JP2000063802A - Ring-like wet paper friction material having radially different compositions - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ring-like wet paper friction material which has radially different compositions so as to correspond to the value of frictional heat generated in the inner periphery and the outer periphery of the friction material. SOLUTION: A ring-like wet friction material 10 has three zones of an inner peripheral zone 10a, an intermediate peripheral zone 10b and an outer peripheral zone 10c each of which has a radially different composition and is fixed to a ring-like core metal to form a friction plate F. On engagement of the friction plate F with a separator plate, the value of the frictional heat generated on the outer peripheral side of the friction material 10 becomes larger than that of the friction heat generated on the inward peripheral side thereof, but as the composition of the friction material 10 is radially different, the difference in the rate of deterioration of the friction material 10 due to the difference in the value of the frictional heat generation can be compensated for.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a wet paper friction material used for automatic transmissions for vehicles, automatic transmissions for industrial construction machines, transmission clutches for motorcycles, lockup clutches and the like. Belong to.

[0002]

2. Description of the Related Art Conventionally, a paper friction material having paper as a base material has been used as a wet friction material. This paper friction material is prepared by dispersing pulp (cellulose fiber etc.) and various organic or inorganic fillers in water, and then adding a paper-making chemical to the paper-making raw material in a state of aggregating to a certain degree.
It is supplied to a paper machine (not shown) equipped with a filter such as wire netting, accumulated, pressed, dehydrated, and dried, and the sheet-shaped molded product is impregnated with a binding resin such as phenol resin and cured. It was made.

The wet friction material used for the clutch is obtained by punching the above-mentioned sheet-shaped paper friction material into a ring shape, and the friction plate constituting the clutch is made of a ring-shaped steel material. The core metal is adhered to both sides or one side.

Such paper-based paper friction materials are used as various wet friction materials because of their good friction characteristics and low cost, but they are large due to an increase in engine output. It is required to have excellent durability and a stable coefficient of friction even under load.

In a clutch using such a ring-shaped friction material, when the friction plate and a steel separator plate, which is a mating plate, are pressure-engaged by the piston when transmitting the engine output to the wheels, the friction plate Since the outer peripheral side is strongly pressed by the snap ring via the end plate, the contact pressure on the outer peripheral side of both plates is larger than that on the inner peripheral side. Therefore, the frictional heat generated on the outer peripheral side of the ring-shaped friction material is larger than that on the inner peripheral side, and the outer peripheral side deteriorates faster due to thermal decomposition. Therefore, there is a problem that the friction coefficient decreases as the number of engagements increases. For such problems,
Conventionally, JP-A-8-233304 and JP-A-9-33004 have been used.
Like the friction material described in Japanese Patent Application Laid-Open No. 210107/1990, the density and the porosity of the friction material are changed from the outer peripheral portion to the inner peripheral portion of the ring-shaped friction material to reduce the difference in deterioration progress between the inner peripheral side and the outer peripheral side. There are some that try to eliminate it and stabilize the friction coefficient.

However, since the above-mentioned friction material has a single composition containing cellulose fibers as a main component, when it is used under a high load condition in which friction heat exceeding the thermal decomposition temperature of the cellulose fibers is generated, As the number of engagements increases, the friction material as a whole deteriorates and the friction coefficient decreases.

Therefore, in order to prevent deterioration of the entire friction material due to thermal decomposition under high load conditions, there is a material in which aramid pulp having a high thermal decomposition temperature is blended into the entire friction material during papermaking.

[0008]

However, since aramid pulp is expensive, a material in which aramid pulp is mixed in the entire friction material has a problem of high material cost.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a ring-shaped wet paper friction material having a plurality of ring-shaped zones having different compositions in the radial direction, the ring-shaped zones being integrally formed. The above-mentioned problems were solved by a wet paper friction material.

[0010]

In the present invention, since the material composition of the ring-shaped friction material can be changed in the radial direction, the outer peripheral side, which generates higher frictional heat than the inner peripheral side, is relatively heat-resistant than the inner peripheral side. As a composition having excellent properties, the durability of the friction material can be improved as a whole.

