JP3433531B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust purification system for an internal combustion engine.
In particular, it was installed in parallel when the cold start of the internal combustion engine
HC in exhaust before activation of catalyst by one HC adsorbent
To reduce HC in exhaust gas while adsorbing
Of upstream side by combustion of HC released from HC adsorbent
The medium can be activated early and adsorbed on HC adsorbent.
Unnecessary fuel consumption can be avoided by the decomposed combustion of HC
To improve the fuel consumption rate of internal combustion engines.
Related. [0002] An internal combustion engine mounted on a vehicle includes an exhaust gas.
An exhaust purification system equipped with a catalyst that purifies harmful components
I am. The catalyst body of the exhaust purification system is
When the exhaust temperature is low, such as during operation,
It takes time to reach the catalyst activation temperature that can purify the minute
You. Pre-catalyst activation catalyst that has not reached its activation temperature
The body can sufficiently purify HC (unburned hydrocarbons) in exhaust gas
There is no problem. [0003] Exhaust of an internal combustion engine capable of coping with such a problem.
As the air purifying device, those shown in FIGS.
You. The exhaust gas purifying apparatus shown in FIG.
A catalyst 706 is provided in the passage 704 and the catalyst 7
An HC adsorbent 708 is provided on the upstream side of 06. When the internal combustion engine 702 is cold started, the catalyst
HC (unburned hydrocarbons) in exhaust gas before liquefaction
Adsorption (trap) on 708 and catalyst activation
Thereafter, HC is released from the HC adsorbent 708 to remove
By the action of the catalytic substance of the catalyst body 706 together with the harmful components
It purifies it to something harmless. The exhaust gas purifying apparatus shown in FIG.
The catalyst body 706 is provided in the exhaust passage 704 of
An HC adsorbent 708 is provided on the upstream side of the catalyst
By providing a bypass passage 710 bypassing the adsorbent 708
In both cases, a switching valve 712 for switching the exhaust flow direction is provided.
You. At the time of cold start of the internal combustion engine 702, the switching valve
The exhaust gas is caused to flow through the HC adsorbent 708 through the
HC in the exhaust gas before activation is adsorbed on the HC adsorbent 708.
And, after activation of the catalyst, exhausted by the switching valve 712.
Gas is passed through the bypass passage 710 and the HC adsorbent 708
Hazardous components in exhaust gas together with HC desorbed from catalyst
706. The exhaust gas purifying apparatus shown in FIG.
The catalyst body 706 is provided in the exhaust passage 704 of
Introducing HC into the exhaust passage 704 on the upstream side of the catalyst body 706
HC introduction device 708 is provided to ignite the introduced HC
An ignition device 716 for burning is provided. At the time of cold start of the internal combustion engine 702, the HC
HC is introduced into the upstream side of the catalyst body 706 by the input device 714.
The fuel is burned by the ignition device 716, and the catalyst of the catalyst
Promote the start of exhaust gas purification by promoting the temperature rise to the activation temperature
It is something to make. Exhaust for adsorbing HC by the HC adsorbent
As the purifying device, Japanese Patent Application Laid-Open No. 5-57138,
JP-A-5-171929, JP-A-5-321647
Some are disclosed in the gazette. JP-A-5-57138 and JP-A-5-57138
The exhaust gas purifying device disclosed in Japanese Unexamined Patent Publication No.
An HC adsorbent is provided upstream of the catalyst body in the air passage to adsorb HC.
Provide a bypass passage to bypass the material and exhaust
A switching valve is provided to switch the direction when the cold start of the internal combustion engine starts.
Exhaust before catalyst activation is circulated to HC adsorbent by valve replacement.
To adsorb HC and exhaust it by the switching valve after the catalyst is activated.
Circulates air through the bypass to separate it from the HC adsorbent
Harmful components in the exhaust gas are purified by the catalyst
It is something to make. [0011] Japanese Patent Application Laid-Open No. Hei 5-171929 discloses
The exhaust gas purifying device is provided with an HC adsorbent downstream of the catalyst body in the exhaust passage.
Provided a material and provided a bypass to bypass the HC adsorbent
And two switching valves to switch the exhaust flow direction.
During the cold start of the internal combustion engine, the catalyst is activated by two switching valves.
Exhaust gas before circulation is passed through the HC adsorbent to purify the catalyst.
HC that cannot be absorbed is adsorbed by the HC adsorbent,
After activation, the exhaust gas is exhausted by two switching valves to the HC adsorbent and
The exhaust gas is circulated through the bypass passage and purified by the catalyst.
The part of the purified exhaust gas causes HC
To be supplied to the intake manifold. In addition, fuel such as HC is supplied to the exhaust purification device.
It is introduced upstream of the catalyst body and burned, and the catalyst activation temperature of the catalyst body
There is one that promotes early rise by promoting temperature rise
(Japanese Utility Model Laid-Open No. 4-8733). However, the above-mentioned internal combustion engine
At the time of cold start of Seki, HC in exhaust before activation of catalyst is converted to HC.
Adsorb to adsorbent and separate from HC adsorbent after activation of catalyst
Exhaust gas purifier that purifies the removed HC with a catalyst
Currently has a low ability of HC adsorbent to adsorb HC
Problem. [0014] For this reason, the conventional exhaust gas purifying apparatus is not suitable for HC absorption.
It is not enough to lower the HC component value in exhaust gas only with
Means to activate the catalyst body early.
There is a problem you need. As means for activating the catalyst early,
A fuel such as HC is introduced into the upstream side of the catalyst body and burned.
In a gas purifier, a fuel supply for supplying fuel such as HC is provided.
There is a problem that requires a source. This fuel source includes water
That supplies hydrogen by electrolysis or cylinders,
There is one that supplies HC generated in the tank. Therefore, these hydrogen and HC are supplied.
Requires the installation of electrolysis equipment and cylinders
This has the disadvantage of increasing the size of the device,
Deterioration of fuel consumption rate by supplying HC in tank
There are inconveniences. [0017] Therefore, the above disadvantages are eliminated.
In order to eliminate this problem, the present invention
Branching into at least two branch exhaust passages,
To the upstream branch and downstream branch of each branch exhaust passage.
Upstream switching valve and downstream switching for switching exhaust flow direction
Provide a valve in the exhaust passage upstream of the upstream branch.
With the upstream catalyst body provided,
A downstream catalyst is provided in the downstream exhaust passage, and
An HC adsorbent is provided in each of the air passages, and each of these HC adsorbents is
One end is branched to each of the branch exhaust passages downstream of the
And the other end is gathered from the upstream catalyst body.
Also provided an HC introduction passage communicating with the exhaust passage on the upstream side,
Each time the internal combustion engine is started, the branch exhaust passages are alternately exhausted.
Switching between the air circulation state and the exhaust stop state,
HC is adsorbed on the HC adsorbent in the branch exhaust passage
And the HC in the branch exhaust passage in the exhaust stopped state.
The HC adsorbing passage is released by releasing the HC adsorbed by the adsorbent.
Introduced into the exhaust passage upstream of the upstream catalyst body
The upstream switching valve and the downstream switching
Control means for switching control of the valve is provided. According to the structure of the present invention, the exhaust emission control device is
Control means, each time the internal combustion engine is started, each branch exhaust passage
Alternately between the exhaust flow state and the exhaust stop state,
HC is adsorbed by the HC adsorbent in the branch exhaust passage in the airflow state.
H of the branch exhaust passage which
Releases the HC adsorbed by the C adsorbent to the HC introduction passage
The fuel is introduced into the exhaust passage on the upstream side of the
Switching control of upstream switching valve and downstream switching valve to burn
Control in parallel at the time of cold start of the internal combustion engine.
HC can be adsorbed by one of the adsorbed HC adsorbents,
The HC released from the other side of the HC adsorbent is
The fuel can be combusted in the exhaust passage on the upstream side. Embodiments of the present invention will be described below with reference to the drawings.
I do. 1 to 4 show a first embodiment of the present invention.
It is. In FIG. 1, 2 is an internal combustion engine, 4 is an intake passage,
6 is the intake manifold, 8 is the exhaust manifold, 10 is the exhaust
It is a passage. The internal combustion engine 2 includes an exhaust purification device 12.
Provided. The exhaust gas purification device 12 is located in the middle of the exhaust passage 10.
Is branched into at least two branch exhaust passages.
You. In the first embodiment, the exhaust passage 10
The inside is branched and provided to first and second branch exhaust passages 14 and 16.
ing. The first and second branch exhaust passages 14 and 16
The upstream branch portion 18 and the downstream branch portion 20 that are branched are
The upstream switching valve 22 and the downstream for switching the exhaust flow direction, respectively.
A side switching valve 24 is provided. Upstream switching valve 22 and downstream
The side switching valve 24 is connected to a switching valve control unit 26. Exhaust gas upstream of the upstream branch portion 18
In the passage 10, a warm-up upstream catalyst body 28 is provided.
Provided. Exhaust gas downstream of the downstream branch portion 20
The passage 10 is provided with a downstream catalyst body 30 serving as a main body.
I have. Also, the first and second branch exhaust passages 14 and 16
Has first and second HC adsorbents 32 and 34, respectively.
You. The exhaust gas purifying device 12 includes first and second HCs.
First and second branch exhaust passages downstream of the adsorbents 32 and 34
One end is branched to each of the roads 14 and 16 to communicate with each other.
And the other end is gathered and the upstream side of the upstream catalyst body 28 is
An HC introduction passage 36 communicating with the exhaust passage 10 is provided.
You. The HC introduction passage 36 is provided with first and second branch exhaust gases.
The first and second HC intakes 38 and 40 of passages 14 and 16
First and second HC introduction passage portions 42.4 each communicating with one end side
4 and the first and second HC introduction passage portions 42 and 44 are provided.
Of third HC, one end of which is connected to the other end where
A passage 46 is provided, and the other end of the third HC introduction passage 46 is provided.
The H side of the exhaust passage 10 upstream of the upstream catalyst body 28
It is provided in communication with the C inlet 48. First and second HC introduction passages 42 and 44 and
The collecting section 50 of the third HC introduction passage 46 includes an HC control section.
52 are provided. The HC control unit 52 includes first and second HCs.
Select the introduction passages 42 and 44 as the third HC introduction passage 46
And the first to third HC introduction passages.
The HC introduction control valve 54 that shuts off the communication between the roads 42 to 46 is
Have. Exhaust gas upstream of the upstream catalyst body 28
The passage 10 has an exhaust igniter 5 close to the HC inlet 48.
6 are provided. The exhaust igniter 56 includes an exhaust ignition control unit 5
8 is connected. Also, from the upstream catalyst body 28
Also, the downstream exhaust passage 10
An exhaust temperature sensor 60 for detecting the exhaust temperature is provided. The exhaust gas purification device 12 has first and second H
First and second branch exhaust upstream of the C adsorbents 32 and 34
Secondary air supply passage for supplying secondary air to passages 14 and 16
62 are provided. The secondary air supply passage 62 has a first
First and second secondary air supply ports of two-branch exhaust passages 14 and 16
First and second secondary air communicating with one end of each of 64 and 66
Supply passages 68 and 70 are provided, and these first and second secondary
One end is connected to the other end where the air supply passages 68 and 70 are assembled.
