Electricity: electrical systems and devices – Control circuits for electromagnetic devices – For relays or solenoids
Patent
1998-01-09
2000-05-30
Fleming, Fritz
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
For relays or solenoids
361170, 361160, H01H 4712
Patent
active
060697849
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for driving a solenoid valve.
BACKGROUND INFORMATION
A conventional method and apparatus for driving a solenoid valve, described in German Published Unexamined Application No. 38 05 031 (corresponding to U.S. Pat. No. 5,313,153), includes a coil and a movable armature. To set the armature into motion, current and/or voltage is applied to the coil. For this, the coil is connected with clocked timing via a switching device to a voltage source.
When using such conventional solenoid valves in motor vehicles, different voltages are applied to the solenoid valves. This causes different behavior of the solenoid valve in different operating states. Defined operation of the solenoid valve thus requires additional outlay.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for driving a solenoid valve. A coil and a movable armature are provided. Current and/or voltage are applied to the coil to move the armature in a clocked manner using a predetermined duty factor. According to the present invention, by varying the driving action, the solenoid valve can be operated optionally as a control valve or as a relief valve.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic arrangement for driving a solenoid valve according to the present invention.
FIG. 2 shows drive signals plotted over time.
FIG. 3 shows an exemplary structure of the solenoid valve according to the present invention.
FIG. 4 shows a duty factor and pressure plotted over time.
FIG. 5a shows a graphical plot of a magnetic force plotted for various currents over lift values (or time).
FIG. 5b shows a graphical plot of a sum of a spring force and a hydraulic force over the lift values (or time).
FIG. 5c shows a graphic plot of other pressures over the lift values (or time).
FIG. 6 shows a flowchart of an operation of the method and apparatus according to the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
The procedure according to the present invention is described hereafter based on a solenoid valve used to, e.g., control brake fluid in an ABSR hydraulic unit. In ABS (anti-lock braking) systems and/or ASR (traction control) systems, the hydraulic fluid is controlled using solenoid valves. So-called integrated selector/relief valves are used which, depending on the control strategy, abruptly relieve the pressure built up by a pump to a so-called main brake cylinder, or limit the pressure to an adjustable value. The abrupt pressure relief is associated with disruptive noise generation. One objective of the present invention is to reduce this noise during operation.
The method and apparatus according to the present invention is not limited to this application, and can be used in all electromagnetic loads. The method and apparatus can also be used in solenoid valves with which the fuel metering in internal combustion engines is controlled and/or the pressure in injection systems for internal combustion engines is controlled and/or limited.
FIG. 1 shows exemplary elements of the apparatus according to the present invention. A load 100 has its first terminal connected to supply voltage Ubat, and its second terminal in contact with a switching device 110. Switching device 110 connects the second terminal of the load to ground via resistive means (current-measuring device) 120. Load 100, switching device 110 and current-measuring device 120 are connected in series. The components can also be connected in a different order. Load 100 is preferably a coil of a solenoid valve. Switching device 110 is preferably a transistor, particularly a field-effect transistor.
Moreover, a control unit 130 is provided that has different signals fed to it from sensors 140. Moreover, the potentials at the inputs of load 100 and current-measuring device 120 are fed to control unit 130. Control unit 130 applies drive signals to switching device 110.
Based on the signals measured by the sensors 140, e.g., sensors to measure the rotational speeds of indiv
REFERENCES:
patent: 5313153 (1994-05-01), Locher et al.
patent: 5703748 (1997-12-01), Fulks et al.
Doden Berend-Wilhelm
Friedow Michael
Hohl Gunther
Ludewig Erich
Mettner Michael
Fleming Fritz
Robert & Bosch GmbH
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