JP6060811B2 - Control device for an internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger.

  In a vehicle including an automatic transmission, an output shaft of an internal combustion engine is connected to a fluid transmission mechanism such as a torque converter. In order to increase the transmission efficiency of the driving force in such a fluid transmission mechanism, a lock-up clutch that couples the input shaft and the output shaft of the fluid transmission mechanism is provided. Is performed according to the vehicle speed, the amount of operation of the accelerator pedal, and the like.

  Here, the speed of increase of the engine speed when the accelerator pedal is depressed differs between the released state and the engaged state of the lockup clutch. Therefore, in an internal combustion engine equipped with a supercharger, the operating state of the lockup clutch affects the supercharged state.

  Therefore, for example, in the device described in Patent Document 1, the boost pressure of the turbocharger, the engine rotation increase rate, and the like are taken into account when controlling the engagement and release of the lockup clutch.

JP 2000-27987 A

  By the way, when the lock-up clutch is in the engaged state, the fuel consumption is improved as compared with the case where the lock-up clutch is in the released state. On the other hand, when the lock-up clutch is released, the fuel economy is worse than when the lock-up clutch is engaged, but the increase in the engine speed when the accelerator pedal is depressed increases, so the boost pressure increases. The speed also increases, and the response of the actual torque to changes in the required torque is improved.

  Thus, in an internal combustion engine with a supercharger, the effects obtained by engaging and releasing the lockup clutch are in a trade-off relationship, so that the lockup clutch can be engaged and released appropriately. desired.

  The present invention has been made in view of such circumstances, and an object of the present invention is to appropriately engage and disengage a lock-up clutch in an internal combustion engine with a supercharger, so that the actual torque with respect to a change in required torque can be reduced. An object of the present invention is to provide a control device capable of achieving both improvement in responsiveness and suppression of deterioration in fuel consumption.

  A control device that solves the above problems is applied to an internal combustion engine with a supercharger that includes a fluid transmission mechanism with a lock-up clutch. The control device permits engagement of the lockup clutch when the required torque for the internal combustion engine is equal to or less than the maximum torque that can be achieved without supercharging by the supercharger, while the required torque for the internal combustion engine When the maximum torque that can be achieved without supercharging is exceeded, clutch control is performed to prohibit engagement of the lockup clutch.

  When the required torque for the internal combustion engine exceeds the maximum torque that can be realized without supercharging by the supercharger, in other words, the maximum torque that can be realized by natural intake, it is preferable to increase the actual torque early by supercharging. Therefore, in this case, engagement of the lockup clutch is prohibited by the clutch control, and the lockup clutch is released. As a result, the increase speed of the engine rotation speed increases, so that the increase speed of the supercharging pressure also increases, and the response of the actual torque to the change in the required torque is improved.

  On the other hand, when the required torque for the internal combustion engine is less than the maximum torque that can be achieved without supercharging by the turbocharger, in other words, less than the maximum torque that can be achieved by natural intake, the actual torque is reduced to the required torque without relying on supercharging. Since it can be increased, it is preferable to prioritize suppression of fuel consumption deterioration over increasing the boost pressure increase rate. Therefore, in this case, the engagement of the lock-up clutch is permitted by the clutch control and the lock-up clutch is brought into the engaged state, thereby suppressing the deterioration of fuel consumption.

  By comparing the maximum torque that can be achieved without supercharging by the supercharger and the required torque in this way, it is appropriately determined whether or not it is necessary to increase the increase rate of the supercharging pressure when realizing the required torque. The Therefore, it is possible to appropriately engage and disengage the lock-up clutch in response to the supercharging request, and as described above, it is possible to achieve both improvement in the response of the actual torque to the change in the required torque and suppression of deterioration in fuel consumption. become able to.

  When engagement of the lockup clutch is prohibited by the clutch control described above, it is preferable to execute together with an increasing process for increasing the supercharging pressure of the supercharger. In this case, the effect of increasing the boost pressure by the increase process is added to the effect of increasing the boost pressure by the release of the lock-up clutch, so that the response of the actual torque to the change in the required torque is further improved. It becomes like this.

It is preferable that the increase amount of the supercharging pressure by such an increase process is increased as the difference between the required torque for the internal combustion engine and the maximum torque that can be achieved without supercharging by the supercharger is larger.
In the control device, it is preferable that the supercharging pressure of the supercharger is controlled to the target supercharging pressure corresponding to the required torque, and that the target supercharging pressure is increased and corrected as the above-described increase processing.

