Resilient tires and wheels – Tires – resilient – Inflating devices
Reexamination Certificate
2000-02-03
2001-12-04
Morano, S. Joseph (Department: 3617)
Resilient tires and wheels
Tires, resilient
Inflating devices
C152S415000, C152S427000
Reexamination Certificate
active
06325124
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to rotary couplings for mounting on wheels of a motorized vehicle to communicate the pressurized air of the tires with a pneumatic system installed inside the vehicle to control and calibrate the pressure of the tires, compensating eventually for slight leaks by supplying air from a compressed air source, typically a compressor system. These couplings provide the pneumatically sealed connection between the installation considered as static and the rotary part, which as well can be affected by other relative movements such as vibrations.
The present invention also concerns a method to detect wear and tear in wheel bearings to prevent catastrophic faults on the wheel mounting at the end of the vehicle's axle.
BRIEF DESCRIPTION OF THE PRIOR ART
In large and medium-sized vehicles, either passenger or cargo, it is of particular importance to control the pressure of the tires whilst on the road, due to the serious consequences an accident, caused by a flat tire, may bring upon when travelling at high speed and/or when other vehicles are on the road. For some years now it is standard to install pneumatic control and pressure compensating systems in these vehicles, that make use of the onboard compressor of the brake system to correct deficiencies detected in the air pressure of the tires. To this purpose, the referred system includes an air pipe connected to the tire intake valves.
The use of rotary couplings in these pipes is known to solve the sealing between the wheel's rotary movement and the chassis or vehicle's fixed parts. The static installation conventionally includes a pipe section fixed to the vehicle's body, typically the mudguard, that is linked axially to the external end of the rotary coupling attached to the wheel's hub. Argentine patent No. 231,948 and patent application Ser. No. 316,897 disclose rotary couplings in which the air connection with the static part is carried out on the external end of the coupling's stem or rotor. The term “external” is used herein in relation to the vehicle's chassis or body, that is the connection is arranged on the outer side of the wheel.
This system is of relative simplicity and does not affect the mounting of the wheel on the axle's end. But it suffers from the drawback of exposing the sealed connection and coupling to knocks that may occur against road curbs or other hard objects or from damages due to slight accidents with things or other vehicles, that may render useless the system on the wheel in question. The system is susceptible to vehicle's vibrations whilst in motion, the movement of the axle's suspension relative to the body, the outdoor weather conditions, the air friction that subjects the system to mechanical and dynamic thermal forces of magnitude and varied oscillations that may limit the useful life of the system, as it is exposed for example in Argentine patent P970105,633.
Also known in the art is the “Meritor” system from Pressure Systems International, Inc., U.S. Pat. No. 5,584,949, which makes use of the hollow axle that most North American and European automobile brands use for mounting the wheels, continuing the air pipe inside the vehicle's axle and arranging an inward axial end connection to the rotor's stem. This system has the advantage of not exposing the pipe and rotary coupling as in the other case but presents other drawbacks, such as small air leaks that build up excessive pressure on the wheel's bearing mountings at the end of the vehicle's axle. This excessive pressure deteriorates the bearing seals and pushes the lubricant grease out of them, diminishing its useful life. This situation worsens when the rotary coupling's seals are worn out, which is generally detected only after some time when the leakage is of certain magnitude, forcing the vehicle's bearings to run dry and eventually break down.
As it happens, none of these systems allow one to diagnose substantial wear of bearings, enough to produce wheel misalignments and uncentring relative to its axle, increasing the tire's wear and the fuel consumption, and could lead to a fault in the vehicle's axle end. This is of particular importance in the referred “Meritor” system, as it does not provide any form of detecting faults in the bearing of which is part cause of.
SUMMARY OF THE INVENTION
The present invention not only solves the problem of the loss of lubrication in the wheel's bearings due to excessive pressure from the rotary coupling, but as well enables one to diagnose a shift in the bearings position, due to wearing, breakage or fault of one of its components.
An object of the invention is a pneumatic coupling for one or more wheels located on the vehicle's axle end, wherein the vehicle's axle is used for the pipe section of the static installation connected to the rotary coupling, the stem of the coupling being directed inwards into the vehicle's axle.
Another object of the invention is to avoid exposing the wheel's bearings to excessive air-pressures coming from the coupling.
A further object of the invention is to provide a method that allows the detection of certain faults of some magnitude in the wheel's bearings by means of the same rotary coupling of the invention herein.
To attain these and other objects and advantages, a pneumatic coupling is provided that encompasses a body that is mounted to the wheel and inside of which a pressurized air cavity is formed, linked through one or more orifices in the body with the wheel's tubes. In the case of axles with two or more wheels, the body may have as many orifices linking with the tube's inside as tires to control. The body holds a rotatable stem traversed axially by a conduit that leads into a cavity and a rotatable seal to avoid, under normal functional conditions, pressurized air from leaking from the cavity through the interstitial gap between the stem and the body. According to the invention, the coupling's stem has an end that projects from the body to the wheel's plane provided with a nozzle or a connecting device to an air passage that runs inside the vehicle's axle to communicate the tire through the conduit with the air pressure control device. In a convenient form, the connecting device is placed as an axial extension of the vehicle's axle end. As well, in the body of the coupling, a vent orifice is provided to depressurize the side of the seal opposite to the cavity, to protect the wheel's bearings.
In the preferred embodiment, the body encompasses a block provided with means for attachment to the wheel's hub and a cover attached to the block and which presents a cup portion whose edge defines a seat for a plastic bushing that supports the internal end of the coupling's stem. The external surface of this bushing includes grooves that communicate the cavity with the orifice that links with the wheel's tire. The bushing may be formed by a circumferential skirt supporting a main seal placed upon a washer with radial open grooves directed towards the airing orifice to maintain the opposite side of the seal to the cavity depressurized.
According to an interesting accessory feature of the invention, the coupling's stem is mounted with some axial play inside said body, enough to displace the end that leads into the cavity at the other side of the seal. It has been found that this mounting enables monitoring a shift or misalignment of certain magnitude of the wheel's bearings, due to wear or breakage, by detection on a panel of the controlling device of a pressurized air leakage provided by the pipe to the coupling by means of the airing orifice.
REFERENCES:
patent: 3037544 (1962-06-01), Gouirand
patent: 3838717 (1974-10-01), Wolf
patent: 5240039 (1993-08-01), Colussi et al.
patent: 5377736 (1995-01-01), Stech
patent: 5538062 (1996-07-01), Stech
patent: 5584949 (1996-12-01), Ingram
patent: 5762732 (1998-06-01), Chapman
patent: 6105645 (2000-08-01)
Colussi Rafael A.
Vénica N{overscore (e)}stor J.
Bellinger Jason R.
Col-Ven S.A.
Davidson Davidson & Kappel LLC
Morano S. Joseph
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