JPH04276190A - Liquid feeding device for analyzing device - Google Patents

Abstract

PURPOSE:To automatically discharge bubbles outside a flow passage when the bubbles in a plunger reciprocating type pump are detected and the bubbles are generated. CONSTITUTION:A drain valve 36 for discharging the liquid in a flow passage is installed in a flow passage on the downstream side of a plunger reciprocating type pump 12 for sending out liquid, and an optical sensor 28 for detecting bubbles is installed in the suction pipe 26 of the pump 12. Further, a bubble detection part 44 for detecting the bubbles by comparing the detection signal level detected by the optical sensor 28 and a previously set standard level, valve control part 46 for opening the drain valve 36 for a prescribed time through a valve driving passage 48 so that the liquid in the flow passage is discharged outside when the bubbles are detected, and a pump control part 50 for increasing the flow rate of the pump 12 for a certain time through a pump driving circuit 52 when the bubbles are detected are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid feeding device equipped with a plunger reciprocating pump for feeding a liquid such as a mobile phase in a liquid chromatograph, a flow injection analyzer, or the like.

0002

2. Description of the Related Art In a liquid feeding device using a reciprocating plunger pump, if air bubbles enter the liquid feeding chamber of the pump, normal liquid feeding cannot be performed. Therefore, in conventional liquid chromatographs, a pressure sensor is provided in the pump discharge side flow path, and the occurrence of bubbles is ascertained by monitoring fluctuations in the liquid feeding pressure using the pressure sensor.

0003

[Problem to be solved by the invention] Even if the liquid feeding pressure fluctuates, there are various factors that cause the pressure fluctuation other than bubble generation, so it is difficult to assume that bubbles are generated just because the liquid feeding pressure fluctuates. It is impossible to say for sure. An object of the present invention is to provide a liquid delivery device that can detect air bubbles in a plunger reciprocating pump and automatically discharge the air bubbles out of the flow path when the air bubbles are generated. It is.

0004

[Means for Solving the Problems] The present invention will be explained using FIG. 1 showing an embodiment and FIG. 2 showing a control section 40 in FIG. 1. In the present invention, a plunger reciprocating liquid sending section 12 that sends out liquid, a drain valve 36 that is provided in a flow path downstream of the liquid sending section 12 and discharges the liquid in the flow path to the outside, and An optical sensor 28 for detecting air bubbles provided in the liquid feeding chamber 14 or the suction side piping 26 of the pump, and this optical sensor 2
a bubble detection unit 44 that detects bubbles by comparing the detection signal level detected at step 8 with a preset reference level; and a valve drive circuit that discharges the liquid in the flow path to the outside when a bubble is detected. 48, and a pump control section 50 that increases the flow rate of the liquid feeding section 12 for a certain period of time via a pump drive circuit 52 when air bubbles are detected. .

[0005]

[Operation] The operation of the present invention will be explained with reference to FIG. Here, the description will be made assuming that the optical sensor 28 is a light transmission type sensor. When liquid feeding is started, the optical sensor 28 detects the intensity of transmitted light. When the detected transmitted light intensity is lower than a certain set level, it is determined that no bubbles are generated. When the detected transmitted light intensity exceeds a certain level, it is determined that bubbles have occurred, and after the pump control unit 50 lowers the set flow rate of the pump to 0 in the pump drive circuit 52, the valve control unit 46 lowers the set flow rate of the pump to 0 in the valve drive circuit. 48, the drain valve 36 is opened to the waste liquid side. Then, the pump control section 5
0, the set flow rate of the pump is increased by the pump drive circuit 52, liquid is fed for a preset time at the increased flow rate, and the fed liquid is discharged from the drain valve 36 to the outside of the flow path. As a result, air bubbles are also discharged to the outside of the flow path. When the set time has elapsed, the pump control unit 50
The set flow rate of the pump drive circuit 52 is lowered to 0,
Further, the drain valve is closed by the valve drive circuit 48 by the valve control unit 46 . Then, the set flow rate is returned to the original state in the pump drive circuit 52 by the pump control unit 50, and normal liquid feeding operation is resumed. After that, the optical sensor 28 continues to detect bubbles.

