CA1053518A - Internal combustion engine with emission control - Google Patents
Internal combustion engine with emission controlInfo
- Publication number
- CA1053518A CA1053518A CA280,609A CA280609A CA1053518A CA 1053518 A CA1053518 A CA 1053518A CA 280609 A CA280609 A CA 280609A CA 1053518 A CA1053518 A CA 1053518A
- Authority
- CA
- Canada
- Prior art keywords
- engine
- air
- idle
- exhaust
- during
- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/22—Control of additional air supply only, e.g. using by-passes or variable air pump drives
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/30—Arrangements for supply of additional air
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B1/00—Engines characterised by fuel-air mixture compression
- F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
- F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder
- F02B1/06—Methods of operating
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B1/00—Engines characterised by fuel-air mixture compression
- F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
- F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Exhaust Gas After Treatment (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
- Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
Abstract
ENGINE
Abstract of the Disclosure Hydrocarbon and carbon monoxide emission of an internal combustion engine fitted with a non-catalytic thermal exhaust reactor is substantially lowered by operating the engine lean during normal modes of engine operation and switching to rich operation during idle using restricted air injection such that the idle exhaust contains about 2-5 volume percent oxygen.
Abstract of the Disclosure Hydrocarbon and carbon monoxide emission of an internal combustion engine fitted with a non-catalytic thermal exhaust reactor is substantially lowered by operating the engine lean during normal modes of engine operation and switching to rich operation during idle using restricted air injection such that the idle exhaust contains about 2-5 volume percent oxygen.
Description
Case 4174 Canada ~053518 Background During recent years there has been an extensive effort to lower the amount of hydrocarbon and carbon monoxide emitted to the atmosphere by internal combustion engines. Substantial reductions have been achieved by such means as using lean air/fuel mixtures, injecting air into hot exhaust, replacing the exhaust manifold with a thermal reactor or placing a catalytic reactor in the exhaust system.
Use of an exhaust catalyst is generally more effective if the engine is operated on lead-free or low-lead (i.e., tetraethyllead) gasoline. Thermal exhaust reactors are effective no matter what type of gasoline is used. Thus, there are substantial economic benefits which are achieved by use of a thermal reactor rather than a catalytic reactor.
Thermal reactors in which the hot exhaust passes from the exhaust port into an enlarged, usually insulated ,............................................................ .
:, ~
' ' ' chamber are quite effective durine normal modes of engine operation. These are generally used in conj~ln~tion with air injection using lean air/fuel mixtures. One problem encountercd with such ]ean s~stems is that during idle the amount of carbon monoxide in the exhaust is too low to provide sufficient combustion heat to keep the thermal reactor and related hardware at a sufficiently high temperature. Furthermore, if unrestricted air injection is used during all modes of engir.e operation the amount injected at idle can be so excessive that the air cools the exhaust mixture below combustion temperature thus allowing the exhaust passage and thermal reactor to cool.
The result of this is that when the engine shifts into an operating work load the thermal reactor is initially ineffective because of its temperature which permits increased amounts of hydrocarbon and carbon monoxide to be exhausted.
Summary According to the present invention, an internal combustion engine is provided which operates at lean air/fuel ratios with restricted air injection into the exhaust under normal operating modes. However, at idle the inducted air/fuel mixture i6 enriched such that the idle exhaust, in the absence of air injection, would contain about 0.5-1.5 vol percent carbon monoxide. In combination with this idle enrichment, restricted air injection into the idle exhaust is provided such that the resultant idle exhaust after reaction contains only about 2-5 vol percent oxygen. The combination of ¦~ enriched 1 e mixture and limited air lnjection has a
Use of an exhaust catalyst is generally more effective if the engine is operated on lead-free or low-lead (i.e., tetraethyllead) gasoline. Thermal exhaust reactors are effective no matter what type of gasoline is used. Thus, there are substantial economic benefits which are achieved by use of a thermal reactor rather than a catalytic reactor.
Thermal reactors in which the hot exhaust passes from the exhaust port into an enlarged, usually insulated ,............................................................ .
:, ~
' ' ' chamber are quite effective durine normal modes of engine operation. These are generally used in conj~ln~tion with air injection using lean air/fuel mixtures. One problem encountercd with such ]ean s~stems is that during idle the amount of carbon monoxide in the exhaust is too low to provide sufficient combustion heat to keep the thermal reactor and related hardware at a sufficiently high temperature. Furthermore, if unrestricted air injection is used during all modes of engir.e operation the amount injected at idle can be so excessive that the air cools the exhaust mixture below combustion temperature thus allowing the exhaust passage and thermal reactor to cool.
The result of this is that when the engine shifts into an operating work load the thermal reactor is initially ineffective because of its temperature which permits increased amounts of hydrocarbon and carbon monoxide to be exhausted.
