Tire pressure indicator providing a visual indication of tire pressure

An tire pressure indicator operative to provide a first visual indication if the tire pressure within a tire to which the indicator is coupled is below a first predetermined pressure and a second different visual indication if the tire pressure is above a second predetermined pressure. The indicator includes first and second magnetic members rotatably mounted within a housing that includes a transparent portion. The first magnetic member rotates in response to air pressure applied to a diaphragm that is mechanically coupled to the first magnetic member. The second magnetic member includes portions having first and second visual characteristics that are viewable through a transparent portion. The second magnetic member is cooperative with the first magnetic member to rotatably orient the second magnetic member such that the first or second visual characteristic is visible through the transparent portion.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCHED OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

This invention is directed to a tire pressure indicator that can be readily installed on valve stems of vehicle tires to provide a visible indication when the tire pressure is above or below predetermined limits.

Proper maintenance of tire pressure is important in the operation of a motor vehicle for a number of reasons. First, it is noted that under inflation of vehicular tires is the leading cause of tire failure. Second, the maintenance of proper tire inflation promotes more even tread wear and thus increases the life of the tire. Lastly, a vehicle with properly inflated tires will exhibit greater gas mileage than a vehicle with under inflated tires.

Tire failure is generally caused by overheating which is typically caused by under inflation of the tire and/or by overloading of the vehicle. More specifically, tire heating is caused by the normal flexure of the tire sidewalls and road friction. If the tires are properly inflated, the sidewalls will be stiff and sidewall flexure will be reduced. However, if the tires are under inflated, greater sidewall flexure along with tire heating results. Thus, in the circumstance in which tires are under inflated, overheating and tire failure are more likely to occur.

Various tire pressure measurement devices have been developed to allow the measurement of tire pressure. For example, hand-held tire pressure gauges are well known. The user typically slides such a pressure gauge over the valve stem of the tire until the gauge seals with the value stem so as to minimize the escape of air during the measurement process. Once the gauge has been appropriately positioned, the user notes the pressure value displayed on the gauge. The user then compares the measured value to the tire pressure value recommended by the tire manufacturer to determine if the tire is under inflated. The user must either refer to a manual or other source for this information or commit this value to memory.

Mechanical tire pressure gauges of the above-described type typically require a great deal of user intervention and do not provide a constant and instantaneous indication of whether the tire is under inflated. Tire pressure is often not measured due to the inconvenience associated with the use of typical mechanical tire pressure gauges and consequently drivers are often operating their vehicles on under inflated tires.

It would therefore be desirable to have a tire pressure indicator that may be installed on the valve stem and left in place so as to provide a visual indication that a tire is underinflated.

BRIEF SUMMARY OF THE INVENTION

A tire pressure indicator is disclosed. The tire pressure indicator is coupled to a tire via the valve stem and provides a first visual indication if the tire pressure is below a first predetermined pressure and a second different visual indication if the tire pressure is above a second predetermined pressure. The indicator thus provides motorists with a visual indication if a tire is underinflated.

More specifically, the indicator includes a base having internal threads sized to permit threaded mating of the base with male threads of a conventional valve stem. The indicator further includes a housing having first and second ends, a transparent cover, and first and second rotatable magnetic members rotatably mounted within the housing.

A pressure to linear motion translator in the form of a flexible elastomeric diaphragm is mounted within the housing and is securely retained between the housing and the base. The base includes a threaded opening at one end for threaded coupling to the valve and at least one air passage that extends through the base to permit air pressure in a tire to be coupled to the diaphragm. When the air pressure is below a first predetermined value, the diaphragm is generally undeformed. When the air pressure applied to the base of the indicator is above a second predetermined value, the diaphragm deforms. A linkage arm is provided that is coupled to the diaphragm and a point on the first magnetic member. The application of air pressure above the second predetermined value causes the diaphragm to deform and causes the first magnetic member to rotate from a first rotational orientation in which one magnetic pole is adjacent the second magnetic member to a second rotational orientation in which the other magnetic pole is adjacent the second magnetic member.

First and second colors or first and second visual indicia are provided on the portions of the second magnetic member associated with the north and south poles. Consequently, the rotation of the first magnetic member causes rotational movement of the second magnetic member such that a first colored portion of the second magnetic member is visible through the transparent cover in the circumstance in which the air pressure applied to the base is below the first predetermined value and a second different colored portion of the second magnetic member is visible through the transparent cover when the air pressure applied to the base is above the second predetermined value.

In the foregoing manner, a visual indication of whether the tire pressure is below a first predetermined value or above a second predetermined value is provided.

Other features, aspects and advantages of the invention will be apparent to those of ordinary skill in the art from the Detailed Description of the Invention that follows.

DETAILED DESCRIPTION OF THE INVENTION

The present application hereby incorporates by reference the disclosure of U.S. Provisional Patent Application No. 60/423,867 filed Nov. 5, 2002 and entitled Low Tire Pressure Indicator.

A low tire pressure indicator is disclosed. The low tire pressure indicator provides a first visual indication if the tire pressure is below a first predetermined pressure value and a second different visual indication if the tire pressure is above a second predetermined pressure value. In one embodiment, the first and second predetermined pressure values are the same.

