JP2016211588A - Wet friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide wet friction material for reducing a drawing torque by an embodiment different from conventional material.SOLUTION: Wet friction material 1 comprises a core plate 2 forming a flat plate ring shape, a plurality of friction segments 3 arranged like a ring form at a major surface 2a of the core plate 2 while being spaced apart by a prescribed spacing, and oil grooves 4 formed between each of the friction segments 3. When the wet friction material 1 is rotated in a peripheral direction around a center of the ring shape of the core plate 2 as its center of rotation P under presence of lubricant oil, it has deformed regions 12 for making irregular oil flow at the surface having friction segments 3 of wet frictional material 1. The deformed regions 12 are formed under an arrangement that a shape of a specified friction part [A] in the plurality of friction segments 3 is made different from that of another friction part [B] or regularity in arrangement of the friction segments 3 is disordered.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a wet friction material. More specifically, the present invention relates to a wet friction material that is used in the presence of oil and can be incorporated into a wet clutch, a wet brake, and the like.

Conventionally, wet clutches and wet brakes using wet friction materials are used for torque transmission, braking, and the like. For example, in an automatic transmission such as an automobile, a wet friction material is used in a wet hydraulic clutch.
The wet hydraulic clutch has a structure in which a plurality of wet friction materials and a plurality of separator plates are alternately arranged via a small clearance, and torque transmission / non-transmission is performed by pressing and separating them. Lubricating oil is supplied into the clutch for the purpose of reducing the friction of the wet friction material in the press-contacting / separation and absorbing the frictional heat accompanying the friction. It is known that when the clutch is not engaged, the wet friction material and the separator plate are separated from each other and relatively rotated, and at that time, a torque called drag torque is generated.
Such drag torque consumes unnecessary energy when the clutch is idling. For this reason, reduction of drag torque is desired as a measure for reducing fuel consumption, which has been progressing rapidly in recent years. It is known that there are various approaches for reducing drag torque, and among them, methods for reducing drag torque by devising the shape of the friction part are disclosed in Patent Document 1 and Patent Document 2 below. Has been.

JP 2005-265186 A JP 2008-202706 A

Patent Document 1 discloses a friction portion whose shape is changed so that the oil groove inlet on the inner peripheral side of the wet friction material is enlarged. And the effect that the discharge | emission flow volume of lubricating oil can be increased by employ | adopting this friction part is disclosed.
Patent Document 2 discloses a friction part in which an oil passage from an inner peripheral side to an outer peripheral side of a wet friction material is shaped to stop with an oil reservoir in the middle of the friction part. And the effect that the drag torque at the time of idling can be reduced by employ | adopting this friction part is disclosed.
However, as described above, various drag torque reduction modes are demanded as measures for reducing fuel consumption that have been strongly demanded in recent years.

  This invention is made | formed in view of the said subject, and it aims at providing the wet friction material which achieves reduction of drag torque by the form different from the past.

  The conventional wet friction material achieves a reduction in drag torque by using a friction part having a superior oil discharge property. This is based on the idea that drag torque can be reduced by using a friction part that is excellent in discharging ability compared to a friction part that is inferior in discharging ability. Therefore, it is possible to aim at a further excellent drag torque reduction by developing a friction part having a superior discharge property. However, there is often a proportional relationship between improvement in oil discharge and reduction in the friction area of the friction part. For this reason, when the discharge property is improved, the frictional force may be simultaneously reduced. Thus, when aiming at drag torque reduction depending only on the shape of the friction part, the adoption may be difficult due to the existence of conflicting characteristics.

On the other hand, the present inventors have intensively studied to develop a drag torque reduction method that does not depend only on the shape of the friction part. As a result, the inventors have found a method for reducing drag torque that does not depend on the shape of the friction part itself, and completed the present invention.
That is, the present invention concentrates the lubricating oil in the transition region by forming a transition region that makes the oil flow irregular, and widens the clearance between the wet friction material and the relatively rotated plate. This reduces the shearing resistance and stirring resistance of the lubricating oil interposed between the wet friction material and the plate. In addition, even if the region where the oil flow is irregular is localized as the transition region and the resistance due to the lubricating oil in the region is increased, the resistance in the other region is reduced to reduce the overall resistance. Can be reduced as compared with the prior art.

The present invention is as follows.
The wet friction material according to claim 1 is formed between a core plate having a flat ring shape, a plurality of friction portions arranged in a ring shape with a predetermined interval on the main surface of the core plate, and each friction portion. A wet friction material comprising an oil groove,
When the wet friction material is rotated in the circumferential direction around the center of the ring shape of the core plate in the presence of lubricating oil, the oil flow on the surface of the wet friction material having the friction portion Has an irregular area that makes the
The transition region is that the shape of the specific friction part (A) of the plurality of friction parts is different from other friction parts (B), or the regularity of the arrangement of the friction parts is broken. The gist is that it is formed.
The wet friction material according to claim 2 is the wet friction material according to claim 1, wherein in the transition region, the shape of a specific friction portion (A) of the plurality of friction portions is another friction portion. It is formed by being different from (B),
The specific friction part (A) has a shape having an oil reservoir that is open in the rotational direction, and the other friction part (B) is an oil reservoir that is open in the rotational direction. The gist is that the shape does not have.
The wet friction material according to claim 3 is the wet friction material according to claim 1, wherein in the transition region, the shape of a specific friction portion (A) of the plurality of friction portions is another friction portion. It is formed by being different from (B), and the specific friction part (A) is summarized as having a thicker shape than the other friction part (B).
The wet friction material according to claim 4 is the wet friction material according to claim 1, wherein the transition region is formed by breaking regularity of the arrangement of the friction portions, and the plurality of friction portions The gist is that the regularity is lost due to the loss of some of the friction portions (C).
The wet friction material according to claim 5 is the wet friction material according to any one of claims 1 to 4, wherein the number of the transition regions is 2% or more and 17% with respect to the total number of the friction portions. The summary is as follows.
The wet friction material according to claim 6 is formed between a core plate having a flat ring shape, a plurality of friction portions arranged in a ring shape with a predetermined interval on the main surface of the core plate, and each friction portion. An oil groove, and in the presence of lubricating oil, a wet friction material used by rotating in the circumferential direction around the center of the ring shape of the core plate as a rotation center,
The specific friction part (A) of the plurality of friction parts is a shape having an oil reservoir that is open with respect to the rotation direction,
The other friction part (B) of the plurality of friction parts is summarized as having a shape that does not have an oil reservoir that is open in the rotational direction.
The wet friction material according to claim 7 is the wet friction material according to claim 6, wherein the specific friction portion (A) is configured to cause the oil reservoir to rotate when the wet friction material is rotated counterclockwise. When the wet friction material is rotated counterclockwise when the wet friction material is rotated counterclockwise, the lubricating oil in the oil reservoir is behind the rotation direction. The gist of the present invention is to include a rear weir portion that inhibits slipping out.
The wet friction material according to claim 8 is the wet friction material according to claim 6 or 7, wherein the specific friction portion (A) is configured to rotate the oil when the wet friction material is rotated clockwise. When the wet side friction material is rotated clockwise, the lubricating oil in the oil reservoir is behind the rotation direction when the wet friction material is rotated clockwise. The gist of the present invention is to include a rear weir portion that inhibits slipping out.
The wet friction material according to claim 9 is the wet friction material according to any one of claims 6 to 8, wherein the specific friction portion (A) is 2% or more with respect to the total number of the friction portions. The gist is to provide 17% or less.

The present inventors have reduced drag torque when the oil flow is irregular as compared to when the oil flow is regular on the surface of the wet friction material 1 having the friction part 3. This has led to the completion of the present application.
In other words, the wet friction material 1 of the first invention has a transition region 12 (see FIGS. 1 to 6 and FIGS. 8 to 11). This inflection region 12 is formed by the shape of a specific friction part 3 (A) of the plurality of friction parts 3 being different from the other friction parts 3 (B), or the arrangement of the friction parts 3 It is formed by breaking the regularity of. And by having this transformation area | region 12, when the core plate 2 is rotated in the circumferential direction, the flow of the oil in the surface which has the friction part 3 of the wet friction material 1 becomes irregular. The drag torque can be reduced by making the oil flow irregular on the surface of the wet friction material 1 on the side having the friction part 3.

In the wet friction material 1 according to the first aspect of the present invention, the transition region 12 is formed by the shape of the specific friction portion 3 (A) of the plurality of friction portions 3 being different from the other friction portions 3 (B). While the specific friction portion 3 (A) has a planar shape (see FIGS. 5 to 6 and FIGS. 8 to 10) having an oil reservoir 3 </ b> S that is open with respect to the rotational direction, When the other friction part (B) has a planar shape that does not have an oil reservoir that is open in the rotational direction, the drag torque can be effectively reduced.
In the wet friction material 1 according to the first aspect of the present invention, the transition region 12 is formed by the shape of the specific friction portion 3 (A) of the plurality of friction portions 3 being different from the other friction portions 3 (B). If the specific friction portion 3 (A) is thicker than the other friction portions 3 (B) (see FIG. 11), the drag torque can be effectively reduced. .
In the wet friction material 1 according to the first aspect of the present invention, the transition region 12 is formed when the regularity of the arrangement of the friction portions 3 is broken, and some of the friction portions 3 are frictioned. When the regularity is broken by the lack of the portion 3 (C) (see FIG. 1), the drag torque can be effectively reduced.

