Patent ID: 11965607
Assignee: CKD CORPORATION
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A butterfly valve configured to be placed on a pipe between a vacuum chamber with a pressure sensor and a vacuum pump, and configured to control pressure in the vacuum chamber, the butterfly valve comprising:
a motor coupled to a rotary shaft and including an encoder;
a butterfly valve element configured to rotate about the rotary shaft in an opening direction and a closing direction; and
a control unit configured to adjust an opening degree of the butterfly valve element based on a pressure value of the vacuum chamber, the pressure being detected by the pressure sensor, wherein
the control unit includes an abnormal vibration detection program configured to determine whether abnormal vibration is occurring in the motor based on a variation amount of the opening degree of the butterfly valve element within a predetermined time period, the variation amount being calculated based on a pulse output from the encoder, while at least the pressure value of the vacuum chamber is stable,
the predetermined time period is shorter than a cycle of a minute variation in a normal state, which is a variation of the opening degree of the butterfly valve element to keep the pressure in the vacuum chamber stable, and
when a difference between (i) an actual variation amount corresponding to a difference between an opening degree of the butterfly valve element at a starting time point of the predetermined time period and an opening degree of the butterfly valve element at an ending time point of the predetermined time period and (ii) an accumulated variation amount obtained by accumulation of the variation amount of the butterfly valve element from the starting time point to the ending time point is equal to or larger than a predetermined threshold, the abnormal vibration detection program is configured to distinguish minute variation of the opening degree of the butterfly valve element caused when the motor is abnormally vibrating from the minute variation in the normal state, and determine that the abnormal vibration is occurring in the motor.