JPH06229434A - Wet type friction material - Google Patents

Abstract

PURPOSE:To obtain wet type friction material which can slip smoothly against counterpart material, can be uniformalized and can restrain judder phenomenon, by forming high elastic carbon layer on sliding surface of the wet type friction material body in which binding resin is impregnated in paper made body and hardened by heating. CONSTITUTION:Paper made body is obtained from raw materials such as pulp 45wt.%, diatomaceous earth 25wt.%, organic fiber 10wt.%, friction regulating agent 10wt.%, and carbon powder 10wt.%. In making of the paper made body, moisture in slurry 12 is filtered as filfered water 16 and filtered dregs 17 is formed gradually over a filter net 15, while an endless filter net 15 moves upwards slantwise and appears above liquid surface through a filter net roller 13 and a filter net roller 14, in the slurry 12 which consists of pulp, diatomaceous earth, organic fiber and friction controlling agent in a paper making vessel 11. Carbon powder 18 is added from the upper part just before the filter net 15 is exposed from the liquid surface, and moreover wet paper made body 19, in which the carbon powder 18 adheres to the surface of the filtered dregs 17, is wound up by a winding roller 20.

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 which is used in pressure contact with lubricating oil in an automatic transmission of an automobile or the like, and in particular, the occurrence of a judder phenomenon due to uneven sliding with a mating material. It relates to a wet friction material to be suppressed.

[0002]

2. Description of the Related Art Conventionally, a wet friction material used in an automatic transmission used in an automobile or the like is used for a mating material that rotates in an ATF (automatic transmission fluid) used as a lubricating oil. Pressing the wet friction material that is stopped to stop the rotation, or pressing the wet friction material that is rotating against the stationary partner material to rotate the partner material and the wet friction material at the same time. Due to
The driving force of the prime mover was transmitted or cut off. In recent years, with the development of the automatic transmission control method, a slip control method has been developed which attempts to transmit a driving force while generating a differential rotation between a wet friction material and a mating material. According to this method, the driving force is transmitted while the wet friction material and the mating material slide, so that a state similar to that of the half clutch occurs, and the transmission can be smoothly performed.

The above-mentioned wet friction material is generally heat-cured on a paper body made of a mixed material such as organic fibers such as pulp, rayon and polyamide, inorganic fibers such as rock wool and glass fibers, and friction modifiers and fillers. It is obtained by impregnating with a resin and curing. The thermosetting resin is used because it has been proved that it has good friction characteristics, is lightweight, and is inexpensive and durable.

Regarding the wet friction material, for example, JP-A-61-85443 and JP-A-1-169134.
Japanese Patent Laid-Open No. 1-288639, Japanese Patent Publication No. 2-6
The technology disclosed in Japanese Patent No. 1661 can be mentioned.

[0005]

However, the conventional wet friction material is easily offset and abutted against the mating material, and in particular, when the size is increased, the phenomenon is remarkable. If this deviation phenomenon occurs due to slippage between the wet friction material and the mating material, and a judder phenomenon that causes uneven contact occurs, problems such as vibration and squeal occur. In addition, the true contact area is reduced, which causes a reduction in the friction coefficient. Therefore, it has been desired to make the slip between the wet friction material and the mating material uniform.

[0006] Therefore, an object of the present invention is to provide a wet friction material capable of smoothing and evenly slipping with a mating material and suppressing the judder phenomenon.

[0007]

According to a first aspect of the present invention, there is provided a wet friction material having a highly elastic carbon layer on a sliding surface portion of a main body of a wet friction material obtained by impregnating a paper-making body with a binder resin and heat curing. Formed.

In the wet friction material according to the invention of claim 2, carbon powder or carbon fibers are mixed and dispersed in a paper body made of a mixed material containing a base fiber and a friction modifier as essential components. The resin is impregnated with the bonded resin and heat cured.

Further, the wet friction material according to the invention of claim 3 is obtained by adding carbon powder or carbon fiber immediately before the completion of the papermaking of the mixed material containing the base fiber and the friction modifier as essential components. The papermaking body thus obtained is impregnated with a binding resin and cured by heating.

