JP2019082240A - Seal member - Google Patents

Abstract

To provide a seal member which forms a good lubrication film on a slide surface and can stably materialize optional slide resistance.SOLUTION: A seal member 1 slides with a slide surface of a slide member, and is made from an elastomer which seals a gap formed between the slide member and another member. On at least a part of the seal member sliding on the slide surface of the slide member, a plurality of unit patterns 3 having recessed/projected shapes. The unit pattern 3 arranges recessed portions 22 on an outer periphery of a projected portion 21, and is equipped with a flat area 23 between the projected portion 21 and the recessed portions 22.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a sealing member which is in sliding contact with a sliding contact surface of a sliding member and seals a gap formed by the sliding member and another member.

  In automobiles, general machines, industrial machines and the like, a sealing member is widely used which contains a liquid such as lubricating oil between a sliding member such as a shaft and other members and seals the liquid so as not to leak outside.

  For example, in the sealed type rolling bearing shown in Patent Document 1, an inner ring having a raceway surface on the outer peripheral surface, an outer ring having a raceway surface opposed to the raceway surface on the inner peripheral surface, and rollability between both raceway surfaces A plurality of rolling elements, a cage for holding the plurality of rolling elements between the inner ring and the outer ring, a seal attached to the inner circumferential surface of the outer ring and in sliding contact with the outer circumferential surface of the inner ring, and formed between the inner ring and the outer ring And a lubricant sealed in the sealed space.

  In the sealed type rolling bearing of Patent Document 1, for the purpose of suppressing the wear of the seal and the increase of the torque, the seal has a lip portion having a sliding contact surface in sliding contact with the other bearing ring, and the lip On the sliding contact surface of the part, fine linear depressions and linear projections are formed alternately in a stripe pattern to form fine irregularities. Patent Document 1 specifically cites three shapes of fine asperities. In the first, the portion in which the fine asperities are formed is in the form of a strip, and a plurality of the strips are arranged in parallel at equal intervals. The second one is that the portion in which the fine asperity is formed has a rectangular shape, and a plurality of the rectangular portions are uniformly disposed on the sliding contact surface while leaving a predetermined interval. The third part has a portion in which fine irregularities are formed in a circular shape, and a plurality of the circular portions are uniformly distributed on the sliding contact surface while leaving a predetermined interval.

JP 2008-8455 A

  In Patent Document 1 mentioned above, the fine unevenness formed on the sliding contact surface of the seal is shallow with a depth of 0.01 μm or more and 0.2 μm or less, so the amount of lubricant that can be held on the sliding contact surface of the lip portion is Limited. Moreover, since the range of the depth of the fine unevenness is narrow, the range in which the frictional force (sliding resistance) between the sliding contact surface of the lip portion and the sliding member such as the outer peripheral surface of the inner ring can be controlled is small. Furthermore, as shown in FIGS. 4 to 6 of Patent Document 1, the convex portions of the fine unevenness described in Patent Document 1 are lubricated by the unevenness formed in a band shape or a plurality of rectangular portions or circular portions. Since the structure for holding the oil is adopted, the flow of the lubricating oil accumulated in the concave portion is divided by the convex portion, and it is difficult to form a good lubricating film with the sliding member.

  In particular, in the case of the piston seal member provided between the cylinder groove and the piston in the brake caliper, when the brake pedal is depressed, fluid pressure is applied from the master cylinder, and the piston advances. At that time, the piston seal member is elastically deformed by the liquid pressure. After that, when the brake pedal is released, the brake fluid flows to the master cylinder, and the piston is released by the elastic force of the seal member and retreats (rollback action of the seal member), and the appropriate gap (rollback amount) between the rotor and the pad ) Keep. In order to control the amount of rollback to an arbitrary size, the seal member is required to realize stable sliding resistance.

  However, even if the fine unevenness disclosed in Patent Document 1 described above is formed on the piston seal member provided between the piston and the cylinder groove, the fine unevenness is as shallow as 0.01 μm or more and 0.2 μm or less. The simple uneven shape makes it difficult to form a lubricating film in consideration of the flowability of the lubricating oil. Therefore, there arises a disadvantage that stable sliding resistance can not be obtained.

  The present invention has been made to solve the conventional technical problems, and takes into consideration the flowability of lubricating oil, even when any sliding resistance is required between the sliding member and the present invention. It is an object of the present invention to provide a seal member which can form a lubricating film well and stably realize any sliding resistance.

  Then, the present inventors came to provide the sealing member as described below as a result of earnest research.

  That is, the sealing member according to the present invention is made of an elastomer which is in sliding contact with the sliding surface of the sliding member and seals the gap formed by the sliding member and the other members, A plurality of unit patterns having a concavo-convex shape are disposed on at least a part of the seal member in sliding contact with the sliding surface of the second surface, and the unit pattern disposes a recess on the outer periphery of the protrusion. And a flat area between them.

  In the seal member according to the present invention, it is preferable that the unit pattern has the convex portion disposed at a corner portion and / or a central portion, and the concave portion disposed at least on the boundary of the adjacent unit patterns. .

  It is preferable that the seal member according to the present invention has a second concave portion surrounded by the convex portion.

  In the sealing member according to the present invention, it is preferable that the maximum value of the height difference between the convex portion and the second concave portion is equal to or less than the maximum value of the height difference between the flat region and the concave portion.

  In the sealing member according to the present invention, the ratio of the area occupied by the flat area in the unit pattern is preferably 37% or more and 55% or less.

  It is preferable that the seal member according to the present invention has a communication passage communicating with the flat region in a part of the convex portion.

  In the seal member according to the present invention, the elastomer is preferably a thermosetting elastomer.

  The seal member according to the present invention is mounted in a groove formed on the inner circumferential surface of the cylinder, slides on a part of the outer circumferential surface of the piston sliding in the cylinder, and seals the gap formed by the cylinder and the piston It is preferable that it is a piston seal member.

The piston seal member according to the present invention has the void volume (Vvv) of the protruding valley portion and the substantial volume (Vmp) of the protruding peak portion, wherein the unit pattern is represented by a three-dimensional surface property parameter according to ISO 25178-2. It is preferable that the substantial volume (Vmc) of the core portion satisfies the following formula (1).
(Vmp + Vmc) / Vvv> 5.7 (1)

  In the sealing member of the present invention, a plurality of unit patterns having an uneven shape are disposed on at least a sliding surface with the sliding member, and the unit pattern has a recess on the outer periphery of the protrusion, and the protrusion and the protrusion Since the flat region is provided between the concave portion and the concave portion, when the convex portion is elastically deformed by the external pressure, the lubricating oil contained in the concave portion disposed on the outer periphery of the convex portion slides through the flat region. A good lubricating film can be formed between the and the seal member. In addition, it is possible to suppress the disadvantage that the frictional force (sliding resistance) locally increases between the sliding member and the sealing member, and it is possible to stably realize any sliding resistance, and to seal the seal. Sealing performance that is the original function can also be realized.

FIG. 2 is a schematic cross-sectional view of a disc brake for a motorcycle provided with a piston seal member. The A part expansion schematic diagram of FIG. 1 (piston seal mounting state). The principal part expansion schematic diagram of FIG. 1 which shows a piston seal member deformation state at the time of a braking (liquid pressurization). The principal part expansion schematic diagram of FIG. 1 which shows a piston seal member decompression | restoration state in the time of a damping | braking cancellation | release (liquid pressure reduction). The perspective view of a piston seal member. FIG. 6 is a cross-sectional view of the piston seal member of FIG. 5; FIG. 5 is a perspective view of a unit pattern (first embodiment). FIG. 2 is a plan view of a unit pattern (first embodiment). BB sectional drawing of FIG. 8 (1st Embodiment). The plurality arrangement | positioning figure of the unit pattern of FIG. 8 (1st Embodiment). The perspective view of a unit pattern (2nd embodiment). The top view of a unit pattern (2nd embodiment). The CC line cross-section schematic diagram of FIG. 12 (2nd Embodiment). The DD line cross section schematic diagram of FIG. 12 (2nd Embodiment). The plurality arrangement | positioning figure of the unit pattern of FIG. 12 (2nd Embodiment). The perspective view of a unit pattern (3rd Embodiment). The top view of a unit pattern (3rd Embodiment). The EE line | wire cross-section schematic diagram of FIG. 17 (3rd Embodiment). The FF schematic cross section of FIG. 17 (3rd Embodiment). The plurality arrangement | positioning figure of the unit pattern of FIG. 17 (3rd Embodiment). Roll back amount measurement system external appearance schematic diagram. Definition explanatory drawing of the amount of rollback. The confirmation result of repetition stability of liquid pressure (sliding resistance) (Example 1). The repeated stability confirmation result of a liquid pressure (sliding resistance) (Example 2). The repeated stability confirmation result (Example 3) of liquid pressure (sliding resistance). Relationship between rollback amount and (Vmp + Vmc) / Vvv.

