JP2601072B2 - Internal combustion engine, operating method thereof, and automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine provided with a means for purifying exhaust gas discharged from an engine. The present invention also relates to an operation method of an internal combustion engine capable of improving exhaust gas purification performance and an automobile provided with exhaust gas purification means.

[0002]

2. Description of the Related Art Carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and the like contained in exhaust gas discharged from an internal combustion engine not only have an adverse effect on the human body as air pollutants, but also have an adverse effect on plants. It causes problems such as hindering growth.

Therefore, a great deal of effort has conventionally been made to reduce these emissions, and a method for reducing the amount of generated gas by improving the structure and combustion conditions of the internal combustion engine, or the exhaust gas discharged from the internal combustion engine, has been used. Technical development has been promoted from both aspects of a post-treatment method for purifying methane with a catalyst or the like.

[0004] Among them, the catalyst system is provided with an exhaust gas purifying catalyst in a flow path of an engine exhaust gas to provide carbon monoxide (CO),
It oxidizes or reduces harmful gases such as hydrocarbons (HC) and nitrogen oxides (NOx). Japanese Patent Application Laid-Open No. 48-58215 discloses an example of a conventional catalyst system in which a first catalyst is provided at a position as close as possible to an engine in an engine exhaust gas flow path, and a second catalyst is provided at a subsequent stage to provide a catalyst at the beginning of engine startup. It shows that the exhaust gas purification performance at low temperatures is enhanced.

[0005] The catalyst becomes highly active only when it is heated to a temperature higher than a predetermined value. This temperature is usually 250
To 400 DEG C., which is described in, for example, JP-A-54-16018. When the engine is started, the temperature of the exhaust gas is low, and low-temperature exhaust gas is led to the catalyst, so that the function of the catalyst cannot be sufficiently brought out. The above prior art discloses a method for improving exhaust gas purification performance when the catalyst temperature at the start of the engine is low.

[0006]

The temperature of the exhaust gas of the engine of the internal combustion engine gradually rises after the engine is started, but it takes about two minutes or longer until the temperature of the exhaust gas rises to a temperature at which the catalyst can function effectively. It takes more. One theory is that it takes 3 to 5 minutes, which is disclosed in Japanese Patent Application Laid-Open No. 54-79319. How to improve the purification performance of exhaust gas during the period from the start of the engine to the temperature at which the catalyst becomes active will determine the success or failure of the catalyst system.

SUMMARY OF THE INVENTION An object of the present invention is to provide an internal combustion engine and an engine starting method in which the catalytic conversion of unburned fuel and partial combustion components discharged immediately after the engine is started is enhanced.

[0008]

According to the present invention, there is provided an air-fuel ratio control unit for controlling the amounts of fuel and air in an intake system of an engine ,
Air supply means in front of exhaust system, exhaust gas purification in rear
In an internal combustion engine having a use three-way catalyst, before the exhaust system
Downstream of the air supply means and upstream of the three-way catalyst
A pre-catalyst comprising a combustion catalyst on the side, wherein the air-fuel ratio control unit
Of the air-fuel ratio A / F (A is the weight of air, F is the weight of fuel)
Temperature at which the three-way catalyst becomes active after the engine starts
Until the temperature rises to 13, the excess fuel exceeds the stoichiometric air-fuel ratio.
Below and at a value of 10 or more, a temperature at which the three-way catalyst exhibits activity
After the temperature rises, set to the stoichiometric air-fuel ratio,
The air-fuel ratio of the air-fuel ratio control unit is set
Air is supplied from the air supply means during the specified period.
That's what I did .

The composition of the engine exhaust gas varies depending on the operating conditions of the engine, especially the air-fuel ratio. If the engine is operated with a fuel excess of the stoichiometric air-fuel ratio, a large amount of carbon monoxide is generated and a relatively large amount of hydrocarbons is generated. Will occur.
It should be noted here that when the air-fuel ratio is smaller than the theoretical value, that is, when the fuel is excessive, the exhaust gas contains a large amount of CO of several% to several tens%, far exceeding the concentration of HC. . CO can be catalyzed at much lower temperatures than HC.

In the present invention, the heat generated by catalytic combustion of CO is used for raising the temperature of the catalyst and the exhaust gas. But HC
Although the concentration of is lower than that of CO, the calorific value per unit weight of HC is as large as about 5 times that of CO. Therefore, if the catalytic combustion of HC is added to the catalytic combustion of low-temperature CO, the temperature of the catalyst and the exhaust gas can be rapidly increased. Operating the engine with an excess of fuel over the stoichiometric air-fuel ratio generates a greater amount of CO and HC than operating at the stoichiometric air-fuel ratio. Desirable.

It is not preferable from the viewpoint of fuel efficiency to keep operating the engine in a state where the fuel is more than the stoichiometric air-fuel ratio. Further, the temperature of the catalyst becomes too high, and there is a problem in terms of heat resistance. Therefore, if the temperature of the catalyst rises, it is desirable to switch to engine operation at the stoichiometric air-fuel ratio.

In the present invention, the term "internal combustion engine" means a device that explodes and burns fuel in a cylinder and converts fluid energy into mechanical energy by the energy. INDUSTRIAL APPLICABILITY The present invention is suitable to be applied to an internal combustion vehicle driven by an internal combustion engine as a power source, such as a gasoline car or a diesel car.

The present invention can be achieved by adopting the following configurations.

(I) The temperature of the three-way catalyst for purifying exhaust gas is
Temperature detection means, and based on this detected temperature,
The air-fuel ratio A / F of the fuel ratio control unit (A is air weight, F is fuel weight
Amount). That is, after starting the engine,
Until the temperature of the medium reaches the active temperature,
The air-fuel ratio A / F of the ratio control unit (A is air weight, F is fuel weight
Volume) is set to 13 or less and 10 or more, and the temperature of the three-way catalyst is set.
When the temperature reaches a temperature that indicates activity, the air-fuel ratio
Set the fuel ratio to the stoichiometric air-fuel ratio.

[0015]

The air-fuel ratio A / F (A is the weight of air, F is the weight of fuel) in an excess fuel state is 13 or less and 10 or more . This
, The CO concentration of the engine exhaust gas increases from 3% to 14% and the HC concentration also increases.
Because it is relatively large, it is a pre-catalyst even at low exhaust gas temperatures
Catalytic combustion by the combustion catalyst occurs quickly, and the exhaust gas temperature
To a temperature at which the three-way catalyst becomes active.
Can be reached.

The stoichiometric air-fuel ratio is determined by the effective amount of HC and C
An air-fuel ratio for oxidizing O and reducing NO. Generally, A / F = 14.7 or a value close to it is selected.

[0018]

In the present invention, for example, it is desirable to provide an exhaust gas purifying main catalyst under the floor of an automobile and to provide a pre-catalyst comprising a combustion catalyst at a position as close as possible to the engine.
The temperature of the engine exhaust gas decreases as it flows through the exhaust gas passage. By providing the pre-catalyst at a position as close as possible to the engine, the exhaust gas can be guided to the catalyst before the exhaust gas temperature decreases. Further, by using the pre-catalyst as a combustion catalyst, the oxidation activity of CO and HC can be increased.

(Ii) Upstream of the front catalyst from the exhaust gas passage
Is provided with air supply means.

Oxygen in exhaust gas produced by combustion under excess fuel conditions is generally low in concentration. Therefore, by adding an oxygen-containing gas such as air to the front stage of the pre-catalyst, the combustion of CO and HC in the pre-catalyst is effectively performed.

The (iii) The The supply amount of the oxygen of the air supply means, it is desirable that the excess of the theoretical oxygen consumption and equivalents or equivalent of the exhaust gas. In this case, both the combustion in the pre-catalyst and the purification of the exhaust gas in the three-way catalyst as the main catalyst can be favorably performed.

As the pre-catalyst, it is desirable to use a combustion catalyst having activity for both oxidation of CO and oxidation of HC. Specifically, as the catalytically active component, group VIII of the periodic table, Ib
It is preferable to use at least one of metals or oxides selected from group III, rare earth metals, zinc and tin.

The main catalysts for purifying exhaust gas include CO and HC.
It is desirable to use a three-way catalyst that is active in both oxidation and reduction of NOx.

A so-called ceramic honeycomb made of cordierite, mullite, aluminum titanate or the like is used as a support for the pre-catalyst, and the above-mentioned catalytically active component is supported on the honeycomb. It is desirable to attach a porous carrier such as titania and further carry the above-mentioned catalytically active component. In the present invention, it is important to rapidly heat and activate the pre-catalyst itself by effectively utilizing the heat generated by the catalytic combustion of the pre-catalyst. This can be achieved by reducing the heat transfer coefficient of the catalyst carrier or support and increasing the temperature gradient between the catalyst and the carrier or support. The heat transfer coefficient of the above-mentioned ceramics is small and effectively functions to rapidly raise the temperature of the catalyst.

