WO2010141638A1

WO2010141638A1 - Systems and methods for tire inflation and pressure regulation

Info

Publication number: WO2010141638A1
Application number: PCT/US2010/037140
Authority: WO
Inventors: Ian Archibald Paton; Guy Robert Babbit; Christopher Wayne Turner; Christopher Charles Ward; Jacob John Schmidt; Jonathan Jay Lorenzen
Original assignee: Czero, Inc.
Priority date: 2009-06-02
Filing date: 2010-06-02
Publication date: 2010-12-09

Abstract

A tire inflation device according to embodiments of the present invention includes a housing comprising a first opening and a second opening, the first opening in fluid communication with a tire by a first check valve, the first check valve permitting one-way fluid flow from the housing into the tire, a piston moveable within the housing, the piston comprising a first end closer to the first opening and a second end closer to the second opening, the piston further comprising features that operate as a second check valve permitting one-way fluid flow from the second end to the first end, and a non-linear biasing element configured to bias the piston toward the second opening, wherein the housing is mounted on a tire in a position and orientation that causes centrifugal forces generated by tire rotation to act on the piston.

Description

SYSTEMS AND METHODS FOR TIRE INFLATION AND PRESSURE REGULATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 61/183,432 filed on June 2, 2009, which is incorporated by reference herein in its entirety for all purposes.

FIELD

[0002] Embodiments of the present invention relate generally to systems and methods for air delivery to, and regulation of air pressure in, a vehicle tire, and more specifically to the automatic delivery and regulation of the air pressure.

BACKGROUND

[0003] Fuel economy, vehicle safety and tire wear are paramount concerns to automobile manufacturers, legislators, and end users. Improper tire inflation, typically under- inflation, can adversely affect each of these groups. All tires leak and need to have air added to them in order to maintain proper inflation and fuel economy, reduce tire wear, and increase safety. Unfortunately, many automobile operators do not take the time to properly check and inflate their tires. Even those who do so may not be doing it correctly. [0004] Even in the best of circumstances, the pressure of the air inside a tire will cause it to leak to the atmosphere, thereby reducing the pressure if not replenished. There are multiple avenues for air to escape from inside the tire, including leaks in the tire material, which is usually a composite of rubber, steel and synthetic fibers. The leaks could be caused by manufacturing defects, punctures, or, in extreme cases, excessive wear. Air also escapes if the seal between the tire and the wheel, often referred to as the bead, does not seal well. The valve stem with the check valve assembly can leak in the valve itself or where the valve mates with the tire assembly, or inner tube if one is used. Even if all of these leak sources are completely sealed, a tire will lose air (or other gases) as air permeates through the tire material, which is not completely impervious to air. According to some estimates, the average passenger car tire loses approximately one pound per square inch (psi) of pressure per month due to a combination of one or more of these losses.

[0005] Tire wear and durability are also adversely affected by improper tire inflation.

When a tire is under-inflated the tire wears unevenly and excessive heat can build up, potentially leading to catastrophic tire failure.

[0006] Under-inflated tires can cause a car to handle poorly and are a leading cause of tire blow outs, which can result in fatal accidents. Systems which alert drivers to tire under- inflation are quite expensive, do not add air to the tire, and sometimes alert the driver only after safety has been compromised, fuel has been wasted, and/or the tire has been exposed to unnecessary wear.

[0007] Systems also exist that use sensors and electronics to measure the pressure in a vehicle's tire and relay that information to an onboard computer and either let the operator know the status and/or take corrective action by supplying air from an on-board pump or storage device. These systems can be very expensive and are usually only used on specialty vehicles such as military vehicles.

SUMMARY

[0008] Embodiments of the present invention automatically add air to a vehicle's tire if it is under-inflated, thereby maintaining the correct, or near correct, air pressure in the tire. According to some embodiments of the present invention, the centrifugal force from the rotation of the vehicle's tire and wheel cause a piston to travel radially from an inward position with maximum volume to an outer position with minimal volume, thereby raising the pressure within the piston cylinder. The piston chamber is in fluid communication with air inside the tire and the flow between the two is controlled by a valving mechanism, such as a one way check valve that allows flow into the tire but not out of the tire, in one embodiment. In some embodiments, a pressure regulating valve is added to the system in communication with either the air in the tire or the air in the piston chamber, and limits the maximum pressure in the tire, or piston chamber. In some embodiments of the present invention, the system is designed so that the maximum pressure achieved in the piston chamber is low enough to prevent over-pressurization of the tire.

[0009] Other embodiments of the invention utilize the angular momentum of a member accelerated by the rotation of a vehicle's wheel to power a small pump that is used to inflate the wheel. These embodiments can also incorporate pressure relief mechanisms to ensure that the tire and/or the pumping chamber pressure never exceeds a desired setting. Other embodiments of the present invention limit the maximum pressure generation. These designs can be further enhanced by making the maximum pressure that the pump can generate adjustable either at the factory or by the end user.

[0010] According to some embodiments of the present invention, an automatic tire inflation system can be used with any pneumatic tire that rotates, including but not limited to passenger cars, trucks, buses, motorcycles, bicycles, tricycles (motorized and un-motorized) unicycles, heavy duty vehicles, delivery vehicles, taxis, ambulances, police cars, fire trucks, and the like.

[0011] Some embodiments of the present invention include one or more of the following features, functions, and/or characteristics: A device that uses centrifugal force caused by the rotation of a vehicle's tire to pump air into the tire, but does not require any deformation in the contact patch of the tire in order to operate.

A device that inflates vehicle tires but is not attached to or connected to the tire itself.

A device that requires the wheel to spin up to a certain speed before a piston or diaphragm overcomes substantial biasing force and moves from a radially inward position to a second radially outward position to pump air into the tire. When the wheel speed reduces below a certain value the system will reset and will be ready for another cycle.

Incorporating a detent device designed such that the once the detent forces have been overcome and the piston or diaphragm starts to move the detent forces reduce in magnitude substantially.

Using a magnet for the detent device that requires the vehicle speed to reach a certain magnitude before air is pumped into the tire.

Matching the magnetic strength to the piston or diaphragm mass and return spring (if included) such that a desired release speed can be selected for a given radius and orientation of installation.

Matching the piston area to the mass of the piston or diaphragm and the release speed to affect the pressure achieved in the pumping chamber and control the impact velocity of the piston into the hard stop .

Using a ball and/or spring detent for the device that requires the vehicle speed to reach a certain magnitude before air is pumped into the tire.

Matching the parameters of the ball detent mechanism to those of the piston or diaphragm mass such that a desired release speed can be selected for a given radius and orientation of installation.

Using a piece of elastically deformable material for the detent device.

Matching the parameters of the elastically deformable member to those of the piston mass such that a desired release speed can be selected for a given radius and orientation of installation.

A device incorporated into the wheel of a vehicle.

A device that attaches directly, or indirectly, to the wheel of a vehicle.

Selecting the trapped volume and stroke of the system such that there is a maximum pressure that can be achieved by the device.

Making that trapped volume and/or stroke of the system adjustable so that the maximum pressure can be adjusted. Incorporating one or more relief valves into the system to limit the pressures the system can achieve. The relief valve can be in fluid communication with the tire pressure or in fluid communication with the pumping chamber.

Incorporating a flow control device so that air can go from the pump chamber to the tire, but flow in the other direction is restricted or prevented.

Using a check valve for the flow control device.

Using a standard Shrader type valve stem and valve core for the flow control device.

Using a specially designed Shrader valve core that has lower or higher opening pressure than a standard valve core for the flow control device.

Using a custom designed check valve for the flow control device.

Utilizing a flow control device that allows atmospheric air to enter the pump cavity from the atmosphere but prevents it from leaving through that device.

Utilizing a check valve for the device that allows atmospheric air to enter the pump cavity from the atmosphere but prevents it from leaving through that valve.

