JP5867151B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

In an exhaust gas purification apparatus that purifies exhaust gas from an internal combustion engine using a catalyst, it is important to accurately control the active state of the catalyst in order to improve exhaust gas purification performance.
For example, an exhaust emission control device has been proposed in which a catalyst device disposed in an exhaust flow path is heated with a heating wire so that the catalyst is activated at an early stage during a cold start (see Patent Document 1).
In addition, in order to reduce the frequency of manual regeneration of Diesel Particulate Filter (DPF: Diesel Particulate Filter), when the vehicle enters a stop idle state, exhaust throttle control is performed to increase the load on the internal combustion engine and Has been proposed (see Patent Document 2), which maintains the temperature at a high temperature and activates the catalyst.

In addition, an exhaust purification device has been proposed that includes a pre-three-way catalyst device, a main three-way catalyst device, a heating chamber for heating the main three-way catalyst, and an HC adsorption device (see Patent Document 3).
In this exhaust purification device, the exhaust flows in the order of the pre three-way catalyst device, the heating chamber, the HC adsorption device, and the main three-way catalyst device in accordance with the operating state of the internal combustion engine, and the exhaust is in the heating chamber and the HC adsorption. The active state of the pre three-way catalyst device and the main three-way catalyst device is controlled by switching to either the state where the main three-way catalyst device is bypassed and only the pre-three-way catalyst device is circulated. .

JP 2011-132870 A Japanese Patent No. 4175281 JP 2002-138823 A

By the way, the catalyst is activated when its temperature reaches the activation temperature. However, if the temperature of the catalyst is too high, the catalyst is deteriorated. Therefore, the temperature of the catalyst needs to be controlled within an appropriate temperature range.
In any of the exhaust gas purification devices described above, although the point of activating the catalyst early by promoting the temperature rise of the catalyst is considered, the temperature of the catalyst is increased when the catalyst is excessively heated. There is no particular consideration on how to suppress and set the temperature range.
Furthermore, as a means for activating the catalyst, a technique in which a heating device is provided in the catalyst itself is disclosed by the technique described above. However, since they do not consider heat dissipation from the catalyst, the heat of the catalyst escapes to the outside air. This is disadvantageous for the activation of the catalyst. Moreover, when a thing with fixed heat insulation performance is provided around the catalyst, the heat radiation amount is fixed, which is disadvantageous when it is desired to actively dissipate heat.
The present invention has been made in view of such circumstances, and an object thereof is to exhaust the internal combustion engine which is advantageous in maintaining the temperature of the catalyst within a predetermined temperature range while promoting the temperature rise of the catalyst. It is to provide a purification device.

In order to achieve the above object, an exhaust gas purification apparatus for an internal combustion engine according to the present invention includes an exhaust pipe through which exhaust gas discharged from the internal combustion engine flows, a catalyst for purifying exhaust gas discharged from the internal combustion engine, and the catalyst. The exhaust heat is recovered from the heat insulation means capable of suppressing the heat radiation amount, the heat insulation control means for controlling the heat insulation means so that the catalyst converges to a predetermined active state, and the exhaust gas passing through the catalyst or the catalyst. Exhaust heat recovery means and exhaust heat recovery amount control means for controlling the amount of exhaust heat recovery of the exhaust heat recovery means , wherein the heat insulation means passes a medium having a temperature higher than that of the exhaust gas flowing into the catalyst to the catalyst. Including a medium flow passage that circulates to the surroundings, wherein the heat insulation control means controls the amount of heat released from the catalyst by the heat insulation means by changing the flow rate of the medium, and the activation of the catalyst after the activation of the catalyst is completed. Maintain state As to the insulation control means suppresses the flow of the medium, the heat recovery amount control means and controls to increase the heat recovery amount.

According to the first aspect of the present invention, by providing the heat insulation means with variable heat insulation performance for the catalyst, the amount of heat released from the catalyst can be increased or decreased, so that the temperature rise of the catalyst can be efficiently promoted. At the same time, the amount of heat release can be increased, which is advantageous in maintaining the temperature of the catalyst within a predetermined temperature range.
In addition, after the catalyst activation is completed, the heat from the catalyst is recovered by the exhaust heat recovery means, and the amount of the medium circulation is suppressed, so that even if the catalyst cannot be controlled only by the heat insulation means, the catalyst is appropriately selected. This is advantageous for keeping the active state.
According to the invention described in claim 2, the heat insulation control means promotes the activation of the catalyst, and after the activation of the catalyst, controls the amount of heat released from the catalyst by the heat insulation means so as to maintain the active state of the catalyst. Therefore, it is advantageous in maintaining the temperature of the catalyst within a predetermined temperature range while promoting the activation of the catalyst. It is also advantageous for purifying the catalyst.
According to the third aspect of the present invention, the heat exhausted after passing through the catalyst is circulated around the catalyst, so that the heat of the exhaust is used for activating the catalyst, and the amount of heat released from the catalyst is reduced by suppressing the flow rate. Since it can be increased, it is advantageous in maintaining the catalyst in a defined temperature range while promoting the activation of the catalyst.
According to the invention described in claim 4, since the exhaust flow rate can be made variable with a simple configuration, it is advantageous for maintaining the temperature of the catalyst within a predetermined temperature range while promoting the activation of the catalyst. is there. Moreover, since the pressure in a catalyst can be raised by installing behind a catalyst, it becomes advantageous when increasing the purification amount of a catalyst.
According to the fifth aspect of the present invention, the medium flow passage is provided in contact with the outer periphery of the inner passage and the inner passage provided in contact with the outer periphery of the catalyst and the exhaust pipe and the inner passage. And the exhaust control valve is provided between the exhaust pipe and each communication port of the inner passage and the outer passage. Therefore, the exhaust gas flowing through the medium flow passage is discharged to the exhaust pipe, and the exhaust gas is combined into one. Since it can be aggregated, it is advantageous in treating exhaust gas. Further, not only the inner passage but also the outer passage functions as a heat insulating layer, which is advantageous in improving the performance of the heat insulating means.
According to the sixth aspect of the present invention, the exhaust heat recovery means promotes warm-up of the internal combustion engine, and the medium flow rate is controlled based on the warm-up state detected by the warm-up state detection means. Since the amount of heat released to the recovery means changes, it is advantageous for promoting warm-up of the internal combustion engine and suppressing the catalyst from being released from the active state.

