Exhaust clamp for a motorcycle

The invention recites an exhaust pipe clamp for clamping at least two pipes. The clamp includes a band formed to at least partially surround each of the two pipes, the band defining an internal volume. A reaction block is interconnected with the band and disposed substantially within the internal volume. The exhaust clamp also includes a clamping member operable to reduce the internal volume of the band.

BACKGROUND OF THE INVENTION

The present invention relates to vehicle exhaust systems, and particularly a clamping mechanism for dual exhaust pipe systems.

Most vehicles include exhaust systems for guiding exhaust gases from a vehicle engine. Such exhaust systems typically include an exhaust pipe for guiding the exhaust gases, and a muffler for reducing noise. The exhaust pipe commonly includes one or more exhaust clamps that support the exhaust pipe and/or muffler relative to the vehicle chassis. Some vehicles include two or more exhaust pipes, with each exhaust pipe typically including an exhaust clamp for supporting the exhaust pipe.

Because the exhaust system of a motorcycle is generally visible, it is important that it, and any clamps, be aesthetically pleasing. To that end, large sweeping curves, chrome plating, and compact fits against the body of the motorcycle are used to increase the visual appeal of the vehicle. These features often require the connection of different pipes with the connecting mechanism often being visible.

In addition to supporting the exhaust pipes, mufflers, and other exhaust components, exhaust clamps can be used to clamp one pipe section to another pipe section. When used in this manner, it is important to achieve an adequate seal between the two pipes.

SUMMARY OF THE PREFERRED EMBODIMENTS

The apparatus of the invention provides an exhaust pipe clamp for clamping at least two pipes. The clamp includes a band formed to at least partially surround each of the two pipes, the band defining an internal volume. A reaction block is interconnected with the band and disposed substantially within the internal volume. The exhaust clamp also includes a clamping member operable to reduce the internal volume of the band.

In preferred constructions two reaction blocks having angled surfaces in contact with one another cooperate with the band to define two lobes. Each lobe substantially surrounds one of the pipes. Operation of the clamping member moves the reaction block angled surfaces against one another to reduce the size of the lobe.

In another embodiment the invention provides an exhaust system including a first outside pipe and a second outside pipe spaced a distance from the first pipe. The exhaust system also includes a first inside pipe having a portion at least partially disposed within the first outside pipe, and a second inside pipe having a portion at least partially disposed within the second outside pipe. A pipe clamp including a band is formed to at least partially surround a portion of the first and second outside pipes. A reaction block is interconnected with the band and disposed between the first and second outside pipes. A clamping member is operable to move the first and second outside pipes into substantial sealing contact with the first and second inside pipes respectively.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring toFIG. 1, a motorcycle10is illustrated as including an engine15and an exhaust system20. The engine15burns fuel to power the motorcycle10and produces exhaust gas as a by-product. The hot exhaust gas passes through the exhaust system20and out near the rear of the motorcycle10. The exhaust system20performs several functions including collecting and routing the exhaust gas and quieting the exhaust using a muffler.

Referring toFIG. 2, the invention relates to an exhaust clamp25that facilitates clamping two exhaust pipes30on a motorcycle10using a single clamping mechanism. The exhaust pipes30include two outside pipes35that receive a flow of exhaust gas from the engine15at one end and include a joint portion40at the opposite end. The exhaust pipes30also include two inside pipes45that receive the flow of exhaust gas from the outside pipes35at the joint portion40and discharge the flow to mufflers near the rear of the motorcycle10. A pipe clamp such as the exhaust clamp25, illustrated inFIGS. 3-5, connects the outside pipes35to the inside pipes45adjacent the joint portion40and maintains a seal therebetween.

