JP2008155682A - Control device for internal combustion engine - Google Patents

Abstract

A control device for an internal combustion engine capable of efficiently performing temperature rise of a catalyst and charging / discharging of a battery by performing control in consideration of an operation state of the internal combustion engine.
A control device for an internal combustion engine controls a hybrid vehicle capable of distributing outputs from the internal combustion engine and an electric motor to driving force of the vehicle and charging / discharging of a battery. Specifically, the catalyst temperature increase control means executes catalyst temperature increase control for increasing the temperature of the catalyst, and the target charge amount changing means executes catalyst temperature increase control based on the load of the internal combustion engine. At this time, the target charge amount of the battery is changed from the reference target charge amount set at least when the catalyst temperature increase control is not being executed. As a result, it is possible to efficiently raise the temperature of the catalyst and charge / discharge the battery in accordance with the operating condition of the internal combustion engine. Therefore, fuel consumption can be improved and exhaust emission can be reduced.
[Selection] Figure 5

Description

  The present invention relates to a control device for an internal combustion engine that is applied to a hybrid vehicle and performs control for recovering a catalyst provided in an exhaust passage.

  Conventionally, the sulfur poisoning of the catalyst is recovered by executing control for raising the temperature of the catalyst provided in the exhaust passage (hereinafter referred to as “catalyst temperature raising control” or “sulfur poisoning recovery control”). Technology is known. For example, Patent Document 1 describes a technique for maintaining an engine output at a predetermined value or higher in a hybrid vehicle during sulfur poisoning recovery control. Patent Document 2 describes a technique for recovering an increase in engine output during sulfur poisoning recovery control using a motor included in a hybrid vehicle.

JP 2004-278465 A JP 2001-241341 A

  However, with the techniques described in Patent Documents 1 and 2 described above, it is difficult to efficiently charge and discharge the battery in the hybrid vehicle while appropriately performing sulfur poisoning recovery.

  The present invention has been made in order to solve the above-described problems, and by performing control in consideration of the operation state of the internal combustion engine, the temperature of the catalyst and the charging / discharging of the battery are efficiently performed. It is an object of the present invention to provide a control device for an internal combustion engine that can be used.

  In one aspect of the present invention, a control device for an internal combustion engine that controls a hybrid vehicle capable of distributing outputs from each of the internal combustion engine and the electric motor to driving force of the vehicle and charge / discharge of a battery is provided. Catalyst temperature rise control means for performing catalyst temperature rise control for raising the temperature of the catalyst provided in the exhaust passage of the engine, and the battery when the catalyst temperature rise control is executed based on the load of the internal combustion engine Target charge amount changing means for changing at least the target charge amount from a reference target charge amount that is set when the catalyst temperature increase control is not being executed.

  The control device for the internal combustion engine is preferably used for controlling a hybrid vehicle that can distribute the output from each of the internal combustion engine and the electric motor to the driving force of the vehicle and the charge / discharge of the battery. Specifically, the catalyst temperature increase control means executes catalyst temperature increase control for increasing the temperature of the catalyst in order to recover sulfur poisoning of the catalyst. The target charge amount changing means is set based on the load of the internal combustion engine when the target charge amount of the battery set when the catalyst temperature increase control is executed is at least when the catalyst temperature increase control is not executed. Change from the standard target charge amount. As a result, it is possible to efficiently raise the temperature of the catalyst and charge / discharge the battery in accordance with the operating condition of the internal combustion engine. Therefore, fuel consumption can be improved and exhaust emission can be reduced.

  In one aspect of the control apparatus for an internal combustion engine, the target charge amount changing means sets the target charge amount at the start of the catalyst temperature increase control when the load of the internal combustion engine is less than a first predetermined value. Then, the value is changed to a value smaller than the reference target charge amount. As a result, the catalyst temperature rise control can be started from a state in which the battery is relatively low. Therefore, the surplus output from the internal combustion engine is effectively supplied to the battery while the internal combustion engine is operated at a high output during the catalyst temperature rise control. Can be charged.

  Preferably, in the control device for an internal combustion engine, the target charge amount changing means sets the target charge amount after the start of the catalyst temperature increase control when the load of the internal combustion engine is less than a first predetermined value. The value can be changed to a value larger than the target charge amount at the start of the catalyst temperature increase control.

  Preferably, when the load of the internal combustion engine is less than a first predetermined value and the temperature at which the catalyst is to be heated by the catalyst temperature increase control is greater than or equal to a predetermined value, The target charge amount after the start of the catalyst temperature increase control is changed to a value that allows the internal combustion engine to be operated at a high output. As a result, the internal combustion engine can be operated at a high output in the catalyst temperature increase control, and the temperature characteristics of the catalyst from the low temperature range can be greatly improved.

  In another aspect of the control apparatus for an internal combustion engine, the target charge amount changing means has a load greater than or equal to a first predetermined value and a value greater than the first predetermined value. When it is less than the second predetermined value, an upper limit value having at least a value larger than the reference target charge amount is set, and the target charge amount after the start of the catalyst temperature increase control is set to the upper limit value and the reference target amount. Change to a value between the amount of charge. Thereby, it is possible to achieve both the temperature rise of the catalyst and the charge of the battery while suppressing the hunting of the state of charge of the battery during the catalyst temperature rise control.

  In another aspect of the control apparatus for an internal combustion engine, the target charge amount changing means is configured such that the load of the internal combustion engine is equal to or greater than a second predetermined value having a value larger than a first predetermined value. The target charge amount at the start of the catalyst temperature increase control is changed to a value larger than the reference target charge amount. As a result, the catalyst temperature increase control can be started from a state in which the battery is relatively charged. Therefore, the internal combustion engine is effectively assisted by the electric motor by effectively discharging the battery during the catalyst temperature increase control. be able to. That is, the requested output can be reliably output from the vehicle during the catalyst temperature increase control by the assist by the electric motor.

  Preferably, in the control device for an internal combustion engine, the target charge amount changing means is configured to detect the catalyst when the load of the internal combustion engine is equal to or greater than a second predetermined value having a value larger than a first predetermined value. The target charge amount after the start of the temperature increase control can be changed to a value smaller than the target charge amount at the start of the catalyst temperature increase control.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Vehicle configuration]
First, a hybrid vehicle to which the control device for an internal combustion engine according to the present embodiment is applied will be described with reference to FIG.

  FIG. 1 is a diagram illustrating a schematic configuration of the hybrid vehicle 10. The hybrid vehicle 10 mainly includes an axle 11, wheels 12, an ECU (Electronic Control Unit) 100, an engine (internal combustion engine) 200, motors MG1, MG2, a planetary gear 300, an inverter 400, and a battery 500. SOC sensor 600, accelerator opening sensor 700, and vehicle speed sensor 800 are provided. The hybrid vehicle 10 is configured as a so-called series / parallel hybrid vehicle.

  The axle 11 is a part of a power transmission system that transmits the power of the engine 200 and the motor MG2 to the wheels 12. The wheels 12 are wheels of the hybrid vehicle 10, and only the left and right front wheels are particularly shown in FIG. The engine 200 is configured by a gasoline engine or the like, and functions as a main power source of the hybrid vehicle 10. The detailed configuration of engine 200 will be described later.

  The motor MG1 is configured to function mainly as a generator for charging the battery 500 or a generator for supplying electric power to the motor MG2. Motor MG2 is configured to function mainly as an electric motor that assists the output of engine 200. These motors MG1 and MG2 are configured as, for example, synchronous motor generators, and include a rotor having a plurality of permanent magnets on the outer peripheral surface, and a stator wound with a three-phase coil that forms a rotating magnetic field. Planetary gear (planetary gear mechanism) 300 is configured to be able to distribute the output of engine 200 to motor MG1 and axle 11, and functions as a power split mechanism.

  Inverter 400 is a DC / AC converter that controls input / output of electric power between battery 500 and motors MG1 and MG2. For example, the inverter 400 converts the DC power extracted from the battery 500 into AC power, or supplies AC power generated by the motor MG1 to the motor MG2, and converts the AC power generated by the motor MG1 into DC power. It can be converted to and supplied to the battery 500.

