MEAN PRESSURE ESTIMATION FOR COMPRESSIBLE FLUID STRUT
First Claim
1. A method of estimating the mean pressure in a compressible fluid strut, the strut forming a portion of an active suspension system for a vehicle, the active suspension system including a motor having a crankshaft driving a cylinder, the cylinder being responsive to flow demands to deliver or remove fluid in the strut, the method comprising the steps of:
- providing a database of values for mean pressure variation corresponding to a specific combination of motor speed and flow demand determining the flow demand;
determining a speed of the motor;
selecting the mean pressure variation corresponding to the determined combination of motor speed and flow demand;
updating the estimation of strut mean pressure with the selected mean pressure variation.
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Accused Products
Abstract
A method and apparatus is provided for estimating the mean pressure in a compressible fluid strut. A database is employed containing values for mean pressure variation corresponding to a specific combination of motor speed and flow demand, and may also account for strut temperature. The flow demand and the speed of the motor are determined, and the mean variation corresponding to the determined combination of motor speed and flow demand is selected. The estimation of strut mean pressure is updated with the selected mean pressure variation. In this way, costly pressure sensors are eliminated as well as the complicated control algorithms which are used therewith.
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Citations
20 Claims
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1. A method of estimating the mean pressure in a compressible fluid strut, the strut forming a portion of an active suspension system for a vehicle, the active suspension system including a motor having a crankshaft driving a cylinder, the cylinder being responsive to flow demands to deliver or remove fluid in the strut, the method comprising the steps of:
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providing a database of values for mean pressure variation corresponding to a specific combination of motor speed and flow demand determining the flow demand;
determining a speed of the motor;
selecting the mean pressure variation corresponding to the determined combination of motor speed and flow demand;
updating the estimation of strut mean pressure with the selected mean pressure variation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An active suspension system for a vehicle comprising:
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a motor having a crankshaft a cylinder driven by the crankshaft, the cylinder having high pressure and low pressure valves, a compressible fluid strut fluidically connected to the cylinder for increasing or decreasing the pressure in the strut;
a vehicle dynamics controller generating a requested pressure for the strut;
a device control for regulating the pressure in the strut, the device control including a valve controller, a mean pressure estimator and a flow demand creator, the valve controller regulating the high and low pressure valves of the cylinder, the mean pressure estimator providing an estimation of the mean pressure in the strut, the flow demand creator sending flow demand signals to the valve controller based on the difference between the requested pressure and the estimation of current mean pressure; and
wherein the mean pressure estimator receives data on the speed of the motor and the flow demand signals, determines a mean pressure variation corresponding to the motor speed and flow demand, and updates the estimation of strut mean pressure with the mean pressure variation. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification