Patent ID: 8246318

Claim:
A water-cooled air compressor comprising: a compressor body configured to compress air; a water-cooled heat-exchanger configured to cool the compressed air by using cooling water; a compressed air supply pipe line configured to supply the cooled compressed air from the water-cooled heat-exchanger; a cooling water supply pipe line configured to supply the cooling water to the water-cooled heat-exchanger; an air feed pipe line configured to connect a portion of the compressed air supply pipe line provided on an outlet side of the water-cooled heat-exchanger; a first and a second cooling water discharge pipe line, wherein the first cooling water discharge pipe line is connected to the air feed pipe line, and wherein the second cooling water discharge pipe line is configured to branch from the cooling water supply pipe line; a first solenoid valve provided in the cooling water supply pipe line; a second solenoid valve provided in the first cooling water discharge pipe line; a third solenoid valve provided in the air feed pipe line; a check valve provided in the air feed pipe line; a fourth solenoid valve provided in the second cooling water discharge pipe line; and a control device configured to control a sequence of opening and/or closing of the first solenoid valve, the second solenoid valve, the third solenoid valve, and the fourth solenoid valve, thereby enabling a flow of cooling water, and in the alternative, a counterflow of cooling water, based on the sequence of opening and/or closing, wherein the control device includes: a storage portion configured to store a preset operation time of the compressor body, and to store at least timings used in the following sequence of operations: closing the first solenoid valve, closing the second solenoid valve, opening the third solenoid valve, and opening the fourth solenoid valve, and a computing portion configured to, when an operation time of the compressor body exceeds the preset operation time, stop the compressor body and deliver a sequence of opening signals and/or closing signals to the first solenoid valve, the second solenoid valve, the third solenoid valve, and the fourth solenoid valve, thereby enabling the counterflow of cooling water used to remove foreign matter from within the water-cooled heat-exchanger.