JP2012144205A - Hybrid vehicle and control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve defects in a one-way clutch type hybrid vehicle.SOLUTION: An engine 11 and a motor 12 used as a driving source of the vehicle are directly connected, and an exhaust shutter 26 is disposed on an upstream side of a catalyst 25 of an exhaust passage 24, and when fuel cut is required, fuel cut is carried out after the exhaust shutter 26 is closed so as to throttle an exhaust flow rate. Thus, an amount of unburned air flowing into the catalyst 25 at a high temperature just after fuel cut is drastically reduced, and reaction heat generated in the catalyst 25 just after fuel cut is drastically reduced, and deterioration of the catalyst 25 is suppressed. In the motor traveling mode for driving the vehicle only by the motor 12, the exhaust shutter 26 on the upstream side of the catalyst 25 is closed, and the amount of the unburned air discharged from the engine 11 and flowing into the catalyst 25 in the motor traveling mode can be drastically reduced, and a throttle valve 22 is opened to an opening larger than an idling opening, and the pump loss of the engine 11 is reduced, and fuel economy is improved.

Description

  The present invention relates to a hybrid vehicle in which an exhaust shutter is provided in an exhaust passage of an internal combustion engine and a control device for the internal combustion engine.

  When an exhaust shutter is provided in an exhaust passage of an internal combustion engine, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2009-156133) and Patent Document 2 (Japanese Patent Laid-Open No. 2005-299408), Some have an exhaust shutter on the upstream side of the catalyst, and some have an exhaust shutter on the downstream side of the catalyst.

  In Patent Document 1 in which an exhaust shutter is provided on the upstream side of the catalyst, when performing exhaust gas temperature increase control, the target idle rotation speed is determined according to the intake air temperature, the exhaust shutter on the upstream side of the catalyst is closed, and Idle operation is performed with the inflow of exhaust restricted.

  On the other hand, in Patent Document 2 in which an exhaust shutter is provided on the downstream side of the catalyst, the temperature increase of the catalyst is promoted by closing the exhaust shutter on the downstream side of the catalyst during the temperature raising operation and retaining hot exhaust gas around the catalyst. I have to.

JP 2009-156133 A JP-A-2005-299408

  However, in Patent Document 1, when the exhaust gas temperature raising control is performed, the temperature of the catalyst cannot be raised because the exhaust shutter on the upstream side of the catalyst is closed. The exhaust shutter does not close completely even when it is fully closed, and it is slightly opened to discharge part of the exhaust. If the catalyst cannot be heated during exhaust temperature rise control, it will flow out of the opening of the exhaust shutter. Exhaust gas cannot be purified with a catalyst, and emissions deteriorate.

  Further, in Patent Document 2, since the exhaust shutter on the downstream side of the catalyst is closed during the temperature raising operation, if the internal combustion engine speed increases and the exhaust gas flow rate increases during the temperature raising operation, the exhaust pressure in the exhaust passage increases. Thus, the exhaust gas residual rate (internal EGR rate) of the internal combustion engine becomes excessive, and there is a possibility that problems such as deterioration of the combustion state of the internal combustion engine may occur.

  Further, in a hybrid vehicle using an internal combustion engine and a motor together as a vehicle drive source, there is one in which the drive system is configured by a one-clutch system in order to simplify the configuration of the drive system. In such a one-clutch hybrid vehicle, since the internal combustion engine and the motor are directly connected, even when the operation (combustion) of the internal combustion engine is stopped in the motor travel mode in which the vehicle is driven only by the motor. The internal combustion engine is driven by the rotation of the motor. For this reason, air is sucked into the internal combustion engine during the motor travel mode, discharged without being burned, and continues to flow into the catalyst. As a result, the heat release of the catalyst is promoted during the motor travel mode, and the catalyst temperature decreases. As a result, the exhaust gas purification rate after the restart of the internal combustion engine decreases, and the emission deteriorates. In addition, since the internal combustion engine is rotated by the rotation of the motor during the motor travel mode, friction loss and pump loss of the internal combustion engine occur, and a part of the motor output is wasted, resulting in fuel efficiency. Will get worse.

  In addition, when a fuel cut request is generated during operation of the internal combustion engine due to a request for switching to the motor travel mode or when the vehicle is decelerating, an idle stop request, etc., the fuel injection to the internal combustion engine is cut and the internal combustion engine is operated (combustion) However, since unburned air containing a large amount of oxygen flows into the high-temperature catalyst immediately after the fuel cut, the reaction between the rich components (HC, CO, etc.) stored in the catalyst and oxygen Is promoted, the catalyst temperature rises instantaneously due to the heat of reaction, and the catalyst deteriorates.

