JPH0625713Y2 - Differential limiting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a differential limiting device mounted on a vehicle. More specifically, the first friction plates and the second friction plates are alternately stacked and arranged. The present invention relates to a differential limiting device in which differential limiting of a differential device is performed by a so-called multi-plate clutch device.

[Conventional technology]

FIG. 1 shows a typical general structure of a differential limiting device. 1
Is a differential case and rotates integrally with a final reduction gear (not shown). A pinion shaft 4 is arranged in the differential case 1 in a direction perpendicular to a rotation axis of the case, and is integrally attached to the differential case 1. Pinion shaft 4
A pair of pinion gears 3 and 3'is rotatably supported on the shaft. Reference numerals 2 and 2 ′ are a pair of side gears that mesh with the pinion gears 3 and 3 ′, and are connected to left and right drive shafts (not shown) by inner splines 7, as is well known. A so-called multi-plate clutch device is arranged between the side wall of the differential case 1 and the back surfaces of the side gears 2 and 2. The multi-disc clutch device comprises a first friction plate 5a connected to the differential case 1 and a second friction plate 5b connected to the side gear 2,
Both friction plates 5a and 5b are arranged so as to be alternately stacked. When a differential more than a predetermined amount is generated between the left and right drive shafts due to the frictional force between the first friction plate 5a and the second friction plate 5b, the differential limiting action is performed as is well known.

In the differential limiting device of this type described above, cold-rolled steel plates were initially used for both the first friction plate and the second friction plate that compose the multi-plate clutch device. However, in both cases, the friction coefficient due to the steel plate is higher than the dynamic friction coefficient, the friction coefficient of the friction surface is large, and the fluctuation range (variation) of the friction coefficient is large, so stick-slip occurs and abnormal noise occurs. There was a problem. In general, stick-slip tends to occur as the friction coefficient increases, and tends to occur as the fluctuation range (variation) of the friction coefficient with respect to the change in the sliding speed of the friction surface increases.

As an attempt to solve the above problem, Shoukai 57-1
There is a conventional technique described in Japanese Patent No. 30039. This prior art is to solve the problem by reducing the friction coefficient. With this structure, the friction surface of the friction plate of the multi-plate clutch device is subjected to surface treatment with a coating material such as a self-lubricating material containing molybdenum disulfide particles or a material containing graded particles. It should be noted that a grid-shaped oil groove is formed on the friction surface of this prior art.

[Problems to be solved by the device]

In the above-described differential limiting device, due to the material characteristics of the coating material used for the friction surface of the friction plate, the friction coefficient of the sliding friction surface becomes small, so that stick-slip and abnormal noise are reduced. However, since the coefficient of friction (μ) is small, there has been a problem that the differential limiting force is insufficient under the usage conditions of the recent high torque engine.

Further, there is a problem that the conventional coating material has poor durability under high torque use. That is, since the conventional coating material is relatively soft, it causes early wear and early peeling under high torque. When premature wear or premature peeling occurs, sliding frictional contact occurs between steel sheets, and stick slip occurs again.

In the prior art, a grid-shaped oil groove is formed on the friction surface coated with a coating material, but this oil groove has an uneven arrangement in the friction sliding direction (rotational direction). The fluctuation range (variation) of the friction coefficient is relatively large. Therefore, there is a problem that stick-slip occurs again only by selecting a material having a necessary and sufficient friction coefficient and excellent durability as a coating material.

Therefore, the technical problem of the present invention is to select the material of the coating material having a necessary and sufficient friction coefficient and excellent durability and to arrange the material of the coating material uniformly in the friction sliding direction (rotational direction). This prevents or reduces the occurrence of stick-slip in the differential limiting device even at the time of high torque use, and at the same time reduces the variation of the friction coefficient and improves the durability.

[Means for Solving the Problems]

Therefore, the present invention takes the following means in order to solve the above problems.

That is, in the above-described differential limiting device, one of the friction surfaces of the first friction plate and the second friction plate that makes frictional contact has a carbon fiber reinforced structure in which the base material is carbon and the reinforcing material is carbon fiber. It is composed of a carbonaceous material composite material (hereinafter, simply referred to as C / C composite material), and its reinforcing carbon fibers are arranged in parallel with the friction sliding direction, and the other friction surface has hardness Hv400. As described above, it is formed of a steel plate having a surface roughness of 1.0 μRZ or less.

