JP5098921B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine control device that automatically stops and restarts an internal combustion engine in accordance with operating conditions, and more particularly to an internal combustion engine control device that can automatically stop an internal combustion engine even during coasting.

In Patent Document 1, when there is a request to restart the internal combustion engine while the internal combustion engine is stopped, when the engine speed of the internal combustion engine is within a predetermined restart prohibition region (800 to 200 rpm), A technique is disclosed in which control is performed such that restart of the internal combustion engine is prohibited until the engine speed falls below a lower limit value of the restart prohibition region.
Japanese Patent Application Laid-Open No. 2002-339881

  However, in Patent Document 1, when there is a request for restarting the internal combustion engine at a timing when the engine speed of the internal combustion engine is within a predetermined restart prohibition region (800 to 200 rpm), the start request for the internal combustion engine is not satisfied. On the other hand, there is a possibility that it cannot respond promptly.

Therefore, the control device for an internal combustion engine of the present invention is capable of automatically stopping / restarting the internal combustion engine even during coasting, and is provided in a power transmission path between the internal combustion engine and driving wheels. It has a lockup mechanism that interrupts the transmission path. When the internal combustion engine is automatically stopped during coasting and the lockup mechanism is unlocked, the throttle opening is expanded and the volumetric efficiency becomes constant. It is characterized by controlling the throttle opening .

  According to the present invention, since the pump loss is reduced and the starting torque of the internal combustion engine is reduced, the internal combustion engine whose engine speed is decreasing due to the automatic stop of the internal combustion engine is quickly restarted when necessary. be able to. In addition, since the pump loss is reduced and the reduction rate of the engine speed due to the automatic stop of the internal combustion engine can be reduced, the engine speed is reduced due to the automatic stop of the internal combustion engine. The marginal torque of the starting means increases, and the startability of the internal combustion engine during coasting can be improved.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system configuration diagram of a control device for an internal combustion engine according to the present invention. As shown in FIG. 1, a power transmission path that connects the rear end side of the internal combustion engine 1 and the drive wheel 5 of the vehicle includes a torque converter 2 with a lockup mechanism that intermittently connects the power transmission path, an automatic transmission 3, and an end. A final gear 4 as a reduction device is interposed. The automatic transmission 3 may be a stepped automatic transmission including a plurality of planetary gear mechanisms, or may be a continuously variable transmission such as a belt type or a toroidal type.

  A crank pulley 7 that rotates integrally with the crankshaft 6 is disposed at the front end of the internal combustion engine 1. A belt 10 is wound around the crank pulley 7 and a motor pulley 9 attached to the output shaft 8 a of the motor generator 8. That is, the motor generator 8 as the starting means and the crankshaft 6 are configured to rotate synchronously.

  The motor generator 8 functions as a generator and a starter. The motor generator 8 functions as a starter during power running operation such as when the internal combustion engine 1 is started, and as a generator during regenerative operation when the internal combustion engine 1 is rotated. It functions. The motor generator 8 is controlled by the control unit 11 to start and stop, and to switch between power running operation and regenerative operation.

  The control unit 11 controls the opening degree of the throttle valve 12.

  The control unit 11 includes a vehicle speed sensor 13 for detecting the vehicle speed of the vehicle, a rotation speed sensor 14 as an engine speed detection means for detecting the engine speed of the internal combustion engine 1, an accelerator pedal ON / OFF, and an accelerator pedal. An accelerator sensor 15 for detecting the operation amount, a brake pedal sensor 16 for detecting the brake pedal ON / OFF and the operation amount of the brake pedal, a select position sensor 17 for detecting the select position of the automatic transmission 3, and a downstream side of the throttle valve 12. A signal is input from a boost sensor 18 provided in the intake passage and serving as pressure detection means for detecting the pressure in the intake passage on the downstream side of the throttle valve 12.

