Exhaust And Gas Recirculating System

Wolgemuth September 17, 1

Patent Grant 3835827

U.S. patent number 3,835,827 [Application Number 05/327,280] was granted by the patent office on 1974-09-17 for exhaust and gas recirculating system. This patent grant is currently assigned to Ford Motor Company. Invention is credited to James H. Wolgemuth.


United States Patent 3,835,827
Wolgemuth September 17, 1974

EXHAUST AND GAS RECIRCULATING SYSTEM

Abstract

An exhaust gas recirculation system is disclosed employing a primary control valve having a vacuum operated servo mechanism for controlling the admission of recirculating gases. The servo mechanism is operated in response to a modulated vacuum signal derived principally from intake manifold vacuum. Modulation of the vacuum signal is achieved by three control means connected in series, one of which functions in response to a differential between carbureted venturi vacuum and the intake manifold vacuum, another control means operates to prevent communication of the vacuum signal to the servo mechanism during prolonged steady or nearly steady conditions of the engine, yet another control means is effective to prevent communication of the vacuum signal during wide-open throttle conditions of the engine carburetor.


Inventors: Wolgemuth; James H. (Warren, MI)
Assignee: Ford Motor Company (Dearborn, MI)
Family ID: 23275902
Appl. No.: 05/327,280
Filed: January 29, 1973

Current U.S. Class: 123/568.29
Current CPC Class: F02M 26/56 (20160201)
Current International Class: F02M 25/07 (20060101); F02m 025/06 ()
Field of Search: ;123/119A

References Cited [Referenced By]

U.S. Patent Documents
3739797 June 1973 Caldwell
Foreign Patent Documents
1,601,374 Apr 1970 DT
Primary Examiner: Burns; Wendell E.
Attorney, Agent or Firm: Malleck; Joseph W. Zerschling; Keith L.

Claims



I claim:

1. In an engine having an exhaust manifold, an intake system for inducting air and fuel through a metering venturi into an intake manifold of said engine, an apparatus for recirculating exhaust gases comprising:

a. a duct connecting said intake system and exhaust manifold,

b. valve means interposed in said duct having a first control element normally biased to a closed position and a servo mechanism operable to overcome said bias for variably opening said valve means, said servo mechanism being connected to vacuum from said intake system, and

c. first control means to modulate the connection of vacuum between said intake system and servo mechanism in accordance with pressure at said metering venturi, said first control means being movable in response to a differential pressure between intake manifold vacuum and venturi vacuum to modulate and limit the degree of intake system vacuum communicated to said servo mechanism, said first control means comprising a housing having a bore with stepped portions, a spool valve provided with differential lands slidable in respectively stepped portions of said bore, said bore having an inlet opening in communication with said servo mechanism and an outlet opening in communication with intake manifold vacuum, said outlet opening being arranged so as to be opened or closed by operable movement of said spool valve, the larger of said lands being subject to a force on one side thereof proportional to intake system air-flow vacuum tending to move said spool valve to an open position about said outlet opening and the other side of said larger land being subject to the intake manifold vacuum tending to urge said spool valve to a close position.

2. The apparatus as in claim 1, in which an accumulator is employed to maintain a predetermined level of intake manifold vacuum for introduction to said first control means during all conditions of operation except when said first control means is closed.

3. The apparatus as in claim 1, in which the smaller land is subjected to intake manifold vacuum urging said first control means to an open position and thereby maintaining a constant relationship between exhaust gas recirculation and intake system air-flow vacuum even during the closed position of said spool valve.

4. The apparatus as in claim 1, comprising in combination a third control means effective to prevent communication of said intake manifold vacuum with said servo mechanism during prolonged steady state cruising conditions of said engine.

5. The apparatus as in claim 1, in which said bias for said servo mechanism is calibrated to provide closure of said valve means at the highest vacuum encountered at wide-open throttle for said engine and said bias being adapted to meter a small amount of exhaust gas recirculation during throttle positions substantially adjacent to wide-open throttle.

6. The apparatus as in claim 1, in which there is further provided additional control means for controlling the communication of manifold intake vacuum to said servo mechanism, said additional control means being adapted to prevent communication of intake manifold vacuum to said servo mechanism during steady-state conditions of said carburetor air flow.

