JP2004100548A - Exhaust gas processing device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas processing device for an internal combustion engine capable of improving exhaust gas purification performance regarding HC, while simplifying the constitution of an exhaust gas passage. <P>SOLUTION: The exhaust gas processing device for the internal combustion engine 1 is capable of supplying secondary air to a position on the upstream side from a catalyst 7 in the exhaust gas passage 6 through a secondary air supply passage 23 from an air pump 21. A storage part 25 capable of holding exhaust substances from the internal combustion engine is connected to the secondary air supply passage 23 apart from the exhaust gas passage 6. The rotational direction of the air pump 21 can be switched by means of an ECU 10 between the normal direction in which the secondary air is supplied to the secondary air supply passage 23 and the reverse direction in which suction force toward the storage part 25 is generated in the secondary air supply passage 23. The air pump 21 is reversely rotated when the state of the catalyst 7 is in a first stage before completion of warming-up and the air pump 21 is normally rotated when the state of the catalyst 7 is in a state before completion of warming-up and in a second stage in which warming-up is more accelerated than the first stage. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust treatment device capable of reducing the emission of harmful substances such as HC from an internal combustion engine.
[0002]
[Prior art]
During a cold start of the internal combustion engine, a large amount of HC (hydrocarbon) is discharged as unburned matter because the temperature of the combustion chamber is low and the supply amount of fuel is large. Generally, harmful substances such as HC and CO are purified using an oxidation catalyst or a three-way catalyst. However, at the time of cold start, the temperature of the catalyst is low and the catalyst is not activated. Therefore, it is difficult to efficiently purify a large amount of HC that is temporarily discharged at the time of starting with a catalyst. Therefore, for example, Patent Document 1 proposes an exhaust treatment device that suppresses the emission of HC by using an HC adsorbent until the catalyst exhibits a predetermined purification performance after a cold start. Patent Document 1 discloses that secondary air is supplied upstream of a catalyst in an exhaust passage separately from primary air introduced into an intake system to promote warm-up of the catalyst by heat of secondary combustion of exhaust gas. A secondary air supply device is also disclosed.
[0003]
[Patent Document 1]
JP-A-7-42539
[Patent Document 2]
JP-A-5-44447
[Patent Document 3]
JP-A-11-148344
[Patent Document 4]
JP-A-5-240037
[0004]
[Problems to be solved by the invention]
In the device of Patent Document 1 described above, an HC adsorbent is disposed between two catalysts provided in an exhaust passage, and HC released from the HC adsorbent with a rise in temperature is treated by a downstream catalyst. I have. Therefore, it is necessary to maintain the HC adsorbent at a temperature lower than the HC release temperature until the downstream catalyst is activated. As a solution to this problem, in the device of Patent Document 1, two catalysts are arranged integrally to promote warm-up of the downstream catalyst by the heat of the upstream catalyst and to guide the HC from the upstream catalyst to the HC adsorbent. The temperature of the exhaust gas is lowered. However, in order to realize such a function, it is necessary to integrate the two catalysts like a double pipe, which complicates the configuration of the exhaust system, and as a result, the durability and reliability of the exhaust system are reduced. Inconveniences such as deterioration and an increase in manufacturing cost occur. Further, since it is necessary to wind the exhaust passage at least once around from the upstream catalyst to the downstream catalyst via the HC adsorbent, the resistance of the exhaust passage increases, the back pressure of the exhaust system increases, and the performance of the internal combustion engine increases. May decrease.
[0005]
Therefore, an object of the present invention is to provide an exhaust treatment device for an internal combustion engine that can suppress emission of harmful substances such as HC while simplifying the configuration of an exhaust passage.
[0006]
[Means for Solving the Problems]
A first exhaust treatment device of the present invention is an exhaust treatment device for an internal combustion engine capable of supplying secondary air from an air pump to a position upstream of a catalyst in an exhaust passage via a secondary air supply passage, A holding means connected to the secondary air supply passage apart from the exhaust passage and capable of holding the exhaust from the internal combustion engine; and a suction force for generating a suction force toward the holding means in the secondary air supply passage. The above-mentioned subject is solved by providing an application means (claim 1).
[0007]
According to this exhaust treatment device, at the time of cold start or the like, in which a large amount of harmful substances such as HC are temporarily discharged, a suction force is applied to the secondary air supply passage, and the discharge from the internal combustion engine is transferred to the holding means. By taking in, release of HC and the like into the atmosphere can be suppressed. The discharged matter taken into the holding means may be guided to the catalyst after the warm-up is completed, or may be returned to the intake passage for post-treatment. It is also possible to treat the effluent by providing a purifying function in the holding means itself. Since the holding means is not installed on the exhaust passage, but is connected to the secondary air supply passage apart from the exhaust passage, an exhaust passage having a complicated structure such as a case where a holding means such as an HC adsorbent is provided on the exhaust passage is used. No need to form. Therefore, advantages such as improved durability and reliability of the exhaust system, reduced manufacturing cost, and reduced back pressure in the exhaust passage are obtained.
[0008]
The first exhaust processing device realizes a function of sucking the discharged material and a function of supplying the secondary air, and these functions may be appropriately used depending on the convenience of the exhaust processing. As an example, when the state of the catalyst is at the first stage before the completion of the warm-up, the discharged material is sucked into the holding means using the suction force of the suction force applying means, and the state of the catalyst is the state of the completion of the warm-up. Before and in the second stage where the warming-up has advanced from the first stage, the secondary air may be supplied to the exhaust passage via the secondary air supply passage (claim 2). However, when there is a concern about release of harmful substances such as HC, the discharge is not limited to the first stage, and the discharged matter may be appropriately sucked into the holding means.
[0009]
Immediately after the cold start of the internal combustion engine, the catalyst may be cooled by the supply of the secondary air, and if such a state is set as the first stage, the supply of the secondary air is temporarily suspended. The exhaust is sucked into the holding means to prevent the emission of harmful substances such as HC, and then the secondary air is supplied in the second stage to promote the secondary combustion by mixing the unburned matter and the secondary air. The warming of the catalyst can be promoted by the combustion heat.
[0010]
In the first exhaust treatment device of the present invention, the air pump may be used as the suction force applying means by rotating the air pump in a direction opposite to a direction in which the secondary air is supplied (claim 3). . In this case, it is not necessary to newly add pumps in order to generate a suction force, and it is possible to further simplify the configuration of the exhaust treatment device and further reduce the cost.
[0011]
In the first exhaust treatment apparatus of the present invention, the suction force applying means may generate the suction force by applying a negative pressure generated in an intake passage of an internal combustion engine to the holding means (Claim 4). ). Also in this case, it is not necessary to newly add pumps to generate a suction force, so that the configuration of the exhaust treatment device can be simplified and the cost can be further reduced. Since the holding means and the intake passage are connected to guide the negative pressure, the EGR can be realized by supplying the waste held by the holding means to the intake passage.
[0012]
In the case where a suction force is generated in the secondary air supply passage by using the negative pressure of the intake passage, when the discharge is sucked into the holding unit, the discharge is caused to pass through the intake passage and the holding unit. The negative pressure of the intake passage may act on the holding means (claim 5). In this case, the waste can be efficiently sucked by utilizing the negative pressure actually generated in the intake passage when the discharge needs to be sucked.
[0013]
Further, when the internal combustion engine is stopped, the negative pressure of the intake passage is stored in the holding unit through the intake passage and the holding unit, and the secondary air supply passage is used when the discharge is sucked into the holding unit. The negative pressure accumulated in the intake passage through the holding means may act on the holding means (claim 6). In this case, at least a part of the energy remaining when the internal combustion engine is stopped is stored in the holding means as a negative pressure, and is used for suctioning the exhaust afterward. Therefore, the energy use efficiency of the internal combustion engine is improved.
[0014]
Next, a second exhaust treatment device of the present invention is an exhaust treatment device for an internal combustion engine capable of supplying secondary air from an air pump to a position upstream of a catalyst in an exhaust passage via a secondary air supply passage. Holding means that is separated from the exhaust passage and is connected to the secondary air supply passage, and that can hold exhaust from the internal combustion engine, and rotates the air pump in the rotation direction with respect to the secondary air supply passage. By providing control means for switching control between a forward direction in which the secondary air is supplied and a reverse direction in which a suction force directed to the holding means is generated in the secondary air supply passage, the above-described problem is solved. Solved (claim 7).
[0015]
According to the second exhaust treatment apparatus, at the time of a cold start or the like, the air pump is rotated in the reverse direction to apply a suction force to the secondary air supply passage, thereby taking in the discharged matter into the holding means and putting it into the atmosphere. Emission of harmful substances such as HC can be suppressed. The discharged matter held by the holding means may be treated afterward by guiding the discharged matter to the catalyst after the warm-up is completed, or by returning it to the intake passage. It is also possible to treat the effluent by providing a purifying function in the holding means itself. Since the holding means is separated from the exhaust passage and connected to the secondary air supply passage, the durability and reliability of the exhaust system are improved, the manufacturing cost is reduced, and the height of the exhaust passage is reduced. Advantages such as a decrease in pressure are obtained. Further, it is not necessary to newly add pumps to generate a suction force, so that it is possible to further simplify the configuration of the exhaust treatment device and reduce costs.
[0016]
In the second exhaust processing device, the function of sucking the discharged material and the function of supplying the secondary air are selectively realized by switching the rotation direction of the air pump, and these functions are appropriately performed according to the convenience of the exhaust processing. You may use it properly. As an example, when the state of the catalyst is at the first stage before the completion of warm-up, the control unit rotates the air pump in the reverse direction, and when the state of the catalyst is before the completion of warm-up and the first stage The air pump may be rotated in the forward direction when the warming-up is in the second stage, which is more advanced (claim 8). However, when there is a concern about the release of harmful substances such as HC, the discharge is not limited to the first stage, and the discharge may be appropriately suctioned.
[0017]
Further, in the second exhaust treatment device, a bypass passage is provided in the secondary air supply passage, and the bypass passage is provided with the holding means and the bypass located closer to the air pump than the holding means. A first valve means for opening and closing the passage, and a flow path in the direction of flowing into the holding means, which is located farther from the air pump than the holding means, and preventing the flow in the direction of flowing out of the holding means; A second valve means may be provided, and the holding means may be further provided with a communication means for communicating the holding means with a predetermined position other than the secondary air supply passage (claim 9).
[0018]
In this case, the discharge is taken into the holding means in the bypass passage for the secondary air supply passage and the first valve means is closed, so that the discharge taken into the holding means is not included in the secondary air. It can be held by holding means. The discharged matter held by the holding means is guided to a predetermined position via the communication means, and can be appropriately processed. For example, a communication means may be provided so as to connect the holding means to an intake passage of the internal combustion engine (claim 10). If the holding means has a purifying function, the communication means may be provided to open the inside of the holding means to the atmosphere, for example.
[0019]
Further, a third exhaust treatment device of the present invention is an exhaust treatment device for an internal combustion engine capable of supplying secondary air from an air pump to a position upstream of a catalyst in an exhaust passage via a secondary air supply passage. Holding means that is provided in an exhaust gas recirculation passage that is separated from the exhaust gas passage and connects the secondary air supply passage and the intake air passage of the internal combustion engine, and that can retain exhaust from the internal combustion engine; A first on-off valve provided between the secondary air supply passage of the passage and the holding means for opening and closing the exhaust gas recirculation passage, and provided between the holding means and the intake passage of the exhaust gas recirculation passage; By providing a second on-off valve for opening and closing the exhaust gas recirculation passage, the above-described problem is solved (claim 11).
[0020]
According to the third exhaust treatment device, the air pump is stopped and the first on-off valve and the second on-off valve are opened, so that the negative pressure of the intake passage acts on the secondary air supply passage via the holding means, The discharge can be taken into the holding means via the secondary air supply passage. Therefore, release of harmful substances such as HC into the atmosphere can be suppressed as in the first and second exhaust treatment devices described above. The discharged matter taken into the holding means may be guided to the catalyst after the warm-up is completed, or may be returned to the intake passage for post-treatment. It is also possible to treat the effluent by providing a purifying function in the holding means itself. When the second on-off valve is opened, the holding means and the intake passage communicate with each other, so that EGR can be realized by using the discharge of the holding means. Since the holding means is not installed on the exhaust passage but is connected to the secondary air supply passage apart from the exhaust passage, a complicated exhaust passage is formed as in the case where a holding means such as an HC adsorbent is provided on the exhaust passage. No need. Therefore, advantages such as improved durability and reliability of the exhaust system, reduced manufacturing cost, and reduced back pressure in the exhaust passage are obtained. Further, it is not necessary to newly add pumps to generate a suction force, so that it is possible to further simplify the configuration of the exhaust treatment device and reduce costs. Further, by closing the first on-off valve and feeding the secondary air from the air pump into the secondary air supply passage, the secondary air can be supplied to the exhaust passage while preventing the secondary air from flowing out to the holding means.
[0021]
In the third exhaust treatment device of the present invention, when the state of the catalyst is at the first stage before the completion of warm-up, the air pump is stopped, and the first and second on-off valves and the second on-off valve are opened to open the catalyst. When the negative pressure of the intake passage is applied to the holding means and the secondary air supply passage, and the state of the catalyst is in a second stage before the completion of the warm-up and in a second stage where the warm-up is advanced from the first stage, Control means for closing the first on-off valve and the second on-off valve and rotating the air pump so that secondary air is supplied to the secondary air supply passage may be provided (claim 12). Alternatively, when the internal combustion engine is stopped, the first opening / closing valve is closed, the second opening / closing valve is opened, and the negative pressure of the intake passage is taken into the holding means, and then the second opening / closing valve is closed and the holding means is closed. When the state of the catalyst is at the first stage before the completion of warming-up, the air pump is stopped and the first on-off valve is opened with the second on-off valve closed, and the holding means is opened. The negative pressure stored in the second air supply passage is applied to the secondary air supply passage, and when the state of the catalyst is in a second stage in which the warm-up is more advanced than the first stage before the warm-up is completed, the first opening / closing is performed. Control means for closing the valve and rotating the air pump so that the secondary air is supplied to the secondary air supply passage may be provided (claim 13).