  The battery 500 is a rechargeable storage battery configured to be able to function as a power source for driving the motor MG1 and the motor MG2. The SOC sensor 600 is a sensor configured to be able to detect the state of charge of the battery 500 (hereinafter simply referred to as “SOC (State Of Charge)”). The SOC sensor 600 is electrically connected to the ECU 100, and the SOC of the battery 500 is always grasped by the ECU 100.

  The accelerator opening sensor 700 is a sensor configured to detect the amount of depression of the accelerator pedal (accelerator opening) by the driver. A detection signal corresponding to the accelerator opening detected by the accelerator opening sensor 700 is supplied to the ECU 100. The vehicle speed sensor 800 is a sensor configured to be able to detect the speed (vehicle speed) of the hybrid vehicle 10. A detection signal corresponding to the vehicle speed detected by the vehicle speed sensor 800 is supplied to the ECU 100.

  The ECU 100 is an electronic control unit that includes an unshown CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory), and controls the entire operation of the hybrid vehicle 10. In the present embodiment, the ECU 100 mainly uses a target charge amount of the battery 500 (hereinafter referred to as “control target SOC”) and a driver's requested output (corresponding to the accelerator opening detected by the accelerator opening 700). Based on the above, the output from the engine 200, the charging of the battery 500 (regeneration by the motor MG1), and the discharging of the battery 500 (assisting the output of the engine 200 using the output of the motor MG2) are controlled. That is, the ECU 100 basically controls engine output and charging / discharging of the battery 500 so that the SOC of the battery 500 is maintained at the control target SOC while satisfying the driver's required output (hereinafter referred to as such The control is also referred to as “battery charge / discharge control”).

[Engine configuration]
Next, a specific configuration of the engine 200 described above will be described with reference to FIG.

  FIG. 2 is a diagram illustrating a schematic configuration of the engine 200. In FIG. 2, solid arrows indicate gas flows, and broken arrows indicate signal input / output. Moreover, the thick line in FIG. 2 has shown the channel | path (piping) through which gas passes.

  The engine 200 is configured as a V-type 6-cylinder engine in which three banks (cylinders) 8La and 8Ra are provided in each of the left and right banks (cylinder groups) 8L and 8R. The engine 200 is a device that generates power by burning a mixture of air and fuel supplied via an intake passage 3 and an intake manifold (not shown). The engine 200 is controlled by the control signals S8L and S8R supplied from the ECU 100, such as the fuel injection amount and the injection timing.

  An intercooler (IC) 5 and a throttle valve 6 are provided in the intake passage 3 for guiding intake air to the cylinders 8La and 8Ra. The intercooler 5 is a device that cools the intake air. The throttle valve 6 is controlled in throttle opening based on a control signal S 6 from the ECU 100, and controls the flow rate of intake air flowing through the intake passage 3. Further, in the intake passage 3, a compressor 4La of the turbocharger 4L and a compressor 4Ra of the turbocharger 4R are disposed.

  Further, exhaust passages 11L and 11R are connected to the banks 8L and 8R, respectively. A turbine 4Lb of the turbocharger 4L is disposed in the exhaust passage 11L, and a turbine 4Rb of the turbocharger 4R is disposed in the exhaust passage 11R. The exhaust passage 11L is provided with a start catalyst 12L, and the exhaust passage 11R is provided with a start catalyst 12R. For example, a three-way catalyst or the like can be used as the start catalysts 12L and 12R. Further, the exhaust passage 11L and the exhaust passage 11R join downstream of the start catalysts 12L and 12R. A NOx catalyst 16 is provided in the exhaust passage 11 on the downstream side of the joined portion. The NOx catalyst 16 is configured as a catalyst capable of purifying NOx.

  The ECU 100 executes bank control to recover the NOx catalyst 16 from sulfur poisoning. The bank control is a control for causing the NOx catalyst 16 to react by making one of the banks 8L and 8R lean burn and richly burning the other to make the air-fuel ratio of the exhaust gas supplied to the NOx catalyst 16 stoichiometric. is there. By executing such control, the temperature of the NOx catalyst 16 is raised and the sulfur poisoning is recovered. Bank control corresponds to catalyst temperature increase control in the present invention.

