Tire monitoring device air breathing tube

A tire monitoring device includes a housing mounted within a cavity of a tire/wheel assembly. A sensor within the housing senses a condition within the cavity via an open passage in the housing. A hollow first tube extends away from the housing coaxial to an axis of the open passage. The first tube has an internal bore aligned with the open passage, and includes: a first tubular portion having a first cross sectional width; and a second tubular portion having a second cross sectional width smaller than the first cross sectional width. The second tubular portion further has a free end opening positioned in the cavity above a level of a liquid present in the cavity when the tire monitoring device is positioned at a lowest point in the cavity. The opening has a cross sectional width sized to prevent entrance of the liquid past the opening.

FIELD

The present disclosure relates to wireless vehicle tire monitoring systems.

BACKGROUND

In some vehicle tires, especially heavy duty off-road vehicles including those used as large dump or hauling trucks, front end loaders, and those used in mining vehicles, a liquid is commonly present inside the tire to assist in cooling the tire/wheel assembly. The liquid can have some or all of the following functions: tire cooling, tire sealing, lubrication, anti-rust or descaling, tire bladder conditioning and the like. It is known to install wireless tire monitoring sensors having a sensing chip that can sense tire chamber conditions and also wirelessly transmit data such as tire pressure and temperature to remote receivers, for example receivers located in a vehicle cab or to further remote monitoring systems. Present wireless air pressure monitoring sensors have a short air passage for communication between the air inside the tire chamber and the sensing chip. It is possible for the liquid in the tire chamber to submerge the tire pressure monitoring sensor or splash on it and thus have the liquid enter the sensor through the breathing hole. Entrance of the cooling liquid can clog the air breathing hole and/or damage the internal electronic unit. If the air pressure monitoring sensor is submerged in the liquid, if additional air is pumped into the tire, the increased air pressure forces the liquid into the air pressure monitoring sensor through the breathing hole. Further, even if the air pressure monitoring sensor is not submerged in the liquid, when the tire rotates the liquid can be splashed on the air pressure monitoring sensor and enter the air pressure monitoring sensor.

U.S. Pat. No. 7,538,660 discloses a communication hole 71 and a U-shaped pipe 580 intended to prevent entrance of a tire repair agent. These features do not prevent entrance of liquid into the communication hole, particularly if the pipe 580 is submerged in a liquid. U.S. Pat. No. 8,138,904 discloses branched path sections and wall sections intended to minimize entrance of fluids by providing direct impingement of incoming fluid against the perpendicularly configured wall sections and the tortuous path of branched path sections. These features also do not prevent the entrance of liquid if the sensor is submerged.

SUMMARY

According to several aspects, a tire monitoring device includes a housing mounted within a cavity of a tire/wheel assembly. A sensor is positioned within the housing adapted to sense a condition within the cavity of the tire/wheel assembly via an open passage created in the housing. A hollow linearly extending breathing tube is connected to the housing having an internal bore aligned with the open passage. The breathing tube includes an opening at a free end. The opening is sized to prevent entrance of a liquid present in the cavity from entering the opening.

According to other aspects, a tire monitoring device includes a housing mounted within a cavity of a tire/wheel assembly. A sensor is positioned within the housing adapted to sense a condition within the cavity via an open passage created in the housing. A hollow first tube extends away from the housing coaxial to an axis of the open passage, the first tube having an internal bore aligned with the open passage. The first tube includes: a first tubular portion having a first cross sectional width; and a second tubular portion having a second cross sectional width smaller than the first cross sectional width. The second tubular portion further has an opening at a free end. The opening is positioned in the cavity above a level of a liquid present in the cavity when the tire monitoring device is positioned at a lowest point in the cavity, and the opening has a cross sectional width sized to prevent entrance of the liquid past the opening.

According to further aspects, a tire monitoring system includes a tire/wheel assembly having a liquid occupying a portion of an internal cavity of the tire/wheel assembly. The liquid pools in the internal cavity when the tire/wheel assembly is in a non-rotating condition. A tire monitoring device positioned in the internal cavity includes: a housing mounted to a tire wall; a hollow breathing tube connected to the housing and aligned with the open passage; and a hollow linearly extending breathing tube connected to the housing having an internal bore aligned with the open passage. The breathing tube includes an opening at a free end. The opening is sized to prevent entrance of a liquid present in the cavity from entering the opening. A total length of the breathing tube is predetermined to position the opening of the breathing tube freely away from a surface of the liquid created by pooling of the liquid when the tire/wheel assembly is stationary and the housing is positioned at a lowest elevation of the internal cavity.

