JPH10279923A - Friction material for hybrid brake material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction material suitable as a low μ friction material and used for a hydrid brake material. SOLUTION: This friction material has a friction coefficient of <=0.4 and a compression elastic modulus of 5-30 kgf/mm<2> . The friction material can be produced from a composition comprising 30-50 vol.% of a base material such as aramide fibers or carbon fibers, 10-15 vol.% of a binder, 15-40 vol.% of an organic filler, 2-10 vol.% of an inorganic filler, and 12-20 vol.% of a solid lubricant. The composition allows to enhance the porosity of the friction material and lower the compression elastic modulus of the friction 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 used for a hybrid brake material in which friction materials having different friction characteristics are combined. INDUSTRIAL APPLICABILITY The present invention can be used for, for example, a brake pad used for a disc brake device of a vehicle and a brake lining used for a drum brake device.

[0002]

2. Description of the Related Art Hitherto, hybrid brake materials having composite friction characteristics obtained by combining friction materials having different friction characteristics have been provided. As this kind of hybrid brake material, Japanese Utility Model Laid-Open Publication No. Sho 56-113241 discloses that a friction material having high wear resistance is arranged on the outer peripheral side and a friction material having low wear resistance is arranged on the inner peripheral side. Is disclosed.
According to this, uneven wear on the outer peripheral side of the friction material is suppressed,
It is advantageous for uniform wear resistance. However, this publication technique is intended to make wear resistance uniform, and is not intended to prevent squeal during braking.

[0003] Japanese Patent Application Laid-Open No. 5-164158 discloses that
There is disclosed a brake pad in which friction materials having different opponent aggressiveness are separately arranged in a sliding direction, and a groove is formed at a boundary between the two. In this publication, it is described that the grooves can suppress the deformation of the friction material and ensure the discharge of abrasion powder. By the way, in the case of brake materials, further reduction of brake "squeal" during braking is demanded.

[0004]

The inventor of the present invention has found that a low friction material having a relatively low friction coefficient is advantageous for "preventing squealing" of a brake, and that "squealing" occurs when the brake operation amount is small. Focusing on ease of use, in recent years a hybrid brake material with the hybrid characteristics of a system combining a high μ friction material with a relatively high friction coefficient and a low μ friction material with a relatively low friction coefficient has been developed in recent years ( Unknown at the time of this application).

In this hybrid brake material, when the brake operation amount is small, the friction coefficient is relatively low and the friction coefficient is low.
Since the degree of friction between the friction material and the mating material is high, it is advantageous for suppressing the "squeal" of the brake. Further, when the brake operation amount increases, the degree of friction of the high μ friction material having a relatively high friction coefficient against the mating material increases, so that the “effectiveness” of the brake is effectively secured.

In the above-mentioned hybrid brake material, in order to effectively secure the "effectiveness" of the brake, in order to increase the degree of friction between the high μ friction material and the mating material, the low μ friction material having a low friction coefficient is: As the braking operation increases, it is preferable that the compression be performed by the mating member. The present invention has been made in view of the above-described circumstances, and has a friction material for a hybrid brake material that is advantageous for reducing “squeal” during brake operation and that is advantageous for being retracted by being compressed as brake operation increases. The task is to provide.

[0007]

SUMMARY OF THE INVENTION The present inventor has been diligently developed based on the above-mentioned problems, and has a coefficient of friction of 0.4 or less and a compression modulus in the thickness direction of 5 to 30 kgf / m.
If the friction member is m ^2, and found to be suitable as a low μ friction material of the hybrid brake material having a hybrid characteristics described above, thereby completing the friction material according to the present invention.

Further, in terms of volume ratio, organic fibers and / or
Or 30 to 50% of inorganic fiber and 10 to 15 of binder
%, Organic filler 15-40%, inorganic filler 2-10
% And a solid lubricant having a composition containing 12 to 20%, the compression elastic modulus of the friction material can be reduced while the friction coefficient of the friction material is lowered, thereby being used for the hybrid brake material described above. The present inventors have found that it is advantageous to produce a friction material having a relatively small coefficient of friction and a small compression elastic modulus, and completed the present invention.

