JPH0616141A - Pipeline connecting structure for power steering device - Google Patents

Abstract

PURPOSE:To provide a pipeline connecting structure for a power steering device by which corrosion is not caused in a pipe and a nut when they are used. CONSTITUTION:An iron nut 2 is connected to an aluminium pipe 1 for a motive power steering device, and a zinc powder chromic acid formation coating film or a fluorocarbon resin coating film is arranged on a surface where the iron nut 2 is contacted at least with the aluminium pipe 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure for piping for a power steering device used in an automobile or the like.

[0002]

2. Description of the Related Art In recent years, various components such as bumpers have been reduced in weight in order to reduce costs and improve fuel efficiency by reducing the weight of automobiles. As part of that,
The weight reduction of the piping parts of the conventional power rudder mounting device has been studied, and aluminum has attracted attention as a material that can replace iron in the iron pipe for the power rudder mounting device.

However, the material of the pipe can be changed from conventional iron to aluminum in order to reduce the weight, but since the nut mounted on the pipe is required to have a large mechanical strength, the nut can be made as usual. It is necessary to use iron-based metal as the material. Under these circumstances, when a combination of an aluminum pipe and an iron nut is used, for example, when muddy water adheres, an electrode reaction occurs between the pipe and the nut, and the pipe corrodes, It had the drawback of not being able to withstand actual use.

[0004]

Therefore, in view of the above-mentioned prior art, the present inventors have developed a connection structure for a power steering system pipe in which corrosion does not occur in an aluminum pipe and an iron nut during use. As a result of earnest research,
The inventors finally found such a connection structure and completed the present invention.

[0005]

That is, according to the present invention, an iron pipe is connected to an aluminum pipe for a power steering apparatus, and zinc dust chrome is provided on at least a surface of the iron nut that is in contact with the aluminum pipe. The present invention relates to a connection structure for a power steering apparatus pipe, which is provided with an oxide film or a fluororesin film.

[0006]

OPERATION AND EXAMPLES As described above, the connection structure of the pipe for power steering device of the present invention is an iron nut having a zinc dust chromium oxide conversion film or a fluororesin film formed on at least the surface in contact with the aluminum pipe. Is connected to the aluminum pipe.

FIG. 1 is a perspective view of an embodiment of the connection structure of the present invention. In FIG. 1, an aluminum pipe 1
Are inserted in the iron nut 2. The aluminum pipe 1 is connected to a steering gear box (not shown), and the screw portion of the steering gear box and the screw portion 3 of the iron nut 2 are screwed together, so that the aluminum pipe 1 and the steering gear box are integrated. Be converted.

As shown in FIG. 2, the aluminum pipe 1 is provided with a hole 4 for feeding oil, and the hole 4 is electrically connected to the control valve of the steering gear box through the nipple portion 5. Is configured.

Further, as shown in FIG. 3, the iron nut 2 is provided with a hole 6 so that the aluminum pipe 1 communicates with the inside thereof.

In the above connection structure, the nut 2 is made of iron so that it can sufficiently withstand the mechanical strength required for screwing the gear box. However, if the iron nut 2 is used as it is, an electrode reaction may occur between the iron nut 2 and the aluminum pipe 1. Therefore, zinc powder may be attached to the contact surface of the iron nut 2 with the aluminum pipe 1. A chromium oxide conversion film or a fluororesin film is provided.

In the present invention, when the iron nut 2 is screwed into the gearbox, it appears outside without being mounted in the gearbox. For example, the hexagonal portion 7 is also provided with the film. It is preferable to provide corrosion resistance.

The zinc dust chromium oxide conversion film is applied, for example, by applying a suspension obtained by suspending zinc fine particles having a particle size of 30 μm or less in an aqueous solution of chromic acid of about 5.5 wt%.
It is a film formed by heating to about 300 ° C. and baking, and the structure of such a film is considered to be a state in which zinc particles are dispersed in chromium oxide. Incidentally, it is desirable that the coating contains zinc fine particles in an amount of about 85% by weight. The thickness of the zinc dust chromium oxide conversion coating is preferably about 5 to 6 μm so as to be uniformly provided on the zinc plating coating.

