TWI479077B - Firing circuit - Google Patents

Description

Ignition circuit

The present invention relates to an ignition circuit.

Ignition circuits are designed on the car to ignite the engine. The design of the general ignition circuit is complicated and costly. For example, the programmable shunt regulator of the model LM431, the voltage regulator, etc. The ignition circuit of the component.

In view of the above, it is necessary to provide an ignition circuit that is simple in structure and low in cost.

An ignition circuit comprising a system power supply, an ignition coil connected to the system power supply at a first end, a delay unit, a first switching unit connected between the system power supply and the ground, and a first connection to the ignition coil a second switching unit between the two ends, the system power supply is connected to the control end of the first switching unit through the delay unit, and the system power supply is connected to the control end of the second switching unit through the first switching unit, After the power of the system is powered on, the second switch unit is turned on to power on the ignition coil, and the delay unit controls the first switch unit to be turned on after the system power is turned on for a delay time to control the second switch unit to be turned off. , the ignition coil is de-energized.

The ignition circuit controls the system power supply to control the first switching unit to be turned on after the power-on delay time, and controls the second switching unit to be turned off after the first switching unit is turned on, thereby controlling the ignition coil to lose power. , complete the ignition operation. The ignition circuit is simple in design, easy to implement, and low in cost.

Referring to FIG. 1 , a first preferred embodiment 100 of an ignition circuit of the present invention includes a system power supply VCC, a delay unit 10 composed of a resistor R1 and a capacitor C1, a first switch unit 20, and a second switch unit 30. An ignition coil L, a diode D and three resistors R2-R4.

The first switch unit 20 includes an NPN-type transistor Q1, and the second switch unit 30 includes a controllable SCR.

The system power supply VCC is connected to the positive pole of the capacitor C1 through the resistor R1, and the cathode of the capacitor C1 is grounded. The base of the transistor Q1 is connected to the node of the resistor R1 and the capacitor C1 through the resistor R2. The emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the system power supply VCC through the resistor R3. The system power supply VCC is also connected to the anode of the controllable SCR through the ignition coil L. The cathode of the controllable SCR is grounded, and the control end of the controllable SCR is connected to the collector of the transistor Q1 through the resistor R4. . The cathode of the diode D is connected to the system power supply VCC, and the anode of the diode D is connected to the anode of the controllable 矽SCR.

After the system power supply VCC is powered on, the system power supply VCC is charged to the capacitor C1 via the resistor R1. The resistance of the resistor R1 is large, and the voltage across the capacitor C1 rises slowly, and the voltage across the capacitor C1 is Before the rise to 0.7V, the transistor Q1 is always in the off state, so at this time, the control terminal of the controllable 矽SCR is at a high level, so that the controllable 矽SCR is in an on state, and the ignition coil L is energized for a short time. After a delay time (determined by the parameter values of the resistor R1 and the capacitor C1), the voltage across the capacitor C1 reaches 0.7V, and the transistor Q1 is turned from the off state to the on state, thereby making the controllable SCR The control terminal changes from a high level to a low level, so that the controllable 矽SCR is in an off state, and the ignition coil L is de-energized, thereby achieving an ignition operation. The role of the diode D is to prevent reverse current from penetrating the ignition coil L. If the ignition requirement is not high or to further reduce the cost, the diode D can be deleted. In other embodiments, the transistor Q1 and the controllable 矽SCR may be replaced by other electronic switches having a switching function, and are not limited to the embodiment.

Referring to FIG. 2, the second preferred embodiment 200 of the ignition circuit of the present invention is different from the first preferred embodiment 100 only in that the controllable SCR in the second switching unit 30 is replaced by an NPN type. Crystal Q2, the base (control terminal) of the transistor Q2 is connected to the collector of the transistor Q1 through the resistor R4, the emitter of the transistor Q2 is grounded, and the collector of the transistor Q2 is connected through the ignition coil L The working principle of the second preferred embodiment 200 is substantially the same as that of the first preferred embodiment 100, and is not described here.