Summary According to the present invention, an internal combustion engine is provided which operates at lean air/fuel ratios with restricted air injection into the exhaust under normal operating modes. However, at idle the inducted air/fuel mixture i6 enriched such that the idle exhaust, in the absence of air injection, would contain about 0.5-1.5 vol percent carbon monoxide. In combination with this idle enrichment, restricted air injection into the idle exhaust is provided such that the resultant idle exhaust after reaction contains only about 2-5 vol percent oxygen. The combination of ¦~ enriched 1 e mixture and limited air lnjection has a
-2-substantial effect on increasing t~e amount of sensible heat in the exhaust ystem dur~ng id:le such that when the engine is again placed under normal ~lork load using a lean air/fuel mixture thc thermal reactor is immediately effective in burning exhaust hydrocarbon and carbon monoxide.
Brief Descr~ n_o~
~igure l is a partial cross-section of an engine including the intake and exhaust system.
Figure 2 is a cross-section showing in more detail the exhaust structure.
Description of the referred Embodiments A preferred embodiment of the invention is an improvement in a spark-ignited, internal combustion engine wherein the engine includes air/fuel induction means and means for injecting air into the hot engine exhaust. According to the present improvement the air/fuel induction means provides a lean air/fuel mixture above about 15.5:1 during operation of ; the engine under normal operating modes after warm-up. During idle the air/fuel induction means changes such that it provides a rich air/fuel mixture such that the resultant exhaust gas during idle would containg in the absence of air injection, about 0.5-1.5 vol percent carbon monoxide. Means for restricting air injection into the exhaust gas during idle are provided such that the amount of oxygen in the resultant exhaust gas after ~xidation contains about 2-5 volume percent oxygen.
,'-s ~053518 A fur~her embo~limenl, of this invention is an improvemellt :in a spark-i.grlited, interrlal. co.~bustion engine wherein the engine i.nclude~s means for injecting air into the hot engi.ne exhaust, means for inducting a lean air/fuel mixture having ar~.air/fue] ratio above about 15.5:1 during operation at normal opera-ting temperature and means for enriching the air/fuel mixture ~hi.le the engine is below operating temperature until the engine attains a warmed--up condition. According to this imprGvement air injection on cold start and during warm-up is equal to about 30~60 volume percent of inducted air which is modulated back to about 0-20 volume percent of , inducted air when the engine reaches a predetermined normal ,operating temperature at which temperature lean air/fuel induction resumes, ~.
The embodiment shown in Figures 1 and 2 comprise a ( spark-ignited, internal combustion gasoline engine 1 having .1 a combustion chamber 23 an intake valve 3, and an exhaust ,, valve 4. Intake port 5 connects to intake manifold 6 through :' intake branches 7. Carburetor 10 is mounted on intake manifold 6. Primary barrel 11 includes choke valve 12, main air/fuel .. nozzle 8, throttle plate 13 and idle enrichment nozzle 14, . . which is controlled by needle valve 15.
, Thermal reactor 16 connects to exhaust ports 17 through exhaust branch 18. In Figure 1, the exhaust reactor is an enlarged cast iron housing 19. In Figure 2 reactor 16 is constructed of double-walled sheet metal forming an enlarged reactor chamber. By enlarged is meant that it has more cross-sectional a and volume compared to a conventional exhaust _4_ ~1 .
manifold. Such thermal reactors are well known and are typified by V.S. 3,635,031, U.S. 3,653,205, U.S. 3,703,083 and U.S. 3,751,92n~
In Figure 2, exhaust port 17 is fitted with exhaust port liner 20 which serves to conserve exhaust heat. Air in~ection nozzle 21 extends into exhaust port 17 to a loca-tion proximate to exhaust valve 4. Aix pump 22 supplies air to air injector 21 through air conduit 24, valve 25, valve 26, and air manifold 27. Connected in parallel with valve 25 is by-pass conduit 28, in which is located restrictive orifice 30.
This restrictive orifice may be provided by any small opening such as a needle valve~ a small venturi or nozzle, an inserted plug having a small opening drilled through it, a fitted disc or porous plug or any such equivalent means.
On start-up, valves 25 and 26 are open to supply a ~-full charge of air to exhaust port 17. This is because the carburetor choke valve 12 will be closed and the initial exhaust gas contains large amounts of unburned hydrocarbon and carbon monoxide requiring large amounts of injected air to burn them in the exhaust port and thermal reactor. This full charge of air should be equal to about 30 to 60 vol percent of inducted air. After the engine attains normal operating temperature the carburetor choke valve 12 will open and valve 25 close. Closing of valve 25 can be actuated by an engine temperature sensor or can be interlocked with the choke so that opening of the choke causes valve 25 to close.