That is, the friction material for a hybrid brake material according to the first aspect is a friction material having a friction coefficient of 0.4 or less used for a hybrid brake material in which friction materials having different friction characteristics are combined. Rate is 5-30k
gf / mm ² . The friction material for a hybrid brake material according to claim 2, wherein the organic fiber and / or the inorganic fiber is 30 to 50% as a base material, the binder is 10 to 15%, and the organic filler is 15 to 40% in volume ratio. It is characterized by having a composition containing 2 to 10% of an inorganic filler and 12 to 20% of a solid lubricant.

[0010] The friction material for a hybrid brake material according to claim 3 is the friction material according to claims 1 and 2 having a porosity of 1 by volume ratio.
5-30%. The friction material for a hybrid brake material according to claim 4 is the method according to claim 2,
The base material contains carbon long fibers, and the volume ratio of carbon long fibers to the friction material is 10 to 20%.

According to a fifth aspect of the present invention, in the friction material for a hybrid brake material according to the second aspect, the inorganic filler contains silica glass particles, and the volume ratio of the silica glass particles to the friction material is 2 to 10%. It is characterized by.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical form of a friction material for a hybrid brake material according to the present invention will be described. In the friction material according to the present invention, generally, organic fibers and / or inorganic fibers are used as the base material. Specifically, aramid fibers (generally para-based), carbon fibers, potassium titanate fibers, metal fibers, and the like can be used as the base material. When the proportion of the base material increases, the porosity of the friction material tends to increase due to the influence of the wettability between the base material and the binder.

As carbon fibers, carbon long fibers (fiber length: 1 mm or more) and short carbon fibers (fiber length: less than 1 mm) can be used. The carbon long fiber has an action of appropriately scraping off the film formed on the friction surface of the mating material while securing the strength of the base material. Therefore, it is easy to stabilize the friction surface of the mating material, and eventually the friction surface of the friction material, which is advantageous for lowering and stabilizing the friction coefficient of the friction material.

As the binder, known binders conventionally used in friction materials can be used, and specifically, phenol resins and epoxy resins can be employed. Further, a polyimide resin type and a polyamide imide resin type can also be expected. Cashew dust, rubber dust and the like can be adopted as the organic filler. Barium sulfate as inorganic filler,
Silica glass particles, alumina particles and the like can be employed. As the solid lubricant, graphite, antimony trisulfide, or the like can be used. The above-mentioned inorganic filler, organic filler, and solid lubricant can function as a friction and wear modifier. In order to produce the friction material having the friction coefficient and the compression modulus according to the first aspect, the composition according to the second aspect is preferable.
Further, the composition defined in claim 2 is advantageous for producing a friction material having a small wear rate in addition to a friction coefficient and a compressive modulus. In this case, the composition of the friction material can be made as follows by volume ratio.

Base material (aramid fiber, carbon fiber) 30-50% Binder (phenol resin, etc.) 10-15% Organic filler (cashew dust, rubber dust, etc.) 15-40% Inorganic filler (barium sulfate, silica) Glass particles, etc.) 2 to 10% Solid lubricant (graphite, antimony trisulfide, etc.) 12 to 20% Given the above composition, the following required values of (1) and (2), or (1) to The requirement of (3) can be satisfied.

(1)... Friction coefficient μ ≦ 0.4, especially friction coefficient μ ≦ 0.35 (2)... Compression elastic modulus E = (5 to 30) [kgf / mm ² ], particularly (8) ~ 30) [kgf / mm ² ] (3) ... Wear rate W ≦ 1.5 × 10 ^-4 [mm ³ / kgf · m] If the above composition is specified, the friction coefficient and the compression modulus In addition, a friction material having a small wear rate can be manufactured. The coefficient of friction, compression modulus, and wear rate were based on test methods described later.

Incidentally, physical properties of general friction materials for brakes are as follows (1 ') to (3'), and the compression elastic modulus is considerably higher than that of (2). (1 ′): friction coefficient μ = 0.4 to 0.5 (2 ′): compression modulus E = (50 to 200) [kgf / mm ² ] (3 ′): wear rate W = ( 1-4) × 10 ⁻⁴ [mm ³ / kgf · m] According to the above composition, the ratio of the base material and the organic filler is large, and the ratio of the binder is small. In such a composition of the friction material, the volume ratio of (base material / binder) = (50% / 10%) to
(30% / 15%) = 5-2. In addition, [(base +
The volume ratio of (organic filler) / binder)) can be set to 7.5 to 4.5. Reasons for Limiting Composition According to the Above-mentioned Embodiment In order to obtain a friction material having a friction coefficient and a compressive elastic modulus according to claim 1, it is preferable that the composition is specified in the above-described ratio.

