JP2004019519A - Control device of engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of performing motoring control in stopping an internal combustion engine while sufficiently keeping a function of catalyst for exhaust emission control disposed in an exhaust passage of the internal combustion engine, in operating and controlling an engine system having the internal combustion engine and a motor. <P>SOLUTION: An electronic control device 90 for wholly controlling an operation state of a hybrid engine system 1 throttles opening of a throttle valve 21a in cooperation with the motoring control in stopping the internal combustion engine 20 to reduce flow rate of fresh air flowing into the exhaust passage 22. This suppresses increase of an oxygen storage amount of three way catalyst in a catalytic converter 23 in response to the motoring control. As a result, silence and driveability in stopping the engine are improved, the superiority of the motoring control of scavenging the exhaust gas remaining in a combustion chamber is secured, and the generation of NOx in starting the engine next time can be suppressed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a hybrid engine having a plurality of drive sources including an internal combustion engine and an electric motor, and more particularly, to a control structure for improving the function of an exhaust purification catalyst provided in an exhaust passage of the internal combustion engine. The present invention relates to a device to be implemented.
[0002]
[Prior art]
A hybrid engine in which an internal combustion engine and an electric motor are combined as a plurality of drive sources has a function of appropriately transmitting the power generated from these drive sources to the outside while controlling the operating state of each drive source. If the hybrid engine system is used, for example, the output of the internal combustion engine is preferentially used in the operation region where the energy conversion efficiency due to engine combustion is high, and the output of the motor is preferentially used in the operation region where the energy conversion efficiency due to engine combustion is low. Control such as utilization can be performed. As a result, a vehicle equipped with a hybrid engine can significantly reduce the amount of fuel consumed and the amount of exhaust gas discharged during vehicle operation compared to a vehicle equipped with a conventional internal combustion engine.
[0003]
One of the controls that effectively utilize the function of the hybrid engine is a control (hereinafter referred to as motoring control) that causes an internal combustion engine that is in a non-combusting state when the engine is stopped to operate by a motor for a predetermined period of time (hereinafter referred to as motoring control). -210520). In general, when the operation of the internal combustion engine stops, a phenomenon (torque shock) in which the engine speed drops suddenly occurs after the fuel supply to the engine stops until the engine operation stops completely. Gives the driver a sense of incongruity.
[0004]
In the motoring control of the hybrid engine, when the operation of the internal combustion engine is stopped, the output shaft of the electric motor and the engine output shaft are connected, and after the fuel supply to the internal combustion engine is stopped, the engine speed is determined by the output of the electric motor. The engine will be completely stopped while gradually lowering. By performing the motoring control, the problem of torque shock is solved, and the quietness when the internal combustion engine is stopped is improved.
[0005]
Moreover, the following effects are also acquired by performing motoring control. After the internal combustion engine is stopped, a part of the exhaust gas remains in the combustion chamber. Generally, since the temperature in the exhaust passage is low when the engine is started, the exhaust purification catalyst provided in the exhaust passage is often not activated sufficiently. For this reason, if the exhaust gas remaining in the combustion chamber is discharged into the exhaust passage simultaneously with the restart of the engine operation after the engine is stopped, the exhaust gas is exhausted to the outside through the exhaust purification catalyst, which may deteriorate the exhaust characteristics. . If motoring control is performed after exhausting fuel to the internal combustion engine and exhaust gas is completely exhausted from the combustion chamber, it is possible to prevent deterioration of exhaust characteristics immediately after resuming engine operation.
[0006]
[Problems to be solved by the invention]
By the way, when the motoring control is performed, the air in the intake passage directly enters the exhaust passage through the combustion chamber. Since the exhaust purification catalyst has a property of storing oxygen (O 2 storage capability), it stores a large amount of oxygen that has entered the exhaust passage by motoring control. Then, at the next engine start, the exhaust purification catalyst releases a large amount of oxygen, and this oxygen increases the amount of NOx in the exhaust.
