US3867919A

US3867919A - Anti-dieseling control

Info

Publication number: US3867919A
Application number: US329923A
Authority: US
Inventors: Emile P Grenier; George H Muller
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1973-02-05
Filing date: 1973-02-05
Publication date: 1975-02-25
Anticipated expiration: 1992-02-25
Also published as: JPS5392514U; GB1424992A; DE2405180A1; JPS5611636Y2; CA988380A; JPS5012426A

Abstract

An apparatus combination is disclosed for use with a conventional internal combustion engine, comprising an induction system for supplying a combustible mixture to the engine in response to engine suction, dilution means including a valve controlled duct effective to introduce air for a predetermined period to said induction means upon engine shut down, and means for overriding the de-energization of said ignition system during shut down to permit ignition of any combustible mixtures in said engine for a short period thereafter.

Description

United States Patent [191 Grenier et a1.

[54] ANTI-DIESELING CONTROL [75] Inventors: Emile P. Grenier; George H. Muller,

both of Ann Arbor, Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Feb. 5, 1973 [21] Appl. N0.: 329,923

[52] US. Cl..... 123/198 D, l23/DIG. 11, 123/97 B,

123/198 DC [51] Int. Cl. F02b 77/00, F02d 31/00 [58] Field of Search.. l23/DIG. 11, 198 D, 198 DB,

123/198 DC, 97 B [56] References Cited UNITED STATES PATENTS 1,751,322 3/l93O Gravel l23/DlG. 11 3,158,144 11/1964 Walker 123/198 DC 3,241,539 3/1966 Kuehn, Ill 3,287,899 11/1966 Bintz 3,354,877 11/1967 Zub et al. 123/DIG. 11 3,482,562 12/1969 Ranft 123/198 DC [451 Feb. 25, 1975 3,635,203 1/1972 Gannoe 123/D1G. 11 X 3,741,188 6/1973 Rickey 123/198 DB 3,752,450 8/1973 Charron et al l23/D1G. 11 X 3,753,427 8/1973 Cedar 123/D1G. 11 X 3,795,230 3/1974 Yoshimura 123/97 B Primary Examiner-Charles J. Myhre Assistant Examiner-Tony Argenbright Attorney, Agent, or Firm-Joseph W. Malleck; Keith L. Zerschling [57] ABSTRACT 4 Claims, 1 Drawing Figure army/M:

[keg/m?! 11. ANTI-DIESELING CONTROL BACKGROUND OF THE INVENTION gine mostly as a result of generation of excessive heat I in the engine at idle and/or after ignition shut off. Notably, when the engine is permitted to overheat a sufficient degree such that the compressed air/fuel mixture in the cylinders exceeds the mixture ignition temperature, the latter will ignite before or without an initiating spark. The problem of dieseling is accentuated in the instance of modern automotive engines which are built 'to power not only the vehicle but also accessories such as air conditioners, power steering, etc., which do generate heat, particularly at idle. In order to maintain a sufficiently fast curb idle speed in such an engine, it is necessary to adjust the carburetor to provide a relatively substantial air/fuel mixture. Thus, under conditions where an automotive engine becomes overheated, a dieseling condition will be maintained even though the engine ignition system is disconnected.

Air dilution, as one approach to this problem, has taken many forms such as including use of a special control for moving the throttle setting so that it will completelychoke off the air/fuel mixture to the engine when the ignition is shut off. Alternatively the throttle can be kicked open by means of a solenoid actuated by the ignition switch when the ignition is turned off, thus providing a substantially more diluted air/fuel ratio to prevent dieseling. Another mode is to draw in a sample of air into a common receptacle and maintain this sample during the operation of the engine{ the air is then forced out of the receptacle into the idle fuel chamber of the carburetor of the internal combustion engine shortly after ignition shut off. This sample of air thus provides a noncombustible air/fuel mixture to the cylinders of the engine. 7

The prior art also has developed various devices for continuing the combustion process after shut down of an engine for various purposes. This has been used particularly in connection with diesel engines in conjunctionwith different fuel injection timing wherein it is desirable to allow a few minutes of idle operation just before shut down after normal engine operation under load. An idle operation is desirable to permit the internal temperature of the engine to stabilize before complete shut down.