Using an O-ring that is only partially backed up to act as the flow control device that allows atmospheric air to enter the pump cavity but not leave through it.

Utilizing a port arrangement that is uncovered to allow air to enter the pumping cavity when the system is at or near maximum volume but is covered up as the piston strokes outward radially.

Utilizing leakage to fill the pumping chamber.

Utilizing a return spring to return the piston back to the low speed position with maximum volume.

Utilizing pressure forces to return the piston back to the low speed position with maximum volume.

Utilizing magnetic forces to return the piston back to the low speed position with maximum volume.

Optionally eliminating a return spring or any other mechanism to bias the piston back to low speed position with maximum volume.

Utilizing a piston for the pumping member.

Utilizing a diaphragm for the pumping member.

Utilizing a a housing which moves relative to a piston or diaphragm that is fixed relative to wheel.

Making the piston out of metal and/or plastic.

Incorporating a seal on the piston to reduce leakage.

Making the seal integral with the piston.

Making the seal from an o-ring or similar design and/or material. Making the fit of the parts close enough such that a seal is not necessary.

Using a rolling diaphragm seal.

Using one or more pressure transducers and/or switches to measure the pressure in the tire and/or the pumping chamber.

Using one or more position sensors or switches to measure the position of the piston or diaphragm.

Using a plurality of tire inflation devices in one wheel so that it pumps up faster.

Using one device to inflate a plurality of tires.

Balancing the tire with the device in the extended (min volume) position so that the tire is balanced after it moves.

Incorporating one or more filter members on the inlet and/or any exhaust or vent ports to keep dirt, snow, ice, debris, and the like away.

Connecting the inflation device to a tire using a regular valve stem.

Selecting the pump's stroke and/or piston diameter to achieve a desired volume delivered per a pump stroke.

Controlling the impact velocity of the piston into the hard stop by selecting the component sizes such that the resulting pressure dynamics slow the impact.

Using a hard stop to limit the maximum motion of the piston or diaphragm.

Using a compliant hard stop to reduce the impact forces when the piston or diaphragm hit the hardstop.

Using the rotational motion of the wheel and/or tire to accelerate a rotor or disc, the momentum of which is used to operate a pump or compressor and pump fluid into the tire (which may also be referred to as a "spinner device")

Using a one way clutch (non-limiting examples include a ratchet, sprag, or roller clutch) in the device to drive the rotor or hub in one direction with the acceleration of the vehicle, but allow it to spin freely in the other direction.

Utilizing system friction to accelerate the rotor or disc in the spinner concept.

Utilizing a torque limiting device to transmit torque from the wheel to the rotor or disc for the spinner device.

Utilizing a torque limiting device to limit the torque that can be applied to the air pump or compressor by the rotor/hub thereby limiting the maximum pressure that can be achieved.

Utilizing the reaction torque created by the pumping member to accelerate or decelerate the rotor or disc.

Using a hose or tube to connect a spinner device to the normal valve stem.

Making the spinner device part of the wheel.

Making the spinner device part of a hubcap or a separate part like a hubcap. Adding electronics to any of the aforementioned to facilitate use, monitoring, and control.

Using a pressure transducer to measure pressure.

Using an electronically controlled valve to control the flow of air from the device into the tire and/or from the atmosphere into the device.

Using an electronically controlled valve to regulate the pressure in the tire.

Using a solenoid or other device to limit the motion of the pumping device to limit the addition of air into the tire.

Including a microprocessor or other form of electronic circuitry or electronic controller to control the system.

Having the microprocessor communicate to another controller using wireless communications (e.g. the engine, powertrain or vehicle controller).

Having the individual tire inflate devices communicate with each other.

Basing control actions on the communications with other controllers and/or other tire inflate devices.

[0012] A tire inflation system according to embodiments of the present invention exhibits a "snap action" (the air displacement mechanism is held in place by a detent mechanism until the forces caused by wheel rotation exceed the detent forces), which involves less time during pump actuation for leakage to occur, and which builds a higher pressure. In addition, one pump actuation is achieved per acceleration cycle, as opposed to existing designs which attempt to perform one pump actuation per tire revolution, for example. Embodiments of the present invention do not rely on tire deformation, and do not need to be located inside the tire.

[0013] While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 illustrates a cross section of a passive tire inflation system in the maximum volume, or low speed position, according to embodiments of the present invention. [0015] FIG. 2 illustrates a cross section of the passive tire inflation system of FIG. 1 in the minimum volume, or high speed position, according to embodiments of the present invention. [0016] FIG. 3 illustrates a cross section of a passive tire inflation device equipped with a pressure transducer, according to embodiments of the present invention.

[0017] FIG. 4 illustrates an isometric view of the passive tire inflation device equipped with a pressure transducer, according to embodiments of the present invention.

[0018] FIG. 5 illustrates a cross section of a passive tire inflation device equipped with a pressure transducer and position sensor, according to embodiments of the present invention.

[0019] FIG. 6 illustrates a cross section of a passive tire inflation device equipped with a relief valve in the pumping chamber and a filter on the inlet air, according to embodiments of the present invention.

[0020] FIG. 7 illustrates a cross section of a passive tire inflation device integrated into a wheel, according to embodiments of the present invention.

[0021] FIG. 8 illustrates another cross section of a passive tire inflation device integrated into a wheel with a relief valve that limits the maximum pressure in the tire, according to embodiments of the present invention.

[0022] FIG. 9 illustrates a system integrated into the wheel, accessible from the outside of the wheel, according to embodiments of the present invention.

[0023] FIG. 10 illustrates a close up view of a system integrated into the wheel taken along box A of FIG. 9, accessible from the outside of the wheel, according to embodiments of the present invention.

[0024] FIG. 1 1 illustrates a close up view of a system that can be preassembled and then installed into the wheel, according to embodiments of the present invention.

[0025] FIG. 12 illustrates a system integrated into the wheel, showing the access location in the outside of the wheel, according to embodiments of the present invention.

[0026] FIG 13 illustrates an embodiment in which the device is mounted in a rim from the inside of the rim.

[0027] FIG. 14 illustrates an enlarged view of the device of FIG. 13, taken along box A of FIG. 14.

[0028] FIG. 15 illustrates a close up view of a system designed to be preassembled and then installed into the wheel from the inside, according to embodiments of the present invention.

[0029] FIG. 16 illustrates a system that can be preassembled and then installed into the wheel from the inside of the wheel, according to embodiments of the present invention.

[0030] FIG. 17 illustrates a cross section of a passive tire inflation device that has adjustable stroke shown in a maximum stroke position, according to embodiments of the present invention. [0031] FIG. 18 illustrates a cross section of a passive tire inflation device that has adjustable stroke shown in a minimum stroke position, according to embodiments of the present invention.

[0032] FIG. 19 illustrates a cross section of a passive tire inflation device that has adjustable clearance volume shown in the minimum volume position, according to embodiments of the present invention.

[0033] FIG. 20 illustrates a cross section of a passive tire inflation device that has adjustable clearance volume shown in the maximum volume position, according to embodiments of the present invention.

[0034] FIG. 21 illustrates a cross section of a passive tire inflation device that uses a ball detent, according to embodiments of the present invention.

[0035] FIG. 22 illustrates an enlarged view of the ball detent of FIG. 21 , taken along box

A of FIG. 21 , according to embodiments of the present invention.

[0036] FIG. 23 illustrates a cross section of a passive tire inflation device that uses a wire form or leaf spring for the detent, according to embodiments of the present invention.

[0037] FIG. 24 illustrates an embodiment of a system that incorporates a check valve or similar device to allow air into the pumping chamber located in the housing itself, according to embodiments of the present invention

[0038] FIG. 25 illustrates an embodiment that incorporates a match fit to control leakage between the piston and the bore, according to embodiments of the present invention.

[0039] FIG. 26 illustrates an embodiment that incorporates an O-ring seal to control leakage between the piston and the bore, according to embodiments of the present invention.