  Hereinafter, a piston seal member applied to a disc brake for a motorcycle will be described as an example of a seal member according to an embodiment of the present invention.

  FIG. 1 is a cross-sectional view schematically showing a disc brake 10 for a motorcycle provided with a piston seal member 1 according to the present embodiment, and FIG. 2 is an enlarged schematic view of a portion A of FIG.

  As shown in FIG. 1, the disk brake 10 according to the present embodiment brakes by pressing the disk rotor 11 rotating integrally with the wheels from both sides by the friction pads 13a and 13b incorporated in the caliper body 12. Further, the gap 16 between the inner peripheral surface of the cylinder 14 provided on the caliper body 12 and the outer peripheral surface of the piston 15 is filled with the brake oil which is the lubricating oil 18. The lubricating oil 18 is supplied from an output port of a master cylinder (not shown).

  Further, an annular piston seal groove 17 is formed on the inner peripheral surface of the cylinder 14 described above. An annular piston seal member 1 to which the present invention is applied is attached to the piston seal groove 17.

  The piston seal member 1 is an annular (endless) seal member made of an elastomer, and holds the piston 15 in close sliding contact with the outer peripheral surface of the piston 15 housed in the cylinder 14. The gap 16 between the inner circumferential surface of the piston 15 and the outer circumferential surface of the piston 15 is sealed. Here, as an elastomer constituting the piston seal member 1, for example, ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), butyl rubber (IIR), ethylene-propylene rubber (EPT), fluororubber (FKM) ), Thermosetting rubbers such as styrene rubber (SBR), natural rubber (NR), hydrogenated nitrile rubber (HNBR), nitrile rubber (NBR), thermoplastic elastomers such as polyolefin, polyester and polyurethane, and mixtures thereof Rubber etc. can be mentioned.

  The behavior of the piston seal member 1 when it is pressurized (during braking) or released (during braking release) by the brake oil which is the lubricating oil 18 will be described below with reference to FIGS. The piston seal member 1 is mounted in a piston seal groove 17 formed in the cylinder 14 as shown in FIG. At the time of braking, as shown in FIG. 3, when the lubricating oil 18 is pressurized and the piston 15 advances in the direction of the arrow, the piston seal member 1 in sliding contact with the sliding surface of the piston 15 Due to the frictional force (sliding resistance), elastic deformation as shown in FIG. Then, when the lubricating oil 18 is depressurized at the time of releasing the brake, the residual strain accumulated in the piston seal member 1 is released, and as shown in FIG. Pushback (rollback action) maintains an appropriate gap (rollback amount) between the disk rotor 11 and the friction pads 13a and 13b.

  The present invention is a seal member which exhibits the behavior as described above, and a plurality of unit patterns having a concavo-convex shape are arranged on at least a part of the seal member slidingly contacting the sliding surface of the sliding member (piston 15) In the unit pattern, the concave portion is disposed on the outer periphery of the convex portion, and the flat region is provided between the convex portion and the concave portion, whereby an arbitrary sliding resistance can be stably realized. The sealing effect, which is the original function of the seal, can also be realized with remarkable effects.

  Hereinafter, the shape of the inner peripheral surface 2 of the piston seal, which is a feature of the seal member according to the present invention, will be described by taking the piston seal member 1 according to the present embodiment as an example. FIG. 5 is a perspective view of the piston seal member 1 and FIG. 6 is a cross-sectional view of the piston seal member 1 of FIG. In the piston seal member 1 according to the present embodiment, a plurality of unit patterns having a fine uneven shape are arranged on the inner peripheral surface 2. A fine pattern is formed on the inner circumferential surface 2 by repeating a plurality of unit patterns in succession. In FIG. 5 and FIG. 6, the fine pattern formed on the inner circumferential surface 2 is shown by oblique lines. In this unit pattern, a concave portion is disposed on the outer periphery of the convex portion, and a flat region is provided between the convex portion and the concave portion. Here, three embodiments are described as an example. The size (longitudinal × lateral) of the unit pattern is 100 μm × 100 μm in all the three embodiments.

