JP2010031648A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of enhancing the warm-up performance of a catalytic device in a constitution having a resonator. <P>SOLUTION: The internal combustion engine 1 includes a catalytic device 42 arranged on an exhaust passage 41 of an engine 2 to purify exhaust, and a resonator 5 opening to the exhaust passage 41, wherein the resonator 5 is provided with an opening/closing valve 52 for adjusting an opening area of an opening to the exhaust passage 41. The opening/closing control of the opening/closing valve 52 is executed on the basis of the warm-up state of the catalytic device 42. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine that can improve the warm-up performance of a catalyst device in a configuration having a resonator.

  Recent internal combustion engines include a catalyst device that is disposed on the exhaust passage of the engine and purifies the exhaust gas. In such an internal combustion engine, there is a problem that the warm-up property of the catalyst device should be improved in order to improve the exhaust purification performance. Further, recent internal combustion engines are provided with a resonator. A resonator is a silencer that reduces the sound of a specific frequency by utilizing Helmholtz's resonance principle. As a conventional internal combustion engine having such a resonator, a technique described in Patent Document 1 is known.

Japanese Utility Model Publication No. 7-10409

  An object of the present invention is to provide an internal combustion engine that can improve the warm-up performance of a catalyst device in a configuration having a resonator.

  In order to achieve the above object, an internal combustion engine according to the present invention is an internal combustion engine including a catalyst device that is disposed on an exhaust passage of an engine and purifies exhaust gas, and a resonator that opens to the exhaust passage. Has an opening / closing valve that adjusts the opening area of the opening to the exhaust passage, and the opening / closing control of the opening / closing valve is performed based on the warm-up state of the catalyst device.

  In this internal combustion engine, the pressure of the exhaust pulsation in the exhaust passage changes due to the opening / closing operation of the open / close valve of the resonator. Further, the warm-up of the catalyst device is affected by the stirring action of the exhaust due to the exhaust pulsation. Therefore, there is an advantage that the warm-up property of the catalyst device can be improved by controlling the opening / closing valve of the resonator according to the warm-up state of the catalyst device.

  In the internal combustion engine according to the present invention, when the catalyst device has not been warmed up, the on-off valve opens.

  In this internal combustion engine, the amplitude of the exhaust pulsation is reduced by the resonator, and the exhaust agitation action due to the pulsation is suppressed. Then, heat transfer from the exhaust to the exhaust manifold is suppressed, and heat loss of the exhaust is reduced, so that there is an advantage that warming up of the catalyst device is promoted.

  In the internal combustion engine according to the present invention, the open / close valve is opened when the operating range of the engine is in a range where a decrease in engine torque due to exhaust pulsation can occur.

  In this internal combustion engine, when the open / close valve of the resonator is opened, the pressure wave in the exhaust passage enters the resonator, thereby reducing the influence of exhaust pulsation. Thereby, a reduction in engine torque is suppressed, and there is an advantage that the fully open high performance of the engine is improved.

  In the internal combustion engine according to the present invention, the on-off valve is opened during steady operation of the engine.

  In this internal combustion engine, when the open / close valve of the resonator is opened, the pressure wave in the exhaust passage enters the resonator, so that the agitation action of exhaust due to exhaust pulsation is alleviated. Then, the reaction between the catalyst and the exhaust is suppressed, and the increase in the catalyst bed temperature is suppressed. Thereby, there exists an advantage by which deterioration of a catalyst is suppressed and the lifetime of a catalyst is maintained.

  In addition, when the internal combustion engine according to the present invention has an exhaust gas recirculation device that supplies a part of the exhaust gas to the intake port and recirculates the exhaust gas to the engine, the open / close valve is opened during exhaust gas recirculation.

  In this internal combustion engine, when the open / close valve of the resonator is opened, the pressure wave in the exhaust passage enters the resonator, thereby reducing the amplitude of the exhaust pulsation. Then, the exhaust flow in the exhaust passage is stabilized, and the amount of recirculated gas is made uniform. Thereby, there exists an advantage which an exhaust gas recirculation apparatus functions correctly and a fuel consumption improves.

