JP2013170533A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine, the device advantageous for improving exhaust emission control performance.SOLUTION: A warm-up state detecting means detects a warm-up state of an engine 10 and detects a warm-up state of the engine 10 on the basis of a medium temperature Tw detected through a medium temperature sensor 30. A catalytic activity state detecting means detects an active state of a catalyst 26, and the means estimates a temperature of the catalyst 26 on the basis of an exhaust temperature Tg detected through an exhaust temperature sensor 32, and detects the activity state of the catalyst 26 on the basis of the estimated catalyst temperature. A control means controls an opening/closing action of an exhaust control valve 36 and a medium control valve 42 on the basis of the activity state detected by the catalytic activity state detecting means and on the warm-up state detected by the warm-up state detecting means.

Description

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

From the viewpoint of effectively using exhaust heat from an exhaust gas of an internal combustion engine mounted on a vehicle, as an exhaust gas purification device for purifying exhaust gas of the internal combustion engine, the catalyst device arranged in the exhaust passage is heated with a heating wire, and the catalyst device Has been proposed in which exhaust heat of exhaust gas is recovered by providing a heating device that heats liquid (cooling water of an internal combustion engine) by exhaust gas on the outer peripheral side of the exhaust gas (see Patent Document 1).
In this exhaust purification device, the exhaust water is introduced to the outer peripheral side of the catalyst device by closing the exhaust opening / closing mechanism provided on the downstream side of the catalyst device, so that the cooling water is heated more efficiently.

  In addition, although the purpose of recovering exhaust heat is different from the purpose of recovering exhaust heat, the vehicle is running while the temperature of exhaust is being increased by multi-injection in order to reduce the frequency of manual regeneration of a diesel particulate filter (DPF: Diesel Particulate Filter). There has been proposed a system in which the exhaust throttle control is performed to increase the load on the internal combustion engine and maintain the exhaust at a high temperature when the vehicle is in a stationary idle state (see Patent Document 2).

JP 2011-132870 A Japanese Patent No. 4175281

By the way, since the exhaust heat recovery means and the catalyst temperature raising means are usually arranged in the same exhaust system, there is a certain influence regardless of the distance. Further, when the exhaust heat recovery means and the catalyst temperature raising means are arranged in the vicinity or integrally formed, the influence is great. In other words, the exhaust heat recovery and the catalyst temperature rise have a certain influence on each other, and it is difficult to control them both at the same time.
For example, in the exhaust purification apparatus, the exhaust heat recovery means and the catalyst temperature raising means are integrally formed. However, since the exhaust heat recovery means is not controlled and always recovers exhaust heat, the exhaust heat recovery means actively recovers exhaust heat even when activation of the catalyst is necessary. Therefore, if it is desired to activate the catalyst at an early stage, heat is recovered from the catalyst, which is disadvantageous.
That is, it is necessary to precisely control the exhaust heat recovery and the catalyst temperature rise according to the exhaust gas state.
By the way, when the exhaust gas purification efficiency is poor, it is more advantageous for exhaust gas purification by preferentially controlling which one of the warm-up of the internal combustion engine or the temperature rise of the catalyst has the better exhaust gas purification rate. Control.
For example, when it is desired to quickly raise the catalyst temperature immediately after starting the internal combustion engine and promote exhaust gas purification, it is important to prioritize the catalyst temperature rise and control the exhaust gas to be purified early. is there.
However, the former prior art described above merely recovers exhaust heat from the exhaust gas, and is disadvantageous for raising the temperature of the catalyst. Further, the latter prior art is limited to maintaining the exhaust temperature at a high temperature, and no particular consideration is given to achieving both warm-up of the internal combustion engine and activation of the catalyst.
The present invention has been made in view of such circumstances, and an object thereof is to provide an exhaust purification device for an internal combustion engine that is advantageous in improving exhaust gas purification performance.

  In order to achieve the above object, an exhaust gas purification apparatus for an internal combustion engine according to the present invention recovers exhaust heat of the exhaust gas from the internal combustion engine, a catalyst for purifying exhaust gas discharged from the internal combustion engine, and warms up the internal combustion engine. Exhaust heat recovery means for promoting the catalyst, catalyst temperature raising means for raising the temperature of the catalyst, catalyst active state detection means for detecting the active state of the catalyst, and warm-up state detection for detecting the warm-up state of the internal combustion engine And controlling the catalyst temperature raising means and the exhaust heat recovery means based on the active state detected by the catalyst active state detecting means and the warm-up state detected by the warm-up state detecting means And a control means.

