JPH05187228A - Exhaust emission purifier - Google Patents

Abstract

PURPOSE:To perform reliable purification of exhaust gas, in an exhaust gas purifying device provided with unburnt gas adsorbent for supplementing the purifying function of a catalyst during a cold start. CONSTITUTION:An exhaust gas purifying device is formed such that an unburnt gas adsorbent 4 and a catalyst converter 5 are arranged in the same exhaust system and a catalyst 5 is disposed on the downstream side in the direction of a flow of the unburnt gas adsorbent 4. The catalyst converter 5 is provided with a heating means, and during warming up, temperature is controlled so that the temperature of the catalyst converter 5 attains a given activation temperature before attaining a value at which adsorbed fuel is discharged by means of the unburnt gas adsorbent 4.

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, and more particularly to an exhaust gas purifying apparatus provided with an unburned gas adsorbent for complementing a catalytic purifying function in a cold state.

[0002]

2. Description of the Related Art Generally, in order to purify exhaust gas from an automobile, a pellet-type or monolith-type catalyst is arranged in the exhaust system. Hazardous components (HC, CO, N in exhaust gas
Of the O _x ), the purification of HC, in particular, by a catalyst is strongly influenced by the exhaust gas temperature, and a temperature of 250 ° C. or higher is generally required even when a noble metal catalyst is used.

Therefore, when the exhaust gas temperature is low immediately after the engine is started, the HC is difficult to be purified by the catalyst.
Moreover, since a large amount of HC is discharged immediately after the engine is started, the ratio of HC (hereinafter, referred to as cold HC) emission when the temperature of the exhaust gas is low accounts for a large proportion. Therefore, in order to improve the exhaust emission during cold, it is necessary to control the discharge of cold HC.

Therefore, as an exhaust gas purifying device, an exhaust gas purifying device is provided in which a purifying catalyst for harmful components in exhaust gas is arranged in an exhaust system of an engine and an unburned gas adsorbent for adsorbing cold HC is provided. Is proposed.

Conventionally, as an exhaust gas purifying apparatus in which a catalyst and an unburned gas adsorbent are provided in an exhaust system, for example, Japanese Patent Laid-Open No. 2-1
There was an exhaust gas purification device shown in Japanese Patent No. 73312.

The exhaust gas purifying device disclosed in the above publication is
A bypass passage branching from the upstream side of the catalyst installation position of the exhaust passage and connecting to the downstream side of the catalyst installation position is provided.
An unburned gas adsorbent is provided in the bypass passage. Further, a switching valve is arranged at a branch portion of the bypass passage located upstream of the catalyst arrangement position of the branch passage, and exhaust gas can be selectively introduced into the exhaust passage or the bypass passage. There is.

Then, in a cold state in which the catalyst is not sufficiently activated, the switching valve is operated so that the exhaust gas is introduced into the bypass passage in which the unburned gas adsorbent is arranged, and the catalyst is activated. Then, the switching valve is operated so that the exhaust gas is introduced into the catalyst arranged in the exhaust passage.

[0008]

Attention is paid to the temperature characteristics of the unburned gas adsorbent and the catalyst. The unburned gas adsorbent effectively adsorbs HC up to a temperature equal to or lower than the desorption temperature (about 100 to 200 ° C.), but desorbs the adsorbed HC at a temperature higher than the desorption temperature (200 ° C. or higher) ( Purge). Further, the activation temperature of the catalyst is about 250 ° C. in a new state, and it has a characteristic of shifting to a high temperature side as it is used thereafter. On the other hand, since both the unburned gas adsorbent and the catalyst are heated by the heat of the exhaust gas, the temperature rise of the upstream unburned gas adsorbent is faster than the temperature rise of the downstream catalyst.

In the conventional exhaust gas purifying apparatus, no consideration was given to the above-mentioned temperature characteristic difference and the degree of temperature rise of the unburned gas adsorbent and the catalyst. (° C) and the adsorbed HC begins to be purged, the catalyst remains at the activation temperature (about 250
However, there is a problem that the HC which has not reached the temperature (° C.) and is separated from the unburned gas adsorbent is discharged to the atmosphere without being purified by the catalyst.