7. The apparatus as in claim 6, in which said additional control means comprises a housing having a bore with an inlet thereto in communication with said servo mechanism and an outlet thereof in communication with the inlet to said first control means, a valve element therein normally biased in a closed position preventing flow between said inlet and outlet and a land connecting with said element having opposite sides thereof normally subjected to intake manifold vacuum, and means for delaying the relief of intake manifold vacuum from either side of said land upon a change of intake manifold vacuum so that one side of said land will be effective to overcome said bias and open said second control means according to said predetermined delay.
Description



BACKGROUND OF THE INVENTION

Numerous systems have been devised to recycle exhaust gases into the air/fuel induction system of an automotive engine for a variety of purposes among which include:

A. use of the exhaust gases to prewarm and thereby vaporize the incoming air/fuel mixture to facilitate its complete combustion in the combustion zone,

B. recirculation of the exhaust gases to reuse unignited or partially burned portions of the fuel which would otherwise pass out into the exhaust pipe and into the atmosphere, and

C. recirculate exhaust gases for the purpose of reducing oxides of nitrogen emitted from the exhaust system and into the atmosphere. This is brought about by reducing the maximum combustion temperature in consequence of the dilution of the air/fuel mixture by the recycling of exhaust gases.

However, since the load and power demands of the engine change rather considerably over their normal operation, the above goals cannot be easily achieved if consideration is given to driveability and satisfactory engine performance. To this end, the invention is concerned with utilizing control signals which vary the volume and timing of exhaust gas recirculated in conformity with achieving more goals. It is known that the recycling of at least 5 percent and not more than 25 percent of the total exhaust gases through the engines, depending upon the load or power demand, will reduce the combustion temperature to less than 2,200.degree.F. But within this range, the amount recycled at any one moment must be tuned to a variety of engine conditions.

SUMMARY OF THE INVENTION

The primary object of this invention is to provide an exhaust gas recirculation system capable of introducing exhaust gases to the intake manifold system during periods when exhaust gas recirculation will not substantially hinder the normal power operation of the engine and in such modulated quantities that best suit the attainment of lower emissions. To this end, the invention contemplates the control or admission of exhaust gas recirculation in response to a vacuum signal, the signal being modulated primarily in proportion to carburetor venturi vacuum. On and off controls are additionally superimposed over this primary modulation by use of (a) a valve adapted to close on a delayed basis in response to a change in intake manifold vacuum and to remain closed during steady state manifold vacuum conditions, and (b) a valve is adapted to close when wide-open throttle conditions are substantially reached.

One or more combinations of the above controls provide a sensitive variation of exhaust gas recirculation more in tune with the multiple needs of the engine for top performance as well as the emissions criteria.

To provide a constant relationship between recirculation and carbureted air flow, an admitting valve may be contoured to provide a flow area through the throat of the admitting valve which is proportional to the one half power of the modulated vacuum signal; the modulated vacuum signal in turn may be related to venturi vacuum which increases at a rate equal to the second power of the air-flow through the carburetor.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a schematic illustration of the exhaust gas recirculation system used in conjunction with a typical internal combustion engine.

DETAILED DESCRIPTION

Referring now to FIG. 1, a preferred embodiment is illustrated comprising, broadly, an exhaust gas recirculation system adapted to operate with a typical engine having an intake system A and an exhaust manifold B, the intake system further comprising a carburetor having a typical air horn 9 provided with a metering venturi 10 for inducting fuel (not shown) in response to the vacuum created by said metering venturi. A throttle 8 is employed to conventionally control the flow of the fuel and air mixture passing into intake manifold 11 of the engine.

Exhaust gas recirculation is conveyed by a duct or passages C interconnecting the exhaust manifold with the intake manifold; primary valve means D is effective to control the admission of exhaust gases through said duct C. Valve means D is operated in response to a servo mechanism E which has a control element or diaphragm 23 normally biased in one direction to close valve means D and is subject to a modulated vacuum signal to overcome the effect of said bias for opening said valve means. Modulation of said vacuum signal is achieved through a series of control means H, G and F. Means H is effective to control the communication of intake manifold vacuum with the servo mechanism in response to a differential between intake system vacuum obtained at the metering venturi 10 and intake manifold vacuum. Control means F is effective to interrupt normal communication of the modulated vacuum signal to said servo mechanism in response to wide-open throttle conditions of said carburetor. Means G is effective to prevent communication of the modulated vacuum signal with said servo mechanism during prolonged steady state cruising conditions of the engine.

