A liquid feeding device includes a discharge channel, a pump part, a feeding pressure sensor, a non-discharge pressure sensor, a pre-compression part, and a pre-compression speed determination part. The pump part has plunger pumps connected in series or parallel. At least one of the plunger pumps is a closed pump in which communication with the discharge channel is disconnected during a non-discharge time. The pre-compression part causes the closed pump that is after the suction process for sucking the liquid into a pump chamber is completed and during the non-discharge time to execute a pre-compression process to perform a discharge operation until a non-discharge pressure is substantially the same as a feeding pressure based on output of the feeding pressure sensor and output of the non-discharge pressure sensor. The pre-compression speed determination part determines a pre-compression speed of the closed pump in the pre-compression process.

A liquid delivery device includes a pump head having a pump chamber provided in the inside, a plunger whose tip is slidably inserted into the pump chamber, and at least one plunger pump having a drive mechanism that reciprocates the plunger in its axial direction. Then, at least one of the plunger pumps is a pressurizing pump that pressurizes a mobile phase including a compressible fluid sucked into the pump chamber and then discharges the mobile phase from the pump chamber, and at least the pump head of the pressurizing pump includes a cooling part that is connected to an outlet channel from the pump chamber, and allows the pump head to absorb heat of the mobile phase discharged from the pump chamber to cool the mobile phase.

A liquid feeding device includes a primary plunger pump; a secondary plunger pump connected downstream; a check valve provided between the primary plunger pump and the secondary plunger pump; a primary pressure sensor that detects a pressure in the pump chamber of the primary plunger pump; a liquid feeding control part configured to control operations of the primary plunger pump and the secondary plunger pump; and a liquid leakage detector configured to detect liquid leakage in the check valve based on a change in an output value of the primary pressure sensor during the waiting time. The liquid feeding control part is configured to control the operation of the primary plunger pump so that a waiting time, where the primary plunger pump stops without operating, is present while a discharge operation by the secondary plunger pump is performed after a suction by the primary plunger pump is completed.

A hydraulic system has two hydraulic circuits, each with a pressure generating unit acting on an actuator unit. The generating units are slot-controlled radial piston pumps and form a pump assembly with a single common pump support and single common rotor. The rotor is rotatable on a free protruding section of a common support hub and has piston-receiving bores on axially offset planes. The hub has two first and two second fluid bores. The first bores communicate with first pump connections and first control openings on the hub on a first plane, and the second fluid bores communicate with second pump connections and second control openings on the hub on a second plane. A first and a second adjustment frame, each having an eccentric ring and acting on the pump pistons, are disposed on respective planes perpendicular to the main axis and independently guided in a linearly movable manner.

A system for pumping fluid, including a sequence of two or more positive-displacement sub-systems each having a respective one-way inlet. A respective one-way flow path links each adjacent two of the sub-systems. A one-way outlet from a last of the sub-systems is provided. The system is capable of a mode of operation in which at least some of the sub-systems are substantially in phase with respect to each other to cause the system to draw fluid from more than one of the one-way inlets; and another other mode of operation in which at least some of the sub-systems are substantially in antiphase with respect to each other to increment a pressure of the fluid as the fluid moves along the sequence.

A liquid feeding device includes a discharge channel, a pump part, a feeding pressure sensor, a non-discharge pressure sensor, a pre-compression part, and a pre-compression speed determination part. The pump part has plunger pumps connected in series or parallel. At least one of the plunger pumps is a closed pump in which communication with the discharge channel is disconnected during a non-discharge time. The pre-compression part causes the closed pump that is after the suction process for sucking the liquid into a pump chamber is completed and during the non-discharge time to execute a pre-compression process to perform a discharge operation until a non-discharge pressure is substantially the same as a feeding pressure based on output of the feeding pressure sensor and output of the non-discharge pressure sensor. The pre-compression speed determination part determines a pre-compression speed of the closed pump in the pre-compression process.

A reciprocation pump has a supply liquid-side sub-pumping chamber and a waste liquid side sub-pumping chamber for containing and sending out liquid adapted to communicate with the supply liquid-side pumping chamber and with the waste liquid-side pumping chamber, respectively. The supply liquid-side sub-pumping chamber and the waste liquid-side sub-pumping chamber are interlocked with a reciprocation mechanism to vary their volume reversely to that of the volume variation of the supply liquid-side pumping chamber and the waste liquid-side pumping chamber, respectively. The reciprocating motion of the reciprocation mechanism enables the liquid to be supplied to the objective apparatus through the supply liquid-side pumping chamber and the supply liquid-side sub-pumping chamber. Also, it enables the waste liquid from the objective apparatus to be discharged to the outside through the waste liquid-side pumping chamber and the waste liquid-side sub-pumping chamber.

A liquid delivery device includes a pump head having a pump chamber provided in the inside, a plunger whose tip is slidably inserted into the pump chamber, and at least one plunger pump having a drive mechanism that reciprocates the plunger in its axial direction. Then, at least one of the plunger pumps is a pressurizing pump that pressurizes a mobile phase including a compressible fluid sucked into the pump chamber and then discharges the mobile phase from the pump chamber, and at least the pump head of the pressurizing pump includes a cooling part that is connected to an outlet channel from the pump chamber, and allows the pump head to absorb heat of the mobile phase discharged from the pump chamber to cool the mobile phase.

A liquid feeding apparatus has a primary side pump and a secondary side pump, and an outlet part of the primary side pump and an inlet part of the secondary side pump are connected to each other via a check valve. A temporary side pump pressure sensor for detecting the pressure inside the pump chamber of the primary side pump and a secondary side pressure sensor for detecting the pressure inside the pump chamber of the secondary side pump are provided. The signal of the primary side pressure sensor and the signal of the secondary side pressure sensor are acquired after the suction operation of the primary side pump is terminated and before the discharge operation of the secondary side pump is terminated.

A system and method for pumping fluid. The system includes a sequence of two or more positive-displacement sub-systems each having a respective one-way inlet. A respective one-way flow path links each adjacent two of the sub-systems. A one-way outlet from a last of the sub-systems is provided. The system is capable of a mode of operation in which at least some of the sub-systems are substantially in phase with respect to each other to cause the system to draw fluid from more than one of the one-way inlets; and another other mode of operation in which at least some of the sub-systems are substantially in antiphase with respect to each other to increment a pressure of the fluid as the fluid moves along the sequence.