventional diaphragm pump mechanism and includes a variable volume chamber 27 having one wall formed by a flexible diaphragm element 28. A discharge passage 29 formed in the main body of the carburetor joins the variable volume chamber 27 and the induction passage 13. The accelerator pump 16 includes a fuel inlet passage 31 closed by a resilient umbrella-type check valve 32 and a second relatively small diameter passage 33 that permits vapors to dissipate from chamber 27.
A vacuum motor 34 is positioned adjacent the accelerator pump 16 and includes a flexible diaphragm 36 defining a vacuum chamber 37 and an atmospheric chamber 38. A plunger 39 connects the diaphragm 28 of the accelerator pump to the diaphragm 36 of the vacuum motor. The plunger 39 and the atmospheric pressure sides of the accelerator pump 16 and the vacuum motor 34 are enclosed within a dumbbell-shaped housing 41. The housing is attached to the main carburetor body 12 and forms the mounting means for the vacuum motor 34.
Flexible diaphragm 28 of the accelerator pump is secured to one end of the plunger 39 by a pair of circular elements 42. A compression spring 40 acts between the main body 12 and element 42 to bias the plunger to the left as viewed in FIG. 2. Flexible diaphragm 36 of the vacuum motor is resiliently biased against the opposite, disc-shaped end 43 of the plunger by compression spring 44 and cup 46. The spring 44 is compressed between the plunger end 43 and the cover 47 of the vacuum motor. Spring 44 exerts a greater force on plunger 39 than spring 40, therefore when there is no vacuum present in chamber 37 the plunger 39 is displaced to its rightward most position. A passage 48 communicates the vacuum chamber 37 with a source of intake manifold vacuum.
The accelerator pump 16 includes an actuating lever 51 pivotally attached by pin 52 to the housing 41. Lever 51 is interconnected with throttle lever 21 by a link 53. The accelerating pump lever 51 extends horizontally through a slot 54 formed in the plunger 39. The lever 51 includes a bulging or protruding edge 56 that is engageable with the end 57 of the slot 54 so that counterclockwise displacement of the lever 51 about the pin 52 as viewed in FIG. 3 causes displacement of plunger 39 and flexible diaphragm 28 in a rightwardly direction which in turn effects a discharge of fuel through passage 29.
Positioned in the vacuum passage 48 between the source of intake manifold vacuum and the vacuum motor 34 is a temperature sensitive valve assembly 58 shown in the drawings as FIG. 4. The valve assembly includes a bimetal disc 59 which above a predetermined temperature sealingly seats against an O-ring 61 to block the vacuum line 48. As the temperature drops, the bimetal disc becomes concave and lifts itself from sealing engagement with the O-ring 61 to open the vacuum line 48. A compression spring 62 resiliently urges the periphery of the bimetal disc into engagement with abutments 63 of the valve housing 64. An umbrella-type resilient check valve element 66 is centrally mounted on the bimetal disc and permits a one-way passage of a pressure differential through openings 67 of the disc.
OPERATION
The accelerating pump fuel system described above is specifically designed so that a full stroke of the accelerating pump lever 51 displaces the pump diaphragm 28 a lesser amount than does a full stroke of the vacuum motor 34. The accelerating pump lever stroke is limited by abutment of the accelerator pump lever with housing 41 at point 68 or abutment of throttle lever 21 with the stop 23 on the carburetor housing. Under cold engine operating conditions, a valve assembly 58 is open and the vacuum chamber 37 of vacuum motor 34 is in full communication with the source of intake manifold vacuum. When a sudden acceleration occurs the throttle plates (not shown) of the carburetor open and the intake manifold vacuum decays. The decrease in the vacuum signal within the chamber 37 of the vacuum motor permits the compression spring 44 to move the plunger 39 rightwardly displacing the pump diaphragm 28 rightwardly and forcing a discharge of fuel through passage 29 into the induction passage 13 of the carburetor. The umbrella valve 32 prevents the return of fuel from chamber 27 to the fuel bowl 14. The stroke is complete when the element 42 abuts the surface 64 of the carburetor housing. Following the acceleration, the intake manifold vacuum is again restored displacing the plunger 39 leftwardly as viewed in FIG. 2. This leftward displacement of plunger 39 refills the accelerator pump chamber 27 through orifice 31.