It is a block diagram which shows the exhaust gas purification apparatus 22 of the internal combustion engine of this Embodiment. FIG. 3 is a first cross-sectional view illustrating the operation of the exhaust purification device 22. 6 is a second cross-sectional view illustrating the operation of the exhaust purification device 22. FIG. It is an operation | movement flowchart of the exhaust gas purification apparatus 22 of the internal combustion engine of this Embodiment. It is explanatory drawing which shows transition of the vehicle speed, catalyst temperature, and cooling water temperature at the time of mounting and operating the exhaust purification apparatus 22 in a vehicle.

Next, an exhaust emission control device for an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an engine 10 (internal combustion engine) to which an exhaust purification device 22 is applied includes a combustion chamber 12, a fuel injection device 14, an exhaust passage 16, a cooling device 18, an ECU 20 described later, and the like. ing.
The combustion chamber 12 forms a space where fuel is combusted.
The fuel injection device 14 injects fuel into the combustion chamber 12, and the fuel injection device 14 controls the fuel injection timing and the injection amount by the ECU 20.

  The exhaust passage 16 is constituted by an exhaust pipe 24 connected to the exhaust manifold 17, and exhausts exhausted by the combustion of fuel in the combustion chamber 12 to the outside of the vehicle and is discharged.

The cooling device 18 includes a cooling water circulation circuit configured to include any water jacket (not shown) and a radiator connected to the water jacket, and circulates the cooling water to the cooling water circulation circuit by a water pump.
The cooling water circulation circuit is connected to a medium flow path of the apparatus main body 34 described later.

  The exhaust purification device 22 includes a catalyst 26, a temperature management device 28, a medium temperature sensor 30, an exhaust temperature sensor 32, and the ECU 20.

The catalyst 26 is disposed in the exhaust passage 16 and purifies exhaust exhausted from the engine 10.
As the catalyst 26, various conventionally known catalysts such as an oxidation catalyst, a three-way catalyst, and a NOx storage catalyst can be used.

The temperature management device 28 makes the heat radiation amount of the catalyst 26 variable. As shown in FIGS. 1 and 2, the device main body 34, the exhaust control valve 36, the inflow pipe 38, the outflow pipe 40, And a medium control valve 42.
The apparatus main body 34 is interposed in the middle portion of the exhaust pipe 24 in the longitudinal direction.
The apparatus main body 34 includes first, second, and third cylindrical wall portions 44, 46, 48 that are coaxial with the exhaust pipe 24, and the cylindrical wall portions 44, 46, 48 extend along the longitudinal direction of the exhaust pipe 24. It is extended.
The first cylindrical wall portion 44 is provided with an inner diameter smaller than that of the exhaust pipe 24.
The first cylindrical wall portion 44 forms a storage chamber 45 in which exhaust gas can flow, and the catalyst 26 is stored in the storage chamber 45.
Of the first cylindrical wall portion 44, the opening on the upstream side of the exhaust flow is an introduction port 50 for introducing exhaust gas, and the opening on the downstream side of the exhaust flow is a first exhaust port 52 for discharging exhaust gas. ing.
A number of exhaust introduction holes 54 are formed through the entire circumference of the first cylindrical wall portion 44 in the vicinity of the first discharge port 52.
The exhaust control valve 36 is provided so as to open and close the first discharge port 52 under the control of the ECU 20. The exhaust control valve 36 is provided on the downstream side of the catalyst 26 and controls the flow rate of exhaust gas that passes through the catalyst 26, and controls the flow rate of exhaust gas that flows into a first medium flow passage 64 described later. .

The second cylindrical wall portion 46 is provided on the outer side in the radial direction of the first cylindrical wall portion 44 at a distance from the first cylindrical wall portion 44. An inner annular space S <b> 1 is formed between the inner peripheral surface of the cylindrical wall portion 46.
An end of the second cylindrical wall portion 46 on the first discharge port 52 side in the longitudinal direction is connected to the first cylindrical wall portion 44 by an end surface wall 54.

