CN117157462A

CN117157462A - Surface processing structure, surface processing sheet and propeller fan

Info

Publication number: CN117157462A
Application number: CN202280028621.3A
Authority: CN
Inventors: 公文由衣; 三角胜
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2021-04-16
Filing date: 2022-03-22
Publication date: 2023-12-01
Also published as: CN117203433A

Abstract

The surface processing structure includes a plurality of blocks which are three-dimensional objects disposed on a surface of an object, that is, an object surface, and are arranged in a first direction parallel to the object surface. Each of the plurality of blocks has an inclined surface that extends so as to gradually increase in distance from the object surface from an upstream side toward a downstream side in the first direction. The plurality of inclined surfaces of the plurality of blocks are arranged on a line extending in the first direction. The plurality of blocks each have a plurality of fine grooves provided on the inclined surface. The plurality of fine grooves are arranged in a second direction orthogonal to the first direction at intervals therebetween, and extend from an upstream side toward a downstream side of the first direction. The plurality of fine grooves extend at the same depth from an upstream side end portion to a downstream side end portion of the inclined surface in the first direction.

Description

Surface processing structure, surface processing sheet and propeller fan

Technical Field

The present disclosure relates to a surface finish structure, a surface finish piece, and a propeller fan. The present application claims priority based on japanese patent application No. 2021-69498, 4 months, 16 days of 2021, and japanese patent application No. 2022-18395, 9 months, 2022, which are incorporated herein by reference.

Background

In recent years, a technology that mimics various functions of living things, so-called biology (biology), has been attracting attention. As an example of the use of such a bionic technique in the manufacture of electric products and the like, natural technology (nature technology) (registered trademark) is known.

As a method of machining the surface of a rotatable blade, pit machining is known. In a device using blades that rotate by receiving a fluid such as wind or flowing water, as in the generator described in patent document 1, by providing dimples in the rotating blades, the surface area of the blades can be increased, the resistance to wind can be increased, and the rotation of the blades can be improved.

Prior art literature

Patent literature

Patent document 1 Japanese patent laid-open publication No. 2003-3945

Disclosure of Invention

The invention aims to solve the technical problems

However, in a device that moves a fluid by rotation of a blade that receives power of a motor, such as a blower fan or a fan, if a pit is provided in the rotating blade, the fluid may not be moved efficiently. Specifically, the surface area of the blade increases due to the pits, and the resistance of the fluid increases, so that the rotational load of the blade increases, which may prevent smooth rotation of the blade. In addition, as the blades rotate, the pits create turbulence at the surface of the blades that may prevent the fluid from moving in a certain direction.

An object of an aspect of the present disclosure is to provide a surface processing structure, a surface processing sheet, and a propeller fan capable of moving a fluid efficiently. Further, the present disclosure is related to biology because it includes a technical idea focusing on the structure of the scale powder and the scale.

Technical scheme for solving technical problems

The surface processing structure according to an aspect of the present disclosure includes a plurality of blocks which are three-dimensional objects disposed on a surface of an object, that is, an object surface, and which are arranged in a first direction parallel to the object surface, each of the plurality of blocks having an inclined surface extending so as to gradually increase in distance from the object surface from an upstream side toward a downstream side of the first direction, the plurality of inclined surfaces of the plurality of blocks being arranged on a line extending in the first direction, each of the plurality of blocks having a plurality of fine grooves provided on the inclined surface, the plurality of fine grooves being arranged in a second direction orthogonal to the first direction at intervals from each other and extending from the upstream side toward the downstream side of the first direction, the plurality of fine grooves extending at the same depth from an upstream side end portion to a downstream side end portion of the inclined surface in the first direction.

A surface processing structure according to an aspect of the present disclosure includes a plurality of blocks which are three-dimensional objects disposed on a surface of an object, that is, an object surface, and which are arranged in a first direction parallel to the object surface and a second direction orthogonal to the first direction, each of the plurality of blocks having an inclined surface which extends so as to gradually increase in distance from the object surface from an upstream side toward a downstream side of the first direction, the plurality of inclined surfaces of the plurality of blocks being arranged on one line extending in the first direction, each of the plurality of blocks having a plurality of fine grooves which are disposed in the inclined surface, the plurality of fine grooves being arranged at intervals in the second direction and extending from an upstream side to a downstream side of the first direction, a groove-like gap which extends in the first direction being formed between two blocks adjacent in the second direction, each of the plurality of grooves having a width smaller than that of the second direction, the plurality of grooves being disposed alternately in the first direction, and the plurality of fluid flow paths being disposed in the fine direction.

In the surface processing sheet according to one aspect of the present disclosure, the surface processing structure is provided on a substrate that can be provided on the target surface.

A propeller fan according to an aspect of the present disclosure includes: a rotating shaft portion; and a blade extending outward from the rotation shaft portion, the surface processing structure being provided on a surface of the blade, the first direction being parallel to a direction from a front edge side toward a rear edge side of the blade.

Drawings

Fig. 1 is a partially exploded side view of a fan machine having a propeller fan.

Fig. 2 is a perspective view of the propeller fan from the front side.

Fig. 3 is a front view of the propeller fan.

Fig. 4A is a sectional view of the B-B line of fig. 3 in a view direction.

Fig. 4B is a view partially enlarged of the front surface of the blade.

Fig. 5 is a partially enlarged perspective view of the surface-treated sheet.

Fig. 6 is a partially enlarged perspective view of the broken line box shown in fig. 5.

Fig. 7A is an enlarged perspective view of one block.

Fig. 7B is a partially enlarged perspective view of the broken line box shown in fig. 6.

Fig. 8 is a schematic top view partially enlarged of a surfacing sheet.

Fig. 9A is a schematic front view of the surfacing sheet shown in fig. 8.

Fig. 9B is a schematic side view of the surfacing sheet shown in fig. 8.

Fig. 10A is a perspective view of the surface-treated sheet of example 1.

Fig. 10B is a table showing the relationship between the surface-treated sheet and the object flow in example 1.

Fig. 10C is a table showing the dimensions of the surface-treated sheet of example 1.

Fig. 10D is a front view of the surface-treated sheet of example 1.

Fig. 10E is a side view of the surfacing sheet of example 1.

Fig. 11A is a perspective view of the surface-treated sheet of example 2.

Fig. 11B is a table showing the relationship between the surface chips and the object flow in examples 2 and 3.

Fig. 11C is a table showing the dimensions of the surface-treated sheet of examples 2 and 3.

Fig. 12A is a perspective view of the surface-treated sheet of example 3.

Fig. 12B is a front view of the surface-treated sheet of example 3.

Fig. 12C is an enlarged perspective view of the block of embodiment 3 as seen from the downstream side.

Fig. 13A is a schematic side view of a surface-treated sheet of the first modification.

Fig. 13B is a schematic side view of a surface-treated sheet of the second modification.

Fig. 13C is a schematic side view of a surface-treated sheet of the third modification.

Fig. 13D is a schematic side view of a surface-treated sheet of the fourth modification.

Fig. 13E is a schematic side view of a surface-treated sheet of the fifth modification.

Fig. 13F is a schematic side view of a surface-treated sheet of the sixth modification.

Fig. 14A is a schematic plan view of a surface-treated sheet of the seventh modification.

Fig. 14B is a schematic plan view of a surface-treated sheet of the eighth modification.

Fig. 14C is a schematic plan view of a surface-finished sheet of the ninth modification.

Fig. 14D is a schematic plan view of a surface-treated sheet of the tenth modification.

Fig. 15A is a schematic plan view of a surface-treated sheet of the eleventh modification.

Fig. 15B is a schematic front view of a surface-finished sheet of the eleventh modification.

Detailed Description

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and repetitive description thereof will be omitted.

[ Fan 1]

The fan 1 will be described. Fig. 1 is a partially exploded side view of a fan 1 provided with a propeller fan 100. As shown in fig. 1, the fan 1 includes a front shroud 2, a rear shroud 3, a main body 4, a bracket 5, and a propeller fan 100. The main body 4 is supported by a bracket 5, and accommodates a drive motor, not shown. A rotary shaft 4A of a drive motor is provided on the front surface of the main body 4. The rotating shaft 110 (see fig. 2, etc.) of the propeller fan 100 is fixed to the rotating shaft 4A using the screw cover 6.

The front guard 2 and the rear guard 3 are provided so as to surround the propeller fan 100 fixed to the main body 4. The backplate 3 is fixed to the main body 4 so as to cover the back surface side (negative pressure surface side) of the propeller fan 100. The front cover 2 is fixed to the rear cover 3 so as to cover the front side (positive pressure side) of the propeller fan 100. The bracket 5 is provided for mounting the fan 1 on the ground or the like, and supports the main body 4. An unshown operation unit for switching on/off of the fan 1, the operation state, and the like is provided at a predetermined position of the bracket 5. The stand 5 may also have a tilting function and a height adjusting function of the fan 1.

[ Propeller fan 100]

Propeller fan 100 is described. Fig. 2 is a perspective view of the propeller fan 100 from the front side. Fig. 3 is a front view of propeller fan 100. As shown in fig. 2 and 3, the propeller fan 100 includes a rotation shaft 110 and a plurality of blades 120. The rotation shaft portion 110 is a hub of the propeller fan 100, and has a substantially cylindrical shape with a bottom. The plurality of blades 120 are respectively smoothly curved plate-like. The plurality of blades 120 protrude from the outer peripheral surface of the rotation shaft portion 110 toward the radial outside of the propeller fan 100. The plurality of blades 120 are arranged at equal intervals along the circumferential direction of the rotation shaft portion 110 and have the same shape as each other. The propeller fan 100 of this example has 7 blades 120.

The propeller fan 100 is driven by the drive motor, and rotates in a counterclockwise direction, i.e., in a rotation direction a when viewed from the front, with the axis of the rotation shaft 110 as the rotation center. That is, the plurality of blades 120 rotates in the rotation direction a. Thereby, air flows from the suction side, which is the back side of the propeller fan 100, toward the discharge side, which is the front side of the propeller fan 100, and is blown toward the front of the fan 1.

A detailed structure of the plurality of blades 120 is described. Fig. 4A is a sectional view of the B-B line of fig. 3 in a view direction. Fig. 4B is a partially enlarged view of the front surface 125 of the blade 120. In this example, since the plurality of blades 120 have the same shape, one blade 120 will be described. As shown in fig. 2 to 4A, the blade 120 includes a leading edge 121, a trailing edge 122, and a peripheral edge 123.

