Patent ID: 8894381
Filing Date: 2014-11-25
Classification: F04B,F04C

Abstract:
1. A compressor capacity control device, comprising: a compressor for generating compressed fluid; a pressure sensor for detecting the discharge pressure of the generated compressed fluid discharged from the compressor; an unloading means for setting the compressor in an unloading state and a loading state; a control means for controlling the unloading means so as to change-over a loading state regarding the compressor operation into an unloading state regarding the compressor operation and vice versa; the control means comprising: a timer for measuring elapsed time after a starting time point when the loading state regarding the compressor is changed into the unloading state regarding the compressor; a time cycle control section for controlling the unloading means so that the loading state is changed into the unloading state, when the measured elapsed time reaches a predetermined operation time span; and an upper limit pressure control section for controlling the unloading means so that the loading state is changed into the unloading state, when the discharge air pressure detected by the pressure sensor exceeds a prescribed upper limit pressure, prior to the control by the time cycle control section; wherein the control means controls the unloading means to change the unloading state into the loading state in a case where the discharge pressure becomes lower than a predetermined lower limit pressure; wherein the control means controls the unloading means to change the loading state to the unloading state when the measured elapsed time exceeds a predetermined operation time and the discharge pressure is higher than a minimum level pressure; and wherein the minimum level pressure is between the lower limit pressure and the upper limit pressure.