Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Patent
1997-05-29
1999-09-28
Gaffin, Jeffrey
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
361152, H01H 4732
Patent
active
059598255
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
(Not Applicable)
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
(Not Applicable)
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to a method of controlling the flow of current in a winding which forms part of a liquid control value more particularly a spill valve of an engine fuel system.
EP-A-0376493 discloses a method of controlling the flow of current in a winding in which the current is allowed to rise to a peak value and is then allowed to decay initially at a low rate and then at a higher rate until it reaches a value which is below a holding value, the current then being increased to the holding value. The current can be allowed to rise and fall to maintain a mean hold value. The armature which is associated with the winding starts to move under the influence of the magnetic field produced by the winding in the latter portion of the period during which the current is rising to the peak value and reaches its final position at or just before the attainment of the holding value of current. GB-A-2025183 discloses a method of controlling the flow of current in which the current is allowed to reach a high peak value and then before the associated valve reaches its final position, modifying the current flow.
In an engine fuel system it is important to know when a valve member forming part of the control valve attains its closed position and in a fuel system which employs a number of such valves it is important that each valve closes at the same time in its cycle of operation. It is desirable that the valve member should reach its closed position as soon as possible following the initiation of current flow but at the same time it is important to ensure that valve bounce is minimised. The knowledge of the point of valve closure enables the instant of valve closure to be varied to ensure correct operation of the engine.
SAE paper 861049 p153, 154 discusses the detection of valve closure in an engine fuel system and also discusses the adjustment of the start of the valve closure sequence in order to compensate for variation of battery voltage and other variables such as the resistance and inductance of the solenoid of the actuator controlling the valve.
WO87/05662 discloses a system for monitoring the opening of a valve in an engine fuel system, the valve being coupled to the armature of an electromagnetic actuator. The solenoid of the actuator is connected to a low voltage source at the time when the valve assumes its fully open position and this allows detection of a discontinuity in the current flowing in the solenoid. However, the connection of the solenoid to the low voltage source does slow the movement of the valve to the open position.
The object of the present invention is to provide a method of controlling the flow of current in a winding of the kind specified in a simple and convenient form.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 shows in diagrammatic form one part of a fuel system for an internal combustion engine;
FIG. 2 shows a diagram for the power circuit which then controls the flow of electric current in a winding forming part of the fuel system of FIG. 1;
FIG. 3 shows the waveform of the current flow in the winding and the movement of the associated armature;
FIG. 4 shows one example of a control circuit for the power circuit shown in FIG. 2, and
FIG. 5 shows modifications to the current waveform.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1 the part of the system shown therein is repeated for each engine cylinder. The part of the system comprises a high pressure fuel pump including a reciprocable plunger 10 housed within a bore 11. The plunger is movable inwardly by the action of an engine driven cam 13 and outwardly by a compression spring 12. The inner end of the bore together with the plunger form a pumping chamber 14 which has an outlet connected to a fuel pressure actuated fuel injection nozzle 15 mounted to direct fuel into an engine combustion s
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patent: 5245501 (1993-09-01), Locher et al.
patent: 5539608 (1996-07-01), Hurley et al.
patent: 5650909 (1997-07-01), Remele et al.
Gaffin Jeffrey
Huynh Kim
Lucas Industries PLC
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