JPH01307549A - Transmission gear - Google Patents

Abstract

PURPOSE:To keep sufficient lubricity between a shift fork rod and a housing case by coating the sliding face of at least one of the sliding portions of the shift fork rod and housing case with a fluorine containing polymer. CONSTITUTION:The sliding face of at least one of the sliding portions of a shift fork rod and a housing case is coated with a fluorine containing polymer. The fluorine containing polymer may be a fluoro-alkyl polymer with a low molecular weight of carbon number 2-20, a fluoro-polyether polymer of a low molecular weight with the formula I as the main structure unit, or a fluorocarbon resin (poly-tetrafluoroethylene-tetrafluoroetylene-hexafluoroprop- ylene copolymer, etc.) etc. Thereby, stable and excellent lubricity and wear resistance can be effected on the sliding faces between the shift fork rod and a housing, enabling light gear change while giving good feeling even to a woman driver, etc.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an automobile transmission.

[Conventional Technology] Various manual or automatic transmission devices are widely used in automobiles. It is desirable that gear changes in these transmissions be performed smoothly with light operations. To achieve this, we needed a 5CRu soft fork rod and ADC (aluminum die-cast) transmission system! A The sliding characteristics of the sliding part with the housing case are greatly affected.

Conventionally, transmission oil has been used as a lubricant for these sliding parts, but transmission oil is highly temperature dependent, and its viscosity increases at low temperatures, making operation difficult and difficult. Because of the reciprocating motion, oil circulation is poor and metal-to-metal contact is likely to occur, increasing the coefficient of friction and causing wear on the inner sliding surface of the housing case. In such a case, the operation is very heavy and abnormal noises are generated, making it difficult to operate stably with a light load.

In recent years, there has been a significant increase in the number of female drivers, and the need for a transmission device with a light load and good feel (gear changing) has increased.For this reason, a method of press-fitting a cylindrical bearing made of resin or the like into a housing case has been adopted. However, during use, the temperature rises due to heat transfer from the engine, and the resin expands, reducing the clearance of the sliding part and increasing the coefficient of friction.Also, metal bushings made of copper alloy, etc., tend to increase. Methods have been considered, but as mentioned above, there are variations in the coefficient of friction, and no fundamental solution has been reached. If the bushing is used in the ADC housing case for a long period of time, the housing case may creep due to repeated temperature rises and falls within the transmission, which is undesirable since there is a risk that the bushing may come off.

[Problem to be solved by the invention]

As mentioned above, the problem with conventional technology is that it is not possible to maintain sufficient lubricity in the shift fork rod and housing case, making it impossible to obtain a transmission that can be operated easily and with a constant force. There were some issues, and the challenge was to resolve them.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a transmission in which at least one sliding surface of the sliding portion between the shift fork rod and the housing case is coated with a fluorine-containing polymer. They adopted a means to make it into a device. The details will be described below.

First, the fluorine-containing polymer in this invention is defined as having 2 carbon atoms.
~20 low molecular weight fluoroalkyl polymers, or low molecular weight fluoropolyether polymers having the general formula CM Polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, etc.), etc.Fluoroalkyl polymers are
For example, CF3 (CF2)? =, H(CF2)6-1C
Fz C1(CFz)++-1CFz C18CFs, . F3. -CF (CFz)7-1 7CF (CFz
), -1Fff having a polyfluoroalkyl group (2 to 20 carbon atoms), and a functional group that has a high affinity for the base material surface of the shift fork rod or housing case, such as an isocyanate group, a hydroxyl group, and a mercapto group. , carboxyl group,
Polymers having units containing epoxy groups, amino groups, sulfone groups, etc. are preferred. Specific examples include the following. That is, Ch F+3Ct H-0CNH(CHz)a NC
01C6F13COOH.

δ Cm F+tCz H45H, C6F++5GHz C
Hz QC(CHI)S NH2, These fluoroalkyl polymers may be used alone or in combination, and a fluoroalkyl polymer containing a reactive group having activated hydrogen and a fluoroalkyl polymer containing a polyfluoroalkyl group may be used. It may be used in combination with an isocyanate compound that is not used. Also,
a fluoroalkyl polymer having an isocyanate group;
Methods such as the combined use of diamines and triamines that do not contain various polyfluoroalkyl groups, or diols and triols that do not contain various polyfluoroalkyl groups may be adopted.

A combination of functional groups is preferred from the viewpoint of increasing strength, and specifically, a combination of functional groups having a polyfluoroalkyl group having 2 to 20 carbon atoms and at least one type selected from a hydroxyl group, a mercapto group, a carboxyl group, and an amino group. or a combination of a fluorine-containing polymer having a C2-C20 polyfluoroalkyl group and a unit containing an isocyanate group and a C2-C20 polyfluoroalkyl group. and a combination with a fluorine-containing polymer having a unit containing a reactive group having activated hydrogen.

Furthermore, the average molecular weight of the fluoropolyether polymer is approximately 1.
000-5oooo polymer, CF, OiC,
F2O−)−+cF! O+-CF3 can be exemplified. As for such polymers, in order to improve the affinity for the base material surface of the shift fork rod or housing case as described above, it is desirable to have units containing functional groups such as isocyanate groups, hydroxyl groups, carboxyl groups, and esters. . Therefore, specific examples of such fluoropolyether polymers include OCN
Cb H3(CHs) NHCOCFz + C
2F40-)-1CFx O'jx CF2 C0NH
(CH3) Cb Hs NCOHOOC-CFz
o-<c,F,0)-(-CFIC)+rCh C0O
H.