Hereinafter, the reasons for limiting the composition will be described.
As described above, if the volume ratio of the base material is increased to 30 to 50%, the ratio of the organic filler is increased to 15 to 40%, and the binder is reduced to 10 to 15%, the pores in the friction material are reduced. It is easy to increase. It is presumed to be caused by wettability between the base material and the binder, wettability between the organic filler and the binder, and the like.
If the porosity of the friction material increases in this way, the compression elastic modulus of the friction material can be reduced.

The porosity of the friction material is 15-30%, preferably 20%.
~ 30% is preferred. In this case, the compression modulus of the friction material is considerably reduced. Therefore, it is advantageous to provide a friction material having both low coefficient of friction and low compression modulus. In addition,
As for the form of the pores, pores of 5 μm or less can occupy 80% of the pores. When the base material is less than 30%, the compression elastic modulus of the friction material tends to increase more than 30 kgf / mm ² . If the base material exceeds 50%, the strength of the friction material tends to decrease. Similarly, when the binder content exceeds 15%, the compression elastic modulus becomes 3
It is easier to increase than 0 kgf / mm ² . If the amount of the binder is less than 10%, the strength of the friction material tends to decrease.

Further, since the organic filler is as large as 15 to 40%, pores are easily secured due to the wettability between the organic filler and the binder. In this sense, it is advantageous for reducing the compression modulus of the friction material. Organic fillers generally tend to contribute to the formation of a lubricating film on the friction surface. Since such an organic filler is as large as 15 to 40%, it is advantageous for improving the wear resistance of the friction material, that is, for reducing the wear rate of the friction material.
If the amount of the organic filler is less than 15%, the compression modulus of the friction material is increased, and the wear resistance is deteriorated, so that the physical property values may deviate from the required values described above. If the amount of the organic filler exceeds 40%, the film formed on the friction surface tends to be thick, and the friction coefficient μ tends to be unstable.

When the amount of the inorganic filler is 2 to 10%, the wear resistance of the friction material is improved. If it is less than 2%, the wear resistance decreases and the wear rate W increases, for example, 1.5 × 10
^{It is} easier to increase than ^-4 mm ³ / kgfm. When the amount of the inorganic filler exceeds 10%, the friction coefficient μ increases and the composition tends to become unstable. By setting the solid lubricant to 12 to 20%, it is possible to expect formation of a good lubricating film by the solid lubricant, which is advantageous for reducing the friction coefficient μ and improving the wear resistance of the friction material. If the amount of the solid lubricant is less than 12%, the friction coefficient μ tends to increase more than 0.4, and the wear rate of the friction material tends to increase, so that the above-mentioned required value may not be satisfied. When the amount of the solid lubricant exceeds 20%, the thickness of the lubricating coating of the friction material tends to be unstable depending on friction conditions, and the friction coefficient μ tends to be unstable.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 to 3 of the present invention will be described below together with a conventional example. Each raw material was adjusted so as to have the composition shown in Table 1, and the friction materials of Examples 1 to 3 were manufactured together with the conventional friction materials.

[0023]

[Table 1] The conditions of the above-mentioned raw materials are as follows. Aramid fiber (para-based) having an average fiber length of 2 mm was used. The potassium titanate fiber is a needle-like fiber and has a fiber length of 10 to 10.
Those having a diameter of 20 μm and a fiber diameter of 0.3 to 0.6 μm were used. The short carbon fibers are pitch-based and have a fiber length of 0.1.
1 mm and a fiber diameter of 10 μm were used. The carbon long fiber is a bread type, and has a fiber length of 3 mm and a fiber diameter of 10
μm and a tensile strength of 300 kgf / mm ² were used. Cashew dust having an average particle diameter of 200 μm was used. Graphite was natural graphite having an average particle size of 6 μm. The silica glass particles were hollow glass spheres having an average particle diameter of 35 μm. Copper is a copper fiber having a fiber length of 1.5 mm and a fiber diameter of 10
The thing of 0 μm was used. The alumina particles have an average particle size of 5
μm was used.

