JP2000283200A - Wet friction mating member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet friction material to acquire a high frictional coefficient by increasing torque capacity high and form a chemical adsorption film by a friction conditioner. SOLUTION: This wet friction mating material slides with a wet friction material with fiber as its base material in working liquid and has a metallic main body and a phosphate film previously formed on a sliding surface of the main body. It is possible to provide a high friction coefficient by the phosphate film even in the case of using an ATF blending a friction conditioner by previously applying the sufficient phosphate film on a surface of a metallic mating material. Additionally, a firm adsorption film is formed on the phosphate film as the friction conditioner is easily chemically adsorbed. Consequently, it is possible to maintain a favourable μ-v characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet friction mating material for an automobile wet clutch. 2. Description of the Related Art Generally, an automatic transmission of an automobile incorporates a wet friction clutch such as a lock-up clutch and a transmission clutch in combination with a torque converter. The present invention particularly relates to a wet friction mating member of a wet clutch.

[0002]

2. Description of the Related Art Generally, a torque converter used in combination with an automatic transmission of an automobile is filled with a hydraulic fluid for the automatic transmission, that is, an automatic transmission fluid (hereinafter, referred to as "ATF"). Wet friction clutches such as lock-up clutches and transmission clutches built into the torque converter
It is used and functions in a state of being immersed in. Generally, a wet friction clutch is composed of a friction material based on fiber and a metallic friction mating material based on iron.

[0003] These wet friction clutches are required to have a high torque capacity in order to cope with an increase in the output of the engine and to reduce the size and weight of the transmission. Therefore, a high friction coefficient is required for the wet friction clutch. Further, it is required to prevent shock and judder from occurring when shifting and engaging the clutch. for that reason,
The wet friction clutch is required to have a characteristic in which the friction coefficient (μ) between the friction material and the friction partner material decreases in a region where the relative slip velocity (v) is low, that is, a positive gradient of the μ-v characteristic. .

In other words, a wet friction clutch is required to have a high friction coefficient from the viewpoint of increasing the torque capacity, and is required to have a good μ-v characteristic from the viewpoint of preventing judder or the like.
Here, the good μ-v characteristic means that the μ-v characteristic has a positive gradient. As a technique for realizing a high torque capacity, Japanese Patent Application Laid-Open Nos. 4-181022 and 4-36629 disclose a technique of performing a surface treatment on a friction mating member of a wet friction clutch. I have. The former is obtained by applying nickel phosphorus plating to the surface of a friction mating material, and the latter is obtained by applying a ceramic thin film to the surface of a metal-based friction mating material. These techniques attempt to obtain a high friction coefficient by surface-treating a friction mating member of a wet clutch.

On the other hand, as a technique for preventing the occurrence of judder or the like, there is a technique in which a friction modifier is added to ATF. For example, JP-A-63-66299 discloses a lubricating oil composition containing a friction modifier such as a reaction product of an unsaturated fatty acid and a dialkanol. This is a technology relating to ATF, in which a friction modifier is added to ATF to reduce the coefficient of friction mainly in a region where the sliding speed is low, and to obtain an action of making the μ-v characteristic a positive gradient. It is.

[0006]

Generally, the action and effect of additives such as a friction modifier incorporated in an ATF vary greatly depending on the material and composition of a friction material and a friction mating material. An ordinary ATF contains an additive assuming a combination of an iron-based metal friction partner and a paper-based friction material.

[0007] As friction modifiers to be compounded in ATF,
Examples include fatty acids, fatty acid esters, fatty acid amides, metal salts of fatty acids, amines, borate esters, phosphate esters, phosphite esters, metal sulfonates, metal phenates, metal salicylates, succinimides, benzylamines, and the like. These friction modifiers form a chemically adsorbed film on the surfaces of the friction material and the friction partner material, and the μ-v characteristics are made to have a positive gradient by the chemically adsorbed film. As a result, it is possible to prevent a shock at the time of shifting / engaging the clutch and the occurrence of judder.

