GB2358686A

GB2358686A - A strain absorption device for a vehicle exhaust

Info

Publication number: GB2358686A
Application number: GB0009745A
Authority: GB
Inventors: Ki Woon Sung
Original assignee: DNV Inc
Current assignee: DNV Inc
Priority date: 2000-01-28
Filing date: 2000-04-19
Publication date: 2001-08-01
Also published as: DE10021494A1; GB2358686A8; GB0009745D0; KR200187118Y1

Abstract

A strain absorption device for a vehicle exhaust comprises an inner sleeve 20 defining a gas flow path, and an inner retainer 30. An outer retainer 40 is connected to the inner retainer by a flexible element, eg bellows 10, located within the inner retainer. The inner retainer is located within the outer retainer, and buffer means 50, 60 are provided between the inner retainer and the outer retainer. Preferably the device is a flexible decoupler for the exhaust pipe of automobiles, and the inner retainer has circular-arc surfaces 31, 32 at both ends of a cylindrical portion 34. The outer retainer may have an inclined section 41, a perpendicular portion 42, and a buffer cover 44 for protecting a first buffer 50 having a sliding surface 70 on its inner surface. Preferably the buffer means are made of resilient material such as a thin wire net.

Description

2358686 FLEXIBLE DECOUPLER FOR EXHAUST PIPE OF AUTOMOBILES The present

invention relates to a flexible decoupler f or exhaust pipe of automobiles, and more particularly, to the flexible decoupler for effectively absorbing the bending displacement from the engine and road vibrations, thereby improving the durability of the exhaust system.

Recent vehicles preferably tend to adopt the larger engines, which increase the engine roll vibration in startup, sudden acceleration or gearshift. Further, the vib.rations of the exhaust pipe may occur depending on the road conditions.

Conventional engines of the vehicle are connected to the exhaust pipe employing a muffler for exhausting the exhaust gas from the vehicle. For connection, a decoupler is installed to absorb and buffer the vibration displacement, impact load or heat deformation. The decoupler on this location should be strong and compact for self-supporting the exhaust pipe with minimum number of lightweight hanger mount.

GB Publication 2,277,969A has described the forced determination of a center point for the bending 2 displacement to absorb the bending displacement. Fig. 1 (Prior Art) shows that both sleeves 5 and 6 are interposed with a predetermined interval, in which the sleeve 6 is separated by the projection 7 to form two pockets on both portions. The pockets are filled with the buffer(s) 8. A bellows 9 is arranged between the sleeves 5 and 6, and one end of the bellows 9 is engaged with the buffer 8.

A center displacement C is determined in the middle of the position at which the sleeves 5 and 6 are interposed, so that the buffer 8 and the bellows 9 may absorb the expansion displacement in the longitudinal direction from engine vibration or impact occurred in the travelling and bending displacement at which the central axis degrees are intercrossed around the decoupler.

In the prior art, the bellows 9 has been externally exposed and it may be easily damaged by corrosion or unexpected objects in travelling.

- Because the center displacement C for absorbing the buffering and bending is located approximately in the middle of the buffer 8, the inner sleeve 6 connected to the exhaust pipe is directly exposed to the exhaust gas at high temperature when the impact of a sudden large displacement is applied. Moreover, in case that the heavy impact load is repetitively applied in this condition, the fatigue life is shortened.

3 The bellows 9 receives the forced moment bending, not an angular motion bending, which shortens the lifetime.

Various attempts to overcome the above disadvantages have been considered. One of them is to increase the number of creases in the bellows 9. However, this attempt causes an entire length of the bellows to be increased and the quality of material should be superior, which increases the costs in producing the device.

Since the buffer 8 cannot efficiently absorb the displacement in the bending direction, the conventional device is not suitable for the function of absorbing the large bending and the scope to be applied of the decoupler is very limited.

Another attempt is found in Japanese Patent Laid- open Publication 11-93657 which discloses the stopper function to be maintained by the outer cover in tension motion, while the displacement absorbing capability should be maintained by the reaction forces of the bellows and a coil spring on the bellows in compression. The external forces from the vibration motion or the engine motion to compress the exhaust system are stronger than the coil spring and the bellows.

Being slid with the inclined portion of the outer cover along the inclined portion on the buffer should absorb the bending motion. However, in the compressed 4 state the absorbing capability in the bending direction is not guaranteed. It has disadvantages to reduce the durability and vibration absorbing or noise reduction capabilities. 5 Accordingly, it is an object of the present invention to provide a flexible decoupler in automobiles in which the bending displacement from the engine vibration or road vibration is effectively absorbed even in the narrow arrangement space, to improve the durability of the exhaust system and passengers' comfort.

It is the other object of the present invention to provide a flexible decoupler for improving the product reliability.

The invention is set out in the appended claims.