The wet friction material 1 of the second invention has a planar shape (see FIGS. 5 to 6 and FIGS. 8 to 10) having an oil reservoir 3S in which a specific friction portion 3 (A) is opened in the rotation direction. On the other hand, the other friction part (B) has a planar shape that does not have an oil reservoir that is open in the rotational direction. Thus, only a part of the friction portion 3 has the oil reservoir portion 3S, so that when the core plate 2 is rotated in the circumferential direction, the oil on the surface having the friction portion 3 of the wet friction material 1 is removed. The flow becomes irregular. The drag torque can be reduced by the irregular flow of oil on the surface of the wet friction material 1 on the side having the friction part 3.
In the wet friction material 1 of the second aspect of the invention, the oil reservoir 3S has a centrifugal dam portion 31 that inhibits the lubricating oil from escaping in the centrifugal direction, and inhibits the lubricating oil from escaping backward in the rotational direction. And the rear weir portion 32 to be formed. When the specific friction portion 3 (A) including the oil reservoir 3S is provided, when the wet friction material 1 is rotated in the circumferential direction, the oil on the surface having the friction portion 3 of the wet friction material 1 is reduced. The flow can be made irregular, which can reduce drag torque.

It is the whole top view and partial perspective view which show Embodiment 1 (Example 1). It is the whole top view and partial perspective view which show Embodiment 2 (Example 2). It is the whole top view and partial perspective view which show Embodiment 3 (Example 3). It is the whole top view and partial perspective view which show Embodiment 4 (Example 4). It is the whole top view and partial perspective view which show Embodiment 5 (Example 5). FIG. 10 is an overall plan view and a partial perspective view showing Embodiment 6. It is the whole top view and partial perspective view which show a comparative product (comparative example 1). It is the whole top view and partial perspective view which show Embodiment 7 (Example 9). It is the whole top view and partial perspective view which show Embodiment 8 (Example 11). It is the whole top view and partial perspective view which show Embodiment 9 (Example 12). FIG. 10 is an overall plan view and a partial perspective view showing Embodiment 10. It is the whole top view and partial perspective view which show a comparative product (comparative example 2). It is explanatory drawing explaining the specific friction part which has the oil reservoir part. It is a graph which shows the correlation with the drag torque obtained using each wet friction material of Example 1-5 and Comparative Example 1, and rotation speed. It is a graph which shows the correlation with the drag torque and rotation speed which are obtained using each wet friction material of Example 6-12 and Comparative Example 2. It is a graph which shows the correlation with the drag torque obtained using each wet friction material of Example 7, Example 13-16, and Comparative Example 2, and the number of shift regions.

  Hereinafter, the present invention will be described with reference to the drawings. The items shown here are exemplary and illustrative of the embodiments of the present invention, and are thought to be the most effective and easy-to-understand explanation of the principles and conceptual features of the present invention. It is stated for the purpose of providing what is to be provided. In this respect, it is necessary for a fundamental understanding of the present invention, and is not intended to show the structural details of the present invention beyond a certain degree. It will be clear to those skilled in the art how this is actually implemented.

[1] Wet Friction Material 1 of the First Invention A wet friction material 1 of the first invention includes a core plate 2 having a flat ring shape, and a plurality of ring plates arranged on the main surface 2a of the core plate 2 at predetermined intervals. A friction part 3 and an oil groove 4 formed between the plurality of friction parts 3 are provided.
The wet friction material 1 of the first invention is obtained when the wet friction material 1 is rotated in the circumferential direction around the center P of the ring shape of the core plate 2 in the presence of lubricating oil. It has a transition region 12 that makes the flow of oil irregular on the surface having one friction part 3 (see FIGS. 1 to 6 and FIGS. 8 to 11).
Further, the metamorphic region 12 is different from the other friction portions 3 (B) in the shape of a specific friction portion 3 (A) among the plurality of friction portions 3 or regularity of the arrangement of the friction portions 3. Is formed by breaking (see FIGS. 1 to 6 and FIGS. 8 to 11).

The core plate 2 has a flat ring shape. The core plate 2 only needs to have a ring shape (annular shape) with a hole in the center. For example, an outer diameter R ₁ (outer diameter) and an inner diameter R ₂ (inner diameter excluding spline inner teeth 8). ) the ratio _R 1 / _{R 2} with the can to from 1.02 to 6. This ratio is preferably 1.07 to 4, and more preferably 1.1 to 1.5. In addition, the core plate 2 may have a ring shape as long as it has a flat plate shape. For example, the thickness of the core plate 2 can be 0.3 to 14.5 mm. This thickness is preferably 0.5 to 6 mm, and more preferably 0.7 to 2.5 mm.
The core plate 2 may be formed of any material, and for example, S35C, S55C, SPCC, NCH780, or the like can be used.
Furthermore, the core plate 2 has a main surface 2a. The main surface 2a is a surface on which the friction portion 3 is disposed. The main surface 2 a is provided on the front surface and / or the back surface of the core plate 2. Therefore, the friction portion 3 may be provided on only one of the front surface and the back surface of the core plate 2 or on both surfaces.

  The friction portion 3 is disposed on the main surface 2a of the core plate 2 (see a partially enlarged view of each figure), and the surface thereof is a friction surface. Depending on the degree of contact between the wet friction material 1 and the separator plate, It has a function of adjusting the interlocking condition between the wet friction material 1 and the separator plate. That is, it has a brake function (braking function) for the separator plate and a torque transmission function.

The friction part 3 may be formed in any manner on the main surface 2 a of the core plate 2. For example, the friction part 3 can be formed from a plurality of friction base materials (segment pieces) joined to the main surface 2 a of the core plate 2. For example, it can be formed by pressing the surface of the core plate 2 while leaving the portion that becomes the friction portion 3 in an island shape, or by cutting the portion that becomes the friction portion 3 in an island shape. The joining method of the core plate 2 and the friction base material is not limited, and examples thereof include heat fusion and sticking via an adhesive or the like.
The friction portion 3 is arranged in a ring shape by forming a plurality of oil grooves 4 on the main surface 2a of the core plate 2. That is, the oil groove 4 is formed as a gap between the adjacent friction portions 3.

The configuration of the friction base material is not particularly limited. For example, the friction base material can be obtained by impregnating a papermaking body obtained by mixing base fiber and filler with a thermosetting resin, followed by heat curing.
As the base fiber, cellulose fiber (pulp), acrylic fiber, aramid fiber and the like can be used, and various synthetic fibers, regenerated fibers, inorganic fibers, natural fibers, and the like can be used. Usually, the base fiber having an average length of 0.5 to 5 mm and an average diameter of 0.1 to 6 μm is used.
As the filler, cashew dust as a friction modifier, graphite and / or molybdenum disulfide as a solid lubricant, diatomaceous earth as an extender pigment, and the like can be used. These may use only 1 type and may use 2 or more types together. Furthermore, as the thermosetting resin, a phenol resin and / or a modified resin thereof can be used.

The inflection region 12 is a region that makes the oil flow irregular on the surface of the wet friction material 1 having the friction portion 3 (see FIGS. 1 to 6 and FIGS. 8 to 11). The wet friction material 1 can reduce drag torque by having the transition region 12.
The conventional wet friction material is devised so that the friction portions are regularly arranged and the oil flow is uniform on the surface of the wet friction material having the friction portions (the oil flow does not become irregular). For example, as illustrated in FIGS. 7 and 12, by using the friction portions 3 having the same shape and arranging them regularly, the flow of oil on the surface having the friction portions of the wet friction material is made uniform. can do. That is, the conventional wet friction material does not have the transformation region 12. Similarly, even in a friction part such as the friction part 3T, the friction part 3T ₁ and the friction part 3T ₂ shown in FIGS. If such a friction part is used as all the friction parts and arranged regularly, the oil flow becomes uniform.
As described above, in the conventional wet friction material, the lubricating oil flowing between the wet friction material and the separator plate opposed to the wet friction material is made uniform, and drag torque is generated in a state where the oil flow is uniform. .
On the other hand, in the wet friction material 1 having the transition region 12, the lubricating oil is concentrated in the transition region while making the oil flow irregular on the surface of the wet friction material 1 having the friction part 3. The clearance between the material and the separator plate that is relatively rotated can be widened. As a result, the drag torque between the wet friction material 1 and the separator plate can be reduced as compared with the case where the flow of the lubricating oil is uniform.

The shift region 12 may be formed in any way, but the drag torque can be effectively reduced by forming it in the following two forms (1) and (2).
That is, the form (1) is a form in which the inflection region 12 is formed by the shape of the specific friction part 3 (A) among the plurality of friction parts 3 being different from the other friction parts 3 (B) ( FIG. 2 to FIG. 6 and FIG. 8 to FIG. 11).
On the other hand, the form (2) is a form in which the metamorphic region 12 is formed by breaking the regularity of the arrangement of the friction portions 3 (see FIG. 1).
Only one of these forms (1) and (2) may be used, or both of them may be used. The specific configuration of these transition areas 12 will be described later.

  Further, the number of the transition regions 12 is not particularly limited, but is preferably 2% or more and 33% or less with respect to the total number of the friction portions 3 (however, of course, the minimum number of the transition regions 12 is 1). . In this range, effective drag torque reduction can be obtained. Further, this ratio is more preferably 2% or more and 17% or less.

