CA1070197A - Exhaust gas purifying system with an air-fuel mixture heating means - Google Patents
Exhaust gas purifying system with an air-fuel mixture heating meansInfo
- Publication number
- CA1070197A CA1070197A CA254,361A CA254361A CA1070197A CA 1070197 A CA1070197 A CA 1070197A CA 254361 A CA254361 A CA 254361A CA 1070197 A CA1070197 A CA 1070197A
- Authority
- CA
- Canada
- Prior art keywords
- exhaust gas
- gas purifying
- air
- fuel mixture
- engine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
- F02D35/0046—Controlling fuel supply
- F02D35/0053—Controlling fuel supply by means of a carburettor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M31/00—Apparatus for thermally treating combustion-air, fuel, or fuel-air mixture
- F02M31/02—Apparatus for thermally treating combustion-air, fuel, or fuel-air mixture for heating
- F02M31/04—Apparatus for thermally treating combustion-air, fuel, or fuel-air mixture for heating combustion-air or fuel-air mixture
- F02M31/10—Apparatus for thermally treating combustion-air, fuel, or fuel-air mixture for heating combustion-air or fuel-air mixture by hot liquids, e.g. lubricants or cooling water
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
An internal combustion engine with a feedback type air-fuel mixture supply means is provided with an airfuel mixture heating means at the intake system thereof. The heating means is so constructed to preheat the mixture by using the heated cooling water coming out from the water jackets of the cylinder block of the engine.
Description
~L07~1~7 The present invention relates in general to an exhaust gas purifying system of an internal combustion engine and particularly to the system of a type having ~ feedback type air-fuel mixture supply means which can control the air-fuel ratio of the air-fuel mixture fed into the combustion chambers of the engine in accordance with the concentration of a predetermined kind of constituents in the exhaust gases issued from the engine.
More particularly, the present invention is concerned with the exhaust gas purifying system of the kind mentioned above in which the air-fuel mixture is he~ted by engine cooling water heated by the heat developed as a result of the operation of the engine ~o that the gasification of the fuel in the mixture is preferably achieved to remarkably improve the operational response of the air-fuel mixture supply means.
It is well known that the concentration of the predetermined kind of constituents in the exhaust gases issued from the internal combustion engine varies with the air-fuel ratio of the air-fuel mixture supplied into the engine. Thus, for the efficient reduction of harmful compounds in the exhaust gases from the engine, it is a preferable way to electronically con-trol the air-fuel ratio of the mix~ure fed into the engine by using the concentration of the predetermined ~ .
kind of constituents as an information factor.
Hitherto~ as the practical procedure, a feeaback type air-fuel mixture supply means has been employed in whIch the desired air-fuel ratio of the air-fuel mixture is determined by the operation of an air-fuel mixture supply means electrically actuated by command signals from a control unit capable of computing the information signals issued from an exhaust gas sensor disposed in the exhaust system of the engine.
Indeed, this means can provide the engine with the stable operation of it when the engine runs at a constant revolution speed. However, in this means, it has been commonly observed that the actual air-fuel ratio controlling operation is subjected to aslow operational response by the nature of the feedback type system. This unwanted phenomenon more remarkably affects the stable operation of the engine especially when the engine is fed with mixture having frequent variation of air-fuel ratio due to the frequently repeated accelerations and/or the decelerations of the engine.
Basically, the operational response of the feed-back type air-fuel mixture supply means closely relates ~25 to the degree of the engine speed. More specifically, ~7~7 the response time is shorten as the engine speed increases. This is because that, in the high speed condition of the engine, the speeds of the air-fuel mixture flow and the exhaust gas flow are inevitably increased. However~ there is a limit in ability of increasing the speeds of the flows of the air-fuel mixture and the exhaust gases by reason of the techni-cal limitation of the engine. Thus, in order to effectively improve the response of the above-mentioned means, it is necessary to check unknown factors other than the factor of the engine speed, Apart from this, during the passage of the air-fuel mixture through the intake tube or manifold, a consi-derable amount of liquid fuel drops out of the mixture and spreads in a thin layer over the inner surface of the-intake tube, and thereafter the liquid fuel slowly flows down along the inner surface of the intake tube toward the combustion chambers of the engine. (It is said that 60% of fuel in the air-fuel mixture in the intake tube is in a liquid state when the engine runs at a low speed, further, 403/~ of fuel is in a liquid state when the engine runs at a high speed.) With respect to the moving ability of fuel, in liquid and gas states, passing through the intake tube f the engine it is observed that the moving ability - lL --~1[)7(~9~ :
of completely gasified fuel is about one hundred times as much as that of the liquid fuel, as is well seen from ~ig. 1. Therefore~ the amount of fuel actually received in the combustion chambers per unit time i3 generally in proportion to the rate of gasification of the fuel. In Fig. 1, the point 100 of the moving ability indicates a condition wherein the flow rates of the fuel and the air are equal to each other.