According to the above configuration, the target supercharging pressure is increased and corrected by executing the increasing process, so that the supercharging pressure can be increased.
Further, in the above control device, when a motor for assisting the rotation of the supercharger is provided, it is preferable to perform a process of increasing the rotational speed of the motor as the increase process described above.

  According to the above configuration, the supercharging pressure can be increased because the rotation speed of the supercharger is increased by executing the increasing process. In addition, as a process which increases the rotational speed of a motor, if it is an electric motor, for example, the process etc. which increase the drive current, drive voltage, etc. which are supplied to the motor are mentioned.

In the control device, it is also possible to adopt a configuration in which the clutch control is executed when the lockup clutch is engaged.
Note that the above-described engagement of the lockup clutch means a state in which the lockup clutch can transmit the driving force, and a state in which the lockup clutch is completely engaged, Including a state in which the slip amount of the lockup clutch is controlled by execution.

1 is a schematic diagram showing a vehicle configuration to which a control device for an internal combustion engine with a supercharger is applied. The conceptual diagram which shows the relationship between an engine speed, the amount of accelerator operation, and a request torque. The flowchart which shows the process sequence for performing operation | movement control of a lockup clutch. The timing chart which shows the action | operation aspect of a lockup clutch when a request | requirement torque exceeds the determination value. The timing chart which shows the action | operation aspect of a lockup clutch when a request torque is below a determination value. The flowchart which shows the example about the process sequence for performing operation | movement control of a lockup clutch. The conceptual diagram which shows the relationship between the increase amount of a supercharging pressure, and a torque deviation in the same example.

Hereinafter, an embodiment embodying a control device for an internal combustion engine with a supercharger will be described with reference to FIGS.
As shown in FIG. 1, an engine 10 provided in a vehicle is provided with a turbocharger 50 as a supercharger that supercharges intake air in an intake passage 11 by using exhaust gas in an exhaust passage 13. . The turbocharger 50 is provided with a waste gate valve for adjusting the amount of exhaust gas flowing into the turbine wheel on the exhaust side, and the supercharging pressure is adjusted by adjusting the opening degree of the waste gate valve. The intake passage 11 is provided with a throttle valve 12 for adjusting the intake air amount.

  A crankshaft that is an output shaft of the engine 10 is connected to a torque converter 30 including a lockup clutch 40. The torque converter 30 is a fluid transmission mechanism that transmits driving force via oil between the engine 10 side and the drive wheel side, and an output shaft thereof is connected to the input side of the automatic transmission 20.

  The lockup clutch 40 is a clutch that can directly connect the input side (engine 10 side) and the output side (automatic transmission side) of the torque converter 30. The operation of the lock-up clutch 40 is controlled by the hydraulic control circuit 21, and a “directly connected state (completely engaged state)” in which the input side and the output side of the torque converter 30 are directly engaged. The operating state changes between the “disengaged state” in which the driving force transmission amount via the lock-up clutch 40 is “0” after the direct connection state is released. When slip control for controlling the slip amount of the lock-up clutch 40 is performed, relative rotation between the input side and the output side of the torque converter 30 is allowed to some extent, and both are partially engaged. The lockup clutch 40 is in the “slip state”.

  In this embodiment, the “engagement” of the lockup clutch 40 means a state in which the lockup clutch 40 can transmit the driving force, and the “directly connected state” and the “slip state” described above are such “engagement”. Included in the "combined" state.

  Various controls such as engine control of the engine 10, shift control of the automatic transmission 20, or operation control of the lockup clutch 40 are performed by the control device 60. In order to perform the various controls described above, for example, detection signals from various sensors as described below are input to the control device 60.

A crank angle sensor 70 that detects the engine rotational speed NE of the engine 10.
An air flow meter 71 that detects the intake air amount GA.
A throttle opening sensor 72 that detects a throttle opening TA that is the opening of the throttle valve 12.

An accelerator sensor 73 that detects an accelerator operation amount ACCP that is an operation amount of the accelerator pedal.
A vehicle speed sensor 74 that detects the vehicle speed SP of the vehicle.

  As shown in FIG. 2, the control device 60 calculates a vehicle driver's required torque TD for the engine 10 based on the accelerator operation amount ACCP and the engine speed NE. The control device 60 controls the intake air amount, the fuel injection amount, the supercharging pressure of the turbocharger 50, and the like so that the required torque TD is obtained.