The third cylindrical wall portion 48 is provided on the outer side in the radial direction of the second cylindrical wall portion 46 at a distance from the second cylindrical wall portion 46. An outer annular space S <b> 2 is formed between the inner peripheral surface of the cylindrical wall portion 48.
The end portion of the third cylindrical wall portion 48 located on the upstream side of the exhaust flow is connected to the exhaust pipe 24 and is connected to the end portion of the first cylindrical wall portion 44 through the end face wall 56. .
A space S3 is secured between the end face wall 56 and the end of the second cylindrical wall portion 46 located on the upstream side of the exhaust flow. The space S3 allows the inner annular space S1 and the outer annular space S2 to be separated from each other. Are communicating.
Further, the end portion of the third cylindrical wall portion 48 located on the downstream side of the exhaust flow is connected to the exhaust pipe 24, and the end portion of the third cylindrical wall portion 48 is connected to the downstream side of the exhaust flow. An annular space S4 is secured between the end of the second cylindrical wall portion 46 and the annular space S4 serves as a second discharge port 58.
In the present embodiment, the first cylindrical portion 44, the second cylindrical portion 46, the third cylindrical portion 48, and the exhaust control valve 36 function as heat insulating means in the claims.

Therefore, when the exhaust control valve 36 closes the first discharge port 52, as shown in FIG. 4, the exhaust after passing through the catalyst 26 passes through the exhaust introduction hole 54 into the inner annular space S1, the space S3, and the outer annular space S2. An exhaust flow passage 60 extending from the second exhaust port 58 to the exhaust pipe 24 is formed.
In this case, the exhaust gas after passing through the catalyst 26 stays in the exhaust flow passage 60 due to the resistance of the exhaust flow passage 60, and the exhaust pressure in the apparatus main body 34 is maintained at about 1 to 2 atm. . Thereby, the temperature rise of the catalyst 26 is promoted.
Further, the exhaust gas after passing through the catalyst 26 has a temperature higher than the temperature of the exhaust gas flowing into the catalyst 26 due to the reaction heat when purified in the catalyst 26.
Further, when the exhaust control valve 36 opens the first discharge port 52, as shown in FIG. 3, the exhaust after passing through the catalyst 26 hardly flows into the exhaust flow passage 60 having a large resistance. It flows from the discharge port 52 to the exhaust pipe 24 on the downstream side.
A first medium flow passage 64 through which exhaust gas after passing through the catalyst 26 circulates is provided outside the storage chamber 62. In other words, the first medium flow path 64 functions as a medium flow path for allowing exhaust, which is a medium higher than the temperature of the exhaust flowing into the catalyst 26, to flow around the catalyst 26.
In the present embodiment, the first medium flow passage 64 is in contact with the inner passage (inner annular space S1) provided in contact with the entire outer area of the storage chamber 62, and in contact with the entire outer area of the inner passage. It includes an outer passage (outer annular space S2) provided.
More specifically, the first medium flow passage 64 communicates with the storage chamber 62 and is provided with an inner passage (inner annular space S 1) provided in contact with the entire length of the storage chamber 62 and the entire outer side of the storage chamber 62. ) And an outer passage (outer annular space S2) provided in communication with the inner passage and in contact with the entire length of the inner passage and the entire outer side of the inner passage.
That is, the first medium flow passage 64 communicates with the exhaust pipe 24 and communicates with the inner passage (inner annular space S1) provided in contact with the outer periphery of the catalyst 26, the exhaust pipe 24, and the inner passage. And an outer passage (outer annular space S2) provided in contact with the outer periphery. The exhaust control valve 36 is provided between the communication ports of the exhaust pipe 24 and the inner and outer passages.

Further, inside the first, second, and third cylindrical wall portions 44, 46, and 48, a medium flow passage for cooling water (not shown) that circulates the cooling water around the catalyst 26 is formed, and the exhaust circulation The cooling water flowing through the medium flow passage can be heated by the heat of the exhaust gas flowing through the passage 60.
In the present embodiment, the medium flow passage for cooling water is provided outside the storage chamber 62 and constitutes a second medium flow passage through which the cooling water that exchanges heat with the engine 10 flows.

One end of the inflow pipe 38 is connected to the upstream side of the cooling water circulation circuit of the cooling device 18, the other end is connected to one end of the medium flow path, and the outflow pipe 40 has one end of the cooling water circulation circuit of the cooling device 18. Connected to the downstream side, the other end is connected to the other end of the medium flow path.
Thereby, the medium flow path is connected in parallel with the flow path constituting the cooling water circulation circuit.
Therefore, the cooling water can be circulated through the cooling device 18 and the medium flow path.

  The medium control valve 42 is provided in the inflow pipe 38 and is opened and closed under the control of the ECU 20 to control the flow rate of the cooling water circulating through the cooling device 18 and the cooling water medium flow path. In the present embodiment, the medium control valve 42 corresponds to exhaust heat recovery amount control means in the claims.