  Here, in the present embodiment, the intake air is used by using the engine speed that is the detection value of the rotation speed sensor 14 and the pressure (intake negative pressure) in the intake passage that is the detection value of the boost sensor 18. The amount is calculated. More specifically, an intake air amount calculation map as shown in FIG. 2 is stored in advance in the ROM of the control unit 11, and the intake air amount is calculated using the intake air amount calculation map. As is apparent from this intake air amount calculation map, the intake air amount increases as the intake negative pressure increases and the engine speed increases, and the intake air amount decreases as the intake negative pressure decreases and the engine speed decreases.

  Further, the opening degree of the throttle valve 12 is controlled by the control unit 11.

  The control unit 11 stops the fuel injection of the internal combustion engine 1 and stops the internal combustion engine 1 when an automatic stop condition (described later) is satisfied when the vehicle is temporarily stopped after the warm-up operation ends. Further, the control unit 11 automatically restarts the engine 1 when an automatic restart condition (described later) is satisfied.

  The automatic stop condition described above is, for example, that the select lever of the automatic transmission 3 is in the D range, the brake pedal is depressed by the driver (brake ON), the accelerator pedal is not depressed (accelerator OFF), and the vehicle speed is This is established when a condition such as 0 (km / h) is established. Also, the automatic restart condition is, for example, when the accelerator pedal is depressed by the driver (accelerator ON) during the automatic stop of the internal combustion engine 1 or when the brake pedal that was depressed by the driver is returned (brake OFF).

  Then, as shown in FIG. 3, the control unit 11 is in a state where the host vehicle does not request acceleration, that is, the accelerator pedal is not depressed (accelerator OFF), fuel injection is stopped, and the internal combustion engine 1 is idling. When the brake pedal is depressed (brake ON) and the lockup mechanism of the torque converter 2 is released, the internal combustion engine 1 is automatically stopped. This is because until the lockup is released, the internal combustion engine 1, the automatic transmission 3, and the axle are in a mechanically coupled state, and a change in friction of the internal combustion engine 1 affects the feeling of deceleration of the vehicle. Note that the rotation of the internal combustion engine 1 does not become “0” at the timing when the lockup mechanism of the torque converter 2 is released.

  Further, when the internal combustion engine 1 is automatically stopped during the coasting, the throttle opening is increased and the throttle opening is controlled so that the volumetric efficiency is constant. In the present embodiment, it is only necessary to secure the amount of air necessary for starting, so when the internal combustion engine 1 is automatically stopped and the volumetric efficiency is constant, the volumetric efficiency is about 20% regardless of the displacement. The throttle opening is controlled. In general, in order to make the volumetric efficiency constant, the throttle opening is controlled to increase in accordance with a decrease in the engine speed of the internal combustion engine 1.

  Then, when the brake pedal is returned (brake OFF) in a state where the internal combustion engine 1 is automatically stopped at the coast, excitation of the motor generator 8 is started and the internal combustion engine 1 is restarted. In other words, when the internal combustion engine 1 is automatically stopped during coasting, and the brake pedal is returned (brake OFF) when the rotation speed of the internal combustion engine 1 decreases toward “0” due to the automatic stop, Excitation of the motor generator 8 is started and the internal combustion engine 1 is restarted.

  Note that after the first explosion, the throttle opening is controlled to a throttle opening corresponding to the accelerator opening, and the control of the throttle opening so that the volumetric efficiency is constant is terminated. That is, after the first explosion, the throttle opening and volumetric efficiency are normally controlled.

  When there is a restart request of the internal combustion engine during the automatic stop of the internal combustion engine as in the prior art described above, the engine speed of the internal combustion engine at that time is within a predetermined restart prohibition region (800 to 200 rpm). In some cases, when the engine speed is prohibited until the engine speed falls below the lower limit value of the restart prohibition region, as shown in FIG. 4, the engine speed is the lower limit value of the restart prohibition region. Since the starter motor is excited after the following, the restart of the internal combustion engine by the starter motor is greatly delayed from the start request (brake OFF).