Each of these approaches have certain drawbacks when considered in light of modern engines and their accessory equipment. An appropriate solution must take into consideration exhaust systems which employ a converter to lower emission levels such as NO, to unprecedented levels. A suitable converter can be of the catalytic type using exotic metals easily contaminated by a certain change in the chemistry of gases passing therethrough. Since engine inherently provides a limited degree of suction after shut down due to the inertia of the elements continuing to move, a limited quantity of fuel, Oil fumes, or air is drawn into the engine regardless of throttle closure; such mixture may pass fully or in part uncombusted. The residual temperature of the catalytic converter may be such to permit a small amount of flaming combustion of such uncombusted elements resulting in contamination or damage to the catalyst.

SUMMARY OF THE INVENTION To overcome the above problems, this invention provides an apparatus combination effective to flush the intake manifold system with a large quantity of fresh air and simultaneously maintain the spark ignition system operative for a predetermined time after engine shut down has been initiated, in order to complete combustion of the mixture under increasingly lean air/fuel ratio.

Another object is to provide a time delay mechanism in such an apparatus combination which is effective to automatically restore the spark ignition system to its off condition after shut down but only when intake manifold vacuum has dropped below a predetermined level.

SUMMARY OF THE DRAWING DETAILED DESCRIPTION Turning now to FIG. 1, a preferred embodiment for this invention is illustrated. A control for post engine shut down is employed with a typical engine A of the internal combustion type having a spark ignition system B controllable by a suitable manual ignition switch C. The engine has a conventional induction system D for supplying a mixture of fuel and air to an intake manifold E leading to said engine. The exhaust gases from said engine travel through a typical exhaust system F, and in this embodiment a catalytic converter G is used to reduce the undesirable emission level of such gases (the catalytic converter being an important combination element for which this invention is effective to protect).

Some internal combustion engines set to legal emission standards for the current year, experience a glow type of ignition in the combustionchambers after the electrical ignition system B has been cut off or deenergized bytuming of the ignitionkey to open switch C. Dieseling is then experienced. Engine shut down shall be used to. refer to the conditions experienced by the engine upon cutting off the ignition spark; for a short period, the inertia of the pistons and other moving parts still continue to place a suction on the carburetor. In past years, the carburetor and carburetor controls have been suitably arranged so that upon shut down of the engine, the intake of air would be suitably cut off in a progressive manner to quickly reduce the induction of further fuel, which would construct a combustible mixture. Thus, after a period of generally no less than 2 seconds, the engine becomes totally dead, that is the residual heat of the engine is no longer capable of igniting the volume of air/fuel mixture that may happen to have been drawn into the engine.

However, as indicated, revised carburetion controls make it possible for the phenomenon of dieseling to take place after engine shutdown. It is very objectionable as it permits emission of noxious pollutants and allows unburned gaseous elements to beconveyed to the downstream catalytic converter causing contamination or destruction of the catalytic elements. Catalytic converters are designed to provide a flameless combustion of exhaust gases at a predetermined range of chemical makeup and at a predetermined temperature level. At shut down, the right temperature condition still prevails due to retained heat in the engine and converter, but an unusual rich air/fuel mixture may be exhausted to provide a glow or semi-flaming combustion in the converter. The result is poisoning or destruction of the expensive catalytic elements which may be of exotic metal such as palladium.

To overcome these objections, the present invention uses an anti-dieseling control which comprises the combination of a dilution means H for flooding the intake manifold with air and means I for overriding the de-energization of the ignition system during shut down to permit ignition of any combustible mixture in the engine for a predetermined period. The means H has a duct communicating an opening 11 in the intake manifold E with outside fresh air to flood and dilute the mixture coming from the induction system for said engine in response to the turning off of the ignition switch and instigating engine shut down. The duct introduces the dilution air to the intake system downstream from where nonnal or regular fuel and air is inducted. A desirable location for the opening 11 is on the opposite portion relative to the carburetor throttle body and as is generally done for the carburetor, it is centrally located in regard to the engine intake parts.

Duct 10 is operably controlled by an admission valve 12 having a valve housing 13 extending transversely across the duct 10 and has a valve orifice l4 defined by the intersection of the housing and duct. A valve element or cylinder 15 is slidable in intimate relationship with housing 13 and can progressively close off the valve orifice 14. The valve element 15 is normally urged in one direction to close the orifice by a spring 16 operating between the housing and an extension 17 of the valve element. A solenoid actuator 18 is effective to overcome said bias by urging an extension 19 in an opposite direction to open the orifice.

