Integral exhaust manifold

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to an integral casting member in which iron-based same or different casting members are joined by friction welding, and more specifically, for example, the exhaust manifold as an exhaust system component used in an internal combustion engine is divided into at least two or more. However, the present invention relates to an integrated exhaust manifold in which heat-resistant cast steel castings or heat-resistant cast steel castings and spheroidal graphite cast iron castings are manufactured as separate bodies, and these are joined by friction welding.

【0002】

[Conventional technology]

Conventionally, there is an exhaust manifold 1a as a tubular heat-resistant member that collects the exhaust gas of an engine and sends it to a muffler. As shown in FIG. 2, the exhaust manifold 1a consists of a mounting flange 3 to be attached to the cylinder head 2, a branch pipe 4 connected to each exhaust port of the cylinder head 2, and a collecting pipe 5 for collecting the branch pipes 4. Exhaust gas passing through each branch pipe 4 is designed to be discharged from the outlet port 6. Further, the collecting pipe 5 is divided into two or three in order to suppress thermal deformation, and each divided manifold is connected by a fitting portion 7. However, it takes a lot of man-hours to process the fitting portion 7, and it is not possible to completely prevent gas leakage due to thermal deformation of the fitting portion 7. Further, since the flange portion is provided for fitting, the weight is increased, and there is a problem that the management and cost of parts such as a seal ring (not shown) are increased. Therefore, as a means for solving the above problems, an exhaust manifold and an exhaust manifold integrally formed by casting are divided, molded by casting, and then integrated by welding.

【0003】

[Problems to be Solved by the Invention]

In the proposal by the conventional method, there is a manifold for a large engine in the structure integrally molded by casting, but it cannot be manufactured with the existing casting frame because the total length is longer than 800 mm. .. In order to manufacture by integral molding by casting, a special large casting frame is required, and a large-scale molding equipment with new investment is required. In addition, the one-piece shape complicates the casting plan, and there is a concern that the manufacturing cost will increase due to the decrease in casting yield. Further, in the case where the exhaust manifold is cast as a separate body by casting and then integrally molded by welding, there is a concern that the number of welding steps will increase and the thermal change and thermal strain of the microstructure due to welding heat will occur.

【0004】

An object of the present invention is to avoid the above problems and to provide an inexpensive and highly reliable exhaust manifold by joining the exhaust manifolds cast separately by friction welding and continuously integrally molding them.

【0005】

[Means for solving problems]

The present inventors manufacture a long member having a length of about 800 mm as two or more separate bodies, such as an exhaust manifold for a large engine, and join them by friction welding to make a large casting at a molding site. Focusing on the fact that the frame is not required and that the integration is effective in reducing the weight of the automobile, the present invention was made as a result of diligent research.

【0006】

The integrated exhaust manifold of the present invention is characterized in that, in a gasoline and diesel internal combustion engine, the exhaust manifold of the internal combustion engine is divided into at least two or more, each is manufactured separately, and these are continuously integrally molded by friction welding. To do. The separate exhaust manifolds may both be cast steel or cast steel and cast iron. Since heat resistance is required, heat-resistant cast steel is used as the cast steel, and spheroidal graphite cast iron is used as the cast iron. Further, it is characterized in that no chill is present in the friction welding joint portion of the one-piece casting member of the present invention joined by friction welding, and the friction welding joint is formed by a joint close to solid phase welding. Is. With this configuration, it is possible to improve the function of the internal combustion engine, reduce the number of parts, prevent gas leakage, reduce the size and weight, and shorten the processing / assembling man-hours.

【0007】

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a main part of the integrated exhaust manifold 1 obtained by pressure welding by the friction welding method according to the present invention. The integrated exhaust manifold 1 is divided into at least two or more, and each is composed of a heat-resistant cast steel exhaust manifold cast separately. In this way, casting as a separate body does not require a special large casting frame, and does not require large-scale molding equipment due to new investment. In order to obtain the integrated exhaust manifold 1 of the present invention, after relative movement while rubbing the members with a friction pressure of 20 to 40 MPa and a friction time of 60 to 120 seconds, an upset pressure of 80 to 140 MPa and an upset time of 6 to 10 seconds are obtained. Perform the upset with. There is no chill at the friction welding boundary 8 joined in this way, and the joining is extremely good.

【0008】

A heating / cooling test using an in-line 6-cylinder high-performance diesel engine with a displacement of 7.8 liters was conducted as a means of confirming the reliability of the integrated exhaust manifold 1 in which the exhaust manifold 1 made of ferritic heat-resistant cast steel was continuously integrally molded by friction welding. went. The test conditions were 250 hours in a cold heat (GO-STOP) cycle with one cycle of heating (5 minutes) -cooling (5 minutes) equivalent to full-load operation at an engine speed of 3000 rpm. The exhaust gas temperature at full load was about 870 ° C. Under this condition, the temperature of the part of the collecting pipe 5 of the integrated exhaust manifold 1 was about 690 ° C. As a result of the evaluation test, in the conventional exhaust manifold, gas leaks from the fitting portion 7 of the exhaust manifold due to the thermal deformation of the fitting portion 7 and the deformation of the seal ring, whereas the integrated exhaust manifold 1 of the present invention causes gas leakage. No gas leaks or cracks occurred from the friction welding portion 8 and other parts. From the above results, it was confirmed that the integrated exhaust manifold 1 of the present invention has excellent durability and reliability.

【0009】

[Effect of the invention]

As described above, the integrated exhaust manifold of the present invention, which is divided into at least two parts and the exhaust manifolds cast separately from each other are joined by friction welding, is special because it can be manufactured as a separate casting. Since it can be easily manufactured without the need for a large casting frame and does not require new capital investment, it contributes to the production effect and has a great economic merit. Further, unlike the welding by welding as in the prior art, the joint can be integrated without generating a large amount of heat, so that the influence of thermal strain does not occur and the reliability of the joint is greatly improved. Therefore, the integrated exhaust manifold of the present invention is inexpensive and has excellent durability, and can completely prevent the leakage of exhaust gas from the joint, which contributes to the improvement of the global environment. ..

[Simple explanation of drawings]

[Figure 1]

It is a front view of the main part of the integrated exhaust manifold obtained by joining by the friction welding method according to the present invention.

[Figure 2]

It is a front view of the conventional split type exhaust manifold.

[Explanation of symbols]

1a Conventional exhaust manifold 1 Integrated exhaust manifold 2 Cylinder head 3 Mounting flange 4 branch pipe 5 Collecting pipe 6 exit port 7 Fitting part 8 Friction welding joint