[2] Wet friction material of the second invention The wet friction material 1 of the second invention is similar to the wet friction material 1 of the first invention, in that the core plate 2 has a flat ring shape and the main surface 2a of the core plate 2 Are provided with a plurality of friction portions 3 arranged in a ring shape at a predetermined interval, and oil grooves 4 formed between the friction portions 3.
The wet friction material 1 of the second invention is a wet friction material 1 that is used by being rotated in the circumferential direction around the center P of the ring shape of the core plate 2 in the presence of lubricating oil. A specific friction portion 3 (A) of the friction portions 3 has a shape having an oil reservoir portion 3 </ b> S that is open with respect to the rotation direction. On the other hand, the other friction part 3 (B) of the plurality of friction parts 3 has a shape that does not have the oil reservoir 3S opened in the rotation direction (FIGS. 5 to 6 and FIG. 7—See FIG. 9).
As described above, the transition region 12 can be formed by having these specific friction portions 3 (A). In addition, the description of each part in the wet friction material 1 of the second invention is common to the description of each part in the wet friction material 1 of the first invention.

In the second invention, the specific friction portion. 3 (A), when rotating the wet friction material 1 in the counterclockwise direction D _1, the lubricating oil in the oil reservoir 3S exits the centrifugal direction 31d It can have the centrifuge side dam part 31 to inhibit. Further, when rotating the wet friction material 1 in the counterclockwise direction D _1, it is provided with a rear weir 32 which lubricating oil in the oil reservoir 3S inhibits being withdrawn to its rearward 32d with respect to the rotational direction it can. The centrifugal dam portion 31 and the rear dam portion 32 may be provided in a continuous manner or may not be provided in a continuous manner.
The description of each part in the wet friction material 1 of the second invention is common to the description of each part in the wet friction material 1 of the first invention.

Similarly, in the second invention, the specific friction portion. 3 (A), when rotating the wet friction material 1 in the clockwise D _2, the lubricating oil in the oil reservoir 3S exits the centrifugal direction 31d It can have the centrifuge side dam part 31 to inhibit. Furthermore, it is possible to provide for the case of rotating the wet friction material 1 in the clockwise D _2, the rear weir 32 which lubricating oil in the oil reservoir 3S inhibits being withdrawn to its rearward 32d with respect to the rotational direction . The centrifugal dam portion 31 and the rear dam portion 32 may be provided continuously or may not be provided continuously. However, by providing them continuously, a mirror image shape of approximately 7 Arabic numerals can be obtained. .
The description of each part in the wet friction material 1 of the second invention is common to the description of each part in the wet friction material 1 of the first invention.

Embodiment
Hereinafter, the present invention will be described by way of embodiments. In addition, the description common to each embodiment is abbreviate | omitted.
[Embodiment 1]
The wet friction material 1 (FIG. 1) according to the first embodiment includes a core plate 2 and a friction portion 3 disposed on the main surface 2a of the core plate 2 (both the main surface 2a on the front side and the main surface 2a on the back side). And comprising.
The core plate 2 is made of NCH780, and has spline internal teeth 8 formed in a gear shape on the inner periphery thereof. The spline inner teeth 8 are disposed so as to be able to mesh with the splines disposed on the outer periphery of the hub that serves as a rotating shaft with respect to the wet friction material 1.
Further, the outer diameter R ₁ of the core plate 2, the ratio R _{1 /} R ₂ of the inner diameter R ₂ of the core plate 2 _(diameter defined by the inner periphery of the core plate 2 excluding the spline teeth 8) 1. It is set to 02-6. With this shape, the area of the main surface 2a on which the friction part 3 is arranged can be ensured sufficiently. Furthermore, the thickness of the core plate 2 is 0.3-14.5 mm.

  Furthermore, a plurality of segment pieces (friction base materials) having a thickness of 0.3 to 1.2 mm are joined to the core plate 2 on the main surfaces 2a on both sides of the front and back surfaces. Is functioning. The segment pieces as the friction portion 3 are arranged on the core plate 2 so as to be annular as a whole at a predetermined interval. A gap formed between the friction portions 3 of the segment pieces functions as an oil groove 4.

  As shown in FIG. 1, each friction portion 3 has a substantially quadrangular shape when viewed in plan. That is, it has an inner periphery on the side closer to the rotation center P, an outer periphery on the side far from the rotation center P, a side edge connecting one end of the inner periphery and one end of the outer periphery, A side edge connecting the end and the other end of the outer peripheral edge. The outer peripheral edge is formed to be longer than the inner peripheral edge. Further, each corner (four corners) of the friction portion 3 is R-processed. In addition, each corner | angular part may be chamfered, and neither R process nor chamfering may be performed.

The wet friction material 1 (FIG. 1) of the first embodiment has a friction portion 3 when it is rotated in the circumferential direction around the center P of the ring shape of the core plate 2 in the presence of lubricating oil. It has a transition region 12 that makes the oil flow irregular on the surface.
The inflection region 12 is formed when the regularity of the arrangement of the friction portions 3 is broken. Specifically, the regularity of the arrangement of the friction parts 3 is broken and formed due to the loss of some of the friction parts 3 (C) of the plurality of friction parts 3.
That is, in the wet friction material 1 (comparative product) shown in FIG. 7, all 40 friction portions 3 having the same shape are regularly arranged in a ring shape. On the other hand, the wet friction material 1 (FIG. 1) of Embodiment 1 has three friction portions 3 (C) of the 40 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. ) Is lost, the regularity of the arrangement of the friction portions 3 is broken. A region where these friction portions 3 (C) are missing is a metamorphic region 12.

Regions friction part 3 (C) is deficient, it 117 degrees between _{C 1} and _{C 2,} is 126 degrees between _{C 2} and _{C 3,} so that between _{C 3} and _{C 1} becomes 117 degrees Is arranged. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Further, the number of the transition regions 12 included in the wet friction material 1 (FIG. 1) according to the first embodiment is three with respect to the total number of 37 frictional portions 3, and the locality region 12 with respect to the total number of frictional portions 3. The ratio of the number is 8.1% (3/37 × 100 = 8.1). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of shift regions 12 is 1 or more and 12 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of transition regions 12 is 1 or more and 6 or less.
The total number of friction portions 3 included in the wet friction material 1 (FIG. 1) of the first embodiment is 37, but this number can be, for example, 12 or more and 57 or less.

By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The oil flow on the surface of the material 1 having the friction portion 3 is made irregular, and the lubricating oil is concentrated on the transition region 12 to widen the clearance between the wet friction material 1 and the separator plate that is rotated relative thereto. Can do. Thereby, the drag torque between the wet friction material 1 and the separator plate can be reduced.
In the wet friction material 1 according to the first embodiment (FIG. 1), when the rotation direction is clockwise D ₂ also, even when the rotation direction is counterclockwise D _1, it is possible to obtain the effect of the .

[Embodiment 2]
The wet friction material 1 (FIG. 2) according to the second embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A) among the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the wet friction material 1 (FIG. 2) according to the second embodiment includes six friction portions 3 of the 40 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. The two friction portions 3 (A) are combined with each other, and each friction portion 3 (A) is larger than the other friction portions 3 (B). And these three specific friction parts 3 (A) form three inflection regions 12.

The specific friction part 3 (A) is arranged so that the distance between A ₁ and A ₂ is 117 degrees, the distance between A ₂ and A ₃ is 126 degrees, and the distance between A ₃ and A ₁ is 117 degrees. Has been. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Furthermore, the number of transition regions 12 included in the wet friction material 1 (FIG. 2) according to the second embodiment is three with respect to the total number of 37 frictional portions 3, and the locality region 12 with respect to the total number of frictional portions 3. The ratio of the number is 8.1% (3/37 × 100 = 8.1). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of shift regions 12 is 1 or more and 12 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of transition regions 12 is 1 or more and 6 or less.
The total number of friction parts 3 included in the wet friction material 1 (FIG. 2) according to the second embodiment is 37, but this number can be, for example, 12 or more and 57 or less.

By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.
In the wet friction material 1 of Embodiment 2 (FIG. 2), when the rotation direction is clockwise D ₂ also, even when the rotation direction is counterclockwise D _1, it is possible to obtain the effect of the .

[Embodiment 3]
The wet friction material 1 (FIG. 3) according to the third embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A) among the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the wet friction material 1 according to the third embodiment (FIG. 3) includes three friction portions 3 of the 40 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. The side ends are chamfered so as to be inclined surfaces 33 (inclined side surfaces, inclined side surfaces). That is, the specific friction part 3 (A) of the wet friction material 1 (FIG. 3) according to the third embodiment is formed with inclined surfaces 33 (inclined with respect to the rotation direction) at both ends. The friction part 3 (B) does not have the inclined surface 33, whereas the specific friction part 3 (A) differs from the other friction parts 3 (B) by having the inclined surface 33. And these three specific friction parts 3 (A) form three inflection regions 12.

