US-12618477-B2 - Fluid control valve, fluid control device, and fluid control valve manufacturing method

US12618477B2US 12618477 B2US12618477 B2US 12618477B2US-12618477-B2

Abstract

The present invention improves the sealability of a fluid control valve, and includes a valve seat having a flat valve seat surface and a valve plug having a flat sitting surface sitting on the valve seat surface. A first surface that is one of the valve seat surface and the sitting surface has a surface hardness higher than a surface hardness of a second surface that is the other one of the valve seat surface and the sitting surface.

Inventors

KAZUYA SHAKUDO

Assignees

HORIBA STEC, CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230327
Priority Date: 20220421

Claims (7)

1 . A fluid control valve comprising: a valve seat having a valve seat surface that is flat; and a valve plug having a sitting surface that is flat and that sits on the valve seat surface, wherein the valve seat and the valve plug are both made of metal, a first surface that is one of the valve seat surface and the sitting surface has a surface hardness higher than a surface hardness of a second surface that is the other one of the valve seat surface and the sitting surface, and a groove is formed in a member having the first surface so as to surround the first surface.
2 . The fluid control valve according to claim 1 , wherein the first surface has an area larger than an area of the second surface.
3 . The fluid control valve according to claim 1 , wherein the first surface is the sitting surface, and the second surface is the valve seat surface.
4 . The fluid control valve according to claim 3 , further comprising a driving mechanism that includes a driving member that comes into contact with the valve plug and that drives the valve plug, wherein the valve plug has the sitting surface and a driving force acting surface that comes into contact with the driving member, and the driving force acting surface has a surface hardness higher than a surface hardness of a contact surface of the driving member, the contact surface coming into contact with the valve plug.
5 . The fluid control valve according to claim 3 , wherein the valve plug has a groove provided adjacently to the sitting surface.
6 . A fluid control device comprising: the fluid control valve according to claim 1 ; a fluid sensor that measures a flow rate or a pressure of a fluid; and a control unit that controls a degree by which the fluid control valve is opened, based on a measurement measured by the fluid sensor, and based on a setting.
7 . A method of manufacturing a fluid control valve including a valve seat having a valve seat surface that is flat and a valve plug having a sitting surface that is flat and that sits on the valve seat surface, wherein the valve seat and the valve plug are both made of metal, the method comprising: forming a groove so as to surround one of the valve seat surface and the sitting surface; and applying burnishing processing to the one of the valve seat surface and the sitting surface that is surrounded by the groove, so as to make a surface hardness of the one of the valve seat surface and the sitting surface higher than a surface hardness of the other one of the valve seat surface and the sitting surface.

Description

TECHNICAL FIELD The present invention relates to a fluid control valve, a fluid control device, and a method of manufacturing a fluid control valve. BACKGROUND ART Conventionally, as disclosed in Patent Literature 1, there has been some fluid control valve that controls a fluid by causing a flat sitting surface to sit and to separate from a flat valve seat surface. However, such a fluid control valve suffers from seat leakage (leakage while the valve is fully closed), as a result of long-term use. Some causes of such seat leakage include the sitting surface or the valve seat surface becoming damaged and deteriorated as a result of the sitting surface and the valve seat surface coming into uneven contact with each other repeatedly, or corrosion causing the valve seat surface or the sitting surface to roughen. CITATION LIST Patent Literature Patent Literature 1: JP 2000-322129 A SUMMARY OF INVENTION Technical Problem Therefore, the present invention has been made in consideration of the problem described above, and a main object of the present invention is to improve the sealability of the fluid control valve. Solution to Problem That is, a fluid control valve according to the present invention includes: a valve seat having a valve seat surface that is flat and a valve plug having a sitting surface that is flat and that sits on the valve seat surface, in which a first surface that is one of the valve seat surface and the sitting surface has a surface hardness higher than a surface hardness of a second surface that is the other one of the valve seat surface and the sitting surface. In such a fluid control valve, because the first surface that is one of the valve seat surface and the sitting surface has a surface hardness higher than a surface hardness of the second surface which is the other one of the valve seat surface and the sitting surface, a hardness difference is ensured between the valve seat surface and the sitting surface so that the sealability can be improved. In addition, because the flat sitting surface is seated on the flat valve seat surface, a variation in the contact position between the sitting surface and the valve seat surface can be tolerated, and therefore, the sealability can be improved. Furthermore, because both of the valve seat surface and the sitting surface are flat, surface hardening processing for enhancing the hardness (e.g., burnishing processing) can be easily applied to one of the valve seat surface and the sitting surface. The burnishing processing is processing for increasing the surface hardness by pressing a tool (burnishing tool) made of a highly hard material against a workpiece having a rough surface resultant of cutting processing, to smooth out the surface of the workpiece by plastic deformation. Preferably, the first surface has an area larger than an area of the second surface. In other words, the first surface with a larger area has a surface hardness higher than that of the second surface with a smaller area. This is because the first surface having a larger area is more likely to become damaged, as a result of an edge of the second surface with a smaller area coming into contact therewith, for example. Because the valve plug is a movable member driven by a driving mechanism, the sitting surface comes into contact with a position offset from the valve seat surface that is fixed. At this time, from the viewpoint of improving the durability of the valve plug, it is desirable to provide the sitting surface with a surface hardness higher than a surface hardness of the valve seat surface. For this reason, the first surface is preferably the sitting surface, and the second surface is preferably the valve seat surface. Furthermore, the fluid control device according to the present invention includes a driving mechanism having a driving member that comes into contact with the valve plug and drives the valve plug. The valve plug preferably has the sitting surface and a driving force acting surface that comes into contact with the driving member, and a surface hardness of the driving force acting surface is preferably higher than a surface hardness of the contact surface of the driving member that comes into contact with the valve plug. Preferably, the valve plug has a groove provided adjacently to the sitting surface. As the sitting surface of the valve plug is subjected to the burnishing processing, extra material is formed as a result of being pushed in the burnishing processing. With this extra material going into the groove provided adjacently to the sitting surface, it is possible to prevent the extra material from impairing the sealability. Furthermore, a fluid control device according to the present invention includes the fluid control valve described above; a fluid sensor that measures a flow rate or a pressure of a fluid; and a control unit that controls a degree by which the fluid control valve is opened, based on a measurement measured by the fluid sensor, and