[0022]
In the former case, the waste can be efficiently sucked by utilizing the negative pressure actually generated in the intake passage when the exhaust needs to be sucked. In the latter case, at least a part of the energy remaining when the internal combustion engine is stopped is stored in the holding means as a negative pressure, and is used for taking in the emission later. Therefore, the energy use efficiency of the internal combustion engine is improved. However, if there is a concern about release of harmful substances such as HC, the discharge is not limited to the first stage, and the discharged matter may be appropriately sucked.
[0023]
In the present invention, the holding means may hold the exhaust gas as an emission as it is, or may hold a specific substance contained in the exhaust gas as an emission. As an example of the latter, the holding means may include an HC adsorbent (claim 14). When the HC adsorbent is provided as the holding means, it is desirable to provide the heating means (claim 15). This is because the heating means can promote the release of HC from the HC adsorbent. The catalyst may be used as the heating means (claim 16). Further, the holding means may include a tank for storing the discharge (claim 17). In this case, the exhaust discharged from the internal combustion engine can be stored in the tank as the exhaust gas.
[0024]
The discharged matter held by the holding means may be supplied to the exhaust passage while being included in secondary air (claim 18) or may be supplied to the intake passage (claim 19). In the former case, the exhaust gas is mixed with the secondary air sent from the secondary air supply device, so the unburned material for secondary combustion is supplemented to promote the warm-up of the catalyst, or the oxygen contained in the secondary air is By reducing the amount, formation of an excessive oxidizing atmosphere in the exhaust passage can be suppressed, and the NOx generation amount can be reduced. In the latter case, the unburned matter held by the holding means can be returned to the intake passage and recombusted, or the amount of oxygen in the intake air can be reduced to reduce the NOx generation amount. In particular, when the holding means holds the exhaust gas, the temperature of the gas returned to the intake passage by the exhaust gas releasing heat during the holding decreases, and the effect of reducing the NOx generation amount increases.
[0025]
In each of the exhaust treatment devices of the present invention, the secondary air supply passage is provided for the purpose of supplying secondary air to the exhaust passage, and at least a part thereof is adjacent to the exhaust passage. Therefore, the exhaust gas can be relatively easily taken into the secondary air supply passage from the exhaust passage. In the simplest case, the exhaust gas can be sucked from the opening for supplying the secondary air to the exhaust passage of the secondary air supply passage. Alternatively, the exhaust gas may be guided to the secondary air supply passage by connecting the exhaust passage and the secondary air supply passage at a position different from the opening for supplying the secondary air.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an exhaust treatment device according to a first embodiment of the present invention and an internal combustion engine to which the exhaust treatment device is attached. The internal combustion engine 1 is configured as an in-line four-cylinder gasoline engine for a vehicle in which four cylinders 1a are arranged in a line. As is well known, air (primary air) corresponding to the opening degree of the throttle valve 4 is sucked into the intake passage 2 of the internal combustion engine 1 through the air filter 3, and the air is passed through the intake manifold 5 to each cylinder. 1a. The exhaust gas from the cylinder 1a is guided to the catalyst 7 through the exhaust passage 6, purified, and then discharged to the atmosphere through a silencer (not shown). As the catalyst 7, a three-way catalyst that oxidizes HC and CO while reducing NOx, a NOx storage catalyst, or the like is used.
[0027]
Although not shown in FIG. 1, the intake passage 2 is provided with an air flow meter that outputs a signal corresponding to the amount of intake air, and a throttle opening sensor that outputs a signal corresponding to the opening of the throttle valve 4. In addition, before and after the catalyst 7 in the exhaust passage 6, an output signal corresponding to the amount of oxygen in the exhaust gas is output. ₂ Sensors (which may be air-fuel ratio sensors) 8 and 9 are provided, respectively. In addition to these, a water temperature sensor that outputs a signal corresponding to the cooling water temperature of the internal combustion engine 1, an intake temperature sensor that outputs a signal corresponding to the intake air temperature, a crank angle sensor that outputs a signal corresponding to the angle of the crankshaft Are provided in the internal combustion engine 1. The output signal of each sensor is guided to an engine control unit (ECU) 10. The ECU 10 is configured as a computer including a microprocessor and peripheral circuits such as a ROM and a RAM necessary for the operation of the ECU 10. The ECU 10 refers to output signals of the various sensors described above and refers to a fuel injection amount, a fuel injection timing, Control ignition timing and the like.
[0028]
The internal combustion engine 1 is provided with an exhaust treatment device 20A. The exhaust processing device 20A includes an electric air pump 21 as an air supply source, a filter 22 for filtering air sucked into the air pump 21, and a device for guiding air discharged from the air pump 21 to the exhaust passage 6 as secondary air. A secondary air supply passage 23 and a first air switching valve (first ASV) 24 for opening and closing the secondary air supply passage 23 are provided. The rotation direction of the air pump 21 can be switched between forward and reverse. In addition, the rotation direction at the time of discharging air to the secondary air supply passage 23 is defined as a forward direction, and the rotation in the forward direction is described as a forward rotation.
[0029]
The secondary air supply passage 23 includes a main passage 23a extending from the air pump 21, and four branch passages 23b connecting the main passage 23a and the exhaust port 6a of each cylinder 1a. The first ASV 24 allows a flow in the direction from the air pump 21 to the branch passage 23b via the main passage 23a, and blocks the flow in the opposite direction, and opens and closes the main passage 23a using electromagnetic force. And a solenoid valve portion 24b.
[0030]
In order for the exhaust processing device 20A to function as an exhaust gas collecting device, a storage section 25 as an exhaust gas holding means is provided in the main passage 23a of the secondary air supply passage 23. The storage section 25 is configured such that the main passage 23a is partially expanded at a position closer to the exhaust passage 6 than the first ASV 24, and the HC adsorbent 25a is accommodated inside the expanded portion. The storage unit 25 is disposed adjacent to the catalyst 7 to such an extent that heat can be exchanged between the catalyst 7 and the storage unit 25. A bypass passage 26 that bypasses the first ASV 24 is connected to a side of the main passage 23a closer to the air pump 21 than the storage unit 25 is. The bypass passage 26 is provided with a second air switching valve (second ASV) 27. The second ASV 27 is a solenoid valve that opens and closes the bypass passage 26 using electromagnetic force.
[0031]
The operations of the air pump 21, the solenoid valve portion 24b of the first ASV 24, and the second ASV 27 are controlled by the ECU 10. When the solenoid valve portion 24b of the first ASV 24 is opened and the air pump 21 is rotated forward, secondary air is supplied to the exhaust passage 6 via the secondary air supply passage 23. When the first ASV 24 is closed, the second ASV 27 is opened, and the air pump 21 is reversed, a suction force acts on the secondary air supply passage 23, and the exhaust gas from the exhaust port 6a is taken into the main passage 23a from the branch passage 23b. If the HC adsorbent 25a is at or below a predetermined HC release temperature, HC in the exhaust gas taken into the secondary air supply passage 23 is adsorbed by the HC adsorbent 25a. When the temperature of the HC adsorbent 25a becomes equal to or higher than the HC release temperature, HC is released from the HC adsorbent 25a. The HC release temperature varies depending on the type of HC adsorbed on the HC adsorbent 25a. HC released from the HC adsorbent can be returned to the exhaust passage 6 together with the secondary air by rotating the air pump 21 forward. The returned HC can be processed by utilizing the secondary combustion in the exhaust passage 6 or the purifying action of the catalyst 7.