  Further, in the present embodiment, the ECU 100 performs a process of changing the control target SOC (target charge amount) of the battery 500 from the normal control target SOC. The normal control target SOC is a control target SOC that is set in a state where at least bank control or the like is not being executed, and corresponds to a reference target charge amount. Specifically, when bank control is executed, ECU 100 changes control target SOC from normal control target SOC based on the load of engine 200. As described above, the ECU 100 functions as a control device for an internal combustion engine in the present invention. Specifically, the ECU 100 functions as a catalyst temperature increase control unit and a target charge amount control unit in the present invention.

  In the above, the embodiment in which the ECU 100 executes both the control on the engine 200 and the control on the motors MG1, MG2, and the battery 500 has been described, but the present invention is not limited to this. In another example, when there are separate ECUs for controlling engine 200 and ECUs for controlling motors MG1, MG2, and battery 500, these ECUs cooperate to perform the control described above. Can be executed.

[Method of changing control target SOC]
Hereinafter, a method for changing the control target SOC in the present embodiment will be specifically described. In this embodiment, the ECU 100 changes the control target SOC from the normal control target SOC based on the load (engine output) of the engine 200 when bank control for recovering sulfur poisoning of the NOx catalyst 16 is executed. To do. The reason for such a change is as follows.

  The engine output at the time of bank control and the requested output by the driver do not necessarily match, and if there is a difference between the engine output and the requested output, it is desirable to compensate for this output difference by charging / discharging by the battery 500. That is, it can be said that the battery 500 needs to be charged or discharged in order to reliably output the required output from the hybrid vehicle 10 during bank control. Specifically, when the engine output is larger than the required output, the battery 500 is charged (that is, regenerated by the motor MG1), and when the engine output is smaller than the required output, the battery 500 is discharged ( That is, it is desirable to assist the motor MG2.

  Here, since the magnitude relationship between the engine output during bank control and the output requested by the driver changes depending on the engine output, the battery 500 should be charged or the battery 500 should be discharged accordingly. Will change. Therefore, in order to appropriately execute the bank control while satisfying the output requested by the driver (that is, to appropriately raise the temperature of the NOx catalyst 16), the battery 500 is appropriately charged according to the engine output. It can be said that it is desirable to set to. Therefore, in the present embodiment, the control target SOC set during bank control is changed from the normal control target SOC based on the engine output. As a result, the temperature rise of the NOx catalyst 16 and the charging / discharging of the battery 500 can be efficiently performed. In addition, it is possible to suppress hunting of SOC of battery 500 during bank control.

  More specifically, the control target SOC is changed as follows.

  If the engine output at the time of bank control is greater than the required output, a surplus output will be generated. In this case, in order to improve fuel consumption, it is desirable to charge the battery 500 with the surplus output effectively. That is, it is desirable that the SOC of the battery 500 has a margin (that is, it is desirable that the battery 500 is in a charged state that can be sufficiently charged). Here, for example, when the engine 200 is operating at a low output (when the load of the engine 200 is less than the first predetermined value), the engine output during bank control tends to be larger than the requested output.

  As described above, in the present embodiment, when the bank control is executed while the engine 200 is operating at a low output, the ECU 100 sets the control target SOC at the start of the bank control to a value smaller than the normal control target SOC. change. Further, after the bank control is started, ECU 100 further changes the control target SOC to a value larger than the control target SOC set at the start of bank control (for example, a value larger than the normal control target SOC). Thereby, since the bank control can be started from a state in which the SOC of the battery 500 is relatively low, the surplus output from the engine 200 is effectively charged to the battery 500 while the engine 200 is operated at a high output during the bank control. be able to. Therefore, the battery 500 can be effectively charged and the fuel consumption can be improved while appropriately raising the temperature of the NOx catalyst 16. In addition, it is possible to suppress hunting of SOC of battery 500 during bank control.

  Furthermore, when engine 200 is operating at medium power (when the load of engine 200 is equal to or greater than the first predetermined value and less than the second predetermined value having a value greater than the first predetermined value). However, the engine output during bank control tends to be larger than the required output. When the bank control is executed while the engine 200 is performing the medium power operation in this way, the ECU 100 determines that the upper limit value (hereinafter referred to as “control target SOC upper limit value”) having a value that is at least larger than the normal control target SOC. The control target SOC after the start of the bank control is changed to a value between the control target SOC upper limit value and the normal control target SOC. Thus, during bank control, it is possible to achieve both the temperature rise of the NOx catalyst 16 and the charging of the battery 500 while suppressing the hunting of the SOC of the battery 500.

