Constant-energy ignition systems

Claim 2

A control circuit for an ignition system with a current source, an ignition coil having an inductive primary winding having a battery end and a load end and capable of storing ignition energy, timing means for indicating spark time and a time period just preceding spark time, and a chassis ground, the improvement including in combination, switch means for being electrically interposed between the current source connected across the winding and the winding for selectively supplying current to the winding, current sensing means for being connected to the winding for receiving current therefrom indicative of the current magnitude flowing in the winding in a first direction and supplying a signal indicative thereof, current control means connected to said switch means and respOnsive to said signal indicating a first current magnitude to supply an actuating signal to said switch means to actuate it to current conduction, and responsive to said signal indicating a second current magnitude to supply a second actuating signal to said switch means to actuate it to current nonconduction, and inertia means connected across the coil responsive to said switch means being nonconductive to provide a current path for winding supplied current generated by a collapsing electric field of the coil whereby energy stored in the field is maintained between limits indicated by the primary winding current first and second magnitudes.

Claim 3

The circuit of claim 1 further including pulser means connected to said switch means and responsive to the ignition system timing means to supply a spark indicating signal to said switch means, said sensing means being a portion of said switch means and said switch means being responsive to said spark indicating signal to electrically isolate said sensing means from any coil current.

Claim 4

The circuit of claim 2 wherein said inertia means is operative during said spark indicating signal duration to complete a discharge path for ignition current generated by the coil electric field flowing through the ignition system.

Claim 5

The circuit of claim 3 wherein said inertia means is connected between the winding battery end and the chassis ground.

Claim 6

The circuit of claim 4 wherein said inertia means is a unidirectional current conducting device poled to conduct current with respect to the winding in said first direction.

Claim 7

The circuit of claim 2 further including an inductance means in said pulser means receiving current from said switch means every time said switch means selectively supplies current and operative to maintain current flow in said pulser means during periods of nonconduction by said switch means.

Claim 8

The circuit of claim 6 wherein said switch means includes a first semiconductor device having first and second primary electrodes and a control electrode with the control electrode connected to said pulser means for receiving signals therefrom, said current sensing means comprising impedance means connected to said first primary electrodes and to chassis ground with said indicating signal being supplied from said first primary electrode, and the coil load end connected to said second primary electrode.

Claim 9

The circuit of claim 7 wherein said switch means includes a second semiconductor device having third and fourth primary electrodes and a control electrode connected to said current control means for receiving said actuating signals, said third primary electrode connected to the coil battery end, said fourth primary electrode connected to the current sources, and said inertia means connected between said third primary electrode and chassis ground and comprising a unidirectional current conducting device connected to conduct current in a direction opposite to any current flowing in said second semiconductor device from said current source.

Claim 10

The circuit of claim 6 wherein said pulser means includes a transistor device having a current gain of Beta, and said energy storing inductance means having an inductance Beta times the inductance of the inductive primary winding.

Claim 11

The circuit of claim 6 wherein said inductance means and the primary winding have substantially equal inductance to resistance ratios.

Claim 12

The circuit of claim 1 wherein said current sensing means comprises impedance means connected between the coil lead end and chassis ground for developing a voltage thereacross indicative of coil current magnitude, said switch means including a current switching semiconductor device having a control electrode receiving said actuating signals and having a plurality of primary electrodes respectively connected to the current source and to the battery end of the primary winding for selectively supplying current source current thereto.

Claim 13

The circuit of Claim 11 further including a first semiconductor device electrically interposed between the winding load end and said impedance means and having a first control electrode, ignition pulser means connected to said first control electrode for supplying ignition indicating signals thereto and connected to said current switching semiconductor device for receiving a portion of said selectively supplied current and responsive to the timing means time period indication to momentarily store energy from said selectively supplied current to supply a continuous current to said first semiconductor device control electrode for maintaining said first semiconductor device in a current conducting state at least during said time period, and being further responsive to the spark time indication to actuate said first semiconductor device to switch to a current nonconducting state.

Claim 14

The circuit of claim 12 wherein said pulser means comprises inductance means connected to said current switching semiconductor device and a second semiconductor device connected between said inductance means and said first semiconductor device control electrode and having a central electrode connected to the timing means with the timing means electrically effectively connecting chassis ground to said second semiconductor device control electrode during said time period and removing said chassis ground connection at spark time to make said second semiconductor device nonconductive.

Claim 15

The circuit of claim 12 wherein said inertia means comprises a unidirectional current conducting semiconductor device connected between the winding battery end and chassis ground and poled to conduct current with respect to the winding in the same direction as said selectively supplied current and wherein a circuit loop is formed including the primary winding, said unidirectional current conducting semiconductor device, said impedance means, said second semiconductor device and chassis ground.