In the present embodiment, the temperature management device 28 circulates exhaust as a medium to suppress or promote heat release from the catalyst 26 to make the heat insulation performance with respect to the catalyst 26 variable, that is, the amount of heat released from the catalyst 26. And heat exhaust means for recovering heat from the exhaust gas passing through the catalyst 26 or the catalyst 26.
The heat insulating means is configured to include the accommodation chamber 62.
That is, the exhaust gas flows through the catalyst 26 stored in the storage chamber 62, whereby the catalyst 26 is heated.
That is, when exhaust gas as a medium is circulated through the first medium flow path 64, the exhaust gas flowing through the first medium flow path 64 covers the outside of the catalyst 26, and thus heat radiation from the catalyst 26 to the outside is suppressed. .
At this time, it can be considered that the exhaust gas flowing through the first medium flow passage 64 functions as a heat insulating layer covering the outside of the catalyst 26. Further, it can be considered that the function of the heat insulating layer covering the outside of the catalyst 26 is lowered in a state where the exhaust gas does not flow through the first medium flow path 64.
Therefore, the heat insulation performance of the heat insulation means is varied depending on the flow rate of the exhaust gas flowing through the first medium flow passage 64.
Further, when the cooling water as the medium is circulated through the second medium flow path, the cooling water flowing through the second medium flow path covers the outside of the catalyst 26, so that the cooling water and the exhaust or the cooling water and the catalyst 26 Heat exchange is performed between the catalyst 26 and the heat release from the catalyst 26 to the outside is promoted.
At this time, it can be considered that the cooling water flowing through the second medium flow path functions as exhaust heat recovery means for recovering the heat of the catalyst 26. Further, in the state where the cooling water does not flow through the second medium flow passage, the heat recovery from the catalyst 26 is suppressed, so that the function of raising the temperature of the catalyst can be improved.
Therefore, the amount of heat recovered from the catalyst 26 can be varied depending on the flow rate of the cooling water flowing through the second medium flow passage.

In the present embodiment, the case where the cooling water of the engine 10 is directly heated by exhaust heat after passing through the catalyst 26 by connecting the cooling device 18 and the medium flow path has been described.
However, a heat exchange device is interposed between the cooling device 18 and the medium flow passage, and the cooling water is circulated between the cooling device 18 and the heat exchange device, so that the heat exchange device is interposed between the heat exchange device and the medium flow passage. A heat exchange medium that exchanges heat with cooling water may be circulated. In this case, the cooling water of the engine 10 is heated through the heat exchange medium due to exhaust heat of the exhaust gas after passing through the catalyst 26. Moreover, conventionally well-known liquids, such as water and oil, can be used as a heat exchange medium.
In other words, the cooling water of the engine 10 and the heat exchange medium such as water and oil are all heat exchange media that exchange heat with the engine 10.

The medium temperature sensor 30 detects the temperature of the cooling water in the cooling water circulation circuit as the medium temperature Tw, and supplies the detected medium temperature Tw to the ECU 20.
The exhaust temperature sensor 32 detects the temperature of the exhaust discharged from the engine 10 as the exhaust temperature Tg, and supplies the detected exhaust temperature Tg to the ECU 20. In the present embodiment, the exhaust temperature sensor 32 detects the exhaust temperature upstream of the catalyst 26.

The ECU 20 is an electronic control unit that controls the engine 10.
The ECU 20 is constituted by a microcomputer in which a CPU, a ROM that stores a control program, a RAM that provides a working area, an interface unit that interfaces with peripheral circuits, and the like are connected by a bus. The CPU functions by executing a control program.
In the present embodiment, the medium temperature sensor 30 and the exhaust temperature sensor 32 are connected to the input side of the ECU 20, and the exhaust control valve 36 and the medium control valve 42 are connected to the output side of the ECU 20.
The ECU 20 controls the exhaust control valve 36 and the medium control valve 42 based on detection information from the medium temperature sensor 30 and the exhaust temperature sensor 32 by the CPU executing the control program.

The ECU 20 functions as a warm-up state detection unit, a catalyst activation state detection unit, and a control unit when the CPU executes the control program.
The warm-up state detection means detects the warm-up state of the engine 10. In this embodiment, the warm-up state detection unit detects the warm-up state of the engine 10 based on the medium temperature Tw detected by the medium temperature sensor 30.
The catalyst active state detecting means detects the active state of the catalyst 26, and in this embodiment, the temperature of the catalyst 26 is estimated based on the exhaust gas temperature Tg detected by the exhaust gas temperature sensor 32 and estimated. The active state of the catalyst 26 is detected based on the catalyst temperature.
The control means controls the flow rate of exhaust and cooling water as a medium based on the active state detected by the catalyst active state detection means. The control means includes the exhaust control valve 36 and the medium control valve 42. It is comprised including.
The control means functions as an adiabatic control means for controlling the adiabatic means so that the catalyst 26 converges to a predetermined active state. In other words, the adiabatic control means is configured to include the exhaust control valve 36, and the adiabatic control means changes the flow rate of the medium (exhaust gas) flowing into the first medium flow passage 64 by the exhaust control valve 36, whereby the catalyst by the adiabatic means is used. The amount of heat released from 26 is controlled.

Next, the operation of the exhaust emission control device 22 will be described with reference to the flowchart shown in FIG.
First, the first warm-up determination temperature TA, the second warm-up determination temperature TB, and the catalyst activation temperature will be described.
The first warm-up determination temperature TA is defined as the medium temperature Tw when the engine 10 has been warmed up.
The second warm-up determination temperature TB is defined as the medium temperature Tw when the engine 10 is not warmed up but is in a predetermined reference warm-up state. Therefore, a relationship of TA> TB is established.
The second warm-up determination temperature TB is, for example, the medium temperature Tw when the purification amount becomes X / 2 when the purification amount of the exhaust gas purified by the catalyst 26 in the warm-up completion state of the engine 10 is X. Can be prescribed.
The catalyst activity determination temperature TC is defined as a catalyst temperature at which the catalyst 26 is activated and can effectively exhibit the exhaust purification function.

