JPH11201206A - Wet friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more excellently keep a friction characteristic by improving a coefficient of thermal conductivity by providing a continuous mesh metallic layer as an intermediate layer in parallel to a sliding surface in a wet friction material. SOLUTION: A wet friction material 1 is formed by fiber base materials such as cellulose fiber and aramido fiber and combined agent of an inorganic filler and resin. In this friction material 1, a mesh metallic layer 2 is provided as an intermediate layer. Namely, because the mesh metallic layer 2 is installed as an intermediate layer in parallel to a sliding surface 4 in the wet friction material 1 held on a metallic substrate 3 by adhesive, local heat generation of the wet friction material 1 can be diffused by the mesh metallic layer 2 and a heat spot is not generated on an opposed material friction plate. Because the surface of the wet friction material 1 can be kept in its normal state, also a friction characteristic can be extremely excellently kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet friction material for an automatic transmission used as a fluid automatic transmission for an automobile or the like. More specifically, the present invention relates to a wet friction material having improved thermal conductivity and improved friction characteristics.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission of an automobile or the like, usually, one or more disk plates in which a wet friction material is adhered to a surface of a metal substrate, and a friction mating material composed of a metal plate. A certain separate plate is arranged, and for a mating member rotating in ATF (auto transmission fluid) used as lubricating oil,
Pressing the stopped wet friction material to stop the rotation, or pressing the rotating wet friction material against the stopped counterpart material to rotate the counterpart material and the wet friction material in the same way Thus, the driving force of the prime mover is transmitted or cut off. In some cases, a rotational difference is generated between the wet friction material and the mating material to smoothly transmit the driving force of the prime mover in the same state as the half clutch.

As described above, the wet friction material used in oil is formed as a porous body because the oil must be sufficiently impregnated in the wet friction material. Heat-cured resin containing a thermosetting resin is generally used, and is lightweight and inexpensive.

[0004] The fiber base material used here is generally wood pulp or cotton linter.
Fillers such as friction modifiers and solid lubricants are appropriately added to these paper bodies. With respect to this type of wet friction material, for example, JP-A-1-169134 and JP-A-1-288
Various improved techniques are described in, for example, US Pat.

[0005]

With respect to such conventional wet friction materials, demands for the characteristics thereof have become more severe due to the recent increase in the engine output of automobiles and the miniaturization of transmissions. I have. In particular, one of them is improvement of heat resistance. For example, when the shift point of the automatic transmission is improved to improve the acceleration performance of the automobile, the engagement rotational speed of the friction material increases, and the friction engagement surface instantaneously increases by 40%.
It reaches 0 ° C. For this reason, in the conventional wet friction material using wood pulp as a fiber base material, even if seizure occurs or seizure does not occur, the friction material is not thermally stable, and it is not possible to obtain stable friction characteristics. In some cases, the wear resistance and durability could not be sufficiently satisfied. In particular, when undulation occurs when the disc plate and / or the separate plate is assembled, or when the pressing piston is not pressed uniformly, a so-called heat spot having a locally high temperature may be generated. Therefore, the temperature of the heat spot portion is further increased, and thermal degradation of the wet friction material may start from this portion.

Generally, in order to prevent such a heat spot, there is a method of improving the thermal conductivity of a friction material to smoothly diffuse heat. For example, Japanese Patent Application Laid-Open No. 62-18408
No. 5 discloses a technique for providing a porosity to a friction material composed of a metal fiber and an inorganic polymer binder, thereby providing a wet friction material having excellent heat resistance and wear resistance. And If the fiber of the base material is changed from organic to metallic to improve the heat resistance, the heat resistance can be improved, but the aggressiveness of the mating material is increased by the metal fiber, which is not preferable as a friction material. Because of the lack of the organic fiber, there is a case where the ability to maintain the pores is lacked as compared with the organic fiber, which causes a problem in the frictional characteristics.

[0007] Japanese Patent Application Laid-Open No. 4-142388 discloses that the thermal conductivity of a friction material is improved by adding an iron-based fine powder to obtain a wet friction material having excellent heat resistance. . However, although this method improves the thermal conductivity as a whole, it is not suitable for eliminating local and instantaneous high temperatures. Further, the addition of the iron-based fine powder may not be able to sufficiently exhibit the oil retaining performance of diatomaceous earth or the like which has been conventionally used as a filler, and may adversely affect the friction characteristics. Therefore,
In a wet friction material for an automatic transmission used as a fluid automatic transmission of an automobile or the like, it is possible to obtain a wet friction material that promotes heat diffusion, eliminates local and instantaneous high temperatures, and has excellent friction characteristics. Had been an issue.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a wet friction material capable of improving thermal conductivity and maintaining better friction characteristics. Aim.

[0009]

According to the present invention, there is provided a wet friction material comprising a fibrous base material, a filler and a binder such as a resin, which is bonded and held to a metal substrate. A wet friction material in which at least one continuous mesh-like metal layer is provided as an intermediate layer in the wet friction material in parallel with the sliding surface.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the wet friction material according to the present invention will be described below in detail with reference to the accompanying drawings. FIG.
1 is a perspective view showing a cross section of a part of a wet friction material according to the present invention, which is cut off. First, the configuration will be described with reference to FIG. The wet friction material according to the present invention is formed from a fiber base material such as cellulose fiber and aramid fiber, and a binder such as an inorganic filler and a resin, and includes a mesh-like metal layer as an intermediate layer in the friction material. Wet friction material. That is, an adhesive (in the figure, reference numeral 5 is an adhesive layer) is applied to the metal substrate 3.
The mesh-type metal layer 2 is provided as an intermediate layer in the wet friction material 1 held in the above manner in parallel with the sliding surface 4.

The mesh-like metal layer 2 used in the present embodiment is made of a metal having a high thermal conductivity such as iron, aluminum, copper, silver, and gold, and the type thereof is appropriately selected. That is, aluminum or the like having a low melting point can be used at a relatively low temperature, and a metal having a high melting point such as copper can be used at a high temperature.

Further, the thickness of the mesh-like metal layer 2 provided as an intermediate layer in the wet friction material 1 is sufficient to diffuse heat of the sliding surface 4 and to maintain mechanical strength. Now, 1-100 microns is good. The thickness of the metal layer 2 is 1
If the thickness is too large, a problem occurs in the strength of the friction material, and also a problem in thermal stress due to a difference in thermal expansion between the friction material 1 and the organic material. If the thickness is less than 1 micron, the strength as a friction material becomes insufficient. Therefore, the thickness of the metal layer 2 is 1 to 100 microns, preferably 5 to 50 microns.

The reason why the metal layer 2 is formed in a mesh shape is as follows.
This is to prevent the wet friction material 1 from being separated from the upper and lower portions of the metal layer 2 so that the mechanical strength cannot be maintained. That is, the wet friction material 1 above and below the metal layer 2 is utilized by utilizing the holes of the mesh.
This is to prevent the mechanical strength of the metal layer 2 from being reduced by the fiber components of the metal layer 2 being entangled with each other. To achieve this effect, the porosity of the mesh should be 2 in area ratio.
0 to 90%, more preferably 50 to 70% is good.

The metal layer 2 must be metallurgically continuous in order to improve the thermal diffusion of the wet friction material 1 by friction. If discontinuous, the thermal resistance will increase at that portion, and thermal diffusion will not be performed sufficiently, resulting in a reduction in frictional characteristics. Therefore, the effect of the present invention cannot be obtained when fibrous metals are simply collected and used as a metal layer.

On the other hand, the distance from the sliding surface 4 of the wet friction material 1 to the metal layer 2 needs to be set in relation to the thickness of the wet friction material 1 as a whole. In the present embodiment, the wet friction material 1
The thickness from the sliding surface 4 to the metal layer 2 is 0.1 to 0.3.
mm. When the thickness of the friction material 1 from the sliding surface 4 to the metal layer 2 is 0.1 mm or less, the metal substrate holding the friction material 1 plays the same role as the intermediate layer, and the metal layer 2 is installed. It does not make sense to improve the ability to prevent heat spots. When the distance from the sliding surface 4 to the metal layer 2 is 0.3 mm or more, the heat of the sliding surface 4
Does not spread quickly, causing a reduction in frictional properties.

Further, the present embodiment is applied only when the total thickness of the wet friction material 1 is 0.6 mm or more, and in this embodiment, the total thickness of the wet friction material 1 is zero. 0.6 to 2.0 mm. 0.6mm overall thickness
In the following, even if the metal layer 2 is provided in the middle of the friction material 1, the effect of improving the friction characteristics cannot be obtained, and if it is 2.0 mm or more, the friction material 1 is undesirably peeled off.

In this embodiment, in parallel with the sliding surface 4,
At least one continuous mesh-like metal layer 2 is provided as an intermediate layer in the wet friction material 1.
If the thickness is 6 to 2.0 mm, the thickness from the sliding surface 4 to the metal layer 2 is 0.1 to 0.3 mm, and the thickness of the metal layer 2 is 1 to 100 μm, the metal layer to be installed is plural. The same effect can be obtained by providing a plurality of sheets.

As the fiber forming the fiber base material, an organic fiber or an inorganic fiber can be used, and for example, it can be formed of at least one of cellulose fiber, polyamide fiber, aramid fiber, glass fiber and the like.

Diatomaceous earth, clay and the like can be used as the inorganic filler. In addition, cashew dust and the like can also be used.

Further, a phenol resin, an acrylic resin, a silicone resin or the like can be used as the binder.

Hereinafter, embodiments of the wet friction material according to the present invention will be specifically described with reference to Examples and Comparative Examples. T: thickness of the metal layer 2, T1: thickness of the wet friction material 1 from the sliding surface 4 to the metal layer 2, T2: metal layer 2
From the thickness of the wet friction material 1 to the adhesive layer 5. (Figure 1
reference)

Example 1 As a raw material of a wet friction material, 45% by weight of linter pulp was used.
An aramid fiber is suspended in an aqueous solution at a ratio of 5% by weight and diatomaceous earth at a ratio of 10% by weight. Then, a mesh-like copper plate having T = 0.04 mm and a porosity of 60% is placed in parallel with the sliding surface.
It inserted so that it might become an intermediate | middle layer in the position of T1 = 0.1mm from the friction material surface. In this state, papermaking and draining were performed and dried, and then the paper base material was impregnated with a phenol resin to cure the resin. Here, outer diameter 130 mm, inner diameter 1
A donut-shaped wet friction material having a thickness of 10 mm and a total thickness of 1.0 mm was obtained. Thereafter, the cured friction material was adhered to an iron-based substrate with a phenol resin adhesive to obtain a wet friction material of Example 1.

[0023] In Example 1, the mesh-like copper plate, the other was placed as an intermediate layer position of T1 = 0.1 mm from the friction material surface were obtained in the same manner wet friction material of Example 2 .

[0024] In Example 3 Example 1, the mesh-like copper plate, the other was placed as an intermediate layer in the position of T1 = 0.3 mm from the friction material surface were obtained in the same manner wet friction material of Example 3 .

Example 4 In Example 1, the thickness of the entire wet friction material (T1 + T
2) was set to 1.7 mm, and a wet friction material of Example 4 was obtained in the same manner except that a mesh-like copper plate was installed as an intermediate layer at a position of T1 = 0.2 mm from the surface of the friction material.

[0026] In Comparative Example 1 Example 1, the mesh-like copper plate, the other was placed as an intermediate layer in the position of T1 = 0.5 mm from the friction material surface were obtained in the same manner wet friction material of Comparative Example 1 .

COMPARATIVE EXAMPLE 2 A comparative example was made in the same manner as in Example 1 except that a mesh-type copper plate was not used, and an integral wet friction material was used so that the total thickness (T1 + T2) of the friction material was 1 mm. Thus, a wet friction material No. 2 was obtained.

Comparative Example 3 In Comparative Example 2, as a raw material of the wet friction material, a particle size of about 2
A wet friction material of Comparative Example 3 was obtained in the same manner except that 20% by weight of iron powder of 0 μm was mixed.

Evaluation Test 1. Friction test The wet friction materials obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were used as SAE Nos. A friction test was performed with up to 5000 cycles using two testers. <Test conditions> Inertia: 2.5 kgcm · sec ² Surface pressure: 1 MPa Rotation speed: 3000 rpm Automatic oil: Nissan Automatic Fluid D Test temperature: 120 ° C. The friction plate of the mating material was tested with three points pressed by a piston at three points. Was carried out.

2. Evaluation method (1) Heat spot The presence / absence of a heat spot on the friction plate as the mating material is investigated. (3 points pressed portion) (2) Appearance The appearance of the wet friction material of the present invention is examined for peeling, burning, discoloration, and the like.

Table 1 shows the results of these evaluations.

[0032]

[Table 1]

[0033]

As described above in detail, according to the present invention, the structure of the present invention comprises a fibrous base material, a filler, a binder such as a resin, and is bonded to and held on a metal substrate by wet friction. The material is a wet friction material in which at least one continuous mesh metal layer is provided as an intermediate layer in the wet friction material in parallel with the sliding surface, so that the local heat generation of the wet friction material is reduced by the mesh metal layer. Can be spread by
Since no heat spot is generated on the mating material friction plate and the surface of the wet friction material can be kept in a normal state, an excellent effect that the friction characteristics can be kept very good can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view illustrating an embodiment of a wet friction material according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wet friction material 2 Mesh metal layer 3 Metal substrate 4 Sliding surface 5 Adhesive layer

Claims (3)

[Claims] 1. A wet friction material comprising a fibrous base material, a filler and a binder such as a resin and adhered to and held on a metal substrate, wherein an intermediate layer is provided in said wet friction material in parallel with a sliding surface. Characterized in that at least one continuous mesh-like metal layer is provided. 2. The wet friction material according to claim 1, wherein the thickness of the entire wet friction material is 0.6 to 2.0 mm, and the wet friction material from the mesh-like metal layer to the sliding surface. A wet friction material, wherein the thickness of the friction material is 0.1 to 0.3 mm. 3. The wet friction material according to claim 1, wherein the continuous mesh-like metal layer has a thickness of 1 to 100 μm and a porosity of 20 to 90% in area ratio. A wet friction material characterized by the following.