When the temperature sensed by the bimetal disc 59 is above a predetermined magnitude, the disc is sealingly seated against the O-ring 61 and the intake manifold vacuum decay is not communicated to the chamber 37 of the vacuum motor 34. The plunger 39 is displaced rightwardly by movement of throttle lever 21, link 53 and accelerating pump lever 51. A maximum or wide open throttle acceleration results in a discharge of fuel through passage 29 of lesser quantity than that resulting from full stroke of vacuum motor 34 because movement of accelerating pump lever 51 or throttle lever 21 is limited by abutments 68 or 23, respectively, which stops the plunger 39 before the elements 42 of the pump engage surface 69.
Modifications and alterations will occur to those skilled in the art which are included within the scope of the following claims.
In conventional carburetors the accelerating pump is often a mechanical device to supply extra fuel to the induction passage simultaneously with the opening of the throttle plate during a vehicle acceleration. It is recognized that an engine needs a greater amount of fuel to be delivered by the accelerator pump under cold engine or ambient temperatures than under warm engine or ambient temperatures. Furthermore, it is known in the art to vary the output of an accelerator pump as a function of engine temperature. See, for example, U.S. Pat. No. 1,981,969 granted on Nov. 27, 1934 to A. M. Prentiss.
This invention provides improved control apparatus for the accelerating pump of an internal combustion engine carburetor that reduces the length of the stroke of the accelerating pump when the temperature sensed by an element of the control apparatus exceeds a predetermined magnitude. The invention also provides apparatus in which the sensed temperature may be that of the intake air, the engine compartment ambient, engine coolant, or the like. In addition, the invention provides temperature responsive accelerating pump apparatus which can be used with existing carburetor structures without significant modification to basic carburetor structure and which is generally external to the main body portion of the carburetor. Finally, this invention provides accelerating pump fuel system which is economical to produce and install and which is reliable in service.
An accelerating fuel pump supply system for an internal combustion engine carburetor constructed in accordance with this invention includes a pump mechanism having a movable element which when displaced effects a discharge from the pump into the induction passage of the carburetor. The quantity of fuel discharged from the pump is variable in direct relation to the magnitude of displacement of the movable element of the pump. The movable element may be displaced either by a linkage connected to a throttle lever or by a vacuum motor.
The vacuum motor is responsive to changes in intake manifold vacuum and is connected by a vacuum passage to a source of intake manifold vacuum. A temperature responsive valve is positioned in the vacuum passage and opens and closes the passage in response to changes in temperature. The vacuum motor is designed to displace the movable element of the accelerating pump a greater distance than the maximum stroke resulting from actuation of connecting the throttle lever linkage. The temperature responsive valve opens when the sensed temperatures are below a predetermined temperature and closed above the predetermined temperature; thus, the accelerating pump discharge is in response to displacement of the throttle lever linkage when temperatures are above the predetermined magnitude and in response to the vacuum motor displacement when temperatures are below the predetermined magnitude. Because the stroke of the vacuum motor is greater than that of the throttle lever linkage, a proportionately greater quantity of fuel is discharged to the induction passage of the carburetor when the sensed temperature is below the predetermined magnitude than when it is above the predetermined magnitude.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 of the drawings is a side elevational view of a carburetor incorporating the invention.
FIG. 2 is a vertical cross sectional view of the accelerator pump and the vacuum motor portion of the system taken along line 2--2 of FIG. 3.
FIG. 3 is a top view of the portion of the carburetor shown in FIG. 2.
FIGS. 4 and 5 are cross sectional views of the thermostatic valve member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Carburetor 11 includes a main body or housing 12 having an induction passage 13 and a fuel bowl 14 formed therein. An accelerating pump assembly 16 is located adjacent the fuel bowl. A throttle lever assembly 17 includes a first lever 18 secured to throttle shaft 19 and a second lever 21 pivotally mounted on shaft 19 and resiliently biased into abutting engagement with lever 18 at point 22. The two levers move as a unit until the second lever 21 engages an abutment 23 on the main body 12. At this time, the second lever 21 remains fixed relative to the carburetor body while further opening movement of the first lever 18 results in torsional windup of spring 24.
The accelerator pump assembly 16 is a conventional diaphragm pump mechanism and includes a variable volume chamber 27 having one wall formed by a flexible diaphragm element 28. A discharge passage 29 formed in the main body of the carburetor joins the variable volume chamber 27 and the induction passage 13. The accelerator pump 16 includes a fuel inlet passage 31 closed by a resilient umbrella-type check valve 32 and a second relatively small diameter passage 33 that permits vapors to dissipate from chamber 27.