As a method for producing the friction material, the mixing step, the preforming step, the thermoforming step, and the heat treatment step were performed in this order.
In the mixing step, the raw materials are mixed using an Erich mixer.
Mix for minutes. In the preforming step, compression molding was performed using a press at a surface pressure of 130 kgf / cm ² and a molding time of 5 seconds. In the thermoforming step, a pressing machine is used to adjust the temperature to 160
Thermoforming was performed at a temperature of 400 ° C., a surface pressure of 400 kgf / cm ² and a molding time of 5 minutes. In the heat treatment step, heat treatment was performed at a temperature of 220 ° C. for 3 hours using a heat treatment furnace.

When the porosity of the friction material was measured by a mercury intrusion method, it was as low as 10 to 12% for the conventional friction material.
The friction material of Example 1 was 18 to 20%, the friction material of Example 2 was 22 to 25%, and the friction material of Example 3 was as high as 25 to 28%. A friction test, a compression test, and a wear test were performed on each of the friction materials according to Examples 1 to 3 and the conventional example manufactured as described above, and the friction coefficient, compression elastic modulus, and wear amount of each friction material were measured. (A-1) The conditions of the friction coefficient test for measuring the friction coefficient μ are as follows.

Test machine: Full size dynamometer, Test condition: Implemented according to JASO C406, Braking start speed: 20 km / h, 50 km / h, 100 k
m / h and three types. (A-2) The conditions of the elastic compression test for measuring the compression elastic modulus are as follows.

Tester: Mechanical compression tester Test conditions: 500 kgf, 1000 kgf That is, when a load of 500 kgf was applied to the friction material, the amount of compressive strain in the thickness direction of the friction material and a load of 1000 kgf were applied to the friction material. The difference from the amount of compressive strain in the thickness direction of the friction material at that time is δ, the area of the friction material is A (44 mm ² ),
The thickness of the friction material before applying a load is t (10 mm),
Assuming that the load difference is F, the compression modulus E is E = (F /
A) / (δ / t). (A-3) The conditions of the wear test for measuring the wear rate W are as follows.

Test machine: full-size dynamometer Test condition: braking start speed 50 km / h number of brakings 500 times at each temperature Deceleration 0.15 G The temperature of the friction material before starting braking was 100 ° C. and 200 ° C.

That is, a brake was applied from a vehicle speed of 50 km / h, and the vehicle was decelerated at a deceleration of 0.15 G and stopped. This was repeated 500 times. And the wear rate W at each temperature
_T was determined based on the following equation. W _T = ｛[2 × (A1 × t1 + A2 × t2) × r ² ]
/ [I × V ² × n]} where A1 is the area of the friction surface of the first friction material, and t1 is the first friction material.
The wear thickness of the friction surface of the friction material, A2 is the area of the friction surface of the second friction material, t2 is the wear thickness of the friction surface of the second friction material, I is the inertial mass of the rotating part, and V is the braking mass at the start of braking. The vehicle speed, r indicates the effective radius of the tire, and n indicates the number of times of braking. In order to sandwich the disk rotor, which is the mating member, between the first friction material and the second friction material, the above formula takes into account the wear of the first friction material and the second friction material.

The wear rate W of the friction material is 100
° based on the wear rate W ₂₀₀ in wear rate W ₁₀₀ and 200 ° C in C, determined by the following equation. W = 0.8 × W ₁₀₀ + 0.2 × W ₂₀₀ The test results in each test are as follows. (B-1) Test Results of Friction Test FIG. 1 shows the test results of the friction coefficient for the friction material of Example 1. FIG. 2 shows the test results of the coefficient of friction with respect to the friction material of Example 2. FIG. 3 shows the test results of the coefficient of friction with respect to the friction material of Example 3. FIG. 4 shows a test result of the friction coefficient of the conventional material with respect to the friction material. 1 to 4, the horizontal axis indicates the hydraulic pressure meaning the pedaling force at the time of braking, the vertical axis indicates the friction coefficient μ, ◆ indicates a speed at the start of braking of 20 km / h, ■ indicates 50 km / h, ○ indicates the case of 100 km / h.