The outside pipes35include several bends and curves that position the joint portion40of the two outside pipes35in a substantially parallel side-by-side relationship. The inside pipes45each include a stub portion50that is sized to fit inside the outside pipes35. The stub portions50are also positioned in a substantially parallel side-by-side relationship. When the inside pipes45are inserted into the outside pipes35, a lap joint is formed. To seal the lap joint, the exhaust clamp25preferably provides a compressive force completely around the two outside pipes35.

The exhaust clamp25, illustrated inFIGS. 3 and 4, includes a band55, a pair of reaction blocks60, a clamping member65, and a pair of washer blocks70. The band55ofFIGS. 3 and 4is a single continuous piece formed into a figure-eight shape to at least partially define two lobes75, an inner surface80, and an outer surface85. The two lobes75fit over the two outside pipes35such that the band55surrounds both pipes35and each lobe75at least partially surrounds one of the pipes35. In the relaxed or uncompressed state, the band55defines a volume and the size of each lobe75allows it to fit loosely over the exterior of the outside pipes35. Other constructions may use non-continuous bands55A, such as shown inFIG. 5, or may use bands that are not figure-eight shaped.

In preferred constructions, the band55is formed from steel or other metals having suitable properties (e.g., strength, ductility, corrosion resistance, thermal expansion, etc.). Alternative constructions may use ceramics, composites, plastics, or other materials suitable for the application.

The band55includes two apertures90located in the narrow region between the lobes75. The apertures90are sized to receive the clamping member65such that operation of the clamping member65narrows the narrow portion of the band55. The clamping member, such as a nut100and bolt105as illustrated inFIGS. 3-5, freely passes through the apertures90within the band55and is operable to compress the lobes75and clamp the pipes35,45.

Two reaction blocks60are positioned within the band55to complete the lobes75and provide for even clamping of the pipes35,45. Each reaction block60is substantially wedge-shaped with two arcuate surfaces110,112and one angled or wedge surface115. An aperture120extends through each block60and passes through one of the arcuate surfaces110and one of the apexes. The arcuate surface110containing the aperture120abuts the inner surface80of the band55on either side of the band55between the lobes75such that the apertures120in the reaction blocks60align with the apertures90in the band55. The bolt105then passes through the band apertures90and the apertures120within the reaction blocks60.

The arcuate surface110is shaped to provide suitable contact between the reaction block60and the inside surface80of the band55. Therefore, any shape surface may be used to accommodate the inside surface80of the band55. For example, the band55A ofFIG. 5provides a flat surface125, and the reaction blocks60A used with the band ofFIG. 5employ a flat surface to achieve the desired amount of contact.

The reaction blocks60are positioned in a manner that allows the second arcuate surface112of the blocks60to abut the outside pipes35that pass through the lobes75of the clamp25. The arcuate surfaces112are shaped to substantially complete each lobe75when in the clamped position and to provide suitable contact between the reaction block60and the outside pipes35. Thus, each reaction block60cooperates with the band55to substantially surround the outside pipes35. In an alternative construction, a single block having an hourglass shape replaces the two reaction blocks60. In still other constructions, the band is oval or racetrack shaped, and the reaction blocks define a larger portion of the lobe75. Any shape band can be used so long as the inside surface of the band and the reaction blocks cooperate to define two substantially complete lobes75suitable for clamping the pipes35,45.

The wedge surfaces115of the two blocks60abut one another. During clamping, the wedge surfaces115slide past one another and force the second arcuate surface112into the outside pipe35. The angle on the wedge portion115can be varied to provide greater or less force as required by the specific application.

The reaction blocks60are preferably made from steel or other metals that have sufficient strength to compress the pipes35,45. Alternative constructions may use other materials with suitable properties (e.g., ceramics, composites, plastics, rubber, etc.).

The washer blocks70include an arcuate surface130and a second surface135shaped to receive the clamping member65. The arcuate surface130is shaped to engage the outer surface85of the band55between the lobes75. The arcuate surface130illustrated inFIG. 3is semicircular. Alternative constructions may call for a different curve such as a half oval, or a parabolic shape. Still other constructions may call for the use of a flat surface instead of the arcuate surface described above.