(1) First Embodiment A unit pattern 3 of the first embodiment will be described with reference to FIGS. 7 to 10. 7 is a perspective view of the unit pattern 3, FIG. 8 is a plan view of the unit pattern 3, FIG. 9 is a schematic sectional view taken along the line B-B of FIG. 8, and FIG. 10 is a view of arranging a plurality of unit patterns 3 of FIG. . In FIG. 7, the change in height of the unit pattern 3 is indicated by contour lines. Also, in FIG. 10, one unit pattern 3 is shown surrounded by a square.

  In the unit pattern 3 of the first embodiment, as shown in FIG. 7, FIG. 8, and FIG. 10, a convex portion 21 protruding inward (toward the piston 15 side) is disposed at the central portion of the rectangular pattern. The recess 22 having a substantially arc-shaped cross section is disposed on the outer periphery of the protrusion 21, specifically, at the four corners of the rectangular pattern. As shown in FIG. 9, a flat area 23 exists between the convex portion 21 and each concave portion 22. Here, although the convex part 21 shown in FIG. 7 is arrange | positioned in the center part containing the center of a rectangular-shaped pattern, the convex part in this invention is not limited to this, The whole convex part is Any area that can be present in the rectangular pattern is referred to as the central portion including this. Moreover, although the recessed part 22 shown in FIG. 7 is arrange | positioned at the part of the four corners of a rectangular-shaped pattern, the recessed part in this invention is not limited to this, The part of a corner and / or adjacent rectangles It may be disposed on at least the boundary of the pattern of shapes. Furthermore, the unit pattern 3 has a second concave portion 24 surrounded by the convex portion 21.

  The functions of the protrusion 21, the recess 22, the second recess 24, and the flat region 23 in the present embodiment will be described below. When the piston seal member 1 is attached to the piston seal groove 17 formed in the cylinder 14, lubricating oil is accumulated in the recess 22 and the second recess 24 of the inner peripheral surface (piston 15 side) 2 of the piston seal member 1 It will be in the state (Fig. 2). In addition, since pressure is naturally applied to the piston seal member 1 at the time of mounting, the convex portion 21 formed on the inner peripheral surface 2 of the piston seal member 1, or the convex portion 21 and the flat area 23 is crushed and lubricating oil is Seal it. At this time, when the flat area 23 is squeezed, the second concave portion 24 present at substantially the same position as the flat area 23 shown in FIG. 9 is also squeezed. However, since the volume of the portion to be crushed is different in the convex portion 21, the second concave portion 24, and the flat region 23, the method of crushing is not uniform in a microscopic manner. There is a slight accumulation of lubricating oil.

  Under such circumstances, when the brake enters a braking state, the piston 15 and the piston seal member 1 are pressurized by the lubricating oil 18, so the piston 15 moves in the direction of the friction pad 13a and moves with the piston 15 The sliding resistance (dynamic frictional force) between the piston seal member 1 and the piston seal member 1 causes elastic deformation of the piston seal member 1 (FIG. 3).

  Thereafter, when the braking state of the brake is released, the lubricating oil 18 is depressurized, so the piston 15 moves in a direction away from the friction pad 13a, and this time elastic deformation occurs from the time when the movement of the piston 15 itself stops. As the piston seal member 1 returns to its original shape, the strain energy stored in the piston seal member 1 is released. At this time, a constant sliding resistance (dynamic frictional force) acts between the piston 15 and the piston seal member 1, so that the piston 15 returns again after the movement of the piston 15 itself stops (rollback action) .

  Since the braking / releasing of the brake is repeated not only once but repeatedly, the piston 15 and the piston seal member 1 will slide repeatedly. At this time, the lubricating oil accumulated in the concave portion 22 or the second concave portion 24 is constantly supplied to the sliding surface and forms a lubricating film as the two slide, so that repeated sliding can be stably performed. . Further, since the flat area 23 has a certain area, it becomes easy to obtain a uniform pressure distribution when the piston seal member 1 is crushed by the external pressure, so that the sliding surfaces of the piston 15 and the piston seal member 1 are uniform. Forming a smooth lubricating film.

