JP2020079648A - Wet friction plate and wet multi-plate clutch device including the same - Google Patents

Abstract

A wet friction plate and a wet multi-plate clutch device including the wet friction plate are provided, which can improve the dischargeability of lubricating oil adhering to the surfaces of friction materials. A wet friction plate (200) comprises an oil groove (203) and a friction material (210) on a flat annular core (201). Friction material 210 has friction sliding surface 213 and lubricating oil recess 214 formed on the surface of porous layer 211 . The lubricating oil recesses 214 are formed on a smooth continuous surface without sharp edges such as corners, and are recessed from the friction sliding surface 213 to form a plurality of recesses. This porous layer 211 has cavities 212 formed at the same formation rate in the portion forming the friction sliding surface 213 and the portion forming the lubricating oil recess 214 . [Selection drawing] Fig. 2

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet friction plate used in lubricating oil, and in particular, it is arranged between a prime mover and a driven body that is rotationally driven by the prime mover to transmit or cut off the driving force of the prime mover to the driven body. The present invention relates to a wet friction plate suitable for a wet multi-plate clutch device and a wet multi-plate clutch device including the wet friction plate.

  BACKGROUND ART Conventionally, a vehicle such as a four-wheeled vehicle or a two-wheeled vehicle is equipped with a wet multi-plate clutch device for transmitting or interrupting a rotational driving force of a prime mover such as an engine to a driven body such as a wheel. Generally, in a wet multi-plate clutch device, two plates arranged in a lubricating oil so as to face each other are pressed against each other to transmit or cut off a rotational driving force.

  In this case, one of the two plates is a wet friction plate in which a friction material is provided on the surface of a flat plate-shaped core metal along the circumferential direction. For example, Patent Document 1 below discloses a wet friction material (hereinafter referred to as “wet friction plate”) in which a papermaking groove (hereinafter referred to as “lubricant oil recess”) formed in a concave shape on the surface of the friction material is formed. ing. This allows the wet friction plate to easily discharge the lubricating oil adhering to the surface of the wet friction plate and reduce the drag torque.

JP, 2007-263203, A

  However, in the wet friction plate described in Patent Document 1, the supporting layer of the lubricating oil recess into which the lubricating oil enters is compressed and deformed by the press work or cutting work for forming the lubricating oil recess, and the lubricating oil is discharged. Sex tends to be low. Therefore, in the conventional wet friction plate, there is a problem that the lubricating oil is difficult to be discharged especially when the lubricating oil has a low temperature or when the contact pressure between the wet friction plate and the clutch plate is low.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a wet friction plate and a wet multi-plate including the wet friction plate capable of improving the discharge property of the lubricating oil adhering to the surface of the friction material. To provide a clutch device.

  To achieve the above object, a feature of the present invention is that a surface of a porous layer having a plurality of cavities is formed with a friction sliding surface and a plurality of lubricating oil recesses recessed in the friction sliding surface. In a wet friction plate including a friction material and a core metal formed in a flat plate annular shape and provided along the circumferential direction, the friction material has a sharp corner such as a corner on the surface of the lubricating oil recess. It is formed on a smoothly continuous surface without a sharpened shape, and the porous layer forming the lubricating oil recess and the porous layer forming the friction sliding surface have the same cavity formation rate. Is being done.

  According to the features of the present invention configured as described above, the wet friction plate is formed into a smooth continuous surface without sharp points such as corners on the surface of the lubricating oil recess and Since the porous layer forming the concave portion and the porous layer forming the friction sliding surface have the same cavity forming rate, the friction sliding surface and the lubricating oil concave portion lubricate the porous layer. Since the oil permeability and discharge property are the same, the discharge property of the lubricating oil adhering to the surface of the friction material can be improved.

  It should be noted that the fact that the porous layer forming the lubricating oil concave portion and the porous layer forming the friction sliding surface have the same cavity forming rate does not mean only a complete match between the two, but not both. A range of difference in formation rate (for example, a difference of ±10% or less) that falls within a predetermined range (for example, a difference of ±10% or less) in which the difference in permeability and dischargeability of the lubricating oil can be considered to be substantially the same. ) Including. Further, the smoothly continuous surface forming the surface of the lubricating oil recess may include an inclined surface formed by a plane extending linearly, but is preferably formed by a concavely curved surface.

  Another feature of the present invention is that, in the wet friction plate, the lubricating oil concave portion is formed in an arc shape having one curvature in at least one of two directions orthogonal to each other in a plan view. is there.

  According to another feature of the present invention configured as described above, in the wet friction plate, the lubricating oil concave portion is formed in an arc shape having one curvature in at least one of two directions orthogonal to each other in a plan view. Therefore, the lubricating oil recess can be easily formed.

  Another feature of the present invention is that, in the wet friction plate, the lubricating oil recess is formed in a long hole shape or an elliptical shape in a plan view.

  According to another feature of the present invention configured in this manner, the wet friction plate has the lubricating oil recess formed in a bottomed oblong shape or an elliptical shape in a plan view, so that it is localized in the friction sliding surface. Therefore, it is possible to form the lubricating oil concave portion while ensuring a necessary frictional contact area without causing a large missing portion of the friction sliding surface.

  Another feature of the present invention is that, in the wet friction plate, the lubricating oil recesses are formed so as to extend linearly, and the adjacent lubricating oil recesses are formed so as to be orthogonal to each other.

