US3721224A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ignition circuit for spark plugs of internal-combustion engine
Assignee: STMicroelectronics SRL
•
Filing: 1971-03-15
•
Granted: 1973-03-20
•
Expires: 1991-03-15
Abstract
Abstract The ignition circuit of a spark plug of an internal-combustion engine includes a storage condenser in series with a controlled rectifier which is periodically triggered under the control of an engine-driven cam switch by a blocking oscillator comprising a transistor with grounded emitter in series with the primary of a coupling transformer. One secondary winding of that transformer is inserted, together with a pair of diodes, in a charging path for the storage condenser while another secondary winding lies between the emitter of the transistor and its base which is connected through a feedback resistor to the collector thereof and via an R/C network to the gate of the controlled rectifier. During the open phase of the cam-switch cycle, the base is grounded through the last-mentioned secondary winding which is so poled as to intensify a firing pulse capacitively transmitted to the base upon the opening of the switch; at the same time the controlled retifier is turned on to discharge the previously charged storage condenser through the ignition circuit, whereupon the transistor cuts off and the condenser is recharged by the reversed transformer voltage.
Inventors
- 👤 Zotto G Del
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:51
CPC Classifications
F; F02; F02P; F02P3/00; F02P3/06; F02P3/08; F02P3/0876; F02P3/0884; F02B; F02B75/00; F02B75/02; F02B2075/022; F02B2075/027
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
218 words
A system for intermittently igniting a spark-discharge device, comprising: a source of direct current; a blocking oscillator connected across said source, said oscillator including a transistor with an emitter, a collector and a base, a coupling transformer having a primary winding inserted between said collector and a first terminal of said source, said emitter being tied to a second terminal of said source, a capacitor in series with said base, switch means For alternately applying a blocking potential and an unblocking potential from said source to said capacitor, and a resistive connection between said base and the junction of said primary winding with said collector, said coupling transformer having a first secondary winding connected between said base and said emitter for intensifying said unblocking and blocking potentials upon incipient conduction and cutoff of said transistor; an ignition circuit for said spark-discharge device including a condenser and an electronic switch in series; a charging circuit including another secondary winding of said coupling transformer and diode means in series with said condensor; and a control circuit for said electronic switch connected to said base for closing said electronic switch in the presence of said unblocking potential, thereby discharging said condenser through said ignition circuit, said other secondary winding being poled to recharge said condenser upon incipient cutoff of said transistor.
Claim 2
Independent Claim
218 words
A system for intermittently igniting a spark-discharge device, comprising: a source of direct current; a blocking oscillator connected across said source, said oscillator including a transistor with an emitter, a collector and a base, a coupling transformer having a primary winding inserted between said collector and a first terminal of said source, said emitter being tied to a second terminal of said source, a capacitor in series with said base, switch means For alternately applying a blocking potential and an unblocking potential from said source to said capacitor, and a resistive connection between said base and the junction of said primary winding with said collector, said coupling transformer having a first secondary winding connected between said base and said emitter for intensifying said unblocking and blocking potentials upon incipient conduction and cutoff of said transistor; an ignition circuit for said spark-discharge device including a condenser and an electronic switch in series; a charging circuit including another secondary winding of said coupling transformer and diode means in series with said condensor; and a control circuit for said electronic switch connected to said base for closing said electronic switch in the presence of said unblocking potential, thereby discharging said condenser through said ignition circuit, said other secondary winding being poled to recharge said condenser upon incipient cutoff of said transistor.
Claim 3
Dependent Claim
24 words
A system as defined in claim 1 wherein said electronic switch is a controlled rectifier with a gate electrode connected to said control circuit.
Claim 4
Dependent Claim
58 words
A system as defined in claim 1, further comprising a resistive voltage divider inserted between said capacitor and said base, said resistive connection being joined to said voltage divider at a first tap thereof relatively remote from said base, said control circuit being connected to said voltage divider at a second tap thereof relatively close to said base.
Claim 5
Dependent Claim
19 words
A system as defined in claim 3 wherein said control circuit includes a capacitance and a resistance in parallel.
Claim 6
Dependent Claim
21 words
A system as defined in claim 3 wherein said first secondary winding is connected between said emitter and said first tap.
Claim 7
Dependent Claim
46 words
A system as defined in claim 5, further comprising a first diode shunting said voltage divider between said capacitor and said first tap, and a second diode shunting said voltage divider between said first and second taps, said diodes being poled to pass said unblocking potential.
Claim 8
Dependent Claim
23 words
A system as defined in claim 1 wherein said transistor is provided with an integrating network connected between said base and said emitter.
Claim 9
Dependent Claim
48 words
A system as defined in claim 1, further comprising a leakage resistor connected between said capacitor and said first terminal, said switch means being operable to connect said second terminal to the junction of said leakage resistor with said capacitor for applying said blocking potential to the latter.
Claim 10
Dependent Claim
24 words
A system as defined in claim 1 wherein said ignition circuit includes a step-up transformer in series with said condenser and said electronic switch.
Claim 11
Dependent Claim
28 words
A system as defined in claim 1 wherein said device is a spark plug of an internal-combustion engine, said switch means comprising a cam driven by said engine.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |