Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Patent
1994-06-20
1996-06-25
Fleming, Fritz M.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
H01H 4732
Patent
active
055306144
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an auxiliary power steering for motor vehicles with an electromagnetically activated proportional valve.
2. Description of the Prior Art
A generic auxiliary power steering is known according to EP 01 42 988 B1. Here, a delta voltage is generated by a triangular generator and is compared to a required voltage of a servo amplifier. A delta voltage with a constant frequency, predetermined by the triangular generator, develops at the output of the comparator. The pulse length is generated in proportion to the required voltage value. This results in a constant energizing frequency for the valve. Such valves frequently produce a whistling sound that is noticed in the vehicle and that is felt to be very annoying.
SUMMARY OF THE INVENTION
The purpose of the invention is to prevent the disturbing whistling sounds in an auxiliary power steering of the kind described initially. This problem is solved by the features of the invention.
The starting sides of the voltage pulses begin at different time intervals; therefore, no constant frequency can be formed and no whistling sound can be generated. Instead, one gets a rather negligible noise that does not have a disturbing effect in the remaining noise level within the vehicle.
The noise can become a so-called "white noise" if the interval changes irregularly according to another proposal of the invention.
The pulse sequence according to the invention can be generated with a processor unit in a simple manner without influencing the current regulation to any major extent.
The invention will be described in greater detail with the help of the drawing that is confined to those points that are essential in understanding the invention.
BRIEF DESCRIPTION OF THE DRAWING
The single FIGURE shows a control unit in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The FIGURE shows the control unit for a magnetic coil 2 of an electromagnetically activated proportional valve (not shown), which control unit includes a processor unit 1 with three ports of which the first port 14 is connected via a driving stage 6 to a power transistor 5. The power transistor regulates the power supply current of a magnetic coil 2 as a function of a pulsed voltage applied at the first port 14. Magnetic coil 2 and a current precision resistor 3 are bridged with a recovery diode 4 in the usual manner.
The current of magnetic coil 2 is tapped as voltage on the current precision resistance 3 and is then supplied to a non-inverting second input 18 of a comparator 7 via a second resistance 8 and a second filter capacitor 9. A pulsed required current value is supplied from the third port 16 of processor unit 1 likewise via a first resistance 10 and a first filter capacitor 11 to an inverting, first input 19 of comparator 7. An output 17 of comparator 7 is connected with a second port 15.
Processor unit 1 calculates the required value 12 according to the rules of logic and contains a logic circuit 13 in which the second port 15 is interrogated in a regular sequence at irregular intervals to determine the actual value and where an opposite signal is always put out to the first port 14. If the required value is greater than the actual value, then the power transistor is turned off and if the required value is smaller than the actual value, the power transistor 5 is turned on.
If power transistor 5 is energized, a current flows through magnetic coil 2 and precision resistor 3 that rises according to an e-function. If the voltage on the precision resistor 3 reaches the magnitude of the required voltage value at the comparator input, the power transistor 5 is again turned off via driving stage 6 and processor unit 1 and comparator 7. That results ill a kick-back voltage on magnetic coil 2 and that voltage, via the recovery diode 4, generates a recovery current that drops again according to the turn-on time of power transistor 5 and the inside resistance of magnetic coil 2. If the voltage on the curr
REFERENCES:
patent: 4546403 (1985-10-01), Nielsen
patent: 4667117 (1987-05-01), Nebgen et al.
patent: 4737882 (1988-04-01), D'onofrio
Cerny Walter
Lang Armin
Fleming Fritz M.
ZF Friedrichshafen AG
LandOfFree
Proportional valve control unit for auxiliary power steering does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Proportional valve control unit for auxiliary power steering, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Proportional valve control unit for auxiliary power steering will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2194364