JPH0742540A - Exhaust emission control device foe intrenal combustion engine - Google Patents

Abstract

PURPOSE:To improve the exhaust emission control function on the cold start of an engine by securing the sufficient temperature rise performance, reducing the weight of a heater and the electric power consumption. CONSTITUTION:A heater catalyst 5, main catalyst 6, and an exhaust silencer 7 are arranged in the exhaust passage 4 of an internal combustion engine E, and an opening/closing valve 9 for reducing the sectional area of the exhaust passage is installed in the exhaust silencer 7. On the cold start of the internal combustion engine E, heating is carried out by allowing electricity to flow in the heater catalyst 5, and the exhaust gas temperature is increased by increasing the back pressure of the exhaust passage 4 by closing-controlling the opening/closing valve 9, and the temperature rise of the heater catalyst 5 is accelerated, and the temperature is speedily raised over the catalyst activation temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine in which an exhaust gas purifying catalyst is provided in an exhaust passage of the internal combustion engine.

[0002]

2. Description of the Related Art An exhaust gas purifying catalyst having an electric heating means is provided in an exhaust passage of an internal combustion engine, and the exhaust gas purifying catalyst is heated at a cold start or the like to raise its temperature above a catalyst activation temperature. As a technique for improving the emission of the internal combustion engine at low temperature, the technique described in Japanese Utility Model Laid-Open No. 4-105925 is known.

Further, the unburned gas component generated in the fuel tank is supplied upstream of the exhaust gas purifying catalyst having no electric heating means, and the exhaust gas purifying catalyst is heated by the heat of burning the unburned gas component. As a technique for raising the temperature with
The one described in Japanese Patent No. 58143 is known.

[0004]

By the way, the one disclosed in Japanese Utility Model Laid-Open No. 4-105925 requires a certain amount of time to raise the temperature of the exhaust gas purifying catalyst to the catalyst activation temperature or higher by the heating means. Therefore, there is an unavoidable problem that harmful substances are emitted during that period. In order to avoid such a problem, the temperature of the exhaust gas purifying catalyst should be quickly raised to the catalyst activation temperature or higher with a large capacity heating means, but for that purpose, a large battery and a large heating means are required. There is a problem that it becomes necessary to increase the weight.

Further, in the one described in the above-mentioned Japanese Patent Laid-Open No. 59-58143, the unburned gas component remains in the atmosphere until the temperature of the exhaust gas purification catalyst reaches the combustion temperature of the unburned gas component. There is a problem of being released.

The present invention has been made in view of the above circumstances, and the temperature of the exhaust gas purifying catalyst can be quickly raised to the catalyst activation temperature or more without excessively increasing the size of the heating means provided in the exhaust gas purifying catalyst. The purpose is to prevent the release of harmful components into the atmosphere.

[0007]

In order to achieve the above object, an exhaust gas purifying apparatus for an internal combustion engine according to a first aspect of the present invention is an exhaust gas having an electric heating means provided in an exhaust passage of the internal combustion engine. A gas purification catalyst, an exhaust passage cross-sectional area control unit provided on the downstream side of the exhaust gas purification catalyst and capable of variably controlling the exhaust passage cross-sectional area, and an exhaust passage according to an operating state of the exhaust gas purification catalyst heating unit. And a control means for reducing the cross-sectional area.

Further, in the exhaust gas purifying apparatus for an internal combustion engine according to a second aspect, in addition to the configuration of the first aspect, the operating state of the heating means of the exhaust gas purifying catalyst depends on the operating state of the internal combustion engine. It is characterized by being decided.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

First, in FIG. 1 showing a first embodiment of the present invention, an intake passage 2 and an exhaust passage 4 are connected to an intake port 1 and an exhaust port 3 of an internal combustion engine E, respectively. The exhaust passage 4 refers to a flow path until the exhaust gas emitted from the exhaust port 3 is released to the atmosphere, and the heating heater catalyst 5 and
The main catalyst 6 located downstream of the heater catalyst 5
And an exhaust silencer 7 located downstream of the main catalyst 6.