As can be understood from FIG. 4, the conventional friction material has a high friction coefficient μ exceeding 0.35. In particular, when the speed is 20 km / h, the coefficient of friction exceeds 0.45. On the other hand, as can be understood from FIGS.
Are all 0.4 or less. In particular, except for the oil pressure of 10 kgf / cm ² at 20 km / h shown in FIG. Considerable data is 0.
3 or less. Therefore, the friction materials of Examples 1 to 3 satisfy the required value for the reduction of the friction coefficient, and
This is advantageous for reduction of

Further, in the friction material of the first embodiment, as can be understood from FIG. 1, the hydraulic spread (= the variation of the friction coefficient μ) at each braking speed is slightly large. On the contrary,
In the second and third embodiments, as can be understood from FIGS. 2 and 3, the hydraulic spread is smaller than in the first embodiment. This is because, in the friction materials of Examples 2 and 3, carbon long fibers are blended instead of carbon short fibers, so that the base material strength is improved, it is difficult to transfer to the mating material, and the friction material is formed on the mating material. It is inferred that the friction coefficient μ was stabilized by scraping the film thus formed. In other words, it is considered that the long carbon fiber has an effect of stabilizing the film formed on the friction surface of the friction material and the surface of the mating material by improving the strength of the base material and scraping the film formed on the mating material.

5 shows the change in the coefficient of friction when the frictional material similar to the second embodiment, that is, the low μ frictional material, is used and the braking start speed is 50 km / h. The horizontal axis in FIG. 5 shows the hydraulic pressure during braking, and the vertical axis shows the friction coefficient μ. 5 in FIG.
Indicates a change in the friction coefficient of the high μ friction material. When applied to a friction material for a brake having a hybrid characteristic of a system as shown in FIG. 8 described later, a low μ friction material comes into contact with a mating material at the time of light depression at the beginning of braking, and braking, that is, as the depression proceeds, Since the degree of contact of the high-μ friction material with the counterpart material is increased, a hybrid friction characteristic shown by ○ in FIG. 5 is obtained. (B-2) Test Result of Compression Test FIG. 6 shows the test result of the compression test described above. As can be understood from FIG. 6, the compression modulus E = 6 in the conventional friction material.
It is as large as 5 [kgf / mm ² ]. On the other hand, Embodiment 1
, The compression elastic modulus E 10 [kgf
/ Mm ² ], which satisfies the required value for the compression modulus. (B-3) Test Results of Wear Test FIG. 7 shows test results of the wear test. As can be understood from FIG. 7, the conventional friction material has a wear rate W = 2.2 × 10
^-4 [mm ³ / kgf · m]. On the other hand, in the friction materials of Examples 1 to 3, the wear rate W ≦ 1.5 × 10 ⁻⁴ [m
m ³ / kgf · m], which satisfies the required value for the wear rate.

As can be understood from FIG. 7, the friction material of the third embodiment has a smaller wear rate and better wear resistance than the other first and second embodiments. This is inferred because the silica glass particles were blended in the friction material of Example 3. That is, even if the silica glass particles themselves have high abrasion resistance, and even if the silica glass particles fall off and are bound at the friction boundary, the silica glass particles are spherical, so that they are difficult to attack the friction material and the partner material. It is inferred that there is.

(Application Example) FIGS. 8 to 10 show application examples. This application example is applied to a hybrid brake material used as a brake pad of a disc brake device of a vehicle. FIG. 8 shows a state in which the hybrid brake material 1 is mounted on the back metal 2. B indicates the rotation center of the disk rotor, which is a counterpart of the disk brake device. FIG. 9 shows a cross section along the line A1-A1 in FIG.

The hybrid brake material 1 according to this application example is a combination of friction materials having different friction characteristics. Specifically, the hybrid brake material 1 has a low μ friction material 3 having a relatively low friction coefficient and a friction material having a relatively low friction coefficient. It is configured by combining with a relatively high high μ friction material 4. In FIG. 8, the area of the low μ friction material 3 having a low coefficient of friction is indicated by oblique lines and has a predetermined width M.
Are arranged along the friction sliding direction with a large radius of curvature, that is, substantially coaxially in the shape of an arc band in the direction of arrow B3 around the rotation center B of the disc brake rotor. The remaining area of the hybrid brake material 1 is a high-μ friction material 4 having a high friction coefficient. Note that the exposed area of the high μ friction material 4 is made larger than the exposed area of the low μ friction material 3 in order to secure the “effectiveness” of the brake.