[0040] FIG. 27 illustrates an embodiment that incorporates a spring loaded dynamic seal to control leakage between the piston and the bore, according to embodiments of the present invention.

[0041] FIG. 28 illustrates a piston made of multiple pieces to allow the mass of it to be adjusted, according to embodiments of the present invention.

[0042] FIG. 29 illustrates an alternative piston made of multiple pieces that allow the mass to be selected or adjusted, according to embodiments of the present invention.

[0043] FIG. 30 illustrates an alternative piston, according to embodiments of the present invention.

[0044] FIG. 31 illustrates an alternative piston, according to embodiments of the present invention. [0045] FIG. 32 illustrates an embodiment that employs rotational inertia of a spinning ring driven by the wheel to power a pump that inflates the tires, according to embodiments of the present invention.

[0046] FIG. 33 illustrates a close up view of an embodiment that utilizes rotational inertia of a spinning ring driven by the wheel to power a pump that inflates the tires, according to embodiments of the present invention.

[0047] FIG. 34 illustrates an embodiment of a tire inflation system which includes a valve controlled by the tire pressure that will in some cases open and allow the air from within the pumping chamber to be in fluid communication with atmosphere or other regions of lower pressure, according to embodiments of the present invention.

[0048] FIG. 35 illustrates a piston assembly that uses an O-ring for both a seal and to admit air to the pumping chamber, according to embodiments of the present invention.

[0049] FIG. 36 illustrates a side view of the piston assembly of FIG. 35, according to embodiments of the present invention.

[0050] FIG. 37 illustrates the piston assembly of FIGS. 35 and 36, with the O-ring deformed, according to embodiments of the present invention.

[0051] FIG. 38 illustrates the side view of the piston assembly of FIG. 37, according to embodiments of the present invention.

[0052] FIG. 39 illustrates a tire inflation system that uses an O-ring for both a seal and to admit air to the pumping chamber, according to embodiments of the present invention.

[0053] FIG. 40 illustrates a tire inflation system that includes a device to open a valve to admit air to the tire using the piston motion and incorporates a port opening to admit air to the pumping chamber, according to embodiments of the present invention.

[0054] FIG. 41 illustrates a tire inflation system that incorporates a valve stem and valve in fluid communication with the tire pressure, according to embodiments of the present invention.

[0055] FIG. 42. illustrates a tire inflation system that utilizes a diaphragm for the pumping mechanism, according to embodiments of the present invention.

[0056] FIG. 43 illustrates the tire inflation system of FIG. 42 with the diaphragm in a different operational position, according to embodiments of the present invention.

[0057] FIG. 44 illustrates a tire inflation system that includes a valve controlled by the tire pressure that can open and allow the air from within the pumping chamber to be in fluid communication with atmosphere or other regions of lower pressure, according to embodiments of the present invention.

[0058] FIG. 45 illustrates an alternative tire inflation system, according to embodiments of the present invention. [0059] While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

[0060] FIG 1 illustrates an embodiment of a passive air inflation device. In this embodiment the device 1 is connected directly to a standard valve stem 2 that may, or may not, include a valve core 3 and is mounted in typical fashion to a wheel rim 4. The valve core 3 may be of typical Schrader (or presta) valve construction, for example, but may be designed to have minimal opening, or cracking pressure. The device also includes a piston 5 that is free to translate in the bore 6 of the cylinder 12. The piston may, or may not, be constrained from rotating in the bore. The piston may be made of many different materials such as metals (including without limitation ferrous, non-ferrous, steels, irons, brass, bronze, copper, plastics, ceramics, or any other engineering materials). The piston may be made by machining operations such as turning and milling, or may be cast, or molded, or any combination of these or other manufacturing processes such as, for example, welding and/or bonding. According to some embodiments of the present invention, the piston is approximately ten millimeters in diameter, sixty millimeters long, and is machined from steel. [0061] In the embodiment shown, a spring 7 is in contact with the piston 5 with the other end in contact with the inside of cylinder 12, or valve stem 2, such that there is a force which tends to move the piston inwards towards the center of the rim 4 (e.g. toward the bottom of the view of FIG. 1 ). The volume 8 in the cylinder, or pumping chamber, is constrained by the piston on one end and, in this embodiment, the valve stem on the other end, such that when the piston is at its most inwardly radial position, the volume will be at a maximum, and when it is at its most radially outward position the volume will be a minimum. According to some embodiments of the present invention, the cylinder 12 is machined of steel and is approximately fifty-seven millimeters in outside diameter and approximately 122 millimeters long.

[0062] In this embodiment, the piston has a hole 9 through it and a check valve 10 placed in fluid communication with the hole 9 and the cylinder end of the piston 5, such that air can pass from outside the cylinder 12 through the valve 10 and into the cylinder 12, but cannot flow from within the cylinder 12 through the valvel O to outside the cylinder 12. Instead of a check valve 10, an alternative air flow control mechanism 10 may be used to permit air flow from outside cylinder 12 into cylinder 12, while substantially inhibiting airflow from inside cylinder 12 to outside cylinder 12. An alternative air flow control mechanism 10 may be a reed-type airflow port, or a spill port, for example. Hole 9 may also be referred to as an aperture or a passage. According to some embodiments of the present invention, the hole 9 through the piston is approximately two millimeters in diameter and is drilled, and the check valve used is a model 855 available for purchase from the Lee Company. [0063] In this embodiment, a magnet 11 is coupled to the piston 5, such that the magnet 1 1 is attracted to the end of the cylinder 12, which in this embodiment is made of a ferrous material, such as steel, that is magnetic. The laws of magnetics dictate that the magnetic attraction between the magnet in the piston and the cylinder will be greatest when there is no air gap between the piston and the cylinder. This magnetic force combined with the spring will tend to force the piston to, and keep it at, the most radially inward position (as in FIG. 1 ). According to some embodiments of the present invention, the magnet is a rare earth magnet (non-limiting examples include: samarium cobalt and neodymium) purchased from McMaster-Carr. According to other embodiments of the present invention, standard magnets (non- limiting examples include ferrite and alnico) are used. [0064] As used herein, the term "coupled" is used in its broadest sense to refer to elements which are connected, attached, and/or engaged, either directly or integrally or indirectly via other elements, and either permanently, temporarily, or removably. As used herein, the term "rotatably coupled" is used in its broadest sense to refer to elements which are coupled in a way that permits one element to rotate with respect to another element. As used herein, the terms "fluidly coupled" or in "fluid communication" are used in their broadest sense to refer to elements which are coupled in a way that permits fluid flow between them. [0065] As the vehicle speed increases and the rotational velocity of the rim and device increases, there will be centrifugal forces on the piston mass that will tend to force the piston 5 outward radially, but until the rotational speed of the wheel is high enough, the forces will not be enough to overcome the combined forces of the spring 7 and the magnet 1 1. As used herein, the term "centrifugal force" is used to refer to the effects of inertia that arise in connection with rotation and which are experienced as an outward force away from the center of rotation. Once the vehicle achieves a speed that is high enough, the centrifugal force will overcome the combined force of the spring 7 and the magnet 1 1 and the piston 5 (and magnet) will accelerate radially outwards. As the piston 5 and magnet 11 accelerate outwardly the gap between the magnet 1 1 and the piston 5 will increase and the magnetic force will reduce very quickly, thereby creating a large force imbalance that will cause the piston 5 to accelerate very rapidly. Accelerating the piston quickly is desired, but not required, as it can generate higher pressures and minimize the time available for leakage, according to embodiments of the present invention. [0066] As the piston 5 accelerates radially outward relative to the center of the wheel, the volume 8 in the cylinder 12 will be reduced and the pressure will rise until it exceeds the pressure required to open the flow control device or valve core 3, and then air will flow from the pumping chamber 8 into the tire 4. According to some embodiments of the present invention, the flow control devices are valve cores that are commercially available cores from the Schrader-Bridgeport Company. Other embodiments use special valve cores designed to open when there is approximately a 2-4 psi pressure differential across the valve. Still other embodiments use special valve cores that open with 10-20 psi pressure differential. [0067] FIG. 2 shows the device 1 of FIG. 1 with the piston 5 at the outward most position. In this case, the volume 100 above the piston has increased and the air gap between the magnet 1 1 and cylinder end 12 is large and there is little force on the piston. According to some embodiments, a magnetic attraction can be imparted between cylinder 12 and piston 5 based on the influence of magnet 1 1 over time. Air enters the volume 100 through hole 13 as the piston 5 moves from the inner position (illustrated in FIG. 1 ) to the outer position (illustrated in FIG. 2). In the outer position, there is a clearance volume 101 between the Schrader valve core 3 and the piston 5. The ratio of this volume to the swept volume of the system (piston area multiplied by stroke) can be adjusted to control the maximum pressure the system can achieve, according to embodiments of the present invention.