A circuit 23 is employed to connect an electrical power source 24 for the spark ignition system with the solenoid actuator 18. To suitably control circuit 23 for use only when desired during engine shut down, another circuit 25 is employed to normally maintain circuit 23 in an open condition when the manual ignition switch C is closed for engine operation. A switch element 26 is normally urged to a closed condition on contacts 27 by resilient means (not shown); element 26 is moved to an open condition by a solenoid assembly 28 with a coil in series with circuit 25 and effective to move extension 29 of element 26 by the force field set up. Thus, during normal engine operation, the solenoid assembly 28 will be energized maintaining the element 26 in the open condition and thereby de-activating actuator l8 keeping duct 10 closed. When the ignition switch C is turned off, assembly 28 is de-energized closing element 26. Circuit 23 is now closed permitting energy to flow to the solenoid actuator 18 and opening duct 10. If actuator 18 is inoperative, for some reason, valve 15 will remain closed rendering a failsafe provision for the combination.

Flushing the intake manifold with air is not alone sufficient; the anti-dieseling control further incorporates an arrangement for continuing spark for ignition a predetermined period after shut-down. To this end, a circuit 31 connects to circuit 23 to receive power when shut-down occurs; circuit 31 connects to one terminal 32 of ignition switch C, terminal 32 is electrically connected to the spark ignition system B. Thus, when shutdown occurs, the spark ignition system continues to function, igniting the mixture in the combustion chamber which is rapidly becoming very lean. To fully terminate the spark, a swtich (element 34 and contacts 35) may be used to interrupt circuit 31 in response to movement of valve element 15 which occurs after circuit 23 is interrupted by a delay mechanism.

The delay mechanism or means I for overriding the de-energization of the ignition system comprises a vacuum responsive electrical switch assembly. The assembly has a housing 36 defining a chamber within which a slidable diaphragm 37 is disposed. A switch element 38 is carried on the diaphragm 37 for connecting or disconnecting contacts 39 of circuit 23. Side 37a of the diaphragm is engaged by spring 40 to urge the switch element to a normally open condition. Side 37a is also subject to vacuum pressure from the intake manifold E; a ball check valve 41 permits communication of vacuum when sufficient to move the check valve and prevents communication at other times thereby venting the housing chamber to atmosphere by way of passage V.

When engine shut down is first initiated, the engine has sufflcient intake manifold vacuum to overcome spring 40 and close contacts 39 thereby allowing the solenoid actuator 18 to be energized for permitting the entrance of the dilution air into the engine. As the diluted mixture in the intake manifold provides progressively less and less power through carburetion, the engine vacuum becomes progressively weaker. Over a period of approximately 5 to 6 seconds, the vacuum level will have deteriorated to a point where spring 40 causes opening of circuit 23. Within a short time thereafter, decay of the magnetic field of actuator 18 will allow the contacts 35 to be opened preventing further spark for ignition.

in review of the operation, when the ignition switch C is opened, current flow to solenoid assembly 28 stops allowing element 26 to close contacts 27. Current can then flow from the power source 24 to contact 39. Upon initiation of shut down, manifold vacuum is usually high so that element 38 has contact 39 closed to permit current to flow to actuator 18 and open duct 10. Momentarily, upon movement of valve 15 to the right, contacts 35 will be closed by element 34 permitting current to continue to flow to the spark ignition system. For a period of time, this simultaneous air flooding and spark ignition will continue; when manifold vacuum decays to a predetermined level, the contacts 39 will be opened, closing duct 10 and breaking current flow to the spark ignition system. Vent V will control the timing of re-opening of contacts 39.

We claim:

1. For use with an engine having a primary combustion zone and a selectively controllable spark ignition system which can be de-energized for shutting down said engine, the combination comprising:

a. an air-fuel induction means for supplying a combustible mixture to said engine,

b. a duct for supplying fresh air to said mixture,

c. a valve for controlling the admission of fresh air to said duct and having a housing extending across said duct and a valve member slidable in said housing for closing off said duct,

d. means for operating said valve between open and closed positions of said duct, said means normally biasing said member to a closed position and having a solenoid actuator responsive to engine shut down for overcoming said bias to move said member to an open position, said operating means providing an electrical circuit for said actuator which is responsive to selective de-energization of said spark ignition system to open said valve and delay completion of said de-energization to permit igni tion of said mixture for a predetermined period, said circuit being responsive to normal energization of said spark ignition system to open said circuit, and

e. a catalytic converter having material for sustaining combustion at a predetermined temperature level, said operating means being effective to continue combustion of said mixture in said primary zone after engine shut-down in a manner to prevent uncombusted mixtures from reaching said catalytic converter that can flamingly combust in said converter at said predetermined temperature level.