  In the internal combustion engine according to the present invention, the pressure of the exhaust pulsation in the exhaust passage changes due to the opening / closing operation of the open / close valve of the resonator. Further, the warm-up of the catalyst device is affected by the stirring action of the exhaust due to the exhaust pulsation. Therefore, there is an advantage that the warm-up property of the catalyst device can be improved by controlling the opening / closing valve of the resonator according to the warm-up state of the catalyst device.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a block diagram showing an internal combustion engine according to an embodiment of the present invention. FIGS. 2 and 3 are an arrangement configuration diagram (FIG. 2) and an enlarged sectional view (FIG. 3) showing the resonator of the internal combustion engine shown in FIG. 4 to 6 are a flowchart (FIG. 4) and an explanatory diagram (FIGS. 5 and 6) showing the operation of the internal combustion engine shown in FIG. 1. 7 and 8 are flowcharts showing a modification of the internal combustion engine shown in FIG.

[Internal combustion engine]
The internal combustion engine 1 includes an engine 2, an intake system 3, an exhaust system 4, a resonator 5, and a control system 6, and is mounted on a vehicle to generate power (see FIG. 1).

  The engine 2 includes a piston (not shown), a cylinder bore 21 that accommodates the piston, a crankshaft coupled to the piston, an intake port 22 and an exhaust port 23 connected to the cylinder bore 21 (combustion chamber), and fuel to the outside air. And a spark plug (not shown). In the engine 2, fuel is added to the introduced outside air to form an air-fuel mixture. The air-fuel mixture is sucked into the cylinder bore 21 from the intake port 22 and compressed. Next, the air-fuel mixture is ignited by the spark plug and burned in the cylinder bore 21, and the piston is driven by the combustion energy to reciprocate in the cylinder bore 21. Then, the reciprocating motion of the piston is converted into the rotational motion of the crankshaft to generate power. Further, the combustion gas in the cylinder bore 21 is discharged to the outside of the cylinder bore 21 through the exhaust port 23.

  The intake system 3 includes an intake passage 31, an air filter 32, a throttle valve 33, and a surge tank 34. The intake passage 31 is a passage for introducing intake air into the engine 2. The air filter 32 is disposed at the inlet of the intake passage 31 and removes dust, dust and the like in the intake air. The throttle valve 33 is a flow rate adjusting valve that adjusts the cross-sectional area of the intake passage 31. The surge tank 34 is a tank that temporarily stores intake air and suppresses intake pulsation. In the intake system 3, the intake air that has passed through the air filter 32 passes through the throttle valve 33 and the surge tank 34 and is supplied to the intake port 22 of the engine 2.

The exhaust system 4 includes an exhaust passage (exhaust pipe) 41 and a catalyst device 42 disposed on the exhaust passage 41. The exhaust passage 41 is a passage for discharging the exhaust from the engine 2 to the outside, and is connected to the engine exhaust port 23 via an exhaust manifold. The catalyst device 42 has a catalyst (for example, a three-way catalyst) for purifying harmful gases (CO, CH, NOx) in the exhaust gas into harmless gases (CO ₂ , H ₂ O, N ₂ ). In the exhaust system 4, exhaust from the engine 2 flows into the exhaust passage 41, is purified by the catalyst device 42, and is discharged outside.

  The resonator 5 is a silencer that reduces the sound of a specific frequency using the Helmholtz resonance principle, and is disposed on the exhaust passage 41 (see FIGS. 1 to 3). The resonator 5 includes a resonator body 51 and an opening / closing valve 52. The resonator body 51 is formed of a cylindrical or container-like hollow member, and constitutes a resonator chamber having a predetermined silencing frequency. The resonator main body 51 opens into the exhaust passage 41. For example, in this embodiment, the resonator body 51 opens into the exhaust passage 41 on the downstream side of the exhaust manifold and the upstream side of the catalyst device 42 (see FIG. 2). The opening / closing valve 52 is disposed in the opening of the resonator body 51. By opening / closing control of the opening / closing valve 52, the opening area of the resonator body 51 with respect to the exhaust passage 41 is adjusted. In this embodiment, a butterfly valve is employed as the open / close valve 52. In the resonator 5, when the open / close valve 52 is opened, the resonator main body 51 and the exhaust passage 41 communicate with each other, and an exhaust pressure wave enters the resonator main body 51. Thereby, the pressure wave of exhaust gas is relieved and exhaust noise is reduced.

The control system 6 includes an ECU (Electronic Control Unit) 61 and various sensors. The various sensors include, for example, a gas sensor 62 such as an air-fuel ratio sensor or an oxygen concentration sensor (O ₂ sensor), a rotational speed sensor that detects engine rotational speed, a torque sensor (not shown) that detects engine torque, an accelerator opening sensor, It consists of a vehicle speed sensor. In this control system 6, the ECU 51 controls the open / close valve 52 of the resonator 5 based on the measurement results of various sensors.

