Measuring and testing – Tire – tread or roadway – Tire inflation testing installation
Reexamination Certificate
2000-03-10
2002-04-23
Oen, William (Department: 2855)
Measuring and testing
Tire, tread or roadway
Tire inflation testing installation
Reexamination Certificate
active
06374666
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the fields of tires and tire pressure gauges. More specifically the present invention relates to an air pressure gauge apparatus which is combined with a tire valve stem to remain on the stem and continuously display the tire pressure, so that at any moment the user can see at a glance whether the tire is properly inflated, and thus know at a glance whether the tire is safe and providing optimum tire wear and fuel efficiency. The gauge apparatus preferably is combined with the valve stem either by screwing it onto existing external cap threads of the valve stem and letting it remain attached until momentary removal during tire inflation, or by integrating it permanently into the structure of the valve stem during stem manufacture.
The essential elements of the apparatus include an apparatus housing, containing a received air chamber for placement in fluid communication with received air from within a vehicle tire and containing a biasing air chamber containing a fixed quantity of biasing air, the chambers being sealingly separated from each other by a pressure equilibration structure which includes a pressure indicator element. The pressure equilibration structure moves within the housing to alter the relative volumes of the two chambers and thus to equalize the pressures of the two chambers. The pressure indicator element moves relative to the apparatus housing as the equilibration structure moves to equalize chamber pressures to display a tire pressure reading. The gauge apparatus operates on the principle of continuous re-establishment of pressure equilibrium, where alteration of received air pressure from outside the apparatus, that is, from within the tire, causes movement of the pressure equilibration structure within the housing against the trapped, fixed quantity of biasing air sealed within the biasing air chamber, thereby moving the indicator structure to reveal the pressure reading. The biasing air functions as a fixed standard against which varying tire pressure is measured.
2. Description of the Prior Art
There have long been gauges for measuring the pressure of air contained within vehicle tires. All of these prior gauges have relied on springs to provide biasing against which a pressure reading is taken. A problem with such prior gauges is that springs can lose resiliency, can corrode, and can add cost and complexity to the gauges.
These prior, spring biased -gauges include Parker, U.S. Pat. No. 4,310,014, issued on Jan. 12, 1982 for a tire pressure indicator integral with a tire stem; Yabor, U.S. Pat. No. 4,901,747, issued on Feb. 20, 1990 for a tire inflation valve with a pressure indicator; Hunt, et al., U.S. Pat. No. 4,924,697, issued on May 15, 1990 for a tire-mounted air pressure gauge assembly; Huang, U.S. Pat. No. 5,014,643, issued on May 14, 1991 for a tire pressure indicator; Rabizadeh, U.S. Pat. No. 5,503,012, issued on Apr. 12, 1996 for a tire pressure monitoring device; Cummings, U.S. Pat. No. 5,569,849, issued on Oct. 29, 1996 for a visual tire cap pressure gauge; Wang, U.S. Pat. Np. 5,856,619, issued on Jan. 5, 1999 for a tire pressure indicator; Halcomb, U.S. Pat. No. 5,979,232, issued on Nov. 9, 1999 for a tire pressure indicator carried aboard a wheel; Chi, U.S. Pat. No. 5,886,254, issued on Mar. 23, 1999 for a tire valve pressure-indicating cover utilizing colors to indicate tire pressure.
On the other hand, Wong, U.S. Pat. No. 4,384,543, issued on May 24, 1983, discloses a air release check valve and indicator device which automatically releases air from an over-inflated tire. A critical problem with Wong is that the device is inoperative, for multiple reasons. First, air from within a tire stem bearing against the piston
19
cannot move piston
19
because its pressure is opposed by equivalent air pressure entering the piston cylinder
16
through port
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. Thus the piston will not move no matter what tire air pressure is introduced into the device housing, and the device cannot function either as a pressure relief valve or as a pressure indicator. Nor can Wong receive air from an air line to fill the tire. Air entering Wong would have no way of moving the piston shaft to place its narrower segment within the partition aperture.
None of the displaceable, pressure measuring structures within the known prior art gauges are at equilibrium and at rest prior to installation on a tire. All have set points above atmospheric, unlike the gauge embodiments of the present application:
It is thus an object of the present invention to provide a tire gauge apparatus which relies on pressure equilibration rather than on a mechanical spring to produce a tire pressure reading.
It is another object of the present invention to provide such a gauge apparatus which remains on the tire and produces an accurate and easily visible tire pressure reading.
It is still another object of the present invention to provide such a gauge apparatus which can be integrated into a valve step during manufacture.
It is yet another object of the present invention to provide such a gauge apparatus which is initially at equilibrium with the atmosphere, is always active, which measures both under- and over-inflation, which can be constructed with a thin pressure responsive membrane with no elastic force constant, and does not rely on pre-set valves.
It is finally an object of the present invention to provide such a valve stem which is highly economical to manufacture, simple in design, light weight, compact and highly durable.
SUMMARY OF THE INVENTION
The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.
A tire pressure gauge apparatus is provided for securing to a vehicle tire valve stem mounted to a tire valve stem port in a vehicle tire, the valve stem including a tubular stem body containing a valve assembly having a valve opening mechanism, the stem body having a stem connection end fitting sealingly to the tire valve stem port, and having a stem air receiving end, the apparatus including a housing for placement in fluid communication with received air from within the tire contained within the tire valve stem; a structure for opening the valve opening mechanism;
and a pressure equilibration structure dividing the housing into a received air chamber and a biasing air chamber and including a pressure indicator element, the pressure equilibration structure and the pressure indicator element being movable relative to the housing, and the pressure indicator element displaying a pressure reading of received air from within the tire which varies with the position of the pressure equilibration structure relative to the housing; so that alteration of the pressure of received air within the received air chamber from the valve stem causes movement of the equilibration structure within the housing to re-establish pressure equilibrium between biasing air sealed within the biasing air chamber and received air within the received air chamber, and movement of the equilibration structure causes the indicator element to move relative to the housing to provide a received air pressure reading.
A tire pressure gauge apparatus is further provided for securing to a vehicle tire valve stem mounted to a valve stem port in a vehicle tire, the valve stem including a tubular stem body containing a valve assembly having an outwardly biased valve opening shaft, the stem body having a stem connection end with a circumferential groove for fitting sealingly into an edge of the tire valve stem port, and having a stem air receiving end having external threads for affixation of a valve stem cap and having internal threads into which the valve assembly is screwed, the apparatus including a housing for placement in fluid communication with received air from within the tire contained within the tire valve stem; a structure for depressing the valve opening shaft and thereby opening the valve assembly, the
Anthony Michael M.
Lemberger Gary
Aw-Musse Abdullahi
Oen William
Oltman Flynn & Kubler
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