When the choke opens the carburetor is then supplying a lean air/fuel mixture to the engine cylinders having an air/fuel ratio above about 15.5:1 and preferably above 16:1.
A large excess of air pb _ 5 _ ~' , . .
105,351~
illjcction dl~rin~r rl~rmaJ engine operat:ion is to be avolded as it; cools the exha~ls~ ar)(l 4ucnches the oxidatlor~. In practice, it has been fourld that with lean air/fuel mixtures, low hydrocarbon and carbon monoxide e~issions can be obtained without any air injection. l~his can be accomplished by mere]y disengaging air pump 22. Alternative]y, valve 26 can be closed after the choke opens. Preferably a small amount of air injection is continued during lean warmed-up operation of the engine. This can be readily provided by continuing the restricted air injection supplied at idle during normal warmed-up operation of the engine. This will be discussed next below. This small amount of air injection is preferably rnetered through an orifice. This orifice will provide air injection during normal warmed-up operation equal to up to about 20 volume percent of inducted air. The range of air injection during normal warmed-up operation of the engine at lean air/fuel ratios is about 0-20 volu~e percent of inducted air and preferably 5-? volume percent.
when the engine comes to idle the air/fuel mix-ture ; 20 supplied to the cylinders is enriched. One means for aecompli~hing this is by adjusting idle valve 1~ so that the ~` exhaust gas in the absenee of any air injection would contair.
about 0. 5-1. 5 vol percent carbon monoxide. Any other means for enriching the air/fuel mixture during idle can be used.
In conjunction with idle enrichment, the air injected into the exhaust ports is restricted by orifice 30.
This restriction is such that the resultant exhaust gas leaving the thermal reactor contains about 2-5 vol percent oxygen.
::`'.
_, . ~
To accomp]-ish th:ir" ~he amount of air injected into the id]e exhaust is ge~lera]]y restricted t;o about 5 to 20 vol percent of the indueted air. Best results have been ach:ieved by restricting air injection to 12-15 vol percent of inducted air at idle. Part of the oxygen in the injected air is consumed in oxidizing hydrocarbons and carbon monoxide such that the resultan-t exhaust gas at idle contains only about 2-5 vol percent oxygen. While injecting restricted air at idle,valve 25 remains closed and valve 26 if closed must then be opened. Alternatively, by-pass conduit 2~ can be eliminated and valve 25 modified such that it still passes a restricted amount of air when in the closed position. This can be accomplished by such means as placing a stop in the valve to prevent complete closure or drilling a small opening through the valve gate such that when valve 25 is open it allows passage of air equal to about 30-60 vol percent of inducted air and when valve 25 is closed it allows passage of air equal to about 5-20 vol percent of inducted air. Valve 25 is then provided with means to cause it to open when the engine is below a pre-determined normal operating temperature and to close when the engine is above a pre-de~ermined operating temperature. The engine will receive full air injection during warm-up and a restricted amount of about 5-20 vol percent of inducted air during remaining periods of engine operation.
Use of enrichment at idle in conjunction with restricted air injection maintains an oxidizing reaction in the exhaust port and thermal reactor even at idle such that .' ~ ' .~
the system temperature does not drop below spontaneous oxidation conditions. This results in immediate f~lnctioning of the oxidizing system when normal lean engine operation resumes. In conventional systems that maintain lean mixtures at idle and/or use unrestricted air injection, the idle exhaust temperature drops to such an extent that the thermal reactor is inoperable during the initial period of subsequent normal engine operation. Lean mixtures during idle do not supply sufficient combustible products in the exhaust.
Unrestricted air injection cools, dilutes and quenches the oxidation reaction during idle.
The present system which provides lean engine operation with 0-20 vol percent air injection during normal ; warmed-up engine operation and a rich idle mixture with restricted air injection during idle results in a sharp drop in exhaust emission as measured by the 1975 Federal CVS
Test Procedure. This is shown in tests conducted with an automobile having a 4-cylinder, 2 liter in-line engine fitted with exhaust port liners, an exhaust thermal reaction and an air/fuel induction system as described in Canadian Patent No.
1,014,439 granted to the present assignee on July 26, 1977.
The carburetor was adjusted to give at 15.5-16:1 air/fuel ratio during normal operation.
In the first series of tests the temperature, hydro-carbon and carbon monoxide of the engine exhaust were measured at idle and various engine speeds without injecting any secondary air. All measurements were made after the engine stabilized at each operating mode. Idle enrichment was provided (notethe volume percent CO at idle)O This test was ~.
~ pb - 8 -¦ for comparat:ive pllrposes an(l was not to demonstrate the present ¦ improvemenl;s since -it did not em~Joy air In~ection even ~uring ¦ idle. The results are shown in Ta~le 1.