According to the first aspect of the invention, in the exhaust gas purification apparatus for an internal combustion engine that controls the catalyst temperature raising means and the exhaust heat recovery means based on both the active state of the catalyst and the warm-up state of the internal combustion engine, the exhaust gas purification apparatus The catalyst temperature raising means and the exhaust heat recovery means are appropriately controlled so that the heat is recovered, and when the catalyst is activated by the catalyst temperature raising means, the heat recovery from the exhaust by the exhaust heat recovery means is suppressed. Therefore, as the temperature of the catalyst is raised by the catalyst temperature raising means, the exhaust heat recovery from the exhaust system by the exhaust heat collecting means is suppressed and the activation of the catalyst is promoted, which is advantageous in promoting the purification of exhaust gas. Become.
According to the second aspect of the invention, since the exhaust heat recovery means accommodates the catalyst, the heat generation from the catalyst can be recovered in addition to the recovery of the exhaust heat, so that the efficiency of the exhaust heat recovery is increased. This is advantageous.
According to the third aspect of the present invention, when it is determined that the catalyst is not activated and the warm-up of the internal combustion engine is not completed, the operation of the catalyst temperature raising means is more than the operation of the exhaust heat recovery means. Since it is preferentially executed, the catalyst can be activated at an early stage, which is advantageous in enhancing the exhaust purification performance of the exhaust purification device.
According to the fourth aspect of the invention, since the catalyst temperature raising means is controlled based on the warm-up state of the internal combustion engine when the internal combustion engine is warmed up by the exhaust heat recovery means, the warm-up time can be shortened and the fuel consumption can be reduced. This is advantageous for improvement.
According to the fifth aspect of the present invention, when it is determined that the catalyst has been activated and the warm-up of the internal combustion engine has not been completed and the predetermined warm-up state has not been reached, When the operation of the heat recovery means and the operation of the catalyst temperature raising means are executed at the same time, and it is determined that the catalyst is activated and has reached the standard warm-up state, only the operation of the exhaust heat recovery means is executed. Therefore, it is advantageous for shortening the warm-up time and improving fuel consumption.
According to the sixth aspect of the present invention, the reference warm-up state can be determined easily and accurately, and the catalyst temperature raising means and the exhaust heat recovery means can be precisely controlled.
According to the seventh aspect of the present invention, when it is determined that the catalyst is activated and the warm-up of the internal combustion engine is completed, both the operation of the exhaust heat recovery means and the operation of the catalyst temperature raising means are stopped. Since it did in this way, warming up of an internal combustion engine can be complete | finished exactly, suppressing the excessive temperature rise of a catalyst.
According to the eighth aspect of the present invention, the exhaust control means is provided on the downstream side of the catalyst, and the exhaust passage is provided in the vicinity of the catalyst, thereby improving the temperature raising efficiency of the catalyst and accurately raising the temperature raising operation of the catalyst. Can be controlled.

It is a block diagram which shows the exhaust gas purification apparatus 22 of the internal combustion engine of this Embodiment. 3 is a first cross-sectional view for explaining the operation of a catalyst 26 and a heat recovery means 28. FIG. 3 is a second cross-sectional view for explaining the operation of the catalyst 26 and the heat recovery means 28. 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 a heat recovery device 34 described later.

  The exhaust purification device 22 includes a catalyst 26, exhaust heat recovery means 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 exhaust heat recovery means 28 accommodates the catalyst 26 and raises the temperature of the cooling water of the engine 10 by exhaust heat of exhaust after passing through the catalyst 26.
As shown in FIGS. 1 and 2, the exhaust heat recovery means 28 includes a heat recovery device 34, an exhaust control valve 36, an inflow pipe 38, an outflow pipe 40, and a medium control valve 42. Yes.
The heat recovery device 34 is interposed in the middle portion of the exhaust pipe 24 in the longitudinal direction.
The heat recovery apparatus 34 includes first, second, and third cylindrical wall portions 44, 46, and 48 that are coaxial with the exhaust pipe 24, and the cylindrical wall portions 44, 46, and 48 are arranged in the longitudinal direction of the exhaust pipe 24. Extending along.
The first cylindrical wall portion 44 is provided with an inner diameter smaller than that of the exhaust pipe 24.
The catalyst 26 is accommodated inside the first cylindrical wall portion 44.
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 constitutes an exhaust flow rate control unit that is provided on the downstream side of the catalyst 26 and controls the flow rate of the exhaust gas that passes through the catalyst 26.

