US3678909A

US3678909A - Exhaust gas recirculation control mechanism

Info

Publication number: US3678909A
Application number: US100112A
Authority: US
Inventors: Thomas D Barker; William K Ojala
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1970-12-21
Filing date: 1970-12-21
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25
Also published as: GB1311397A; JPS558665B1; CA950295A; DE2156986A1; SE369541B

Abstract

A lever is mounted pivotally on a spacer located between the carburetor and the intake manifold of a reciprocating internal combustion engine and a cam is mounted pivotally on the lever. The cam positions a poppet-type valve that determines exhaust gas recirculation rate. A vacuum motor responding to intake manifold pressure acts on the lever to position the cam indirectly and carburetor throttle linkage is connected directly to the cam.

Description

United States Patent Barker et al.

1451 July 25, 1972 [54] EXHAUST GAS RECIRCULATION CONTROL MECHANISM [72] Inventors: Thomas D. Barker, Detroit; William K.

Ojala, Dearborn Hts, both of Mich.

[731 Assignee: Ford Motor Company, Dearborn, Mich.

{22] Filed: Dec. 21, 1970 211 Appl. No.1 100,112

[52] US. CL. ..l23/ll9 A, l23/ll9B [51] Int. Cl ..F02m 25/06 [58] FieldofSear-ch ..l23/ll9A [56] v References Cited UNITED STATES PATENTS 2,722,927 [1/1955 Cornelius ..123/l l9 A 2,969,800 l/l96l Skiruin et al ..l23/l 19 A 3,186,392 Gregoric ..l23/l 19 A 3,294,073 12/1966 Bressan ....l23/l 19 A 3,444,846 5/l969 Sarto et l 23/1 19 A 3,465,736 9/1969 Daigh et al.... ....l23/l 19 A 3,513,816 5/1970 Daigh ..l23/l 19 A Primary Examiner-Wendell E. Burns Attorney-John R. Faulkner and Glenn S. Arendsen 57] ABSTRACT A lever is mounted pivotally on a spacer located between the carburetor and the intake manifold of a reciprocating internal combustion engine and a cam is mounted pivotally on the' lever. The cam positions a poppet-type valve that determines exhaust gas recirculation rate. A vacuum motor responding to intake manifold pressure acts on the lever to position the cam indirectly and carburetor throttle linkage is connected directly to the cam.

18 Claims, 4 Drawing Figures Patented July 25, 1972 2 Shets-Sheet 1 INVENTORS 77/0/1016 0 BAR/(7? ryn/AM /1. OJ 1/) ATTORNEYS SUMMARY OFTHE INVENTION This invention relates to US. Pat. No. 3,621,825 to Ojala entitled Exhaust Gas Recirculation Control Valve.

Recirculating small quantities of the exhaust gases of reciprocating internal combustion engines significantly reduces the quantity of undesirable nitrogen oxides emitted to the atmosphere. Such recirculation seriously affects engine performance however, particularly during certain modes of engine operation. Several individual mechanisms previously have been used to control exhaust gas recirculation in a manner intended to maximize emission reductions and engine performance.

The mechanism of this invention controls exhaust gas recirculation during all phases of engine operation. A housing for the mechanism has a poppet valve mounted therein for controlling the flow of exhaust gases from the engine exhaust passages to the engine intake passages. A lever pivotally mounted to the housing has a cam pivotally mounted thereon with its cam surface positioned to contact the poppet valve and thereby determine poppet valve opening and closing. A vacuum motor responsive to an engine generatedpressure signal such as intake manifold pressure acts on the lever to move the cam surface toward and away from the poppet valve. The cam is connected directly to the carburetor throttle blade so throttle blade movement pivots the cam relative to the lever and combines with the vacuum motor to determine poppet valve opening and closing.

In a highly effective construction, a laterally extended spacer located between the carburetor or an air metering device and the engine intake manifold serves as the housing. The movable element of the vacuum motor is bifurcated into two legs, one contacting one side of the lever on one side of the lever pivot point and the other contacting the other side of the lever on the other side of the pivot point. Both full extension and full retraction of the movable element pivot the lever in the direction moving its cam end away from the poppet valve. Exhaust gas recirculation is diminished or eliminated during periods of high manifold pressure produced by engine starting, rapid acceleration, and high power demand and during periods of low manifold pressure such as engine idling and deceleration.