I ~able 1 I _ ¦ Without Air _ 1ection I Engine ~peed~ mnh) ¦ idle ]5 _ _ 3~ 50 ¦ Exhaust785 898 945 995 1062 1148 1325 l carbon (ppm) 77 21 16 24 10 10 8 0 (vol. ~0) 1.67 0.35 0.17 0.35 o.o8l~ o.o28 o.o28 ¦In the next test the same sequence was carried out ¦ except that full unmodulated air injection was used. These ¦ results are reported in Table 2.
¦ Table 2 IUnrestricted Secondary Air ¦Engine Speed (m ~
¦ idle 15 20 25 ~0 40 50 Inj.49 58.4 49.7 54.4 51.6 46.8 41.8 Temp.(F)804 839 882 915 980 1055 1244 Hydro-carbon (ppm) 24 25 22 20 15 12 10 C0 (vol.
~o ) (1).507 .174 .150 .154.127.161 .119 ' (1) corrected for dilution by injected air.
In the above tests limited reduction in hydrocarbon and carbon monoxide was achieved at idle, but at other modes no substantial reduction was noted.
In the next test series air injection was restricted by an orifice placed in the air supply conduit such that the '..., ~_ idle e~haust cc-ntairle(l 2.5~/o oxygcn. Air illJection during othcr mo~es ~as restricted by the same orifice. ~l~he;e results ~hich are attributable to the present :invention are shown in Table 3.
Table 3 ~estr:icted_S~condar~ Air _ En~ine .Speed~mPh ) idle 15 20 25 3 -T~o 50 Inj.15.4 12.3 12,4 12.9 11.9 8.8 11.2 Exhaust Ternp. (F)850 905 942 960 1040 1155 1~20 Hydro-carbon (ppm) 18 18 16 14 13 13 1~
C~O)(v(1}Ø1~ .og4 .o63 .o63 .031 .030 .031 corrected for dilution by injected air.
The above results show the substantial reduction of hydrocarbon and very sharp drop in carbon monoxide when using restricted air injection compared to no air or unrestricted air.
The above results were measured after the engine was stabilized at each mode. The benefits attributable to the present invention become even more apparent when emissions are measured under dynamic conditions. These tests were conducted according to the 1975 Federal CVS Test Procedure.
In CVS Test No. 4 the engine was operated lean (air/
fuel ratio 15.5-16:1) except while the choke was on during warm-up. No idle enrichment or air injection was used.
In CVS Test No. 5 the engine was again operated lean except when the choke was on during warm-up. No idle enrichment was used but unrestricted air injection (equal to 40-60 volume percent of 1n~ucted air) was used throughout the test.
. . . .
., .
,. . -10-.. . . .
1~53518 In CVS Test No. 6 the engine was operated 1ean except when the choke ~as on dur.ing warm-llp. I`here was no idle enrichment. Unrestricted alr injection (40-60 volume percent of inducted air) wa~ used during the first 4 minutes of the test (warm-up period). No air injection was used after this.
This test demonstrates the improvement due to one embodiment Or the invention using unrestricted air during warm-up and either none or restricted air after warm-up.
In CVS Test No. 7 the engine was operated lean except when the choke was on during warm-up. Idle enrichment was used to provide 1 percent C0 in the idle exhaust without air injection.
Unrestricted air injection was used during warm-up (40-60 volume percent) and restricted air injection was used during idle such that the idle exhaust contained 2-570 oxygen. The restriction was provided by placing an orifice in the air conduit. This orifice remained in place during the remaining test procedure such that restricted air was provided through the same orifice ¦ during all other warmed-up modes of the test.
¦ The results of the above four CVS tests are shown ¦ in Table 4.
¦ Table 4 ¦1975 Federal CVS Tests ¦Exhaust Emission (~/mi) ¦ Test No. ~ydrocar~on ~ N~
I __ 1 4 o.42 4.68 1.64 o.42 4.19 1.69 6 0.23 2,70 1.6~
7 0.10 2.09 1,81 - ~ 3 I Federal Std. 1.5 15.0 3.4 ¦ Pending :~ I Federal Std. .41 3.4 .41 ,'; , I
~ I -11-I
r~
Test Numbers '~ and 5 are for comparat:ive purposes since they do not show the improvcd features of the preserlt invention.
Test No. 6 shows the sharp reductioll in hydrocarbon and carbon onoxide which can be obtained with only one embodiment of the present invention, that is, unrestricted air injection during warm-up only with none or restricted air af`ter warm-up.
Test No. 7 shows the still further reductions of hydrocarbon and carbon monoxide which can be achieved using a further embodiment of the invention which includes idle O enrichment and restricted air injection during idle. The improvements provided by the present invention readily enable the engine to pass 1976 Federal Emission Standards and to pass the pending statutory hydrocarbon and carbon monoxide standards proposed fo he future.
: ' ..