  Furthermore, in recent years, in order to improve the fuel efficiency of the internal combustion engine, there is a tendency to downsize the internal combustion engine and frequently use a high load region with a small pump loss, but for an internal combustion engine that frequently uses such a high load region, When an EGR system that recirculates part of the exhaust gas to the intake side using the pressure difference between the intake side and the exhaust side is provided, the pressure difference between the intake side and the exhaust side becomes sufficiently small in a heavily used high load range. The amount of EGR cannot be secured.

  Accordingly, an object of the present invention is to solve at least one of the problems described above.

  In order to solve the above-mentioned problems, an invention according to claim 1 uses an internal combustion engine and a motor together as a drive source of a vehicle, and provides a throttle valve in an intake passage of the internal combustion engine, while providing an exhaust passage of the internal combustion engine. In a hybrid vehicle provided with a catalyst for exhaust purification, and configured to drive the internal combustion engine so that the internal combustion engine is rotated by rotation of the motor in a motor travel mode in which the vehicle is driven only by the motor. An exhaust shutter provided on the upstream side of the catalyst in the exhaust passage and capable of opening and closing; and a control means for opening the throttle valve to an opening larger than an idle opening and closing the exhaust shutter during the motor travel mode; It is set as the structure provided with.

  As described above, in the conventional one-clutch hybrid vehicle, the catalyst temperature is lowered by the unburned air discharged from the internal combustion engine driven by the rotation of the motor during the motor running mode. Therefore, the exhaust gas purification rate after restarting the internal combustion engine is reduced. In addition, since the internal combustion engine is rotated by the rotation of the motor during the motor travel mode, friction loss and pump loss of the internal combustion engine occur, and a part of the motor output is wasted, resulting in fuel efficiency. Will get worse.

  On the other hand, in the invention according to claim 1, the pump loss of the internal combustion engine can be reduced and the exhaust shutter on the upstream side of the catalyst is closed by opening the throttle valve to an opening larger than the idle opening during the motor traveling mode. Therefore, it is possible to prevent or reduce unburned air discharged from the internal combustion engine during the motor travel mode from flowing into the catalyst, thereby suppressing a decrease in the catalyst temperature, improving fuel consumption and exhausting the internal combustion engine after restarting. Improve the purification rate.

  In this case, as in the second aspect, the valve overlap of the internal combustion engine (a period during which both the intake and exhaust valves are open) is increased and the exhaust shutter is closed during the motor travel mode by the variable valve device. good. Even if the valve overlap is increased during the motor running mode, the effect of reducing the pump loss of the internal combustion engine can be obtained.

  Further, as in claim 3, an internal combustion engine comprising a control means for providing a catalyst for purifying exhaust gas in an exhaust passage of the internal combustion engine and executing fuel cut to stop fuel injection to the internal combustion engine in response to a fuel cut request The engine control device includes an exhaust shutter that can be opened and closed provided upstream of the catalyst in the exhaust passage, and the control means closes the exhaust shutter upstream of the catalyst when a fuel cut request is generated. It is recommended that the fuel cut be performed after the exhaust flow rate is reduced. Thus, if the exhaust shutter on the upstream side of the catalyst is closed before the fuel cut is started and the exhaust flow rate is reduced, the amount of unburned air (oxygen amount) flowing into the high-temperature catalyst immediately after the fuel cut can be greatly reduced. As a result, the reaction heat generated in the catalyst immediately after the fuel cut can be greatly reduced, and the catalyst temperature can be prevented from rising immediately after the fuel cut to suppress the deterioration of the catalyst.

  In this case, as in claim 4, when the fuel cut request is generated, the exhaust shutter on the upstream side of the catalyst is closed to the minimum opening, and the opening area when the exhaust shutter is at the minimum opening (fully closed) is It is good to comprise so that it may become smaller than the opening area at the time of the minimum opening degree (at the time of full closure). In this way, the amount of air flowing into the catalyst during the fuel cut can be surely reduced, and the exhaust gas purification rate after returning from the fuel cut can be improved by suppressing the decrease in the catalyst temperature during the fuel cut.

