JPH0318669A - Engine ignition device - Google Patents

Abstract

PURPOSE:To prevent an engine from generating abnormal noise by providing a delay circuit for delaying action of an overspeed governing circuit when an accelerator opening is shifted from a value above a fixed value to a value below the fixed value. CONSTITUTION:When an accelerator switch 13 is made ON, a transistor 44 is made OFF, therefore a transistor 50 is made ON, combined resistance of a resistance 41 and a resistance 32 becomes small, and engine revolution speed becomes high. In this case, if a set revolution speed is set higher than a set revolution speed of an overspeed governing circuit 40A, ignition of the engine is continued. Then when the switch 13 is made OFF from ON, the transistor 50 slowly becomes from ON to OFF being delayed by a delay circuit consisting of a resistance 47 and a condenser 49, so the engine does not miss fire promptly but misses fire being delayed by a fixed time, therefore abnormal noise on the engine is not generated. Relation between elapsed time of the switch 13 from ON to OFF, and engine revolution speed in this case, is that engine revolution speed is slowly increased and set revolution speed of the circuit 40A is also slowly increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention... This invention relates to an ignition system for internal combustion engines such as snowmobiles that uses an automatic centrifugal clutch.

[Prior technology] There is a problem with snowmobiles and other vehicles that use automatic centrifugal clutches, where the cab of the vehicle freezes due to icing, etc., and the cab opens even when the accelerator lever is released, causing the vehicle to drive out of control. As a countermeasure to this problem, it has been conventionally considered to install an accelerator switch that detects the opening degree of the accelerator lever and a cab switch that detects the opening degree of the cap, and use that logic to prevent the vehicle from running out of control, as shown in Figure 3. However, in this case, it has been considered to prevent runaway from the logic of the accelerator switch and the engine speed in terms of complexity and reliability by providing two switches. This logic is illustrated in FIG. C that performs the logic shown in Figure 4
A DI internal combustion engine ignition system is shown in Figure 5. In Fig. 5, (1) is the generating coil of a magnet generator driven by an engine (not shown). Generates AC output in synchronization with engine rotation. (2) is a diode (3) that rectifies the AC output of this generator coil (1).
The capacitor (4) charged by the rectified output of the power supply circuit (4) is a power supply circuit, one end of which is connected to one end of the generator coil (1), and the other end is grounded. (5) is a signal coil that generates an ignition signal in response to the engine's ignition timing, and is attached to the magnet generator. Generates AC output in synchronization with engine rotation. (6) is a diode that rectifies the alternating current signal of the signal coil (5), (7) is a resistor that limits the rectified output Tf of the signal coil (5), (8) is an ignition coil,
9) is a thyristor which conducts upon receiving the ignition signal from the signal coil (5) and discharges the charge in the capacitor (3) to the ignition coil (8) at the engine ignition timing. (10) is a resistor, which is connected between the gate and cathode of Cyrisk (9), and biases the gate of Cyrisk (9). (11) is a diode, whose anode is connected to one end of the capacitor (3>). and its cathode is grounded (12
) is a spark plug that sparks when it receives the high voltage generated in the ignition coil <8>. (13> is the accelerator switch,
The overspeed prevention circuit (40), one end of which is connected to the power supply from the power supply circuit (4>) and the other end grounded, consists of the following components: {20} is the ignition signal source; A diode (21) rectifies the AC output of a certain signal coil (5).
The resistor (22〉) that limits the rectified output current of 5) is the resistor (2
1) is a resistor that divides the rectified voltage of the signal coil (5), and (23) is a resistor. One end is connected to the power supply. The other end is connected to the connection point between the resistor (21) and the resistor (22). (24〉 is a diode. Its cathode is connected to one end of the resistor (23), and its anode is grounded. (25) is the resistor (21) and the resistor (23〉).
A transistor (26) is a resistor connected to the collector of the transistor (25). (27> is a capacitor. Transistor (2
5) is charged through the diode (28) when it is in a conductive state, and discharged when the transistor (25) is in a cut-off state. (2) charges the capacitor (27). Also, the diode (30) is a capacitor (27) that blocks reverse current.
A capacitor (31) is a transistor that conducts/cuts off conduction in response to the terminal voltage of the capacitor (30), (32) is a resistor through which the base current of the transistor (31) flows, and i33) is a resistor. One end thereof is connected to the collector of the transistor (3l), and the other end is grounded. (34> is a capacitor charged when the transistor (31) is turned on, (35> is a capacitor (34)
) is a resistor that controls the discharge of electric charge. (36) is the resistance〈33
〉 and the resistor (35) are connected and cut off by the divided voltage.
- The transistor (37) is a resistor connected to the collector of the transistor (36), and <38) is a thyristor, which is connected to short-circuit the half-wave that contributes to ignition of the AC output of the energizing coil (1>). (39) is a resistor that biases the gate of Cyrisk (38).