According to this embodiment, in a normal state,
As shown in FIG. 9, the low μ friction material 3 having a low friction coefficient projects ΔL1 more toward the counterpart material side than the high μ friction material 4 having a high friction coefficient. Note that ΔL1 can be appropriately selected according to the type of the hybrid brake material 1, the operating conditions, the demands of the brake feeling, and the like. Generally, it can be 0.5 mm or less, particularly 0.3 mm or less, but is limited to this. Instead, it may be about 1 mm in some cases.

Hereinafter, the friction coefficient used in this application example is low and low.
The characteristics of μ friction material 3 and high μ friction material 4 with high friction coefficient are explained.
I will tell.・ Low μ friction material 3 Friction coefficient μ_L: 0.25 to 0.35 Compression modulus E_L: 8 to 30 [kgf / mm^Two] Wear rate W_L: (0.9 to 1.0) × 10^-Four[Mm^Three/ K
gf ・ m] ・ High μ friction material 4 Friction coefficient μ_H: Compression modulus E exceeding 0.4_H: 50 to 110 [kgf / mm^Two] Wear rate W_H: (1.4 to 2.5) × 10^-Four[Mm^Three/ K
gf · m] Here, in this application example, the wear rate W of the high μ friction material 4_H/ Low
Wear rate W of μ friction material 3 _L) Is about 2.8. Ma
The area of the low μ friction material 3 is A_LAnd the area of the high μ friction material 4
A_HThen A_H/ A_L= 2.8.

As can be understood from the above description, according to this application example, the friction coefficient μ _L of the low μ friction material 3 is smaller than the friction coefficient μ _H of the high μ friction material 4 (μ _L <μ _H). ). Further, the compression elastic modulus E _L of the low μ friction material 3 is smaller than the compression elastic modulus E _H of the high μ friction material 4 (E _L <E _H ). The wear rate WL of the low μ friction material 3 is equal to the wear rate W _L of the high μ friction material 4.
_H is smaller than _H (W _L <W _H ), and the low-μ friction material 3 has good wear resistance and is hard to wear.

According to this application example, as can be understood from FIG. 9, the low μ friction material 3 projects more than the high μ friction material 4.
Therefore, at the time of the light pedaling force of the brake, the low μ friction material 3 having a small friction coefficient and effective for “reduction of squealing” firstly rubs against the disk brake rotor, that is, the mating material 6. Thereby, the problem of "squeal" at the time of the light pedaling force of the brake is reduced and avoided.

Also, at the time of the high pedaling force with the brake pedal stepped on, the low μ friction material 3 is compressed in the thickness direction as can be understood from FIG. As a result, the degree of friction of the high μ friction material 4 having a high friction coefficient μ _{H and a} large surface area with the counterpart material 6 is increased. As a result, the "effectiveness" of the brake is well ensured.
Furthermore, according to this application example, the compression modulus E _L of the low μ friction material 3
Is smaller than that of the high μ friction material 4, and has a characteristic of being easily compressed and retracted by the mating material 6. Thus, at the time of Koto force depression amount of the brake is increased, the compression modulus E _L is small low μ friction material 3 compressed proceeds. Therefore, the high μ friction material 4 having a high friction coefficient μ _{H and} having a strong “effectiveness” is more likely to rub against the mating material 6. Therefore, at high pedaling force,
This is even more advantageous for improving the "effectiveness" of the brake.

According to this application example, the friction of the low μ friction material 3 is reduced.
Wear rate W_LIs the wear rate W of the high μ friction material 4 _HLess than
Therefore, the wear of the low μ friction material 3 is relatively smaller than that of the high μ friction material 4.
Less. Therefore, when the brake is released
Low friction material 3 tends to protrude more than high μ friction material 4
Become. As a result, the protruding structure of the low μ friction material 3 shown in FIG.
Is easily maintained.

In addition, according to this application example, as can be understood from FIG. 8, the low μ friction material 3 and the high μ friction material 4 are arranged substantially coaxially, and both are arranged in the friction sliding direction, that is, along the arrow B3 direction. It is arranged. Therefore, the hybrid brake material 1
In the case where the friction member slides with the mating member 6, the problem that the low μ friction material 3 and the high μ friction material 4 are mixed due to the drag phenomenon of the friction material is suppressed. Therefore, even if the hybrid brake material 1 is used for a long period of time, it is possible to suppress a change in the friction characteristics of the hybrid brake material 1.

