Fluid pump

A fluid pump comprising:

• three or more volume chambers that suction and discharge a fluid sequentially;
• moving elements that are respectively provided in the volume chambers, move relative to the volume chamber, and suction and discharge the fluid from and to the volume chamber;
• a cam that abuts against and drives the moving elements;
• and
• a driving section that drives at least one of the moving elements and the cam and relatively rotates the moving elements and the cam to discharge the fluid one time from each of the volume chambers in one cycle of the relative rotation,
• wherein, in each of the volume chambers, when suctioning and discharging the fluid, regarding a discharge rotation angle α from a start phase in which an instantaneous discharge amount of the fluid is zero is achieved, then a central phase in which the instantaneous discharge amount becomes a maximum value is achieved and an end phase in which the instantaneous discharge amount is again zero is achieved among one-cycle rotation angles Z according to the one cycle, α=(Z/M)×N is satisfied, where the number of volume chambers is M and any integer from 2 to (M−1) is N,
• when any one of the volume chambers has reached the end phase, an N-th volume chamber subsequent to the volume chamber is configured to be in the start phase,
• when a phase which is exactly in a middle between the start phase and the central phase is set as a first intermediate phase, an increasing tendency of the instantaneous discharge amount from the start phase to the first intermediate phase and an increasing tendency from the first intermediate phase to the central phase are inverted to each other with the central phase interposed therebetween, and
• an increasing tendency from the start phase to the central phase and a decreasing tendency of the fluid from the central phase to the end phase are symmetric to each other with the first intermediate phase interposed therebetween.