[0007]
The present invention has been made in view of such circumstances, and an object of the present invention is to be provided in an exhaust passage of the internal combustion engine in order to control the operation of the engine system including the internal combustion engine and the motor. Another object of the present invention is to provide a control device capable of carrying out motoring control when the internal combustion engine is stopped while maintaining the function of the exhaust purification catalyst satisfactorily.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is provided in (1) an internal combustion engine, a motor, a power transmission mechanism for transmitting a rotational force generated by the motor to the internal combustion engine, and an exhaust passage of the internal combustion engine. A control device for controlling an engine system having an exhaust purification catalyst, wherein when the internal combustion engine is stopped, the driving force of the motor is transmitted to the internal combustion engine to operate the engine in a non-combustion state The gist of the present invention is to provide an engine stop control means for causing the engine to stop and an air inflow amount suppression means for suppressing the amount of air flowing into the exhaust purification catalyst in accordance with the operation of the engine in the non-combustion state.
[0009]
According to this configuration, by reducing the flow rate of fresh air flowing into the exhaust passage in conjunction with the operation of the motor, contact of fresh air with the exhaust purification catalyst even under conditions where the motor is operating. As a result, an increase in the oxygen storage amount of the exhaust purification catalyst is suppressed. As a result, the operation of the engine stop control means, that is, quietness and drivability when the engine is stopped is improved, and the exhaust gas purification at the next engine start is ensured while ensuring the operation of scavenging the exhaust gas remaining in the combustion chamber. The amount of NOx generated downstream of the catalyst for use can be suppressed.
[0010]
(2) Further, it is preferable that the air inflow amount suppressing means suppresses the amount of air flowing into the exhaust purification catalyst by increasing a passage resistance of an intake passage of the internal combustion engine.
[0011]
According to this configuration, it is possible to effectively suppress the inflow of excess air in the exhaust passage.
[0012]
(3) a recirculation passage that connects an upstream portion of the exhaust purification catalyst in the exhaust passage of the internal combustion engine and the intake passage, and recirculates a part of the exhaust gas flowing through the exhaust passage to the intake passage; An exhaust gas recirculation amount adjusting means for adjusting the amount of exhaust gas recirculated through the recirculation passage, and the air inflow amount suppressing means increases the amount of exhaust gas recirculated through the exhaust gas recirculation amount adjusting means, It is preferable to suppress the amount of air flowing into the exhaust purification catalyst.
[0013]
According to this configuration, as an operation of the engine stop control means, it is possible to obtain an effect of improving the quietness and drivability when the engine is stopped, and in particular, an effect of suppressing a decrease in engine temperature.
[0014]
(4) It is preferable that the air inflow amount suppression means suppresses the amount of air flowing into the exhaust purification catalyst by blocking a flow path of gas flowing into the exhaust purification catalyst.
[0015]
(5) The air flow rate suppression means includes an upstream-side passage opening / closing valve that opens and closes an upstream portion of the exhaust purification catalyst in the exhaust passage, and a downstream that opens and closes a downstream portion of the exhaust purification catalyst in the exhaust passage. It is preferable that the flow path of the gas flowing into the exhaust gas purification catalyst is shut off by closing the upstream side passage on-off valve and the downstream side on-off valve.
[0016]
According to this configuration, not only can the contact of oxygen with the exhaust purification catalyst be reliably and continuously blocked from the outside, but also a temperature drop of the catalyst can be suppressed.
[0017]
(6) The engine is automatically stopped according to the operating state of the engine system and the engine is manually stopped based on a command signal from the operation operation unit of the engine system. When the system performs the manual engine stop, it is preferable to shut off the flow path of the gas flowing into the exhaust purification catalyst by closing the upstream side passage on-off valve and the downstream side on-off valve.
[0018]
According to this configuration, the operation of the engine stop control means is not only improved in quietness and drivability when the engine is stopped, but also when the internal combustion engine is stopped for a long time, During the period up to the time, the contact of oxygen with the exhaust purification catalyst can be reliably and continuously suppressed, and the temperature reduction of the exhaust purification catalyst can be suppressed.
