Device to provide a regulated power supply for in-cylinder ionization detection by using a charge pump
First Claim
1. An ionization detection circuit, comprising:
- a charge pump;
an ignition coil comprising a primary winding with a first end and a second end and a secondary winding with a first end and a second end;
an ignition plug operably connected between said second end of said secondary winding and ground;
a current mirror having a first terminal operably connected to said first end of said secondary winding, a second terminal operably connected to said charge pump and a third terminal; and
a first switch having a command input and a first and a second end, wherein said first switch is operably connected between said second end of said primary winding and ground.
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Accused Products
Abstract
A charge pump is used to supply current to the ionization detection circuit. To detect in-cylinder ions generated during the combustion process, a DC bias voltage needs to be applied. There are two ways to generate the DC bias: conventional DC power supply (large electronics) and capacitor charges by primary or secondary flyback voltage (high voltage capacitor). Typically, flyback voltage is used to charge the capacitor which supplies current to the ionization detection circuit. This necessitates the use of high voltage capacitors. Generally, ceramic capacitors are used. However, as temperature fluctuates, the board that the capacitor is mounted on can flex, causing the ceramic capacitor to crack. This invention proposes to use a high voltage charge pump to provide enough DC bias voltage for measuring ionization current. In a preferred embodiment, a model number M1C4827 EL driver is used in the charge pump circuit. The charge pump circuit will convert the 12 Volt DC at the B+ terminal to a 90 to 100 volt pulse train with a pulse repetition frequency of 500 kHz at the charge pump output.
29 Citations
20 Claims
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1. An ionization detection circuit, comprising:
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a charge pump;
an ignition coil comprising a primary winding with a first end and a second end and a secondary winding with a first end and a second end;
an ignition plug operably connected between said second end of said secondary winding and ground;
a current mirror having a first terminal operably connected to said first end of said secondary winding, a second terminal operably connected to said charge pump and a third terminal; and
a first switch having a command input and a first and a second end, wherein said first switch is operably connected between said second end of said primary winding and ground. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An ionization detection circuit, comprising:
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a charge pump;
an ignition coil comprising a primary winding having a first end and a second end and a secondary winding having a first end and a second end;
a current mirror having a first terminal operably connected to said first end of said secondary winding, a second terminal operably connected to said charge pump and a third terminal;
an ignition plug operably connected between said second end of said secondary winding and ground;
a first switch having a command input, a first end and a second end, wherein said first switch is operably connected between said second end of said primary winding and ground;
a first resistor operably connected between said second end of said first switch and ground potential;
a second resistor operably connected between said third terminal of said current mirror and ground potential;
a third resistor operably connected between said first terminal of said current mirror and said first end of said secondary winding, whereby ionization current is limited; and
a diode operably connected between said first end of said secondary winding and ground potential, wherein said current mirror comprises a pair of matched transistors and wherein each of said transistors comprises a base terminal, a collector terminal and an emitter terminal, whereby said base terminals are operably connected to each other and said base terminals are operably connected to each other. - View Dependent Claims (18, 19, 20)
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Specification