'~ ~_
Brief Descr~ n_o~
~igure l is a partial cross-section of an engine including the intake and exhaust system.
Figure 2 is a cross-section showing in more detail the exhaust structure.
Description of the referred Embodiments A preferred embodiment of the invention is an improvement in a spark-ignited, internal combustion engine wherein the engine includes air/fuel induction means and means for injecting air into the hot engine exhaust. According to the present improvement the air/fuel induction means provides a lean air/fuel mixture above about 15.5:1 during operation of ; the engine under normal operating modes after warm-up. During idle the air/fuel induction means changes such that it provides a rich air/fuel mixture such that the resultant exhaust gas during idle would containg in the absence of air injection, about 0.5-1.5 vol percent carbon monoxide. Means for restricting air injection into the exhaust gas during idle are provided such that the amount of oxygen in the resultant exhaust gas after ~xidation contains about 2-5 volume percent oxygen.
,'-s ~053518 A fur~her embo~limenl, of this invention is an improvemellt :in a spark-i.grlited, interrlal. co.~bustion engine wherein the engine i.nclude~s means for injecting air into the hot engi.ne exhaust, means for inducting a lean air/fuel mixture having ar~.air/fue] ratio above about 15.5:1 during operation at normal opera-ting temperature and means for enriching the air/fuel mixture ~hi.le the engine is below operating temperature until the engine attains a warmed--up condition. According to this imprGvement air injection on cold start and during warm-up is equal to about 30~60 volume percent of inducted air which is modulated back to about 0-20 volume percent of , inducted air when the engine reaches a predetermined normal ,operating temperature at which temperature lean air/fuel induction resumes, ~.
The embodiment shown in Figures 1 and 2 comprise a ( spark-ignited, internal combustion gasoline engine 1 having .1 a combustion chamber 23 an intake valve 3, and an exhaust ,, valve 4. Intake port 5 connects to intake manifold 6 through :' intake branches 7. Carburetor 10 is mounted on intake manifold 6. Primary barrel 11 includes choke valve 12, main air/fuel .. nozzle 8, throttle plate 13 and idle enrichment nozzle 14, . . which is controlled by needle valve 15.
, Thermal reactor 16 connects to exhaust ports 17 through exhaust branch 18. In Figure 1, the exhaust reactor is an enlarged cast iron housing 19. In Figure 2 reactor 16 is constructed of double-walled sheet metal forming an enlarged reactor chamber. By enlarged is meant that it has more cross-sectional a and volume compared to a conventional exhaust _4_ ~1 .
manifold. Such thermal reactors are well known and are typified by V.S. 3,635,031, U.S. 3,653,205, U.S. 3,703,083 and U.S. 3,751,92n~
In Figure 2, exhaust port 17 is fitted with exhaust port liner 20 which serves to conserve exhaust heat. Air in~ection nozzle 21 extends into exhaust port 17 to a loca-tion proximate to exhaust valve 4. Aix pump 22 supplies air to air injector 21 through air conduit 24, valve 25, valve 26, and air manifold 27. Connected in parallel with valve 25 is by-pass conduit 28, in which is located restrictive orifice 30.
This restrictive orifice may be provided by any small opening such as a needle valve~ a small venturi or nozzle, an inserted plug having a small opening drilled through it, a fitted disc or porous plug or any such equivalent means.
On start-up, valves 25 and 26 are open to supply a ~-full charge of air to exhaust port 17. This is because the carburetor choke valve 12 will be closed and the initial exhaust gas contains large amounts of unburned hydrocarbon and carbon monoxide requiring large amounts of injected air to burn them in the exhaust port and thermal reactor. This full charge of air should be equal to about 30 to 60 vol percent of inducted air. After the engine attains normal operating temperature the carburetor choke valve 12 will open and valve 25 close. Closing of valve 25 can be actuated by an engine temperature sensor or can be interlocked with the choke so that opening of the choke causes valve 25 to close.
When the choke opens the carburetor is then supplying a lean air/fuel mixture to the engine cylinders having an air/fuel ratio above about 15.5:1 and preferably above 16:1.
A large excess of air pb _ 5 _ ~' , . .
105,351~
illjcction dl~rin~r rl~rmaJ engine operat:ion is to be avolded as it; cools the exha~ls~ ar)(l 4ucnches the oxidatlor~. In practice, it has been fourld that with lean air/fuel mixtures, low hydrocarbon and carbon monoxide e~issions can be obtained without any air injection. l~his can be accomplished by mere]y disengaging air pump 22. Alternative]y, valve 26 can be closed after the choke opens. Preferably a small amount of air injection is continued during lean warmed-up operation of the engine. This can be readily provided by continuing the restricted air injection supplied at idle during normal warmed-up operation of the engine. This will be discussed next below. This small amount of air injection is preferably rnetered through an orifice. This orifice will provide air injection during normal warmed-up operation equal to up to about 20 volume percent of inducted air. The range of air injection during normal warmed-up operation of the engine at lean air/fuel ratios is about 0-20 volu~e percent of inducted air and preferably 5-? volume percent.
when the engine comes to idle the air/fuel mix-ture ; 20 supplied to the cylinders is enriched. One means for aecompli~hing this is by adjusting idle valve 1~ so that the ~` exhaust gas in the absenee of any air injection would contair.
about 0. 5-1. 5 vol percent carbon monoxide. Any other means for enriching the air/fuel mixture during idle can be used.
In conjunction with idle enrichment, the air injected into the exhaust ports is restricted by orifice 30.
This restriction is such that the resultant exhaust gas leaving the thermal reactor contains about 2-5 vol percent oxygen.
::`'.
_, . ~
To accomp]-ish th:ir" ~he amount of air injected into the id]e exhaust is ge~lera]]y restricted t;o about 5 to 20 vol percent of the indueted air. Best results have been ach:ieved by restricting air injection to 12-15 vol percent of inducted air at idle. Part of the oxygen in the injected air is consumed in oxidizing hydrocarbons and carbon monoxide such that the resultan-t exhaust gas at idle contains only about 2-5 vol percent oxygen. While injecting restricted air at idle,valve 25 remains closed and valve 26 if closed must then be opened. Alternatively, by-pass conduit 2~ can be eliminated and valve 25 modified such that it still passes a restricted amount of air when in the closed position. This can be accomplished by such means as placing a stop in the valve to prevent complete closure or drilling a small opening through the valve gate such that when valve 25 is open it allows passage of air equal to about 30-60 vol percent of inducted air and when valve 25 is closed it allows passage of air equal to about 5-20 vol percent of inducted air. Valve 25 is then provided with means to cause it to open when the engine is below a pre-determined normal operating temperature and to close when the engine is above a pre-de~ermined operating temperature. The engine will receive full air injection during warm-up and a restricted amount of about 5-20 vol percent of inducted air during remaining periods of engine operation.
Use of enrichment at idle in conjunction with restricted air injection maintains an oxidizing reaction in the exhaust port and thermal reactor even at idle such that .' ~ ' .~
the system temperature does not drop below spontaneous oxidation conditions. This results in immediate f~lnctioning of the oxidizing system when normal lean engine operation resumes. In conventional systems that maintain lean mixtures at idle and/or use unrestricted air injection, the idle exhaust temperature drops to such an extent that the thermal reactor is inoperable during the initial period of subsequent normal engine operation. Lean mixtures during idle do not supply sufficient combustible products in the exhaust.
Unrestricted air injection cools, dilutes and quenches the oxidation reaction during idle.
The present system which provides lean engine operation with 0-20 vol percent air injection during normal ; warmed-up engine operation and a rich idle mixture with restricted air injection during idle results in a sharp drop in exhaust emission as measured by the 1975 Federal CVS
Test Procedure. This is shown in tests conducted with an automobile having a 4-cylinder, 2 liter in-line engine fitted with exhaust port liners, an exhaust thermal reaction and an air/fuel induction system as described in Canadian Patent No.
1,014,439 granted to the present assignee on July 26, 1977.
The carburetor was adjusted to give at 15.5-16:1 air/fuel ratio during normal operation.
In the first series of tests the temperature, hydro-carbon and carbon monoxide of the engine exhaust were measured at idle and various engine speeds without injecting any secondary air. All measurements were made after the engine stabilized at each operating mode. Idle enrichment was provided (notethe volume percent CO at idle)O This test was ~.
~ pb - 8 -¦ for comparat:ive pllrposes an(l was not to demonstrate the present ¦ improvemenl;s since -it did not em~Joy air In~ection even ~uring ¦ idle. The results are shown in Ta~le 1.
I ~able 1 I _ ¦ Without Air _ 1ection I Engine ~peed~ mnh) ¦ idle ]5 _ _ 3~ 50 ¦ Exhaust785 898 945 995 1062 1148 1325 l carbon (ppm) 77 21 16 24 10 10 8 0 (vol. ~0) 1.67 0.35 0.17 0.35 o.o8l~ o.o28 o.o28 ¦In the next test the same sequence was carried out ¦ except that full unmodulated air injection was used. These ¦ results are reported in Table 2.
¦ Table 2 IUnrestricted Secondary Air ¦Engine Speed (m ~
¦ idle 15 20 25 ~0 40 50 Inj.49 58.4 49.7 54.4 51.6 46.8 41.8 Temp.(F)804 839 882 915 980 1055 1244 Hydro-carbon (ppm) 24 25 22 20 15 12 10 C0 (vol.
~o ) (1).507 .174 .150 .154.127.161 .119 ' (1) corrected for dilution by injected air.