Here, as the base fiber, pulp, aramid fiber, organic fiber such as novoloid fiber, glass fiber,
Inorganic fibers such as rock wool, silicate fibers and alumina fibers, and metal fibers such as steel fibers and stainless steel fibers can be used.

As the friction modifier, molybdenum disulfide, antimony trisulfide, etc. can be used.

Examples of the binder resin include a phenol resin, an epoxy resin, a melamine resin, a polyimide resin, and a polyester resin.

The carbon powder or carbon fiber forming the carbon layer has high elasticity. The carbon powder is, for example, thermosetting resin such as phenol resin or petroleum / coal pitch is carbonized and fired at a high temperature in a non-oxidizing atmosphere, and the carbonized and fired body is finely pulverized to a predetermined particle size. Obtainable. The particle size is 0.1 to 50 μm, preferably 5 to 15 μm, and the carbon purity is preferably 90% or more. The firing temperature is 600 ° C to 2000 ° C, preferably 800 to 1400 ° C, which is the most hardened. 600 ° C
In the following, since the organic component remains, the powder hardness is low and the elastic modulus is also low, which is not preferable. On the other hand, 200
At 0 ° C. or higher, graphitization of carbon powder, that is, crystallization proceeds, so that both hardness and elastic modulus decrease, which is not preferable.
A Mohs hardness of 6 to 8 is desirable. Further, the carbon fiber can be synthesized from petroleum pitch, and the average fiber length is preferably about 0.1 mm.

For the wet friction material, in addition to the above compounding materials, organic compounding agents such as diatomaceous earth and rubber, iron oxide, silicon oxide,
Inorganic compounding agent such as magnesium oxide, aluminum powder,
Metal powder such as copper powder and brass powder is appropriately added.

[0015]

In the invention of claim 1, since the highly elastic carbon layer is formed on the sliding surface portion of the wet friction material body,
Due to the self-lubricating effect of carbon, smooth sliding is obtained between the mating material and the contact is uniform. Further, since the carbon layer is formed only on the sliding surface portion of the wet friction material, and the main body of the wet friction material can be formed of the same material as before,
The general performance equivalent to the conventional one can be secured without lowering the heat resistance and the peeling resistance.

Further, in the invention of claim 2, since the papermaking body is impregnated with the binding resin in which carbon powder or carbon fibers are mixed and dispersed, and is cured by heating, the sliding surface of the main body of the wet friction material can be easily treated. A carbon layer is formed on the part.

Further, in the invention of claim 3, carbon powder or carbon fiber is added immediately before the completion of the papermaking of the mixed material containing the base fiber and the friction modifier as essential components, and the papermaking body obtained thereby Since it is impregnated with the binder resin and is heat-cured, the carbon layer can be easily formed on the sliding surface portion of the wet friction material body as in the second aspect.

[0018]

【Example】

 <First Embodiment> First, a first embodiment of the present invention will be described.

The wet friction material as Example 1 in the first example was manufactured as follows.

First, a mixed material containing 50% by weight of pulp, 30% by weight of diatomaceous earth, 10% by weight of organic fiber and 10% by weight of a friction modifier was made into a paper to obtain a papermaking body. On the other hand, separately, a phenol resin cured product is carbonized and fired at 800 ° C. in a non-oxidizing atmosphere, and further, this carbonized and fired product is finely pulverized to an average particle size of 10 μm to prepare carbon powder, and a phenol resin varnish is obtained. 5% by weight of this finely pulverized carbon powder was mixed and dispersed. The specific gravity of the carbon powder was 1.4 to 1.6. Next, the papermaking body was immersed and impregnated in a phenol resin varnish in which the carbon powder was mixed and dispersed. Next, this was taken out, naturally dried, and then treated in a furnace at 200 ° C. for 10 minutes to heat and cure the phenol resin component. At this time, carbon powder was uniformly deposited on the surface portion of the main body of the wet friction material obtained by impregnating the paper body with the phenol resin and heating and curing. Next, this heat-cured body is molded by a hot press at 200 ° C., and further,
A wet friction material was obtained by machining.

