JP4830915B2 - Liquid feeding device - Google Patents

Description

  The present invention relates to a liquid delivery device used for a liquid chromatograph.

  A general liquid chromatograph configuration is shown in FIG. The liquid (mobile phase) placed in the reservoir 1 is sucked by the liquid feeding device 2 and fed. A pressure sensor 3 is installed on the downstream side of the liquid feeding device 2 to check the state of liquid feeding. The sample introduced from the injector 4 flows into the column 5 together with the mobile phase fed by the liquid feeding device 2. The introduced sample is separated for each component in the column 5. The column 5 is maintained at a constant temperature by the column oven 6. The sample separated in the column 5 passes through the detector 7 for each component over time, and is stored together with the used mobile phase in a waste liquid bottle 9 installed downstream of the detector 7. When the sample component passes through the flow cell portion, the detector 7 generates a detection signal corresponding to the concentration of the sample component. The detection signal is transmitted to the control unit 8, and the control unit 8 performs data processing. In addition, the control unit 8 sets the flow rate of the liquid delivery device 2, the temperature of the column oven 6, and the detection conditions of the detector 7, and executes an operation according to the analysis setting conditions.

  Liquid chromatographs require highly accurate liquid feeding with little pulsating flow under high pressure (several tens of MPa) conditions. Therefore, a plunger pump is frequently used as the liquid feeding device 2. The plunger pump is a liquid feeding device suitable for a liquid chromatograph, which feeds liquid by sucking and discharging liquid by reciprocating movement of the plunger. In particular, the parallel double plunger pump has a feature that a difference in flow rate between discharge and suction is small compared to a single plunger pump, a serial dual plunger pump, or the like, and is suitable for high-precision liquid feeding.

  The parallel-type double plunger pump is configured such that two plunger pumps are arranged in parallel so as to have a common suction port (branch point) and a common discharge port (confluence point). Each plunger pump is provided with plungers P1 and P2 which are driven by the rotational movements of the respective cams C1 and C2 to reciprocate. The cams C1 and C2 are fixed to each other so that the rotational phase difference thereof is always constant, and are driven to rotate at a constant speed by a single motor (not shown). The cam profiles of the cams C1 and C2 of both plunger pumps are shown in FIG. When the plunger P1 (solid line) is at the maximum discharge flow rate, the plunger P2 (broken line) is at the maximum suction flow rate. When the discharge flow rate at the plunger P1 starts to decrease, the plunger P2 takes charge at a flow rate sufficient to compensate for the decrease. Thus, the total of the discharge flow rates (that is, the flow rate at the confluence) by both the plungers P1 and P2 is designed to be always constant (for example, Patent Document 1).

  If the pumping is stopped for a long time, impurities and components contained in the mobile phase will adhere to the valve seat and valve body of the check valve, causing the valve body and the valve seat to stick, Drying may cause salt to precipitate and the valve body and valve seat to stick. The check valve disposed at the intake port and the discharge port of the plunger pump prevents the backflow by pressing the valve body against the valve seat, and thus is particularly likely to occur at the check valve on the suction side. This causes a problem that liquid feeding is not performed normally (liquid feeding failure) when the liquid is fed. As a configuration for eliminating liquid feeding defects, for example, a configuration for removing an air bubble generated in a flow path and providing an auxiliary pump upstream of a plunger pump has been proposed (Patent Document 2). Even when bubbles are generated in the main pump, the liquid is promptly returned to the normal liquid feeding state.

  A valve using a flow path switching valve instead of a check valve by a valve body / seat has been proposed. For example, two pumps are controlled so that the total discharge flow rate of both is a predetermined value, the port of the first pump 1 is connected to the liquid supply destination channel, and the port of the second pump is the supply source channel. A first state in which the first pump port is connected to the supply source flow path, and a second state in which the second pump port is connected to the liquid supply destination flow path; and the first and second states A valve for switching between the third state where both the pump ports are connected to the liquid supply destination flow path is provided, and this valve is switched in synchronism with the suction and discharge operations of the first and second pumps. (Patent Document 3)

JP-A-5-272449 JP-A-4-110656 JP 2003-107065 A

  When an auxiliary pump for eliminating the liquid feeding failure of the main pump is provided, the dead volume increases. In this regard, Patent Document 2 solves the problem of an increase in dead volume by providing a switching valve between the analysis flow channel and the drain flow channel downstream of the main pump and arranging and sucking the auxiliary pump on the drain flow channel side. Has proposed. However, considering that the auxiliary pump needs to have a liquid feeding capacity comparable to that of the main pump, the cost is inevitably increased. In addition, the possibility that the auxiliary pump may cause liquid feeding failure is as high as that of the main pump for analysis.