[0011]

1 shows a ring-shaped wet paper friction material 10 of the present invention, and FIG. 1 (a) shows a friction plate F to which the ring-shaped paper friction material 10 is fixed.
1B is a perspective view of the ring-shaped paper friction member 10 fixed to the friction plate F of FIG. It is a perspective view. As shown in FIG. 1 (b), the ring-shaped paper friction material 10 of the present invention has an inner peripheral zone 10
a, a middle zone 10b, and an outer zone 10c.

Next, how to integrally manufacture the ring-shaped wet paper friction material 10 of the present invention will be described with reference to FIGS. 2 and 3. FIG. 2 is a side view of a ring paper machine 20 for manufacturing the paper friction material 10 of the present invention. The outline of the papermaking method by the ring paper machine 20 is the same as that of the conventional papermaking method. However, in the conventional papermaking machine, the friction material is formed into a long sheet shape. Formed into a shape. Therefore, it is not necessary to punch the sheet after papermaking into a ring shape unlike the conventional one.

The ring paper machine 20 has a cylindrical filtration tank 30 equipped with a filter 32 for filtering the papermaking raw material, and a plurality of stirring supply tanks 4 for supplying the papermaking raw material to the filtration tank 30.
0a, 40b, 40c. FIG. 3 is a vertical cross-sectional view of the filtration tank 30 in the ring paper machine 20 of FIG. A filter 32 such as a wire mesh is provided on the lower surface of the filtration tank 30, and a portion below the filter 32 is connected to the drain port 50. The inside of the filtration tank 30 is divided into three spaces 36a, 36b by concentric guide pipes 34a, 34b having different diameters.
Funnels 38a, 38b, 38c are attached to the upper portions of the spaces 36a, 36b, 36c. The guide pipes 34a and 34b partitioning each space are movable up and down, and a clearance C of about 5 to 7 mm is provided between the guide pipes 34a and 34b and the filter 32.
L is left.

Papermaking raw materials having different components are supplied into the respective agitation supply tanks 40a, 40b, 40c, and are constantly agitated by an agitator 42. Each stirring supply tank 40a, 40
b, 40c, and the spaces 3 in the filtration tank 30 corresponding to these
6a, 36b, 36c are connected by a tube 60, respectively, and funnels 38a, 3 provided on the upper part of the filtration tank 30.
8b, 38c through the respective stirring supply tanks 40a, 40b, 4
The papermaking raw material in 0c is the spaces 36a, 36 in the filtration tank 30.
b, 36c.

Guide pipes 34a, 34 in the filtration tank 30
clearance CL formed between b and the filter 32
If the value is too large, a flow of the papermaking materials between the zones parallel to the filter 32 occurs at the clearance CL, and the papermaking materials are mixed between the adjacent zones, and as a result, the ring-shaped friction material becomes radial. The composition will not be different. On the other hand, if the clearance CL is too small, the end surfaces of the guide pipes 34a and 34b will be the filter 3
Since it is close to the state of being in contact with 2, the deposited layer at the boundary portion of each circumferential zone becomes a thin layer, and as a result, cracks may occur in the ring-shaped friction material.

In the paper machine 20 of FIG. 2, the guide pipe 34
When a clearance CL of 5 to 7 mm is left between a, 34b and the filter 32, the papermaking raw materials having different components supplied to the spaces 36a, 36b, 36c in the filtration tank 30 have different circumferential bands. It was found that they were slightly mixed at the boundaries of and were deposited on the filter 32 in a continuous state with satisfactory results.

After the above-mentioned deposit is dried, the ring-shaped friction material is impregnated with a thermosetting resin in the same manner as in the conventional case, heated to cause a thermosetting reaction, and then pressure-molded to obtain the present invention. A ring-shaped friction material 10 was obtained. FIG. 4 is a front view of the above-described ring-shaped friction material 10 of the present invention.
a, a middle zone 10b, and an outer zone 10c, which are three zones different in the radial direction. To give an example of specific dimensions of the ring-shaped friction material of the present invention, the outermost diameter is 1
30mm, inner diameter is 111mm, inner diameter is 95
mm, and the diameter of the innermost circumference is 81 mm.