[0006]

Embodiment FIG. 1 shows an embodiment. 12 is one of the liquid feeding parts of the parallel double plunger reciprocating pump. A plunger 16, which is prevented from leaking by a plunger seal 18, moves in a reciprocating direction in a liquid feeding chamber 14 of a liquid feeding section 12. Check valves 20 are provided on the inlet and outlet sides of the liquid feeding chamber 14, respectively.
22 is provided, and a suction pipe 2 of the suction side piping is provided on the inlet side.
6 is connected, and its tip is immersed in the liquid 24 to be delivered. 36 is a filter. The suction pipe 26 is made of a transparent material at least near the pump inlet,
A transmission type optical sensor 28 is provided near the pump inlet.

[0007] Discharge side piping 3 connected to the outlet of the liquid feeding chamber 14
2 is led to the analysis system via a pressure sensor 34 and a drain valve 36. A plunger reciprocating type liquid feeding section (not shown), which is the same as the illustrated liquid feeding section 12, is connected to the liquid feeding channel upstream of the pressure sensor 34. The other liquid feeding section is also provided with a transmission type optical sensor for detecting air bubbles in the suction pipe on the pump inlet side.

[0008] The drain valve 36 is driven by a motor 38 and switches whether the liquid sent from the liquid sending section is guided to the analysis system or discharged to the outside of the flow path. Reference numeral 40 denotes a control unit that drives the two liquid feeding units 12 to achieve a set flow rate, captures the detection signals of the optical sensors 28 of both liquid feeding units, and extracts the signals from the detection signals of these optical sensors 28. When air bubbles are detected, the drain valve 36 is switched from the analytical system side to the waste liquid side for a certain period of time via the motor 38, and the liquid feeding section 12
The set flow rate is controlled to be larger than the set flow rate during analysis for a certain period of time.

As shown in FIG. 4, the control section 40 includes a transmitted light level detection section 42 that takes in the detection signals a and b of the optical sensor 28 and detects the transmitted light level, and an output of the transmitted light level detection section 42. A CPU 54 that takes in and detects air bubbles and controls the drain valve 36 and the liquid feeding section 12;
A valve drive circuit 48, which is a motor drive circuit that drives the motor 38 of the drain valve 36, and two liquid feeding parts 12a.
, 12b. In FIG. 4, the two liquid feeding parts are shown as 12a and 12b, and the outputs from the respective optical sensors are shown as a and b.

The optical sensor 28 is not limited to a transmission type, but may be a reflection type to detect air bubbles. Alternatively, a part of the liquid feeding chamber 14 of the liquid feeding section may be made of a transparent material, and an optical sensor may be provided therein to detect air bubbles within the liquid feeding chamber 14. The drain valve 36 is not limited to one that is rotated by a motor to switch the flow path, but may be one that switches the flow path by other means.

[0011]

[Effects of the Invention] In the present invention, an optical sensor for detecting air bubbles is provided in the liquid feeding chamber or suction side piping of the pump, and when air bubbles are detected, the control unit automatically takes measures to expel the air bubbles from the flow path. By doing so, bubbles can be detected accurately and the normal state can be automatically restored. Additionally, since air bubbles are automatically expelled, long-term unattended operation is possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment.

FIG. 2 is a block diagram showing the functions of a control section in one embodiment.

FIG. 3 is a flowchart diagram illustrating an example of the operation of the present invention.

FIG. 4 is a block diagram showing a control unit in one embodiment.

[Explanation of symbols]

Claims (1)

[Claims] 1. A plunger reciprocating pump that sends out a liquid, a drain valve that is provided in a flow path downstream of the pump and discharges the liquid in the flow path to the outside, and a liquid feeding chamber of the pump or a suction chamber of the pump. An optical sensor installed on the side pipe for detecting air bubbles, an air bubble detection unit that detects air bubbles by comparing the detection signal level detected by this optical sensor with a preset reference level, and an air bubble detection unit that detects air bubbles by comparing the detection signal level detected by the optical sensor with a preset reference level An analyzer comprising: a valve control unit that opens the drain valve for a certain period of time so as to release liquid in the channel to the outside; and a pump control unit that increases the flow rate of the pump for a certain period of time when air bubbles are detected. liquid delivery device.