Turning now in more particularity to the components of the system, primary valve means D comprises a rigid valve housing 7 having a cylindrical bore or wall 17 subdivided therein longitudinally into chamber portions 18, 19, 26 and 27 by the respective interposition of flat walls 16, 22 and a diaphragm 23 (forming a control element), all extending transversely across the bore at spaced locations. The wall 16 has an opening 15 therein defining a valve seat; a valve element 14 is movable between opened and closed positions (shown in the semi-open position in FIG. 1) for said valve seat. The valve element 14 is carried by a valve stem 25 connected with said flexible diaphragm 23 for movement therewith. Inlet 21 chamber portion 18 provides for introducing exhaust gases via conduit 12 from said exhaust manifold; outlet 20 from chamber portion 19 is provided for communicating with the intake manifold 11 of said intake system by way of a conduit 13 connecting with a port 92 positioned below the carburetor throttle 8.

The servo-mechanism E utilizes a helical spring 24 to bias diaphragm 23 in a direction to bring valve element 14 to a closed position; spring 24 acts between the right hand side of wall 22 and the left hand side of diaphragm 23. A passage 29 is provided to communicate chamber portion 26 with the control vacuum signal conveyed from means F, G and H, means H communicating directly with the port 91 of the intake manifold immediately below the throttle of the carburetor. The opposite side of the diaphragm 23 is subjected to pressure in chamber portion 27 which is vented V to atmosphere by way of passage 28.

Control means H, as indicated, is adapted to provide modulation of intake manifold vacuum in accordance with a signal that rises and falls more closely with the conditions at which the engine can assimulate exhaust gas recirculation. For this purpose the vacuum generated at the primary venturi 10 of the carburetor is utilized; this signal is generally proportional to the second power of the air-flow rate through the air horn 9. When intake manifold vacuum will be generally high at low speeds of the engine, venturi vacuum will not be low; similarly at high engine speeds, intake manifold vacuum will be generally insignificant whereas venturi vacuum will be available. To employ the venturi vacuum signal, control means H has a housing 6 defining a valve chamber 73 having stepped cylindrical walls 73a, 73b and 73d; walls 73b and 73d are connected by a tapered wall 73c. A spool valve 74 is slidable in chamber 73 and has cylindrical land 77 (having diameter 78) slidable in intimate contact with the cylindrical wall 73a; land 75 (having diameter 79) is slidable in intimate contact with cylindrical wall 73b and diaphragm 86 is connected at the juncture of tapered wall 73c and wall 73d to define chamber portions 84 and 85. The lands 77 and 75 are spaced apart, by stem 76, a distance so that in the position as viewed in FIG. 1, inlet 95 and outlet 81 to chamber portion 80 are in communication.

Chamber portion 80 is defined by the lands 77 and 75; inlet 82 is connected to a reservoir 98 by passage 95, the reservoir in turn is in communication with intake manifold vacuum by way of conduit 65 leading to port 91. To insure sufficient vacuum for system operation at low intake manifold vacuum levels, an accumulator (in the form of reservoir 98) is utilized; a check valve 100 acting against seat 101 is employed to preserve the reservoir vacuum. Outlet 81 is ultimately in communication with the servo-mechanism E.

Chamber portion 85 (defined between the land 75 and the diaphragm 86) is in communication with atmosphere, identified as vent V, by way of passage 94. Chamber portion 84 (defined between the diaphragm 86 and the end of the chamber) has an inlet 88 in communication (by way of passage 89) with a port 90 entering into the venturi of the carburetor.