Slip evaluation was carried out on the wet friction material produced in this manner.

The slip evaluation was performed by mounting a wet friction material as shown in FIG.

FIG. 1 is a schematic view showing a slip evaluation method for a wet friction material.

In the evaluation, the wet friction material 1 produced by the above method was adhered to both surfaces of the core metal 2 to obtain a test piece. Then, it was clamped by an iron plate 4 which is a mating member that is attached to the tester case 3 and does not rotate, and a pressure of 20 kg / cm ² is applied through a piston 5 so that the surface pressure is 20 kg / cm ² . Next, the test piece was rotated by the hub 6 at 10 rpm, which was assumed to be a differential rotation speed, and the amount of non-uniform slippage that occurred at this time was detected as the torque amplitude and used as the evaluation target. Note that these operations were performed while being immersed in ATF.

As a result, the torque amplitude was 2 kg · m.

For comparison, a wet friction material containing no carbon powder was prepared as Comparative Example 1, and Example 1 was used.
The slip evaluation was performed in the same manner as in. The wet friction material of Comparative Example 1 was made of the same material as in Example 1 except that carbon powder was not used, and was manufactured by the same manufacturing process.

The torque amplitude of Comparative Example 1 was 15 kg · m.

From this, it can be seen that the torque amplitude of Example 1 is remarkably smaller than that of Comparative Example 1, and therefore the non-uniform slip amount is small.

As described above, the wet friction material of the above-mentioned embodiment is
A highly elastic carbon powder obtained by carbonizing and firing a hardened phenolic resin is finely pulverized into a paper body made from a mixed material containing pulp and organic fibers as base fibers and a friction modifier as essential components. It is formed by impregnating a dispersed binder resin, phenol resin, and heating and curing.

Therefore, according to the above embodiment, since the highly elastic carbon layer is formed on the sliding surface portion of the wet friction material body, the self-lubricating effect of carbon causes a smooth sliding with the mating material. Is obtained, and the hits are made uniform. As a result, since the judder phenomenon is suppressed, it is possible to prevent vibration and squeal.

Here, it is possible to preliminarily mix a large amount of carbon powder into the papermaking material. Although the slip performance can be improved by this, a large amount of carbon powder is mixed in this way. With a wet friction material, not only the paper strength decreases, but also the performance as the original wet friction material may significantly change. On the other hand, since the wet friction material of the present example has the carbon layer formed only on the surface portion, the wet friction material body is formed of the same material as the conventional one, and the above-mentioned problems do not occur and heat resistance and peel resistance It is possible to secure general performance equivalent to the conventional one without deteriorating the properties.

Further, since the papermaking body is impregnated with the binder resin in which carbon powder is mixed and dispersed and is cured by heating, it is possible to easily form the carbon layer on the surface portion of the main body of the wet friction material.

The first embodiment corresponds to the aspect of claim 2 and also corresponds to the aspect of claim 1. <Second Embodiment> Next, a second embodiment of the present invention will be described.

The wet friction material as Example 2 in the second example was manufactured as follows.

A papermaking body similar to that used in Example 1 and a phenol resin varnish were used, and further synthesized from petroleum pitch,
Prepare carbon fiber cut to an average fiber length of 0.1 mm,
This carbon fiber was mixed and dispersed in the phenol resin varnish so as to have a concentration of 5% by weight, and then the phenol resin varnish was impregnated into the paper body in the same manner as in Example 1 and air-dried.
It was thermoset, thermoformed and machined to obtain a wet friction material. On the surface layer of the obtained wet friction material, short carbon fibers were firmly adhered to the surface with a phenol resin.

When slip evaluation was performed on this wet friction material, the torque amplitude was 3 kg · m.

Next, for comparison, a wet friction material of Comparative Example 2 was prepared by using glass fibers in place of the carbon fibers of Example 2, and slip evaluation was performed by the same method as in Example 1. The wet friction material of Comparative Example 2 was made of the same material as in Example 1 except that carbon powder was not used, and was manufactured by the same manufacturing process.

