JPH10311231A - Output controller for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure excellent ignition combustion at engine low load operation time while restraining the occurrence of a pumping loss by gradually quickening the valve opening timing of an intake valve toward the intake upper dead center as a demand load becomes high in an output controller to control output of an internal combustion engine by changing the valve opening period of the intake valve. SOLUTION: An electronic control unit 30 controls driving of an intake valve driving actuator 8, an exhaust valve driving actuator 11 and a fuel injection valve 15 by inputting output signals of a load sensor 41 and a crank angle sensor 42. That is, an exhaust valve 10 is controlled so that the valve is opened before the exhaust lower dead center and the valve is closed when going over the intake upper dead center. On the other hand, an intake valve 7 is controlled so that the valve is opened in the vicinity of the intake lower dead center at engine low load operation time and the valve opening timing is slightly delayed by gradually quickening the valve opening timing toward the intake upper dead center as a demand load becomes high. Therefore, comparatively strong turbulence is generated in a combustion chamber 5 at engine low load operation time, and ignition combustion can be excellently performed on an air-fuel mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an output control device for an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, the engine output is usually controlled by a throttle valve disposed in an engine intake passage. However, when the engine output is controlled in this manner, a large pumping loss occurs when the throttle valve opening is small. Therefore, there is known an internal combustion engine in which the throttle valve is removed in order to prevent such pumping loss from occurring, and the engine output is controlled by changing the opening period of the intake valve (Japanese Patent Application Laid-Open No. 55-55980). −12861
No. 0). In this internal combustion engine, the opening timing of the intake valve is fixed near the intake top dead center, and the closing timing of the intake valve is gradually delayed as the required load increases.

[0003]

In particular, in order to obtain good combustion during low-load operation of the engine, it is necessary to generate strong turbulence in the combustion chamber at the end of the compression stroke in which the mixture is ignited. There is. However, in the above-described internal combustion engine, during low engine load operation, the intake valve is opened for a certain period from the intake top dead center. In this case, while the intake valve is open, the pressure in the combustion chamber becomes slightly lower than the atmospheric pressure, and the intake air flows into the combustion chamber at a low speed. As a result, only weak turbulence will occur in the combustion chamber. In addition, since the turbulence occurs much before the piston reaches the bottom dead center of the intake stroke, the turbulence is almost attenuated at the end of the compression stroke, and thus there is a problem that good combustion cannot be obtained.

[0004]

According to the present invention, there is provided an output control apparatus for controlling the output of an internal combustion engine by changing an opening period of an intake valve. Is low, the intake valve is opened only near the intake bottom dead center, and the opening timing of the intake valve is gradually advanced toward the intake top dead center as the required load increases. That is, during low engine load operation, the intake valve is opened only near the intake bottom dead center where a large negative pressure is generated in the combustion chamber, so that when the intake valve is opened, the intake air flows into the combustion chamber at a high speed. Thus, strong turbulence is generated in the combustion chamber.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is a spark plug, 7 is an intake valve, and 8 is intake air. A valve driving actuator, 9 is an intake port, 10 is an exhaust valve, 11 is an exhaust valve driving actuator, and 12 is an exhaust port. The intake port 9 is connected to a surge tank 14 via a corresponding intake branch 13, and a fuel injection valve 15 is attached to each intake branch 13. The surge tank 14 is connected to an air cleaner 17 via an intake duct 16. As shown in FIG. 1, no throttle valve is provided in the intake duct 16.

The electronic control unit 30 is composed of a digital computer, and is connected to a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35, An output port 36 is provided. A load sensor 41 that generates an output voltage proportional to the amount of depression L of the accelerator pedal 40 is provided to the accelerator pedal 40.
Is connected, and the output voltage of the load sensor 41 is
The signal is input to the input port 35 via the converter 37. Further, the input port 35 has a crank angle sensor 42 for generating an output pulse every time the crankshaft rotates, for example, by 30 °.
Is connected. On the other hand, the output port 36 is connected to the actuators 8 and 11 and the fuel injection valve 15 via the corresponding drive circuit 38.

