JP6930954B2 - Wet friction material - Google Patents

Description

The present invention relates to a wet friction material. More specifically, it relates to a wet friction material used in the presence of a lubricating oil.

Conventionally, wet clutches and wet brakes using wet friction materials have been 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 clutch.
The wet clutch has a structure in which a plurality of wet friction materials and a plurality of separator plates are alternately arranged with a small clearance, and torque transmission / non-transmission is performed by pressing and separating the two. Further, lubricating oil is supplied into the clutch for the purpose of reducing the friction of the wet friction material in the pressure contact / 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 rotate relative to each other, and at that time, a torque called drag torque is generated.
Since this drag torque consumes unnecessary energy when the clutch idles, it is desired to reduce it as a measure for improving fuel efficiency, which has been rapidly developed in recent years. For example, in lock-up clutches, attempts have recently been made to increase the number of wet friction materials in order to improve the shifting feeling of the vehicle. Is manifested. For example, when the lubricating oil has a low temperature, the drag torque may increase remarkably, and it is required to reduce this. In this regard, the techniques of Patent Documents 1 and 2 below are known as techniques for reducing drag torque.

Japanese Unexamined Patent Publication No. 2005-228648 Japanese Unexamined Patent Publication No. 2016-001004

In Patent Document 1, when the intermediate portions of the segment pieces facing each other across the oil groove are symmetrically cut into a V-shape or a rectangular shape, the lubricating oil spreads in these V-shapes or a rectangular shape. It is disclosed that the friction material is supplied to the friction surface of the friction material base material in contact with the friction material, and the contact between the separator plate and the friction surface can be suppressed to suppress the drag torque (FIGS. 6 (b) and 6 (e)). [0055], [0056], [0062]).
In Patent Document 2, since the segment piece has a circumferential groove extending in the circumferential direction ending in the piece, the oil overflowing from the peripheral groove flows in the axial direction to generate pressure on the friction surface and separate the segment piece. It is disclosed that the drag torque can be reduced by producing the effect ([0014]).

However, it can be seen that the wet friction material of Patent Document 1 has a characteristic that the drag torque is reduced as the relative rotation speed increases as disclosed in FIG. On the other hand, it can be seen that the wet friction material of Patent Document 2 has a characteristic that the drag torque increases as the relative rotation speed increases as disclosed in FIG. As described above, there is no wet friction material capable of uniformly reducing the drag torque over the entire range from high rotation to low rotation. Therefore, it is necessary to realize the reduction of drag torque by selecting the optimum form according to various product requirements. That is, it is required that more options can be pooled, and more forms of drag torque reduction are required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wet friction material capable of achieving a reduction in drag torque by a form different from the conventional one.

The present invention is as follows.
[1] This wet friction material uses a ring-shaped core plate and
A wet friction material having a plurality of segment pieces arranged on the main surface of the core plate.
Each of the segment pieces has a substantially W shape.
The substantially W-shaped shape has a substantially rectangular original shape having a long side extending in the centrifugal direction of the core plate and a short side extending in the rotational direction of the core plate, and the right side portion of the long side or the left side portion of the long side. It has a shape in which two notch recesses are provided on one side and one notch recess is provided on the other side.
The two adjacent segment pieces of the plurality of segment pieces are convex formed by being sandwiched between the one notch recess of the first segment piece and the two notch recesses of the second segment piece. It is characterized in that the parts are face-to-face.
[2] The other form of the wet friction material is the wet friction material according to the above [1], in which the segment piece is located on the outer peripheral side of the core plate among the side portions having the one notched recess. The gist is that the corners are notched.
[3] The other form of the wet friction material is the core when a virtual straight line is drawn from the rotation center of the core plate toward the centrifugal direction in the wet friction material according to the above [1] or [2]. The gist is to have a virtual straight line that does not contact the segment piece from the inner peripheral side to the outer peripheral side of the plate.
[4] The other form of the wet friction material is the wet friction material according to any one of the above [1] to [3], in which the depth of cut of the notch recess is 1 / of the width of the original shape. The gist is that it is 2 or less.
[5] The other form of the wet friction material is the wet friction material according to any one of the above [1] to [4], wherein the segment piece crosses the segment piece in the rotation direction of the core plate. The gist is to have a groove.
[6] The gist of the other form of the wet friction material is that, in the wet friction material according to the above [5], one end of the groove includes the deepest notch position in the notch recess.
[7] The gist of the other form of the wet friction material is that the depth of the groove does not exceed the thickness of the segment piece in the wet friction material according to the above [5] or [6].

According to this wet friction material, a reduction in drag torque can be achieved by a form different from the conventional one.

It is a top view (a) which shows an example of this wet friction material (Examples 1 and 2), and is the perspective view (b) which shows a part thereof enlarged. It is a top view explaining the original form. It is a top view explaining the segment piece. It is a top view explaining the cut depth of a notch recess. It is a top view explaining the variation of a prototype and a segment piece. It is a top view explaining the variation of a prototype and a segment piece. It is a top view explaining the variation of a prototype and a segment piece. It is a top view explaining the variation of a prototype and a segment piece. It is a top view explaining an example of the correlation between a convex part and a notch concave part. It is a top view explaining another example of the correlation between a convex part and a notch concave part. It is a top view explaining another example of the correlation between a convex part and a notch concave part. It is a perspective view explaining an example of the groove which crossed the segment piece. It is a perspective view explaining another example of the groove across the segment piece. It is a top view explaining the groove across the segment piece. It is sectional drawing explaining the variation of the groove across the segment piece. It is explanatory drawing explaining the flow of lubricating oil on the surface of a segment piece. It is explanatory drawing explaining the outline shape of each wet friction material of Examples 1-7 and Comparative Examples 1-2. It is a graph which shows the correlation of the drag torque of each wet friction material of Example 1 and Comparative Examples 1 and 2. It is a graph which shows the correlation of the drag torque of each wet friction material of Examples 2-7.

Hereinafter, the present invention will be described with reference to the drawings. Further, when explaining the planar shape of each part in the present specification, the shape will be explained assuming that the parts are arranged at the 12 o'clock position on the clock face. Further, in the present specification, when the segment piece is described, it is assumed that the segment piece is placed at the 12 o'clock position of the clock face. Therefore, in a predetermined segment piece, "right" means the direction from the 9 o'clock position to the 3 o'clock position on the clock face, and "left" means the direction from the 3 o'clock position to the 9 o'clock position on the clock face. Means. Further, "up" means the direction from the 6 o'clock position to the 12 o'clock position on the clock face, and "down" means the direction from the 12 o'clock position to the 6 o'clock position on the clock face.

The wet friction material (1) of the present invention includes a ring-shaped core plate (2) and a ring-shaped core plate (2).
It has a plurality of segment pieces (3) arranged on the main surface (2a) of the core plate (2) (see FIG. 1).

[1] Core plate The core plate 2 has a ring shape. That is, it usually has a ring shape in which the center of the plate is opened. The center of the ring shape of the core plate 2 is the center of rotation P. The main surface 2a of the core plate 2 is a surface to which a plurality of segment pieces 3 are joined. The main surface 2a may be provided on only one surface of the core plate 2 or may be provided on both sides. That is, the segment piece 3 may be arranged on only one side of the core plate 2 or may be arranged on both sides of the core plate 2.

In addition to the main surface 2a, the core plate 2 may be provided with other necessary configurations as appropriate. Other configurations include, for example, engaging teeth. The engaging teeth can be provided so as to project from the inner peripheral surface or the outer peripheral surface of the core plate 2. Specifically, as shown in FIG. 1, it is possible to have the engaging teeth 8 projecting from the inner peripheral surface. The engaging teeth 8 can be provided so as to be able to mesh with the splines arranged on the outer periphery of the hub, which is the axis of rotation, with respect to the wet friction material 1.

The size of the core plate 2 and the like are not limited, and the correlation between the outer diameter and the inner diameter is not limited. For example, when the outer diameter is R ₁ (outer diameter) and the inner diameter is R ₂ (with engaging teeth 8). Is based on the inner peripheral surface excluding the engaging teeth 8), these ratios R ₁ / R ₂ can be 1 <R ₁ / R ₂ ≤ 10 and 1.05 ≤ R ₁ / R ₂ ≦ 5 can be set, and 1.1 ≦ R ₁ / R ₂ ≦ 3 can be set.
Further, when the thickness of the core plate 2 is D (mm), the thickness D is not limited, but can be, for example, 0.1 ≦ D (mm) ≦ 10 mm, and 0.3 ≦ D (mm). ) ≤ 7, and 0.5 ≤ D (mm) ≤ 5.
Further, the core plate 2 may be formed of any material, for example, various carbon steels (S35C, S55C, etc.), cold-rolled steel sheets (SPCC, SPCTT, etc.), low-carbon high-tensile steel (NCH780, etc.). Etc. can be used.

[2] Segment pieces Each of the segment pieces 3 has a substantially W shape (see FIGS. 1 and 3 to 8).
More specifically, this substantially W-shaped shape has a substantially rectangular original shape 5 having a long side 51 extending in _{the centrifugal direction D 1 of the core plate 2 and a short side 52 extending in the rotation direction D 2 of the core plate 2.} (See FIG. 2) has the shape provided with the following three notch recesses 61, 62 and 63 (see FIG. 3). That is, two notch recesses 61 and 62 are provided in one of the side portions 55 of the long side right side portion 55R or the long side left side portion 55L of the original shape 5, and one notch recess 63 is provided in the other side portion 55. Has a shape. That is, the substantially W-shape has two notch recesses 61 and 62 on one side portion 55 and one notch recess 63 on the other side portion 55.
All of these notch recesses 61, 62, and 63 are preferably substantially trapezoidal, and particularly preferably narrow trapezoidal in which the opening width narrows toward the inside of the segment piece 3.

Although it is not clear why the drag torque can be reduced by having the substantially W-shaped segment piece 3 having these notch recesses 61, 62 and 63, as shown in FIG. 16, the lubricating oil is added to the arrow T. _It is considered that this is because it can easily flow along 1 and arrow T _{2 and can be rectified.} More specifically, by having the notch recess 62, the flow of the lubricating oil can be blocked by the notch recess 62, and the lubricating oil can be run onto the friction surface of the segment piece 3. At this time, since the long side right portion 55R having two cutout recess (61 and 62), the notch recesses 62 are positioned shifted to the outer peripheral side S _O. As a result, the lubricating oil that has run on the friction surface through the notch recess 61 will escape to the notch recess 63. By diagonally facing the notch recess 62 and the notch recess 63 in this way, the flow path of the lubricating oil riding on the friction surface can be shortened. As a result, while supplying sufficient lubricating oil to the friction surface, it is possible to shorten the time for the lubricating oil to stay on the friction surface by shortening the flow path thereof. It can be considered that such an action contributes to the reduction of the drag torque.