  According to another feature of the present invention having such a configuration, the wet friction plate is formed such that the lubricating oil recesses are formed to extend linearly, and the lubricating oil recesses adjacent to each other are oriented in a direction orthogonal to each other. Therefore, the durability of the friction material can be prevented from weakening in a specific direction, and uniform durability can be ensured. Further, the lubricating oil concave portion can improve the frictional resistance by being formed in a direction intersecting the rotational driving direction of the wet type friction plate, and at the same time, can be formed so as to extend radially outward of the wet type friction plate. It is possible to secure the drainability of the lubricating oil due to the centrifugal force.

  Another feature of the present invention is that, in the wet friction plate, the lubricating oil recesses are formed in a plurality of depths.

  According to another feature of the present invention having such a configuration, in the wet friction plate, since the lubricating oil recesses are formed in a plurality of depths, wear of the friction material progresses and the total thickness of the friction material is reduced. When the thickness is reduced, the shallow depth of the lubricating oil concave portion is brought into a state close to disappearance, and deterioration of durability of the friction material can be suppressed. In this case, the wet friction plate can be expected to have the same effect by forming the lubricating oil recesses in plural kinds of groove widths instead of or in addition to forming the lubricating oil recesses in plural kinds of depths.

  Further, the present invention can be carried out not only as an invention of a wet friction plate but also as an invention of a wet multi-plate clutch including the wet friction plate and a method of manufacturing the wet friction plate.

  Specifically, the wet multi-plate clutch device is rotationally driven between the drive side plate, which is rotationally driven by the prime mover, by disposing the opposing side plate to face each other through a gap and lubricating oil so as to closely contact or separate each other. In the wet multi-plate clutch device that transmits or cuts off force, at least one of the drive side plate and the opposing side plate is the wet friction plate according to any one of claims 1 to 5. Good. According to the wet multi-plate clutch device configured as described above, it is possible to expect the same operational effect as the wet friction plate.

  Further, the method of manufacturing a wet friction plate is such that a friction sliding surface and a plurality of lubricating oil recesses concavely recessed with respect to the friction sliding surface are formed on the surface of a porous layer having a plurality of cavities. Material, and a method for producing a wet friction plate comprising a core metal formed in a flat plate annular shape and provided with a friction material along the circumferential direction, in the form of a slurry containing a fibrous material forming a porous layer. The raw forming process of forming the raw material into a sheet, the water content adjusting step of reducing the water content of the sheet-like raw material to 90% or less and 50% or more, and the sheet-shaped raw material with the water content adjusted to have a square surface. Portion for forming a lubricant oil recess formed by pressing a lubricant oil recess forming die formed on a smoothly continuous surface without a sharp portion having a sharp shape, and a sheet on which a lubricant oil recess is formed It is advisable to include a drying step of reducing the water content in the raw material to 10% or less. According to the method of manufacturing a wet friction plate configured as described above, the wet friction plate can be manufactured.

It is a sectional view showing the whole wet multi-plate clutch device composition provided with the wet friction plate concerning one embodiment of the present invention. It is a top view which shows the outline of the external appearance of the wet friction plate which concerns on one Embodiment of this invention incorporated in the wet multi-plate clutch apparatus shown in FIG. It is the image data which imaged the cross section of the friction material which comprises the wet friction plate shown in FIG. 2 with the scanning electron microscope. (A) to (C) schematically show the lubricating oil recesses in the friction material constituting the wet friction plate shown in FIG. 2, (A) is a plan view of the lubricating oil recesses, and (B) is a lubricating oil. It is a cross-sectional view of a recessed portion, (C) is a vertical cross-sectional view of the lubricating oil recessed portion. 3A and 3B are image data obtained by binarizing the image data trimmed by the trimming frames TF1 and TF2 with respect to the image data shown in FIG. 3, and FIG. The layer is shown, and (B) shows the porous layer immediately below the recess of the lubricating oil. 6 is a bar graph showing the rate of formation of cavities in the friction material shown in FIG. 5 and the rate of formation of cavities in the friction material according to the related art for each friction sliding surface and lubricating oil recess. It is the image data which imaged the cross section of the friction material concerning a prior art with a scanning electron microscope. 7A and 7B are image data obtained by binarizing the image data trimmed by the trimming frames TF1 and TF2 with respect to the image data shown in FIG. 7, and FIG. The layer is shown, and (B) shows the porous layer immediately below the recess of the lubricating oil. It is explanatory drawing which shows typically the main manufacturing processes of the wet friction plate and friction material which are shown in FIG. FIG. 10 is a partial enlarged view schematically showing an external configuration of a lubricating oil recessed mold that is attached to the press roller shown in FIG. 9. It is a partial top view which shows a part of external appearance structure of the wet type friction plate which concerns on the modification of this invention. It is a partial top view which shows a part of external appearance structure of the wet friction plate which concerns on the other modified example of this invention. It is a partial top view which shows a part of external appearance structure of the wet friction plate which concerns on the other modified example of this invention. It is a partial top view which shows a part of external appearance structure of the wet friction plate which concerns on the other modified example of this invention.

  Hereinafter, an embodiment of a wet friction plate, a wet multi-plate clutch device including the wet friction plate, and a method for manufacturing the wet friction plate according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an outline of the overall configuration of a wet multi-plate clutch device 100 including a wet friction plate 200 according to the present invention. It should be noted that each drawing referred to in the present specification schematically illustrates some of the constituent elements in an exaggerated manner in order to facilitate understanding of the present invention. For this reason, the dimensions, ratios, and the like between the constituent elements may differ. The wet multi-plate clutch device 100 is a mechanical device for transmitting or cutting off a driving force of an engine (not shown) which is a prime mover of a two-wheeled vehicle (motorcycle) to wheels (not shown) which are driven bodies, It is arranged between the engine and a transmission (transmission) (not shown).

