JPS631749A - Method of operating engine without causing knocking - Google Patents

Abstract

PURPOSE:To prevent occurrence of knocking with ease, by delaying an ignition timing by a prescribed angle or enriching an air fuel ratio by a prescribed ratio when a cooling water temperature is greater than a prescribed value and a wall temperature is exceeded by a prescribed temperature. CONSTITUTION:An exhaust gas passage 9 is provided with a CO sensor S1, a cooling water jacket 7 with a cooling water temperature sensor S2, a combustion chamber wall with a wall temperature sensor S3, an air cleaner 8f with an intake air temperature sensor S4, and a throttle valve 8c with an opening sensor S5, outputs from these sensors being applied to a small computer CPU. The CPU selects an ignition timing and an air fuel ratio of air fuel mixture based on sensed wall and cooling water temperatures using a previously prepared map for controlling an ignition coil 6b and a fuel injection valve 8h. In the case, when a cooling water temperature is greater than a prescribed value (about 80 deg.C) and a wall temperature is greater than the cooling water temperatures by a prescribed value (about 3 deg.C), an ignition timing is delayed by a prescribed angle or an air fuel ratio is enriched by a prescribed ratio.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of operating a spark ignition engine to prevent knocking, and in particular detects at an early stage an operating condition where engine knocking is likely to occur and delays the ignition timing. At the same time, by adjusting the air-fuel ratio to a high angle or richly adjusting the air-fuel ratio to create a condition where knocking is less likely to occur, in other operating conditions, select an advanced ignition timing and a lean air-fuel ratio to enable economical operation. Regarding driving methods.

[Conventional technology and its problems]

In recent years, the ignition system and fuel injection system of high-speed automobile engines use sensors to detect engine operating conditions such as engine speed, intake negative pressure, intake air temperature, and coolant temperature, and use these signals to operate a small computer. The ignition timing and fuel injection amount are set for each cycle according to a characteristic map prepared in advance.

On the other hand, when setting the characteristic map, the ignition timing and fuel injection amount are set so that knocking often occurs even under the most severe operating conditions that the engine may be subjected to. In order to prevent non-king due to delay, the ignition timing is retarded, or the air-fuel ratio of the air-fuel mixture is set to zero, and the engine compression ratio is set to a low value, assuming severe operating conditions that would cause knocking. Because of this, there is a problem with poor fuel economy.

[Object of the invention, outline of the structure]

This invention eliminates the above-mentioned problems and makes it possible to operate an engine that combines excellent economic efficiency and high output.The invention is designed to overcome the harsh operating conditions in which knocking is likely to occur, and is greatly affected by the wall temperature of the combustion chamber. This technology focuses on the fact that the combustion chamber wall becomes higher in temperature than the cooling water temperature.In engines where the outer surface of the combustion chamber wall is a cooling water jacket, A wall temperature sensor is installed on the combustion chamber wall and a cooling water temperature sensor is installed on the cooling water jacket.The cooling system is equipped with a small computer that selects the ignition timing and air-fuel ratio of the mixture from among preset characteristics based on the detection signals of these sensors. When the water sensor detects a temperature above a predetermined value and the wall temperature sensor detects a wall temperature exceeding the predetermined temperature, the small computer retards the ignition timing by a predetermined angle or adjusts the air-fuel ratio. It is characterized by selecting at least one of controlling the concentration by a predetermined ratio.

〔Example〕

Hereinafter, the invention will be explained with reference to the illustrated embodiment. In the figure, 1 indicates a 4-stroke, 4-cylinder engine.

2 is the combustion chamber of this engine, cylinder block 3
, a cylinder head 4 and a piston 5. 6a is a spark plug with an electrode facing into the combustion chamber 2; s
b is an ignition coil that supplies power to the ignition plug 6a, and 6c is a distributor. A cooling water jacket 7 is provided in the cylinder block 3 and cylinder head 4 so as to surround the combustion chamber 2.

As is well known, an intake passage 8 and an exhaust passage 9 are connected to the combustion chamber 2 via an intake valve 2a and an exhaust valve 2b, respectively. The intake passage 8 includes a branch pipe 9a for each cylinder connected to the cylinder head 4, a surge tank Bb, a throttle valve Be driven by the accelerator pedal, and a collecting pipe connecting the upstream side of the throttle valve 8C to an air flow meter 8d. 8e and an air cleaner 8f, the upstream end of which is open to the atmosphere, and 08h is a fuel injection valve provided for each branch pipe 8a.