Similarly, by having the notch recess 61, the flow of the lubricating oil can be blocked by the notch recess 61, and the lubricating oil can be carried onto the friction surface of the segment piece 3. At this time, since the long side right portion 55R having two cutout recess (61 and 62), the notch recesses 61 are positioned shifted to the outer peripheral side S _O. Thus, lubricating oil rides to the friction surface via the cutout recess 61 is made to escape to the short side 52 of the outer peripheral side S _O, it is possible to shorten the flow path. Further, when the notch portion 67 is provided, the flow path through which the lubricating oil riding on the notch recess 61 flows through the friction surface can be further shortened. By making the notch recess 61 and the notch 67 diagonally opposed to each other in this way, the flow path of the lubricating oil riding on the friction surface can be shortened. As a result, while supplying sufficient lubricating oil to the friction surface, the flow path thereof can be shortened and the time for the lubricating oil to stay on the friction surface can be shortened.

The dimensions of each part are not limited, but can be, for example, as follows (see FIGS. 4a and 4b).
_{The depth of cut (WO61} , _WO62 and _WO63 ) of the notch recesses (61, 62 and 63) can be 1/2 or less of the width of the original shape 5. Within this range, a high drag torque reduction effect can be obtained while securing the friction area. _{The depth of cut (WO61} , _WO62 and _WO63 ) of the notch recesses (61, 62 and 63) is preferably 0.25 to 0.30, which is the width of the original shape 5. It is more preferable to set it to ~ 0.28.

More specifically, cutting depth _{W O61} of cutout recess 61 _{is W O61 ≦ {W D61 × 1} /2}. The notch depth W _O61 of the notch recess 61 is a linear distance between the outer circumference 5S of the original shape 5 and the bottom 61B of the notch recess 61. The bottom portion 61B is the deepest cut portion in the notch recess 61, and when the bottom portion 61B has a portion having the same cut depth as shown in FIG. 4A, the bottom portion 61B is cut at the center of the bottom portion 61B. The filling depth W _O61 is measured. Further, the width _WD61 of the prototype 5 is the width of the prototype 5 at the position where the bottom portion 61B is measured. Accordingly, as shown in FIG. 4 (a), original 5, although a substantially rectangular shape, the short side 52 _I of the inner circumferential side S _I is shorter than the short sides 52 _O of the outer circumferential side S _O is , The width of the original shape 5 is different for each cutting depth W _O61 , cutting depth W _{O 62,} and cutting depth W _{O 63} .

Further, the cutting depth W _O62 of the notch recess 62 is W _{O 62} ≦ {WD62 × 1/2}. The notch depth W _O 62 of the notch recess 62 is a linear distance between the outer circumference 5S of the original shape 5 and the bottom 62B of the notch recess 62. The bottom portion 62B is the deepest cut portion in the notch recess 62, and when the bottom portion 62B has a portion having the same cut depth as shown in FIG. 4A, the bottom portion 62B is cut at the center of the bottom portion 62B. The filling depth W _O62 is measured. Further, the width _WD62 of the prototype 5 is the width of the prototype 5 at the position where the bottom portion 62B is measured.
Similarly, cutting depth _{W O63} of cutout recess 63 _{is W O63 ≦ {W D63 × 1} /2}. The notch depth W _O 63 of the notch recess 63 is a linear distance between the outer circumference 5S of the original shape 5 and the bottom 63B of the notch recess 63. The bottom portion 63B is the deepest cut portion in the notch recess 63, and when the bottom portion 63B has a portion having the same cut depth as shown in FIG. 4A, the bottom portion 63B is cut at the center of the bottom portion 63B. The filling depth W _O63 is measured. Further, the width _WD63 of the prototype 5 is the width of the prototype 5 at the position where the bottom 63B is measured.

Further, the notch recesses (61, 62 and 63) have two notch recesses 61, 62 in one side portion 55 (long side right side portion 55R or long side left side portion 55L) of the original shape 5, and the other. It suffices to have one notch recess 63 in the side portion 55, and the forming position of each is not limited.
Sonouede, for example, notched recess 62 may be positioned on the inner peripheral side S _I further than the height position of the half of the height H ₃ of the segment piece. More specifically, the linear distance between the _{position where the depth of cut W O} 62 of the notch recess 62 is the deepest (X ₆₂ ) and the height position of 1/2 of the height _{H 3 of the segment piece (X HF).} H ₆₂ is preferably 20% or more of the height H ₃ of the segment piece (see FIG. 4b). That is, it is preferable that _{H 62} / H _{3 ≧ 0.20.} This value (H ₆₂ / H ₃ ) is further _{preferably 0.20 ≦ H 62} / H ₃ ≦ 0.30, and more preferably 0.23 ≦ H ₆₂ / H ₃ ≦ 0.27.

Also, the notch recesses 61 may further be positioned on the outer peripheral side S _O than the height position of the half of the height H ₃ of the segment piece. More specifically, the linear distance between the _{position where the depth of cut W O} 61 of the notch recess 61 is the deepest (X ₆₁ ) and the height position of 1/2 of the height _{H 3 of the segment piece (X HF).} H ₆₁ is preferably 35% or less of the height H ₃ of the segment piece (see FIG. 4b). That is, it is preferable that _{H 61} / H _{3 ≦ 0.35.} This value (H ₆₁ / H ₃ ) is further _{preferably 0.20 ≦ H 61} / H ₃ ≦ 0.30, and more preferably 0.23 ≦ H ₆₁ / H ₃ ≦ 0.27.