[0068] A tire inflation system according to embodiments of the present invention can be "passive" in that it adds air to the tire and/or maintains or regulates pressure within the tire, without human initiation. A tire inflation system according to embodiments of the present invention can be "automatic" in that it adds air to the tire and/or maintains or regulates pressure within the tire, without human intervention. According to some embodiments of the present invention, an electronic control system actively controls the pressure within the tire. [0069] FIG 3 illustrates an embodiment of the present invention with instrumentation to measure the pressure in the cylinder or pumping chamber. The pressure measurement can be used for testing purposes and/or can be used to communicate the pressure to other devices when in normal and/or diagnostic use. The passive air inflation system 200 includes a housing 201 and a cylinder bore block 202 that is affixed to the housing with threaded bolts 203 that are M4x0.7x10mm. Other means of affixing the two members together can be used such as, without limitation, interference fits, welding, clips, adhesives or any other manufacturing process. In some embodiments the housing 201 is comprised of steel of approximately fifty-four millimeters in diameter and the cylinder bore block 202 is also comprised of steel with a ten millimeter bore inside of it. In some embodiments one or more of the components is made of plastics or polymers and other parts are molded or manufactured in place. A steel end plate 204 is attached to the end of the housing 201 using bolts 205 that are M3xO.5x8mm, but many different fastening or retaining methods can be utilized. A seal 206, for example an O-ring, may be included between cylinder bore block 202 and end plate 204. According to some embodiments, seal 206 is a Parker 2-014, 70 durometer Viton or Buna ring. The end plate 204 can be threaded at location 207 to accept a typical Schrader valve stem, a valve core similar to one from a Schrader valve stem, or other types of connections. A piston 208 translates in the bore of the cylinder bore block 202, and is optionally attached to the piston weight 209, in some cases using bolts such as M3xO.5x5mm. The piston weight can be made of any heavy material including, for example, steel, iron, and/or lead, as long as it can be secured to the piston itself, but magnetic materials can enhance the magnetic flux path and may be desirable in some cases, according to embodiments of the present invention. Other embodiments use a single piece piston.

[0070] According to some embodiments of the present invention, a magnet 210 is affixed to the piston 208 using an interference fit or other suitable coupling, including but not limited to adhesives, mechanical tapping, fasteners, and the like. An end plate 21 1 made of magnetic material is affixed to the housing 201 with screws 213 (M4xO.75x10). End plate 21 1 may be affixed to housing 201 with many other methods, especially if magnets are not being used in the piston 208. The end plate 21 1 has a hole 212 and the magnet has a hole 220 which allow air to pass through. According to some embodiments of the present invention, a dynamic seal 214 is included to limit the passage or leakage of air around the piston 208 inside of the cylinder bore. This leakage may be controlled solely by ensuring that the clearances between the two parts are suitably small, for example by using a match fit, an O-ring, a piston disc, a rolling diaphragm, a molded dynamic seal such as a American High Performance seals part number APSMM 5.1 mm x 10mm x 2.2mm, fabrics, rubber sheets or any other sealing method. A return spring 216 is included to return the system, according to embodiments of the present invention. A pressure sensor 217 may be included to monitor the pressure of the pumping chamber 221. Alternatively, a pressure sensor may be incorporated with one that directly measures the tire pressure, or both could be used. These pressure sensors can be used for testing purposes or in normal or diagnostic operation but are not required, according to embodiments of the present invention. According to some embodiments of the present invention, the sensor has a threaded portion 218 which threads into a threaded portion of the cylinder bore 222 and a seal 219 is used to limit the leakage.

[0071] FIG 4 shows an isometric view of the system of FIG. 3. FIG 5 illustrates an embodiment of the present invention with both a pressure transducer 217 to measure the cylinder pressure and a position sensor 300 to measure the piston position. Neither sensor is required, but may be used for test purposes or during normal and/or diagnostic operation. The position sensor 300 has a threaded rod 301 that threads into the piston weight 302 and is mounted to a mount 303 using bolts 304. The mount 303 is coupled to another mount 305 using bolts 306 and that mount is secured to the end plate with bolts 307, according to embodiments of the present invention.

[0072] FIG 6 illustrates an embodiment of the present invention that incorporates a relief valve 400 that limits the pressure in the pumping chamber 401 to ensure that it does not get too high. In this embodiment the relief valve is mounted in the cylinder bore 402 and may be secured, without limitation, by threads, clips, swaging, adhesives, fasteners and/or any other fastening mechanism or manufacturing process. According to some embodiments of the present invention portions of the relief valve mechanism may be integral to the cylinder housing, such through the use of a spring loaded check ball or disc. The relief valve can also be configured to regulate the pressure of the air inside the tire rather than the pressure inside the control volume. Regulators in both positions can be used to control both pressures, according to embodiments of the present invention.

[0073] FIG 6 also illustrates an embodiment of the present invention that incorporates a filter 404 or similar material or membrane that is used to keep dirt, water, debris and any other contaminants from entering the cylinder 401 though the check valve 403. According to some embodiments of the present invention this filter 404 may be placed in the hole (for example, hole 212), may be mounted on top of the cylinder in various ways, including, but not limited to, snap in place, adhesives, interference, fasteners and/or other securements, or the air entrance hole may be located at any position that would prevent contamination from entering the system. According to embodiments of the present invention, the filter 404 is mounted in a filter housing 405 made of plastic or other easily molded materials and is snapped into place over the housing 402. The filter is not required for operation but may improve the durability and performance of the system over time, according to embodiments of the present invention.

[0074] FIG 7 illustrates a passive tire inflation device 500 that is integrated into a wheel 501 with tire 502, according to embodiments of the present invention. The wheel may be made of different materials including, but not limited to, cast aluminum, magnesium, steel, plastics, composites and/or any other materials known to one of ordinary skill in the art, based on the present disclosure. According to one embodiment of the present invention, the passive inflation device 500 is a complete assembly that may be assembled in advance and installed, or coupled with the wheel 501 in one assembly. According to some embodiments of the present invention the assembly 500 is secured to the wheel using a retainer 503, which could consist of a snap ring, threads, mounting screws, welding, adhesive, and/or similar mechanisms. A seal can be added between the wheel 501 and the device 500. This seal could include, but is not limited to, an o-ring, a molded seal, and/or a liquid sealant. There are many different ways in which the device can be integrated into the wheel and secured there, including, but not limited to, threading the device in, having a threaded portion that extends through the wheel and is secured with a nut, or having a protrusion that goes through the rim and is secured with a clip, snap in place parts, and/or interference fits, for example. The device could be installed from the tire side of the rim, or from the inside of the rim, according to embodiments of the present invention.

[0075] FIG 8 illustrates a view of an embodiment of the present invention 600 that is integrated into a wheel 601 . FIG 8 also illustrates a relief valve 602 that is used to limit the maximum air pressure in the tire 603 to proper levels. The relief valve may be designed to relieve pressure at a set pressure or may be adjustable by a technician or the operator. The relief valve may be part of the assembly 600 or may be a separate piece located in the wheel itself as shown.