A third secondary air supply passage portion 72 that is communicated is provided. The other end of the third secondary air supply passage 72 is
It is connected to the secondary air supply device 74. Secondary air supply
The device 74 includes an air pump for supplying heated secondary air.
And a heat source 78. In addition, the first and second
Secondary air supply passages 68 and 70 and third secondary air supply passage
The collecting section 80 of the section 72 includes a third secondary air supply passage section 72.
To the first and second secondary air supply passages 68 and 70
And the first to third secondary air supply passages.
The secondary air control valve 82 that shuts off the communication between the
Provided. The upstream switching valve 22 and the downstream switching valve 2
4, switching valve controller 26, HC controller 52, and exhaust ignition control
Section 58, exhaust temperature sensor 60, secondary air supply device 74,
The secondary air control valve 82 is a control unit of the exhaust purification device 12.
84. The control means 84 includes an internal combustion engine
Engine speed of Seki 2 and operation of starter motor (not shown)
Input various signals such as status and throttle opening
Sensors 86 are connected. The control means 84 controls the exhaust gas temperature sensor 60 and its
Switching by various signals input from other sensors 86
The valve control unit 26, the HC control unit 52, the exhaust ignition control unit 58
Controls the secondary air supply device 74 and the secondary air control valve 82
Each time the internal combustion engine 2 is started, the first and second branch exhaust passages 1
4 ・ 16 alternately switched between exhaust circulation state and exhaust stop state
For example, the first branch exhaust passage 14 in the exhaust circulation state
The first HC adsorbent 32 adsorbs HC and exhausts
For example, the second HC in the second branch exhaust passage 16 in a stopped state
The HC adsorbed by the adsorbent 34 is released, and the HC introduction passage
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0 and the upstream switching valve 22 and the lower
The flow-side switching valve 24 is switched and controlled. Next, the operation will be described. At the time of cold start of the internal combustion engine 2, the upstream catalyst
Body 28 and downstream catalyst body 30 are sufficiently activated
Therefore, HC in exhaust gas cannot be sufficiently purified. Therefore, the control means 84 controls the cooling of the internal combustion engine 2.
When the machine is started, control is performed as shown in FIGS. In addition,
The upstream switching valve 22 and the downstream switching valve 24 are
Is stopped, the first branch exhaust passage 14 is set in an exhaust flow state.
And the second branch exhaust passage 16 is set in the exhaust stop state.
It is assumed that the switching is controlled as described above. As shown in FIG. 2, the control means 84 controls the
When started (step 100), read various signals
(Step 102), whether or not the internal combustion engine 2 has been started
Is determined (step 104). When this determination (step 104) is NO
Returns to reading of various signals (step 102)
I do. If this determination (step 104) is YES,
Switching control of HC introduction control valve 54 and turning on exhaust igniter 56
Of air pump 76 and heat source 78 and secondary air control valve
The processing with the switching control of 82 is performed (step 106). In this process (step 106),
As shown in FIG. 3, the control means 84 operates when the internal combustion engine 2 is started.
First branch by upstream switching valve 22 and downstream switching valve 24
The exhaust passage 14 is set in an exhaust circulation state, and the second branch exhaust
The air passage 16 is in the exhaust stop state, and the HC control unit 52
To control the HC introduction control valve 54 to switch the second HC
When the entrance passage portion 44 communicates with the third HC introduction passage portion 46,
In both cases, the first HC introduction passage 42 is shut off. The control means 84 controls the secondary air control valve 8
2 to control the third secondary air supply passage 7
2 to the second secondary air supply passage 70 and
The first secondary air supply passage 68 is shut off and the secondary air supply
The air pump 76 and the heat source 78 are operated by the device 74
Second branch exhaust passage 1 upstream of second HC adsorbent 34
Supply heated secondary air (for example, about 300 ° C) to 6
I do. The first branch exhaust passage in the exhaust circulation state
The first HC adsorbent 32 in the passage 14 adsorbs HC in the exhaust gas.
You. The second branch exhaust passage 16 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. The released HC is derived from HC
Exhaust gas upstream of the upstream catalyst body 28 through the inlet passage 36
The exhaust point introduced into the passage 10 and emitted by the exhaust ignition control unit 58
The HC is burned by turning on the firearm 56. As a result, the upstream catalyst body 28 is
The temperature is raised by combustion, and activation is promoted. Following the above processing (step 106),
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 108), and the temperature T ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 110). When this determination (step 110) is NO
Is the exhaust gas temperature T ₁ Is detected (step 108)
On. When this judgment (step 110) is YES
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
Switching control of the HC introduction control valve 54 and the O
Stop of FF, air pump 76 and heat source 78 and secondary air control
Processing for switching control of the control valve 82 is performed (step 11).
2), return (step 114). In the above processing (step 112),
The control means 84 includes, as shown in FIG.
The first branch exhaust passage 1 is controlled by the switching control of the downstream switching valve 24.
4 and the second branch exhaust passage 16
Into the exhaust circulation state, and the HC control unit 52 controls the introduction of HC.
The switching control of the control valve 54 is performed to control the first to third HC introduction passage portions 4.
The communication between 2 and 46 is cut off. The control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the exhaust igniter 56 is turned off. Thus, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust circulation state
The second HC adsorbent 34 of the sixth HC
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. This state is maintained until the internal combustion engine 2 is stopped.
Will be maintained. When the stopped internal combustion engine 2 is restarted,
The means 84 performs control as shown in FIGS. This and
The upstream switching valve 22 and the downstream switching valve 24 are
As described above, when the first branch exhaust passage 14 is set to the exhaust stop state,
First, the second branch exhaust passage 16 is set to the exhaust circulation state.
Switching is controlled. As shown in FIG. 2, the control means 84 controls the
When started (step 100), read various signals
(Step 102), whether or not the internal combustion engine 2 has been started
Is determined (step 104). When this determination (step 104) is NO
Returns to reading of various signals (step 102)
I do. If this determination (step 104) is YES,
Switching control of HC introduction control valve 54 and turning on exhaust igniter 56
Of air pump 76 and heat source 78 and secondary air control valve
The processing with the switching control of 82 is performed (step 106). In this process (step 106), the control
As shown in FIG. 4, when the internal combustion engine 2 is restarted,
First branch by upstream switching valve 22 and downstream switching valve 24
The exhaust passage 14 is brought into an exhaust stop state and the second branch exhaust is performed.
The air passage 16 is in an exhaust flow state, and the HC control unit 52
To control the HC introduction control valve 54 to switch the first HC
When the entrance passage section 42 communicates with the third HC introduction passage section 46,
In both cases, the second HC introduction passage portion 44 is shut off. The control means 84 controls the secondary air control valve 8
2 to control the third secondary air supply passage 7
2 in communication with the first secondary air supply passage 68.
The second secondary air supply passage 70 is shut off, and the secondary air supply
The air pump 76 and the heat source 78 are operated by the device 74
First branch exhaust passage 1 upstream of first HC adsorbent 32
4 is supplied with heated secondary air. The second branch exhaust passage in the exhaust circulation state
The second HC adsorbent 34 in the passage 16 adsorbs HC in the exhaust gas.
You. The first of the first branch exhaust passages 14 in the exhaust stopped state
The HC adsorbent 32 is heated by the supplied secondary air.
Release and release HC. The released HC is derived from HC
Exhaust gas upstream of the upstream catalyst body 28 through the inlet passage 36
The exhaust point introduced into the passage 10 and emitted by the exhaust ignition control unit 58
The HC is burned by turning on the firearm 56. As a result, the upstream catalyst body 28 is
The temperature is raised by combustion, and activation is promoted. Following the above processing (step 106),
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 108), and this temperature is
It is determined whether the activation temperature threshold Ta has been exceeded.
(Step 110). When this determination (step 110) is NO
Is the exhaust gas temperature T ₁ Is detected (step 108)
On. When this judgment (step 110) is YES
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
Switching control of the HC introduction control valve 54 and the O
Stop of FF, air pump 76 and heat source 78 and secondary air control
Processing for switching control of the control valve 82 is performed (step 11).
2), return (step 114). In the above processing (step 112),
The control means 84 includes, as shown in FIG.
The first branch exhaust passage 1 is controlled by the switching control of the downstream switching valve 24.
4 and the second branch exhaust passage 16
In the exhaust stop state, and the HC control unit 52 controls the introduction of HC.
The switching control of the control valve 54 is performed to control the first to third HC introduction passage portions 4.
The communication between 2 and 46 is cut off. The control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the exhaust igniter 56 is turned off. As a result, the second minute in the exhaust stopped state
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
4 during the operation of the internal combustion engine 2.
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. As described above, the exhaust gas purification device 12 is controlled by the control
By means of the stage 84, the first and second minutes each time the internal combustion engine 2 is started
Exhaust flow state and exhaust stop alternately in branch exhaust passages 14 and 16
The state is switched to the state, and the exhaust flow state is set, for example, the first branch.
HC is adsorbed by the first HC adsorbent 32 in the exhaust passage 14.
And the second branch exhaust passage 1 in which the exhaust is stopped.
Release HC adsorbed by the second HC adsorbent 34 of No. 6
The upstream side of the upstream catalyst body 28 by the HC introduction passage 36
Switch to the upstream side so as to be introduced into the exhaust passage 10 for combustion.
The switching control of the valve 22 and the downstream switching valve 24 is performed. As a result, the exhaust gas purifying device 12 is
To control the switching of the switching valve 22 and the downstream switching valve by 24
Thus, the first and the second motors provided in parallel when the internal
2 HC can be adsorbed by one of the HC adsorbents 32 and 34.
And release HC released from the other side on the upstream side.
The combustion in the exhaust passage 10 upstream of the catalyst body 28
Can be. For this reason, the exhaust gas purification device 12
First and second HC adsorption provided in parallel at the time of cold start of the engine 2
H in exhaust before activation of the catalyst by one of the materials 32 and 34
C in adsorbed to reduce HC in exhaust gas
At the same time as the HC
The medium 28 can be activated at an early stage.
Release of HC adsorbed on the other of the second HC adsorbents 32 and 34
Unnecessary fuel consumption because decombustion does not require separate fuel
Can be avoided, and the fuel consumption rate can be improved. In the first embodiment, the secondary air supply
The secondary air heated by the supply device 74 is supplied to the first and second HCs.
Releases adsorbed HC by supplying to adsorbents 32 and 34
However, part of the exhaust gas of the internal combustion engine 2 is absorbed by the first and second HCs.
Exhaust gas supply to supply HC 32 and 34 to release HC
Steps can also be provided. In this case, an air pump or
Eliminates the need for a heat source and can reduce costs
You. FIGS. 5 to 8 show a second embodiment of the present invention.
It is something. In this second embodiment, FIG.
The parts having the same functions as in the first embodiment are denoted by the same reference numerals.
The description will be omitted, and the characteristic portions will be denoted by reference numerals.