Further, generally, the exhaust passage is a portion to which vibration from the engine and the road surface is applied fairly strongly, and due to the influence of the back pressure of the exhaust gas, etc. It is difficult to reliably switch between the exhaust passage and the bypass passage, and HC leaks from the portion of the switching valve, and the leaked HC is discharged to the atmosphere without being purified by the catalyst. was there.

Further, in the above exhaust gas purifying apparatus, since the bypass passage is provided in the exhaust passage, there is a problem that the structure of the apparatus is complicated and the size becomes large.

The present invention has been made in view of the above points, and by complementing the temperature characteristic difference between the unburned gas adsorbent and the catalyst, the exhaust gas can be surely purified. The purpose is to provide a device.

[0013]

[Means for Solving the Problems] The above-mentioned problem is that unburned components are adsorbed in the same exhaust system up to a first predetermined temperature, and when the temperature exceeds the first predetermined temperature, the unburned components are not desorbed. A combustion gas adsorbent and a catalytic converter activated at a second predetermined temperature or higher, which is higher than the first predetermined temperature, are provided, and the catalytic converter flows the exhaust gas more than the unburned gas adsorbent. In the exhaust gas purification device arranged on the downstream side with respect to the direction, when the unburned gas adsorbent is at or above the first predetermined temperature at least during warm-up, the catalytic converter is set to the second predetermined temperature. This is solved by an exhaust gas purifying device provided with heating means for heating the catalytic converter so that the temperature becomes equal to or higher than the temperature.

[0014]

In the exhaust gas purifying device configured as described above, when the unburned gas adsorbent is at or above the first predetermined temperature at least during warm-up, the catalytic converter is at or above the second predetermined temperature. Be heated. In other words, when the unburned gas adsorbed by the unburned gas adsorbent is released, the catalytic converter is already in the activated state.

[0015]

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

FIG. 1 is a block diagram showing an exhaust gas purifying apparatus 1 which is an embodiment of the present invention. In the figure, 2 is an exhaust passage for guiding exhaust gas discharged from an engine (not shown), and the exhaust gas purifying apparatus 1 is arranged at an intermediate position of this exhaust passage 2. The exhaust gas is configured to flow from left to right in the figure, so that the left side in the figure is the upstream side and the right side is the downstream side.

The exhaust gas purifying device 1 is roughly composed of a case 3, an HC adsorbent 4, a catalytic converter with a heater (hereinafter, simply referred to as a catalyst with a heater) 5, a temperature sensor 7, a controller 10 and the like. An HC adsorbent 4 for adsorbing HC contained in the exhaust gas is provided on the upstream side in the case 3.
And a catalyst 5 with a heater that purifies HC is disposed on the downstream side. The HC adsorbent 4 and the catalyst 5 are
Arrangement positions are selected so as to be in series in the converter case 3. As described above, the exhaust gas purification device 1 has a structure in which the HC adsorbent 4 and the catalyst with heater 5 are housed in the case 3 in a compact manner, and the device is downsized.

The HC adsorbent 4 is formed by winding a ferritic stainless steel foil excellent in high temperature corrosion resistance to form a metal carrier 4a having a honeycomb structure.
It has a structure in which a is coated with an adsorbent (for example, a porous material such as zeolite, silica, or alumina).
A temperature sensor 7 that measures the temperature of the HC adsorbent 4 is disposed near the position where the HC adsorbent 4 is disposed in the converter case 3. HC adsorbent 4 detected by this temperature sensor 7
The temperature of is supplied to the controller 10.

This HC adsorbent 4 has a desorption temperature (about 100
At temperatures lower than 200 ° C.), HC contained in the introduced exhaust gas is adsorbed to remove the HC from the exhaust gas, and when the temperature is equal to or higher than the desorption temperature,
It has a characteristic of releasing (purging) the adsorbed HC.

