Patent ID: 11879877
Assignee: SHIMADZU CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  F | IPC F  G

Claim 0:
1. A binary pump comprising:
a first pump part;
a second pump part provided separately from the first pump part;
an output part for outputting liquid delivered by the first pump part and/or the second pump part;
a switching valve that includes a first liquid delivery port to which the first pump part is connected, a second liquid delivery port to which the second pump part is connected, and an output port communicating with the output part, and is configured to be switched to any one of a first state, a second state, and a third state, wherein the first state is a state in which the first liquid delivery port is connected to the output port and the second liquid delivery port is not connected to any port, the second state is a state in which the second liquid delivery port is connected to the output port and the first liquid delivery port is not connected to any port, and the third state is a state in which both the first liquid delivery port and the second liquid delivery port are connected to the output port;
a first pressure sensor that detects a pressure in a space which exists between the first pump part and the switching valve as a first pressure;
a second pressure sensor that detects a pressure in a space which exists between the second pump part and the switching valve as a second pressure;
a backflow calculation part that is configured to obtain a change rate of a system pressure detected by the first pressure sensor or the second pressure sensor, and to calculate a backflow rate to the first pump part and a backflow rate to the second pump part based on the change rate of the system pressure; and
a backflow prevention part configured to switch the switching valve to the second state while the backflow rate to the first pump part calculated by the backflow calculation part exceeds a set flow rate for the first pump part or a value determined based on the set flow rate, and to switch the switching valve to the first state while the backflow rate to the second pump part calculated by the backflow calculation part exceeds a set flow rate for the second pump part or a value determined based on the set flow rate, in a case where the switching valve is set to the third state and the liquid delivery by the first pump part and the second pump part is performed.