To achieve the above objects, according to the present invention, there is provided a flexible decoupler comprising a bellows 10 for absorbing the bending and expansion to maintain the exhaust gas to be airtight; an inner sleeve 20 in a cylindrical shape, located inward the bellows 10, for supporting the bellows 10 through which the exhaust gas at high temperature may pass; an inner retainer 30 engaged with one end of the bellows 10, located outward the bellows 10; an outer retainer 40 engaged with the other end of the bellows 10, located outward the inner retainer 30; and first buffer 50 and second buffer 60 between the inner retainer 30 and the outer retainer 40 for absorbing the displacements, characterized in that the inner retainer 30 has a circular-arc surfaces 31 and 32 at both ends of a cylindrical portion 34, with respect to the motion center C of the bellows 10; the outer retainer 40 has an inclined section 41 and a perpendicular section 42 with respect to the motion center C; and a buffering protector 44 for protecting the first buffer 50 having a sliding surface 70 on an inner side thereof, located between the circular-arc surface 32 and the perpendicular portion 42 is rovided in a body.

The flexible decoupler of the present invention includes an inner retainer 30 located outward the bellows 10; circular-arc surfaces 31 and 33, inclined section 41 and a perpendicular section 42 arranged at the opposing ends of the outer retainer 40 with respect to the motion center C of the bellows 10; first and second buffers 50 and 60 employing a sliding surface 70 having the same contact surface with the circular-arc surfaces 31 and 32 between the inner retainer 30 and the outer retainer 40, thereby efficiently absorbing the bending displacement A buffering cover 44 functions to protect the edge of the first buffer 50 and prevents the first buffer 50 from corrosion or damage due to the external exposure.

6 Embodiments of the invention will now be described, by way of example, with reference to the drawings, of which:

Fig. 1 is a sectional view of the conventional 5 decoupler of the exhaust pipe.

- Fig. 2 is a sectional view of the flexible decoupler of the automobile exhaust pipe according to the present invention; Fig. 3 is a schematic view in which the inner retainer moves in the bending direction to absorb the bending displacement; and Fig. 4 shows a preferred embodiment of the present invention, showing the inner sleeves at both ends.

Engines are generally supported by a number of installations employing a muffler in the direction of the decoupler of the exhaust pipe. The decoupler connects the engines and the exhaust pipe.

Referring to Figs. 2 to 4, a bellows 10 of the flexible decoupler of the automobile exhaust pipe functions to absorb the displacement in the directions of the expansion and bending, and prevents the exhaust gas though the inner sleeve 20 from leaking out.

The bellows 10 of a repeatedly corrugated shape can readily accommodate both axial displacement and bending displacement, and recovers the original shape when the 7 external forces causing displacement are removed.

An inner sleeve 20 of a cylindrical shape through which the exhaust gas at high temperature is located inward the bellows 10, for protecting the bellows 10. The inner sleeve 20 may be separately arranged in the lateral direction as shown in Fig. 4, to reduce the exhaust resistance.

Referring to Fig. 3, an inner retainer 30 located outward the bellows 10 is moved with the bellows 10 in the bending direction. The inner retainer 30 has a con,figuration in such that a cylindrical portion 34 is arranged in the middle of the inner retainer 30, and circular-arc surfaces 31 and 32 are arranged on the radius Rl with respect to the motion center C of the bellows 10.

The circular-arc surfaces 31 and 32 in a unilateral direction on both ends of the inner retainer 30 have a predetermined angle with respect to the motion center C of the bellows 10. Referring to Fig. 2, the circular- arc surfaces 31 and 32 having a predetermined radius Rl at the motion center C of the bellows 10 slide with a second buffer 60 to absorb the bending impact.

The bending center is set to a motion center C of the bellows 10 to induce an angular motion from the bellows 10 to lower the stress, to maintain the endurance, with the small number of creases in the 8 bellows.

An intermittent jaw 33 is arranged at the end of the circular-arc surfaces 31 of the inner retainer 30, to be in contact with the second buffer 60 to perform the 5 function of stopper (as shown in Fig. 3).

Outward located from the inner retainer 30 is an outer retainer 40, which is engaged with one end of the bellows 10. The outer retainer 40 has an inclined section 41 with a predetermined angle with respect to the motion center C of the bellows 10.

The inclined section 41 and the perpendicular section 42 at both sides of the outer retainer 40 are arranged on a larger radius R2 than the radius Rl of the circular-arc surfaces 31 and 32 with respect to the center axis C of the bellows 10.

The buffering protector 44 at the end of the perpendicular section 42 protects the first buffer 50 (as shown in Fig. 3), and prevents the first buffer 50 from being externally exposed. The buffering protector 44 functions to accommodate sliding in the bending displacement.

A second buffer 60 is arranged in the inclined section 41 of the outer retainer 40. Outer section of the second buffer 60 has a predetermined radius R2 from the motion center C of the bellows 10, as in the inclined section 41.