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.

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.
That is, the exhaust flow passage 60 corresponds to an exhaust passage through which the exhaust after passing through the catalyst 26 flows around the catalyst 26.
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 heat recovery device 34 is maintained at about 1 to 2 atm. Become. Thereby, the temperature rise of the catalyst 26 is promoted.
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.
In the present embodiment, the exhaust control valve 36 and the ECU 20 that controls the exhaust control valve 36 correspond to catalyst temperature raising means for raising the temperature of the catalyst 26, and the catalyst temperature raising means is controlled by the exhaust control valve 36. The temperature raising operation of the catalyst 26 is executed or stopped by controlling the flow rate of the exhaust gas passing through the catalyst 26.
The catalyst temperature raising means is only required to raise the temperature of the catalyst 26, and various conventionally known configurations and controls such as post injection by the fuel injection device 14 and provision of a heater for heating the medium 26 are possible. It can be adopted.

  In addition, a medium flow passage (not shown) through which cooling water flows around the catalyst 26 is formed inside the first, second, and third cylindrical wall portions 44, 46, and 48, and flows through the exhaust flow passage 60. The cooling water flowing through the medium flow path can be heated by the heat of the exhaust.

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 medium flow passage.
As the medium control valve 42 controls the flow rate of the cooling water, the exhaust heat recovery means 28 executes or stops the cooling water heating operation.

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.

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 opening / closing operations of the exhaust control valve 36 and the medium control valve 42 based on both the active state detected by the catalyst active state detecting means and the warm-up state detected by the warm-up state detecting means. Is.

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 remains in the exhaust flow passage 60 of the heat recovery device 34, so that the temperature of the catalyst 26 is increased. The
Further, by closing the medium control valve 42, the flow of the cooling water in the medium flow path of the heat recovery device 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. The temperature increase of 26 is further promoted.
That is, by performing the operation for raising the temperature of the catalyst 26 in preference to the operation of the exhaust heat recovery means 28, the temperature of the catalyst 26 is given priority over the warming up of the engine 10. That is, when the activation of the catalyst 26 is promoted by the catalyst temperature raising means, the heat recovery from the exhaust by the exhaust heat recovery means 28 is suppressed.
In other words, in steps S12 and S14, when it is determined that the catalyst 26 is not activated and the engine 10 has not been warmed up, the operation of the catalyst temperature raising means is changed from the operation of the exhaust heat recovery means 28. Is equivalent to executing with priority.
As a result, since the cooling water does not flow through the medium flow path 60 of the exhaust heat recovery means 28, the catalyst 26 is heated by the heat of the exhaust while the heat exchange between the heat of the exhaust and the cooling water is suppressed. become. Therefore, the catalyst 26 can be activated at an early stage, which is advantageous in improving the exhaust purification performance of the exhaust purification device 22.
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 flows in the medium flow passage of the heat recovery device 34, and the exhaust control valve 36 is closed so that the cooling water due to the exhaust heat of the exhaust gas after passing through the catalyst 26. A temperature raising operation is performed.
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 warm-up state. This corresponds to the simultaneous execution of the operation of the heat recovery means 28 and the operation of the catalyst temperature raising means.
In other words, in steps S16 and S18, when it is determined that the catalyst 26 is activated and the engine 10 has not been warmed up, the operation of the exhaust heat recovery means 28 and the operation of the catalyst temperature raising means are performed. This is equivalent to executing them simultaneously.
This is advantageous in shortening the warm-up time and improving fuel consumption.
Steps S16 and S18 correspond to controlling the temperature increase amount of the catalyst 26 by the catalyst temperature increase means based on the warm-up state of the engine 10 when the exhaust heat recovery means 28 warms up the engine 10.
If step S18 is performed, it will return to step S16.