In the above tests limited reduction in hydrocarbon and carbon monoxide was achieved at idle, but at other modes no substantial reduction was noted.
In the next test series air injection was restricted by an orifice placed in the air supply conduit such that the '..., ~_ idle e~haust cc-ntairle(l 2.5~/o oxygcn. Air illJection during othcr mo~es ~as restricted by the same orifice. ~l~he;e results ~hich are attributable to the present :invention are shown in Table 3.
Table 3 ~estr:icted_S~condar~ Air _ En~ine .Speed~mPh ) idle 15 20 25 3 -T~o 50 Inj.15.4 12.3 12,4 12.9 11.9 8.8 11.2 Exhaust Ternp. (F)850 905 942 960 1040 1155 1~20 Hydro-carbon (ppm) 18 18 16 14 13 13 1~
C~O)(v(1}Ø1~ .og4 .o63 .o63 .031 .030 .031 corrected for dilution by injected air.
The above results show the substantial reduction of hydrocarbon and very sharp drop in carbon monoxide when using restricted air injection compared to no air or unrestricted air.
The above results were measured after the engine was stabilized at each mode. The benefits attributable to the present invention become even more apparent when emissions are measured under dynamic conditions. These tests were conducted according to the 1975 Federal CVS Test Procedure.
In CVS Test No. 4 the engine was operated lean (air/
fuel ratio 15.5-16:1) except while the choke was on during warm-up. No idle enrichment or air injection was used.
In CVS Test No. 5 the engine was again operated lean except when the choke was on during warm-up. No idle enrichment was used but unrestricted air injection (equal to 40-60 volume percent of 1n~ucted air) was used throughout the test.
. . . .
., .
,. . -10-.. . . .
1~53518 In CVS Test No. 6 the engine was operated 1ean except when the choke ~as on dur.ing warm-llp. I`here was no idle enrichment. Unrestricted alr injection (40-60 volume percent of inducted air) wa~ used during the first 4 minutes of the test (warm-up period). No air injection was used after this.
This test demonstrates the improvement due to one embodiment Or the invention using unrestricted air during warm-up and either none or restricted air after warm-up.
In CVS Test No. 7 the engine was operated lean except when the choke was on during warm-up. Idle enrichment was used to provide 1 percent C0 in the idle exhaust without air injection.
Unrestricted air injection was used during warm-up (40-60 volume percent) and restricted air injection was used during idle such that the idle exhaust contained 2-570 oxygen. The restriction was provided by placing an orifice in the air conduit. This orifice remained in place during the remaining test procedure such that restricted air was provided through the same orifice ¦ during all other warmed-up modes of the test.
¦ The results of the above four CVS tests are shown ¦ in Table 4.
¦ Table 4 ¦1975 Federal CVS Tests ¦Exhaust Emission (~/mi) ¦ Test No. ~ydrocar~on ~ N~
I __ 1 4 o.42 4.68 1.64 o.42 4.19 1.69 6 0.23 2,70 1.6~
7 0.10 2.09 1,81 - ~ 3 I Federal Std. 1.5 15.0 3.4 ¦ Pending :~ I Federal Std. .41 3.4 .41 ,'; , I
~ I -11-I
r~
Test Numbers '~ and 5 are for comparat:ive purposes since they do not show the improvcd features of the preserlt invention.
Test No. 6 shows the sharp reductioll in hydrocarbon and carbon onoxide which can be obtained with only one embodiment of the present invention, that is, unrestricted air injection during warm-up only with none or restricted air af`ter warm-up.
Test No. 7 shows the still further reductions of hydrocarbon and carbon monoxide which can be achieved using a further embodiment of the invention which includes idle O enrichment and restricted air injection during idle. The improvements provided by the present invention readily enable the engine to pass 1976 Federal Emission Standards and to pass the pending statutory hydrocarbon and carbon monoxide standards proposed fo he future.
: ' ..
'~ ~_
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a spark-ignited, internal combustion engine, said engine including air/fuel induction means and means for injecting air into the hot exhaust gas of said engine, the improvement comprising means for inducting a lean air/
fuel mixture into the engine cylinders, said lean mixture having an air/fuel ratio above about 15.5:1 during normal operation of the engine after warm-up, means for inducting a rich air/fuel mixture into the engine cylinders during idle, said rich mixture being such that the resultant idle exhaust gas without air injection would contain about 0.5-1.5 volume percent carbon monoxide, and means for restricting air injection into the exhaust gas during engine idle such that the amount of oxygen in the resultant exhaust gas during idle contains about 2-5 volume percent oxygen.
fuel mixture into the engine cylinders, said lean mixture having an air/fuel ratio above about 15.5:1 during normal operation of the engine after warm-up, means for inducting a rich air/fuel mixture into the engine cylinders during idle, said rich mixture being such that the resultant idle exhaust gas without air injection would contain about 0.5-1.5 volume percent carbon monoxide, and means for restricting air injection into the exhaust gas during engine idle such that the amount of oxygen in the resultant exhaust gas during idle contains about 2-5 volume percent oxygen.
