JP6157139B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device that controls an internal combustion engine mounted on a vehicle.

  When the vehicle stops on an uphill road, the target value of the engine speed at the time of the restart is increased as the slope of the uphill road is larger in order to prevent the vehicle from slipping down during the restart and to ensure acceleration. It is conceivable to perform control to increase the engine torque by operating the throttle valve to an opening corresponding to the target rotational speed (for example, refer to the following patent document).

JP 2007-055434 A

  However, there is a time lag between the increase of the throttle opening and the increase of the intake amount actually filled in the cylinder. This time lag becomes more conspicuous as the throttle opening speed increases, in other words, as the engine torque required when the vehicle restarts increases. That is, depending on the throttle valve opening operation, sufficient engine torque cannot be secured, and the vehicle may slip down on the uphill road or the vehicle start-up acceleration may be delayed.

  The present invention has been made by paying attention to the above-mentioned problem for the first time, and an object of the present invention is to further improve the response at the time of restart of a vehicle stopped on an uphill road.

In the present invention, the internal combustion engine mounted on the vehicle is controlled. When the vehicle is stopped on an uphill road, the ignition timing is compared with the case where the vehicle is stopped on a road other than the uphill road. Control of the internal combustion engine that retards and increases the intake air amount and the fuel injection amount . In this case, the larger the upslope, the more retarded the ignition timing while the vehicle is stopped and the more the intake air amount and the fuel injection amount. Configured the device.

ADVANTAGE OF THE INVENTION According to this invention, the response at the time of re-starting when stopping on an uphill road can be improved further.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. The figure which shows the relationship between an ignition timing and the output torque of an internal combustion engine. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment performs according to a program.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (so-called required load), and a brake pedaling amount signal d output from a sensor that detects the amount of depression of the brake pedal The intake air temperature / intake pressure signal e output from the temperature / pressure sensor for detecting the intake air temperature and the intake pressure in the intake passage 3 (particularly, the surge tank 33), and the output from the water temperature sensor for detecting the cooling water temperature of the engine. The cam angle sensor outputs the cooling water temperature signal f and a plurality of cam angles of the intake camshaft or the exhaust camshaft. Angle signal g, the acceleration signal h such that acceleration or vehicle of a vehicle is outputted from an acceleration sensor for detecting the gradient of the road surface to be located is inputted.

  From the output interface, an ignition signal i is output to the igniter of the spark plug 12, a fuel injection signal j is output to the injector 11, an opening operation signal k is output to the throttle valve 32, and the like.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k corresponding to the operation parameters via the output interface.

  Thus, when the vehicle stops on the uphill road, the ECU 0 of the present embodiment secures the reserve torque by retarding the ignition timing, and reduces the engine torque (reserve) due to the retarded ignition timing. (Torque) is compensated by increasing the intake air amount and the fuel injection amount.

  When the driver requests to start the accelerator pedal again after stopping on the uphill road, the ECU 0 increases the opening amount of the throttle valve 32 to increase the amount of intake air charged into the cylinder 1, and at the same time, the injector 11 The fuel injection amount from the engine is increased to increase the engine torque.

  However, even if the throttle valve 32 is expanded, the amount of intake air charged in the cylinder 1 does not increase immediately. There is a time lag between the two, and the fuel injection amount cannot be increased sufficiently during the time lag. As a result, the increase in engine torque is delayed with respect to the start request, and the vehicle may slide down on the uphill road or the acceleration performance of the vehicle may be insufficient.

  In this embodiment, paying attention to the fact that the ignition timing change (advance / retard) can be completed instantaneously without a time lag, the ignition timing is retarded in advance while the vehicle is stopped on an uphill road, Prepare for a restart. In response to the start request, the ignition timing is advanced to quickly increase the engine torque to prevent the vehicle from slipping, and to improve the acceleration of the vehicle so as to realize a good “hill start”. I have to.

  FIG. 2 shows the relationship between the ignition timing and the engine torque when a certain intake air amount, fuel injection amount, and other operating parameters are assumed. The torque output by the internal combustion engine is maximized when the ignition timing is set to the MBT (Minimum Advance for Best Torque) point after compression top dead center, and decreases as the ignition timing is retarded (or advanced) from the MBT point. To do. Normally, the ignition timing is set to the most advanced timing within a limit that does not cause knocking in the cylinder 1.

  The ECU 0 of the present embodiment changes the ignition timing between when the vehicle is stopped on an uphill road and when the vehicle is stopped on a road other than the uphill road. The ignition timing T2 in the former case is set to a timing delayed from the ignition timing T1 in the latter case (which may coincide with the MBT point), that is, a timing farther from the MBT point. The difference between the engine torque at the ignition timing T1 and the engine torque at the ignition timing T2 is the reserve torque.

  Of course, if the ignition timing is simply retarded, the engine torque may be insufficient and an engine stall may occur. Therefore, the ECU 0 increases the intake air amount and the fuel injection amount charged in the cylinder 1 by performing an operation of increasing the opening of the throttle valve 32 as the ignition timing is retarded while the vehicle stops on the uphill road. This compensates for the torque drop by the reserve torque. As a result, while the ignition timing is set to T2, the engine torque during stopping on the uphill road is maintained at substantially the same magnitude as when the ignition timing is set to T1.

  The magnitude of the reserve torque, that is, the ignition timing retardation correction amount (the difference between the reference timing T1 and the retarded timing T2) and the opening amount of the throttle valve 32 (or the intake air amount increase) The amount) is preferably variable in accordance with the slope of the road surface where the stopped vehicle is located, the friction loss of the internal combustion engine itself or the drive system, or the magnitude of other mechanical loads on the internal combustion engine. .

