Liquid delivery pump

A liquid delivery pump that discharges a liquid, the liquid delivery pump comprising:

• a first plunger pump having a movable first plunger;
• a second plunger pump having a movable second plunger and connected to the first plunger pump;
• a pressure sensor disposed on a downstream side of the second plunger pump, and configured to measure a liquid delivery pressure that is a pressure of the liquid discharged from the second plunger pump;
• and
• a control unit configured to receive the liquid delivery pressure measured by the pressure sensor, and control driving of the first plunger and driving of the second plunger,
• wherein the control unit obtains a moving speed of the first plunger and a moving speed of the second plunger using a set of parameters depending on the liquid delivery pressure, the liquid delivery pressure, and a target flow rate which is a predetermined flow rate of the liquid,
• wherein the set of parameters are expressions representing a relationship between the liquid delivery pressure and a flow rate of the liquid, and a relationship between a basic flow rate and the flow rate of the liquid, and
• wherein the basic flow rate is a flow rate of the liquid in a compressed state discharged from the liquid delivery pump when there is no leakage.