You. The exhaust gas purifying apparatus 12 of the second embodiment is
As shown in FIG. 5, a third HC introduction passage portion of the HC introduction passage 36
46, an HC sensor 88 for detecting the concentration of HC is provided.
In the C control unit 52, the HC supply device 90 is connected to the HC supply passage 92.
The HC sensor 88 and the HC supply device 9
0 is connected to the control means 84 and provided. HC supply device
90 is, for example, a fuel tank (not shown) of the internal combustion engine 2
Or a canister (not shown). Control means of the exhaust gas purifying apparatus 12 of the second embodiment
Reference numeral 84 denotes a state when the internal combustion engine is cold started, as shown in FIGS.
Control. The upstream switching valve 22 and the downstream switching
The valve 24 is connected to the first branch exhaust passage 1 when the internal combustion engine 2 is stopped.
4 and the second branch exhaust passage 16
Switching control so that
I do. As shown in FIG. 6, the control means 84
When started (step 200), read various signals
(Step 202), whether or not the internal combustion engine 2 is started
Is determined (step 204). When this determination (step 204) is NO
Returns to reading of various signals (step 202)
I do. If this determination (step 204) is YES,
Switching control of HC introduction control valve 54 and turning on exhaust igniter 56
Of air pump 76 and heat source 78 and secondary air control valve
A process with the switching control of 82 is performed (step 206). In this processing (step 206),
When the internal combustion engine 2 is started, as shown in FIG.
The first branch exhaust passage 14 is set in an exhaust flow state and the
The two-branch exhaust passage 16 is in the exhaust stop state,
The C introduction passage portion 44 communicates with the third HC introduction passage portion 46
And the first HC introduction passage portion 42 is shut off. The control means 84 controls the third secondary air supply.
The passage 72 is communicated with the second secondary air supply passage 70.
And the first secondary air supply passage 68 is shut off,
By operating the pump 76 and the heat source 78, the second HC adsorbent 34
The secondary heated in the second branch exhaust passage 16 on the more upstream side
Supply air. The first branch exhaust passage in the exhaust circulation state
The first HC adsorbent 32 in the passage 14 adsorbs HC in the exhaust gas.
You. The second branch exhaust passage 16 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Following the above processing (step 206), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 208), and the temperature T ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 210). When this determination (step 210) is NO
Is H of the third HC introduction passage 46 by the HC sensor 88.
The concentration of C is detected (step 212), and air-fuel by HC is detected.
It is determined whether the ratio is in the flammable region (step 214). When this judgment (step 214) is YES
The exhaust temperature T ₁ Is detected (step 208).
To When this determination (step 214) is NO
Performs the process of correcting the air-fuel ratio (step 216),
Exhaust temperature T ₁ Return to step 208
You. The air-fuel ratio correction process (step 216)
In the control unit 84, the HC control unit 52
The switching control of the introduction control valve 54 causes the HC supply passage 92 to
It is communicated with the 3HC introduction passage portion 46. HC supply device 90
Is combined with HC released from the second HC adsorbent 34.
To the exhaust passage 10 upstream of the upstream catalyst body 28.
And is burned by turning on the exhaust igniter 56,
The catalyst 28 is heated to promote activation. On the other hand, if the judgment (step 210) is YES
In the case, the switching of the upstream switching valve 22 and the downstream switching valve 24 is performed.
Control and switching control of the HC introduction control valve 54 and the exhaust igniter 56
OFF, stop of air pump 76 and heat source 78 and secondary empty
Processing for switching control of the air control valve 82 is performed (step 21).
8) Return (step 220). In the above processing (step 218),
The control means 84 includes, as shown in FIG.
The first branch exhaust passage 1 is controlled by the switching control of the downstream switching valve 24.
4 and the second branch exhaust passage 16
The exhaust gas circulation state is set, and HC introduction control is performed by the HC control unit 52.
The switching of the valve 54 is controlled so that the first to third HC introduction passage portions 42
To 46 are cut off and the HC supply device 90
When supplying C, the communication of the HC supply passage 92 is cut off
I do. The control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the exhaust igniter 56 is turned off. As a result, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust circulation state
The second HC adsorbent 34 of the sixth HC
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. This state is maintained until the internal combustion engine 2 is stopped.
Will be maintained. When the stopped internal combustion engine 2 is restarted,
The means 84 performs control as shown in FIGS. This and
The upstream switching valve 22 and the downstream switching valve 24 are
As described above, when the first branch exhaust passage 14 is set to the exhaust stop state,
First, the second branch exhaust passage 16 is set to the exhaust circulation state.
Switching is controlled. As shown in FIG. 6, the control means 84
Once started (step 200), as before,
Execute (Step 202) to (Step 206)
You. In this processing (step 206), the control
As shown in FIG. 8, the means 84 is provided when the internal combustion engine 2 is restarted.
The first branch exhaust passage 14 is set to the exhaust stop state and the
The two-branch exhaust passage 16 is in an exhaust circulation state, and is HC controlled.
The control unit 52 controls the switching of the HC introduction control valve 54 to
The 1HC introduction passage portion 42 communicates with the third HC introduction passage portion 46
And the second HC introduction passage portion 44 is shut off. The control means 84 controls the secondary air control valve 8
2 to control the third secondary air supply passage 7
2 in communication with the first secondary air supply passage 68.
The second secondary air supply passage 70 is shut off, and the secondary air supply
The air pump 76 and the heat source 78 are operated by the device 74
First branch exhaust passage 1 upstream of first HC adsorbent 32
4 is supplied with heated secondary air. The second branch exhaust passage in the exhaust circulation state
The second HC adsorbent 34 in the passage 16 adsorbs HC in the exhaust gas.
You. The first of the first branch exhaust passages 14 in the exhaust stopped state
The HC adsorbent 32 is heated by the supplied secondary air.
Release and release HC. The released HC is derived from HC
Exhaust gas upstream of the upstream catalyst body 28 through the inlet passage 36
It is introduced into the passage 10 and burns when the exhaust igniter 56 is turned on.
To promote activation by raising the temperature of the upstream catalyst body 28.
You. Following the above processing (step 206), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 208), and the temperature T ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 210). When this determination (step 210) is NO
Is H of the third HC introduction passage 46 by the HC sensor 88.
The concentration of C is detected (step 212), and air-fuel by HC is detected.
It is determined whether the ratio is in the flammable region (step 214). If this determination (step 214) is YES
The exhaust temperature T ₁ Is detected (step 208).
To When this determination (step 214) is NO
Performs the process of correcting the air-fuel ratio (step 216),
Exhaust temperature T ₁ Return to step 208
You. The air-fuel ratio correction process (step 216)
In the control unit 84, the HC control unit 52
The switching control of the introduction control valve 54 causes the HC supply passage 92 to
It is communicated with the 3HC introduction passage portion 46. HC supply device 90
From the first HC adsorbent 32 is combined with the HC released from the first HC adsorbent 32.
To the exhaust passage 10 upstream of the upstream catalyst body 28.
And is burned by turning on the exhaust igniter 56,
The catalyst 28 is heated to promote activation. On the other hand, if the judgment (step 210) is YES
In the case, the switching of the upstream switching valve 22 and the downstream switching valve 24 is performed.
Control and switching control of the HC introduction control valve 54 and the exhaust igniter 56
OFF, stop of air pump 76 and heat source 78 and secondary empty
Processing for switching control of the air control valve 82 is performed (step 21).
8) Return (step 220). In the above processing (step 218),
The control means 84 includes, as shown in FIG.
The first branch exhaust passage 1 is controlled by the switching control of the downstream switching valve 24.
4 and the second branch exhaust passage 16
In the exhaust stop state, and the HC control unit 52 controls the introduction of HC.
The switching control of the control valve 54 is performed to control the first to third HC introduction passage portions 4.
The communication between 2 and 46 is cut off, and
When supplying HC, the communication of the HC supply passage 92 is blocked.
Refuse. The control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the exhaust igniter 56 is turned off. As a result, the second minute in the exhaust stopped state
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
4 during the operation of the internal combustion engine 2.
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. As described above, the exhaust gas purifying apparatus of the second embodiment
The device 12 is controlled by the control means 84 when the internal combustion engine 2 is started.
The first and second branch exhaust passages 14 and 16 alternately flow
Switch to the exhausted state and the exhausted state.
For example, the first HC adsorbent 32 of the first branch exhaust passage 14
HC is adsorbed and exhaust is stopped.
Adsorbed by the second HC adsorbent 34 in the two-branch exhaust passage 16
The HC is discharged, and the upstream side catalyst is
The fuel is introduced into the exhaust passage 10 on the upstream side of 28 and burned.
Control the upstream switching valve 22 and the downstream switching valve 24
In addition, the upstream catalyst 28 is controlled by the HC sensor 88.
Detects the concentration of HC introduced into the exhaust passage 10 on the upstream side
To control the HC control unit 52 to obtain an appropriate air-fuel ratio.
You. Thus, the exhaust gas purifying device 12 is
The first and second HC intakes provided in parallel when the cold start of the fuel engine 2 is started
HC can be adsorbed by one of the materials 32 and 34
And the HC released from the other
Combustion in the exhaust passage 10 upstream of
In addition, HC can be appropriately burned. this
Therefore, the exhaust gas purifying apparatus 12 performs the cold start of the internal combustion engine 2.
One of the first and second HC adsorbents 32 and 34 sometimes provided in parallel.
By adsorbing HC in exhaust gas before catalyst activation
HC in the air can be reduced and from the other
Combustion of the separated HC quickly causes the upstream catalyst body 28 to
The first and second HC adsorbents 3 can be activated.
Separately due to desorption combustion of HC adsorbed on the other side of 2.34
Without the need for fuel, and properly controlling HC supply
Controllable fuel vapor from fuel tanks and canisters
Can be used to avoid unnecessary fuel consumption,
The rate can be further improved. FIGS. 9 to 12 show a third embodiment of the present invention.
It is shown. In this third embodiment, FIG.
Parts that perform the same functions as in the first embodiment are given the same reference numerals.
The description will be omitted, and the description will be given by attaching the reference numerals to the characteristic portions.
You. The exhaust gas purifying apparatus 12 of the third embodiment is shown in FIG.
As shown in FIG. 9, the middle of the exhaust passage 10 is
In addition to branching into the air passages 14 and 16,
The third branch exhaust passage 94 is branched and provided. 1st and 1st
The two-branch exhaust passages 14 and 16 have first and second HC intakes, respectively.
The dressing materials 32 and 34 are provided. In the third exhaust passage 94
Does not provide an HC adsorbent and bypasses exhaust gas. The upstream branch section 18 and the downstream branch section 20
The upstream switching valve 22 and the downstream switching valve 24 provided respectively are
Exhaust temperature T ₁ To switch the exhaust flow direction. Upstream
The switching valve 22 and the downstream switching valve 24 are connected to an upstream catalyst body 28.
Of the exhaust gas detected by the exhaust gas temperature sensor 60 provided on the downstream side of
Temperature T ₁ Is the temperature threshold at which the HC catalyst is thermally degraded
If the temperature exceeds Tc (for example, 500 ° C.), the exhaust is exhausted to the third exhaust
Switching control is performed so as to bypass the exhaust passage 94.
You. Control means for the exhaust gas purifying apparatus 12 of the third embodiment.
Reference numeral 84 denotes a state when the internal combustion engine 2 is cold started, as shown in FIGS.
Control is performed as follows. In addition, the upstream switching valve 22 and the downstream
When the internal combustion engine 2 is stopped, the switching valve 24 is configured to switch between the first and second branches.
While the exhaust passages 14 and 16 are in the exhaust stop state,
Switching control so that the branch exhaust passage 94 is in an exhaust circulation state
It is assumed that As shown in FIG. 10, the control means 84
Is started (step 300), various signals are read.
(Step 302), whether the internal combustion engine 2 has been started
It is determined whether or not it is (step 304). This judgment (step
If step 304) is NO, reading of various signals (step
Return to step 302). This judgment (Step 30)
If 4) is YES, the upstream switching valve 22 and the downstream cutoff
Switching control of the switching valve 24 and switching control of the HC introduction control valve 54
Turning on the exhaust igniter 56 and turning on the air pump 76 and heat source 78
The operation and the switching control of the secondary air control valve 82 are performed.
(Step 306). In this processing (step 306),
The control means 84 includes, as shown in FIG.
And the downstream side switching valve 24 to control the
The first branch exhaust passage 14 is set in an exhaust flow state and the
Stops exhausting the two-branch exhaust passage 16 and the third-branch exhaust passage 94
And the second HC introduction passage portion 44 is connected to the third HC introduction passage.
And the first HC introduction passage portion 42
Cut off. The control means 84 controls the supply of the third secondary air.
The passage 72 is communicated with the second secondary air supply passage 70.
And the first secondary air supply passage 68 is shut off,
By operating the pump 76 and the heat source 78, the second HC adsorbent 34
The secondary heated in the second branch exhaust passage 16 on the more upstream side
Supply air. The first branch exhaust passage in the exhaust circulation state
The first HC adsorbent 32 in the passage 14 adsorbs HC in the exhaust gas.
You. The second branch exhaust passage 16 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Following the above processing (step 306),
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 308), and the temperature T ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 310). When this determination (step 310) is NO
Is the exhaust gas temperature T ₁ Is detected (step 308).
On. When this judgment (step 310) is YES
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
Switching control of the HC introduction control valve 54 and the O
Stop of FF, air pump 76 and heat source 78 and secondary air control
Processing for switching control of the control valve 82 is performed (step 31).
2). In the above processing (step 312),
The control means 84 includes, as shown in FIG.
And the downstream side switching valve 24 controls the first suction side
The branch exhaust passage 14 and the third branch exhaust passage 94 are in an exhaust stop state.
And the second branch exhaust passage 16 is in an exhaust circulation state.
And the HC introduction control valve 54 is switched by the HC control unit 52
Controlled communication of the first to third HC introduction passages 42 to 46
Cut off. The control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the exhaust igniter 56 is turned off. As a result, the first minute in the exhaust stopped state
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust circulation state
The second HC adsorbent 34 of the sixth HC
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. Following the above processing (step 312),
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 314), and the temperature T ₁ Is H
Whether or not the threshold value Tc of the temperature at which the C adsorbent thermally deteriorates is exceeded
Is determined (step 316). When this determination (step 316) is NO
Is the exhaust gas temperature T ₁ Is detected (step 314).
On. When this determination (step 316) is YES
Controls switching of the upstream switching valve 22 and the downstream switching valve 24
And the first and second branch exhaust passages 14 and 16 are in an exhaust stopped state.
And the third branch exhaust passage 94 is set in an exhaust circulation state.
(Step 318), and returns (step 32).
0). Thus, the temperature at which the HC adsorbent thermally degrades
Exceeding the threshold Tc of the third branch exhaust passage 94
And prevent thermal degradation of the HC adsorbent
You. This state is maintained until the internal combustion engine 2 is stopped.
Will be maintained. When the stopped internal combustion engine 2 is restarted,
The means 84 performs control as shown in FIGS. This
, The upstream switching valve 22 and the downstream switching valve 24
As described above, the first and second branch exhaust passages 14 and 16 are exhaust stopped.
To the stop state and exhaust gas flows through the third branch exhaust passage 94.
The switching is controlled to be in the state. As shown in FIG. 10, the control means 84
Starts (step 300), as described above,
Execute (Step 302) to (Step 306)
You. In this processing (step 306),
The control means 84 includes, as shown in FIG.
The second branch exhaust passage 1 is controlled by controlling the switching of the
6 and the first branch exhaust passage 14
-The third branch exhaust passage 94 is set to the exhaust stop state, and the first HC
The introduction passage 42 is communicated with the third HC introduction passage 46.
At the same time, the second HC introduction passage 44 is shut off. Further, the control means 84 controls the third secondary air supply.
The passage 72 communicates with the first secondary air supply passage 68.
And the second secondary air supply passage 70 is shut off,
The first HC adsorbent 32 by operating the pump 76 and the heat source 78.
Secondary heated in the first branch exhaust passage 14 on the more upstream side
Supply air. The second branch exhaust passage in the exhaust circulation state
The second HC adsorbent 34 in the passage 16 adsorbs HC in the exhaust gas.
You. The first of the first branch exhaust passages 14 in the exhaust stopped state
The HC adsorbent 32 is heated by the supplied secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Following the above processing (step 306),
The temperature T of the exhaust gas is detected by the air temperature sensor 60. ₁ Is detected (step
308), this temperature T ₁ Of the temperature at which the catalyst is activated
It is determined whether the threshold Ta has been exceeded (step 31).
0). When this determination (step 310) is NO
Is the exhaust gas temperature T ₁ Is detected (step 308).
On. When this judgment (step 310) is YES
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
Switching control of the HC introduction control valve 54 and the O
Stop of FF, air pump 76 and heat source 78 and secondary air control
Processing for switching control of the control valve 82 is performed (step 31).
2). In the above processing (step 312),
The control means 84 includes, as shown in FIG.
The second branch exhaust passage 1 is controlled by the switching control of the downstream switching valve 24.
6. When the third branch exhaust passage 94 is set to the exhaust stop state,
First, the first branch exhaust passage 14 is set in an exhaust flow state, and HC control is performed.
The switching control of the HC introduction control valve 54 is performed by the
-Communication between the third HC introduction passage portions 42 to 46 is interrupted. Further, the control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the exhaust igniter 56 is turned off. As a result, the second exhaustion stopped state
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
4 during the operation of the internal combustion engine 2.
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. Following the above processing (step 312),
Similarly, the exhaust gas temperature T detected by the exhaust gas temperature sensor 60 ₁ of
Detection (step 314), this temperature T ₁ Is the threshold Tc
Is determined (step 316). When this determination (step 316) is NO
Is the exhaust gas temperature T ₁ Is detected (step 314).
On. When this determination (step 316) is YES
Controls switching of the upstream switching valve 22 and the downstream switching valve 24
And the first and second branch exhaust passages 14 and 16 are in an exhaust stopped state.
And the third branch exhaust passage 94 is set in an exhaust circulation state.
(Step 318), and returns (step 32).
0). Thus, the temperature at which the HC adsorbent thermally degrades
Exceeding the threshold Tc of the third branch exhaust passage 94
And prevent thermal degradation of the HC adsorbent
You. As described above, the exhaust gas purifying apparatus of the third embodiment is described.
The device 12 is controlled by the control means 84 when the internal combustion engine 2 is started.
The first and second branch exhaust passages 14 and 16 alternately flow
Switch to the exhausted state and the exhausted state.
For example, the first HC adsorbent 32 of the first branch exhaust passage 14
HC is adsorbed and exhaust is stopped.
Adsorbed by the second HC adsorbent 34 in the two-branch exhaust passage 16
The HC is discharged, and the upstream side catalyst is
The fuel is introduced into the exhaust passage 10 on the upstream side of 28 and burned.
Control the upstream switching valve 22 and the downstream switching valve 24
Control, and the exhaust gas temperature T ₁ Degrades HC adsorbent
When the temperature exceeds the threshold value Tc, the exhaust is exhausted in the third branch.
In order to bypass the passage 94, the upstream switching valve 22 and
The switching control of the downstream switching valve 24 is performed. Thus, the exhaust gas purifying device 12 is
The first and second HC intakes provided in parallel when the cold start of the fuel engine 2 is started
HC can be adsorbed by one of the materials 32 and 34
And the HC released from the other side,
It can be burned in the exhaust passage 10 on the more upstream side,
Further, thermal deterioration of the HC adsorbent can be prevented. For this reason, the exhaust gas purification device 12
First and second HC adsorption provided in parallel at the time of cold start of the engine 2
H in exhaust before activation of the catalyst by one of the materials 32 and 34
C in adsorbed to reduce HC in exhaust gas
At the same time as the HC
The medium 28 can be activated at an early stage.
Release of HC adsorbed on the other of the second HC adsorbents 32 and 34
Unnecessary fuel consumption because decombustion does not require separate fuel
Can be avoided and the fuel consumption rate can be further improved.
And durability by preventing thermal degradation of the HC adsorbent
Can be up. FIGS. 13 to 19 show a fourth embodiment of the present invention.
It is shown. In this fourth embodiment, FIG.
The parts having the same functions as those of the first embodiment shown in FIG.
The description will be omitted, and the characteristic portions will be denoted by reference numerals.
I do. [0127] The exhaust gas purifying apparatus 12 of the fourth embodiment is shown in FIG.
As shown in FIG. 13, the third HC introduction passage of the HC introduction passage 36
The part 46 is provided with an HC pump 96 for supplying HC,
An HC feeding device 98 for operating and stopping the C pump is provided.
A C feeder 98 is provided connected to the control means 84. The HC pump 96 is located below the upstream catalyst body 28.
Exhaust gas temperature detected by an exhaust gas temperature sensor 60 provided on the upstream side
T ₁ Is a temperature at which HC can be adsorbed (for example,
It is activated when the threshold value Tb of the lower part is exceeded, and the catalyst is activated.
When the temperature exceeds a threshold value Ta, the operation is stopped. Also,
The upstream switching valve 22 and the downstream switching valve 24 are provided at the exhaust gas temperature.
T ₁ Exceeds a threshold value Tb of a temperature at which HC can be adsorbed.
And the exhaust circulation state of the first and second branch exhaust passages 14 and 16
・ Switch the exhaust stop state. Threshold Tb and threshold
The value Ta has a relationship of Tb <Ta. Control Means of Exhaust Purification System 12 of Third Embodiment
Reference numeral 84 denotes when the internal combustion engine 2 is cold-started, as shown in FIGS.
Control is performed as shown. In addition, the upstream switching valve 22 and the downstream
When the internal combustion engine 2 is stopped, the side switching valve 24 is connected to the first branch exhaust valve.
The passage 14 is set in an exhaust circulation state, and the second branch exhaust passage
Switching control is performed so that the path 16 is in the exhaust stop state.
Shall be. As shown in FIG. 14, the control means 84
Is started (step 400), various signals are read.
(Step 402), whether the internal combustion engine 2 has been started
It is determined whether or not it is (step 404). When this determination (step 404) is NO
Returns to reading of various signals (step 402)
I do. If this determination (step 404) is YES,
Switching control of HC introduction control valve 54 and turning on exhaust igniter 56
Of air pump 76 and heat source 78 and secondary air control valve
A process with the switching control of 82 is performed (step 406). In this process (step 406),
The control means 84 is, as shown in FIGS.
The first branch exhaust passage 14 into an exhaust circulation state at the start of
At the same time, the second branch exhaust passage 16 is set to the exhaust stop state.
Thus, the second HC introduction passage portion 44 is connected to the third HC introduction passage portion 46.
And shut off the first HC introduction passage portion 42
You. Further, the control means 84 controls the third secondary air supply.
The passage 72 is communicated with the second secondary air supply passage 70.
And the first secondary air supply passage 68 is shut off,
By operating the pump 76 and the heat source 78, the second HC adsorbent 34
The secondary heated in the second branch exhaust passage 16 on the more upstream side
Supply air. Note that the HC pump 96 is stopped
I have. The first branch exhaust passage in the exhaust passage state
The first HC adsorbent 32 in the passage 14 adsorbs HC in the exhaust gas.
You. The second branch exhaust passage 16 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and the exhaust igniter 5
6 is turned on, and the temperature of the upstream catalyst body 28 is increased.
Promotes activation. Following the above processing (step 406), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 408), and the temperature T ₁ Is H
It is determined whether the temperature exceeds the threshold value Tb at which C can be adsorbed.
It is turned off (step 410). When this determination (step 410) is NO
Is the exhaust gas temperature T ₁ Is detected (step 408).
On. When this judgment (step 410) is YES
Is the exhaust gas temperature T detected by the exhaust gas temperature sensor 60. ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 412). When this determination (step 412) is NO
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
The air pump 76 and the heat source 78 and the HC pump 96
(Step 414), and the temperature of the exhaust gas
T ₁ Is returned (step 408). In the above processing (step 414),
The control means 84 is, as shown in FIGS.
First branch by switching control of the valve 22 and the downstream switching valve 24
The exhaust passage 14 is brought into an exhaust stop state and the second branch exhaust is performed.
The air passage 16 is set in the exhaust gas circulation state, and the secondary air control valve 82 is
The first to third secondary air supply passages are controlled by switching control.
The communication between 68 and 72 is cut off, and the secondary air supply device 74
The air pump 76 and the heat source 78 are stopped to
The supply is stopped, and the HC pump 96 is
Activate As a result, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust circulation state
The second HC adsorbent 34 of No. 6 removes HC by the exhaust gas whose temperature has been increased.
Departed and moved up by HC pump 96 together with part of exhaust
The gas is returned to the exhaust passage 10 on the upstream side of the upstream catalyst body 28,
It is burned by the gas igniter 60 to promote activation. If the judgment (step 412) is YES
In this case, the switching control of the HC introduction control valve 54 and the exhaust igniter 56
OFF, stop of HC pump 96 and secondary air control valve 82
(Step 416), and the
(Step 418). In the above processing (step 416),
The control means 84 is, as shown in FIGS.
The switching control of the HC introduction control valve 54 is performed by the
The communication between the third HC introduction passages 42 to 46 is cut off, and the exhaust point
The firearm 56 is turned off, and the HC pump is
The stop 96 is stopped. The second branch exhaust passage 16 in the exhaust circulation state
2HC adsorbent 34 releases HC during operation of internal combustion engine 2
And the released HC is transferred to the downstream catalyst body 3
Purify with 0. In this state, the internal combustion engine 2 is stopped.
Is maintained until When the stopped internal combustion engine 2 is restarted,
The means 84 performs control as shown in FIGS. This
, The upstream switching valve 22 and the downstream switching valve 24
As described above, the first branch exhaust passage 14 is set in the exhaust stop state.
At the same time, the second branch exhaust passage 16 is brought into an exhaust circulation state.
The switching is controlled as follows. As shown in FIG. 14, the control means 84
Starts (step 400), as before,
Execute (Step 402) to (Step 406)
You. In this processing (step 406),
The control means 84 restarts the internal combustion engine 2 as shown in FIG.
Sometimes, the first branch exhaust passage 14 is set to the exhaust stop state.
The second branch exhaust passage 16 is in an exhaust circulation state.
The 1HC introduction passage portion 42 communicates with the third HC introduction passage portion 46
And the second HC introduction passage portion 44 is shut off. Further, the control means 84 controls the supply of the third secondary air.
The passage 72 communicates with the first secondary air supply passage 68.
And the second secondary air supply passage 70 is shut off,
The first HC adsorbent 32 by operating the pump 76 and the heat source 78.
Secondary heated in the first branch exhaust passage 14 on the more upstream side
Supply air. Note that the HC pump 96 is stopped
I have. The second branch exhaust passage in the exhaust circulation state
The first HC adsorbent 34 in the passage 16 adsorbs HC in the exhaust gas.
You. The first of the first branch exhaust passages 14 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Following the above processing (step 406),
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 408), and the temperature T ₁ Is H
It is determined whether the temperature exceeds the threshold value Tb at which C can be adsorbed.
It is turned off (step 410). When this determination (step 410) is NO
Is the exhaust gas temperature T ₁ Is detected (step 408).
On. When this judgment (step 410) is YES
Is the exhaust gas temperature T ₁ Threshold temperature at which the catalyst activates
It is determined whether Ta has been exceeded (step 412). When this determination (step 412) is NO
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
The air pump 76 and the heat source 78 and the HC pump 96
(Step 414), and the temperature of the exhaust gas
T ₁ Is returned (step 408). In the above processing (step 414),
The control means 84 includes, as shown in FIG.
4 and the second branch exhaust passage 16
In the exhaust stop state, and the first to third secondary air supply passages 6
8 to 72, and the air pump 76 and the heat source 78
Is stopped to stop the supply of the secondary air, and the HC pump 96 is stopped.
Activate As a result, the second minute in the exhaust stop state is set.
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
The first HC adsorbent 32 of No. 4 removes HC by the exhaust gas whose temperature has been raised.
Departed and moved up by HC pump 96 together with part of exhaust
The gas is returned to the exhaust passage 10 on the upstream side of the upstream catalyst body 28,
It is burned by the gas igniter 60 to promote activation. If the judgment (step 412) is YES
In this case, the switching control of the HC introduction control valve 54 and the exhaust igniter 56
OFF, stop of HC pump 96 and secondary air control valve 82
(Step 416), and the
(Step 418). In the above process (step 416),
The control means 84 controls the HC introduction control valve 5 by the HC control unit 52.
4 to control the first to third HC introduction passages 42 to 4.
6, the exhaust igniter 56 is turned off, and the HC supply is stopped.
The HC pump 96 is stopped by the supply device 98. Exhaust flow
Second HC adsorbent 34 in the second branch exhaust passage 16
Is in a detached state in which HC is released during operation of the internal combustion engine 2.
And the released HC is purified by the downstream catalyst 30.
You. As described above, the exhaust gas purifying apparatus of the fourth embodiment is described.
The device 12 is controlled by the control means 84 when the internal combustion engine 2 is started.
The first and second branch exhaust passages 14 and 16 alternately flow
Switch to the exhausted state and the exhausted state.
For example, the first HC adsorbent 32 of the first branch exhaust passage 14
HC is adsorbed and exhaust is stopped.
Adsorbed by the second HC adsorbent 34 in the two-branch exhaust passage 16
The HC is discharged, and the upstream side catalyst is
The fuel is introduced into the exhaust passage 10 on the upstream side of 28 and burned.
Control the upstream switching valve 22 and the downstream switching valve 24
Control, and the exhaust gas temperature T ₁ Of the temperature at which HC can be adsorbed
Threshold of temperature exceeding threshold value Tb and activating catalyst
When the value is equal to or less than the value Ta, the first and second branch exhaust passages 14.1
And the state of exhaust circulation to the 6
Stop supplying secondary air and send HC along with part of exhaust
To supply the water, the upstream switching valve 22 and the downstream switching valve 24 are turned off.
Control to control the secondary air supply device and the HC
The operation of the amplifier 96 is controlled. That is, the control means 84 determines that the exhaust is stopped.
Which of the first and second branch exhaust passages 14 and 16
Either the first HC adsorbent 32 or the second HC adsorbent 3
4 to remove HC from the upstream side of the upstream catalyst body 28.
When the gas is introduced into the air passage 10, the exhaust gas temperature T ₁ Scribble
If the temperature exceeds the threshold Tb, the HC pump 98
Switch 96 is operated, and the upstream side is switched by the switching valve control unit 26.
The switching control of the valve 22 and the downstream switching valve 24 is performed, and the first and second switching valves are controlled.
Exhaust flow to branch exhaust passages 14/16, exhaust stop
Switch state. Thus, the control means 84 sets the exhaust stop state.
And second branch exhaust switched from the state to the exhaust circulation state
The first HC adsorbent 32 of one of the passages 14 and 16
Alternatively, exhaust gas is circulated through the second HC adsorbent 34 to separate HC.
And discharged to the exhaust passage 10 on the upstream side of the upstream catalyst body 28.
Reflux with some of the air. The control means 84 controls the temperature T of the exhaust gas. ₁ Threshold
When the value Ta exceeds the value Ta, the HC pump 98
96, and the exhaust passage on the upstream side of the upstream catalyst body 28
The introduction of HC and partial exhaust to the fuel cell 10 is stopped. As a result, the exhaust gas purifying device 12
The first and second HC intakes provided in parallel when the cold start of the fuel engine 2 is started
HC can be adsorbed by one of the materials 32 and 34
And the HC released from the other side,
It can be burned in the exhaust passage 10 on the more upstream side,
In addition, the temperature at which HC can be adsorbed together with the released HC
If it is possible to release HC from the exhaust when it exceeds
In addition, the exhaust gas is partially combined with the HC,
Can also be supplied to the exhaust passage 10 on the upstream side. For this reason, the exhaust gas purifying apparatus 12 uses the internal combustion engine.
First and second HC adsorption provided in parallel at the time of cold start of the engine 2
H in exhaust before activation of the catalyst by one of the materials 32 and 34
C in adsorbed to reduce HC in exhaust gas
At the same time as the HC
The medium 28 can be activated at an early stage.
Release of HC adsorbed on the other of the second HC adsorbents 32 and 34
Unnecessary fuel consumption because decombustion does not require separate fuel
Can be avoided and the fuel consumption rate can be further improved.
And the exhaust gas temperature exceeds the temperature at which HC can be adsorbed.
When the exhaust gas is used to release HC, the secondary air
The operation of the supply device 74 can be reduced, and the function of the HC adsorbent is improved.
It can be used effectively and durability can be improved. FIGS. 20 to 23 show a fifth embodiment of the present invention.
It is shown. In this fifth embodiment, FIG.
The parts having the same functions as those of the first embodiment shown in FIG.