  The present invention has been made in view of the above-described problems. The liquid feeding device according to the present invention includes an upstream flow path that communicates with a reservoir that stores a liquid to be fed, a downstream flow path that communicates with a flow path to which the liquid is fed, A flow path communicating with the suction port of the first plunger pump, a flow path communicating with the discharge port of the first plunger pump, a flow path communicating with the suction port of the second plunger pump, the second plunger pump A flow path switching mechanism connected to a flow path communicating with the discharge port of the first plunger pump, the discharge port of the second plunger pump, the downstream side A first state in which a flow path is communicated, a suction port of the first plunger pump, a suction port of the second plunger pump, a flow path of the upstream side, and a discharge port of the first plunger pump; Communicating the suction port of the second plunger pump Wherein the switch and a second state that. With this configuration, the double plunger pump is provided with two three-way valves, and it is possible to switch between a state in which two plunger pumps are connected in parallel and a liquid is fed, and a state in which they are connected in series.

  Further, in the second state of the flow path switching mechanism, the discharge port of the second plunger pump and the suction port of the first plunger pump can be further communicated. With this configuration, it is possible to form a flow path for circulating the liquid between the two plunger pumps.

  Further, the discharge port of the first plunger pump, the suction port of the second plunger pump, and the upstream flow path communicate with each other, the discharge port of the second plunger pump, and the suction port of the first plunger pump. The third state communicating with the downstream channel can be switched. With this configuration, a branching flow path is formed in which fluid is fed to the inlet of the plunger pump on the side where the malfunction has occurred due to the plunger pump that operates normally, and communicates to the downstream side. It is possible to produce a large or small flow path resistance.

  Furthermore, it is preferable to provide a pressure sensor in the downstream channel. Based on the output of the pressure sensor, it is determined whether or not there is a liquid feeding failure in the first and second plunger pumps, and the suction port of one plunger pump and the discharge port of the other plunger pump in communication are communicated. Thus, the flow path switching mechanism can be switched.

  A 6-port rotary valve can be applied as the flow path switching mechanism. A liquid chromatograph may be configured by including an injector for introducing a sample into the flow path, a column for separating the sample for each component, and a detector for detecting the separated component in the downstream flow path of the liquid feeding device. Is possible.

  By configuring as in the present invention, the flow path through which the liquid is supplied from the reservoir is branched and supplied to the first and second plunger pumps, and the liquid is discharged from the first and second plunger pumps. And the state connected to the discharge port from the first (second) plunger pump and the suction port to the second (first) plunger pump are switched, so that the first (second) plunger The liquid discharged from the pump is sucked into the second (first) plunger pump. As a result, even if the check valve of either one of the plunger pumps is in a state where the valve body and the valve seat are adhered and fixed, impurities and precipitated salts are removed by the feeding of the other plunger pump. Or it melt | dissolves or it is pushed up by the pressure of liquid feeding, and comes to operate | move normally as a non-return valve. Therefore, it is possible to eliminate the problems caused by the adhesion of impurities and the adhesion due to the precipitation of salt without disassembling the liquid feeding device. Furthermore, it is not necessary to separately provide an auxiliary pump for eliminating liquid feeding defects. If it is performed when the apparatus is activated, it is not necessary for the operator to be aware of the operation, and the burden on the operator is reduced.

The present invention will be described below with reference to the drawings.
FIG. 1 shows the flow paths near the suction port and the discharge port of each of the two plunger pumps. First, in the operation of performing normal liquid feeding, the three-way valves 14, 15, 24, and 25 are in a state where the flow paths indicated by solid lines are communicated. The liquid supplied from the upstream reservoir and branched at the branch point is sucked into the first (second) plunger pump 10 (20) through the three-way valve 14 (24) by the reciprocating motion of the plunger 11 (21), It is discharged, merges at the merge point via the three-way valve 15 (25), and is fed downstream.