  On the other hand, when the engine output during the bank control is smaller than the required output, the battery 500 is discharged and the output of the engine 200 is effectively assisted by the motor MG2 in order to satisfy the required output. Is desirable. That is, it is desirable that the SOC of the battery 500 is sufficient (that is, it is desirable that the battery 500 is in a charged state that can be sufficiently discharged). Here, for example, when the engine 200 is operating at a high output (when the load of the engine 200 is equal to or greater than the second predetermined value), the engine output during bank control tends to be smaller than the required output.

  As described above, in the present embodiment, when the bank control is executed when the engine 200 is operating at a high output, the ECU 100 sets the control target SOC at the start of the bank control to a value larger than the normal control target SOC. change. Further, after the bank control is started, the ECU 100 further changes the control target SOC to a value smaller than the control target SOC set at the start of the bank control. Thereby, since the bank control can be started from a state in which the SOC of the battery 500 is relatively high, the engine 200 can be effectively assisted by the motor MG2 by effectively discharging the battery 500 during the bank control. it can. That is, the requested output can be reliably output from the hybrid vehicle 10 by the assistance of the motor MG2. By performing the above control, the battery 500 can be effectively discharged while the NOx catalyst 16 is appropriately heated. In addition, it is possible to suppress hunting of SOC of battery 500 during bank control.

  Here, with reference to FIG. 3, a problem that may occur when the control target SOC is not changed (that is, when the control target SOC is maintained at the normal control target SOC) will be described.

  3A shows battery charge / discharge control performed during normal operation (when bank control is not being executed), and FIG. 3B shows battery charge / discharge control performed during bank control. Yes. In FIGS. 3A and 3B, the horizontal axis indicates time, and the vertical axis indicates SOC.

  In the battery charge / discharge control during normal operation, the SOC of the battery 500 is a predetermined region (a region where the control target SOC is generally defined as the center, specifically, the SOC indicated by the symbol A1 and the SOC indicated by the symbol A2. The engine 200 is driven, and regeneration by the motor MG1 or assistance by the motor MG2 is performed. For example, the engine 200 is operated at the required output, and the battery 500 is charged or discharged as necessary.

  Here, referring to FIG. 3A, when the SOC exceeds the control target SOC, the battery 500 is discharged (that is, assisted by the motor MG2). In this case, the SOC of the battery 500 is lowered. On the other hand, when the SOC is lower than the control target SOC, the battery 500 is charged (that is, regenerated by the motor MG1). In this case, the SOC of battery 500 increases. FIG. 3A shows that the change in the SOC of the battery 500 is slight and the SOC is maintained in a predetermined region defined by the control target SOC. Therefore, it can be said that it is not particularly necessary to change the control target SOC during normal operation.

  On the other hand, when the battery charge / discharge control is performed during the bank control, it can be seen that the SOC of the battery 500 is greatly hunted as shown in FIG. Specifically, it can be seen that the SOC of the battery 500 has greatly increased since the bank control was started at time t1. This is considered to be because a large surplus output was generated because the engine output was increased with the execution of bank control. Then, at time t2, the SOC of battery 500 reaches a limit (SOC is approximately 100%). Thereafter, it can be seen that the SOC of the battery 500 is greatly reduced. This is presumably because the SOC of the battery 500 has reached its limit, so that the engine 200 is assisted by discharging power from the battery 500 and the engine output is reduced. In this way, when the engine output decreases, it can be said that the temperature holding characteristic of the NOx catalyst 16 deteriorates.

  After that, at time t3, the SOC of the battery 500 reaches a predetermined region that is defined with the control target SOC as a center, and the reduction of the SOC ends. Then, after time t3, the SOC of battery 500 again increases. It should be noted that such increase and decrease of the SOC of the battery 500 (in other words, increase and decrease of the engine output) are repeatedly generated.

