JP2010159680A - Exhaust system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system capable of suppressing boiling of cooling water after stopping the operation of an internal-combustion engine. <P>SOLUTION: An exhaust system (100) includes: an exhaust gas cooling part (110) cooling exhaust gas exhausted from an exhaust gas port (12) of an internal-combustion engine (10) using cooling water; exhaust passages (120, 122) communicating with the exhaust gas cooling part and a catalyst part (30) having a catalyzer purifying exhaust gas exhausted from the exhaust gas port; a valve (130) arranged in the exhaust passages and switching the exhaust passages between a blockade status and a non-blockade status; an operation status detection means (140) detecting whether the internal-combustion engine is operated or not; and a control means (150) controlling the valve based on a detection result detected by the operation status detection means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust system.

  In a conventional internal combustion engine, exhaust discharged from an exhaust port of the internal combustion engine passes through an exhaust manifold and then passes through a catalyst portion having an exhaust purification catalyst. In such an internal combustion engine, the exhaust may become hot. Therefore, Patent Document 1 discloses a technique for suppressing a rise in exhaust gas temperature by providing a water-cooled exhaust cooling unit (exhaust cooling adapter) having a cooling water passage between a cylinder head and an exhaust manifold. ing.

Japanese Utility Model Publication No. 64-15718

  In the technique according to Patent Document 1, when the operation of the internal combustion engine is stopped, the circulation of the cooling water provided to the exhaust cooling unit is also stopped. In this case, the cooling water may boil after the operation of the internal combustion engine is stopped. If the internal combustion engine is restarted in a state where the cooling water has boiled, it may be difficult to exert the function of the exhaust cooling unit.

  An object of the present invention is to provide an exhaust system capable of suppressing boiling of cooling water after the operation of an internal combustion engine is stopped.

  An exhaust system according to the present invention includes an exhaust cooling unit that cools exhaust discharged from an exhaust port of an internal combustion engine with cooling water, and a catalyst that purifies the exhaust discharged from the exhaust cooling unit and the exhaust port. An exhaust passage that communicates with the exhaust passage, a valve that is disposed in the exhaust passage and switches between a shut-off state and a non-cut-off state of the exhaust passage, and detects whether the internal combustion engine is in an operating state or a stopped state An operation state detection unit and a control unit for controlling the valve based on a detection result of the operation state detection unit are provided.

  According to the exhaust system of the present invention, the exhaust passage can be shut off when the detection result of the operation state detection means is the operation stop state. Thereby, the heating of the cooling part by the gas flowing backward from the catalyst part side after the operation of the internal combustion engine is stopped and the heating of the cooling part by the radiant heat of the catalyst part are suppressed. As a result, boiling of the cooling water after the operation of the internal combustion engine is stopped can be suppressed.

  In the above configuration, the control unit controls the valve so that the exhaust passage is in the non-blocking state when the detection result of the operation state detection unit is the operation state, and the detection result of the operation state detection unit When the operation is stopped, the valve may be controlled so that the exhaust passage is in the shut-off state.

  The above configuration may further include an acquisition unit that acquires a parameter that can evaluate the state of the cooling water, and the control unit may control the valve based on an acquisition result of the acquisition unit.

  According to this configuration, the exhaust passage can be shut off when the acquisition result of the acquisition means is equal to or greater than the threshold value and the internal combustion engine is stopped. In this case, boiling of the cooling water can be suppressed.

  In the above-described configuration, the control unit is configured so that the exhaust passage is in the non-blocking state when the acquisition result of the acquisition unit is smaller than a threshold value or when the detection result of the operation state detection unit is the operation state. The valve is controlled, and when the acquisition result of the acquisition unit is equal to or greater than the threshold value and when the detection result of the operation state detection unit is the operation stop state, the valve is controlled so that the exhaust passage is in the cutoff state. May be.

  ADVANTAGE OF THE INVENTION According to this invention, the exhaust system which can suppress the boiling of cooling water after the operation stop of an internal combustion engine can be provided.

FIG. 1 is a schematic diagram of a vehicle in which an exhaust system according to a first embodiment is used. FIG. 2 is a schematic diagram of the vehicle when the internal combustion engine is in a stopped state. FIG. 3 is a diagram illustrating an example of a flowchart of the ECU according to the first embodiment. FIG. 4 is a schematic diagram of a vehicle in which the exhaust system according to the second embodiment is used. FIG. 5 is a diagram illustrating an example of a flowchart of the ECU according to the second embodiment.

  Hereinafter, modes for carrying out the present invention will be described.

  An exhaust system 100 according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram of a vehicle 200 in which the exhaust system 100 according to the first embodiment is used. The vehicle 200 includes an internal combustion engine 10, a cooling water circuit 20, a catalyst unit 30, and an exhaust system 100. An intake port 11 and an exhaust port 12 are formed in the cylinder block of the internal combustion engine 10.

  The cooling water circuit 20 is a circuit for circulating cooling water supplied to an exhaust cooling unit 110 described later. The cooling water circuit 20 mainly includes a radiator 21, a cooling water circulation pump 22, and a reserve tank 23. The radiator 21 cools the cooling water supplied to the exhaust cooling unit 110 by heat exchange with the outside air. The cooling water circulation pump 22 is a pump for circulating cooling water. The cooling water circulation pump 22 starts operating when the internal combustion engine 10 starts operating, and stops operating while the internal combustion engine 10 stops operating. The reserve tank 23 is a tank that stores cooling water circulating in the cooling water circuit 20.

  The catalyst unit 30 is connected downstream of an exhaust pipe 122 described later. The catalyst unit 30 has a catalyst for purifying the exhaust discharged from the exhaust port 12. As the catalyst unit 30, for example, a three-way catalyst device or the like can be used.

  The exhaust system 100 includes an exhaust cooling unit 110, an exhaust passage (exhaust manifold 120 and exhaust pipe 122), a valve 130, an operating state detection unit 140, and an ECU 150.

  The exhaust cooling unit 110 is a device that cools the exhaust discharged from the exhaust port 12 with cooling water. In the present embodiment, the exhaust cooling unit 110 is connected to the cylinder block of the internal combustion engine 10. The exhaust cooling unit 110 has a passage through which the exhaust discharged from the exhaust port 12 passes through the exhaust cooling unit 110. Further, the exhaust cooling unit 110 has a passage (hereinafter referred to as a cooling water passage) through which the cooling water flows. The exhaust discharged from the exhaust port 12 is cooled by the cooling water flowing in the cooling water passage when passing through the exhaust cooling unit 110. The cooling water used for cooling the exhaust is cooled by the radiator 21 and supplied to the exhaust cooling unit 110 again.

  The exhaust passage is a passage communicating the exhaust cooling unit 110 and the catalyst unit 30. In this embodiment, the exhaust passage includes an exhaust manifold 120 and an exhaust pipe 122. The exhaust manifold 120 is connected downstream of the exhaust cooling unit 110. The exhaust pipe 122 is connected downstream of the exhaust manifold 120.

  The valve 130 is disposed in the exhaust passage. In this embodiment, the valve 130 is disposed in the exhaust pipe 122. In response to an instruction from ECU 150, valve 130 switches between an exhaust passage blocking state and a non-blocking state. Specifically, when the valve 130 is closed, the exhaust passage is cut off. Further, when the valve 130 is opened, the exhaust passage is in a non-blocking state. When the exhaust passage is in a non-blocking state, the catalyst unit 30 and the exhaust cooling unit 110 communicate with each other. In FIG. 1, the valve 130 is open.

  The valve 130 is not particularly limited as long as it can switch between an exhaust passage blocking state and a non-blocking state in response to an instruction from the ECU 150. An electric valve or the like can be used as the valve 130. Alternatively, the valve 130 may be an application of an exhaust throttle valve used for introducing EGR so that the exhaust passage can be switched between a blocked state and a non-blocked state.

  The operation state detection unit 140 detects whether the internal combustion engine 10 is in an operation state or an operation stop state, and transmits the detection result to the ECU 150. Although it does not specifically limit as the driving | running state detection means 140, For example, an engine speed sensor etc. can be used.

  The ECU 150 is a microcomputer that includes a CPU 151, a ROM 152, and a RAM 153. The ECU 150 has a function as a control unit that controls the valve 130 based on the detection result of the operation state detection unit 140.

  Subsequently, operations of the vehicle 200 and the exhaust system 100 will be described. First, when the internal combustion engine 10 starts operation, the ECU 150 controls the valve 130 so that the valve 130 is opened. Thereby, the exhaust passage is in a non-blocking state. In this case, the exhaust discharged from the exhaust port 12 flows through the exhaust cooling unit 110, the exhaust manifold 120, and the exhaust pipe 122 to reach the catalyst unit 30. In the catalyst part 30, the exhaust gas is purified. The exhaust gas flowing through the catalyst unit 30 is then discharged to the outside of the vehicle 200.

  Further, when the internal combustion engine 10 starts operation, the cooling water circulation pump 22 starts circulation of the cooling water. Thereby, the exhaust gas discharged from the exhaust port 12 is cooled by the exhaust cooling unit 110. As a result, the temperature rise of the exhaust is suppressed. The cooling water is cooled by the radiator 21. Therefore, when the internal combustion engine 10 is in an operating state, boiling of the cooling water is suppressed.