A conventional engine ignition system is configured as described above, and the AC output of the generator coil (1) is rectified by the diode (2).
Charge the capacitor (3). The electric charge charged in the capacitor (3) is transferred to the signal coil (5) at the ignition timing of 11%.
It is discharged to the ignition coil (8) through the thyristor (9) which becomes conductive at the ignition signal. When the charge of the capacitor (3) is discharged to the primary coil of the ignition coil (8). In the secondary coil. High voltage is generated. Sparks fly to the spark plug (12). The ignition signal from the signal coil (5>) is also supplied to the overspeed prevention circuit (40) at the ignition timing of the engine.

The AC output of the signal coil (5) is rectified by the diode (20) and becomes a half-wave pulsating output, which is then connected to the resistors (21) and (2).
2). This divided voltage is applied to the transistor (
25).

This transistor (25) is D7a of the signal coil (5>
When the output voltage reaches the conduction level, it becomes conductive, and when it is below it, it is cut off. Therefore, the transistor 25) is repeatedly turned on and off for each cycle of the output voltage waveform of the signal coil (5). In other words, transistor {25} repeatedly turns on and off in synchronization with engine rotation. When the transistor (25) becomes conductive, the capacitor (27) is rapidly charged from the power supply circuit (4) through the diode (28). A constant charge determined by the capacitance of this capacitor (27) is N'r?! .Transistor (25
) is cut off, the charge on the capacitor (27) is transferred to the resistor (
26) and is added to the power of the power supply circuit (4). Charges the capacitor (30) through the diode (29). In this way, the capacitor (30) is connected to the signal coil (5〉
A fixed amount of charge is charged every cycle of the output voltage waveform of the capacitor (30), and the fixed amount of charge is discharged to charge the capacitor (30).

On the other hand, the capacitor (
27) is charged to the capacitor (30). If the terminal voltage of this capacitor {30} is a steady state voltage. A resistor (
The base current flows through 32). Transistor (31
) becomes conductive. Also, if the R voltage rises above the steady state, no base current will flow. The transistor (31) is in a cut-off state for a certain period of time. The capacitor (34) is connected when the transistor (31) is conductive. It is rapidly charged to the power supply voltage. When the transistor (31) is cut off, it is discharged through the resistors (33) and (35) with a time constant determined by these resistors (3 3 ) and (3 5 ). This discharge continues until the transistor (3■) becomes conductive. Transistor (3
As long as 1) is conductive, the transistor (36) maintains a conductive state because the base current flows through the resistor (35). If the above transistor <36> is in a conductive state. Since no voltage is applied to the gate of the thyristor (38), the thyristor (38) continues to be in a cut-off state. The half-wave that contributes to the ignition of the generator coil (1) is not short-circuited and engine ignition is performed normally. On the other hand, if the transistor (36) is in the cut-off state, the thyristor (38) is passed through the resistor (37).
) because a voltage is applied to the gate of the thyristor (38)
becomes conductive. Therefore, the half wave that contributes to the ignition of the generator coil (1) is short-circuited, so the engine ignition is stopped and the engine speed decreases.

Now, set the engine's idle speed to the set speed N (clutch-in speed). When the engine speed is less than the set speed N1, transistor 1 (31) is cut off and then conducts for a period of time, so that the capacitor (34) is rapidly charged and rises to the power supply voltage.Transistor (31)
6) is maintained in a conductive state by receiving the terminal voltage of this capacitor (34>).Since the cyrisk (38) continues to be in a cut-off state, engine ignition is performed normally.

