Abnormal discharge detection device and abnormal discharge detection method

Abstract

A pump included in an oil supply unit includes a piezoelectric body that is repeatedly deformed when a pulsed drive voltage is applied from a drive unit. The pump discharges lubricant as the volume of a storage unit that stores fluid to be supplied decreases with deformation of the piezoelectric body. An abnormal discharge detection device that detects an abnormal fluid discharge operation of the pump includes: a measurement unit that measures a terminal voltage of the piezoelectric body; and a control unit functioning as a determination unit that determines if the discharge operation is being performed normally or not based on whether or not the measured terminal voltage has changed with time during application of a pulse of the drive voltage.

What is claimed is: 
     
       1. An abnormal discharge detection device that detects an abnormal fluid discharge operation in a fluid supply device, the fluid supply device including a drive unit that outputs a pulsed drive voltage, a piezoelectric element that is repeatedly deformed when the pulsed drive voltage is applied, and a storage unit that stores therein fluid to be supplied, and the fluid supply device discharging the fluid from the storage unit as volume of the storage unit decreases with the deformation of the piezoelectric element, the abnormal discharge detection device comprising:
 a measurement unit that measures at least two terminal voltages of the piezoelectric element at least two measurement times during application of a pulse of the drive voltage; and 
 a determination unit that determines if the discharge operation is being performed normally or not by determining if the terminal voltage has changed with time during application of the pulse of the drive voltage or not based on the at least two terminal voltages measured at the at least two measurement times. 
 
     
     
       2. The abnormal discharge detection device according to  claim 1 , wherein
 the determination unit determines if the discharge operation is being performed normally or not by comparing a first terminal voltage, which is a value measured at a first measurement time during application of the pulse of the drive voltage, with a second terminal voltage, which is a value measured at a second measurement time after the first measurement time, and determining if the second terminal voltage is larger than the first terminal voltage. 
 
     
     
       3. The abnormal discharge detection device according to  claim 2 , wherein
 the determination unit stores in advance a rate of change in terminal voltage per unit time during application of a pulse of the drive voltage, and determines if the discharge operation is being performed normally or not by determining if an amount of increase from the first terminal voltage to the second terminal voltage is equal to an amount of increase obtained from a period from the first measurement time to the second measurement time and the rate of change. 
 
     
     
       4. The abnormal discharge detection device according to  claim 1 , wherein
 the determination unit stores in advance threshold terminal voltages for each of the measurement times, and determines if the discharge operation is being performed normally or not by comparing each of the at least two terminal voltages with a corresponding one of the threshold terminal voltages. 
 
     
     
       5. The abnormal discharge detection device according to  claim 1 , wherein
 the measurement unit further measures a terminal voltage of the piezoelectric element immediately after application of the drive voltage is stopped, and 
 the determination unit further determines if the discharge operation is being performed normally or not based on whether or not the terminal voltage measured with the measurement unit immediately after application of the drive voltage is stopped is equal to the drive voltage. 
 
     
     
       6. The abnormal discharge detection device according to  claim 1 , wherein
 the determination unit determines that the discharge operation is being performed abnormally, when the terminal voltage measured with the measurement unit during application of the pulse of the drive voltage is equal to the drive voltage. 
 
     
     
       7. A method for detecting an abnormal fluid discharge operation in a fluid supply device, the fluid supply device including a drive unit that outputs a pulsed drive voltage, a piezoelectric element that is repeatedly deformed when the pulsed drive voltage is applied, and a storage unit that stores therein fluid to be supplied, and the fluid supply device discharging the fluid from the storage unit as volume of the storage unit decreases with the deformation of the piezoelectric element, the method comprising:
 measuring at least terminal voltages of the piezoelectric element at least two measurement times during application of a pulse of the drive voltage; and 
 determining if the discharge operation is being performed normally or not based on whether or not the at least two terminal voltages measured at the at least two measurement times have changed with time.