  Further, as in claim 5, when the warm-up request for the internal combustion engine and / or the catalyst is generated, the exhaust shutter on the downstream side of the catalyst is set within the range from the minimum opening to the intermediate opening. You may make it control according to driving | running conditions. In this way, when a warm-up request for the internal combustion engine or a warm-up request for the catalyst is generated, the exhaust pressure in the exhaust passage does not become too high while the hot exhaust gas stays around the catalyst. It becomes possible to adjust the exhaust flow rate flowing out from the opening of the exhaust shutter by adjusting the opening degree of the exhaust shutter, and while maintaining the warm-up performance, the exhaust gas residual rate (internal EGR rate) of the internal combustion engine is within an appropriate range. By controlling, deterioration of the combustion state of the internal combustion engine and the like can be prevented.

  In this case, the exhaust heat recovery means for recovering the exhaust heat may be provided on the upstream side of the exhaust shutter in the exhaust passage. In this way, exhaust heat can be efficiently recovered by the exhaust heat recovery means when the internal combustion engine is warmed up or when the catalyst is warmed up, and fuel efficiency can be improved.

  As described above, in recent years, in order to improve the fuel efficiency of the internal combustion engine, there is a tendency to downsize the internal combustion engine and frequently use a high load region with low pump loss. However, an internal combustion engine that frequently uses such a high load region. When the engine is equipped with an EGR device that recirculates part of the exhaust gas to the intake side using the pressure difference between the intake side and the exhaust side, the pressure difference between the intake side and the exhaust side becomes small in a heavily used high load range. Therefore, there is a possibility that a sufficient amount of EGR cannot be secured.

  As a countermeasure against this, in an internal combustion engine provided with an EGR device, an exhaust shutter is provided downstream of the connection port of the EGR passage in the exhaust passage, and the opening degree of the exhaust shutter is determined according to the required EGR amount. May be controlled. As the opening degree of the exhaust shutter becomes smaller, the exhaust pressure in the exhaust passage becomes higher, the pressure difference between the intake side and the exhaust side becomes larger, and the EGR amount increases. From this relationship, for example, as the required EGR amount increases, the exhaust shutter opening decreases, and as the required EGR amount increases, the pressure difference between the intake side and the exhaust side increases to increase the EGR amount. Control is possible, and an EGR amount corresponding to the required EGR amount can be secured even in an internal combustion engine that frequently uses a high load range.

  The invention according to claim 7 may be applied to an internal combustion engine that makes heavy use of a high load range. For example, the invention may be applied to an internal combustion engine with a supercharger (claim 8), and the number of cylinders is three. You may apply to the following internal combustion engines (Claim 9). In general, an internal combustion engine with a supercharger or an internal combustion engine with a small displacement of 3 cylinders or less often uses a high load region, so that the effect of applying the invention according to claim 7 is large.

FIG. 1 is a diagram schematically showing a configuration of a drive system of a one-clutch hybrid vehicle according to a first embodiment of the present invention. FIG. 2 is a flowchart showing a flow of processing of the exhaust shutter control program according to the first embodiment. FIG. 3 is a diagram schematically showing the configuration of the drive system of the one-clutch hybrid vehicle of the second embodiment. FIG. 4 is a flowchart showing the flow of processing of the exhaust shutter control program according to the second embodiment.

  Hereinafter, two Examples 1 and 2 which embody the form for implementing this invention are demonstrated.

A first embodiment of the present invention will be described with reference to FIGS.
First, the configuration of the drive system of a one-clutch hybrid vehicle will be described with reference to FIG.

  An engine 11 (internal combustion engine) such as a gasoline engine and a motor 12 are mounted as a vehicle drive source, and a crankshaft of the engine 11 and a rotation shaft of the motor 12 are directly connected. A rotation shaft of the motor 12 is detachably connected to an input shaft of an automatic transmission 14 such as a CVT through a clutch 13, an output shaft of the automatic transmission 14 is connected to a drive shaft 15, and the rotation thereof is differential gear. 16 is transmitted to the axle 17 via 16 and the wheel 18 is rotationally driven. The motor 12 is driven by electric power supplied from the battery 19.

  There are three types of travel modes: an engine / motor travel mode in which the vehicle is driven by both the engine 11 and the motor 12, an engine travel mode in which the vehicle is driven only by the engine 11, and a motor travel mode in which the vehicle is driven by only the motor 12. And the traveling mode is switched according to the traveling state and the state of charge of the battery 19. In any travel mode, the engine 11 and the motor 12 rotate integrally. In the motor travel mode, the operation (combustion) of the engine 11 is stopped, but the engine 11 is rotated by the rotation of the motor 12. The

  A throttle valve 22 is provided in the intake passage 21 of the engine 11, and the throttle valve 22 is opened and closed by a motor 23 to electronically control the opening degree (throttle opening degree) of the throttle valve 22.