Furthermore, when the engine speed reaches the set speed N1 or higher and reaches E, the transistor (31) is continuously cut off. Since the terminal voltage of capacitor <34> decreases, the transistor (
36> is reversed from conduction to cutoff state and the thyristor (38)
When voltage is applied to the gate, the gate changes from cutoff to conduction, shorting the half-wave that contributes to the ignition of the generator coil (1). Therefore, when the set rotation speed N1 is reached, engine ignition stops,
The engine rotational speed will not rise above the set rotational speed N1, and overspeeding of the engine will be prevented. again. When the v1 function rotation speed decreases below the set rotation speed N1, the thyristor (38) is switched back to the cut-off state and normal engine ignition is performed.Next, when the accelerator switch (13) is turned on/off, the setting The engine ignition operation according to the rotation speed N. will be described below.When the accelerator switch (13) is turned on, the overspeed prevention circuit (40) will be disabled.As shown in the table in Fig. 4, the set rotation speed will be N, the engine is ignited.
On the other hand, when the accelerator switch (13) is turned off. When the engine speed is below the set rotation speed N, engine ignition continues as described above, but when the engine speed exceeds the set rotation speed N1, an abnormality occurs as described above, and the engine ignition is stopped and a misfire occurs. [Problems to be Solved by the Invention] In the conventional engine ignition system as described above, when the accelerator is fully closed during high-speed driving, the accelerator opens and the set rotation speed N is exceeded. Close the accelerator after passing through an area of number N1 or more. Set rotation speed N. Reach the following areas. In this case, even if there is no abnormality such as icing on the carburetor, when the accelerator is closed and the number of revolutions N or higher, a temporary misfire will occur, resulting in poor operation performance, and when the misfire turns into ignition. There was a problem with the engine making an unpleasant noise. Additionally, when driving at high speeds, the same phenomenon occurs even if the accelerator is repeatedly opened and closed, and an abnormal noise is produced when the accelerator is closed and then opened.

This invention was made to solve these problems. By providing a delay circuit, the overspeed prevention circuit is not activated for a short period of time, such as when the throttle is closed from a high-speed state, thereby preventing a temporary misfire from occurring and causing abnormal noise from the engine. The purpose of the present invention is to obtain an engine ignition system that prevents

[Means for Solving the Problems] An engine ignition device according to the present invention is as follows. An ignition circuit performs ignition operation in synchronization with engine rotation, an accelerator switch detects the accelerator opening of the engine, and detects the engine rotation speed. An engine ignition system comprising: an over-speed prevention circuit that prevents the ignition circuit from igniting when the rotational speed of the engine is above a predetermined value and the accelerator opening is below a predetermined value based on the accelerator switch. The vehicle is equipped with a delay circuit that delays the operation of the overspeed prevention circuit when the accelerator opening changes from a predetermined value or more to a predetermined value or less.

[Operation] In this invention. During normal operation with the accelerator switch on, the overspeed prevention circuit should not operate, and when the accelerator switch is off. In the event of abnormal operation, the overspeed prevention circuit is activated by a delay circuit when a predetermined time limit has elapsed. [Embodiment] Fig. 1 is a diagram showing a circuit of a CDI type engine ignition system according to an embodiment of the present invention. ．． In the figure (1) to (39>
is the same as the conventional one. (42) is a resistor, one end of which is connected to the power supply, and the other end connected to the accelerator switch (l3). (43) is a Zener diode whose cathode is connected to the accelerator switch (13), and whose anode is connected to the pace of the transistor (44) whose emitter is grounded. (45) is a resistor. One end of it is the power supply, and the other end is the transistor《4
4) are connected to the respective collectors. (46) is a diode whose anode is connected to the collector of transistor (44). Its cathode is connected to the base of a transistor (50) whose emitter is grounded. (47) is a resistor, one end of which is a diode (46)
The other end is connected to the cathode of the terminal, and the other end is grounded. (48) is a resistor, one end of which is a diode (46)
The other end is connected to the cathode of the capacitor (
49). (50> is a transistor whose emitter is grounded, its base is the cathode of the diode (46), and its collector is the resistor (41)
The bases of the transistors (31) are connected to each other via the respective bases of the transistors (31).