  The ratio of the flat region 23 in the unit pattern 3 of the first embodiment shown in FIG. 8 is 49.8%. This ratio is a ratio of only the flat area 23 which does not include the convex portion 21, the second concave portion 24, and the concave portion 22, in which the unit pattern 3 has a rectangular shape of 100 μm × 100 μm.

  Further, the maximum value of the height difference from the top (the point closest to the piston 15) of the protrusion 21 of the unit pattern 3 to the bottom of the second recess 24 for storing lubricating oil is the height difference between the flat region 23 and the recess 22 It is preferable that it is below the maximum value of. This has an influence which contributes to lubricating film formation of the 2nd crevice 24 which stores lubricating oil, when piston seal member 1 carries out elastic deformation, and especially a part of convex part 21 and flat field 23 is crushed. It is because it may become small, and instead, the recessed part 22 will play a role of a supply source of lubricating oil required for favorable lubricating film formation. Therefore, by setting the maximum value of the height difference from the flat region 23 to the recess 22 more than the maximum value of the height difference from the protrusion 21 to the second recess 24, the lubricating oil is abundantly supplied to the sliding surface, and always constant. This is because the formation of the lubricating film is performed.

(2) Second Embodiment A unit pattern 4 according to a second embodiment will be described with reference to FIGS. 11 is a perspective view of the unit pattern 4, FIG. 12 is a plan view of the unit pattern 4, FIG. 13 is a schematic sectional view taken along the line C-C of FIG. 12, and FIG. 14 is a schematic sectional view taken along the line D-D of FIG. These are the figures which arranged multiple unit pattern 4 of FIG. In FIG. 11, the change in height of the unit pattern 4 is indicated by contour lines. Also, in FIG. 15, one unit pattern 4 is shown surrounded by a square.

  In the unit pattern 4 of the second embodiment, as shown in FIG. 11, FIG. 12 and FIG. 15, the compound convex portion 31 protruding inward (toward the piston 15 side) is arranged at the center part of the rectangular pattern area. The concave portion 32 having a substantially arc-shaped cross section is disposed on the outer periphery of the composite convex portion 31, specifically, at the four corners of the rectangular pattern. In addition, about arrangement | positioning of the compound convex part 31 and the recessed part 32 in this embodiment, since it is the same as that of the convex part 21 and the recessed part 22 of 1st Embodiment, description is abbreviate | omitted here.

  The composite convex portion 31 is a combination of four convex portions 31 a in which the communication passage 36 is formed by cutting out a part of the convex portion 21 in the first embodiment, and is surrounded by the respective convex portions 31 a. It has four second recesses 34. At a central portion of the composite convex portion 31, a third concave portion 35 whose periphery is surrounded by four convex portions 31a is formed. The third concave portion 35 functions as a second concave portion in the present invention as the second concave portion 34 does. Further, as shown in FIG. 13 and FIG. 14, a flat region 33 exists between the composite convex portion 31 and each concave portion 32.

  Hereinafter, functions of the composite convex portion 31, the concave portion 32, the second concave portion 34, the third concave portion 35, and the flat region 33 in the present embodiment will be described. First, as described above, the compound convex portion 31 has a shape in which four convex portions 31 a in which the communication passage 36 is formed by cutting out a part of the convex portion 21 described in the first embodiment. The composite convex portion 31 has the same function as the convex portion 21 of the first embodiment, but the communication passage 36 is connected to the flat region 33 so that the third concave portion 35 existing in the central portion of the composite convex portion 31 is present. Even when the external pressure is completely crushed, the flowability of the lubricating oil to the flat area 33 can be secured. This makes it possible to continue to form a good lubricating film on the sliding surface. The functions of the recess 32, the second recess 34, and the flat area 33 are the same as the functions of the recess 22, the second recess 24, and the flat area 23 in the first embodiment, and thus the description thereof is omitted here.

  Further, as in the first embodiment, the height difference from the top (the point closest to the piston 15) of the compound convex portion 31 of the unit pattern 4 to the bottom of the second recess 34 or the third recess 35 for storing lubricating oil The maximum value is preferably equal to or less than the maximum value of the height difference between the flat region 33 and the recess 32. The reason for this is the same as the reason for the first embodiment, so it is omitted here.

  The ratio of the flat area 33 in the unit pattern 4 of the second embodiment shown in FIG. 12 is 37.9%. This ratio is a ratio of only the flat region 33 which does not include the composite convex portion 31, the second concave portion 34, the third concave portion 35, and the concave portion 32 in which the unit pattern 4 has a rectangular shape of 100 μm × 100 μm.

(3) Third Embodiment A unit pattern 5 according to a third embodiment will be described with reference to FIGS. 16 is a perspective view of the unit pattern 5, FIG. 17 is a plan view of the unit pattern 5, FIG. 18 is a schematic sectional view taken along the line E-E of FIG. 17, and FIG. 19 is a schematic sectional view taken along the line F-F of FIG. These are the figures which arranged multiple unit pattern 5 of FIG. In FIG. 16, the change in height of the unit pattern 5 is indicated by contour lines. Further, in FIG. 20, one unit pattern 5 is shown surrounded by a square.

  In the unit pattern 5 of the third embodiment, as shown in FIG. 16, FIG. 17 and FIG. 20, the deformation convex portion 41 protruding inward (toward the piston 15 side) is arranged at the center part of the rectangular pattern area. The concave portion 42 having a deformed elliptical shape is disposed on the outer periphery of the deformed convex portion 41, specifically, in the vicinity of the four corners of the rectangular pattern. As shown in FIGS. 18 and 19, a flat area 43 is present between the deformation convex portion 41 and the concave portions 42 in the deformation oval shape. In addition, about arrangement | positioning of the deformation | transformation convex part 41 in this embodiment, and the recessed part 42, since it is the same as that of the convex part and recessed part of 1st Embodiment and 2nd Embodiment, description is abbreviate | omitted here.

  The deformation convex portion 41 in the unit pattern 5 of the present embodiment is provided with two second concave portions 44, 44 at the top portion where the cross section protrudes toward the piston 15 side. Each of the second recesses 44, 44 also has a function of storing lubricating oil, and as shown in FIG. 17, its shape has a laterally long elliptical shape and is juxtaposed in the major axis direction of the elliptical shape. Further, the periphery of the second concave portions 44, 44 is surrounded by a deformed convex portion 41 constituted by a raised portion connected in a mountain-like shape in which mountains having a difference in elevation are connected. Furthermore, the deformation convex portion 41 having a difference in height has a recess 45 which is somewhat lower than the other portions of the deformation convex portion 41 in a portion where the second concave portions 44 are adjacent to each other on a plane. .

  Hereinafter, functions of the deformation convex portion 41, the concave portion 42, the second concave portions 44 and 44, the recess 45, and the flat area 43 in the present embodiment will be described. In addition, since the function of the recessed part 42 and the 2nd recessed part 44 is the same as that of the recessed part of 1st Embodiment and 2nd Embodiment, and the 2nd recessed part, description is abbreviate | omitted.

  As described above, the deformation convex portion 41 in the present embodiment is constituted by a raised portion in which a mountain range having a difference in height is connected, and in particular, the depression 45 of the deformation convex portion 41 exists as shown in FIG. Thus, the flowability of the lubricating oil on the inner circumferential surface 2 of the piston seal member 1 can be improved. As a result, it is possible to promote stable lubricant film formation on the sliding surface. That is, when the deformation convex portion 41 or the deformation convex portion 41 and the flat area 43 are crushed by the pressure applied to the piston seal member 1, the lubricating oil accumulated in the second concave portion 44 flows out in the convex portion having a constant height. Although the degree is small, the piston seal member 1 is pushed by the external pressure by having the depression 45 in a part of the deformation convex part 41, particularly in a part of the deformation convex part 41 adjacent to the second concave part 44 as in this embodiment. Even when crushed, good flowability of the lubricating oil from the second recess 44 can be realized. In conjunction with such an effect, the size of the concave portion 42 of the deformed elliptical shape formed at the corner of the unit pattern 5 can be reduced, and not only the four corners of the unit pattern 5 but a large number can be formed. Also by this, the lubricating film formed on the sliding surface can be formed more stably.

  Further, as in the first embodiment and the second embodiment, the height difference from the top (the point closest to the piston 15) of the deformation convex portion 41 of the unit pattern 5 to the bottom of the second recess 44 for storing lubricating oil. It is preferable that the maximum value of H is equal to or less than the maximum value of the height difference between the flat area 43 and the recess 42. The reason is the same as the reason of the first embodiment and the second embodiment.

