JPH0447425Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a rotational speed control device for controlling the rotational speed of an internal combustion engine, and particularly to a rotational speed control device that can switch the controlled rotational speed.

[Prior Art] Some conventional rotational speed control devices are capable of switching the controlled rotational speed. For example, in an outboard motor, in order to prevent the engine from being damaged due to overspeeding, control is performed such as stopping the ignition spark when the engine speed exceeds approximately 6000r/min to prevent overspeeding. When the engine overheats, a device is used that sends a signal from an overheat sensor and switches the control speed to approximately 2,500 r/min to prevent the engine from seizing up and to enable minimal navigation.

[Problem that the invention attempts to solve]

In such conventional devices, since the control rotational speed is switched by an external signal, there is a problem that the control rotation speed is switched at a time when the driver does not expect it. For example, when an outboard motor overheats and the controlled rotational speed changes from 5900 r/min to 2500 r/min, the rotation is decreasing, and there is no serious danger. However, when switching from 2500r/min to 5900r/min, if the driver forgets to return the throttle and leaves it in the full throttle position, the engine speed will rise rapidly at the same time as the speed changes and the outboard motor will Vessels equipped with this system suddenly accelerate, posing serious dangers such as the driver being thrown off, or the vessel spinning out of control and colliding with another vessel. In order to avoid such a danger, the signal from the overheat sensor is held in a holding circuit so that the controlled rotational speed is maintained at about 2500 r/min even if the signal from the overheat sensor disappears. However, the holding circuit is not released unless the engine is stopped, and when the overheating condition becomes normal and high-speed running is to be resumed, the engine must be stopped and restarted, making operation cumbersome.

As described above, the conventional device has the problem that there is a danger when switching the rotation speed, and that it becomes cumbersome to operate in order to avoid the danger.

This idea was created to solve the problems mentioned above, and it avoids the dangers when changing the engine speed and allows the engine to change speed without the need for troublesome operations such as stopping and restarting the engine. An object of the present invention is to obtain a rotation speed control device for an internal combustion engine that can perform the following steps.

[Means for solving problems]

The rotational speed control device according to this invention includes means for controlling the engine rotational speed to a first predetermined value, overheat detection means for detecting overheating of the engine, and controlling the engine rotational speed from the first predetermined value when the engine overheats. means for controlling to a lower second predetermined value; means for detecting that control is being performed to the second predetermined value;
means for prohibiting switching to the first predetermined value even if the overheating condition is eliminated while the engine speed is controlled to a predetermined value; Means is provided to enable switching to the first predetermined value after control to the value is stopped.

[Effect]

In this device, switching to the first predetermined value is prohibited during control operation using the second predetermined value, so even if the external signal is switched, the rotation speed will not fluctuate, avoiding the risk of sudden acceleration. can. In addition, when the engine speed falls below the speed at which the speed control is performed, it becomes possible to switch to the first predetermined value by an external signal.
There is no need to stop or restart the engine.

〔Example〕

Examples of this invention will be described below with reference to the drawings. In Fig. 1, 1 is a generator coil of a magnet generator driven by the engine, 2 is a diode that rectifies the AC output of the generator coil 1, and 3 is a diode 2.
4 is a signal coil that generates an ignition signal at the ignition timing of the engine;
5 is a diode that rectifies the alternating current output of the signal coil 4; 6 is a resistor that controls the rectified output current of the diode 5; and 7 is a resistor that receives the output of the signal coil 4 and conducts at the ignition timing of the engine to charge the capacitor 3. The first thyristor 8 is an ignition coil that conducts the discharged charge of the capacitor 3 to the primary coil and generates a high voltage in the secondary coil.
9 is a spark plug that discharges in response to the high voltage of the ignition coil 8 and ignites the engine; 10 is a diode that rectifies the AC output of the signal coil 4; 11 is a capacitor that is charged by the rectified output of the diode 10; 12; 13 is a resistor that divides the voltage of the capacitor 11; 14 is a second thyristor that receives the divided voltage by the resistors 12 and 13 and becomes conductive to short-circuit the output of the generating coil 1; 15 and 16 divide the voltage of the capacitor 11 A resistor 17 is a third thyristor that conducts in response to the divided voltage of the resistors 15 and 16 and short-circuits the output of the generator coil 1. 18 is a third thyristor that conducts the short-circuit current of the generator coil 1 that flows when the third thyristor 17 is conductive. A resistor that generates a voltage drop, 19 a diode that passes the voltage drop generated in the resistor 18 and blocks reverse current, 20 a capacitor that is charged by the current flowing through the diode 19, and 21 conductive upon receiving the voltage of the capacitor 20. transistor, 2
2 is a battery mounted on the engine, and 23 is a thermosensor mounted on the engine, which is made of bimetal, and when the engine temperature exceeds a certain value, the contacts close and become conductive. 24 is a resistor that limits the current flowing to the thermosensor 23, and 25 is a transistor that receives current from the battery 22 via the resistor 24 and becomes conductive.

Next, the operation will be explained. The AC output generated in the generator coil 1 is rectified by the diode 2 and charged into the capacitor 3 in the direction shown. When a signal is generated in the signal coil 4, this signal is applied to the gate of the first thyristor 7 via the diode 5 and the resistor 6, and the first thyristor 7 becomes conductive, and the charge in the capacitor 3 is transferred to the ignition coil. A high voltage is generated in the secondary coil of the ignition coil 8. This high voltage is applied to the spark plug 9, which discharges and ignites the engine.