The process of FIG. 4 is performed when the engine 10 is started.
First, the ECU 20 determines whether or not the medium temperature Tw detected by the medium temperature sensor 30 is higher than the first warm-up determination temperature TA (step S10: warm-up state detection means). That is, it is determined whether or not the engine 10 has been warmed up.
If the determination result in step S10 is negative, the ECU 20 estimates the temperature of the catalyst 26 based on the exhaust temperature Tg detected by the exhaust temperature sensor 32, and whether or not the estimated catalyst temperature is equal to or higher than the catalyst activation temperature. Whether or not the catalyst 26 is activated is determined based on whether or not (step S12: catalyst state detecting means).
If the determination result of step S12 is negative, the ECU 20 closes the exhaust control valve 36 and closes the medium control valve 42 (step S14).
By closing the exhaust control valve 36, as shown in FIG. 2, the exhaust discharged from the engine 10 stays in the exhaust flow passage 60 of the apparatus main body 34, so that the temperature of the catalyst 26 is increased. .
Further, by closing the medium control valve 42, the flow of the cooling water in the medium flow passage of the apparatus main body 34 is stopped, and the operation of raising the temperature of the cooling water due to the exhaust heat of exhaust after passing through the catalyst 26 is stopped. Is further promoted.
In other words, by performing the operation for raising the temperature of the catalyst 26 in preference to the operation for raising the temperature of the cooling water, the temperature of the catalyst 26 is given priority over the warming up of the engine 10.
In this case, since the exhaust gas flowing through the first medium flow path 64 covers the outside of the catalyst 26, heat radiation from the catalyst 26 to the outside is suppressed, and cooling water does not flow through the second medium flow path. The heat exchange between the heat of the exhaust gas flowing through the first medium flow path 64 and the cooling water in the second medium flow path, or the heat exchange between the catalyst 26 and the cooling water in the second medium flow path is suppressed. It becomes a state.
That is, since the catalyst 26 is heated by the heat of the exhaust gas in a state where the heat insulating performance of the heat insulating means with respect to the catalyst 26 is changed in a direction to enhance the heat insulating property, the catalyst 26 can be activated at an early stage, and the exhaust gas purification device 22 purifies the exhaust gas. This is advantageous for improving performance.
If step S14 is performed, it will return to step S10.

If the determination result in step S12 is affirmative, the ECU 20 determines whether or not the medium temperature Tw detected by the medium temperature sensor 30 is higher than the second warm-up determination temperature TB (step S16: warm-up state detection). means). That is, it is determined whether or not the engine 10 is warmed up moderately.
If the determination result of step S16 is negative, the ECU 20 maintains the exhaust control valve 36 closed and opens the medium control valve 42 (step S18).
When the medium control valve 42 is opened, the cooling water is circulated in the second medium flow path, and the exhaust control valve 36 is closed, so that the temperature of the cooling water is increased by exhaust heat of exhaust after passing through the catalyst 26. The action is executed.
That is, at the stage where the activation of the catalyst 26 is completed, warming up of the engine 10 is promoted while maintaining the temperature raising operation of the catalyst 26.
In other words, steps S16 and S18 are performed when it is determined that the catalyst 26 has been activated and the engine 10 has not been warmed up and has not reached a predetermined reference warm-up state. This corresponds to simultaneously executing the operation of raising the temperature of water and the operation of raising the temperature of the catalyst 28.
In other words, in steps S16 and S18, the operation of raising the temperature of the cooling water and the operation of raising the temperature of the catalyst 28 when it is determined that the catalyst 26 is activated and the engine 10 has not been warmed up. Is equivalent to simultaneously executing.
This is advantageous in shortening the warm-up time and improving fuel consumption.
If step S18 is performed, it will return to step S16.
In this case, the exhaust gas flowing through the first medium flow path 64 covers the outside of the catalyst 26 in the same manner as described above, so that heat radiation from the catalyst 26 to the outside is suppressed, while the second medium flow path has cooling water Therefore, heat exchange between the heat of the exhaust gas flowing through the first medium flow passage 64 and the cooling water of the second medium flow passage, or the heat of the catalyst 26 and the cooling water of the second medium flow passage. The exchange is promoted.
Accordingly, the processes in steps S12, S16, and S18 determine that the activation of the catalyst 26 has been completed, and that the engine 10 has not been warmed up and has not reached a predetermined reference warm-up state. In this case, the exhaust heat recovery control means controls to increase the exhaust heat recovery amount, and the heat insulation control means increases the flow of the medium (exhaust gas) in the first medium flow path 64 to thereby release the heat released from the catalyst 26. It is equivalent to restraining.

