Adjustable Control Valve Stem

Abstract

A pneumatic control device is provided designed to work with self-inflating inner tubes and tires, specifically for bicycles or wheelchairs. The device distinguishes a stem assembly and an air control assembly. The device allows users to set a desired pressure and maintains that constant pressure over time, thereby eliminating the need to manually re-fill the tires. The device is compatible with current rims and tires and requires no modification to be installed to existing rims. The device works by regulating the intake of air from the atmosphere into the self-inflating pumping mechanism. Once the desired pressure is reached, the system stops new air from entering the self-inflating mechanism.

Claims

1. A pneumatic control device to control pressure designed to work with self-inflating inner tubes and tires, comprising: (a) a stem assembly adapted to be mounted through a rim of a wheel, wherein the stem assembly comprises a stem with an air passage through the stem from the top end to the bottom end of the stem, and a tubing assembly adapted to fit within the air passage of the stem; and (b) an air control assembly adapted to be pneumatically mounted to the top of the stem assembly, wherein the tubing assembly has a first passage for air to enter and exit the inner tube or tire, and a second passage to activate the air control assembly, and wherein the air control assembly comprises a user-adjustable air pressure adjuster.

2. The pneumatic control device as set forth in claim 1, wherein the pneumatic control device is compatible with a rim for a Presta fitting or a Schrader fitting.

3. The pneumatic control device as set forth in claim 1, wherein the pneumatic control device is for a bicycle tire or inner tube.

4. The pneumatic control device as set forth in claim 1, wherein the pneumatic control device is for a wheelchair tire or inner tube.

5. The pneumatic control device as set forth in claim 1, wherein the pneumatic control has markings or indicators for indicating air pressure.

6. The pneumatic control device as set forth in claim 1, further comprising a removable cap with an air filter adapted to be affixed to the valve core.

7. The pneumatic control device as set forth in claim 1, wherein the air control assembly comprises a check ball has a diameter of about 2-5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a pneumatic control device according to an exemplary embodiment of the invention/

[0024] FIG. 2 shows according to an exemplary embodiment of the invention an exploded view of the pneumatic control device shown in FIG. 1. In FIG. 2, the following elements are shown: 1. a cap, 2. a valve core, 3. a valve core spring, 4. an air pressure adjuster, 5.

[0025] an air pressure selector spring, 6. a check ball, 7. a spring guide, 8. a housing seal 9. a housing, 10. a ball seat, 11. a stem, 12. a tubing assembly, 13. a first tubing, 14. a second tubing

[0026] FIG. 3 shows according to an exemplary embodiment of the invention the pneumatic control device similar as shown in FIG. 1 indicating a first air passage way tubing 13 where air from the inner tube or tire can be passed and pneumatically act onto check ball 6, and a second air passage way tubing 14 where air from the atmosphere can be drawn into the inner tube or tire via part of the spring guide 7 and through the air passage way of stem 11.

[0027] FIG. 4 shows according to an exemplary embodiment of the invention a modified cap 1 compared to the cap shown in FIG. 1. Cap 1 has a support base 15 for the cap and a filter 16 within support base 15.

DETAILED DESCRIPTION

[0028] An embodiment of the invention is a pneumatic control device designed to work with self-inflating inner tubes and tires. In its most basic form the device is able to fulfill the following functions: [0029] 1) Allows the tire to be inflated with a compressed air source attached to the valve stem. [0030] 2) Regulates the pressure in the tire by stopping air from the atmosphere from entering the tire. [0031] 3) Allows the air to be discharged from the tire from the valve stem.

[0032] Each of these three functions is important. The tire must be able to be inflated when initially mounted to the rim and the tire must be able to be deflated to dismount the tire from the rim.

[0033] In addition to the basic form, the device may perform some or all of the following functions: [0034] 1) Filter the air before it enters the tire. [0035] 2) Offer the user the ability to set the desired pressure within a range. [0036] 3) Be serviceable by the user. [0037] 4) May be mounted on Schrader and Presta compatible rims without modification. [0038] 5) May exhaust compressed air from the tire to regulate pressure, although this is not the preferred regulation method. [0039] 6) May use a check valve core assembly found in industry to reduce manufacturing cost, engineering time and increase reliability and serviceability.

[0040] The device differs from a typical valve stem in that the device has two air passageways through the valve stem. One passage way is for air to enter and exit the tire. The other passage way is to activate a control valve. In the current embodiment of the invention, air pressure from the main chamber of the tire pushes up on the check ball stopping new air from the atmosphere from entering the valve stem.

[0041] In this disclosure, we speak of tire pressure for the sake of simplicity and we do not differentiate between air entering the inner tube or air entering the tire. We do not differentiate between inner tube pressure and tire pressure knowing that the device may be applied equally to pneumatic tires that use inner tubes and pneumatic tires that do not use inner tubes.

How the Device is Attached to a Wheel

[0042] The device is easily mounted to the rim by pushing the stem assembly through the rim and then screwing on the air control assembly to the stem The stem assembly distinguishes elements 11-14. The control assembly distinguishes elements 1-10.

[0043] In one embodiment, the stem assembly passes through the hole in the rim placed there for a typical valve stem. The air control assembly is then screwed down on to the stem assembly. The stem assembly is held fixed to the rim either by the air control assembly pushing against the rim or an optional nut, which would fix the stem assembly to the rim. At this point the tire can be inflated with a compressed air source. Approximately 1 bar minimum pressure is needed to stabile the tire on the rim and enable the bicycle to be ridden. The tire could also be inflated to the desired pressure at this point. The last step is to adjust the air control assembly to the desired pressure.

Setting the Tire Pressure

[0044] Turning the air pressure adjuster 4 sets the tire pressure. The maximum set pressure is achieved when the pressure adjustor is screwed down to its lowest point. The minimum set pressure is achieved by unscrewing the pressure adjuster to its highest point. Markings may be included on housing 9 to indicate the pressure settings. Markings may be indicators such as lines, geometric shapes, dots, arrows or other figures. Units may include general indicators such as higher or lower or may be in pounds per square inch (psi), bar or other recognized units. Markings may be monochrome or color-coded.

Pressure Range and Precision

[0045] An advantage of the device it that different springs can be used to optimize the adjustment range and precision for different riders and applications. For example an urban commuter bike could be optimized for both heavy and light loads by incorporating a wide range of pressures. With a heavy load or heavy rider, the tires might perform best at 4 bar pressure. With a light load or light rider, the tires might perform best at 3 bar pressure. For this application, a spring could be chosen that regulates the pressure from 2.5-4-5 bar with an error range of +/0.25 bar. In another application the spring could be exchanged with another to regulate within a smaller range, but with much greater precision. For example the range of pressure regulation could be reduced to 4.0-4.5 bar with an error range of +/0.10 bar. For certain applications precision will take precedence over range and vice versa. The current embodiment is designed for the urban commuter and has an adjustable pressure range of 2.5-4.5 bar.

Digital Pressure Monitoring

[0046] The device may have an electronic pressure monitoring means. For example a battery powered pressure monitor may be included in the system and may transmit the data via Bluetooth or other electrical means to a receiver on the bicycle. This would create a means for users to be able to easily verify the pressure in their tires and be informed if the tire pressure moves outside of a desired range. Such stand-alone monitoring systems are already available for bicycles, motorcycles and automotive use. The electric pressure monitoring means may be located within the tire or may be located outside the tire on the valve stem.

Materials

[0047] Pneumatic valves have been refined over many years and are currently made of a variety of materials to optimize for specific applications. The bicycle industry is very weight sensitive and lightweight plastics, rubbers, metals, resins and composites could be used. For example valve stems are typically made out of steel, brass and other metals due to the range of stresses and impacts they must withstand. In the current design, there is great flexibility in the material choice for the housing, air spring guide and other components. The elements of the device could be made from metal, plastic, rubber, resins, composites, alloys, carbon fiber or any other material available.

Check Ball Design

[0048] One of the aspects of the design that enhances performance and precision is the large size of the check ball. Generally speaking, a larger check ball enhances the operation of the valve as it permits more airflow through the valve improving valve performance. A larger check ball allows for spring design with lower stress and a more advantageous spring index. A larger check ball minimizes the effects of manufacturing tolerances resulting in more predictable performance and therefore lower hysteresis between the open and closed positions.

Mode of Operation

[0049] The adjustable control valve has two modes of operation. In the first mode, the adjustable control valve allows air from the atmosphere to enter through the valve stem and into the main chamber of a bicycle tire. In the second mode, the adjustable control valve limits at least partially the flow of air from the atmosphere into the main chamber of the bicycle tire.

[0050] In the first mode, when the wheel is at rest the pressure from the main chamber of the tire pushes against the first check valve. The first check valve is located in the valve core. The first check valve stops the pressurized air from escaping out of the tire. When the self-inflating means is activated, usually by riding the bike and putting a load on the tire, the self-inflating means draws a vacuum, which reduces the air pressure in the valve stem to below atmospheric pressure and opens the first check valve. The first check valve may employ a spring to positively keep the first check valve in the closed position. Air from the atmosphere is pulled through the first check valve all the way through the base and into the pumping mechanism where it is forced into the main chamber of the tire.

[0051] In the second mode, the pressure in the main chamber of the tire exceeds the set pressure of the adjustable control valve stem. This usually occurs when the self-inflating means is activated. The pressure from the main chamber of the tire exceeds the spring force of the pressure selector spring and releases air into the stem assembly. This pressurized air immediately pushes against the first check valve thereby closing it and stopping new air from the atmosphere from entering the stem assembly. The released, pressurized air flows back into the pumping mechanism. If the self-inflating mechanism is active, i.e., pumping, it will recirculate air from the main chamber into the pumping mechanism and not draw new air in from the atmosphere. In this scenario, the pumping mechanism will do no work and no pressurized air is lost to the atmosphere.