[0019]
In addition, said each structure can be combined as much as possible.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the control device of the present invention is applied to an in-vehicle hybrid engine system will be described.
[0021]
[Engine system structure and function]
As shown in FIG. 1, a hybrid engine system (hereinafter simply referred to as an engine system) 1 includes an internal combustion engine 20, a motor 30, a generator (generator) 40, a power split mechanism 50, a speed reducer 60, an inverter 70, a battery 80, An electronic control unit (ECU) 90 and the like are included as main components. The internal combustion engine 20 is a gasoline engine configured by arranging four cylinders A, B, C, and D in series. In the middle of the intake passage 21 of the internal combustion engine 20, a throttle valve 21a for controlling the flow rate (intake amount) of intake air is provided. Further, in the middle of the exhaust passage 22 of the internal combustion engine 20, an exhaust purification three-way catalyst (hereinafter referred to as a three-way catalyst) that purifies carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) in the exhaust gas. A catalytic converter 23 having a built-in). The internal combustion engine 20 applies a rotational force to the drive wheels 9 and 10 of the vehicle and drives the generator 40 to generate electric power. The motor 30 receives power supplied from the battery 80 or the generator 40 and functions to apply rotational force to the drive wheels 9 and 10. On the contrary, the motor 30 applies rotational force from the drive wheels 9 and 10 and the internal combustion engine 20. As a result, the battery 80 may function to generate power and supply power for charging to the battery 80.
[0022]
The crankshaft 24 of the internal combustion engine 20, the rotating shaft 31 of the motor 30, and the rotating shaft 41 of the generator 40 are connected to each other via a power split mechanism 50. The power split mechanism 50 uses a known planetary gear (not shown) to transmit the power (rotational force of the crankshaft 24) generated by the internal combustion engine 20 to the rotary shaft 31 of the motor 30 and the rotary shaft 41 of the generator 40. Divide and transmit.
[0023]
The rotation shaft 31 of the motor 30 is connected to the rotation shafts 9 a and 9 a of the drive wheels 9 and 10 via the speed reducer 60.
[0024]
In addition, the rotating shaft 31 and the crankshaft 24 of the motor 30 can be appropriately connected or disconnected. That is, even when the internal combustion engine 20 stops engine combustion, the crankshaft 24 can be rotated using the power generated by the motor 30.
[0025]
The ECU 90 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM 94, a timer counter, and the like. These units, an external input circuit including an A / D converter, A logic operation circuit configured to be connected to the output circuit by a bidirectional bus is provided. The ECU 90 inputs detection signals of various sensors (not shown) via an external input circuit, and based on these signals, grasps the operating states of the internal combustion engine 20, the motor 30, the battery 80, etc., and these elements 20, 30, 80 Various controls for optimizing the operating state of the engine system 1 are performed based on the operating state.
[0026]
The engine system 1 configured as described above properly transmits power (shaft torque) generated by the internal combustion engine 20 and the motor 30 to the drive wheels 9 and 10 of the vehicle as appropriate. The battery 80 is charged by converting energy generated as the vehicle decelerates into electric power.
[0027]
[Engine system operation]
Hereinafter, the operation of the engine system 1 will be described with a specific example.
[0028]
FIG. 2 shows how the power generated by the internal combustion engine 20 and the motor 30 and the power stored in the battery 80 are utilized according to the operating conditions of the engine system 1, focusing on the power and power transmission path. It is a schematic diagram demonstrated to. In each of FIGS. 2 (a), 2 (b), and 2 (c), a solid arrow indicates a power transmission path, and a broken arrow indicates a power transmission path.
(1) At system startup
When the engine system 1 is started, the internal combustion engine 20 is warmed up. At this time, part of the energy generated by the internal combustion engine 20 is converted into electric power via the generator 40 and stored in the battery 80 (FIG. 1). When the temperature of the cooling water of the internal combustion engine 20 exceeds a predetermined value (when the warm-up is completed), the operation of the internal combustion engine 20 is stopped.