(Structure of wet multi-plate clutch device 100)
The wet multi-plate clutch device 100 includes a housing 101 made of aluminum alloy. The housing 101 is formed in a cylindrical shape with a bottom, and is a member that constitutes a part of the housing of the wet multi-plate clutch device 100. An input gear 102 is fixed to a left side surface of the housing 101 in the drawing by a rivet 102b via a torque damper 102a. The input gear 102 is rotationally driven by meshing with a drive gear (not shown) which is rotationally driven by driving the engine. A plurality of (eight in the present embodiment) clutch plates 103 are displaceable along the axial direction of the housing 101 on the inner peripheral surface of the housing 101, and are spline-fitted so as to be integrally rotatable with the housing 101. Respectively held by.

  The clutch plate 103 is a flat plate annular component that is pressed against a wet friction plate 200 described later, and is formed by punching a thin plate material made of SPCC (cold rolled steel plate) material into an annular shape. Oil grooves (not shown) having a depth of several [mu]m to several tens [mu]m are formed on both side surfaces (front and back surfaces) of these clutch plates 103 for holding lubricating oil, which will be described later. Further, both side surfaces (front and back surfaces) of the clutch plate 103 where the oil grooves are formed are subjected to surface hardening treatment for the purpose of improving wear resistance. Since this surface hardening treatment is not directly related to the present invention, its explanation is omitted.

  Inside the housing 101, a friction plate holder 104 formed in a substantially cylindrical shape is arranged concentrically with the housing 101. A large number of spline grooves are formed on the inner peripheral surface of the friction plate holder 104 along the axial direction of the friction plate holder 104, and the shaft 105 is fitted in the spline grooves. The shaft 105 is a shaft formed in a hollow shape, and one end (right side in the figure) of one end side rotatably supports the input gear 102 and the housing 101 via a needle bearing 105a, and a friction plate that engages with the spline. The holder 104 is fixedly supported via the nut 105b. That is, the friction plate holder 104 rotates integrally with the shaft 105. On the other hand, the other end (left side in the drawing) of the shaft 105 is connected to a transmission (not shown) in the two-wheeled vehicle.

  A shaft-shaped push rod 106 is disposed so as to penetrate through the hollow portion of the shaft 105 in a state of protruding from the one end (right side in the drawing) of the shaft 105. The push rod 106 is connected to a clutch operating lever (not shown) of a two-wheeled vehicle on the opposite side (left side in the drawing) of the end portion protruding from one end (right side in the drawing) of the shaft 105, and by operating the clutch operating lever. The inside of the hollow portion of the shaft 105 slides along the axial direction of the shaft 105.

  On the outer peripheral surface of the friction plate holder 104, a plurality of wet friction plates 200 (seven in this embodiment) can be displaced along the axial direction of the friction plate holder 104 with the clutch plate 103 sandwiched therebetween. Further, they are held by spline fitting in a state of being integrally rotatable with the friction plate holder 104.

  On the other hand, inside the friction plate holder 104, a predetermined amount of lubricating oil (not shown) is filled and three cylindrical support columns 104a are formed (only one is shown in the figure). The lubricating oil is supplied between the wet friction plate 200 and the clutch plate 103 to prevent friction heat generated between the wet friction plate 200 and the clutch plate 103 and prevent abrasion of the friction material 210.

  Further, the three cylindrical support columns 104 a are formed in a state of protruding toward the axial direction outer side (right side in the drawing) of the friction plate holder 104, respectively, and the pressing cover arranged at a position concentric with the friction plate holder 104. 107 are respectively assembled via a bolt 108a, a receiving plate 108b and a coil spring 108c. The pressing cover 107 is formed in a substantially disc shape having an outer diameter substantially the same as the outer diameter of the wet friction plate 200, and is pressed toward the friction plate holder 104 by the coil spring 108c. In addition, a release bearing 107a is provided at the inner center of the pressing cover 107 at a position facing the right end of the push rod 106 in the figure.

(Structure of wet friction plate 200)
As shown in detail in FIG. 2, the wet friction plate 200 is configured to include an oil groove 203 and a friction material 210 on a flat plate-shaped cored bar 201. The cored bar 201 is a member that is a base of the wet friction plate 200, and is formed by punching a thin plate material made of SPCC (cold rolled steel plate) material into a substantially annular shape. In this case, an inner tooth-shaped spline 202 for engaging the friction plate holder 104 with the spline is formed on the inner peripheral portion of the cored bar 201.

  On the side surface of the wet friction plate 200 facing the clutch plate 103, that is, on the side surface of the cored bar 201 facing the clutch plate 103, a plurality (32 in the present embodiment) of small-piece-shaped friction materials 210 are provided. They are provided along the circumferential direction of the cored bar 201 via oil grooves 203 formed of a gap.

  The oil groove 203 is a flow path for guiding the lubricating oil between the inner peripheral edge and the outer peripheral edge of the cored bar 201 of the wet friction plate 200, and allows the lubricating oil to exist between the wet friction plate 200 and the clutch plate 103. It is also an oil holding part for storing. The oil groove 203 is formed so as to extend linearly between each of the plurality of small friction members 210.