  On the other hand, an exhaust purification catalyst 25 is provided in the exhaust passage 24 of the engine 11, an exhaust shutter 26 is provided upstream of the catalyst 25 in the exhaust passage 24, and the exhaust shutter 26 is an actuator such as a motor. 27 is driven to open and close. The exhaust shutter 26 only needs to be switched at least between a fully open position (maximum opening) and a fully closed position (minimum opening), and of course, the opening is switched over three stages or continuously. Also good.

  The exhaust shutter 26 is not completely closed even in the fully closed position, and is slightly opened to discharge a part of the exhaust. However, the exhaust shutter 26 has an opening area at the minimum opening (when fully closed). The throttle valve 22 is configured to be smaller than the opening area at the minimum opening (when fully closed).

  The control device 28 that controls the drive system of the hybrid vehicle described above is composed of one or a plurality of microcomputers, and switches the travel mode according to the travel state and the state of charge of the battery 19, and according to the travel mode. The engine 11, the motor 12, the clutch 13, and the automatic transmission 14 are controlled to control the driving state of the vehicle. Further, the control device 28 functions as control means in the claims, and controls the opening / closing operation of the exhaust shutter 26 by executing an exhaust shutter control program of FIG.

  By the way, when driving in the driving mode (engine / motor driving mode or engine driving mode) for driving the engine 11, when switching to the motor driving mode in which the vehicle is driven only by the motor 12, a fuel cut request is generated. Then, the fuel cut for stopping the fuel injection to the engine 11 is executed to stop the operation (combustion) of the engine 11. In addition, a fuel cut request may be generated during operation of the engine 11. For example, there are (1) fuel cut at deceleration, (2) fuel cut at high speed when the engine speed exceeds the allowable speed, and (3) fuel cut at idle stop. If unburned air containing a large amount of oxygen flows into the high-temperature catalyst 25 immediately after these fuel cuts, the reaction between the rich components (HC, CO, etc.) stored in the catalyst 25 and oxygen is promoted. The catalyst temperature rises instantaneously due to the reaction heat, and the catalyst 25 deteriorates.

  As a countermeasure, in the first embodiment, when a fuel cut request is generated, the fuel cut is executed after the exhaust shutter 26 on the upstream side of the catalyst 25 is closed to the minimum opening and the exhaust flow rate is reduced. . Thus, if the exhaust shutter 26 on the upstream side of the catalyst 25 is closed to the minimum opening degree before the fuel cut is started and the exhaust flow rate is reduced, the amount of unburned air (oxygen amount) flowing into the high temperature catalyst 25 immediately after the fuel cut. ) Can be greatly reduced. As a result, the reaction heat generated in the catalyst 25 immediately after the fuel cut can be significantly reduced, and the catalyst temperature can be prevented from rising immediately after the fuel cut, and the deterioration of the catalyst 25 can be suppressed.

  In the first embodiment, when the fuel cut request is generated, the exhaust shutter 26 on the upstream side of the catalyst 25 is closed to the minimum opening, but the opening area when the exhaust shutter 26 is at the minimum opening (when fully closed) is the throttle valve. Since the opening area is smaller than 22 at the minimum opening (when fully closed), the amount of air flowing into the catalyst 25 immediately after the fuel cut can be reliably reduced.

  The opening degree at which the exhaust shutter 26 is closed when the fuel cut request is generated is not limited to the minimum opening degree, and may be a predetermined opening degree slightly larger than that, or when the fuel cut request is generated. The opening degree at which the exhaust shutter 26 is closed may be changed according to the engine operating state such as the engine rotation speed and the intake air amount.

  During the motor travel mode, the engine 11 is rotated by the rotation of the motor 12 and the intake air continues to be discharged from the engine 11 without being burned. Therefore, the unburned air discharged from the engine 11 during the motor travel mode is the catalyst. If it continues to flow into the engine 25, the catalyst 25 is cooled and the catalyst temperature decreases, and the exhaust gas purification rate after restarting the engine 11 decreases. Moreover, when the engine 11 is rotated by the rotation of the motor 12 during the motor travel mode, a pump loss or a pump loss of the engine 11 occurs, and a part of the output of the motor 12 is wasted. The fuel consumption will deteriorate.