(2) Starting and running at low speed
Under conditions where the thermal efficiency of the internal combustion engine 20 is low, such as when a vehicle equipped with the engine system 1 starts or runs at a low speed, the vehicle (drive wheels) preferentially uses the power generated by the motor 30. 9 and 10) are driven.
(3) During normal driving
When a vehicle equipped with the engine system 1 travels under normal conditions, the power generated by the internal combustion engine 20 is divided into an appropriate ratio by the power split mechanism by the power split mechanism. Control is performed such that the power (power directly transmitted from the shaft 24 to the speed reducer 60) and the power generated by the motor 30 cooperate with each other at an optimum ratio to drive the vehicle (drive wheels 9, 10).
[0029]
In the engine system 1 configured as described above, the vehicle is driven while controlling the sharing of the internal combustion engine 20 and the motor 30. Further, for example, since power supply from the internal combustion engine 20 is not required when the vehicle starts, it is possible to perform control for automatically stopping the internal combustion engine 20 when the vehicle is stopped. As a result, fuel consumption can be improved and total exhaust gas emission can be reduced.
[0030]
[Motoring control when the internal combustion engine is stopped]
In the engine system 1, when the internal combustion engine 20 is stopped, the crankshaft 24 is rotated using the power of the motor 30 after the fuel supply to each cylinder A, B, C, D is stopped (or before and after the stop). By doing so, the control (motoring control) which reduces the rotational speed of the crankshaft 24 gradually and leads to a complete stop is implemented.
[0031]
When the motoring control is performed, the power of the motor 30 is transmitted to the crankshaft 24 of the internal combustion engine 20 through the power split mechanism (see FIG. 3), and assists the rotational operation of the crankshaft 24. For this reason, a rapid decrease in the engine speed accompanying the stop of the internal combustion engine 20 is suppressed.
[0032]
Further, after the internal combustion engine 20 is stopped, if the exhaust gas remaining in each cylinder A, B, C, D is discharged to the exhaust passage 22 immediately after the next restart of operation, the three-way catalyst in the catalyst casing 23 is discharged. The amount of exhaust gas that passes through the casing 23 under conditions that have not yet been activated increases. After stopping the fuel supply to the internal combustion engine 20, each cylinder A, B, C, D is performed by performing motoring control until exhaust gas is completely discharged from the combustion chamber of each cylinder A, B, C, D. Since the exhaust gas remaining in the exhaust gas is scavenged, the exhaust characteristics when the operation of the internal combustion engine 20 is resumed are improved.
[0033]
By the way, when the motoring control is performed, when the crankshaft 24 of the internal combustion engine 20 in the non-combustion state rotates, the air (fresh air) in the intake passage 21 passes through the cylinders A, B, C, D to the exhaust passage. 22, and reaches the catalytic converter 23. Since the three-way catalyst has the property of storing oxygen (oxygen storage capability), it stores a large amount of oxygen that has entered the exhaust passage by motoring control. Then, the three-way catalyst releases a large amount of oxygen at the next engine start, and there is a concern that this oxygen increases the amount of NOx in the exhaust.
[0034]
Therefore, the engine system 1 reduces the opening of the throttle valve 21a together with the implementation of the motoring control (increases the passage resistance of the intake passage 21), thereby excessively supplying the exhaust passage 22 (catalytic converter 23). Control to suppress the inflow of air.
[0035]
Hereinafter, a specific procedure of control performed when the engine system 1 stops the operation of the internal combustion engine that is a component thereof will be described.
[0036]
FIG. 4 is a flowchart showing a control routine for engine stop control performed by the engine system 1. This routine is repeatedly executed at a predetermined cycle through the ECU 90 during operation of the internal combustion engine 20.