[0032]
The operations of the air pump 21, the first ASV 24, and the second ASV 27 may be appropriately switched according to the necessity of supplying the secondary air and the necessity of taking the exhaust gas into the storage unit 25. FIG. 2 is a time chart showing the contents of preferable operation control of the exhaust treatment device 20A executed by the ECU 10 when the internal combustion engine 1 is cold started.
[0033]
In the example of FIG. 2, when the ignition switch of the internal combustion engine 1 is turned on and the starter motor is started (ON), the air pump 21 starts reverse rotation, and the second ASV 27 is opened. The first ASV 24 is kept closed. The ECU 10 monitors the success or failure of the start of the internal combustion engine 1 in accordance with a predetermined condition, and when it is determined that the start is successful, changes the start flag stored in the RAM to a value corresponding to the start state. In FIG. 2, the start state is expressed as ON, and the state not started is expressed as OFF. In the following description, the state of the start flag is expressed in accordance with FIG. When a predetermined time A has elapsed from the time when the start flag was turned on, the rotation direction of the air pump 21 is switched to the forward direction, and the second ASV 27 is closed. Thereafter, the first ASV 24 and the second ASV 27 are closed until the predetermined time B has elapsed. When the predetermined time B has elapsed, the first ASV 24 is opened and the second ASV 27 is kept closed. Thereafter, when a predetermined time C has elapsed, the air pump 21 is stopped, and the first ASV 24 is closed.
[0034]
According to the above processing, the air pump 21 is driven in the reverse direction in the first stage (range of the predetermined time A) before the warm-up of the catalyst 7 is completed, and the suction force acts on the secondary air supply passage 23, Exhaust gas is sucked from the exhaust port 6a, and HC in the exhaust gas is adsorbed by the HC adsorbent 25a. During this time, the exhaust gas is also guided to the catalyst 7, and the secondary combustion of the unburned matter contained in the exhaust gas gradually heats the catalyst 7. When the catalyst 7 is warmed up to a certain extent, the suction of the exhaust gas into the secondary air supply passage 23 is stopped, and then the second stage until the warming up of the catalyst 7 is completed (a predetermined time from the elapse of the predetermined time B) Until the time C elapses), the secondary air is supplied to the exhaust passage 6. During this time, the HC adsorbent 25a is heated by the heat of the catalyst 7, and HC is gradually released. Then, the HC released from the HC adsorbent 25a is returned to the exhaust passage 6 by the secondary air passing through the storage unit 25. As a result, oxygen and unburned matter are supplied to the exhaust passage 6 from the secondary air supply passage 23. As a result, the secondary combustion of the unburned matter discharged from the internal combustion engine 1 and the unburned matter returned from the secondary air supply passage 23 is promoted, and the warm-up of the catalyst 7 is accelerated.
[0035]
As is clear from the above description, the predetermined time C is set as a time required for the catalyst 7 to warm up to a predetermined state. The predetermined times A and B may be appropriately determined in consideration of the adsorption capacity of the HC adsorbent 25a and the purification capacity of the catalyst 7. For example, the predetermined time A is a time required for warming up the catalyst 7 to such an extent that the amount of HC released into the atmosphere is suppressed to a predetermined allowable level, or a large amount of HC is temporarily discharged when the internal combustion engine 1 is started. It may be set as the time to be discharged. Alternatively, the predetermined time A may be set as the time required until the HC adsorption amount of the HC adsorbent 25a is substantially saturated. However, as long as priority is given to completing the warm-up of the catalyst 7 as soon as possible by supplying the secondary air, the shorter the predetermined time A is, the better the range in which the amount of HC release can be suppressed to an allowable level.
[0036]
The predetermined time B may be determined so that a delay time required when switching the rotation direction of the air pump 21 occurs between the predetermined time A and the predetermined time B. For example, even if the instruction of the rotation direction to the air pump 21 is switched, the actual rotation direction may not immediately change due to the inertia of the impeller of the air pump 21. In such a case, a delay time longer than the time from when the rotation direction is instructed to the air pump 21 until the rotation direction is actually switched in response to the instruction is set between the predetermined times A and B. By doing so, the opening of the first ASV 24 is delayed until the secondary air is actually sent from the air pump 21, and the backflow of the air containing the exhaust gas can be reliably prevented.
[0037]
FIG. 3 is a flowchart showing a secondary air supply control routine executed by the ECU 10 to control the air pump 21, the first ASV 24, and the second ASV 27 according to the time chart of FIG. This process is repeatedly executed at a predetermined cycle after the ignition switch of the internal combustion engine 1 is turned on. However, the execution time may be limited to a certain period after the start of the internal combustion engine 1 until the catalyst 7 is completely warmed up and the supply of the secondary air is determined to be unnecessary.
[0038]
In the routine of FIG. 3, the ECU 10 first determines in step S11 whether a secondary air supply condition is satisfied. The secondary air supply condition is set as a condition for determining whether the warm-up state of the catalyst 7 has reached a predetermined level, and includes, for example, the temperature of the cooling water, the intake air temperature, the temperature of the catalyst 7, and the like. The condition is set by at least one parameter that can be used to determine the warm-up state of the seventh condition. When the warm-up of the catalyst 7 is insufficient, it is determined that the secondary air supply condition is satisfied. In that case, the ECU 10 proceeds to step S12 and determines whether the starter of the internal combustion engine 1 is turned on. I do. If the starter is ON, the process proceeds to step S13, and it is determined whether the start flag is ON. When the start flag is OFF, the process proceeds to step S17 to close the first ASV 24, open the second ASV 27 in step S18, and reverse the air pump 21 in step S19. In this case, the exhaust gas is sucked from the exhaust passage 6 toward the storage unit 25.
[0039]
On the other hand, if the start flag is ON in step S13, it is determined whether the start flag was ON at the time of the previous execution of the routine. If the previous time is not ON, the process proceeds to step S15 to start the timer, and if the previous time is ON, step S15 is skipped. The timer started here is a criterion for judging whether or not the predetermined times A, B and C have elapsed. After the processing of step S14 or step S15, the process proceeds to step S16 to determine whether or not a predetermined time A has elapsed. If the predetermined time A has not been exceeded, the process proceeds to step S17 and subsequent steps. If the predetermined time A has elapsed, the process proceeds to step S20 to determine whether or not the predetermined time B has elapsed. If the predetermined time B has elapsed, the process proceeds to step S21 to close the first ASV 24, and in step S22, the first ASV 24 is closed. The 2ASV 27 is closed, and the air pump 21 is rotated forward in step S23.
[0040]
If the predetermined time B has elapsed in step S20, it is determined in step S24 whether the predetermined time C has elapsed. If not, the process proceeds to step S25 to open the first ASV 25, and in step S26, the second ASV 27 is opened. The air pump 21 is normally rotated in step S27. Thereby, secondary air is supplied to the exhaust passage 6. If the predetermined time C has not elapsed in step S24, the process proceeds to step S28 to close the first ASV 24, close the second ASV 27 in step S29, and stop the air pump 21 in step S30. Even when the secondary air supply condition is not satisfied in step S11, the processing of steps S28 to S30 is executed. After controlling the operation of the air pump 21 in step S19, S23, S27 or S30, the current routine is ended and the process returns to the predetermined main routine.