From the above descriptionj it will be appreciated that if well gasification of the fuel of the air-fuel mixture is not made in the intake tube, the feeds of the fuel and the air into the combustion chambers of.
the engine from the air-fuel mixture supply means are not timingly or simultaneously done by the reason mentioned before, thereby preventing the normal opera-tion of the engine. In other words, the air-fuel ratio controlling operation of the feedback type air-fuel supply means is caused to have a relatively long res-ponse tlme. This response delay remarkabLy affects the operation of the engine especially when the engine is subjected to frequent repetition of acceleration and/or deceleration.
It is possible to heat the air-fuel mixture for the well gasification of the fuel by using the heat of the exhaust gases emitted from the engine.
~owever, in this case, the temperature drop of the exhaust gases is inevitably occured. Thus, if the temperature of the exhaust gases emitted from the engine is in a critical level wherein the exhaust gas sensor barely functions, the temperature drop of the exhaust gases will cause the sensor to fail in the normal operation. Further, if the exhaust gas purify-ing system is of a type including exhaust gas purifying device such as a catalytic converter and/or a thermal reactor, the temperature drop will also affect the optimal functions of these devices as well known.
Therefore, the present invention contemplates pro-vision of a new and useful exhaust gas purifying system which can eliminate the drawbacks encountered in the prior art system as mentioned.
It is an object of the present invention to provide an eXhaust gas purifying system including a feedback type air-fuel mixture supply system which ensures improved response time.
It is another object of the present invention to provide an exhaust gas purifying system which has an air-fuel mixture heating means for facilitating the gasification of the fuel of the mixture by using the heat of the cooling water of the engine.
It is still another object of the present invention ~7~
to provide an exllaust gas puriEying system having a feedback type air-fuel mixture supply means, in which a heat transfer chamber is forrned at -the intake tube or manifold for receiving therein the heated cooling water coming out from water jackets of a cylinder block of the engine.
Accordingly, the present invention provides an exhaust gas purifying system for use wi-th an internal combustion engine having intake and exhaust systems thereof, comprising: an exhaust gas sensor disposed in said exhaust system of the engine for issuing an information signal representing the concentration of a given constituent in the exhaust gases issued from the engine; electronically controlled air-fuel supply means mounted in said intalce system of the engine for sypplying an air-fuel mixture in response to a command signal applied thereto; a -control unit electricallv connected to said electronically controlled air-fuel mixture supplv means and said exhaust gas sensor for issuing a command signal to said air-fuel mixture supply means upon receiving said information signal issued from the exhaust gas sensor; and air-fuel mixture heating means mounted insaid intake system of the engine for preheating the mixture passing through the intake s~stem, wherehy preferable gasification of the fuel in the mixture is achieved.
Other objects and advantages of the present invention will become more apparen-t from the following description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic graph illustrating a relationship between the gasification rate of a fuel and the moving ability of the fuel;
Fig. 2 is a schematic view of an exhaust gas purifying system according to the present invention, in which the system is illustrated as accompanied with an internal combustion engine;
and ~7~)~97 Fig. 3 is a schematic graph illustrating a relationship between the running speed of a vehicle equipped with the system of the present invention and the amount of carbon monoxide (~0) contained in the exhaust gases issued from the cngine, further in which, for the comparison, a relationship on the conventional sys~em is a]so shown.
~s ~ell shown in Fig. 1, the moving abili-ty of the ~07~9-~
completelygasified fuel is excellent. The amount of fuel a~tually recei.ved in the combustion chambers of the en,¢ine per unit time is generally proportional to the gaslfication rate of the fuel, as shown.
.5 Referring now to Fig. 2, there is shown the exhaust gas purifying system o~ the present invention, the system being accompanied by an internal combustion .
engine 10~ The engine 10 generally comprises an . . intake system and an exhaust sys~em which are generally designated.by reference numerals 12 and 1~, respectively.