  Therefore, in the first embodiment, during the motor travel mode, the exhaust shutter 26 on the upstream side of the catalyst 25 is maintained at the minimum opening, and the throttle valve 22 is opened to a predetermined opening larger than the idle opening. I am doing so. If the exhaust shutter 26 on the upstream side of the catalyst 25 is kept closed at the minimum opening during the motor travel mode, the amount of unburned air discharged from the engine 11 during the motor travel mode flows into the catalyst 25. It can be greatly reduced, the catalyst temperature can be suppressed from decreasing, and the exhaust gas purification rate after restarting the engine 11 can be improved.

  Note that the opening degree of closing the exhaust shutter 26 during the motor travel mode is not limited to the minimum opening degree, and may be a predetermined opening degree slightly larger than that, or the engine rotation speed during the motor travel mode, The opening degree of the exhaust shutter 26 may be changed according to the engine operating state such as the intake air amount.

  Further, in the first embodiment, the pump loss of the engine 11 can be reduced and the fuel consumption can be improved by opening the throttle valve 22 to a predetermined opening larger than the idle opening during the motor traveling mode. Here, the opening degree of the throttle valve 22 may be set to an opening degree at which the negative pressure disappears (or becomes sufficiently small). Therefore, even if the throttle valve 22 is opened to the fully opened position (maximum opening degree). good.

  When a variable valve device that changes at least one of the valve timing, the valve lift amount, and the operating angle of the engine 11 is mounted, the valve overlap ( The period during which both the intake and exhaust valves are open may be increased. Even if the valve overlap is increased during the motor running mode, the effect of reducing the pump loss of the engine 11 can be obtained. Here, as a method of increasing the valve overlap, the intake valve timing may be advanced, the exhaust valve timing may be retarded, or the lift amount or the working angle may be increased. Note that only one of valve overlap increase control and throttle valve 22 opening control may be performed during the motor travel mode, or a combination of both may be performed.

  Further, even in a travel mode other than the motor travel mode, a fuel cut is executed during deceleration of the engine 11 or at a high speed during the operation of the engine 11, but unburned air exhausted from the engine 11 during these fuel cuts. If it continues to flow into the catalyst 25, the catalyst 25 is cooled and the catalyst temperature decreases, and the exhaust gas purification rate after fuel cut recovery (after restarting injection) decreases.

  Therefore, in the first embodiment, the exhaust shutter 26 on the upstream side of the catalyst 25 is kept in the closed state when the fuel cut is performed in a travel mode other than the motor travel mode. As a result, the amount of unburned air exhausted from the engine 11 during the fuel cut flows into the catalyst 25 can be greatly reduced, and a decrease in the catalyst temperature can be suppressed, and the exhaust after the fuel cut is restored (after restarting the injection). The purification rate can be improved. The exhaust shutter 26 may be closed to a predetermined opening that is slightly opened from the minimum opening during the fuel cut, or the exhaust shutter according to the engine operating state such as the engine speed and the intake air amount during the fuel cut. The closing opening degree of 26 may be changed.

  The exhaust shutter control of the first embodiment described above is executed by the control device 28 as follows according to the exhaust shutter control program of FIG.

  The exhaust shutter control program of FIG. 2 is repeatedly executed at a predetermined period during the power-on period of the control device 28, and plays a role as control means in the claims. When this program is started, first, at step 101, it is determined whether or not a fuel cut request has occurred. The fuel cut request is generated when a request for switching to the motor travel mode is generated during the operation of the engine 11, when the engine speed exceeds the allowable speed during deceleration, or when an idle stop request is generated. One of them. If it is determined in step 101 that a fuel cut request has not occurred, the process proceeds to step 107, where the exhaust shutter 26 is driven or maintained at the fully open position, and this program ends.

  On the other hand, if it is determined in step 101 that a fuel cut request has been generated, the process proceeds to step 102 to drive the exhaust shutter 26 to the fully closed position (minimum opening). Thereafter, the process proceeds to step 103 and waits until the exhaust shutter 26 is fully closed.

  Thereafter, after the fully closing operation of the exhaust shutter 26 is completed, the routine proceeds to step 104 where the fuel cut is executed to stop the operation (combustion) of the engine 11. During the fuel cut, the exhaust shutter 26 is maintained at the fully closed position (minimum opening).

  Thereafter, the process proceeds to step 105, where it is determined whether or not it is a motor travel mode in which the vehicle is driven only by the motor 12, and if it is determined not to be the motor travel mode, this program is terminated as it is.

  On the other hand, if it is determined in step 105 that the motor travel mode is set, the process proceeds to step 106 where the throttle valve 22 is opened to a predetermined opening larger than the idle opening, and the pump of the engine 11 in the motor travel mode is opened. Reduce loss.