[Control of the open / close valve of the resonator]
In the internal combustion engine 1, during the warm-up operation, the open / close valve 52 is controlled based on the warm-up state of the catalyst device 42 (see FIG. 4). Specifically, first, after the ignition start, it is determined whether or not the catalyst device 42 has been warmed up (ST11). This determination step ST11 is performed by the ECU 61 based on the output value of the gas sensor 62. If it is not determined that the catalyst device 42 has been warmed up (in the case of negative determination), the open / close valve 52 of the resonator 5 is opened (ST12). Then, the pressure wave in the exhaust passage 41 enters the resonator 5, so that the amplitude of exhaust pulsation in the exhaust passage 41 decreases. Then, since the stirring action of exhaust due to pulsation is reduced, heat transfer from the exhaust to the exhaust manifold is suppressed. Thereby, the heat loss of the exhaust gas is reduced, and the warming-up of the catalytic device 42 is promoted (the warming-up promoting action of the catalytic device 42 by the resonator 5).

  By the way, the crank angle [deg] of the engine and the pressure [kPa] of the exhaust pulsation have a relationship shown in FIG. 5, for example. As shown in FIG. 5, when the maximum value of the exhaust pulsation pressure appears at the time of lap between the exhaust stroke and the intake stroke of the engine, the full opening performance (engine torque) of the engine decreases due to the influence of the exhaust pulsation (broken line in FIG. 5). reference). On the other hand, the pressure distribution of the exhaust pulsation can be changed by opening / closing control of the opening / closing valve 52 of the resonator 5. Therefore, by adjusting the opening / closing valve 52 of the resonator 5 to adjust the pressure distribution of the exhaust pulsation, the maximum value of the exhaust pulsation pressure can be moved to a position deviated from the lap time of the exhaust stroke and the intake stroke ( (See the solid line in FIG. 5). Thereby, the fully open performance of the engine can be improved.

  Further, at the time of steady operation after completion of warm-up, engine torque may decrease due to exhaust pulsation in a predetermined operation region (see FIG. 6). For example, in the example shown in FIG. 6, when the open / close valve 52 of the resonator 5 is normally closed (non-operating), the engine torque decreases due to exhaust pulsation in the predetermined operation regions X1 and X2. It has occurred (see broken line in FIG. 6). On the other hand, when the open / close valve 52 of the resonator 5 is open (during operation), the pressure wave in the exhaust passage 41 enters the resonator 5, thereby reducing the amplitude of exhaust pulsation in the exhaust passage 41. Then, the influence of exhaust pulsation is mitigated, and the decrease in engine torque is suppressed. Therefore, the full opening performance of the engine is improved by controlling the opening / closing valve 52 of the resonator 5 to adjust the exhaust pulsation (see the solid line in FIG. 6). It should be noted that the regions X1 and X2 in which the engine torque can be reduced due to exhaust pulsation can be defined based on, for example, the relationship between the engine speed and the engine torque acquired by a predetermined conformance test.

  From the above viewpoint, when it is determined in the determination step ST11 that the warm-up of the catalyst device 42 has been completed, the engine operating region is changed to the regions X1 and X2 in which a decrease in engine torque due to exhaust pulsation can occur. It is determined whether or not there is (ST13). That is, it is determined whether or not the engine operating range after completion of warm-up is in a range that requires adjustment of exhaust pulsation. If it is determined in the determination step ST13 that the engine operating region is in the regions X1 and X2, the open / close valve 52 of the resonator 5 is controlled to open and close (ST14). As a result, the influence of exhaust pulsation is mitigated, and a decrease in engine torque is suppressed. On the other hand, when it is not determined in the determination step ST13 that the engine operating region is in the regions X1 and X2 (in the case of negative determination), the open / close valve 52 of the resonator 5 is closed (ST15).

[effect]
As described above, in the internal combustion engine 1, the resonator 5 has the opening / closing valve 52 that adjusts the opening area of the opening to the exhaust passage, and the opening / closing control of the opening / closing valve 52 based on the warm-up state of the catalyst device 42. Is performed (see FIGS. 1 to 4). In such a configuration, the pressure of the exhaust pulsation in the exhaust passage changes due to the opening / closing operation of the opening / closing valve 52 of the resonator 5. Further, the warm-up of the catalyst device 42 is affected by the exhaust stirring action caused by the exhaust pulsation. Therefore, there is an advantage that the warm-up property of the catalyst device 42 can be improved by controlling the opening / closing valve 52 of the resonator 5 according to the warm-up state of the catalyst device 42.

