TIRE AIR INTAKE FILTER
STATEMENT REGARDING FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
[0001] This invention was made with Government support under DE-EE0005447
awarded by DOE. The Government has certain rights in this invention.
BACKGROUND
[0002] Air Maintenance Technology (AMT) is a system to use a pump that is built
into a tire to automatically maintain a vehicle's tire pressure at a target pressure. A
regulator senses when the tire is at the target pressure. If the pressure drops below
the target level, an inlet filter in the regulator allows some outside air into the pumping
tube which runs circumferentially around the inside of the tire. Deformations of the
tube as the tire rolls produce compress air inside the tube. The air may be discharged
through the regulator into the tire cavity to inflate the tire.
SUMMARY
[0003] A tire air intake filter includes a housing to be attached to a sidewall of an Air
Maintenance Technology (AMT) pneumatic tire. The housing has a cavity to be in fluid
communication with an atmospheric air inlet of a regulator for the AMT tire. A filtration
media is to block contaminants from entering the cavity while allowing atmospheric air
to be drawn through the filtration media into the cavity by a pump of the AMT tire. The
filter has an elliptical profile having a minor axis and a major axis. The minor axis is to
be aligned with a radius of the tire. An AMT tire having the air intake filter is also
disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Features and advantages of examples of the present disclosure will become
apparent by reference to the following detailed description and drawings, in which like

reference numerals correspond to the same or similar, though perhaps not identical,
components. For the sake of brevity, reference numerals or features having a
previously described function may or may not be described in connection with other
drawings in which they appear.
[0005] Fig. 1 is a perspective view of an example of an intake filter of the present
disclosure;
[0006] Fig. 2 is a top view of the example of the intake filter depicted in Fig. 1
according to the present disclosure;
[0007] Fig. 3 is a cross-sectional view of the example of intake filter depicted in Fig.
2 according to the present disclosure;
[0008] Fig. 4 is an end view of a wheel and tire with an example of an intake filter
disposed thereon according to an example of the present disclosure;
[0009] Fig. 5 is a cross-sectional view of a wheel and tire depicting an AMT
regulator disposed on the according to the present disclosure;
[0010] Fig. 6 is a semi-schematic cross-sectional view of an example of an intake
filter on a tire according to the present disclosure;
[0011] Fig. 7 is a plan view of an example of a snap-on filter cover of the present
disclosure;
[0012] Fig. 8 is a cross-sectional view of an example of an intake filter with a snap-
on filter cover, the intake filter mounted in a socket in a tire according to the present
disclosure;
[0013] Fig. 9 is a cross-sectional view of another example of an intake filter with a
snap-on cover of the present disclosure;
[0014] Fig. 10 is a cross-sectional view of an example of an intake filter with a
snap-on filter cover, the intake filter mounted in a socket in a tire according to the
present disclosure; and
[0015] Fig. 11 is a plan view of another example of a snap-on filter cover of the
present disclosure.

DETAILED DESCRIPTION
[0016] The present disclosure relates generally to an intake filter for an air pump.
Such a filter may be used, for example, with an AMT system used with the tires of a
commercial truck. It is to be understood that intake filters according to the present
disclosure may be used with various sizes of tires for various types of vehicles.
[0017] Figs. 1, 2 and 3 depict an example of an intake filter 17 of the present
disclosure. Clean (filtered) air is communicated from the intake filter 17 through port
23, via inlet 22 to an intake of a regulator 10 (see Fig. 6) for a pneumatic tire 50 (see
Fig. 4) in an AMT system. The regulator 10 may regulate airflow into and out of a
pump (not shown) and thereby regulate air pressure in the pneumatic tire 50. The
example of the intake filter 17 depicted in Figs. 1, 2 and 3 includes a housing 12, and a
filtration media 16. As used herein, environment means ambient air including any
contaminants present (e.g., e.g., dirt, dust, road debris, mud, water, other fluids and
particulate matter, etc.). Also, outside means the space that is not enclosed by the tire
50 or the intake filter 17. Tires 50 operating in the environment are subjected to
various contaminants in various forms. For example, a cloud of dust may envelop the
tire 50. In other examples, a tire 50 may travel through rainy conditions or through
puddles of dirty water or mud, creating a splash or cloud of contaminants from
operation of the tire 50, or from operation of another tire nearby. The tire that causes
the splash or cloud may be on the same vehicle as the intake filter 17, or on another
vehicle.
[0018] The intake filter 17 may include a cover 19 disposed adjacent to the filtration
media 16. In an example, the housing 12 may have an elliptical profile. The intake
filter 17 may be any size with sufficient airflow capacity to allow the AMT pump to
operate without significant restriction to the airflow. An example of significant
restriction is in a range from about 10 inches of water to about 30 inches of water or
greater pressure drop at the maximum flow rate through a clean, dry filter. In an
example, the major axis 67 of the ellipse may be about 3 cm and the minor axis 59
may be about 1 cm. In another example, the intake filter 17 may be an ellipse with a
major axis 67 ranging from about 20 mm to about 50 mm, a minor axis 59 ranging