The intake system 12 comprises an air filter 16 containing therein a fiIter element (not shown), an electronically controlled air-fuel.mixture supply means 18~ a throttle valve 19, and an intake tube or manifold 20. The electronically controlled air-fuel mixture supply mean.s 18 may be both types of an electro-nically controlled carburetor and an electronically .
controlled f~el injector and comprises an electric or electro masnetic valve 22. The electric valve 22 may be of an ON-OFF type which is so constructed to open a passage-for fuel supply into the air-fuel mixture passage of the mixture supply means 18 when electri-cally ener$ized. The electric valve 22 is connected to a control unit 24 the description on which will be made hereinafter.
3L~7~7 The exhaust gas system 14 generally comprises an ex~laust tube 26 fluidly connected to exhaust ports formed in a cylinder head (no numeral) of the engine 10, and an exhaust gas purifying device 28, such as 5 a three-way catalytic converter, an oxidizing converter, a reducing converter and/or a thermal reactor, disposed in a downstream portion of the exhaust tube 26 as shown.
Projected into the exhaust tube 26 upstream of the exhaust gas purifying device 28 is an exhaust gas sensor 30 which is electrically connected to the control unit 24 for sending information signals, representing concentration of a given constituent in the exhaust gases, to the control unit 24. The exhaust gas sensor 30 may be so constructed to generate an output voltage the magnitude of which is generally proportional to the concentration of the given constituent contained in the sxhaust gases. Now9 it is to be noted that, as men-tioned before, the concentration of the given constituent in the exhaust gases is closely related to the actual air-fuel ratio of the mixture fed into the engine 10.
Thus, it is very possible to estimate the air-fuel ratio of the mixture by measuring the concentration of the given constituent in the exhaust gases. The exhaust gas sensor may be one of the types of an oxygen sensor, a hydrocarbon sensor, a carbon monoxide sensor 9 a carbon .
dioxide sensor and a nitrogen oxide sensor.
The control unit 24 generally comprises a propor-tional-integral controller 32, a pulse generator 31~ and a pulse width rnodulator 36 which are connected to each other and to the electric valve 22 and the exhaust gas sensor 32, as shown. The proportional-integral con-troller 32 has both a proportional portion, as well as integrating portion, and delivers a control voltage to the pulse width modulator 36 thus generates a train of pulses whose duration depends on the input control vol-tage. Therefore, the opening time of the electric valve 22 is controlled by the width of the pulses generatea by the modulator 3~. In this invention, the control unit is so arranged to allow the electric valve 22 to have a standard opening time when the exhaust gas sensor issues a basic output voltage representing a state where-in the air-fuel mixture supplied into the engine lO is in a desired air fuel ratio, such as a stoichiometric condition, and to have an opening time longer or shorter than the standard opening time when the sensor 30 issues lower or higher output vol*ages respectively representing state wherein the air-fuel mixture is leaner or richer than the desired air-fuel ratio condition.
An air-fuel mixture heating means is further employed in this exhaust gas purifying system of the present invention~ which is provided in the intake tube or manifold 20 for preheating the air-fuel mixture passing through the tube 20. The air-fuel mixture heating means includes a heat transfer chamber 30 positionocl directly under the whole floor portion of the intake tube or manifold 20. As well seen, the heat transfer chamber 38 is formed to have,an enlarged section 38a located under the throttle valve 19. The heat'transfer chamber 38 is in'communication with water jackets ~not shown) formed in the cylinder block of the engine 10 so that the hot water comming out from the water jackets thereinto preheats the air-fuel mixture being passed through the inta~e tube 20. To.efficiently heat the air-fuel mixture, it is preferable to arrange the heat transfer chamber 38 in such a manner that heated water from the water jackets of the engine is directly fed into the heat transfer chamber 38 before being introduced into a radiator (not shown).~
With the above-stated construction of the exhaust gas purifying system of the present invention, the operation is as follows:
- Under the engine opération, when the exhaust gas sensor 30 issues an output voltage the degree of which is lower than the basic output voltage, the control unit 24 issues command signals to the electric valve ~ .
~.~70197 22 for allowing the same to have a relatively long opening time for supplying relatively large amount of fuel into the air-fuel mixture passage of the air-fuel mixture supply means 18. On the contrary, when the oxhaust gas sensor 30 issues an output voltage the deg~ee of which is higher than the basic output voltage, the control unit 24 operates the electric valve 22 to have a relati~ely short opening time for supplying a relatively small amount of fuel into the air-fuel mixture passage of the air-fuel mixture supply means 18. Thus~ the air-fuel ratio of the air-fuel mixture just provided .in the viGinity of the air-fuel mixture supply means 18 is maintained within a range close to the desired leve]. under the engine operation.
