Patent ID: 9410543
Filing Date: 2016-08-09
CPC Classification: F04B,G01N

Claim Text:
1. A pump for liquid chromatograph characterized in that the pump comprises: a first plunger pump including, a first pressurizing chamber communicating with a first intake channel and a first ejection channel, and a first plunger configured to reciprocate inside the first pressurizing chamber; a second plunger pump including, a second pressurizing chamber communicating with a second intake channel and a second ejection channel, and a second plunger configured to reciprocate inside the second pressurizing chamber; a connection flow channel connecting the first plunger pump and the second plunger pump in series or in parallel; at least one electric motor configured to generate rotative power; a power transmission mechanism configured to convert the rotative power of the electric motor into linear reciprocating power and to transmit the power to the first plunger and the second plunger; the power transmission mechanism is formed of a cam; wherein the power transmission mechanism is configured to adopt a cam phase in which a differential value dL/dθ of a rotational angle θ relative to a lift amount L of the cam varies, the cam phase being established by changing a rotational speed of the electric motor in such a manner that a product of the differential value dL/dθ and the rotational speed of the electric motor becomes substantially constant as compared to values preceding and subsequent thereto; a motor driver configured to control the electric motor; at least one pressure detecting means provided in the first pressurizing chamber, the second pressure chamber, or a channel on a downstream side of any of the pressuring chambers; and a pump controller configured to read a measurement value of the pressure detecting means, to provide the motor driver with an instruction value, to cause the first plunger pump and the second plunger pump to perform intake and compression actions alternately at substantially constant time cycles, to set the pressurizing chamber of one of the plunger pumps to a state of a higher pressure during compression than the pressurizing chamber of the other plunger pump during compression, and to perform flow rate control by adjusting stroke lengths of the first plunger and the second plunger.