from about 5 mm to about 20 mm, and a depth ranging from about 5 mm to about 15
mm. In an example, an area of filter media exposed to the outside environment
ranges from about 50 square mm (millimeters) to about 100 square mm.
[0019] The intake filter 17 may be embedded in a tire sidewall. For example, the
intake filter 17 may be molded in place in the sidewall (see e.g. Fig. 6), or installed into
a complementary shaped socket 31 (see e.g. Figs. 8 and 10) in the sidewall. Without
being held bound to any theory, it is believed that radial strains are larger in some tire
sidewalls than tangential strains. The elliptical shape of the intake filter 17 disclosed
herein reduces stresses in the tire 50 and on the intake filter 17. By aligning the minor
axis 59 of the elliptically shaped intake filter 17 with a radius of the tire 50, the radial
load applied by the tire on the intake filter 17 is minimized. It is also believed that by
aligning the minor axis 59 of the elliptically shaped intake filter 17 with a radius of the
tire 50, stress risers in the sidewall from the intake filter 17 are minimized.
[0020] In examples of the present disclosure, the cover 19 may be made of a
flexible material, or the cover 19 may be substantially rigid. The cover 19 may be
attached to the housing 12 to retain the filtration media 16 and to allow air to flow
through the filtration media 16.
[0021] As shown for example in Fig. 4, the housing 12 may be accommodated on,
or fitted in a sidewall of a pneumatic tire 50 for connection to a regulator 10 (see Fig.
6) inside the tire 50. The housing 12 may be molded into the sidewall of the tire 50
during the production process of tire 50. Other attachment mechanisms will be
discussed further below.
[0022] It is to be understood that the mass of air pumped into the tire cavity 52 (see
Fig. 5) by the pump (and therefore through the intake filter 17) according to the present
disclosure in a single revolution may be relatively small compared to the mass of air in
a fully inflated tire 50. In an example, an AMT system may pump enough air to make
up for normal losses in a tire. For example, an AMT system may pump about 1 psi
into a 100 psi tire over a month. A range of airflow from about 250 SCCM (Standard
Cubic Centimeters per Minute) to about 1000 SCCM may flow through the intake filter
17. In terms of mass airflow the same example would range from about 0.3 g (gram)

to about 1.3 g of dry air at STP (Standard Temperature and Pressure). In an example,
a commercial truck tire may contain 150 liters of air at about 100 psi (689 kilopascals)
under normal operating conditions.
[0023] The filtration media 16 may be disposed in contact with the cover 19 of the
intake filter 17. The cavity 26 is in fluid communication with at least one port 23 (see
Fig. 6) providing air to the pump via the regulator 10 of the tire 50. The filtration media
16 may block contaminants from entering the cavity 26 while allowing atmospheric air
to be drawn through the filtration media 16 into the cavity 26 by a pump of the AMT
system. In an example, the filtration media 16 may substantially block contaminants
from entering the cavity 26 while allowing a small amount of contaminants to pass
through the filtration media 16. As used herein, substantially block means
contaminants in the form of particulate matter will be blocked if the particulate matter is
larger than a predetermined size. For example, the efficiency of the filtration media 16
may be at least about 90 percent when exposed to 150 grams of dust at a maximum
flow rate using SAE J726 JUN2002, Air Cleaner Test Code, Section 5.4. After
exposure to the dust, the pressure drop across the filter is within about 70% of the
pressure drop at clean filter conditions. Pressure drop is measured at maximum flow
rate. The pressure drop across clean intake filter 17 may be less than about 1 psi
when measured at maximum flow rate. It is to be understood that the pump is
operatively connected to the regulator 10.
[0024] Fig. 7 shows an example of a snap-on filter cover 19 of the present
disclosure. The filtration media 16 may be disposed between the filter cover 19 and
the housing 12. The cover 19 may define apertures 32 to expose the filtration media
16 to the atmosphere impinging upon the tire 50. The apertures 32 also may be used
as removal tool access points for removing the cover 19 from the intake filter 17 for
servicing or replacing the filtration media 16. Retention features 64 are tabs that
engage slots 62 as shown in Fig. 8. The filter cover 19 may have a plurality of
apertures defined therein to operate as an intake screen 18. The intake screen 18 may
protect the filter media 16 from impacts and abrasion prior to and during installation in