  When the first plunger pump 10 malfunctions, the three-way valves 14 and 25 are switched so that the flow paths indicated by broken lines and the three-way valves 15 and 24 are indicated by solid lines are communicated. . That is, a flow path (hereinafter referred to as “series flow path”) that connects two plunger pumps in series is formed. The liquid from the reservoir passes through the three-way valve 24, and the liquid sucked and discharged by the second plunger pump 20 passes from the three-way valve 25 (broken line) to the flow path 27 and the three-way valve 14 (broken line). As a result, the valve body / valve seat of the check valve disposed at the suction port 12 of the first plunger pump 10 is reached. The salt or the like fixing the valve body / valve seat is dissolved or removed by the liquid, or pushed up by the pressure of the liquid feeding. In conjunction with the suction / discharge operation of the plunger pump 10, the valve body performs the operation of separating from the valve seat / abutting on the valve seat, and the first plunger pump operates normally.

  When the second plunger pump 20 malfunctions, the flow path indicated by a broken line for the three-way valves 15 and 24 and the flow path indicated by a solid line for the three-way valves 14 and 25 are communicated. Switch. Similarly, salt or the like fixing the valve body / valve seat of the check valve disposed at the suction port 22 of the second plunger pump 20 is dissolved or removed by the liquid, or pushed up by the pressure of the liquid feeding. The second plunger pump 20 normally performs suction / discharge.

  When the three-way valves 14, 15, 24, and 25 are switched so that the broken-line flow path is communicated, the flow path connected to the reservoir is sealed by the three-way valves 14 and 24, and the flow path to the downstream side is the three-way valve 15, 25. In other words, the flow of liquid between the first plunger pump 10 and the second plunger pump 20 (hereinafter referred to as “circulation flow path”) is eliminated because the liquid does not flow in and out of the two plunger pumps. ) Is formed. This state is effective when it is not desired to consume extra liquid in the reservoir.

  An operator can operate by forming a series flow path or a circulation flow path for a certain period of time (for example, 5 minutes) when the liquid feeding device is started, and then switching to a normal flow path for analysis. However, it is not necessary to be aware of the operation, and the burden on the operator is reduced.

  FIG. 3 shows a configuration in which the liquid feeding device according to the present invention is applied to a liquid chromatograph. A flow path switching mechanism 30 is provided between the branch point and the merge point, and the flow path is switched as described above. If the flow path switching mechanism 30 is configured to switch the flow path by the control unit 8, the flow path can be switched according to the conditions set by the control unit 8.

  1 is a flow path switching valve having six ports, as shown in FIG. 2A, and simplifies the structure of the flow path and the control unit. Is possible. A flow path for introducing liquid from the reservoir to the port a of the flow path switching valve 35, a flow path connected to the suction port 12 of the first plunger pump to the port b, and a flow connected to the discharge port 23 of the second plunger pump to the port c. A downstream channel, a channel connected to the port d, a channel connected to the discharge port 13 of the first plunger pump, and a channel connected to the suction port 22 of the second plunger pump are connected to the port f. The ports a to f are formed at positions of 180, 120, 60, 0, 300, and 240 degrees in a clockwise direction on the circumference around the rotation axis of the rotor. In the rotor that operates to switch the flow path, the rotor grooves k and m are formed to face each other in a circular arc of about 120 degrees on the circumference centered on the rotor axis. The groove m communicates the ports f, a, and b, and the other rotor groove k communicates the ports c, d, and e. In the state of FIG. 2A, port a is a branch point and port d is a junction.

  As shown in FIG. 2B, when the rotor is rotated 90 degrees (clockwise) and the position of the rotor grooves k and m is changed, the rotor groove k causes the ports b and c to communicate with each other. The port e and the port f are in communication with each other. In this state, the port a and the port d are not communicated with any other port, and are equivalent to the above-described circulation flow path as a flow path. In this way, by changing the angle at which the rotor is rotated, other flow paths can be formed, and the same effect can be obtained with a simple configuration compared to the above-described one.

