Flowpath switching valve and liquid chromatograph analysis device

Abstract

In the present invention, the center between an action point 225, at which a rotor seal 240 is fixed and rotated, and a force application point 235, at which stress that causes a rotation member to rotate is received, is included in a second-site 230 constraint area formed by radial bearings 270. The distance between one end on the force application point 235 side of the constraint area and the center is longer than the distance between one end on the action point 225 side of the constraint area and the center. Due to this configuration, provided are a flowpath switching valve and a liquid chromatograph analysis device with which it is possible to suppress the occurrence of partial contact compared to the prior art.

Description

Flow path switching valve and liquid chromatograph analyzer

[0001] The present invention relates to a flow path switching valve and a liquid chromatograph analyzer.

[0002] A liquid chromatograph (LC, Liquid Chromatograph) is a chromatograph that uses a liquid as a mobile phase to be sent to a column for separating a sample. A liquid sample containing a measurement target introduced from an injection unit into an analysis flow path is sent to a column by the mobile phase. Using the difference in affinity between the stationary phase filled in the column and the mobile phase, the liquid sample is separated into a plurality of components. Each separated component is detected using a detector such as an ultraviolet / visible spectrophotometer, a fluorescence spectrophotometer, or a mass spectrometer (see, for example, Patent Document 1).

[0003] Patent No. 7351897

[0004] A flow path switching valve mounted on a liquid chromatograph or the like is composed of a stator for connecting pipes, a rotor seal, a rotor for rotating the rotor seal, a housing for holding them, and the like. The rotor seal is pressed against the stator by a spring or the like, and liquid tightness is maintained between the flow path formed in the rotor seal and the flow path formed in the stator. The rotor seal is fixed to the rotor by a pin, and by rotating the rotor with a motor, the rotor seal also rotates, and the flow path of the rotor seal is switched with respect to the flow path of the stator.

[0005] In such a flow path switching valve, the flow path is switched while maintaining high pressure by sliding two parts provided with a plurality of grooves for guiding the fluid while bringing them into close contact.

[0006] However, if the rotation axis is displaced with respect to the seal surface during sliding, one-sided contact of the sliding surface occurs. When one-sided contact occurs, wear of the sliding surface tends to progress, which causes liquid leakage and biting, and affects the life of the parts. Therefore, further improvement is required.

[0007] The present invention provides a flow path switching valve and a liquid chromatograph analyzer capable of suppressing the occurrence of one-sided contact as compared with the prior art.

[0008] A flow path switching valve according to one embodiment of the present invention comprises a stator having a plurality of through holes, a rotor seal having grooves and rotating in contact with the stator, a rotating part having a first part that fixes and rotates the rotor seal, and a second part that is configured as a drive shaft for the first part, and a radial bearing provided in the circumferential direction of the second part, wherein the centers of the point of application that fixes and rotates the rotor seal in the first part and the point of force that receives the stress that rotates the rotating part in the second part are included in the constrained region of the second part by the radial bearing, and the distance between one end of the constrained region on the point of force side and the center is longer than the distance between one end of the constrained region on the point of application side and the center.

[0009] According to the present invention, the occurrence of uneven contact can be suppressed compared to conventional methods.

[0010] A schematic diagram illustrating an example of the configuration of a liquid chromatograph analyzer. A schematic diagram of a flow path switching valve. A schematic diagram showing the effect of stress in the flow path switching valve. A schematic diagram of a flow path switching valve according to a modified example of Embodiment 1. A schematic diagram of a flow path switching valve according to Embodiment 2.

[0011] Hereinafter, embodiments of the flow path switching valve and liquid chromatograph analyzer of the present invention will be described with reference to the attached drawings.

[0012] In the attached drawings, functionally identical elements may be indicated by the same or corresponding numbers. While the attached drawings illustrate embodiments and implementations in accordance with the principles of this disclosure, they are for the purpose of understanding this disclosure and are not intended to restrict its interpretation. The descriptions herein are typical examples and do not limit the claims or applications of this disclosure in any way.