9 Between the inner retainer 30 and the outer retainer 40, the first and the second buffers 50 and 60 are arranged on the circular-arc surfaces 31 and 33 of the inclined section 41 and the perpendicular section 42.

In case that the inner retainer 30 located outward the bellows 10 receives a bending displacement during travelling of the vehicles, the circular-arc surface 31 of the inner retainer 30 is slid according to the sliding surface 70 of the second buffer 60 in the bending direction, thereby absorbing the impact displacement.

The first buffer 50 at the rear end of the inner retainer 30 moves in the moving direction of the inner retainer 30 and is slid along the outer sliding surface 70 of the circular-arc surface 32 of the inner retainer 30, so as to absorb the impact displacement between the circular-arc surface 32 and the perpendicular portion 42.

A flange 80 is located beneath the second buffer 60, to be in contact with the intermittent jaw 33 of the inner retainer 30 with a predetermined angle 0, for performing the function as a stopper to limit the displacement angle.

Even if the displacement is higher than the desired angle 0, the flange 80 may absorb the displacement after partial transformation with a predetermined angle, without forcefully stopping the displacement.

The first buffer 50 may perform the function of the stopper, enabling the circular-arc surface 31 of the inner retainer 30 to be in contact with the sliding surface 70.

The first buffer 50 and the second buffer 60 are made of resilient material which can readily absorb the expansion displacement and bending displacement in the longitudinal direction and the impact from the road vibration in travelling. The first buffer 50 and the second buffer 60 should have the characteristics of resilience and easy deformation and are.preferably made of thin wire net in a ring shape.

Due to the repetitive frictions applied to the sli-ding surface 70 of the first and the second buffers 50 and 60, it is desirable to apply the carbon or insulation coating on the surface 70. Other method by appropriate surface treatment materials is also applicable. By this configuration, it is possible to have the self- supporting function on the exhaust pipe. The first and the second buffers 50 and 60 may have another possible shape other than a ring shape.

In the flexible decoupler for the exhaust pipe of automobiles, the inner retainer 30 slides with the outer retainer 40 to absorb the impact. Each buffer slides with the inner retainer and the outer retainer by the sliding surface to absorb the impact, thereby improving the durability.

According to the present invention, the outer retainer 40 and the inner retainer 30, both of which are arranged outward the bellows 10 to absorb the impact. The buffers are moved in the bending direction by sliding each retainers in the bending direction, to absorb the impact, thereby improving the durability of the decoupler. With use of the buffering cover 44 to protect the edge of the first buffer 50, the present invention also prevents the first buffer 50 from deviation or damage such as wear due to the external exposure.

Accordingly, the present invention has an effect to prolong the life of the exhaust system and improve the passenger's comforts. The present invention contributes the reduction of the wear and friction noise, so that it guarantees the product reliability and reduces the fatigue life of the exhaust pipe.

Those skilled in the art will readily recognize that these and various other modifications and changes may be made to the present invention without strictly following the exemplary application illustrated and described herein, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.

12 Cla'_ s 1. A flexible decoupler for automobiles, comprising: a bellows (10) for absorbing the bending and expansion to maintain the exhaust gas to be airtight; an inner sleeve (20) in a cylindrical shape, located inward the bellows (10), for supporting the bellows (10) through which the exhaust gas at high temperature may pass; an inner retainer (30) engaged with one end of the bellows (10), located outward the bellows (10); an outer retainer (40) engaged with the other end of the bellows (10), located outward the inner retainer (30); and first buffer (50) and second buffer (60) between the inner retainer (30) and the outer retainer (40) for absorbing the displacements, characterized in that the inner retainer (30) has a circular-arc surfaces (31) and (32) at both ends of a cylindrical portion (34), on the extended line with respect to the motion center (C) of the bellows (10); the outer retainer (40) has an inclined section (41) and a perpendicular portion (42) on' the extended line with respect to the motion center (C); and a buffering cover (4 4) for protecting the first buffer (50) having the sliding surface (70) on an inner side, located between the circular-arc surface (32) and the perpendicular portion (42) is provided, thereby efficiently absorbing the bending displacement by being slid in the bending direction.

2. A flexible decoupler for automobiles as claimed in claim 1, said inner sleeves (20) are located in the directions of the engine and the exhaust pipe, respectively.

3. A strain absorption device for a vehicle exhaust comprising: an inner sleeve defining an exhaust gas flow path; an inner retainer defining a continuation of the exhaust gas flow path; and an outer retainer connected to the inner retainer by a flexible element, in which:

the flexible element is provided within the inner retainer and the inner retainer is provided within the outer retainer, and buffer means are provided between the inner retainer and the outer retainer.

Amendments to the claims have been filed as follows the perpendicular portion (4,2) is provided, thereby efficiently absorbing the bending displacement by being slid in the bending direction.

2. A flexible decoupler for automobiles as claimed in claim 1, said inne r sleeves (20) are located in the directions of the engine and the exhaust pipe, re6pectively.