Now, it is to be appreciated that since the air-fuel mixture from the air-fuel mixture supply means 18 is preheated by the hot engine cooling water as mentioned, almost whole amount of fuel in the air-fuel mixture is gasfied instantly in the in$ake tube or manifold 20 thereby providing the simultaneous reach-ing of the intake a1r and the gasfied fuel to the combustion chambers. Thus, the response time of the feedback type air-fuel mixture supp]y means i5 made shorten ~ that -the burning condition of the air-fuel mixture in the combustion chambers is reliably and accurately 107~197 controlled in accordance with the concentration of the given constituent in the exhaust gases from the engine 10. Accordingly, even if the engine 10 is subjected to frequent repetition of acceleration and/or decelera-tion thereof,.the operation of`the engine 10 is not.so affected.
In order to show the advantages according to the pro-~ision of the air-fuel mixture heating means to the ex-haust gas purifying sy~tem of ~he invention~ a graph is presented in Fig. 3, which shows the concentration of carbon monoxide (C0) contained in the exhaust gases issued from two engines (A) and (B). The engine (A).
is of a type equipped with the feedback type air-fuel mixture supply means with the mixture heating means and the engine (B) is of a type equipped with the feedback type air:fuel mixture supply means without the mixture heating means. From this graph 9 it will be appreciated that the amount of carbon monoxide (C0) issued from the engine (A) with the mixture heating means is remarkably small than that of the engine (B) without such means.
It should be noted that since the air-fuel mixture heating is not made by the exhaust gases, the tempe-rature drop of -the exhaust gases can.not be occured so that the normal functions of the exhaust gas sensor ~7~9'7 and the exhaust gas purifying device are not disturbed.
In conclusion~ by the provision of the air-fuel mixture heating means, the operational response of the feodback type air-fuel mixture supply is remarkably improvad, so that the reduction of the harmful com-pounds in the exhaust gases is tnore accurately achieved.
In the same time, the stable engine operation is not disturbed by the frequent repetition of the accelera-tions and/or the decelerations thereof.
It is to be understood that the invention is not to be limited to the exact construction shown and described and that various changes and modifications~
may be made without departing from the scope of the invention, as described in the appended claims.
More particularly, the present invention is concerned with the exhaust gas purifying system of the kind mentioned above in which the air-fuel mixture is he~ted by engine cooling water heated by the heat developed as a result of the operation of the engine ~o that the gasification of the fuel in the mixture is preferably achieved to remarkably improve the operational response of the air-fuel mixture supply means.
It is well known that the concentration of the predetermined kind of constituents in the exhaust gases issued from the internal combustion engine varies with the air-fuel ratio of the air-fuel mixture supplied into the engine. Thus, for the efficient reduction of harmful compounds in the exhaust gases from the engine, it is a preferable way to electronically con-trol the air-fuel ratio of the mix~ure fed into the engine by using the concentration of the predetermined ~ .
kind of constituents as an information factor.
Hitherto~ as the practical procedure, a feeaback type air-fuel mixture supply means has been employed in whIch the desired air-fuel ratio of the air-fuel mixture is determined by the operation of an air-fuel mixture supply means electrically actuated by command signals from a control unit capable of computing the information signals issued from an exhaust gas sensor disposed in the exhaust system of the engine.
Indeed, this means can provide the engine with the stable operation of it when the engine runs at a constant revolution speed. However, in this means, it has been commonly observed that the actual air-fuel ratio controlling operation is subjected to aslow operational response by the nature of the feedback type system. This unwanted phenomenon more remarkably affects the stable operation of the engine especially when the engine is fed with mixture having frequent variation of air-fuel ratio due to the frequently repeated accelerations and/or the decelerations of the engine.
