1. Field of the Invention
This invention relates generally to air pressure gauges for pneumatic tires and, more specifically, to a compact air pressure gauge assembly mountable to a valve stem of a tire or mountable through the rim of a wheel for continuous monitoring of the tire inflation pressure.
2. Description of the Prior Art
Proper tire inflation is important for fuel economy of a vehicle and prolongs the life of a tire. By maintaining proper tire inflation, optimum performance of a vehicle can be reached while keeping the operating costs relatively low and the safety relatively high. Under inflation of a tire can cause excessive wear of the tire, tire failure, loss of fuel economy, excessive engine drag, increased emissions, and depletion of fossil fuels.
In general, the air pressure of a tire is checked by removing a cap from a valve stem, applying a pressure gauge to the valve stem to get a pressure reading, and replacing the cap onto the valve stem. While inflating the tire to reach a desired air pressure, the pressure gauge needs to be applied to the valve stem several times alternating between inflating the tire with an air pump or the like and checking the air pressure by applying the pressure gauge to the valve stem. This procedure is inconvenient and time consuming.
In order to simplify this process air pressure gauges mounted directly to a tire valve stem have been developed, for example U.S. Pat. No. 4,924,697 issued to Hunt et al. and U.S. Pat. No. 5,377,539 issued to LaSalle. These prior art air pressure gauges monitor and indicate the tire inflation pressure continuously. However, using valve stem extenders for mounting these prior art gauges cause them to extend relatively far out of the tire valve stem. This might cause a problem since devices that extend the valve stem may influence the balance of the wheel.
While LaSalle illustrates an air pressure gauge that does not interfere with the tire inflation through the valve stem and also monitors the air pressure while inflating the tire, Hunt et al. provides an air pressure gauge that still needs to be removed for inflating of the tire. Still both prior art air pressure gauges are connected to the tire valve stem and are driven by the air coming through the valve stem. This can cause a problem while replacing the tire and/or the valve stem.
Further, the air pressure gauge illustrated by LaSalle shows the air intake leading through the chamber housing a pressure indicator or sensing element, which can interfere with the function of the indicator or sensing element.
Also, if a prior art pressure gauge is accidentally broken off or fractured, air may leak causing hazardous deflation of the tire. Moreover, depending on the tire positions, prior art air pressure gauges may be hard to read.
Therefore a need existed to provide an air pressure gauge assembly mountable to a valve stem of a tire or mountable through the rim of a wheel and having a compact design.
A further need existed to provide an air pressure gauge assembly that barely extends the valve stem or wheel rim in order to avoid curb contact and interference with the wheel balance.
A still further need existed to provide an air pressure gauge assembly that allows for the continuous monitoring of the tire pressure, is easy to read, indicates a warning for lower than normal air pressure, and therefore eliminates the use of an external handheld air pressure gauge.
A still further need existed to provide an air pressure gauge assembly that does not interfere with the function of the tire valve stem.
A still further need existed to provide an air pressure gauge assembly that has the air intake separate from the chamber housing a pressure indicator or sensing element.