  As shown in FIG. 2 (c), when the rotor is rotated 60 degrees (clockwise) and the positions of the rotor grooves k and m are changed, the rotor groove k communicates the ports b, c and d, and the rotor groove m The ports a, e, and f are in communication. This state is effective when liquid feeding failure occurs in the first plunger pump 10 and the second plunger pump 20 is normal. In this state, the port a (reservoir) and the port e (the discharge port 13 of the first plunger pump 10) communicate with the port f connected to the suction port 22 of the second plunger pump 20. When a suction operation is performed by the second plunger pump 20, the liquid is supplied to the second plunger pump 20 through the reservoir, the port a, the port f, and the suction port 22. As for the discharge port 13 of the first plunger pump 10, the first plunger pump 10 has a problem, and therefore the liquid is not supplied at the beginning when the second plunger pump 20 starts the suction operation. Liquid is supplied only from the reservoir.

  The liquid discharged from the discharge port 23 of the second plunger pump 20 flows into the port c of the flow path switching valve 35. The liquid flowing in from port c is branched into two flow paths, port b and port d. The liquid flowing into the branched flow path is distributed according to the flow resistance ratio of the flow path ahead. When the flow resistance of the flow path of the port b and the port d is examined, the port b passes from the port e to the port f of the rotor groove m through the suction port 12 and the discharge port 13 of the first plunger pump 10 in which a problem has occurred. The port d has the total flow resistance of the downstream flow path (flow path from the confluence to the outlet through the column 5, the detector 7, etc.) for the port d. It will be. The liquid flowing in from the port c is distributed at a ratio of these flow path resistances.

  Even if the valve body and the valve seat of the check valve disposed in the first plunger pump 10 are firmly fixed and cannot be recovered only by liquid feeding of the second plunger pump 20, the second plunger pump 20 Since the delivered liquid is distributed as described above (in this case, all is delivered to the port d), excessive pressure is not generated by the liquid flowing in the normal analysis flow path. The burden on the second plunger pump 20 is reduced.

  When liquid feeding failure occurs in the second plunger pump 20, the rotor is rotated so that the rotor groove m is in a position where the ports a, b, and c communicate with the ports a, b, and c. You can do it.

  For the ports a to f and the rotor grooves k and m, only the positional relationship on the contact surface between the stator in which the ports a to f are formed and the rotor in which the rotor grooves k and m are formed is illustrated. These can be changed as appropriate. For example, as shown in FIG. 5, the ports a to f are formed at positions of 180, 135, 45, 0, 315, and 225 degrees clockwise on the circumference around the rotation axis of the rotor, and the rotor groove k , M may be formed so as to face each other in a circular arc of about 90 degrees on the circumference centered on the rotation axis of the rotor. FIG. 5A shows a normal liquid feeding state, where one rotor groove m communicates ports f, a, and b, and the other rotor groove k communicates ports c, d, and e. FIG. 5B shows a state in which the rotor is rotated 90 degrees (clockwise), the rotor groove k communicates the port b and the port c, and the rotor groove m communicates the port e and the port f. FIG. 5C shows a state in which the rotor is rotated 45 degrees (clockwise), the rotor groove k communicates the ports b, c, and d, and the rotor groove m communicates the ports a, e, and f.

  A pressure sensor is provided on the downstream side of the plunger pump, and the plunger pump operates by converting the rotary motion into a reciprocating motion by a cam connected to the rotation shaft of the motor. The shape of the cam and the rotation of the motor From the corner, it is possible to determine whether ejection or inhalation is being performed. From these configurations, it is possible to determine which of the first plunger pump 10 and the second plunger pump 20 has caused the liquid feeding failure. For example, when the pressure increase is not detected by the pressure sensor when the discharge amount of the first plunger pump 10 is maximized, it is determined that there is a problem in the liquid feeding of the first plunger pump 10.

  When starting the liquid delivery device, or when it is determined that any of the plunger pumps has malfunctioned during liquid delivery in the normal flow path, the suction port of the malfunctioning plunger pump and the normal plunger It is preferable to eliminate the liquid feeding defect by switching the discharge port of the pump to communicate. In addition, since the flow path that has been switched to eliminate the problem is not a flow path for performing normal analysis, it is not necessary to continue feeding at the flow rate set in the control unit. For example, in the case of a system that delivers a small amount of liquid, it can be expected to increase the liquid flow rate and shorten the time until the salt dissolves. However, it is preferable to change the flow rate in consideration of the configuration of the entire flow path to the detector (whether it is a system for micro analysis or a system for conventional analysis).

  In addition, the malfunction of the valve caused by the impurities and components in the mobile phase adhering to the check valve on the suction side and the valve body and the valve seat being fixed has been described. One of the two plunger pumps has poor fluid delivery due to the presence of air bubbles in one plunger pump, and the check valve on the discharge side is in a fixed state between the valve body and the valve seat in the same manner as the suction check valve above. Yes Liquid delivery failure caused by the presence of air bubbles in the plunger pump where this discharge side check valve is installed, and the discharge pressure sufficient to operate the discharge side check valve cannot be obtained, or the discharge side check valve In addition, the suction side check valve is also effective in recovering from a liquid feeding failure caused by malfunction.

  The above embodiment is merely an example of the present invention, and can be appropriately changed or modified within the scope of the gist of the present invention. Obviously, these changes and modifications are also included in the present invention.

  In addition to being suitable for an analyzer having a liquid delivery device such as a liquid chromatograph, it can also be applied to a large flow rate liquid delivery device used in a production line of a factory.

It is a figure which shows the flow-path structure of the liquid feeding apparatus which concerns on this invention. It is another Example of the liquid feeding apparatus which concerns on this invention. It is a figure which shows the structure which used the liquid feeding apparatus which concerns on this invention with the liquid chromatograph. (a) Configuration of a general liquid chromatograph, (b) A diagram showing a cam profile. It is another Example of the liquid feeding apparatus which concerns on this invention.

Explanation of symbols

1 ... Reservoir 2 ... Liquid feeding device (parallel double plunger pump)
DESCRIPTION OF SYMBOLS 3 ... Pressure sensor 4 ... Injector 5 ... Column 6 ... Column oven 7 ... Detector 8 ... Control part 9 ... Waste liquid bottle 10 ... 1st plunger pump 11 ... Plunger 12 ... Suction port (check valve)
13 ... Discharge port (check valve)
14, 15 ... Three-way valve 17 ... Bypass flow path 20 ... Second plunger pump 21 ... Plunger 22 ... Suction port (check valve)
23 ... Discharge port (check valve)
24, 25 ... Three-way valve 27 ... Bypass flow path 35 ... Flow path switching valve af ... Port

Claims (6)

An upstream flow path communicating with a reservoir in which liquid to be fed is stored,
A downstream-side flow path communicating with a flow path to which the liquid is sent,
A flow path communicating with the suction port of the first plunger pump;
A flow path communicating with the discharge port of the first plunger pump;
A flow path communicating with the suction port of the second plunger pump;
A flow path switching mechanism to which a flow path communicating with the discharge port of the second plunger pump is connected;
The flow path switching mechanism is
A discharge port of the first plunger pump, a discharge port of the second plunger pump, and the downstream channel, the suction port of the first plunger pump, the suction port of the second plunger pump, A first state communicating with the upstream flow path;
A liquid feeding device that switches between a discharge state of the first plunger pump and a second state in which the suction port of the second plunger pump communicates. In the liquid feeding apparatus of Claim 1,
In the second state of the flow path switching mechanism, the discharge port of the second plunger pump and the suction port of the first plunger pump are further communicated with each other. The liquid delivery device according to claim 2,
The discharge port of the first plunger pump, the suction port of the second plunger pump, and the upstream flow path communicate with each other, the discharge port of the second plunger pump, the suction port of the first plunger pump, A liquid feeding device that switches between a third state communicating with a downstream channel. The liquid delivery device according to claim 3,
A pressure sensor is provided in the downstream channel,
Based on the output of the pressure sensor, determine the presence or absence of liquid feeding failure in the first and second plunger pumps,
A liquid feeding device comprising: a control unit that switches the flow path switching mechanism so as to communicate a suction port of one plunger pump in which a problem has occurred and a discharge port of the other plunger pump. In the liquid feeding apparatus of any one of Claims 2-4,
The flow path switching mechanism is a 6-port rotary valve. 6. An injector for introducing a sample into the flow path, a column for separating the sample for each component, and a detection for detecting the separated component in the downstream flow path of the liquid delivery device according to any one of claims 1 to 5. Liquid chromatograph equipped with a vacuum vessel.

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