Further, the notch recess 63 can be located at a position including a height position of 1/2 of the height _{H 3 of the segment piece.} More specifically, the deepest position cutting depth _{W O63} cutout recess 63 _{(X 63),} the most protruding position of the convex portion 66 disposed on the outer peripheral side _{S O} of the cutout recess 63 _{(X 66)} The linear distance H ₆₃ between and is preferably 35% or less of the height H _{3 of the segment piece (see FIG. 4b).} That is, it is preferable that _{H 63} / H _{3 ≦ 0.35.} This value (H ₆₃ / H ₃ ) is further _{preferably 0.25 ≦ H 63} / H ₃ ≦ 0.35, and more preferably 0.28 ≦ H ₆₃ / H ₃ ≦ 0.32.

Further, the notch angles (θ _61a , θ _62a and θ _63b ) of the notch recesses (61, 62 and 63), the relief angles (θ _61b , θ _62b and θ _63a ) of the notch recesses (61, 62 and 63), and the notch. The notch angle (θ ₆₇ ) of 67 is preferably 40 degrees or more. Each of these angles may be the same or different. By setting each angle in the above range, a high drag torque reduction effect can be obtained. These angles are further preferably 43 degrees or more and 65 degrees or less, more preferably 45 degrees or more and 60 degrees or less, and particularly preferably 45 degrees or more and 55 degrees or less (see FIG. 4b).

Examples of variations of the segment piece 3 as described above include FIGS. 5 (b to c).
)-The ones shown in FIGS. 8 (b-c) can be exemplified. The wet friction material 1 may have a plurality of only one of these segment pieces 3, or two or more of these may be used in combination.
Among these, the segment piece 3 shown in FIG. 5 (3A and 3B) is the length of right and left long side 51 are the same, a length of a short side 52 of the inner circumferential side S _I and the outer S _O is the same The original shape 5 (Fig. 5a) is a rectangle with four corners at right angles. The segment piece 3A (FIG. 5b) has two notch recesses 61 and 62 in the long side right side portion 55R and one notch recess 63 in the long side left side portion 55L. Furthermore, the segment piece 3B (Fig. 5b) has, in addition to a segment piece 3A as well as cutout recess 61, 62 and 63, corners positioned on the outer peripheral side _{S O} of the core plate 2 of the long side left portion 55L The portion 67 has a notched shape. That is, the segment piece 3B (Fig. 5b), the outer peripheral side S _O to have a notch 67 (conveniently corner 67 and notch 67 of the long side left portion 55L will be described using the same reference numerals. The same applies below).

Further, the segment piece 3 (3A and 3B) shown in FIG. 6 is the length of right and left long side 51 are the same, the length of the short side 52 of the inner circumferential side S _I and the outer S _O is the same The original shape 5 (FIG. 6a) is a substantially rectangular shape in which the four corners are chamfered into an R shape. The segment piece 3A (FIG. 6b) has two notch recesses 61 and 62 in the long side right side portion 55R and one notch recess 63 in the long side left side portion 55L. Furthermore, the segment piece 3B (Fig. 6b) has, in addition to a segment piece 3A as well as cutout recess 61, 62 and 63, corners positioned on the outer peripheral side _{S O} of the core plate 2 of the long side left portion 55L The portion 67 has a notched shape. That is, the segment piece 3B (Fig. 6b) has a notch 67 on the outer circumferential side _{S O} of the long side left portion 55L. In addition, the notch recesses 61, 62 and 63 and the corners forming the notch 67 are all chamfered and gently curved.

Furthermore, the segment piece 3 shown in FIG. 7 (3A and 3B) is the length of right and left long side 51 are the same, shorter than the short side 52 short side 52 of the outer peripheral side S _O of the inner circumferential side S _I The original shape 5 (FIG. 7a) is a substantially rectangular shape in which the four corners are not chamfered into an R shape. The segment piece 3A (FIG. 7b) has two notch recesses 61 and 62 in the long side right side portion 55R and one notch recess 63 in the long side left side portion 55L. Furthermore, the segment piece 3B (Fig. 7b), in addition to having a segment piece 3A as well as cutout recess 61, 62 and 63, corners positioned on the outer peripheral side _{S O} of the core plate 2 of the long side left portion 55L The portion 67 has a notched shape. That is, the segment piece 3B (Fig. 7b) has a notch 67 on the outer circumferential side _{S O} of the long side left portion 55L.

In the original 5 shown in Figures 7a and 7b, the longer the length of the short side 52 (the short side of the outer peripheral side S _O) and L _1, the shorter the shorter side 52 (the inner circumferential side S _I short of When the length of the side) is L ₂ , it is preferable that 0.8 ≦ L ₂ / L _{1 ≦ 1.} Further, when the internal angle of the original shape 5 is non-right angle, the size of the internal angle is preferably 80 degrees or more and 100 degrees or less.

Further, the segment piece 3 shown in FIG. 8 (3A and 3B) is the length of right and left long side 51 are the same, shorter than the short side 52 short side 52 of the outer peripheral side S _O of the inner circumferential side S _I The original shape 5 (FIG. 8a) is a substantially rectangular shape in which the four corners are chamfered into an R shape. The segment piece 3A (FIG. 8b) has two notch recesses 61 and 62 in the long side right side portion 55R and one notch recess 63 in the long side left side portion 55L. Furthermore, the segment piece 3B (Fig. 8b), in addition to having a segment piece 3A as well as cutout recess 61, 62 and 63, corners positioned on the outer peripheral side _{S O} of the core plate 2 of the long side left portion 55L The portion 67 has a notched shape. That is, the segment piece 3B (FIG. 8b) has a notch 67 on the outer circumferential side _{S O} of the long side left portion 55L. In addition, the notch recesses 61, 62 and 63 and the corners forming the notch 67 are all chamfered and gently curved.