  When the phenomenon shown in FIG. 3B occurs, the temperature holding characteristic of the NOx catalyst 16 deteriorates, or the life of the battery 500 is shortened by hunting with a large SOC. Therefore, in this embodiment, control for suppressing deterioration of the temperature holding characteristic of the NOx catalyst 16 and SOC hunting is executed. Specifically, in this embodiment, the control target SOC is changed from the normal control target SOC, and bank control and battery charge / discharge control are executed.

  Here, with reference to FIG. 4, the change method of the control target SOC which concerns on this embodiment is demonstrated concretely.

  4A to 4C, the horizontal axis indicates time, and the vertical axis indicates SOC. 4A to 4C show changes in the control target SOC and the SOC of the battery 500 that are set during the low output operation, during the medium output operation, and during the high output operation, respectively.

  FIG. 4A shows the control target SOC and the like set during the low output operation. In this case, a bank control request is issued at time t10. At this time, the ECU 100 changes the control target SOC at the start of bank control (hereinafter referred to as “control start SOC”) to a value smaller than the normal control target SOC. The ECU 100 performs control to assist the motor MG2 by discharging the battery 500 while reducing the engine output. With this control, the SOC of battery 500 reaches the control start SOC at time t11. Therefore, ECU 100 starts bank control at time t11. At this time, the ECU 100 further changes the control target SOC after the start of the bank control to a value larger than the control start SOC (for example, a value larger than the normal control target SOC). After time t11, the ECU 100 performs control to increase the engine output and charge the battery 500. Thereby, at time t12, the SOC of battery 500 reaches the control target SOC. Thereafter, the SOC of the battery 500 is generally maintained at the control target SOC.

  The ECU 100 changes the control target SOC after the start of the bank control to a larger value when, for example, the temperature at which the NOx catalyst 16 should be raised by bank control is equal to or higher than a predetermined value. Specifically, ECU 100 changes control target SOC to a value that allows engine 200 to be operated at a high output. Thereby, the engine 200 can be operated at a high output in the bank control, and the temperature characteristics of the NOx catalyst from the low temperature range can be greatly improved. Hereinafter, the bank control as described above is referred to as “high output bank control”.

  FIG. 4B shows the control target SOC and the like set during the medium output operation. In FIG. 4B, a bank control request is issued at time t20. In this case, since it is during the medium output operation, the ECU 100 starts the bank control almost simultaneously with the request for the bank control without setting the control start SOC as described above. At this time, ECU 100 sets the control target SOC upper limit value, which is the upper limit value of the control target SOC, and sets the control target SOC to a value between the control target SOC upper limit value and the normal control target SOC. Then, the ECU 100 performs control for charging the battery 500. Thus, at time t21, the SOC of battery 500 reaches the control target SOC. Thereafter, the SOC of the battery 500 is generally maintained at the control target SOC.

  FIG. 4C shows the control target SOC and the like that are set during high-power operation. In this case, a bank control request is issued at time t30. At this time, the ECU 100 changes the control start SOC at the start of the bank control to a value larger than the normal control target SOC. Then, the ECU 100 performs control to increase the engine output and charge the battery 500. With this control, the SOC of the battery 500 reaches the control start SOC at time t31. At this time, the ECU 100 further changes the control target SOC after the start of the bank control to a value smaller than the control start SOC. After time t31, the ECU 100 performs control to assist the motor MG2 by discharging the battery 500. Thereby, at time t32, the SOC of battery 500 reaches the control target SOC. Thereafter, the SOC of the battery 500 is generally maintained at the control target SOC.

  By changing the control target SOC as described above, it is possible to efficiently increase the temperature of the NOx catalyst 16 and charge / discharge the battery 500 in accordance with the operating condition of the engine 200. Thereby, fuel consumption can be improved and exhaust emission can be reduced.

[Processing in this embodiment]
Next, processing executed in the present embodiment (processing performed in bank control and battery charge / discharge control) will be described with reference to the flowchart shown in FIG. This process is executed by the ECU 100.

  First, in step S101, the ECU 100 calculates a required output from the driver based on the accelerator opening and the vehicle speed. In this case, the ECU 100 obtains the accelerator opening from the accelerator opening sensor 700 and also obtains the vehicle speed from the vehicle speed sensor 800 to calculate the required output. Then, the process proceeds to step S102.

  In step S102, the ECU 100 determines whether there is a bank control request for recovery from sulfur poisoning. For example, the ECU 100 determines whether or not the bank control is to be executed based on the elapsed time or the intake air amount since the previous bank control was executed. If there is a bank control request (step S102; Yes), the process proceeds to step S103. If there is no bank control request (step S102; No), the process exits the flow.

  In step S103, the ECU 100 determines whether or not the engine 200 is currently operating at a low output. In this case, ECU 100 determines whether the engine output is less than the first predetermined value. When the low output operation is performed (step S103; Yes), the process proceeds to step S104, and when the low output operation is not performed (step S103; No), the process proceeds to step S109.

  In step S104, the ECU 100 issues an instruction to decrease the engine output, and the process proceeds to step S105. In step S105, the ECU 100 adjusts the balance of the battery 500 until the control start SOC. Specifically, ECU 100 adjusts the SOC by discharging battery 500. The reason why the processes in steps S104 and S105 are performed is as follows. In the situation where the above processing is performed, the engine 200 is operating at a low output, so the ECU 100 changes the control start SOC to a value smaller than the normal control target SOC. In this case, the ECU 100 performs control to assist the motor MG2 by discharging the battery 500 and reducing the engine output so that the SOC of the battery 200 becomes the control start SOC. This is because the bank control is started from a state where the SOC of the battery 500 is relatively low, so that the engine 200 is operated at a high output during the bank control, and the surplus output from the engine 200 is effectively charged to the battery 500. Because. When the processes in steps S104 and S105 are completed, the process proceeds to step S106.

  In step S106, the ECU 100 starts high-power bank control in order to prioritize the temperature increase of the NOx catalyst 16. This is for greatly improving the temperature characteristics of the NOx catalyst from the low temperature range. When the above process ends, the process proceeds to step S107.

  In step S107, ECU 100 sets a control target SOC after the start of bank control. In this case, ECU 100 changes the control target SOC after the start of bank control to a value larger than the control start SOC. For example, the ECU 100 sets the control target SOC after the start of the bank control to a value that is at least larger than the normal control target SOC and is capable of operating the engine 200 at a high output. Then, the process proceeds to step S108. In step S108, the ECU 100 continues the bank control with the control target SOC. Then, the process exits the flow.

  On the other hand, when the engine 200 is not performing the low output operation (step S103; No), in step S109, the ECU 100 determines whether or not the engine 200 is currently performing the medium output operation. In this case, the ECU 100 determines whether or not the engine output is greater than or equal to the first predetermined value and less than the second predetermined value. When the medium output operation is performed (step S109; Yes), the process proceeds to step S110. When the medium output operation is not performed (step S109; No), the process proceeds to step S113.

  In step S110, the ECU 100 starts bank control. In this case, since engine 200 is performing a medium output operation, ECU 100 starts bank control almost simultaneously with a request for bank control without setting the control start SOC as described above. Then, the process proceeds to step S111.

  In step S111, the ECU 100 sets a control target SOC upper limit value and a control target SOC for bank control. Specifically, ECU 100 sets a value larger than at least the normal control target SOC as the control target SOC upper limit value, and sets the control target SOC to a value between the control target SOC upper limit value and the normal control target SOC. To do. This is because, during bank control, the hunting of the SOC of the battery 500 is suppressed, and the temperature rise of the NOx catalyst 16 and the charging of the battery 500 are compatible. Then, the process proceeds to step S112. In step S112, the ECU 100 continues the bank control with the control target SOC. Then, the process exits the flow.

  On the other hand, when the engine 200 is not performing the medium output operation (step S109; No), that is, when the engine output is equal to or greater than the second predetermined value, it can be said that the engine 200 is performing the high output operation. In this case, in step S113, the ECU 100 issues an instruction to increase the engine output, and the process proceeds to step S114. In step S114, the ECU 100 adjusts the balance of the battery 500 until the control start SOC. Specifically, ECU 100 adjusts the SOC by charging battery 500. The reason why the processes in steps S113 and S114 are performed is as follows. In the situation where the above processing is performed, the engine 200 is performing a high-power operation, so the ECU 100 changes the control start SOC to a value larger than the normal control target SOC. In this case, the ECU 100 performs control to increase the engine output and charge the battery 500 so that the SOC of the battery 200 becomes the control start SOC. Such control is performed by starting the bank control from a state in which the SOC of the battery 500 is relatively high, thereby effectively discharging the battery 500 during the bank control, thereby appropriately assisting the engine 200 by the motor MG2. It is to do. When the processes in steps S113 and S114 are completed, the process proceeds to step S115.