The torque amplitude of Comparative Example 1 was 9 kg · m.

From this, it can be said that the torque amplitude of Example 2 is remarkably smaller than that of Comparative Examples 1 and 2, and therefore the non-uniform slip amount is small.

The second embodiment corresponds to the aspect of claim 2 and also corresponds to the aspect of claim 1.

<Third Embodiment> A third embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a schematic view showing a papermaking apparatus used for producing the wet friction material of the third embodiment of the present invention.

The wet friction material as Example 3 in the third example was manufactured as follows.

First, a papermaking body was obtained from raw materials of 45% by weight of pulp, 25% by weight of diatomaceous earth, 10% by weight of organic fiber, 10% by weight of friction modifier and 10% by weight of carbon powder used in Example 1.

Papermaking of the papermaking body is carried out as shown in FIG. 2, and pulp, diatomaceous earth,
A slurry 12 composed of organic fibers and a friction modifier is fed into the papermaking tank 11. Further, the slurry 12 supplied into the papermaking tank 11 is stirred by the stirring means 31 rotated by the electric motor 31a, and a slurry layer suitable for papermaking is formed in the upper part of the papermaking tank 11. In the slurry 12 composed of pulp, diatomaceous earth, organic fiber and friction modifier having an appropriate concentration in the papermaking tank 11, the endless papermaking machine 15 moves obliquely upward through the papermaking roller 13 and the papermaking roller 14. While appearing on the liquid surface, the water in the slurry 12 is filtered as filtered water 16 to gradually form a filter residue 17 on the paper making net 15.

Immediately before the papermaking machine 15 was exposed from the liquid surface, the carbon powder 18 scattered from the hopper 35 was added. Further, the wet paper making body 19 having the carbon powder 18 adhered to the surface of the filter residue 17 is wound up by a winding roller 20, squeezed and dried by a squeezing means and a drying means (not shown) to complete a paper body having a certain thickness. Let

Drained water 1 obtained by filtering the slurry 12 at this time
6 is sucked into the slurry supply means 33 through the discharge pipe 32, and the thick slurry 12 prepared in the material tank 34 is mixed therein, and the slurry 12 having an appropriate concentration is fed from the feeding means 30 into the paper making tank 11 again. Is supplied to.

That is, in the production of the papermaking body, the timing of adding the carbon powder alone was delayed from that of the other raw materials just before the completion of the papermaking, so that the carbon powder was deposited on the surface layer of the papermaking body. After that, the papermaking body was impregnated with a phenolic resin, and air-dried, thermoset, thermoformed, and machined in the same manner as in Example 1 and Example 2 to obtain a wet friction material. Carbon powder was firmly deposited on the surface layer of the obtained wet friction material.

First, a papermaking body was obtained from raw materials of 45% by weight of pulp, 25% by weight of diatomaceous earth, 10% by weight of organic fiber, 10% by weight of friction modifier and 10% by weight of carbon powder used in Example 1. Papermaking of the papermaking body is performed as shown in FIG.
In the slurry 12 composed of pulp, diatomaceous earth, organic fibers, and friction modifier in the papermaking tank 11, an endless papermaking machine 15 moves diagonally upward through a papermaking roller 13 and a papermaking roller 14 so as to be on the liquid surface. While appearing in, the water in the slurry 12 was filtered as filtered water 16 to gradually form a filter residue 17 on the paper making net 15. Then, the carbon powder 18 was added from above immediately before the papermaking machine 15 was exposed from the liquid surface. Furthermore, 17
The wet papermaking product 19 having the carbon powder 18 adhered on its surface can be taken up by a take-up roller 20, and can be made into a wet friction material through a squeezing means, a drying means, and a predetermined molding which are not shown.

As described above, in the wet friction material of Example 3, the carbon powder was added immediately before the completion of the papermaking of the mixed material containing the pulp and organic fibers as the base fibers and the friction modifier as the essential components. The paper body obtained by the above is impregnated with a phenol resin which is a binding resin, and heat-cured.