The angle between the particular friction portion 3 (A), is 117 degrees between the _{A 1} and _{A 2,} is 126 degrees between the _{A 2} and _{A 3,} and is 117 degrees between _{A 3} and _{A 1} It is arranged to be. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Furthermore, the number of the transition regions 12 included in the wet friction material 1 (FIG. 3) according to the third embodiment is three with respect to the total number of 40 friction portions 3, and the transition regions 12 with respect to the total number of friction portions 3. The ratio of the number is 7.5% (3/40 × 100 = 7.5). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 40, it is preferable that the number of the transition regions 12 is 1 or more and 13 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 40, it is preferable that the number of transition regions 12 is 1 or more and 6 or less.
In addition, although the total number of the friction part 3 which the wet friction material 1 (FIG. 3) of this Embodiment 3 has is 40 sheets, this number can be 15 sheets or more and 60 sheets or less, for example.

By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.
In the wet friction material 1 of the third embodiment (FIG. 3), when the rotation direction is clockwise D ₂ also, even when the rotation direction is counterclockwise D _1, it is possible to obtain the effect of the . In addition, since the above-mentioned inclined surface 33 can form the transmutation area | region 12 by making it incline toward a rotation direction, it can also be formed only in a required rotation direction.

[Embodiment 4]
The wet friction material 1 (FIG. 4) according to the fourth embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A) among the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the specific friction portion 3 (A) included in the wet friction material 1 (FIG. 4) according to the fourth embodiment is a specific friction portion included in the wet friction material 1 (second embodiment) illustrated in FIG. 3 (A) further has a shape having an oil reservoir 3S. That is, the specific friction part 3 (A) included in the wet friction material 1 (FIG. 4) according to the fourth embodiment is selected from the 40 friction parts 3 included in the wet friction material 1 (comparative product) illustrated in FIG. 7. The six friction portions 3 are combined into two friction portions 3 (A) that are combined two by two, and each friction portion 3 (A) is made larger than the other friction portions 3 (B). Furthermore, each friction part 3 (A) is made into the shape which has the oil reservoir part 3S. And these three specific friction parts 3 (A) form three inflection regions 12.
Further, the oil reservoir 3S is opened to the inner peripheral side of the core plate 2. On the other hand, the oil reservoir 3S is not opened in the rotational direction. Furthermore, the oil reservoir 3S is formed so that the inner peripheral side is wide and the outer peripheral side is narrow.

The angle between the particular friction portion 3 (A), is 117 degrees between the _{A 1} and _{A 2,} is 126 degrees between the _{A 2} and _{A 3,} and is 117 degrees between _{A 3} and _{A 1} It is arranged to be. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Further, the number of the transition regions 12 included in the wet friction material 1 (FIG. 4) according to the fourth embodiment is three with respect to the total number of 37 frictional portions 3, and the locality region 12 with respect to the total number of frictional portions 3. The ratio of the number is 8.1% (3/37 × 100 = 8.1). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of shift regions 12 is 1 or more and 12 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of transition regions 12 is 1 or more and 6 or less.
The total number of the friction parts 3 included in the wet friction material 1 (FIG. 4) according to the fourth embodiment is 37. The number can be, for example, 12 or more and 57 or less.

By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.
In the wet friction material 1 according to the fourth embodiment (FIG. 4), when the rotation direction is clockwise D ₂ also, even when the rotation direction is counterclockwise D _1, it is possible to obtain the effect of the .

[Embodiment 5]
The wet friction material 1 (FIG. 5) according to the fifth embodiment has a transition region 12. The inflection region 12 is formed by the shape of a specific friction portion 3 (A _X ) among the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the specific friction part 3 (A _X ) of the wet friction material 1 (FIG. 5) of the fifth embodiment is the specific friction of the wet friction material 1 (Embodiment 2) shown in FIG. Furthermore, it has a shape having an oil reservoir 3S with respect to the portion 3 (A). That is, the specific friction portion 3 (A _X ) included in the wet friction material 1 (FIG. 5) according to the fifth embodiment is the 40 friction portions 3 included in the wet friction material 1 (comparative product) illustrated in FIG. The six friction portions 3 are combined into two friction portions 3 (A) that are combined two by two, and each friction portion 3 (A) is made larger than the other friction portions 3 (B). In addition, each friction portion 3 (A) has a shape having an oil reservoir portion 3S. And these three specific friction parts 3 (A _X ) form three shift regions 12.
Further, the oil reservoir 3S is opened with respect to the rotational direction (counterclockwise direction D ₁ ) of the wet friction material 1. On the other hand, it is not open to the inner peripheral side of the core plate 2.

The angle between the specific friction parts 3 (A _X ) is 117 degrees between A _X1 and A _X2 , 126 degrees between A _X2 and A _X3, and 117 degrees between A _X3 and A _X1. It is arranged to become. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Furthermore, the number of the transition regions 12 included in the wet friction material 1 (FIG. 5) according to the fifth embodiment is three with respect to the total number of 37 frictional portions 3, and the locality region 12 with respect to the total number of frictional portions 3. The ratio of the number is 8.1% (3/37 × 100 = 8.1). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of shift regions 12 is 1 or more and 12 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 37, it is preferable that the number of transition regions 12 is 1 or more and 6 or less.
The total number of friction parts 3 included in the wet friction material 1 (FIG. 5) according to the fifth embodiment is 37, but this number can be, for example, 12 or more and 57 or less.

By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.
In the wet friction material 1 of Embodiment 5 (FIG. 5), the effect of the direction of rotation to reduce the drag torque in the case of counterclockwise D ₁ is obtained. When reducing the drag torque in the rotation direction of the clockwise D _2, of course, the opening direction of the particular friction portion 3 (A _X) becomes opposite to the direction shown in FIG.

[Embodiment 6]
The wet friction material 1 (FIG. 6) according to the sixth embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A _Y ) of the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the wet friction material 1 (FIG. 6) of the sixth embodiment includes three friction portions 3 out of 45 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. The specific friction portions 3 (A _Y ) are changed, and the specific friction portions 3 (A _Y ) have an oil reservoir portion 3S that is open in the rotation direction (counterclockwise direction D ₁ ). It is a planar shape. In addition, the oil reservoir 3S included in these specific friction portions 3 (A _Y ) is also opened on the inner peripheral side of the core plate 2. That is, the specific friction portion 3 (A _Y ) included in the wet friction material 1 (FIG. 6) according to the sixth embodiment includes the oil reservoir portion 3S that is open to the rotation direction and the inner peripheral side. Thereby, the lubricating oil supplied from a rotation direction and the inner peripheral side of the core plate 2 can be caught more efficiently. On the other hand, the other friction part (B) which the wet friction material 1 (FIG. 6) of Embodiment 6 has is made into the planar shape which does not have the oil reservoir part 3S open | released with respect to the rotation direction. In the wet friction material 1 according to the sixth embodiment, three inflection regions 12 are formed by the three specific friction portions 3 (A _Y ) described above.

The specific friction portion 3 (A _Y ) of the wet friction material 1 (FIG. 6) according to the sixth embodiment is the lubricating oil in the oil reservoir 3S when the wet friction material 1 is rotated counterclockwise. Has a centrifugal dam portion 31 that hinders the escape in the centrifugal direction 31d. Further, when the wet friction material 1 is rotated counterclockwise, the specific friction portion 3 (A _Y ) causes the lubricating oil in the oil reservoir 3S to rotate in the rotation direction (counterclockwise D ₁ ). The rear dam part 32 which inhibits coming out in the direction 32d after that is provided. The centrifugal weir portion 31 and the rear weir portion 32 are connected to each other to form a shape of approximately 7 Arabic numerals (hereinafter also simply referred to as “7-letter shape”). That is, the specific friction portion 3 (A _Y ) included in the wet friction material 1 (FIG. 6) according to the sixth embodiment has a seven-letter shape.
In the wet friction material 1 of the sixth embodiment (FIG. 6), the effect of the direction of rotation to reduce the drag torque in the case of counterclockwise D ₁ is obtained. When reducing the drag torque in the rotation direction of the clockwise D _2, of course, the opening direction of the particular friction portion 3 (A _Y) becomes opposite to the direction shown in FIG. 6 (clockwise D _2).

If the specific friction part 3 (A) includes the centrifugal dam part 31 and the rear dam part 32 as described above, each dam part can inhibit the lubricating oil in the oil reservoir 3S from escaping. The shape beyond that is not particularly limited.
More specifically, when the friction portion 3 (A _Y ) is viewed in plan (see FIG. 13), the edge of the centrifugal dam portion 31 that contacts the oil reservoir 3S may be a curve. It is preferable to be closer to a straight line. When a substantially linear, it is preferred edge L ₃₁ is the angle theta ₁ formed by the virtual line LP ₉₀ is greater than zero degrees. If this angle theta ₁ is 0 degrees or more it can more effectively inhibit escape of the centrifugal direction 31d of the lubricating oil in the oil reservoir 3S. Further, the angle θ ₁ is more preferably 0 ° to 45 °, and particularly preferably 0 ° to 30 °.
Further, when the friction portion 3 (A _Y ) is viewed in plan (see FIG. 13), the edge of the rear weir portion 32 that contacts the oil reservoir 3S may be a curved line, but closer to a straight line. Is preferred. When a substantially linear, it is preferable edges L ₃₂ is the angle theta ₂ formed by the virtual line LP ₀ is 0 degrees or more. If this angle theta ₂ is at 0 degrees or more can more effectively inhibit escape in the direction 32d after the lubricating oil in the oil reservoir 3S. Further, the angle θ ₂ is more preferably 0 degree or greater and 45 degrees or less, and particularly preferably 0 degree or greater and 30 degrees or less.
The line segment LP ₀ is a line segment obtained by extending the diameter of the core plate 2 (passing through the rotation center P), and is a virtual line segment passing through the center of the friction part 3. The line segment LP ₉₀ is a virtual line segment that goes directly to LP ₀ .