  If the road surface has a large slope and a tight slope, the vehicle is likely to slide down and not to accelerate when the vehicle restarts. Therefore, the ECU 0 delays the ignition timing T2 while the vehicle is stopped and opens the throttle valve 32 more greatly as the upward gradient detected via the acceleration sensor is larger.

  Similarly, the friction loss of the internal combustion engine itself or the drive system is large. Specifically, the higher the temperature of the internal combustion engine or the drive system (engine cooling water temperature, torque converter and transmission oil temperature), the ignition timing during stopping. T2 is retarded more and the throttle valve 32 is opened more widely.

  In addition, the greater the mechanical load on the internal combustion engine, more specifically, the greater the amount of power generation (output voltage or current) of the generator operating by receiving the rotational driving force from the crankshaft, or the refrigerant of the air conditioner The greater the output of the compressor for compression (the greater the percentage of time the compressor is operating or the higher the refrigerant pressure), the more retarded the ignition timing T2 during stopping and the more the throttle valve 32 is opened. .

  In the memory of ECU0, external conditions such as road surface gradient, engine cooling water temperature, oil temperature of torque converter, etc., generator power generation, air conditioner ON / OFF or compressor output, etc. Stored is map data defining the relationship between the ignition timing T2 and the throttle opening (or intake air amount). The ECU 0 searches the map by using the parameter of the external condition being sensed as a key, and knows the ignition timing T2 and the throttle opening while the vehicle is stopped.

  FIG. 3 shows a procedure example of processing executed by the ECU 0 during the period from when the vehicle stops to when it restarts. The ECU 0 is an uphill road whose road surface gradient detected by the acceleration sensor when the vehicle speed detected via the vehicle speed sensor is 0 or less than a threshold value close to 0 (step S1). In the case of (Step S2), while the ignition timing is retarded to T2 (Step S3), an operation to widen the opening of the throttle valve 32 is performed to compensate for the torque drop by the reserve torque (Step S4). As the throttle opening increases, the amount of intake air that fills the cylinder 1 increases, and the fuel injection amount increases accordingly.

  On the other hand, when the road surface has an ascending slope of less than a predetermined value or the road surface is a flat road or a downhill road, the ignition timing is set to T1 closer to the MBT point than T2 (step S5).

  When a start request is made while the vehicle is stopped on an uphill road (step S6), the retarded ignition timing is advanced so as to approach the T1 or MBT point (step S7), thereby reducing the output torque of the internal combustion engine. Increase rapidly. In step S7, the ignition timing may be immediately shifted to the T1 or MBT point, or the greater the accelerator pedal depression amount in the start request, or the greater the accelerator pedal depression amount per unit time. The ignition timing may be greatly advanced from T2.

  In the present embodiment, the internal combustion engine mounted on the vehicle is controlled. When the vehicle is stopped on the uphill road, the ignition timing is compared with the case where the vehicle is stopped on a road other than the uphill road. The internal combustion engine control device 0 is configured to further retard the angle and increase the intake air amount and the fuel injection amount.

  According to the present embodiment, it is possible to further improve the response at the time of restart when the vehicle stops on an uphill road. That is, the engine torque can be instantaneously increased by advancing the ignition timing in response to a start request, so that the vehicle can be prevented from sliding down on an uphill road, and the acceleration performance of the vehicle can be improved, resulting in a smoother operation. Hill start is realized.

  When the vehicle stops on a flat road or a downhill road, it is permitted to set the ignition timing closer to the MBT point than when the vehicle stops on an uphill road. When stopping on an uphill road and when stopping on a flat road or downhill road, the control content is not the same, and by changing a part of it, sufficient engine torque necessary for restarting on the uphill road is obtained. While ensuring, fuel consumption can be reduced on flat roads or downhill roads to improve fuel efficiency.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, the vehicle speed sensor and the acceleration sensor are used to determine whether or not the vehicle has stopped on the uphill road.However, in the case where the acceleration sensor is not present, based on the vehicle speed and the accelerator opening, It is possible to determine whether the vehicle has stopped on an uphill road. Specifically, although the accelerator pedal is depressed and the accelerator opening is greater than or equal to a predetermined value, the vehicle is on the uphill road because the vehicle acceleration (the amount of increase in vehicle speed per unit time) is less than or equal to the predetermined value. Judge that it is located.

  In the above embodiment, in order to increase the intake air amount (and the fuel injection amount) charged in the cylinder 1 in step S4, the opening degree of the electronic throttle valve 32 is corrected to be enlarged. In an internal combustion engine equipped with a control valve, the opening degree of the idle speed control valve may be enlarged and corrected. As is well known, the idle speed control valve is a flow control valve that opens and closes a bypass that communicates the upstream side and the downstream side of the throttle valve 32 in the intake passage 3.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 11 ... Injector 12 ... Spark plug 32 ... Throttle valve a ... Vehicle speed signal h ... Acceleration signal i ... Ignition signal j ... Fuel injection signal k ... Opening operation signal

Claims (1)

Controlling an internal combustion engine mounted on a vehicle,
When the vehicle is stopped on an uphill road, the ignition timing is retarded and the intake air amount and the fuel injection amount are increased as compared with the case where the vehicle is stopped on a road other than the uphill road . A control device for an internal combustion engine that retards the ignition timing while the vehicle stops and increases the intake air amount and the fuel injection amount as the upward gradient increases .

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