Patent classifications
F15B2211/8646
Preventing control-induced oscillations of the position of a valve member in a valve with pneumatic actuator
A method for preventing control-induced oscillations in a valve with a pneumatic actuator and position control with an integrating component, including the following steps: Checking whether oscillations of the valve member occur by counting the zero crossings or extreme values of the control difference. If oscillations were detected, it is checked whether they result from oscillations of the set point. If not, the dead zone is increased and/or the gain parameter is decreased. If no oscillations were detected, it is checked whether wear in the drive has exceeded a predetermined measure. If so, the dead zone is decreased and/or the gain parameter is increased. In this way, oscillations caused by the I-component of the control can be detected and stopped. Further changes to the parameters are only made when friction is expected to have decreased due to wear.
Work machine and method for calibrating an electrohydraulic pump in an open center hydraulic system
A work machine and method for a work machine with an open center hydraulic system for controlling actuation of an implement includes an implement control valve, an electro-hydraulically controlled pump, a hydraulic circuit coupled to the implement actuator, and a pressure transducer positioned for measuring a pressure in the hydraulic circuit between the pump and the implement control valve. A calibration system for calibrating the pump includes a controller having a non-transitory computer readable medium having a program instruction for causing a processor to calibrate a first pump threshold for the pump in a pump-flow curve wherein the first pump threshold including a minimum pump control signal to actuate the pump; determine a hysteresis band in the pump-flow curve; and calibrate a second pump threshold for the pump in the pump-flow curve wherein the second pump threshold including a maximum pump control signal to actuate the pump below a relief setpoint.