[Action]

According to the present invention, one of the friction surfaces has a relatively large friction coefficient C /
Since the C composite was selected and formed, the friction coefficient of the sliding friction surface at the time of the differential limitation becomes necessary and sufficient even when high torque is used. In addition, the C / C composite has high abrasion resistance due to its characteristics. As a result, the sliding friction surface of the friction plate maintains a stable friction coefficient state for a long period of time. Further, since the C / C composite matrix is graphitized carbon, the friction coefficient tends to increase with respect to the sliding speed, and the dynamic friction coefficient is higher than the static friction coefficient. Furthermore, since the carbon fibers that are the reinforcing material are arranged in concentric circles and arranged in a uniform friction surface state with respect to the friction sliding direction of rotation, the fluctuation range with respect to changes in the sliding speed of the friction surface is (Variation) is also small. The other friction surface is made of steel plate and has a hardness of Hv 400 or more and a surface roughness of 1.0 μRZ or less, which increases wear resistance and improves durability. Further, the bending strength becomes high and the contact with the mating material becomes uniform, and as a result, it is possible to suppress variations in the friction coefficient.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The overall structure of the differential limiting device is the same as that of the first embodiment described in the related art.
Since the configuration is as shown in the figure, its detailed description is omitted. FIG. 2 shows the first friction plate 5a. In this embodiment,
In this example, the friction surface of the friction plate 5a is subjected to C / C composite, and the friction surface of the second friction plate 5b is a steel plate.

The first friction plate 5a is manufactured by the following method. First, a woven fabric made of long carbon fibers having a diameter of 8 μm is arranged in the circumferential direction and laminated in a disc shape. After impregnating this with a phenol resin, it is cured to obtain a molded body. Next, this molded product is heated at 1000 ° C. for 24 hours and carbonized to obtain a C / C composite molded product. Next, the C / C composite is re-impregnated with resin and carbonized for 2 to
The density is increased to 2.0 g / cm ³ by repeating three times and performing a CVD process (chemical vapor deposition process). Then, it is further treated at 3000 ° C. for graphitization. After that, if desired, re-impregnation / carbonization or CVD treatment is performed to increase the density again, and then graphitization is performed again. The friction material (thickness: about 0.5 mm) thus obtained is pressure-bonded to both sides of a steel plate (thickness: about 1.0 mm) with a thermosetting resin (phenolic resin). As a result, the first friction plate 5a shown in FIG. 2 is obtained. In this production, the carbon fibers 6 which are the reinforcing material in the C / C composite are produced by arranging them concentrically.

In the structure of the first friction plate 5a manufactured as described above, the substrate is formed of a steel plate, and the friction surface is formed of a C / C composite in which the base material is carbon and the reinforcing material is carbon fiber. The carbon fibers as the reinforcing material are arranged in a concentric circle.

Next, a test example for clarifying the performance characteristics of the friction plate 5a of the present invention shown in FIG. 2 will be shown by using the friction plates A and B shown in FIGS. 3 and 4 as comparative examples. The friction plate A of Comparative Example (1) shown in FIG. 3 has a structure in which carbon fibers 6 are arranged in a grid on the sliding friction surface. The friction plate B of the comparative example (2) shown in FIG. 4 has a structure in which the carbon fibers 6 are nonuniformly arranged in dots on the sliding friction surface.

Test Example 1 The above three types of friction plates and a steel plate (material: JIS standard SK5M) that has been quenched and tempered (hardness: H
v480), and another friction plate (outer diameter φ70, thickness 1.8 mm) having a surface roughness of 0.5 μRZ was combined and tested by a thrust tester.

In the test, each friction plate to be compared was pressed with a load of 400 kgf to the friction plate rotating at about 5 rpm in the differential limiting differential oil (mineral oil), and the friction torque at that time was detected to obtain the friction coefficient. It was The result is shown in FIG. For comparison, the friction plate surface-treated with the coating material with self-lubricating oil described as the prior art is also shown. As is clear from FIG. 5, the friction plates using the C / C composites (the present invention and Comparative Examples 1 and 2) have significantly improved friction coefficients as compared with the prior art.
Among them, it can be seen that the tendency differs depending on the arrangement of the carbon fibers 6 as follows.

(I) In the case of the friction plate B of Comparative Example 2 in which the carbon fibers 6 are non-uniformly arranged in a dotted manner on the sliding friction surface, the area where the carbon fibers 6 contact (slide) with the mating member is small, The friction coefficient (μ) is lower than that of No. 1, and the fluctuation range (variation) is large because it is non-uniform in the friction sliding direction. or,
The surface pressure applied to the carbon fiber 6 is high, and the attacking property to the mating member is great.

(Ii) In the case of the friction plate A of Comparative Example 1 in which the carbon fibers 6 are arranged in a grid on the sliding friction surface, the carbon fibers have a larger area of contact with the counterpart member than the friction plate B of Comparative Example 2 described above. The coefficient of friction (μ) is high, but in this example as well, the arrangement of carbon fibers is non-uniform in the friction sliding direction.
Wide fluctuation range.

(Iii) On the other hand, in the case of the friction plate 5a of the present invention in which the carbon fibers 6 are concentrically arranged on the sliding friction surface, the carbon fibers 6 are arranged uniformly in the rotation direction of the friction plate, The fluctuation range (variation) of the friction coefficient (μ) is smaller than that of the friction plates A and B of Comparative Examples 1 and 2.

Test Example 2 In the same combination as in Test Example 1, to another friction plate rotating at about 50 rpm in the differential oil,
Press each friction plate to be compared with a load of 500 kgf 15
A 0 hour friction test was performed. The wear amount (wear depth) of the friction plate based on the test results is shown in FIG. It can be seen that the wear amount of the friction plate using the C / C composite is reduced to about 1/3 of that of the conventional friction plate. Particularly, it can be seen that the friction plate 5a of the present invention has a wear amount reduced to 1/3 or less as compared with the friction plate of the prior art, and has excellent wear resistance. In the case of a friction plate using a coating material with a self-lubricating oil of the prior art, the coating material is worn away and the base (steel plate substrate)
Has been exposed.

In Test Examples 1 and 2 described above, the counterpart friction plate was made of a steel plate and had a hardness of Hv480. In this case, wear of the counterpart friction plate made of a steel plate was hardly seen,
If a mating friction plate having a hardness of Hv 400 or less is used, the mating friction plate is likely to be slightly worn. Especially Hv
If it is less than 200, the wear is remarkable. In addition, since the bending strength of the friction plate on the other side decreases, the contact with the friction plate becomes non-uniform and the fluctuation range (variation) of the friction coefficient (μ) increases.
Therefore, the hardness of the steel plate of the friction plate on the other side is Hv400.
The above is preferable.

The surface roughness of the steel plate of the friction plate on the other side is 1.0
When it is more than μRZ, the friction coefficient (μ) becomes large, and the wear resistance also deteriorates. Therefore, it is preferable to make it as small as 1.0 μRZ or less as much as possible.

The present invention has been described above with reference to a specific embodiment, but the present invention is not limited to the above embodiment, and various embodiments are conceivable within the scope described in the scope of claims for utility model registration. Is.

For example, in the above embodiment, the friction surface of the first friction plate 5a connected to the differential case 1 is C / C.
Although it is made of composite, conversely, the friction surface of the second friction plate 5b connected to the side gear 2 may be made of C / C composite.

Further, the carbon fibers 6 in the C / C composite may be arranged concentrically, and the long fibers may be arranged concentrically as in the above embodiment, or the short fibers may be connected. Alternatively, they may be arranged concentrically.

In addition, since the friction plate in the embodiment of the present invention frictionally slides in the rotation direction, the carbon fibers in the C / C composite are arranged concentrically, but it is also applied to a friction member that slides linearly. In that case, the carbon fibers may be arranged linearly.

[Effect of device]

As described above, according to the present invention, one friction surface is composed of a C / C composite in which carbon fibers as a reinforcing material are oriented parallel to the sliding direction, and the other friction surface has a hardness of Hv400.
Since it is made of steel plate with a surface roughness of 1.0 μRZ or less,
A necessary and sufficient friction coefficient can be obtained even under high torque use, and a sufficient differential limiting action can be achieved even under such use. In addition, because of the characteristics of the material, which is excellent in wear resistance, there is an effect that the durability of the friction plate is improved. It should be noted that the larger the friction coefficient of the friction surface, the more likely it is that stick-slip will occur. Although the friction coefficient of the present invention is larger than that of the conventional technology, it is smaller than in the case of frictional contact between steel plates, and the friction coefficient fluctuation Combined with the small width (variation), the occurrence of stick-slip can be effectively prevented or reduced.

[Brief description of drawings]

FIG. 1 is an overall sectional view showing a typical differential limiting device to which the present invention is applied, FIG. 2 is a plan view showing an embodiment of a friction plate according to the present invention, and FIGS. 3 and 4 are FIG. 5 is a plan view showing friction of a comparative example, and FIGS. 5 and 6 are performance comparison diagrams showing results of a test example of the present invention. 1 ... Differential case 2 ... Side gear 3 ... Pinion gear 4 ... Pinion shaft 5a ... First friction plate 5b ... Second friction plate 6 ... Carbon fiber 7 ... Spline

Claims (1)

[Scope of utility model registration request] 1. A first friction plate and a second friction plate are arranged so as to be alternately superposed on each other, and the first friction plate and the second friction plate are rotatable relative to each other in a differential device. In the differential limiting device, which is integrally engaged with the member in the rotational direction and is configured to perform differential limiting by the frictional force between the first friction plate and the second friction plate, the first frictional contact device One of the two friction surfaces of the friction plate and the second friction plate is a carbon fiber reinforced carbonaceous material composite material in which the base material is carbon and the reinforcement material is carbon fiber and is a reinforcement material. Carbon fibers are arranged in parallel with the friction sliding direction, and the other friction surface has hardness Hv4.
A differential limiting device, which is formed of a steel plate having a surface roughness of 00 or more and a surface roughness of 1.0 μRZ or less.