As a support for the precatalyst, a honeycomb made of a conductive metal such as stainless steel or an alloy can be used.

Rapid heating of the catalyst can also be achieved by reducing the specific heat of the catalyst support or support. By using a honeycomb made of metal such as stainless steel as a support for the catalyst, the specific heat of the material itself can be reduced, and the material can be made thinner. As a result, the heat capacity can be reduced and the temperature can be rapidly increased. .

[0028]

[0029]

[0030]

[0031]

(Iv) The amount of fuel and air in the intake system of the engine
Air-fuel ratio control unit for controlling the
Catalyst for exhaust gas purification and temperature detection and detection of the three-way catalyst
Means, and after the engine starts, the temperature detecting means
The temperature of the detected three-way catalyst reaches the temperature at which activity is detected.
Until the air-fuel ratio of the air-fuel ratio controller is
And the air supply means
Supply air, and bring the temperature of the three-way catalyst to a temperature at which activity is exhibited.
After that, the air-fuel ratio of the air-fuel ratio controller is changed to the stoichiometric air-fuel ratio.
And supply of air from the air supply means.
In the method for operating an internal combustion engine which is configured to be stopped,
The three-way catalyst downstream of the air supply means in the exhaust system
A pre-catalyst consisting of a combustion catalyst is provided upstream of
After starting the engine, the temperature of the three-way catalyst shows activity
Until the temperature is reached, the air-fuel ratio A of the air-fuel ratio control unit
/ F (A is air weight, F is fuel weight) 13 or less, 10
Operate with the above settings.

[0033]

[0034]

[0035]

(V) A bypass is provided in the exhaust system of the engine.
And a three-way catalyst consisting of a combustion catalyst
You. And excess fuel is supplied than the stoichiometric air-fuel ratio.
Exhaust gas to the three-way catalyst through the bypass
If the excess fuel supply is stopped, the bypass
Exhaust gas is allowed to flow directly to the three-way catalyst without passing through the
Switch the gas gas flow path .

If the pre-catalyst functions for a short time (approximately 2 minutes) immediately after startup, the pre-catalyst becomes essentially unnecessary. Even after it becomes unnecessary, flowing exhaust gas unnecessarily increases pressure loss. Exposure of the pre-catalyst to a high temperature for a long time also brings about a cause of catalyst deterioration. A bypass is provided in the flow path of exhaust gas from the engine to the main catalyst, a pre-catalyst is provided in the bypass, and excess fuel is burned only immediately after the engine starts and only when the main catalyst has not reached the operating temperature, and the exhaust gas is bypassed. These problems can be eliminated by leading to the main catalyst via the pre-catalyst.

It is also desirable to provide a dehumidifying means, preferably a cooling dehumidifier, in the exhaust gas flow path between the engine and the precatalyst. When the temperature of the precatalyst is equal to or lower than the dew point of the exhaust gas, it is desirable that the exhaust gas is dehumidified by the dehumidifying means, for example, cooled and dehumidified to a temperature equal to or lower than the precatalyst temperature, and then supplied to the precatalyst.

Engine exhaust gas usually contains a large amount of water vapor. When exhaust gas containing water vapor is supplied to the pre-catalyst and the pre-catalyst temperature is low, more precisely, when the temperature of the pre-catalyst is lower than the dew point of the exhaust gas, the moisture in the exhaust gas condenses on the catalyst or in the catalyst pores. . This phenomenon not only deteriorates the performance of the catalyst but also causes deterioration of the catalyst, and also increases the pressure loss. Furthermore, once condensation has occurred, latent heat of vaporization is required to evaporate it.
A large amount of heat is required to raise the temperature as described above, and thus it takes time. Dehumidifying the exhaust gas, for example, cooling and dehumidifying to a temperature equal to or lower than the pre-catalyst temperature,
By subsequently supplying the pre-catalyst, the condensation of water vapor in the pre-catalyst section can be prevented, and the accompanying trouble can be avoided. (Vi) the (v) a gas dehumidifying means to the bypass passage is provided in, the three-way catalyst is a main catalyst after dehumidified exhaust gas by dehumidifying means of the bypass when the temperature of the front catalyst is below the dew point of the combustion exhaust gas When the temperature of the pre-catalyst is equal to or higher than the dew point of the exhaust gas, the exhaust gas is directly guided to the pre-catalyst.

If the temperature of the pre-catalyst is equal to or higher than the dew point of the exhaust gas, there is no possibility of water condensation. Dehumidifying the exhaust gas in this state is an unnecessary operation. Therefore, a bypass is provided in the flow path of the exhaust gas from the engine to the main catalyst, an exhaust gas dehumidifying means is provided in the bypass, and the exhaust gas is dehumidified by the dehumidifying means of the bypass when the temperature of the pre-catalyst is equal to or lower than the dew point of the exhaust gas. By guiding the exhaust gas directly to the pre-catalyst when the temperature of the pre-catalyst is equal to or higher than the dew point of the exhaust gas, it is possible to eliminate water condensation in the pre-catalyst and unnecessary troubles without performing unnecessary dehumidification. .

An example in which fuel is supplied to the engine in excess of the stoichiometric air-fuel ratio is disclosed in JP-A-61-58912. However, they do not consider exhaust gas measures at the start of the engine.

[0042]

Hereinafter, the present invention will be described in detail with reference to specific examples. However, the present invention is not limited to the following examples.

FIG. 1 is a schematic diagram of an internal combustion engine according to one embodiment of the present invention. A front catalyst 2 and a main catalyst 3 are provided in an exhaust gas passage 11 of the engine 1. An air amount adjusting valve 8 and a fuel supply valve 9 are attached to an intake pipe 4 of the engine 1. The air amount adjusting valve 8 and the fuel supply valve 9 are connected to an air-fuel ratio control unit (A
/ F control section 10 controls the opening / closing degree. A secondary air supply pipe 6 for supplying an oxidizing agent (air) is provided in the exhaust gas flow path 11 at a stage before the pre-catalyst 2, and the secondary air supply pipe 6 is provided with an air pump. A temperature sensor 7 is provided downstream of the main catalyst 3 so as to detect the temperature of the exhaust gas. The detected temperature is communicated to the air-fuel ratio control unit (A / F control unit) 10, and the air-fuel ratio control unit 10 determines whether to continue or stop the excessive fuel operation based on the temperature. ing.

FIG. 2 shows the relationship between the air-fuel ratio and the composition of exhaust gas in a gasoline engine.

FIG. 3 is a schematic view showing another example of the internal combustion engine according to the present invention. A bypass flow path 20 is provided in the engine exhaust gas flow path 11, and a pre-catalyst 2 is provided in the bypass flow path. Also, a valve 1 is provided to switch the flow of exhaust gas.
2 and valve 21 are provided. The temperature sensor 7 detects the temperature of the exhaust gas at the outlet of the main catalyst and outputs a temperature signal to the A / F controller 10.
To the valve 2 when the temperature is lower than the operating temperature of the main catalyst.
1 is closed, the valve 12 is opened, and the exhaust gas is
To the pre-catalyst 2, and at the same time, controls the air amount regulating valve 8 and the fuel supply valve 9 to perform combustion with excess fuel. If the temperature is equal to or higher than the operating temperature of the main catalyst, the valve 21 is opened and the valve 12 is opened.
Is closed and the exhaust gas is directly led to the main catalyst 3, and at the same time, the air amount regulating valve 8 and the fuel supply valve 9 are controlled to perform combustion under conditions close to the stoichiometric air-fuel ratio.

FIG. 4 is a schematic diagram showing an internal combustion engine according to still another embodiment of the present invention. A bypass flow path 20 is provided in the engine exhaust gas flow path 11, and the bypass flow path 2
0 is provided with a dehumidifier 15. Further, valves 13 and 14 are provided to switch the flow of the exhaust gas. A temperature sensor 16 was provided in the pre-catalyst 2. When the temperature of the pre-catalyst is lower than the dew point of the flue gas, the exhaust gas is dehumidified by the dehumidifier 15 in the bypass passage 20 and then guided to the main catalyst. When the temperature of the pre-catalyst is higher than the dew point of the flue gas, the exhaust gas is directly discharged. Lead to pre-catalyst.

COMPARATIVE EXAMPLE 1 A ceramic (cordierite) honeycomb having a volume of 1 liter and an opening ratio of 76% was coated on the pre-catalyst 2 with alumina, and palladium (Pd) was added with 0.5% by weight (hereinafter referred to as w).
It is called t%. ) Using a charge of lifting the catalyst, volume 2 to the main catalyst 3
A liter of a catalyst having Pd supported on a ceramic honeycomb having the same material and the same structure was used, and gasoline engine exhaust gas was circulated through the series. CO7 volume% (squid vol%) obtained by burning with an air-fuel ratio (A / F) of 12
That. ), When 0.35 vol% of HC exhaust gas was led to the pre-catalyst 2 at a flow rate of 1000 l / min, the pre-catalyst outlet temperature reached 300 ° C after 63 seconds, and the outlet temperature of the main catalyst 7 reached 300 ° C after 135 seconds. Reached.

