Pipe joints or couplings – End to side or plate – Saddle-type clamp
Reexamination Certificate
1999-01-11
2001-05-22
Nicholson, Eric K. (Department: 3629)
Pipe joints or couplings
End to side or plate
Saddle-type clamp
C024S277000, C285S199000, C285S420000
Reexamination Certificate
active
06234541
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to conduit clamps. More particularly, the present invention relates to U-bolt clamps for use in association with exhaust systems.
BACKGROUND OF THE INVENTION
Automotive, truck and other vehicular exhaust systems typically include conduit for directing exhaust gas from an engine to a remote location. Such exhaust systems often include a muffler, catalytic converter, resonator, or a combination thereof for treating the exhaust gas before it is discharged to the atmosphere. To accommodate various design criteria, exhaust gas systems usually include several exhaust conduits, tubes, hoses or pipes of various shapes and lengths which are connected together to form a fluid path for the exhaust gas.
The most common way of interconnecting consecutive conduits is to utilize a lap joint. To make a lap joint, one end of a first conduit is inserted within an end of a second conduit. The conduits are then clamped at the region where the conduits overlap. A typical clamp functions to crush, crimp or otherwise deform the outer conduit against the inner conduit. The ends of the outer conduit typically include a plurality of longitudinal slots spaced about its circumference to facilitate crimping or otherwise deforming the outer conduit against the inner conduit.
It is important that exhaust clamps provide a substantially leak-proof and mechanically secure joint. Any leakage of exhaust at a joint presents a safety hazard because of escaping noxious fumes and a noise problem because of the pulsating nature of the flow through the conduit. Since a number of joints occur in most exhaust systems, it is also desirable that such clamps be inexpensive and relatively easy to install, and if possible, also be relatively easy to disconnect and reinstall.
A variety of clamps have been developed for use in association with lap joints. One common clamp is known as a guillotine or saddle-type clamp. This clamp includes a U-bolt which is mounted on a saddle. The U-bolt includes a concave portion that opposes a corresponding concave portion of the saddle. The saddle and U-bolt are forced towards each other through the use of a pair of nuts that are threaded on the legs of the U-bolt. U.S. Pat. Nos. 2,719,345 and 4,270,689 disclose guillotine or saddle-type clamps configured as described above.
Wide band, leak-proof clamps have also been developed for use in association with lap joints. Wide band clamps are typically designed to surround lap joints and cover all the deformation or take-up slots defined by the conduits forming the lap joints. Various versions of such clamps are illustrated in U.S. Pat. No. 4,629,226 and U.S. Pat. No. 4,558,891.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to a guillotine or saddle-type clamp arranged for effectively and easily sealing a lap joint. The clamp includes a saddle member having an inwardly facing concave saddle portion, and a U-bolt mounted on the saddle member. The U-bolt has an inwardly facing concave portion that opposes the saddle member concave saddle portion. At least one curved shim is positioned (when assembled) between the U-bolt and the saddle member. The shim preferably is wider than either one of the U-bolt and the saddle member. Consequently, the shim cooperates with the U-bolt and the saddle member to more effectively surround and seal a lap joint.
The present invention provides numerous advantages over the prior clamps discussed above. For example, when using a conventional guillotine or saddle-type clamp at a lap joint, it can sometimes be difficult to achieve uniformly leak-proof joints because of the narrowness of such clamps. Specifically, when a conventional guillotine clamp is used at a lap joint, it can be difficult to completely cover and seal the longitudinal deformation slots formed at the ends of the exhaust tubing being connected. This problem is overcome by the present invention. Specifically, one aspect of the present invention teaches using a relatively wide shim in combination with a U-bolt and a saddle member to effectively and easily seal a lap joint. Furthermore, an effective seal can be achieved without requiring high installation torque that damages the exhaust tubing being sealed. Consequently, the clamp can easily be removed to allow the sealed joint to be taken apart for service and maintenance.
Another problem relating to existing guillotine-type clamps relates to corrosion. Specifically, conventional U-bolts and saddle members are typically made of zinc-plated cold rolled steel. By contrast, exhaust pipes and mufflers are typically made of aluminized steel. Consequently, when a zinc-plated guillotine clamp is clamped on a aluminized steel pipe or muffler, galvanic action between the clamp and the pipe or muffler causes premature corrosion of the pipe or muffler. To overcome the aforementioned problem, an aspect of certain preferred embodiments of the present invention relates to the preferable use of a shim with desirable galvanic properties to separate or insulate a U-bolt and saddle from a structure being clamped. The shim is preferably made of the same material as the structure being clamped, or is coated to inhibit galvanic action. Consequently, galvanic action between the tube/conduit structure being clamped and both the U-bolt and the saddle is inhibited. Although corrosion may occur on the outside of the shims where the shims engage the U-bolt and the saddle, unlike typical exhaust pipes or mufflers, the shims are preferably sufficiently thick to withstand substantial corrosion without experiencing significant adverse effects.
The present invention also provides advantages over conventional wide-band clamps. For example, while wide-band clamps are suitable for sealing lap joints, such clamps are not readily adapted for securing an exhaust conduit to structures of a vehicle. Hence, while such wide-band clamps can be used at lap joints, additional clamps, such as guillotine-type clamps, have generally also been required to effectively secure exhaust tubing to a vehicle. In contrast, a further aspect of the present invention relates to clamps capable of effectively sealing lap joints while concurrently providing means for securing exhaust pipes to a vehicle. Moreover, certain clamps constructed in accordance with the principles of the present invention are adapted for inhibiting localized tube/conduit deformation such that lap joints sealed by such clamps can easily be disassembled. Furthermore, clamps constructed in accordance with the principles of the present invention are adapted for effectively sealing lap joints having “captured slots” as disclosed in U.S. Pat. No. 4,113,289.
A variety of additional advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description or may be learned by practicing the invention. It is to be understood that neither the foregoing general description nor the following detailed description is restrictive of the invention as claimed.
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Herman John T.
Protas Michael J.
Shields James P.
Wagner Wayne M.
Donaldson & Company, Inc.
Merchant & Gould P.C.
Nicholson Eric K.
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