JP2024000899A - engine control device - Google Patents

Abstract

To suppress deterioration in startability of an engine.SOLUTION: An engine control device controls an engine such that after starting the engine during cold, the equivalence ratio becomes a target equivalence ratio based on a cooling water temperature at the time of engine startup and an integrated air amount, which is the integrated value of intake air amounts since startup of the engine. After starting the engine during cold, when the integrated air amount is small, the engine control device sets the target equivalence ratio to be larger as compared with that when the integrated air amount is large, and when the engine stalls after starting the engine during cold, resets the integrated air amount to a value 0.SELECTED DRAWING: Figure 2

Description

The present invention relates to an engine control device.

Conventionally, this type of engine control device calculates the basic fuel injection amount at startup based on the temperature at engine startup, and increases or decreases the basic fuel injection amount at startup depending on the time from engine stop to engine startup. A correction method has been proposed (for example, see Patent Document 1). This device is said to be able to maintain an appropriate equivalence ratio (air-fuel ratio) in the cylinder when the engine is repeatedly started at low temperatures.

Japanese Patent Application Publication No. 2010-138919

However, with the above engine control device, immediately after starting the engine when it is cold, the engine may not be warmed up enough and the engine may stall. As a method to suppress such engine stalls, after the engine is started, the cumulative air amount is calculated as the cumulative value of the intake air amount since the engine was started, as a parameter that reflects the warm-up state of the engine's combustion chamber. A possible method is to reduce the equivalence ratio as the integrated air amount increases. However, if an engine stall occurs immediately after starting the engine, and then when the engine is restarted, the equivalence ratio will not be sufficient to start the engine properly, since the cumulative air amount is large when the engine is started for the first time. If the equivalence ratio becomes excessively small compared to the possible equivalence ratio, it may not be possible to suppress the engine stall at the time of restarting, and the startability may deteriorate.

The engine control device of the present invention aims to suppress deterioration in engine startability.

The engine control device of the present invention includes:
After starting the engine when it is cold, the equivalence ratio becomes a target equivalence ratio based on the cooling water temperature at the time of starting the engine and the cumulative air amount that is the cumulative value of the intake air amount since starting the engine. An engine control device for controlling the engine, comprising:
After starting the engine when the engine is cold, the target equivalence ratio is set to be larger when the integrated air amount is small than when it is large;
The gist of the present invention is to reset the integrated air amount to a value of 0 when the engine stalls after starting the engine when the engine is cold.

In the engine control device of the present invention, after starting the engine when the engine is cold, the target equivalence ratio is set so that when the integrated air amount is large, the target equivalence ratio is smaller than when it is small. The cumulative air amount is a parameter that reflects the warm-up state of the combustion chamber of the engine, and when the cumulative air amount is small, it is considered that the combustion chamber has not warmed up as much as when it is large. Therefore, after starting the engine when the engine is cold, by setting the target equivalence ratio so that when the cumulative air volume is large, the target equivalence ratio is smaller than when the cumulative air volume is small, it is possible to warm up the combustion chamber of the engine when the cumulative air volume is small. Since the target equivalence ratio is increased when the engine speed is not progressing, it is possible to suppress engine stall and a decrease in engine startability. Then, when an engine stall occurs after starting the engine in a cold state, the integrated air amount is reset to a value of 0. As a result, after the engine is restarted after the engine stall, the cumulative air amount becomes a value of 0, and the target equivalence ratio is set larger than when the cumulative air amount is not a value of 0. As a result, engine stalling is suppressed, and deterioration in engine startability can be suppressed.

1 is a configuration diagram schematically showing the configuration of an automobile 20 equipped with an engine control device as an embodiment of the present invention. It is a flowchart which shows an example of the cold start post-processing performed by ECU30. FIG. 2 is an explanatory diagram showing an example of temporal changes in the rotational speed Ne of the engine 22, the target equivalence ratio φ*, and the integrated air amount Iqa.

Next, a mode for carrying out the present invention will be described using examples.

FIG. 1 is a block diagram schematically showing the structure of an automobile 20 equipped with an engine control device as an embodiment of the present invention. The automobile 20 of the embodiment includes an engine 22, a starter motor 24, a transmission 26, and an electronic control unit (hereinafter referred to as "ECU") 30, as illustrated. The ECU 30 mainly corresponds to the engine control device of the embodiment.