The leading edge 121 is an end edge located downstream in the rotational direction a of the blade 120. The leading edge 121 is curved such that a radially intermediate portion thereof protrudes upstream in the rotational direction a. The trailing edge 122 is an end edge located upstream of the rotation direction a of the blade 120. The trailing edge 122 is curved such that a radially intermediate portion thereof protrudes upstream in the rotational direction a. The peripheral edge 123 is an end edge extending in the rotational direction a on the blade 120. The peripheral edge 123 connects the radially outer end of the leading edge 121 and the radially outer end of the trailing edge 122. As the entire blade 120 is directed radially outward, the distance between the leading edge 121 and the trailing edge 122 increases.

By rotating the propeller fan 100 in the rotation direction a, in the blades 120, the airflow flows from the front edge 121 toward the rear edge 122. The front surface 125 of the blade 120 is a positive pressure surface curved in a concave shape. The back surface 126 of the vane 120 is a negative pressure surface curved in a convex shape. In the above-described configuration, when the propeller fan 100 rotates, air flowing from the leading edge 121 to the blade surface of the blade 120 flows substantially in the circumferential direction from the leading edge 121 and flows out from the trailing edge 122.

In propeller fan 100, surface finish pieces 200 are provided on the blade surfaces, i.e., front surface 125 and back surface 126, of blades 120. In this example, the surface finish 200 is attached to substantially the entire surface of the front surface 125 and substantially the entire surface of the back surface 126. Alternatively, the surfacing sheet 200 may be disposed on one of the front surface 125 and the back surface 126. The surfacing sheet 200 may be provided on a portion of the front surface 125 or on a portion of the back surface 126.

As shown in fig. 4B, the surfacing sheet 200 is attached in surface contact with the front surface 125 of the blade 120 and extends along the front surface 125. In this example, the direction from the front edge 121 side toward the rear edge 122 side, that is, the direction in which air flows relatively to the rotating blades 120 corresponds to a first direction described later. The radial direction of the blade 120 corresponds to a second direction described later.

[ surface-finished sheet 200]

The surfacing sheet 200 will be described. Fig. 5 is a partially enlarged perspective view of the surfacing sheet 200. Fig. 6 is a partially enlarged perspective view of the inside of the dashed box shown in fig. 5. Hereinafter, the upper side, lower left side, upper right side, upper left side, lower right side in fig. 5 are defined as the upper side, lower side, front side, rear side, left side, right side of the surface processing sheet 200, respectively. The example of fig. 5 is a part of the surface-treated sheet 200, which is 2mm in the front-rear direction and 2mm in the left-right direction. In fig. 6, only one block 500 located at the left front side among the plurality of blocks 500 illustrates the fine groove 520.

As shown in fig. 5 and 6, in the surface processing sheet 200, a surface processing structure 201 is provided on a base 202 that can be provided on the surface of an object, that is, the target surface. Hereinafter, in order to describe the surface processing sheet 200 provided on the front surface 125 of the blade 120, the blade 120 is an object, and the front surface 125 is an object surface.

The surface-treated sheet 200 of this example is a thin, lightweight, flexible sheet. Specifically, the thickness of the surface-treated sheet 200 is less than 2000 μm, and is about 100 μm as an example. The base 202 may be formed of a material that can be fixed to the target surface by adhesion or fusion, and includes, for example, at least 1 selected from the group consisting of a resin, a rubber, and a metal. The resin contains, for example, at least one selected from the group consisting of polypropylene (PP), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), acrylonitrile-butadiene-styrene (ABS), and polyurethane. The rubber includes, for example, silicone rubber. The metal includes, for example, at least 1 selected from the group consisting of aluminum and stainless steel. The base material 202 has flexibility capable of being deformed in a shape matching with the surface of the object surface, and thus can be in contact with the surface of the object surface without gaps.

The surfacing structure 201 has a plurality of blocks 500. The plurality of blocks 500 are three-dimensional objects arranged on the surface of the object, that is, the object surface, and are arranged in a first direction parallel to the object surface. The first direction may be a straight line direction or a curved line direction. In this example, a surfacing structure 201 is formed on a substrate 202. The plurality of blocks 500 are arranged on the target surface with the base 202 interposed therebetween. The front-rear, left-right direction of the surface processing sheet 200 is substantially parallel to the surface direction of the target surface. The upper side of the surface processing sheet 200 faces the opposite side to the target surface. The underside of the surfacing sheet 200 faces the object surface side.

The plurality of blocks 500 constitute a plurality of block columns 501. Each of the plurality of block rows 501 is composed of two or more blocks 500 arranged in the first direction. The plurality of block rows 501 are arranged in a second direction orthogonal to the first direction. The second direction may be a straight line direction or a curved line direction. Thus, the plurality of blocks 500 are arranged in a two-dimensional arrangement along the first direction and the second direction on the substrate 202.

In the propeller fan 100, the front surface 125 of the blade 120 is mounted such that the front side of the surface processing sheet 200 faces the front edge 121 side and the rear side of the surface processing sheet 200 faces the front edge 121 side. Therefore, as shown in fig. 5, the rear direction of the surface processing sheet 200 is parallel to the first direction (see fig. 4B). The left-right direction of the surfacing sheet 200 is parallel to the second direction.

As shown in fig. 4A, the blade surface of the blade 120 of this example is curved from the front edge 121 side toward the rear edge 122 side toward the front side of the blade 120. Accordingly, as shown in fig. 4B and 5, the upper and lower directions of the surface processing sheet 200 are inclined with respect to the front and rear directions of the blade 120, respectively. Specifically, the upward direction of the surface processing sheet 200 is inclined to the upstream side in the first direction with respect to the front direction of the blade 120.

As shown in fig. 6, each of the plurality of blocks 500 has an inclined surface 510 extending so that the distance from the target surface gradually increases from the upstream side toward the downstream side in the first direction. The inclined surface 510 is at least a part of the surface of the block 500 facing upward. In this example, the entire upper surface of the block 500 forms an inclined surface 510 inclined toward the rear and upward.

The plurality of blocks 500 have a plurality of inclined surfaces 510 arranged on one line V extending in the first direction. Specifically, one line V extending in the first direction among the blocks of the plurality of block rows 501 passes through the inclined surfaces 510 of all the blocks 500 constituting the block rows 501 in a plan view. The line V is an imaginary straight line or curve extending parallel to the first direction. In the example of fig. 6, a line V extending straight rearward passes through all blocks 500 in the block row 501 in a plan view.

A detailed structure of the plurality of blocks 500 is described. Fig. 7A is an enlarged perspective view of one block 500. Fig. 7B is a partially enlarged perspective view of the inside of the dashed box shown in fig. 6. In fig. 7A, the fine groove 520 provided in the block 500 is not shown.

The plurality of blocks 500 may be made of a material that can be formed on the base material 202, and may be made of the same material as the base material 202 or a material different from the base material 202. The plurality of blocks 500 may be manufactured by molding such as injection molding, or may be manufactured by removing processing such as milling, laser processing, etching, or the like. In this example, the upper surface of the base 202 is etched to perform micromachining, and a plurality of blocks 500 having the same shape are produced. Hereinafter, one block 500 will be described.

The inclined surface 510 has a function of generating an air flow flowing in a first direction by contacting with air flowing into the front surface 125 when the blade 120 rotates. In the example of fig. 7A, the block 500 has a rectangular parallelepiped shape longer in the first direction so that the inclined surface 510 can guide air in the first direction over a longer distance. The inclined surface 510 is a flat surface inclined so as to be higher toward the downstream side in the first direction.

The inclined surface 510 has a relatively large area so as to be able to sufficiently contact with the air flowing into the front surface 125. In the case of the surface-processed sheet 200 in plan view, the ratio of the total area of the plurality of inclined surfaces 510 in the surface-processed sheet 200 is, for example, 60% or more of the entire surface. In this example, the length of the inclined surface 510 in the first direction is equal to the depth D, which is the length of the block 500 in the first direction. The length of the inclined surface 510 in the second direction is equal to the length of the block 500 in the second direction. The length of the block 500 in the second direction is equal to a groove interval G2 of a block gap 550 described later. The groove interval G2 is a distance between two block gaps 550 adjacent to each other.

The inclined surface 510 includes an upstream side end portion 511 and a downstream side end portion 512 in the first direction. In the example of fig. 7A, the inclined surface 510 is a plane inclined linearly from an upstream side end 511 located at the front end of the inclined surface 510 to a downstream side end 512 located at the rear end of the inclined surface 510. Therefore, the height H2 of the inclined surface 510 becomes the minimum value Hmin at the upstream end 511 and becomes the maximum value Hmax at the downstream end 512. That is, the distance from the target surface to the inclined surface 510 is smallest at the upstream end 511 and largest at the downstream end 512.

The height H2 of the inclined surface 510 is equal to the height of the block 500. The smaller the height H2 of the upstream-side end 511, the smaller the contact area of the air flowing into the block 500 from the upstream side in the first direction with the front surface 521 of the block 500. In this example, since the height H2 of the upstream end 511 is the minimum value Hmin, the contact area can be suppressed and air can smoothly move onto the inclined surface 510.

In the block 500, the inclination angle α of the inclined surface 510 with respect to the target surface is determined by the height difference and the depth D of the inclined surface 510. The larger the inclination angle α is, the more the air moving on the inclined surface 510 can be moved to a position higher from the target surface, and on the other hand, the contact pressure between the air and the inclined surface 510 becomes large, and the flow velocity of the air may be reduced. The smaller the inclination angle α is, the more the flow velocity of the air moving on the inclined surface 510 can be suppressed from decreasing, and on the other hand, the air may not be moved to a position higher from the target surface. From this point of view, the inclination angle α is in the range of 6 degrees to 27 degrees.

The size and shape of the inclined surface 510 are not limited to the above examples. For example, the inclination angle α is not limited to the above-described range of 6 degrees to 27 degrees, and may be at least greater than 0 degrees and less than 45 degrees.

As shown in fig. 7B, each of the plurality of blocks 500 has a plurality of fine grooves 520 provided on the inclined surface 510. In other words, the upper surface of each block 500 includes a plurality of fine grooves 520. The plurality of fine grooves 520 are arranged at intervals in a second direction orthogonal to the first direction, and extend from an upstream side toward a downstream side in the first direction. The plurality of fine grooves 520 have a function of forming an air layer formed by relatively slow air flow inside the fine grooves 520. As a result, air passing through the vicinity of the upper portion of the fine groove 520 can pass through the surface of the air layer formed inside the fine groove 520 so as to slide. That is, the plurality of fine grooves 520 are provided to reduce contact resistance applied to the air flow on the inclined surface 510 by suppressing the contact area between the air flowing along the inclined surface 510 and the inclined surface 510, and to smoothly flow the air flow.

In this example, the plurality of fine grooves 520 extend at the same depth from the upstream end 511 to the downstream end 512 of the inclined surface 510 in the first direction. A rail-shaped convex portion 530 extending in the first direction is formed between two adjacent ones of the plurality of fine grooves 520. In other words, the upper surface of each block 500 includes a plurality of protruding portions 530 provided between two adjacent fine grooves 520 among the plurality of fine grooves 520, respectively. Accordingly, the plurality of protrusions 530 and the plurality of fine grooves 520 are alternately arranged on the inclined surface 510. The air flowing into the inclined surface 510 flows along the upper surfaces of the plurality of convex parts 530 in the first direction. In this example, since the plurality of fine grooves 520 have the same shape, a single fine groove 520 will be described.

The length of the fine groove 520 in the second direction is the groove width W1. The smaller the groove width W1, the easier an air layer is formed inside the fine groove 520, while the accurate production of the fine groove 520 becomes difficult, and the contact area between the air and the inclined surface 510 becomes large. The larger the groove width W1 is, the more accurate the production of the fine groove 520 becomes, while it is difficult to form an air layer inside the fine groove 520, and air passing through the vicinity of the upper portion of the fine groove 520 easily flows in. When air flows into the interior of the fine groove 520, frictional resistance corresponding to the contact area of the air and the fine groove 520 is generated. From such a viewpoint, the groove width W1 of the fine groove 520 is in the range of 0.5 μm to 600 μm.

The length of the fine groove 520 in the up-down direction is a height H1. The smaller the height H1, the easier it is to accurately manufacture the fine groove 520, while the easier it is for air passing through the vicinity of the upper portion of the fine groove 520 to flow into the fine groove 520. The greater the height H1, the deeper the air layer in the fine groove 520 becomes, and the air layer is more easily formed, whereas if it is too deep, the air layer is formed at a deep position, the upper portion of the fine groove 520 becomes resistance, and it is difficult to accurately manufacture the fine groove 520. Further, when the height H1 is large, the height of the convex portion 530 with respect to the lateral width becomes large, and therefore the rigidity of the convex portion 530 becomes small, which may be easily deflected. When the convex portion 530 is deflected, there is a possibility that an air layer in the fine groove 520 is broken. From this viewpoint, the height H1 of the fine groove 520 is in the range of 0.5 μm to 300. Mu.m.

The groove gap G1 is a distance between two fine grooves 520 adjacent to each other, and is equal to the length of the convex portion 530 in the second direction. The larger the groove gap G1 is, the more accurate the formation of the plurality of fine grooves 520 becomes, while the number of fine grooves 520 that can be formed on the inclined surface 510 decreases, so that the contact resistance applied to the air flow on the inclined surface 510 increases. The smaller the groove gap G1, the larger the number of fine grooves 520 that can be formed on the inclined surface 510, and therefore the smaller the contact resistance applied to the air flow on the inclined surface 510, on the other hand, it is difficult to accurately manufacture the plurality of fine grooves 520. From such a viewpoint, the groove gap G1 of the fine groove 520 is in the range of 1 μm to 800 μm.

The number of the fine grooves 520, the groove width W1, the height H1, and the groove gap G1 are not limited to the above-described examples, and may be different from the above-described ranges. The plurality of fine grooves 520 are not limited to the form extending in the first direction over the entire range of the inclined surface 510, and may extend in the first direction at a portion between the upstream end portion 511 and the downstream end portion 512.

The arrangement of the plurality of blocks 500 is described. Fig. 8 is a partially enlarged schematic top view of the surfacing sheet 200. Fig. 9A is a schematic front view of the surfacing sheet 200 shown in fig. 8. Fig. 9B is a schematic side view of the surfacing sheet 200 shown in fig. 8. In the example of fig. 8, four block columns 501 are arranged in the second direction, and in each block column 501, four blocks 500 are arranged in the first direction.

In each of the plurality of blocks 500, the entirety of the inclined surface 510 is exposed on the upstream side of the block 500 in the first direction. Specifically, in the example of fig. 8 and 9B, two blocks 500 adjacent to each other in the first direction among the plurality of blocks 500 are an upstream block 500A and a downstream block 500B located downstream of the upstream block 500A. The entire inclined surface 510 of the downstream block 500B is not shielded from other members and is exposed when viewed from the rear surface 522 of the upstream block 500A.

The downstream end portion 512 of the inclined surface 510 in the first direction has the largest distance from the target surface in the block 500. That is, the downstream end portion 512 of the inclined surface 510 is located at the highest position in the block 500.

Further, the upstream end 511 of the inclined surface 510 in the downstream block 500B in the first direction is smaller in distance from the target surface than the downstream end 512 of the upstream block 500A in the first direction. That is, the upstream end 511 of the downstream block 500B is located at a lower position than the downstream end 512 of the upstream block 500A.

In each of the plurality of block rows 501, a groove-like gap 540 extending in a direction intersecting the first direction is formed between two blocks 500 adjacent in the first direction among the plurality of blocks 500. In the example of fig. 8 and 9B, a gap 540 extending in the second direction is formed between two blocks 500 adjacent to each other in the front-rear direction in each block row 501.

A groove-shaped block gap 550 extending in a direction intersecting the second direction is formed between two blocks 500 adjacent in the second direction among the plurality of blocks 500. In the example of fig. 8 and 9A, in two adjacent block rows 501, a block gap 550 extending in the first direction is formed between the block 500 of the block row 501 on the left side and the block 500 of the block row 501 on the right side.

Thus, among the plurality of blocks 500, two blocks 500 adjacent in the first direction are arranged with the gap 540 interposed therebetween, and two blocks 500 adjacent in the second direction are arranged with the block gap 550 interposed therebetween. In this way, since the plurality of blocks 500 are separated from each other, the plurality of blocks 500 can be accurately and easily manufactured on the base material 202, as compared with, for example, manufacturing by connecting the plurality of blocks 500 to each other.

As shown in fig. 9A, the length of the block gap 550 in the second direction is the groove width W2. The block gap 550 has a function of forming an air layer between two blocks 500 adjacent in the second direction. As a result, air passing through the vicinity of the upper portion of the block gap 550 can pass through the surface of the air layer formed in the block gap 550 so as to slide. That is, the block gap 550 is provided to reduce contact resistance applied to the air flow in the block gap 550 by suppressing the contact area between the air passing through the vicinity of the upper portion of the block gap 550 and the surface processing sheet 200, and to smoothly flow the air flow.

The smaller the groove width W2 is, the easier an air layer is formed in the block gap 550, while the more difficult it is to accurately manufacture the block gap 550, and the more difficult it is to manufacture the plurality of blocks 500 in the second direction. The larger the groove width W2, the easier it is to accurately manufacture the block gap 550, and the plurality of blocks 500 can be easily arranged in the second direction, while it is difficult to form an air layer in the block gap 550, and air passing through the vicinity of the upper portion of the block gap 550 can easily flow in. When air flows into the block gap 550, frictional resistance corresponding to the contact area of the air and the block gap 550 is generated. From such a viewpoint, the groove width W2 of the block gap 550 is in the range of 10 μm to 600 μm.

The groove width W1 in the second direction in each of the plurality of fine grooves 520 is smaller than the groove width W2 in the second direction in the block gap 550. Here, the flow rate of the air flowing into the surface processing sheet 200 varies depending on, for example, the rotational speed of the propeller fan 100. In the grooves such as the fine grooves 520 and the block gaps 550, the relationship between the flow rate of air toward the grooves and the width of the grooves affects whether or not an air layer can be effectively formed inside the grooves. If the air layer cannot be formed efficiently in the groove, air may flow into the groove, and the groove may become a resistance to the flow of air.

For example, the flow velocity width of the air flowing into the surface processing sheet 200 is divided into three of a low-speed region, a medium-speed region, and a high-speed region. In the case where the flow rate of the inflow air is in the low-speed region, the relatively wide block gap 550 can effectively form an air layer as compared with the relatively narrow fine groove 520. In the case where the flow rate of the inflow air is in the medium speed region, the block gap 550 and the fine groove 520 can effectively form an air layer. In the case where the flow rate of the inflow air is in the high-speed region, the fine groove 520 can effectively form an air layer as compared with the block gap 550. That is, even when the flow rate of the air flowing into the surface processing sheet 200 is in any one of the speed regions, an air layer can be effectively formed by at least one of the block gaps 550 and the fine grooves 520. With such a surface processing structure 201, a friction reducing effect can be exerted in a wide flow velocity region of the flowing air.

The ratio of the height H1 in the fine groove 520 to the groove width W1 is referred to as the aspect ratio of the fine groove 520. The ratio of the height H2 in the block gap 550 to the groove width W2 is referred to as the aspect ratio of the block gap 550. The aspect ratio of the block gap 550 effective in the low speed region may be smaller than the aspect ratio of the fine groove 520 effective in the high speed region. In this case, the surface area of the block gap 550 can be made relatively smaller than the surface area of the fine groove 520. Therefore, even in the high-speed region, when the air layer is not effectively formed in the block gap 550, the contact area with the air flowing into the block gap 550 can be suppressed, and the frictional resistance in the case where the block gap 550 becomes resistance can be suppressed.

In this example, the plurality of blocks 500 are configured to form a plurality of block gaps 550 that are continuously arranged in the first direction. The plurality of block gaps 550 form one fluid flow path extending in the first direction. Specifically, as shown in fig. 5 and 8, a plurality of blocks 500 are two-dimensionally arrayed in a lattice shape on the base 202. Accordingly, between two block rows 501 adjacent to each other, fluid flow paths in which a plurality of block gaps 550 are arranged continuously in the first direction are formed. The plurality of fine grooves 520 and the fluid flow path provided on the upper surface of the block 500 are alternately arranged in the second direction. The air flowing through the fluid flow path smoothly flows in the first direction without meandering.

As shown in fig. 9B, the length of the gap 540 in the first direction is the groove width W3. As will be described later, air flowing into the surface processing sheet 200 from the upstream side in the first direction continuously flows along the inclined surfaces 510 of the plurality of blocks 500 arranged in the first direction. The larger the groove width W3 is, the easier the plurality of blocks 500 are arranged in the first direction. However, when air flows from the inclined surface 510 of the upstream block 500A to the inclined surface 510 of the downstream block 500B, a part of the air flows into the gap 540, and the air volume of the air flow may be reduced.

On the other hand, the smaller the groove width W3, the higher the likelihood that blocks 500 adjacent to each other are connected in the first direction when manufacturing a plurality of blocks 500. However, even if the blocks 500 adjacent to each other are connected in the first direction, there is no great obstacle in the function of flowing air in the first direction. From such a viewpoint, the groove width W3 of the gap 540 is in the range of 300 μm or less.

The flow of air in the surfacing sheet 200 is illustrated. As described above, when the propeller fan 100 rotates in the rotation direction a, air relatively moving with respect to the rotating blades 120 flows onto the blade surfaces of the blades 120. At this time, air flows from the front edge 121 located downstream in the rotation direction a into the front surface 125 and the rear surface 126. The flow of air in the front surface 125 will be described below, but the flow of air in the back surface 126 is also similar.

As shown in fig. 8, as the blade 120 rotates, the surfacing sheet 200 also rotates in the rotation direction a. In this example, as described above, the upper direction of the front surface processed sheet 200 is inclined with respect to the upstream side, i.e., the front side, of the front surface direction first direction of the blade 120. Therefore, as shown in fig. 9B, the surface processing sheet 200 rotated in the rotation direction a moves upward toward the front side thereof. Accordingly, the air flowing into the front surface 125 relatively moves so as to approach the surface processing sheet 200 from above the front side.

In this case, the air moves from the upstream side to the downstream side in the first direction in the surface processing sheet 200 as follows. As shown in fig. 8, in the surface processing sheet 200, air directed to the surface processing sheet 200 is branched into a plurality of main flows ST1 and a plurality of sub-flows ST2. In the plurality of main streams ST1, most of the air flowing into the surfacing sheet 200 flows on the upper side of the plurality of blocks 500 occupying most of the surfacing sheet 200 in a plan view. In the plurality of sub-streams ST2, the remaining portion of the air flowing into the surface processing sheet 200 flows on both left and right sides of the plurality of blocks 500 in a plan view. Accordingly, on the upper side of the surface processing sheet 200, the air flowing in flows in the first direction so that the main flow ST1 and the sub-flow ST2 are alternately repeated and arranged in the left-right direction.

As shown in fig. 8 and 9B, the plurality of main streams ST1 are airflows formed corresponding to the plurality of block rows 501, respectively. In each of the plurality of main streams ST1, air flows from the upstream side to the downstream side in the first direction along the inclined surfaces 510 of the two or more blocks 500 constituting the corresponding block row 501. Specifically, when the air flows along the inclined surface 510 of the upstream block 500A, the air exits upward from the front surface 125 of the vane 120 as it moves downstream from the upstream end 511.

The inclined surface 510 of each block 500 is provided with the plurality of fine grooves 520. The inclined surface 510 has a small area on its outer surface, corresponding to the provision of the plurality of fine grooves 520. The outer surface of the inclined surface 510 is substantially constituted by the upper end surfaces of the plurality of convex portions 530. As described above, the groove width W1 of the plurality of fine grooves 520 is extremely narrow, and thus an air layer into which air is difficult to enter is formed inside. Accordingly, the air flowing on the inclined surface 510 substantially contacts only the outer surface of the inclined surface 510, and thus the contact area of the inclined surface 510 with the air is suppressed. The contact resistance applied to the airflow on the inclined surface 510 can be reduced, and the flow velocity of the main flow ST1 can be suppressed from being reduced.

Further, the air flows downstream beyond the downstream end portion 512 of the upstream block 500A, and moves onto the inclined surface 510 of the downstream block 500B. In this example, the entire inclined surface 510 of the downstream block 500B is exposed toward the upstream block 500A, and the downstream end portion 512 is highest in the upstream block 500A. The airflow continuously flowing on the upstream side block 500A and the downstream side block 500B generates airflow vortex E in the vicinity of the upper side of the upstream side end 511 of the downstream side block 500B due to the difference in height between the downstream side end 512 of the upstream side block 500A and the upstream side end 511 of the downstream side block 500B.

Thus, when the main flow ST1 flowing through the inclined surface 510 of the upstream block 500A exceeds the downstream end portion 512 of the upstream block 500A, the main flow ST1 flows so as to slide on the upper side of the airflow vortex E, and moves to the inclined surface 510 of the downstream block 500B. That is, the airflow vortex E suppresses the main flow ST1 from flowing into the gap 540 between the upstream block 500A and the downstream block 500B, and therefore can suppress contact resistance applied to the main flow ST 1.

In the present embodiment, the upstream end 511 of the downstream block 500B is spaced a smaller distance from the target surface than the downstream end 512 of the upstream block 500A. Therefore, the air flowing out from the downstream end portion 512 of the upstream block 500A does not interfere with the upstream end portion 511 of the downstream block 500B, and is likely to move toward the inclined surface 510 of the downstream block 500B. Further, since the gap 540 between the upstream block 500A and the downstream block 500B is extremely narrow, the air flowing from the upstream block 500A to the downstream block 500B can be suppressed from flowing into the gap 540.

In each block row 501, by repeating the above-described movement, the inclined surfaces 510 of two or more blocks 500 arranged in the first direction are continuously moved so as to jump up. The air does not move from the upstream end portion 511 to the downstream end portion 512 at each inclined surface 510, but moves from a position downstream of the upstream end portion 511 to the downstream end portion 512. Accordingly, the movement distance of the air on each inclined surface 510 in the first direction is suppressed, and thus the contact resistance applied to the air flow on the inclined surface 510 is further reduced.

In this way, in each block row 501, the contact resistance applied to the air flow on the inclined surface 510 is relatively small, and therefore the main flow ST1 smoothly flows in the first direction. When the main flow ST1 flows from the upstream block 500A to the downstream block 500B, the flow velocity is suppressed from decreasing due to the influence of the airflow vortex E. The plurality of main streams ST1 are suppressed from deviating from the first direction, and smoothly and stably flow.

As shown in fig. 8 and 9A, the plurality of sub-streams ST2 are air streams formed between the plurality of block rows 501 in a plan view. In each of the plurality of sub-flows ST2, air flows from the upstream side to the downstream side in the first direction along a fluid flow path formed near the upper portions of the plurality of block gaps 550 arranged in the first direction. The sub-stream ST2 is sandwiched by two main streams ST1 flowing on the left and right sides thereof. As described above, the block gap 550 is wider than the fine groove 520, and the air flow vortex E is not generated in the block gap 550, so that a flow velocity difference is generated between the sub-flow ST2 and the main flow ST 1. That is, since the flow rates of the sub-stream ST2 and the main stream ST1 on the left and right sides thereof are different from each other, the sub-stream ST2 can be suppressed from deviating from the first direction.

As is clear from the above, in the surface processing sheet 200, the air flows in the first direction through the plurality of main flows ST1 and the sub-flows ST2, and a different flow velocity distribution is generated in the second direction, which is the span direction. That is, in the boundary layer of the laminar flow on the surface processing sheet 200, streaks of the flow velocity in which the opposite low-speed layers and high-speed layers are alternately arranged are formed. The momentum of the air flow flowing in the first direction on the facing sheet 200 spreads in the span direction. This can delay the growth of the turbulent flow region as compared with the case where the uniform flow flows through the surface processing sheet 200.

As described above, in the surface processing sheet 200 having the surface processing structure 201, the plurality of main flows ST1 and sub-flows ST2 can smoothly and stably move in the first direction. By providing the surface processing pieces 200 on the plurality of blades 120, the propeller fan 100 can smoothly rotate while suppressing air resistance during rotation thereof, and can accurately blow wind at a higher speed in the first direction.

An example of a method of designing the surface finish structure 201 described above is described. In the following embodiments, the flow, which is a main object of the surface processing structure 201, among the flows of the fluid and the flow rate that may be generated in the product or the environment in which the surface processing structure 201 is applied is referred to as an object flow. The surface finish 201 is designed to target two flows among a plurality of flows having different flow rates.

The surface processing structure 201 of the present example is applied to the blades 120 of the fan 1, and thus in the fan 1, a plurality of airflows having different flow rates may be generated for each operation mode. For example, the operation modes of the fan 1 include "strong fan" having a high speed (for example, 15 m/s), "medium fan" having a medium speed (for example, 10 m/s), and "weak fan" having a low speed (for example, 4 m/s). The surfacing structure 201 is designed to cooperate with two streams of objects corresponding to two of these multiple modes of motion.

The surface finish 201 has fine grooves 520 and block gaps 550 as two kinds of grooves for controlling air flow. The fine groove 520 is designed to match the fast object stream of the two object streams. The block gap 550 is designed to accommodate the later of the two object streams. Thus, the surface processing structure 201 can smoothly send out the air flow in the same manner as in the above embodiment, regardless of which of the two operation modes the fan 1 is in.

Example 1

A design example of the surface finish structure 201 in embodiment 1 will be described. Fig. 10A is a perspective view of the surface-treated sheet 200 of example 1. Fig. 10B is a table showing the relationship between the surface-treated sheet 200 and the object flow in example 1. Fig. 10C is a table showing the dimensions of the surfacing sheet 200 of example 1. Fig. 10D is a front view of the surface-treated sheet 200 of embodiment 1. Fig. 10E is a side view of the surfacing sheet 200 of example 1.

As shown in fig. 10A, the surface finish structure 201 of example 1 has the same basic structure as the above embodiment. As shown in fig. 10B, the surface processing structure 201 of this example is designed in the following order with the "strong fan" air flow (flow rate 15 m/s) and the "weak fan" air flow (flow rate 4 m/s) as target flows in the operation mode of the fan 1.