[0076] FIG 9 illustrates a passive tire inflation system integrated into a wheel from the front side. According to some embodiments of the present invention a wheel 700 has a bore 701 in it in which the inflation device 702 is located. Figure 10 is an enlarged view taken along box A of FIG. 9, showing more detail, including an O-ring seal 703 and a retaining clip 704. There are many different ways, and locations, in which the system could be sealed, including without limitation: sealants, gaskets, metal compression rings, Teflon tape, and/or molded rings; the O-ring illustrated is but one example. Similarly, there are many different ways that the device could be constrained in the wheel or rim including, without limitation, snap rings, retaining clips, fasteners, press fits, thermal shrink fits, adhesives, swaging, welding, molding in place, and/or any other method apparent to one of ordinary skill in the art, based on the disclosure provided herein.

[0077] FIG 1 1 illustrates an embodiment in which a preassembled inflation device 800 is mounted into a wheel 850 that has a bore that has been manufacture by various processes including, but not limited to, machining, casting, molding, and/or produced in some manner to accept the device. The device 800 includes an outer housing 801 that may be formed at least in part from sheet metal or other similar materials using drawing, rolling and welding, hydroforming, or other processes for those materials, or could be made of other materials such as, for example, plastics, resins, composites, and could be molded, cast, machined or produced with a wide variety of methods. The device also includes a piston/mass 802 that could be made of many different materials. Piston/mass 802 is steel and has magnetic properties, according to some embodiments of the present invention. The piston/mass 802 is free to translate, and optionally rotate, in the bore so as to change the volume created between it and the check valve 803. According to embodiments of the present invention there may be a seal 804 attached to the piston/mass 802 that is trapped by a plate 805 that is affixed to the piston 802 by one of a variety of methods including without limitation: snap to fit, interference fit, fasteners, molding it in place, and/or adhesives. The system may also include a spring 806 to return the piston/mass to the inward position that represents bottom dead center (BDC).

[0078] In certain embodiments, the piston/mass includes a check valve 807 or some other means that allows one way flow such as a reed, or flapper valve, used to allow air into the pumping chamber 852 but not out of it. Some embodiments of the present invention include a detent mechanism used to hold the piston/mass at the BDC location as the vehicle accelerates but has not reached the switching speed (e.g. the speed at which the centrifugal force acting on the piston/mass overcomes the force acting on the piston/mass by the spring and/or magnet). A magnet 808 can be used as a detent mechanism, and can be located in the piston 802, or another part contacted by the piston. In FIG 1 1 , the magnets 808 are located inside of an end plate 809 that sits in the bore on the wheel upon the housing and supports a filter 810, according to embodiments of the present invention. The housing has a "necked down" or reduced diameter area 81 1 that serves as a step upon which the device can rest in the bottom of the bore in the wheel, according to embodiments of the present invention. The entire device 800 can be sandwiched between the step and a retaining ring 812 and/or other fastening device that holds the parts together.

[0079] FIG 12 illustrates a wheel 900 in which an inflation device has been mounted. The opening 901 on the front provides an aperture through which the air enters, and through which the inflation devices can be maintained and/or adjusted, according to embodiments of the present invention.

[0080] FIG 13 illustrates an embodiment in which the device is mounted in a rim from the inside of the rim. FIG. 14 illustrates an enlarged view of the device of FIG. 13, taken along box A of FIG. 14. Here the device is retained with a nut 1000 that screws onto threads in the device. Mounting the device from the inside has the advantage of protecting it and the air intake from the direct contact with the elements and impact that it could be exposed to if mounted on the outside, according to embodiments of the present invention. [0081] FIG 15 is a cross sectional view of the device mounted in a tire rim from the inside. This embodiment includes a filter 1 100 mounted on top of the device, and there is flat spot 1101 machined in the rim so that the device can be screwed on using a nut 1 102, according to embodiments of the present invention. FIG 16 illustrates an embodiment in which an inflation device is mounted in the rim from the inside and can be adjusted there if desired.

[0082] FIG 17 illustrates a tire inflation mechanism in which the stroke of the piston is adjustable to affect the amount of air added to the tire, and/or the maximum pressure to which the system can pump, according to embodiments of the present invention. In a pump used to pressurize compressible gases such as air, the maximum pressure rise a system can achieve is limited by both the stroke (swept volume) and the clearance volume. Reducing the stroke can be an effective way of limiting the maximum pressure that the system can achieve. By doing this, it is possible to both configure the system so that it is not possible to over-inflate the tire, or adjust the pressure to which the system will pump by simply adjusting the stroke. In such configurations, no relief valve is needed although a relief valve could be added for redundancy, according to embodiments of the present invention. Numerous other methods can be used to permit an adjustable stroke including, for example, using an adjustable stop as illustrated in FIG 17.

[0083] In FIG 17, the piston 1200 motion is limited by a piston hard stop 1201 that can be adjusted to limit the maximum stroke and therefore the maximum displaced volume 1202 in the system. According to one embodiment of the present invention the position of the hard stop 1201 can be controlled by a threaded rod or screw 1203 that can be advanced or retracted to adjust the stroke by threading into the housing 1204. A lock nut 1205 can be used to ensure that the position of the threaded rod, and therefore the hard stop, does not unintentionally move. Based on the disclosure provided herein, one of ordinary skill in the art will appreciate numerous other ways that configuring and/or adjusting the hard stop can be achieved, and FIGS. 17 and 18 are just one example. FIG. 18 illustrates the hard stop adjusted to provide limited stroke and therefore less swept volume 1206 and the capability of less pressure.

[0084] FIG. 19 illustrates an embodiment of the present invention in which the housing 1300 contains a step or other feature 1301 that limits the travel of the piston 1302 in the direction towards top dead center (TDC). The housing 1300 is threaded or mounted to the end piece 1303 in a way that it can be moved when desired relative to the end piece 1303 such that the clearance volume 1304 can be adjusted thereby affecting the maximum pressure that can be obtained, the maximum pressure being a function of the ratio of the swept volume to the clearance volume. Based on the disclosure provided herein, one of ordinary skill in the art will appreciate numerous other ways in which the clearance volume can be configured and/or adjusted. FIG 19 shows the volume in a minimum configuration which will result in the largest pressures and FIG 20 shows the system of FIG. 19 with the volume in a maximum configuration which will result in the lowest pressures, according to embodiments of the present invention.