In some cases, as another application example,
In a normal state, the low μ friction material 3 does not protrude from the high μ friction material 4, and the friction material may have a structure in which the low μ friction material 3 and the high μ friction material 4 are substantially on the same plane. it can. In this case, as in the application example shown in FIG. 9 described above, at the time of high pedaling force, the compression load distribution of the high μ friction material 4 having a large compression elastic modulus is larger than that of the low μ friction material 3 having a small compression elastic modulus. Easy to be. Therefore, "effectiveness" while suppressing "squealing" of brakes
It is advantageous to ensure. 11 and 12 show other application examples. This application example is applied to a hybrid brake material 11 used as a lining of a drum brake device of a vehicle. FIG. 11 shows a state in which the hybrid brake material 11 is mounted on the back metal 21. FIG. 12 shows a cross section along the line A2-A2 in FIG.

The hybrid brake material 11 according to this application example is a combination of friction materials having different friction characteristics as in the case described above. Specifically, the low brake friction material has a relatively low friction coefficient. A material 31 is combined with a high-μ friction material 41 having a relatively high friction coefficient. In FIG. 11, the area of the low μ friction material 31 having a low coefficient of friction is indicated by oblique lines, and has a large radius of curvature having a predetermined width and is substantially coaxially formed in an arc band shape in the direction of arrow B4 along the friction sliding direction. It is arranged. Note that the exposed area of the high μ friction material 41 is made larger than the exposed area of the low μ friction material 31 in order to secure braking characteristics.

According to this embodiment, in a normal state,
As shown in FIG. 12, the low μ friction material 31 having a low friction coefficient
Δ is closer to the mating material 61 than to the high μ friction material 41 having a high friction coefficient.
L2 protrudes. ΔL2 can be appropriately selected according to the type of hybrid brake material 11, usage conditions, brake feeling requirements, and the like. Generally, ΔL2 can be 0.5 mm or less, particularly 0.3 mm or less, but is limited to this. Instead, it may be about 1 mm in some cases.

According to this application example, the friction coefficient μ _L of the low μ friction material 31 is smaller than the friction coefficient μ _H of the high μ friction material 41 (μ _L <μ), as in the above application example. _H ).
Also, the compression modulus E _L of the low μ friction material 31 is
It is smaller than the compression modulus E _H (E _L <
E _H ). The low wear rate of μ friction material 31 W _L is smaller than the wear rate W _H of the high-μ friction material 41 (W _L <
W _H ).

Also in this application example, as shown in FIG. 12, the low μ friction material 31 projects more than the high μ friction material 41. Therefore, at the time of the light pedaling force of the brake, the low-μ friction material 31 having a small friction coefficient and effective for “reduction of squealing” firstly rubs against the drum, that is, the mating material 61. Thereby, the problem of "squeal" at the time of the light pedaling force of the brake is reduced and avoided.

Also, at the time of a high pedaling force with an increased depression of the brake, the low μ friction material 31 having a small compression elastic modulus is compressed in the thickness direction. As a result, the degree of friction of the high μ friction material 41, which has a high friction coefficient μ _{H and} is strong in “effectiveness”, against the partner material increases.
As a result, the "effectiveness" of the brake is well ensured. Note that the low μ friction material 31 and the high μ friction material 41 used in this application example were used.
Can be basically the same as those in the application example.

[0050]

According to the friction material for a hybrid brake material according to the first aspect, the coefficient of friction is low and the compression modulus is 5 to 5.
30 kgf / mm ² , and both the coefficient of friction and the compression modulus are low. As described above, a friction material having such physical properties combines a high μ friction material having a relatively high friction coefficient with a low μ friction material having a relatively low friction coefficient to provide a low μ friction during a high braking operation. It is suitable for use as a low-μ friction material among hybrid brake materials that are expected to be retracted by compression of the material.

According to the friction material for a hybrid brake material according to the second aspect, in terms of volume ratio, the base material is composed of 30 to 50% of organic fibers and inorganic fibers, 10 to 15% of binder, and 15 to 15% of organic filler. 40%, 2-10% inorganic filler and 12-20% solid lubricant. With such a composition, the proportion of the base material is large, the proportion of the binder is small, and the proportion of the organic filler is large. Therefore, the porosity of the friction material is easily secured appropriately, and the compression modulus is easily reduced.

