JP2011027044A - Ignition device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition device for an internal combustion engine, stably performing "soft-on" or "soft-off" of an ignition coil for the internal combustion engine of a motorcycle or the like with the reduced number of components. <P>SOLUTION: In this ignition device for the internal combustion engine, a capacitor C<SB>1</SB>is charged prior to power distribution to the primary winding 141 of the ignition coil 14, and the capacitor C<SB>1</SB>is discharged by turning on a power distribution switch Q<SB>1</SB>. When an ON signal is inputted into the control terminal of the Q<SB>1</SB>, the charged charge of the C<SB>1</SB>is discharged through a discharge circuit 13 by negative feedback to the control terminal of the Q<SB>1</SB>. When an OFF signal is inputted into the control terminal during the power distribution to the primary winding 141, the capacitor C<SB>1</SB>is charged through a charge circuit 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technology for energizing an ignition coil for so-called "soft-on" or "soft-off" of a switch connected to an ignition coil for an internal combustion engine such as a motorcycle. The present invention relates to an internal combustion engine ignition device capable of operating.

Conventionally, a circuit shown in FIG. 8 is known as an ignition device for an ignition coil for an internal combustion engine of a motorcycle. In the ignition device 8 of FIG. 8A, when the ignition signal S ₀ changes from the H level to the L level in the state where the coil energization signal S ₁ is at the H level (that is, when the transistor Q ₀₂ is turned off), the transistor Q ₀₁ Is suddenly turned on, and a current (primary current I _{IGN, 1} ) flows through the primary winding 811 of the ignition coil 81. In the ignition device 8, as shown in the waveform diagram of FIG. 8B, LC resonance vibration is generated by the stray capacitance and inductance of the ignition coil in the process of increasing the primary current I _IGN , and thereby the secondary voltage V _IGN is reduced. The ignition voltage VF (for example, 1 kV) may be exceeded, and erroneous ignition may occur.

In order to eliminate this inconvenience, for example, the ignition device 9 shown in FIG. 9A is used.
In the ignition device 9 performs the transistor Q ₂₂ is turned off, by turning on the transistor Q _31, Q _32, the charge of C ₁₁ through R _11. As a result, the base voltage of the transistor Q ₁₁ gradually increases with a time constant of R ₁₁ × C ₁₁ , so that the base current of the transistor Q ₁₁ also increases gradually, so that the transistor Q ₁₁ is so-called soft-on.

In the ignition device 9, as shown in the waveform diagram of FIG. 9B, the primary current I _IGN does not vibrate, so the secondary voltage V _IGN does not exceed the ignition voltage VF (the secondary voltage in the figure). V _IGN is 900V).

  However, since the ignition device 9 of FIG. 9A does not have a negative feedback configuration, there is a problem in that the influence of variations in the characteristics of the component parts is great, and it takes time to design and evaluate. For example, every time the ignition coil 91 changes, it is necessary to newly design and evaluate.

In addition, the ignition device 9 has a complicated circuit configuration, a large number of parts, and a high manufacturing cost. In order to secure the capacitor charging time constant (R ₁₁ × C ₁₁ ), it is necessary to increase at least one of the resistor R ₁₁ and the capacitor C ₁₁ .
If an attempt is made to increase the value of the resistor R ₁₁ , the base current of the transistor Q ₁₁ cannot be guaranteed. For this reason, the value of the capacitor C ₁₁ must be increased, resulting in an increase in the size of the device.

Further, in the ignition device 9 of FIG. 9A, the current flowing to the base via the resistance (R ₅₁ , R ₅₂ ) of the discharge circuit provided for soft-off is large because the capacity of C ₁₁ is large. It takes time to decrease to near zero (see FIG. 7B described later). As a result, it takes time to turn off the transistor Q _11, to the power loss increases, also the size of the radiator.

Further, in the above circuit, a current drive type (bipolar transistor or the like) can be used as a transistor, but in the case of a voltage drive type switching element (MOSFET, IGBT, etc.) having a threshold value for a control input, the threshold value becomes a boundary. In order to suppress the LC resonance vibration in order to turn on and off, the above charging time constant (R ₁₁ × C ₁₁ ) needs to be considerably increased, which is not practical.

  An object of the present invention is to provide an internal combustion engine ignition device suitable for “soft-on” or “soft-off”, which can perform stable operation with a small number of parts.

  Another object of the present invention is to downsize the capacitor or downsize the energizing switch in addition to the above-mentioned purpose.