H: +C00CCFgOiC2F40-)-ii+C
F2O line CF2 C0OH.

HOCH2CF20(Cz F2O−+−fCFz O
Examples include CFz CHt OH1, and these may be used alone or in combination. Furthermore, even if a fluoropolyether polymer containing activated hydrogen in a functional group is used in combination with an isocyanate compound that does not contain a polyfluoropolyether group, a fluoropolyether polymer having an isocyanate group and A method may be adopted in which various diamines and triamines that do not contain fluoropolyether groups or diols and triols that do not contain various fluoropolyether groups are used in combination. In particular, it is preferable to use a combination of fluoropolyether polymers whose functional groups react with each other to increase the molecular weight. For example, one having a unit containing an isocyanate group and one having a unit containing a hydroxyl group are preferably used. Combinations are desirable as in the case of the fluoroalkyl polymers described above.

In order to coat the sliding surface of the shift fork rod or housing case with the above fluorine-containing polymer, it is necessary to coat the raw material polymer directly when it is a low viscosity liquid, or coat it directly with a high viscosity liquid.
When it is semi-solid or solid, for example, ketones such as acetone and methyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as xylenes and toluene, methyl chloroform, trichloroethylene, trichlorotrifluoroethane, etc. It may be applied after being diluted or dispersed in an organic solvent such as an organic halide. Possible coating methods for shift fork rods include day coat, souffle coat, and dip bottle coat, but dip coat is preferable from the standpoint of quality control and economy, and the same method can be used for housing cases as well. However, a spray coating method is preferable for coating the inner diameter surface.

On the other hand, fluorocarbon resins such as polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymers, etc. do not have adhesion or reactivity by themselves, so resins with good adhesion such as epoxy resins and polyamides It is preferable to use a coating liquid in which a binder resin such as a resin, polyamideimide resin, or phenol resin is dispersed in an organic solvent to form an enamel.

In addition, in order to improve wear resistance, molybdenum disulfide, cadmium selenide, cadmium sulfide pigments, etc. may be added as fillers, and the combination of molybdenum disulfide was particularly effective. In addition, it is of course possible to use a binder resin as a brimer, but the coating method in this case may be the same as in the case of the low molecular weight fluoroalkyl polymer and fluoropolyether polymer described above.

〔Example〕

Example 1: A mixed enamel-like coating liquid of polyamide-imide and polytetrafluoroethylene resin (PTFE) was applied to the shift fork rod of a transmission (Nil-Lon R manufactured by Yobea Rulon Kogyo Co., Ltd.).
600) by spray method and heated to approximately 230°C130
A test rod was prepared by firing for a minute. Attach the obtained rod to the transmission and connect the air cylinder to 4kgf/cif.
i, stroke 25 strokes, speed 40 m/s, load 20 kg
The friction coefficient at f is the lubricating oil (transmission oil)
The temperature was changed to four stages: 0'C, 25°C, 50°C, and 80"C, and the measurements were made under conditions close to practical conditions. Furthermore, continuous operation was performed for about 250 hours at 80°C, and the temperature was changed every 50 hours. We measured the friction coefficient of
It was evaluated in two stages (marked). The results obtained are summarized in the table.

Example 2: Exactly the same as Example 1 except that the inner sliding surface of the housing case was coated with a mixed enamel coating liquid of polyamideimide and tetrafluoroethylene resin (PTFE), but the shift fork rod was not coated. The friction coefficient and its stability were determined by the method.

The obtained results are also listed in the table.

Example 3: 10 molybdenum disulfide powder was added to the coating material in Example 1.
The coefficient of friction and its stability were determined in exactly the same manner as in Example 1, except that the sliding portion of the shift fork rod was coated with a 15 μm thick coating containing 2% by weight. The obtained results are also listed in the table.

Comparative Example 1: The coefficient of friction and its stability in lubricating oil (transmission oil) were determined in exactly the same manner as in Example 1, except that neither the shift fork rod nor the inner diameter sliding surface of the housing case was coated with resin. The results are also listed in the table.

Comparative Example 2: A method similar to Example 1 was carried out by press-fitting a fluorine-containing resin molded product onto the inner diameter surface of a cylindrical steel plate onto the inner diameter sliding surface of the housing case without applying a resin coating to the shift fork rod. The friction coefficient and its stability were determined using the method, and the obtained results are also listed in the table.

From the above measurement results, it can be seen that in Comparative Example 1, in which neither the shift fork rod nor the inner diameter sliding surface of the housing case was coated with a fluorine-containing polymer coating, the friction coefficient was affected by transmission oil, but the friction coefficient was dependent on temperature. It was extremely unstable, and in continuous tests, the friction coefficient tended to increase over time. In addition, in Comparative Example 2, in which a fluorine-containing polymer molded bund was press-fitted into the inner diameter sliding surface of the housing case, the friction coefficient tended to increase due to the influence of temperature and was unstable. The operation was relatively stable. In contrast to such comparative examples, Examples 1 to 3 exhibited stable friction coefficients without being affected by temperature, and were also very stable even in long-term continuous tests.

[Effects] As described above, the transmission of the present invention exhibits long-term stability on the sliding surface between the shift fork rod and the housing, exhibits excellent lubricity and friction and wear resistance, and enables light gear changes. It can also give a good feeling to female drivers. Therefore, it can be said that the significance of this invention is extremely large.

Patent applicant: Fuji Heavy Industries Co., Ltd.

Claims (1)

[Claims] (1) A transmission for an automobile, characterized in that at least one sliding surface of a sliding portion between a shift fork rod and a housing case is coated with a fluorine-containing polymer.