System and method to detect accumulator loss of precharge
AssigneeCaterpillar Inc.
InventorHeng Zhou
Life of this patent
Estimating the term…
Abstract
Methods and apparatus for detecting a leak in a gas precharged hydraulic accumulator having an initial gas charge entail activating a hydraulic pump to charge the gas precharged hydraulic accumulator and the hydraulic circuit associated with the gas precharged hydraulic accumulator when the hydraulic circuit and the hydraulic accumulator have a temperature that is substantially equivalent to an ambient temperature, e.g., on a cold start. The hydraulic pressure in the hydraulic circuit is monitored, and when a step in the hydraulic pressure is detected, various quantities are measured and used to determine a volumetric efficiency of the pump for use in later calculations of remaining gas amount.
Claims19
A method for detecting a leak in a gas precharged hydraulic accumulator having an initial gas charge, in a hydraulic circuit associated with a hydraulic pump, the method comprising:
- activating the hydraulic pump to charge the hydraulic circuit and the hydraulic accumulator when the hydraulic circuit and the hydraulic accumulator have a temperature that is substantially equivalent to an ambient temperature;
- monitoring a hydraulic pressure in the hydraulic circuit;
- detecting a step in the hydraulic pressure at a first time based on the monitoring;
- generating a measure of an amount of precharge gas remaining in the hydraulic accumulator based on the hydraulic pressure at the step, the ambient temperature, and a maximum gas volume of the hydraulic accumulator;
- and
- comparing the amount of precharge gas remaining in the hydraulic accumulator with the initial gas charge and determining that a gas leak exists in the hydraulic accumulator if the amount of precharge gas remaining in the hydraulic accumulator is less than the initial gas charge by greater than a predetermined extent.
A system for detecting a gas leak in a gas precharged hydraulic accumulator having an internal volume divided by a piston, with a precharge of gas on a first side of the piston and hydraulic fluid and a hydraulic fluid inlet on a second side of the piston, the hydraulic accumulator being associated with a hydraulic circuit, a hydraulic pump being in fluid communication with the hydraulic circuit, the system comprising:
- a temperature sensor located to sense a temperature of the precharge of gas;
- a fluid pressure sensor located to sense a pressure of hydraulic fluid at the hydraulic fluid inlet;
- and
- a controller configured to detect a gas leak from the hydraulic accumulator by calculating a volumetric efficiency of the hydraulic pump during a first charge cycle of the hydraulic circuit by the hydraulic pump, and deriving a measure of an amount of gas remaining in the hydraulic accumulator after a subsequent charge cycle based on measurements from the temperature sensor and the fluid pressure sensor and based on the calculated volumetric efficiency of the hydraulic pump.
A truck having at least one gas precharged hydraulic accumulator for facilitating a function with respect to the truck, the hydraulic accumulator having an internal volume divided by a piston, with a precharge of gas on a first side of the piston and hydraulic fluid and a hydraulic fluid inlet on a second side of the piston, the truck further comprising:
- a hydraulic circuit associated with the hydraulic accumulator;
- a hydraulic pump in fluid communication with the hydraulic circuit for charging the hydraulic circuit;
- a temperature sensor located to sense a temperature of the precharge of gas in the hydraulic accumulator;
- a fluid pressure sensor located to sense a pressure of hydraulic fluid at the hydraulic fluid inlet;
- and
- a controller configured to detect a gas leak from the hydraulic accumulator by calculating a volumetric efficiency of the hydraulic pump during a first charge cycle of the hydraulic circuit by the hydraulic pump, and deriving a measure of an amount of gas remaining in the hydraulic accumulator after a subsequent charge cycle based on measurements from the temperature sensor and the fluid pressure sensor and based on the calculated volumetric efficiency of the hydraulic pump.
Dependencies are inferred from the claim text.