  FIG. 2 is a schematic diagram of the vehicle 200 when the internal combustion engine 10 is in a stopped state. When the internal combustion engine 10 is stopped, no exhaust is generated. Further, the operation of the cooling water circulation pump 22 is stopped. The ECU 150 controls the valve 130 so that the valve 130 is closed. When the valve 130 is closed, the exhaust passage is cut off.

  Here, when the internal combustion engine 10 is in an operating state, the catalyst unit 30 is heated by the exhaust gas. Therefore, when the internal combustion engine 10 is in an operating state, the temperature of the catalyst unit 30 is higher than normal temperature. On the other hand, after the operation of the internal combustion engine 10 is stopped, the catalyst unit 30 is not heated by the exhaust gas. However, the temperature of the catalyst unit 30 does not always decrease to normal temperature immediately after the operation of the internal combustion engine 10 is stopped. Therefore, when the exhaust system 100 does not include the valve 130, the gas heated by the catalyst unit 30 after the operation of the internal combustion engine 10 stops may flow backward to heat the exhaust cooling unit 110. In addition, the radiation heat of the catalyst unit 30 may heat the exhaust cooling unit 110 after the operation of the internal combustion engine 10 is stopped. When the exhaust cooling unit 110 is heated, the cooling water may be boiled.

  In that respect, according to the exhaust system 100 according to the present embodiment, the bubble 130 is controlled to close after the operation of the internal combustion engine 10 is stopped. Thereby, it is possible to suppress the exhaust cooling unit 110 from being heated by the gas flowing backward from the catalyst unit 30 side after the operation of the internal combustion engine 10 is stopped. Further, it is possible to prevent the exhaust cooling unit 110 from being heated by the radiant heat of the catalyst unit 30 after the operation of the internal combustion engine 10 is stopped. By suppressing the exhaust cooling unit 110 from being heated after the operation of the internal combustion engine 10 is stopped, boiling of the cooling water is suppressed. Further, even in the case of so-called dead soak, such as when the operation of the internal combustion engine 10 is suddenly stopped after the internal combustion engine 10 is in a high load state (for example, when the vehicle 200 is traveling at a high speed, traveling uphill) Boiling of cooling water can be suppressed. By suppressing the boiling of the cooling water after the operation of the internal combustion engine 10 is stopped, the exhaust cooling unit 110 can be made to function early when the internal combustion engine 10 resumes operation.

  FIG. 3 is a diagram illustrating an example of a flowchart of the ECU 150 according to the present embodiment. The ECU 150 repeatedly executes the flowchart of FIG. 3 at predetermined time intervals. First, the ECU 150 determines whether or not the internal combustion engine 10 is in a stopped state (step S10). Specifically, the ECU 150 determines whether or not the internal combustion engine 10 is in the operation stop state by determining whether the detection result of the operation state detection unit 140 is in the operation stop state or the operation state. Can do.

  When it is determined in step S10 that the internal combustion engine 10 is in the operation stop state, the ECU 150 performs control so as to close the valve 130 (step S20). As a result, the exhaust passage is cut off. As a result, boiling of the cooling water after the operation of the internal combustion engine 10 is stopped is suppressed. Next, ECU 150 ends the execution of the flowchart.

  If it is not determined in step S10 that the internal combustion engine 10 is in the operation stop state, the ECU 150 controls to open the valve 130 (step S30). In this case, the exhaust passage is in a non-blocking state. As a result, the exhaust from the exhaust port 12 is cooled by the exhaust cooling unit 110, passes through the exhaust passage and the catalyst unit 30, and is discharged to the outside. Next, ECU 150 ends the execution of the flowchart.

  As described above, the ECU 150 according to this embodiment controls the valve 130 so that the exhaust passage is shut off when the detection result of the operation state detection unit 140 is the operation stop state. The boiling of the cooling water after stopping the operation can be suppressed.

  Then, the exhaust system 100a which concerns on Example 2 of this invention is demonstrated. FIG. 4 is a schematic diagram of a vehicle 200a in which the exhaust system 100a according to the second embodiment is used. Exhaust system 100a differs from exhaust system 100 shown in FIG. 1 in that it further includes an acquisition unit that acquires a parameter that can evaluate the state of the cooling water, and in that it includes ECU 150a instead of ECU 150. Since other configurations are the same as those of the exhaust system 100, description thereof is omitted. As the acquisition means, for example, a temperature sensor 160 that detects the temperature of exhaust gas, a sensor that detects the temperature of cooling water, or a sensor that detects the temperature of the temperature sensor 160 and cooling water is used. In this embodiment, the acquisition means is a temperature sensor 160.