DETAILED DESCRIPTION

A wireless transmission tire system such as a tire pressure monitoring system (TPMS) of the present disclosure can be mounted to an inner side or tread wall, or to the metal wheel of each of the tires of a vehicle, typically large commercial vehicle tires used such as in mining dump trucks, heavy machinery such as front end loaders, and hauling trucks. A tire pressure monitor as used herein broadly also includes temperature, motion, and other similar sensors that are commonly used to provide remote transmission of the operating conditions of vehicle tires. The breathing tube of the present disclosure is an axially elongated tube connected to the body or wall of the monitoring device that acts to minimize or prevent entry of fluid/contaminants that are present in the inner space of the tire from entering the inlet pressure port of the monitoring device.

Referring toFIG. 1, a monitoring system “S” consists of a tire monitoring device10having a sensor12positioned in a body or housing14. The housing14can be mounted using a bracket assembly having brackets16a,16bconnected at a bracket body18by fasteners20to a resilient material “patch” or mounting pad22that is in turn fixed or releasably connected such as by an adhesive layer24or by thermal bonding to an inner wall26of a tire28. According to several aspects, inner wall26is an inner tread wall of tire28.

The sensor12is positioned in an inner cavity30of the housing14to protect the sensor12. In order to sense the conditions of an inner volume32of the tire28, an open passage34is created through a wall36of housing14. In order to mount a member acting to prevent fluid such as water, coolant, or contaminants that are present in inner volume32from entering cavity30of tire monitoring device10, a stub38is attached to wall36in coaxial alignment with open passage34. Stub38may include external threads40.

Referring toFIG. 2and again toFIG. 1, tire monitoring device10may be fixed to an inner tread wall of tire28; therefore, a coolant liquid42present in the inner volume32of tire28can at least partially submerge tire monitoring device10during a portion of a rotational cycle of tire28such as when the tire28is stationary and tire monitoring device10is at a lowest elevation of tire28. Under some operating conditions, liquid42can cover or submerge tire monitoring device10such that liquid42could enter open passage34and cavity30to contact sensor12. Presence of liquid42in contact with sensor12can alter the pressure signal created by sensor12and/or damage sensor12. In order to prevent this occurrence, a breathing tube44is connected to and extends away from stub38. Breathing tube44includes a first tubular portion46connected to stub38, and according to several aspects a smaller cross section second tubular portion48extending from first tubular portion46, and defining a free or open end of breathing tube44. Breathing tube44has a first internal bore50which is in communication through open passage34with cavity30. According to several aspects, a length of breathing tube44is predetermined to position at least second tubular portion48extending above a surface52defining a maximum expected column height of liquid42in tire28. According to other aspects, breathing tube44is designed to have at least a portion of first tubular portion46extending above surface52.

Referring toFIG. 3and again toFIGS. 1 and 2, first and second tubular portions46,48can have a circular, oval, rectangular, triangular, or other geometric shaped cross section having a hollow, longitudinally and linearly extending bore. According to several aspects, a circular cross section is shown, but is not limiting. First tubular portion46of breathing tube44includes first internal bore50defining a first cross sectional width “A” which corresponds to a diameter when first tubular portion46has a circular cross section. Second tubular portion48integrally extends from first tubular portion46at a free end of breathing tube44and includes a second internal bore54defining a second cross sectional width “B”. Breathing tube44extends linearly, and has a longitudinal central axis56that is coaxially aligned with the centerline of open passage34when breathing tube44is installed. A mouth or opening58of second tubular portion48is located at and defines a free end of breathing tube44opening into inner volume32of tire28. Under normal operating conditions of tire monitoring device10, the pressure within first internal bore50equals the pressure within inner volume32of the tire28, therefore the air inside breathing tube44is not pushed/compressed by liquid42, thus liquid42will be blocked by the air inside breathing tube44from entering the tube. Further, because the opening58is small, surface tension of liquid42will further prevent the liquid42from entering the breathing tube44. In addition, a material such as grease or a similar material can be applied to a tube surface proximate to the opening58of breathing tube44to prevent accumulation of liquid42at opening58, and thereby prevent entrance of liquid42into opening58. If in any case there is any liquid present at the opening58of breathing tube44, as pressure within inner volume32reduces naturally over time, as all tires do, this liquid will be forced out as the greater pressure within breathing tube44forces air out to match the reducing pressure of inner volume32.

According to several aspects, second cross sectional width “B” is 3 mm or less and is smaller than first cross sectional width “A”, thereby allowing the natural adhesion and cohesion properties of molecules of the liquid42to be used to prevent entrance of the liquid42through opening58. Cohesion of the liquid molecules acts to bond the water molecules together at opening58, while adhesion of the bonded water molecules to the inner wall of opening58prevents entrance of the liquid. These adhesion and cohesion forces with a selectively sized opening58act to trap liquid42at the opening58having the predetermined second cross sectional width “B”, thereby preventing liquid42from entering first internal bore50of breathing tube44. In further aspects, the second cross sectional width “B” is approximately 2 mm or less.