First step (determining target value of pitch (pitch) P corresponding to fast object flow)

The target value of the pitch P of the formed grooves is determined in accordance with the object flow having the fast flow rate of the two object flows. In this example, the target value of the pitch P1 of the fine groove 520 is determined in cooperation with the "strong fan" air flow. As shown in fig. 10D, the pitch P1 is equal to the length obtained by adding the groove width W1 of one fine groove 520 and the length of one convex portion 530 in the second direction (i.e., the groove interval G1).

As an example, the target value of the pitch P can be calculated as follows (equation 1) based on the relationship with the target stream.

P=P'. V/u.cndot.cndot.cndot.cndot.1

In (equation 1), P 'is the dimensionless number of pitches P, and in this example, P' =15 to 30.v is the kinematic viscosity coefficient, in this case 20℃air (15.01X10-6 (m/s)). u is the friction speed of the object flow in the surfacing structure 201, in this case the "fan-strong" flow velocity 15 (m/s). As shown in fig. 10B, in this example, the target value of the pitch P1 of the fine groove 520 is calculated to be in the range of 15 to 30 (μm) based on (formula 1).

A second step (determining a target value of the pitch P corresponding to the slow object flow)

The target value of the pitch P of the formed grooves is determined in association with the slow flow velocity of the two object streams. In this example, the target value of the pitch P2 of the block gap 550 is determined in coordination with the "fan weak" airflow. As shown in fig. 12D, the pitch P2 is equal to the length obtained by adding the groove width W2 of one block gap 550 to the length of one block 500 in the second direction (i.e., the groove interval G2).

In this example, the target value of the pitch P2 of the block gap 550 is calculated based on (equation 1). In this case, u is the flow rate 4 (m/s) of "weak air fan". Thus, as shown in fig. 10B, the target value of the pitch P2 of the block gap 550 is calculated to be in the range of 56 to 112 (μm).

Third step (determining the number of micro grooves 520)

The number of the fine grooves 520 provided in each block 500 is determined. The number of the fine grooves 520 provided in each block 500 is at least three, and more preferably five or more. As shown in fig. 10D, in this example, five fine grooves 520 are provided in each block 500.

Fourth step (determining the size of the micro groove 520)

The groove width W1 of each fine groove 520 is determined. As shown in fig. 10D, one fine groove 520 and one convex part 530 are arranged in the second direction at one pitch P1. Here, since the groove width W1 is relatively large and the groove gap G1 is relatively small, the proportion of the fine grooves 520 of the inclined surface 510 of the block 500 increases, and thus frictional resistance to the flow of the fluid is easily suppressed. From this point of view, the groove width W1 is larger than the groove spacing G1. In other words, the width of each of the plurality of fine grooves 520 in the second direction is greater than the width of each of the plurality of protrusions 530 in the second direction.

The plurality of convex portions 530 provided in each block 500 include two first convex portions constituting the second direction both end portions 513 of the upper surface of the block 500, and a plurality of second convex portions different from the two first convex portions. In other words, the plurality of second protrusions are disposed between the two first protrusions. A boundary region BR sandwiched between the main stream ST1 and the sub stream ST2 is formed above each first convex portion. The boundary region BR is a region in which the flow velocity changes in the second direction so as to switch the main stream ST1 and the sub stream ST 2. The boundary region BR suppresses interference between the main stream ST1 and the sub-stream ST2, and the entire air flow stably flows.

Here, in order to stably flow the main flow ST1 and the sub-flow ST2 without meandering, it is preferable to generate momentum diffusion of each air flow. In order to efficiently generate the momentum spread, it is preferable that the flow velocity changes sharply between the main flow ST1 and the sub-flow ST2 in the boundary region BR, and therefore, the narrower the boundary region BR is, the more preferable. The size of the boundary region BR depends on the length of each first protrusion in the second direction, that is, the size of the wall width G10. From such a point of view, the wall width G10 is smaller than the groove width W1 of the fine groove 520.

On the other hand, since the first convex portion is a part of the wall portion forming the fine groove 520, when the thickness of the first convex portion is too small, durability may be impaired or it may be difficult to manufacture the first convex portion accurately. From this point of view, the wall width G10 is equal to or greater than the thickness (groove interval G1) of the second protruding portion. That is, the width of each of the two first convex portions in the second direction is equal to or greater than the width of each of the plurality of second convex portions in the second direction.

In this example, the pitch P1 is determined to be 15 (ms) in the range of 15 to 30 (μm) which is the target value of the pitch P1 determined in the first step. On this basis, the groove width W1 is determined to be 10 (ms), and the groove interval G1 is determined to be 5 (ms). The wall width G10 is determined to be 5 (ms) as with the groove spacing Gl.

Here, in order to suppress the frictional resistance against the air flow, the aspect ratio of the grooves (i.e., the ratio of the height H to the groove width W) may be appropriately designed. The grooves to be designed in this example are the fine grooves 520 and the block gaps 550. The height H can be calculated by the following (equation 2).

H=H'. V/u. Cndot. (formula 2)

In (formula 2), H' is dimensionless by the height H. v and u are kinematic viscosity coefficients and friction speeds as in (formula 1). From the viewpoint of reducing the fluid resistance, the aspect ratio of the grooves (i.e., height H/groove width W) is in the range of 0.5 to 0.7.

In this example, the shape of the longitudinal cross section of the fine groove 520, that is, the groove shape is a square having a rectangular shape when viewed from the first direction. As shown in fig. 10C, in order to suppress the frictional resistance of the air flow flowing along the fine groove 520, the aspect ratio (i.e., height H1/groove width W1) of the fine groove 520 is determined to be 0.5. When the groove width W1 of the fine groove 520 is determined, the height H1 of the fine groove 520 can be calculated by setting the groove width W1 to 0.5 times. Since the groove width W1 is 10 (ms), the height H1 is determined to be 5 (ms).

Fifth step (determining the size of the Block gap 550)

As described above, when the number of fine grooves 520, the groove width W1, the groove interval G1, and the wall width G10 are determined, the length in the second direction of the block 500 (i.e., the groove interval G2) can be calculated. As shown in fig. 10C, in this example, the groove interval G2 is determined to be 80 (μm) corresponding to the five fine grooves 520 and the six convex portions 530 provided on the block 500.

In the range of 56 to 112 (μm) which is the target value of the pitch P2 determined in the second step, the pitch P2 is determined as a value satisfying the following first condition and second condition.

The first condition is explained. The pitch P2 is a value satisfying the condition that the groove width W2 of the block gap 550 is larger than the groove width W1 of the fine groove 520. This condition is the same as that of the second direction width of each of the plurality of fine grooves 520 being smaller than the second direction width of the block gap 550. The groove width W2 corresponds to the difference between the pitch P2 and the groove gap G2. That is, the pitch P2 may be a value larger than the sum of the groove gap G2 and the groove width W1.

When the pitch P2 satisfies the first condition, a flow velocity difference is likely to occur between the main flow ST1 due to the fine groove 520 and the sub-flow ST2 due to the block gap 550. In this example, the groove gap G2 of the block gap 550 is 80 (μm), and the groove width W1 of the fine groove 520 is 10 (ms), so that the pitch P2 may be larger than 90 (μm).

The second condition is explained. The pitch P2 is a value satisfying the condition that "the groove width W2 of the block gap 550 is smaller than the sum of the groove widths W1 of the plurality of fine grooves 520 provided in one block 500". This condition is the same as that the width of the block gap 550 in the second direction is smaller than the sum of the widths of the plurality of fine grooves 520 in the second direction. That is, the pitch P2 may be smaller than the sum of the groove gap G2 and the groove width W1 of each fine groove 520 in one block 500.

By the pitch P2 satisfying the second condition, the area width of the main stream ST1 can be made wider than the area width of the sub-stream ST2, and the surface finish structure 201 effective in the high-speed area as a whole can be realized. In this example, since the number of the fine grooves 520 is five and the groove width W1 is 10 (ms), the sum of the groove widths W1 of the fine grooves 520 is 50 (ms). The pitch P2 may be less than 130 (μm) obtained by adding 80 (μm) to the sum of the groove widths W1, which is the groove gap G2.

Therefore, in this example, the range in which the first condition and the second condition are satisfied among the target values of the pitch P2 is 90 to 112 (μm). The pitch P2 may be determined within this range, but as shown in fig. 10C, the pitch P2 is determined to be 112 (μm). In this case, the groove width W2 of the block gap 550 becomes 32 (μm).

Sixth step (determination of aspect ratio of the block gap 550)

The aspect ratio (i.e., height H2/groove width W2) of the block gap 550 may be 0.5 to 0.7 from the viewpoint of reduction in fluid resistance as described above. Here, as shown in fig. 10E, since the upper surface of the block 500 is the inclined surface 510, the height H2 of the block 500 increases toward the first direction. Along with this, the aspect ratio of the block gap 550 also gradually increases from the upstream side toward the downstream side in the first direction. That is, the block gap 550 is different from the fine groove 520 in aspect ratio toward the first direction.

In order to suppress the frictional resistance of the block gap 550, the aspect ratio of the upstream side end portion of the block gap 550 may be 0.5 or less, and the aspect ratio of the downstream side end portion of the block gap 550 may be 0.7 or more. That is, the aspect ratio of the block gap 550 may be increased toward the first direction so as to span the range of 0.5 to 0.7. To meet this condition, the height H2 of the block 500 may be determined.

In this example, the aspect ratio of the upstream-side end portion of the block gap 550 is determined by the groove width W2 (32 μm) described above and the height H2 (i.e., the minimum value Hmin) of the upstream-side end portion 511 of the block 500. The minimum value Hmin of the block 500 is 16 (μm) or less, and the aspect ratio is 0.5 or less. On the other hand, the aspect ratio of the downstream side end portion of the block gap 550 is determined by the groove width W2 (32 μm) and the height H2 (i.e., the maximum value Hmax) of the downstream side end portion 512 of the block 500 described above. The maximum value Hmax of the block 500 may be 22.4 (μm) or more so that the aspect ratio is 0.7 or more.

However, if the aspect ratio of the block gap 550 is too large or small, the function of the block gap 550 may not be sufficiently exhibited. Therefore, the aspect ratio of the block gap 550 may be set to 0.3 at the lower limit and 2.5 at the upper limit. In this example, the minimum value Hmin of the block 500 is determined to be 10 (μm) so that the aspect ratio of the upstream end portion of the block gap 550 becomes about 0.3. The maximum value Hmax of the block 500 is determined to be 60 (μm) so that the aspect ratio of the downstream side end of the block gap 550 becomes about 1.85. Thus, as shown in fig. 10C, the aspect ratio of the block gap 550 increases from about 0.3 to about 1.85 toward the first direction.

In the block 500 described above, the difference S between the height of the inclined surface 510 is 50 (μm) which is the difference between the maximum value Hmax and the minimum value Hmin. As described above, the inclination angle α of the inclined surface 510 is determined by the height difference S and the depth D of the inclined surface 510. That is, the depth D of the inclined surface 510 may be determined by the height difference S of the inclined surface 510 and the inclination angle α. The inclination angle α may be determined within a range of 6 degrees to 27 degrees, but in this example, the inclination angle α is determined to be 14 degrees, and the depth D is determined to be 100 (μm). In this case, since the depth D is greater than the height H2 and the groove interval G2, the block 500 becomes longer in the first direction in which the airflow flows. The height difference S of the inclined surface 510 and the aspect ratio of the block gap 550 may be appropriately designed by adjusting the inclination angle α and/or the depth D.

Seventh step (sizing gap 540)

As shown in fig. 10E, a groove-like gap 540 extending in the second direction is formed between two blocks 500 adjacent in the first direction among the plurality of blocks 500. A gap 540 is provided between two blocks 500 adjacent in the first direction. When the groove width W3 of the gap 540 is substantially equal to the height difference S of the inclined surface 510, the airflow vortex E is easily and effectively generated (see fig. 9B). For example, when the groove width W3 is in the range of 0.75 to 1.25 times the height difference S, the groove width W3 is substantially equal to the height difference S.

Therefore, in this example, as shown in fig. 10C, the groove width W3 is determined to be approximately equal to 40 (μm) of the height difference S (50 μm). That is, the height difference S of the block 500 located on the upstream side in the first direction among the two blocks 500 is substantially equal to the width in the first direction in the groove-like gap 540.

Production and use examples of the surface-worked structure 201 in which the plurality of blocks 500 are two-dimensionally arranged was produced based on the design values (see fig. 10C) determined in the first to seventh steps. In the thus-fabricated surface-finishing structure 201, the plurality of fine grooves 520 are arranged on the upper surface of the block 500 at a first pitch corresponding to a relatively fast first flow rate of two different flow rates. The plurality of block gaps 550 are arranged at a second pitch corresponding to a relatively slow second flow rate of the two different flow rates on the upper surface of the block 500. In this example, the first pitch corresponding to the first flow rate is a pitch P1 corresponding to the "strong fan" high-speed air flow. The second pitch corresponding to the second flow rate is a pitch P2 corresponding to the "weak fan" low-speed air flow.

The following function is achieved by attaching the surface processing sheet 200 having the surface processing structure 201 to, for example, the blade 120 of the fan 1. When the operation mode of the fan 1 is "fan strong", a high-speed object flow flows along the surface processing structure 201. Since the fine grooves 520 are designed in accordance with the high-speed object flow, the air layer is effectively formed by the fine grooves 520, and contact resistance with the main flow ST1 can be greatly suppressed. On the other hand, when the operation mode of the fan 1 is "weak", the low-speed target flow flows along the surface processing structure 201. Since the block gaps 550 are designed in accordance with the low-speed object flow, the air layer is effectively formed by the block gaps 550, and contact resistance against the sub-flow ST2 can be greatly suppressed.

In this way, since the surface processing structure 201 is designed in accordance with the two operation modes of the fan 1, the contact resistance against at least one of the main flow ST1 and the sub-flow ST2 can be significantly suppressed regardless of whether the operation mode is "strong fan" or "weak fan". Thereby, the entire airflow including the main flow ST1 and the sub-flow ST2 smoothly flows along the surface processing structure 201. Therefore, the surface processing structure 201 can exert a friction reducing effect in a wide range of flow velocity regions of the flowing air.

End design of block 500

As described above, for stabilization of the main stream ST1 and the sub-stream ST2, momentum diffusion of each air stream is preferably generated. In order to generate this momentum spread, the difference in flow velocity between the main flow ST1 and the sub-flow ST2 is preferably large. To achieve this, the difference in height between the upper surface of the block 500 and the bottom surface of the block gap 550 adjacent to each other may be increased. In particular, since the block gaps 550 and the blocks 500 are aligned in the second direction, the level difference between the upper surface of the blocks 500 and the bottom surface of the block gaps 550 may be increased at the boundary where the blocks 500 and the block gaps 550 are adjacent.

From this point of view, both ends 513 in the second direction of the upper surface of the block 500 are located above the bottoms of the plurality of fine grooves 520 in the cross section of the block 500 extending along the plane perpendicular to the first direction. In other words, in the longitudinal section of the cutout 500 perpendicular to the first direction, each of the two end portions 513 is located at a position higher than the bottoms of the plurality of fine grooves 520. Each of the two end portions 513 is a bank-like structure that separates the fine groove 520 from the block gap 550 on the upper surface of the block 500.

If the two first protrusions are not provided on the upper surface of the block 500, the height of each of the two end portions 513 is equal to or less than the bottom of the fine groove 520. In this case, the difference in height between the block 500 and the block gap 550 at the boundary becomes smaller than in the case where the respective end portions 513 are located at positions higher than the bottom of the fine groove 520. That is, the effect of increasing the flow velocity difference between the main flow ST1 and the sub-flow ST2 may be weakened.

In this example, the upper end surfaces of the plurality of protrusions 530 constitute the outer surface of the block 500. The outer surface of the block 500 is an imaginary plane extending along the highest portion of the upper surface of the block 500. Both end portions 513 in the second direction of the upper surface of the block 500 are located at the same height as the outer surface. In other words, each of the two end portions 513 is included in the upper end face of the first protruding portion located at the two ends in the second direction in the block 500. This increases the difference in height between the block 500 and the block gap 550 at the boundary, and enables the main flow ST1 to smoothly flow along the flat outer surface of the block 500.

Further, since the upper surface of the block 500 is the inclined surface 510, the flow velocity of the main flow ST1 can be increased, and the flow velocity difference between the main flow ST1 and the sub flow ST2 can be made larger. Alternatively, the upper surface of the block 500 may be a plane extending in the first direction and the second direction, for example. Even in this case, the same function as described above is achieved by providing a plurality of fine grooves 520 on the upper surface of each block 500 and providing a block gap 550 between two adjacent blocks 500.

Example 2

A design example of the surface finish structure 201 of example 2 will be described. Fig. 11A is a perspective view of the surface-treated sheet 200 of example 2. Fig. 11B is a table showing the relationship between the surface-treated sheet 200 and the object flow in examples 2 and 3. Fig. 11C is a table showing the dimensions of the surface-treated sheet 200 of examples 2 and 3. The point different from example 1 will be described below.

As shown in fig. 11A, the surface finish structure 201 of example 2 has the same basic structure as the above embodiment. As shown in fig. 1lB, the surface processing structure 201 of this example was designed in the same manner as in example 1, using the "strong fan" air flow (flow rate 15 m/s) and the "in fan" air flow (flow rate 10 m/s) as the target flows in the operation mode of the fan 1.

The first step (determination of the target value of the pitch P corresponding to the fast target flow) calculates the target value of the pitch P1 of the fine groove 520 in the range of 15 to 30 (μm) in accordance with the "strong fan" airflow in the same manner as in example 1.

In this example, the target value of the pitch P2 of the block gap 550 is determined in conjunction with the air flow "in fan". In this case, u (formula 1) is the flow rate of "in fan" of 10 (m/s). As a result, as shown in fig. 11B, the target value of the pitch P2 is calculated to be in the range of 22 to 45 (μm).

Third step (determining the number of micro grooves 520)

As in example 1, five fine grooves 520 are provided in each block 500.

Fourth step (determining the size of the micro groove 520)

The number of fine grooves 520, the groove width W1, the groove gap G1, and the wall width G10 are determined in the same manner as in example 1 (see fig. 11C). The fine groove 520 has a square groove shape similar to that of embodiment 1.

Fifth step (determining the size of the Block gap 550)

As in example 1, the groove interval G2 was determined to be 80 (μm) corresponding to the five fine grooves 520 and the six convex portions 530 provided on the block 500. However, the groove gap G2 is larger than 22 to 45 (μm) which is the target value of the pitch P2. In this way, when the flow velocity difference between the two target flows is relatively small, the groove gap G2 (i.e., the size of the block 500) exceeds the target value of the pitch P2, and the block gap 550 may not be arranged within the target value of the pitch P2.

In this case, the groove width W2 of the block gap 550 is determined by setting the groove width W1 of the fine groove 520 to be a predetermined multiple. The predetermined multiple is, for example, in the range of 1 to 5 times (excluding 1 time). As shown in fig. 11C, in this example, 20 (μm) in which the groove width W1 is 2 times is determined as the groove gap G2. Thus, 100 (μm) obtained by adding the groove gap G2 and the groove width W2 is determined as the pitch P2.

Sixth step (determination of aspect ratio of the Block gap 550)

As in embodiment 1, the height H2 of the block 500 may be determined so that the aspect ratio of the block gap 550 increases in the first direction and extends over the range of 0.5 to 0.7.

In this example, the minimum value Hmin of the block 500 is determined to be 10 (μm) so that the aspect ratio of the upstream end portion of the block gap 550 becomes about 0.5. The maximum value Hmax of the block 500 was determined to be 45 (μm) so that the aspect ratio of the downstream side end of the block gap 550 became about 2.2. Thus, as shown in fig. 11C, the aspect ratio of the block gap 550 increases from about 0.5 to about 2.2 toward the first direction.

In the block 500 described above, the difference S between the height of the inclined surface 510 is 35 (μm) which is the difference between the maximum value Hmax and the minimum value Hmin. In this example, the inclination angle α is determined to be 10 degrees, and the depth D is determined to be 200 (μm).

Seventh step (sizing gap 540)

In this example, the groove width W3 is determined to be approximately 30 (μm) equal to the height difference S (35 μm).

