JPH0735748B2 - Engine controller - Google Patents

Description

TECHNICAL FIELD The present invention relates to an engine control device.

[Conventional technology]

Some conventional engine control devices perform fuel injection control and ignition control for each cylinder. In this case, a multipoint injection device is used for fuel injection control, and a low-voltage distribution ignition device is used for ignition control.

[Problems to be Solved by the Invention] In the above-described conventional engine control device, the operation can be continued even if there is a misfire in a specific cylinder. However, when unburned gas is discharged from the misfiring cylinder, this unburned gas burns near the exhaust pipe and heats the catalyst. As a result, the life of the catalyst is shortened and a fire may occur.

The present invention has been made to solve the above problems, and can prevent damage to the catalyst and the occurrence of a fire, and the number of terminals of the control means can be small, and the misfire detection can be performed. An object of the present invention is to obtain an engine control device that does not hinder normal engine operation due to abnormality of the means.

[Means for solving problems]

The engine control device according to the present invention inputs the voltage signal generated in the ignition coil in synchronization with the ignition timing of each ignition coil via the OR circuit, and determines the misfire state of each cylinder based on this voltage signal. Based on the outputs of the misfire detecting means for detecting, the misfire detecting means, the cylinder identification sensor and the crank angle sensor, it is determined which cylinder corresponds to which ignition coil is in the misfire state, and the fuel injection valve corresponding to the misfire cylinder is driven When it is determined that the cylinders corresponding to all the ignition coils are in the misfire state based on the outputs of the stop means for stopping, the misfire detection means, the cylinder identification sensor, and the crank angle sensor, the drive stop of the fuel injection valve is prohibited. It is provided with a prohibition means.

[Work]

The engine control device according to the present invention detects the misfire state of each cylinder by the misfire detection means and stops the fuel injection valve of the misfire cylinder. Further, since the misfire detection means receives the OR signal of the misfire state detection signal for each cylinder, only one input / output line is required and the number of terminals of the control means is reduced. Further, when it is determined that all the cylinders are in the misfire state, the driving stop of the fuel injection valve is prohibited.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. First
FIG. 1 shows the configuration of an engine control device according to an embodiment of the present invention, 1 is an engine control unit, 2 is a microcomputer, 3 is a fuel injection valve drive coil provided for each cylinder,
Reference numeral 4 is a timer connected to the microcomputer 2, 5 is a transistor provided between the timer 4 and the drive coil 3, 6 is an ignition coil for # 1 / # 3 cylinders, and 7 is ignition for # 2 / # 4 cylinders. Coil, 8 and 9 are transistors for driving the ignition coils 6 and 7, 10 and 11 are diodes connected to the primary side of the ignition coils 6 and 7, 13 and 14 are connected to the microcomputer 2, and transistors 8 and 9 are connected. A timer for giving ignition control signals Ig ₁ and Ig ₂ to 15 and a microcomputer 2 and a diode 1
It is a misfire detection means connected between 0 and 11. In addition, an input of the engine control unit 1 is input with an output of a cylinder identification sensor 16 which generates a cylinder identification signal for each specific cylinder, and a crank angle which produces a crank angle signal in synchronization with a predetermined crank angle position. The output of the sensor 17 is input.

Next, the operation of the above device will be described with reference to FIGS. The cylinder identification signal is generated for each specific cylinder, for example, the # 1 cylinder, and the crank angle signal is output for each of the # 1 to # 4 cylinders with a pulse width of BTDC75 ° to BTDC5 °. The microcomputer 2 calculates the drive timing and ignition timing of the fuel injection valve for each cylinder based on these signals, and the fuel injection valve drive signals Inj _{1 to} Inj ₄ are supplied to the drive coils 3 via the timer 4 and the transistor 5. Are sequentially added, and fuel injection is performed. Further, the ignition control signals Ig ₁ and Ig ₂ are applied to the transistors 8 and 9 via the timers 13 and 14, and the primary voltages 1c ₁ and Ic ₂ are alternately generated on the primary side of the ignition coils 6 and 7, whereby A high voltage is generated on the secondary side and the cylinders in the compression stroke are sequentially ignited. The primary voltages Ic ₁ and Ic ₂ are applied to the misfire detection means 15 (signal a) via the OR circuit composed of the diodes 10 and 11 and the output b thereof is applied to the microcomputer 2.

