JP2009299563A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine suppressing deterioration in exhaust property, in an internal combustion engine automatically started or stopped. <P>SOLUTION: In the internal combustion engine mounted on a hybrid vehicle performing travelling only by an M/G, an exhaust passage thereof has a catalytic device on which exhaust cleaning catalyst for cleaning exhaust is carried. An electronic control unit performs a cylinder operation control operating a cylinder out of all cylinders, on the condition that a catalyst temperature T is a predetermined temperature Tc or lower at which cleaning ability is impaired when satisfying an M/G travel condition as an automatic stop condition of the internal combustion engine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that is automatically started and stopped.

Conventionally, for example, there is a hybrid vehicle that is driven by a generator motor when the speed of the vehicle is low, and is driven by a generator motor and an engine when the speed is high, or is driven only by an engine instead of the generator motor (for example, Patent Document 1). reference).
JP 2005-163718 A

  By the way, in the hybrid vehicle described in Patent Document 1, when the operation of the internal combustion engine is automatically stopped, the temperature of the catalyst that purifies the exhaust gas of the internal combustion engine may decrease and become lower than the activation temperature. In that state, when the internal combustion engine that has been stopped is automatically restarted, it becomes difficult for the catalyst to effectively purify the exhaust gas until the temperature reaches the activation temperature again, which may lead to deterioration of the exhaust properties. There is.

  Such problems are not limited to hybrid vehicles. For example, when the vehicle travels downhill or when the vehicle is stopped for a short time while waiting for a signal, an eco-run vehicle that automatically stops the internal combustion engine, etc. This is generally common in vehicles equipped with an internal combustion engine that automatically stops.

  The present invention has been made in view of such circumstances, and an object of the present invention is an internal combustion engine that is automatically started and stopped, and an internal combustion engine control device that can suppress deterioration of exhaust properties. It is to provide.

In the following, means for achieving the above object and its effects are described.
According to a first aspect of the present invention, in a control device for an internal combustion engine that includes a catalyst for purifying exhaust gas and that is automatically started and stopped, the temperature of the catalyst has a purification capacity when the automatic stop condition of the engine is satisfied. The gist of the invention is to provide cylinder operating means for operating some cylinders of all cylinders on condition that the temperature is lower than a predetermined temperature.

  According to the above configuration, when the automatic stop condition for the internal combustion engine is satisfied, the cylinder operation is performed so that some of the cylinders are operated on condition that the temperature of the exhaust purification catalyst is equal to or lower than a predetermined temperature at which the purification capability decreases. With the provision of the means, even if the engine automatic stop condition is satisfied, it is possible to operate some of the cylinders and maintain the catalyst temperature to such an extent that the purification capacity does not decrease. As a result, in an internal combustion engine that is automatically started and stopped, deterioration of exhaust properties can be suppressed.

  According to a second aspect of the present invention, in the control device for an internal combustion engine that includes a catalyst for purifying exhaust gas and that is automatically started and stopped, the automatic stop condition of the engine is satisfied and all the cylinders are stopped. The gist of the invention is that it includes cylinder operating means for operating some of the cylinders on the condition that the temperature of the catalyst is equal to or lower than a predetermined temperature at which the purification ability is reduced.

  According to the above configuration, when the automatic stop condition of the internal combustion engine is satisfied and all the cylinders are stopped, the exhaust purification catalyst temperature is less than or equal to a predetermined temperature at which the purification capability decreases. Since cylinder operation means for operating some of the cylinders is provided, even if all the cylinders are stopped, if the purification capacity of the catalyst is reduced, some cylinders may be operated to maintain the catalyst temperature. It becomes possible. As a result, in an internal combustion engine that is automatically started and stopped, deterioration of exhaust properties can be suppressed.

  According to the third aspect of the invention, by applying the present invention to a hybrid vehicle that travels using only the electric motor, when the vehicle travels using only the electric motor, some of the cylinders are operated to set the catalyst temperature. It becomes possible to hold.