Claim 16

The circuit of claim 11 wherein said current control circuit comprises first and second semiconductor devices each having one primary electrode connected to chassis ground, a central electrode and another primary electrode, said another primary electrode of said second semiconductor device connected to said control electrode of said current switching semiconductor device for supplying said actuating signals thereto, said another primary electrode of said first semiconductor device connected to said control electrode of said second semiconductor device, a unidirectional current conducting device connected between said first semiconductor control electrode and said another primary electrode of said second semiconductor device and poled to conduct current in the direction of current flow necessary to actuate said current switching semiconductor device to current conduction, an RC circuit connected between the current source and said control electrode of said first semiconductor device, and said impedance means connected to said control electrode of said first semiconductor device for supplying said indicative voltage thereto.

Claim 17

The circuit of claim 15 further including a current sensing control semiconductor device electrically interposed between the winding load end and said impedance means and having a control electrode, and pulser means connected to the last mentioned control electrode for selectively making said current sensing control semiconductor device current nonconductive for causing energy stored in the coil to discharge through the ignition system.

Claim 18

The circuit of claim 16 wherein said pulser means has an energy storing means receiving said selectively supplied current and said pulser means being operative to supply a continuous current to said current sensing central semiconductor device for keeping it continuously current conductive and responsive to the timing means indicating spark time to actuate said current sensing control semiconductor device to current nonconduction.

Claim 19

A vehicular ignition system wherein the vehicle has an engine with an ignition means, ignition timing means operative to indicate a time period just before spark time and spark time, a vehicular ground, a current source, an ignition coil connected to the ignition means, and having a primary winding with battery and load ends, the improvement including in combination, a circuit inertia unidirectional current conducting device connected between vehicular ground and the battery end and poled to conduct current in a first direction through the primary winding, a current switching semiconductor device electrically connected between the current source and the battery end to selectively supply current to the primary winding flowing in said first direction and having a first control electrode and capable of switching between current conductive and nonconductive states, a current sensing impedance means having one end connected to vehicular ground and an output end, a current sensing control semiconductor device electrically interposed between the load end and said output end having a second control electrode and capable of being in current conductive and nonconductive states, a current control circuit comprising a voltage responsive switch connected to said current sensing impedance means output end and responsive to a first voltage to switch to a first state and to a second voltage to switch to a second state, and supplying actuating signals indicative of said first and second states, said current switching semiconductor device control electrode connected to said voltage responsive switch and said current switching semiconductor device being responsive to said first state being indicated to switch to a current conductive state and to said second state being indicated to switch to a current nonconductive state, pulser means including energy storage means connected to said current switching semiconductor device for receiving said selectively supplied current, semiconductor switch means electrically coupling said energy storage means to said second control electrode and responsive to the timing means indicating a time period just before spark time to continuously couple said energy storage means to said second control electrode for making said current sensing control semiconductor device continuously conductive during such time period and responsive to the timing means indicating spark time to make said current sensing control semiconductor device current nonconductive.

Claim 20

A vehicular ignition system wherein the vehicle has an engine with an ignition means, ignition timing means operative to indicate a time period just before spark time and spark time, a vehicular ground, a current source, an ignition coil connected to the ignition means, and having a primary winding with battery and load ends, the improvement including in combination, a circuit inertia unidirectional current conducting device connected between vehicular ground and the battery end and poled to conduct current in a first direction through the primary winding, a current switching semiconductor device electrically connected between the current source and the battery end to selectively supply current to the primary winding flowing in said first direction and having a first control electrode and capable of switching between current conductive and nonconductive states, a current sensing impedance means having one end connected to vehicular ground and an output end, a current sensing control semiconductor device electrically interposed between the load end and said output end having a second control electrode and capable of being in current conductive and nonconductive states, a current control circuit comprising a voltage responsive switch connected to said current sensing impedance means output end and responsive to a first voltage to switch to a first state and to a second voltage to switch to a second state, and supplying actuating signals indicative of said first and second states, said current switching semiconductor device control electrode connected to said voltage responsive switch and said current switching semiconductor device being responsive to said first state being indicated to switch to a current conductive state and to said second state being indicated to switch to a current nonconductive state, pulser means including energy storage means connected to said current switching semiconductor device for receiving said selectively supplied current, semiconductor switch means electrically coupling said energy storage means to said second control electrode and responsive to the timing means indicating a time period just before spark time to continuously couple said energy storage means to said second control electrode for making said current sensing control semiconductor device continuously conductive during such time period and responsive to the timing means indicating spark time to make said current sensing control semiconductor device current nonconductive.