the tire 50 as well as from large pieces of debris that may be contact the filter cover
19.
[0025] A membrane may be used as a filtration media 16 to block water or other
contaminants. As used herein, membrane means a layer of material which serves as
a selective barrier between two phases (e.g., liquid water and vapor) and remains
impermeable to specific particles, molecules, or substances when exposed to the
action of a driving force. The membrane, in an example, may be about 0.5 mm thick
and may be fixed to the cover 19 with an adhesive. In another example, the
membrane may be attached to the cover 19 by welding (e.g. heat stake).
[0026] The filtration media 16 may include a membrane layer; woven fiber layer; a
non-woven fiber layer; a reticulated foam layer; an activated carbon layer; a porous
solid layer; or combinations thereof. Examples of fiber layers may include a
Polytetrafluoroethylene (PTFE) fiber (e.g., Teflon® fiber, available from E. I. du Pont
de Nemours and Company, Wilmington, Delaware and may include Gore-Tex® brand
materials, available from W. L. Gore & Associates, Inc., Elkton, Maryland. Examples
of the porous solid layer may include compressed carbon charcoal. In an example,
the filtration media 16 may include a layer of activated carbon disposed between two
woven fiber layers. An example of a membrane layer may include a non-woven nylon,
e.g. Versapor® 450R from Pall.
[0027] Referring now to Fig. 6, the intake filter 17 is depicted as fitted in the
sidewall of tire 50. Loading of the tire 50 through the wheel 98 (see Fig. 5) may
compress the tire 50 against the road surface 40, causing deflection of at least a
portion of the tire 50. Under load, the tire 50 forms a contact patch on the road surface
40 to distribute the load from the tire 50 to the road surface 40. As used herein, the
contact patch means the total area of the tire tread in contact with a road surface,
including the area of grooves or other depressions and may be load and inflation
dependent. As used herein, road surface 40 means any surface upon which a tire 50
attached to a vehicle is operated. For example, a road surface 40 may be paved,
unpaved, dirt, mud, sand, cinders, gravel, clay, stone, concrete, tarmac, macadam,
paint, rubber, plastic, wood, metal, expanded metal, glass, ice, snow etc., and