FIGS. 1–3depict a tire pressure indicator in accordance with the present invention. The indicator10includes a base12that engages the threads of a tire valve stem (not shown). The indicator10further includes a housing14having a first end adjacent the base12and a second opposing end. The first end of the housing14is mounted to the base12. The base is preferably metallic but may alternatively be fabricated of plastic. The housing14may be mounted to the base12via an interference fit or alternatively, via an adhesive. A transparent cover or dome16is mounted to or is integral with the second end of the housing14. More specifically, the transparent cover16may be molded from a clear polycarbonate material or any suitable clear plastic material. When molded as a separate component from the housing14, the cover16may be mounted to the housing14via ultrasonic welding, via an adhesive, or any other suitable mounting technique known in the art. The mounting of the cover16to the housing14should provide a seal to avoid the introduction of moisture at the location of the joint between the cover16and the housing14. The transparent cover16and the housing14may also be produced via a two part molding process to produce an integral component having a transparent end. Alternatively, the housing14and cover16may be integrally formed of a transparent material and the housing portion may be partially coated or painted with an opaque coating so that only the cover16is transparent.

One or more air passages18(seeFIGS. 2,3) are provided through the base12. The base12also includes a pin20that impinges upon the valve pin within the valve stem of a tire when the base12is threaded onto the cooperative male threads of the valve stem (not shown). The air passages18open to a flexible elastomeric diaphragm22that is captively retained between the base12and the housing14so as to form a seal between the base12and the interior of the housing14. The diaphragm22serves as a pressure to linear motion translator. While in the illustrated embodiment an elastomeric diaphragm is employed as the pressure to linear motion translator, any device suitable to perform this function may be substituted for the diaphragm. For example, a piston that provides an air seal to the interior of the housing14may be employed in the alternative. Increased air pressure in a tire results in greater deformation of the diaphragm22and urges the center of the diaphragm22away from the base12. A linkage arm24having first and second ends is coupled to the center of the diaphragm22at the first end of the linkage arm. The second end of the linkage arm24is pivotally coupled to a first rotatable magnetic member or actuator26that has opposing north and south poles. The first end of the linkage arm24may comprise a ball which is pressed into a socket formed in the center of the diaphragm22or via any other suitable means. Similarly, the second end of the linkage arm24may be mounted to the actuator26using any technique known in the art for pivotally coupling a member to a rotatable object. For example, the linkage arm24may be coupled to the actuator26via a pivot pin.

The actuator26is rotatable around a first pivot axis28. Increased air pressure applied to the diaphragm22through the openings18in the base causes greater deformation of the flexible diaphragm22which, in turn, causes rotational movement of the actuator26via the linkage arm24. Accordingly, as depicted inFIG. 2when air pressure below a first predetermined pressure is applied to the indicator10, the diaphragm22is not significantly deformed and the actuator26is oriented with the south pole generally adjacent the diaphragm22and the north pole adjacent a second rotatable magnetic member30. The second rotatable magnetic member30also has opposing north and south poles and is freely rotatable about a second pivot axis32. The second rotatable magnetic member30may be fabricated in the form of a generally planar disk or alternatively as a sphere. In either case, different visual indicia are provided on portions of the second magnetic member30associated with opposing poles of the second member30. For example, the portion of the second member30associated with the north pole may be red and the portion of the second member30associated with the south pole may be green. The second magnetic member30is rotatably mounted adjacent the actuator26such that a portion of the second member30is visible through the transparent cover16.

When the air pressure within the tire is below the first predetermined pressure, as depicted inFIG. 2, the north pole of the actuator26is disposed adjacent the second member30. The orientation of the actuator26with its north pole adjacent the second member30causes the south pole of the second member30to be attracted to the north pole of the actuator26, as depicted inFIG. 2. In this orientation, the red portion (north pole) of the second member30is visible through the transparent cover16so as to provide a visual indication of a low tire pressure condition.

FIG. 3depicts the orientation of the first and second members26,30in the circumstance in which air pressure that is in excess of the second predetermined value is applied to the tire pressure indicator10. When the pressure within the tire is above the second predetermined value, the diaphragm22deforms so as to cause the linkage arm24to move away from the base12. The movement of the linkage arm24causes rotational movement of the actuator26around its pivot axis28. More specifically, in response to the application of air pressure to the indicator above the second predetermined value, the actuator rotates so that its south pole is generally adjacent the second member30. The north pole of the second member30is attracted to the south pole of the actuator26causing the second member30to rotate about the second pivot axis32until the north pole of the second member30is adjacent the south pole of the actuator26. In this rotational orientation, the green portion of the second member30is visible through the transparent cover16of the indicator10.

Thus, based upon the color of the portion of the second member30that is visible through the transparent cover16of the tire pressure indicator10, a user can readily obtain a visual indication of whether the tire pressure is below the first predetermined value or above the second predetermined value.

A compression spring34having first and second ends is mounted within the housing14. One end of the spring34abuts a shoulder36formed in the interior surface of the housing14and the other end of the spring abuts the diaphragm so as to urge the diaphragm into its undeflected orientation. The stiffness of the spring34is in part determinative of the first and second predetermined values.

While the first member26is depicted in the form of a disk and the second member30is depicted in the form of a sphere, it should be appreciated that that any suitable rotatable magnetic objects may be used for either of the members26,30. For example, rotatable magnetic disks, cylinders, magnetic spheres, bar magnets, and/or combinations of the above may be employed. Moreover, while the illustrated embodiment describes one orientation of magnetic poles of the magnetic members26,28, the polar orientation of the two members26,28may be reversed without affecting the functionality of the presently disclosed low tire pressure indicator.

Additionally, while the above description is provided in terms of a tire pressure indicator, it should be appreciated that the presently disclosed indicator may be employed to provide a visual indication of whether a fluid pressure is above or below first and second predetermined values.

It will be appreciated that variations to and modifications of the above-described tire pressure indicator may be made without departing from the inventive concepts disclosed herein. Accordingly, the invention should not be viewed as limited except by the scope and spirit of the appended claims.