[0013] While this embodiment is described in sufficient detail for those skilled in the art to implement the disclosure, other implementations and forms are possible, and it is important to understand that the configuration and structure can be changed and various elements replaced without departing from the scope and spirit of the technical idea of ​​this disclosure. Therefore, the following description should not be interpreted as limiting it to this embodiment. For example, the shape and number of flow paths of the automatic switching valve are not limited to the embodiments described below.

[0014] Furthermore, in the drawings used herein, identical or corresponding components are denoted by the same or similar reference numerals, and repeated explanations of these components may be omitted.

[0015] <Embodiment 1> The flow path switching valve and liquid chromatograph analyzer of Embodiment 1 will be described with reference to Figures 1 to 4.

[0016] Referring to the schematic diagram in Figure 1, an example of the configuration of a liquid chromatograph analyzer will be explained. The liquid chromatograph analyzer 100 consists of a mobile phase tank 101, a liquid delivery unit 102, a sample introduction unit 103, a column temperature control unit 104, a detector 105, a control unit 114, an operation unit 118, and a display unit 119, etc.

[0017] The liquid delivery unit 102 includes, for example, a liquid delivery device 106, a pressure detector 107, a flow path switching valve 108, a liquid delivery flow path C0, an analysis flow path C1, and a drainage flow path C2. The liquid delivery device 106 has the function of drawing in the mobile phase used for transporting and separating the sample from the mobile phase tank 101, compressing it under high pressure, and discharging it. This liquid delivery unit 102 can be configured, for example, as a liquid chromatograph system capable of delivering one or more mobile phases from a single liquid delivery device 106.

[0018] The pressure detector 107 is a sensor device that detects the pressure in the piping leading to the detector and the liquid delivery channel C0 through which the mobile phase of the liquid delivery unit 102 is delivered.

[0019] The flow path switching valve 108 is connected to the downstream side of the liquid delivery device 106 and has the function of selectively connecting the liquid delivery flow path C0 to either the analysis flow path C1 connected to the sample introduction unit 103 or the drainage flow path C2. Furthermore, as will be described later, the flow path switching valve 108 is configured to form a tightly sealed state in which it is not connected to either the analysis flow path C1 or the drainage flow path C2 when performing a pressure resistance test.

[0020] The sample introduction unit 103 is broadly composed of a sample introduction valve 109, a sample metering pump 110, and a needle 111.

[0021] The sample introduction valve 109 is connected to the aforementioned analysis channel C1 and has a switching function for introducing the mobile phase into the downstream analysis channel C3 while simultaneously introducing the sample discharged by the sample metering pump into the analysis channel C3. The sample introduction valve 109 is equipped with a sample inlet 112 for introducing the sample.

[0022] The sample metering pump 110 has the function of discharging the sample to be measured through the needle 111 into the sample inlet 112. The sample introduced from the sample metering pump 110 to the sample introduction valve 109 is mixed with the mobile phase and discharged into the analysis channel C3.

[0023] The column temperature control unit 104 is capable of housing the separation column 113 and has the function of controlling the temperature of the separation column 113 to a constant temperature state. The separation column 113 is connected to the sample introduction unit 103 via the analysis channel C3 and separates the sample introduced from the sample introduction unit 103 by the mobile phase into its respective components.

[0024] The detector 105 is connected downstream of the column temperature control unit 104 and has the function of detecting each component of the sample separated in the separation column 113.

[0025] The central control unit 114 controls the liquid delivery unit 102, the sample introduction unit 103, the column temperature adjustment unit 104, and the detector 105 to control the acquisition of liquid chromatography data and the operation for pressure resistance testing.

[0026] The operation unit 118 includes, for example, input devices such as a keyboard, numeric keypad, and mouse, and is a device for the user to input various instructions related to control in the central control unit 114.

[0027] The display unit 119 is a device for displaying analysis conditions and analysis results, and may consist of, for example, a liquid crystal display or an organic EL display.

[0028] Next, the details of the flow path switching valve will be explained using Figures 2 and 3. In the following explanation, the flow path switching valve 108 or the sample introduction valve 109 described above will be used as an example.