  For example, in this embodiment, when the warm-up of the catalyst device 42 is not completed, the open / close valve 52 of the resonator 5 is opened (ST11, ST12) (see FIG. 4). In such a configuration, the amplitude of the exhaust pulsation is reduced by the resonator 5, and the exhaust agitation action due to the pulsation is suppressed. Then, the heat transfer from the exhaust to the exhaust manifold is suppressed, and the heat loss of the exhaust is reduced, so that there is an advantage that warming up of the catalyst device 42 is promoted.

  In this embodiment, the opening area of the resonator body 51 is set to be extremely smaller than the flow path cross-sectional area of the exhaust passage 41 (see FIGS. 2 and 3). For this reason, when the on-off valve 52 is opened, only the pressure wave of the exhaust enters the resonator main body 51, so that the inflow amount of the exhaust itself is small. Therefore, it is considered that there is little adverse effect due to the installation of the resonator 5 when the catalyst device 42 is warmed up.

  Further, in the internal combustion engine 1, when the operating region of the engine 2 is in the regions X1 and X2 where the engine torque can be reduced due to exhaust pulsation, the open / close valve 52 of the resonator 5 is opened (ST13 and ST14) ( (See FIG. 4 and FIG. 6). In such a configuration, when the opening / closing valve 52 of the resonator 5 is opened, the pressure wave in the exhaust passage 41 enters the resonator 5, thereby reducing the influence of exhaust pulsation. Thereby, a reduction in engine torque is suppressed, and there is an advantage that the fully open high performance of the engine is improved.

[Modification]
In general, when the catalyst device is warmed up and is in steady operation, and the exhaust manifold temperature rises to an equilibrium state with respect to the exhaust temperature, the heat capacity of the exhaust manifold and the heat transfer rate between the exhaust manifold and outside air become constant. . Then, regardless of the presence or absence of exhaust pulsation, the amount of heat transferred from the exhaust to the exhaust manifold becomes substantially constant. However, if there is an exhaust pulsation, the exhaust is agitated and the exhaust coming into contact with the catalyst of the catalyst device 42 increases. Then, there is a problem that the reaction between the catalyst and the exhaust is promoted, the catalyst bed temperature is increased, the heat load on the catalyst is increased, and the life of the catalyst is shortened.

  Therefore, in the internal combustion engine 1, it is preferable that the opening / closing valve 52 of the resonator 5 is opened during the steady operation of the engine 2 (see FIG. 7). In such a configuration, when the open / close valve 52 of the resonator 5 is opened, the pressure wave in the exhaust passage 41 enters the resonator 5, thereby reducing the exhaust stirring action due to the exhaust pulsation. Then, the reaction between the catalyst and the exhaust is suppressed, and the increase in the catalyst bed temperature is suppressed. Thereby, there exists an advantage by which deterioration of a catalyst is suppressed and the lifetime of a catalyst is maintained.

  For example, in the modification of this embodiment, first, after the ignition start, it is determined whether or not the engine 2 is in a steady operation state (ST21) (see FIG. 7). In this determination step ST21, for example, when the accelerator opening (output value of the accelerator opening sensor) and the vehicle speed (output value of the vehicle speed sensor) are within a predetermined range, it is determined that the engine 2 is in a steady operation state. The When it is determined that the engine 2 is in a steady operation state, the open / close valve 52 of the resonator 5 is opened (ST22). Thereby, the stirring action of the exhaust due to the exhaust pulsation is mitigated, and the deterioration of the catalyst is suppressed. When it is not determined that the engine 2 is in the steady operation state, the open / close valve 52 of the resonator 5 is maintained in the current open / close state.