  The friction material 210 improves the frictional force with respect to the clutch plate 103, and is made of a small piece of paper material attached along the circumferential direction of the cored bar 201. As shown in FIG. 3, the friction material 210 is composed of a hard porous layer 211 obtained by impregnating and hardening a paper base material with a thermosetting resin.

  In this case, the paper base material is configured by adding a filler to at least one of the organic fiber and the inorganic fiber. Here, as the organic fiber, wood pulp, synthetic pulp, polyester fiber, polyamide fiber, polyimide fiber, polyvinyl alcohol modified fiber, polyvinyl chloride fiber, polypropylene fiber, polybenzimidazole fiber, acrylic fiber, carbon fiber, phenol Fibers, nylon fibers, cellulose fibers and the like can be composed of one kind or a plurality of kinds. Further, as the inorganic fiber, glass fiber, rock wool, potassium titanate fiber, ceramic fiber, silica fiber, silica-alumina fiber, kaolin fiber, bauxite fiber, kayanoid fiber, boron fiber, magnesia fiber and metal fiber or the like or It can be composed of multiple types.

  The filler functions as a friction modifier and/or a solid lubricant, and includes barium sulfate, calcium carbonate, magnesium carbonate, silicon carbide, boron carbide, titanium carbide, silicon nitride, boron nitride, and alumina. , One or more of silica, zirconia, cashew dust, rubber dust, diatomaceous earth, graphite, talc, kaolin, magnesium oxide, molybdenum disulfide, nitrile rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, silicone rubber and fluororubber. Can be configured. Examples of thermosetting resins include phenolic resins, melamine resins, epoxy resins, urea resins, melamine resins and silicone resins.

  Innumerable cavities 212 are formed in the porous layer 211. The cavity portion 212 is a pore portion formed in the gap between the materials of the paper base material and the thermosetting resin, in which the paper base material and the thermosetting resin do not exist, and the lubricating oil attached to the surface of the friction material 210 is It is the part that is soaked and flows or is retained. The hollow portions 212 are randomly formed in large numbers in various sizes inside the porous layer 211. In this case, the cavity portion 212 has a cavity portion 212 that opens to the surface of the porous layer 211 and a cavity portion 212 that is formed inside the porous layer 211 without facing the surface of the porous layer 211. .. Further, the cavity portion 212 includes a case where the cavity portions 212 adjacent to each other communicate with each other and a case where the cavity portions 212 adjacent to each other do not communicate with each other.

  As shown in FIGS. 4A to 4C, friction sliding surfaces 213 and lubricating oil recesses 214 are formed on the surface of the porous layer 211. The friction sliding surface 213 is a portion that comes into frictional sliding contact with the clutch plate 103, and is configured by a flat surface. The lubricating oil recesses 214 are portions that increase the frictional resistance of the friction material 210 and retain the lubricating oil, and are formed in a plurality of recesses in the friction sliding surface 213. In this case, the recessed surface of each lubricating oil recess 214 is formed as a smoothly continuous surface without sharp points such as corners having a sharp shape.

  In the present embodiment, each lubricating oil recess 214 is formed in an elongated hole shape in plan view. More specifically, the lubricating oil recess 214 has a vertical cross-sectional shape along the longitudinal direction in which the deepest part linearly extends in the horizontal direction, and both ends of the deepest part are gently curved toward the friction sliding surface 213. And is formed in a shape that inclines in a curved shape. Further, the lubricating oil recess 214 is formed in an arc-shaped transverse cross section along the width direction orthogonal to the longitudinal direction. In this case, the lubricating oil recess 214 is configured to include a plurality of types of lubricating oil recesses 214 formed with a plurality of types of length in the longitudinal direction, length in the width direction, and depth of the deepest portion. .. In the present embodiment, the lubricating oil recess 214 is of a plurality of types having a longitudinal direction of about 1.0 to 2.0 mm, a width direction of about 0.6 to 0.7 mm, and a depth of 0.25 to 0.4 mm. It is composed of sizes.

  The lubricating oil recesses 214 are formed so that the lubricating oil recesses 214 adjacent to each other extend in a direction orthogonal to each other via the friction sliding surface 213. In the present embodiment, the lubricant oil recesses 214 are formed by extending the lubricant oil recesses 214 that are adjacent to each other in the longitudinal direction and the width direction in directions orthogonal to each other. That is, in the present embodiment, the lubricating oil recess 214 is formed in a mesh shape over the entire friction sliding surface 213 in plan view.

  Then, in the porous layer 211, the hollow portions 212 are formed at the same forming rate in the portion forming the friction sliding surface 213 and the portion forming the lubricating oil recess 214. Here, the formation rate of the cavity portion 212 is the proportion of the cavity portion 212 in a certain space in the porous layer 211. The formation rate of the cavity 212 can be calculated from the amount of the injected fluid by pressurizing a fluid such as oil, mercury, or helium into the porous layer 211. The formation rate of the cavity 212 can be approximately calculated by performing image processing using a digital image of the porous layer 211. Specifically, the formation rate of the hollow portion 212 is 2 by obtaining an image of each cross section of the porous layer 211 immediately below the friction sliding surface 213 and the porous layer 211 immediately below the lubricating oil recess 214. It can be calculated by image processing for binarization.

  First, the operator cuts the lubricating oil recess 214 in the friction material 210 in the cross-sectional direction, and then determines the cross-sectional state using a magnifying imaging device such as a scanning electron microscope at a predetermined magnification (for example, 120 times). The digital image data (hereinafter, simply referred to as "image data") imaged in (3) is acquired (see FIG. 3). In this case, the operator takes an image in a state including the cross section of the frictional sliding surface 213 formed around the lubricating oil recess 214 that is the imaging target.

  Next, the operator uses image data obtained by using a computer device such as a personal computer capable of processing the image data, the image data of the portion directly below the lubricating oil recess 214 and the image of the portion directly below the friction sliding surface 213. The data is trimmed by the trimming frames TF1 and TF2 having a predetermined size. In this case, the trimming frame TF1 that defines the trimming range of the image data of the portion immediately below the lubricating oil recess 214 has the lubricating oil recess 214 centered on the center position in the width direction of the lubricating oil recess 214 immediately below the lubricating oil recess 214. Within a width of at least ⅓, and at least 70% or more within a thickness of the porous layer 211 immediately below the lubricating oil recess 214, and can be formed in a rectangular shape as a whole. ..

  On the other hand, the trimming frame TF2 that defines the trimming range of the image data immediately below the friction sliding surface 213 has the same size as the trimming frame TF1, and the friction sliding surface 213 that is sufficiently separated from the lubricating oil recess 214. It is located directly below. In these cases, the trimming frames TF1 and TF2 are arranged at positions close to the respective surfaces of the lubricating oil recess 214 and the friction sliding surface 213. In addition, in the present embodiment, the trimming frames TF1 and TF2 are formed by 330 pixels×660 pixels.

  Next, as shown in FIGS. 5A and 5B, the worker uses the image processing software (known computer program) capable of binarizing the image data to set the trimming frames TF1 and TF2. The two trimmed image data are binarized. In this case, a threshold value that can accurately convert the image data representing the hollow portion 212 in the image data into black or white is set in the image processing software. Thereby, the operator can acquire the image data obtained by binarizing the image data representing the portions directly below the lubricating oil recess 214 and the friction sliding surface 213. In this embodiment, the hollow portion 212 is converted to black and the porous layer 211 other than the hollow portion 212 is converted to white.

  Next, the operator uses the image processing software (known computer program) capable of calculating each area of the black portion and the white portion in the binarized image data, and the cavity in the binarized image data. The total value obtained by integrating the areas of the portions (black portions) corresponding to 212 is calculated. The calculation of this total value is performed for each trimming frame TF1 and TF2.

  As a result, the operator can set the difference between the total value of the area of the cavity 212 in the trimming frame TF1 on the image data and the total value of the area of the cavity 212 in the trimming frame TF2 on the image data within a predetermined range. The same formation rate. Here, the difference within the predetermined range is preferably a range where the difference between the two total values is ±10% or less. In addition, the operator may compare the ratio of the total value of the area of the hollow portion 212 to the entire area of the trimming frame TF1 or the total value of the area of the porous layer 211 (white portion) excluding the hollow portion 212 in the trimming frame TF1. It is also possible to confirm the identity of the formation rate by comparing the ratio of the total value of the areas of the cavity 212 with the ratio of the total value of the same areas in the trimming frame TF2.

  Here, the verification result by the present inventors will be described. FIG. 6 is a bar graph showing integrated values of the area of the cavity 212 obtained by performing the image processing by the binarization on the friction material 210 according to the present invention and the friction material 90 according to the related art. Here, the horizontal axis represents the total value of the areas of the friction sliding surface 213 of the friction material 210 and the hollow portions 212 of the lubricating oil recess 214, and the friction sliding surface 93 of the friction material 90 and the hollow portions of the lubricating oil recess 94. This is a total value of 92 areas. Further, the vertical axis represents the ratio of the total value of the area of the cavity 212 to the total area of the trimming frames TF1 and TF2.

  In the friction material 90, as shown in FIG. 7, a concave lubricating oil recess 94 is formed by pressing a mold against the surface of a porous layer 91 of the same quality as the porous layer 211. In this case, the lubricating oil recess 94 is formed with corners at an angle of about 120° at both ends in the cross-sectional direction at the bottom. Note that in FIG. 7, only one (the left side in the drawing) side of the two corners is imaged, but the other side corner that is not imaged is formed at the right side end in the figure of the captured image. ing.

  For the friction material 90, the present inventors acquired image data of the porous layer 91 in the same manner as the friction material 210, and then, as shown in FIG. 8, for the acquired image data. The trimming frames TF1 and TF2 are trimmed and binarized. Then, the present inventors calculate the total value obtained by integrating the areas of the portions (black portions) corresponding to the hollow portions 92 in the binarized image data in the same manner as described above. In the friction material 90, the porous layer 91, which is the supporting layer that forms the lubricating oil recess 94, is the supporting layer that forms the frictional sliding surface 93, based on the image data shown in FIGS. 7 and 8. It can be confirmed that it is compressed and crushed in the vertical direction in the figure than 91.

  According to the verification results by the present inventors, the formation rate of the cavity 212 immediately below the frictional sliding surface 213 in the friction material 210 is 27.4%, and the cavity 212 immediately below the lubricating oil recess 214 is formed. The formation rate is 26.1%. In addition, the formation rate of the cavity portion 92 immediately below the frictional sliding surface 93 in the friction material 90 is 28.8%, and the formation rate of the cavity portion 92 immediately below the lubricating oil recess 94 is 21.2%. .. Each of these formation rates is an average value of a plurality of samples.