Further, in the present wet friction material 1, the plurality of segment pieces 3 have a notch recess 63 included in the first segment piece 301 and a second segment piece 302 in each of the two adjacent segment pieces 3. The convex portion 65 formed between the two notch recesses 61 and 62 having the same is arranged so as to face each other (see FIGS. 9 to 11). That is, it can be said that the bottom portion 63B of the notch recess 63 of the first segment piece 301 and the top portion 65T of the convex portion 65 of the second segment piece 302 are arranged facing each other.

In this way, the notch recess 63 of the first segment piece 301 and the convex portion 65 of the second segment piece 302 face each other, so that the lubricating oil easily flows and is rectified on the surface of the wet friction material 1 ( see FIG. 16, the arrows _{T 1} and arrow _{T 2)} can be obtained. That is, by the above face, it is possible to ensure a flow path capable of forming a flow along the arrow T _1, also can ensure a flow path capable of forming a flow along the arrow T _2.
The partitioned gap between the two adjacent segment pieces 3 functions as an oil groove 4. The oil groove 4 is a groove that serves as a flow path for lubricating oil.

Although specific forms of face-to-face above are not limited, if minus the imaginary straight line toward the rotation center P of the core plate 2 in the centrifugal direction D _1, the outer peripheral side S _O from the inner circumferential side S _I of the core plate 2 It is preferable that the shape has a virtual straight line L that does not come into contact with the segment piece 3 (see FIGS. 9 and 10). This configuration while suppressing the deterioration of the friction area can flow passage capable of forming a flow along the arrow T ₁ (see shaded portions of FIGS. 9-11) is greater ensured.

More specifically, embodiments of Figure 11, when the minus imaginary straight line toward the rotation center P of the core plate 2 in the centrifugal direction D _1, from the inner circumferential side S _I of the core plate 2 to the outer peripheral side S _O , Shows a form having only a virtual straight line L'contacting the segment piece 3. Thus, when the gap between the segment pieces 301 and 302 is narrow, there is the flow path (hatched portion in FIG. 11) it is also narrow and short tends capable of forming a flow along the arrow T _1, the rectifying effect of the aforementioned It tends to be difficult to exert.

In contrast, as in the embodiment of FIG. 10, when the minus imaginary straight line, from the inner circumferential side S _I of the core plate 2 to the outer peripheral side S _O, have a virtual straight line L which is not in contact with the segment piece 3 if possible, a flow path capable of forming a flow along the arrow T ₁ (shaded portion in FIG. 10) tend to be secured wide and long, it is easy to exhibit a rectifying effect as described above.
Furthermore, as in the embodiment of FIG. 9, when the minus imaginary straight line, when the inner peripheral side S _I of the core plate 2 to the outer peripheral side S _O, wide enough to form a virtual straight line L which is not in contact with the segment piece 3 is wide the, there flow path can form a flow along the arrow T ₁ (the shaded portion in FIG. 9) to the wider and longer securable tendency becomes easy further exhibit a rectifying effect as described above. Distance _{L D} of _{L 301} and (L that closer to the rightmost) _{L 302} and (L that closer to the leftmost) in FIG. 9 (inner circumferential side _{S I} of the segment piece 3) include, but are not limited to, for example, 0 ≦ L _D (mm) ≤ 3.0 can be set.

Further, the segment piece 3 can have a groove 7 (hereinafter, also simply referred to as “crossing groove”) that crosses the segment piece 3 in _{the rotation direction D 2 of the core plate 2 (see FIGS. 12 to 14).} In this wet friction material 1, the segment piece 3 does not have to have the cross groove 7, but the one having the cross groove 7 has a better drag torque reduction effect than the case where the cross groove 7 is not provided. Can be demonstrated.
As shown in FIGS. 12, 15a, 15b and 15c, the cross groove 7 may be a cross groove 7 having a depth that does not divide the segment piece 3, and is shown in FIGS. 13, 15d and 15e. As shown, it may be a cross groove 7 that divides the segment piece 3. Of these, the former is preferable. That is, it is preferable that the depth of the cross groove 7 does not exceed the thickness of the segment piece 3.

Further, the cross-sectional shape of the cross groove 7 is not limited, but is exemplified in FIG. 15, for example. That is, the shape can be a constant groove width regardless of the groove depth (FIG. 15a), and the groove width can be narrowed as the groove depth becomes deeper (FIG. 15b, FIG. 15c and FIG. 15e), and the shape can have a constant groove width regardless of the groove depth (FIG. 15c).
The method of forming these transverse grooves 7 is not limited, but for example, the transverse groove 7 having the cross-sectional shape shown in FIGS. 15a, 15b and 15c is a wet friction material 1 in a state where the segment piece 3 is joined to the main surface 2a. Can be formed by pressing against. On the other hand, the cross groove 7 having the cross-sectional shape shown in FIGS. 15d and 15e can be formed by cutting the wet friction material 1 in a state where the segment piece 3 is joined to the main surface 2a.

Further, although any number of cross-grooves 7 may be formed at any portion of the segment piece 3, it is preferable that one segment piece 3 has one or more and three or less. If the number is three or less, an excellent drag torque reduction effect can be obtained while suppressing a decrease in the friction area. Further, the forming position of each crossing groove 7 is not limited, but it is preferable to have it at a position corresponding to the notch recesses (61, 62 and 63). Specifically, it is preferable that one end of the cross groove 7 includes the position of the deepest cut in the notch recess.
More specifically, as shown in FIG. 14, the cross groove 7 corresponding to the notch recess 61 is formed at a position where one end thereof includes the deepest notch position 61B of the notch recess 61. preferable. Similarly, it is preferable that one end of the cross groove 7 corresponding to the notch recess 62 is formed at a position including the deepest notch position 62B of the notch recess 62. Similarly, it is preferable that one end of the cross groove 7 corresponding to the notch recess 63 is formed at a position including the deepest notch position 63B of the notch recess 63.

In the wet friction material 1, the number of segment pieces 3 arranged on one main surface 2a of the core plate 2 is not limited, but can be, for example, 10 or more and 100 or less. This number is preferably 15 or more and 90 or less, more preferably 20 or more and 80 or less, and particularly preferably 25 or more and 60 or less.

The material constituting these segment pieces 3 is not limited, and for example, a paper machine containing a base fiber and a filler and hardened with a curable resin can be used.
Among these, as the base fiber, various synthetic fibers, regenerated fibers, inorganic fibers, natural fibers and the like can be used. Specifically, cellulose fibers (pulp), acrylic fibers, aramid fibers and the like are preferable. Further, as the filler, cashew dust as a friction modifier, graphite and / or molybdenum disulfide as a solid lubricant, diatomaceous earth as an extender pigment, or the like can be used. Only one of these may be used, or two or more thereof may be used in combination. Further, as the thermosetting resin, a phenol resin and / or a modified resin thereof can be used.
Further, the segment piece 3 is usually joined and fixed to the main surface 2a of the core plate 2, but the joining method with the core plate 2 is not limited, and heat fusion, an adhesive or the like is used. A method such as sticking (adhesion) can be used.

Hereinafter, the present invention will be described by way of examples. The description common to each embodiment will be omitted.
[1] Effect of reducing drag torque due to segment piece shape (1) Adjustment of wet friction material [Example 1]
The wet friction material of Example 1 was obtained using the following configuration (see FIGS. 1 and 17a).
Core plate: A flat ring shape (outer diameter R ₁ = 181 mm, inner diameter R ₂ = 149 mm, ratio R ₁ / R ₂ = 1.21), and spline teeth 8 (engagement teeth 8) protruding from the inner circumference. ).
Segment piece: It has a substantially W shape with a notch 67. This substantially W-shape has a substantially rectangular original shape 5 (FIG. 8a) having a long side 51 extending in _{the centrifugal direction D 1 of the core plate 2 and a short side 52 extending in the rotation direction D 2 of the core plate 2.} The shape is such that two notch recesses 61 and 62 are provided in the long side right side portion 55R, and one notch recess 63 is provided in the long side left side portion 55L (FIG. 8c). Further, W _O61 / W _D61 ≤ 0.5, _{WO 62} / W D62 ≤ 0.5, _{WO 63} / W _D63 ≤ 0.5, and θ _61a , θ _61b , θ _61a, and θ ₆₇ are Both are 50 degrees, H ₆₁ / H ₃ is 0.30, H ₆₂ / H ₃ is 0.25, H ₆₃ / H ₃ is 0.30, and W is 10.7 mm. ..
Arrangement: The segment piece 3 has a form in which 45 pieces are joined to one side of the core plate 2, and both adjacent segment pieces face each other in a form in which the notch recess 63 and the convex portion 65 have a virtual straight line L. They are evenly arranged in a ring shape.

[Comparative Example 1]
A wet friction material of Comparative Example 1 was obtained using the following configuration (see FIG. 17 g).
Core plate: Same as Example 1.
Segment piece: The shape of the segment piece 3 of the first embodiment is the same as that of the original shape 5 (FIG. 8a) without the notch recesses 61, 62 and 63 and the notch 67.
Arrangement: The segment pieces are in the form of 45 pieces joined to one side of the core plate 2 and are evenly arranged in a ring shape.

[Comparative Example 2]
A wet friction material of Comparative Example 2 was obtained using the following configuration (see FIG. 17h).
Core plate: Same as Example 1.
Segment piece: a shape having a notch formed by cutting the corner portion of the outer peripheral side S _O of the long side right portion 55R and a long side left portion 55L of the original 5 of Example 1 (Figure 8a).
Arrangement: The segment pieces are in the form of 45 pieces joined to one side of the core plate 2 and are evenly arranged in a ring shape.

Each segment piece 3 is made by applying a curable resin to a papermaking 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 soil. It is impregnated and then cured. Then, each segment piece is joined to the main surface 2a of the core plate 2 by pressure heating.

(2) Measurement of drag torque Using four wet friction materials of Example 1 and Comparative Example 1-2 of (1) above, using a SAE friction tester under the following conditions, the drag torque (N. m) was measured. The obtained results are shown in a graph in FIG.
Lubricating oil: Bonnock M680 (manufactured by JXTG Energy), oil temperature: 25 ° C, oil amount: 500 mL / min (axial lubrication / full dip), pack clearance: 0.18 mm / sheet, relative rotation speed fixed at 950 rpm

(3) Effect of Example From the result of FIG. 18, as compared with the wet friction material in which the shape of the segment piece is kept in its original shape as in Comparative Example 1, the corner portion on the outer peripheral side is cut as in Comparative Example 2. It can be seen that the drag torque can be suppressed to 30% smaller in the wet friction material using the segment piece in which the discharge property of the lubricating oil is improved by the lack.
Further, it can be seen that when the wet friction material of Example 1 which is an aspect of the present invention is used, a remarkable reduction of drag torque of 28.6% can be achieved as compared with Comparative Example 2. This corresponds to a value of 50% of the drag torque of Comparative Example 1 when compared with Comparative Example 1. As described above, by using the segment piece having a specific shape, it is possible to achieve a remarkable reduction in drag torque as compared with the conventional case.

