JPH0231584Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ignition timing detection device using an ignition timing sensor that detects combustion light in an engine combustion chamber.

Such an ignition timing detection device converts the combustion light detected by the ignition timing sensor into voltage, compares this converted voltage with a reference voltage, and detects the time when the converted voltage exceeds the reference voltage as the ignition timing. but,
In conventional ignition timing detection devices, this reference voltage is held constant regardless of engine temperature. Even if the engine speed and load are constant, the combustion speed in the combustion chamber is delayed when the engine temperature is low, and the voltage rise is delayed accordingly. There is a problem that the timing detection time is delayed.

An object of the present invention is to provide an ignition timing detection device that can quickly detect ignition timing even when the engine temperature is low.

In order to achieve this object, the present invention converts the intensity of combustion light in the engine combustion chamber into an electrical signal, compares this electrical signal with a predetermined reference value, and determines whether the electrical signal matches the reference value. The gist of the ignition timing detection device is to detect the ignition timing of the engine when the value exceeds the reference value, the ignition timing detection device being characterized in that the reference value increases as the temperature of the engine increases.

In other words, in view of the fact that combustion light in the engine combustion chamber is generated sharply and strongly as the engine temperature rises, the reference value for ignition timing detection is increased in accordance with the engine temperature, so that the ignition timing detection can be adjusted according to the engine temperature. It is maintained at an optimal timing that is unrelated to the current situation.

Furthermore, in the ignition timing detection device of the present invention, if the comparison is made using a comparator and the reference value is created using a thermistor that detects the temperature of the engine, the intended purpose can be achieved with an extremely simple configuration. can be achieved.

In a preferred embodiment, the electrical signal and a reference value are compared in a comparator, and a thermistor whose resistance value changes depending on the engine temperature is connected to the reference value input of the comparator.

Embodiments of the present invention will be described with reference to the drawings.

Diesel engine odor sub-combustion chamber 1 in Figure 1
is provided within the cylinder head 2 and separated from the main combustion chamber 6 by a partition member 4. On the other hand, the main combustion chamber 6 is divided by a cylinder block 8 and a piston 10, and communicates with the sub-combustion chamber 1 through a port 12 of the partition member 4. The fuel injection nozzle 14 is attached to the cylinder head 2 and injects atomized fuel 16 into the auxiliary combustion chamber 1.
The ignition timing sensor 18 has an optical fiber 20 that propagates combustion light from the auxiliary combustion chamber 1 to the outside of the engine, and is attached to the cylinder head 2 so that the light input portion at the lower end is located within the range of the fuel 16. The range of the fuel 16 is the range where the combustion flame is generated and the range where the light incident part of the ignition timing sensor 18 is cleaned by the fuel. The output of the ignition timing sensor 18 is transmitted through the optical fiber 22.
The signal is then sent to the electronic control unit.

FIG. 2 is a circuit diagram of the ignition timing detection device. A photodiode 26 as a photoelectric conversion element and a resistor 28 are connected in series to each other and connected to a voltage terminal 30.
The connection point 31 between the two is connected to the positive phase terminal of an operational amplifier 32 as a comparator. Further, the thermistor 34 and the resistor 36 are connected in series with each other and connected to the voltage terminal 30, and a connection point 38 between the two is connected to the opposite phase terminal of the operational amplifier 32. Combustion light is transmitted to the photodiode 26 via the optical fiber 22, and the thermistor 34 is attached to the cylinder block 8 to detect the temperature of the engine cooling water. Therefore, the resistance of the thermistor 34 is
It decreases as the engine cooling water temperature rises. The operational amplifier 32 has a positive phase terminal voltage, that is, a converted voltage Vb of the output of the ignition timing sensor 18, and a negative phase terminal voltage,
That is, when the voltage is higher than the reference voltage Vr, a high level voltage is generated at the output terminal, and the time when this high level voltage is generated is detected as the ignition timing.

FIG. 3 shows the change in converted voltage Vb during fuel ignition with a solid line. When the engine is at high temperature, combustion occurs quickly and in a short time, so the converted voltage Vb rises quickly and has a large peak value. On the other hand, when the engine is at a low temperature, combustion is slow and takes a long time, so the converted voltage Vb rises slowly and has a small peak value. As a result of the resistance value of the thermistor 34 increasing as the engine cooling water temperature decreases, the reference voltage Vr decreases as the engine cooling water temperature T decreases as shown in FIG. The timing of high level voltage generation at the terminals is advanced when the engine temperature is low. This makes it possible to quickly detect the ignition timing even when the engine is at a low temperature and the conversion voltage Vb rises slowly.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the installation position of the ignition timing sensor.
FIG. 2 is a circuit diagram of the ignition timing detection device, FIG. 3 is a diagram showing changes in converted voltage during fuel ignition, and FIG. 4 is a graph showing the relationship between engine cooling water temperature and reference voltage. 1... Sub-combustion chamber, 18... Ignition timing sensor, 2
6...Photodiode, 32...Operation amplifier,
34...Thermistor.

Claims (1)

[Scope of Claim for Utility Model Registration] Converting the intensity of combustion light in an engine combustion chamber into an electrical signal, comparing this electrical signal with a predetermined reference value, and determining that the electrical signal exceeds the reference value. An ignition timing detection device for detecting a time as an ignition timing of the engine, wherein the reference value increases as the temperature of the engine increases.