Basically, the operational response of the feed-back type air-fuel mixture supply means closely relates ~25 to the degree of the engine speed. More specifically, ~7~7 the response time is shorten as the engine speed increases. This is because that, in the high speed condition of the engine, the speeds of the air-fuel mixture flow and the exhaust gas flow are inevitably increased. However~ there is a limit in ability of increasing the speeds of the flows of the air-fuel mixture and the exhaust gases by reason of the techni-cal limitation of the engine. Thus, in order to effectively improve the response of the above-mentioned means, it is necessary to check unknown factors other than the factor of the engine speed, Apart from this, during the passage of the air-fuel mixture through the intake tube or manifold, a consi-derable amount of liquid fuel drops out of the mixture and spreads in a thin layer over the inner surface of the-intake tube, and thereafter the liquid fuel slowly flows down along the inner surface of the intake tube toward the combustion chambers of the engine. (It is said that 60% of fuel in the air-fuel mixture in the intake tube is in a liquid state when the engine runs at a low speed, further, 403/~ of fuel is in a liquid state when the engine runs at a high speed.) With respect to the moving ability of fuel, in liquid and gas states, passing through the intake tube f the engine it is observed that the moving ability - lL --~1[)7(~9~ :
of completely gasified fuel is about one hundred times as much as that of the liquid fuel, as is well seen from ~ig. 1. Therefore~ the amount of fuel actually received in the combustion chambers per unit time i3 generally in proportion to the rate of gasification of the fuel. In Fig. 1, the point 100 of the moving ability indicates a condition wherein the flow rates of the fuel and the air are equal to each other.
From the above descriptionj it will be appreciated that if well gasification of the fuel of the air-fuel mixture is not made in the intake tube, the feeds of the fuel and the air into the combustion chambers of.
the engine from the air-fuel mixture supply means are not timingly or simultaneously done by the reason mentioned before, thereby preventing the normal opera-tion of the engine. In other words, the air-fuel ratio controlling operation of the feedback type air-fuel supply means is caused to have a relatively long res-ponse tlme. This response delay remarkabLy affects the operation of the engine especially when the engine is subjected to frequent repetition of acceleration and/or deceleration.
It is possible to heat the air-fuel mixture for the well gasification of the fuel by using the heat of the exhaust gases emitted from the engine.
~owever, in this case, the temperature drop of the exhaust gases is inevitably occured. Thus, if the temperature of the exhaust gases emitted from the engine is in a critical level wherein the exhaust gas sensor barely functions, the temperature drop of the exhaust gases will cause the sensor to fail in the normal operation. Further, if the exhaust gas purify-ing system is of a type including exhaust gas purifying device such as a catalytic converter and/or a thermal reactor, the temperature drop will also affect the optimal functions of these devices as well known.
Therefore, the present invention contemplates pro-vision of a new and useful exhaust gas purifying system which can eliminate the drawbacks encountered in the prior art system as mentioned.
It is an object of the present invention to provide an eXhaust gas purifying system including a feedback type air-fuel mixture supply system which ensures improved response time.
It is another object of the present invention to provide an exhaust gas purifying system which has an air-fuel mixture heating means for facilitating the gasification of the fuel of the mixture by using the heat of the cooling water of the engine.
It is still another object of the present invention ~7~
to provide an exllaust gas puriEying system having a feedback type air-fuel mixture supply means, in which a heat transfer chamber is forrned at -the intake tube or manifold for receiving therein the heated cooling water coming out from water jackets of a cylinder block of the engine.
Accordingly, the present invention provides an exhaust gas purifying system for use wi-th an internal combustion engine having intake and exhaust systems thereof, comprising: an exhaust gas sensor disposed in said exhaust system of the engine for issuing an information signal representing the concentration of a given constituent in the exhaust gases issued from the engine; electronically controlled air-fuel supply means mounted in said intalce system of the engine for sypplying an air-fuel mixture in response to a command signal applied thereto; a -control unit electricallv connected to said electronically controlled air-fuel mixture supplv means and said exhaust gas sensor for issuing a command signal to said air-fuel mixture supply means upon receiving said information signal issued from the exhaust gas sensor; and air-fuel mixture heating means mounted insaid intake system of the engine for preheating the mixture passing through the intake s~stem, wherehy preferable gasification of the fuel in the mixture is achieved.
Other objects and advantages of the present invention will become more apparen-t from the following description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic graph illustrating a relationship between the gasification rate of a fuel and the moving ability of the fuel;
Fig. 2 is a schematic view of an exhaust gas purifying system according to the present invention, in which the system is illustrated as accompanied with an internal combustion engine;
and ~7~)~97 Fig. 3 is a schematic graph illustrating a relationship between the running speed of a vehicle equipped with the system of the present invention and the amount of carbon monoxide (~0) contained in the exhaust gases issued from the cngine, further in which, for the comparison, a relationship on the conventional sys~em is a]so shown.
