Method and system for evaluating hydrostatic transmission using charge pressure
AssigneeDeere & Company
InventorAustin J. Karst
Life of this patent
Estimating the term…
Abstract
A method of diagnosing a hydrostatic transmission system includes defining an initial charge pressure of a charge pump at a defined operating position of a primary pump. The primary pump is controlled to operate at the defined operating position. A current charge pressure from the charge pump is sensed when the primary pump is operating at the defined operating position. A pressure difference between the initial charge pressure of the charge pump and the current charge pressure of the charge pump is calculated and correlated to a system state of health of the hydrostatic transmission system.
Claims23
A method of evaluating performance of a hydrostatic transmission system having a primary pump, a hydraulic motor, and a charge pump fluidically connected via a closed hydraulic fluid circuit, the method comprising:
- defining an initial charge pressure of the charge pump at a defined operating position of the primary pump;
- controlling the primary pump with a transmission controller to operate at the defined operating position;
- sensing a current charge pressure from the charge pump when the primary pump is operating at the defined operating position with a charge pressure sensor;
- calculating a pressure difference between the initial charge pressure of the charge pump and the current charge pressure of the charge pump with the transmission controller;
- and
- correlating the pressure difference to a system state of health of the hydrostatic transmission system with the transmission controller.
A hydrostatic transmission system comprising:
- a primary pump and a hydraulic motor fluidically connected via a closed hydraulic fluid circuit, wherein the primary pump is operable to pressurize and circulate a fluid through the closed hydraulic fluid circuit to the hydraulic motor at an operating pressure, and receive the fluid via the closed hydraulic fluid circuit from the hydraulic motor;
- a tank configured to contain a supply of the fluid;
- a charge pump fluidically connected to the tank and the closed hydraulic fluid circuit, wherein the charge pump is operable to pressurize the fluid to a charge pressure to replenish the fluid lost through leakage from the closed hydraulic fluid circuit;
- a charge pressure sensor positioned to sense the charge pressure of the fluid from the charge pump;
- a transmission controller including a processor and a memory having a transmission diagnostic algorithm stored therein, wherein the processor is operable to execute the transmission diagnostic algorithm to:
- receive a test command via an input device requesting initiation of a transmission test mode;
- control the primary pump to operate at a defined operating position;
- sense a current charge pressure from the charge pump when the primary pump is operating at the defined operating position with the charge pressure sensor;
- calculate a pressure difference between an initial charge pressure of the charge pump at the defined operating position of the primary pump and the current charge pressure of the charge pump;
- and
- correlate the pressure difference to a system state of health of the hydrostatic transmission system.
Dependencies are inferred from the claim text.