JPH05156932A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make the catalytic activation of an exhaust emission controlling catalytic converter yet accelerable. CONSTITUTION:In an exhaust emission control device 1 of an internal combustion engine, a specified flow of gas is made to flow in by an engine 11 or a gas feeding means and an exhaust pipe 3 toward a honeycomb 17 from the side of a heater 15 in addition to heating of this honeycomb 17 or carrier of a catalytic converter by the heater 15 or the heating means till the detection temperature of a catalytic sensor 19 or the temperature detecting means is reached to the specified time or specified temperature before starting and/or after starting the engine 11 at a time when the catalytic converter 5 is activated. At this time, in order to raize a temperature of the honeycomb 17 quickly as well as to make a faint breeze flow in, the honeycomb 17 comes to receive the heated gas in a proper flow rate in consequence, so even in the central part, temperature goes up so quickly. With this constitution, a catalytic activation for the emission controlling catalytic converter 5 is thus accelerable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust purification system for an internal combustion engine using a catalytic converter.

[0002]

2. Description of the Related Art In order to activate a catalytic converter for purifying the exhaust gas of an internal combustion engine, the temperature of the carrier of the catalytic converter must be about 350 degrees Celsius or higher. For the conventional,
There has been an attempt to raise the temperature of the carrier by providing an electric heater near the carrier of the exhaust gas purification catalytic converter and starting heating by the electric heater when the internal combustion engine is started.

[0003]

In the conventional method, however, a large amount of low-temperature exhaust gas flows into the exhaust gas purification catalytic converter during idle operation, so that the heat of the heater is removed by the exhaust gas and the purification gas is removed. It was difficult to reach the carrier of the catalytic converter. Therefore, it took a long time for the carrier to reach the catalyst activation temperature even in the central portion.

In view of the above problems, it is an object of the present invention to accelerate catalyst activation of an exhaust gas purification catalytic converter by heating while flowing a gas of a predetermined flow rate.

[0005]

In order to achieve this object, the invention described in claim 1 has the following construction.
That is, as illustrated by a solid line in FIG. 7, an exhaust gas purification catalytic converter provided in an exhaust pipe of an internal combustion engine, a heating unit that heats the exhaust gas purification catalytic converter, and an exhaust gas purification catalytic converter heating unit. Gas supply means for supplying gas from the side of the heating means, and the heating means while allowing a predetermined flow rate of gas to flow into the exhaust gas purification catalytic converter by the gas supply means for a predetermined time before starting the internal combustion engine and / or after starting the internal combustion engine. According to the present invention, there is provided an exhaust gas purification device for an internal combustion engine, which is capable of accelerating catalyst activation of the exhaust gas purification catalytic converter by including heating control means for heating the exhaust gas purification catalytic converter.

The invention according to claim 3 has the following configuration. That is, as illustrated by a solid line and a dotted line in FIG. 7, an exhaust gas purification catalytic converter provided in an exhaust pipe of an internal combustion engine, a heating means for heating the exhaust gas purification catalytic converter, and an exhaust gas purification catalytic converter are provided. Gas supply means for supplying gas from the heating means side, temperature detection means for detecting the internal temperature of the exhaust gas purification catalytic converter,
Before and / or after starting the internal combustion engine, until the temperature detected by the temperature detecting means reaches a predetermined temperature,
And a heating control unit for heating the exhaust gas purification catalytic converter by the heating unit while allowing a predetermined flow rate of gas to flow into the exhaust gas purification catalytic converter by the gas supply unit. The gist is an exhaust emission control device for an internal combustion engine that enables quick catalyst activation.

[0007]

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the catalytic converter for exhaust gas purifying is activated, the heating means is operated before and / or after starting the internal combustion engine until a predetermined time or a predetermined temperature is reached. In addition to heating the carrier of the exhaust gas purifying catalytic converter, a gas of a predetermined flow rate is introduced from the heating means side toward the carrier by the gas supply means. At this time, if a large amount of gas flows in, there is a problem that the gas, which is still low in temperature, takes heat from the heating means during idle operation. There is a problem that only a part of the surroundings can be heated. That is, in order to quickly raise the temperature of the carrier of the exhaust gas purification catalytic converter, it is necessary to flow in a gas at a flow rate suitable for it. In the present invention, the heated gas is sent to the carrier at a controlled and appropriate flow rate, so that the temperature of the carrier rises rapidly even in the central portion.

This makes it possible to accelerate the catalyst activation of the exhaust gas purification catalytic converter.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of an exhaust gas purification apparatus 1 for an internal combustion engine as an embodiment of the present invention. The exhaust gas purification device 1 for an internal combustion engine includes an exhaust pipe 3, a catalytic converter 5, a bypass pipe 7 and an ECU 9.

The exhaust pipe 3 is a pipe for discharging the exhaust gas emitted from the internal combustion engine 11 to the outside. At that time, the exhaust pipe 3
The internal combustion engine 11 also functions as gas supply means. The exhaust pipe 3 is provided with a catalytic converter 5, and a downstream side of the catalytic converter 5 is provided with a first valve 13 as a partial function of a flow rate adjusting means capable of closing the exhaust pipe 3. This first valve 13 is
It can be opened and closed under the control of an electric signal from the ECU 9.

The catalytic converter 5 comprises a heater 15, a honeycomb 17, a CA sensor 19 and the like. The heater 15 functions as a heating means for heating the honeycomb 17, and is attached on the upstream side of the honeycomb 17. The honeycomb 17 is a carrier carrying a catalyst for purifying exhaust gas. In order to activate the catalyst of the honeycomb 17, it is necessary to raise its temperature to about 350 degrees Celsius or higher. The temperature of the honeycomb 17 is detected by the CA sensor 19 as a temperature detecting means, and the temperature data is output to the ECU 9. CA sensor 19
Is a chromel alumel thermometer capable of measuring up to approximately 1200 degrees Celsius.

The bypass pipe 7 connects the upstream side of the catalytic converter 5 and the downstream side of the first valve 13 and performs a function of bypassing exhaust gas that bypasses the catalytic converter 5. The bypass pipe 7 is provided with a second valve 21 as a part of the function of the flow rate adjusting means that can close the bypass pipe 7. The second valve 21 can be opened and closed under the control of an electric signal from the ECU 9.

The ECU 9 includes an I / O, CPU, ROM / R
It is composed of an AM, various data buses, etc., and functions as a heating control means. This ECU 9 is C
The temperature data of the honeycomb 17 detected by the A sensor 19 is used as an input, and the control relating to the internal combustion engine 11 and the heater 15 and the opening / closing control of the first valve 13 and the second valve 21 are performed.

Next, the processing of the program executed by the ECU 9 will be described in detail with reference to the flowchart. EC
U9 performs processing based on the flow of FIG. Figure 3
It is a timing chart in that case. First, internal combustion engine 1
The internal combustion engine 11 is started by a person who wants to operate 1 turning the key switch 23 to the start position and operating the starter motor. By this operation, the ECU 9
Starts the flow of FIG. First, the ECU 9
Whether the internal combustion engine is started or not is determined depending on whether the key switch 23 is turned on (step 31). The determination at this time may be made when the rotational speed of the internal combustion engine has risen to a certain degree, or when the key switch 23 is turned to the start position. When it is determined to start the internal combustion engine, the ECU 9 closes the first valve 13 and opens the second valve 21 (step 33). However, the first valve 13 at this time is not completely closed, and is open to such an extent that the gas having an appropriate flow rate hits the catalytic converter 5. Next, the internal combustion engine 11 is started and the heater 15 is turned on (step 35). From this point, heating of the honeycomb 17 of the catalytic converter 5 begins. At this time, as shown in FIG. 4A, most of the exhaust gas flows toward the bypass pipe 7 by the first valve 13 and the second valve 21 as the flow rate adjusting means. Therefore, an appropriately adjusted amount of exhaust gas flows into the catalytic converter 5. The appropriately adjusted exhaust gas flows from the heater 15 side toward the honeycomb 17, so that the exhaust gas that is sufficiently heated can be efficiently used.
Heat 7. In this state, the temperature of the honeycomb 17 is set to CA.
Continue to monitor through the sensor 19 and continue to warm the honeycomb 17 until the temperature of the honeycomb 17 reaches approximately 350 degrees Celsius of the activation temperature (step 37). Thus, when the temperature of the honeycomb 17 reaches the activation temperature, the ECU 9 opens the first valve 13 and closes the second valve 21 (step 39). By this operation, as shown in FIG. 4 (B), all the exhaust gas bypassing the bypass pipe 7 will flow to the catalytic converter 5 side of the exhaust pipe 3. The exhaust is
It is released to the outside through the catalytically activated catalytic converter 5. This completes the processing of the ECU 9 as the heating control means.

Next, it will be described based on data that the catalyst activation of the honeycomb 17 is actually accelerated by following the above-mentioned processing procedure. FIG. 5 shows comparison data when a slight wind (limited air volume) is sent from the heater 15 side of the catalytic converter 5 (a), when no wind is sent (b), and when strong wind is sent (c). is there. In each case, the temperature distribution inside the honeycomb 17 after 30 seconds from heating is shown. Looking at this, when no wind is sent (b), only the surface of the honeycomb 17 is warmed,
The heating of the heater 15 does not reach the inside. Further, in the case (c) in which a strong wind is sent, a large amount of low-temperature gas flows in during idle operation, and the heat of the heater is taken away. Therefore, the honeycomb 17 is not so warm as a whole. When a slight breeze is sent as shown in this embodiment (a)
Then, it is understood that the heat is well transferred to the inside of the honeycomb 17 and is effectively warmed as compared with the other cases. FIG. 6 shows a comparison between the case where the flow rate is adjusted using the first valve 13 and the second valve 21 (x) and the case where the flow rate is not adjusted by these valves (y). When the flow rate is not adjusted (y), the temperature of the central portion of the honeycomb 17 rises slower than when the flow rate is adjusted (x). It is considered that this is because the heater 15 and the honeycomb 17 receive a large amount of exhaust gas that is not warmed when the internal combustion engine is started.