The fluororesin film is, for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoride. Propylene copolymer,
Tetrafluoroethylene-ethylene copolymer, polychlorotrifluoroethylene, a fluororesin such as polyvinylidene fluoride alone, further smoothness, in order to improve the adhesiveness, for example, polyamide, polyamideimide, epoxyphenol resin, After mixing alkyd resin, acrylic resin, etc. and making each dispersion or solution into a thickness of about 5 to 25 μm, heat it to about 200 to 250 ℃,
It is a film formed by baking. The fluororesin may be blended with a heat-resistant inorganic fine powder such as molybdenum disulfide within a range of about 1 to 20% by weight.

As the pipe used in the connection structure, as described above, an aluminum pipe is used in order to reduce the weight.

As described above, the connection structure in which the iron pipe having the zinc dust chromium oxide conversion film or the fluororesin film provided on at least the surface in contact with the aluminum pipe and the aluminum pipe are connected is Since the film provided on the surface electrically insulates between the aluminum pipe and the iron nut,
For example, even when a conductive liquid such as salt water is attached, corrosion does not occur between the two.

Next, the connection structure of the power steering system piping of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Production Example 1 Fluorine resin is applied to the portion other than the screw portion 3 of the iron nut 2 shown in FIG. 3 to form a coating film having a thickness of about 20 μm, and then at 200 ° C. for 30 minutes. After baking, an iron nut A having a fluororesin film was obtained.

Production Example 2 The iron nut 2 shown in FIG.
(3 μm or less) is immersed in a suspension of an aqueous solution of about 5.5% chromic acid containing about 30% by weight, and then baked at 320 ° C for 10 minutes,
Then, the operation of cooling is defined as one cycle, and this cycle is repeated twice so that the thickness of the zinc dust chromium oxide conversion film is about 6 μm.
An iron nut B having a zinc powder chromium oxide conversion film of m was obtained.

Production Example 3 Iron nut 2 shown in FIG. 3 was washed with acetone to obtain iron nut C whose surface was cleaned.

Production Example 4 The iron nut 2 shown in FIG. 3 was obtained by an electrogalvanizing method to obtain an iron nut D having a zinc plating film with a zinc plating film thickness of about 10 μm.

Example A sample was prepared by inserting the aluminum pipe 1 shown in FIG. 2 into the iron nuts A to D obtained in Production Examples 1 to 4.

Next, the corrosion resistance of the obtained sample was examined according to the following method. The results are shown in Table 1.

(Corrosion resistance) Salt spray 4 hours, dry (60 ° C)
Two hours and two hours of wetting (50 ° C, 95% RH or more) were repeated as one cycle, and after 300 cycles, the corrosion state was visually observed and evaluated according to the following evaluation criteria.

(Evaluation Criteria) A: No occurrence of corrosion is observed. B: Very little corrosion is observed, but it is judged that there is no problem in practical use. C: Corrosion is slightly recognized, which may cause a problem in practical use. D: Corrosion is slightly noticeable. E: Corrosion is clearly recognized and conspicuous.

[0025]

[Table 1]

From the results shown in Table 1, it can be seen that the connection structures of the surface-treated iron nuts and aluminum pipes obtained in Production Examples 1 and 2 all have excellent corrosion resistance. Recognize.

[0027]

INDUSTRIAL APPLICABILITY The connection structure for a power steering system pipe of the present invention is lighter than iron as a pipe, but is excellent in corrosion resistance despite being made of aluminum which is inferior in corrosion resistance. Therefore, it can be suitably used, for example, in a connecting portion of a gear box of an automobile.

[Brief description of drawings]

FIG. 1 is a perspective view of a connection structure of the present invention.

FIG. 2 is a perspective view of an aluminum pipe used in the connection structure of the present invention.

FIG. 3 is a perspective view of an iron nut used in the connection structure of the present invention.

[Explanation of symbols]

 1 Aluminum pipe 2 Iron nut

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Onishi 1118 Sado, Bessho-cho, Himeji-shi, Hyogo Prefecture Nichirin Himeji Plant

Claims (1)

[Claims] 1. An iron pipe nut is connected to an aluminum pipe for a power steering device, and a zinc dust chromium oxide conversion film or a fluororesin film is provided on at least a surface of the iron nut that comes into contact with the aluminum pipe. A structure for connecting a pipe for a power steering device, which is characterized in that