The exhaust passage 9 is a relatively long exhaust pipe 9b extending from an exhaust manifold 9a connected to the cylinder head 4.

The downstream end is open to the atmosphere through the three-way catalyst 9C and the illustrated exhaust muffler.

To explain the operation control system of this engine, the center of the control system is a small computer CPU, and the small computer CPU is installed in the exhaust passage 9 and includes a CO sensor S1 that detects the carbon monoxide concentration in the exhaust gas. , cylinder block 3
A cooling water temperature sensor S2 is installed on the jacket 7 of the cylinder block 3 to detect the cooling water temperature, a wall temperature sensor S3 is installed on the combustion chamber wall of the cylinder block 3 facing the combustion chamber 2, and an intake air temperature sensor S4 is installed on the air cleaner 8f. , the opening sensor S5 of the throttle valve 8C, each signal from the air flow meter 8d, and the ignition pulse obtained from the distributor C are used as signal sources, and the storage battery 11 is used as the power source. The output of the small ffi computer CPU is controlled by the above-mentioned signal source and power source to control the ignition of the electromagnetic fuel injection valve Bh1; the oil 6b, and inject the appropriate amount of fuel into the intake passage 8 at a timely manner to achieve approximately the stoichiometric air-fuel ratio. A mixture is generated, and high-voltage electricity is applied from the ignition coil 6b to the ignition plug 6m in a timely manner. With the exception of the description regarding the wall temperature sensor S3, the above description is generally very different from the configuration of a conventional engine.

To explain the characteristic i-tube used to set the ignition timing and air-fuel ratio, as shown in the graph in Figure 2, the engine crankshaft is calculated from the interval of ignition pulses obtained from the Distributoro C. When the intake air flow rate signal is calculated from the signal obtained from the air flow meter 8d and the crankshaft speed on the Y axis, the ignition timing is plotted on the Z axis. Or the air/fuel ratio is indicated. Note that the characteristics shown in the diagram relate to the ignition timing, and the larger the number in the diagram, the earlier the ignition timing.

Therefore, in this engine, 1 cooling water sensor S2 is activated during operation.
When detects that the engine is warmed up at around 80℃,
The steady state characteristic shown by the solid line is selected, but when the wall temperature sensor S3 detects a wall temperature that is 3° C. higher than that, the characteristic shown by the broken line is selected. That is, the ignition timing is retarded by about 5 degrees, and/or the air-fuel ratio is made richer by about υ1 to 2 than the stoichiometric mixture ratio.

〔Effect of the invention〕

As described above, the method for preventing engine knocking according to the present invention includes providing a wall temperature sensor on the combustion chamber wall and a cooling water temperature sensor on the cooling water jacket in an engine in which the outer surface of the combustion chamber wall is a cooling water jacket. Equipped with a small computer that selects the ignition timing and the air-fuel ratio of the air-fuel mixture from preset characteristics based on the sensor's detection signal, the cooling water sensor detects a temperature above a predetermined temperature, and the wall temperature sensor detects a temperature above a predetermined temperature. When a wall temperature exceeded by a predetermined amount is detected, at least the small computer selects either one of retarding the ignition timing by a predetermined angle or enriching the air-fuel ratio by a predetermined ratio. It is something. Therefore, by simply installing the sensor S3 that detects the wall temperature of the combustion chamber 2, it is possible to relatively easily detect that a state in which knocking is likely to occur is occurring. The ignition timing and air-fuel ratio in steady-state operation can be set to appropriate values by simply selecting the simplified characteristics, which has the effect of enabling economical operation.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a configuration diagram showing the configuration of an engine, and FIG. 2 is a characteristic diagram thereof. CPU...Small computer S1...CO
Sensor, S2...@-Cooling water temperature sensor, S3... Wall temperature sensor, 84, φ... Intake temperature sensor, S5... Opening degree sensor.

Claims (1)

[Claims] In an engine with a cooling water jacket on the outer surface of the combustion chamber wall, a wall temperature sensor is installed on the combustion chamber wall and a cooling water temperature sensor is installed on the cooling water jacket, and the ignition timing and air-fuel ratio of the mixture are determined in advance based on the detection signals of these sensors. It is equipped with a small computer that selects from among set characteristics, and when the cooling water sensor detects a temperature higher than a predetermined value and the wall temperature sensor detects a wall temperature exceeding the predetermined temperature, the small computer ignites. An engine knock prevention operating method which selects at least one of retarding the timing by a predetermined angle and controlling the air-fuel ratio to enrich by a predetermined ratio.