  On the other hand, in this embodiment, as shown in FIG. 3, when the brake pedal is returned (brake OFF) immediately during the coasting while the engine speed is decreasing due to the automatic stop of the internal combustion engine 1. Since the excitation of the motor generator 8 is started, the internal combustion engine 1 can be restarted as soon as possible in response to the start request.

  In the present embodiment, when the internal combustion engine 1 is automatically stopped during the coasting, the throttle opening is controlled to increase as the engine speed decreases, so that the pump loss is reduced and the internal combustion engine 1 is started. Since the torque is reduced, the internal combustion engine 1 whose engine speed is decreasing due to the automatic stop of the internal combustion engine 1 can be quickly restarted when necessary. Further, since the pump loss is reduced and the reduction rate of the engine speed due to the automatic stop of the internal combustion engine 1 can be reduced, the engine speed can be kept relatively high when the internal combustion engine 1 is automatically stopped. While the engine speed is decreasing due to the stop, the surplus torque of the motor generator 8 at the time of the automatic restart of the internal combustion engine 1 increases, and the startability of the internal combustion engine 1 at the coast can be improved.

  Further, in the present embodiment, when the internal combustion engine 1 is automatically stopped during the coasting, the throttle opening is controlled to increase the throttle opening so that the volumetric efficiency becomes constant. The variation in the amount is reduced, the torque shock becomes constant every time the first explosion is caused by automatic restart, and the internal combustion engine 1 can be restarted without giving the driver a sense of incongruity. In addition, since the volumetric efficiency is constant, it is easy to adapt the fuel and ignition timing, etc., the controllability at the time of restart (at the time of reacceleration) can be improved, and the cost can be reduced by reducing the man-hours. .

  In the present embodiment, since the intake air amount is calculated using the engine speed and the pressure in the intake passage, the engine speed of the internal combustion engine 1 is in a very low speed region such as before the stop. Even in such a case, the intake air amount can be accurately measured.

  In the above-described embodiment, when the internal combustion engine 1 is stopped during coasting, the throttle opening is controlled to increase the throttle opening so that the volumetric efficiency is constant. Also, by controlling the throttle opening according to the engine speed, the variation in the in-cylinder air amount of each cylinder can be reduced, and the torque shock becomes constant every time at the first explosion, without giving the driver a sense of incongruity. The internal combustion engine 1 that has been automatically stopped can be restarted.

  In this embodiment, the motor generator 8 serving as the starting means is responsible for the functions of the generator and the starter, but it is also possible to apply a starter motor having only the starter function as the starting means. It is. When the starter is a starter motor, the starter motor is started at the brake OFF timing in FIG. 3 described above.

  The technical ideas of the present invention that can be grasped from the above-described embodiments will be listed together with their effects.

  (1) A control device for an internal combustion engine that automatically stops and restarts the internal combustion engine in accordance with a driving condition of the vehicle, and controls the internal combustion engine that can automatically stop and restart the internal combustion engine even during coasting. In the apparatus, a starting means for starting the internal combustion engine, and a power transmission path between the internal combustion engine and the drive wheel are provided, and a lockup mechanism for intermittently connecting the power transmission path is provided. When the operation is stopped and the lockup mechanism is unlocked, the throttle opening is increased. As a result, the pump loss is reduced and the starting torque of the internal combustion engine is reduced, so that the internal combustion engine whose engine speed is decreasing due to the automatic stop of the internal combustion engine can be quickly restarted when necessary. . In addition, since the pump loss is reduced and the rate of decrease in the engine speed due to the automatic stop of the internal combustion engine can be reduced, the engine speed can be kept relatively high during the automatic stop, and the engine speed can be reduced by the automatic stop of the internal combustion engine. In the middle of the decrease, the margin torque of the starting means at the time of automatic restart of the internal combustion engine increases, and the startability of the internal combustion engine at the coast can be improved.