The ignition device for an internal combustion engine of the present invention is summarized as (1) or (2).
(1)
A switch for energization connected to the primary winding of the ignition coil;
A charging circuit including a capacitor provided between a power source and a control terminal of the energizing switch, and operating according to a charging instruction signal;
A discharge circuit including the capacitor, the energization switch, a control signal source of the energization switch, and a resistor provided between the signal source and the control terminal;
With
An internal combustion engine ignition device that charges the capacitor prior to energization of the primary winding and discharges the capacitor by turning on the energization switch;
When an ON signal is input to the control terminal of the energization switch, the charge of the capacitor is discharged through the discharge circuit by negative feedback to the control terminal of the energization switch,
The internal combustion engine is characterized in that the capacitor is charged via the charging circuit when an off signal is input to the control terminal of the energizing switch during energization of the primary winding of the ignition coil. Ignition device.

(2)
One-way conduction for blocking current from the ignition coil between a terminal of the capacitor opposite to the control terminal side of the energizing switch and a terminal of the ignition coil on the primary winding side of the energizing switch With elements,
When an ON signal is input to the control terminal of the energization switch, the charge of the capacitor is discharged through the one-way conduction element, the energization switch, and the discharge circuit (1) ) Ignition device for internal combustion engine.

(3)
A switch for energization connected to the primary winding of the ignition coil;
A first charging circuit including a capacitor provided between a power source and a control terminal of the energizing switch;
A discharge circuit including the capacitor, the energization switch, a control signal source of the energization switch, and a first resistor provided between the signal source and the control terminal;
A second charging circuit including a second resistor provided between the power source, the capacitor, the control terminal and the ground;
With
An internal combustion engine ignition device that performs charging of the capacitor by the first charging circuit prior to energization of a primary winding of an ignition coil, and discharges the capacitor by turning on the energizing switch;
When an ON signal is input to the control terminal of the energization switch, the charge of the capacitor is discharged through the discharge circuit, so that the terminal voltage of the energization switch becomes the value of the capacitor and the first Decreasing at a ratio determined by the resistance value,
When an off signal is input to the control terminal of the energizing switch during energization of the primary winding of the ignition coil, the capacitor is charged via the second charging circuit, whereby the energizing switch The terminal voltage increases at a ratio determined by the value of the capacitor and the value of the second resistor,
An internal combustion engine ignition device.

  The present invention can provide “soft on” or “soft off” with excellent characteristics.

  In the present invention, the terminal voltage is negatively fed back to the control terminal when the energization switch is turned on. In the present invention, the terminal voltage is negatively fed back to the control terminal when the energization switch is forcibly turned off while the ignition coil is energized. Therefore, design and evaluation can be performed without being affected by variations in the characteristics of the component parts.

  In the present invention, since the circuit is simplified (because the number of parts is small), the manufacturing cost can be kept low, and the value of the capacitor can be reduced, which is suitable for downsizing.

In the present invention, since the off time of the energization switch is short, power loss can be reduced (the energization switch can be reduced in size).
In the present invention, a voltage-driven transistor as well as a current-driven transistor can be used as the energization switch.

1 is a basic circuit diagram showing a first embodiment of an ignition device for an internal combustion engine of the present invention. It is a circuit diagram for demonstrating the operation | movement at the time of charge of 1st Embodiment. It is a circuit diagram for demonstrating the operation | movement at the time of discharge of 1st Embodiment. It is an operation | movement waveform diagram of 1st Embodiment. It is a basic circuit diagram showing a second embodiment of an ignition device for an internal combustion engine of the present invention. It is a circuit diagram for demonstrating the operation | movement at the time of the electricity supply stop of the ignition device for internal combustion engines of 2nd Embodiment. (A) is an operation waveform diagram when the internal combustion engine ignition device of the second embodiment is soft-off, and (B) is an operation waveform diagram when the conventional ignition device is soft-off. (A) is a circuit diagram of a conventional internal combustion engine ignition device, and (B) is an operation waveform diagram. (A) is a circuit diagram of another conventional ignition device for an internal combustion engine, and (B) is an operation waveform diagram.

In an internal combustion engine ignition apparatus 1A of FIG. 1, energizing the switch circuit 11 is a transistor to Q ₁ NPN type. Instead of the transistor Q ₁ , a voltage control element such as an FET can be used. The collector of the transistor Q ₁ is connected to one end of the primary winding 141 of the ignition coil 14, and the emitter is grounded (connected to ground GND). Note that the multiple ends of the primary winding 141 of the ignition coil 14 are connected to a power supply terminal (power supply voltage V _bat ).

The charging circuit 12 includes a switch circuit including resistors R ₃ and R ₄ and a transistor Q ₂ , the capacitor C ₁ described above, and a resistor R ₂ . When a charging instruction signal S ₀ (signal source G ₀ ) is input to this switch circuit, the transistor Q ₂ is turned on, and the capacitor C ₁ is charged via the resistor R ₂ by the power supply voltage V _bat .