[0085] FIGS. 21 and 22 illustrate a passive tire inflation device in which a spring loaded ball 1404 is used as a detent mechanism to hold the piston 1400 in place until a sufficient or desired centrifugal force is achieved, according to embodiments of the present invention. FIG. 22 is an enlarged view taken along box A of FIG. 21. Once the spring force (including the spring force transmitted via the spring ball detent 1403) is overcome, there is a large force imbalance which causes the piston 1400 to accelerate rapidly radially outward relative to the center of rotation, resulting in a rapid rise in pressure creating a burst of air that is injected into the tire. By building pressure quickly, the effects of leakage are minimized and the device can be safer and/or more efficient because the valve core 1410 is only open for short periods of time, according to embodiments of the present invention. In FIG 21 , the piston 1400 may include a detent feature 1401 machined, or processed, into it and the housing 1402 may include a pocket 1403 in it that holds a ball 1404 and a spring 1405 that preloads the ball 1404 into the piston. This design creates a certain amount of force that needs to be overcome before the piston 1400 can move thereby requiring a certain wheel rotational speed to be obtained before the piston 1400 can accelerate. [0086] Other configurations may be employed in a passive inflation device which impart a force that must be overcome before the piston can accelerate in a substantially radial direction. FIG. 23 shows an embodiment in which a leaf spring or wire 1500 is used to create the force. Here the spring 1500 is attached to the housing 1501 with a bolt 1502 and rides in a detent feature 1503 (e.g. a notch or indentation, partially or entirely encircling the piston) in the piston 1504. The spring or wire form 1500 can be secured to the housing 1501 and interact with the piston 1504 to create the desired force in numerous other ways. [0087] FIG 24 illustrates a tire inflation system that includes a device used to limit the maximum pressure in the cylinder or pumping chamber, according to embodiments of the present invention. According to some embodiments of the present invention a relief valve 1588, which may consist of a spring loaded check ball, or may be a spring biased plate or piston will allow fluid to pass from within the pumping chamber to atmosphere or another region of lower pressure. One of ordinary skill in the art can appreciate that there are many different mechanisms that can be used to create the desired functionality [0088] According to some embodiments of the present invention, a seal may be used to limit the amount of leakage in the annular clearance between the piston and cylinder bore. This seal may be a polymer or synthetic O-ring, a molded seal with specific cross section, a composite seal that includes a backup ring or spring, a skirt or layer of film attached to the piston or bore, or any other sealing mechanism apparent to one of ordinary skill in the art, based on the disclosure provided herein. FIG. 25 illustrates an example of a passive tire inflation device in which there is no discrete seal but the leakage is controlled by selecting the clearance between the piston 5 and the bore 6 to be sufficiently small. FIG 26 illustrates an example in which an O-ring 2600 is used, and FIG 27 illustrates an example in which a dynamic seal with a back-up spring 2700 is used.

[0089] FIGS. 28-31 illustrate a multi-part piston for which the overall mass is adjustable, according to embodiments of the present invention. Adjusting the mass is one way to adjust the vehicle speed (and hence the wheel rotational speed) at which the system releases the piston and pumps air into the tire. The vehicle speed at which the inflation system activates can also be adjusted by varying the spring preload, the mounting location and orientation on the wheel, the force of the detent mechanism and/or other parameters in the inflation system.

[0090] According to other embodiments of the present invention, the rotational energy of a member accelerated by the vehicle is used to operate the passive inflation mechanism. FIG. 32 illustrates a device 1650 that comprises a tire 1600 mounted on rim 1601 with a member 1602 attached to the rim in such a way that it can rotate relative to the rim, according to embodiments of the present invention. The rotating member 1602 is mounted on a fixed assembly 1603 that is part of, or attached, directly or indirectly, to the rim 1601. The fixed assembly 1603 contains a pumping mechanism that pumps air inside the tire. According to embodiments of the present invention the air may flow through a tube or hose 1605 connected to the normal valve stem 1606 that may have a standard or modified valve stem in it.

[0091] FIG 33 illustrates the embodiment of FIG. 32 in more detail. The rim 1601 has a rotating member 1602 attached to it so that the rotating member 1602 can rotate with minimal friction relative to the rim 1601 but is otherwise constrained and supported. According to some embodiments of the present invention, the rotation of the rotating member 1601 is controlled by a one way clutch 1702, or other device with similar functionality such that when the vehicle is accelerating the clutch will be engaged and the rim 1601 will accelerate the ring 1602. Alternative embodiments use a friction mechanism that may transmit a certain amount of torque in one direction and more or less in the other direction, but which will limit how much torque can be transmitted. The ring 1602 will continue to accelerate as long as the vehicle is accelerating. Once the vehicle decelerates the rim 1601 will also decelerate but the one-way clutch will provide minimal, if any, restraining torque and therefore the rotational inertia of the rotating member 1602 will tend to keep the ring 1602 at the same speed and therefore it will be spinning faster than the rim, according to embodiments of the present invention. The relative motion will cause a cam 1703 or similar crank assembly to move relative to the fixed pump housing 1603 which contains a piston 1704 which will then translate back and forth in the bore. The same relative motion may be used to operate other kinds of pumps, according to embodiments of the present invention. According to such embodiments of the present invention, the cam 1703 or similar device is rigidly mounted on the rotating member 1602 and/or is integral with the rotating member 1602, such that a rotational velocity of the cam 1703 matches a rotational velocity of the rotating member 1602. In some cases, one or more gears or other devices may be used to cause the rotational velocity of the cam 1703 to be related to, but not necessarily the same as, that of the rotating member 1602. As the piston translates back and forth in the bore the volume of air 1705 trapped between the piston 1704 and the end plate 1706 will get larger and smaller creating a pumping effect. Check valves or similar flow control devices 1707 and 1708 control the flow in and out of the cylinder These valves 1707 and 1708 may be check valves or may be valves that are actively controlled. A return spring 1709 is used to return the piston to the bottom dead center position, according to embodiments of the present invention.

[0092] According to embodiments of the present invention the passive tire inflation device illustrated in FIGS. 32 and 33 can be constructed without a one way clutch so that the relative motion between the pumping chamber fixed to the rim and the rotating member could be used to pump air into the tires on acceleration and deceleration. According to alternative embodiments of the present invention, the components may be rearranged to achieve similar results; for example, the piston may rotate with the rotating member 1602 and the cam could be fixed with respect to the rim. In other embodiments, the piston can be formed of a deformable member such as a diaphragm or a membrane and can still be actuated using forces generated from the rotation of the tire (centrifugal force) or from the energy stored in a rotating member. In other embodiments of the present invention, motion created either from the centripetal forces, or from the rotational energy, may be stored up over multiple cycles before being released all at once to add air to the tire. [0093] According to some embodiments of the present invention the tire pressure can be used as an actuation signal to control whether air is added to the tire or not. FIG. 34 illustrates a tire inflation system that utilizes a valve 1800 controlled by the tire pressure that will allow the air in the pumping chamber to exit the pumping chamber rather than attain a pressure high enough to permit it to enter the tire, thereby limiting the pressure. In this embodiment, valve 1800 is biased to a closed position with spring 1801 and opens when pressure on line 1802 exceeds a predetermined threshold. Line 1802 is in fluid communication with the inside of the tire, at tire pressure. The valve 1800 may operate in a digital fashion where the valve is either open or closed, or may operate in an analog manner. The valve mechanism may include a detent mechanism that helps hold the valve in one or more discrete positions. The valve may be controlled directly by the tire pressure as illustrated, or in other embodiments the valve may be controlled indirectly based upon the tire pressure such as by the use of a pressure transducer and electronically controlled valve. [0094] Alternatively, other embodiments of the present invention use the tire air pressure to prevent air from being introduced into the pumping chamber, thereby limiting the maximum pressure that can be achieved.

[0095] Other embodiments use the tire pressure to overcome a spring or other biasing device restricting the motion of the piston, preventing it from pumping. [0096] Still other embodiments permit the tire pressure to be used to create forces that work against the detent mechanism, allowing the piston to release at lower vehicle speeds, thus minimizing the amount of pressure that can be produced and allowing long periods of time for the pressure in the pumping chamber to leak. For example, a piston may have the tire pressure acting on one side of it and the other end acts to push the piston away from the magnet.

[0097] FIGS. 35-36 illustrate a piston assembly that utilizes an o-ring to seal pressure in one direction and allows air to flow in the other direction. FIG. 35 illustrates a piston 1900 with end 1901 exposed to the pumping chamber and end 1902 exposed to atmospheric pressure. An O-ring (made of rubber, polymer, or other flexible material) or similar type seal 1903 is installed on the piston 1900 in a gland comprised of a upper land 1904 and an lower land 1905. The upper land 1904 of the gland is either continuous or covers enough of the periphery of the piston 1900 such that the seal will be supported and will make full contact with the cylinder bore and prevent flow from end 1901 of the piston to end 1902 when the pressure is greater on end 1901 than at end 1902, or when the motion of the piston relative to a fixed bore is such that it would appear to travel towards the bottom of FIG. 35. [0098] FIG 36 illustrates the same piston 1900 as shown in FIG. 35 rotated 90 degrees around its centerline. In this figure the lower land 1905 is not continuous and includes cuts 1906 in the lower land where the O-ring is not supported. FIG. 36 illustrates that these cuts

1906 do not affect the performance of the seal when the system is operated with pressure on end 1901 greater than end 1902 or when the motion of the piston relative to a fixed bore is such that it would appear to travel towards the bottom of FIG. 35. FIG. 36 illustrates two cuts 1906, but this is only exemplary and the system will function with one, two or more than two cuts 1906 in the piston 1900.

[0099] FIGS. 37 and 38 illustrates the same piston with pressure on end 1902 being greater than 1901 or when the motion of the piston relative to a fixed bore is such that it would appear to travel towards the top of FIG. 36 or 37. FIG. 38 illustrates the side view of FIG. 37. In these figures the cuts 1906 in the lower land 1905 allow the O-ring to deform

1907 such that a gap 1908 is created between the O-ring 1903 and the cylinder bore. This allows fluids to move from end 1902 of the piston to 1901. This allows the pumping chamber to be recharged with fluid to be pumped into the tire. In other words, O-ring 1903 acts at different times as both a seal (between the piston and the bore) and also as a form of air flow control mechanism or valve permitting air to flow past the O-ring 1903 (between the piston and the bore) when the O-ring is bent or deformed.

[00100] FIG 39 illustrates a tire inflation system that utilizes the seal design illustrated in FIGS. 35-38, according to embodiments of the present invention. [00101] FIG. 40 illustrates a tire inflation system that utilizes a port to allow fluid to be introduced into the pumping chamber. In FIG. 40 a piston 2000, travels in a bore 2001 with port 2002 that connects the interior of the cylinder 2001 to atmosphere. When the piston is in the maximum volume position the port will be inside the pumping chamber allowing the pumping chamber to fill. When the piston is released it will travel past the port 2002 thereby preventing fluid from leaving or entering the pumping chamber. When the vehicle speed has been reduced and the piston is ready to return to the maximum volume position, leakage will allow the pressure in the pumping chamber to rise enough to permit the piston to return. [00102] Other embodiments of the system do not have valves or porting to admit fluid to the pumping chamber but rather rely on leakage into the pumping chamber (for example, leakage past the piston/cylinder interface) to fill the pumping chamber. Because the duration of time available to fill the pumping chamber is much greater than the time that the piston is pumping, the leakage is small enough to permit the system to build pressure and inflate the tire even despite the leakage at the piston/cylinder interface.

[00103] FIG. 41 Illustrates invention tire inflation system that includes the ability to directly measure the tire pressure and/or add or remove air from the tire. In this embodiment, the inflation device 2100 is mounted in a wheel 2101 with end 2102 exposed to the tire pressure. A passage 2103 connects the tire pressure to a typical (Schrader, presta, or otherwise) valve stem 2104 with valve insert 2105 in fluid communication with the passage 2103. The design illustrated is only exemplary and there are many other designs that perform the same or similar functionality.

[00104] FIG 42 illustrates an embodiment of the present invention that is comprised of a diaphragm 2102 a magnet 2130, a steel member 2104 and a flow control device 2105. This embodiment functions substantially in the same manner as the piston designs. Non-limiting examples of materials for the diaphragm include, but are not limited to, a combination of one or more of the following: metal, polymers, rubber, plastic, composites, fibers, resins or natural products. According to some embodiments of the present invention, the geometry and material properties of the diaphragm are designed to act as a return spring to return the diaphragm to the maximum volume position illustrated in FIG. 42. FIG. 43 illustrates an embodiment of the present invention that utilizes a diaphragm after it has pumped and is in a lower volume state.

[00105] As illustrated in FIG. 44, a tire inflation system comprises a housing 2200 that has a bore, or cylinder, 2201 in it, according to embodiments of the present invention. The housing 2200 is mounted to, coupled to, or installed in, a wheel 2202 of a vehicle such that the one end of the bore 2203 in the housing is closer to the axis about which the tire rotates than the other end of the bore 2204. A piston 2205 is located within a bore, or cylinder 2201 , of the housing such that it can translate in the bore. Attached to the housing 2200 is an end cap 2206 which has one or more magnets 2207 in contact with it. The magnet 2207 may be secured in place by any combination of means including, but not limited to interference fit, adhesives, staking, fasteners, retaining plates, clips, or other mechanisms. Alternatively, the magnet may be allowed to move freely in the piston and may be held in place primarily by magnetic forces.

[00106] According to some embodiments of the present invention, the piston 2205 is made from, or includes, magnetic materials, including but not limited to ferrous materials and other magnets properly oriented to be attracted to the magnet 2207. The magnet 2207 creates a strong force that tends to keep the piston 2205 in contact with end cap 2206 and/or the magnet 2207 once they are in contact or close proximity with each other. A return spring 2208 is located inside the housing to create a force that is used to return the piston to end 2203 of the bore. Both the magnetic force and the spring force tend to force the piston towards end 2203 of the bore, but the properties of most springs are such that the force created by the spring will be the least when the piston is at end 2203 of the bore and will increase as the piston is displaced closer to end 2204. Conversely, the properties of magnetics are such that the force attracting the piston towards end 2203 will be greatest when there is minimum gap between the piston and the end cap and/or magnet and it will be reduced very quickly as the magnet piston moves away from end 2203. To this effect, the magnet acts as a detent mechanism that has high force initially to hold the piston in substantially one position and then diminishes rapidly once the piston has started moving. A different alternate detent mechanism may be used, according to embodiments of the present invention. Similarly, one function of the spring is to return the piston for the next cycle. Other embodiments of the present invention do not include a spring but rely on other forces, such as, but not limited to, pressure and gravity to return the spring to the inner position near end 2203 of the bore.

[00107] When the wheel of the vehicle is not rotating, the combination of the spring 2208 (if included) and the detent mechanism will be sufficient to keep the piston at, or near, end 2203. As the rotational speeds of the wheel increase, forces that oppose the spring and detent mechanism will increase until they are great enough to overcome the detent mechanism and start to accelerate the piston along the bore in the direction of end 2204. Once the detent mechanism has been overcome those forces will diminish quickly and there will be a large force imbalance causing the piston to accelerate rapidly towards end 2204 of the bore. As the piston moves towards end 2204, air in the cylinder, or pumping chamber, 2209 will be compressed until flow control device 2210 opens and allows air to pass from the pumping chamber into the tire via passage 221 1 , which is in fluid communication with the tire.

[00108] As the vehicle speed, and therefore wheel speed during normal circumstances, is reduced, the forces tending to move the piston towards end 2204 will be reduced, and once the tire is rotating slow enough the forces will be insufficient to prevent the piston from returning to end 2203 where the detent mechanism will reengage. According to some embodiments of the present invention, fluid will flow into the pumping chamber as the piston moves towards end 2203 by flowing past an O-ring that is only partially supported and allowed to flex to create a gap and act as a one way check valve (similar to that which is described with respect to FIGS. 35-38).

[00109] According to some embodiments of the present invention, a third flow control device 2213 can be used to allow fluid from the pumping chamber 2209 to travel into areas of lower pressure, such as, but not limited to, the atmosphere by venting, the inlet to the device, or another control volume or hose. In certain embodiments this flow control device 2213 can be a valve that can be controlled directly by the tire pressure using a piston, or membrane 2214 that will exert a force and open the flow control device 2213 when the tire has sufficient pressure in it. Opening this flow control valve will divert some, or all, of the fluid from the pumping chamber to somewhere other than the tire. According to some embodiments of the present invention the fluid can be rerouted to the inlet of the device using a passage 2215.