During those operating times when the tire is not rotating and liquid42can settle or pool at the bottom inner tread wall of tire28, tire monitoring device10can be partially or completely submerged in the pool of liquid42. Breathing tube44is therefore provided having a total length “C” which positions opening58above or free of the surface52of liquid42. Total length “C” can be predetermined by determining a maximum volume of cooling liquid42recommended by the tire manufacturer or tire liquid manufacturer, and using the dimensions of the tire28to calculate where surface52is anticipated. The second tubular portion48has a length “L” which can range from substantially zero to approximately the total length “C”, for example when first cross sectional width “A” is provided only where necessary to provide connection to stub38. According to several aspects, an end portion60connects first and second tubular portions46,48. End portion60can be conical-shaped (shown), or concave shaped, convex shaped, rounded, or flat (oriented transverse to longitudinal central axis56).

With continuing reference toFIG. 3and again toFIGS. 1 and 2, internal threads62can be provided proximate to a connecting end64of first tubular portion46. Internal threads62are coupled with external threads40of stub38. According to further aspects, external threads40and internal threads62can be omitted and breathing tube44can be fixed to stub38at connecting end64, for example by an adhesive, a solder connection, a C-ring snap connection, or a similar fixing method. For example, the threaded connection is not used when other geometric shapes for breathing tube44and stub38are used, for example rectangular, oval, and the like. Connecting end64can therefore have a smooth internal bore to slidably connect to a roughened or smooth surface of stub38in these aspects. In a further aspect, breathing tube44can be directly connected to wall36or inserted into a mating internal counter-bore created in wall36such that stub38can therefore be eliminated entirely as will be described in reference toFIG. 10.

Referring toFIG. 4, a chamber wall66can be provided in the inner cavity30of housing14. Chamber wall66creates a sealed communication passage68between open passage34and sensor12. Chamber wall66isolates sensor12from an encapsulation material70which is normally used to fill the inner cavity30and which also helps isolate sensor12from fluid and/or contaminants that could enter or be present in housing14.

Referring toFIG. 5and again toFIG. 3, according to additional aspects, a breathing tube72can be used in place of breathing tube44. Breathing tube72includes a tubular body74having an end portion76. End portion76, similar to end portion60can be concave shaped (shown), conical-shaped, convex shaped, rounded, or flat (oriented transverse to a tube longitudinal central axis). A mouth or opening78is similar in size to cross sectional width “B” of opening58. The shape of end portion76functions similarly to end portion60to transition from an outer body wall of tubular body74to a breathing tube end80proximate to the opening78. A connecting end82can be similarly configured to connecting end64of breathing tube44.

Referring toFIG. 6and again toFIGS. 3 and 5, according to further aspects, a breathing tube84can be substituted for either breathing tube44or breathing tube72. Breathing tube84defines a “tube-within-a-tube” design that provides an additional level of liquid isolation. Breathing tube84is shown in several aspects having a first tubular portion or outer tube86which in the embodiment shown is similar to breathing tube72in geometry, having outer tube86integrally connected to a curved or oval shaped end portion88. Outer tube86can also be provided in any other geometric shape desired. In addition, breathing tube84can be made using any combination of breathing tube44or breathing tube72for the inner and/or outer tubes as a tube-within-a-tube design. Curved or oval shaped end portion88has a continuously reducing cross sectional width which acts similarly to cross sectional width “B”. A mouth or first opening90is similar in size to opening58and has a continuously reducing cross sectional width which acts similarly to cross sectional width “B”. End portion88can also be shaped similar to any of the shapes provided for end portions60or76. Liquid which may enter first opening90is received in an internal bore92of outer tube86and will initially adhere to an inner wall94of outer tube86. If a sufficient quantity of liquid enters outer tube86, it will collect proximate to a collection end96which is sealed by a collection end wall98from open passage34. Collection end wall98can be oriented perpendicularly to inner wall94and can be connected to or integrally joined to a second tubular portion or inner tube100.

Second tubular portion or inner tube100, according to several aspects, is similar in geometry to breathing tube44, however any geometry can be selected. Inner tube100has a cross sectional width “D” smaller than cross sectional width “A” of breathing tube44such that clearance is provided between inner tube100and the inner wall94. Inner tube100extends through collection end wall98such that an inner bore102of inner tube100communicates with an end cavity104of breathing tube84, whereas internal bore92is isolated from end cavity104by collection end wall98. A second portion106of inner tube100is similar in design and function to second tubular portion48of breathing tube44and includes a cross sectional width “E” which is smaller than cross sectional width “D”. A mouth or second opening110of second portion106is elevated with respect to collection end wall98such that liquid pooling at collection end96is isolated from second opening110.

