JPH06117240A - Catalyst warming-up equipment of internal combustion engine - Google Patents

Abstract

PURPOSE:To maintain an excellent ignition performance of an ignition plug mounted on the exhaust system and execute the secure early warming-up of a catalyst converter in a catalyst warming-up equipment of an internal combustion engine to realize the early warming-up of the catalyst converter mounted on the exhaust system. CONSTITUTION:A catalyst warming-up equipment is provided with a catalyst converter 4 mounted on an exhaust system 2 of an internal combustion engine, an igniting means 5 mounted in the upstream of the catalyst converter 4 of the exhaust system 2, a combustible supplying means 6 to supply the combustible to the vicinity of the igniting means 5, a first control means 11 to actuate the respective means 5, 6 when the catalyst temperature of the catalyst converter 4 is below the specified value, and a second control means 11 to actuate the respective means 5, 6 when the non-actuating time of the respective means 5, 6 while the internal combustion engine is running is below the specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst warm-up device for an internal combustion engine for achieving early warm-up of a catalytic converter provided in an exhaust system.

[0002]

2. Description of the Related Art Generally, a catalytic converter provided in an exhaust system of an internal combustion engine sufficiently purifies harmful components in exhaust gas when the catalyst temperature is raised by the exhaust gas and activated. Is. As a result, during the period from when the engine is started to when the catalyst temperature is raised by the exhaust gas, the harmful components in the exhaust gas are not sufficiently purified and are released into the atmosphere, which causes air pollution. There is a need for early warm-up of the catalytic converter at times.

Before the catalyst is activated, secondary air is supplied upstream of the catalytic converter in the engine exhaust system, the unburned fuel in the exhaust gas is ignited by the spark plug and burned together with this air, and the heat causes the catalytic converter to burn. Although a catalyst warming device intended to warm up early is known, it is difficult to reliably burn the catalyst because the amount of unburned fuel is small. Japanese Patent Application No. 3-85430 proposes a catalyst warm-up device for supplying hydrogen, which is a combustible substance, in order to ensure the combustion in the upstream of the above-mentioned catalytic converter.

[0004]

In the above-mentioned prior art, since the spark plug provided in the exhaust system is constantly exposed to the exhaust gas, the spark plug is gradually exposed to carbon and the like contained in the exhaust gas. Adhere to. Since the ignition performance of the spark plug deteriorates with the increase of the adhered amount, even if secondary air and hydrogen are finally supplied to the exhaust system, they cannot be combusted, and the catalytic converter at the time of start-up. Early warm-up becomes impossible.

Therefore, an object of the present invention is to provide a catalyst warm-up device for an internal combustion engine, which maintains good ignition performance of a spark plug provided in an exhaust system and enables reliable early warm-up of a catalytic converter. That is.

[0006]

A first catalyst warm-up device for an internal combustion engine according to the present invention is a catalytic converter provided in an exhaust system of an internal combustion engine, and an ignition provided upstream of the catalytic converter in the exhaust system. Means, a combustible material supply means for supplying a combustible material to the vicinity of the ignition means, a first control means for operating both means when the catalyst temperature of the catalytic converter is equal to or lower than a predetermined value, and the internal combustion engine Second control means for activating both means when the non-operating time of both means during operation exceeds a predetermined time.

A second catalyst warm-up device for an internal combustion engine according to the present invention is the catalyst warm-up device for a first internal combustion engine as described above, wherein the richer the air-fuel ratio of the air-fuel mixture in the non-operating time is, The predetermined time is shortened.

[0008]

According to the first catalyst warm-up device for an internal combustion engine described above, when the catalyst temperature of the catalytic converter is equal to or lower than a predetermined value, the first control means causes the combustible material supply means to transfer the combustible material to the exhaust system catalytic converter upstream. Is supplied to the vicinity of the spark plug provided at the same time, and at the same time, the ignition means performs ignition to ensure reliable combustion of the combustible material upstream of the catalytic converter in the exhaust system,
Early warm-up of the catalytic converter is realized. Further, when the non-operating time of both the means during the operation of the internal combustion engine becomes a predetermined time or more, since the both means are operated by the second control means, carbon and the like adhered to the ignition means during this period are combustible. The ignition means is purified by burning with an object, and the ignition performance of the ignition means can always be kept good.

According to the second catalyst warm-up device for an internal combustion engine, the richer the air-fuel ratio of the air-fuel mixture in the non-operating time is, the shorter the above-mentioned predetermined time is and the more frequent the second control means is. Since the combustion is performed in the exhaust system by the above, the richer the air-fuel ratio, the more reliable combustion purification can be realized for carbon and the like that adheres much to the ignition means.

[0010]

1 is a schematic diagram of an internal combustion engine provided with a catalyst warm-up device according to the present invention. In the figure, 1 is an engine, 2 is an exhaust passage, and 3 is an intake passage. Exhaust passage 2
Is provided with a catalytic converter 4 for purifying harmful components in exhaust gas, and an ignition plug 5 is provided upstream thereof. A hydrogen generator 6 for generating hydrogen, which is a combustible substance, by electrolysis of water is provided, and the hydrogen generator 6 and the vicinity of the spark plug 5 of the exhaust passage 2 have a hydrogen supply passage 8 having a solenoid valve 7. Connected by.

Further, the hydrogen supply passage 8 in the exhaust passage 2
An air supply device 9 such as an electric pump is connected upstream of the connecting portion, and an oxygen sensor 10 for detecting the oxygen concentration in the exhaust gas is installed upstream thereof. A control device 11 for controlling ignition of the spark plug 5, opening / closing of the solenoid valve 7, and driving of the air supply device 9 is provided.
A catalyst temperature sensor 12 that detects the catalyst temperature of the catalytic converter 4, a starter switch (not shown), and the like are electrically connected to the.

The above-mentioned control by the control unit 11 is performed according to the first flow chart shown in FIG. This flowchart is executed when the starter switch is turned on and is stopped when the engine 1 is stopped. At this time,
Flag F and time tih, toh, tric described later
h is reset to 0, the solenoid valve 7 is closed, and the air supply device 9 is stopped. First, in step 101, it is judged whether or not the starter switch is in the ON state, and when the judgment is positive, the process proceeds to step 102,
It is determined whether the flag F is 1. Since the initial flag F is 0, the routine proceeds to step 103, where it is judged if the catalyst temperature T detected using the catalyst temperature sensor 12 is equal to or higher than the activation temperature T1.

When this judgment is denied, that is, when the catalyst warm-up is required, the routine proceeds to step 104, where the ignition plug 5 is ignited, and at step 105, the air supply device 9 is operated and the exhaust gas is exhausted. Air is supplied to the passage 2, and in step 106, the electromagnetic valve 7 is opened to open the exhaust passage 2
Is supplied with hydrogen, and then the flag F is set to 1. By these processes, hydrogen and air are ignited and reliably burned upstream of the catalytic converter 4 in the exhaust passage 2, and the catalytic converter 4 is warmed up.

Thereafter, in step 108, a subroutine for counting time is called and the process is ended. On the other hand, the determination in step 102 after the above-described processing is executed is that the flag F is 1, and at this time, the above-mentioned subroutine is called in step 108 and the processing ends. When the determination in step 103 is affirmative, that is, when the catalyst warm-up is unnecessary, the flag F remains 0 and the aforementioned subroutine is called in step 108 and the process ends.

The subroutine for time counting is shown in FIG. First, in step 1001, it is determined whether the flag F is 1. When this determination is denied, that is, when the combustion in the exhaust passage 2 is not executed, the routine proceeds to step 1002, the combustion execution time tih is reset to 0, and the combustion non-execution time toh is incremented by 1 in step 1003. To be done. Next, in step 1004, the flag RF is 1
Is determined. This flag RF is set by the second flowchart for air-fuel ratio determination which is executed at the same time.

This second flow chart is shown in FIG. First, in step 201, the oxygen sensor 10
Based on the signal obtained from, it is determined whether the air-fuel ratio of the air-fuel mixture, which is controlled to obtain the optimum operating state, is richer than the stoichiometric air-fuel ratio. When this determination is affirmed, the flag is determined in step 202. RF is set to 1, and when denied, flag RF is set to 0 in step 203.

Accordingly, when the determination in step 1004 of the above-mentioned subroutine is affirmed, step 10
05, the operation time trich in the rich air-fuel mixture during non-combustion is incremented by 1
Return to the flowchart. Further, when the determination in step 1004 is negative, the rich mixture operation time tri
ch returns to the first flowchart without being counted up. On the other hand, when the determination in step 1001 is affirmative, that is, when the combustion in the exhaust passage 2 is being executed, the combustion non-execution time toh is reset to 0 in step 1006, and the rich mixture operation time trich is 0 in step 1007. Reset to
Next, at step 1008, the combustion execution time tih is incremented by 1.

When the determination in step 101 of the first flowchart is denied, that is, when the engine 1 is started and the starter switch is off, step 109
Then, it is determined whether the flag F is 1. When this determination is affirmative, that is, when the combustion in the exhaust passage 2 is being executed, the routine proceeds to step 110, where the combustion execution time tih is the hydrogen supply time t1 set in consideration of the catalyst warm-up time. It is determined whether it has been reached. Initially, this determination is denied, and the above-mentioned subroutine is called in step 108 and the processing ends.

On the other hand, when the combustion execution time tih has elapsed and the determination in step 110 is affirmative, step 11
1, the solenoid valve 7 is closed and the hydrogen supply to the exhaust passage 2 is stopped, and in step 112, the spark plug 5
Ignition is stopped. Next, in step 113, after counting for a certain period of time, in step 114, the air supply device 9 is stopped and the air supply to the exhaust passage 2 is stopped, and in step 115 the flag F is set to 0. As a result, combustion in the exhaust passage 2 is stopped and catalyst warm-up is stopped. At this time, if the air supply is stopped first, unburned hydrogen is supplied into the catalytic converter 4 and burns there, which may damage the catalytic converter 4, but this is prevented by this flowchart. It Next, at step 108, the above-mentioned subroutine is called and the processing ends.

When the determination in step 109 is negative, that is, when the combustion in the exhaust passage 2 is stopped, the routine proceeds to step 116, where the rich mixture operating time trich multiplied by the coefficient α is the combustion non-execution time toh. Is calculated and whether or not the time t has reached a predetermined time t2 is determined in step 117. When this judgment is affirmed, the routine proceeds to step 118, where it is judged whether the catalyst temperature T is lower than the limit temperature T2 which accelerates the deterioration thereof. If the determination in step 117 or step 118 is negative, step 10
At 8, the above subroutine is called and the process ends. On the other hand, when the determination in step 118 is affirmative, the routine proceeds to step 119, the ignition of the spark plug 5 is executed, the air supply device 9 is operated in step 120 to supply air to the exhaust passage 2, and in step 121 the electromagnetic The valve 7 is opened and hydrogen is supplied to the exhaust passage 2. Next, in step 122, the flag F is set to 1, and in step 108 the above-mentioned subroutine is called and the processing ends. The combustion in the exhaust passage 2 at this time is also the same as the combustion for warming up the catalyst in the above-mentioned step 1.
It is canceled by the processing from 10 onward.

According to this control, when the engine temperature is low and the catalyst temperature T is low and warming up is required at the time of starting the engine 1, hydrogen and air are supplied to the upstream side of the catalytic converter 4 in the exhaust passage 2 and the spark plug 5 is supplied. The ignition is performed, and the combustion of these causes the catalytic converter 4 to be warmed up early. This combustion is stopped when the combustion execution time tih reaches the hydrogen supply time t1, and at the same time, counting up of the combustion non-execution time toh is started. If the operating state at this time requires a rich air-fuel mixture, the count-up of the rich air-fuel mixture operation time trich is further started. When the time t calculated by adding the combustion non-execution time toh to the value obtained by multiplying the rich mixture operation time trich by α reaches a predetermined time t2, the catalyst temperature T reaches a limit temperature T2 that accelerates its deterioration. After confirming that the exhaust gas is not present, hydrogen and air are supplied to the exhaust passage 2, ignition of the spark plug 5 is executed, and combustion in the exhaust passage 2 is performed.

As a result, the carbon or the like attached to the spark plug during this period is simultaneously burned to purify the spark plug 5, and the ignition performance of the spark plug 5 can be maintained excellent. The above time t is the combustion non-execution time toh
In addition, since the rich air-fuel mixture operating time trich is added by α times, the operation is performed only with the rich air-fuel mixture in which the carbon content in the exhaust gas increases when combustion is not executed. A predetermined time t2 is reached early, and combustion in the exhaust passage 2 for purifying the spark plug 5 is executed. That is, the time t described above represents the amount of carbon adhering to the spark plug 5, and the predetermined time t2 represents the amount of carbon adhering to which the spark plug 5 is desired to be cleaned. Even if the coefficient α for weighting the rich air-fuel mixture operating time trich is a constant, the above-mentioned time t accurately represents the carbon deposition amount to some extent. However, the richer the air-fuel mixture concentration, the higher the carbon content in the exhaust gas. Then
Considering that the exhaust gas amount increases as the rotation speed increases, the coefficient α is increased as the average rich degree of the air-fuel mixture in the rich air-fuel mixture operation increases and as the average rotation speed increases. Therefore, the above-mentioned time t is the spark plug 5
The amount of carbon deposited on the exhaust passage 2 for cleaning the spark plug 5 can be expressed more accurately and only when it is really needed.
Internal combustion can be performed.

The activation temperature of the catalyst of the catalytic converter 4 rises with the passage of time, and the activation temperature cannot be maintained sufficiently at the exhaust gas temperature in the engine steady operation. However, according to the present embodiment, the exhaust passage The combustion in 2 is repeatedly executed for purifying the spark plug 5 not only at the time of start-up, but the catalyst temperature can be raised, and the exhaust gas purification performance at this time can be improved.

For catalyst warm-up, it is very difficult to burn unburned fuel in the engine combustion chamber using the spark plug 5 in the exhaust passage 2 due to the small amount of unburned fuel. However, by newly supplying a combustible substance such as hydrogen as in the present embodiment, the combustion in the exhaust passage becomes reliable, and not only the combustion at this time but also the combustion for purifying the spark plug 5 is performed. The above-mentioned unburned fuel is simultaneously burned by
Unburned fuel, which is a harmful component in the exhaust gas, can be significantly reduced.

In the present embodiment, in order to simplify the first flow chart, the combustion in the exhaust passage 2 for cleaning the spark plug 5 is stopped at the same time as the combustion for warming up the catalyst. Of course, in consideration of the amount of carbon adhering to the ignition plug 5, it is possible to stop the operation after another optimum time has elapsed. Although hydrogen was used as the combustible material, it is obvious that other combustible materials can be used.

FIG. 5 shows another embodiment showing the vicinity of the spark plug 5 in the exhaust passage 2. In the figure, similar to FIG. 1, a hydrogen supply passage 8 is connected to the hydrogen supply device in the vicinity of the spark plug 5. On the other hand, the air supply device is arranged so as to supply air from around the hydrogen supply passage 8 to the vicinity of the spark plug 5.

In the structure shown in FIG. 1, the air supplied to the exhaust passage 2 is mixed with the exhaust gas and supplied to the vicinity of the ignition plug 5 to be ignited together with hydrogen. However, about 3 to 5 times the required amount of air is required, which lowers the exhaust gas temperature and prolongs the catalyst warm-up time. However, according to the structure shown in FIG.
The air supplied to is supplied to the vicinity of the ignition plug 5 together with hydrogen without being mixed with the exhaust gas, so that only the necessary amount of air needs to be supplied, and the air supply amount decreases.
It is possible to prevent the temperature of the exhaust gas from decreasing, and it is possible to downsize the air supply device.

[0028]

As described above, according to the catalyst warm-up device for an internal combustion engine according to the present invention, when the catalyst temperature at engine startup is low, combustible substances are supplied upstream of the catalytic converter in the exhaust passage by the combustible substance supply means. Thus, the catalyst can be ignited by the ignition means and burned reliably, and the catalyst can be warmed up early.
Further, after the combustion in the exhaust passage for catalyst warm-up is completed, when the non-operation time of both means reaches a predetermined time, hydrogen and air are supplied again to perform combustion in the exhaust passage. The carbon adhering to the ignition means can be burnt and purified by this combustion, and the ignition performance of the ignition means can always be maintained good. The predetermined time that determines the execution of combustion for purifying the ignition means is shortened as the air-fuel ratio of the air-fuel mixture is richer during the non-operating time of both means, so that the carbon content in the exhaust gas increases. The above-mentioned combustion is frequently executed for the operation in a rich air-fuel mixture, and at this time, it is possible to reliably combust and purify carbon that adheres much to the ignition means, while the execution of this combustion is minimized, The life of the ignition means and the combustible material supply means can be extended.

[Brief description of drawings]

FIG. 1 is a schematic view of an internal combustion engine equipped with a catalyst warm-up device according to the present invention.

FIG. 2 is a first flowchart for control.

FIG. 3 is a subroutine used in the first flowchart.

FIG. 4 is a second flowchart for control.

FIG. 5 is a cross-sectional view showing another embodiment near the spark plug of the exhaust passage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust passage 4 ... Catalytic converter 5 ... Spark plug 6 ... Hydrogen generator 7 ... Control valve 8 ... Hydrogen supply device 9 ... Air supply device 11 ... Control device 12 ... Catalyst temperature sensor

Claims (2)

[Claims] 1. A catalytic converter provided in an exhaust system of an internal combustion engine, an ignition means provided upstream of the catalytic converter in the exhaust system, and a combustible material supply means for supplying a combustible material in the vicinity of the ignition means. And, when the catalyst temperature of the catalytic converter is equal to or lower than a predetermined value, the first means for activating both means.
A catalyst for an internal combustion engine, comprising: a control means; and a second control means that activates both means when the non-operation time of the both means during operation of the internal combustion engine exceeds a predetermined time. Warming device. 2. The catalyst warm-up device for an internal combustion engine according to claim 1, wherein the predetermined time is shortened as the air-fuel ratio of the air-fuel mixture in the non-operation time is richer.