Acoustics – Sound-modifying means – Muffler – fluid conducting type
Patent
1992-03-27
1995-10-31
Dang, Khanh
Acoustics
Sound-modifying means
Muffler, fluid conducting type
285268, F01N 710, F16L 2704
Patent
active
054631947
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an exhaust system and in particular to the joint in an internal combustion engine between the exhaust manifold and the down pipe.
BACKGROUND OF THE INVENTION
The engine of a motor vehicle is supported on flexible engine mounts and can rock during operation. Because of the mass of the exhaust pipe and the manner of its mounting on the vehicle body, rocking of the engine gives rise to significant stresses in the exhaust system which reduce the life of the system.
In order to assist in isolating the exhaust system from the rocking of the engine, flexible ball joints have been proposed for use at the junction between two pipe sections. The term "flexible ball joint" is used in the present specification to a refer to a joint having a collar with a part-spherical surface which seals between a flange on one of the pipe sections and a part-spherical seat on the other, the joint allowing the pipe sections to pivot relative to one another without any escape of exhaust gases.
Such a joint has been used at the lower end of the down pipe, but there it is far removed from the rocking axis of the engine. The length of the down pipe exaggerates the rocking and introduces considerable side to side movement, which cannot be accommodated by a single flexible ball joint.
It has also been proposed to use a flexible ball joint at the top end of the down pipe, where it joins on to the exhaust manifold. In this case, the down pipe has but a single conduit and it is not possible to tune the length of the branches of the exhaust manifold to enhance scavenging.
GB-A-1 586 244 describes an exhaust system for a motor vehicle internal combustion engine, in which the lower end of the exhaust manifold and the upper end of the down pipe each comprise two conduits which are sector shaped in cross section and are arranged to form a complete circle split by radial walls. The circumference of the down pipe is sealed by a flexible ball joint against the circumference of the manifold and the radial walls of the down pipe are spaced from the radial walls of the manifold by a small gap sufficient to permit pivoting of the down pipe relative to the manifold.
Though this exhaust system is capable of permitting the engine to rock relative to the down pipe, the construction and design of the clamping bolts which hold the parts of the flexible ball joint against one another interfere with the operation of the ball joint and are a source of squeaks.
OBJECT OF THE INVENTION
The invention therefore seeks to provide an exhaust system in which a flexible ball joint is provided to enable the engine to rock relative to exhaust down pipe but in which the flexible ball joint is held together by clamping bolts which do not interfere with the function of the ball joint and do not squeak in operation.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an exhaust system for a motor vehicle internal combustion engine, in which the lower end of the exhaust manifold and the upper end of the down pipe each comprise two or more conduits which are sector shaped in cross section and are arranged to form a complete circle split by radial walls, and wherein the circumference of the down pipe is sealed by a flexible ball joint against the circumference of the manifold and the radial walls of the down pipe are spaced from the radial walls of the manifold by a small gap sufficient to permit pivoting of the down pipe relative to the manifold, characterised in that the down pipe is urged against the manifold by clamping bolts the heads of which are pivotable relative to the manifold about an axis passing through the pivotal centre of the flexible ball joint.
Conveniently, the exhaust manifold and the down pipe are divided into only two conduits by a partition wall extending along a diameter of the flexible ball joint.
A further problem found with the proposal of GB-1 586 244 is that the pivotal centre of the flexible ball joint is far removed from the roll centre of the engine. The rol
REFERENCES:
patent: 4182121 (1980-01-01), Hall
patent: 4188784 (1980-02-01), Hall
patent: 4516782 (1985-05-01), Usher
patent: 4856822 (1989-08-01), Parker
Ransom Keith C.
Southwell Michael J.
Dang Khanh
Drouillard Jerome R.
Ford Motor Company
May Roger L.
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