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 after passing through the catalyst 26 is exhausted from the first exhaust port 52 to the exhaust pipe 24 on the downstream side, as shown in FIG. The exhaust pressure returns to the original, 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 the exhaust heat recovery means 28 is executed, and the operation of the catalyst temperature increase means is performed. Is equivalent to stopping.
In other words, steps S16 and S20 correspond to executing only the operation of the exhaust heat recovery means 28 when it is determined that the catalyst 26 is activated and the engine 10 has not been warmed up. .
Steps S <b> 16 and S <b> 20 correspond to controlling the temperature increase amount of the catalyst 26 by the catalyst temperature increasing means based on the warm-up state of the engine 10 when the exhaust heat recovery means 28 warms up the engine 10.
This is advantageous in shortening the warm-up time and improving fuel consumption.
If step S20 is performed, it will return to step S10.

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 stop both the operation of the exhaust heat recovery means 28 and the operation of the catalyst temperature raising means when it is determined that the catalyst 26 is activated and the engine 10 has been warmed up. Is equivalent to

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 exhaust purification device 22 of the present embodiment, it is detected that the engine 10 is not warmed up by the warm-up state detection means, and the catalyst 26 is not activated by the catalyst active state detection means. When this is detected, the operation of the catalyst temperature raising means has priority over the operation of the exhaust heat recovery means 28.
Therefore, when early activation of the catalyst 26 is necessary, the operation of the catalyst temperature raising means is preferentially executed, whereby the catalyst 26 is activated early, which is advantageous in promoting the purification of exhaust gas.

  According to the present embodiment, since the catalyst temperature raising means and the exhaust heat recovery means 28 are controlled based on both the active state of the catalyst 28 and the warm-up state of the engine 10, the warm-up of the engine 10 is performed. And activation of the catalyst 28 can both be achieved.

  Further, when it is determined that the catalyst 28 is not activated and the warm-up of the engine 10 is not completed, the operation of the catalyst temperature raising means is executed with priority over the operation of the exhaust heat recovery means 28. Therefore, the catalyst 26 can be activated at an early stage, which is advantageous in improving the performance of the exhaust purification device 22.

  Further, when the engine 10 is warmed up by the exhaust heat recovery means 28, the temperature rise amount of the catalyst 26 by the catalyst temperature raising means is controlled based on the warm-up state of the engine 10, so that the warm-up time is shortened and the fuel consumption is reduced. This is advantageous for improvement.

  Further, when it is determined that the catalyst 28 is activated and the warm-up of the engine 10 has not been completed and the predetermined warm-up state has not been reached, the operation of the exhaust heat recovery means 28 The operation of the catalyst temperature raising means is executed at the same time, and when it is determined that the catalyst 28 is activated and has reached the standard warm-up state, only the operation of the exhaust heat recovery means 28 is executed. Therefore, it is advantageous for shortening the warm-up time and improving fuel consumption.

  Further, when the temperature of the cooling water exceeds a predetermined first warm-up determination temperature TA, it is determined that the warm-up has been completed, and the temperature of the cooling water is lower than the first warm-up determination temperature TA. When the warm-up determination temperature TB is exceeded, it is determined that the reference warm-up state has been reached, and when the amount of exhaust purification purified by the catalyst 28 in a state where the warm-up of the engine 10 is completed is X, the catalyst 28 is purified. Since the temperature of the cooling water when the purification amount of exhaust gas to be X / 2 is the second warm-up determination temperature TB, the reference warm-up state can be determined easily and accurately.

  In addition, when it is determined that the catalyst 28 is activated and the warm-up of the engine 10 is completed, both the operation of the exhaust heat recovery means 28 and the operation of the catalyst temperature raising means are stopped. The warm-up of the engine 10 can be accurately terminated while suppressing the excessive temperature rise of the engine 26.

  Further, the exhaust heat recovery means 28 executes or stops the temperature rise operation of the cooling water by controlling the flow rate of the cooling water flowing through the medium flow passage 60 through which the cooling water flows around the catalyst 26 by the medium control valve 42. As a result, the temperature raising operation of the cooling water can be accurately controlled.

  Further, the catalyst temperature raising means controls the temperature rise of the catalyst 28 by controlling the flow rate of the exhaust gas passing through the catalyst 28 by the exhaust control valve 36 provided on the downstream side of the catalyst 28 and controlling the flow rate of the exhaust gas passing through the catalyst 28. Since the operation is executed or stopped, the temperature raising operation of the catalyst 28 can be accurately controlled.