~s ~ell shown in Fig. 1, the moving abili-ty of the ~07~9-~
completelygasified fuel is excellent. The amount of fuel a~tually recei.ved in the combustion chambers of the en,¢ine per unit time is generally proportional to the gaslfication rate of the fuel, as shown.
.5 Referring now to Fig. 2, there is shown the exhaust gas purifying system o~ the present invention, the system being accompanied by an internal combustion .
engine 10~ The engine 10 generally comprises an . . intake system and an exhaust sys~em which are generally designated.by reference numerals 12 and 1~, respectively.
The intake system 12 comprises an air filter 16 containing therein a fiIter element (not shown), an electronically controlled air-fuel.mixture supply means 18~ a throttle valve 19, and an intake tube or manifold 20. The electronically controlled air-fuel mixture supply mean.s 18 may be both types of an electro-nically controlled carburetor and an electronically .
controlled f~el injector and comprises an electric or electro masnetic valve 22. The electric valve 22 may be of an ON-OFF type which is so constructed to open a passage-for fuel supply into the air-fuel mixture passage of the mixture supply means 18 when electri-cally ener$ized. The electric valve 22 is connected to a control unit 24 the description on which will be made hereinafter.
3L~7~7 The exhaust gas system 14 generally comprises an ex~laust tube 26 fluidly connected to exhaust ports formed in a cylinder head (no numeral) of the engine 10, and an exhaust gas purifying device 28, such as 5 a three-way catalytic converter, an oxidizing converter, a reducing converter and/or a thermal reactor, disposed in a downstream portion of the exhaust tube 26 as shown.
Projected into the exhaust tube 26 upstream of the exhaust gas purifying device 28 is an exhaust gas sensor 30 which is electrically connected to the control unit 24 for sending information signals, representing concentration of a given constituent in the exhaust gases, to the control unit 24. The exhaust gas sensor 30 may be so constructed to generate an output voltage the magnitude of which is generally proportional to the concentration of the given constituent contained in the sxhaust gases. Now9 it is to be noted that, as men-tioned before, the concentration of the given constituent in the exhaust gases is closely related to the actual air-fuel ratio of the mixture fed into the engine 10.
Thus, it is very possible to estimate the air-fuel ratio of the mixture by measuring the concentration of the given constituent in the exhaust gases. The exhaust gas sensor may be one of the types of an oxygen sensor, a hydrocarbon sensor, a carbon monoxide sensor 9 a carbon .
dioxide sensor and a nitrogen oxide sensor.
The control unit 24 generally comprises a propor-tional-integral controller 32, a pulse generator 31~ and a pulse width rnodulator 36 which are connected to each other and to the electric valve 22 and the exhaust gas sensor 32, as shown. The proportional-integral con-troller 32 has both a proportional portion, as well as integrating portion, and delivers a control voltage to the pulse width modulator 36 thus generates a train of pulses whose duration depends on the input control vol-tage. Therefore, the opening time of the electric valve 22 is controlled by the width of the pulses generatea by the modulator 3~. In this invention, the control unit is so arranged to allow the electric valve 22 to have a standard opening time when the exhaust gas sensor issues a basic output voltage representing a state where-in the air-fuel mixture supplied into the engine lO is in a desired air fuel ratio, such as a stoichiometric condition, and to have an opening time longer or shorter than the standard opening time when the sensor 30 issues lower or higher output vol*ages respectively representing state wherein the air-fuel mixture is leaner or richer than the desired air-fuel ratio condition.
An air-fuel mixture heating means is further employed in this exhaust gas purifying system of the present invention~ which is provided in the intake tube or manifold 20 for preheating the air-fuel mixture passing through the tube 20. The air-fuel mixture heating means includes a heat transfer chamber 30 positionocl directly under the whole floor portion of the intake tube or manifold 20. As well seen, the heat transfer chamber 38 is formed to have,an enlarged section 38a located under the throttle valve 19. The heat'transfer chamber 38 is in'communication with water jackets ~not shown) formed in the cylinder block of the engine 10 so that the hot water comming out from the water jackets thereinto preheats the air-fuel mixture being passed through the inta~e tube 20. To.efficiently heat the air-fuel mixture, it is preferable to arrange the heat transfer chamber 38 in such a manner that heated water from the water jackets of the engine is directly fed into the heat transfer chamber 38 before being introduced into a radiator (not shown).~
With the above-stated construction of the exhaust gas purifying system of the present invention, the operation is as follows:
- Under the engine opération, when the exhaust gas sensor 30 issues an output voltage the degree of which is lower than the basic output voltage, the control unit 24 issues command signals to the electric valve ~ .