From these facts, it can be seen that it is quite effective to introduce a proper flow rate of gas from the heater 15 side in order to raise the temperature of the honeycomb 17. As described above, it becomes possible to accelerate the catalyst activation of the catalytic converter 5 by the exhaust gas purification device 1 for an internal combustion engine of this embodiment. In this embodiment, the internal combustion engine 11 is used as the gas supply means.
Although the exhaust pipe 3 is used, this method has an advantage that it is not necessary to separately provide a device for supplying gas.

In this embodiment, the flow rate is adjusted by the two valves, but instead of these, a damper device for allocating the flow rate at the branch point between the exhaust pipe 3 and the bypass pipe 7 may be provided to obtain the same effect. Be done. Further, the downstream side of the bypass pipe 7 does not necessarily have to be connected to the exhaust pipe 3. If a pump, a blower or the like is used as the gas supply means, the catalytic converter 5 can be activated in a short time before starting the internal combustion engine, and the emission of unpurified exhaust gas can be prevented. Further, in the present embodiment, the CA sensor 19 is provided as the temperature detecting means, but even without providing the CA sensor 19, the time for which the honeycomb 17 is sufficiently heated is experimentally obtained, and the catalyst is calculated based on the time. It is possible to activate the honeycomb 17 by determining the time for which the breeze is applied to the converter 5. It is also possible to activate the honeycomb 17 faster by adjusting the flow rate of the inflowing gas and the inflowing time depending on whether the material of the honeycomb 17 is metal or ceramic.

[0018]

As described above in detail, the exhaust gas purifying apparatus for an internal combustion engine according to the present invention can accelerate the catalyst activation of the catalytic converter by heating while flowing a gas of a predetermined flow rate. ..

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a flowchart of a program executed by the ECU 9.

FIG. 3 is a timing chart of a program executed by the ECU 9.

FIG. 4 is an explanatory diagram of valve control by the ECU 9.

FIG. 5 is a first explanatory diagram showing comparison data.

FIG. 6 is a second explanatory diagram showing comparison data.

FIG. 7 is a diagram illustrating a configuration of the present invention.

[Explanation of symbols]

1 ... Exhaust gas purification device for internal combustion engine, 3 ... Exhaust pipe, 5
... Catalytic converter, 7 ... Bypass pipe, 9 ...
ECU, 11 ... internal combustion engine, 13 ... first valve,
15 ... Heater, 17 ... Honeycomb, 19 ... C
A sensor, 21 ... Second valve, 23 ... Key switch

Claims (4)

[Claims] 1. An exhaust gas purifying catalytic converter provided in an exhaust pipe of an internal combustion engine, heating means for heating the exhaust gas purifying catalytic converter, and gas is supplied to the exhaust gas purifying catalytic converter from the heating means side. A gas supply means and a predetermined time period before and / or after the internal combustion engine is started,
And a heating control unit for heating the exhaust gas purification catalytic converter by the heating unit while allowing a predetermined flow rate of gas to flow into the exhaust gas purification catalytic converter by the gas supply unit. An exhaust gas purification device for an internal combustion engine that makes it possible to accelerate catalyst activation. 2. The gas supply means comprises a bypass bypassing the exhaust purification catalytic converter, and a flow rate adjusting means capable of adjusting a flow rate ratio between the exhaust flowing to the exhaust purification catalytic converter and the exhaust flowing to the bypass. The exhaust emission control device for an internal combustion engine according to claim 1, further comprising: 3. An exhaust gas purifying catalytic converter provided in an exhaust pipe of an internal combustion engine, heating means for heating the exhaust gas purifying catalytic converter, and gas is supplied to the exhaust gas purifying catalytic converter from the heating means side. Gas supply means, temperature detection means for detecting the internal temperature of the exhaust gas purification catalytic converter, and before and / or after starting the internal combustion engine until the temperature detected by the temperature detection means reaches a predetermined temperature,
And a heating control unit for heating the exhaust gas purification catalytic converter by the heating unit while allowing a predetermined flow rate of gas to flow into the exhaust gas purification catalytic converter by the gas supply unit. An exhaust gas purification device for an internal combustion engine that makes it possible to accelerate catalyst activation. 4. The gas supply means comprises a bypass bypassing the exhaust purification catalytic converter, and a flow rate adjusting means capable of adjusting a flow rate ratio between the exhaust flowing to the exhaust purification catalytic converter and the exhaust flowing to the bypass. The exhaust gas purification device for an internal combustion engine according to claim 3, comprising: