JPH0244150Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention can be used, for example, in automobile internal combustion engines, etc.
Exhaust air intake pipe (EAI), which is piped around the engine, connects one end to the exhaust manifold on the high temperature side and the other end to the air purifier to mix in the exhaust and supply secondary air. The present invention relates to improvements in the structure of these small-diameter metal pipes, such as pipes) or exhaust gas return pipes (EGR pipes) that return part of the exhaust gas to an air purifier.

[Conventional technology]

Conventionally, this type of EAI pipe or EGR pipe is a thin metal pipe with a pipe diameter of approximately 25 m/m or less and is made of a thin metal pipe with an exhaust manifold whose one end is in a high temperature atmosphere of 400°C to 700°C. Because it is connected to the exhaust gas and is constantly exposed to a corrosive atmosphere due to temperature changes in the exhaust gas or its condensed water, it is natural that the material must be
The entire piping body was composed of stainless steel pipes such as SUS409 or SUS304.

[Problem that the invention attempts to solve]

However, in such conventional products, the material is expensive due to the stainless steel pipe material extending over the entire length, and furthermore, it impedes bending workability, making simple manual bending work impossible, and generally requires complicated mechanical bending work. This has the problem of increasing the product cost.

In order to extremely effectively solve the above-mentioned conventional problems, the present invention specifically uses a short stainless steel pipe located on the high temperature side, and a carbon steel pipe on the other end. By welding these together to form the piping body and also having a plating layer of Ni-P alloy or Ni-B alloy on the inner circumferential surface, the material cost can be significantly reduced and bending process is easy. It is an object of the present invention to provide a piping body whose product cost is reduced by easy manual bending work due to improved flexibility.

[Means to solve the problem]

This idea consists of a relatively short stainless steel pipe and a carbon steel pipe, each of which has a connection structure to a mating body at one end, and the other ends of which are welded together and connected to each other, and the connected piping body Ni-P alloy or Ni-B on at least the inner peripheral surface over the entire length of the
The gist is a small-diameter metal pipe constructed with a plating layer made of an alloy.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. Fig. 1 is a plan view of a small diameter metal pipe of the present invention, and Fig. 2 is an enlarged cross-sectional end view of the line A-A in Fig. 1. P has a connection structure 1', such as a flange or a tightening nut, to the mating base at one end;
This is a piping body in which a relatively short stainless steel pipe 1 and a long carbon steel pipe 2 are connected by welding the other ends 1'' and 2'' to each other. Reference numeral 5 denotes a plating layer made of Ni--P alloy or Ni--B alloy, which is provided on at least the inner circumferential surface 4 over the entire length of the pipe body P. As shown in FIG. 3, the piping main body P is attached to the exhaust manifold 7 around the engine 8, with its one end connected to the exhaust manifold 7 as a mating base.
Also, the other end is connected to the air purifier 6 for use.

[Effect]

Since the present invention is constructed in this way, the stainless steel pipe 1 side is installed on the side that is most affected by the heat from the exhaust manifold 7 as a high temperature part, so that it is sufficiently resistant to oxidation in a high temperature atmosphere. At the same time, the plating layer 5 on the inner circumferential surface 4 can sufficiently satisfy not only heat resistance but also corrosion resistance in a corrosive atmosphere caused by temperature changes or condensed water.

[Effect of idea]

As explained above, the small-diameter metal pipe of the present invention has a structure of the pipe main body P by welding 3 of the short stainless steel pipe 1 and the long carbon steel pipe 2. The P material was made inexpensive, and at the same time, the product cost was made low enough that bending workability could be achieved through simple manual operations, and sufficient heat resistance and corrosion resistance in use conditions could be achieved. It has an extremely useful small-diameter metal piping structure.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a small-diameter metal pipe according to an embodiment of the present invention, Fig. 2 is an enlarged cross-sectional end view taken along line A-A in Fig. 1, and Fig. 3 is an installed state of the pipe shown in Fig. 1. figure. 1... Stainless steel pipe, 1'... Connection structure,
1"...Other end, 2...Carbon steel pipe, 2'...Connection structure, 2"...Other end, 3...Welding, 4...Inner peripheral surface, 5...Plating layer, P ...The main body of the piping.

Claims (1)

[Scope of utility model registration request] The other ends 1'', 2 of a relatively short stainless steel pipe 1 and a carbon steel pipe 2 each have connection structures 1', 2' to the exhaust manifold 7 and the air purifier 6 on one end side, respectively. '' are welded 3 and connected to each other to form a piping body P, and at least the inner circumferential surface 4 over the entire length of the piping body is made of Ni-P alloy or Ni-B.
A small diameter metal pipe characterized by having a plating layer 5 made of an alloy.