2. For use with an engine having a primary combustion zone and a selectively controllable spark ignition system which can be de-energized for shutting down said engine, the combination comprising:

b. a duct for supplying fresh air to said mixture,

c. a valve for controlling the admission of fresh air to said duct, and

d. means for operating said valve between open and closed positions, said means being responsive to selective de-energization of said spark ignition system to open said valve and delay completion of said de-energization to permit ignition of said mixture for a predetermined period, said operating means having: (I) a solenoid actuator for moving said valve to an open position, (2') an electrical circuit for energizing said solenoid engine, (3) means rcsponsive to energization of said spark ignition system for maintaining said circuit in an open condition, said responsive means having a switch in said circuit normally biased to a closed position, a sole noid actuator for opening said switch, said solenoid actuator being de-energized in response to deenergization of said spark ignition system, and (4) delay means in said circuit operable to open said circuit after a predetermined period has elapsed from de-energization of said spark ignition system.

3. The combination as in claim 2, in which that portion of the operating means providing for a delay comprises a vacuum-operated switch responsive to the intake manifold vacuum of said engine.

4. The combination in claim 2, in which the vacuum operated switch has a diaphragm for moving said switch between opened and closed positions, said diaphragm being moved in one direction by a spring force and in an opposite direction by the force of vacuum from said intake manifold, whereby said circuit is closed upon de-energization of said spark ignition system and is maintained closed until the force-of said vacuum falls below the spring force in response to a cessation of combustion.

Claims

1. For use with an engine having a primary combustion zone and a selectively controllable spark ignition system which can be deenergized for shutting down said engine, the combination comprising: a. an air-fuel induction means for supplying a combustible mixture to said engine, b. a duct for supplying fresh air to said mixture, c. a valve for controlling the admission of fresh air to said duct and having a housing extending across said duct and a valve member slidable in said housing for closing off said duct, d. means for operating said valve between open and closed positions of said duct, said means normally biasing said member to a closed position and having a solenoid actuator responsive to engine shut down for overcoming said bias to move said member to an open position, said operating means providing an electrical circuit for said actuator which is responsive to selective de-energization of said spark ignition system to open said valve and delay completion of said de-energization to permit ignition of said mixture for a predetermined period, said circuit being responsive to normal energization of said spark ignition system to open said circuit, and e. a catalytic converter having material for sustaining combustion at a predetermined temperature level, said operating means being effective to continue combustion of said mixture in said primary zone after engine shut-down in a manner to prevent uncombusted mixtures from reaching said catalytic converter that can flamingly combust in said converter at said predetermined temperature level.

2. For use with aN engine having a primary combustion zone and a selectively controllable spark ignition system which can be de-energized for shutting down said engine, the combination comprising: a. an air-fuel induction means for supplying a combustible mixture to said engine, b. a duct for supplying fresh air to said mixture, c. a valve for controlling the admission of fresh air to said duct, and d. means for operating said valve between open and closed positions, said means being responsive to selective de-energization of said spark ignition system to open said valve and delay completion of said de-energization to permit ignition of said mixture for a predetermined period, said operating means having: (1) a solenoid actuator for moving said valve to an open position, (2) an electrical circuit for energizing said solenoid engine, (3) means responsive to energization of said spark ignition system for maintaining said circuit in an open condition, said responsive means having a switch in said circuit normally biased to a closed position, a solenoid actuator for opening said switch, said solenoid actuator being de-energized in response to de-energization of said spark ignition system, and (4) delay means in said circuit operable to open said circuit after a predetermined period has elapsed from de-energization of said spark ignition system.

4. The combination in claim 2, in which the vacuum operated switch has a diaphragm for moving said switch between opened and closed positions, said diaphragm being moved in one direction by a spring force and in an opposite direction by the force of vacuum from said intake manifold, whereby said circuit is closed upon de-energization of said spark ignition system and is maintained closed until the force of said vacuum falls below the spring force in response to a cessation of combustion.