On the other hand, the ATF has the wear resistance of a normal gear.
From the viewpoint of seizure resistance and the like, a phosphorus-based additive such as a phosphate ester, a phosphite ester, and zinc dithiophosphate is blended as an essential component. When the wet clutch is slid in the ATF containing the phosphorus-based additive, the phosphorus-based additive chemically reacts with the iron-based friction mating member, and the chemical reaction causes the sliding of the friction mating member. A phosphate film is formed on the moving surface. This phosphate film has a function of maintaining a high friction coefficient in a wet friction clutch. As a result, a high torque capacity is realized.

However, for the purpose of preventing the occurrence of shock and judder at the time of shifting and engagement, a friction modifier having a strong chemical adsorption property is blended into the ATF, or the friction modifier is blended at a high concentration. In such a case, the friction adjusting agent forms a chemically adsorbed film on the surfaces of the friction material and the friction partner material. And due to the presence of the chemisorption film,
The chemical reaction of the phosphorus-based additive compounded in the ATF is inhibited, and the amount of the phosphate film formed on the surface of the friction mating member is reduced. As a result, even if good μ-v characteristics can be obtained by the friction modifier, there is a problem that the friction coefficient is reduced.

On the other hand, for the purpose of increasing the torque capacity, the sliding surface of the metal friction mating member is subjected to a surface treatment in advance,
A high coefficient of friction can be obtained. However, when a film that does not chemically adsorb with the friction modifier, such as nickel-phosphorus plating and a ceramic thin film, is applied to the surface of the friction partner, the friction modifier does not chemically adsorb, so that a chemically adsorbed film is not formed. Will be. So in this case,
Although a high friction coefficient can be obtained, a problem arises in that the effect of making the μ-v characteristic of the friction modifier positive gradient cannot be obtained.

[0011] These problems are caused by the fact that the surface treatment applied to the metal friction mating member obtains a high friction coefficient,
It is a problem that can be solved if the surface treatment enables the formation of a chemically adsorbed film by the friction compounding agent contained in the ATF. Accordingly, an object of the present invention is to obtain a high friction coefficient by performing a surface treatment on a metal friction mating member in advance, and at the same time, to enable formation of a chemically adsorbed film by a friction modifier, thereby obtaining a good μ-v characteristic. To get

[0012]

SUMMARY OF THE INVENTION A wet friction mating material of the present invention is a friction mating material that slides in a working fluid with a wet friction material having a fiber as a base material. And a phosphate film formed on the sliding surface in advance. That is, by applying a sufficient phosphate film on the surface of the metal counterpart material in advance, a high friction coefficient due to the phosphate film can be obtained even when an ATF containing a friction modifier is used.

Further, the friction modifier is easily chemically adsorbed on the phosphate film, and a strong adsorption film is formed. As a result, good μ-v characteristics can be maintained. The phosphate film is preferably at least one of an iron phosphate film, a zinc phosphate film and a calcium phosphate film.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The wet friction mating material of the present invention constitutes a wet friction clutch by being combined with a wet friction material. This wet-type friction clutch is used as a lock-up clutch, a speed change clutch, and the like provided in a torque converter when immersed in an ATF.

The wet friction mating member of the present invention comprises a metal main body and a phosphate film previously applied to the surface of the metal main body. Thereby, the friction coefficient is increased, and a high torque capacity is realized. The metal body is preferably an iron-based metal. A conventionally used hot-rolled steel sheet can be used. As the phosphate, metal phosphates such as iron phosphate, zinc phosphate, calcium phosphate, and magnesium phosphate are preferable.

The wet friction material may be any material as long as it is made of a fibrous base material, and a conventionally used material can be used as it is. A where wet friction clutch operates
As the TF, those containing a friction modifier are preferable. This is because the friction modifier adsorbs to the wet friction mating material and forms a chemically adsorbed film, whereby good μ-v characteristics can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for producing a friction partner having a phosphate film according to the present invention is as follows. Three types of treatment solutions for forming a phosphate film were prepared: an iron phosphate treatment solution, a zinc phosphate treatment solution, and a calcium phosphate treatment solution. Table 1 shows the compositions of these three types of processing solutions.