If the determination result in step S16 is affirmative, the ECU 20 maintains the state in which the medium control valve 42 is opened, and opens the exhaust control valve 36 (step S20).
When the exhaust control valve 36 is opened, the exhaust gas that has passed through the catalyst 26 is discharged from the first discharge port 52 to the downstream exhaust pipe 24 as shown in FIG. The atmospheric pressure is restored, and the rotation of the engine 10 is maintained smoothly.
That is, while maintaining the rotation of the engine 10 smoothly, the temperature raising operation of the catalyst 26 and the warming up of the engine 10 are promoted.
In other words, in steps S16 and S20, when it is determined that the catalyst 28 is activated and has reached the standard warm-up state, the operation of raising the temperature of the catalyst 28 is stopped and the temperature of the cooling water is raised. This corresponds to executing the operation.
In other words, steps S16 and S20 correspond to executing only the operation of raising the temperature of the cooling water when it is determined that the catalyst 26 is activated and the engine 10 has not been warmed up. .
This is advantageous in shortening the warm-up time and improving fuel consumption.
If step S20 is performed, it will return to step S10.
In this case, the flow of the exhaust gas to the first medium flow passage 64 is stopped, and the state where the exhaust covers the outside of the catalyst 26 is released. Therefore, heat radiation from the catalyst 26 to the outside is promoted, and the second medium Since the cooling water flows through the flow passage, heat exchange between the catalyst 26 and the cooling water in the second medium flow passage is promoted.
Accordingly, in the processes of steps S12, S16, and S20, when it is determined that the catalyst 26 is activated and has reached the standard warm-up state, the exhaust heat recovery control means increases the exhaust heat recovery amount, This corresponds to increasing the amount of heat released from the catalyst 26 by suppressing the flow of the medium (exhaust gas) in the first medium flow passage 64 by the heat insulation control means.
That is, the adiabatic control means suppresses the flow of the medium (exhaust gas) in the first medium flow passage 64 and maintains the exhaust heat recovery amount control means so that the active state of the catalyst 26 is maintained after the activation of the catalyst 26 is completed. Controls to increase the amount of exhaust heat recovery.

If the determination result in step S10 is affirmative, warm-up of the engine 10 is complete, and the ECU 20 closes the medium control valve 42 while maintaining the exhaust control valve 36 open (step S22).
That is, since the warm-up of the engine 10 has been completed, the promotion of warm-up is stopped, the normal operation is performed, and the series of processes is terminated.
In other words, steps S10 and S22 include an operation of raising the temperature of the catalyst 28 and an operation of raising the temperature of the cooling water when it is determined that the catalyst 26 is activated and the engine 10 has been warmed up. This is equivalent to stopping both.
Further, in the processing of steps S12, S14, S16, S18, and S20, the heat insulation control means promotes the activation of the catalyst 26, and maintains the activated state of the catalyst 26 after the activation of the catalyst 26 is completed. This corresponds to controlling the amount of heat released from the catalyst 26 by the heat insulating means.

As described above, in the present embodiment, the control unit maintains the activated state of the catalyst 26 based on the active state of the catalyst 26 detected by the catalyst active state detecting unit, and excessively increases the catalyst 26. The exhaust control valve 36 and the medium control valve 42 are controlled so as to suppress the temperature.
The control means controls the exhaust control valve 36 and the medium control valve 42 so as to promote warm-up of the engine 10 based on the warm-up state detected by the warm-up state detection means after the catalyst 26 is activated. doing.

FIG. 5 is a diagram showing changes in vehicle speed, catalyst temperature, and cooling water temperature when a vehicle equipped with the exhaust purification device 22 is run.
Both the exhaust control valve 36 and the medium control valve 42 are closed until the catalyst temperature reaches the catalyst activity determination temperature TC.
When the catalyst temperature reaches the catalyst activity determination temperature TC, the exhaust control valve 36 is maintained closed and the medium control valve 42 is opened.
When the cooling water temperature reaches the second warm-up determination temperature TB, the exhaust control valve 36 is opened and the medium control valve 42 is kept open.
When the cooling water temperature reaches the first warm-up determination temperature TA, the exhaust control valve 36 is kept open, and the medium control valve 42 is closed.

  According to the present embodiment, the amount of heat released from the catalyst 26 can be increased or decreased by providing the heat insulating means that makes the heat insulating performance variable with respect to the catalyst 26 by circulating the medium (exhaust gas). The temperature increase of the catalyst 26 can be promoted and the amount of heat released can be increased, which is advantageous in maintaining the temperature of the catalyst 26 within a predetermined temperature range.

  Further, according to the present embodiment, the adiabatic control means promotes the activation of the catalyst 26 and, after the activation of the catalyst 26, maintains the active state of the catalyst 26 from the catalyst 26 by the adiabatic means. Since the amount of heat release is controlled, it is advantageous for maintaining the temperature of the catalyst 26 within a predetermined temperature range while promoting the activation of the catalyst 26. Further, it is advantageous for purifying the catalyst 26.

  Further, according to the present embodiment, the exhaust after passing through the catalyst 26 is circulated around the catalyst 26, so that the heat of the exhaust is used for activating the catalyst 26, and the circulation amount is suppressed, thereby Therefore, it is advantageous in maintaining the catalyst 26 in a predetermined temperature range while promoting the activation of the catalyst 26.