[0029] Figure 2 shows an example of the configuration of the flow path switching valve 108 and the sample introduction valve 109.

[0030] The flow path switching valve 108 or sample introduction valve 109 is a high-pressure switching valve and, as shown in Figure 2, includes a housing 210, a stator 201, a first part 220, a second part 230, a rotor seal 240, a disc spring 250, a thrust bearing 260, and a radial bearing 270, etc.

[0031] The housing 210 is a component that houses the first part 220, the second part 230, the rotor seal 240, the disc spring 250, the thrust bearing 260, and the radial bearing 270 in holes formed inside it.

[0032] The hole in the housing 210 has a diameter that changes in three stages from the opening side to the back side. The rotor seal 240 and the first part 220 are housed in the area with the largest diameter closest to the opening side, the disc spring 250, the thrust bearing 260 and part of the second part 230 are housed in the area one stage further back, and the radial bearing 270 and the remaining part of the second part 230 are housed in the area with the smallest diameter at the back. The opening side of the hole is covered by the stator 201 fixed to the housing 210.

[0033] The rotor seal 240 is pressed against the stator 201 by a disc spring 250 and contacts the stator 201 via a contact surface. This normally maintains liquid tightness. This contact surface also acts as a sliding surface, and the rotor seal 240 rotates while in contact with the stator 201. The rotation angle of the rotor seal 240 is measured, for example, by equipping a motor (omitted for illustrative purposes) connected to the second part 230 with an encoder, but the configuration is not limited to this.

[0034] The stator 201 has a first through hole 202, a second through hole 203, and a third through hole 204. In contrast, the rotor seal 240 has multiple grooves. The main difference between the flow path switching valve 108 and the sample introduction valve 109 is the shape of these first through hole 202, second through hole 203, third through hole 204, and grooves.

[0035] The first part 220 is a roughly disc-shaped member, with one side fixed to the rotor seal 240 by a pin or the like, and the other side fixed to a shaft-shaped second part 230 which is configured as the drive shaft of the first part 220. The first part 220, the second part 230, and the like constitute the rotating part.

[0036] The three first through holes 202, second through hole 203, and third through hole 204 formed in the stator 201, and the grooves formed in the rotor seal 240, constitute a portion of the flow paths, such as the liquid delivery flow path C0, the analysis flow path C1, the drainage flow paths C2, C4, and the analysis flow path C3. By rotating the second part 230, the first part 220 and the rotor seal 240 fixed to the second part 230 rotate, and the first through holes 202, second through hole 203, and third through hole 204 of the stator 201, which are connected to the grooves, switch, thereby switching the flow path.

[0037] The disc spring 250 is positioned between the first portion 220 and the thrust bearing 260, with one end pressing against the housing 210 via the thrust bearing 260 and the other end pressing against the first portion 220, thereby pressing the rotor seal 240 against the stator 201.

[0038] Multiple radial bearings 270 are provided in the circumferential direction of the shaft-shaped second portion 230, and by restraining the second portion 230 to the housing 210, the axial movement of the second portion 230 is restricted.

[0039] In Figure 2, four radial bearings 270 are provided along the second portion 230, which is the drive shaft of the flow path switching valve 108 or the sample introduction valve 109. All of these radial bearings 270 are configured to have the same diameter, specifically, an outer diameter that is approximately the same as the inner diameter of the innermost hole in the housing 210. More preferably, they should be exactly the same.

[0040] Next, Figure 3 will be used to explain in detail the effect of stress during operation in the flow path switching valve 108 and the sample introduction valve 109. Figure 3 is a schematic diagram showing the effect of stress in the flow path switching valve.

[0041] As shown in Figure 3, when attempting to rotate the valve, that is, when the rotor seal 240 rotates, a bending stress is generated at the point of force application 235, which receives the stress that rotates the second portion 230, causing the second portion 230 to bend. This bending stress acting at the point of force application 235 changes according to the lever principle, depending on the distance L1 from the point of force application side constraint point 285, which is the radial bearing 270 closest to the point of force application 235, within the constraint region of the second portion 230 that is constrained by the multiple radial bearings 270. In other words, it is preferable that the distance L1 from the point of force application side constraint point 285 to the point of force application 235 is short.

[0042] Furthermore, at the point of application 225, the rotor seal 240 is pressed against the stator 201 under high pressure by the disc spring 250. As a result, stress is generated at the point of application 225, which is the connection point between the rotor seal 240 and the first part 220, due to frictional resistance during rotation. This stress, for the same reasons as the bending stress acting at the point of force application 235, also changes depending on the distance L2 from the point of application side constraint point 280 by the radial bearing 270 on the side of the point of application 225 within the constraint region constrained by the radial bearing 270 of the second part 230. Therefore, it is preferable that the distance L2 from the point of application side constraint point 280 to the point of application 225 is short.

[0043] Here, since the stress acting on the force point 235 is greater than the bending stress acting on the action point 225, in order to reduce the overall stress, it is more effective to reduce the stress acting on the side of the force point 235 with a larger magnitude. Therefore, in order to make the distance L1 shorter than the distance L2, it is effective that the central position of the axial length of the constrained region constrained by the radial bearing 270 is closer to the force point 235 side.

[0044] Therefore, in the flow path switching valves 108 and the sample introduction valve 109 of the present embodiment, when the axial length from the action point 225 to the force point 235 is L, the central position (the position of L / 2) between the action point 225 for fixing and rotating the rotor seal 240 and the force point 235 receiving the stress for rotating the rotating part is included in the constrained region of the second part 230 by the radial bearing 270. Here, the constrained region is the region between the force point side constraint point 285 and the action point side constraint point 280 in the axial region of the second part 230.

[0045] Further, the distance (L / 2 - L1) between the force point side constraint point 285 by the radial bearing 270 on the most force point 235 side and the center is made longer than the distance (L / 2 - L2) between the action point side constraint point 280 by the radial bearing 270 on the most action point 225 side and the center.

[0046] Here, it is desirable that the plurality of radial bearings 270 constrain at least 30% of the distance from the force point 235 to the action point 225.

[0047] Next, a modified example of the flow path switching valve 108A and the sample introduction valve 109A will be described with reference to FIG. 4. FIG. 4 is a schematic view of a flow path switching valve according to a modified example of Embodiment 1.

[0048] The flow path switching valve 108A and the sample introduction valve 109A shown in FIG. 4 have a form in which the second part 230 is constrained by one long radial bearing 270A in the driving axis direction, different from the plurality of radial bearings 270.

[0049] Next, the effects of the present embodiment will be described.

[0050] The flow path switching valve 108 and sample introduction valve 109 of the above-described embodiment 1 include a stator 201 having a plurality of first through holes 202, second through holes 203, and third through holes 204; a rotor seal 240 having grooves and rotating in contact with the stator 201; a rotating part having a first part 220 that fixes and rotates the rotor seal 240, and a second part 230 configured as a drive shaft for the first part 220; and radial bearings 270 and 270A provided in the circumferential direction of the second part 230. The centers of the point of application 225 that fixes and rotates the rotor seal 240 and the point of force application 235 that receives the stress that rotates the rotating part are included in the constrained region of the second part 230 by the radial bearings 270 and 270A, and the distance between one end of the constrained region on the point of force application 235 side and the center is longer than the distance between one end of the constrained region on the point of application 225 side and the center.

[0051] This allows for a longer restraining distance for the second part 230, which is the drive shaft, thereby improving shaft accuracy. In addition, by shifting the restraining position towards the point of force 235, the moment force applied to the rotor seal 240 when the second part 230 rotates can be reduced, thus suppressing uneven contact compared to conventional designs. As a result, wear on the sliding surface can be reduced compared to conventional designs, reducing fluid leakage and galling, and extending the lifespan of the parts.

[0052] Furthermore, since multiple radial bearings 270 are provided along the drive shaft, it becomes easier to increase the restraint distance of the second portion 230.

[0053] Furthermore, since all of the radial bearings 270 are configured to have the same diameter, it is easy to create a configuration that suppresses axial displacement of the radial bearings 270 by the housing 210, and the preparation of the radial bearings 270 themselves and the fixing work to the housing 210 are made very easy, thus achieving a reduction in manufacturing costs.

[0054] Furthermore, by constraining at least 30% of the distance from the point of force application 235 to the point of application 225, a stronger constraint can be achieved.

[0055] <Embodiment 2> The flow path switching valve and liquid chromatograph analyzer of Embodiment 2 will be described with reference to Figure 5. Figure 5 is a schematic diagram of the flow path switching valve according to Embodiment 2.

[0056] In the flow path switching valve 108B and sample introduction valve 109B shown in Figure 5, the multiple radial bearings are the same as in the flow path switching valve 108 and sample introduction valve 109 of Embodiment 1. However, the difference is that a spacer 275B is further arranged between the radial bearing 270B2 closest to the point of force 235 and the radial bearing 270B1 closest to the point of application 225, among the radial bearings 270B1 on the point of application side and the radial bearing 270B2 on the point of application side. Note that Figure 5 shows an example with two radial bearings, but there may be three or more, and it is not particularly limited.

[0057] The spacer 275B only needs to be able to suppress the axial movement of the radial bearing 270B1 on the point of application side and the radial bearing 270B2 on the point of force application side, and is not particularly limited in size or material.

[0058] The other configurations and operations are substantially the same as those of the flow path switching valve and liquid chromatograph analyzer described in Embodiment 1 above, and details are omitted.

[0059] In the flow path switching valve and liquid chromatograph analyzer of Embodiment 2, substantially the same effects as those of the flow path switching valve and liquid chromatograph analyzer of Embodiment 1 described above can be obtained.

[0060] Furthermore, by providing a spacer 275B positioned between the radial bearing 270B2 closest to the point of force 235 and the radial bearing 270B1 closest to the point of application 225, it becomes possible to reduce the number of bearings required.

[0061] 100...Liquid chromatograph analyzer 101...Mobile phase tank 102...Liquid delivery unit 103...Sample introduction unit 104...Column temperature control unit 105...Detector 106...Liquid delivery device 107...Pressure detector 108, 108A, 108B...Flow path switching valve 109, 109A, 109B...Sample introduction valve 110...Sample metering pump 111...Needle 112...Sample inlet 113...Separation column 114...Control unit 118...Operation unit 119...Display unit 201...Stator 202...First through-hole 203...Second through-hole 204...Third through-hole 210...Housing 220...First part 225...Point of application 230...Second part 235...Point of force application 240...Rotor seal 250...Disc spring 260...Thrust bearing 270, 270A...Radial bearing 270B1...Radial bearing on the point of application 270B2...Radial bearing on the point of force application 275B...Spacer 280...Constraint point on the point of application 285...Constraint point on the point of force application C0...Fluid delivery channel C1...Analysis channel C2...Drainage channel C3...Analysis channel

Claims

1. A flow path switching valve comprising: a stator having a plurality of through holes; a rotor seal having grooves and rotating in contact with the stator; a rotating part having a first part that fixes and rotates the rotor seal, and a second part that is configured as a drive shaft for the first part; and a radial bearing provided in the circumferential direction of the second part, wherein the center of the point of application that fixes and rotates the rotor seal and the point of force that receives the stress that rotates the rotating part are included in the constrained region of the second part by the radial bearing, and the distance between one end of the constrained region on the point of force side and the center is longer than the distance between one end of the constrained region on the point of application side and the center.

2. A flow path switching valve according to claim 1, wherein a plurality of radial bearings are provided along the drive shaft.

3. A flow path switching valve according to claim 2, wherein all of the radial bearings are configured to have the same diameter.

4. A flow path switching valve according to claim 2, further comprising a spacer disposed between the radial bearing closest to the point of force application and the radial bearing closest to the point of action among a plurality of radial bearings.

5. A flow path switching valve according to claim 1, wherein the restraining region restrains a distance of at least 30% of the distance from the point of force application to the point of application.

6. A liquid chromatograph analyzer equipped with a flow path switching valve according to any one of claims 1 to 5.

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