Now, if the ignition is normally performed, the misfire detection means
Output b of 15 is H and L at each ignition timing of each ignition coil.
repeat. Here, if the # 2, # 4 cylinder ignition coil 7 is broken, as shown by the dotted line in FIG.
Ic ₂ no longer occurs, and the ignition operations of the # 2 and # 4 cylinders are no longer performed. In this case, the input a of the misfire detection means 15 from the # 2 and # 4 cylinder ignition coils 7 also disappears, and the output b cannot be inverted at each ignition timing of each ignition coil. As a result, the microcomputer 2 is # 2,
The misfire of the # 4 cylinder is detected, the drive control signals Inj ₂ and Inj ₄ are stopped, and the fuel injection to the # 2 and # 4 cylinders is stopped. Therefore, the discharge of unfueled gas is prevented.

Also, even if no misfire has occurred, the diode 10,1
If the output b of the ignition detecting means 15 does not change at all due to the disconnection of the signal line ORed in ₁ , all the cylinders are misfired. In this case, the microcomputer 2 outputs the fuel injection signals Inj _{1 to} Inj ₄ as usual. Output and fuel injection for all cylinders. This is because it is unlikely that all the cylinders are in the misfire state, and in such a case, it is considered that the signal line from the OR circuit is disconnected. When all the cylinders actually go into misfire, the operation of the engine is stopped, so there is no problem.

Further, the microcomputer 2 and the engine control unit 1 have a shortage of input / output terminals due to the complicated control, but since the primary voltages Ic ₁ and Ic ₂ are integrated into one by the OR circuit by the diodes 10 and 11, It is only necessary to add one input terminal for the microcomputer 2 and the engine control unit 1.

In each of the above embodiments, one ignition coil is provided for every two cylinders, but an ignition coil may be provided for each cylinder.

〔The invention's effect〕

As described above, according to the present invention, when the cylinder misfires,
By detecting this, the fuel injection to the misfiring cylinder is stopped, the unburned gas is prevented from burning in the exhaust pipe, the life of the catalyst is shortened, and the occurrence of fire can be prevented. Further, since the misfire state detection signal for each cylinder is input through the OR circuit, the number of input terminals can be reduced. Further, when it is determined that all the cylinders are in the misfire state, the driving stop of the fuel injection valve is prohibited, so that the normal engine operation is not hindered by the abnormality of the misfire detection means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the invention device, and FIGS. 2 and 3 are operation waveform diagrams of respective parts of the invention device. 1 ... Engine control unit, 2 ... Microcomputer,
3 ... Fuel injection valve drive coil, 6, 7 ... Ignition coil, 10,
11 …… Diode, 15 …… Misfire detection means, 16 …… Cylinder identification sensor, 17 …… Crank angle sensor.

Claims (1)

[Claims] 1. A plurality of fuel injection valves provided corresponding to each cylinder of an engine having a plurality of cylinders, a plurality of ignition coils provided to ignite each of the cylinders, and a cylinder identification signal. A cylinder identification sensor, a crank angle sensor for generating a crank angle signal, and control for controlling the fuel injection valves and the ignition coils corresponding to the cylinders based on the outputs of the cylinder identification sensor and the crank angle sensor. Means and a voltage signal generated in the ignition coil in synchronization with the ignition timing of each ignition coil is input via an OR circuit, and misfire detection for detecting the misfire state of each cylinder based on this voltage signal. Means, and which ignition coil corresponds to which cylinder is in the misfire state based on the outputs of the misfire detection means, the cylinder identification sensor, and the crank angle sensor. If the cylinders corresponding to all the ignition coils are in the misfire state based on the outputs of the stop means for stopping the driving of the fuel injection valve corresponding to the misfiring cylinder, the misfire detecting means, the cylinder identification sensor and the crank angle sensor. An engine control device comprising: a prohibition unit that prohibits driving stop of the fuel injection valve when the determination is made.