The engine 22 is configured as an internal combustion engine that outputs power using gasoline, light oil, or the like as fuel, for example. The starter motor 24 is connected to a crankshaft 23 serving as an output shaft of the engine 22, and cranks the engine 22. The transmission 26 includes an automatic transmission (not shown) whose output shaft is connected to a drive shaft 28 connected to the drive wheels DW via a differential gear DF, and a transmission between the crankshaft 23 and the input shaft of the transmission. A torque converter (not shown) connected to the engine 22 changes the speed of the power from the engine 22 and outputs the same to the drive shaft 28. Engine 22, starter motor 24, and transmission 26 are controlled by ECU 30.

Although not shown, the ECU 30 is configured as a microcomputer having a CPU, ROM, RAM, flash memory, and input/output ports. Signals from various sensors are input to the ECU 30 via input ports. Signals input to the ECU 30 include, for example, the cooling water temperature Tw from the water temperature sensor 22a that detects the temperature of the cooling water of the engine 22, and the intake air from the air flow meter 22b installed on the upstream side of the intake pipe throttle valve. Examples include the quantity Qa. Furthermore, the accelerator opening degree Acc from the accelerator pedal position sensor 42 that detects the amount of depression of the accelerator pedal 40 and the vehicle speed V from the vehicle speed sensor 44 can also be cited. Various control signals are output from the ECU 30 via an output port. Examples of the signals output from the ECU 30 include a control signal to the throttle valve of the engine 22, a control signal to the starter motor 24, and a control signal to the transmission 26. The ECU 30 determines the load factor of the engine 22 (the amount of air actually taken in in one cycle relative to the stroke volume per cycle of the engine 22) based on the intake air amount Qa from the air flow meter 22b and the rotation speed Ne of the engine 22. The volume ratio) KL is calculated.

In the automobile 20 of the embodiment configured in this manner, the ECU 30 sets the target gear Gs* of the transmission 26 based on the accelerator opening Acc and the vehicle speed V, and the gear Gs of the transmission 26 is set to the target gear Gs*. The transmission 26 is controlled so that. Further, the target torque Te* of the engine 22 is set based on the accelerator opening Acc, the vehicle speed V, and the gear position Gs of the transmission 26, and the engine 22 is controlled so that the engine 22 is operated based on the target torque Te*. Performs intake air amount control, fuel injection control, ignition control, etc.

In fuel injection control, the ECU 30 determines the equivalence ratio obtained by dividing the stoichiometric air-fuel ratio by the air-fuel ratio AF from the air-fuel ratio sensor installed upstream of the exhaust pipe purification device, based on the load factor KL of the engine 22. The target fuel injection amount Qfd* of the fuel injection valve is set so that φ becomes the target equivalence ratio φ*, and the fuel injection valve is controlled so that the target fuel injection amount Qfd* of fuel is injected from the fuel injection valve. Since intake air amount control and ignition control do not form the core of the present invention, detailed explanations will be omitted.

Next, the operation of the automobile 20 according to the embodiment configured as described above, particularly the setting of the target equivalence ratio φ* after cold starting the engine 22, will be described. FIG. 2 is a flowchart illustrating an example of the cold start post-processing executed by the ECU 30. This routine is executed after the ignition switch is turned on and the engine 22 is started by cranking the engine 22 using the starter motor 24 while the cooling water temperature Tw is below the predetermined temperature Tref (after the first explosion of the engine 22). ) is repeatedly executed at predetermined time intervals (for example, every few milliseconds).

When this routine is executed, the CPU of the ECU 30 inputs the starting water temperature Tws and the intake air amount Qa (step S100). The starting water temperature Tws is a value detected by the water temperature sensor 22a immediately after the engine 22 is started. As the intake air amount Qa, a value detected by the air flow meter 22b is input.

Subsequently, it is determined whether an engine stall has occurred after starting the engine 22 (step S110). When the engine stall has not occurred, the integrated air amount Iqa is calculated (step S130). The cumulative air amount Iqa is calculated by adding the intake air amount Qa input in step S100 to the cumulative air amount Iqa calculated the last time this routine was executed (previous Iqa, initial value is 0). The cumulative air amount Iqa is the cumulative value of the intake air amount Qa after the engine 22 is started.

Subsequently, a target equivalence ratio φ* is set using the integrated air amount Iqa and the starting water temperature Tws (step S150), and this routine ends. In step S150, the target equivalence ratio φ* is set so that when the starting water temperature Tws is high, it is smaller than when it is low, and from a value larger than 1, when the integrated air amount Iqa is large, the ratio is set when it is small. Set it so that it becomes smaller. The cumulative air amount Iqa is a parameter that reflects the warm-up state of the combustion chamber of the engine 22, and when the cumulative air amount Iqa is small, it is considered that the combustion chamber has not warmed up as much as when it is large. Therefore, after starting the engine 22 when the engine 22 is cold, the target equivalence ratio φ* is set from a value larger than 1 so that when the integrated air amount Iqa is large, it is smaller than when it is small. Engine stall can be suppressed when the amount Iqa is small and the combustion chamber of the engine 22 has not warmed up.

When an engine stall occurs after the engine 22 is started in step S110, it is determined whether the integrated air amount Iqa has been reset to the value 0 due to the current engine stall (step S120). If the cumulative air amount Iqa has not been reset to the value 0 due to the current engine stall, the cumulative air amount Iqa is reset to the value 0 (step S140), and the target equivalent is determined using the cumulative air amount Iqa and the starting water temperature Tws. The ratio φ* is set (step S150), and this routine ends. If the cumulative air amount Iqa has not been reset to the value 0 due to the current engine stall, the cumulative air amount Iqa is reset to the value 0 (step S140), and the target equivalent is determined using the cumulative air amount Iqa and the starting water temperature Tws. The ratio φ* is set (step S150), and this routine ends. If the cumulative air amount Iqa has already been reset to the value 0 due to the current engine stall, the target equivalence ratio φ* is set using the cumulative air amount Iqa and the starting water temperature Tws (step S150), and this routine ends. .

FIG. 3 is an explanatory diagram showing an example of temporal changes in the rotational speed Ne of the engine 22, the target equivalence ratio φ*, and the integrated air amount Iqa. In the figure, a solid line indicates an example, and a broken line indicates a comparative example. In the comparative example, when the engine 22 is started (time t0) and then stalled (time t1), the integrated air amount Iqa is not reset to the value 0. Therefore, from the time when the engine 22 is restarted (time t2), the integrated air amount Iqa is integrated from a value larger than the value 0, and the target equivalence ratio φ* becomes smaller and becomes less than the value 1, and becomes so-called lean. At this time, the combustion chamber of the engine 22 has not warmed up and the engine may stall again. In the embodiment, when the engine stalls (time t1), the integrated air amount Iqa is reset to the value 0. Therefore, from the time the engine 22 is restarted (time t2), the integrated air amount Iqa is integrated from the value 0, and the target equivalence ratio φ* becomes larger than the value 1, that is, becomes rich, so that engine stall is suppressed. . Thereby, deterioration in startability of the engine 22 can be suppressed.

According to the automobile 20 equipped with the engine control device of the embodiment described above, after starting the engine 22 when the engine is cold, the target equivalence ratio φ* is adjusted when the integrated air amount Iqa is small compared to when it is large. When the engine 22 stalls after starting the engine 22 when the engine 22 is cold, the integrated air amount Iqa is reset to a value of 0, thereby suppressing the deterioration of the startability of the engine 22.

The correspondence between the main elements of the embodiments and the main elements of the invention described in the column of means for solving the problems will be explained. In the embodiment, the ECU 30 corresponds to an "engine control device."

Although the embodiments of the present invention have been described above using examples, the present invention is not limited to these examples in any way, and may be modified in various forms without departing from the gist of the present invention. Of course, it can be implemented.

20 automobile, 22 engine, 22a water temperature sensor, 22b air flow meter, 23 crankshaft, 24 starter motor, 26 transmission, 28 drive shaft, 30 electronic control unit (ECU), 40 accelerator pedal, 42 accelerator pedal position sensor, 44 vehicle speed Sensor, DF differential gear, DW drive wheel.

Claims (1)

After starting the engine when it is cold, the equivalence ratio becomes a target equivalence ratio based on the cooling water temperature at the time of starting the engine and the cumulative air amount that is the cumulative value of the intake air amount since starting the engine. An engine control device for controlling the engine, comprising:
After starting the engine when the engine is cold, the target equivalence ratio is set to be larger when the integrated air amount is small than when it is large;
An engine control device that resets the integrated air amount to a value of 0 when the engine stalls after starting the engine when the engine is cold.

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