Moreover, it is preferable that the width 31w of the centrifugal dam part 31 is 0.4 mm or more. When the width 31w is 0.4 mm or more, the lubricating oil from the oil reservoir 3S can be more effectively inhibited from coming out in the centrifugal direction 31d. The width 31w is more preferably from 0.7 mm to 7 mm, and particularly preferably from 0.7 mm to 3.5 mm.
Furthermore, the width 32w of the rear weir portion 32 is preferably 0.4 mm or more. When the width 32w is 0.4 mm or more, it is possible to more effectively inhibit the oil reservoir 3S from coming out in the rearward direction 32d. The width 32w is more preferably 0.7 mm or more and 7 mm or less, further preferably 1.5 mm or more and 6 mm or less, and particularly preferably 2.5 mm or more and 5 mm or less.

The angle between the specific friction portions 3 (A _Y ) is 117 degrees between A _Y1 and A _Y2 , 126 degrees between A _Y2 and A _Y3, and 117 degrees between A _Y3 and A _Y1. It is arranged to become. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Furthermore, the number of the transition regions 12 included in the wet friction material 1 of the sixth embodiment (FIG. 6) is three with respect to the total number of 40 friction portions 3, and the transition regions 12 with respect to the total number of friction portions 3. The ratio of the number is 7.5% (3/40 × 100 = 7.5). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 40, it is preferable that the number of the transition regions 12 is 1 or more and 13 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 40, it is preferable that the number of transition regions 12 is 1 or more and 6 or less.
The total number of the friction parts 3 included in the wet friction material 1 (FIG. 6) of the sixth embodiment is 40, but this number can be, for example, 15 or more and 60 or less.

  By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.

[Embodiment 7]
The wet friction material 1 (FIG. 8) according to the seventh embodiment includes a core plate 2 and a friction portion 3 disposed on the main surface 2a of the core plate 2 (both the main surface 2a on the front side and the main surface 2a on the back side). And comprising.
The core plate 2 is made of NCH780, and has spline internal teeth 8 formed in a gear shape on the inner periphery thereof. The spline inner teeth 8 are disposed so as to be able to mesh with the splines disposed on the outer periphery of the hub that serves as a rotating shaft with respect to the wet friction material 1.
Further, the outer diameter R ₁ of the core plate 2, the ratio R _{1 /} R ₂ of the inner diameter R ₂ of the core plate 2 _(diameter defined by the inner periphery of the core plate 2 excluding the spline teeth 8) 1. It is set to 02-6. With this shape, the area of the main surface 2a on which the friction part 3 is arranged can be ensured sufficiently. Furthermore, the thickness of the core plate 2 is 0.3-14.5 mm.

  Furthermore, a plurality of segment pieces (friction base materials) having a thickness of 0.3 to 1.2 mm are joined to the core plate 2 on the main surfaces 2a on both sides of the front and back surfaces. Is functioning. The segment pieces as the friction portion 3 are arranged on the core plate 2 so as to be annular as a whole at a predetermined interval. A gap formed between the friction portions 3 of the segment pieces functions as an oil groove 4.

  As shown in FIG. 8, each friction portion 3 has a substantially hexagonal shape whose tip is narrowed toward the inner peripheral side of the core plate 2 when viewed in plan. That is, it has an inner periphery on the side closer to the rotation center P, an outer periphery on the side far from the rotation center P, a side edge connecting one end of the inner periphery and one end of the outer periphery, A side edge connecting the end and the other end of the outer peripheral edge. The outer peripheral edge is formed to be longer than the inner peripheral edge. Further, each corner (four corners) of the friction portion 3 is R-processed. In addition, each corner | angular part may be chamfered, and neither R process nor chamfering may be performed.

Further, the wet friction material 1 (FIG. 8) according to the seventh embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A _Y ) of the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the wet friction material 1 (FIG. 8) of the seventh embodiment includes three friction portions 3 out of 45 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. The specific friction portions 3 (A _Y ) are changed, and the specific friction portions 3 (A _Y ) have an oil reservoir portion 3S that is open in the rotation direction (counterclockwise direction D ₁ ). It is a planar shape. In addition, the oil reservoir 3S included in these specific friction portions 3 (A _Y ) is also opened on the inner peripheral side of the core plate 2. That is, the specific friction portion 3 (A _Y ) included in the wet friction material 1 (FIG. 8) according to the seventh embodiment includes the oil reservoir portion 3S that is open to the rotation direction and the inner peripheral side. Thereby, the lubricating oil supplied from a rotation direction and the inner peripheral side of the core plate 2 can be caught more efficiently. On the other hand, the other friction part (B) which the wet friction material 1 (FIG. 8) of Embodiment 7 has is made into the planar shape which does not have the oil reservoir part 3S open | released with respect to the rotation direction. In the wet friction material 1 according to the seventh embodiment, three inflection regions 12 are formed by the three specific friction portions 3 (A _Y ) described above.

The specific friction portion 3 (A _Y ) of the wet friction material 1 (FIG. 8) according to the seventh embodiment is the lubricating oil in the oil reservoir 3S when the wet friction material 1 is rotated counterclockwise. Has a centrifugal dam portion 31 that hinders the escape in the centrifugal direction 31d. Further, when the wet friction material 1 is rotated counterclockwise, the specific friction portion 3 (A _Y ) causes the lubricating oil in the oil reservoir 3S to rotate in the rotation direction (counterclockwise D ₁ ). The rear dam part 32 which inhibits coming out in the direction 32d after that is provided. The centrifugal weir portion 31 and the rear weir portion 32 are connected to each other to form a shape of approximately 7 Arabic numerals. That is, the specific friction part 3 (A _Y ) included in the wet friction material 1 (FIG. 8) according to the seventh embodiment has a seven-letter shape.
In the wet friction material 1 of the seventh embodiment (FIG. 8), the effect of the direction of rotation to reduce the drag torque in the case of counterclockwise D ₁ is obtained. When reducing the drag torque in the rotation direction of the clockwise D _2, of course, the opening direction of the particular friction portion 3 (A _Y) becomes opposite to the direction shown in FIG. 8 (clockwise D _2).
About the preferable shape regarding specific friction part 3 (A), it is the same as that of the wet friction material 1 of Embodiment 6 (FIG. 6).

The angle between the specific friction portions 3 (A _Y ) is 117 degrees between A _Y1 and A _Y2 , 126 degrees between A _Y2 and A _Y3, and 117 degrees between A _Y3 and A _Y1. It is arranged to become. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Furthermore, the number of the transition regions 12 included in the wet friction material 1 of the seventh embodiment (FIG. 8) is three with respect to the total number of 45 friction portions 3, and the transition regions 12 with respect to the total number of friction portions 3. The ratio of the number is 6.7% (3/45 × 100 = 6.7). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 45, it is preferable that the number of shift regions 12 is 1 or more and 14 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 45, it is preferable that the number of shift regions 12 is 1 or more and 7 or less.
The total number of friction parts 3 included in the wet friction material 1 (FIG. 8) according to the seventh embodiment is 45, but this number can be, for example, 15 or more and 60 or less.

  By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.

[Embodiment 8]
The wet friction material 1 (FIG. 9) according to the eighth embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A _Y ) of the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the wet friction material 1 according to the eighth embodiment (FIG. 9) includes six friction portions 3 out of 45 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. , The specific friction part 3 (A _Y ), and three of these specific friction parts 3 (A _Y ) are oil released in the rotational direction (counterclockwise D ₁ ). It is set as the planar shape which has the reservoir 3S. The remaining three sheets have a planar shape having an oil reservoir 3S that is open with respect to the rotation direction (clockwise D ₂ ). In addition, the oil reservoir 3S included in these specific friction portions 3 (A _Y ) is also opened on the inner peripheral side of the core plate 2. That is, the specific friction portion 3 (A _Y ) included in the wet friction material 1 (FIG. 9) according to the eighth embodiment includes the oil reservoir portion 3S that is open in the rotational direction and the inner peripheral side. Thereby, the lubricating oil supplied from a rotation direction and the inner peripheral side of the core plate 2 can be caught more efficiently. On the other hand, the other friction part (B) which the wet friction material 1 (FIG. 9) of Embodiment 8 has is made into the planar shape which does not have the oil reservoir part 3S open | released with respect to the rotation direction. In the wet friction material 1 according to the eighth embodiment, the six specific friction portions 3 (A _Y ) described above are arranged in a pair, and three shift regions 12 are formed. .

In the wet friction material 1 according to the eighth embodiment, as described above, two specific friction portions 3 (A _Y ) are formed as a set to form one inflection region 12. Specifically, as shown in FIG. 9, one of the specific friction portions 3 (A _Y ) has a seven-letter shape, and the other has a mirror image shape of approximately Arabic numeral 7 (hereinafter also simply referred to as “mirror image shape”). They are arranged back to back (seven shape on the right side and mirror image shape on the left side), and one set of two regions 12 is formed by one set.
Friction unit 3 of these 7 characters shape (A _Y) is inhibited that when this wet friction material 1 is rotated counterclockwise D _1, the lubricating oil in the oil reservoir 3S exits the centrifugal direction 31d And a rear dam portion 32 that inhibits the lubricating oil in the oil reservoir 3S from slipping out in the backward direction 32d in the rotational direction.
Similarly, the friction portion 3 of the mirror image shape (A _Y), when this wet friction material 1 is rotated clockwise D _2, lubricating oil in the oil reservoir 3S inhibits being withdrawn in the centrifugal direction 31d A centrifugal dam portion 31 and a rear dam portion 32 that inhibits the lubricating oil in the oil reservoir 3S from slipping out in the backward direction 32d in the rotational direction are provided.