To obtain modulation of the vacuum signal passing through means H, a differential between intake manifold vacuum (acting on the inner surfaces of the spool valve) and venturi vacuum (acting on diaphragm 86) is employed. Initially, venturi vacuum from passage 89 will flex the diaphragm 86 to the right allowing the spool valve 74 to uncover inlet 82, thereby admitting the intake manifold vacuum to the chamber portion 80. Intake manifold vacuum operating against the differential faces of lands 77 and 75 will have a resultant force urging the spool valve to the left and closing inlet 82. Thus, the resultant intake manifold vacuum force will oppose that of the venturi vacuum operating on the diaphragm; the land areas are chosen so that the forces will be generally in equilibrium or nearly so at mid-range speed conditions for the engine. If engine conditions are such that the venturi vacuum will predominate over the intake manifold vacuum resultant, the spool valve will move further to the right, admitting a larger degree of intake manifold vacuum as the vacuum control signal. This may occur at higher speed conditions. Should the intake manifold vacuum differential predominate, such as at low speeds or idle, the opposite will occur and the valve 74 will be moved to restrict the inlet 82. When the spool 74 is moved sufficiently to substantially restrict or close the inlet 82, the vent V will be opened communicating with atmosphere by passage 96. The vent V cannot be uncovered by over movement of the spool valve to the left because of its attachment to the diaphragm; this prevents a leak to manifold vacuum. All vents, in the various control means, as well as in the primary valve means, are vented to the clean side of the engine air cleaner which is very slightly below atmospheric pressure.

The modulation by means H provides a type of amplification of a weak signal (venturi vacuum) to a relatively strong signal (intake manifold vacuum). At times it may be desirable to construct the apparatus to produce a constant relationship between exhaust gas recirculation and the carbureted air flow through the venturi 10. To accomplish the latter, intake manifold vacuum in chamber portion 80 (which is our control vacuum) will be modulated further by intake manifold in chamber portion 5 (this manifold vacuum, under most conditions will be slightly different from the control vacuum in chamber 80). To this end, a passage 97 communicates chamber portion 5 with port 91 of the carburetor. Thus at high manifold vacuum levels, the modulated control vacuum communicated to outlet 81 is reduced from the value which it would normally have at low manifold vacuum levels. This offsets the effect of the vacuum signal on the differential pressure across the primary valve D (namely, the pressure at inlet 21 minus the pressure at the outlet 20). Thus with high manifold vacuum, control vacuum will be somewhat lowered and the primary valve means D will not be open as far, thereby providing a smaller flow area to compensate for the higher vacuum at inlet 21.

Proceeding directly to the third control means G (skipping for the moment the second control means F) further modulation of the control vacuum signal is obtained in accordance with transient conditions of the engine. That is to say, the control vacuum will be admitted to permit exhaust gas recirculation during accelerations and short cruises when it is mot desirable to do so. Control means G comprises a housing 4 defining a valve chamber having stepped portions; a first cylindrical wall 47 (having a diameter 44) is interrupted by a smaller cylindrical wall 48 (having a diameter 45). An enlarged chamber 56 is defined at the right hand side of the chamber. A spool valve 41 with three lands 42, 43 and 53 is arranged to slidably reciprocate within the chamber portions; land 42 is adapted to slide in intimate relationship with the cylindrical wall 47, land 43 slides in intimate relationship with cylindrical wall 48, and the third land 53 (having a diameter similar to land 42) slides in intimate relationship with the right hand side of the cylindrical wall 47. The spacing between lands 42 and 43 is arranged to provide a chamber portion 3 and fluid communication between inlet 49 and outlet 50 when the lands are so positioned as in FIG. 1.

A compression spring 55 is positioned between the termination of the chamber of housing 4 and the right hand surface of land 53; spring 55 urges spool valve 41 in a leftward direction causing the edge of the land 43 to move across the edge 82 of inlet 49 and thereby close communication with the outlet. Similarly, the land 42 will uncover a vent allowing the space between the lands to be reduced to substantially atmospheric pressure. Chamber portions 58 and 56 (which are on opposite sides of land 53) are interconnected by parallel passages 62 and 63, both of which are commonly in communication with intake manifold vacuum via passage 66 and 65. Parallel passage 62 contains a check valve adapted to allow intake manifold vacuum to enter chamber portion 56; the ball element 60 of the check valve will be maintained away from valve seat 61 as the result of vacuum pressure. Parallel passage 63 contains a restriction 64 which acts as a delay mechanism in allowing the transient change in pressure between opposite sides of the restriction.