A removable cartridge fits in the spacer and contains the seat and guides for the poppet valve. The cartridge and poppet valve assembly can be removed easily from the spacer for cleaning and other maintenance. Recirculating exhaust gases are conducted to an annular space surrounding each induction passage opening in the spacer. The recirculating gases enter the induction passage through small openings located circumferentially around the induction passage opening to provide a uniform mixture of exhaust gases with the new fuel-air charge from the carburetor.

Gases from the engine crankcase can be mixed with the recirculating exhaust gases in the spacer assembly. A lockout tang associated with the temperature sensing element of the carburetor choke mechanism or a separate temperature sensing element can be included to prevent or diminish exhaust gas recirculation during low engine or ambient temperatures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic showing a spacer housing the mechanism of the invention, the carburetor, the intake and exhaust manifolds, and other pertinent components of a reciprocating internal combustion engine.

FIG. 2 is a plan view of the spacer for a two venturi induction system with part of the spacer housing removed to show details of the cam lever and poppet valve. FIG. 3 is a view of the lever taken along line 3-3 of FIG. 2 that shows the relationship to the lever of a lockout tang actuated by the temperature sensing element of the choke mechanism.

FIG. 4 is a sectional view of part of the spacer showing the poppet valve, its cartridge, and the chambers and passages for mixing exhaust gases with crankcase vapors and distributing the gases into the induction passages.

DETAILED DESCRIPTION Referring primarily to FIGS. 1 and 2, the spacer for the mechanism of this invention comprises a relatively thin plate 10 that is positioned between the carburetor 12 and the intake manifold 14 of a reciprocating internal combustion engine 16. Spacer 10 contains two

openings

18 and 20 that register with corresponding carburetor induction passages, one of which is designated in FIG. 1 by numeral 22, and with corresponding passages in intake manifold l4. The induction passages supply a fuel-air mixture to the combustion chambers of engine 16 in the conventional manner. A conventional exhaust manifold 24 conducts exhaust gases from the combustion chambers.

As shown primarily in FIG. 2, a portion of plate 10 is cut away at a location horizontally adjacent to

openings

18 and 20 to form an open area defined in part by a floor 26 integral with the rest of plate 10. A pivot pin 27 pivotally mounts a lever 28 to floor 26 and another pivot pin 29 pivotally mounts arm'34 to the left end of lever 28. Arm 34 has a cam 30 attached to its inner end and its outer end projects slightly beyond the upper edge of floor 28. A rod 36 connects the outer end of arm 34 to the carburetor throttle blade 38 (FIG. 1).

A vacuum motor 40 is attached to one side of floor 26 with the axis of its movable element 42 intersecting lever pivot pin 27. Movable element 42 bifurcates into two legs 44 and 46 with leg 44 positioned on the left side of pivot pin 27 and leg 46 extending beneath lever 28 on the right side of pivot pin 27 Leg 44 has an upstanding tab 48 that contacts the inner surface of lever 28 on the left side of pivot pin 27. In a similar manner, leg 46 has an upstanding tab 50 that contacts the outer surface of lever 28 on the right side of pivot pin 27.

An adjusting screw 51 threadably engages an upstanding wall 52 on the right side of floor 26 and bears against the outer surface of lever 28 on the right side of pivot pin 27. Screw 51 determines the maximum counterclockwise position of lever 28. A tension spring 53 has one end anchored to floor 26 to the left of vacuum motor 50 and its other end connected to a threaded rod 54 that threadably engages a downwardly extending tab 55 fastened to the outer surface of lever 28. A lock nut 56 threadably engages rod 54 and bears against the outer surface of tab 55.

Referring also to FIG. 3, a pivot member 57 supports an L- shaped tang 58 in a vertical plane just above the left end of lever 28. The pivot point of tang 58 is at the junction of its

legs

59 and 60 as shown in FIG. 3. Leg 59 extends downward toward lever 28 and has a latch portion 61 for engaging the inner surface of lever 28. Leg 60 extends outward and is connected to a rod 62 that connects with the temperature sensing mechanism of the automatic choke.