The second surfaces135of the washer blocks70are flat to allow them to support the nut100and bolt105of the clamping member65. The two washer blocks70are positioned on opposite sides of the band55between the lobes75with their arcuate surfaces130engaging the band55. The two flat surfaces135remain parallel to one another, thereby allowing the bolt105to apply a more even force to the band55.

The bolt105passes through the first washer block70, the band55, and the reaction blocks60before also passing through the second washer block70. The nut100engages the bolt105and facilitates the tightening of the clamp25. In another construction, the second washer block includes a threaded bore sized to receive the bolt, thereby eliminating the nut100. In yet another construction, the first and second washer blocks both include threaded bores. However, the threads are of opposite hand (e.g., the first washer block has left hand threads and the second washer block has right hand threads). A threaded stud engages both washer blocks such that rotation in one direction (e.g., clockwise) pulls both washer blocks toward one another to facilitate clamping, while turning the stud in the opposite direction moves the washer blocks away from one another and loosens the clamp.

The exhaust clamp25, when in the unclamped configuration, fits within a recess140provided on the outside pipes35. The stub portions50of the inside pipes45extend into the outside pipe35. The inside pipes45and outside pipes35in some constructions may include relief slots (not shown) that allow the pipes45to collapse slightly under the compressive force applied by the clamp25.

Once the inside pipe45is positioned within the outside pipe35the exhaust clamp25is tightened to form a seal therebetween. As the clamping member65is tightened (e.g., the bolt105is turned) the lobes75are reduced in size and the narrow area between the lobes75becomes more narrow. As the narrow area narrows, the wedge surfaces115of the reaction blocks60cooperate with one another to apply a clamping force to the pipes35,45. The clamp25is tightened until each outside pipe35is compressed into sealing contact with the corresponding inside pipe45.

FIG. 5illustrates an alternate construction of the clamp25A including another construction of the reaction blocks60A and a band55A formed from two pieces rather than one continuous piece. The reaction blocks60A are truncated wedge-shaped members that include two arcuate side surfaces150shaped to engage the pipes35and a third surface155shaped to engage the inside surface80of the band55A. In the construction ofFIG. 5, the third surface155is flat. However, other constructions having a different band may employ an arcuate surface to facilitate proper engagement of the reaction blocks and the band. For example, reaction blocks for use with the band55illustrated inFIGS. 3-4would preferably include an arcuate surface that abuts the inside surface80of the band55.

The apex of each reaction block60A opposite the third surface155is removed to provide a flat top surface160. When the clamp25is tightened too far, the top surfaces160contact one another to prevent over tightening of the clamps25and resultant damage to the pipes35,45.

The arcuate surfaces150of the reaction blocks60A cooperate with the inside surface80of the band55A to define the two lobes75. Each lobe75substantially surrounds one of the outer pipes35and provides an even clamping force when the clamp25is tightened.

The construction ofFIG. 5includes two U-shaped members165that attach to one another to define the band55A. Other constructions employ two pieces that are W-shaped such that they attach to one another at the outermost point of each lobe75to define a complete band. In still other constructions, three or more pieces are assembled to define the band.

It should be noted that the reaction blocks60and reaction blocks60A described herein included arcuate surfaces110,150that engage the pipes35and assist in distributing the clamping force on the exhaust pipes30over a larger area. Spreading the clamping force reduces the chance of crushing the exhaust pipes30and/or denting the exhaust pipes30due to stress concentration applied by the clamp25. Alternate constructions may employ reaction blocks that do not engage the pipes35but instead rely on the band55alone to provide the force necessary to clamp the pipes35,45.

It should be understood that the exhaust clamp25of the invention can be used to connect any two pipes in the manner just described. Therefore, the invention should not be limited to the specific connection illustrated herein, nor should the invention be limited to motorcycles10.

Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.