The heating heater catalyst 5 is provided with a heating heater (not shown) around it, and can be heated by energizing this heating heater through a heater driver 8. The heater catalyst 5 may be composed of an electric resistor whose catalyst carrier itself generates heat when energized, or may be a separate heater. The main catalyst 6 has a larger capacity than the heater catalyst 5, and is responsible for most of the exhaust gas purification function when the warm-up of the internal combustion engine E is completed.

The inside of the exhaust silencer 7 has a labyrinthine shape in order to obtain a sound deadening effect, and two exhaust ports 7 ₁ and 7 ₂ are provided at the downstream end thereof. An opening / closing valve 9 as an exhaust passage cross-sectional area control means is provided at _one exhaust port 7 ₁ . The on-off valve 9 composed of a butterfly valve or a rotary valve is connected to a pulse motor 11 driven via a motor driver 10, and a valve opening position and an exhaust port for opening an exhaust port 7 ₁ provided at a rear portion of the exhaust silencer 7 Opening / closing control is performed at an arbitrary opening between the valve closing position for closing 7 ₁ . Therefore, by adjusting the opening degree of the opening / closing valve 9, the flow passage cross-sectional area of the exhaust passage 4 can be increased or decreased to change the flow passage resistance of the exhaust gas.

The intake passage 2 of the internal combustion engine E is provided with an intake temperature sensor 12 for detecting the intake temperature Ta and an intake passage absolute pressure sensor 13 for detecting the absolute pressure Pb of the intake passage, and the water of the internal combustion engine E is also provided. The jacket is provided with a cooling water temperature sensor 14 for detecting the cooling water temperature Tw. An internal combustion engine speed sensor 15 for detecting the internal combustion engine speed Ne is provided near the crankshaft of the internal combustion engine E, and a catalyst temperature sensor 16 for detecting the temperature of the heater heating catalyst 5 is provided on the heater heating catalyst 5. Is provided.

The electronic control unit U includes the intake air temperature sensor 12, the intake passage absolute pressure sensor 13, the cooling water temperature sensor 14, the internal combustion engine speed sensor 15 and the catalyst temperature sensor 1.
6, an input circuit 17 to which a signal from the sensor 6 is input, a central processing unit 18 for processing the signals from the sensors 12 to 16 based on a predetermined calculation program, and a central processing unit 18 for calculation. ROM 19 in which various calculation programs and various data stored are stored, and each sensor 1
R from which signals from 2 to 16 and calculation results are temporarily stored
An AM 20 and an output circuit 21 that outputs a drive signal to the heater driver 8 and the motor driver 10 are provided.

Next, the operation of the first embodiment having the above-mentioned structure will be described with reference to the flow chart of FIG.

First, at step S1, the internal combustion engine speed Ne detected by the internal combustion engine speed sensor 15 and the intake passage absolute pressure Pb detected by the intake passage absolute pressure sensor 13 are read into the electronic control unit U, and the internal combustion engine is read. Engine speed Ne
Also, a map search is performed for the opening control value of the on-off valve 9 provided in the exhaust silencer 7 based on the absolute pressure Pb in the intake passage. The opening control value of the opening / closing valve 9 is increased by increasing the opening of the opening / closing valve 9 and decreasing the back pressure generated in the exhaust passage when the internal combustion engine E is in an operating state where knocking is likely to occur. It is set so as to reduce the internal EGR amount of E to lower the combustion chamber temperature and thereby prevent knocking. Conversely, when the internal combustion engine E is in an operating state in which knocking is unlikely to occur, opening / closing is performed. It is set so that the opening degree of the valve 9 is decreased to increase the back pressure generated in the exhaust passage.

Then, in step S2, the heater heating catalyst 5
If the heater operating condition of is not satisfied, that is, the internal combustion engine E
If the warm-up of the motor driver 1 is completed, the process proceeds to step S5 and the opening control value calculated in step S1 is set as the final control value, and based on the final control value, the motor driver 1
The opening degree of the on-off valve 9 is controlled via 0 and the pulse motor 11. The heater operating condition is, for example, the intake air temperature sensor 1
It is judged by comparing the intake air temperature Ta detected in 2 and the cooling water temperature Tw detected by the cooling water temperature sensor 14 with a predetermined reference value, and when the intake air temperature Ta and / or the cooling water temperature Tw is below the reference value, the heater is activated. If the condition is satisfied and is equal to or more than the reference value, the heater operating condition is not satisfied.

On the other hand, when the heater operating condition of the heater heating catalyst 5 is satisfied in step S2, that is, when the warm-up of the internal combustion engine E is not completed, the process proceeds to step S3 and the heater heating catalyst 5 is changed. Electric power is supplied through the heater driver 8, and the heater heating catalyst 5 is rapidly heated by this. At the same time, in step S4, the catalyst temperature sensor 16
The correction value for the closing side of the on-off valve 9 is map-searched on the basis of the catalyst temperature Tc detected in. The correction value on the closing side of the on-off valve 9 is large when the catalyst temperature Tc is low and the heater heating catalyst 5 is not activated, and is small as the catalyst temperature Tc increases and the heater heating catalyst 5 is activated. Is set to. Then, in step S5, the final control value is obtained by adding the closing side correction value obtained in step S4 to the opening control value of the on-off valve 9 obtained in step S1, and the opening / closing valve is obtained based on the final control value. The opening degree of 9 is controlled.

As described above, when the temperature of the heater heating catalyst 5 is below the catalyst activation temperature, such as during cold start, not only is the heater heating catalyst 5 heated by energization, but also the exhaust silencer 7 The provided on-off valve 9 is driven in the valve closing direction to reduce the cross-sectional area of the exhaust passage, whereby the flow passage resistance of the exhaust passage 4 increases and the combustion chamber temperature rises. As a result, the exhaust gas temperature rises. The temperature rise of the heater heating catalyst 5 is promoted. Therefore, the temperature of the heater heating catalyst 5 rapidly rises to the catalyst activation temperature or higher in combination with the energization of the heater heating catalyst 5, and the harmful components in the exhaust gas are prevented from being released into the atmosphere. In this way, if the temperature of the main catalyst 6 rises above the catalyst activation temperature while the temperature of the small-capacity heater heating catalyst 5 is raised above the catalyst temperature temperature to purify the exhaust gas, the heater heating catalyst The energization of 5 is stopped, the on-off valve 9 is driven in the valve opening direction, and a normal operating state is entered.

Thus, not only is the heater heating catalyst 5 electrically heated, but the temperature rise of the heater heating catalyst 5 is promoted by reducing the exhaust passage cross-sectional area. It is possible to secure sufficient exhaust gas purification performance while reducing power consumption.

FIG. 3 shows a second embodiment of the present invention.
In the second embodiment, a pre-exhaust silencer 7p and a main exhaust silencer 7m are provided in series at the rear of the main catalyst 6, and an opening / closing valve 9 as exhaust passage cross-sectional area control means is provided at the rear of the pre-exhaust silencer 7p. It is provided. Also in the second embodiment, the energization of the heater heating catalyst 5 and the opening / closing of the on-off valve 9 are controlled in the same manner as in the first embodiment, and the same effect can be obtained.

As an effect peculiar to the second embodiment, by providing the opening / closing valve 9 on the pre-exhaust silencer 7p, it is possible to reduce the heat capacity from the internal combustion engine E to the opening / closing valve 9 and further improve the temperature raising effect. Become. However, if the on-off valve 9 is provided in the pre-exhaust silencer 7p located on the upstream side of the exhaust passage 4, the temperature of the on-off valve 9 becomes high, and therefore the first embodiment is performed from the viewpoint of durability and operation reliability of the on-off valve 9. The examples are excellent. Further, in common to both embodiments, an on-off valve 9 is provided at the rear of the exhaust silencer 7 and the pre-exhaust silencer 7p.
Since the temperature rise of the on-off valve 9 is suppressed by providing the above, the exhaust silencer 7 and the pre-exhaust silencer 7p can be provided with the effect of a surge tank, and the controllability of the exhaust gas flow rate can be improved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made.