  (2) In the control device for an internal combustion engine according to (1), when the lockup of the lockup mechanism is released, the throttle opening is controlled so that the volumetric efficiency becomes constant. As a result, the torque shock becomes constant every time at the first explosion, and the internal combustion engine can be restarted without giving the driver a sense of incongruity. In addition, since the volumetric efficiency is constant, it is easy to adapt the fuel and ignition timing, etc., the controllability at the time of restart (at the time of reacceleration) can be improved, and the cost can be reduced by reducing the man-hours. .

  (3) The control device for an internal combustion engine according to (1) or (2) is provided in an intake passage on the downstream side of the throttle valve, and pressure detecting means for detecting the pressure in the intake passage on the downstream side of the throttle valve; Engine speed detecting means for detecting the engine speed of the internal combustion engine, and calculating the intake air amount using the detected value of the pressure detecting means and the detected value of the engine speed detecting means. . As a result, even when the engine speed of the internal combustion engine is in an extremely low rotation region such as before stopping, the intake air amount can be accurately measured.

  (4) The control device for an internal combustion engine according to (1) is provided in an intake passage on the downstream side of the throttle valve, and includes pressure detection means for detecting a pressure in the intake passage on the downstream side of the throttle valve; An engine speed detecting means for detecting the engine speed, and when the lockup mechanism is unlocked, the detected value of the pressure detecting means and the detected value of the engine speed detecting means Accordingly, the throttle opening is controlled. As a result, the torque shock becomes constant every time the first explosion occurs, and the internal combustion engine that has been automatically stopped can be restarted without causing the driver to feel uncomfortable.

The system block diagram of the control apparatus of the internal combustion engine which concerns on this invention. Explanatory drawing which shows the example of a characteristic of an intake air amount calculation map. The timing chart explaining the operation | movement of the automatic stop of the internal combustion engine at the time of a coast in the control apparatus of the internal combustion engine which concerns on this invention, and an automatic restart. The timing chart explaining the operation | movement of the automatic stop and automatic restart of the internal combustion engine at the time of the conventional coast.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Torque converter 3 ... Automatic transmission 5 ... Drive wheel 8 ... Motor generator 9 ... Control unit

Claims (3)

A control device for an internal combustion engine that performs automatic stop / automatic restart of the internal combustion engine in accordance with a driving condition of the vehicle, wherein the internal combustion engine is capable of automatic stop / automatic restart even during coasting,
Starting means for starting the internal combustion engine;
Wherein provided in the power transmission path between the engine and the drive wheels, it has a lock-up mechanism for intermittently the power transmission path,
During coasting, when the internal combustion engine is automatically stopped and the lock-up mechanism is unlocked, the throttle opening is increased and the throttle opening is controlled so that the volumetric efficiency is constant. Control device for internal combustion engine. A pressure detecting means provided in the intake passage on the downstream side of the throttle valve, for detecting the pressure in the intake passage on the downstream side of the throttle valve;
Engine speed detecting means for detecting the engine speed of the internal combustion engine,
The detected value of said pressure detecting means, the control apparatus for an internal combustion engine according to claim 1, characterized in that for calculating the intake air amount using a detected value of the engine speed detecting means. A control device for an internal combustion engine that performs automatic stop / automatic restart of the internal combustion engine in accordance with a driving condition of the vehicle, wherein the internal combustion engine is capable of automatic stop / automatic restart even during coasting,
  Starting means for starting the internal combustion engine;
  A pressure detecting means provided in the intake passage on the downstream side of the throttle valve, for detecting the pressure in the intake passage on the downstream side of the throttle valve;
  Engine speed detecting means for detecting the engine speed of the internal combustion engine;
  A lockup mechanism that is provided in a power transmission path between the internal combustion engine and the drive wheel and interrupts the power transmission path;
  When the internal combustion engine is automatically stopped during the coasting and the lockup mechanism is unlocked, the throttle opening degree is determined according to the detection value of the pressure detection means and the detection value of the engine speed detection means. A control device for an internal combustion engine, characterized in that control is performed to enlarge the engine.

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