The description will be omitted, and the characteristic portions will be denoted by reference numerals.
I do. The exhaust gas purifying apparatus 12 of the fifth embodiment is similar to that of FIG.
As shown in FIG. 20, the first and second branches are formed in the middle of the exhaust passage 10.
In addition to branching into the exhaust passages 14 and 16,
The third branch exhaust passage 94 is branched and provided. First
The first and second H are respectively provided in the second branch exhaust passages 14 and 16.
C adsorbents 32 and 34 are provided. Third exhaust / exhaust passage 9
No. 4 is provided with no HC adsorbent and the exhaust gas is bypassed. The upstream branch section 18 and the downstream branch section 20
The upstream switching valve 22 and the downstream switching valve 24 provided respectively are
Exhaust temperature T ₁ To switch the exhaust flow direction. Upstream
The switching valve 22 and the downstream switching valve 24 are connected to an upstream catalyst body 28.
Of the exhaust gas detected by the exhaust gas temperature sensor 60 provided on the downstream side of
Temperature T ₁ Is the temperature threshold at which the HC catalyst is thermally degraded
If the temperature exceeds Tc (for example, 500 ° C.), the exhaust is exhausted to the third exhaust
Switching control is performed so as to bypass the exhaust passage 94.
You. Further, the exhaust gas purifying apparatus 12 of the fifth embodiment
As shown in FIG. 20, the third HC passage in the HC introduction passage 36 is
An HC pump 96 for supplying HC to the inlet passage 46;
An HC feeder 98 for operating and stopping the HC pump is provided.
And an HC feeder 98 connected to the control means 84 and provided.
I have. The HC pump 96 is located below the upstream catalyst body 28.
Exhaust gas temperature detected by an exhaust gas temperature sensor 60 provided on the upstream side
T ₁ Is a temperature at which HC can be adsorbed (for example,
It is activated when the threshold value Tb of the lower part is exceeded, and the catalyst is activated.
When the temperature exceeds a threshold value Ta, the operation is stopped. Also,
The upstream switching valve 22 and the downstream switching valve 24 are provided at the exhaust gas temperature.
T ₁ Exceeds a threshold value Tb of a temperature at which HC can be adsorbed.
And the state of exhaust gas flow to the first and second branch exhaust passages 14 and 16
Switch between the state and the exhaust stop state. Threshold Ta and threshold
The relationship between the threshold value Tb and the threshold value Tc is Tb <Ta <Tc.
It has become. Control means of the exhaust gas purifying apparatus 12 of the fifth embodiment
Reference numeral 84 denotes when the internal combustion engine 2 is cold started, as shown in FIGS.
Control is performed as shown. In addition, the upstream switching valve 22 and the downstream
When the internal combustion engine 2 is stopped, the side switching valve 24
The branch exhaust passages 14 and 16 are set to the exhaust stop state, and the
Switching control so that the three-branch exhaust passage 94 is in an exhaust circulation state.
Shall be controlled. As shown in FIG. 21, the control means 84
Starts (step 500), and reads various signals.
(Step 502), whether the internal combustion engine 2 has been started
It is determined whether or not it is (step 504). When this determination (step 504) is NO
Returns to reading of various signals (step 502)
I do. If this determination (step 504) is YES,
Switching control of upstream switching valve 22 and downstream switching valve 24 and H
Switching control of the C introduction control valve 54 and turning on of the exhaust igniter 56
Operation of air pump 76 and heat source 78 and secondary air control valve 8
The processing with the switching control of No. 2 is performed (step 506). In this processing (step 506),
As shown in FIG. 22, the control means 84 includes the upstream switching valve 22 and the
And the downstream side switching valve 24 to control the
The first branch exhaust passage 14 is set in an exhaust flow state and the
Stops exhausting the two-branch exhaust passage 16 and the third-branch exhaust passage 94
And the second HC introduction passage portion 44 is connected to the third HC introduction passage.
And the first HC introduction passage portion 42
Cut off. Further, the control means 84 controls the third secondary air supply.
The passage 72 is communicated with the second secondary air supply passage 70.
And the first secondary air supply passage 68 is shut off,
By operating the pump 76 and the heat source 78, the second HC adsorbent 34
The secondary heated in the second branch exhaust passage 16 on the more upstream side
Supply air. The first branch exhaust passage in the exhaust circulation state
The first HC adsorbent 32 in the passage 14 adsorbs HC in the exhaust gas.
You. The second branch exhaust passage 16 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and the exhaust igniter 5
6 is turned on, and the temperature of the upstream catalyst body 28 is increased.
Promotes activation. Following the above processing (step 506),
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 508), and the temperature T ₁ Is H
It is determined whether the temperature exceeds the threshold value Tb at which C can be adsorbed.
(Step 510). When this determination (step 510) is NO
Is the exhaust gas temperature T ₁ Is detected (step 408).
On. When this judgment (step 510) is YES
Is the exhaust gas temperature T detected by the exhaust gas temperature sensor 60. ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 512). When this determination (step 512) is NO
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
Of air pump 76 and heat source 78 and secondary air control valve
82 and control the operation of the HC pump 96.
(Step 514), temperature T of exhaust gas ₁ Detection (step
Return to step 508). In the above processing (step 514),
As shown in FIG. 22, the control means 84 includes the upstream switching valve 22 and the
The first branch exhaust passage is controlled by the switching control of the
14. When the third branch exhaust passage 94 is set to the exhaust stop state
In particular, the second branch exhaust passage 16 is set in an exhaust circulation state. The control means 84 controls the secondary air control valve 8
2 to control the first to third secondary air supply.
The communication between the road portions 68 to 72 is cut off, and the secondary air supply device 74 is closed.
To stop the air pump 76 and the heat source 78,
The supply of air is stopped, and the HC pump is
Activate 96. As a result, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust circulation state
The second HC adsorbent 34 of No. 6 emits HC
And a part of the exhaust gas and the HC pump 96
Recirculated to the exhaust passage 10 on the upstream side of the upstream catalyst body 28,
It is burned by the exhaust igniter 60 to promote activation. When the judgment (step 512) is YES,
In this case, the switching control of the HC introduction control valve 54 and the exhaust igniter 56
OFF and stop HC pump 96 (step
516). In the above processing (step 516),
The control means 84 is controlled by the HC control section 52 as shown in FIG.
To control the HC introduction control valve 54 to switch the first to third HCs.
The communication between the introduction passages 42 to 46 is cut off, and the HC supply device 9 is closed.
8, the HC pump 96 is stopped, and the exhaust igniter 56 is turned off.
FF. As a result, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust circulation state
The second HC adsorbent 34 of the sixth HC
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. Following the above processing (step 516), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 518), and the temperature T ₁ Is H
Whether or not the threshold value Tc of the temperature at which the C adsorbent thermally deteriorates is exceeded
Is determined (step 520). When this determination (step 520) is NO
Is the exhaust gas temperature T ₁ Is detected (step 518).
On. When this judgment (step 520) is YES
Controls switching of the upstream switching valve 22 and the downstream switching valve 24
And the first and second branch exhaust passages 14 and 16 are in an exhaust stopped state.
And the third branch exhaust passage 94 is set in an exhaust circulation state.
(Step 522), and returns (step 52).
4). Accordingly, the temperature at which the HC adsorbent is thermally degraded
Exceeding the threshold Tc of the third branch exhaust passage 94
To prevent thermal deterioration of the HC adsorbent
Can be This state is maintained until the internal combustion engine 2 is stopped.
Will be maintained. When the stopped internal combustion engine 2 is restarted,
The means 84 performs control as shown in FIGS. This
, The upstream switching valve 22 and the downstream switching valve 24
As described above, the first and second branch exhaust passages 14 and 16 are exhaust stopped.
To the stop state and exhaust gas flows through the third branch exhaust passage 94.
The switching is controlled to be in the state. As shown in FIG. 21, the control means 84
Starts (step 500), as before,
(Step 502) to (Step 506) are executed. In this processing (step 506),
The control means 84 includes, as shown in FIG.
And the downstream side switching valve 24 is controlled to switch to the second
The branch exhaust passage 16 is set to the exhaust circulation state and the first branch is performed.
The exhaust passage 14 and the third branch exhaust passage 94 are set in an exhaust stopped state.
Then, the first HC introduction passage portion 42 is connected to the third HC introduction passage portion 46.
And shut off the second HC introduction passage portion 44
You. Further, the control means 84 controls the third secondary air supply.
The passage 72 communicates with the first secondary air supply passage 68.
And the second secondary air supply passage 70 is shut off,
The first HC adsorbent 32 by operating the pump 76 and the heat source 78.
Secondary heated in the first branch exhaust passage 14 on the more upstream side
Supply air. The second branch exhaust passage in the exhaust passage state
The second HC adsorbent 34 in the passage 16 adsorbs HC in the exhaust gas.
You. The first of the first branch exhaust passages 14 in the exhaust stopped state
The HC adsorbent 32 is heated by the supplied secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Following the above processing (step 506), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 508), and the temperature T ₁ Is H
It is determined whether the temperature exceeds the threshold value Tb at which C can be adsorbed.
(Step 510). When this determination (step 510) is NO
Is the exhaust gas temperature T ₁ Is detected (step 408).
On. When this judgment (step 510) is YES
Is the exhaust gas temperature T detected by the exhaust gas temperature sensor 60. ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 512). When this determination (step 512) is NO
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
Of air pump 76 and heat source 78 and secondary air control valve
82 and control the operation of the HC pump 96.
(Step 514), temperature T of exhaust gas ₁ Detection (step
Return to step 508). In the above processing (step 514),
The control means 84 includes, as shown in FIG.
The second branch exhaust passage is controlled by the switching control of the
16. When the third branch exhaust passage 94 is set to the exhaust stop state
In particular, the first branch exhaust passage 14 is set in an exhaust circulation state,
By switching control of the air control valve 82, the first to third secondary
The communication between the air supply passages 68 to 72 is cut off, and the secondary air supply is stopped.
The air pump 76 and the heat source 78 are stopped by the supply device 74.
To stop the supply of secondary air,
The HC pump 96 is operated. As a result, the second minute in the exhaust stopped state
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
The first HC adsorbent 32 of No. 4 emits HC
And a part of the exhaust gas and the HC pump 96
Recirculated to the exhaust passage 10 on the upstream side of the upstream catalyst body 28,
It is burned by the exhaust igniter 60 to promote activation. When the judgment (step 512) is YES,
In this case, the switching control of the HC introduction control valve 54 and the exhaust igniter 56
OFF and stop HC pump 96 (step
516). In the above processing (step 516),
The control means 84 is controlled by the HC control unit 52 as shown in FIG.
To control the HC introduction control valve 54 to switch the first to third HCs.
The communication between the introduction passages 42 to 46 is cut off, and the HC supply device 9 is closed.
8, the HC pump 96 is stopped, and the exhaust igniter 56 is turned off.
FF. As a result, the second minute in the exhaust stopped state
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
4 during the operation of the internal combustion engine 2.