Comparative Example 2 CO obtained by burning at an air-fuel ratio of 14.5 close to the stoichiometric air-fuel ratio
When 0.9 vol% and HC 0.2 vol% exhaust gas were introduced into the pre-catalyst 2 at a flow rate of 1000 liter / min, the pre-catalyst outlet temperature reached 300 ° C. after 87 seconds, and the main catalyst 3 outlet temperature was 170 seconds. Later, 300 ° C. was reached.

Example 1 To the exhaust gas generated under the same pre-catalyst and main catalyst as in Comparative Example 1 and under the same combustion conditions (A / F = 12), 380 l / min of air was added before the pre-catalyst. The catalyst outlet temperature reached 300 ° C. after 40 seconds and the outlet temperature of the main catalyst reached 300 ° C. after 87 seconds.

Example 2 Under the same conditions as in Example 1 , the time required to reach the pre-catalyst outlet temperature of 300 ° C. was measured using various catalysts, and the results shown in Table 1 were obtained. A ceramic honeycomb was used as a support for the pre-catalyst and the main catalyst, and was coated with alumina to support the catalytically active components shown in Table 1.

[0051]

[Table 1]

Example 3 Under the same conditions as in Example 1 , for Pd and Pt supported on various porous carriers and supports, the time required to reach a pre-catalyst outlet temperature of 300 ° C. was measured. I got

[0053]

[Table 2]

Example 4 As a pre-catalyst, 0.5% of Pd was added to a honeycomb of a 0.05% thick ferrite stainless steel plate having a porosity of 90%.
When the catalyst heating rate was measured under the same conditions as in Example 1 using the catalyst loaded with t%, the pre-catalyst outlet temperature reached 300 ° C. in 36 seconds, and the main catalyst outlet temperature reached 300 ° C. in 83 seconds. .

[0055]

[0056]

According to the present invention described above, it is possible to purify unburned fuel and partial combustion components discharged immediately after the start of the engine of the internal combustion engine. In particular, the temperature of the pre-catalyst is quickly raised by oxidizing the exhaust gas of an engine operated with excess fuel over the stoichiometric air-fuel ratio with the pre-catalyst, and the main catalyst provided downstream of the pre-catalyst is quickly activated. Temperature can be increased to the formation temperature. As a result, it is possible to enhance the exhaust gas purification performance at the time of exhaustion at the start of the engine of the internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an internal combustion engine of the present invention.

FIG. 2 is a graph showing a relationship between an air-fuel ratio and an exhaust gas composition in a gasoline engine.

FIG. 3 is a schematic diagram showing another embodiment of the internal combustion engine of the present invention.

FIG. 4 is a schematic diagram showing another embodiment of the internal combustion engine of the present invention.

[Explanation of symbols]

1 engine, 2 front catalyst, 3 main catalyst, 4 intake pipe,
5 ... Air pump, 6 ... Secondary air supply pipe, 7,16 ... Temperature sensor, 8 ... Air amount adjustment valve, 9 ... Fuel adjustment valve, 10 ...
Air-fuel ratio control unit (A / F control unit), 11, 13, 14, 2
DESCRIPTION OF SYMBOLS 1 ... Valve, 12 ... Bypass flow path, 15 ... Dehumidifier.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication F02D 41/14 310 F02D 41/14 310J (72) Inventor Noriko Watanabe 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi Laboratory (72) Inventor Toshio Ogawa 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi Laboratory Co., Ltd. (72) Inventor Hiroshi Miyadera 4026 Kuji-cho, Hitachi City, Ibaraki Hitachi, Ltd.Hitachi Research, Ltd. In-house (72) Inventor Takeshi Atako 2520 Oaza Takaba, Katsuta-shi, Ibaraki Hitachi, Ltd. Automotive Equipment Division (56) References JP-A-49-13515 (JP, A) JP-A-54-79319 ( JP, A) Jiko 63-38340 (JP, Y2)

Claims (9)

(57) [Claims] An intake system of an engine has an air-fuel ratio control unit for controlling the amounts of fuel and air, and an air supply means is provided upstream of an exhaust system.
An internal combustion engine having a three-way catalyst for purifying exhaust gas at a subsequent stage, wherein the three-way catalyst is provided downstream of the air supply means in the exhaust system.
A pre-catalyst consisting of a combustion catalyst is provided upstream of the catalyst, and the air-fuel ratio A / F (A is air weight, F is
Fuel weight) after the engine is started and the three-way catalyst
Until the temperature rises to the level at which
The fuel excess is also 13 or less and 10 or more, the three-way catalyst
After the temperature rises to a temperature at which
The air-fuel ratio of the air-fuel ratio control unit is higher than the stoichiometric air-fuel ratio.
While the air supply means is set to
An internal combustion engine characterized in that the internal combustion engine is supplied . 2. The air supply means according to claim 1, wherein
Equal to or greater than the theoretical oxygen consumption of the exhaust gas
An internal combustion engine comprising: means for supplying an oxidizing agent . 3. The three-way catalyst according to claim 1, wherein
A means for detecting a temperature, wherein the temperature detected by the means is provided;
Based on the temperature, the temperature of the three-way catalyst reaches an active temperature.
An internal combustion engine characterized in that it is determined whether or not it has reached . 4. The method according to claim 1, wherein:
To the exhaust system from the engine upstream of the three-way catalyst.
And a bypass passage is provided in the bypass passage.
An internal combustion engine comprising a pre-catalyst . 5. The engine according to claim 4, wherein
Engine exhaust while fuel is being supplied in excess of the fuel ratio
The gas flows into the bypass, and the engine
After the fuel of the fuel ratio is supplied, the engine exhaust
Said air gas directly the bypass passage without being passed to the three-way catalyst
An internal combustion engine comprising exhaust gas flow switching means for flowing . 6. The method according to claim 1, wherein:
In the exhaust gas flow path from the engine to the pre-catalyst.
An internal combustion engine comprising dehumidifying means . 7. The method according to claim 1, wherein:
Exhaust gas downstream of the front catalyst in the bypass passage.
Dehumidifying means, the temperature of the pre-catalyst is below the dew point of exhaust gas
When the exhaust gas is dehumidified by the dehumidifying means,
An internal combustion engine characterized by being guided to a catalyst . 8. An air-fuel ratio control unit for controlling the amounts of fuel and air is provided in an intake system of an engine, and an air supply means and an exhaust gas are provided in an exhaust system.
Gas purification three-way catalyst and temperature detection and detection means of the three-way catalyst
Provided and detected by the temperature detecting means after the engine is started.
Until the temperature of the activated three-way catalyst reaches a temperature at which activity is exhibited.
During the period, the air-fuel ratio of the air-fuel ratio controller is set to be lower than the stoichiometric air-fuel ratio.
And set air to excess, and supply air from the air supply means.
Supply and the temperature of the three-way catalyst reaches a temperature at which activity is exhibited.
After that, set the air-fuel ratio of the air-fuel ratio controller to the stoichiometric air-fuel ratio
And the supply of air from the air supply means is stopped.
In the operating method for an internal combustion engine, the three-way system is provided downstream of the air supply means in the exhaust system.
A pre-catalyst consisting of a combustion catalyst is provided upstream of the catalyst.
After the engine is started, the temperature of the three-way catalyst becomes active.
The air-fuel ratio of the air-fuel ratio control unit until the temperature reaches
A / F (A is air weight, F is fuel weight) is 13 or less, 1
An internal combustion engine characterized by being set to 0 or more
Driving method. 9. A fuel and air supply system for an intake system of an internal combustion engine.
It has an air-fuel ratio control unit that controls the amount of air.
It has a supply means and has a three-way catalyst for exhaust gas purification at the subsequent stage
In the automobile, the three-way valve is disposed downstream of the air supply means in the exhaust system.
Comprises a pre-catalyst consisting of combustion catalyst on the upstream side of the catalyst, the air-fuel ratio A / F (A of the air-fuel ratio control unit air weight, F is
Fuel weight) after the engine is started and the three-way catalyst
Until the temperature rises to the level at which activity occurs.
A value of 13 or less and 10 or more of fuel excess over the ratio,
After the temperature of the source catalyst rises to a temperature at which activity
Fuel ratio, and the air-fuel ratio of the air-fuel ratio controller is the stoichiometric air-fuel ratio.
During the period when the air supply is set to be over fueled,
Automatic, characterized in that air is supplied from the stage
car.