JP3389649B2 - Liquid sending device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid sending device, and more particularly, to a liquid sending device provided with a pressure sensor for detecting a pressure of a liquid to be sent. 2. Description of the Related Art FIG. 2 is a flow chart showing an example of a conventional liquid feeding device. This liquid sending device is used for sending a mobile phase in a liquid chromatograph, and uses a series double plunger pump in which plunger reciprocating pumps 10 and 20 are connected in series. An analysis flow path C which reaches a column (not shown) via an injector (not shown) is connected to an outlet of the series double plunger pump. When a plunger reciprocating pump is used, the discharge pressure of the pump is usually monitored by a pressure sensor so that the pressure of the liquid to be sent does not become abnormally high due to clogging of the column or the like. Therefore, also in the present liquid sending device, the pressure sensor 32
Is provided. Further, a damper 34, a drain valve 36, and a filter 38 are sequentially provided in the analysis flow path C downstream of the pressure sensor 32. In the above-mentioned liquid feeding device, the first pump 10 sucks the mobile phase from the pump inlet and sends it intermittently to the second pump 20, and the second pump sends the mobile phase of the mobile phase sent from the first pump 10. Smooths pulsating flow. Then, the mobile phase whose pulsatile flow has been smoothed is discharged from the second pump 20 to the analysis channel C. The pressure (discharge pressure) of the discharged mobile phase is monitored by the pressure sensor 32. The pulsating flow (fluctuation in discharge pressure) that cannot be removed by the second pump 20 is attenuated by the damper 34. The mobile phase that has passed through the damper 34 reaches the drain valve 36. The drain valve 36 switches whether or not to discharge the mobile phase by opening and closing the drainage flow path D branched from the analysis flow path C. That is, when the drain valve 36 is opened, both the analysis flow path C and the drainage flow path D are in an open state. However, since the analysis flow path C includes a column and a resistance tube (not shown), the The phase is discharged via the drain passage D without being sent to a column or the like. On the other hand, when the drain valve 36 is closed, only the analysis flow path C is opened, so that the mobile phase is sent to a column or the like after the impurities are removed by the filter 38. The mobile phase sent to a column or the like is used for analyzing a sample by chromatography. [0004] In the above-described conventional liquid feeding apparatus, the capacity of the pressure sensor 32 and the damper 34 provided in the analysis flow path C is large, so that when the liquid is exchanged, the flow rate is reduced. It takes a long time for the inside of the road to be completely replaced with fresh liquid. In a liquid chromatograph, a plurality of liquids are mixed in a pump chamber or in front of a pump chamber to form a mixed liquid (mobile phase), and the mixed liquid (mobile composition) is sent while changing the mixing ratio (composition) with time. There is a case (low pressure gradient liquid feeding is performed). In this case, since the capacities of the pressure sensor 32 and the damper 34 are large and there is a small dead end path in which the liquid is likely to stay, an error occurs in the mixing ratio (composition) of the mixed liquid (the target value at each time and the actual value of the liquid are actually transmitted). (Difference with the mixture ratio of the mixture). SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to enable the liquid to be sent to be quickly replaced and to perform a low-pressure gradient liquid sending. It is an object of the present invention to provide a liquid sending device capable of suppressing an error in a mixing ratio of a mixed solution to be sent to the liquid feeding device. According to the present invention, which has been made to solve the above-mentioned problems, a liquid is sucked and discharged to a main flow path, and the liquid is sent to a supply destination having resistance through the main flow path. Pump, a pressure sensor for detecting the pressure of the discharged liquid, and a flow path switching valve for switching the flow path of the discharged liquid between a main flow path and a drain flow path branched from the main flow path. Wherein the flow path switching valve is an open / close valve provided in a drain flow path, and the pressure sensor is provided in a drain flow path upstream of the open / close valve. When the flow path switching valve is opened, both the main flow path and the drainage flow path are in an open state. However, since the main flow path has a resistance at the supply destination, the liquid discharged from the pump is discharged. Are discharged through a drain passage. On the other hand, when the flow path switching valve is closed, only the main flow path is opened, so that the liquid discharged from the pump is sent to the supply destination via the main flow path. At this time,
The pressure sensor located upstream of the flow switching valve detects the discharge pressure of the pump. However, since the pressure sensor is provided in the drain flow path branched from the main flow path, the liquid sent to the supply destination does not pass through the pressure sensor.