  Although the size of the unit pattern according to each embodiment described above has been described as 100 μm × 100 μm, the size of the unit pattern in the present invention is not limited to this, and may be any size. be able to. This is because, as described in the first to third embodiments, in order to form a good and stable lubricating film, the area ratio between the flat area in the unit pattern and the other area is important. Specifically, in the present invention, the ratio of the area occupied by the flat region in the unit pattern is preferably in the range of 37% to 55% as shown in the first to third embodiments. By setting the ratio of the area occupied by the flat region within this range, it is possible to facilitate the formation of a good and stable lubricating film.

  Hereinafter, examples of the piston seal member of the present invention and the evaluation thereof will be described.

  In the embodiment of the piston seal member to which the present invention is applied, first, a rubber material made of ethylene-propylene-diene rubber (EPDM) is filled in a mold (not shown), and crosslinked by heating for a predetermined time. -Shaped rubber member was obtained. As a mold used for molding, a mold for molding a piston seal member on which a fine concavo-convex pattern is formed on the surface using short pulse laser processing such as femtosecond laser processing is adopted from the viewpoint of fine concavo-convex shape accuracy. The cylindrical rubber member taken out of the mold was cut into a predetermined thickness and cut into a plurality of annular piston seal members as an example.

  The object of the present invention is to control the amount of rollback by controlling the sliding resistance of the sliding surface, and therefore, a piston seal as an example obtained using the unit pattern 3 of the first embodiment described above. With respect to the members, "repetitive stability of liquid pressure (≒ sliding resistance)" and "relationship between three-dimensional surface characteristics of micropatterned surface formed on piston seal member and amount of rollback" were examined.

<Measurement method>
1. Three-dimensional surface texture:
Three types of volume parameters (Vmp (substantial volume of protruding ridges), Vmc (entity of core) of surface roughness according to ISO 25178-2 in measurement area 624 μm × 624 μm using a laser microscope (manufactured by Olympus Corporation) Volume), Vvv (void volume of protruding valley) were measured.

2. Rollback amount:
The amount of rollback when using the piston seal member as an example was measured using the simple measurement system shown in FIG. In the figure, reference numeral 50 denotes a holder for holding the piston seal member 1. Reference numeral 51 denotes a hydraulic pressure gauge which measures the hydraulic pressure of the lubricating oil 18. Reference numeral 52 denotes a displacement meter that measures the displacement of the piston 15.

  Specifically, the amount of rollback is measured by gradually increasing the hydraulic pressure (pressure to the lubricating oil) to displace the piston 15 to 2 mm, and the hydraulic pressure at the start of the piston sliding and that of the lubricating oil during the piston sliding The hydraulic pressure was measured. At this time, if the sliding resistance between the piston 15 and the piston seal member 1 is small, the hydraulic pressure at the time of movement of the piston is small, and if the sliding resistance is large, the hydraulic pressure becomes large. The size of the dynamic resistance is considered. Thereafter, as shown by the arrow in FIG. 22, the displacement amount to which the piston 15 returns after the pressure reduction is started is defined as the rollback amount.

3. Variation of sliding resistance (hydraulic pressure):
The same apparatus as the simplified measurement system (FIG. 21) for measuring the amount of rollback was used to measure the variation in the hydraulic pressure (sliding resistance) when the hydraulic pressure of the lubricating oil was increased.

Examples 1 to 3
1. Ring-shaped piston seal member of each embodiment: outer diameter: 38 mm, inner diameter: 32 mm, thickness: 3 mm. Depth of recess groove: 3 levels (formed by femtosecond laser processing) of 5 μm (Example 1), 7 μm (Example 2), 9 μm (Example 3)

<Result>
Three-dimensional surface texture parameters of the fine pattern on the inner peripheral surface of the piston seal member transferred from the mold in which the fine pattern (the unit pattern of the first embodiment described above) is created by the femtosecond laser beam machine and this three-dimensional surface texture parameter The roll back amounts of the three types of piston seal members (Example 1, Example 2, Example 3) are shown in Table 1. In addition, the measurement used the amount measuring system of rollbacks shown in FIG.

  The results of measurement of the cyclic stability of the hydraulic pressure (sliding resistance) of the lubricating oil by mounting Example 1 to Example 3 of Table 1 on the rollback amount measuring system of FIG. 21 are shown in FIGS. 23 to 25. Show.