The discharge circuit 13 has a resistor R ₁ and a capacitor C ₁ . In FIG. 2, a diode D ₂ for preventing backflow is provided on the capacitor C ₁ side of the resistor R ₁ .
A discharge circuit 13, a diode D _1, the energizing switch circuit 11, the signal source G ₁ of the coil energization signal S _1, a discharge path of the capacitor C ₁ is formed.
The negative voltage terminal of the capacitor C ₁ is connected to the control terminal (base) of the transistor Q ₁ . In the present embodiment, the negative voltage terminal of the capacitor C ₁ is grounded (connected to the ground GND) via the resistor R ₅ .

The operation of the circuit of FIG. 1 will be described below with reference to the circuit diagrams of FIGS. 2 and 3 and the waveform diagram of FIG.
FIG. 2 is a circuit diagram when the capacitor C ₁ is charged. When charge instruction signal S ₀ changes from L level (eg, 0 V) to H level (5 V), transistor Q ₂ is turned on (t _{0 in} FIG. 4), and capacitor C ₁ passes through resistor R ₂ by power supply voltage V _bat. The battery is charged to a battery voltage V _bat (for example, 12 V) (t ₀ to t _{1 in} FIG. 4).

FIG. 3 is a circuit diagram when the capacitor C ₁ is discharged. When charging instruction signal S ₀ changes from H level to L level and coil energization signal S ₁ changes from L level (0 V) to H level (for example, 5 V), transistor Q ₁ starts to turn on. At the beginning of ON, the collector-emitter voltage (terminal voltage V _ce ) of the transistor Q ₁ is the full charge voltage of the capacitor C ₁ .

The collector terminal voltage of the transistor Q ₁ is lowered by [Delta] V, the diode D ₁ by the voltage variation, by way of capacitor C _1, the base potential of the transistor Q ₁ is also lowered by [Delta] V. This means that the output of the transistor Q ₁ is negatively fed back to the control terminal, and the transistor Q ₁ cannot be turned on suddenly.

In parallel with the above operation, the charge of the capacitor C ₁ is discharged through the path of the diode D ₁ , the transistor Q ₁ , the signal source S ₁ , the diode D ₂ , and the resistor R ₁ . The transistor Q ₁ and the capacitor C ₁ constitute a Miller integrating circuit, and the collector-emitter voltage (terminal voltage V _ce ) of the transistor Q ₁ is a time constant determined by the value of the capacitor C _{1 and} the value of R _1. It decreases linearly (t ₁ to t _{2 in} FIG. 4).

If the base potential of the transistor Q ₁ is substantially constant and the base current is ignored, the discharge current I _c of the capacitor C ₁ is given by _assuming that the forward voltage of the diode D ₂ is V _f2 .
I _c = (5V−V _be −V _f2 ) / R ₁ (1)
It is represented by
Therefore, the slope of the discharge voltage of the capacitor C ₁ due to the discharge current is
ΔV _C1 / Δt = I _c / C ₁ (2)
It becomes.

Assuming that the collector-emitter voltage (terminal voltage V _ce ) of the transistor Q1 at time t is the forward voltage V _f1 of the diode D1 and the base-emitter voltage Vbe of Q ₁ ,
_{V ce = V bat -I c ·} t / C 1 -V f1 + V be ··· (3)
It is. Therefore,
_{V ce = V bat - (5V} -V be- V f2) · t / (C 1 · R 1) -V f1 + V be ··· (4)
It becomes.

From equation (4), the rate of decrease in V _ce can be set to a desired value by changing either or both of C _{1 and} R ₁ .
That is, in the present embodiment, the transistor Q ₁ can be softly turned on, whereby the change in the current flowing through the primary coil 141 of the ignition coil 14 can be suppressed, and as a result, the secondary voltage of the ignition coil 14 can be easily obtained. Can be suppressed.

FIG. 5 is an explanatory diagram showing a basic configuration of a second embodiment of the ignition device for an internal combustion engine of the present invention.
The internal combustion engine ignition device 1C of FIG. 5 has a configuration in which a second charging circuit 15 is added to the internal combustion engine ignition device 1A shown in FIG. That is, the resistor R ₅ is provided between the control terminal of the transistor Q ₁ and the ground, and the second charging circuit 15 is constituted by the capacitor C ₁ and the resistor R ₅ .

In the internal combustion engine ignition device 1C, R ₅ is sufficiently larger than R ₁ and R ₂ . Therefore, when the energizing switch 11 is softly turned on, R ₅ can be ignored. Therefore, the operation of the internal combustion engine ignition device 1C during the soft on state is the same as that in the first embodiment (see FIGS. 1 to 4). is there.

The operation of the circuit of FIG. 5 will be described below with reference to the circuit diagram of FIG. 6 and the waveform diagram of FIG.
FIG. 6 is a circuit diagram when the capacitor C ₁ is charged.
While the ignition coil 14 is energized, an equilibrium state as shown by the following equation is established.
V _ce + V _f = V _C1 + V _be (5)
Incidentally, V _ce is the terminal voltage of the transistor Q _1, is V _f voltage drop of the diode D _1, V _C1 is charged voltage of the capacitor C _{1, V} be is the base-emitter voltage of the transistor Q _1.

In this state, when the coil energization signal S _{1 is set} to L level (turned off), the base voltage of the transistor Q ₁ decreases, so that the transistor Q ₁ tries to turn off and the terminal voltage V _ce increases. If V _ce rises by ΔV, the above-described equilibrium state is lost, and C ₁ is charged through the path indicated by (a) in FIG. 6 to maintain the equilibrium. A part of the charging current becomes the base current of the transistor Q ₁ as shown by (b) in FIG. 6 and acts to prevent the collector-emitter voltage V _ce from rising, so that the transistor Q ₁ is sharply turned off. Can not do it.

With the above operation, the collector-emitter voltage V _ce of the transistor Q ₁ rises (substantially linearly) with a value of (R ₂ + R ₅ ) and a time constant determined by the value of C ₁ .
If R ₂ >> R ₅ and R ₂ , R ₅ are selected, the collector-emitter voltage V _{ce at} time t is expressed by the following equation.
V _ce = {V _be / (R ₅ · C ₁ )} · t (5)

Therefore, by changing either or both of R _{5 and} C ₁ , the rise time of the transistor Q ₁ can be set to a desired value, and the current of the ignition coil can be safely cut off. At the same time, the power loss can be minimized by shortening the time until the transistor Q ₁ is turned off.

FIG. 7A shows the coil energization signal S ₁ , the energization current I _IGN , and the collector-emitter voltage V _ce when the energization to the ignition coil 14 of the internal combustion engine ignition device 1C is stopped. FIG. 7B shows a coil energization signal S ₁ , energization current I _IGN , and collector-emitter voltage V _ce when energizing the ignition coil 14 in the conventional internal combustion engine ignition device is stopped.
As can be seen from FIGS. 7A and 7B, in the internal combustion engine ignition device 1C, the soft-off time can be remarkably shortened as compared with the prior art.

1A, 1C Ignition device for internal combustion engine 11 Switch circuit for energization 12 Charging circuit
13 Discharge circuit (first discharge circuit)
14 Ignition coil 141 Primary winding

Claims (3)

A switch for energization connected to the primary winding of the ignition coil;
A charging circuit including a capacitor provided between a power source and a control terminal of the energizing switch, and operating according to a charging instruction signal;
A discharge circuit including the capacitor, the energization switch, a control signal source of the energization switch, and a resistor provided between the signal source and the control terminal;
With
An internal combustion engine ignition device that charges the capacitor prior to energization of the primary winding and discharges the capacitor by turning on the energization switch;
When an ON signal is input to the control terminal of the energization switch, the charge of the capacitor is discharged through the discharge circuit by negative feedback to the control terminal of the energization switch,
The internal combustion engine is characterized in that the capacitor is charged via the charging circuit when an off signal is input to the control terminal of the energizing switch during energization of the primary winding of the ignition coil. Ignition device. One-way conduction for blocking current from the ignition coil between a terminal of the capacitor opposite to the control terminal side of the energizing switch and a terminal of the ignition coil on the primary winding side of the energizing switch With elements,
The charged charge of the capacitor is discharged through the one-way conducting element, the energizing switch, and the discharging circuit when an ON signal is input to the control terminal of the energizing switch. 2. An ignition device for an internal combustion engine according to 1. A switch for energization connected to the primary winding of the ignition coil;
A first charging circuit including a capacitor provided between a power source and a control terminal of the energization switch, and operating according to a charging instruction signal;
A discharge circuit including the capacitor, the energization switch, a control signal source of the energization switch, and a first resistor provided between the signal source and the control terminal;
A second charging circuit including a second resistor provided between the capacitor and the control terminal and ground;
With
An internal combustion engine ignition device that performs charging of the capacitor by the first charging circuit prior to energization of a primary winding of an ignition coil, and discharges the capacitor by turning on the energizing switch;
When an ON signal is input to the control terminal of the energization switch, the charge of the capacitor is discharged through the discharge circuit, so that the terminal voltage of the energization switch becomes the value of the capacitor and the first Decreasing at a ratio determined by the resistance value,
When an off signal is input to the control terminal of the energizing switch during energization of the primary winding of the ignition coil, the capacitor is charged via the second charging circuit, whereby the energizing switch The terminal voltage increases at a ratio determined by the value of the capacitor and the value of the second resistor,
An internal combustion engine ignition device.

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