As shown in FIGS. 2 and 4, cam surface 31 of cam 30 is positioned adjacent the tip of a poppet type valve 66. Poppet valve 66 is mounted in a cylindrical cartridge member 68 that is positioned in a hole 70 drilled horizontally into plate 10 from the open area above floor 26. Cartridge member 68 has a wall spaced a short distance from the bottom of hole 70 and forming a chamber 73 therewith. A compression spring 71 seats on member 68 and acts on a retainer 72 to urge the head 75 of valve 66 onto its valve seat located in the wall.

Openings

74 and 76 in the sides of cartridge member 68 align with a passage 78 formed in plate 10 and communicating with annular spaces 80 and 82 surrounding

respective openings

18 and 20. Ring-

shaped inserts

84 and 86 define the inner surfaces of respective spaces 80 and 82. Small holes 88 extend radially through the inserts at spaced locations to connect annular spaces 80 and 82 with

respective openings

18 and 20.

Projecting tubes 90 and 92 (FIG. 2) communicate with chamber 73 and passage 78 respectively. A conduit 94 connects tube 90 with exhaust manifold 24 and another conduit 96 connects tube 92 with the crankcase of engine 16 (FIG. 1). A third conduit 98 connects vacuum motor 40 to intake manifold 14.

The mechanism operates in the following manner. Vacuum motor 40 pivots lever 28 fully clockwise when subjected to either high or low intake manifold pressures. When the engine is not operating, the relatively high pressure in the intake manifold pivots lever 28 to its fully clockwise position in FIG. 2 and thereby moves cam surface 31 away from the tip of poppet valve 66. The end of lever 28 thus has moved outward beyond latch portion 61 of tang 58 (this lever movement would be upward in the perspective of FIG. 3).

During cold starting conditions when the automatic choke is effective, the temperature sensing mechanism of the automatic choke pivots tang 58 in a counterclockwise direction in FIG. 3 so latch portion 61 engages the inner surface of lever 28 and thereby prevents the lever from moving the cam 30 into contact with valve 66. Regardless of intake manifold pressure or throttle position, the cam does not contact valve 66 so no exhaust gas recirculation occurs. When the engine has warmed sufficiently, the temperature sensing mechanism of the automatic choke pivots tang 58 clockwise to release lever 28. Cam surface 31 then contacts the tip of poppet valve 66.

The position of poppet valve 66 then is determined by the combined positions of lever 28 and cam 30 because intake manifold pressure acts through vacuum motor 40 to position lever 28 and throttle blade position acts through rod 36 and arm 34 to position cam 30. When valve 66 is depressed, exhaust gases from exhaust manifold 24 enter space 73, flow by the open valvehead 75, and enter passage 78. Passage 78 conducts the gases tospaces 80 and 82 from which the gases pass through holes 88 -to enter the induction passages. When cam surface 31 exerts relatively little force on valve 66, the valve modulates exhaust gas recirculation by reducing the opening of the valve head relative to its seat. Engine crankcase vapors can flow directly through passage 78 and

openings

74 and 76 to enter the induction passages. Conduit 94 can contain a supplemental valve mechanism to control crankcase vapors if desired.

The attitude of spring 53 and rod 54 relative to lever 28 determines the rate at which pressure changes sensed by vacuum motor 44 affect the position of valve 66. Moving tab 55 to the right in FIG. 2 results in a decreasing moment arm from lever pivot pin 27 to rod 54 as lever 28 pivots clockwise. The decreasing moment arm varies the rate at which pressure changessensed by vacuum motor 40 move cam 30 toward or away from valve 66. A similar effect can be achieved by moving the anchor of spring 53 to the left. The opposite effect can be achieved by moving the anchor of spring 53 to the right or shifting tab 55 to the left. Spring attitude relative to the lever also can be selected to produce a constant moment arm or a constant force regardless of lever position.

Any loss of the pressure signal for vacuum motor 40 pivots lever arm 28 fully clockwise and thus prevents exhaust gas recirculation. Additionally, seizure of valve 66 in its closed position does not prevent sticking of the throttle blade 38 since cam 30 remains free to pivot relative to lever 28.