When intake manifold vacuum is constant, the communication to chamber portions 58 and 56 will impose equal forces on opposite sides of land 53; spring 55 can thus cause the valve 41 to substantially close. When intake manifold vacuum increases due to deceleration, both the chamber portion 56 and the chamber portion 58 will be further evacuated quickly (check valve 60 will be open) and the valve 41 will still continue to remain substantially closed. However, when manifold vacuum decreases due to an increase in engine acceleration, the check valve 60 will prevent flow from chamber portion 56 through passage 62. The higher pressure in chamber portion 58 will force the spool valve to the right uncovering the inlet 49. The spool valve will move slowly due to the restriction 64 with dampens fluid flow to or from chamber portion 56. When transient condition has expired, the valve 41 will be urged by spring 55 to the left to substantially close the inlet 49 and obtain equilibrium again. The time required to close the inlet 49 can be varied by changing the size of the chambers portions 58 and 56 or changing the size of the restrictor 64.

Another damper or delay mechanism can be built in at the left hand side of the valve means G by use of a vent passage 68 communicating with chamber portion 57. A parallel passage 67 is incorporated to also communicate chamber portion 57 with the vent V. In passage 67, a one way check valve is used, having a ball 70 adapted to seal against seat 71 when vacuum pressure is sufficiently low in chamber portion 57. A restrictor 69 is incorporated in passage 68 so as to delay flow therethrough. Thus, the time required to close inlet 49 can be additionally extended; when there is a transient change of conditions urging the spool valve 41 to the right or left, the restrictors 69 and 64, and ball check valves 70 and 60 will cooperate.

The control vacuum signal delivered from the means G intended for the servo-mechanism E can be further controlled by second control means F. Means F is adapted to prevent the admission of the control vacuum signal during wide-open throttle conditions when exhaust gas recirculation is not desired. Means F comprises a housing 2 defining a chamber 30 within which is slidable a spool valve 31 having lands 32 and 33 spaced apart sufficiently to allow communication between an inlet 34 and an outlet 51 for conducting the control vacuum signal. Valve 31 is normally urged to a closed position over inlet 34 by spring 35 residing in chamber portion 40 defined between the right hand land 33 and the end of the chamber. The chamber portion 40 is normally in communication with intake manifold vacuum by way of passage 36; the chamber portion 37 on the opposite side of the spool valve (between land 32 and the end of the chamber) is in communication with atmosphere by either passage 38 or 39 connected as a vent V. Inlet 34 will be closed by the edge 52 of land 33 when manifold vacuum decreases to such a level that the compression spring acting on the spool valve, moves it sufficiently leftward. In the closed position, one of the vents will be open, particularly through passage 38. The control vacuum signal acting on the surfaces 32a and 33a of the respective lands 32 and 33 will offer no differential force urging the spool valve in either direction; therefore the differential between the force of spring 35 and the force of intake manifold vacuum, conveyed by passages 36 and 65, will determine the position of the spool valve 31.

The scope of this invention comprehends variations of the series of control means. For example, the system can be used without the transient valve means G if exhaust gas recirculation is desired at steady state cruising conditions. Control means F could be eliminated in conjunction with reservoir 98; valve means D can then be recalibrated to provide a shut-off at the highest vacuum encountered at wide-open throttle conditions with metering of the recirculation over a small range when above the highest vacuum encountered.

* * * * *


uspto.report is an independent third-party trademark research tool that is not affiliated, endorsed, or sponsored by the United States Patent and Trademark Office (USPTO) or any other governmental organization. The information provided by uspto.report is based on publicly available data at the time of writing and is intended for informational purposes only.

While we strive to provide accurate and up-to-date information, we do not guarantee the accuracy, completeness, reliability, or suitability of the information displayed on this site. The use of this site is at your own risk. Any reliance you place on such information is therefore strictly at your own risk.

All official trademark data, including owner information, should be verified by visiting the official USPTO website at www.uspto.gov. This site is not intended to replace professional legal advice and should not be used as a substitute for consulting with a legal professional who is knowledgeable about trademark law.

© 2024 USPTO.report | Privacy Policy | Resources | RSS Feed of Trademarks | Trademark Filings Twitter Feed