The heater-equipped catalyst 5 is formed by winding a ferritic stainless steel foil excellent in high temperature corrosion resistance around the center electrode 6 to form an electrically heatable metal carrier 5a having a honeycomb structure, After coating the metal carrier 5a with alumina, catalyst components (Pt, Pd, Rh, etc.)
Is carried. The activation temperature of this catalyst is about 2
In the state where the temperature is 50 ° C. and the temperature of the catalyst is lower than the activation temperature, the catalyst with heater 5 cannot effectively perform the purifying function, and H
C is not purified.

The plus electrode 11 arranged in the central portion of the heater-equipped catalyst 5 extends downstream from the metal carrier 5a, is then bent into an L-shape, and is drawn out of the converter case 3. The positive electrode 11 is connected to the controller 10. Further, a minus electrode 12 is connected to the metal carrier 5 a forming the heater-equipped catalyst 5, and the minus electrode 12 is also connected to the controller 10. Therefore, the voltage applied to the electrodes 11, 12 from the controller 10 causes the metal carrier 5a to generate heat, and the heater-equipped catalyst 5 is heated by the metal carrier 5a.

The controller 10 controls the temperature sensor 7 to H
While the temperature signal of the C adsorbent 4 is supplied,
Water temperature signal from a water temperature sensor (not shown) installed on the body
(T _w), But also from the distributor (not shown)
Is configured to be supplied with the engine speed signal (R)
There is. In the figure, 13 is a battery, and the controller 1
A metal carrier as well as a driving power source for driving 0
It also functions as a power supply for heating 5a.

The controller 10 controls the center electrode 6 as shown in FIG. 2 based on these various signals supplied. Hereinafter, the heater control operation executed by the controller 10 will be described with reference to FIG. still,
The heater control process shown in FIG. 2 is a routine process executed every 4 ms, for example.

When the heater control process shown in FIG.
First, in step 10 (hereinafter, step is abbreviated as S), the controller 10 reads the engine water temperature t _w based on the water temperature signal from the water temperature sensor. In subsequent S20, the engine coolant temperature t _w read in step S10 to determine whether higher than a predetermined temperature (t _1). When it is determined in S20 that the engine water temperature t _w is lower than the predetermined temperature t ₁ , the process proceeds to S30, and the engine speed (R) is read based on the engine speed signal from the distributor. In subsequent S40, it is determined whether the engine rotation speed R read in S30 is higher than a predetermined rotation speed (R ₁ ). When it is determined in S40 that the engine speed R is higher than the predetermined engine speed R ₁ , the process proceeds to S50.

The above-mentioned steps S10 to S40 require whether or not the engine is in a cold start state, in other words, the catalyst 5 with the heater is in an inactive state and the adsorbing action of the HC adsorbent 4 is required. This is a process of determining whether or not the engine is in the state. At cold start, the engine water temperature _tw is low,
The engine speed R is also low. Therefore, when the engine water temperature and the engine speed are high and the heater-equipped catalyst 5 has already been activated, the processing is terminated without performing the heater control processing of S60 and thereafter.

When it is determined by the processes of S10 to S40 that the engine state is cold start, the temperature (t _H ) of the HC adsorbent 4 supplied from the temperature sensor 7 is determined in S50.
Read. In subsequent S60, the temperature t _H of the HC adsorbent 4 read in S50 is set to the energization start set temperature (t
₂ ) is lower than. Here, the energization start set temperature t ₂ is the desorption temperature of the HC adsorbent 4 (200
The temperature is set based on (° C) and is set to a temperature lower than the desorption temperature of the HC adsorbent 4 by a predetermined value (for example, 150 ± 30 ° C).

When it is determined by the process of S60 that the temperature t _H of the HC adsorbent 4 is higher than the energization start set temperature t ₂ , the process proceeds to S70, and the energization of the metal carrier 5a is started. As a result, the metal carrier 5a is heated,
Along with this, the catalyst with heater 5 is also heated. As described above, the processing from S50 onward is performed at the cold start, and the exhaust gas purifying apparatus 1 is in a state where the exhaust gas is flowing from the engine. Therefore, H due to the heat of the exhaust gas
The C adsorbent 4 and the heater-equipped catalyst 5 are heated and rise in temperature.

