JP4983292B2 - Flow path switching valve - Google Patents

Description

  The present invention relates to a flow path switching valve used in a high performance liquid chromatograph or the like.

In a high performance liquid chromatograph, it is necessary to switch the liquid flow path under high pressure.
Conventionally, as a flow path switching valve in such an application, a disk-shaped rotor formed with a switching groove is rotated while being brought into contact with a disk-shaped stator formed with a through hole connected to the groove in a plane. A switching valve is used.
The stator is sandwiched between the housing top to which the flow path is connected and the rotor, and the rotor and the stator are in surface contact with each other to prevent liquid leakage in the flow path. When the rotor is rotated and slid at a certain angle, the flow path is switched.
As a material of such a conventional flow path switching valve, resin is used for the rotor and ceramic is used for the stator.

  However, if the valve is used for a long period of time, the sliding surface of the rotor made of a material softer than the stator will be worn, which increases the rotational torque of the valve, leakage of the fluid, and cross-contamination due to liquid remaining on the worn part of the rotor. There is a problem that causes an increase in

  In the flow path switching valve, the rotor is pressed against the stator with a strong force in order to prevent liquid leakage. When the rotor rotates in this state, if the material of the rotor is resin, the surface of the stator and the rotor is scraped off by friction due to the rotation to generate shavings, which causes deterioration of the subsequent column. On the other hand, when the rotor is made of ceramic, such shavings are not generated, but considering the sealing properties, both the stator and the rotor are made to have a fine surface roughness and a high degree of flatness. When such surfaces are pressed with a strong force, a mirror surface adhesion phenomenon called so-called linking occurs, which impairs the rotational operation of the rotor.

  On the other hand, a flow path switching valve is disclosed in which the rotor is made of a fluorocarbon-containing polymer and the durability of the rotor is improved by coating a tungsten carbide / carbon layer (see Patent Document 1). The tungsten carbide / carbon layer disclosed in Patent Document 1 has a structure in which hard tungsten carbide particles are dispersed in a soft amorphous carbon matrix, and is formed by alternately laminating amorphous carbon and tungsten carbide.

US Pat. No. 6,453,946

  In the present invention, in order to improve the durability of the softer contact surface between the rotor and the stator, the harder contact surface is a coating different from that of Patent Document 1 and has high adhesion to the base material. It is an object of the present invention to provide a flow path switching valve with further improved durability.

  The flow path switching valve of the present invention includes a stator and a rotor having contact planes that are in contact with each other, the stator has a flow port connected to each of the plurality of flow paths, and the rotor is within the flow port of the stator. The at least one groove for communicating the two is urged against the contact plane of the stator, and is slidably rotated so as to switch the flow port of the stator to be communicated. One of the contact planes of the stator and the rotor is made of resin, and the other is coated with a chromium nitride film.

  When configuring the flow path switching valve, one of the stator or rotor is made of a hard material such as metal, and the other is made of a soft material such as resin to prevent leakage of the flow path. There are many cases. In the present invention, the rotor having a resin surface is preferably a rotor, and the one coated with a chromium nitride film is preferably a hard stator, but the opposite is also possible.

In order to improve adhesion to the chromium nitride film and reduce the specular adhesion phenomenon, irregularities are formed on the surface of the base material on which the chromium nitride film is formed by a fine processing technique, and the chromium nitride film is formed on the irregularities. to form.

  As a preferable example of the material of the flow path switching valve, there can be mentioned one in which the stator is made of stainless steel and the unevenness is formed by the sand blast method.

  In the flow path switching valve of the present invention, one of the contact planes of the stator and the rotor is made of resin, and the other is coated with a chromium nitride film. The chromium nitride film has good adhesion to the base material on which the chromium nitride film is formed, and can reduce wear on the resin surface facing the chromium nitride film.

  Since the rotor is relatively easy to process as compared to the stator, it is preferable to use the rotor having the resin surface as the rotor and the base material coated with the chromium nitride film as the stator. Also, the stator replacement frequency can be reduced.

  If the concave and convex portions are formed on the contact plane of the stator using a microfabrication technique, and the chromium nitride film is formed on the concave and convex portions, the adhesion between the chromium nitride and the base material can be further improved, and , The mirror surface adhesion phenomenon can be reduced.

