Abstract:
An online method for reconfiguring pressure and position sensors in a hydraulic system is disclosed. In one step, a sensor drift condition, a recalibration request, or an unisolated fault condition is detected. In another step, a system pressure sensor or another sensor, such as a load-sense pressure sensor, is verified as a trusted master reference sensor. Another step includes measuring and recording a first pressure reading at the master reference sensor and first voltage readings associated with first, second, third, and fourth pressure slave sensors at a first pump pressure set point. Another step includes, repeating the previous step at a second pump pressure set point. A new gain and offset for each of the first, second, third, and fourth pressure sensors can be calculated based on a comparison of the recoded first and second pressure readings and the recorded first and second voltage readings.
Abstract:
Methods for initiating and implementing fail operational modes in an electro-hydraulic system are disclosed. In one step, a plurality of valve assemblies is provided wherein each of the valve assemblies has a pressure sensor and a position sensor in communication with an electronic system controller. The valve assemblies are in fluid communication with a hydraulic actuator, for example a linear actuator or hydraulic motor. In one step, a fault condition with one of the sensors is detected. The method may also include the steps of determining the type and location of the sensor associated with detected fault condition. In another step, an actuator state is determined wherein the actuator is in a passive state or overrunning state. Another step is initiating and implementing one of a plurality of fail operational modes based on the determination of the sensor type and location, and the actuator state.
Abstract:
Fail-safe methods for utilizing an over-center pump/motor in a hydraulic hybrid vehicle are disclosed. A high-pressure fluid shutoff valve and an optional electrically or manually operated valve are additionally provided as means to ensure disconnection of the high pressure source in the event of a failure. Displacement stroke position and pressure differentials across the pump/motor are continually monitored. On detection of various modes of failure or irregularity in control of displacement, actions are taken including any of: the high pressure and low pressure accumulators are shut off automatically or manually, a check valve between the high and low pressure ports of the pump/motor is activated, and a small amount of pressurized fluid is released from the high pressure circuit to depressurize the captive fluid. Safe startup and shutdown procedures are also specified. The system provides for safe operation of a hydraulic hybrid vehicle that includes an engine pump and drive motor, at least one of which operates over-center. The system optionally provides a displacement control valve that is controlled by feedback from an actuator or displacement position sensor and that on loss of electric power to the displacement control valve will cause the controlled pump/motor to stroke to a zero displacement position.
Abstract:
An online method for reconfiguring pressure and position sensors in a hydraulic system is disclosed. In one step, a sensor drift condition, a recalibration request, or an unisolated fault condition is detected. In another step, a system pressure sensor or another sensor, such as a load-sense pressure sensor, is verified as a trusted master reference sensor. Another step includes measuring and recording a first pressure reading at the master reference sensor and first voltage readings associated with first, second, third, and fourth pressure slave sensors at a first pump pressure set point. Another step includes, repeating the previous step at a second pump pressure set point. A new gain and offset for each of the first, second, third, and fourth pressure sensors can be calculated based on a comparison of the recoded first and second pressure readings and the recorded first and second voltage readings.
Abstract:
Fail-safe methods for utilizing an over-center pump/motor in a hydraulic hybrid vehicle are disclosed. A high-pressure fluid shutoff valve and an optional electrically or manually operated valve are additionally provided as means to ensure disconnection of the high pressure source in the event of a failure. Displacement stroke position and pressure differentials across the pump/motor are continually monitored. On detection of various modes of failure or irregularity in control of displacement, actions are taken including any of: the high pressure and low pressure accumulators are shut off automatically or manually, a check valve between the high and low pressure ports of the pump/motor is activated, and a small amount of pressurized fluid is released from the high pressure circuit to depressurize the captive fluid. Safe startup and shutdown procedures are also specified. The system provides for safe operation of a hydraulic hybrid vehicle that includes an engine pump and drive motor, at least one of which operates over-center. The system optionally provides a displacement control valve that is controlled by feedback from an actuator or displacement position sensor and that on loss of electric power to the displacement control valve will cause the controlled pump/motor to stroke to a zero displacement position.
Abstract:
A hydraulic circuit comprising: a hydraulic input A, a hydraulic output B, a first directional control valve 12 arranged between the hydraulic input and hydraulic output, and a second directional control valve arranged between the hydraulic input and hydraulic output in series with the first directional control valve, wherein the first directional control valve has a first position in which it inhibits the passage of hydraulic fluid from the hydraulic input to the hydraulic output and a second position in which it permits the passage of hydraulic fluid, the second directional control valve has a first position in which it inhibits the passage of hydraulic fluid from the hydraulic input to the hydraulic output and a second position in which it permits the passage of hydraulic fluid, and wherein the first and second directional control valves each require an energy input to be maintained in their respective second positions.
Abstract:
A system and method for controlling a valve increases the availability of a control valve assembly used in a control process. A pair of positioners (204,206) are arranged in a high-availability configuration and individually coupled to a controller (216). A first positioner (204) includes an output coupled to a switch (218) and a second positioner (206) includes an output coupled to the switch (218). The operating state of the first positioner (204) is monitored and the output of the first or second positioner (204,206) allowed to pass through the switch (218) to the control valve (214) is dependent upon the operating status of the first positioner (204).