JPH0419375B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a device that prevents an internal combustion engine from being destroyed by excessive rotation (hereinafter referred to as overspeed prevention). The present invention attempts to provide an anti-rotation device.

Overspeeding of an internal combustion engine is prevented by stopping fuel supply or stopping ignition of a spark plug.

Among these, the present invention will be described with respect to a case in which overspeed is prevented by stopping the ignition of the spark plug. In this case, the rotational speed of the engine is detected by the rotation detector, and the output of the engine rotational speed is used to stop the operation of the ignition device, the energization of the ignition coil, and the ignition of the ignition plug.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an ignition signal generator that generates an ignition signal according to the rotation of the internal combustion engine, 2 is an ignition pulse circuit that receives the ignition signal and outputs an ignition pulse having an appropriate closing rate, and 3 is a circuit that generates an ignition signal according to the ignition pulse. a switching circuit that drives the ignition coil 5;
4 is a power terminal connected to the ignition coil 5; 6 is a rotation detector that detects the rotation speed of the engine from the ignition signal generated by the ignition signal generator 1, and compares the detected rotation speed with a set rotation speed; It has a comparison means and generates an output when the detected rotational speed increases to a set rotational speed. 7 passed the output of the rotation detector 6 in synchronization with the ignition signal (the output of the rotation detector 6 was passed after the primary current of the ignition coil was cut off).
An ignition stop circuit 8 outputs an ignition stop signal and is a bypass circuit that responds to this ignition stop signal and bypasses the ignition pulse input from the ignition pulse circuit 2 to the switching circuit 3 to ground. Reference numeral 9 denotes a temperature detector that detects the temperature of the engine, such as the temperature of lubricating oil in a predetermined portion, and lowers the set rotation speed of the rotation detector 6 as the detected temperature increases.

Next, the operation will be explained. First, normal ignition operation will be described. The ignition signal generator 1 generates an ignition signal according to the rotation of the internal combustion engine, and this ignition signal is transmitted to the ignition pulse circuit 2, the rotation detector 6, and the ignition stop circuit 7.
is input. The ignition pulse circuit 2 processes this ignition signal and outputs an ignition pulse having an appropriate closure rate. The switching circuit 3 turns on and off the energization of the ignition coil 5 in accordance with this ignition pulse. When the ignition coil 5 is cut off, an ignition voltage is generated at its output, and the engine is ignited and operated.

Next, the ignition stop operation will be described. When the engine speed becomes higher than a set value, the rotation detector 6 outputs a rotation detection signal. The ignition stop circuit 7 receives this rotation detection signal and the ignition signal, and outputs an ignition stop signal synchronized with the ignition signal. That is, even if the rotation detection signal is started while the ignition coil 5 is energized, the ignition stop signal is started after the ignition coil 5 is turned off, thereby preventing the occurrence of wasted fire at times other than the ignition timing.

The bypass circuit 8 operates according to this ignition stop signal, and connects the ignition pulse circuit 2 to the switching circuit 3.
bypasses the ignition pulse input to ground. Therefore, the input signal to the switching circuit 3 is cut off, the energization of the ignition coil 5 is stopped, and the ignition voltage output from the ignition coil 5 is no longer generated. This reduces the engine speed and prevents overspeeding.

Next, when the engine speed falls below the set value, the rotation detector 6 stops outputting the rotation detection signal, and the ignition stop circuit 7 and bypass circuit 8 each cease to operate.
An ignition pulse is input to the switching circuit 3, and the energization of the ignition coil 5 is resumed.

Incidentally, as an input signal for detecting the rotation speed, the output of the ignition signal generator 1 may not be directly used, but any switching output of the subsequent stage may be used.

Incidentally, the above-mentioned overspeed prevention device is generally provided in high-output engines. The reason for this is that high-output engines are designed to be able to operate at higher speeds than normal engines, and are designed to produce higher output.

For this reason, there is a danger that high-output engines will be operated at higher speeds that are closer to the limits of the engine's component parts than normal engines, and as mentioned above, overspeed prevention is required to prevent the engine from rotating beyond the set speed. We need to protect our institutions.

On the other hand, heat damage is another important issue in the engine. As mentioned above, high-output engines are often operated at high rotation speeds, which also means that they are often operated at high loads, and the permissible temperature of the engine components becomes an issue.

For example, if the engine is operated for a long time with an abnormally high oil level, the oil loses its viscosity and the piston seizes up.In addition, in a supercharged engine, the supercharger This is a major problem that can lead to breakdowns.

Before reaching this high temperature state, low rotation,
It is necessary to protect the engine by limiting its operating range to light loads.

Therefore, in the present invention, when the temperature inside the engine increases,
This protects the engine by lowering the operating speed of the above-mentioned overspeed prevention mechanism.

That is, in the embodiment shown in FIG. 1, the set rotation speed of the rotation detector 6 is lowered at high temperatures by the detection force of the temperature detector 9.

FIG. 2 shows an example of the temperature characteristics of the set rotation speed of this rotation detector 6. In this figure, the horizontal axis shows the temperature and the vertical axis shows the set rotation speed.

In this way, if the temperature detector 9 detects the oil temperature of the engine and controls the set rotation speed to decrease at high temperature, piston seizure as described above can be avoided.
Alternatively, failure of the supercharger can be prevented.

Although the above description has been made regarding the case where the ignition of the spark plug is stopped, it is obvious that the same over-speed prevention can also be achieved by stopping the fuel supply.

As described above, according to the present invention, in the overspeed prevention device that detects the engine speed and limits the engine speed to a set speed or less, the set speed for overspeed prevention is changed depending on the temperature, and By lowering the operating speed at times, it is possible to limit the engine speed at high temperatures to a low speed, thereby providing the effect that the engine can be more accurately protected. In addition, since the above temperature is the detected engine oil temperature, it is possible to accurately detect that the oil viscosity decreases at high temperatures and control the engine's rotational speed limit to be lowered, further preventing engine seizure failures. Can be prevented accurately.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the ignition device of the present invention;
FIG. 2 is a diagram showing an example of the temperature characteristics of the overspeed prevention rotation speed. In the figure, 1 is an ignition signal generator, 2 is an ignition pulse circuit, 3 is a switching circuit, 4 is a power terminal, 5 is an ignition coil, 6 is a rotation detector, 7 is an ignition stop circuit, 8 is a bypass circuit, and 9 is a A temperature sensor is shown.

Claims (1)

[Claims] 1. In an overspeed prevention device that detects the rotation of an internal combustion engine and limits the maximum rotational speed of the internal combustion engine to a set rotational speed to prevent damage due to excessive rotation of the internal combustion engine, the oil temperature of the internal combustion engine is detected, An over-speed prevention device for an internal combustion engine, comprising means for controlling the set rotation speed to decrease as the detected temperature increases.