  Further, the control device 60 sets the operation state of the lockup clutch 40 to any one of “directly connected state”, “slip state”, and “released state” based on the accelerator operation amount ACCP and the vehicle speed SP. In the present embodiment, the region where the lock-up clutch 40 is set to either the “directly connected state” or the “slip state” in the driving region of the vehicle defined by the accelerator operation amount ACCP and the vehicle speed SP is “ The area where the lock-up clutch 40 is set to the “released state” is referred to as the “release area”.

As described above, the operation state of the lockup clutch 40 is basically set according to the driving state of the vehicle based on the accelerator operation amount ACCP and the vehicle speed SP.
Here, as described above, when the lock-up clutch 40 is in the engaged state, the fuel efficiency is improved as compared with the case of being in the released state. On the other hand, when the lock-up clutch 40 is in the released state, although it is disadvantageous in terms of fuel consumption compared to the engaged state, the increase speed of the engine speed when the accelerator pedal is depressed increases. The increasing speed of the supply pressure also increases, and the response of the actual torque (actual torque output from the engine 10) to the change in the required torque TD is improved.

  Thus, in the engine 10 including the turbocharger 50, the effects obtained by the engagement and release of the lockup clutch 40 are in a trade-off relationship, and the engagement and release of the lockup clutch 40 are brought into the engine operation state. It is desirable to do appropriately.

  Therefore, the control device 60 performs clutch control that has priority over the operation control of the lockup clutch 40 based on the accelerator operation amount ACCP and the vehicle speed SP. This clutch control is performed by executing a series of processes shown in FIG. 3 at predetermined intervals.

  As shown in FIG. 3, when this process is started, first, whether or not the current driving region of the vehicle is the above-described “engagement region”, that is, the lockup clutch 40 is “directly connected” or “ It is determined whether or not one of the “slip states” is set (S100).

  Then, when the current driving region of the vehicle is not the “engagement region”, that is, when the lockup clutch 40 is in the “released state” (S100: NO), this process is temporarily ended.

  On the other hand, when the current driving range of the vehicle is the “engagement range” (S100: YES), it is determined whether or not the required torque TD described above has increased (S110). Then, when the required torque TD has not increased (S110: NO), this process is temporarily terminated.

On the other hand, when the required torque TD increases (S110: YES), a determination value α is calculated (S120).
This determination value α is the maximum torque of the engine 10 that can be obtained without supercharging by the turbocharger 50, in other words, the maximum torque of the engine 10 that can be obtained by natural intake, and can be obtained through a prior experiment or the like. Is possible.

  Since the maximum torque changes according to the engine operating state, a plurality of determination values α corresponding to the engine operating state are stored in the control device 60, or the determination value α is controlled by using a model equation. 60 can be calculated. For example, the determination value α can be calculated using a model equation from the intake air amount, atmospheric pressure, or the like corresponding to the throttle opening degree TA or the like. It is also possible to set the determination value α in the following manner. In other words, the output torque when the engine is fully loaded (when the throttle valve is fully opened) varies depending on the engine speed and the like. Therefore, by determining the relationship between the engine rotational speed and the like when the engine 10 is a naturally aspirated engine and the output torque at full load by a simulation experiment or the like, a determination value α corresponding to the engine rotational speed or the like is obtained. Can also be set.

When the determination value α is thus calculated, it is determined whether or not the increased required torque TD is equal to or less than the determination value α (S130).
When the increased required torque TD is equal to or less than the determination value α (S130: YES), the engagement of the lockup clutch 40 is permitted, and the engagement of the lockup clutch 40 is continued (S140). This process is temporarily terminated.

  On the other hand, when the increased required torque TD exceeds the determination value α (S130: NOY), the lockup clutch 40 is disengaged by prohibiting the engagement of the lockup clutch 40 (S150). Is temporarily terminated.

  In addition, when the lockup clutch 40 that should have been engaged in this way is switched to the released state by the process of step S140, after a predetermined time has elapsed since the lockup clutch 40 was released. The lockup clutch 40 is preferably engaged. For example, the lockup clutch 40 may be returned to the engaged state when the actual torque of the engine 10 reaches the required torque TD or when the actual torque has sufficiently approached the required torque TD. Alternatively, the lockup clutch 40 may be returned to the engaged state when the elapsed time after the lockup clutch 40 is released reaches a predetermined determination time.

Next, the operation of the clutch control will be described with reference to FIGS.
FIG. 4 shows the operating state of the lockup clutch 40 when the required torque TD exceeds the determination value α.

  As shown in FIG. 4, when the required torque TD (shown by the solid line L1) increases and exceeds the determination value α (time t1), the required torque TD for the engine 10 is not supercharged by the turbocharger 50. Since the maximum torque that can be achieved, in other words, the maximum torque that can be achieved by natural intake, is exceeded, it is preferable to increase the actual torque early by using supercharging.

