JP2002294217A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction material which has excellent wear resistance, excellent brake working with stable friction coefficient, and small brake crying in the friction material being used in combination with a discrotor comprising an aluminum composite material. SOLUTION: In a disc brake being constituted in combination with the friction material pushing and pressing the discrotor comprising the aluminum composite material, the friction material comprises compounding and molding a base fiber, a binding material, a rigid inorganic material, and a filler, the aluminum composite material being an aluminum alloy containing a particle of a rigid inorganic matter, the rigid inorganic material compounded into the friction material being >=1 μm in an average particle diameter, and the average particle diameter of the rigid inorganic material contained in the friction material being smaller than that of the rigid inorganic matter contained in the aluminum composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material having excellent abrasion resistance and friction coefficient used in combination with a disk rotor made of an aluminum composite material.

[0002]

2. Description of the Related Art In recent years, in the face of environmental problems, developments in consideration of environmental protection have been promoted in the field of automobiles, and electric vehicles and hybrid cars have been commercialized.

Under these circumstances, the use of a motor in an automobile has reduced the load on the brake, and one of the requirements for reducing the weight of the vehicle has been to reduce the weight of brake parts.

Conventionally, cast iron has been used as a material for a disk rotor of a disk brake for an automobile. But,
In order to meet the demand for weight reduction, there is a movement to adopt an aluminum alloy having a very small specific gravity as compared with cast iron as a disk rotor. The aluminum alloy disk rotor uses aluminum as a base material, which is extremely inferior in strength and wear resistance as compared with the conventional cast iron disk rotor. Therefore, the disk rotor is made of an aluminum composite material having a very strong matrix in which a large amount of a hard inorganic substance such as silicon carbide or alumina is contained in an aluminum alloy in order to compensate for a defect of the base material. When a conventional friction material for cast iron is used for the aluminum rotor having this extremely strong matrix, the friction coefficient becomes extremely low, and the wear of the friction material is accelerated and is not worthy of use.

[0005] This is because the hardness of the hard inorganic substance contained in the aluminum composite disk rotor is very hard at Mohs hardness of 9 or more, so that the friction surface of the friction material is broken and collapses.

To improve this point, Japanese Patent Laid-Open No. 6-228 discloses
JP-A-539 and JP-A-6-228540 disclose that a hard inorganic material similar to the hard inorganic material internally added to an aluminum composite disk rotor is used as a friction material that is inferior to or can compete with an aluminum composite disk rotor. There is a disclosure that it is also blended into the material.

However, in this method, the friction characteristics are greatly affected by the size of the hard inorganic particles contained in the aluminum composite disk rotor. That is, depending on the combination of the size of the hard inorganic material particles included in the disk rotor and the size of the hard inorganic material particles included in the friction material, the friction coefficient is reduced or the friction material is worn more. There is a problem that.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and is a friction material for a disk rotor made of an aluminum composite material, which has excellent wear resistance, a stable friction coefficient, and an excellent brake performance. It is an object to propose a friction material which is excellent in the noise and has less brake squeal.

[0009]

The friction material according to the present invention is a disk brake comprising a combination of a disk rotor made of an aluminum composite material and a friction material for pressing the disk rotor, wherein the friction material is Is formed by compounding a base fiber, a binder, a hard inorganic material, and a filler, and the disc rotor composite is an aluminum alloy containing hard inorganic particles, and the hard inorganic compound mixed with the friction material. The material has a hardness that can withstand the hard particles blended in the disk rotor and has an average particle diameter of 1 μm or more, and the average particle diameter of the hard inorganic material included in the friction material is included in the disk rotor. Characterized in that it is smaller than the average particle size of the hard inorganic material.

It is preferable that the ratio of the average particle diameter of the hard inorganic material contained in the friction material to the average particle diameter of the hard inorganic substance contained in the disk rotor is 1:20 to 1: 2.

It is preferable that the hardness of the hard inorganic material mixed in the friction material is 9 or more in Mohs hardness.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disk brake comprising a combination of a disk rotor made of an aluminum composite material and a friction material for pressing the disk rotor. By paying attention to the average particle diameter, the performance of the friction material is enhanced.

That is, the average particle diameter of the hard inorganic material blended in the friction material is 1 μm or more, and the average particle diameter of the hard inorganic material is adjusted to the average particle diameter of the hard inorganic material contained in the aluminum composite material constituting the disk rotor. That is, it is smaller than the average particle diameter.

