CONSTANT FLOW RATE/NON-PULSATING ROTARY VANE-TYPE POSITIVE DISPLACEMENT MACHINE

There is provided a technology of which main object is reduction of a flow rate fluctuation of working fluid and vibration reduction by suppression of a pressure pulsation therewith and which is also for reducing a pulse-like pressure pulsation, an exciting force, and leakage that occur when ports that communicate with a working chamber are switched at the same time in a rotary-vane-type displacement machine. First, a change pattern of each working chamber volume determined by the motion of vanes pressed against a cam-ring inner circumferential surface is improved and the fluctuation of the entire flow rate that is a time change of the total volume of each working chamber is reduced by devising the profile of the cam-ring inner circumferential surface. The devised profile is a profile in which a fixed interval of maintaining each working chamber volume to be in a state of being the maximum or minimum can be provided, and pressure balancing and formation of a seal portion with respect to the port side with which each working chamber newly communicates while passing therethrough are performed by utilizing the interval.