  Further, according to the present embodiment, the exhaust control valve 36 for controlling the flow rate of the exhaust gas flowing into the first medium flow passage 64 is provided on the downstream side of the catalyst 26 in the exhaust flow, so that the configuration is simple. Since the exhaust gas flow rate can be made variable, it is advantageous for maintaining the temperature of the catalyst 26 within a predetermined temperature range while promoting the activation of the catalyst 26. Moreover, since the pressure in the catalyst 26 can be increased by installing it behind the catalyst 26, it is advantageous in increasing the purification amount of the catalyst 26.

In addition, according to the present embodiment, the first medium flow passage 64 communicates with the exhaust pipe 24 and is connected to the outer periphery of the catalyst 26 (inner annular space S1), the exhaust pipe 24, And an outer passage (outer annular space S2) provided in communication with the inner passage and in contact with the outer periphery of the inner passage. The exhaust control valve 36 is provided between the exhaust pipe 24 and each communication port of the inner passage and the outer passage. Is provided.
Therefore, the exhaust gas flowing through the first medium flow passage 64 is discharged to the exhaust pipe 24, and the exhaust gas can be integrated into one, which is advantageous in processing the exhaust gas. Further, not only the inner passage but also the outer passage functions as a heat insulating layer, which is advantageous in improving the performance of the heat insulating means.

  Further, according to the present embodiment, after the activation of the catalyst 26 is completed, the heat from the catalyst 26 is recovered by the exhaust heat recovery means, and the circulation amount of the exhaust gas flowing through the first medium flow path 64 is suppressed. Even when the catalyst 26 cannot be controlled only by the heat insulating means, it is advantageous to keep the catalyst 26 in an appropriate active state.

  Further, according to the present embodiment, the exhaust heat recovery means promotes the warm-up of the engine 10, and the exhaust gas flowing through the first medium flow passage 64 based on the warm-up state detected by the warm-up state detection means. By controlling the flow rate, the amount of heat released to the exhaust heat recovery means changes, which is advantageous in promoting warm-up of the engine 10 and suppressing the catalyst 26 from coming out of the active state.

  Further, according to the present embodiment, the temperature management device 28 as the heat insulating means includes the first medium flow passage 64 provided outside the storage chamber 62 through which the exhaust gas after passing through the catalyst flows, and the catalyst passes as the medium. Since the later exhaust is used, the temperature control of the catalyst can be appropriately performed with a simple configuration.

In addition, according to the present embodiment, the first medium flow passage 64 includes the inner passage (inner annular space S1) provided in contact with the entire outer area of the storage chamber 62, and the outer side of the inner passage communicating with the inner passage. And an outer passage (outer annular space S2) provided in contact with the entire region.
Accordingly, the inner passage (inner annular space S1) and the outer passage (outer annular space S2) function as two heat insulation layers, which is advantageous in securing the heat insulation performance of the heat insulation means.

  In addition, according to the present embodiment, the temperature management device 28 as the exhaust heat recovery means is provided outside the storage chamber 62 and the second water through which cooling water (heat exchange medium) that exchanges heat with the engine 10 circulates. Since the medium flow path is further provided and the cooling water (heat exchange medium) is used as the medium, it is advantageous in promoting warm-up of the engine 10.

  Further, according to the present embodiment, since the medium control valve 42 that controls the flow rate of the cooling water (heat exchange medium) is configured, the amount of exhaust heat recovery can be varied with a simple configuration. .

  Further, according to the present embodiment, the exhaust control valve is configured to suppress excessive temperature rise of the catalyst 26 while maintaining the activated state of the catalyst 26 based on the activated state detected by the catalyst activated state detecting means. 36 and the medium control valve 42 are controlled, so that it is more advantageous to maintain the temperature of the catalyst 26 within a predetermined temperature range while promoting the temperature rise of the catalyst 26.

  Further, according to the present embodiment, after the catalyst 26 is activated, the exhaust control valve 36 and the medium control are performed so as to promote the warm-up of the engine 10 based on the warm-up state detected by the warm-up state detecting means. Since the valve 42 is controlled, it is advantageous in promoting warm-up of the engine 10.