[0037]
When the processing shifts to this routine, the ECU 90 first determines in step S101 whether or not the current time is the timing when the engine system 1 starts shifting to the stop mode of the internal combustion engine 20. Here, the transition to the stop mode means a process in which the operating internal combustion engine 20 stops.
[0038]
In the engine system 1, for example, when any one of the following conditions (a) to (d) is satisfied, the internal combustion engine 20 shifts to the stop mode.
(A) When the vehicle equipped with the engine system 1 stops
(B) When a vehicle equipped with the engine system 1 decelerates
(C) When the required torque for the engine system 1 falls below a predetermined value
(D) When the driver stops the engine system 1 voluntarily by operating the ignition key or the like
If the determination in step S101 is affirmative, the ECU 90 moves the process to step S102, and if the determination is negative, the ECU 90 once exits this routine.
[0039]
In step S102, the ECU 90 sets conditions for performing motoring control. Here, for example, from the viewpoint of quietly stopping the internal combustion engine 20, in light of the current operating state of the engine system 1 (for example, the rotational speed and torque of the internal combustion engine 20), the motoring control period, the power supplied to the motor Set various implementation conditions such as amount and rate of change in power supply.
[0040]
In the subsequent step S103, motoring control is performed in accordance with the conditions set in step S102. Further, along with the motoring control, the opening degree of the throttle valve 21a is adjusted (throttle) to reduce the flow rate of fresh air flowing from the intake passage 21 into the exhaust passage 22 via the cylinders A, B, C, D. Implement control (new air volume reduction control).
[0041]
When the motoring control and the fresh air amount reduction control are completed, the ECU 90 once exits this routine.
[0042]
The ECU 90 of the engine system 1 that performs engine stop control according to such a control procedure reduces the flow rate of fresh air that flows into the exhaust passage 22 in accordance with the motoring control, thereby reducing the amount of air flowing into the catalytic converter 23. Suppress.
[0043]
Here, in the conventional control device, by performing the motoring control when stopping the internal combustion engine, the effect of suppressing the torque shock generated when the internal combustion engine stops and improving the silence and drivability, The exhaust gas remaining in the combustion chamber can be scavenged and sent to the three-way catalyst for purification. However, on the other hand, the air in the intake passage passes through the cylinders of the internal combustion engine in a non-combustion state and flows into the exhaust passage in large quantities, so that the three-way catalyst having oxygen storage ability holds excessive oxygen. It was. Since the oxygen storage capacity of a three-way catalyst tends to increase under high temperature conditions and decrease under low temperature conditions, especially when the internal combustion engine is shut down immediately after high-load operation continues, The original catalyst stores a large amount of oxygen, and the next time the engine is started, a phenomenon occurs in which it is released at once. As a result, there is a concern that the amount of NOx discharged downstream of the three-way catalyst increases.
[0044]
In this regard, in the engine stop control performed by the ECU 90 of the engine system 1, the fresh air flows into the three-way catalyst in the catalytic converter 23 by reducing the flow rate of fresh air flowing into the exhaust passage 22 in conjunction with the execution of the motoring control. Avoid contact. This improves the quietness and drivability when the engine is stopped, and ensures the superiority of motoring control such as scavenging the exhaust gas remaining in the combustion chamber, while reducing the amount of NOx generated at the next engine start. Can be suppressed.
[0045]
In the above-described embodiment, control for adjusting the opening of the throttle valve 21a is performed as the fresh air amount reduction control (see step S103 in FIG. 4). However, another control for reducing the flow rate of fresh air flowing from the intake passage 21 through the cylinders A, B, C, and D into the exhaust passage 22 may be performed.
[0046]
[Modification 1]
For example, as shown in FIG. 5, the exhaust gas recirculation passage (EGR passage) 100 that connects the intake passage 21 and the exhaust passage 22 and the flow rate of exhaust gas (EGR gas) that is opened and closed by electronic control and flows through the passage 100 are adjusted. A known EGR device is configured by adding an EGR valve 101 capable of performing the above operation to the engine system 1. If the control for opening the EGR valve 101 together with the motoring control is performed as a new air amount reduction control, at least the quietness and drivability when the engine is stopped are improved, and the next time the engine is started. In addition to suppressing the amount of NOx generated, it is also possible to suppress a decrease in engine temperature.