[0041]
In this embodiment, the ECU 10 implements a suction force applying unit by rotating the air pump 21 in the reverse direction. Then, the ECU 10 functions as control means for switching control of the rotation direction of the air pump, and the catalyst 7 functions as heating means for the holding means. The control means may be realized by a computer different from the ECU 10. Instead of the catalyst 7, an electric heater or the like may be used as heating means. The heating means only needs to be able to heat the HC adsorbent 25a to 70 to 80 ° C, at most about 200 ° C.
[0042]
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS. 4 to FIG. 6, the same reference numerals are given to the same parts as those in FIG. 1 to FIG.
[0043]
In the exhaust treatment device 20B of FIG. 4, a tank 30 is provided in the middle of the bypass passage 26 instead of the storage unit 25 of FIG. Therefore, the exhaust gas sucked into the secondary air supply passage 23 is stored in the tank 30 as it is. The tank 30 may be configured as a highly rigid container that maintains a constant shape regardless of the amount of exhaust gas stored, or may be configured as a flexible bag-shaped container whose shape changes according to the amount of exhaust gas stored. Good. The second ASV 27 is provided between the tank 30 and the air pump 21. A reed valve 31 is arranged between the tank 30 and the exhaust gas intake portion (branch passage 23b). The reed valve 31 allows the flow of exhaust gas from the branch passage 23b toward the tank 30, and prevents the flow of exhaust gas in the opposite direction.
[0044]
The tank 30 is connected to the intake passage 2 via an EGR passage 32. The EGR passage 32 is provided with an EGR valve 33 for opening and closing the EGR passage 32. The EGR valve is a solenoid valve that is opened and closed in response to an instruction from the ECU 10, similarly to the second ASV 27 and the like. The connection position between the EGR passage 32 and the intake passage 2 is set to, for example, the intake manifold 5.
[0045]
According to the above configuration, the first ASV 24 and the EGR valve 33 are closed, the second ASV 27 is opened, and the air pump 21 is rotated in reverse, so that the suction force is applied to the secondary air supply passage 23 via the tank 30 and the exhaust passage 6 Exhaust gas can be sucked into the tank 30. When the second ASV 27 and the EGR valve 33 are closed and the first ASV 24 is opened to rotate the air pump 21 forward, the secondary air can be supplied to the exhaust passage 6 via the secondary air supply passage 23. Further, when the EGR valve 33 is opened with the first ASV 24 and the second ASV 27 closed, the exhaust gas is taken into the intake passage 2 by applying the negative pressure of the intake passage 2 to the tank 30 and the secondary air supply passage 23. EGR can be realized. When the air pump 21 is rotated forward, secondary air may flow into the tank 30 via the reed valve 31. However, the second ASV 27 and the EGR valve 33 are closed to prevent pressure from flowing out of the tank 30. As long as the pressure in the tank 30 is substantially equal to or higher than the pressure in the secondary air supply passage 23, the reed valve 31 does not open.
[0046]
Also in the present embodiment, the operations of the first ASV 24, the second ASV 27, and the EGR valve 33 are appropriately switched according to the necessity of supplying the secondary air, the necessity of taking the exhaust gas into the tank 30, and the necessity of performing the EGR. Good. FIG. 5 is a time chart showing the contents of preferable operation control of the exhaust treatment device 20B executed by the ECU 10 at the time of the cold start of the internal combustion engine 1. In this example, the relationship between the ignition switch, the starter, the start flag, the air pump 21, the first ASV 24, and the second ASV 27 is the same as that in FIG. 2, and a detailed description thereof will be omitted. The EGR valve 33 is kept closed at least until a predetermined time C has elapsed, and is opened at an appropriate time thereafter.
[0047]
When the operation of each part is switched as shown in FIG. 5, the air pump 21 is driven in the reverse direction in the first stage (range of the predetermined time A) before the warm-up of the catalyst 7 is completed, and the secondary air supply passage The suction force acts on 23, and the exhaust gas is sucked into the tank 30 from the exhaust port 6 a. During this time, the exhaust gas is also guided to the catalyst 7, and the secondary combustion of the unburned matter contained in the exhaust gas gradually heats the catalyst 7. When the catalyst 7 is warmed up to a certain extent, the suction of the exhaust gas into the secondary air supply passage 23 is stopped, and then the second stage until the warming up of the catalyst 7 is completed (a predetermined time from the elapse of the predetermined time B) Until the time C elapses), the secondary air is supplied to the exhaust passage 6. Thereby, the secondary combustion of the unburned matter from the internal combustion engine 1 is promoted, and the warm-up of the catalyst 7 is accelerated.
[0048]
Since the EGR valve 33 is closed during the supply of the secondary air, the exhaust gas is held in the tank 30. The exhaust gas is returned to the intake passage 2 by opening the EGR valve 33 later. As a result, the amount of oxygen in the intake air decreases, and the NOx generation amount decreases. Since the exhaust gas radiates heat while being held in the tank 30, the temperature of the exhaust gas returned to the intake passage 2 decreases as compared with the case where the exhaust gas is immediately returned from the exhaust port 6a. Therefore, the combustion temperature in the cylinder 1a decreases, and the NOx reduction effect further increases. Thus, the tank 30 can also function as an EGR cooler. In order to enhance the cooling effect of the exhaust gas, means for increasing the amount of heat exchange inside and outside the tank 30 may be provided, such as providing a radiation fin in the tank 30.
[0049]
Note that the operation control regarding the air pump 21, the first ASV 24, and the second ASV 27 in FIG. 5 is the same as that in the first embodiment, so that the processing to be executed by the ECU 10 to realize this may be as shown in FIG. For the control of the EGR valve 33, the ECU 10 may repeatedly execute the EGR control routine shown in FIG.
[0050]
The process of FIG. 6 is repeatedly executed at a predetermined cycle after the ignition switch of the internal combustion engine 1 is turned on. In this EGR control routine, the ECU 10 first determines in step S31 whether secondary air supply conditions are satisfied. This process is the same as step S11 in FIG. Then, when the supply condition is satisfied, the process proceeds to step S34, the EGR valve 33 is closed, and the routine ends. This ensures that the EGR valve 33 is kept closed until the predetermined time C in FIG. 5 has elapsed. If the supply condition is not satisfied in step S31, the process proceeds to step S32, and it is determined whether the EGR operation condition is satisfied. This condition may be set similarly to the condition for determining whether or not EGR is appropriate in a general EGR device. When the EGR operation condition is not satisfied, the process proceeds to step S34.
[0051]
On the other hand, if the EGR operation condition is satisfied, the EGR valve 33 is opened in step S33, and the routine ends. As a result, if the EGR operation condition is satisfied, the EGR valve 33 is opened, the negative pressure in the intake passage 2 acts on the tank 30 and the secondary air supply passage 23, and the exhaust gas held in the tank 30 is removed from the intake passage. It is sucked into 2. During the execution of EGR, the exhaust gas in the exhaust passage 6 is sequentially sucked from the secondary air supply passage 23 into the tank 30 via the reed valve 31. Since both the first ASV 24 and the second ASV 27 are closed, there is no possibility that the outside air is taken into the tank 30 and the action of the EGR is impaired.
[0052]
In this embodiment, the ECU 10 reverses the air pump 21 to realize a suction force applying unit. In addition, the ECU 10 functions as a control unit that controls switching of the rotation direction of the air pump 21. However, the control means may be realized by a computer different from the ECU 10. Further, the second ASV 27 corresponds to first valve means, the reed valve 31 corresponds to second valve means, and the EGR passage 32 and the EGR valve 33 correspond to communication means. As the holding means, a storage unit 25 containing an HC adsorbent 25a may be provided instead of the tank 30.
[0053]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. In FIGS. 7 to 10, the same parts as those in FIGS. 1 to 6 are denoted by the same reference numerals.
[0054]
In the exhaust treatment device 20C of FIG. 7, the introduction passage is located at a position closer to the branch passage 23b than the first ASV 24 of the main passage 23a of the secondary air supply passage 23 in place of the bypass passage 26 of the exhaust treatment device 20B shown in FIG. The tank 30 is connected to the end of the introduction passage 34 via the second ASV 27. Other configurations are the same as those of the exhaust treatment device 20B of FIG.
[0055]
In the configuration of the present embodiment, even if the air pump 21 is reversed, the suction force does not act on the tank 30 and exhaust gas cannot be taken into the tank 30. Instead, the negative pressure of the intake passage 2 is introduced into the tank 30 by opening the EGR valve 33 to apply a negative pressure to the tank 30. Further, the first ASV 24 is closed and the second ASV 27 is opened to open the negative pressure in the tank 30. By applying the pressure to the secondary air supply passage 23, the exhaust gas in the exhaust passage 6 can be sucked into the tank 30. The exhaust gas held in the tank 30 can be returned to the intake passage 2 as EGR by closing the first ASV 24 and opening the second ASV 27 and the EGR valve 33. When supplying the secondary air, the second ASV 27 may be closed, the first ASV 24 may be opened, and the air pump 21 may be rotated forward.
[0056]
Also in the present embodiment, the operations of the first ASV 24, the second ASV 27, and the EGR valve 33 are appropriately switched according to the necessity of supplying the secondary air, the necessity of taking the exhaust gas into the tank 30, and the necessity of performing the EGR. Good. FIG. 8 is a time chart showing the contents of preferable operation control of the exhaust treatment device 20C executed by the ECU 10 when the internal combustion engine 1 is cold started.
[0057]
In the example of FIG. 8, when the ignition switch of the internal combustion engine 1 is turned on and the starter motor is started (ON), the second ASV 27 is opened, and the EGR valve 33 is opened with a delay of a predetermined delay time d. The air pump 21 is maintained in a stopped state, and the first ASV 24 is maintained in a closed state. The delay time d is provided because the combustion in the cylinder becomes unstable when the EGR valve 33 is opened while the rotation speed of the internal combustion engine 1 is increasing at the time of starting, so that the rotation speed of the internal combustion engine 1 increases. This is because the EGR valve 33 is opened at a timing when the fuel is appropriately stabilized. When a predetermined time A elapses with reference to the timing when the start flag is turned on, the second ASV 27 and the EGR valve 33 are respectively closed, and in exchange for them, the first ASV 24 is opened, and the air pump 21 starts normal rotation. Thereafter, when a predetermined time C has elapsed, the air pump 21 is stopped, and the first ASV 24 is closed. After the rotation of the air pump 21 starts, the second ASV 27 and the EGR valve 33 are kept closed at least until a predetermined time C has elapsed. These valves 27 and 33 are opened at an appropriate time after the air pump 21 stops.
[0058]
When the operation of each part is switched as shown in FIG. 8, in the first stage (range of the predetermined time A) before the warm-up of the catalyst 7 is completed, the EGR valve 33 and the second ASV 27 are opened and the first ASV 24 is closed. Therefore, the negative pressure in the intake passage 2 acts on the secondary air supply passage 23 via the tank 30, and the exhaust gas is sucked into the tank 30 from the exhaust port 6 a. While the exhaust gas is being sucked into the tank 30, the exhaust gas is also guided to the catalyst 7, and the secondary combustion of the unburned matter contained in the exhaust gas gradually heats the catalyst 7. When the catalyst 7 is warmed up to a certain extent, the suction of the exhaust gas into the secondary air supply passage 23 is stopped, and then the second stage until the warming up of the catalyst 7 is completed (a predetermined time from the elapse of the predetermined time A) At the time (elapse of time C), the air pump 21 is driven in the forward direction and secondary air is supplied to the exhaust passage 6. Thereby, the secondary combustion of the unburned matter from the internal combustion engine 1 is promoted, and the warm-up of the catalyst 7 is accelerated.
[0059]
During the supply of the secondary air, the second ASV 27 and the EGR valve 33 are closed, so that the exhaust gas is held in the tank 30, and the temperature of the exhaust gas in the tank 30 gradually decreases due to heat radiation from the tank 30. The second ASV 27 and the EGR valve 33 are opened at an appropriate time after the completion of the warm-up of the catalyst 7, so that the appropriately cooled exhaust gas flows from the tank 30 into the intake passage 2 via the EGR passage 32 as EGR. Will be returned. As a result, the NOx generation amount decreases.
[0060]
FIGS. 9 and 10 are flowcharts showing a secondary air supply control routine executed by the ECU 10 to control the air pump 21, the first ASV 24, the second ASV 27, and the EGR valve 33 according to the time chart of FIG. This process is repeatedly executed at a predetermined cycle after the ignition switch of the internal combustion engine 1 is turned on.
[0061]
In comparison with the secondary air supply control routine shown in FIG. 3, in the secondary air supply control routine of FIGS. 9 and 10, step S20 is omitted, step S41 is provided instead of step S19, and step S42 is further provided. To S46 (FIG. 9) and S47 to S49 (FIG. 10). Other parts are the same as those in FIG. The following description focuses on the differences.
[0062]
First, if the secondary air supply condition is satisfied in step S11, the process proceeds to step S17 to close the first ASV 24 and opens the second ASV 27 in step S18 unless it is determined that the predetermined time A has elapsed in step S16. . Thereafter, the process proceeds to step S41, in which the air pump 21 is stopped. In step S42, it is determined whether or not the delay time d is in progress. If it is not the delay time d, the EGR valve 33 is opened in step S43 and the routine ends. According to these processes, after the starter is turned on, the negative pressure in the intake passage 2 acts on the secondary air supply passage 23 side until the predetermined time A elapses, and the exhaust gas is sucked into the tank 30. The determination as to whether or not the time is during the delay time d can be performed, for example, by activating a timer at the time when the process of step S41 is first performed and determining whether or not time measurement has progressed to the delay time d.
[0063]
On the other hand, if the predetermined time A has elapsed in step S16, then it is determined in step S24 whether the predetermined time C has elapsed. If the predetermined time C has not elapsed, the first ASV 24 is opened in step S25, the second ASV 27 is closed in step S26, and the air pump 21 is rotated forward in step S27. Further, in step S44, the EGR valve 33 is closed and the routine ends. In this case, secondary air is sent from the air pump 21 to the exhaust passage 6, and the second ASV 27 and the EGR valve 33 are closed, so that the exhaust gas is held in the tank 30.