Production and use examples of the surface-processed Structure 201

Based on the design values determined in the first to seventh steps (see fig. 11C), the surface-machined structure 201 in which the plurality of blocks 500 are two-dimensionally arranged is fabricated. In the surface processing structure 201 of the present example, the plurality of fine grooves 520 are arranged at a first pitch corresponding to a first flow rate, and the plurality of block gaps 550 are arranged at a second pitch corresponding to a second flow rate. The first pitch corresponding to the first flow rate is a pitch P1 corresponding to the "strong fan" high-speed air flow. The second pitch corresponding to the second flow rate is a pitch P2 corresponding to the medium speed air flow "in fan". In this case, the surface processing structure 201 can exert the friction reducing effect on the flow velocity region of the air flowing in a wide range, as in example 1. Otherwise, the end design of the block 500 is the same as in embodiment 1.

Example 3

A design example of the surface finish structure 201 of example 3 will be described. Fig. 12A is a perspective view of the surface-treated sheet 200 of example 3. Fig. 12B is a front view of the front surface processed sheet 200 of embodiment 3. Fig. 12C is an enlarged perspective view of the block 500 of embodiment 3 from the downstream side. The point different from example 1 will be described below.

As shown in fig. 12A, the surface finish structure 201 of example 3 has the same basic structure as the above embodiment, but differs in that the groove shape of the fine groove 520 is V-shaped. In the V-shaped fine groove 520, the groove width W1 gradually decreases downward. The surface processing structure 201 of this example was designed in the same manner as in example 2, using the "strong fan" air flow (flow rate 15 m/s) and the "in-fan" air flow (flow rate 10 m/s) as the target flows in the operation mode of the fan 1 (see fig. 11B). As a result, the same design value as in example 2 was determined (see fig. 11C). As in example 2, the surface finish structure 201 can exert a friction reducing effect in a wide range of flow velocity regions of the flowing air.

In this example, as in the above embodiment, the upper surface of the block 500 is the inclined surface 510, and thus the height H2 increases toward the first direction. The both end portions 513 of the block 500 are included in the upper end faces of the convex portions 530 at the same height as the outer surface of the block 500 and at both ends in the second direction. However, the block 500 of the present example is different from the above embodiment in the following points.

The fine groove 520 extends in the first direction at the inclined surface 510 with a fixed groove width W1, as in the above embodiment. Unlike the above embodiment, the block 500 has a trapezoidal shape with a shorter upper side than a lower side as viewed in the first direction. Both side surfaces of the block 500 in the second direction extend obliquely downward from both end portions 513 of the upper surface of the block 500. Further, both sides of the block 500 in the second direction face the first direction, and the inclination angle with respect to the base 202 becomes large. In other words, the inclination of both side surfaces of the block 500 becomes steep toward the vertical surface toward the first direction.

Specifically, as shown in fig. 12B, the inclination angle of the side surface extending obliquely downward from both end portions 513 is about 45 degrees on the front surface 521 facing the upstream side of the block 500. On the other hand, as shown in fig. 12C, the inclination angle of the side surface extending obliquely downward from both end portions 513 is about 80 degrees toward the rear surface 522 on the downstream side of the block 500. The inclination angles of both sides of the block 500 gradually increase from the front surface 521 toward the rear surface 522 of the block 500.

According to the above structure, even if the height H2 of the block 500 increases toward the first direction, the length of the block 500 in the second direction (i.e., the groove interval G2) is constant. Therefore, in a plan view, the block 500 has a rectangular shape extending in the first direction with a constant width, as in the above embodiment.

Assuming that the inclination of both side surfaces in the second direction of the block 500 is constant, as the height H2 of the block 500 increases toward the first direction, the length of the block 500 in the second direction increases. In this case, the block 500 has a trapezoidal shape extending in the first direction in a plan view. In this way, the interval (i.e., the groove width W2) of two blocks 500 adjacent in the second direction becomes narrower toward the first direction, and thus the side surfaces of the respective blocks 500 are sometimes connected to each other. In this case, the bottom surface of the block gap 550 bulges upward at the portion where the two blocks 500 are connected, and the difference in height between the upper surface of the block 500 and the bottom surface of the block gap 550 may be small.

In this case, since the inclination of both side surfaces of the block 500 becomes steep in the first direction as described above, the interval between two adjacent blocks 500 in the second direction is constant. Therefore, the connection between two adjacent blocks 500 is suppressed, and therefore, the difference in height between the upper surface of the block 500 and the bottom surface of the block gap 550 can be increased, and the difference in flow velocity between the main flow ST1 and the sub flow ST2 can be increased.

[ thinking ]

The present disclosure is not limited to the above-described embodiments and modifications, and various modifications can be made within the scope of the claims, and embodiments in which the technical means disclosed in the different embodiments are appropriately combined are also included in the technical scope of the present invention. Further, by combining the respective embodiments, new features can be formed.

In the above embodiment, the case where the surface processing sheet 200 is provided to the propeller fan 100 of the fan 1 has been described, but the surface processing sheet 200 may be provided on the surface of the object in contact with the gas or the liquid as the fluid. For example, by providing the surface processing sheet 200 to an outdoor fan of an air conditioner, it is possible to supply air with low power consumption and high efficiency with silence. Further, by providing the surface processing sheet 200 on the inner surface of the hose for drainage or exhaust, the fluid flowing in the hose can be smoothly and desirably directed.

In the above-described embodiment, the surface processing structure 201 is easily and accurately provided on the object by providing the surface processing sheet 200 on the object surface. Alternatively, the surface processing structure 201 may be directly formed on the surface of the object such as the propeller fan 100. At least one block 500 of the plurality of blocks 500 may not have the plurality of fine grooves 520 formed on the inclined surface 510.

The surfacing structure 201 can be applied in various ways. For example, the shape and arrangement of the plurality of blocks 500 can be variously modified as follows. Fig. 13A to 13F are schematic side views of the surface-treated sheet 200 of the first to sixth modifications, respectively. Fig. 14A to 14D are schematic plan views of surface-treated sheets 200 according to seventh to tenth modifications, respectively. Fig. 15A is a schematic plan view of a surface-treated sheet 200 of the eleventh modification. Fig. 15B is a schematic front view of a surface-treated sheet 200 of the eleventh modification.

As shown in the first modification of fig. 13A, two or more blocks 500 arranged in the first direction in each block row 501 may be connected to each other. As shown in the second modification of fig. 13B, each of the plurality of blocks 500 may be provided with an upstream end 511 on the base 202 so as to have a triangular shape in side view. As shown in the third modification of fig. 13C, two or more blocks 500 arranged in the first direction in each block row 501 may be mountain-shaped, which are connected in the first direction in a side view.

As shown in the fourth modification of fig. 13D, each of the plurality of blocks 500 may be plate-shaped extending obliquely upward in the first direction from the base 202. As shown in the fifth modification of fig. 13E, each of the plurality of blocks 500 may have a shape that bulges in a circular arc shape or a parabolic shape in a side view on the base 202. As shown in the sixth modification of fig. 13F, the inclined surface 510 may be curved in an arc shape or a parabolic shape in a side view in each of the plurality of blocks 500.

In the third to fifth modifications (see fig. 13C to 13E), an inclined surface or a curved surface extending from the upstream end 511 located at the front end of the block 500 to the downstream end 512 located at the upper end of the block 500 functions as the inclined surface 510. In this case, an inclined or curved surface extending from the downstream-side end portion 512 to the rear end of the block 500 forms the rear surface 522 of the block 500.

As shown in the seventh modification of fig. 14, the plurality of blocks 500 may be arranged in a staggered manner. In this example, a plurality of blocks 500 constitute a plurality of block rows 502. Each of the plurality of block rows 502 is composed of two or more blocks 500 arranged in the second direction. The plurality of block rows 502 are arranged in the first direction. Of the two plurality of block rows 502 adjacent in the first direction, one block row 502 is offset from the other block rows 502 by half of the block 500 in the second direction.

As in the above embodiment, the plurality of inclined surfaces 510 of the plurality of blocks 500 are arranged on one line V extending in the first direction. Specifically, as shown in fig. 14A, a line V passing through the left or right portion of one block 500 passes through the right or left portion of the block 500 included in each block row 502 in all the block rows 502 in a plan view. That is, the line V passes through the inclined surface 510 of the block 500 in all the block rows 502 in a plan view.

The air directed to the surface processing sheet 200 is branched into a plurality of main flows ST1 and a plurality of sub-flows ST2 as follows. Air toward the left or right portion of each block 500 flows in the first direction along the corresponding line V, respectively. At this time, the air continuously flows along the plurality of inclined surfaces 510, thereby forming a plurality of main streams ST1. On the other hand, the other air alternately flows in the first direction through the central portion of the inclined surface 510 and the block gap 550. As described above, the block gap 550 is wider than the fine groove 520, and the airflow vortex E is not generated in the block gap 550, so that a plurality of sub-streams ST2 having different flow rates from the main stream ST1 are formed.

In the seventh modification (see fig. 14A), as in the above-described embodiment, the plurality of main flows ST1 and the plurality of sub-flows ST2 are alternately arranged in the second direction, and therefore the momentum of the air flow flowing in the first direction on the surface processing sheet 200 spreads in the span direction. Therefore, the plurality of main flows ST1 and sub flows ST2 can smoothly and stably move in the first direction, and higher-speed wind can be accurately blown in the first direction.

As shown in the eighth modification of fig. 14B, the plurality of blocks 500 may have different shapes of a plurality of patterns or may be arranged at random. In this case, in the surface processing sheet 200, the number and the range of the blocks 500 through which the line V passes are different depending on the position in the second direction. In the case where air flows along the line V, when the number and the range of the blocks 500 through which the line V passes are large, the air smoothly flows, thereby forming the main stream ST1. On the other hand, when the air flows along the line V, if the number and the range of the blocks 500 through which the line V passes are small, a sub-flow ST2 having a flow rate different from that of the main flow ST1 is formed.

As described above, if the shape patterns of the plurality of blocks 500 are different or the plurality of blocks 500 are arranged at random, the plurality of main streams ST1 and the plurality of sub streams ST2 are formed, and the formation positions of the main streams ST1 and the sub streams ST2 are deviated in the second direction. Therefore, even in the eighth modification (see fig. 14B), as in the above-described embodiment, the plurality of main flows ST1 and sub-flows ST2 can smoothly and stably move in the first direction, and can accurately blow wind at a higher speed in the first direction.