  In the first embodiment described above, when a fuel cut request is generated, the fuel cut is executed after the exhaust shutter 26 on the upstream side of the catalyst 25 is closed and the exhaust flow rate is reduced. The amount of unburned air (oxygen amount) flowing into the high temperature catalyst 25 can be greatly reduced, the reaction heat generated in the catalyst 25 immediately after the fuel cut can be greatly reduced, and the catalyst temperature can be increased immediately after the fuel cut. Thus, the deterioration of the catalyst 25 can be suppressed.

  Moreover, in the first embodiment, the exhaust shutter 26 on the upstream side of the catalyst 25 is closed and the throttle valve 22 is opened to a predetermined opening larger than the idle opening in the motor traveling mode in which the vehicle is driven only by the motor 12. The amount of unburned air exhausted from the engine 11 during the motor travel mode can be greatly reduced, the decrease in the catalyst temperature can be suppressed, and the exhaust gas purification rate after restarting the engine 11 can be improved. In addition, the pump loss of the engine 11 can be reduced and the fuel consumption can be improved.

  Further, when the fuel cut is being performed in a travel mode other than the motor travel mode, the exhaust shutter 26 on the upstream side of the catalyst 25 is kept closed, so that the exhaust gas discharged from the engine 11 during the fuel cut is not yet discharged. The amount of combustion air flowing into the catalyst 25 can be greatly reduced, the decrease in the catalyst temperature can be suppressed, and the exhaust gas purification rate after returning from the fuel cut (after resuming injection) can be improved.

  Note that the technology for performing fuel cut after closing the exhaust shutter 26 on the upstream side of the catalyst 25 and reducing the exhaust flow rate when a fuel cut request is generated is limited to a one-clutch hybrid vehicle as shown in FIG. However, the present invention can also be applied to other types of hybrid vehicles, and can also be applied to vehicles having only the engine as the drive source of the vehicle.

  In the first embodiment, the exhaust shutter 26 is provided on the upstream side of the catalyst 25 in the exhaust passage 24. However, in the second embodiment of the present invention shown in FIGS. An exhaust shutter 31 is provided on the downstream side, and the exhaust shutter 31 is opened and closed by an actuator 32 such as a motor.

  Further, an exhaust heat recovery unit 33 (exhaust heat recovery means) that recovers exhaust heat is provided in the exhaust passage 24 upstream of the exhaust shutter 31. The exhaust heat recovery unit 33 is provided in a cooling water circulation circuit (not shown) of the engine 11 and increases the temperature of the cooling water by exchanging heat between the exhaust and the cooling water.

  The engine 11 is an engine that frequently uses a high load range with good fuel efficiency. For example, the engine 11 is an engine with a supercharger or a small displacement engine having three or less cylinders and is equipped with an EGR device 34. . The EGR device 34 includes an EGR passage 35 that recirculates part of the exhaust gas flowing through the exhaust passage 24 to the intake passage 21, and an EGR valve 36 that controls the amount of EGR flowing through the EGR passage 35. The position of the connection port 37 between the exhaust passage 24 and the EGR passage 35 may be anywhere as long as it is upstream of the exhaust shutter 31. In the configuration example of FIG. 3, the position of the connection port 37 of the EGR passage 35 is on the downstream side of the exhaust heat recovery device 33, but may be on the upstream side of the exhaust heat recovery device 33. It may be upstream. Other configurations are substantially the same as those of the first embodiment.

  In the second embodiment, when an engine warm-up request or a catalyst warm-up request is generated, the exhaust shutter 31 on the downstream side of the catalyst 25 is operated in an engine operating condition (range from a minimum opening to an intermediate opening). The exhaust shutter 31 is controlled so as to prevent the exhaust pressure in the exhaust passage 24 from becoming excessively high while retaining high-temperature exhaust gas on the catalyst 25 side in the exhaust passage 24 by controlling the engine according to the engine speed, the intake air amount, etc. The exhaust flow rate flowing out from the opening of the exhaust shutter 31 is adjusted by adjusting the opening degree.

  In recent years, in order to improve the fuel efficiency of the engine 11, there is a tendency to downsize the engine 11 and to frequently use a high load region with a small pump loss. When the EGR device 34 that recirculates part of the exhaust gas to the intake side using the pressure difference between the exhaust side and the exhaust side is provided, the pressure difference between the intake side and the exhaust side becomes small in the heavily used high load region in the conventional configuration. Therefore, there is a possibility that a sufficient amount of EGR cannot be secured.