[0064]
If the predetermined time C has elapsed in step S24, the first ASV 24 is closed in step S28, the second ASV 22 is closed in step S29, and the air pump 21 is stopped in step S30. Further, in step S45, the EGR valve 33 is closed and the routine ends.
[0065]
When the supply condition is not satisfied in step S11, that is, when the warm-up of the catalyst 7 is completed, the process proceeds to step S46, and it is determined whether the EGR operation condition is satisfied. This condition may be the same as that in step S32 in FIG. If the operating condition is not satisfied, the process proceeds to step S28 and thereafter. On the other hand, when the EGR operation condition is satisfied, the process proceeds to step S47 in FIG. 10 to close the first ASV 24, open the second ASV 27 in step S48, open the EGR valve 33 in step S49, and end the routine. As a result, the exhaust gas held in the tank 30 is drawn into the intake passage 2 to realize EGR. During the execution of the EGR, the exhaust gas in the exhaust passage 6 is sequentially sucked from the secondary air supply passage 23 into the tank 30 via the second ASV 27. Since the first ASV 24 is closed, there is no possibility that outside air is taken into the tank 30 and the action of EGR is impaired.
[0066]
In the exhaust treatment device 20C, the operation of applying a negative pressure to the tank 30 can be executed when the internal combustion engine 1 is stopped. For example, as shown in FIG. 11, when the ignition switch is turned off, the second ASV 27 is closed, the EGR valve 33 is opened for a predetermined time to allow the tank 30 to temporarily communicate with the intake passage 2, and then the second ASV 27 and the EGR valve 33 Can be stored in a closed state, and a negative pressure can be stored in the tank 30 and used as a suction force at the time of the next start or the like. When the negative pressure is stored at the time of stop, the EGR valve 33 may be kept closed when exhaust gas is sucked into the tank 30 at the time of start.
[0067]
FIG. 12 is a flowchart showing an example of a negative pressure intake control routine to be executed by the ECU 10 when negative pressure is introduced into the tank 30 according to FIG. This negative pressure intake control routine may be repeatedly executed at a predetermined cycle, for example, triggered by turning off the ignition switch. In the first step S51, the second ASV 27 is closed, in the next step S52, the EGR valve 33 is opened, and in the following step S53, a timer for measuring the time during which the EGR valve 33 is open is started. If the timer has already been started, the timer is not reset, and the timer continues. In the next step S54, the change of the start flag to OFF is prohibited. In step S55, it is determined whether or not the opening time of the EGR valve 33 has exceeded a predetermined time from the time measured by the timer. If the predetermined time has not elapsed, the routine ends. If the predetermined time has elapsed, the EGR valve 33 is closed in step S56, and the prohibition of the change of the start flag to OFF is released in step S57, and the routine ends.
[0068]
In this embodiment, when the ECU 10 sucks the exhaust gas into the tank 30 or when the internal combustion engine 1 stops, the ECU 10 opens the EGR valve 33 and the second ASV 27 to realize the suction force applying means. An exhaust gas recirculation passage is formed by the introduction passage 34 and the EGR passage 32, and the second ASV 27 corresponds to a first on-off valve, and the EGR valve 33 corresponds to a second on-off valve. As the holding means, a storage unit 25 containing an HC adsorbent 25a may be provided instead of the tank 30.
[0069]
The present invention is not limited to the above embodiments, and may be implemented in various forms. In the above embodiments, the exhaust gas is taken from the branch passage 23b of the secondary air supply passage 23, but the exhaust gas may be taken from another position. As an example, as shown in FIG. 13, a suction passage 35 connecting the exhaust passage 6 and the secondary air supply passage 23 is provided separately from the branch passage 23b, and is provided at a connection position between the suction passage 35 and the secondary air supply passage 23. The switching valve 36 provided may alternatively connect the air pump 21 and the storage unit 25 to the side of the branch passage 23b when supplying secondary air, or to the side of the suction passage 35 when taking in exhaust gas. In this case, there is an advantage that the position for supplying the secondary air and the position for taking in the exhaust gas can be set to optimal positions according to their purposes. Since it is desirable to supply the secondary air to a position where the temperature of the exhaust gas is as high as possible, the branch passage 23b is opened at a position as close to the cylinder 1a as possible. Since the gas can be taken in, it is connected to the exhaust passage 6 downstream of the branch passage 23 b and upstream of the catalyst 7.
[0070]
As shown in FIG. 14, the intake passage 35 may be connected to the exhaust passage 6 downstream of the catalyst 7. In this case, since the exhaust gas that has passed through the catalyst 7 is taken into the storage unit 25, a large amount of exhaust gas can be guided by the catalyst 7 at the start time, and the warming-up promotion effect by the secondary combustion increases. Further, by increasing the flow rate of the exhaust gas taken into the secondary air supply passage 23, all or most of the exhaust gas that cannot be processed by the catalyst 7 can be taken into the storage unit 25, thereby preventing the release of harmful substances into the atmosphere. The effect can be further enhanced.
[0071]
The suction passage 35 and the switching valve 36 shown in FIGS. 13 and 14 can be applied to the above-described second or third embodiment. The activation of the timer (step S15) in the flowchart shown in FIG. 3 or FIG. 9 may be executed in association with the ignition ON or the starter ON. The period during which the exhaust gas is taken in and the period in which the secondary air is supplied are not limited to the example determined by the elapsed time, but the warm-up of the catalyst 7 such as the integrated intake air amount from the start, the exhaust gas flow rate, the secondary air flow rate, and the like. May be determined in association with various physical quantities that are considered to be related to the progress of the calculation.
[0072]
【The invention's effect】
As described above, according to the exhaust treatment apparatus of the present invention, the suction force is applied to the secondary air supply passage at the time of cold start or the like in which a large amount of harmful substances such as HC are temporarily discharged. By taking the discharge from the engine into the holding means, the release of harmful substances such as HC into the atmosphere can be suppressed. In addition, since the holding means is not provided on the exhaust passage but is connected to the secondary air supply passage apart from the exhaust passage, the exhaust having a complicated structure such as the case of providing the holding means such as an HC adsorbent on the exhaust passage is provided. There is no need to form a passage. Therefore, excellent effects such as simplification of the configuration of the exhaust passage, improvement of durability and reliability of the exhaust system, reduction of manufacturing cost, and reduction of back pressure of the exhaust passage can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an exhaust treatment device according to a first embodiment of the present invention.
FIG. 2 is a time chart showing a correlation between states of respective parts of the exhaust treatment device when the internal combustion engine of FIG. 1 is cold started.
FIG. 3 is a flowchart of a secondary air supply control routine executed by an ECU to control operation according to the time chart of FIG. 2;
FIG. 4 is a diagram showing a schematic configuration of an exhaust treatment device according to a second embodiment of the present invention.
FIG. 5 is a time chart showing a correlation between states of respective parts of the exhaust treatment device when the internal combustion engine of FIG. 4 is cold started.