  In step S115, the ECU 100 starts bank control. Then, the process proceeds to step S116. In step S116, ECU 100 sets a control target SOC after the start of bank control. In this case, ECU 100 changes the control target SOC after the start of bank control to a value smaller than the control start SOC. Then, the process proceeds to step S117. In step S117, ECU 100 continues the bank control with the control target SOC. Then, the process exits the flow.

  By executing the processing as described above, it is possible to efficiently increase the temperature of the NOx catalyst 16 and charge / discharge of the battery 500 according to the operating state of the engine 200, and to improve fuel efficiency. Exhaust emissions can be reduced.

1 shows a schematic configuration of a hybrid vehicle to which an internal combustion engine control device according to an embodiment is applied. 1 shows a schematic configuration of an engine according to the present embodiment. It is a figure for demonstrating the malfunction which may occur when not changing control target SOC. It is a figure for demonstrating the change method of control target SOC which concerns on this embodiment. It is a flowchart which shows the process which concerns on this embodiment.

Explanation of symbols

3 Intake passage 4L, 4R Turbocharger 8L, 8R Bank (cylinder group)
11, 11L, 11R Exhaust passage 12L, 12R Start catalyst 16 NOx catalyst 100 ECU
200 engine (internal combustion engine)
500 Battery MG1, MG2 Motor

Claims (7)

In a control device for an internal combustion engine that controls a hybrid vehicle that can distribute the output from each of the internal combustion engine and the electric motor to driving force of the vehicle and charge / discharge of the battery,
Catalyst temperature rise control means for performing catalyst temperature rise control for raising the temperature of the catalyst provided in the exhaust passage of the internal combustion engine;
Based on the load of the internal combustion engine, the target charge amount of the battery when the catalyst temperature increase control is executed is changed from at least a reference target charge amount set when the catalyst temperature increase control is not executed A control unit for an internal combustion engine, comprising:   The target charge amount changing means changes the target charge amount at the start of the catalyst temperature increase control to a value smaller than the reference target charge amount when the load of the internal combustion engine is less than a first predetermined value. The control apparatus for an internal combustion engine according to claim 1, wherein:   The target charge amount changing means uses the target charge amount after the start of the catalyst temperature increase control as the target charge at the start of the catalyst temperature increase control when the load of the internal combustion engine is less than a first predetermined value. 3. The control device for an internal combustion engine according to claim 1, wherein the control device is changed to a value larger than the amount.   When the load of the internal combustion engine is less than a first predetermined value and the temperature at which the catalyst is to be heated by the catalyst temperature increase control is greater than or equal to a predetermined value, the target charge amount changing means The control of the internal combustion engine according to any one of claims 1 to 3, wherein the target charge amount after the start of the temperature raising control is changed to a value capable of operating the internal combustion engine at a high output. apparatus.   The target charge amount changing means is at least the reference when the load of the internal combustion engine is greater than or equal to a first predetermined value and less than a second predetermined value having a value larger than the first predetermined value. An upper limit value having a value larger than the target charge amount is set, and the target charge amount after the start of the catalyst temperature increase control is changed to a value between the upper limit value and the reference target charge amount. The control apparatus for an internal combustion engine according to any one of claims 1 to 4.   The target charge amount changing means determines a target charge amount at the start of the catalyst temperature increase control when the load of the internal combustion engine is equal to or greater than a second predetermined value having a value larger than a first predetermined value. The control device for an internal combustion engine according to any one of claims 1 to 5, wherein the value is changed to a value larger than the reference target charge amount.   When the load of the internal combustion engine is equal to or greater than a second predetermined value having a value greater than a first predetermined value, the target charge amount changing means sets the target charge amount after the start of the catalyst temperature increase control, The control device for an internal combustion engine according to any one of claims 1 to 6, wherein the controller is changed to a value smaller than a target charge amount at the start of the catalyst temperature increase control.

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