  Therefore, in the clutch control, when the required torque TD exceeds the determination value α (time t1, step S130 of FIG. 3: NO), the engagement of the lockup clutch 40 that has been engaged is prohibited ( Step S150 in FIG. As a result, the lockup clutch 40 that has been engaged is released. When the lockup clutch 40 is released, the load against the increase in the rotation of the engine 10 becomes smaller than when the lockup clutch 40 is engaged. Therefore, the increase rate of the engine rotation speed when the required torque TD increases due to depression of the accelerator pedal increases. To do. When the increase speed of the engine rotation speed increases in this way, the increase speed of the exhaust gas flow rate increases, and thus the increase speed of the supercharging pressure increases. Therefore, the increase speed of the actual torque TR (shown by a one-dot chain line L2 in FIG. 4) when the lock-up clutch 40 is released is equal to the actual torque TR (FIG. 4) when the lock-up clutch 40 is engaged. 2), the responsiveness of the actual torque TR to the change in the required torque TD is improved. Therefore, when the lockup clutch 40 is disengaged, the time for the actual torque TR to reach the increased required torque TD is shortened compared to when the lockup clutch 40 is engaged, and the actual torque TR is increased early.

FIG. 5 shows an operating state of the lockup clutch 40 when the required torque TD is equal to or less than the determination value α.
As shown in FIG. 5, when the required torque TD (shown by the solid line L1) increases but does not exceed the determination value α (time t1), the required torque TD for the engine 10 is supercharged by the turbocharger 50. It does not exceed the maximum torque that can be achieved without, in other words, the maximum torque that can be achieved with natural aspiration. Therefore, as indicated by the alternate long and short dash line L2, the actual torque TR can be increased to the required torque TD without relying on supercharging. Therefore, in this case, it is preferable to give priority to suppression of fuel consumption deterioration over increase in boost pressure increase rate.

  Therefore, in the clutch control, when the required torque TD is equal to or less than the determination value α (time t1 in FIG. 5, step S130 in FIG. 3: YES), the engagement of the lockup clutch 40 is permitted (FIG. 3 (step S140), the engagement of the lock-up clutch 40 is maintained, thereby suppressing the deterioration of fuel consumption.

  Thus, by comparing the maximum torque (determination value α) that can be achieved without supercharging by the turbocharger 50 and the required torque TD, it is necessary to increase the increase rate of the supercharging pressure when realizing the required torque TD. It is possible to appropriately determine whether or not there is. Therefore, it is possible to appropriately engage and disengage the lock-up clutch 40 according to the supercharging request, and to achieve both improvement in the response of the actual torque TR to the change in the required torque TD and suppression of deterioration in fuel consumption. it can.

As described above, according to the present embodiment, the following effects can be obtained.
(1) When the required torque TD exceeds the maximum torque (determination value α) that can be achieved without supercharging by the turbocharger 50, the engagement of the lockup clutch 40 is prohibited, and therefore the required torque TD Responsiveness of the actual torque TR with respect to the change is improved. On the other hand, when the required torque TD is equal to or less than the maximum torque (determination value α) that can be achieved without supercharging by the turbocharger 50, the engagement of the lockup clutch 40 is permitted, so that deterioration of fuel consumption is suppressed. The

  Thus, by comparing the maximum torque (determination value α) that can be achieved without supercharging by the turbocharger 50 and the required torque TD, the lockup clutch 40 is appropriately engaged and released according to the supercharging request. This makes it possible to achieve both improvement in the response of the actual torque TR to changes in the required torque TD and suppression of deterioration in fuel consumption.

In addition, the said embodiment can also be changed and implemented as follows.
As shown in FIG. 6, an increase process for increasing the supercharging pressure may be executed as a step performed after step S150 shown in FIG. 3 (S200). That is, when the engagement of the lockup clutch 40 is prohibited by the clutch control described above, an increasing process for increasing the supercharging pressure of the turbocharger 50 may be executed together. Note that the boost pressure increasing process may be performed simultaneously with the lock-up clutch 40 being prohibited or prior to the engagement being prohibited. In this case, the effect of increasing the boost pressure due to the increase process is added to the effect of increasing the boost speed of the boost pressure due to the release of the lockup clutch 40, and therefore the response of the actual torque TR to the change in the required torque TD. Will be further improved.