FIG. 2 is an enlarged view of the actuator 8 for driving the intake valve. Referring to FIG. 2, reference numeral 50 denotes a disc-shaped iron piece mounted on the top of the intake valve 7, 51 and 52 denote solenoids disposed on both sides of the iron piece 50, and 53 and 54 denote compression springs disposed on both sides of the iron piece 50. Are shown respectively. When the solenoid 51 is energized, the iron piece 50 rises, and the intake valve 7 closes.
On the other hand, when the solenoid 52 is energized, the iron piece 50 descends, and the intake valve 7 opens. Therefore, each solenoid 5
By controlling the energizing timings 1 and 52, the intake valve 7 can be opened and closed at an arbitrary time. The exhaust valve driving actuator 11 also has the same structure as the intake valve driving actuator 8 shown in FIG. 2, so that the exhaust valve 10 can be opened and closed at any time.

FIG. 3 shows the opening period of the exhaust valve 10. In the embodiment according to the present invention, the opening period of the exhaust valve 10 is fixed, and as shown in FIG. 3, the exhaust valve 10 opens before the exhaust bottom dead center, and the exhaust top dead center, that is, the intake top. Close the valve a little beyond the dead center. On the other hand, FIGS. 4A and 4B show the opening period of the intake valve 7. In FIG. 4B, the horizontal axis represents the amount of depression L of the accelerator pedal 40, that is, the required load. As shown in FIGS. 4A and 4B, during low engine load operation, the intake valve 7 is opened only near the intake bottom dead center. On the other hand, when the depression amount L of the accelerator pedal 40 increases, that is, when the required load increases, the intake valve 7
Is gradually advanced toward the intake top dead center, and the valve opening timing IC of the intake valve 7 is slightly delayed. That is, the opening period of the intake valve 7 is gradually increased as the required load increases. In the embodiment according to the present invention, as shown in FIG. 1, no throttle valve is arranged in the intake passage, and the amount of intake air supplied into the combustion chamber 5 is controlled by the intake valve 7.
Is controlled by changing the valve-opening period.

In the present invention, during low engine load operation, the intake valve 7 is opened only near the intake bottom dead center. Therefore, a large negative pressure is generated in the combustion chamber 5 immediately before the intake valve 7 opens. On the other hand, since no throttle valve is disposed in the intake passage, the pressure in the intake port 9 is substantially equal to the atmospheric pressure. Therefore, when the intake valve 7 is opened, the intake air flows into the combustion chamber 5 at a high speed, so that strong turbulence is generated in the combustion chamber 5. On the other hand, if strong turbulence is generated in the combustion chamber 5 near the intake bottom dead center in this way, the combustion chamber
A relatively strong turbulence continues to occur in the interior, and thus the mixture is ignited and burned well.

In the embodiment according to the present invention, the air-fuel ratio is made rich during the full load operation, and the air-fuel ratio is controlled to the stoichiometric air-fuel ratio in the other operation states. The basic injection time TP required to bring the air-fuel ratio to the stoichiometric air-fuel ratio is determined in advance as a function of the engine speed N and the required load L in the form of a map shown in FIG.
It is stored in the OM32. FIG. 6 shows an operation control routine of the engine. Referring to FIG. 6, first, step 6
0, the valve opening timing IO and the valve closing timing IC of the intake valve 7 according to the required load L shown in FIG. 4B are calculated, and then at step 61, the exhaust valve 10 according to the required load L
Of the valve opening timing EO and the valve closing timing EC are calculated. In the embodiment according to the present invention, the valve opening timing EO and the valve closing timing EC of the exhaust valve 10 are fixed. Next, at step 62, the basic injection time TP is calculated from the map shown in FIG.
Next, at step 63, the injection time TAU is calculated based on the basic injection time TP.

[0011]

According to the present invention, it is possible to secure good ignition combustion, particularly during low-load operation of the engine, while suppressing the occurrence of pumping loss.

[Brief description of the drawings]

FIG. 1 is an overall view of an internal combustion engine.

FIG. 2 is an enlarged side sectional view of an actuator for driving an intake valve.

FIG. 3 is a diagram showing opening / closing valve timings of an exhaust valve.

FIG. 4 is a diagram showing the opening / closing valve timing of an intake valve.

FIG. 5 is a diagram showing a map of a basic injection time.

FIG. 6 is a flowchart for controlling the operation of the engine.

[Explanation of symbols]

 7 ... intake valve 10 ... exhaust valve 15 ... fuel injection valve

Claims (1)

[Claims] In an output control device for controlling the output of an internal combustion engine by changing the opening period of an intake valve, when the required load is low, the intake valve is opened only near the intake bottom dead center. An output control device for an internal combustion engine wherein the opening timing of an intake valve is gradually advanced toward intake top dead center as the load increases.