JPS6146173Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an exhaust pipe for an automobile engine.

In so-called horizontally mounted front-engine, front-drive automobiles in which the rotating shaft of the engine is arranged in the width direction of the vehicle, engine vibrations in the longitudinal direction of the automobile also spread to the exhaust pipe extending rearward. Engine vibrations that have a large vibration effect on the exhaust pipe include vibrations associated with high-speed engine rotation and vibrations due to torque reaction force when the engine load suddenly changes. It also has a large impact on Moreover, the vehicle body vibrates while driving, and it is inevitable that these vibrations will spread to the exhaust pipe. Furthermore, the exhaust pipe is usually arranged in a bent manner on the vehicle body, and the bent portion tends to lack strength because stress due to vibration is concentrated therein.

The purpose of this proposal is to improve the strength of the bent portion of the exhaust pipe with an extremely simple configuration.

To give a concrete explanation based on the illustrated example, 1 is a so-called horizontally mounted engine, 2 is a gearbox integrated with the engine 1, and power from the engine 1 is transmitted through the output shaft 3 of the differential device in the gearbox 2. The signal is transmitted to the front wheels 4. The engine 1 and gearbox 2 are supported by the vehicle body via elastic bodies not shown in the figure. Reference numeral 5 denotes an exhaust pipe, which is bent from the front side of the engine 1 to below the engine and led to the rear, and is connected to a rear muffler 7 via a sub-muffler 6 on the way. The mufflers 6 and 7 are supported by the vehicle body via elastic bodies, but are not shown in the figure.

The aforementioned engine vibrations, particularly vibrations caused by torque reaction force when the engine load suddenly changes, cause the entire power unit to vibrate around a certain position O between the output shaft of the engine and the output shaft of the differential gear. This vibration is mainly a vibration in the longitudinal direction, which is transmitted to the exhaust pipe 5, and stress is concentrated on the bent portions 5a to 5c.
In particular, the bent portion 5a extending from the front side of the engine downward is susceptible to the effects of vehicle body vibration in the vertical direction.

Therefore, in the present invention, as shown in Fig. 3, the bent portion 5a of the exhaust pipe 5 is formed into a substantially elliptical cross section with the long axis extending in the inner and outer directions of the bent portion (Fig. 3b,
d).

Although not shown in the figure, other bent parts, such as the bent part 5b between the engine 1 and the sub-muffler 6, and the bent part 5c between the sub-muffler 6 and the muffler 7, have a substantially oval cross section in the same manner as above. may be formed.

As a processing method, for example, the part to be bent is flattened in advance to a substantially oval cross section, and then
Bending is performed using a bending die such as the punch 8 and die 9 shown in the figure. Alternatively, if the flattening ratio is small, it is also possible to directly process the flattening at the same time as the bending process using a suitable bending die.

In this case, as described above, the bent part of the exhaust pipe 5 is formed into a substantially elliptical cross section with the long axis in the inner and outer directions of the bent part, so the section modulus in the direction perpendicular to the vibration direction increases, and the exhaust pipe bends. The strength of the part can be improved.

Furthermore, recently there has been a trend to reduce the weight of vehicles as much as possible from the viewpoint of energy conservation, and it is desired to reduce the thickness of the exhaust pipe as much as possible. Conventionally, it was not possible to make the exhaust pipe very thin because the strength of the bent portion was insufficient, but the present invention has the advantage that the required strength of the bent portion of the exhaust pipe can be ensured even if the exhaust pipe is made considerably thin.

[Brief explanation of the drawing]

Figure 1 is a plan view of an example in which the exhaust pipe of the present invention is installed in a vehicle with a horizontally mounted engine, Figure 2 is a side view thereof, and Figure 3 is a side view of the exhaust pipe.
Figure a is an enlarged view of a part thereof, figures b to e are sectional views taken along lines bb, cc, dd, and ee in figure a, and Figure 4 is a front view of the bending die. 1 is an engine, 2 is a gearbox, 3 is an output shaft, 4 is a front wheel, 5 is an exhaust pipe, and 5a to 5c are bent parts.

Claims (1)

[Scope of Claim for Utility Model Registration] In a front-engine, front-drive vehicle with a horizontally mounted engine, the bent portion of the exhaust pipe from the front side of the engine to the bottom of the engine has an approximate cross-sectional length whose major axis is in the inward and outward direction of the bent portion. A circular exhaust pipe for an automobile engine.