(Production of wet friction plate 200)
Next, a method of manufacturing the wet friction plate 200 having the above structure will be described with reference to FIGS. 9 and 10. First, the worker performs a raw material stirring step of stirring the raw materials. Specifically, the operator puts the raw material of the paper base material, that is, the organic fiber and/or the inorganic fiber, the filler and the coagulant into the water in the stirring tank 300 and stirs the slurry. Produce raw material in the form of Next, the worker transfers the slurry-like raw material in the stirring tank 300 to the papermaking tank 301 using the pump 300a.

  Next, the worker carries out the papermaking process. This papermaking process mainly includes a raw forming process, a water content adjusting process, a lubricating oil recess forming process and a drying process. Specifically, the operator rotationally drives the conveying device 303 provided with the endless belt-shaped paper making net 302 arranged facing the paper making tank 301, and strains the raw material into a sheet from the paper making tank 301. The sheet is conveyed to the pair of press rollers 305 (original forming process). The conveying device 303 includes a water absorbing roller 304a and a suction box 304b between the papermaking tank 301 and the press roller 305, respectively, and removes water from the sheet-shaped raw material on the papermaking net 302 (water content adjusting step).

  The press roller 305 is a component for forming the lubricating oil recess 214 in the sheet-shaped raw material on the papermaking net 302, and is composed of a pair of rollers arranged to face each other. In this case, on one surface of one of the two rollers forming the press roller 305, as shown in FIG. 10, a lubricating oil recess forming die 305a made by knitting metal or resin threads in a lattice pattern is formed. It is composed by being wrapped around. The press roller 305 is provided in the range of 90% to 50% of the water content (% by weight) of the sheet-shaped raw material on the path of the papermaking net 302. In the present embodiment, the press roller 305 is provided such that the water content (% by weight) of the sheet-shaped raw material on the path of the papermaking net 302 is in the range of 60% to 50%.

  Therefore, the sheet-shaped raw material that has been pulled up from the papermaking tank 301 and adjusted to have a predetermined water content is passed through the press roller 305 to form a friction sliding surface 213 and a lubrication surface on the surface facing the lubricating oil recess forming die 305a. The oil recesses 214 are respectively formed (lubricant oil recess forming step). In this case, the sheet-shaped raw material is adjusted to have a relatively high water content, and the lubricating oil recess molding die 305a is formed into a smooth curved surface. As a result, the friction material 210 is prevented from being compressed and deformed at the portion against which the lubricating oil recess forming die 305a is pressed and the cavity 212 disappears. Therefore, the friction sliding surface 213 and the lubricating oil recess 214 are porous. It is possible to suppress a difference in the formation rate of the hollow portions 212 in the layer 211. According to the experiments performed by the present inventors, the lubricating oil recessed mold 305a is easier to ensure flexibility than the case where the lubricating oil recessed mold 305a is made of metal by knitting a resin thread. The compressive deformation of the porous layer 211 immediately below 214 can be suppressed.

  Next, the sheet-shaped raw material on which the frictional sliding surface 213 and the lubricating oil recess 214 are respectively formed is passed through a drying device 306 including a drying roller or the like arranged on the downstream side of the press roller 305. Further, the water content is reduced to 10% or less (drying step). In this case, the water content of the sheet-shaped raw material in which the lubricating oil recesses 214 are formed is preferably 3% or more. After that, the sheet-shaped raw material is wound around the collecting roller 307, and the papermaking process is completed.

  Next, the worker performs a curing process. Specifically, an operator impregnates a sheet-shaped raw material, which has been dried to a water content of 10% or less, with a thermosetting resin, and then presses this sheet-shaped raw material while heating to adjust the shape. Let it harden. Thereby, the worker can manufacture the friction material 210 including the porous layer 211 that is hardened in the state where the friction sliding surface 213 and the lubricating oil recess 214 are formed.

  Next, the worker carries out the step of attaching the friction material 210. Specifically, the operator attaches a small piece of the friction material 210 to the surface of the cored bar 201 manufactured by mechanical processing such as press working in another process along the circumferential direction using an adhesive. In this case, the worker may attach the friction material 210, which is cut into small pieces in advance, to the cored bar 201, or may cut the frictional material 210 into small pieces when attached to the cored bar 201. .. Thereby, the worker can manufacture the wet friction plate 200 in which the small friction material 210 is attached to both surfaces of the core 201 along the circumferential direction via the oil grooves 203. In addition, in the manufacturing process of the wet friction plate 200, there are a machining process, a friction characteristic adjusting process, an inspection process, and the like other than those described above, but the description thereof is omitted because they are not directly related to the present invention.

(Operation of wet friction plate 200)
Next, the operation of the wet friction plate 200 configured as described above will be described. The wet friction plate 200 is used by being assembled in the wet multi-plate clutch device 100 as described above. As described above, the wet multi-plate clutch device 100 is arranged between the engine and the transmission of the vehicle, and the shift of the driving force of the engine is performed by the operation of the clutch operating lever by the operator of the vehicle. Transmission to and disconnection from the machine.

  That is, when an operator (not shown) of the vehicle operates a clutch operating lever (not shown) to move the push rod 106 backward (displace to the left in the figure), the tip of the push rod 106 is released. 107a is not pressed, and the pressing cover 107 presses the clutch plate 103 by the elastic force of the coil spring 108c. As a result, the clutch plate 103 and the wet friction plate 200 are displaced toward the receiving portion 104b formed in a flange shape on the outer peripheral surface of the friction plate holder 104 and are pressed against each other to be frictionally coupled. As a result, the driving force of the engine transmitted to the input gear 102 is transmitted to the transmission via the clutch plate 103, the wet friction plate 200, the friction plate holder 104 and the shaft 105.

  On the other hand, when the vehicle operator operates the clutch operating lever (not shown) to move the push rod 106 forward (displace to the right in the figure), the tip of the push rod 106 presses the release bearing 107a. Then, the pressing cover 107 is displaced rightward in the drawing while resisting the elastic force of the coil spring 108c, and the pressing cover 107 and the clutch plate 103 are separated from each other. As a result, the clutch plate 103 and the wet friction plate 200 are displaced toward the pressing cover 107 side, released from the state of being pressed against each other, and separated from each other. As a result, the drive force is not transmitted from the clutch plate 103 to the wet friction plate 200, and the transmission of the engine drive force transmitted to the input gear 102 to the transmission is interrupted.

  In the state where the clutch plate 103 and the wet friction plate 200 are in frictional contact with each other, the lubricating oil existing on the surface of the friction material 210 in the wet friction plate 200 is pushed by the clutch plate 103 and part of the friction material 210. It is discharged to the outside of the friction material 210 through the outer edge portion, and another part penetrates into the friction material 210. In this case, the lubricating oil that permeates the friction material 210 includes the lubricating oil that is retained in the lubricating oil recess 214 and the lubricating oil that permeates into the porous layer 211. Then, a part of the lubricating oil that permeates into the porous layer 211 is discharged from the end surface of the porous layer 211 (friction material 210) through the cavity 212, and the other part remains in the cavity 212. ..

  In this case, the lubricating oil recess 214 is formed on a smooth continuous surface without sharp points such as corners on the surface holding the lubricating oil, and the porous layer forming the lubricating oil recess 214 is formed. 211 and the porous layer 211 forming the frictional sliding surface 213 are formed so that the cavity portions 212 have the same formation rate. As a result, in the wet multi-plate clutch device 100, the difference between the permeability and the drainability of the lubricating oil with respect to the porous layer 211 between the friction sliding surface 213 and the lubricating oil recess 214 is reduced, and they are attached to the surface of the friction material 210. It is possible to improve the discharge property of the lubricating oil, stabilize the temperature characteristics (cooling characteristics) and the surface pressure characteristics, and improve the durability of the friction material 210.

  Moreover, in the wet multi-plate clutch device 100, when the clutch plate 103 and the wet friction plate 200 are separated from each other, the amount of lubricating oil remaining between the clutch plate 103 and the wet friction plate 200 is smaller than that in the conventional technique. Thus, the wet multi-plate clutch device 100 can reduce the drag torque when the clutch plate 103 and the wet friction plate 200 are indirectly connected by the lubricating oil existing between the clutch plate 103 and the wet friction plate 200. it can.

  As can be understood from the above description of the operation, according to the above-described embodiment, the wet friction plate 200 is formed on the surface of the lubricating oil recess 214 in a smoothly continuous surface without a sharp portion such as a corner having a sharp shape. In addition, since the porous layer 211 forming the lubricating oil recess 214 and the porous layer 211 forming the frictional sliding surface 213 are formed so that the cavity portions 212 are formed at the same rate, the frictional sliding surface is formed. 213 and the lubricating oil recess 214 have the same permeability and dischargeability of the lubricating oil with respect to the porous layer 211, and the dischargeability of the lubricant oil adhering to the surface of the friction material 210 can be improved.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the object of the present invention. In each of the modified examples described below, the same components as those of the wet friction plate 200 in the above embodiment are denoted by the same reference numerals as those of the wet friction plate 200, and the description thereof will be omitted.

  For example, in the above-described embodiment, the wet friction plate 200 is held by the friction plate holder 104 that is rotationally driven integrally with the shaft 105. That is, the wet friction plate 200 is applied to the opposite side plate that is arranged opposite to the clutch plate 103 that is rotationally driven by the rotational driving force of the engine and that is integrally rotationally driven with the shaft 105 that is the output shaft of the wet multi-plate clutch device 100. did. However, the wet friction plate 200 can also be applied to the clutch plate 103 as a driving side plate that is rotationally driven by the rotational driving force of the engine.

  Further, in the above-described embodiment, the lubricating oil recess 214 is formed in a single circular arc cross section. However, the lubricating oil recess 214 may be formed on a smoothly continuous surface without sharp points such as corners on the surface. Therefore, the lubricating oil recess 214 may include a straight line portion like a vertical cross-sectional shape, or may be formed to have a curved surface made up of two or more curves.

  Further, in the above-described embodiment, the lubricating oil recess 214 is formed in the shape of an elongated hole in plan view. However, the lubricating oil recess 214 may be formed on a smoothly continuous surface without sharp points such as corners on the surface. Therefore, as shown in FIG. 11, the lubricating oil recess 214 can also be formed in a hemispherical dimple shape. Further, the lubricating oil recess 214 can be formed to have an elliptical shape, and can also be formed to include an elongated hole shape and an elliptical shape as shown in FIG. Further, as shown in FIG. 13, the lubricating oil recess 214 may be formed to extend linearly in the radial direction of the cored bar 201 and penetrate the friction material 210. Further, the lubricating oil recess 214 may be formed to extend in the circumferential direction and the tangential direction instead of or in addition to the radial direction of the cored bar 201. Further, as shown in FIG. 14, the lubricating oil recesses 214 can be formed by extending in a lattice shape or a mesh shape in two directions intersecting with each other. The lubricating oil recess 214 may be formed in a curved shape instead of or in addition to the linear shape in a plan view.