In the present embodiment, the medium flow path 60 of the exhaust heat recovery means 28 is provided around the catalyst 26, and the medium flow path 60 is located closer to the upstream side of the exhaust flow. This is advantageous in raising the temperature of the (heat exchange medium) more efficiently, and is advantageous in reducing the size of the exhaust heat recovery means 28.
In the present embodiment, the heat of the exhaust recovered by the exhaust heat recovery means 28 is used to raise the temperature of the cooling water of the engine 10, but the temperature of other fluids such as lubricating oil and air may be raised, The 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.

  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, control means) 22 …… Exhaust purification device, 24 …… Exhaust pipe, 26 …… Catalyst, 28 …… Exhaust heat recovery means 28, 30 …… Medium temperature sensor, 32 …… Exhaust temperature sensor, 36 …… Exhaust control valve (exhaust flow rate) Control means), 42... Medium control valve (medium flow rate control means), 60... Medium flow passage.

Claims (8)

A catalyst for purifying exhaust gas discharged from the internal combustion engine;
Exhaust heat recovery means for recovering exhaust heat of the exhaust gas of the internal combustion engine and promoting warm-up of the internal combustion engine;
A catalyst temperature raising means for raising the temperature of the catalyst;
Catalyst active state detecting means for detecting the active state of the catalyst;
A warm-up state detecting means for detecting a warm-up state of the internal combustion engine;
Control means for controlling the catalyst temperature raising means and the exhaust heat recovery means based on the active state detected by the catalyst active state detecting means and the warm-up state detected by the warm-up state detecting means; The exhaust gas purification apparatus for an internal combustion engine, wherein the control means suppresses heat recovery from the exhaust gas by the exhaust heat recovery means when the activation of the catalyst is promoted by the catalyst temperature raising means. The exhaust gas purification device for an internal combustion engine according to claim 1, wherein the exhaust heat recovery means contains the catalyst. The control means prioritizes the operation of the catalyst temperature raising means over the operation of the exhaust heat recovery means when it is determined that the catalyst is not activated and the internal combustion engine has not been warmed up. To
The exhaust emission control device for an internal combustion engine according to claim 1 or 2. The said control means controls the temperature rising amount of the said catalyst by the said catalyst temperature rising means based on the said warming-up state at the time of warming up of the said internal combustion engine by the said exhaust heat recovery means. The exhaust gas purification apparatus for an internal combustion engine according to any one of the above. The control means determines that the exhaust heat recovery is performed when it is determined that the catalyst is activated and the internal combustion engine has not been warmed up and has not reached a predetermined warm-up state. Only when the exhaust heat recovery means is operated when it is determined that the catalyst is activated and has reached the reference warm-up state. To execute,
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. The warm-up state detection means detects the temperature of the cooling water of the internal combustion engine as the warm-up state,
The control means determines that the warm-up is completed when the temperature of the cooling water exceeds a predetermined first warm-up determination temperature TA, and the temperature of the cooling water is the first warm-up determination temperature. When the second warm-up determination temperature TB lower than TA is exceeded, it is determined that the reference warm-up state has been reached,
6. An exhaust emission control device for an internal combustion engine according to claim 5, wherein: The control means stops both the operation of the exhaust heat recovery means and the operation of the catalyst temperature raising means when it is determined that the catalyst is activated and the warm-up of the internal combustion engine is completed.
The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 6, wherein the exhaust gas purification device is an internal combustion engine. The catalyst temperature raising means includes exhaust flow rate control means for controlling the flow rate of exhaust gas that is provided downstream of the catalyst and passes through the catalyst,
The catalyst temperature raising means executes or stops the temperature raising operation of the catalyst by controlling the flow rate of exhaust gas passing through the catalyst by the exhaust flow rate control means,
Furthermore, an exhaust passage through which the exhaust after passing through the catalyst flows around the catalyst is provided,
The catalyst temperature raising means executes or stops the temperature raising operation of the catalyst by controlling the flow rate of exhaust gas passing through the exhaust passage by the exhaust flow rate control means.
The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 7, wherein the exhaust gas purification device is an internal combustion engine.

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