Examples of the present invention will be described below.
FIG. 1 is a schematic perspective view of a stator and a rotor portion of a flow path switching valve according to an embodiment.
The stator 11 is made of stainless steel and has an integrated housing top to which a flow path is connected. The stator sliding surface 13 of the stator 11 is in contact with the rotor sliding surface 17 of the rotor 15, and the through hole 19 provided in the stator 11 is electrically connected to the groove 21 provided in the rotor 15. The rotor 15 is made of, for example, polyether ether ketone (PEEK) resin, and a plurality of grooves 21 are provided in an arc shape.

On the stator sliding surface 13 of the stator 11, chromium nitride is formed to a thickness of about 0.6 μm by magnetron sputtering after the sliding surface 13 of the stainless steel stator 11 is mirror finished.
When coating is performed by magnetron sputtering, droplets and the like are less likely to adhere to the coating surface, and a smooth surface can be obtained. By reducing the coefficient of friction by the chromium nitride coating, the wear of the rotor can be reduced. Further, the chromium nitride coating makes the surface harder than that of a stainless steel base material, and therefore the sliding surface with the rotor 15 prevents the stator 11 from being damaged.

Further, as a pre-process for applying the chromium nitride coating, fine irregularities are formed on the stator sliding surface 13 by sandblasting, and chromium nitride is formed on the surface layer thereof . By providing minute irregularities before coating, it is possible to reduce wear due to excessive contact between the stator sliding surface and the rotor sliding surface.
Note that the chromium nitride coating is preferable because it has good adhesion to the sliding surface of the mirror-finished stator and is a technically stable formation method.

FIG. 2 is a schematic sectional view showing the overall structure of the flow path switching valve. The stator 11 is provided with a plurality of flow path connecting portions 23, and the tips thereof communicate with the through holes 19 of the contact plane 13.
The rotor 15 is attached to the tip of the shaft 25 and is urged toward the stator 11 by an elastic member 29 provided in a body portion 27 that rotatably supports the shaft 25. The body portion 27 is screwed to the outer peripheral portion of the stator 11 with bolts 31.
A groove 21 is formed in the contact plane 17 of the rotor 15 (see FIG. 1), and communicates with the through hole 19 of the contact plane 13 of the stator 11.
When switching the flow path, the shaft 25 is rotated to rotate and slide the rotor 15 with respect to the stator 11 to switch the connection between the through hole 19 and the groove 21.

Since the flow path switching valve of the present invention is coated with chromium nitride on the surface of the stator, the adhesion between the stator and the film is improved, thereby protecting the surface of the stator and reducing the wear of the rotor. Can do. Further, unlike the embodiment, the stator can be made of resin and the rotor can be made of stainless steel, and a chromium nitride film can be formed on the surface thereof.
In the embodiment, the through hole 19 in the contact plane of the stator is arranged on the circumference, and the groove 21 of the rotor communicates the two of them. A common hole is arranged in the center as a through hole, a plurality of holes are arranged on the circumference of the circumference, and the rotor groove selectively connects the common through hole of the stator to any through hole on the circumference Some of them are radially extending grooves. The present invention can be similarly applied to such a flow path switching valve.

  The present invention can be used for high-performance liquid chromatographs, analytical instruments and other instruments that require switching of flow paths.

It is a schematic perspective view of the stator and rotor part of a flow path switching valve. It is a schematic sectional drawing of the whole flow-path switching valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Stator 13 Contact plane 15 Rotor 17 Contact plane 19 Through-hole 21 Groove 23 Flow path connection part 25 Shaft 27 Body part 29 Elastic member 31 Bolt 33 Bearing

Claims (2)

The stator includes a stator and a rotor having contact planes in contact with each other, the stator has a flow port connected to each of the plurality of flow paths, and the rotor communicates two of the flow ports of the stator. In a flow path switching valve that has at least one groove, is urged by a contact plane of the stator, and rotates and slides so as to switch the flow port of the stator to be communicated.
One of the contact planes of the stator and the rotor is made of resin, and the other is made of stainless steel. The stainless steel contact plane is formed with irregularities by sandblasting, and a chromium nitride film is coated on the irregularities. The flow path switching valve.   2. The flow path switching valve according to claim 1, wherein the one having a resin surface is a rotor, and the one coated with a chromium nitride film is a stator.

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