[0047]
[Modification 2]
For example, as shown in FIG. 6, a control valve 102 capable of electronically opening and closing can be provided upstream of the catalytic converter 23 in the exhaust passage 22 to adjust the flow rate of exhaust gas flowing into the catalytic converter 23 from the passage 22. An apparatus configuration that can be used is added to the engine system. And even if it implements the control which closes the control valve 102 with motoring control as fresh air quantity reduction control, there can exist an effect equivalent to the said embodiment, or an equivalent thing.
[0048]
[Modification 3]
Furthermore, as shown in FIG. 7, control valves 102 and 103 that can be opened and closed by electronic control are provided upstream and downstream of the catalytic converter 23 in the exhaust passage 22, and both control valves 102 and 103 are closed together with motoring control. You may make it speak. In this way, not only the inflow of gas from the upstream of the catalytic converter 23 is suppressed, but also the inflow of gas from the downstream of the catalytic converter 23 is suppressed.
[0049]
Control for closing the control valves 102 and 103 provided upstream and downstream of the catalytic converter 23 (hereinafter referred to as second fresh air amount reduction control) is, for example, control for throttle the throttle valve 21a in the intake passage 21, Compared to the control for opening the EGR valve 101 (hereinafter referred to as first fresh air amount reduction control), there is a disadvantage that the pressure in the exhaust passage 22 is increased, but the three-way catalyst in the catalyst casing 23 is securely and It can be continuously blocked from the outside, and the temperature drop in the catalyst casing 23 can also be suppressed.
[0050]
Therefore, under the condition that the internal combustion engine 20 is temporarily stopped during the operation of the engine system 1, the first fresh air amount reduction control is performed to suppress excessive oxygen inflow into the catalyst casing 23, and the engine Under conditions such that the operation of the system 1 is stopped (conditions where it is predicted that the operation of the internal combustion engine 20 will be stopped for a long period of time), the second new air amount reduction control is performed, and the three inside the catalyst casing 23 are controlled. The original catalyst may be cut off almost completely from the outside.
[0051]
Hereinafter, a specific control procedure for appropriately performing the first new air amount reduction control and the second new air amount reduction control will be described with reference to a flowchart.
[0052]
FIG. 8 is a flowchart showing a modification of the control routine for engine stop control performed by the engine system 1. This routine is repeatedly executed at a predetermined cycle through the ECU 90 during the operation of the internal combustion engine 20, as in the control routine for engine stop control described with reference to FIG.
[0053]
When the processing shifts to this routine, the ECU 90 first determines in step S201 whether or not the current time is the timing when the engine system 1 starts shifting to the first stop mode of the internal combustion engine 20. Here, as described above, “transition to the stop mode” means a process in which the operating internal combustion engine 20 stops. In this example, the “first stop mode” means that the engine system 1 automatically stops the internal combustion engine 20 in accordance with a command signal from the ECU 90. Specifically, (a) when the vehicle equipped with the engine system 1 stops, (b) when the vehicle equipped with the engine system 1 decelerates, (c) the required torque for the engine system 1 falls below a predetermined value. In this case, the engine system 1 shifts to the first stop mode.
[0054]
If the determination in step S201 is affirmative (if the current time is the transition timing to the first stop mode), the ECU 90 sets the conditions for performing the motoring control (step S201A), and Motoring control is performed according to the set conditions (step S201B). Further, along with the execution of the motoring control, the opening degree of the throttle valve 21a is throttled or the EGR valve 101a is opened (first fresh air amount reduction control) (step S201B).
[0055]
When the motoring control and the first new air amount reduction control are completed, the ECU 90 once exits this routine.
[0056]
On the other hand, if the determination in step S201 is negative (if the current time is not the timing for shifting to the first stop mode), the ECU 90 proceeds to step S202.
[0057]
In step S202, it is determined whether or not the current time is the timing when the engine system 1 starts to shift the internal combustion engine 20 to the second stop mode. Here, the “second stop mode” means that the internal combustion engine 20 is stopped based on a manual operation. Specifically, (d) when the driver operates the ignition key or the like to stop the engine system 1 spontaneously, the engine system 1 shifts to the first stop mode.
[0058]
If the determination in step S202 is negative (if the current time is not the timing for shifting to the second stop mode), the ECU 90 once exits this routine.
[0059]
On the other hand, if the determination in step S202 is affirmative (if the current time is the transition timing to the second stop mode), the ECU 90 sets conditions for performing the motoring control (step S202A). ), Motoring control is performed according to the set condition (step S202B). Further, with the execution of the motoring control, a control (second fresh air amount reduction control) for closing the control valves 102 and 103 provided upstream and downstream of the catalyst casing 23 is performed (step S201B).
[0060]
When the motoring control is completed, the ECU 90 once exits this routine.
[0061]
The control valves 102 and 103 remain closed until the next start of the internal combustion engine.
[0062]
According to such a control routine, it is predicted that the internal combustion engine 20 will be stopped for a long period of time by performing the first fresh air amount reduction control and the second new air amount reduction control separately. Under such conditions, the second new air amount reduction control can be performed together with the motoring control. By performing such control, not only when the internal combustion engine 20 is stopped, but also after the stop, the suppression of the flow of fresh air into the catalyst casing 23 and the heat retention in the catalyst casing 23 are combined. It can be carried out.
[0063]
In addition, the various fresh air amount reduction controls that are applied in the present embodiment, including the above-described modified examples, can be implemented appropriately selectively or in combination depending on the situation. For example, in conjunction with the implementation of the motoring control, the control valves 102 and 103 can be closed while the EGR valve 101 is in a half-open state.
[0064]
Further, the opening degree of the throttle valve 21a, the opening degree of the EGR valve 101, the target value and the changing speed of the opening degree of the control valves 102 and 103, etc. for the fresh air amount reduction control are determined when the engine is shifted to the stop mode. You may make it change according to 20 driving | running states (for example, engine speed or engine temperature).
[0065]
Further, when the engine system 1 starts shifting to the stop mode of the internal combustion engine 20, first, motoring control is performed independently for a predetermined period, and the exhaust gas scavenging from each cylinder A, B, C, D is performed. After the completion, motoring control and fresh air amount reduction control may be performed together.
[0066]
The engine system 1 is not limited to a system in which the internal combustion engine 20 and the motor 30 cooperate to apply power to the drive wheels of the mounted vehicle, and is sufficiently high for the internal combustion engine and the internal combustion engine in a non-combustion state. If it is an engine system provided with the motor which provides a torque, the control apparatus of this invention can be applied, and there can exist an effect equivalent to the said embodiment or an equivalent thing.
[0067]
In the present embodiment, the present invention is applied to an engine system including a gasoline engine as an internal combustion engine. However, the present invention is also applied to an engine system including another internal combustion engine such as a diesel engine. An effect equivalent to or equivalent to this can be achieved.
[0068]
Moreover, even if the control device of the present invention is applied to other driven objects as well as the engine system mounted on the vehicle as in the engine system 1, the effect equivalent to or equivalent to that of the above embodiment can be obtained. it can.
[0069]
Further, not only for a three-way catalyst, but also for an internal combustion engine (engine system) provided with another exhaust purification catalyst (for example, an oxidation catalyst or NOx storage reduction catalyst) provided in the exhaust passage of the internal combustion engine in the exhaust passage. However, by applying the control device of the present invention, an effect equivalent to or equivalent to that of the above embodiment can be achieved.