[00110] FIG. 45 illustrates a tire inflation system that comprises a tire 2300 mounted on a wheel 2301 , a pump or compressor housing 2302, an input shaft to the pump (compressor) 2305 that rotates substantially collinear to the center line 2304 of the wheel, and an arm or connection 2305 that connects the pump input shaft 2305 to a mass 2306 such that the moment created by the mass prevents the pump input shaft from rotating if the torque requirements for the pump are not too large, according to embodiments of the present invention. Because the housing does rotate, there is relative motion of the pumping members that allows air to be pumped into one or more tires. Non-limiting examples of pumps that can be used include, but are not limited to, piston pumps, diaphragm pumps, vane pumps, squirrel cage pumps, ball pumps, scroll compressors, fans and blowers. According to one embodiment of the present invention, the device includes a mechanism to adjust the amount of torque that the mass on the lever arm can impart upon the pumping mechanism, and therefore limit the amount of pressure that can be achieved and/or delivered to the tire. This may be done, for example, by using a torque limiting coupling between the arm and the pump inlet, adjusting the distance that the mass is from the axis of rotation, and/or adjusting the amount of mass used. Additional embodiments include using a biasing mechanism to bias the mass to a larger distance from the axis of rotation and using the tire pressure to actuate a piston or diaphragm to move the weight closer to the centerline as the pressure in the tire rises. Non-limiting examples of biasing devices include, but are not limited to, springs, membranes, pistons, and elastic members.

[00111] Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.

Claims

CLAIMS What is claimed is:

1. A device for tire inflation, comprising: a one-way valve in fluid communication with a tire; a housing comprising a first opening and a second opening, the first opening in fluid communication with the one-way valve, wherein the one-way valve permits one-way fluid flow from the housing into the tire; a piston moveable within the housing between at least a first position and a second position, wherein movement of the piston from the first position to the second position pumps fluid from within the housing into the tire through the one-way valve; and a detent mechanism configured to releasably hold the piston in the first position, wherein the housing is mounted on a tire in a position and orientation that causes forces generated by rotation of the tire to act on the piston to release the piston from the detent mechanism and move the piston from the first position to the second position.

2. The device of claim 1 , wherein an inner diameter of the housing and an outer diameter of the piston are cylindrical.

3. The device of claim 2, wherein a central axis of the inner diameter intersects an axis of rotation of the tire.

4. The device of claim 1 , wherein the detent mechanism comprises a magnet.

5. The device of claim 4, wherein the piston comprises the magnet, and wherein the housing comprises a magnetic material in proximity with the magnet when the piston is in the first position.

6. The device of claim 4, wherein the housing comprises the magnet, and wherein the piston comprises a magnetic material in proximity with the magnet when the piston is in the first position.

7. The device of claim 4, wherein the magnet is a first magnet, the detent mechanism further comprising a second magnet, wherein the piston comprises the first magnet and the housing comprises the second magnet, and wherein the first magnet is in proximity with the second magnet when the piston is in the first position.

8. The device of claim 1 , further comprising a biasing element configured to bias the piston toward the first position, wherein the biasing element is independent of the detent mechanism.

9. The device of claim 8, wherein the biasing element is a spring.

10. The device of claim 1 , wherein the one-way valve is a first one-way valve, wherein the piston comprises a first end closer to the first opening and a second end closer to the second opening, the piston further comprising a third opening between the first and second ends and a second one-way valve in the third opening, wherein the second one-way valve permits one-way fluid flow into the second opening and through the third opening from the second end to the first end as the piston moves from the second position toward the first position.

1 1 . A device for tire inflation, comprising: a housing adapted to be fluidly coupled to a tire by an air flow control mechanism which permits air flow from the housing into the tire while substantially inhibiting air flow from the tire into the housing; an air displacement mechanism moveable with respect to the housing, the air displacement mechanism configured to pump air through the housing and into the tire using force generated by rotation of the tire; and a detent mechanism configured to limit displacement of the air displacement mechanism until the force generated by rotation of the tire exceeds a predetermined threshold.

12. The device of claim 11 , wherein the air displacement mechanism is a diaphragm mechanism.

13. The device of claim 11 , wherein the air displacement mechanism is a piston.

14. The device of claim 13, wherein the housing is a cylinder, and wherein an outer perimeter of the piston is circular.

15. The device of claim 13, wherein the air flow control mechanism is a first air flow control mechanism, wherein the piston comprises a first end, a second end, an aperture formed through the piston between the first end and the second end, and a second air flow control mechanism which permits air flow through the aperture from the second end to the first end while substantially inhibiting air flow through the aperture from the first end to the second end, wherein the piston moves in a direction from the second end toward the first end to pump air into the tire.

16. The device of claim 11 , wherein the air flow control mechanism is a check valve.

17. The device of claim 15, wherein the second air flow control mechanism is a check valve.

18. The device of claim 13, wherein the air flow control mechanism is a first air flow control mechanism, wherein the piston moves with respect to the housing between an inner position and an outer position, such that the piston pumps air into the tire as it moves from the inner position to the outer position, the device further comprising a second air flow control mechanism which permits air flow into the housing as the piston moves from the outer position to the inner position while substantially inhibiting air flow out of the housing as the piston moves from the inner position to the outer position.

19. The device of claim 13, wherein the piston moves with respect to the housing between an inner position and an outer position, such that the piston pumps air into the tire as it moves from the inner position to the outer position, the device further comprising a biasing element configured to bias the piston toward the inner position.

20. The device of claim 19, wherein the biasing element is independent of the detent mechanism.

21 . The device of claim 19, wherein the biasing element is a spring.

22. The device of claim 11 , wherein the detent mechanism comprises a magnet.

23. The device of claim 22, wherein the magnet is comprised by the piston, the detent mechanism further comprising a magnetic material comprised by the housing.

24. The device of claim 23, wherein the housing comprises a first end adapted to be fluidly coupled to the tire and a second end, wherein the magnet is coupled to the second end of the piston, and wherein the magnetic material is located at the second end of the housing.

25. The device of claim 11 , wherein the detent mechanism comprises a spring loaded ball between the piston and the housing.

26. The device of claim 11 , wherein the detent mechanism comprises a leaf spring between the piston and the housing.

27. The device of claim 13, wherein the piston moves with respect to the housing between an inner position and an outer position, such that the piston pumps air into the tire as it moves from the inner position to the outer position, wherein a maximum displacement between a maximum inner position and a maximum outer position is adjustable.

28. The device of claim 27, wherein housing is adapted to threadably engage with a valve stem of the tire, and wherein the maximum displacement is adjustable by changing a position of the housing with respect to the valve stem.

29. The device of claim 27, wherein a hard stop is threadably engaged with the housing, and wherein the maximum displacement is adjustable by changing a position of the hard stop with respect to the housing.

30. The device of claim 11 , further comprising a pressure sensor configured to sense a pressure inside the housing between the tire and the air displacement mechanism.

31 . The device of claim 11 , further comprising a pressure sensor configured to sense a tire pressure.

32. The device of claim 11 , further comprising a position sensor configured to measure a position of the air displacement mechanism with respect to the housing.

33. The device of claim 11 , wherein the device is embedded within a wheel to which the tire is attached.

34. The device claim 13, wherein the piston moves with respect to the housing between an inner position and an outer position, such that the piston pumps air into the tire as it moves from the inner position to the outer position, the device further comprising: a rotating member rotatably coupled to a wheel of a vehicle, the wheel attached to the tire; and a clutching mechanism configured to mechanically couple the wheel to the rotating member when a rotational speed of the wheel is greater than or equal to a rotational speed of the rotating member, wherein rotation of the rotating member moves the piston between the inner and outer positions.

35. The device of claim 34, wherein the rotating member comprises a cam, and wherein the cam moves the piston between the inner and outer positions as the rotating member rotates.

36. The device claim 1 1 , further comprising: a rotating member rotatably coupled to a wheel of a vehicle, the wheel attached to the tire; and a mechanism configured to mechanically couple the wheel to the rotating member to impart rotational energy from the wheel into rotation of the rotating member, wherein rotation of the rotating member actuates the air displacement mechanism.