The ported vacuum from the carburetor or the carburetor venturi vacuum can be used as the input signal to vacuum motor 40 in place of intake manifold pressure. Tang 58 can be positioned by a temperature sensing element separate from the automatic choke mechanism and the tang can be stepped to provide varying degrees of temperature lockout, some of which permit small amounts of exhaust gasrecirculation depending on the pressure signal supplied to the vacuum motor and the position of the throttle blade. The contour of cam surface 31 and the mechanical relationship of arm 34 and linkage 36 can be varied as desired to modify the effect of throttle blade position on exhaust gas recirculation. Similarly, the rate of vacuum motor 40, the mechanical relationship of its movable element 42 and the mechanical relationship of lever 28 can be varied as desired to modify the effect of the vacuum signal on recirculation. In systems where fuel metering is accomplished by fuel injection or some other mechanism that does not use a carburetor, the mechanism of this invention is used with equal effectiveness by locating it somewhere in the air induction system. Pivot member 57 can have one end offset from the other so actuation of the temperature sensing element swings tang 58 downward to engage the lever.

Thus the invention provides an integral exhaust gas recirculation control mechanism that is relatively inexpensive to build and maintain but provides excellent versatility in controlling recirculation as a function of a vacuum signal, throttle blade position and temperature. The mechanism is readily adaptable to changed recirculation requirements of an individual engine and to various engines having differing recirculation requirements.

We claim:

1. An exhaust gas recirculation control mechanism comprising a housing,

a poppet valve mounted in said housing for controlling the flow of exhaust gases,

a lever pivotally mounted in said housing,

a cam pivotally mounted on said lever and having a cam sur face for contacting said poppet valve to determine poppet valve opening and closing,

means for pivoting said lever to move said cam surface toward or away from said poppet valve, and

means for pivoting said cam relative to said lever to change the portion of the cam surface adjacent said poppet valve.

2. The mechanism of claim 1 in which the lever pivoting means is a vacuum motor having a movable element in contact with said lever, said movable element comprising a bifurcated member having one leg contacting one side of the lever on one side of the pivot point and the other leg contacting the other side of the lever on the other side of the pivot point so that both full extension and full retraction of the movable element pivots the lever in the same direction.

3. The mechanism of claim 2 in which the lever is pivotally mounted to the housing approximately on the axis of the movable element of the vacuum motor.

4. The mechanism of claim 3 comprising a cartridge member removably fitting in a hole in said housing, said cartridge member having a wall spaced from the bottom of said hole and defining a chamber therewith, said wall having a valve seat for said poppet valve.

5. The mechanism of claim 4 in which the housing comprises a passage intersecting the cartridge member and communicating with the interior of the cartridge member through an opening in the cartridge member, said poppet valve controlling communication between said chamber and the interior of the cartridge member.

6. The mechanism of claim 1 comprising a .cartridge member removably fitting in a hole in said housing, said cartridge member having a wall spaced from the bottom of said hole and defining a chamber therewith, said wall having a valve seat for said poppet valve.

7. The mechanism of claim 6 in which the housing comprises a passage intersecting the cartridge member and communicating with the interior of the cartridge member through an opening in the cartridge member, said poppet valve controlling communication between said chamber and the interior of the cartridge member.

8. In a reciprocating internal combustion engine having a combustion chamber, an exhaust conduit for conducting exhaust gases away from said combustion chamber, an air metering device having a throttle blade for metering air for said combustion chamber, and an intake conduit for conducting air to said combustion chamber, a spacer located between said air metering device and said intake conduit for metering and distributing recirculating exhaust gases comprising a spacer housing having an opening communicating with said air metering device and said intake conduit, a poppet valve mounted in said spacer housing, said poppet valve controlling the flow of exhaust gases from said exhaust conduit to said intake conduit,

a vacuum motor having an element movable by pressure changes,

a lever pivotally mounted to said spacer housing, said lever being in contact with the movable element of said vacuum motor,

a cam pivotally mounted to said lever and having a cam surface for contacting said poppet valve, and

linkage connecting said cam to said throttle blade so movement of said throttle blade pivots said cam, said cam moving toward or away from said poppet valve by pivotal movement of said lever, said cam pivoting relative to said lever to open and close said poppet valve by movement of said throttle blade when the cam is in contact with the poppet valve.