[2] Effect of reducing drag torque by presence / absence of crossing groove and its arrangement (1) Adjustment of wet friction material [Example 2]
The wet friction material of Example 2 was obtained using the following configuration (see FIGS. 1 and 17a).
Core plate: Flat ring shape (outer diameter R ₁ = 165.1 mm, inner diameter R ₂ = 134.3 mm, ratio R ₁ / R ₂ = 1.23), spline teeth 8 protruding from the inner circumference (outer diameter R 1 = 165.1 mm, inner diameter R 2 = 134.3 mm, ratio R 1 / R 2 = 1.23) It has engaging teeth 8).
Segment piece: It has a substantially W shape with a notch 67. This substantially W-shape has a substantially rectangular original shape 5 (FIG. 8a) having a long side 51 extending in _{the centrifugal direction D 1 of the core plate 2 and a short side 52 extending in the rotation direction D 2 of the core plate 2.} The shape is such that two notch recesses 61 and 62 are provided in the long side right side portion 55R, and one notch recess 63 is provided in the long side left side portion 55L (FIG. 8c). Further, W _O61 / W _D61 ≤ 0.5, _{WO 62} / W D62 ≤ 0.5, _{WO 63} / W _D63 ≤ 0.5, and θ _61a , θ _61b , θ _61a, and θ ₆₇ are Both are 50 degrees, H ₆₁ / H ₃ is 0.30, H ₆₂ / H ₃ is 0.25, H ₆₃ / H ₃ is 0.30, and W is 9.5 mm. .. It should be noted that all the segment pieces 3 do not have the cross groove 7.
Arrangement: The segment piece 3 has a form in which 45 pieces are joined to one side of the core plate 2, and both adjacent segment pieces face each other in a form in which the notch recess 63 and the convex portion 65 have a virtual straight line L. They are evenly arranged in a ring shape.

[Example 3]
The wet friction material of Example 3 was obtained using the following configuration (see FIG. 17b).
Core plate: Same as Example 2.
Segment piece: It differs from the second embodiment only in that the cross groove 7 is provided. One crossing groove 7 is provided for all the segment pieces 3 by pressing (pressing is added after joining to the core plate 2). Therefore, each crossing groove 7 has a depth that does not exceed the thickness of the segment piece. One end of each transverse groove 7 includes the deepest notch position 63B of the notch recess 63.
Sequence: The same as in Example 2.

[Example 4]
The wet friction material of Example 4 was obtained using the following configuration (see FIG. 17c).
Core plate: Same as Example 2.
Segment piece: It differs from the second embodiment only in that the cross groove 7 is provided. Three crossing grooves 7 are provided for all the segment pieces 3 by pressing (pressing is added after joining to the core plate 2). Therefore, each crossing groove 7 has a depth that does not exceed the thickness of the segment piece. One end of each crossing groove 7 includes the deepest notch positions 61B, 62B, 63B of the notch recesses 61, 62, 63, respectively.
Sequence: The same as in Example 2.

[Example 5]
The wet friction material of Example 5 was obtained using the following configuration (see FIG. 17d).
Core plate: Same as Example 2.
Segment piece: It differs from the second embodiment only in that the cross groove 7 is provided. One crossing groove 7 is provided for all the segment pieces 3 by pressing (pressing is added after joining to the core plate 2). Therefore, each crossing groove 7 has a depth that does not exceed the thickness of the segment piece. Further, regular crossing grooves 701 to 703 are provided for one set of segment pieces that are adjacent to each other clockwise in the order of the first segment piece 301, the second segment piece 302, and the third segment piece 303. .. The cross groove 7 is repeated with the cross grooves 701 to 703 as one cycle. Of these, the cross groove 701 is provided in the first segment piece 301, and one end thereof includes the deepest notch position 61B of the notch recess 61. The cross groove 702 is provided in the second segment piece 302, and one end thereof includes the deepest notch position 63B of the notch recess 63. Further, the cross groove 703 is provided in the third segment piece 303, and one end thereof includes the deepest notch position 62B of the notch recess 62.
Arrangement: The same as in Example 2, the first to third segment pieces (301 to 303) are arranged so as to be repeated as one cycle.

[Example 6]
The wet friction material of Example 6 was obtained using the following configuration (see FIG. 17e).
Core plate: Same as Example 2.
Segment piece: It differs from the second embodiment only in that the cross groove 7 is provided. Two crossing grooves 7 are provided for all the segment pieces 3 by pressing (pressing is added after joining to the core plate 2). Therefore, each crossing groove 7 has a depth that does not exceed the thickness of the segment piece. One end of each crossing groove 7 includes the deepest notch positions 61B and 62B of the notch recesses 61 and 62, respectively.
Sequence: The same as in Example 2.

[Example 7]
The wet friction material of Example 7 was obtained using the following configuration (see FIG. 17f).
Core plate: Same as Example 7.
Segment piece: It differs from the second embodiment only in that the cross groove 7 is provided. Regular crossing grooves 701 and 703 were provided for one set of segment pieces that were adjacent to each other clockwise in the order of the first segment piece 301, the second segment piece 302, and the third segment piece 303. The cross groove 7 is repeated with the cross grooves 701 and 703 as one cycle. Of these, the cross groove 701 is provided in the first segment piece 301, and one end thereof includes the deepest notch position 62B of the notch recess 62. The second segment piece 302 located to the right of the first segment piece 301 clockwise does not have the cross groove 7. Further, the third segment piece 303 located to the right of the second segment piece 302 clockwise has a cross groove 703. The cross groove 703 is provided in the third segment piece 303, and one end thereof includes the deepest notch position 61B of the notch recess 61.
Arrangement: The same as in Example 2, the first to third segment pieces (301 to 303) are arranged so as to be repeated as one cycle.

