US4604675A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuel injection solenoid driver circuit
Assignee: Caterpillar Inc
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Filing: 1985-07-16
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Granted: 1986-08-05
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Expires: 2005-07-16
Abstract
Abstract A fuel injection solenoid driver circuit controllably connects and disconnects a solenoid coil to and from a storage capacitor to effect operation of the coil. Precise control of the timing and duration of coil is necessary to ensure that a proper quantity of fuel is delivered to each cylinder of an internal combustion engine. A means monitors the voltage level of the storage capacitor and periodically delivers a high voltage inductive spike to the capacitor to maintain the capacitor voltage level within prescribed limitations. Further, a means aids in charging the capacitor by discharging the solenoid coil to the capacitor in response to the coil and capacitor being disconnected. Use of the energy stored in the coil to recharge the capacitor increases the power efficiency of the circuit and also results in a fast decay of the solenoid voltage. The fast decay time minimizes variations in solenoid operation timing and duration and precisely controls the quantity of fuel delivered.
Inventors
- 👤 Mark R. Pflederer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:46
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/20; F02D2041/2003; F02D2041/2006; F02D2041/2013; F02D2041/2017; F02D2041/202; F02D2041/2051
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
307 words
A fuel injection solenoid driver circuit, comprising: a solenoid coil; a storage capacitor; first switching means for controllably connecting and disconnecting a solenoid coil to and from a storage capacitor in response to receiving a control signal; second switching means for controllably connecting and disconnecting said solenoid coil to and from system ground in response to receiving a control signal; means for delivering a first control signal to said first and second switching means and enabling said first and second switching means for a first preselected duration of time to initiate current flow in said solenoid coil; third means for sensing the magnitude of the current in said solenoid coil and delivering a second control signal to said first switching means to alternately connect and disconnect said solenoid coil to and from the storage capacitor in response to the magnitude of said current respectively falling below and rising above a first and second preselected level; fourth means for sensing the magnitude of the current in said solenoid coil and delivering a third control signal to said first switching means to alternately connect and disconnect said solenoid coil to and from the storage capacitor in response to the magnitude of said current respectively falling below and rising above a third and fourth preselected level, said third and fourth preselected levels being less than both of said first and second preselected levels; fifth means for preventing delivery of said third control signal for a second preselected duration of time in response to receiving said first control signal; sixth means for preventing delivery of said first control signal for a third preselected duration of time after termination of said second preselected duration of time; and means for discharging said solenoid coil to said storage capacitor in response to disconnecting said solenoid coil from both said storage capacitor and system ground.
Claim 2
Dependent Claim
307 words
A fuel injection solenoid driver circuit, comprising: a solenoid coil; a storage capacitor; first switching means for controllably connecting and disconnecting a solenoid coil to and from a storage capacitor in response to receiving a control signal; second switching means for controllably connecting and disconnecting said solenoid coil to and from system ground in response to receiving a control signal; means for delivering a first control signal to said first and second switching means and enabling said first and second switching means for a first preselected duration of time to initiate current flow in said solenoid coil; third means for sensing the magnitude of the current in said solenoid coil and delivering a second control signal to said first switching means to alternately connect and disconnect said solenoid coil to and from the storage capacitor in response to the magnitude of said current respectively falling below and rising above a first and second preselected level; fourth means for sensing the magnitude of the current in said solenoid coil and delivering a third control signal to said first switching means to alternately connect and disconnect said solenoid coil to and from the storage capacitor in response to the magnitude of said current respectively falling below and rising above a third and fourth preselected level, said third and fourth preselected levels being less than both of said first and second preselected levels; fifth means for preventing delivery of said third control signal for a second preselected duration of time in response to receiving said first control signal; sixth means for preventing delivery of said first control signal for a third preselected duration of time after termination of said second preselected duration of time; and means for discharging said solenoid coil to said storage capacitor in response to disconnecting said solenoid coil from both said storage capacitor and system ground.
Claim 3
Dependent Claim
44 words
The fuel injection solenoid driver circuit, as set forth in claim 1, including a seventh means for providing an alternate current path for discharging said solenoid coil in response to only said first switching means controllably disconnecting said solenoid coil from said storage capacitor.
Claim 4
Dependent Claim
216 words
The fuel injection solenoid driver circuit, as set forth in claim 1, wherein said first switching means includes: a field effect transistor having a source, gate, and drain, the source of said transistor being connected to said storage capacitor and the drain of said transistor being connected to said solenoid coil; first and second bipolar junction transistors each having an emitter, collector, and base and respectively being of the npn and pnp type, the emitters of said first and second transistors being connected to the gate of said field effect transistor, the collectors of said first and second transistors being respectively connected to said storage capacitor and ground, and the bases of said first and second transistors being connected to said storage capacitor through a parallel connection of a first resistor and a zener diode; and a third bipolar junction transistor of the npn type having an emitter, base, and collector, the emitter of said third transistor being connected to system ground, the collector of said third transistor being connected through a second resistor to the bases of said first and second transistors, and said third transistor being adapted for controllably connecting and disconnecting said solenoid coil to and from said storage capacitor in response to receiving a control signal on the base of said transistor.
Claim 5
Dependent Claim
150 words
The fuel injection solenoid driver circuit, as set forth in claim 1, wherein said second switching means includes: a field effect transistor having a source, gate, and drain, the drain of said transistor being connected to said solenoid coil and the source of said transistor being connected to system ground; a bipolar junction transistor having an emitter, collector, and base and being of the npn type, the emitter of said bipolar junction transistor being connected to the gate of said field effect transistor, the collector of said bipolar junction transistor being connected to a voltage source; a resistor connected intermediate the base of said bipolar junction transistor and said voltage source; a diode connected intermediate the emitter and base of the transistor; and said transistor being adapted for controllably connecting and disconnecting said solenoid coil to and from system ground in response to receiving a control signal on said base.
Claim 6
Dependent Claim
192 words
The fuel injection solenoid driver circuit, as set forth in claim 1, wherein said storage capacitor is charged to a first preselected voltage by a step up power supply, said supply including: an inductor having a first terminal connected to a source of power, said source of power having a voltage substantially less than said first preselected voltage; a switching means for providing a low impedance path from a second terminal of said inductor to system ground, said switching means disconnecting said inductor from ground in response to receiving a control signal; a means for monitoring the magnitude of the current flowing through said inductor and said switching means and delivering a control signal to said switching means for a preselected duration of time in response to the magnitude of said current being greater than a preselected level; a power diode having a cathode connected to said inductor and an anode connected to said storage capacitor; and a means for monitoring the magnitude of the voltage of said storage capacitor and delivering a control signal to said switching means in response to said storage capacitor voltage being greater than a preselected magnitude.
Claim 7
Dependent Claim
50 words
The fuel injection solenoid driver circuit, as set forth in claim 5, including first and second alternate means for supplying regulated voltage to said fuel injection driver circuit, said first alternate means being connected to said source of power, and said second alternate means being connected to said storage capacitor.
References Cited (Backward Citations)
US4479161A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-04 | 1990-02-03 | 1990-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-04 | 1994-02-03 | 1994-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-04 | 1998-02-03 | 1998-08-05 | $7700.00 | Window Closed / Lapsed |