Patent ID: 8479886

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; 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 continuous measurements of the physical-quantity measuring unit and a measuring time thereof, 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 plural representative values 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, wherein the representative value is one of a maximum value, a minimum value, an average value, an effective value or a variation value of the physical quantity measured in the 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.