~.~70197 22 for allowing the same to have a relatively long opening time for supplying relatively large amount of fuel into the air-fuel mixture passage of the air-fuel mixture supply means 18. On the contrary, when the oxhaust gas sensor 30 issues an output voltage the deg~ee of which is higher than the basic output voltage, the control unit 24 operates the electric valve 22 to have a relati~ely short opening time for supplying a relatively small amount of fuel into the air-fuel mixture passage of the air-fuel mixture supply means 18. Thus~ the air-fuel ratio of the air-fuel mixture just provided .in the viGinity of the air-fuel mixture supply means 18 is maintained within a range close to the desired leve]. under the engine operation.
Now, it is to be appreciated that since the air-fuel mixture from the air-fuel mixture supply means 18 is preheated by the hot engine cooling water as mentioned, almost whole amount of fuel in the air-fuel mixture is gasfied instantly in the in$ake tube or manifold 20 thereby providing the simultaneous reach-ing of the intake a1r and the gasfied fuel to the combustion chambers. Thus, the response time of the feedback type air-fuel mixture supp]y means i5 made shorten ~ that -the burning condition of the air-fuel mixture in the combustion chambers is reliably and accurately 107~197 controlled in accordance with the concentration of the given constituent in the exhaust gases from the engine 10. Accordingly, even if the engine 10 is subjected to frequent repetition of acceleration and/or decelera-tion thereof,.the operation of`the engine 10 is not.so affected.
In order to show the advantages according to the pro-~ision of the air-fuel mixture heating means to the ex-haust gas purifying sy~tem of ~he invention~ a graph is presented in Fig. 3, which shows the concentration of carbon monoxide (C0) contained in the exhaust gases issued from two engines (A) and (B). The engine (A).
is of a type equipped with the feedback type air-fuel mixture supply means with the mixture heating means and the engine (B) is of a type equipped with the feedback type air:fuel mixture supply means without the mixture heating means. From this graph 9 it will be appreciated that the amount of carbon monoxide (C0) issued from the engine (A) with the mixture heating means is remarkably small than that of the engine (B) without such means.
It should be noted that since the air-fuel mixture heating is not made by the exhaust gases, the tempe-rature drop of -the exhaust gases can.not be occured so that the normal functions of the exhaust gas sensor ~7~9'7 and the exhaust gas purifying device are not disturbed.
In conclusion~ by the provision of the air-fuel mixture heating means, the operational response of the feodback type air-fuel mixture supply is remarkably improvad, so that the reduction of the harmful com-pounds in the exhaust gases is tnore accurately achieved.
In the same time, the stable engine operation is not disturbed by the frequent repetition of the accelera-tions and/or the decelerations thereof.
It is to be understood that the invention is not to be limited to the exact construction shown and described and that various changes and modifications~
may be made without departing from the scope of the invention, as described in the appended claims.
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An exhaust gas purifying system for use with an internal combustion engine having intake and exhaust systems thereof, comprising:
an exhaust gas sensor disposed in said exhaust system of the engine for issuing an information signal representing the concentration of a given constituent in the exhaust gases issued from the engine;
electronically controlled air-fuel supply means mounted in said intake system of the engine for supplying an air-fuel mixture in response to a command signal applied thereto;
a control unit electrically connected to said electronically controlled air-fuel mixture supply means and said exhaust gas sensor for issuing a command signal to said air-fuel mixture supply means upon receiving said information signal issued from the exhaust gas sensor; and air-fuel mixture heating means mounted in said intake system of the engine for preheating the mixture passing through the intake system, whereby preferable gasification of the fuel in the mixture is achieved.
an exhaust gas sensor disposed in said exhaust system of the engine for issuing an information signal representing the concentration of a given constituent in the exhaust gases issued from the engine;
electronically controlled air-fuel supply means mounted in said intake system of the engine for supplying an air-fuel mixture in response to a command signal applied thereto;
a control unit electrically connected to said electronically controlled air-fuel mixture supply means and said exhaust gas sensor for issuing a command signal to said air-fuel mixture supply means upon receiving said information signal issued from the exhaust gas sensor; and air-fuel mixture heating means mounted in said intake system of the engine for preheating the mixture passing through the intake system, whereby preferable gasification of the fuel in the mixture is achieved.