If the average particle diameter of the hard inorganic material contained in the friction material is less than 1 μm, the effect of adding the hard inorganic material is not recognized, which is not preferable. Furthermore, the upper limit of the average particle size of the hard inorganic material in the friction material is determined in relation to the ratio with the average particle size of the hard inorganic material contained in the disk rotor. For example, the ratio of the average particle size of the hard inorganic material used for the friction material to the average particle size of the hard inorganic material contained in the disk rotor is preferably in the range of 1:20 to 2. When the ratio to the average particle diameter of the hard inorganic material is smaller than 1:20, the average particle diameter of the hard inorganic material in the friction material becomes smaller than the average particle of the hard inorganic material in the disk rotor, and the friction material becomes harder. The effect of scraping off the coating formed on the rotor sliding surface is weakened, and the coating is deposited on the disk rotor sliding surface, which increases the wear of the friction material and lowers the friction coefficient, which is not preferable. Conversely, if the ratio of the average particle diameters exceeds 1: 2, the friction material not only scrapes off the coating but also damages the disk rotor side, which is undesirable because brake judder is generated.

As the hard inorganic material blended in the friction material, alumina, silicon carbide or the like having a high Mohs hardness of 9 or more can be used. If the Mohs hardness of the hard inorganic material mixed with the friction material is less than 9, wear of the friction material increases and the friction coefficient decreases, which is not preferable.

A disk rotor made of an aluminum composite material has an aluminum alloy as a matrix and hard inorganic particles having a Mohs hardness of 9 such as silicon carbide and alumina.
High hardness particles are included.

By setting the average particle diameter of the hard inorganic material of the friction material within the above range, the friction material corresponding to the above-mentioned aluminum rotor has excellent braking effect and wear resistance, and performance with suppressed brake squeal. Can be demonstrated.

Here, the friction material comprises a base fiber, a binder, a hard inorganic material, and a filler.

As the base fiber, inorganic fibers such as rock wool, glass fiber, silicate fiber, carbon fiber, potassium titanate fiber and calcium silicate fiber, steel fiber, and copper fiber used in conventional friction materials are used. Metal fibers such as brass fibers and bronze fibers; aromatic polyamide fibers such as hemp, cotton and aramid fibers; and organic fibers such as phenol fibers.

As the filler, graphite as a lubricant,
Inorganic substances such as metal sulfides, such as molybdenum disulfide and antimony disulfide, organic dusts such as cashew dust and rubber dust, and copper, brass, zinc, iron and the like can be used as metal powders. Further, fillers used for friction materials such as barium sulfate, calcium carbonate, slaked lime, mica, kaolin, and talc can be used.

In addition to the phenol resin, an epoxy resin, a polyimide resin and the like can be used as the binder.

The ratio of these compounding materials is 5 to 5
25% by volume, preferably 8 to 20% by volume, hard inorganic material 3 to 20% by volume, preferably 5 to 15% by volume, lubricant 5 to 15% by volume, preferably 8 to 13% by volume, and organic dust 1 to 25% by volume, preferably 3 to 20% by volume, metal powder 1 to 10% by volume, preferably 2 to 6% by volume, binder 10 to 30% by volume, preferably 15 to 25% by volume, and other filling The material is used in an amount of 0 to 40% by volume. After they are sufficiently mixed, they are produced by thermoforming under pressure and heat treatment.

[0023]

The present invention will be specifically described below with reference to examples.

Example 1 15% by volume of a mixture of aramid fiber, ceramic fiber and copper fiber as base fiber, 20% by volume of phenol resin as binder, and mixture of cashew dust, barium sulfate, graphite and slaked lime as filler. 55% by volume, alumina powder 1 having an average particle diameter of 1 μm of hard inorganic material
And 0% by volume with a universal mixer for 10 minutes to obtain a mixed powder. This mixed powder is put into a mold at 160 ° C.,
It was heated and pressed at a pressure of 30 MPa for 10 minutes. 2 after molding
Heat treatment was performed in a furnace at 20 ° C. for 6 hours to obtain the friction material of Example 1. The Mohs hardness of the alumina powder is 9.

