JP2006177527A - Air directional control valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air directional control valve capable of maintaining smooth operation without intervening lubricating oil. <P>SOLUTION: The air directional control valve is provided with a spool 11 and a housing 15 slidably fitted with each other. In the air directional control valve to change the air flow direction by moving the spool 11, a DLC coating film 20 composed of amorphous structure mainly made of carbon is applied on the surface of a land part 12 of the spool 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of an air switching valve used in a power transmission mechanism of various machines.

In general, an air switching valve is configured by a spool and a valve housing that are slidably fitted to each other, and the air flow direction is switched by moving the spool in the axial direction (see Patent Document 1).
Japanese Patent Laid-Open No. 10-002308

  However, in the conventional air switching valve, it is necessary to interpose lubricating oil in order to prevent wear of the sliding contact portion of the spool and the valve housing.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an air switching valve that can maintain a smooth operation without interposing lubricating oil.

  The present invention is applied to an air switching valve that includes a spool and a valve housing that are slidably fitted to each other, and that moves the spool to switch the direction of air flow.

  A DLC coating film made of an amorphous structure mainly composed of carbon is formed on at least one of the surfaces of the spool and the valve housing that are in sliding contact with each other.

  According to the present invention, the air switching valve has a structure in which a high-hardness DLC coating film is formed on at least one of the surfaces of the spool and the valve housing that are in sliding contact with each other. The frictional force acting on the sliding contact portion is reduced, the driving force for moving the spool in the axial direction is reduced, the wear of the spool and the valve housing is reduced, and the life of the air switching valve is extended. And it becomes possible to make the clearance between a spool and a valve housing small, and to reduce the air leak between each port.

  Further, since the air switching valve can ensure smooth operability without supplying lubricating oil, it can be operated in an oil-free state, and maintenance can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the air switching valve 10 includes a spool 11 and a valve housing 15 that are slidably fitted to each other, and moves the spool 11 to switch the air flow direction.

  A housing hole 16 is formed in the valve housing 15. On the other hand, the cylindrical spool 11 has four land portions 12 formed on the outer periphery thereof, and each land portion 12 is slidably inserted into the housing hole 16.

  Three ports 17, 18, 19 are formed in the valve housing 15, and pipes (not shown) are connected to the ports 17, 18, 19. The spool 11 is moved in the axial direction by a drive mechanism (not shown), and is switched between a position where the ports 17 and 18 are communicated as shown and a position where the spool 11 is moved to the left side and the ports 18 and 19 are communicated. The flow direction of air guided through the pipe is switched.

  As a gist of the present invention, a DLC coating film 20 made of an amorphous structure mainly composed of carbon is formed on the surface of the land portion 12 of the spool 11. The thickness of the DLC coating film 20 is a dimension of about several μm or less, for example.

  The DLC coating film 20 is formed by an unbalanced magnetron sputtering method (hereinafter referred to as “UBM sputtering method”).

  As shown in FIG. 3, the principle of sputtering is that a plasma is formed by glow discharge between an anode and a target 41 in a vacuum into which an inert gas such as argon is introduced. The atoms of the target 41 are blown off by being collided with each other, and the atoms are deposited on the work (spool 11) 21 arranged to face the target 41 to form a film.

  In the UBM sputtering method, magnetic fields 42 and 43 having different magnetic characteristics in the central portion and the peripheral portion of the target 41 are arranged in the sputter evaporation sources 40a to 40d, and one of the lines of magnetic force generated by the strong magnetic field 42 while forming plasma. When the part reaches the vicinity of the workpiece 21 and a bias voltage is applied to the workpiece 21, the substance constituting the target material 41 is deposited on the workpiece 21.

  FIG. 4 shows a basic configuration of the UBM sputtering apparatus 50. Four sputter evaporation sources 40 a to 40 d are provided in the vacuum chamber 51, the work 21 is placed on a self-revolving work table 56 disposed at the center thereof, and the work 21 is coated. A flat target as a film material is attached to the sputter evaporation sources 40a to 40d. The vacuum chamber 51 is filled with a predetermined amount of an inert gas such as argon and a hydrocarbon gas such as methane gas.

  Sputter evaporation sources 40a and 40c use graphite as a target, and sputter evaporation sources 40b and 40d use metal as a target.

  As shown in FIG. 2, the DLC coating film 20 has a nickel plating layer 61 formed on the surface of the stainless steel workpiece 21, and a bond layer 62, an intermediate layer 63, and a top layer 64 are sequentially laminated on the surface of the nickel plating layer 61. Formed.

  FIG. 5 shows how the target output changes when the DLC coating film 20 is formed.

  The bond layer 62 is formed as a metal film by sputtering only the metal targets 40b and 40d. In forming the bond layer 62, as shown in FIG. 5, the metal target output of the sputter evaporation sources 40b and 40d is set to 100%, and the graphite target output of the sputter evaporation sources 40a and 40c is kept constant at 0%. Sputtering is performed for a predetermined time.

  The intermediate layer 63 is formed as a gradient composition film of metal and carbon by simultaneously sputtering the metal target of the sputter evaporation sources 40b and 40d and the graphite target of the sputter evaporation sources 40a and 40c, and gradually changing the target output. In forming the intermediate layer 63, as shown in FIG. 5, the metal target output of the sputter evaporation sources 40b and 40d is temporarily reduced from 100%, while the graphite target output of the sputter evaporation sources 40a and 40c is reduced to 0. Sputtering is performed for a predetermined time with a primary increase from%.