Table 1 shows five kinds of compositions as an example of the composition of the friction material, and Table 2 shows the compositions of the inner circumference, the middle circumference and the outer circumference.
The friction material selected from each composition shown in is shown below.

[Table 1]

[Table 2] From Table 2, the friction material of the present invention has a constant density throughout, but does not contain aramid pulp in the inner peripheral zone and gradually increases the content of aramid pulp from the middle peripheral zone to the outer peripheral zone. It turns out that it is a thing.

On the other hand, Comparative Example 1 has the same overall density and composition, while Comparative Example 2 has the same overall composition, but the inner peripheral side has a higher density than the outer peripheral side. As described above, it is manufactured using the ring paper machine 20 described above. In the case of Comparative Example 1, it is not necessary to provide the guide pipes 34a and 34b for separating the inside of the filtration tank 30 during papermaking. In addition, in Comparative Example 2, three spaces 36a separated by the guide pipes 34a and 34b in the filtration tank 30 are provided.
36b and 36c are supplied with papermaking raw materials having the same composition, but the amounts of papermaking raw materials supplied to the spaces 36a, 36b and 36c are different. That is, the inner space 36
A large amount is supplied to a.
The supply amount is gradually decreased over c so that the amount of the papermaking material deposited on the filter 32 is different depending on the zone, and the papermaking material is compressed to have the same thickness, dehydrated and dried to have the same composition as a whole. However, a friction material having a different density depending on the zone can be obtained.

FIG. 5 shows changes with time in the friction coefficient of each friction material in a durability test under a high load condition performed using a friction plate to which each friction material is fixed. In the figure, a is the friction material of the present invention, b is Comparative Example 1 in Table 2,
c shows the test result about the thing using the comparative example 2 of Table 2. The friction plate in this case was prepared by impregnating each friction material of Table 2 selected from each composition of Table 1 with a phenol resin so that the impregnation amount was 40%.
After the thermosetting reaction, the friction material has a thickness of 0.4 mm and is fixed to the core metal. It can be seen from FIG. 4 that the friction material of the present invention does not significantly change the friction coefficient even when the number of times of engagement increases, and is excellent in durability.

Of course, the friction material of the present invention may be constructed by combining compositions other than those shown in Table 1 above.

[0022]

As described above, the ring-shaped wet paper friction material of the present invention has an effect of having high durability even under a high load condition. In addition, since aramid pulp having a higher thermal decomposition temperature than that of cellulose pulp or the like can be blended only in the middle side to the outer side where high frictional heat is generated, the material cost can be reduced.

[Brief description of drawings]

1 shows a ring-shaped wet paper friction material of the present invention, FIG. 1 (a) is a perspective view of a friction plate to which the friction material is fixed, and FIG. 1 (b) is a friction material of FIG. 1 (a). FIG. 3 is an enlarged perspective view schematically showing a part of the device.

FIG. 2 is a side view of a ring-shaped paper machine for producing the ring-shaped wet paper friction material of the present invention.

FIG. 3 is a vertical cross-sectional view of a filtration tank in the ring-shaped paper machine shown in FIG.

FIG. 4 is a front view of the ring-shaped wet paper friction material of the present invention.

FIG. 5 is a result of a durability test of a clutch plate to which a friction material is fixed, under a high load condition.

[Explanation of symbols]

10: Ring-shaped paper friction material 10a: inner peripheral band 10b: Middle frequency band 10c: Outer band

Claims (3)

[Claims] 1. A ring-shaped wet paper friction material, comprising: a plurality of ring-shaped zones having different compositions in a radial direction, wherein the plurality of zones are integrally formed. Friction material. 2. The ring-shaped wet paper friction material according to claim 1, wherein there are at least two zones, and the outer zone contains more aramid pulp than the inner zone. 3. The ring-shaped wet paper friction material according to claim 2, wherein there are three zones.