On the other hand, the AC output of the signal coil 4 is connected to the diode 1.
0, and the capacitor 11 is charged. The signal coil 4 is a coil built into the magnet generator, and generates a voltage proportional to the rotation speed of the magnet generator, that is, the engine rotation speed. Therefore, capacitor 1
The voltage 1 is a DC voltage that increases and decreases in proportion to the engine speed. The voltage of the capacitor 11 is the voltage of the resistor 12,1
3 and resistors 15 and 16 and supplied to the gates of the second and third thyristors 14 and 17, respectively. When the divided voltage reaches the gate trigger voltage, the second and third thyristors 14 and 17 The current is turned on, the output of the generating coil 1 is short-circuited, and the ignition spark of the ignition plug 9 is stopped. Since the voltage of the capacitor 11 is proportional to the engine speed, the voltage divided by the resistors 12 and 13 and the resistors 15 and 16 is also proportional to the engine speed.
Since the gate trigger voltages 4 and 17 are approximately constant values, the second and third thyristors 14 and 17 become conductive when the rotation speed of the engine exceeds a predetermined constant speed.
The ignition spark of the spark plug 4 is stopped to control the engine speed.

Here, the resistance 1 is larger than the voltage division ratio of resistances 12 and 13.
The partial pressure ratio of 5 and 16 is set smaller, so that the third thyristor 17 is lower than the second thyristor 14.
Since the thermosensor 23 is in an open state in the normal operating state where it is kept conductive at a lower rotational speed, the voltage of the battery 22 flows into the base of the transistor 25 through the resistor 24, and the voltage of the battery 22 flows into the base of the transistor 25 through the resistor 24.
5 is in a conductive state, and the third thyristor 1
Since the gate and cathode of the third thyristor 17 are short-circuited, the third thyristor 17 remains non-conductive. Therefore, the rotation of the engine is controlled only by the second thyristor 14. Next, when the engine overheats and the thermosensor 23 is closed, the transistor 2
The base current of transistor 5 becomes zero, transistor 25 becomes non-conductive, and third thyristor 17 is triggered by the divided voltage of resistors 15 and 16. Therefore, during overheating, the engine speed is controlled to a lower speed than in normal operating conditions. While the third thyristor 17 is conducting, that is, controlling the engine speed, the short-circuit current of the generator coil 1 flows through the resistor 18, causing a voltage drop.
The capacitor 20 is charged through the capacitor 9, and the voltage on the capacitor 20 makes the transistor 21 conductive. Therefore, the base and emitter of the transistor 25 are short-circuited by the transistor 21, the transistor 25 remains non-conductive, and the thermosensor 2
3 returns to the closed state, the transistor 25 is prohibited from becoming conductive, and the control rotational speed of the engine is prohibited from switching. When the engine speed is lowered to a speed at which no speed control is performed, the third thyristor 17 becomes non-conductive, the voltage drop across the resistor 18 becomes zero, and the capacitor 20 is no longer charged, so the terminal voltage decreases and the transistor 21 The base of
When the forward voltage between the emitters becomes lower than that, the transistor 21 becomes non-conductive. Therefore, when the thermosensor 23 returns to the open state, the transistor 25
becomes conductive and the third thyristor is no longer triggered, so that the controlled rotational speed of the engine returns to the rotational speed controlled by the second thyristor 14.

In the above embodiment, the thermosensor 23 is used as the overheat detection means, but the same effect can be obtained by using a switch that detects a decrease in engine oil, cooling water, or the like.

[Effect of idea]

As described above, according to this invention, switching of the control rotation speed is prohibited during the control operation using the lower control rotation speed of the two types of control rotation speeds, and when the engine rotation speed falls below the control rotation speed, control is performed. It is possible to switch the rotation speed, avoiding dangers caused by sudden acceleration, and since the control rotation speed is automatically switched, there is no need to stop or restart the engine, and all you need to do is operate the throttle. It gets easier.

[Detailed explanation of the idea] FIG. 1 is a circuit diagram of this device.

1... Generator coil, 3, 11, 20... Capacitor, 4... Signal coil, 7, 14, 17... Thyristor, 8... Ignition coil, 12, 13, 1
5, 16, 18...Resistor, 21, 25...Transistor, 23...Thermosensor.

Claims (1)

[Scope of utility model registration request] An ignition coil that ignites the engine, an ignition circuit that controls the current flowing through the ignition coil, and an ignition circuit that controls the ignition spark generated in the ignition coil when the engine speed exceeds a predetermined value. A rotation speed control device for an internal combustion engine including a rotation speed control circuit that controls the rotation speed, comprising means for controlling the engine rotation speed to a first predetermined value, overheat detection means for detecting overheating of the engine, and overheating of the engine. means for controlling the engine speed to a second predetermined value lower than the first predetermined value; means for detecting that the engine speed is being controlled to the second predetermined value; Even if the condition is resolved, the first
means for prohibiting switching to a predetermined value, and means for prohibiting switching to the first predetermined value after the engine rotation speed falls below a second predetermined value and control to the second predetermined value is stopped when the engine speed is not in an overheating state. A rotation speed control device for an internal combustion engine, characterized in that it is equipped with means for enabling switching.