(2) Measurement of drag torque Using four wet friction materials of Example 1 and Comparative Example 1-2 of (1) above, using a SAE friction tester under the following conditions, the drag torque (N. m) was measured. The obtained results are shown in a graph in FIG.
Lubricating oil: Bonnock M680 (manufactured by JXTG Energy), oil temperature: 25 ° C, oil amount: 500 mL / min (axial lubrication / full dip), pack clearance: 0.18 mm / sheet, relative rotation speed fixed at 950 rpm

(3) Effect of Example From the result of FIG. 20, it can be seen that the drag torque can be further reduced by providing the cross groove 7 with respect to the segment piece of the wet friction material of Example 1 which is the aspect of the present invention.
Specifically, by providing the crossing groove of the embodiment of the third embodiment, it is possible to achieve a drag torque reduction of 20.6% as compared with the second embodiment having no crossing groove. Further, in the cross groove of the embodiment of the fourth embodiment, a drag torque reduction of 31.7% can be achieved as compared with the second embodiment. Further, in the cross groove of the embodiment of the fifth embodiment, a drag torque reduction of 39.7% can be achieved as compared with the second embodiment. Further, in the cross groove of the embodiment of the sixth embodiment, a drag torque reduction of 41.3% can be achieved as compared with the second embodiment. Further, in the cross groove of the aspect of Example 7, a drag torque reduction of 44.4% can be achieved as compared with Example 2.

In the present invention, the examples are not limited to those shown in the above specific examples, and examples can be variously modified within the scope of the present invention according to the purpose and application.

The application of the wet friction material of the present invention is not particularly limited, and is widely applied to, for example, automobiles (four-wheeled automobiles, two-wheeled automobiles, etc.), railroad vehicles, ships, airplanes, and the like. Of these, as automobile supplies, they are preferably used for automatic transmissions (automatic transmissions, ATs), manual transmissions, lockup clutches, torque limiters and the like. Only one piece of the wet friction material may be used in the apparatus, or a plurality of pieces may be used, but it is preferable that a plurality of pieces are used. The more the wet friction material is used in one device, the greater the effect can be obtained in terms of integration. That is, the drag torque can be reduced more effectively in a device such as a wet multi-plate clutch in which the number of wet friction materials used is large.

1; Wet friction material,
2; core plate, 2a; main surface,
3; segment piece,
3A, 3B; segment piece,
301, 302, 303; segment piece,
4; Oil groove,
5; Prototype, 5S; Outer circumference of Prototype,
51; long side, 52; short side,
55; side, 55L; left side of long side, 55R; right side of long side,
61; notch recess, 61B; bottom,
62; notch recess, 62B; bottom,
63; notch recess, 63B; bottom,
65, 66; convex, 65T; top,
67; Corner (notch),
7; Groove (crossing groove), 701; Crossing groove, 702; Crossing groove, 703; Crossing groove,
8; spline teeth (engaged teeth),
D ₁ ; Centrifugal direction, D ₂ ; Rotation direction,
S _I; inner periphery side, _{S O;} the outer peripheral side,
P; center of rotation.

Claims (8)

A ring-shaped core plate and
A wet friction material having a plurality of segment pieces arranged on the main surface of the core plate.
Each of the segment pieces has a substantially W shape.
The substantially W-shaped shape has a substantially rectangular original shape having a long side extending in the centrifugal direction of the core plate and a short side extending in the rotational direction of the core plate, and the right side portion of the long side or the left side portion of the long side. It has a shape in which two notch recesses are provided on one side and one notch recess is provided on the other side.
The two adjacent segment pieces of the plurality of segment pieces are convex formed by being sandwiched between the one notch recess of the first segment piece and the two notch recesses of the second segment piece. The department is facing each other,
A wet friction material having a virtual straight line that does not contact the segment piece from the inner peripheral side to the outer peripheral side of the core plate when a virtual straight line is drawn from the center of rotation of the core plate toward the centrifugal direction. .. The wet friction material according to claim 1, wherein the segment piece has a shape in which a corner portion located on the outer peripheral side of the core plate is notched among the side portions having the one notched recess. A ring-shaped core plate and
A wet friction material having a plurality of segment pieces arranged on the main surface of the core plate.
Each of the segment pieces has a substantially W shape.
The substantially W-shape has a substantially rectangular original shape having a long side extending in the centrifugal direction of the core plate and a short side extending in the rotation direction of the core plate, and the right side portion of the long side or the left side portion of the long side. It has a shape in which two notch recesses are provided on one side and one notch recess is provided on the other side.
The segment piece has a shape in which only the corner portion located on the outer peripheral side of the core plate is notched out of the side portions having the one notched recess.
The two adjacent segment pieces of the plurality of segment pieces are convex formed by being sandwiched between the one notch recess of the first segment piece and the two notch recesses of the second segment piece. A wet friction material characterized in that the parts face each other. The wet friction according to claim 3 , wherein when a virtual straight line is drawn from the center of rotation of the core plate toward the centrifugal direction, the core plate has a virtual straight line that does not contact the segment piece from the inner peripheral side to the outer peripheral side. Material. The wet friction material according to any one of claims 1 to 4 , wherein the depth of cut of the notch recess is ½ or less of the width of the original shape. The wet friction material according to any one of claims 1 to 5 , wherein the segment piece has a groove that crosses the segment piece in the rotation direction of the core plate. The wet friction material according to claim 6 , wherein one end of the groove includes a position of the deepest cut in the notch recess. The wet friction material according to claim 6 or 7 , wherein the depth of the groove does not exceed the thickness of the segment piece.

Images