  Further, in the above embodiment, the lubricating oil recess 214 is configured to include a plurality of types of sizes formed by a plurality of types of length in the longitudinal direction, length in the width direction and depth. However, the lubricating oil recesses 214 can be formed to have the same shape.

  Further, in the above embodiment, in the original forming step, the raw material is formed into a sheet shape extending in the shape of a band by using the endless belt-shaped paper making net 302. However, the paper-making net 302 should just be able to form a raw material into a sheet form. Therefore, the papermaking net 302 may be formed in a square shape or a circular shape. In this case, the rectangular or circular papermaking net 302 can be housed in a bottomed cylindrical mold to mold the raw material into a rectangular or circular sheet.

  Further, in the above embodiment, in the water content adjusting step, the water content of the sheet-shaped raw material is adjusted to 60% or less and 50% or more. However, in the water content adjusting step, the water content of the sheet-shaped raw material may be adjusted to 90% or less and 50% or more, and preferably 70% or less and 50% or more to easily and easily form the lubricating oil recess 214. It can be molded with high precision.

  Further, in the above embodiment, in the lubricating portion recess forming step, the lubricating oil recess 214 is formed by the lubricating oil recess forming die 305a formed in a roll shape. However, in the lubricating portion recess forming step, the lubricating oil recess 214 can be formed by pressing the planar lubricating oil recess forming die 305a against the raw material.

  Further, in the above-described embodiment, the lubricating oil recess molding die 305a is formed by knitting resin threads in a lattice pattern. However, the lubricating oil recess molding die 305a is only required to be able to mold the lubricating oil recess 214 on the raw material. Therefore, the lubricating oil recessed mold 305a may be formed by molding a resin material or a metal material into a lattice shape by using a processing method such as injection molding, or the lubricating oil recessed portion 214 may be formed on a resin or metal plate. It is also possible to form by forming a plurality of irregularities or through holes for forming.

  Further, in the above embodiment, the example in which the wet friction plate according to the present invention is applied to the wet friction plate 200 used in the wet multi-plate clutch device 100 has been described. However, the wet friction plate according to the present invention may be a wet friction plate used in oil, and is not limited to the wet multi-plate clutch device 100 and a wet friction plate used for a brake device that brakes rotary motion by a prime mover. Is also applicable.

TF1... Trimming frame for acquiring image data immediately below the lubricating oil concave portion, TF2... Trimming frame for acquiring image data immediately below the surface of the friction circumferential portion,
90... Conventional friction material, 91... Porous layer, 92... Cavity, 93... Friction sliding surface, 94... Lubricant recess 100... Wet multi-plate clutch device, 101... Housing, 102... Input gear, 102a... Torque damper , 102b... Rivet, 103... Clutch plate, 104... Friction plate holder, 104a... Cylindrical support column, 105... Shaft, 105a... Needle bearing, 105b... Nut, 106... Push rod, 107... Press cover, 107a... Release bearing , 108a... bolts, 108b... receiving plate, 108c... coil spring,
200... Wet friction plate, 201... Core metal, 202... Spline, 203... Oil groove,
210... Friction material, 211... Porous layer, 212... Cavity, 213... Friction sliding surface, 214... Lubricating oil recess,
300... Stirring tank, 300a... Pump, 301... Paper making tank, 302... Paper making net, 303... Conveying device, 304a... Water absorbing roller, 304b... Suction box, 305... Press roller, 305a... Lubricant recessed mold, 306... Drying Device, 307... Collection roller.

Claims (6)

A friction material having a friction sliding surface and a plurality of lubricating oil recesses recessed in a concave shape with respect to the friction sliding surface on the surface of a porous layer having a plurality of cavities, respectively,
In a wet friction plate including a core metal formed in a flat plate annular shape and the friction material is provided along the circumferential direction,
The friction material is
The surface of the lubricating oil recess is formed into a smoothly continuous surface without sharp points such as corners, and the porous layer and the friction sliding surface forming the lubricating oil recess are formed. The wet friction plate is characterized in that the formation rate of the cavity is the same as that of the porous layer. The wet friction plate according to claim 1,
The lubricating oil recess is
A wet friction plate, wherein at least one cross section in two directions orthogonal to each other in a plan view is formed in an arc shape having one curvature. The wet friction plate according to claim 1 or 2,
The lubricating oil recess is
A wet friction plate, which is formed in an elongated hole shape or an elliptical shape in a plan view. The wet friction plate according to claim 3,
The lubricating oil recess is
A wet friction plate, wherein the lubricating oil recesses that are formed to extend linearly and that are adjacent to each other are formed in directions orthogonal to each other. The wet friction plate according to any one of claims 1 to 4,
The lubricating oil recess is
A wet friction plate having a plurality of depths. Wet multi-plate clutch device that transmits or cuts rotational driving force between two driving plates that are rotationally driven by a prime mover so as to face each other through a gap and a lubricating oil so that the two plates closely contact or separate from each other. At
The drive side plate and the opposite side plate,
A wet multi-plate clutch device, at least one of which is the wet friction plate according to any one of claims 1 to 5.