Is released. The released HC is downstream
The catalyst is introduced into the catalyst body 30 and purified. Following the above processing (step 516), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 518), and the temperature T ₁ Is H
Whether or not the threshold value Tc of the temperature at which the C adsorbent thermally deteriorates is exceeded
Is determined (step 520). When this determination (step 520) is NO
Is the exhaust gas temperature T ₁ Is detected (step 518).
On. If this determination (step 520) is YES,
Switching control of the upstream switching valve 22 and the downstream switching valve 24
The first and second branch exhaust passages 14 and 16 are set to the exhaust stop state.
And the third branch exhaust passage 94 is set in an exhaust circulation state.
(Step 522), return (Step 52)
4). Thus, the temperature at which the HC adsorbent thermally degrades
Exceeding the threshold Tc of the third branch exhaust passage 94
To prevent thermal deterioration of the HC adsorbent
Can be As described above, the exhaust gas purifying apparatus of the fifth embodiment is described.
The device 12 is controlled by the control means 84 when the internal combustion engine 2 is started.
The first and second branch exhaust passages 14 and 16 alternately flow
Switch to the exhausted state and the exhausted state.
For example, the first HC adsorbent 32 of the first branch exhaust passage 14
HC is adsorbed and exhaust is stopped.
Adsorbed by the second HC adsorbent 34 in the two-branch exhaust passage 16
The HC is discharged, and the upstream side catalyst is
The fuel is introduced into the exhaust passage 10 on the upstream side of 28 and burned.
Control the upstream switching valve 22 and the downstream switching valve 24
Control, and the exhaust gas temperature T ₁ Degrades HC adsorbent
When the temperature exceeds the threshold value Tc, the exhaust is exhausted in the third branch.
In order to bypass the passage 94, the upstream switching valve 22 and
The switching control of the downstream switching valve 24 is performed.
₁ Exceeds the temperature threshold value Tb at which HC can be adsorbed and
When the temperature is equal to or lower than the threshold temperature Ta for activating the medium, the first
-Exhaust flow to second branch exhaust passages 14 and 16-Exhaust
Switching the stop state and stopping the supply of secondary air
Upstream switching valve 22 and downstream switching valve 22 to supply HC
24 to control the secondary air supply device 74
Both control the operation of the HC pump 96. Thus, the exhaust gas purifying device 12 is
The first and second HC intakes provided in parallel when the cold start of the fuel engine 2 is started
HC can be adsorbed by one of the materials 32 and 34
And the HC released from the other side,
It can be burned in the exhaust passage 10 on the more upstream side,
In addition, the temperature at which HC can be adsorbed together with the released HC
If it exceeds, part of the exhaust gas is upstream of the upstream catalyst body 28.
To the exhaust passage 10 of the fuel cell.
Thermal deterioration of the material can be prevented. For this reason, the exhaust purification device 12
First and second HC adsorption provided in parallel at the time of cold start of the engine 2
H in exhaust before activation of the catalyst by one of the materials 32 and 34
C in adsorbed to reduce HC in exhaust gas
At the same time as the HC
The medium 28 can be activated at an early stage.
Release of HC adsorbed on the other of the second HC adsorbents 32 and 34
Unnecessary fuel consumption because decombustion does not require separate fuel
Can improve fuel efficiency.
The temperature at which HC can be adsorbed along with the combustion of the separated HC
When the temperature exceeds the degree, secondary air is returned by recirculating some exhaust
Adsorbs HC of HC adsorbent without requiring operation of supply device 74
・ Can be separated, which is advantageous for improving the combustion consumption rate
Durability by preventing thermal deterioration of HC adsorbent
Can be improved. FIGS. 24 to 29 show a sixth embodiment of the present invention.
It is shown. The exhaust gas purifying apparatus 12 of the sixth embodiment
Has the same configuration as that of the third embodiment shown in FIG.
Therefore, description will be made using the reference numerals in FIG. The exhaust gas purifying apparatus 12 of the sixth embodiment is
As shown in FIG. 9, the middle of the exhaust passage 10 is
In addition to branching into the air passages 14 and 16,
The third branch exhaust passage 94 is branched and provided. 1st and 1st
The two-branch exhaust passages 14 and 16 have first and second HC intakes, respectively.
The dressing materials 32 and 34 are provided. In the third exhaust passage 94
Does not provide an HC adsorbent and bypasses exhaust gas. In the upstream branch section 18 and the downstream branch section 20,
The upstream switching valve 22 and the downstream switching valve 24 provided respectively are
Exhaust temperature T ₁ To switch the exhaust flow direction. Upstream
The switching valve 22 and the downstream switching valve 24 are connected to an upstream catalyst body 28.
Of the exhaust gas detected by the exhaust gas temperature sensor 60 provided on the downstream side of
Temperature T ₁ Is the threshold value Tb of the temperature at which HC can be adsorbed (eg,
If the temperature exceeds 200 ° C., for example, the third exhaust
Switching control is performed to bypass the passage 94. Control Means of Exhaust Purification System 12 of Sixth Embodiment
Reference numeral 84 denotes a state when the internal combustion engine 2 is cold started, as shown in FIGS.
Control is performed as shown. In addition, the upstream switching valve 22 and the downstream
When the internal combustion engine 2 is stopped, the side switching valve 24
The branch exhaust passages 14 and 16 are set to the exhaust stop state, and the
Switching control so that the three-branch exhaust passage 94 is in an exhaust circulation state.
Shall be controlled. As shown in FIG. 24, the control means 84
Is started (step 600), various signals are read.
(Step 602), whether the internal combustion engine 2 has been started
It is determined whether or not it is (step 604). When this determination (step 604) is NO
Returns to reading of various signals (step 602)
I do. If this determination (step 604) is YES,
Switching control of upstream switching valve 22 and downstream switching valve 24 and H
Switching control of the C introduction control valve 54 and turning on of the exhaust igniter 56
Operation of air pump 76 and heat source 78 and secondary air control valve 8
The processing with the switching control of No. 2 is performed (step 606). In this processing (step 606),
The control means 84 is, as shown in FIGS.
Valve 22 and downstream switching valve 24 are switched and controlled to
For example, if the first branch exhaust passage 14 is set to an exhaust flow state,
Both the second branch exhaust passage 16 and the third branch exhaust passage 94
The exhaust is stopped, and the second HC introduction passage 44 is moved to the third HC
A first HC introduction passage which communicates with the introduction passage portion 46;
The part 42 is shut off. [0211] The control means 84 supplies the third secondary air.
The passage 72 is communicated with the second secondary air supply passage 70.
And the first secondary air supply passage 68 is shut off,
By operating the pump 76 and the heat source 78, the second HC adsorbent 34
The secondary heated in the second branch exhaust passage 16 on the more upstream side
Supply air. The first branch exhaust passage in the exhaust circulation state
The first HC adsorbent 32 in the passage 14 adsorbs HC in the exhaust gas.
You. The second branch exhaust passage 16 in the exhaust stopped state
The HC adsorbent 34 is heated by the supplied heated secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and the exhaust igniter 5
6 is turned on, and the temperature of the upstream catalyst body 28 is increased.
Promotes activation. Following the above processing (step 606), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 608), and the temperature T ₁ Is H
It is determined whether the temperature exceeds the threshold value Tb at which C can be adsorbed.
(Step 610). When this determination (step 610) is NO
Is the exhaust gas temperature T ₁ Is detected (step 608).
On. When this judgment (step 610) is YES
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
(Step 612). In the above processing (step 612),
As shown in FIG. 25 and FIG.
First branch by switching control of the valve 22 and the downstream switching valve 24
The exhaust passage 14 and the second branch exhaust passage 16 are in an exhaust stopped state.
And the third branch exhaust passage 94 is set in an exhaust circulation state.
You. As a result, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust stopped state
No. 6 second HC adsorbent 34 is supplied to the heated secondary
Releases HC by air. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Ma
Further, the third branch exhaust passage 94 bypasses the exhaust.
As a result, the temperature exceeds the threshold value Tb at which HC can be adsorbed.
Exhaust gas is circulated through the third branch exhaust passage 94 to remove HC.
The function of the dressing can be used effectively. Following the above processing (step 612), the exhaust
The temperature of the exhaust gas from the upstream catalyst body 28 is detected by the temperature sensor 60.
Degree T ₁ Is detected (step 614), and the temperature T ₁ Touch
It is determined whether or not the threshold temperature Ta for activating the medium has been exceeded.
(Step 616). When this determination (step 616) is NO
Is the exhaust gas temperature T ₁ Is detected (step 614).
On. If this determination (step 616) is YES,
Switching control of HC introduction control valve 54 and OF of exhaust igniter 56
F, stop of air pump 76 and heat source 78 and secondary air control
Processing for switching control of the valve 82 is performed (step 618),
Return (step 620). In the above processing (step 618),
The control means 84 is, as shown in FIGS. 25 and 29, an HC control unit.
The switching control of the HC introduction control valve 54 is performed by the
The communication between the third HC introduction passage portions 42 to 46 is cut off, and the secondary
By switching control of the air control valve 82, the first to third secondary
The communication between the air supply passages 68 to 72 is cut off, and the secondary air supply is stopped.
The air pump 76 and the heat source 78 are stopped by the supply device 74.
To stop the supply of secondary air and turn off the exhaust igniter 56
I do. As a result, the first minute in the exhaust stop state is set.
The first HC adsorbent 32 in the branch exhaust passage 14 is
Hold. Second branch exhaust passage 1 in an exhaust stopped state
The second HC adsorbent 34 is prevented from being detached. 3rd minute
The branch exhaust passage 94 allows exhaust to be bypassed. Exhaust on
Purification is performed by the upstream catalyst body 28 and the downstream catalyst body 30. This state is maintained until the internal combustion engine 2 is stopped.
Will be maintained. When the stopped internal combustion engine 2 is restarted,
The means 84 performs control as shown in FIGS.
At this time, the upstream switching valve 22 and the downstream switching valve 24
As described above, the first and second branch exhaust passages 14 and 16 are exhausted.
In the stop state, the exhaust gas flows through the third branch exhaust passage 94.
The switching is controlled so that the communication state is established. As shown in FIG. 24, the control means 84
Starts (step 600), as described above,
Execute (Step 602) to (Step 606)
You. In this processing (step 606), control
The control means 84 includes, as shown in FIG.
And the downstream side switching valve 24 is controlled to switch to the second
The branch exhaust passage 16 is set to the exhaust circulation state and the first branch is performed.
The exhaust passage 14 and the third branch exhaust passage 94 are set in an exhaust stopped state.
Then, the first HC introduction passage portion 42 is connected to the third HC introduction passage portion 46.
And shut off the second HC introduction passage portion 44
You. The control means 84 controls the third secondary air supply.
The passage 72 communicates with the first secondary air supply passage 68.
And the second secondary air supply passage 70 is shut off,
The first HC adsorbent 32 by operating the pump 76 and the heat source 78.
Secondary heated in the first branch exhaust passage 14 on the more upstream side
Supply air. The second branch exhaust passage in the exhaust circulation state
The second HC adsorbent 34 in the passage 16 adsorbs HC in the exhaust gas.