According to a fourth aspect of the present invention, there is provided the control device for an internal combustion engine according to any one of the first to third aspects, wherein the partial cylinder is one of all cylinders. To do.
According to the above configuration, since some of the cylinders are one of all the cylinders, it is possible to suppress the decrease in the catalyst temperature while maximally improving the fuel consumption within a range in which the exhaust properties do not deteriorate. .

Hereinafter, an embodiment in which a control device for an internal combustion engine according to the present invention is employed in a hybrid vehicle will be described with reference to FIGS.
FIG. 1 schematically shows a schematic configuration of an internal combustion engine and a control device of a hybrid vehicle in the present embodiment. As shown in FIG. 1, an intake passage 11 and an exhaust passage 13 are connected to the first cylinder # 1 to the fourth cylinder # 4 of the internal combustion engine 10, respectively. The intake passage 11 is provided with a throttle valve 26 that adjusts the flow rate of intake air flowing through the intake passage 11 and an actuator 70 that drives the throttle valve 26 to open and close. In the intake passage 11 in this embodiment, an open / close valve 25 that is opened and closed by an actuator 71 is provided in each cylinder between the throttle valve 26 and the intake valve of each cylinder. The on-off valve 25 is maintained in a fully opened state when the internal combustion engine 10 is in operation.

  A fuel injection valve 20 is provided in each intake passage 11 corresponding to each cylinder. The fuel injected from each fuel injection valve 20 is mixed with intake air to form an air-fuel mixture. The air-fuel mixture flowing into each cylinder as the intake valve is opened is ignited and burned by an ignition plug provided in each cylinder, and then discharged to the exhaust passage 13 as the exhaust valve is opened. The

  The exhaust passage 13 is provided with a catalyst device 16 carrying an exhaust purification catalyst for purifying exhaust components. The catalytic device 16 has a function of purifying hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) mainly contained in exhaust gas by utilizing the oxidation-reduction action. Further, the catalyst device 16 is provided with a catalyst temperature sensor 72 for detecting the temperature of the catalyst.

  A crankshaft 17 in the internal combustion engine 10 as an engine output shaft is connected to a drive wheel of the vehicle through an automatic transmission (automatic transmission: A / T shown in FIG. 1) 30. The output of the internal combustion engine 10 is transmitted from the crankshaft 17 of the internal combustion engine 10 to the drive wheels of the vehicle via the torque converter 18 and the A / T 30. The crankshaft 17 is connected to a starter 35, which is an electric motor for starting the engine, as necessary.

  In addition to the driving force transmission system from the internal combustion engine 10 to the driving wheels, the output of the internal combustion engine 10 is transmitted to a pulley 41 connected to the crankshaft 17. The belt 19 is hung on the pulleys 45 and 46 other than the pulley 41 along a part of the peripheral edge of each pulley. That is, the output of the internal combustion engine 10 transmitted to the pulley 41 is transmitted as a rotational force to the pulleys 45 and 46 via the belt 19. The pulley 41 includes the electromagnetic clutch 15 and is turned on (connected) or turned off (cut off) as necessary by the electromagnetic clutch 15, so that the pulley 41 transmits output to and from the crankshaft 17. Or non-transmission can be switched.

  Auxiliary machinery 40 is connected to the pulley 45 (shown above the pulley 41 in FIG. 1) via its rotating shaft, and the auxiliary machinery 40 is connected to the pulley 41 transmitted from the belt 19. It can be driven by rotational force. Examples of the auxiliary machines 40 include a water pump for cooling an internal combustion engine, a power steering pump, and an air conditioner compressor.

  The pulley 46 (shown below the pulley 41 in FIG. 1) is connected to a motor generator (shown as M / G in FIG. 1) 42, and the M / G 42 receives a rotational force to transmit the belt. It rotates in conjunction with 19. The M / G 42 functions as a generator (power generation mode or regeneration mode) or an electric motor (drive mode) as necessary. When functioning as a generator, the M / G 42 converts the rotational force of the internal combustion engine 10 transmitted from the pulley 46 into electrical energy. When functioning as an electric motor, the M / G 42 rotates the belt 19 via the pulley 46. Then, one or both of the crankshaft 17 and the auxiliary machinery 40 are rotated.