  As can be seen from FIGS. 23 to 25, in Example 1 (recess groove depth 5 μm, Vvv 0.25), the variation in the sliding resistance is relatively large, and Example 2 (recess groove depth 7 μm, Vvv 0.29 And in Example 3 (recess groove depth 9 μm, Vvv 0.37), the variation in repeated sliding resistance is small. Therefore, forming a uniform lubricating film stably between the piston 15 and the piston seal member 1 (= sliding surface) by making the recess groove depth larger than 5 μm (Vvv larger than 0.25) I understand.

  Furthermore, the relationship between ((Vmc + Vmp) / Vvv) and the amount of rollback is shown in Table 2 and FIG. 26 using the three-dimensional surface property parameters of Table 1.

  As can be seen from FIG. 26, the rollback amount can be set to an arbitrary value by ((Vmc + Vmp) / Vvv). Here, Example 1 in which ((Vmc + Vmp) / Vvv) is 5.72 lacks stability of repetitive sliding resistance as described above. Therefore, it is understood that ((Vmc + Vmp) / Vvv) preferably has a value larger than 5.7 in order to realize the stability of the sliding resistance and the optional amount of rollback. Note that ((Vmc + Vmp) / Vvv) is considered to mean the friction coefficient between the sliding member and the seal member substantially via the lubricating film.

  By the way, although the piston seal member applied to the disc brake for motorcycles is mentioned as an example and explained in the embodiment mentioned above, the present invention is not limited to this and was provided in the sliding face. Of course, as a sealing member which consists of elastomers, it is applicable also to a sealing member etc. for vacuum boosters, for example.

  The seal member according to the present invention is industrially useful because it can provide a seal member that can stably realize any sliding resistance.

1 Piston seal member (seal member)
Reference Signs List 2 inner circumferential surface 3, 4, 5 unit pattern 10 disk brake 11 disk rotor 12 caliper body 13a, 13b friction pad 14 cylinder 15 piston 16 gap 17 piston seal groove 18 lubricating oil (brake oil)
21 convex part 22 concave part 23 flat area 24 second concave part 31 compound convex part (convex part)
31 a convex portion 32 concave portion 33 flat area 34 second concave portion 35 third concave portion 36 communication passage 41 deformation convex portion (convex portion)
42 recessed portion 43 flat region 44 second recessed portion 45 recessed 50 holder 51 hydraulic pressure gauge 52 displacement gauge

Claims (9)

In a seal member made of an elastomer, which is in sliding contact with a sliding surface of a sliding member and seals a gap formed by the sliding member and another member,
A plurality of unit patterns having a concavo-convex shape are disposed on at least a part of the seal member slidingly contacting the sliding surface of the sliding member,
A sealing member characterized in that the unit pattern has a concave portion on the outer periphery of the convex portion and a flat region between the convex portion and the concave portion.   2. The seal member according to claim 1, wherein the unit pattern has the convex portion disposed in a central portion, and the concave portion disposed at least at a boundary of corner portions and / or adjacent unit patterns.   The seal member according to claim 1 or 2, further comprising a second concave portion surrounded by the convex portion.   The seal member according to claim 3, wherein the maximum value of the height difference between the convex portion and the second concave portion is equal to or less than the maximum value of the height difference between the flat region and the concave portion.   The seal member according to any one of claims 1 to 4, wherein the ratio of the area occupied by the flat area in the unit pattern is 37% or more and 55% or less.   The seal member according to any one of claims 1 to 5, wherein a communication passage communicating with the flat region is provided in a part of the convex portion.   The seal member according to any one of claims 1 to 6, wherein the elastomer is a thermosetting elastomer. The seal member according to any one of claims 1 to 7, wherein
A piston seal mounted in a groove formed on the inner circumferential surface of a cylinder, in sliding contact with a part of an outer circumferential surface of a piston sliding in the cylinder, and sealing a gap formed by the cylinder and the piston. Element. The unit pattern is represented by three-dimensional surface texture parameters in accordance with ISO 25178-2. The void volume (Vvv) of the protruding valley portion, the substantial volume (Vmp) of the protruding peak portion, and the substantial volume (Vmc) of the core portion The piston seal member according to claim 8, wherein and satisfy the following formula (1).
(Vmp + Vmc) / Vvv> 5.7 (1)

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