  Note that such a process of increasing the supercharging pressure can be performed as appropriate. For example, when the supercharging pressure of the turbocharger 50 is controlled to the target supercharging pressure corresponding to the required torque TD, the target supercharging pressure is increased and corrected as an increase process. In this case, since the target boost pressure is corrected to increase by executing the increase process, the actual boost pressure can be increased. When a motor for assisting the rotation of the turbocharger 50 is provided, a process for increasing the rotational speed of the motor may be performed as the increase process. In this case, since the rotation speed of the turbocharger 50 is increased by executing the increasing process, the supercharging pressure can be increased. Incidentally, the process of increasing the rotation speed of the motor can be appropriately performed. For example, in the case of an electric motor, a process for increasing a drive current, a drive voltage, or the like supplied to the motor may be performed.

  As shown in FIG. 7, the increase amount of the supercharging pressure by the above-described increase processing (step S200 of FIG. 6) is the maximum torque (determination value) that can be realized without the required torque TD for the engine 10 and supercharging by the turbocharger 50. You may make it increase, so that the difference (DELTA) T ((DELTA) T = TD- (alpha)) with (alpha) is large.

  The process of step S100 shown in FIG. 3, that is, the process of determining whether or not the current driving region of the vehicle is the above-described “engagement region” may be omitted. Even in this case, the clutch control shown in FIG. 3 has priority over the operation control of the lockup clutch 40 based on the accelerator operation amount ACCP and the vehicle speed SP. Therefore, regardless of the state of the accelerator operation amount ACCP and the vehicle speed SP, if the required torque TD is equal to or less than the determination value α, the engagement of the lockup clutch 40 is permitted and the required torque TD does not exceed the determination value α. In this case, engagement of the lockup clutch 40 is prohibited. Therefore, the same effect as that of the above embodiment can be obtained.

  -The supercharger in the said embodiment was the turbocharger which supercharges using exhaust_gas | exhaustion. In addition, a supercharger that obtains driving force from the crankshaft of the engine and performs supercharging, a so-called supercharger may be used. Even in such a supercharger, when the lockup clutch 40 is released, the load against the increase in rotation of the engine 10 becomes smaller than when the lockup clutch 40 is engaged. Therefore, the required torque TD is reduced by depressing the accelerator pedal. As the engine speed increases, the engine speed increases. When the increase speed of the engine rotation speed increases in this way, the rotation speed of the supercharger also increases, so the increase speed of the supercharging pressure increases. Therefore, when the lock-up clutch 40 is released, the time for the actual torque to reach the increased required torque is shorter than when the lock-up clutch 40 is engaged, and the actual torque is increased early. Therefore, even when the engine includes a supercharger, the same effect as that of the above embodiment can be obtained. Even in an engine including a turbocharger and a supercharger, it is possible to obtain an effect according to the above embodiment and this modification.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Intake passage, 12 ... Throttle valve, 13 ... Exhaust passage, 20 ... Automatic transmission, 21 ... Hydraulic circuit, 30 ... Torque converter, 40 ... Lock-up clutch, 50 ... Turbocharger, 60 ... Control device , 70 ... crank angle sensor, 71 ... air flow meter, 72 ... throttle sensor, 73 ... accelerator sensor, 74 ... vehicle speed sensor.

Claims (6)

A control device for an internal combustion engine with a supercharger in which an output shaft is connected to a fluid transmission mechanism with a lock-up clutch,
When the required torque for the internal combustion engine is equal to or less than the maximum torque that can be achieved without supercharging by the supercharger, the lockup clutch is allowed to be engaged, while when the required torque exceeds the maximum torque, the lockup is performed. A control device for an internal combustion engine with a supercharger, wherein clutch control for prohibiting engagement of the clutch is performed. The control device for an internal combustion engine with a supercharger according to claim 1, wherein when the engagement of the lockup clutch is prohibited by the clutch control, an increase process for increasing a supercharging pressure of the supercharger is executed. The control device for an internal combustion engine with a supercharger according to claim 2, wherein an increase amount of the supercharging pressure by the increasing process is increased as a difference between the required torque and the maximum torque is increased. 4. The turbocharger according to claim 2, wherein the supercharging pressure of the supercharger is controlled to a target supercharging pressure corresponding to the required torque, and an increase correction of the target supercharging pressure is performed as the increase process. 5. Control device for internal combustion engine. 4. The control device for an internal combustion engine with a supercharger according to claim 2, wherein a motor for assisting rotation of the supercharger is provided, and processing for increasing the rotational speed of the motor is performed as the increase processing. The control device for an internal combustion engine with a supercharger according to any one of claims 1 to 5, wherein the clutch control is executed when the lockup clutch is engaged.