In addition. The overspeed prevention circuit (40A) is the same as the conventional overspeed prevention circuit (4o) except that a resistor (41) is added. Also. This over-rotation prevention circuit (40A) has two set rotation speeds. In other words, 4. When the accelerator switch is on (accelerator open), the set rotation speed is high, and when the accelerator switch is off (accelerator closed), the set rotation speed is low.
(corresponds to the set rotation speed N of the conventional example). Figure 2 shows the situation when the throttle is closed from a high speed state when the cab is in a normal state with no ice. In the engine ignition system configured as described above, the engine ignition operation and the operation of the overspeed prevention circuit are the same as before. If you turn off the accelerator switch (13) now, the transistor (44) will become conductive. Transistor (5
0) becomes non-conductive. The combined resistance of resistance (41) and resistance (32) becomes large. The engine speed becomes lower. In this case, if the set rotation speed N, is set, if the set rotation speed N1 or less. Ignite the engine. Set rotation speed N. In the above case, stop the engine6. On the other hand, turn on the accelerator switch (13). Since the transistor (44) becomes non-conductive, the transistor (50) becomes conductive, and the combined resistance of the resistor (4l) and the resistor (32) becomes smaller.The engine speed increases.In this case, the set rotation speed If N' is set higher than the aforementioned set rotation speed N, engine ignition continues.Also, when the accelerator switch (13) is turned from on to off, the transistor (50> changes from on to resistor (47)). Since the transistor (50) is gradually turned off with a delay due to the delay circuit formed by the capacitor (49) and the engine, the engine does not misfire immediately, but after a predetermined time delay. No sound is generated. In this case, the function system of the elapsed time from ON to OFF of the accelerator switch (13) and the engine speed is shown in Figure 2. In Figure 2, the lI112 line is the overspeed prevention line. The rotation speed characteristics of the circuit (40A).The solid lines indicate the engine rotation speed characteristics.In this case, the engine rotation speed shown by the solid line gradually increases, but the set rotation speed of the overspeed prevention circuit (40A) shown by the broken line also increases. The engine will not misfire due to gradual increase.

In addition,#! Examples include an example in which the overspeed prevention circuit is inoperable for a predetermined period of time after the accelerator is closed.

[Effect of the invention] This invention is as explained above. an ignition circuit that performs an ignition operation in synchronization with the rotation of the engine; an accelerator switch that detects the accelerator opening of the engine; In an engine ignition system having an overspeed prevention circuit that prevents the ignition circuit from igniting when the accelerator opening is below a predetermined value based on an accelerator switch, the accelerator opening changes from above a predetermined value to below a predetermined value. and a delay circuit that delays the operation of the overspeed prevention circuit when the accelerator switch is turned on, so that the overspeed prevention circuit is not activated during normal operation when the accelerator switch is turned on. With the accelerator switch off. n During normal operation, the overspeed prevention circuit is activated by the delay circuit when a predetermined time limit has elapsed, so that abnormal noise from the engine can be prevented even when the engine is running at high speed and the accelerator is fully idle. effective.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a CDI type internal combustion engine ignition system according to an embodiment of the present invention, Fig. 2 is an operational characteristic diagram of the present invention, and Fig. 3
Figures 4 and 4 are diagrams showing conventional runaway prevention logic tables. Figure 5 is a circuit diagram of a conventional CDI type internal combustion engine ignition system. In the figure. (l)...Generating coil. (2) Diode, (3) Capacitor, (5) Signal coil, (8> Ignition coil. (13) Accelerator switch, (40A) Overspeed prevention circuit i47 )...
Resistor, (49)... capacitor, (50)... transistor. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] an ignition circuit that performs an ignition operation in synchronization with the rotation of the engine; an accelerator switch that detects the accelerator opening of the engine; In an engine ignition system having an overspeed prevention circuit that prevents the ignition circuit from igniting when the accelerator opening is below a predetermined value based on an accelerator switch, the accelerator opening changes from above a predetermined value to below a predetermined value. An engine ignition system characterized by comprising a delay circuit that delays the operation of the overspeed prevention circuit when the engine ignition is shifted.