Igniter and vehicle

Patent metadata

Field	Value
Publication number	US-9784233-B2
Application number	US-201514923512-A
Country	US
Kind code	B2
Filing date	Oct 27, 2015
Priority date	Oct 31, 2014
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

An igniter includes: a switch connected to an ignition coil; and a controller to control the switch according to an ignition signal. The controller includes an ignition signal input; a determination stage comparing a voltage of the input with a reference voltage to generate a determination signal; a drive stage controlling the switch's ON/OFF according to the determination signal; a comparison circuit receiving a first supply voltage, comparing a current on the switch with a reference current, and generating a feedback-signal having a level based on the comparison; an output transistor having one end grounded and the other end connected to an output terminal of an ignition check signal and having a threshold voltage higher than the first supply voltage; and a level-shifter receiving a second supply voltage higher than the threshold voltage, level-shifting the feedback-signal, and outputting the level-shifted feedback-signal to a control terminal of the output transistor.

First claim

What is claimed is:

1. An igniter comprising:
a switch device connected to a primary coil of an ignition coil; and
a switch controller configured to control the switch device in response to an ignition signal from an ECU (Engine Control Unit),
wherein the switch controller includes:
an input line to which the ignition signal is input;
a determination stage in which a voltage of the input line is compared with a predetermined reference voltage to generate a determination signal based on a result of the comparison;
a drive stage in which ON/OFF of the switch device is controlled in response to the determination signal;
a current comparison circuit, the current comparison circuit receiving a first power supply voltage, comparing a coil current flowing through the switch device with at least one reference current, and generating a feedback signal having a logical level based on a result of the comparison;
an output transistor having one end grounded and the other end connected to a terminal for outputting an ignition check signal, the output transistor having a threshold voltage higher than the first power supply voltage; and
a level shifter to receive a second power supply voltage higher than the threshold voltage of the output transistor, to level-shift the feedback signal, and to output the level-shifted feedback signal to a control terminal of the output transistor.

2. The igniter of claim 1 , wherein the level shifter includes a first resistor and a first transistor that are connected in series between a ground line and a second power supply line to which the second power supply voltage is supplied.

3. The igniter of claim 1 , wherein the current comparison circuit compares the coil current with an upper reference current and a lower reference current, and the feedback signal has (i) a first level when the coil current is smaller than the lower reference current or larger than the upper reference current and (ii) a second level when the coil current is larger than the lower reference current and smaller than the upper reference current.

4. The igniter of claim 1 , wherein the current comparison circuit includes at least one voltage comparator which compares a detection voltage proportional to the coil current with at least one reference voltage corresponding to the at least one reference current.

5. The igniter of claim 4 , wherein the current comparison circuit includes a filter circuit to eliminate noise of the detection voltage.

6. The igniter of claim 4 , wherein the at least one reference voltage has a hysteresis.

7. The igniter of claim 6 , wherein the at least one voltage comparator includes:
a second transistor;
a second resistor connected between a ground line and an emitter of the second transistor;
a third transistor having a base connected to a base of the second transistor and an emitter to which the detection voltage is input;
a first current source connected to a collector of the second transistor;
a second current source connected to a collector of the third transistor;
a fourth transistor having a base connected to the collector of the second transistor and an emitter connected to the bases of the second transistor and the third transistor;
a third resistor and a fourth resistor that are connected in series between the emitter of the second transistor and the bases of the second transistor and the third transistor; and
a fifth transistor interposed between the ground line and a node between the third resistor and the fourth resistor and having a base to which an output signal of the voltage comparator is input.

8. The igniter of claim 4 , further comprising a current sense resistor interposed between the switch device and the ground,
wherein a voltage across the current sense resistor is the detection voltage.

9. The igniter of claim 3 , wherein the current comparison circuit includes:
a first comparator to compare a detection voltage corresponding to the coil current with an upper reference voltage corresponding to the upper reference current and output a first comparison signal based on a result of the comparison;
a second comparator to compare the detection voltage with a lower reference voltage corresponding to the lower reference current and output a second comparison signal based on a result of the comparison; and
a logic circuit to perform a logical operation for the first comparison signal and the second comparison signal to generate the feedback signal.

10. The igniter of claim 1 , wherein the switch controller is integrated on a single semiconductor substrate.

11. A vehicle comprising:
a gasoline engine;
an ignition plug;
an ignition coil having a primary coil and a secondary coil connected to the ignition plug;
an ECU to generate an ignition signal indicating ignition of the ignition plug; and
an igniter of claim 1 , the igniter driving the ignition coil in response to the ignition signal.

Assignees

• Rohm Co Ltd

Inventors

• Obe Katsuya

Classifications

• F02P2017/121

  by measuring spark voltage · CPC title

• F02D35/028

  by determining the combustion timing or phasing · CPC title

• F02P17/12 Primary

  Testing characteristics of the spark, ignition voltage or current (testing of sparking plugs H01T13/60) · CPC title

• F02P3/0442

  using digital techniques (F02P3/0456, F02P3/053, F02P3/0554, F02P3/0558 take precedence) · CPC title