You. The first of the first branch exhaust passages 14 in the exhaust stopped state
The HC adsorbent 32 is heated by the supplied secondary air.
Release and release HC. This HC is an HC introduction passage.
36, the exhaust passage 1 upstream of the upstream catalyst body 28
0, and is burned by turning on the exhaust igniter 56,
The temperature of the upstream catalyst body 28 is raised to promote activation. Following the above processing (step 606),
The temperature T of the exhaust gas is detected by the air temperature sensor 60. ₁ Is detected (step
608), the temperature T ₁ Of the temperature at which HC can be adsorbed
It is determined whether or not the threshold value Tb has been exceeded (step 61).
0). When this determination (step 610) is NO
Is the exhaust gas temperature T ₁ Is detected (step 608).
On. When this judgment (step 610) is YES
Is the switching control of the upstream switching valve 22 and the downstream switching valve 24
(Step 612). In the above processing (step 612),
The control means 84 includes, as shown in FIG.
The first branch exhaust passage is controlled by the switching control of the
14. When the second branch exhaust passage 16 is set to the exhaust stop state
In particular, the third branch exhaust passage 94 is set in an exhaust circulation state. [0230] Thereby, the second minute in the exhaust stop state is set.
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust circulation state
No. 4 first HC adsorbent 32 is supplied to the heated secondary
The air releases HC and releases it. This HC is HC
The exhaust passage 36 upstream of the upstream catalyst body 28
It is introduced into the air passage 10 and is turned on by the exhaust igniter 56.
It is burned, and the upstream catalyst body 28 is heated to promote activation.
You. Further, the third branch exhaust passage 94 exhausts exhaust gas.
Let me pass. As a result, the temperature at which HC can be adsorbed is reduced.
Exhaust exceeding the threshold value Tb flows through the third branch exhaust passage 94.
And effectively use the function of HC adsorbent
You. Following the above processing (step 612),
Exhaust temperature T by the air temperature sensor 60 ₁ Detection (step
614) and the temperature T ₁ Has exceeded the threshold value Ta
The determination (step 616) is performed. If this determination (step 616) is NO
Is the exhaust gas temperature T ₁ Is detected (step 614).
On. If this determination (step 616) is YES,
Switching control of HC introduction control valve 54 and OF of exhaust igniter 56
F, stop of air pump 76 and heat source 78 and secondary air control
Processing for switching control of the valve 82 is performed (step 618),
Return (step 620). In the above processing (step 618),
The control means 84 controls the HC introduction control valve 5 by the HC control unit 52.
4 to control the first to third HC introduction passages 42 to 4.
6 and the switching of the secondary air control valve 82 is controlled.
As a result, the first to third secondary air supply passages 68 to 72
The communication is cut off, and an air pump is
Stops supply of secondary air by stopping 76 and heat source 78
Then, the exhaust igniter 56 is turned off. As a result, the second minute in the exhaust stop state is set.
The second HC adsorbent 34 in the branch exhaust passage 16 is
Hold. First branch exhaust passage 1 in an exhaust stopped state
The first HC adsorbent 32 is prevented from being detached. 3rd minute
The branch exhaust passage 94 allows exhaust to be bypassed. Exhaust on
Purification is performed by the upstream catalyst body 28 and the downstream catalyst body 30. As described above, the exhaust gas purifying apparatus of the sixth embodiment is described.
The device 12 is controlled by the control means 84 when the internal combustion engine 2 is started.
The first and second branch exhaust passages 14 and 16 alternately flow
Switch to the exhausted state and the exhausted state.
For example, the first HC adsorbent 32 of the first branch exhaust passage 14
HC is adsorbed and exhaust is stopped.
Adsorbed by the second HC adsorbent 34 in the two-branch exhaust passage 16
The HC is discharged, and the upstream side catalyst is
The fuel is introduced into the exhaust passage 10 on the upstream side of 28 and burned.
Control the upstream switching valve 22 and the downstream switching valve 24
Control, and the exhaust gas temperature T ₁ Of the temperature at which HC can be adsorbed
If the threshold value Tb is exceeded, the exhaust gas is discharged to the third branch exhaust passage 9.
4 so that the upstream side switching valve 22 and the downstream side
The switching of the switching valve 24 is controlled. Thus, the exhaust gas purifying apparatus 12 is
The first and second HC intakes provided in parallel when the cold start of the fuel engine 2 is started
HC can be adsorbed by one of the materials 32 and 34
And the HC released from the other side,
It can be burned in the exhaust passage 10 on the more upstream side,
In addition, it is necessary to properly adsorb and desorb HC to the HC adsorbent.
Can be. For this reason, the exhaust purification system 12 is
First and second HC adsorption provided in parallel at the time of cold start of the engine 2
H in exhaust before activation of the catalyst by one of the materials 32 and 34
C in adsorbed to reduce HC in exhaust gas
At the same time as the HC
The medium 28 can be activated at an early stage.
Release of HC adsorbed on the other of the second HC adsorbents 32 and 34
Unnecessary fuel consumption because decombustion does not require separate fuel
Can improve fuel efficiency.
In addition, the function of the HC adsorbent can be used effectively to improve durability.
Can be up. As described above, according to the present invention, the exhaust gas purification is performed.
The engine alternates between the branch exhaust passages each time the internal combustion engine is started.
To the branch exhaust passage that is in the exhaust circulation state.
HC is adsorbed to the material and exhaust is stopped.
The HC of the HC adsorbent in the branch exhaust passage is released to make the upstream catalyst
Into the exhaust passage upstream of the body for combustion
The HC adsorbent provided in parallel at the time of cold start of the internal combustion engine
HC can be adsorbed by one of the
The HC released from the other side is upstream of the upstream catalyst body.
It can be burned in the exhaust passage. For this reason, this exhaust gas purifying apparatus is an internal combustion engine.
When one of the HC adsorbents provided in parallel is
HC in the exhaust gas before adsorption of the medium
Can be reduced and separated from the other HC adsorbent.
Activation of the upstream catalyst body by early combustion of HC
And the desorption combustion of HC adsorbed on the HC adsorbent.
Avoid unnecessary fuel consumption and improve fuel consumption rate
be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system configuration diagram of an exhaust emission control device according to a first embodiment of the present invention. FIG. 2 is a flowchart of control of the exhaust gas purification device. FIG. 3 is a timing chart when the internal combustion engine is started. FIG. 4 is a timing chart when the internal combustion engine is restarted. FIG. 5 is a system configuration diagram of an exhaust emission control device according to a second embodiment of the present invention. FIG. 6 is a flowchart of control of the exhaust gas purification device. FIG. 7 is a timing chart when the internal combustion engine is started. FIG. 8 is a timing chart when the internal combustion engine is restarted. FIG. 9 is a system configuration diagram of an exhaust emission control device according to a third embodiment of the present invention. FIG. 10 is a flowchart of control of the exhaust gas purification device. FIG. 11 is a timing chart at the time of starting the internal combustion engine. FIG. 12 is a timing chart when the internal combustion engine is restarted. FIG. 13 is a system configuration diagram of an exhaust emission control device according to a fourth embodiment of the present invention. FIG. 14 is a flowchart of control of the exhaust gas purification device. FIG. 15 is a timing chart at the time of starting the internal combustion engine. FIG. 16 is a timing chart when the internal combustion engine is restarted. FIG. 17 is a diagram showing flows of exhaust gas and HC below a temperature threshold value Tb at which HC can be adsorbed. FIG. 18 is a diagram showing flows of exhaust gas and HC which are higher than a HC adsorbable temperature threshold Tb and lower than a catalyst activation temperature threshold Ta. FIG. 19 is a diagram showing flows of exhaust gas and HC exceeding a catalyst activation temperature threshold value Ta. FIG. 20 is a system configuration diagram of an exhaust emission control device according to a fifth embodiment of the present invention. FIG. 21 is a flowchart of control of the exhaust gas purification device. FIG. 22 is a timing chart at the time of starting the internal combustion engine. FIG. 23 is a timing chart when the internal combustion engine is restarted. FIG. 24 is a flowchart of control of the exhaust emission control device according to the sixth embodiment of the present invention. FIG. 25 is a timing chart when the internal combustion engine is started. FIG. 26 is a timing chart when the internal combustion engine is restarted. FIG. 27 is a diagram showing flows of exhaust gas and HC below a temperature threshold value Tb at which HC can be adsorbed. FIG. 28 is a diagram showing flows of exhaust gas and HC which are higher than the HC adsorbable temperature threshold Tb and lower than the catalyst activation temperature threshold Ta. FIG. 29 is a diagram showing flows of exhaust gas and HC exceeding a catalyst activation temperature threshold value Ta. FIG. 30 is a schematic configuration diagram of an exhaust gas purifying apparatus showing a conventional example. FIG. 31 is a schematic configuration diagram of an exhaust gas purification apparatus showing another conventional example. FIG. 32 is a schematic configuration diagram of an exhaust gas purification apparatus showing still another conventional example. [Description of Signs] 2 Internal combustion engine 4 Intake passage 6 Intake manifold 8 Exhaust manifold 10 Exhaust passage 12 Exhaust purification device 14 First branch exhaust passage 16 Second branch exhaust passage 18 Upstream branch 20 Downstream branch 22 Upstream switching Valve 24 Downstream switching valve 26 Switching valve control unit 28 Upstream catalyst body 30 Downstream catalyst body 32 First HC adsorbent 34 Second HC adsorbent 36 HC introduction passage 52 HC control unit 54 HC introduction control valve 56 Exhaust igniter 58 Exhaust Ignition controller 60 Exhaust temperature sensor 62 Secondary air supply passage 74 Secondary air supply device 76 Air pump 78 Heat source 82 Secondary air control valve 84 Control means 86 Other sensors 88 HC sensor 90 HC supply device 94 Third branch exhaust Passage 96 HC pump 98 HC feeder

Claims (1)

(57) Claims 1. An exhaust passage of an internal combustion engine is divided into at least two branch exhaust passages, and an upstream branch portion and a downstream branch portion of each of the branch exhaust passages are provided. An upstream switching valve and a downstream switching valve for switching an exhaust flow direction, an upstream catalyst body is provided in an exhaust passage upstream of the upstream branch section, and exhaust gas downstream of the downstream branch section is provided. A downstream catalyst body is provided in the passage, an HC adsorbent is provided in each of the branch exhaust passages, and one end is branched and communicated with each of the branch exhaust passages downstream of these HC adsorbents while the other end is connected. Are provided to provide an HC introduction passage communicating with an exhaust passage upstream of the upstream catalyst body, and each of the branch exhaust passages alternately enters an exhaust flow state and an exhaust stop state every time the internal combustion engine is started. Switch to the exhaust flow state The HC is adsorbed on the HC adsorbent in the branch exhaust passage, and the HC adsorbed on the HC adsorbent in the branch exhaust passage in the exhaust stopped state is released. An exhaust gas purification apparatus for an internal combustion engine, further comprising control means for switchingly controlling the upstream switching valve and the downstream switching valve so as to be introduced into an exhaust passage and burn.