However, in the exhaust gas purifying apparatus 1 according to the present invention, since the electrically conductive metal carrier 5a is incorporated in the heater-equipped catalyst 5, the temperature rise of the HC adsorbent 4 and the heater-equipped catalyst 5 are incorporated. The degree of temperature rise can be different. More specifically, the temperature rise of the heater-equipped catalyst 5 can be made faster than the temperature rise of the HC adsorbent 4.

When the energization of the metal carrier 5a is started in S70, the energization timer counter for measuring the energization time starts counting in the subsequent S80. Then, the energization of the metal carrier 5a is continued until the count value (T) of the energization timer counter exceeds a predetermined energization time (T ₁ : eg 10 ± 5 sec) (S90). When the count value T of the energization timer counter exceeds the predetermined energization time T ₁ , the process proceeds to S100, the energization of the metal carrier 5a is stopped, and the count value T of the energization timer counter is reset in S110. Ends.

How the temperatures of the HC adsorbent 4 and the heater-equipped catalyst 5 change by executing the above heater control process will be described with reference to FIG. In the figure, the vertical axis represents the temperatures of the HC adsorbent 4 and the heater-equipped catalyst 5, and the horizontal axis represents time. Also, the solid line in the figure shows the temperature change of the HC adsorbent 4, and the dashed line shows the temperature change of the heater-equipped catalyst 5. still,
The two-dot chain line in the figure shows the temperature change of the conventional catalyst having no heater.

From the figure, it can be seen that in the case of the conventional catalyst without the heater, even if the HC adsorbent 4 reaches the desorption temperature, the catalyst has not yet reached the activation temperature. Therefore, in the exhaust gas purification device having the conventional configuration, the HC purged from the HC adsorbent is not purified by the catalyst and is released to the atmosphere.

[0032] In the exhaust gas purification device 1 according to the present invention, on the other hand, since there is provided a heatable metallic support 5a by the electrical energization of the heater-converter 5, the energization time T ₁ as shown in FIG. In the meantime, the heater-equipped catalyst 5 is a metal carrier 5a.
When the HC adsorbent 4 has reached the desorption temperature, it has already reached the activation temperature. Therefore, even if HC is purged from the HC adsorbent 4, the purged HC is surely purified by the activated heater-equipped catalyst 5, and HC is not released to the atmosphere. As a result, the purification efficiency of HC is improved, and exhaust emission can be significantly reduced.

As described above, the energization start set temperature t
_{Although 2} is set to a temperature lower than the desorption temperature of the HC adsorbent 4 by a predetermined value, this takes a predetermined time to raise the temperature of the catalyst with heater 5 to the activation temperature by energizing the metal carrier 5a. This is because it is necessary to set the energization start set temperature t ₂ as described above, so that the heater-equipped catalyst 5 can be activated when the HC adsorbent 4 reaches the desorption temperature.

FIG. 4 shows an exhaust gas purification device 20 which is a modification of the above-mentioned exhaust gas purification device 1 (in the figure, the same components as those of the exhaust gas purification device 1 shown in FIG. Will be attached and the description thereof will be omitted).

In the exhaust gas purifying apparatus 20 shown in the figure, two cases 21 and 22 are arranged in series, the HC adsorbent 4 is arranged in the case 21 on the upstream side, and the case 22 on the downstream side is arranged. The heater-equipped catalyst 5 is arranged.
In addition, in this modification, in addition to the temperature sensor 7 that detects the temperature of the HC adsorbent 4, a second temperature sensor 23 that detects the temperature of the heater-equipped catalyst 5 is provided. This temperature sensor 23 is also connected to the controller 10, and is configured so that the temperature of the heater-equipped catalyst 5 is supplied to the controller 10.

The exhaust gas purifying apparatus 20 having the above structure is
Converter case 2 in which adsorbent 4 and catalyst with heater 5 are separate
Since it is stored in 1 and 22, HC during maintenance
There is an advantage that the adsorbent 4 and the heater-equipped catalyst 5 can be separated for maintenance work, and the HC adsorbent 4 and the heater-equipped catalyst 5 can be independently replaced even when replacement is required.