  The top layer 64 simultaneously sputters the metal target of the sputter evaporation sources 40b and 40d and the graphite target of the sputter evaporation sources 40a and 40c to make the target output substantially constant, and the sputter evaporation sources 40b and 40d and the sputter evaporation source 40a. , 40c, sputtering is performed for a predetermined time while keeping the sputtering rate of the graphite target within a predetermined range.

  In forming the top layer 64, as shown in FIG. 5, the metal target output of the sputter evaporation sources 40b and 40d is about 10%, and the graphite target output of the sputter evaporation sources 40a and 40c is kept constant at about 90%. The ratio of the metal contained in the top layer 64 is set in the range of 3 to 18%. More desirably, the ratio of the metal contained in the top layer 64 is set in the range of 3 to 12%.

  Next, the operation will be described.

  After forming the nickel plating layer 61 on the surface of the work 21 made of stainless steel, the bond strength of the DLC coating film 20 with respect to the base material can be increased by providing the bond layer 62 with a metal ratio of 100%.

  An intermediate layer 63 made of a gradient composition film of metal and carbon that gradually reduces the metal ratio is provided on the bond layer 62 having a metal ratio of 100%, and a top layer 64 mainly composed of carbon is formed on the intermediate layer 63. By providing, the bonding strength of the top layer 64 in the DLC coating film 20 can be increased.

  By setting the metal ratio of the top layer 64 in the range of 3 to 18%, the adhesion and toughness of the top layer 64 can be improved, and cracking or peeling occurs when the workpiece 21 is deformed by a high load. Can be prevented. And the fall of the hardness of the top layer 64 can be suppressed and abrasion resistance can be ensured.

  As shown in FIG. 6, the relationship between the ratio of the metal contained in the top layer 64 and the toughness and hardness increases the toughness and hardness of the top layer 64 by setting the metal ratio in the range of 3 to 18%. It is done. Furthermore, by setting the ratio of the metal contained in the top layer 64 within a range of 3 to 12%, both the toughness and hardness of the top layer 64 can be remarkably increased.

  On the other hand, conventionally, since the ratio of the metal contained in the top layer was 0%, there was a problem that adhesion and toughness were insufficient, and the top layer was likely to be cracked or peeled off.

  As a result, even if the DLC coating film 20 is formed on the surface of the workpiece 21 that receives a high load, the DLC coating film 20 is prevented from being cracked or peeled off, and can be put to practical use.

  Due to the structure in which the hard DLC coating film 20 is formed on the surface of each land portion 12 of the spool 11, the friction force acting on the sliding contact portion with the valve housing 15 is reduced by the smooth DLC coating film 20 having a low friction coefficient. The driving force for moving the spool 11 in the axial direction is reduced, wear of the spool 11 and the housing hole 16 is reduced, and the life of the air switching valve 10 is extended. And it becomes possible to make the clearance of each land part 12 and the housing hole 16 small, and the air leak between each port 17,18,19 can be reduced.

  Furthermore, the air switching valve 10 can be operated in an oil-free state since smooth operability is ensured without supplying lubricating oil. As a result, the spool 11 can avoid the scattering of the lubricating oil or the generation of dust from the lubricating oil, and can cope with, for example, a clean room.

  As another embodiment, the DLC coating film 20 may be formed on the surface of the housing hole 16 of the valve housing 15, and the same effect can be obtained.

  Further, the DLC coating film 20 may be formed on both surfaces of the land portion 12 of the spool 11 and the housing hole 16 of the valve housing 15, and the same effect can be obtained.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The present invention can be used for various air switching valves such as an on-off valve, a flow control valve, and a direction switching valve.

The side view which shows embodiment of this invention and is an air switching valve. Sectional drawing of a DLC coating film similarly. Explanatory drawing which similarly shows the principle of a sputtering method. The block diagram of a UBM sputtering device similarly. The characteristic view which shows a mode that a target output similarly changes. The characteristic view which shows the relationship between the ratio of the metal contained in a top layer, toughness, and hardness similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Air switching valve 11 Spool 12 Land 15 Valve housing 16 Housing hole 20 DLC coating film 21 Work 40a-40d Sputter evaporation source 50 UBM sputtering apparatus 61 Plating layer 62 Bond layer 63 Intermediate layer 64 Top layer

Claims (3)

In an air switching valve that includes a spool and a valve housing that are slidably fitted to each other and moves the spool to switch the direction of air flow.
An air switching valve, wherein a DLC coating film made of an amorphous structure mainly composed of carbon is formed on at least one of the surfaces of the spool and the valve housing which are in sliding contact with each other.   The air switching valve according to claim 1, wherein a nickel plating layer is formed on the surface, and the DLC coating film is formed on the surface of the nickel plating layer.   The DLC coating film forms a bond layer by sputtering only a metal target on the surface, and forms an intermediate layer by simultaneously sputtering a metal target and a graphite target on the bond layer and gradually changing the target output. 2. A top layer having a metal ratio in the range of 3 to 18% is formed on the intermediate layer by simultaneously sputtering a metal target and a graphite target and making the target output substantially constant. Or the air switching valve of 2.

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