FIG. 6 is a flowchart of an EGR control routine executed by the ECU to control the operation of the EGR valve according to the time chart of FIG. 5;
FIG. 7 is a diagram showing a schematic configuration of an exhaust treatment device according to a third embodiment of the present invention.
8 is a time chart showing a correlation between states of each part of the exhaust treatment device when the internal combustion engine of FIG. 7 is cold started.
FIG. 9 is a flowchart of a secondary air supply control routine executed by the ECU to control the operation according to the time chart of FIG. 8;
FIG. 10 is a flowchart following FIG. 9;
FIG. 11 is a time chart showing a modification of the embodiment of FIG. 8;
FIG. 12 is a flowchart of a negative pressure intake control routine executed by the ECU to control the operation according to the time chart of FIG. 8;
FIG. 13 is a view corresponding to FIG. 1 showing a modified example in which the exhaust gas intake position is changed.
FIG. 14 is a view showing a further modification of FIG. 13;
[Explanation of symbols]
1 Internal combustion engine
2 Intake passage
6 Exhaust passage
10 Engine control unit
20A, 20B, 20C Exhaust treatment device
21 Air pump
23 Secondary air supply passage
23a Main passage
23b Branch passage
24 First air switching valve
24a Reed valve part
24b solenoid valve
25 storage
25a HC adsorbent
26 Bypass passage
27 Second air switching valve
30 tanks
31 Reed valve
32 EGR passage
33 EGR valve
34 Connection passage

Claims (19)

In an exhaust treatment apparatus for an internal combustion engine capable of supplying secondary air from an air pump to a position upstream of a catalyst in an exhaust passage via a secondary air supply passage, the secondary air supply passage separated from the exhaust passage Holding means capable of holding the exhaust from the internal combustion engine,
Suction force applying means for generating a suction force toward the holding means in the secondary air supply passage,
An exhaust treatment device for an internal combustion engine, comprising: When the state of the catalyst is at the first stage before the completion of warm-up, the discharge is sucked into the holding means by using the suction force of the suction force applying means, and the state of the catalyst is before the completion of warm-up. 2. The exhaust system according to claim 1, wherein the secondary air is supplied to the exhaust passage via the secondary air supply passage when the engine is in a second stage in which warm-up is advanced from the first stage. 3. Processing equipment. The exhaust treatment device according to claim 1, wherein the air pump is used as the suction force applying unit by rotating the air pump in a direction opposite to a direction in which the secondary air is supplied. 3. The exhaust treatment apparatus according to claim 1, wherein the suction force applying unit applies the negative pressure generated in an intake passage of the internal combustion engine to the holding unit to generate the suction force. 4. The suction means for applying a suction force causes the suction unit to pass a negative pressure of the intake passage to the holding unit when sucking the discharged matter into the holding unit. 5. The exhaust treatment device according to 4. The suction force applying unit stores the negative pressure of the intake passage in the holding unit through the intake passage and the holding unit when the internal combustion engine is stopped, and stores the negative pressure in the holding unit when the discharge is sucked into the holding unit. 5. The exhaust treatment device according to claim 4, wherein the negative pressure stored in the intake passage is made to act on the holding unit through a secondary air supply passage and the holding unit. 6. In an exhaust treatment device of an internal combustion engine capable of supplying secondary air to a position upstream of a catalyst in an exhaust passage from an air pump via a secondary air supply passage,
Holding means that is separated from the exhaust passage and is connected to the secondary air supply passage, and that can hold emissions from the internal combustion engine;
The rotation direction of the air pump is changed between a forward direction for supplying the secondary air to the secondary air supply passage and a reverse direction for generating a suction force toward the holding means in the secondary air supply passage. Control means for switching control;
An exhaust treatment device for an internal combustion engine, comprising: The control means rotates the air pump in the reverse direction when the state of the catalyst is in the first stage before the completion of warming up, and the control unit controls the state of the catalyst before the completion of warming up and warms up more than the first stage. The exhaust treatment device according to claim 7, wherein the air pump is rotated in the forward direction when the machine is in a second stage advanced. The secondary air supply passage is provided with a bypass passage, and the bypass passage includes the holding unit, and a first valve unit that is located closer to the air pump than the holding unit and opens and closes the bypass passage. A second valve means which is located on a side farther from the air pump than the holding means, allows a flow in a direction flowing into the holding means, and blocks a flow in a direction flowing out of the holding means, 9. The exhaust treatment apparatus according to claim 7, wherein a communication unit that connects the holding unit and a predetermined position other than the secondary air supply passage is further attached to the holding unit. 10. The exhaust treatment device according to claim 9, wherein the communication means is provided so as to communicate the holding means with an intake passage of the internal combustion engine. In an exhaust treatment device of an internal combustion engine capable of supplying secondary air to a position upstream of a catalyst in an exhaust passage from an air pump via a secondary air supply passage,
Holding means that is provided in an exhaust gas recirculation passage that is separated from the exhaust passage and that connects the secondary air supply passage and the intake passage of the internal combustion engine, and that can hold emissions from the internal combustion engine;
A first on-off valve provided between the secondary air supply passage of the exhaust gas recirculation passage and the holding means to open and close the exhaust gas recirculation passage;
A second on-off valve provided between the holding means of the exhaust gas recirculation passage and the intake passage to open and close the exhaust gas recirculation passage;
An exhaust treatment device for an internal combustion engine, comprising: When the state of the catalyst is at the first stage before the completion of warm-up, the air pump is stopped and the first and second on-off valves and the second on-off valve are opened to reduce the negative pressure of the intake passage to the holding means and the second Acting on the next air supply passage, when the state of the catalyst is in a second stage before the completion of warm-up and in a second stage in which warm-up is advanced from the first stage, the first on-off valve and the second on-off valve are closed and The exhaust processing apparatus according to claim 11, further comprising control means for rotating the air pump so that secondary air is supplied to the secondary air supply passage. When the internal combustion engine is stopped, the first opening / closing valve is closed, the second opening / closing valve is opened, and the negative pressure of the intake passage is taken into the holding means, and thereafter, the second opening / closing valve is closed to apply a negative pressure to the holding means. When the state of the catalyst is in the first stage before the completion of warm-up, the air pump is stopped and the first on-off valve is opened with the second on-off valve closed, and stored in the holding means. Applying the negative pressure to the secondary air supply passage, and when the state of the catalyst is in a second stage before warm-up completion and in a second stage in which warm-up is advanced from the first stage, the first on-off valve is opened. 12. The exhaust treatment device according to claim 11, further comprising a control unit configured to rotate the air pump so as to close and supply the secondary air to the secondary air supply passage. 14. The exhaust treatment device according to claim 1, wherein the holding unit includes an HC adsorbent. The exhaust treatment apparatus according to claim 14, further comprising heating means for the HC adsorbent. The exhaust treatment device according to claim 15, wherein the catalyst is used as the heating unit. The exhaust treatment device according to any one of claims 1 to 13, wherein the holding unit includes a tank for storing the discharged matter. The exhaust treatment device according to any one of claims 1 to 8, wherein the exhaust retained by the retaining unit is included in secondary air and supplied to the exhaust passage. The exhaust treatment apparatus according to any one of claims 1 to 17, wherein the waste held by the holding means is supplied to an intake passage.

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