2. An engine of Claim 1 wherein said means for in-jecting air delivers said air proximate to the engine exhaust valves.
3. An engine of Claim 2 including a liner in the exhaust port of said engine.
4. An engine of Claim 1 including an exhaust thermal reactor, said reactor comprising an enlarged housing connected by conduits to each engine exhaust port to receive the exhausted gas.
5. An engine of Claim 4 wherein said means for injecting air delivers said air proximate to the engine exhaust valves.
6. An engine of Claim 5 including a liner in the exhaust ports of said engine.
7. An engine of Claim 6 wherein said air/fuel induction means inducts a rich mixture during idle such that the resultant idle exhaust gas without air injection would contain about one percent carbon monoxide and wherein said air/fuel induction means inducts a lean mixture having an air/fuel ratio above about 15.5:1 during remaining periods of normal warmed-up operation of said engine.
8. An engine of Claim 6 wherein said means for restricting air injection during idle comprises a restric-tive orifice in the air induction conduit, said orifice being sized such that during idle the resultant engine exhaust gas contains about 2-5 weight percent oxygen.
9. An engine of Claim 8 wherein said means for injecting air injects an unrestricted amount of air into the exhaust during the initial period of engine operation during engine warm-up, said unrestricted amount being about 30-60 vol percent of the inducted air, and wherein during remaining periods of engine operation said air injection means includes said restrictive orifice.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70109776A | 1976-06-30 | 1976-06-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1053518A true CA1053518A (en) | 1979-05-01 |
Family
ID=24816065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,609A Expired CA1053518A (en) | 1976-06-30 | 1977-06-15 | Internal combustion engine with emission control |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5334005A (en) |
| AU (1) | AU513582B2 (en) |
| BR (1) | BR7704184A (en) |
| CA (1) | CA1053518A (en) |
| DE (1) | DE2729438A1 (en) |
| FR (1) | FR2356817A1 (en) |
| GB (1) | GB1556922A (en) |
| IT (1) | IT1079868B (en) |
| SE (1) | SE7707555L (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5865474U (en) * | 1981-10-28 | 1983-05-04 | 松下電器産業株式会社 | electric valve |
| JPS6263280A (en) * | 1985-09-11 | 1987-03-19 | Kawaden Kiki Seisakusho:Kk | Motor-operated valve |
| JPS62124376U (en) * | 1986-01-30 | 1987-08-07 |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4532963Y1 (en) * | 1967-12-06 | 1970-12-16 | ||
| JPS5129254B2 (en) * | 1972-04-11 | 1976-08-24 | ||
| NL175480C (en) * | 1974-06-12 | 1984-11-01 | Philips Nv | ELECTRODE FOR A DISCHARGE LAMP, METHOD FOR MANUFACTURING SUCH ELECTRODE AND DISCHARGE LAMP PROVIDED WITH SUCH ELECTRODE. |
| JPS5433325B2 (en) * | 1974-09-12 | 1979-10-19 | ||
| JPS5141107A (en) * | 1974-10-03 | 1976-04-06 | Nissan Motor | |
| FR2291360A1 (en) * | 1974-11-13 | 1976-06-11 | Nissan Motor | INTERNAL COMBUSTION ENGINE IMPROVEMENTS |
-
1977
- 1977-06-15 CA CA280,609A patent/CA1053518A/en not_active Expired
- 1977-06-21 GB GB25983/77A patent/GB1556922A/en not_active Expired
- 1977-06-27 BR BR7704184A patent/BR7704184A/en unknown
- 1977-06-29 FR FR7719977A patent/FR2356817A1/en not_active Withdrawn
- 1977-06-29 DE DE19772729438 patent/DE2729438A1/en active Pending
- 1977-06-29 SE SE7707555A patent/SE7707555L/en not_active Application Discontinuation
- 1977-06-29 IT IT50049/77A patent/IT1079868B/en active
- 1977-06-30 JP JP7845577A patent/JPS5334005A/en active Pending
- 1977-06-30 AU AU26658/77A patent/AU513582B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1556922A (en) | 1979-12-05 |
| SE7707555L (en) | 1977-12-31 |
| IT1079868B (en) | 1985-05-13 |
| DE2729438A1 (en) | 1978-01-12 |
| BR7704184A (en) | 1978-03-28 |
| FR2356817A1 (en) | 1978-01-27 |
| AU2665877A (en) | 1979-01-04 |
| AU513582B2 (en) | 1980-12-11 |
| JPS5334005A (en) | 1978-03-30 |
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