[0070]
【The invention's effect】
As described above, according to the control device of the present invention, the quietness and drivability when the engine is stopped are improved, and the action of scavenging the exhaust gas remaining in the combustion chamber is ensured while the engine is started next time. The amount of NOx generated downstream of the exhaust gas purification catalyst can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a hybrid engine system according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a stop control procedure for the internal combustion engine according to the embodiment;
FIG. 3 is a schematic diagram showing a power transmission path when motoring control is performed in the engine system according to the embodiment;
FIG. 4 is a flowchart showing a control procedure for engine stop control according to the embodiment;
FIG. 5 is a schematic configuration diagram showing a modification of the engine system according to the embodiment;
FIG. 6 is a schematic configuration diagram showing a modification of the engine system according to the embodiment;
FIG. 7 is a schematic configuration diagram showing a modification of the engine system according to the embodiment;
FIG. 8 is a flowchart showing another control procedure of the engine stop control according to the embodiment;
[Explanation of symbols]
1 Hybrid engine system (engine system)
9,10 Drive wheel
9a, 9a Rotating shaft
20 Internal combustion engine
21 Intake passage
21a Throttle valve
22 The same passage
22 Exhaust passage
23 Catalytic converter (including exhaust purification catalyst)
24 Crankshaft
30 motor
31 Rotating shaft
40 generator
41 Rotating shaft
50 Power split mechanism (composed of power transmission mechanism)
60 reducer
80 battery
90 Electronic control unit (ECU)
100 EGR passage
101 EGR valve
102 Control valve (upstream passage open / close valve)
103 Control valve (downstream passage opening / closing valve)

Claims (6)

An internal combustion engine;
A motor,
A power transmission mechanism for transmitting the rotational force generated by the motor to the internal combustion engine;
An exhaust purification catalyst provided in an exhaust passage of the internal combustion engine;
A control device for controlling an engine system having
Engine stop control means for transmitting the driving force of the motor to the internal combustion engine when the internal combustion engine is stopped, and operating the engine in a non-combustion state;
Air inflow amount suppression means for suppressing the amount of air flowing into the exhaust purification catalyst in accordance with the operation of the engine in the non-combustion state;
An engine system control device comprising: 2. The engine system according to claim 1, wherein the air inflow amount suppression unit suppresses an amount of air flowing into the exhaust purification catalyst by increasing a passage resistance of an intake passage of the internal combustion engine. Control device. A recirculation passage that communicates an upstream portion of the exhaust purification catalyst in the exhaust passage of the internal combustion engine and the intake passage, and returns a part of the exhaust flowing through the exhaust passage to the intake passage;
Exhaust gas recirculation amount adjusting means for adjusting the amount of exhaust gas recirculated through the recirculation passage;
With
2. The air inflow amount suppression means suppresses the amount of air flowing into the exhaust gas purification catalyst by increasing the amount of exhaust gas recirculated through the exhaust gas recirculation amount adjusting means. The engine system control device described. 2. The air inflow amount suppression means suppresses an amount of air flowing into the exhaust purification catalyst by blocking a flow path of gas flowing into the exhaust purification catalyst. Control device for engine system. The air flow rate suppression means is
An upstream side passage opening and closing valve for opening and closing an upstream portion of the exhaust gas purification catalyst in the exhaust passage;
A downstream-side passage opening / closing valve that opens and closes a downstream portion of the exhaust purification catalyst in the exhaust passage;
With
5. The engine system control device according to claim 4, wherein the upstream side passage on-off valve and the downstream side on-off valve are closed to shut off a flow path of the gas flowing into the exhaust purification catalyst. 6. While automatically stopping the engine according to the operating state of the engine system and manually stopping the engine based on a command signal from the operation unit of the engine system,
The air flow rate suppression means is
When the engine system performs the manual engine stop, the upstream passage opening / closing valve and the downstream opening / closing valve are closed to shut off the flow path of the gas flowing into the exhaust gas purification catalyst. 6. The engine system control apparatus according to claim 5, wherein:

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