Bellows-Type Spring Seal

1. Technical Field

This invention relates to a novel means for coupling, sealing, and aligning a cab mounted air intake pipe to a frame mounted air cleaner canister while providing an economical and effective breakaway joint. More particularly, the invention relates to a bellows type spring seal to connect the air cleaner canister to an air intake pipe mounted on a cab-over-engine truck.

2. Background Art

As illustrated in FIGS. 1 and 2, a commonly employed means to connect an air intake pipe 10 mounted on the cab 14 of a cab-over-engine truck to an air cleaner canister 20 mounted to the frame is to seat a bell housing 12 on the pipe 10 with a flared sealing end 25 of an extender pipe mounted above the canister 20. To position the flared sealing end 25, a rubber elbow 24 and metal elbow 23 project rearwardly, while the air intake pipe 10 is a straight section of pipe mounted with brackets 13 to the rear of the cab 14. A leaf spring support bracket 22 attach the elbows 23 and 24 to the frame 27, but take up space on the frame which could be better used for mounting fuel tanks, battery boxes, and other necessary equipment. The bracket 22 and elbows 23 and 24 also represent excessive weight. Changing the air cleaner is complicated because the bracket and elbows 23 and 24 must be removed to lift the cover from the canister 20. Finally, the bracket 22 does not allow self-alignment for the seal in the plane perpendicular to the air intake pipe 10. When assembled on the production line, a final adjustment must be made once the cab 14 is placed on the frame 27. While in use, the sealing end 25 and bell housing 12 can become misaligned.

U.S. Pat. No. 2,925,874 (Norrie) discloses an exhaust stack for tilting cab vehicles which uses a system similar to that just discussed for the pripr art air intake. Yet another exhaust system is disclosed in U.S. Pat. No. 3,173,710 (Kinnison); however, the sealing means used therein is much more complex than it need be. The metal-to-metal seals required for the heated exhaust gases increase the complexity if minor vertical misalignment or rocking motion is to be accommodated. Kinnison requires extensive modifications to otherwise commonly available pipes to make his metal-to-metal seals. Machining to high tolerance is also required.

U.S. Pat. No. 3,151,695 (Mintz) discloses an air cleaner seal for tilt cab vehicles whereby an elastomeric bellows seals around the top of an air cleaner canister with magnets. With weight becoming an ever increasing concern in vehicles, canister tops may soon be made of nonmagnetic material, such as plastic. To use magnetic connection requires that the diameter of the bellows are considerably larger than the top of the canister. Once the magnets hit the metal top, they stick. Therefore, to have adequate self-aligning capacity, the bellows is wide. Furthermore, to attach the bellows, the air intake pipe must be modified. Because the seal comes primarily from the flex in the bellows, the seal is likely to fail within a relatively short time as the elasticity of the bellows deteriorates. Finally, the wide bellows creates an orifice which restricts flow and which produces an undesirably large pressure drop. The pressure drop may impair engine performance.

Various other connectors are known, although they appear to be less relevant to this invention due to their environment of use and complexity. These patents include:

U.S. Pat. No., 3,490,792

U.S. Pat. No., 3,815,941

U.S. Pat. No., 4,072,329

U.S. Pat. No., 2,922,663

U.S. Pat. No., 3,319,979

A novel bellows-type spring seal of this invention provides an effective breakaway joint and significantly improves the air cleaner canister and air intake pipe system in a number of ways. First, the cumbersome and heavy leaf spring and bracket commonly employed to support the air intake pipe are eliminated. A more positive seal is attained with elastomeric sealing surfaces and positive sealing pressure. The flexible bellows provides better self-aligning capability both vertically and horizontally. Replacement of the air filter is greatly eased because the obstruction of the bracketry is removed. Airflow is relatively unrestricted because the bellows forms an extension of the air intake tubing.

The bellows-type spring seal of this invention includes a bellows which has an upper sealing end. The bellows connects between an air intake pipe mounted on the cab and an air cleaner canister mounted on the frame. The lower end of the bellows is fastened with suitable means to the neck of the canister top. To maintain a positive preload on the seal, a means is provided for biasing the sealing end of the bellows away from the canister. Preferably, the biasing is obtained by equidistantly spaced coil springs between the canister top and the underside of the sealing end of the bellows.