combinations thereof. Fig. 6 depicts the connection of intake filter 17 via port 23 and
inlet 22 through a sidewall of the tire 50 to the regulator 10.
[0028] The intake filter 17 may, under certain conditions, receive a flow of air from
the regulator 10 to pass in turn from the cavity 26 through the filtration media 16 to
clean the filtration media 16. As such, the intake filter 17 may be self-cleaned by
reversing the direction of airflow through the filter 17. The self-cleaning may occur
periodically, e.g., with every revolution of the tire 50 as long as the air inspired in that
revolution is not used during the revolution to fill the tire 50.
[0029] In examples of the present disclosure, the intake filter 17 assembly may be
modular, thereby allowing simple replacement of the filtration media 16. In an
example, the filtration media 16 is replaceable without permanently disabling a portion
of the intake filter 17 other than the filtration media 16 to be replaced. For example,
the housing 12 may be permanently fixed in the tire 50, e.g., by a molding and curing
process, whereas the cover 19 may be removable to provide access to the filtration
media 16 for replacement.
[0030] As shown Figs. 8, 9, and 10 together, slots 62 of housing 12 engage
retention feature 64 of the cover 19. The retention feature 64 may be a resilient tab,
interoperable with slot 62 to deform and enter the space created by slot 62 to form a
snap lock between the cover 19 and the housing 12. Alternatively, the retention
feature 64 may be stiffer than the housing 12 and therefore the housing 12 may
deform around retention feature 64 during assembly. The snap retention of the cover
19 onto the housing 12 allows retention without separate fasteners, eases assembly,
and facilitates serviceability of the intake filter 17. The removable cover 19 allows the
filtration media 16 to be replaced without destroying the intake filter 17.
[0031] Fig. 8 is a semi-schematic cross-sectional view of an example of an intake
filter 17 captured in a socket 31 by a resilient web 21. The regulator housing 12
engages an example of a snap-on filter cover 19 of the present disclosure. The
resilient web 21 surrounds the filter cover 19, forming a seal between the filter cover
19 and the resilient web 21. The resilient web 21 is fixedly attached to the sidewall
surrounding the socket 31. As such, the resilient web 21 retains the filter 17 in the

socket 31 and seals the volume of the socket 31 surrounding the filter 17. The
resilient web 21 is curved to form an arch in the cross section shown such that the
arch is concave toward the port 23. The resilient web 21 defines a mouth 57 of the
socket 31. The curvature of the resilient web 21 causes the mouth 57 to enlarge when
the filter cover 19 is pressed toward the cavity 26, and causes the mouth 57 to
constrict when the filter cover 19 is moved away from the port 23. In this way, the filter
is trapped in the socket 31 by the resilient web 21. Slots 62 engage retention feature
64 of filter body 28. The retention feature 64 may be a resilient tab, interoperable with
slot 62 to deform and enter the space created by slot 62 to form a snap lock between
the cover 19 and the filter body 28. In the example depicted in Fig. 8, the filter cover
19 is received in the filter body 28. The example depicted in Fig. 8 is an internal snap-
lock filter cover 19.
[0032] Fig. 9 is a semi-schematic cross-sectional view of an example of an intake
filter 17 captured in the regulator housing 12 by another example of a snap-on filter
cover 19 of the present disclosure. As shown in Fig. 9, the retention feature 64 may
be a tab that is interoperable with slot 62 to enter the space created by slot 62 to form
a snap-lock between the cover 19 and the housing 12.
[0033] Fig. 10 is a semi-schematic cross-sectional view of an example of an intake
filter 17 captured in the socket 31 by a resilient web 21. The regulator housing 12
engages another example of a snap-on filter cover 19 of the present disclosure. The
resilient web 21 surrounds the filter 17, forming a seal between the filter 17 and the
resilient web 21. The resilient web 21 is curved to form an arch in the cross-section
shown such that the arch is concave toward the port 23. The resilient web 21 defines
a mouth 57 of the socket 31. The curvature of the resilient web 21 causes the mouth
57 to enlarge when the filter cover 19 is pressed toward the port 23, and causes the
mouth 57 to constrict when the filter cover 19 is moved away from the port 23. In this
way, the filter 17 is trapped in the socket 31 by the resilient web 21. Slots 62 engage
retention feature 64 of filter body 28. The retention feature 64 may be a resilient tab,
interoperable with slot 62 to deform and enter the space created by slot 62 to form a
snap lock between the cover 19 and the filter body 28. In the example depicted in Fig.