For example, in the embodiment, the heater heating catalyst 5 and the main catalyst 6 are provided separately, but the main catalyst 6
Is not essential, and the function of the main catalyst 6 can also be provided by increasing the capacity of the heater heating catalyst 5.

[0025]

As described above, according to the invention described in claim 1, the exhaust gas purifying catalyst having the electric heating means is provided in the exhaust passage of the internal combustion engine, and the exhaust gas purifying catalyst is provided downstream of the exhaust gas purifying catalyst. Exhaust passage sectional area control means is provided on the side,
Since the exhaust passage cross-sectional area is reduced according to the operating state of the heating means of the exhaust gas purification catalyst, the exhaust passage cross-sectional area is reduced even if the electrical heating means is downsized to reduce weight and power consumption. The temperature rise of the exhaust gas purifying catalyst can be quickly raised by the temperature rise effect due to the increase of the back pressure of the exhaust passage, and the release of harmful components in the exhaust gas to the atmosphere can be suppressed.

According to the invention described in claim 2,
By determining the operating state of the heating means of the exhaust gas purifying catalyst according to the operating state of the internal combustion engine, when the temperature of the exhaust gas purifying catalyst is below the catalyst activation temperature during cold start etc. It is possible to raise the temperature of the catalyst and suppress the release of harmful components in the exhaust gas into the atmosphere.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an exhaust gas purifying apparatus for an internal combustion engine according to a first embodiment.

FIG. 2 is a flowchart explaining the operation.

FIG. 3 is an overall configuration diagram of an exhaust gas purifying apparatus for an internal combustion engine according to a second embodiment.

[Explanation of symbols]

 4 Exhaust Passage 5 Heating Heater Catalyst (Exhaust Gas Purification Catalyst) 9 Opening / Closing Valve (Exhaust Passage Cross Section Area Control Means) E Internal Combustion Engine U Electronic Control Unit (Control Means)

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location F02D 9/04 ZAB E (72) Inventor Hiroaki Kato 1-4-1 Chuo Wako-shi, Saitama Stock company Honda Inside Technical Research Institute (72) Inventor Riichi Oketani 1-4-1 Chuo, Wako-shi, Saitama Stock Technical Research Institute (72) Inventor Moriji Hachina 1-4-1 Chuo, Wako-shi, Saitama Shares Incorporated company Honda R & D Co., Ltd. (72) Inventor Seiji Matsumoto 1-4-1 Chuo, Wako-shi, Saitama Stock Company Incorporated Honda R & D Co., Ltd. (72) Takuya Aoki 1-4-1-1 Wako-shi, Saitama Stock Incorporated Honda Technical Research Institute (72) Inventor Yukio Miyashita 1-4-1 Chuo, Wako-shi, Saitama Incorporated Honda Technical Research Institute

Claims (2)

[Claims] 1. An exhaust gas purification catalyst (5) having an electric heating means provided in an exhaust passage (4) of an internal combustion engine (E), and a downstream side of the exhaust gas purification catalyst (5). The exhaust passage sectional area control means (9) capable of variably controlling the exhaust passage sectional area and the control means (U) for reducing the exhaust passage sectional area according to the operating state of the heating means of the exhaust gas purification catalyst (5). An exhaust gas purifying device for an internal combustion engine, comprising: 2. The exhaust gas of an internal combustion engine according to claim 1, wherein the operating state of the heating means of the exhaust gas purification catalyst (5) is determined according to the operating state of the internal combustion engine (E). Gas purification device.