When the rotational direction is counterclockwise D ₁ is the friction portion 3 of 7 characters shape (A _Y), the flow of the lubricating oil at the surface with a friction portion 3 of the wet friction material 1 can be irregular. On the other hand, when the rotation direction is clockwise D ₂ is the friction portion 3 of the mirror image shape (A _Y), the flow of the lubricating oil at the surface with a friction portion 3 of the wet friction material 1 can be irregular. Therefore, by arranging these two friction portions 3 (A _Y ) in one set, drag torque can be reduced in any rotation direction.
The seven-shaped friction part 3 (A _Y ) and the mirror-shaped friction part 3 (A _Y ) may be arranged next to each other as shown in FIG. 9, but the other friction parts 3 (B ), The same function can be exhibited.

As described above, the 7-shaped friction part 3 (A _Y ) and the mirror-shaped friction part 3 (A _Y ) can be prevented if each dam part prevents the lubricating oil in the oil reservoir part 3S from escaping. Well, the shape beyond it is not specifically limited, About the preferable shape regarding specific friction part 3 ( _AY ), etc., it is the same as that of the wet friction material 1 of Embodiment 6 (FIG. 6).

The angle between the specific friction portions 3 (A _Y ) is 117 degrees between A _Y1 and A _Y2 , 126 degrees between A _Y2 and A _Y3, and 117 degrees between A _Y3 and A _Y1. It is arranged to become. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%. That is, the 7-shaped friction parts 3 (A _Y ) need only have the above-described angle, and the mirror-shaped friction parts 3 (A _Y ) may have the above-described angle.
Furthermore, the number of the transition regions 12 included in the wet friction material 1 (FIG. 9) according to the eighth embodiment is three with respect to the total number of 45 friction portions 3, and the transition regions 12 with respect to the total number of friction portions 3. The ratio of the number is 6.7% (3/45 × 100 = 6.7). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 45, it is preferable that the number of shift regions 12 is 1 or more and 14 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 45, it is preferable that the number of shift regions 12 is 1 or more and 7 or less.
Three seven-shaped friction portions 3 (A _Y ) and three mirror image-shaped friction portions 3 (A _Y ) are arranged via another friction portion 3 (B). In this case, the total number of shift areas 12 is six, but the number of shift areas 12 converted with respect to the rotation direction is three.
Further, the total number of the friction portions 3 included in the wet friction material 1 (FIG. 9) according to the eighth embodiment is 45, but this number can be, for example, 15 or more and 60 or less.

  By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.

[Embodiment 9]
The wet friction material 1 (FIG. 10) according to the ninth embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A _Y ) of the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
In the eighth embodiment (FIG. 9), the specific friction portions 3 (A _Y ) are arranged back-to-back with each other (seven-shaped on the right side and mirror image on the left side). In the wet friction material 1 (FIG. 10) according to the ninth embodiment, the specific friction portions 3 (A _Y ) are arranged in line with each other (a mirror image shape is located on the right side and a seven-letter shape is located on the left side). It is different in point. In other parts, the ninth embodiment is the same as the eighth embodiment.

[Embodiment 10]
The wet friction material 1 (FIG. 11) according to the tenth embodiment has a transition region 12. This transition region 12 is formed by a shape of a specific friction portion 3 (A) among the plurality of friction portions 3 being different from that of the other friction portions 3 (B).
Specifically, the wet friction material 1 of the tenth embodiment (FIG. 11) includes three friction portions 3 out of the 45 friction portions 3 included in the wet friction material 1 (comparative product) shown in FIG. The specific friction portion 3 (A) is changed to a shape that is thicker than the other friction portion (B). The three specific friction portions 3 (A) form three shift regions 12 in the wet friction material 1 of the tenth embodiment.
When the thickness of the specific friction part 3 (A) is d _A and the thickness of the other friction part 3 (B) is d _B , d _A / d _B is “d _A / d _B > 1” I just need it.

The angle between the particular friction portion 3 (A), is 117 degrees between the _{A 1} and _{A 2,} is 126 degrees between the _{A 2} and _{A 3,} and is 117 degrees between _{A 3} and _{A 1} It is arranged to be. These regions are preferably arranged so that the difference in angle between them is in the range of 4% to 10%.
Furthermore, the number of the transition regions 12 included in the wet friction material 1 (FIG. 11) according to the tenth embodiment is three with respect to the total number of 45 friction portions 3, and the transition regions 12 with respect to the total number of friction portions 3. The ratio of the number is 6.7% (3/45 × 100 = 6.7). This ratio is preferably 2% or more and 33% or less. That is, when the total number of friction portions 3 is 45, it is preferable that the number of shift regions 12 is 1 or more and 14 or less. Further, this ratio is more preferably 2% or more and 17% or less. That is, when the total number of friction portions 3 is 45, it is preferable that the number of shift regions 12 is 1 or more and 7 or less.
The total number of friction parts 3 included in the wet friction material 1 (FIG. 11) of the tenth embodiment is 45, but this number can be, for example, 15 or more and 60 or less.

By having the transition region 12 as described above, when the wet friction material 1 is rotated in the circumferential direction around the ring-shaped center P of the core plate 2 in the presence of lubricating oil, the wet friction material 1 The flow of oil on the surface of the material 1 having the friction part 3 can be made irregular. And when this oil flow becomes irregular, drag torque between the wet friction material 1 and the separator plate can be reduced.
In a wet friction material 1 (FIG. 15) of the tenth embodiment, when the rotation direction is clockwise D ₂ also, even when the rotation direction is counterclockwise D _1, it is possible to obtain the effect of the .

  In the tenth embodiment, the transition region 12 is formed by making the thickness of the specific friction portion 3 (A) thicker than that of the other friction portions 3 (B). The inflection region 12 can also be formed by making the thickness of the portion 3 (A) thinner than that of the other friction portions 3 (B). This is natural because the drag torque can be reduced also in the first embodiment.

[Test example]
Below, this invention is demonstrated by a test example.
[1] Wet friction material Each wet friction material of Example 1-12 and Comparative Example 1 was prepared.
(1) Example 1-5
Wet friction material 1 having each of the above-described embodiments 1-5 (see FIGS. 1 to 5) (three transition regions) was prepared. Each core plate 2 is a plate ring shape made of NCH780, having a plate thickness of 0.96 mm, an outer diameter R ₁ = 144.7 mm, and an inner diameter R ₂ = 108.2 mm. Friction members were joined to both the main surfaces 2a on the front and back surfaces of the core plate 2 by pressure heating to form the friction portion 3. The friction base material is made of a thermosetting resin (resin) on a paper body obtained by making a fiber base material such as pulp and aramid fiber, a friction modifier such as cashew dust, and a filler such as diatomaceous earth. The binder is impregnated with heat and cured.

(2) Comparative Example 1
It is a wet friction material which has the friction part 3 of the shape shown in FIG. A friction base material (similar to Example 1-5) is joined to both main surfaces 2a of the front and back surfaces of the core plate 2 (similar to Example 1-5) by pressure heating to form the friction part 3.

(3) Example 9-12
As Example 9, a wet friction material 1 having the form of the above-described Embodiment 7 (FIG. 8) (the total number of friction base materials is 45 sheets and the transition area is 3 places) was prepared. The core plate 2 is made of NCH780 and has a plate ring shape with a plate thickness of 0.96 mm, an outer diameter R ₁ = 143.6 mm, and an inner diameter R ₂ = 123.1 mm. Friction members were joined to both the main surfaces 2a on the front and back surfaces of the core plate 2 by pressure heating to form the friction portion 3. The material of the friction base material is the same as in Example 1-5. And the maximum width 3T (refer FIG. 13) of the friction base material which makes the following specific friction part 3 ( _AY1 , _AY2, and _AY3 ) is 6 mm, and the maximum width of another friction base material is also 6 mm.
Moreover, the shape (refer FIG. 15) of the friction base material which comprises the specific friction part 3 ( _AY1 , _AY2, and _AY3 ) with which Example 9 is provided is common, and both the centrifugal dam part 31 and the rear dam part A portion 32 is provided, and these are connected to form a seven-letter shape. The size (see FIG. 13) of each part in these specific friction portions 3 (A _Y1 , A _Y2 and A _Y3 ) is such that the width 31w of the centrifugal dam portion 31 is 1 mm and the width 32w of the rear dam portion 32 is 3 mm, the angle θ ₁ is 0 degrees, and the angle θ ₂ is 20 degrees.
Similarly, as Example 10, although it has the form of the above-mentioned Embodiment 7 (FIG. 8) (the total number of friction base materials is 45 sheets and the transition area is 3 places), the specific friction part 3 (A _Y ) A wet friction material 1 having a shape different from that of Example 9 was prepared. The shapes of the specific friction portions 3 (A _Y1 , A _Y2, and A _Y3 ) in Example 10 are the same, the width 31 w of the centrifugal dam portion 31 is 3 mm, and the width 32 w of the rear dam portion 32. Is 3 mm, the angle θ ₁ is 0 degree, and the angle θ ₂ is 20 degrees.

Similarly, as Example 11, a wet friction material 1 having the form of the above-described Embodiment 8 (FIG. 9) (the total number of friction base materials is 45 and the transition area is 3 places) was prepared. The shape of the specific friction portion 3 (A _Y1 , A _Y2, and A _Y3 ) of Example 11 is common, and a 7-shaped friction base material (common to the friction base material of Example 9) and its A mirror image-shaped friction base material is placed back to back (seven-shaped on the right side and mirror image on the left side), and a single metamorphic region 12 is formed with a set of two sheets. Yes.
Similarly, as Example 12, a wet friction material 1 having the form of the above-described Embodiment 9 (FIG. 10) (the total number of friction base materials is 45 and the transition area is 3 places) was prepared. The shape of the specific friction portion 3 (A _Y1 , A _Y2, and A _Y3 ) of Example 12 is common, and a 7-shaped friction base material (common to the friction base material of Example 9) and its Mirror image-shaped friction base materials are placed on the stomach (the mirror image shape is located on the right side and the 7-character shape is located on the left side) to form one inflection region 12 with one set of two sheets. ing.

(4) Example 6-8
As Example 6, a wet friction material 1 having the form of the above-described Embodiment 7 (FIG. 8) (the total number of friction base materials is 45 and the number of transition regions is 3) was prepared. The core plate 2 is made of NCH780 and has a plate ring shape with a plate thickness of 0.96 mm, an outer diameter R ₁ = 143.6 mm, and an inner diameter R ₂ = 123.1 mm. Friction members were joined to both the main surfaces 2a on the front and back surfaces of the core plate 2 by pressure heating to form the friction portion 3. The material of the friction base material is the same as in Example 1-5. And the maximum width 3T (refer FIG. 13) of the friction base material of the friction base material which makes the following specific friction parts 3 ( _AY1 , _AY2, and _AY3 ) is 8 mm, and the maximum width of the other friction base material is It is set to 6 mm.
Moreover, the shape (refer FIG. 15) of the friction base material (segment piece) which comprises the specific friction part 3 ( _AY1 , _AY2, and _AY3 ) with which Example 6 is provided is common, and the centrifugal dam part 31 and a rear weir portion 32, and these are connected to form a seven-letter shape. The size (see FIG. 13) of each part in these specific friction portions 3 (A _Y1 , A _Y2 and A _Y3 ) is such that the width 31w of the centrifugal dam portion 31 is 1 mm and the width 32w of the rear dam portion 32 is 1 mm, the angle θ ₁ is 0 degree, and the angle θ ₂ is 20 degrees.
Similarly, as Example 7, although it has the form of the above-mentioned Embodiment 7 (FIG. 8) (the total number of friction base materials is 45 sheets and the transition area is 3 places), the specific friction part 3 (A _Y ) A wet friction material 1 having a shape different from that of Example 6 was prepared. The specific friction portions 3 (A _Y1 , A _Y2, and A _Y3 ) of the seventh embodiment have the same shape, the width 31 w of the centrifugal dam portion 31 is 1 mm, and the width 32 w of the rear dam portion 32. Is 3 mm, the angle θ ₁ is 0 degree, and the angle θ ₂ is 20 degrees.
Furthermore, as Example 8, although it has the form of the above-mentioned Embodiment 7 (FIG. 8) (the total number of friction base materials is 45 sheets and the transition area is 3 places), the shape of the specific friction part 3 (A _Y ) However, a wet friction material 1 different from that in Example 6 was prepared. The shapes of the specific friction portions 3 (A _Y1 , A _Y2, and A _Y3 ) in Example 8 are the same, the width 31 w of the centrifugal dam portion 31 is 1 mm, and the width 32 w of the rear dam portion 32. Is 5 mm, the angle θ ₁ is 0 degrees, and the angle θ ₂ is 20 degrees.

(5) Examples 13-16
Similarly to the above (3), the wet friction material 1 having the form of the above-described seventh embodiment (FIG. 8) (three transition regions), but having a different number of specific friction portions 3 (A _Y ). Prepared as Examples 13-16. Among these, the specific friction part 3 ( _AY ) of Example 13 is one place, the specific friction part 3 ( _AY ) of Example 14 is two places, and the specific friction part 3 of Example 15 is provided. (A _Y ) is 5 places, and the specific friction part 3 (A _Y ) of Example 16 is 7 places. That is, these numbers of the transition regions 12 are formed.
Example 13: One station area Example 14: Two station areas (A _Y1 A _Y2 angle 176 degrees, A _Y2 A _Y1 angle 184 degrees)
Example 7: Three places of the transformation area (A _Y1 A _Y2 angle 120 degrees, A _Y2 A _Y3 angle 120 degrees, A _Y3 A _Y4 angle 120 degrees, A _Y3 A _Y1 angle 120 degrees)
Example 15: Five stations (A _Y1 A _Y2 angle 72 degrees, _AY2 A _Y3 angle 72 degrees, _AY3 A _Y4 angle 72 degrees, _AY4 A _Y5 angle 72 degrees, _AY5 A _Y1 angle 72 degrees)
Example 16: 7 locations of metamorphosis ( _{AY1 AY2} angle 48 degrees, _AY2 A _Y3 angle 56 degrees, _AY3 A _Y4 angle 48 degrees, _AY4 A _Y5 angle 56 degrees, _AY5 A _Y6 angle 48 degrees, _AY6 A _Y7 angle 56 degrees, A _Y7 A _Y1 angle 48 degrees)

(6) Comparative Example 2
It is a wet friction material which has the friction part 3 of the shape shown in FIG. A friction base material (similar to Example 1-5) is joined to both main surfaces 2a of the front and back surfaces of the core plate 2 (similar to Example 1-5) by pressure heating to form the friction part 3.

[2] Correlation between drag torque and rotational speed (1) Correlation between Example 1-5 and Comparative Example 1 Each of the wet friction materials of Example 1-5 and Comparative Example 1 obtained in [1] above was 4 Using the sheet, the rotational speed was measured between 500 and 3000 rpm with an SAE friction tester under the following conditions. The obtained results are shown in a graph in FIG. 14 (FIG. 14 shows that the drag torque is larger on the upper side of the vertical axis).
Automatic transmission lubricating oil (AutoAttic Fluid Fluid, “ATF” is a registered trademark of Idemitsu Kosan Co., Ltd., but here abbreviated as “ATF”, regardless of the registered trademark) Oil temperature: 40 ° C., ATF oil Amount: 2000 mL / min (no shaft center lubrication), total pack clearance: Under the environment of 0.9 mm, set four wet friction materials of the test specimen, change the rotation speed from 500 to 3000 rpm, 500 rpm, 1000 rpm, The drag torque (N · m) was measured at six points of 1500 rpm, 2000 rpm, 2500 rpm, and 3000 rpm. The measurement time was 15 seconds / each rotation, and the number of repetitions was 5.

(2) Effect of Test Example From the result of FIG. 14, it is understood that drag torque can be reduced by forming the transition region 12.
Especially, it turns out that the wet friction material 1 of Example 3 (FIG. 3) can reduce drag torque especially effectively in the range of 500-2000 rpm.
Moreover, it turns out that the wet friction material 1 of Example 4 (FIG. 4) and Example 5 (FIG. 5) can reduce drag torque especially effectively in the area | region of the medium-high rotation speed of 1000 rpm or more. Of these, it can be seen that Example 5 (FIG. 5) exhibits a higher effect than Example 4 (FIG. 4).
Furthermore, it can be seen that the wet friction material 1 of Example 1 (FIG. 1) and Example 2 (FIG. 2) can significantly reduce drag torque in any region of low, medium and high rotation speeds. Especially, it turns out that the effect of Example 2 (FIG. 2) is excellent. The peculiarity of the wet friction material 1 of Example 2 is that the total area of the friction part 3 is more than that of Comparative Example 1 while significantly reducing the drag torque in the entire range of low, medium and high rotation speeds. That is, it can be seen that the frictional force can be improved while reducing the drag torque.

(3) Correlation between Example 6-12 and Comparative Example 2 SAE friction test was performed under the following conditions using seven wet friction materials of Example 6-12 and Comparative Example 2 obtained in [1] above. The number of rotations was measured between 500 and 3000 rpm. The obtained results are shown in a graph in FIG. 15 (FIG. 15 shows that the drag torque is larger on the upper side of the vertical axis).
Automatic transmission lubricating oil (AutoAttic Fluid Fluid, “ATF” is a registered trademark of Idemitsu Kosan Co., Ltd., but here abbreviated as “ATF”, regardless of the registered trademark) Oil temperature: 40 ° C., ATF oil Amount: 2000 mL / min (without shaft center lubrication), total pack clearance: Under the environment of 1.5 mm, 7 wet friction materials of the test specimen were set, the rotation speed was changed from 500 to 3000 rpm, 500 rpm, 1000 rpm, The drag torque (N · m) was measured at six points of 1500 rpm, 2000 rpm, 2500 rpm, and 3000 rpm. The measurement time was 15 seconds / each rotation, and the number of repetitions was 5.