[Exhaust gas recirculation system]
The internal combustion engine 1 is preferably applied to, for example, a diesel engine having an exhaust gas recirculation device 7 (see FIG. 1). The exhaust gas recirculation device 7 includes a recirculation gas pipe 71, an oxidation catalyst 72, a cooling device 73, and an EGR (Exhaust Gas Recirculation) valve 74. The recirculation gas pipe 71 constitutes an EGR passage that communicates the exhaust port 23 and the intake port 22 of the engine 2. The oxidation catalyst 72 is disposed on the recirculation gas pipe 71 and on the exhaust port 23 side (upstream in the flow direction of the recirculation gas) from the cooling device 73, and soluble organic substances (SOF) contained in the recirculation gas, etc. Oxidize and purify. The cooling device 73 is disposed on the recirculation gas pipe 71 and cools the recirculation gas flowing into the recirculation gas pipe 71 from the exhaust port 23. The EGR valve 74 is a valve that adjusts the supply amount of the recirculation gas to the intake port 22. In this exhaust gas recirculation device 7, a part of the exhaust gas (recirculation gas) is taken out from the exhaust port 23 to be purified and cooled, and this exhaust gas is supplied to the intake port 22 and recirculated to the engine 2. Thereby, NOx emission amount is suppressed.

  In general, in an exhaust gas recirculation device, exhaust pulsation is one of the causes of a large variation in the amount of recirculated gas.

  Therefore, in the internal combustion engine 1, it is preferable that the on-off valve 52 is opened during exhaust gas recirculation (see FIGS. 1 and 8). In such a configuration, when the opening / closing valve 52 of the resonator 5 is opened, the pressure wave in the exhaust passage 41 enters the resonator 5, thereby reducing the amplitude of the exhaust pulsation. Then, the exhaust flow in the exhaust passage 41 is stabilized, and the amount of recirculated gas is made uniform. Thereby, there exists an advantage which the exhaust gas recirculation apparatus 7 functions appropriately, and a fuel consumption improves.

  For example, in this embodiment, after the ignition is started, it is determined whether or not the operating region of the engine 2 is in a region where exhaust gas recirculation is performed (ST31) (see FIG. 7). In this determination step ST21, for example, a region in which exhaust gas recirculation is performed is defined by a predetermined aptitude test. When there is an engine operating region in this region, the exhaust gas recirculation is performed in the operating region of the engine 2. It is determined that it is in the area. When it is determined that the operation region of the engine 2 is in a region where exhaust gas recirculation is performed, the open / close valve 52 of the resonator 5 is opened (ST32). Thereby, the amplitude of the exhaust pulsation is relaxed and the amount of recirculated gas is made uniform.

  As described above, the internal combustion engine according to the present invention is useful in that the warm-up property of the catalyst device can be improved in the configuration having the resonator.

1 is a configuration diagram illustrating an internal combustion engine according to an embodiment of the present invention. FIG. 2 is an arrangement configuration diagram showing a resonator of the internal combustion engine shown in FIG. 1. It is an expanded sectional view which shows the resonator of the internal combustion engine described in FIG. It is a flowchart which shows the effect | action of the internal combustion engine described in FIG. It is explanatory drawing which shows the effect | action of the internal combustion engine described in FIG. It is explanatory drawing which shows the effect | action of the internal combustion engine described in FIG. 7 is a flowchart showing a modification of the internal combustion engine shown in FIG. 1. 7 is a flowchart showing a modification of the internal combustion engine shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Engine 21 Cylinder bore 22 Intake port 23 Exhaust port 24 Fuel supply device 3 Intake system 31 Intake passage 32 Air filter 33 Throttle valve 34 Surge tank 4 Exhaust system 41 Exhaust passage 42 Catalytic device 5 Resonator 51 Resonator body 52 Opening / closing valve 6 Control system 61 ECU
62 Gas sensor 7 Exhaust gas recirculation device 71 Recirculation gas pipe 72 Oxidation catalyst 73 Cooling device 74 Valve

Claims (5)

An internal combustion engine comprising a catalyst device that is disposed on an exhaust passage of an engine and purifies exhaust gas, and a resonator that opens to the exhaust passage,
The internal combustion engine, wherein the resonator has an opening / closing valve that adjusts an opening area of the opening to the exhaust passage, and the opening / closing control of the opening / closing valve is performed based on a warm-up state of the catalyst device. .   The internal combustion engine according to claim 1, wherein the on-off valve opens when the warming-up of the catalyst device is not completed.   The internal combustion engine according to claim 1 or 2, wherein the on-off valve opens when an engine operating region is in a region where a decrease in engine torque due to exhaust pulsation can occur.   The internal combustion engine according to any one of claims 1 to 3, wherein the open / close valve opens during steady operation of the engine.   5. The open / close valve according to claim 1, wherein when the exhaust gas recirculation device is provided to supply a part of the exhaust gas to the intake port and recirculate to the engine, the open / close valve opens during exhaust gas recirculation. Internal combustion engine.

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