In the present embodiment, the heat of the exhaust recovered by the cooling water flowing through the second medium flow passage is used to raise the temperature of the cooling water of the engine 10, but other fluids such as lubricating oil and air are used. The temperature may be raised, or the heat energy may be recovered by converting it into other energy such as electric energy, and is not limited.
Moreover, in this Embodiment, although the engine 10 is a gasoline engine, the engine 10 may be a diesel engine and it is not limited.
Further, in the present embodiment, the medium having a temperature higher than the temperature flowing into the catalyst is the exhaust after passing through the catalyst. However, other fluids such as overheated air and lubricating oil may be used and are limited. is not.
In the present embodiment, the heat insulation control means includes the exhaust control valve. However, the heat insulation control means is not limited to this as long as it is suitable for the medium control means. For example, when the medium is lubricating oil, an oil pump or the like can be applied as the adiabatic control means.
Further, in the present embodiment, the medium flow path is two, that is, the inner path and the outer path, but it may be one or three or more and is not limited.
Further, in the present embodiment, it is described that the inner passage is in contact with the entire outside region of the catalyst, but the contacting portion may be a part thereof and is not limited.
In the present embodiment, it has been described that the outer passage is in contact with the entire outer periphery of the inner passage. However, the contact portion may be a part thereof and is not limited.
Further, in the present embodiment, the exhaust gas after passing through the catalyst is configured to flow first through the inner passage and then to the outer passage, but may be configured such that the exhaust gas first passes through the outer passage and then passes through the inner passage. Is not to be done.
Further, in the present embodiment, the temperature management device 28 as the heat insulating means includes both the first medium flow path 64 through which the exhaust flows and the second medium flow path through which the cooling water flows. Only the first medium flow path 64 may be used, and is not limited. In this case, the heat insulation performance can be made variable by controlling the flow rate of the medium having a temperature higher than the temperature of the exhaust gas flowing into the catalyst 26.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Combustion chamber, 14 ... Fuel injection device, 16 ... Exhaust flow path, 18 ... Cooling device, 20 ... ECU (warm-up state detection means, active state detection means, adiabatic control means ), 22 ... Exhaust gas purification device, 24 ... Exhaust pipe, 26 ... Catalyst, 28 ... Temperature management device (heat insulation means, exhaust heat recovery means), 30 ... Medium temperature sensor, 32 ... Exhaust temperature sensor, 36 …… Exhaust control valve (heat insulation means, heat insulation control means), 42 …… Medium control valve (exhaust heat recovery amount control means), 60 …… Medium flow path, 62 …… Accommodating chamber, 64 …… First medium Flow passage (medium flow passage, heat insulating means), S1... Inner annular space (inner passage), S2... Outer annular space (outer passage).

Claims (6)

An exhaust pipe through which the exhaust discharged from the internal combustion engine flows;
A catalyst for purifying exhaust gas discharged from the internal combustion engine;
Heat insulating means capable of suppressing the amount of heat released from the catalyst;
Heat insulation control means for controlling the heat insulation means so that the catalyst converges to a predetermined active state;
Exhaust heat recovery means for recovering exhaust heat from the catalyst or exhaust gas passing through the catalyst;
An exhaust heat recovery amount control means for controlling the exhaust heat recovery amount of the exhaust heat recovery means;
With
The heat insulating means includes a medium flow passage for circulating a medium having a temperature higher than the temperature of the exhaust gas flowing into the catalyst around the catalyst,
The heat insulation control means controls the amount of heat released from the catalyst by the heat insulation means by changing the flow rate of the medium ,
The adiabatic control means controls the flow of the medium and the exhaust heat recovery amount control means controls to increase the exhaust heat recovery amount so as to maintain the active state of the catalyst after the activation of the catalyst is completed. An exhaust emission control device for an internal combustion engine. The adiabatic control means promotes the activation of the catalyst, and controls the amount of heat released from the catalyst by the adiabatic means so as to maintain the active state of the catalyst after the activation of the catalyst is completed.
The exhaust emission control device for an internal combustion engine according to claim 1. The medium is the exhaust after passing through the catalyst;
The exhaust emission control device for an internal combustion engine according to claim 1 or 2. The adiabatic control means includes an exhaust control valve that is provided on the downstream side of the catalyst in the exhaust flow and controls the flow rate of the exhaust gas flowing into the medium flow passage.
The exhaust gas purification apparatus for an internal combustion engine according to claim 3. A first cylindrical wall portion extending so as to connect the exhaust pipe to a middle portion in the extending direction of the exhaust pipe, and a second cylindrical wall provided radially outside the first cylindrical wall portion A cylindrical wall portion, and a third cylindrical wall portion provided radially outside the second cylindrical wall portion,
Both ends in the longitudinal direction of the inner space of the first cylindrical wall portion communicate with the exhaust pipe, and the catalyst is accommodated in the inner space,
A space between the first cylindrical wall portion and the second cylindrical wall portion is formed as an inner passage,
A space between the second cylindrical wall portion and the third cylindrical wall portion is formed as an outer passage,
An exhaust introduction hole that guides the exhaust flowing in the inner space to the inner passage on the downstream side of the exhaust flowing in the inner space;
A communication port that guides the exhaust introduced into the inner passage to the outer passage is provided at a location of the inner passage located on the upstream side of the exhaust flowing through the inner space,
A discharge port for discharging the exhaust gas introduced into the outer passage from the outer passage to the exhaust pipe is provided at a location of the outer passage located on the downstream side of the exhaust gas flowing through the inner space,
The exhaust control valve is provided to be able to open and close an end of the inner space on the downstream side of the exhaust flowing through the inner space.
The exhaust gas purification apparatus for an internal combustion engine according to claim 4, wherein the exhaust gas purification apparatus is an internal combustion engine. A warm-up state detecting means for detecting a warm-up state of the internal combustion engine;
The exhaust heat recovery means promotes warm-up of the internal combustion engine by exhaust heat recovery,
When it is determined that the activation of the catalyst has been completed and the internal combustion engine has not been warmed up and has not reached a predetermined warm-up state, the exhaust heat recovery amount control means Is controlled to increase the amount of exhaust heat recovery, and the heat insulation control means increases the flow of the medium to suppress the amount of heat released from the catalyst,
When it is determined that the catalyst has been activated and has reached the reference warm-up state, the exhaust heat recovery amount is increased by the exhaust heat recovery control unit, and the flow of the medium is reduced by the adiabatic control unit. Suppress and increase the amount of heat released from the catalyst,
The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 5, wherein

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