2. An exhaust gas purifying system as claimed in Claim 1, further comprising an exhaust gas purifying device which is disposed in said exhaust system down-stream of said exhaust gas sensor.
3. An exhaust gas purifying system as claimed in Claim 1, in which said air-fuel mixture heating means is so arranged to preheat the air-fuel mixture by using the heat developed as a result of the operation of the engine.
4. An exhaust gas purifying system as claimed in Claim 3, in which said air-fuel mixture heating means is so arranged to heat the air-fuel mixture by using the heated cooling water coming out from water jackets formed in a cylinder block of the engine.
5. An exhaust gas purifying system as claimed in Claim 4, in which said air-fuel mixture heating means comprises a heat transfer chamber positioned under the floor portion of an intake manifold of said intake system, said heat transfer chamber being in communica-tion with said water jackets of said cylinder block.
6. An exhaust gas purifying system as claimed in Claim 5, in which said heat transfer chamber is posi-tioned directly under substantially whole floor portion of said intake manifold.
7. An exhaust gas purifying system as claimed in Claim 6, in which said heat transfer chamber has an enlarged section thereof located under a throttle valve rotatably mounted in said intake system.
8. An exhaust gas purifying system as claimed in Claim 7, in which said heat transfer chamber is directly connected to said water jackets of said cylinder block for instantly receiving therein the hot water just coming out from said water jackets.
9. An exhaust gas purifying system as claimed in Claim 2, in which said exhaust gas purifying device is a three-way catalytic converter.
10. An exhaust gas purifying system as claimed in Claim 2, in which said exhaust gas purifying device is an oxidizing catalytic converter.
11. An exhaust gas purifying system as claimed in Claim 2, in which said exhaust gas purifying device is a reducing catalytic converter.
12. An exhaust gas purifying system as claimed in Claim 2, in which said exhaust gas purifying device is a thermal reactor.
13. An exhaust gas purifying system as claimed in Claim 9, 10 or 11, in which said exhaust gas sensor is an oxygen sensor.
14. An exhaust gas purifying system as claimed in Claim 9, 10 or 11, in which said exhaust gas sensor is a hydro-carbon sensor.
15. An exhaust gas purifying system as claimed in Claim 9, 10 or 11, in which said exhaust gas sensor is a carbon monoxide sensor.
16. An exhaust gas purifying system as claimed in Claim 9, 10 or 11, in which said exhaust gas sensor is a carbon dioxide sensor.
17. An exhaust gas purifying system as claimed in Claim 9, 10 or 11, in which said exhaust gas sensor is a nitrogen oxide sensor.
18. An exhaust gas purifying system as claimed in Claim 2, in which said air-fuel mixture heating means comprises a heat transfer chamber positioned directly under the substantially whole floor portion of an intake manifold of said intake system, said heat transfer chamber being in communication with water jackets formed in a cylinder block of said engine.
19. An exhaust gas purifying system as claimed in Claim 18, in which said heat transfer chamber has an enlarged section thereof located under a throttle valve rotatably mounted in said intake system.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1975078303U JPS51157722U (en) | 1975-06-09 | 1975-06-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070197A true CA1070197A (en) | 1980-01-22 |
Family
ID=13658147
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA254,361A Expired CA1070197A (en) | 1975-06-09 | 1976-06-08 | Exhaust gas purifying system with an air-fuel mixture heating means |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS51157722U (en) |
| CA (1) | CA1070197A (en) |
| DE (1) | DE2625822A1 (en) |
| GB (1) | GB1528542A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2703720A1 (en) * | 1977-01-29 | 1978-08-03 | Daimler Benz Ag | DEVICE FOR PREHEATING THE INTAKE MIXTURE OF A CARBURETTOR COMBUSTION ENGINE |
-
1975
- 1975-06-09 JP JP1975078303U patent/JPS51157722U/ja active Pending
-
1976
- 1976-06-08 CA CA254,361A patent/CA1070197A/en not_active Expired
- 1976-06-09 GB GB23823/76A patent/GB1528542A/en not_active Expired
- 1976-06-09 DE DE19762625822 patent/DE2625822A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| JPS51157722U (en) | 1976-12-15 |
| GB1528542A (en) | 1978-10-11 |
| DE2625822A1 (en) | 1976-12-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |