Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1998-12-30
2001-12-18
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S040000, C073S049000
Reexamination Certificate
active
06330822
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention pertains to the art of methods and apparatuses for leak detection, and more specifically to methods and apparatuses for leak detection on small pneumatic tires, such as those commonly used on riding lawn mowers.
2. Description of the Related Art
The need for detecting leaks in various pneumatic products is well known in the art. In order for a pneumatic tire to function properly, all components must be sealed so that the tire will not leak air and decrease in pressure. Several methods of leak detection exist, and have previously been used to detect leaks in various products. However, using a helium leak detector for detecting leaks in tires before the tires are placed onto a vehicle, is new in the art. Previously, the leaks in the tires were not found until the lawn mower had been assembled and purchased by the dealer or consumer. Once the lawn mower had reached the consumer, it was too late to conveniently repair or replace the leaking tire. In addition, the lawn mower manufacture could not easily determine whether the leak was a defect of the tire, as manufactured by the tire manufacturer, or whether the tire had been subsequently damaged. As a result, the lawn mower manufacturers could not require the tire suppliers to repair or credit the lawn mower manufacturer for the defective tires.
One current testing method involves inflating the tires and then storing them in a warehouse for 48 hours in order to allow leaking tires to decrease in pressure. The tires are then delivered to the assembly line where they are checked for proper inflation pressure before mounting the tire on a lawn mower. This method is capable of detecting gross leaks, a leak that is so large that the tire loses a significant amount of the inflation pressure. However, many tires have much smaller leaks that cannot be detected in this short period of time. These tires continue to leak while in storage and become flat by the time the mower reaches the customer. Another problem with this testing method is the amount of material handling and warehouse space required.
The present invention contemplates a new and improved tire testing apparatus and method. Thus, this invention is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention a new and improved tire testing apparatus includes a robotic arm, a roughing pump, a high vacuum (hi-vac) pump, a spectrometer, first and second vacuum chambers, and a pressure sensor. The robotic arm has a set of pincer-like extensions for gripping the tires. The roughing pump and hi-vac pump create a vacuum in the vacuum chambers. The vacuum chambers have a cylindrical shape, a chamber top, and tubes connecting the vacuum chambers to the spectrometer and the respective pumps. The pressure sensor senses the level of vacuum created in the vacuum chambers by the roughing and hi-vac pumps.
In accordance with another aspect of the invention, the tire is filled with a mixture of air and 10% helium by volume. The tire is then placed in the vacuum chamber and the chamber is sealed with a chamber top and an o-ring. The air is removed from the vacuum chamber by the pumps, and a vacuum is created at around 5.0 millitorrs to 600 millitorrs. A spectrometer detects the level of helium in the vacuum chamber and measures that against the acceptable level, and tells the robotic arm to either place the tire in the rejected conveyor or the acceptable conveyor. The entire process takes about 13 seconds.
One advantage of the present invention is that the leaks in the tires can be detected before they are placed on the lawn mower and sent to the consumers.
Another advantage of the current invention is that the defective tires can be promptly identified and returned to the manufacturer of tires.
Yet another advantage of the current invention is that small leaks which would go unnoticed by previous testing methods, can now be detected before shipping.
Another advantage of the current invention is that the helium leak detection is an extremely sensitive means for detecting leaks.
Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.
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Brookhart Craig
Hawk Homer J.
Setele Thomas
Bennett Timothy D.
Cygan Michael
Emerson Roger D.
Emerson & Skeriotis
MTD Products Inc
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