Patent ID: 8668050

Claim:
A lubrication-condition detector that detects a lubricant shortage of a target portion, the target portion comprising: a fixed member; a movable member that repeats a predetermined operation relative to the fixed member at a predetermined cycle; a driver that drives the movable member including a motor which operates the movable member; and a lubricant that lubricates the movable member between the fixed member and the movable member, the lubrication-condition detector comprising: a physical-quantity measuring unit that continuously measures a physical quantity related to the target portion; and a computer that determines a presence of a lubricant shortage of the target portion based on the physical quantity measured by the physical-quantity measuring unit, wherein the computer comprises: a cycle extractor that extracts for each operational cycle plural values of the physical quantity from the continuous measurements of the physical quantity measured by the physical-quantity measuring unit and times of measurement, the plural values of the physical quantity being associated with the movable member as it moves through the operational cycle; a representative-value calculator that calculates a representative value for each of a plurality of operational cycles, each of the representative values being calculated from the plural values extracted by the cycle extractor for the corresponding operational cycle; and a determining unit that determines a presence of a lubricant shortage of the target portion based on the representative values calculated by the representative-value calculator for corresponding plural operational cycles, wherein the physical value measured by the physical-quantity measuring unit is torque or electric current of the motor.