Referring to FIG. 3, the third preferred embodiment 300 of the ignition circuit of the present invention is different from the first preferred embodiment 100 only in that the NPN transistor Q1 in the first switching unit 20 is replaced by a PNP type. The transistor Q3 is removed and the resistor R3 is removed. The base of the transistor Q3 is connected to the node of the resistor R1 and the capacitor C1 through the resistor R2. The emitter of the transistor Q3 is directly connected to the system power supply VCC. The collector is connected to the control terminal of the controllable SCR through the resistor R4. The working principle of the third preferred embodiment 300 is basically the same as that of the first preferred embodiment 100, and details are not described herein. .

The ignition circuit of the invention realizes the function of the ignition circuit by using only a few components such as a resistor, a capacitor, a transistor or a controllable crucible, and the circuit structure is simple and easy to implement, and the cost is greatly saved.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

100, 200, 300‧‧‧ ignition circuit

20‧‧‧First switch unit

VCC‧‧‧ system power supply

C1‧‧‧ capacitor

D‧‧‧ diode

SCR‧‧‧Controlled

10‧‧‧Delay unit

30‧‧‧Second switch unit

R1-R4‧‧‧ resistance

Q1, Q2, Q3‧‧‧ transistor

L‧‧‧Ignition coil

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a circuit diagram of a first preferred embodiment of the ignition circuit of the present invention.

Figure 2 is a circuit diagram of a second preferred embodiment of the ignition circuit of the present invention.

Figure 3 is a circuit diagram of a third preferred embodiment of the ignition circuit of the present invention.

100‧‧‧Ignition circuit

20‧‧‧First switch unit

VCC‧‧‧ system power supply

C1‧‧‧ capacitor

D‧‧‧ diode

SCR‧‧‧Controlled

10‧‧‧Delay unit

30‧‧‧Second switch unit

R1-R4‧‧‧ resistance

Q1‧‧‧Optoelectronics

L‧‧‧Ignition coil

Claims (8)

An ignition circuit comprising a system power supply, an ignition coil connected to the system power supply at a first end, a delay unit, a first switching unit connected between the system power supply and the ground, and a first connection to the ignition coil a second switching unit between the two ends, the system power supply is connected to the control end of the first switching unit through the delay unit, and the system power supply is connected to the control end of the second switching unit through the first switching unit, After the power of the system is powered on, the second switch unit is turned on to power on the ignition coil, and the delay unit controls the first switch unit to be turned on after the system power is turned on for a delay time to control the second switch unit to be turned off. , the ignition coil is de-energized. The ignition circuit of claim 1, further comprising a diode, the cathode of the diode being connected to the first end of the ignition coil, the anode of the diode and the second of the ignition coil Connected to the end. The ignition circuit of claim 1, wherein the delay unit comprises a first resistor and a capacitor, and the system power supply is connected to the anode of the capacitor and the control end of the first switch unit through the first resistor. The negative pole of this capacitor is grounded. The ignition circuit of claim 3, wherein the first switching unit comprises an NPN-type first transistor, and the base of the first transistor serves as a control terminal of the first switching unit through a second resistor Connected to the node between the first resistor and the positive pole of the capacitor, the collector of the first transistor is connected to the system power supply through a third resistor, and is connected to the control end of the second switch unit through a fourth resistor, The emitter of the first transistor is grounded. The ignition circuit of claim 4, wherein the second switch unit includes a controllable switch, and the control end of the controllable switch is connected to the control terminal of the second switch unit through the fourth resistor a collector of a transistor, the cathode of the controllable crucible is grounded, and the anode of the controllable crucible is coupled to the second end of the ignition coil. The ignition circuit of claim 4, wherein the second switching unit comprises an NPN-type second transistor, and the base of the second transistor serves as a control terminal of the second switching unit to transmit the fourth resistor Connected to the collector of the first transistor, the emitter of the second transistor is grounded, and the collector of the second transistor is coupled to the second end of the ignition coil. The ignition circuit of claim 3, wherein the first switching unit comprises a PNP type transistor, and a base of the transistor is connected to the control terminal of the first switching unit through a second resistor to the first a node between the resistor and the positive terminal of the capacitor, the emitter of the transistor is connected to the power supply of the system, and the collector of the transistor is connected to the control end of the second switch unit through a third resistor. The ignition circuit of claim 7, wherein the second switch unit comprises a controllable switch, and the control end of the controllable switch is connected to the control terminal of the second switch unit through the third resistor The collector of the crystal, the cathode of the controllable crucible is grounded, and the anode of the controllable crucible is connected to the second end of the ignition coil.