Therefore, a space (pressure sensor) having a large capacity is excluded from the main flow path, and the liquid to be supplied to the supply destination can be replaced with a new liquid more quickly than before. Further, for example, when a mixed liquid (mobile phase) is sent to a supply destination (column) while changing the mixing ratio, as in a low-pressure gradient liquid sending in a liquid chromatograph, a space where the mixed liquid stays ( Since the pressure sensor is excluded from the main flow path, an error in the mixing ratio (difference between the target value and the actual value at each time) is smaller than in the related art. FIG. 1 is a flow chart showing a liquid feeding apparatus of the present embodiment. This liquid sending device is used for sending a mobile phase in a liquid chromatograph, as in the conventional example shown in FIG. 2, and uses a series double plunger pump. The first pump 10 on the upstream side of the two pumps constituting this series double plunger pump
The first plunger 12, the first pump chamber 14, the first
Check valves 15 and 16 provided at the inlet and the outlet of the pump chamber 14, respectively, the first plunger 12 and the first pump chamber 1
Seal 18 for preventing leakage of liquid from between the inner wall and the inner wall 4
The first plunger 12 reciprocates by a driving mechanism (not shown). The second, another pump
Pump 20 is similar to pump 20 except that no check valve is provided.
It has a configuration similar to that of the first pump 10 and includes a second plunger 22, a second pump chamber 24, a seal 28, and the like.
Connected to the entrance. The outlet side flow path (hereinafter referred to as “analysis flow path”) A of the second pump 20 reaches a column (not shown) via an injector (not shown). In the series double plunger pump having the above structure, the first pump 1 provided with the check valves 15 and 16 is provided.
0 intermittently sends the liquid sucked from the pump inlet to the second pump 20 by the reciprocating motion of the first plunger 12. The second pump 20 reciprocates the second plunger in synchronization with the first plunger by the cam,
The pulsating flow of the liquid delivered by the first pump 10 is smoothed. As a result, the serial double plunger pump continuously sends out the liquid (mobile phase) to the analysis channel A at a constant flow rate. The difference between the liquid feeding device of the present embodiment and the conventional one is that
Analysis channel A, drain channel B, pressure sensor 32, damper 3
4, a pump outlet comprising a drain valve 36 and a filter 38. That is, in the liquid supply device of the present embodiment, the pressure sensor 32 and the damper 3 are provided in the drainage flow path B branched from the analysis flow path A connected to the outlet of the second pump 20.
4, and a drain valve 36 are provided in order toward the downstream. However, due to its function, the filter 38 for removing impurities in the mobile phase is not the drainage channel B but the analysis channel A.
It is provided in. In the liquid feeding apparatus of this embodiment having such a configuration, the discharge pressure is detected by the pressure sensor 32 as in the prior art. Further, the fluctuation (pulsation) of the discharge pressure is attenuated by the damper 34. However, unlike before,
Since the pressure sensor 32 and the damper 34 are provided in the drainage flow path B, when the drain valve 36 is closed, the mobile phase discharged from the second pump 20 does not pass through the pressure sensor 32 and the damper 34, The solution is sent to a column or the like.
Therefore, except for the filter 38, there is no space having a large capacity or a dead end in the mobile phase flow path (analysis flow path) A used for analysis. Therefore, when the mobile phase is exchanged, the liquid in the analysis flow path A is promptly replaced with the new mobile phase, and the analysis using the new mobile phase can be started earlier than in the past. In addition, when performing low-pressure gradient liquid feeding, a space (the pressure sensor 32 and the damper 34) in which the mixed liquid stays is excluded from the main flow path. The error of the composition) (difference from the target value at each time) is reduced. When the drain valve 36 is opened, both the analysis channel A and the drain channel B are opened. However, since the analysis channel A has columns and resistance tubes (not shown). ), The mobile phase is discharged through the drainage channel B without being sent to a column or the like. As described above, according to the present invention,
Since a space having a large capacity is removed from the main flow path that sends the liquid discharged from the pump to the supply destination, the liquid in the main flow path is promptly replaced with a new liquid when replacing the liquid when compared with the conventional case. The new liquid can be sent to the supply destination more quickly. Further, for example, when performing low-pressure gradient liquid feeding in a liquid chromatograph, since a space in which a mixed liquid as a mobile phase stagnates is excluded from the main flow path, an error in the mixing ratio (composition) (each (Difference from the target value at the time).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing a liquid feeding device according to one embodiment of the present invention. FIG. 2 is a flow diagram showing a conventional liquid feeding device. [Description of Signs] 10 ... first pump 20 ... second pump 32 ... pressure sensor 36 ... drain valve (valve) A ... analysis channel B ... drainage channel

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F17D 3/03 B67D 5/56 F04B 23/00 G01N 30/26 G01G 30/80

Claims (1)

(57) A pump for sucking a liquid, discharging the liquid to a main flow path, and feeding the liquid to a supply destination having resistance through the main flow path;
A liquid sensor comprising: a pressure sensor for detecting a pressure of the discharged liquid; and a flow path switching valve for switching a flow path of the discharged liquid between a main flow path and a drain flow path branched from the main flow path. A liquid feeder, wherein the path switching valve is an open / close valve provided in a drain passage, and the pressure sensor is provided in a drain passage upstream of the open / close valve.