FIG. 1 is a side elevation of a prior art technique for connecting an air intake pipe to an air cleaner canister.

FIG. 2 is another side elevation of the prior art with the cab raised to show how the joint breaks away.

FIG. 3 is a side elevation showing the bellows-type spring seal of this invention.

FIG. 4 shows the bellows-type spring seal from the rear of the cab looking forward.

FIG. 5 is a side elevation showing how the bellows-type spring seal of this invention breaks away.

FIG. 6 is a detail of the bellows-type spring seal of this invention.

FIG. 7 is a view similar to FIG. 6, partially in section.

FIG. 8 is another detail, partially in section, taken along line 8--8 of FIG. 6.

In a cab-over-engine diesel truck (FIGS. 3, 4 and 5) an air intake pipe 10 is mounted with brackets 13 to the rear of the cab 14. The pipe 10 extends upwardly so that fresh air is drawn to the engine. A rain cap 11 keeps precipitation and other material out. The intake pipe 10 sealingly connects with the air cleaner canister 20. The canister is mounted to the frame 27 with mounting bands 21 and a mounting bracket 26 (FIG. 4). A series of elbows 16 and couplings 15, some being elastomeric and flexible, form the necessary tubing to match the canister 20 and intake pipe 10. These pieces are attached to the cab through a mounting bracket 17.

The sealing connection is accomplished with a bellows-type spring seal 100 which forms the basis of this invention. As best seen in FIGS. 6, 7 and 8, the preferred bellows-type spring seal comprises a bellows 102 which has an upper sealing end 104 that is sized to mate with the standard bell housing 12 of the air intake pipe 10. The bellows 102 is elastomeric, being made of rubber, synthetic rubber, plastic, rubber-impregnated cloth, plastic-impregnated cloth or another suitable material. Its sealing end 104 usually will be deformable so that when it is pressed against the bell housing 12 of the intake pipe 10, a fluid seal is formed. The bellows 102 provides self-aligning capability for the intake pipe 10 and canister 20. It is able to adjust vertically because it is compressible in the axial direction. It is elastomeric in that it functions as a spring in the axial direction. Thus it may absorb the rocking motion which often develops with a cab-over-engine cab 14. Its flexibility and end shape allow for self-aligning for minor offsets in the horizontal plane.

The lower end of the bellows 102 is attached to the canister top 28 about its neck with suitable means 108, such as a hose clamp. The bellows 102 is an extension of the air intake tubing and does not create a substantial restriction to airflow.

A novel feature of this invention is a means (supplemental to the bellows' elasticity) for biasing the upper sealing end 104 of the bellows 102 away from the canister top 28. Preferably, three coil springs 106 are equidistantly spaced about the periphery of the bellows. Each spring 106 rests on a pin 112 which protrudes upwardly from a ring 114 resting on the canister top 28. The upper end of each spring 106 similarly encircles a pin 110 on another ring 116. The pins 110 and 112 function to position the springs 106. Each spring 106 exerts an upward preload force of about 90 pounds on the underside of the sealing end 104 of the bellows 102. This force helps to keep a fluid seal between the sealing end 104 and the bell housing 12 of air intake pipe 10. Other means to provide a uniformly distributed preload force on the sealing end 104, such as a single coil spring encircling the bellows or a plurality of independent coil springs, may be used.

A bellows-type spring seal of this construction reduces many of the problems found in prior art seals. It allows use of standard materials presently available. The seal 100 is easily manufactured. It has no welded parts. Various parts are easily replaced when worn. The seal 100 is simple, yet effective and economical in providing a breakaway joint.

Those skilled in the art will recognize numerous modifications to the bellows-type spring seal which is shown and described. These modifications are considered to be part of this invention. Therefore, the invention should be limited only if such limitation is necessary because of the prior art or the nature and spirit of the appended claims.