  The temperature sensor 160 detects the temperature of the exhaust and transmits the detection result to the ECU 150a. That is, the temperature sensor 160 has a function as temperature detection means for detecting the temperature of the exhaust. In the present embodiment, the temperature sensor 160 is disposed in the exhaust manifold 120 and detects the temperature of exhaust passing through the exhaust manifold 120. Note that the temperature sensor 160 may detect the temperature of an exhaust passage portion through which the exhaust gas passes in the internal combustion engine 10 and the vehicle 200a instead of directly detecting the temperature of the exhaust gas. As the exhaust passage part, for example, a cylinder block, an exhaust cooling unit 110, an exhaust manifold 120, an exhaust pipe 122, a catalyst unit 30, and the like are used.

  ECU 150a differs from ECU 150 in that valve 130 is controlled based on the detection result of temperature sensor 160. Specifically, the ECU 150a controls to open the valve 130 when the detection result of the temperature sensor 160 is smaller than the threshold value or when the detection result of the operation state detection unit 140 is the operation state. Further, the ECU 150a controls the valve 130 to be closed when the detection result of the temperature sensor 160 is greater than or equal to the threshold value and when the detection result of the operation state detection means 140 is in the operation stop state.

  FIG. 5 is a diagram illustrating an example of a flowchart of the ECU 150a according to the present embodiment. The ECU 150a repeatedly executes the flowchart of FIG. 3 every predetermined time. FIG. 5 differs from the flowchart of FIG. 3 in that step S5 is further provided before step S10. Other configurations are the same as those in FIG.

  In step S5, the ECU 150a determines whether or not the detection result of the temperature sensor 160 is greater than or equal to a threshold value. As the threshold value, for example, a temperature at which the cooling water is considered to boil after the operation of the internal combustion engine 10 is stopped may be used.

  When it is determined in step S5 that the detection result of the temperature sensor 160 is equal to or greater than the threshold value, the ECU 150a executes step S10. On the other hand, when it is not determined in step S5 that the detection result of the temperature sensor 160 is greater than or equal to the threshold value, the ECU 150a executes step S30.

  According to the exhaust system 100a according to the present embodiment, the exhaust passage can be shut off when the detection result of the temperature sensor 160 is equal to or greater than the threshold value and when the internal combustion engine 10 is stopped. Thereby, boiling of the cooling water after operation stop can be suppressed.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed. For example, the exhaust system 100a according to the second embodiment may use a sensor that detects the temperature of the cooling water instead of the temperature sensor 160 that detects the temperature of the exhaust in step S5 of the flowchart of FIG. Alternatively, the exhaust system 100a may use both the temperature sensor 160 and a sensor that detects the temperature of the cooling water in step S5. Or the exhaust system 100a may use the acquisition means which acquires the parameter which can evaluate the state of the temperature sensor 160, the sensor which detects the temperature of cooling water, and the other cooling water in step S5.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Intake port 12 Exhaust port 20 Circuit for cooling water 21 Radiator 22 Cooling water circulation pump 23 Reserve tank 30 Catalyst part 100 Exhaust system 110 Exhaust cooling part 120 Exhaust manifold 122 Exhaust pipe 130 Valve 140 Operating state detection means 150 ECU
160 Temperature sensor 200 Vehicle

Claims (4)

An exhaust cooling section for cooling the exhaust discharged from the exhaust port of the internal combustion engine with cooling water;
An exhaust passage communicating the exhaust cooling unit and a catalyst unit having a catalyst for purifying the exhaust discharged from the exhaust port;
A valve that is disposed in the exhaust passage and switches between a shut-off state and a non-cut-off state of the exhaust passage;
An operation state detection means for detecting whether the internal combustion engine is in an operation state or an operation stop state;
An exhaust system comprising: control means for controlling the valve based on a detection result of the operating state detection means.   The control means controls the valve so that the exhaust passage is in the non-blocking state when the detection result of the operation state detection means is the operation state, and the detection result of the operation state detection means is the operation stop The exhaust system according to claim 1, wherein the valve is controlled so that the exhaust passage is in the shut-off state in a state. An acquisition means for acquiring a parameter capable of evaluating the state of the cooling water;
The exhaust system according to claim 1, wherein the control unit controls the valve based on an acquisition result of the acquisition unit.   The control unit controls the valve so that the exhaust passage is in the non-blocking state when the acquisition result of the acquisition unit is smaller than a threshold value or when the detection result of the operation state detection unit is the operation state. The valve is controlled so that the exhaust passage is in the shut-off state when the acquisition result of the acquisition unit is equal to or greater than the threshold and the detection result of the operation state detection unit is the operation stop state. The exhaust system described.

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