  As a countermeasure, in the second embodiment, an exhaust shutter 31 is provided on the downstream side of the connection port 37 of the EGR passage 35 in the exhaust passage 24, and the opening degree of the exhaust shutter 31 is controlled according to the required EGR amount. ing. Generally, as the opening degree of the exhaust shutter 26 becomes smaller, the exhaust pressure in the exhaust passage 24 becomes higher, the pressure difference between the intake side and the exhaust side becomes larger, and the EGR amount increases. From such a relationship, for example, as the required EGR amount increases, the opening degree of the exhaust shutter 31 decreases, and as the required EGR amount increases, the pressure difference between the intake side and the exhaust side increases to increase the EGR amount. Thus, even in the engine 11 that makes heavy use of the high load range, the EGR amount corresponding to the required EGR amount can be secured.

  The exhaust shutter control of the second embodiment described above is executed by the control device 28 as follows according to the exhaust shutter control program of FIG.

  The exhaust shutter control program of FIG. 4 is repeatedly executed at a predetermined period during the power-on period of the control device 28, and plays a role as control means in the claims. When this program is started, first, in step 201, it is determined whether or not a catalyst warm-up request has been generated. If it is determined that a catalyst warm-up request has been generated, the process proceeds to step 204, where the exhaust gas is exhausted. The shutter 26 is driven to a small opening (or a minimum opening). At this time, the opening degree of closing the exhaust shutter 26 may be changed by a map or the like according to engine operating conditions (engine rotational speed, intake air amount, etc.).

  On the other hand, if it is determined in step 201 that a catalyst warm-up request has not been generated, the process proceeds to step 202, where it is determined whether an engine warm-up request has been generated, and an engine warm-up request has been generated. If it is determined, the process proceeds to step 205, where the target opening degree of the exhaust shutter 31 is mapped in accordance with the engine operating conditions (engine speed, intake air amount, etc.) at that time in the intermediate region of the adjustable range. Then, the process proceeds to step 207, and the exhaust shutter 31 is driven to the target opening set in step 205.

  If both of the above-described steps 201 and 202 are determined as “No”, that is, if it is determined that neither a catalyst warm-up request nor an engine warm-up request has occurred, the process proceeds to step 203 to request an EGR request. If it is determined that the EGR request has occurred, the process proceeds to step 206, where the target opening of the exhaust shutter 31 is set to the required EGR amount in the intermediate range of the adjustable range. Then, after setting with a map or the like, the process proceeds to step 207, where the exhaust shutter 31 is driven to the target opening set in step 206.

  On the other hand, if it is determined in step 203 that an EGR request is not generated, the process proceeds to step 206 to drive the exhaust shutter 26 to the fully open position (maximum opening).

  In the second embodiment described above, when the engine warm-up request is generated, the exhaust shutter 31 on the downstream side of the catalyst 25 is operated under the engine operating condition (engine rotation) in the range from the minimum opening to the intermediate opening. Therefore, when the engine warm-up request is generated, the exhaust passage 24 is allowed to stay in the exhaust passage 24 while retaining high-temperature exhaust gas on the catalyst 25 side. The exhaust flow rate flowing out from the opening of the exhaust shutter 31 can be adjusted by adjusting the opening degree of the exhaust shutter 31 so that the exhaust pressure inside the engine 11 does not become too high. It is possible to prevent the deterioration of the combustion state of the engine 11 by controlling the exhaust residual ratio (internal EGR ratio) within an appropriate range.

  Moreover, in the second embodiment, the exhaust heat recovery unit 33 that recovers the exhaust heat is provided on the upstream side of the exhaust shutter 31 in the exhaust passage 24. Therefore, the exhaust heat is recovered by the exhaust heat recovery unit 33 during warm-up. It can be collected efficiently and fuel efficiency can be improved.

  In the second embodiment, the exhaust shutter 31 is provided downstream of the connection port 37 of the EGR passage 35 in the exhaust passage 24, and the opening degree of the exhaust shutter 31 is controlled according to the required EGR amount. Therefore, even in the engine 11 that frequently uses a high load range with high fuel efficiency, it is possible to increase the EGR amount by increasing the pressure difference between the intake side and the exhaust side according to the required EGR amount, and according to the required EGR amount. The EGR amount can be secured.

  The technique for controlling the opening degree of the exhaust shutter 31 provided on the downstream side of the connection port 37 of the EGR passage 35 according to the required EGR amount is also applied to a configuration in which an exhaust shutter is provided on the upstream side of the catalyst 25. Can be implemented.

  Further, the technology described in the second embodiment is not limited to the one-clutch hybrid vehicle as shown in FIG. 1, but can be applied to other hybrid vehicles. Further, only the engine is used as a vehicle drive source. It is applicable also to the vehicle which uses.

  In addition, the present invention can be implemented with various modifications such as providing exhaust shutters on the upstream side and the downstream side of the catalyst 25, respectively, and combining the technique of the first embodiment and the technique of the second embodiment. Needless to say.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Motor, 13 ... Clutch, 14 ... Automatic transmission, 15 ... Drive shaft, 18 ... Wheel, 21 ... Intake passage, 22 ... Throttle valve, 23 ... Motor, 24 ... Exhaust passage, DESCRIPTION OF SYMBOLS 25 ... Catalyst for exhaust purification, 26 ... Exhaust shutter, 27 ... Actuator, 28 ... Control apparatus (control means), 31 ... Exhaust shutter, 32 ... Actuator, 33 ... Exhaust heat recovery device (exhaust heat recovery means), 34 ... EGR device, 35 ... EGR passage, 36 ... EGR valve, 37 ... connection port

Claims (9)

An internal combustion engine and a motor are used in combination as a drive source for the vehicle, and a throttle valve is provided in the intake passage of the internal combustion engine, while an exhaust purification catalyst is provided in the exhaust passage of the internal combustion engine, and the vehicle is driven only by the motor. In the hybrid vehicle that configures the drive system of the vehicle so that the internal combustion engine is rotated by the rotation of the motor in the motor travel mode,
An exhaust shutter provided on the upstream side of the catalyst in the exhaust passage and capable of opening and closing; and control means for opening the throttle valve to an opening larger than an idle opening and closing the exhaust shutter during the motor travel mode. A hybrid vehicle comprising: and. An internal combustion engine and a motor are used together as a drive source for the vehicle, and a variable valve device for changing the valve overlap of the internal combustion engine is provided, while an exhaust purification catalyst is provided in the exhaust passage, and the vehicle is driven only by the motor. In the hybrid vehicle that configures the drive system of the vehicle so that the internal combustion engine is rotated by the rotation of the motor in the motor travel mode,
An exhaust shutter provided on the upstream side of the catalyst in the exhaust passage and capable of opening and closing; and the variable valve device increases the valve overlap of the internal combustion engine and closes the exhaust shutter during the motor travel mode A hybrid vehicle comprising: a control means. In a control device for an internal combustion engine provided with a control means for providing a catalyst for exhaust purification in an exhaust passage of the internal combustion engine and executing fuel cut to stop fuel injection to the internal combustion engine in response to a fuel cut request,
An exhaust shutter provided on the upstream side of the catalyst in the exhaust passage and capable of opening and closing;
The control device of the internal combustion engine, wherein when the fuel cut request is generated, the control means executes the fuel cut after closing the exhaust shutter and reducing the exhaust flow rate. A throttle valve is provided in the intake passage of the internal combustion engine,
The control means closes the exhaust shutter to a minimum opening when a fuel cut request occurs,
4. The control device for an internal combustion engine according to claim 3, wherein an opening area of the exhaust shutter at a minimum opening is configured to be smaller than an opening area of the throttle valve at a minimum opening. In a control device for an internal combustion engine in which an exhaust purification catalyst is provided in an exhaust passage of the internal combustion engine,
An exhaust shutter provided on the downstream side of the catalyst in the exhaust passage and capable of opening and closing; and when the warm-up request for the internal combustion engine and / or the catalyst is generated, the exhaust shutter is moved from a minimum opening degree. A control means for controlling the internal combustion engine according to the operating conditions of the internal combustion engine in a range up to an intermediate opening.   6. The control apparatus for an internal combustion engine according to claim 5, wherein exhaust heat recovery means for recovering exhaust heat is provided upstream of the exhaust shutter in the exhaust passage. In the control device for an internal combustion engine provided with an EGR passage for recirculating a part of the exhaust gas flowing through the exhaust passage of the internal combustion engine to the intake passage of the internal combustion engine,
An exhaust shutter capable of opening and closing provided downstream of the connection port of the EGR passage in the exhaust passage;
And a control means for controlling the opening degree of the exhaust shutter according to the required EGR amount.   The control apparatus for an internal combustion engine according to claim 7, wherein the internal combustion engine is an internal combustion engine with a supercharger.   The control apparatus for an internal combustion engine according to claim 7 or 8, wherein the internal combustion engine is an internal combustion engine having three or less cylinders.

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