Pipe joints or couplings – With casing – lining or protector – Insulated
Reexamination Certificate
1999-11-18
2001-12-18
Browne, Lynne H. (Department: 3629)
Pipe joints or couplings
With casing, lining or protector
Insulated
C285S300000
Reexamination Certificate
active
06331019
ABSTRACT:
The invention relates to a conduit vibration decoupling device and more particularly to a conduit vibration decoupling device for use in exhaust systems of internal combustion engines.
BACKGROUND OF THE INVENTION
The invention relates, in particular, to a fluid-tight conduit vibration decoupling device having a bellows-type corrugated connecting element which permits changes in axial length and angular displacements. Such a connecting element is, however, sensitive to mechanical stresses especially torsional stresses, so that these stresses need to be by-passed around the connecting element by means of a force transmitting means commonly comprising an articulated spring assembly. Conduit vibration decoupling devices can be subdivided, in dependence on the way in which their articulated spring assemblies are designed, into those where the elasticity is provided by a coil spring extending circumferentially of the centre line of the decoupling device or by a wire cable spring element, and those in which individual spring units are provided. Examples of decoupling devices of the first type are to be found in the following publications: DE-A-44 01 827, EP-A-0 432 436, EP-A-0 615 595, U.S. Pat. No. 3,369,829, EP-B-747 582. The invention is directed to a conduit vibration decoupling device of the second type as is known e.g. from U.S. Pat. No. 5 299 827. In the prior device three annular cable spring units are provided, these being arranged around the periphery of an adjacent conduit connecting member at circumferentially spaced locations and each being rigidly connected to the housing and the conduit connecting member independently of one another. A large amount of space is therefore required between the housing and the conduit connecting member for accommodating these cable spring units so that the known decoupling device has a large radial dimension and this thus runs counter to the trend in the automobile industry towards lightweight, compact decoupling devices. In addition, the sensitive, bellows-type connecting element is not protected or is only protected to a limited extent from torsional stress. Furthermore, a decoupling device of the second type is known from EP-B-0 816 738 which, in contrast to the previously described known device, has the advantage that it can be fabricated and assembled in an effective easy manner whilst, at the same time, being of compact size. In this prior device three linear leaf spring units are disposed around the periphery of an adjacent conduit connecting member, the ends of said units being supported on the housing with a certain amount of circumferential play i.e. in “floating” manner. Further each spring unit engages with clearance the adjacent conduit connecting member and extends therethrough like a secant passing through a circle. The not play-free coupling of the spring units to the housing and the conduit connecting member can lead to the development of irritating noises in use. Furthermore, due to the floating support of the spring units, a relative rotation, even though of limited extent, between the conduit connecting member and the housing cannot be avoided so that the sensitive, bellows-type connecting element will be subjected to a certain amount of torsional stress, which, although lower than was the case for the decoupling device in the aforementioned U.S. Pat. No. 5,299,827, nevertheless may result in a shortening of its useful working life.
An object of the invention is to provide an improved conduit vibration decoupling device. Another object of the invention is to provide a conduit vibration decoupling device having an articulated spring assembly which can easily be manufactured and assembled. Still another object of the invention is to provide a conduit vibration decoupling device in which the bellows-type corrugated connecting element has a greater degree of protection against torsional stress. A further object of the invention is to provide a conduit vibration decoupling device in which the development of noise on the part of the decoupling device can be reduced and a reduction in the dimensions of the decoupling( device realized.
SUMMARY OF THE INVENTION
The conduit vibration decoupling device according to the invention comprises a pair of axially spaced conduit connecting members interconnected with each other by a flexible connecting element, and a force transmitting means having at least axial elasticity for transferring forces between said conduit connecting members whilst by-passing the flexible connecting element. The force transmitting means comprises a housing surrounding said flexible connecting element. The housing is connected near at least one axial end thereof to an adjacent conduit connecting member by an articulated spring assembly having at least a pair of spring means. Each of said spring means comprises at least a single leaf spring element and has end portions spaced from each other. The end portions are supported by said housing. The spring means at an intermediate portion thereof between said end portions is mounted to the conduit connecting member and at one of said end portions to the housing substantially free from clearance or play at least in the circumferential direction of the decoupling device. Consequently, each articulated spring assembly comprises two or more spring) units or spring means distributed around the periphery of the corresponding adjacent conduit connecting member, in which each of said spring means is a component independent of the others and comprising one or preferably more leaf spring elements. In contrast to the above-mentioned known decoupling device having leaf spring elements, the spring means according to the present invention are not “floatingly” supported by the housing or the conduit connecting member with freeplay or clearance, but rather, the spring means do not have any freeplay or clearance with respect to these parts so that the sensitive, flexible, preferably bellows-type connecting element is not involved, not even to a limited degree, in a transfer of torsional forces between the conduit connecting members. The flexible connecting element is thereby protected effectively against torsional loads of any strength. At the same time, the play-free mounting of the spring means to the adjacent conduit connecting member and the housing prevents the occurrence of irritating rattling noises. The play-free mounting can be achieved in several ways by using convenient fabrication techniques. Preferably, the end portions of adjacent spring means overlap each another and thus form a common force transmitting assembly which can be formed without using weakening or time consuming rivet, pin or weld connections. Preferably the play-free mounting is achieved by a clamping interengagement of the parts. A transfer of force from one part to an adjacent one, with the force being distributed over a large surface area, can thereby be achieved, thus avoiding peak loadings which could reduce the useful working life of the assembly. Furthermore a self-aligning property is simultaneously provided for these spring means at the force transmitting portions, thereby making an assembly of the parts less sensitive to the maintenance of tight manufacturing tolerances. If desired, however, a rivet assembly may also be provided. Moreover, the force transmitting portions at the housing end need not be rigid but may be resilient, this being relevant to the transfer of axial forces, so that the freedom from play in the circumferential direction will have only very little or no effect upon the spring behaviour of the spring means. Consequently, in a manner similar to that of the known decoupling devices, the flexibility of the spring means under the effects of axial stress is ensured in like manner to the natural vibration damping property of a plurality of leaf spring elements combined into a spring stack from which each spring means is preferably formed. In accordance with a particularly advantageous embodiment of the invention, the adjacent spring means do not just overlap each another, but each
Friess Werner
Jahnel Harald
Morgner Dietmar
Vogt Christian
Browne Lynne H.
Feodor Burgmann Dichtungswerke GmbH & Co.
Thompson Kenn
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