Therefore, the coefficient of friction is 0.4 or less, especially 0.1.
35 or less, and the compression modulus is 5 to 30 kgf / mm ²
It is advantageous to provide a low μ friction material having the following physical properties.
Therefore, it is suitable for use as a low μ friction material among the above-mentioned hybrid brake materials. According to the friction material for a hybrid brake material according to claim 3, the porosity is 15 to 3.
Since it is 0%, the porosity is higher than that of a general friction material, which is advantageous in reducing the compression modulus of the friction material.
Therefore, a soft friction material having a compression modulus in the range of 5 to 30 kgf / mm ² is easily obtained. Therefore, it is advantageous to provide a low μ friction material having both low coefficient of friction and low compression modulus.

For effective braking, it is preferable to appropriately scrape off the film formed on the friction surface of the mating material due to transfer or the like during braking. In this respect, according to the friction material for a hybrid brake material according to claim 4, the carbon long fiber is 10 to 20% by volume ratio. Since carbon long fibers have an action of appropriately scraping off the film formed on the mating material, it is easy to stabilize the friction surface of the mating material, and eventually the friction surface of the friction material. Therefore, it is advantageous for stabilizing the friction coefficient of the friction material to a lower level.

According to the friction material for a hybrid brake material according to claim 5, the silica glass particles have a volume ratio of 2 to 10%.
%. Since the silica glass particles themselves have wear resistance, the wear rate of the friction material is reduced. Further, since the silica glass particles have a spherical shape or a shape close to a spherical shape, even if the silica glass particles fall off from the friction material, the aggressiveness to the mating material and the friction material is low. Therefore, it is advantageous in improving the wear resistance of the friction material and reducing the wear rate of the friction material. Therefore, it is advantageous to provide a low μ friction material having a low coefficient of friction, a low compression modulus, and a low wear rate.

[Brief description of the drawings]

FIG. 1 is a graph showing a test result of a friction coefficient according to Example 1.

FIG. 2 is a graph showing a test result of a coefficient of friction according to Example 2.

FIG. 3 is a graph showing a test result of a friction coefficient according to Example 3.

FIG. 4 is a graph showing a test result of a friction coefficient according to a conventional example.

FIG. 5 is a graph showing a test result of a friction coefficient according to another example.

FIG. 6 is a graph showing a test result of a compression elastic modulus of a friction material.

FIG. 7 is a graph showing a test result of a wear rate of a friction material.

FIG. 8 is a front view showing an example in which a friction material is applied to a brake pad of a disc brake device.

FIG. 9 is a cross-sectional view showing a state before a mating member comes into contact with a friction material.

FIG. 10 is a cross-sectional view showing a state after a mating member comes into contact with a friction material.

FIG. 11 is a perspective view showing an example in which a friction material is applied to a brake lining of a drum brake device.

FIG. 12 is a cross-sectional view showing a state before a mating material comes into contact with a friction material.

[Explanation of symbols]

In the figure, 1 denotes a hybrid brake material, 2 and 21 denote back metal, 3 and 31 denote low μ friction materials, and 4 and 41 denote high μ friction materials.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 5/14 C08J 5/14 C10M 103/02 C10M 103/02 Z 103/06 103/06 C F16D 69/02 F16D 69/02 Z

Claims (5)

[Claims] A friction coefficient of 0.1 is used for a hybrid brake material in which friction materials having different friction characteristics are combined.
A friction material for a hybrid brake material, wherein the friction material has a compression modulus of 5 to 30 kgf / mm ² or less. 2. A volume ratio of 30-50% of organic fibers and / or inorganic fibers, 10-15% of binder, 15-40% of organic filler and 2-10% of inorganic filler as a base material. A friction material for a hybrid brake material, wherein the friction material has a composition containing 12 to 20% of a solid lubricant. 3. A friction material for a hybrid brake material according to claim 1, wherein the porosity is 15 to 30% by volume. 4. The method according to claim 2, wherein the base material contains carbon filaments, and the volume ratio of carbon filaments to the friction material is 10%.
A friction material for a hybrid brake material, wherein the friction material is about 20%. 5. The friction material for a hybrid brake material according to claim 2, wherein the inorganic filler contains silica glass particles, and the silica glass particles have a volume ratio of 2 to 10% with respect to the friction material.