As the disk rotor corresponding to the friction material, 70% by volume of a matrix of an aluminum alloy of JIS standard and 30% by volume of silicon carbide having an average particle diameter of 20 μm are used.
Was produced. Mohs hardness of silicon carbide is 9.5.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1:20.
It is. Table 1 shows the compositions of the friction material and the disk rotor.

Example 2 In Example 1, 10% by volume of alumina powder having an average particle diameter of 2 μm of the hard inorganic material was used.
Except for using it, it was manufactured in the same manner as in Example 1 to obtain Example 2.
Was manufactured. Mohs hardness of silicon carbide is 9.5.

As the disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of an aluminum alloy of the same JIS standard as in Example 1 and 30% by volume of silicon carbide having an average particle diameter of 20 μm was used.

The ratio between the average particle size of the hard inorganic material of the friction material and the average particle size of the hard inorganic material of the disk rotor is 1:10.
It is.

Example 3 The same procedure as in Example 1 was carried out except that 10% by volume of silicon carbide powder having an average particle diameter of 4 μm as a hard inorganic material was used. A friction material was produced. The Mohs hardness of silicon carbide is 9.
5

As the disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of the same JIS standard aluminum alloy as in Example 1 and 30% by volume of silicon carbide having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1: 5.

Example 4 A friction material of Example 4 was manufactured in the same manner as in Example 1 except that 10% by volume of silicon carbide powder having an average particle diameter of 10 μm was used as the hard inorganic material. Materials were produced. The Mohs hardness of silicon carbide is 9.
5

As a disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of an aluminum alloy of the same JIS standard as in Example 1 and 30% by volume of silicon carbide having an average particle diameter of 20 μm was used. The Mohs hardness of alumina is 9.

The ratio between the average particle size of the hard inorganic material of the friction material and the average particle size of the hard inorganic material of the disk rotor is 1: 2.

Example 5 A friction material of Example 5 was produced in the same composition and method as in Example 1.

As the disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of the same JIS standard aluminum alloy as in Example 1 and 30% by volume of alumina having an average particle diameter of 20 μm was used. The Mohs hardness of alumina is 9.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1:20.
It is.

Example 6 A friction material of Example 6 was produced in the same composition and method as in Example 4.

As the disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of the same JIS standard aluminum alloy as in Example 1 and 30% by volume of alumina having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1: 2.

Comparative Example 1 In Example 1, 10 parts of silicon carbide powder having an average particle diameter of 0.7 μm were used as the hard inorganic material.
A friction material of Comparative Example 1 was manufactured in the same manner as in Example 1 except that the volume% was used.

As the disk rotor corresponding to the friction material, a disk rotor composed of 70% by volume of a matrix of the same JIS standard aluminum alloy as in Example 1 and 30% by volume of silicon carbide having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1: 2.
8.6.

Comparative Example 2 The friction material of Comparative Example 2 was manufactured in the same manner as in Example 1 except that 10% by volume of alumina powder having an average particle diameter of 20 μm was used as the hard inorganic material. Was prepared.

As the disk rotor corresponding to the friction material, a disk rotor composed of 70% by volume of a matrix of an aluminum alloy of the same JIS standard as in Example 1 and 30% by volume of silicon carbide having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1: 1.

Comparative Example 3 In Example 1, alumina powder having an average particle size of 0.8 μm was used as a hard inorganic material.
A friction material of Comparative Example 3 was manufactured in the same composition and method as in Example 1, except that the volume% was used.

As a disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of an aluminum alloy of the same JIS standard as in Example 1 and 30% by volume of alumina having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1:25.
It is.

Comparative Example 4 A friction material of Comparative Example 4 was produced by the same composition and method as in Example 3, except that 10% by volume of silicon carbide having an average particle diameter of 20 μm was used as the hard inorganic material. did.

As a disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of an aluminum alloy of the same JIS standard as in Example 1 and 30% by volume of alumina having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1: 1.

Comparative Example 5 In Example 1, the amount of the filler was 53% by volume and the average particle size of the hard inorganic material was 2%.
A friction material of Comparative Example 5 was produced in the same composition and method as in Example 1 except that zirconium silicate having a thickness of 12 μm was used. Mohs hardness of zirconium silicate is 7.5.

As a disk rotor corresponding to the above friction material, a disk rotor composed of 70% by volume of a matrix of an aluminum alloy of the same JIS standard as in Example 1 and 30% by volume of alumina having an average particle diameter of 20 μm was used.

The ratio of the average particle size of the hard inorganic material of the friction material to the average particle size of the hard inorganic material of the disk rotor is 1:10.
It is.

The friction coefficient of each combination of the friction materials of Examples 1 to 6 and Comparative Examples 1 to 5 and the disk rotor was measured and evaluated. The results are shown in Table 1.

The coefficient of friction was measured by setting the test environment at 23 ° C.-6
Using a diometer with a constant 5 RH%, JASO
The measurement was performed at a deceleration of 0.35 G and a pre-brake temperature of 120 ° C. The amount of wear was measured with a micrometer after the test. The test was conducted with a friction material of 32.8 cm ² × 15.5 mm and an outermost diameter of 23.
A 5 mm aluminum disk rotor and a 51.1 mm cylinder diameter brake caliper were used.

Table 1 also shows the amount of wear of the friction material and the amount of wear of the disk rotor.

[0060]

[Table 1]

As shown in Table 1, the friction materials of Examples 1 to 6 have a large coefficient of friction and little change regardless of the speed.
It can be seen that the wear amount of the friction material is small and excellent as compared with Comparative Examples 1 to 5.

Further, the amount of wear of the disk rotor was determined in Example 1.
# 6 to # 6 are less than Comparative Examples # 1 to # 5.

The reason why the wear amount of the disk rotors of Comparative Examples 2 and 4 cannot be measured is that the disk rotor friction surface was damaged. Further, the negative value of the wear amount of the disk rotor means that the disk rotor has become thick due to the adhesion of the transfer film.

For the combination of the friction material of Example 2 and the disk rotor, a brake squeal measurement test was performed using a dynamometer. Test environment is 10 ℃ -80RH%
At a constant speed of 10 to 30 km / h and a hydraulic pressure of 0.196.
Combination of ~ 1.96MPa, braking temperature 40 ℃ ~ 200
C., and the frequency analysis device detected sound exceeding 60 dB as squeal.

As a result, during approximately 6,000 braking operations, the squealing rate (number of squealing occurrences / number of braking times × 100) = 0.7%, and the sound pressure level is very small at a maximum of 75 dB. Was.

[0066]

As described above, in the present invention, the average particle diameter of the hard inorganic material to be added to the friction material is smaller than the average particle diameter of the hard inorganic material added to the corresponding aluminum composite disk rotor. are doing. As a result, this friction material is excellent in coefficient of friction and wear resistance, has little occurrence of brake squeal, and can be applied with high performance to a lightweight aluminum composite disk rotor.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F16D 65/12 F16D 65/12 EM T 69/02 69/02 Z B (72) Inventor Akinori Nakayama Aichi 1141-1, Okawagahara, Iino, Fujioka-cho, Nishikamo-gun, Aichi, Japan Aisin Chemical Industry Co., Ltd. Aichiin Seiki Co., Ltd., 2-1-1 Asahi-cho, Kariya-shi, Japan (72) Inventor Hiroaki Nakanishi 1-Tenno, Takaoka-Shinmachi, Toyota-shi, Aichi F-term in Aisin Takaoka Co., Ltd. 3J058 AA41 AA57 AA58 AA62 BA21 BA23 BA41 BA46 BA76 CA42 CB11 GA04 GA07 GA23 GA24 GA26 GA28 GA33 GA35 GA37 GA38 GA41 GA45 GA54 GA55 GA57 GA62 GA63 GA64 GA65 GA73 GA82

Claims (3)

[Claims] 1. A disk brake comprising a combination of a disk rotor made of an aluminum composite material and a friction material for pressing the disk rotor, wherein the friction material is a base fiber, a binder, a hard inorganic material. , Filler and compound molding, the disk rotor composite material,
An aluminum alloy containing particles of hard inorganic material, wherein the hard inorganic material blended in the friction material has a hardness that can withstand the hard particles blended in the disk rotor, and has an average particle diameter of 1 μm or more; A friction material, wherein an average particle diameter of the hard inorganic material included in the friction material is smaller than an average particle diameter of the hard inorganic material included in the disk rotor. 2. The ratio of the average particle size of the hard inorganic material contained in the friction material to the average particle size of the hard inorganic material contained in the disk rotor is 1:20 to 1: 2. The friction material described. 3. The friction material according to claim 1, wherein the hardness of the hard inorganic material mixed in the friction material is 9 or more in Mohs hardness.