(4) Effect of Test Example From the results of Examples 6-12 and Comparative Example 2 in FIG. 15, by using the specific friction part 3 (A _Y ) having the oil reservoir part 3S opened in the rotation direction, It can be seen that the shift region 12 can be formed to reduce drag torque.
Especially, the difference between Example 6 and Examples 7-12 shows the importance of making the width 32w of the rear dam part 32 into a suitable range. That is, in the result of Example 6, it is recognized that the drag torque gradually increases from the low rotation to the high rotation region. On the other hand, as for the result of Example 7-12, the tendency for drag torque to become small gradually toward the area | region of low rotation to medium rotation is recognized. Among them, in Example 11-12, it is recognized that the drag torque tends to decrease further from the middle rotation to the high rotation region. Thus, the tendency of the drag torque reduction effect can be controlled by the width 32w of the rear dam portion 32. Among these, the results of Example 8 and Example 9 are particularly excellent.

From the result of FIG. 15, it can be seen that the drag torque can be reduced by forming the transition region 12. Furthermore, it can be seen that a 7-shaped friction base material or a mirror image of the friction base material is effective as the shape of the friction portion 3 </ b> A constituting the transition region 12.
Further, it can be understood from the comparison between Example 9 and Example 10 in FIG. 15 that the width 31w of the centrifugal dam portion 31 affects the magnitude of the drag torque. Similarly, from comparison between Example 6, Example 7, and Example 8, it can be seen that the width 32w of the rear weir portion 32 affects the drag torque.
Specifically, from the comparison between Example 9 (the width 31w of the centrifugal dam 31 is 1 mm) and Example 10 (the width 31w of the centrifugal dam 31 is 3 mm), the width of the centrifugal dam 31 is shown. It can be seen that the drag torque can be reduced in the entire range of the relative rotational speed by reducing.
Furthermore, Example 6 (the width 32w of the rear dam 32 is 1 mm), Example 7 (the width 32w of the rear dam 32 is 3 mm), and Example 8 (the width 32w of the rear dam 32 is 5 mm), From the comparison, it can be seen that by increasing the width of the rear weir portion 32, it is possible to reduce the drag torque in the entire region of the relative rotational speed. In particular, it is considered that the wider the rear weir portion 32, the higher the drag torque reduction effect. This is because the area on which the lubricating oil rides on the friction base material surface (especially, the area on the rear dam 32) is increased by increasing the width 32w of the rear dam part 32, and the wet friction material and the separator are increased by increasing the ride area. This is probably because the clearance with the plate can be further increased.

In addition, when Example 6 and Example 10 are compared, the drag torque of Example 10 is lower in the range of relative rotation speed 1000 or more, while the drag torque at relative rotation speed 500 is lower in Example 6. I understand that.
Specifically, it is considered that the drag torque reduction effect in the low rotation range with a relative rotational speed of less than 1000 is higher when the width 31w of the centrifugal dam portion 31 is narrower. This is because the reduction of the width 31 of the centrifugal dam portion 31 makes it easier for the lubricating oil to ride on the outer peripheral region on the rear dam portion 32, and as a result, the riding area on the rear dam portion 32 is increased. Since it is enlarged, it is considered that the clearance between the wet friction material and the separator plate can be further increased.
From this result, it can be seen that the combination of the characteristics of the width 31w, the width 32w, and the maximum width 3T can be used as a means for reducing the drag torque in a specific rotation region as necessary.

[3] Correlation between drag torque and shift region (1) Correlation between Example 7, Example 13-16 and Comparative Example 2 Example 7, Example 13-16 and Comparative Example obtained in [1] above Each of the two wet friction materials of No. 2 was used and measured with a SAE friction tester at the rotation speed of 1000 rpm under the following conditions. The obtained results are shown in a graph in FIG. 16 (FIG. 16 shows that the drag torque is larger on the upper side of the vertical axis).
Automatic transmission lubricating oil (AutoAttic Fluid Fluid, “ATF” is a registered trademark of Idemitsu Kosan Co., Ltd., but here abbreviated as “ATF”, regardless of the registered trademark) Oil temperature: 40 ° C., ATF oil Amount: 2000 mL / min (no shaft center lubrication), Total pack clearance: 7 mm of wet friction material of the test specimen was set in an environment of 1.5 mm, and the rotation speed was changed from 500 to 3000 rpm. The drag torque (N · m) was measured at 1000 rpm. The measurement time was 15 seconds / each rotation, and the number of repetitions was 5.

(2) Effect of Test Example From the results of FIG. 16, it can be seen that drag torque can be reduced by forming the transition region 12. Furthermore, it turns out that the number of the metamorphosis area | region 12 is exhibited in all the test ranges of 1-6, is especially excellent in 1-5, and 1-3 are especially excellent.

  In addition, in this invention, it can restrict to what is shown to said specific Example, It can be set as the Example variously changed within the range of this invention according to the objective and the use.

  The use of the wet friction material of the present invention is not particularly limited, and is widely applied to, for example, automobiles (four-wheel automobiles, two-wheel automobiles, etc.), railway vehicles, ships, airplanes and the like. Among these, the automobile article is suitably used for an automatic transmission (automatic transmission, AT). Only one wet friction material may be used in the transmission, or a plurality of wet friction materials may be used, but a plurality of wet friction materials are preferably used. If the wet friction material is used more frequently in one transmission, a great effect can be obtained in an integrated manner. That is, drag torque can be more effectively reduced in a wet multi-plate clutch that uses a large number of wet friction materials.

1; wet friction material, 12;
2; core plate, 2a; main surface,
3; friction part,
3A: friction part forming the inflection region,
3A _X ; friction part having an oil reservoir part opened in the rotation direction,
3A _Y ; friction part having an oil reservoir part opened in the rotational direction and the inner peripheral side;
3B: a friction part that does not form an inflection region,
3S; oil reservoir,
31; centrifugal weir part,
32; rear weir,
33; inclined surface (inclined side surface),
4; oil groove,
8; Spline internal teeth,
LP ₀ ; virtual diameter (line segment obtained by extending the virtual diameter)
LP ₉₀ ; hypothetical line segment 31w perpendicular to LP ₀ ; width of the centrifugal weir,
32w; rear weir width,
L ₃₁ ; an edge (plan view) in contact with the oil reservoir in the centrifugal dam portion,
L ₃₂ ; an edge (plan view) in contact with the oil reservoir in the rear weir,
θ ₁ ; angle formed by LP ₉₀ and L ₃₁ ,
θ ₂ ; an angle formed by LP ₀ and L ₃₂ ,
P: Center of rotation.

Claims (9)

A wet friction material comprising a core plate having a flat ring shape, a plurality of friction portions arranged in a ring shape with a predetermined interval on the main surface of the core plate, and oil grooves formed between the friction portions. There,
When the wet friction material is rotated in the circumferential direction around the center of the ring shape of the core plate in the presence of lubricating oil, the oil flow on the surface of the wet friction material having the friction portion Has an irregular area that makes the
The transition region is that the shape of the specific friction part (A) of the plurality of friction parts is different from other friction parts (B), or the regularity of the arrangement of the friction parts is broken. A wet friction material characterized by being formed. The transition region is formed by a shape of a specific friction part (A) among the plurality of friction parts being different from other friction parts (B),
The specific friction part (A) has a shape having an oil reservoir that is open in the rotational direction, and the other friction part (B) is an oil reservoir that is open in the rotational direction. The wet friction material according to claim 1, wherein the wet friction material has a shape that does not have any. The transition region is formed by a shape of a specific friction part (A) among the plurality of friction parts being different from other friction parts (B),
The wet friction material according to claim 1, wherein the specific friction part (A) has a shape that is thicker than the other friction part (B). The translocation region is formed by breaking the regularity of the arrangement of the friction part,
The wet friction material according to claim 1, wherein the regularity is broken due to a loss of a part of the friction portions (C) of the plurality of friction portions.   The wet friction material according to any one of claims 1 to 4, wherein the number of the transition regions is 2% or more and 17% or less with respect to the total number of the friction portions. A core plate having a flat ring shape, a plurality of friction portions arranged in a ring shape with a predetermined interval on the main surface of the core plate, and oil grooves formed between the friction portions, In the presence, a wet friction material used by rotating in the circumferential direction around the center of the ring shape of the core plate,
The specific friction part (A) of the plurality of friction parts is a shape having an oil reservoir that is open with respect to the rotation direction,
The other friction part (B) of the plurality of friction parts has a shape that does not have an oil reservoir open to the rotation direction.   When the wet friction material is rotated counterclockwise, the specific friction portion (A) includes a centrifugal dam portion that inhibits the lubricating oil in the oil reservoir portion from escaping in the centrifugal direction, and the wet friction material. The wet friction material according to claim 6, further comprising: a rear weir portion that inhibits the lubricating oil in the oil reservoir portion from slipping backward in the rotation direction when the material is rotated counterclockwise. .   When the wet friction material is rotated clockwise, the specific friction portion (A) includes a centrifugal side weir portion that inhibits the lubricating oil in the oil reservoir from coming out in the centrifugal direction, and the wet friction material. A wet friction material according to claim 6 or 7, further comprising: a rear weir portion that inhibits the lubricating oil in the oil reservoir portion from slipping backward in the rotational direction when the oil is rotated clockwise. .   The wet friction material according to any one of claims 6 to 8, comprising the specific friction portion (A) in a range of 2% to 17% with respect to the total number of the friction portions.

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