Motor operated valve apparatus and motor operated valve controller

A motor operated valve apparatus comprising:

• a motor operated valve driven by a motor;
• a drive unit configured to drive the motor;
• a control unit configured to control the drive unit;
• and
• a communication unit configured to communicate with an external controller,
• wherein the control unit is configured to:
• start control of the motor operated valve according to a command from the external controller;
• drive the motor in a valve closing direction at start of control of the motor operated valve, detect a load on the motor based on a drive pulse output by the drive unit for driving the motor, and set a driven state when the detected load reaches a predetermined reference value to be a valve switching point of a valve section;
• and
• drive the motor relative to the valve switching point of the valve section to perform control so that an opening degree of the valve section becomes a value corresponding to a control command value;
• wherein the motor operated valve includes,
• a body having an inlet port through which fluid is introduced from an upstream side, an outlet port through which fluid is delivered to a downstream side, and a valve hole through which the inlet port and the outlet port communicate with each other;
• a valve element configured to open and close the valve section by moving away from and toward a valve seat formed at an open end of the valve hole;
• the motor being a stepping motor including a rotor for driving the valve element;
• a shaft configured to rotate with the rotor and support the valve element at an end portion thereof;
• a biasing structure for elastically pressing the valve element against the valve seat during valve closure;
• and
• a motion converting mechanism configured to convert rotational movement of the rotor into translational movement of the shaft;
• wherein the control unit stops the shaft when the shaft has further moved a predetermined number of steps in the valve closing direction after the valve element touched the valve seat, and
• wherein the valve switching point is defined by the number of driving steps in a valve opening direction from an origin, the origin being a position at which the shaft is stopped.