As shown in the ninth modification of fig. 14C, a plurality of blocks 500 long in the second direction may be formed in one block row 501 aligned in the first direction. In this case, since the air directed to the surface processing sheet 200 flows continuously along the inclined surfaces 510 of the plurality of blocks 500 constituting the block row 501, and the main flow ST1 is formed as a whole, in the ninth modification (see fig. 14C), the air can be blown accurately in the first direction of the wind direction at a higher speed, as in the above embodiment.

As shown in the tenth modification of fig. 14D, the first direction in which two or more blocks 500 constituting each block row 501 are arranged may extend in a curved shape. That is, in each block row 501, two or more blocks 500 may be arranged continuously in a curved shape in a plan view. In this case, each block 500 may be arranged such that the front side thereof faces the upstream side in the first direction and the rear side thereof faces the downstream side in the first direction. Thus, in each block 500, the inclined surface 510 extends so as to be inclined upward in the first direction, and the plurality of fine grooves 520 extend substantially parallel to the first direction and linearly.

In the tenth modification (see fig. 14D), the air directed to the surface processing sheet 200 is branched into the plurality of main flows ST1 and the plurality of sub-flows ST2 and flows in the first direction, and thus functions in the same manner as the above-described embodiment. In this example, the plurality of main streams ST1 and the plurality of sub streams ST2 also flow in a curved shape corresponding to the first direction. In this way, by the function of the surface processing structure 201 to flow air in a certain direction, air can be easily blown in a desired direction.

As shown in the eleventh modification of fig. 15A, each of the plurality of blocks 500 may have a diamond shape in a plan view, or the diamond-shaped blocks 500 may be arranged in a lattice shape. A gap 560 extending obliquely with respect to the first direction and the second direction is formed between two blocks 500 adjacent to each other.

In this case, in the surface processing sheet 200, the number of blocks 500 through which the line V passes differs depending on the position in the second direction. In the case where air flows along the line V, the line V passes through the left or right portion of the block 500, and the number of blocks 500 through which the air passes is greater than the line V passes through the center portion of the block 500.

Here, when the air flows a predetermined distance, the greater the number of blocks 500 through which the air passes, the greater the flow rate of the air for the following reason. The greater the number of blocks 500 at a distance of air flow, the greater the number of gaps 560 within that distance. When air flows through the gap 560, it is difficult to generate contact resistance to the air. That is, the air flowing in the gap 560 is easily moved without reducing its flow rate.

In the eleventh modification (see fig. 15A), a plurality of main flows ST1 are formed by air flowing in the left or right portion of the block 500, and a plurality of sub flows ST2 are formed by air flowing in the central portion of the block 500. As in the above embodiment, the plurality of main streams ST1 and the plurality of sub streams ST2 are alternately arranged in the second direction. Therefore, the plurality of main flows ST1 and sub flows ST2 can smoothly and stably move in the first direction, and can accurately blow wind at a higher speed in the first direction.

As shown in fig. 15B, in the inclined surface 510 of the block 500, the plurality of fine grooves 520 may have a shape that extends so as to curve downward and narrows in width downward when viewed from the front. The plurality of convex portions 530 may be curved upward and narrowed in width upward when viewed from the front. The protruding height may be increased as the plurality of protruding portions 530 are closer to the center in the second direction. Each of the plurality of convex portions 530 may be a shape having a larger height toward the downstream side in the first direction. Even if the inclined surface 510 is configured in this way, the same function as the inclined surface 510 as in the above-described embodiment can be exhibited.

In the example of fig. 15B, the surface roughness of the top of the plurality of convex portions 530 is relatively small. The surface roughness of the bottoms of the plurality of fine grooves 520 is relatively large. This makes it possible to facilitate the air flowing into the inclined surface 510 to flow over the convex portion 530 and to make it difficult to flow into the fine groove 520. In the same manner as in the above embodiment and other modifications, the surface roughness of the convex portion 530 may be relatively small, or the surface roughness of the fine groove 520 may be relatively large.

In the above embodiment, the case where the fine groove 520 is provided on the inclined surface 510 of the block 500 is exemplified. Alternatively, the block 500 may not have the inclined surface 510. The fine groove 520 may not be provided in the block 500. For example, the surface processing structure 201 may include a plurality of first grooves aligned in the second direction and second grooves extending parallel to the first grooves and narrower than the first grooves and shallower than the first grooves. A plurality of second grooves may be arranged between adjacent first grooves. In this case, the first groove functions in the same manner as the block gap 550 and the second groove functions in the same manner as the fine groove 520, as in the above-described embodiment, and therefore, the friction reducing effect can be exerted in a wide flow velocity region of the flowing air.

According to the present disclosure, the following surface finish structure, surface finish piece, and propeller fan can be provided.

(1) A surface processing structure according to an aspect of the present disclosure includes a plurality of blocks which are three-dimensional objects disposed on a target surface, which is a surface of an object, and which are arranged in a first direction parallel to the target surface, each of the plurality of blocks having an inclined surface which extends so as to gradually increase in distance from the target surface from an upstream side toward a downstream side in the first direction,

the plurality of inclined surfaces of the plurality of blocks are arranged on a line extending in the first direction.

(2) In the surface processing structure, the entire inclined surface is exposed on the upstream side of the block in the first direction, and the downstream side end of the inclined surface in the first direction is at the largest distance from the target surface in the block.

(3) In the surface processing structure, two blocks adjacent in the first direction among the plurality of blocks are an upstream side block and a downstream side block located on a downstream side of the upstream side block, and an upstream side end portion of the inclined surface in the first direction among the downstream side blocks is smaller in distance from the object surface than a downstream side end portion of the inclined surface in the first direction among the upstream side blocks.

(4) In the surface processing structure, the plurality of blocks each have a plurality of fine grooves provided on the inclined surface, the plurality of fine grooves being arranged in a second direction orthogonal to the first direction at intervals therebetween and extending from an upstream side toward a downstream side in the first direction.

(5) In the surface processing structure, the plurality of fine grooves extend from an upstream side end portion to a downstream side end portion of the inclined surface in the first direction.

(6) In the surface processing structure, the plurality of blocks are arranged in the first direction and the second direction and are arranged in two dimensions, a groove-like block gap is formed between two blocks adjacent in the second direction among the plurality of blocks, the block gap extends in a direction intersecting the second direction, and a width of each of the plurality of fine grooves in the second direction is smaller than a width of the gap in the second direction.

(7) In the surface processing structure, the plurality of blocks are arranged so as to form a plurality of the gaps arranged in succession in the first direction, the plurality of gaps constituting one fluid flow path extending in the first direction.

(8) The surface processing structure according to one aspect of the present disclosure includes: a plurality of first grooves arranged in a second direction; and a second groove extending parallel to the first groove, being narrower than the first groove, and shallower than the first groove, wherein a plurality of the second grooves are arranged between adjacent first grooves.

(9) In the surfacing structure, an aspect ratio of the first groove is less than an aspect ratio of the second groove.

(10) The surface finish piece according to one aspect of the present disclosure is provided with the surface finish structure on a base material that can be provided on the object surface.

(11) A propeller fan according to an aspect of the present disclosure includes: a rotating shaft portion; and a blade extending outward from the rotation shaft portion, the surface processing structure being provided on a surface of the blade, the first direction being a direction from a leading edge side toward a trailing edge side of the blade.

Claims

1. A surface processing structure is characterized in that,

which comprises a plurality of blocks that are three-dimensional objects arranged on a surface of an object, that is, on the object surface, and are arranged in a first direction parallel to the object surface,

each of the plurality of blocks having an inclined surface extending so as to gradually increase in distance from the object surface from an upstream side toward a downstream side in the first direction,

the plurality of inclined surfaces of the plurality of blocks are arranged on a line extending in the first direction,

each of the plurality of blocks has a plurality of fine grooves provided on the inclined surface,

The plurality of fine grooves are arranged in a second direction orthogonal to the first direction at intervals therebetween and extend from an upstream side toward a downstream side of the first direction,

the plurality of fine grooves extend at the same depth from an upstream side end portion to a downstream side end portion of the inclined surface in the first direction.

2. The surfacing structure according to claim 1, wherein the surface of the substrate comprises a plurality of protrusions,

the entirety of the inclined surface is exposed on the upstream side of the block in the first direction,

the downstream end of the inclined surface in the first direction has a largest distance from the target surface in the block.

3. The surfacing structure according to claim 1 or 2, wherein,

two blocks adjacent in the first direction among the plurality of blocks are an upstream side block and a downstream side block located on a downstream side of the upstream side block,

an upstream-side end of the inclined surface in the first direction in the downstream-side block is smaller in distance from the object surface than a downstream-side end of the inclined surface in the first direction in the upstream-side block.

4. A surface finish according to any one of claims 1 to 3,

The plurality of blocks are arranged in the first direction and the second direction and two-dimensionally arranged,

a groove-like gap extending in the first direction is formed between two blocks adjacent in the second direction among the plurality of blocks,

the width of each of the plurality of fine grooves in the second direction is smaller than the width of the gap in the second direction,

the plurality of blocks are arranged in such a manner that the gap constitutes one fluid flow path extending in the first direction,

the plurality of fine grooves provided on the inclined surface and the fluid flow path are arranged alternately in the second direction.

5. The surfacing structure according to claim 4, wherein the surface of the substrate comprises a plurality of protrusions,

an aspect ratio representing a magnitude of a width of the gap with respect to a depth is smaller than an aspect ratio representing a magnitude of a width of the fine groove with respect to a depth,

the width is a length in the second direction, and the depth is a length in the first direction and a third direction orthogonal to the second direction.

6. A surface processing structure is characterized in that,

which comprises a plurality of blocks that are three-dimensional objects disposed on a target surface, which is a surface of the target, and are arranged in a first direction parallel to the target surface and a second direction orthogonal to the first direction,

the plurality of fine grooves are arranged in the second direction at intervals from each other and extend from an upstream side to a downstream side of the first direction,

7. The surfacing structure according to claim 6, wherein the surface of the substrate comprises a plurality of protrusions,

8. A surface-treated sheet, wherein the surface-treated structure according to any one of claims 1 to 7 is provided on a substrate that can be provided on the target surface.

9. A propeller fan is characterized by comprising:

a rotating shaft portion; and

a blade extending outward from the rotation shaft portion,

the surface finish according to any one of claims 1 to 7 is provided on a surface of the blade,

the first direction is a direction from a leading edge side toward a trailing edge side of the blade.