An SPHC (hot-rolled steel plate) material was used as a surface-treated material. First, the surface of the main body was polished and then washed with a detergent. Thereafter, the body was washed with acetone, and the washed body was immersed in a 0.2 mol / L aqueous solution of sodium hydroxide heated to 80 ° C. for 10 minutes, and then the metal body was washed with water. Next, 15mo heated to 45 ° C
It was immersed in a 1 / L sulfuric acid aqueous solution for 5 minutes, and then washed with water.

Next, the treatment liquid (see Table 1) diluted 1/20 was heated to 90 ° C., and the main body was immersed for 15 minutes to form a phosphate film on the surface. After that, it was washed with water. After washing with acetone, it was put in a dryer at 50 ° C. for 10 minutes and dried to prepare a friction partner material having a phosphate film of the present invention.

[0020]

[Table 1]

[0021]

[Test] (Test method) The friction characteristics of a friction partner material were measured in ATF using a thrust color type friction tester shown in FIG. The outline of the test is shown in FIG.
Table 2 shows test conditions such as slip speed, test time, friction surface temperature, and surface pressure.

The sliding speed is 0.2 m / s, 0.4 m / s
s, 0.6 m / s, 0.8 m / s, 1.0 m / s, 1.
2 m / s, 1.4 m / s, 1.6 m / s, 1.8 m / s
s and 2.0 m / s were changed step by step, and the measurement was performed. As the friction coefficient, a value 30 seconds after the load was applied was measured under each sliding speed condition. The measurement result is 3
After a 0 minute break-in, the evaluation was performed.

A paper friction material is adhered to the ring specimen. The friction area is 200 mm ² and the outer diameter is φ25.
6 mm, and the inner diameter is 20.0 mm. An SPHC (hot-rolled steel plate) material was used as a plate specimen as a friction partner material. The surface roughness of SPHC material is 0.04-0.06μ
mRa. As the phosphate film treatment, those subjected to the iron phosphate film treatment, the zinc phosphate film treatment, and the calcium phosphate film treatment shown in the examples were used.

For comparison, a sample not subjected to a phosphate film treatment was used. ATF includes commercially available DEXRO
A blend of N-II (standard oil) and 0.2% by mass of hydroxypalmitic acid as a friction modifier was used. As an antiwear agent, a phosphorus-based extreme pressure agent, a viscosity index improver, a dispersant (succinimide), an antioxidant and the like are also blended. Hydroxypalmitic acid used as a friction modifier is that of a reagent. The structure has both a -OH group and a -COOH group at the terminal of a long-chain alkyl group. These two functional groups increase the adsorptivity to the iron surface. From this feature, the solid friction reduction effect is large, and effectively acts on the positive gradient of the dependency (μ-v characteristic) of the friction coefficient on the slip speed in the wet clutch. 150 ml of ATF was used.

At the time of the test, a thermocouple was attached to a portion of the outermost periphery of the friction surface of 1 mm, and the plate specimen SPHC was used.
The surface temperature of the material was measured. Regarding the test temperature, the temperature of the ATF, which is a sample oil, was adjusted between 80 and 125 ° C. so that the surface temperature at this site was constant at 120 ° C.

[0026]

[Table 2]

(Evaluation) From the results of the test, it was confirmed that a higher coefficient of friction was realized when the phosphate coating was applied beforehand than when no phosphate coating was applied.
At this time, good μ-v characteristics are also maintained.

[0028]

According to the present invention, the surface of a metal friction mating member is subjected to a phosphate film treatment which chemically adsorbs a friction modifier to thereby maintain the μ-v characteristic and the judder resistance. The phosphate film treatment has an effect of obtaining a high friction coefficient and realizing a high torque capacity.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a thrust color test.

FIG. 2 is a graph showing a relationship between a sliding speed and a friction coefficient as a result of a test.

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Claims (2)

[Claims] 1. A wet friction mating material which slides in a working fluid with a wet friction material having a fiber as a base material, comprising a metal main body and a phosphate film formed on a sliding surface of the main body in advance. And a wet-type friction mating material comprising: 2. The phosphate coating according to claim 1, wherein said phosphate coating comprises at least one of an iron phosphate coating, a zinc phosphate coating and a calcium phosphate coating.
The wet friction mating material according to claim 1, which is a seed.