Therefore, according to the above-mentioned embodiment, the carbon layer can be easily formed on the surface portion of the main body of the wet friction material, as in the second embodiment.

In the preparation of the wet friction material of Example 3, the carbon fiber used in Example 2 can be used instead of the carbon powder.

When slip evaluation was performed on this wet friction material, the torque amplitude was 3 kg · m.

Next, as Comparative Example 3, the papermaking raw material used in Example 3 was used for papermaking. However, the carbon powder in the papermaking was added not immediately before the completion of the papermaking but simultaneously with other raw materials, and the carbon powder was mixed so as to be uniformly dispersed in the entire papermaking body. Then, the paper body thus obtained was impregnated with a phenol resin as in Example 3, and air-dried, thermoset, thermoformed, and machined to prepare a wet friction material.

When the slip evaluation was performed on the produced wet friction material of Comparative Example 3, the torque amplitude was 8 kg · m. This is probably because although carbon having self-lubricating properties was mixed as a blending component of the wet friction material, the amount of carbon exposed on the surface portion, which is the sliding surface, was small and the effect was small.

From this, it can be seen that the torque amplitude of Example 3 is significantly smaller than that of Comparative Examples 1 to 3, and therefore the amount of non-uniform slip is small.

The third embodiment corresponds to the aspect of claim 3 and also corresponds to the aspect of claim 1.

By the way, the carbon powder or carbon fiber of each of the above-described examples is mixed with a phenol resin or added immediately before the completion of papermaking to form a carbon layer on the surface of the wet friction material. However, the present invention is not limited to this, for example,
The surface of the papermaking body or the main body of the wet friction material may be later coated with carbon powder or carbon fibers by a coating method such as coating or spraying. In short, any method may be used as long as the carbon layer can be formed on the surface of the wet friction material body.

[0059]

As described above, according to the wet friction material of the invention of claim 1, a highly elastic carbon layer is formed on the sliding surface portion of the main body of the wet friction material obtained by impregnating the paper-making body with the binder resin and heat-curing. Formed. Therefore, due to the self-lubricating effect of carbon, smooth sliding is obtained with the mating material and the contact is made uniform. As a result, the judder phenomenon can be suppressed and vibration and squeal can be prevented. Further, since the carbon layer is formed only on the surface portion of the wet friction material and the main body portion of the wet friction material is formed of the same material as the conventional one, it is possible to prevent deterioration of other general performance.

In the wet friction material of the second aspect of the present invention, carbon powder or carbon fibers are mixed and dispersed in a paper body made of a mixed material containing base fiber and friction modifier as essential components. It is formed by impregnating a binder resin and heating and curing. Therefore, simply impregnating the paper body with a binder resin in which carbon powder or carbon fibers are mixed and dispersed, and heating and curing,
The carbon layer can be easily formed on the surface of the wet friction material body.

Further, in the wet friction material of the invention of claim 3, carbon powder or carbon fiber is added immediately before the completion of the papermaking of the mixed material containing the base fiber and the friction modifier as essential components,
The papermaking body thus obtained is impregnated with a binder resin and cured by heating. Therefore, like the second aspect, the carbon layer can be easily formed on the surface portion of the main body of the wet friction material.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a slip evaluation method for a wet friction material.

FIG. 2 is a schematic view showing a papermaking apparatus used for manufacturing a wet friction material according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Wet friction material 12 Slurry 18 Carbon powder

Claims (3)

[Claims] 1. A wet friction material characterized in that a high elastic carbon layer is formed on a sliding surface portion of a wet friction material body which is obtained by impregnating a paper body with a binder resin and heat curing. 2. A paper body made of a mixed material containing a base fiber and a friction modifier as essential components is impregnated with a binder resin in which carbon powder or carbon fibers are mixed and dispersed, and heat-cured. A wet friction material characterized by the above. 3. Carbon powder or carbon fibers are added immediately before the completion of papermaking of a mixed material containing a base fiber and a friction modifier as essential components, and a papermaking body thus obtained is impregnated with a binder resin, A wet friction material characterized by being heat-cured.