A vacuum motor 34 is positioned adjacent the accelerator pump 16 and includes a flexible diaphragm 36 defining a vacuum chamber 37 and an atmospheric chamber 38. A plunger 39 connects the diaphragm 28 of the accelerator pump to the diaphragm 36 of the vacuum motor. The plunger 39 and the atmospheric pressure sides of the accelerator pump 16 and the vacuum motor 34 are enclosed within a dumbbell-shaped housing 41. The housing is attached to the main carburetor body 12 and forms the mounting means for the vacuum motor 34.
Flexible diaphragm 28 of the accelerator pump is secured to one end of the plunger 39 by a pair of circular elements 42. A compression spring 40 acts between the main body 12 and element 42 to bias the plunger to the left as viewed in FIG. 2. Flexible diaphragm 36 of the vacuum motor is resiliently biased against the opposite, disc-shaped end 43 of the plunger by compression spring 44 and cup 46. The spring 44 is compressed between the plunger end 43 and the cover 47 of the vacuum motor. Spring 44 exerts a greater force on plunger 39 than spring 40, therefore when there is no vacuum present in chamber 37 the plunger 39 is displaced to its rightward most position. A passage 48 communicates the vacuum chamber 37 with a source of intake manifold vacuum.
The accelerator pump 16 includes an actuating lever 51 pivotally attached by pin 52 to the housing 41. Lever 51 is interconnected with throttle lever 21 by a link 53. The accelerating pump lever 51 extends horizontally through a slot 54 formed in the plunger 39. The lever 51 includes a bulging or protruding edge 56 that is engageable with the end 57 of the slot 54 so that counterclockwise displacement of the lever 51 about the pin 52 as viewed in FIG. 3 causes displacement of plunger 39 and flexible diaphragm 28 in a rightwardly direction which in turn effects a discharge of fuel through passage 29.
Positioned in the vacuum passage 48 between the source of intake manifold vacuum and the vacuum motor 34 is a temperature sensitive valve assembly 58 shown in the drawings as FIG. 4. The valve assembly includes a bimetal disc 59 which above a predetermined temperature sealingly seats against an O-ring 61 to block the vacuum line 48. As the temperature drops, the bimetal disc becomes concave and lifts itself from sealing engagement with the O-ring 61 to open the vacuum line 48. A compression spring 62 resiliently urges the periphery of the bimetal disc into engagement with abutments 63 of the valve housing 64. An umbrella-type resilient check valve element 66 is centrally mounted on the bimetal disc and permits a one-way passage of a pressure differential through openings 67 of the disc.
OPERATION
The accelerating pump fuel system described above is specifically designed so that a full stroke of the accelerating pump lever 51 displaces the pump diaphragm 28 a lesser amount than does a full stroke of the vacuum motor 34. The accelerating pump lever stroke is limited by abutment of the accelerator pump lever with housing 41 at point 68 or abutment of throttle lever 21 with the stop 23 on the carburetor housing. Under cold engine operating conditions, a valve assembly 58 is open and the vacuum chamber 37 of vacuum motor 34 is in full communication with the source of intake manifold vacuum. When a sudden acceleration occurs the throttle plates (not shown) of the carburetor open and the intake manifold vacuum decays. The decrease in the vacuum signal within the chamber 37 of the vacuum motor permits the compression spring 44 to move the plunger 39 rightwardly displacing the pump diaphragm 28 rightwardly and forcing a discharge of fuel through passage 29 into the induction passage 13 of the carburetor. The umbrella valve 32 prevents the return of fuel from chamber 27 to the fuel bowl 14. The stroke is complete when the element 42 abuts the surface 64 of the carburetor housing. Following the acceleration, the intake manifold vacuum is again restored displacing the plunger 39 leftwardly as viewed in FIG. 2. This leftward displacement of plunger 39 refills the accelerator pump chamber 27 through orifice 31.
When the temperature sensed by the bimetal disc 59 is above a predetermined magnitude, the disc is sealingly seated against the O-ring 61 and the intake manifold vacuum decay is not communicated to the chamber 37 of the vacuum motor 34. The plunger 39 is displaced rightwardly by movement of throttle lever 21, link 53 and accelerating pump lever 51. A maximum or wide open throttle acceleration results in a discharge of fuel through passage 29 of lesser quantity than that resulting from full stroke of vacuum motor 34 because movement of accelerating pump lever 51 or throttle lever 21 is limited by abutments 68 or 23, respectively, which stops the plunger 39 before the elements 42 of the pump engage surface 69.
Modifications and alterations will occur to those skilled in the art which are included within the scope of the following claims.