FIG. 5 is a flow chart showing the heater control processing of the exhaust gas purification device 20 shown in FIG. 4 (in the figure, the same processing as the processing explained in FIG. 2 is given the same number of steps. The explanation is omitted).

In the figure, the engine state is judged to be cold start by the processing from S10 to S40, and S5
When it is determined that the temperature t _H of the HC adsorbent 4 is higher than the energization start set temperature t ₂ by the processing of 0 and S60, the processing is S
Proceed to 120.

In step S120, the temperature (t _E ) of the heater-equipped catalyst 5 is determined based on the temperature signal supplied from the temperature sensor 23.
Read. In subsequent S130, it is determined whether or not the temperature t _E of the heater-equipped catalyst 5 read in S120 is lower than the set temperature (t ₃ : eg t ₃ = 350 ° C.) corresponding to the activation temperature.

Then, in S130, the catalyst with heater is
Temperature t 5_EIs the set temperature t corresponding to the activation temperature₃ Lower
If not, the process proceeds to S140, where the metal
Energization of the carrier 5a is started. Conversely, in S130
The temperature t of the catalyst 5 with heater _EIs equivalent to the activation temperature
Constant temperature t₃ If it is judged to be higher, catalyst with heater
Since 5 has already been activated, it is a metal in S150.
The power supply to the carrier 5a is stopped.

As described above, the temperature sensor 23 capable of detecting the temperature of the heater-equipped catalyst 5 is provided, and the heater control is performed based on the signal of the temperature sensor 23, so that the heater control is directly performed based on the temperature of the heater-equipped catalyst 5. Therefore, more accurate control can be performed, and HC release to the atmosphere can be reliably prevented.

FIG. 6 shows an exhaust gas purifying apparatus 30 which is another modification of the above-mentioned exhaust gas purifying apparatus 1 (in FIG. 6, the same components as the exhaust gas purifying apparatus 1 shown in FIG. The same reference numerals are given and the description thereof is omitted).

The exhaust gas purifying apparatus 30 shown in the figure is provided with an HC adsorbent 4 and a heater-equipped catalyst 5 inside a case 31, as in the case of the above-mentioned exhaust gas purifying apparatus 10, and immediately downstream thereof. The catalyst 32 is provided.

Similar to the heater-equipped catalyst 5, this catalyst 32 is obtained by coating a metal carrier 32a formed by winding a ferritic stainless steel foil with alumina and then Pt, P.
This is a configuration in which catalyst components such as d and Rh are supported.

As described above, in this modification, since the catalyst 32 is further provided immediately downstream of the heater-equipped catalyst 5, even if HC in the exhaust gas passes through the heater-equipped catalyst 5, the catalyst is immediately discharged. The amount captured in 32 and released to the atmosphere is suppressed. Therefore, the volume of the heater-equipped catalyst 5 can be reduced, and the heat capacity of the metal carrier 5a can be reduced.

Therefore, the time required to heat the heater-equipped catalyst 5 to the active temperature range is shortened, and good exhaust emission can be obtained immediately after cold start, and the amount of electricity required for heating is reduced. You can

Further, the exhaust gas purifying apparatus 30 of this modification is provided with a temperature sensor 33 for detecting the temperature of the catalyst 5 with a heater, instead of the temperature sensor 7 of the exhaust gas purifying apparatus 10 described above. The output terminal of the temperature sensor 33 is connected to the controller 10 as in the case of the temperature sensor 7 of the above embodiment.

That is, the controller 10 controls the energization of the center electrode 6 based on the water temperature signal T _W from the water temperature sensor, the engine speed signal R from the distributor, and the temperature T _E of the heater-equipped catalyst 5.

FIG. 7 shows the exhaust gas purifying apparatus 3 shown in FIG.
It is a flow chart which shows 0 heater control processing. Hereinafter, the operation of the modified apparatus will be described with reference to the same drawing (in the same drawing, the same steps as those described with reference to FIG. 2 are designated by the same step numbers and the description thereof is omitted).

