CONDUIT LOSS COMPENSATION FOR A DISTRIBUTED ELECTROHYDRAULIC SYSTEM
First Claim
1. A method for operating a hydraulic system having a supply conduit connected to a source, wherein the supply conduit has a plurality of first taps through which fluid is supplied to a plurality of hydraulic actuators, the method comprising:
- deriving a plurality of first pressure differentials between adjacent first taps in the supply conduit and between the fluid source and one of the first taps;
establishing a desired pressure level required at each tap of the supply conduit to operate the hydraulic actuator that is connected to that respective tap;
in response to the plurality of first pressure differentials, determining a supply pressure level to be provided by the source in order that the desired pressure level occurs at each tap of the supply conduit; and
controlling pressure at the source in response to the supply pressure level.
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Accused Products
Abstract
A plurality of hydraulic actuators are connected by valve assemblies to fluid supply and return conduits. Desired operating velocities are specified for the hydraulic actuators and used to define the amounts of fluid flow required by each actuator to move at the respective velocity. Provide the requisite flow amounts, fluid at related pressures must be provided at the different hydraulic actuators. In order for those pressures to occur, a pump has to furnish fluid at a greater pressure to allow for supply conduit losses. A process is provided for determining the pressure that the pump must provide to satisfy the greatest pressure that is necessary for the desired operation of all the hydraulic actuators.
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Citations
24 Claims
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1. A method for operating a hydraulic system having a supply conduit connected to a source, wherein the supply conduit has a plurality of first taps through which fluid is supplied to a plurality of hydraulic actuators, the method comprising:
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deriving a plurality of first pressure differentials between adjacent first taps in the supply conduit and between the fluid source and one of the first taps;
establishing a desired pressure level required at each tap of the supply conduit to operate the hydraulic actuator that is connected to that respective tap;
in response to the plurality of first pressure differentials, determining a supply pressure level to be provided by the source in order that the desired pressure level occurs at each tap of the supply conduit; and
controlling pressure at the source in response to the supply pressure level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for operating a hydraulic system to compensate for fluid losses in a conduit between a source and a plurality of hydraulic actuators, that method comprising:
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establishing a desired pressure level for each of the plurality of hydraulic actuators, thereby establishing a plurality of desired pressure levels;
determining conduction characteristics of the conduit between the fluid source and each of the plurality of hydraulic actuators;
in response to the conduction characteristics, the plurality of desired pressure levels and a pressure level in the conduit proximate the source, calculating a separate pressure level available in the conduit for each hydraulic actuator; and
controlling each hydraulic actuator in response to a respective separate pressure level. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for operating a hydraulic system having a supply conduit connected to a source and a return conduit connected to a tank, wherein the source and a plurality of hydraulic actuators are coupled to the supply conduit at different first points, the method comprising:
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(a) determining a fluid flow between a pair of the first points;
(b) calculating a first pressure differential in response to the fluid flow and a flow coefficient for a section of the supply conduit between the pair of first points;
(c) repeating steps (a) and (b) for other pairs of first points of the supply conduit, thereby calculating a plurality of first pressure differentials;
(d) for each of the plurality of hydraulic actuators, establishing a desired pressure level for operating that respective hydraulic actuator;
(e) designating the first point, that is farthest from the source, as a selected first point;
(f) calculating a compensated pressure level as a function of one of the plurality of first pressure differentials and the desired pressure level for the hydraulic actuator coupled to the selected first point;
(g) redesignating another first point, that is closer to the source than the selected first point, as the selected first point;
(h) selecting as a selected pressure level the compensated pressure level or the desired pressure level for the hydraulic actuator coupled to the selected first point, whichever is greater;
(i) recalculating the compensated pressure level as a function of one of the plurality of first pressure differentials and the selected pressure level;
(j) repeating steps (g) through (i) for all the first points to which a hydraulic actuator is coupled;
(k) then designating the compensated pressure level as a source pressure level; and
(l) using the source pressure level to control pressure provided by the source. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification