LIQUID DELIVERY PUMP

PROBLEM TO BE SOLVED: To provide a liquid delivery pump capable of reducing compression capacity of a liquid in a pump chamber without making the metal inner wall of the pump chamber come in contact with an external form of a plunger.SOLUTION: The liquid delivery pump includes the cylindrical pump chamber wherein the inside is made of a metal, the plunger inserted into the pump chamber from its pointed head and increasing and decreasing the volume of pump chamber by reciprocating in a fixed direction, a volume reducing member made of a resin and lessening a gap between the volume reducing member and the plunger by covering at least a part of the inner wall of the pump chamber, and a seal member for sealing the pump chamber by sliding with an outer peripheral surface of the plunger at a plunger-insertion section of the pump chamber. Preferable examples of the volume reducing member are a cylindrical sleeve covering at least a part of the inner peripheral surface of the pump chamber, a spacer disposed on the innermost face of the pump chamber and lessening a gap between the spacer and the pointed head of the plunger which reaches a top dead center, or both of the sleeve and the spacer.