In FIG. 7, when this routine is started every predetermined time, it is first checked in S0 whether the energization flag is "0". This energization flag is a flag that is set to "1" when the center electrode 6 is energized, and is "0" when it is not energized yet, so the process proceeds to S10.

The processing from S10 to S40 is the same as the processing in the apparatus of the above-mentioned embodiment, and it is determined whether or not the engine state is cold start. If, as a result of performing these steps, it is determined that it is not a cold start,
Since it is not necessary to execute any processing, the processing is finished as it is.

If it is determined that it is during cold start, in order to heat the heater-equipped catalyst 5, the current to be applied to the center electrode 6 is calculated in S160, and then the process proceeds to S170 to energize the center electrode 6. Start. At this time, the energizing current is set so that the temperature of the heater-equipped catalyst 5 reaches the activation temperature before the temperature at which the HC adsorbent 4 releases the fuel, from the cooling water temperature of the internal combustion engine and the operating conditions.

Next, in S180, "1" is set to the energization flag to indicate that the center electrode 6 is energized. Therefore, when this routine is started next time,
Since it is determined that the energization flag is "1" in S0, S
Steps 10 to S40 are jumped, and steps S160 to S180 are performed to reach S190.

In S190, a predetermined value is added to the energization time timer T to count the energization time, and it is checked in S200 whether the timer has reached the predetermined value T ₁ . When it is determined that the timer T has not yet reached the predetermined value T ₁ , that is, the center electrode 6 has not been energized for the predetermined time, the temperature t _E of the heater-equipped catalyst 5 is read from the temperature sensor 33 (S
210), it is checked whether the temperature t _E has reached a predetermined temperature t ₃ (S220). This predetermined temperature t ₃ is near the upper limit of the activation temperature region of the catalyst 5 with a heater (for example, 400
℃) is set. That is, in S220, it is determined whether the heater-equipped catalyst 5 is heated to the activation temperature region.

Therefore, if it is determined that t _E has not reached t ₃ , it is necessary to continue heating, so the processing is terminated while the center electrode 6 is still energized, and the timer T is counted up in S200. The above-described processing (S0, S160 to S220) is repeatedly executed until it is determined that the temperature of the catalyst 5 with the heater reaches the activation temperature region in S220.

If it is determined in S200 that the timer T has counted up, or if it is determined in S220 that the heater-equipped catalyst 5 has reached the activation temperature range, the process proceeds to S230 and the energization of the center electrode 6 is stopped. To do.

Next, the energization time timer and the energization flag are reset for the next startup of the routine and the processing is terminated. After that, the central electrode 6 is not energized until it is determined that the engine is cold starting again.

As described above, in the apparatus of this modification, the energization of the central electrode 6 ends when the temperature of the catalyst 5 with a heater reaches the active region. Therefore, even if the set value of the energization time timer is set to be relatively long, wasteful energization does not occur and the catalyst 5 with a heater does not overheat.

Therefore, according to the apparatus of this modification, it is possible to secure a wider temperature range of the catalyst with a heater before the engine is started, which makes it possible to perform appropriate temperature overheating, as compared with the apparatus of the above-mentioned embodiment. Further, since the central electrode 6 is not energized for a time longer than the set time of the energization time timer, even if the temperature sensor 33 fails, the heater-equipped catalyst 5 does not overheat.

As described above, the present modified apparatus 30 directly detects the temperature of the catalyst 5 with a heater to control the energization of the center electrode 6, and has the catalyst 32 immediately downstream of the catalyst 5 with a heater. Therefore, the catalyst with heater 5 can be quickly overheated to the activation temperature range. Therefore, according to the exhaust gas purification device 30, it is possible to obtain good HC emission immediately after the start even in the cold state.

Next, the HC emission improving effect of the exhaust gas purifying device 30 of this modification will be described based on the test results.

The HC adsorbent 4 housed in the exhaust gas purifying apparatus 30 is a zeolite-coated 400 cm.
Consists of ³ metal carriers. The catalyst 5 with a heater is configured by winding a 100 cm ³ metal carrier coated with alumina and then coated with Pt and Rh around the center electrode 6. The catalyst 32 is the heater-equipped catalyst 5.
The same metal carrier of 700 cm ³ is used.

The exhaust gas purifying device 30 having the above-mentioned specifications is connected to an engine having a total displacement of about 2200 cc upstream of the exhaust gas purifying device 30 by means of a three-way catalytic converter to perform an emission test (LA # 4 mode, cold in USA).・ Transient test) was performed.

As a result, the HC purification rate was 92% when the heater-equipped catalyst 5 was not energized, whereas it was 97 when the heater-equipped catalyst 5 was energized according to the flowchart of FIG. It became%.

In this way, by energizing the central electrode 6 to quickly bring the temperature of the catalyst 5 with a heater to the activation temperature region, the HC adsorbent 4 is released along with the temperature rise of the HC adsorbent 4.
The effective purification becomes possible. That is, according to the exhaust gas purifying apparatus of each of the above-described embodiments, it is possible to achieve a remarkable improvement in exhaust emission.

In each of the above-mentioned embodiments, an example in which an electric heater is provided in the catalytic converter as the temperature adding means has been shown, but the temperature adding means is not limited to this, and a burner or the like may be used. is there.

In each of the above embodiments, a metal carrier made of ferritic stainless foil is used as a carrier for the HC adsorbent 4, the heater-equipped catalyst 5, and the catalyst 32, but the present invention is not limited to this. Instead, it may be constituted by a ceramic carrier having cordierite as a main component, or a foam carrier having a ceramic three-dimensional skeleton structure.

[0068]

As described above, according to the present invention, it is possible to raise the temperature of the catalytic converter to the activation temperature before the unburned gas adsorbent reaches the temperature at which the unburned gas is desorbed. Therefore, at the same time that the unburned gas is desorbed from the unburned gas adsorbent, the unburned gas that has desorbed from the unburned gas adsorbent can be purified by the catalytic converter.

As described above, according to the present invention, it is possible to reliably prevent the release of the unburned gas into the atmosphere, always secure a good purification efficiency of the unburned gas, and to significantly reduce the exhaust emission. It has features such as

[Brief description of drawings]

FIG. 1 is a configuration diagram of an exhaust gas purification apparatus that is an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a heater control operation.

FIG. 3 is a diagram showing temperature changes of an HC adsorbent and a catalyst due to execution of a heater control process.

4 is a configuration diagram showing an exhaust gas purification device which is a modification of the exhaust gas purification device shown in FIG. 1. FIG.

FIG. 5 is a flowchart showing a modified example of the heater control operation.

FIG. 6 is a configuration diagram showing an exhaust gas purification device which is another modification of the exhaust gas purification device shown in FIG. 1.

FIG. 7 is a flowchart showing another modification of the heater control operation.

[Explanation of symbols]

 1,20,30 Exhaust gas purifier 2 Exhaust passage 3,21,22,31 Case 4 HC adsorbent 4a, 5a, 32a Metal carrier 5 Heater catalyst 6 Center electrode 7,23,33 Temperature sensor 10 Controller 11,12 Electrode 13 battery

Claims (2)

[Claims] 1. An unburned gas adsorbent that adsorbs unburned components up to a first predetermined temperature in the same exhaust system and desorbs the unburned components when the temperature reaches or exceeds the first predetermined temperature; A catalytic converter that is activated at a second predetermined temperature or higher, which is higher than the predetermined temperature, is arranged downstream of the unburned gas adsorbent in the exhaust gas flow direction. In the exhaust gas purifying apparatus described above, at least during warm-up, when the unburned gas adsorbent is at a temperature equal to or higher than the first predetermined temperature, the catalytic converter is adjusted to reach a temperature equal to or higher than the second predetermined temperature. An exhaust gas purifying device comprising heating means for heating a converter. 2. The exhaust gas purifying apparatus according to claim 1, wherein the heating means is an electric heating means provided in the catalytic converter.