  Further, the M / G 42 is electrically connected to the inverter 51. When the M / G 42 is set to the power generation mode or the regenerative mode, the inverter 51 switches the high voltage battery 55 to the low voltage battery 56 via the DC / DC converter 52 (shown simply as DC / DC in FIG. 1). On the other hand, electric energy is charged from the M / G42. The high voltage battery 55 is provided with a battery sensor (not shown) for detecting the voltage of the high voltage battery 55 and the current input / output to / from the high voltage battery 55.

  On the other hand, when the M / G 42 is set to the drive mode, the inverter 51 supplies power to the M / G 42 from the high voltage battery 55 that is a power source. The inverter 51 drives the M / G 42 to rotate the auxiliary machinery 40 via the pulley 46 and the belt 19 when the internal combustion engine 10 is stopped, and when the automatic stop, automatic start or vehicle start is performed. Rotates the crankshaft 17. In addition, the inverter 51 adjusts the rotational speed of the M / G 42 by adjusting the electric energy supplied from the high voltage battery 55.

  The electric power of the low voltage battery 56 is supplied to the starter 35 and also to an electric hydraulic pump (not shown) provided in the A / T 30. The electric hydraulic pump supplies hydraulic oil to a hydraulic control unit provided inside the A / T 30. The hydraulic oil supplied to the hydraulic control unit is adjusted in hydraulic pressure by a control valve provided in the hydraulic control unit. Thus, the operating states of the clutch, brake and one-way clutch inside the A / T 30 are adjusted so that the shift state can be switched as necessary.

  On / off switching of the electromagnetic clutch 15 described above, mode control of the M / G 42 of the inverter 51, control of the starter 35, control of the amount of charge in the high voltage battery 55 and the low voltage battery 56, on / off of driving of the auxiliary machinery 40, and further electric The A / T 30 shift control including the drive of the hydraulic pump is executed by the electronic control unit 80. The electronic control unit 80 also controls the fuel injection control of the fuel injection valve 20, the opening control of the throttle valve 26 by the actuator 70, the opening control of the opening / closing valve 25 by the actuator 71, and the control of other operating states of the internal combustion engine 10. Execute.

  The electronic control unit 80 includes a CPU that executes various controls, a memory that stores information necessary for the control, an input port for inputting a signal from the outside, an output port for outputting a command signal to the outside, and the like. Configured. Output signals from various sensors for grasping the driving state of the vehicle are input to the input port of the electronic control unit 80. Examples of the various sensors include a vehicle speed sensor 61 that detects the vehicle speed of the vehicle, an accelerator pedal depression amount sensor 62 that detects the depression amount of the accelerator pedal operated by the driver, and an engine that detects the engine speed of the internal combustion engine 10. Examples thereof include a rotation speed sensor 63 and a battery sensor attached to the high voltage battery 55. Further, in the present embodiment, an output signal from the catalyst temperature sensor 72 described above is also input to the electronic control unit 80. Based on signals output from these various sensors, the electronic control unit 80 grasps the state of the vehicle and executes various controls.

  For example, the electronic control unit 80 detects the state of charge (SOC) of the high-voltage battery 55 based on a signal from the battery sensor, and controls the charging of the high-voltage battery 55 according to the detected SOC. . Specifically, when it is detected that the SOC of the high-voltage battery 55 falls below a predetermined lower limit value, the electronic control unit 80 sets the required load of the internal combustion engine 10 high and increases the driving force of the internal combustion engine 10. Such charging of the high voltage battery 55 is performed by operating the M / G 42 in consideration of the traveling state of the vehicle.

  Further, as described above, the electronic control unit 80 grasps the traveling state of the vehicle based on signals from the vehicle speed sensor 61, the accelerator pedal depression amount sensor 62, the engine speed sensor 63, and the like. Note that the driving state of the vehicle grasped in this way includes the driving force requested by the driver. Then, the required load of the internal combustion engine 10 is calculated based on the grasped traveling state of the vehicle and the SOC of the high voltage battery 55. And various control of the internal combustion engine 10 and M / G42 is performed. For example, the operating state of the internal combustion engine 10 such as the intake air amount, the fuel injection amount, and the ignition timing is controlled based on the calculated required load.

