Method of determining an initial pressure in a motor vehicle brake system
First Claim
1. A method of determining an initial pressure which prevails between a master brake cylinder and an inlet valve of a wheel brake cylinder of a motor vehicle brake system, which determines the initial pressure taking into consideration a variation of a supply voltage during an on-off-on cycle of a PWM-operated motor of a pump for return delivery of brake fluid from a low-pressure accumulator into the master brake cylinder;
- the method comprising the following steps;
measuring several characteristic quantities of the voltage variation including at least a first and a second characteristic quantity;
determining a first individual initial pressure value from the first characteristic quantity and setting the first individual initial pressure value as a current first individual initial pressure value;
determining a second individual initial pressure value from the second characteristic quantity and setting the second individual initial pressure value as a current second individual initial pressure value;
newly measuring the several characteristic quantities;
determining that at least one of the first and second newly measured characteristic quantities is an outlier if the at least one of the newly measured first and second characteristic quantities was measured while the pump was between two speed stages;
replacing the first individual initial pressure value with a new first individual initial pressure value as a current first individual initial pressure value calculated from the newly measured first characteristic quantity if the newly measured first characteristic quantitative is not an outlier;
maintaining the first individual initial pressure value as the current first individual initial pressure value if the newly measured first characteristic quantity is an outlier because it was measured while the pump was between two speed stages;
replacing the second individual initial pressure value with a new second individual initial pressure value calculated from the newly measured second characteristic quantity if the second characteristic quantitative is not an outlier;
maintaining the second individual initial pressure value as the current second individual initial pressure value if the second characteristic quantity is an outlier because it was measured while the pump was between two speed stages;
averaging the current first and second individual initial pressure values to determine a first averaged initial pressure value;
determining a subsequent first averaged initial pressure value from subsequent current first and second individual initial pressure values;
temporally averaging the subsequent first averaged initial pressure value with at least the previously determined first averaged initial pressure value to determine a second averaged initial pressure value; and
generating output information representing the second averaged initial pressure value.
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Accused Products
Abstract
A method of determining an initial pressure prevailing between a master brake cylinder and an inlet valve of a wheel brake cylinder of a motor vehicle determines the initial pressure taking into consideration the variation of a voltage of a PWMoperated motor of a pump, which is used for the return delivery of brake fluid from a low-pressure accumulator into the master brake cylinder. Several characteristic quantities of the voltage variation are measured and converted to respective initial pressure values. The characteristic quantities or the initial pressure values determined therefrom are filtered or conditioned in the event of lack in quality or reliability of the measured characteristic quantities. The respective initial pressure values of similar size are averaged, and the averaged initial pressure values are temporally averaged in order to dampen fluctuations.
12 Citations
7 Claims
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1. A method of determining an initial pressure which prevails between a master brake cylinder and an inlet valve of a wheel brake cylinder of a motor vehicle brake system, which determines the initial pressure taking into consideration a variation of a supply voltage during an on-off-on cycle of a PWM-operated motor of a pump for return delivery of brake fluid from a low-pressure accumulator into the master brake cylinder;
- the method comprising the following steps;
measuring several characteristic quantities of the voltage variation including at least a first and a second characteristic quantity; determining a first individual initial pressure value from the first characteristic quantity and setting the first individual initial pressure value as a current first individual initial pressure value; determining a second individual initial pressure value from the second characteristic quantity and setting the second individual initial pressure value as a current second individual initial pressure value; newly measuring the several characteristic quantities; determining that at least one of the first and second newly measured characteristic quantities is an outlier if the at least one of the newly measured first and second characteristic quantities was measured while the pump was between two speed stages; replacing the first individual initial pressure value with a new first individual initial pressure value as a current first individual initial pressure value calculated from the newly measured first characteristic quantity if the newly measured first characteristic quantitative is not an outlier; maintaining the first individual initial pressure value as the current first individual initial pressure value if the newly measured first characteristic quantity is an outlier because it was measured while the pump was between two speed stages; replacing the second individual initial pressure value with a new second individual initial pressure value calculated from the newly measured second characteristic quantity if the second characteristic quantitative is not an outlier; maintaining the second individual initial pressure value as the current second individual initial pressure value if the second characteristic quantity is an outlier because it was measured while the pump was between two speed stages; averaging the current first and second individual initial pressure values to determine a first averaged initial pressure value; determining a subsequent first averaged initial pressure value from subsequent current first and second individual initial pressure values; temporally averaging the subsequent first averaged initial pressure value with at least the previously determined first averaged initial pressure value to determine a second averaged initial pressure value; and generating output information representing the second averaged initial pressure value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- the method comprising the following steps;
Specification