10, the filter body 28 is received in the filter cover 19. The example depicted in Fig. 10
is an external snap lock filter cover 19.
[0034] Fig. 11 is a plan view of another example of a snap-on filter cover 19 of the
present disclosure.
[0035] It is to be understood that the terms "connect/connected/connection" and/or
the like are broadly defined herein to encompass a variety of divergent connected
arrangements and assembly techniques. These arrangements and techniques
include, but are not limited to (1) the direct communication between one component
and another component with no intervening components therebetween; and (2) the
communication of one component and another component with one or more
components therebetween, provided that the one component being "connected to" the
other component is somehow in operative communication with the other component
(notwithstanding the presence of one or more additional components therebetween).
[0036] In describing and claiming the examples disclosed herein, the singular forms
"a", "an", and "the" include plural referents unless the context clearly dictates
otherwise.
[0037] It is to be understood that the ranges provided herein include the stated
range and any value or sub-range within the stated range. For example, a range from
about 250 SCCM to about 1000 SCCM should be interpreted to include not only the
explicitly recited limits of about 250 SCCM and about 1000 SCCM, but also to include
individual values, such as 250 SCCM, 375 SCCM, 750 SCCM, etc., and sub-ranges,
such as from about 270 SCCM to about 500 SCCM, etc. Furthermore, when "about" is
utilized to describe a value, this is meant to encompass minor variations (up to +/-
10%) from the stated value.
[0038] Furthermore, reference throughout the specification to "one example",
"another example", "an example", and so forth, means that a particular element (e.g.,
feature, structure, and/or characteristic) described in connection with the example is
included in at least one example described herein, and may or may not be present in
other examples. In addition, it is to be understood that the described elements for any

example may be combined in any suitable manner in the various examples unless the
context clearly dictates otherwise.
[0039] While several examples have been described in detail, it will be apparent to
those skilled in the art that the disclosed examples may be modified. Therefore, the
foregoing description is to be considered non-limiting.

What is claimed is:
1. A tire air intake filter, comprising:
a housing to be attached to a sidewall of an Air Maintenance Technology (AMT)
pneumatic tire, the housing having a cavity to be in fluid communication with an
atmospheric air inlet of a regulator for the AMT tire;
a filtration media to block contaminants from entering the cavity while allowing
atmospheric air to be drawn through the filtration media into the cavity by a pump of
the AMT tire wherein:
the filter has an elliptical profile having a minor axis and a major axis; and
the minor axis is to be aligned with a radius of the tire.
2. The intake filter as defined in claim 1 wherein the filtration media
comprises:
a membrane layer;
a woven fiber layer;
a non-woven fiber layer;
a reticulated foam layer;
an activated carbon layer;
a porous solid layer; or
combinations thereof.
3. The intake filter as defined in claim 1, further comprising a snap-on cover
having:
a plurality of apertures defined therein to expose the filtration media to the
atmosphere impinging upon the tire;
a retention tab disposed on the snap-on cover to engage a slot defined in the
housing in a snap-fit relationship wherein the snap-on cover is an intake screen to
protect the filter media from impacts and abrasion.
4. The intake filter as defined in claim 3 wherein the plurality of apertures are

aligned with a direction of a flow stream of water that is induced by rotation of the tire
to cause the flow stream to wash debris from the plurality of apertures.
5. The intake filter as defined in claim 1 wherein the intake filter is
to receive a flow of air from the regulator to pass from the cavity through the filtration
media to clean the filtration media.
6. The intake filter as defined in claim 1 wherein the filtration media is
replaceable without permanently disabling a portion of the intake filter other than the
filtration media to be replaced.
7. An Air Maintenance Technology (AMT) tire, comprising:
a pneumatic tire having an elliptical socket defined in a sidewall of the
pneumatic tire;
an air regulator disposed in a pressurizable cavity of the tire;
an air intake filter disposed in the elliptical socket wherein the intake filter
includes;
a housing having an elliptical profile and having a cavity to be in fluid
communication with an atmospheric air inlet of the regulator;
a filtration media to block contaminants from entering the cavity while
allowing atmospheric air to be drawn through the filtration media into the cavity
by a pump of the AMT tire wherein:
the elliptical profile has minor axis and a major axis; and
the minor axis is to be aligned with a radius of the tire.

ABSTRACT

A tire air intake filter includes a housing to be attached to a sidewall of an Air
Maintenance Technology (AMT) pneumatic tire. The housing has a cavity to be in fluid
communication with an atmospheric air inlet of a regulator for the AMT tire. A filtration
media is to block contaminants from entering the cavity while allowing atmospheric air
to be drawn through the filtration media into the cavity by a pump of the AMT tire. The
filter has an elliptical profile having a minor axis and a major axis. The minor axis is to
be aligned with a radius of the tire. An AMT tire having the air intake filter is also
disclosed.