  By the way, in the hybrid vehicle as in the present embodiment, when the operation of the internal combustion engine is automatically stopped, the temperature of the catalyst that purifies the exhaust gas of the internal combustion engine may decrease and fall below the activation temperature. In that state, when the internal combustion engine that has been stopped is automatically restarted, it becomes difficult for the catalyst to effectively purify the exhaust gas until the temperature reaches the activation temperature again, which may lead to deterioration of the exhaust properties. There is.

  Therefore, in the electronic control unit 80 of the internal combustion engine 10 according to the present embodiment, all the cylinders are conditioned on the condition that the catalyst temperature is equal to or lower than a predetermined temperature when the M / G running condition that is the automatic stop condition of the internal combustion engine 10 is established. Cylinder operation control for operating some of the cylinders is executed. This cylinder operation control will now be described in detail with reference to FIG. Note that the cylinder operation control shown in FIG. 2 corresponds to a process as a cylinder operation means, and is periodically executed through the electronic control unit 80, for example, with a time interruption every predetermined time.

  As shown in FIG. 2, when the cylinder operation control is started, it is first determined whether or not the M / G traveling condition is satisfied (step S110). Here, the M / G traveling condition is, for example, that the vehicle speed of the vehicle detected from the vehicle speed sensor 61 is not more than a predetermined value, and the amount of depression of the accelerator pedal detected from the accelerator pedal depression amount sensor 62 is not more than a predetermined amount. The engine speed detected from the engine speed sensor 63 is equal to or lower than a predetermined speed, and the SOC of the high-voltage battery 55 detected from the battery sensor is equal to or higher than a predetermined value. If it is determined that these conditions are not satisfied (step S110: NO), the operation of the internal combustion engine 10 is continued as it is, or the drive of the M / G 42 is stopped and the operation of the internal combustion engine 10 is started. Specifically, when the operation of the internal combustion engine 10 is started, the throttle valve 26 is opened by the actuator 70, the fuel injection of the fuel injection valve 20 corresponding to all cylinders, and the opening / closing valve 25 is opened by the actuator 71. Valve is performed. And this process is once complete | finished.

  On the other hand, if it is determined that the above condition is satisfied (step S110: YES), the driving of the M / G 42 is continued or the rotation of the crankshaft 17 by the driving of the M / G 42 is started. Then, the present process is shifted to the next step in order to determine the operation stop mode of the cylinder in the internal combustion engine 10.

  Subsequently, the catalyst temperature T is read from the catalyst temperature sensor 72 provided in the catalyst device 16 (step S120), and it is determined whether or not the read catalyst temperature T is equal to or lower than a predetermined temperature Tc (step S130). . Here, the predetermined temperature Tc is the temperature of the catalyst at which the purification capacity is lowered, and is an experimental value obtained by experiments.

  If it is determined that the catalyst temperature T exceeds the predetermined temperature Tc (step S130: NO), it is assumed that the exhaust property will not deteriorate even if the vehicle is driven only by the M / G 42, as shown in FIG. The operation of all the first to fourth cylinders # 1 to # 4 is stopped (step S150), and the M / G 42 is driven. Specifically, the throttle valve 26 is closed by the actuator 70 shown in FIG. 1, and the fuel injection of the fuel injection valves 20 of all the cylinders and the ignition of the air-fuel mixture are stopped.

  On the other hand, when it is determined that the catalyst temperature T is equal to or lower than the predetermined temperature Tc (step S130: YES), it is assumed that exhaust characteristics deteriorate when the vehicle is driven only by the M / G 42. Only one cylinder of the fourth cylinder # 4 is operated, and the operations of the other first cylinder # 1 to third cylinder # 3 are stopped (step S140). Specifically, the throttle valve 26 is opened by the actuator 70, the fuel injection of the fuel injection valve 20 corresponding to the fourth cylinder # 4, the opening of the on-off valve 25, and the ignition of the air-fuel mixture are performed. Then, the fuel injection of the fuel injection valves 20 corresponding to the first cylinder # 1 to the third cylinder # 3 and the ignition of the air-fuel mixture are stopped, and the corresponding opening / closing valve 25 is also closed.