9. The engine of claim 8 in which the movable element of the vacuum motor is a bifurcated member having one leg contacting one side of said lever on one side of the lever pivot point and the other leg contacting the other side of the lever on the other side of the pivot point so that both full extension and full retraction of the movable element pivots the lever in the same direction.

10. The engine of claim 9 comprising a cartridge member removably fitting in a hole in said spacer housing, said cartridge member having a wall spaced from the bottom of said hole and defining a chamber therewith, said wall having a valve seat for said poppet valve, and conduit means connecting said engine exhaust conduit with said chamber.

11. The engine of claim 10 in which said spacer housing comprises a passage intersecting the cartridge member and communicating with the interior of the cartridge member through an opening in the cartridge member, said poppet valve controlling communication between said chamber and the interior of the cartridge member.

12. The engine of claim 11 in which the spacer housing comprises an annular space surrounding said opening of the spacer housing and a ring member defining the interior surface of the annular space, said passage communicating with said space, said ring member having a plurality of holes connecting said annular space with said opening of the spacer housing.

13. The engine of claim 12 comprising an engine crankcase and conduit means connecting said crankcase with said passage.

14. The engine of claim 13 comprising a tang means pivotally mounted to said spacer housing and a temperature sensing means connected to said tang means, said temperature sensing means actuating said tang means to contact said lever and move said cam away from said poppet valve.

15. The engine of claim 14 comprising spring. means anchored to said spacer housing and connected to said lever for urging said cam toward said poppet valve.

16. The engine of claim 8 comprising a cartridge member removably fitting in a hole in said spacer housing, said cartridge member having a wall spaced from the bottom of said hole and defining a chamber therewith, said wall having a valve seat for said poppet valve, and conduit means connecting said engine exhaust conduit with said chamber.

17. The engine of claim 8 comprising a tang means pivotally mounted to said spacer housing and a temperature sensing means connected to said tang means, said temperature sensing means actuating said tang means to contact said lever and move said cam away from said poppet valve.

18. The engine of claim 8 comprising spring means anchored to said spacer housing and connected to said lever for urging said cam toward said poppet valve.

Claims

1. An exhaust gas recirculation control mechanism comprising a housing, a poppet valve mounted in said housing for controlling the flow of exhaust gases, a lever pivotally mounted in said housing, a cam pivotally mounted on said lever and having a cam surface for contacting said poppet valve to determine poppet valve opening and closing, means for pivoting said lever to move said cam surface toward or away from said poppet valve, and means for pivoting said cam relative to said lever to change the portion of the cam surface adjacent said poppet valve.

6. The mechanism of claim 1 comprising a cartridge member removably fitting in a hole in said housing, said cartridge member having a wall spaced from the bottom of said hole and defining a chamber therewith, said wall having a valve seat for said poppet valve.

8. In a reciprocating internal combustion engine having a combustion chamber, an exhaust conduit for conducting exhaust gases away from said combustion chamber, an air metering device having a throttle blade for metering air for said combustion chamber, and an intake conduit for conducting air to said combustion chamber, a spacer located between said air metering device and said intake conduit for metering and distributing recirculating exhaust gases comprising a spacer housing having an opening communicating with said air metering device and said intake conduit, a poppet valve mounted in said spacer housing, said poppet valve controlling the flow of exhaust gases from said exhaust conduit to said intake conduit, a vacuum motor having an element movable by pressure changes, a lever pivotally mounted to said spacer housing, said lever being in contact with the movable element of said vacuum motor, a cam pivotally mounted to said lever and having a cam surface for contacting said poppet valve, and linkage connecting said cam to said throttle blade so movement of said throttle blade pivots said cam, said cam moving toward or away from said poppet valve by pivotal movement of said lever, said cam pivoting relative to said lever to open and close said poppet valve by movement of said throttle blade when the cam is in contact with the poppet valve.

15. The engine of claim 14 comprising spring means anchored to said spacer housing and connected to said lever for urging said cam toward said poppet valve.