In step S140 or step S150, the cylinder operation of the internal combustion engine 10 is controlled, and this process is temporarily terminated.
Next, a mode of cylinder operation accompanying a change in the catalyst temperature T will be described with reference to FIGS. 3 and 4 show examples of the transition of the catalyst temperature T and the control mode of cylinder operation. FIG. 3 shows a case where the above-described cylinder operation control is started when the catalyst temperature T exceeds the predetermined temperature Tc, such as when the internal combustion engine 10 is in operation. In such a case, as shown in FIG. 3, when the cylinder operation control is executed, the cylinder operation of the internal combustion engine 10 is controlled from the all cylinder operation state to the all cylinder stop state (t1). As a result, the catalyst temperature T decreases with time. When the catalyst temperature T becomes equal to or lower than the predetermined temperature Tc, the cylinder operation is controlled to a single cylinder operation state, that is, only the fourth cylinder # 4 in FIG. 1 is operated (t2). Then, the catalyst of the catalyst device 16 is warmed and the catalyst temperature T rises. When the catalyst temperature T exceeds the predetermined temperature Tc, all cylinders are stopped again (t3).

  Instead, FIG. 4 shows a case where the above-described cylinder operation control is started when the catalyst temperature T is equal to or lower than the predetermined temperature Tc, such as when the internal combustion engine 10 is just started. In such a case, as shown in FIG. 4, when the cylinder operation control is executed, the cylinder operation is controlled from the all-cylinder operation state of the internal combustion engine 10 to the one-cylinder operation state (t1). Then, as the time elapses, the catalyst of the catalyst device 16 is warmed and the catalyst temperature T rises. When the catalyst temperature T exceeds the predetermined temperature Tc, the cylinder operation is controlled to the all cylinders stopped state (t2). Then, the catalyst temperature T decreases, and when the catalyst temperature T becomes equal to or lower than the predetermined temperature Tc, the cylinder operation is again performed by one cylinder (t3).

According to the embodiment described above, the following effects can be obtained.
(1) The electronic control unit 80 is in all cylinders on condition that the temperature T of the exhaust purification catalyst of the catalyst device 16 is equal to or lower than a predetermined temperature Tc at which the purification capability decreases when the automatic stop condition of the internal combustion engine 10 is satisfied. Since cylinder operation control for operating one cylinder of the fourth cylinder # 4 among the first cylinder # 1 to the fourth cylinder # 4 is executed, one cylinder is operated even if the automatic stop condition of the internal combustion engine 10 is satisfied. Thus, the catalyst temperature T can be maintained to such an extent that the purification capacity does not decrease. As a result, in the internal combustion engine 10 that is automatically started and stopped, deterioration of exhaust properties can be suppressed.

  (2) The electronic control unit 80 performs the exhaust purification catalyst of the catalyst device 16 when the automatic stop condition of the internal combustion engine 10 is satisfied and the first cylinder # 1 to the fourth cylinder # 4, which are all cylinders, are stopped. All cylinders are stopped in order to execute cylinder operation control for operating the fourth cylinder # 4, which is one of all the cylinders, on the condition that the temperature T of the cylinder is equal to or lower than the predetermined temperature Tc at which the purification capacity decreases. However, if the purification capacity of the catalyst is reduced, it is possible to operate one cylinder and maintain the catalyst temperature T. As a result, in the internal combustion engine 10 that is automatically started and stopped, deterioration of exhaust properties can be suppressed.

  (3) The fourth cylinder # 4, which is switched whether or not to be operated by the cylinder operation control performed by the electronic control unit 80, is one of the first cylinder # 1 to the fourth cylinder # 4, which is all cylinders. Therefore, it is possible to suppress the decrease in the catalyst temperature T while maximally improving the fuel consumption within a range where the exhaust properties do not deteriorate.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the open / close valve 25 is provided in the intake passage 11 between the throttle valve 26 and the intake valve of each cylinder, and when the fourth cylinder # 4 is operated by the cylinder operation control, the fourth cylinder Although the opening / closing valve 25 corresponding to # 4 is opened and the fuel injection of the fuel injection valve 20 is controlled to be performed and the air-fuel mixture is ignited, the opening / closing valve is not provided, and the one-cylinder operation by the cylinder operation control is performed. At this time, only the injector corresponding to one cylinder among all the cylinders may be injected with fuel and the air-fuel mixture may be ignited. In addition, a mechanism for controlling the opening degree of the intake valve may be provided in one cylinder without providing the on / off valve, and may be opened and closed in a manner similar to the on / off valve of the above embodiment.

  In the above embodiment, it is determined whether or not only the fourth cylinder # 4, which is one of the first cylinder # 1 to the fourth cylinder # 4 of all the cylinders, is operated during the cylinder operation control. However, the position and the number of some cylinders to be operated are not limited. Further, the cylinders to be operated may not be fixed to the same cylinder but sequentially switched to different cylinders.

  In the above embodiment, the catalyst temperature T is directly detected by the catalyst temperature sensor 72. However, the catalyst temperature may be calculated using other detected values such as the operating state of the internal combustion engine. Good.

  In the above embodiment, the control device for an internal combustion engine of the present invention is employed in the internal combustion engine 10 having in-line four cylinders. However, the present invention is not limited to the internal combustion engine having other in-line multi-cylinders. This internal combustion engine can also be employed.

  In the above embodiment, the control device for an internal combustion engine of the present invention is employed in a hybrid vehicle that travels using only the M / G 42. However, the eco-run that automatically stops the drive of the internal combustion engine when the vehicle stops for a short time. The present invention can be applied to any vehicle that is automatically started and stopped, such as a vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the internal combustion engine to which this is applied, and its periphery structure about one Embodiment of the control apparatus of the internal combustion engine concerning this invention. The flowchart which shows the process sequence of the cylinder operation control in the same embodiment. 4 is a time chart showing the transition of the catalyst temperature and the mode of cylinder operation when cylinder operation control is started when the catalyst temperature exceeds a predetermined temperature in the embodiment. 5 is a time chart showing changes in catalyst temperature and modes of cylinder operation when cylinder operation control is started when the catalyst temperature is equal to or lower than a predetermined temperature in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 13 ... Exhaust passage, 15 ... Electromagnetic clutch, 16 ... Catalyst device, 17 ... Crankshaft, 18 ... Torque converter, 19 ... Belt, 20 ... Fuel injection valve, 25 ... Open / close valve, 26 ... Throttle valve, 30 ... Automatic transmission (A / T), 35 ... Starter, 40 ... Auxiliary equipment, 41, 45, 46 ... Pulley, 42 ... Motor generator (M / G), 51 ... Inverter, 52 ... DC DC converter, 55 ... high voltage battery, 56 ... low voltage battery, 61 ... vehicle speed sensor, 62 ... accelerator pedal depression sensor, 63 ... engine speed sensor, 70, 71 ... actuator, 72 ... catalyst temperature sensor, 80 ... electronic control apparatus.

Claims (4)

In a control device for an internal combustion engine that includes a catalyst for purifying exhaust gas and that is automatically started and stopped,
Cylinder operation means for operating some cylinders of all cylinders on condition that the temperature of the catalyst is equal to or lower than a predetermined temperature at which purification capacity decreases when the automatic stop condition of the engine is satisfied, A control device for an internal combustion engine. In a control device for an internal combustion engine that includes a catalyst for purifying exhaust gas and that is automatically started and stopped,
When all the cylinders are stopped due to the automatic engine stop condition being met, a part of all the cylinders may be operated under the condition that the temperature of the catalyst is equal to or lower than a predetermined temperature at which the purification capacity is reduced. A control apparatus for an internal combustion engine, comprising: cylinder operating means for operating. The control apparatus for an internal combustion engine according to claim 1 or 2,
The engine is mounted on a hybrid vehicle that runs only by an electric motor,
The control apparatus for an internal combustion engine, wherein the automatic stop condition of the engine is a condition for running the vehicle only by the electric motor. The control device for an internal combustion engine according to any one of claims 1 to 3,
The control apparatus for an internal combustion engine, wherein the partial cylinder is one of all cylinders.

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