With continuing reference toFIG. 6and again toFIGS. 1-4, the tube-within-a-tube design provided by inner tube100and outer tube86provides a double opening (first opening90and second opening110) that liquid must traverse to enter open passage34. Because each of the first opening90and second opening110have a reduced cross sectional width compared to outer tube86and inner tube100, which as noted herein is approximately 3 mm or less, a double barrier or double restriction to liquid passage is provided for breathing tube84. According to several aspects a length “F” including inner tube100and a connecting end112is shorter than a total length “G” of breathing tube84. Similar to breathing tubes44and72, breathing tube84can also include internal threads114in end cavity104adapted to couple with the threads40of stub38.

Referring toFIG. 7and again toFIGS. 1 and 3, tire monitoring system “S” having tire monitoring device10can be used for sensing and monitoring tire pressure or other operating conditions within an inner volume or chamber defined by any vehicle tire/wheel assembly, and particularly in slowly rotating tire/wheel assemblies such as a front steerable tire/wheel assembly116or the rear tire/wheel assemblies118of a large heavy material hauling machine120. The wireless transmission signals from tire pressure sensor12can be received in a cab122of hauling machine120and monitored by the occupant of cab122.

Referring toFIG. 8and again toFIG. 7, an exemplary installation of tire monitoring device10in tire/wheel assembly116has housing14perpendicularly oriented to a radial centerline124of mounting pad22and approximately centered on a tire inner tread wall126. This orientation maximizes the spacing between tire monitoring device10and either of opposed first or second tire side walls128,130. Because deflection of the first and second side walls128,130continuously varies during tire rotation and when front tire/wheel assembly116(or rear tire/wheel assembly118) encounters an object, this positioning of tire monitoring device10minimizes deflection which could affect the bond at mounting pad22. The breathing tube44shown (any of breathing tubes44,72or84can be used) has opening58in communication with an inner volume or cavity131of the tire/wheel assembly. The breathing tube44extends axially away from housing14to position opening58above the surface52of, and therefore outside of, the volume of liquid42in a condition anticipated to provide the maximum liquid height, i.e., when tire monitoring device10is positioned at the lowest point of front tire/wheel assembly116(or rear tire/wheel assembly118) where liquid42can “pool” at the inner bottom of the tire tread wall. Surface52is expected to be at a maximum height when the tire/wheel assembly is stopped (non-rotating), allowing maximum pooling of liquid42. At other rotational positions of tire/wheel assembly116, the inlet opening cross sectional width “B” of the breathing tube selected (44,72,84), which is limited to 3 mm or less, will prevent entrance of liquid42into tire monitoring device10, as previously described herein.

Referring toFIG. 9and again toFIGS. 1-8, tire monitoring system “5”, having tire monitoring device10, produces an electric output signal from sensor12indicating a condition such as a tire pressure of front or rear tire/wheel assembly116,118. Tire monitoring device10is releasably mounted using fasteners132to brackets16a,16b. Tire monitoring device10is fixed to mounting pad22such that a longitudinal axis134of housing14is oriented transverse to radial centerline124of mounting pad22which is subsequently aligned with a radial centerline of the tire. Tire monitoring device10is shown prior to installation of any of the breathing tubes44,72, or84.

According to other aspects, tire monitoring device10includes housing14mounted within cavity131of tire/wheel assembly116,118. Sensor12positioned within the housing14is adapted to sense a condition within the cavity131via open passage34created in the housing. Hollow first breathing tube44extends away from the housing14coaxial to axis56of the first breathing tube44and open passage34. The first breathing tube44has first internal bore50aligned with the open passage34. The first breathing tube44includes: first tubular portion46having first cross sectional width “A” and second tubular portion48having second cross sectional width “B” which is smaller than the first cross sectional width “A”. The second tubular portion48has a length “L”. The second tubular portion48further has opening58at the free end, the opening58sized to prevent entrance of liquid42present in the cavity30from entering the opening58.

Referring toFIG. 10, a tire monitoring device136is modified from tire monitoring device10to include a breathing tube140having a continuous inner bore diameter “H” that can be substantially equal to a passage diameter “J” of open passage34. Breathing tube140includes a first end142which is received in a cavity or counterbore144created in housing14, such that breathing tube first end142can be externally threaded to be releasably received in counterbore144, or can be fixedly connected to counterbore144using for example an adhesive. A continuous bore146of breathing tube140extends throughout a length of breathing tube146to a free end148having an opening150, which extends above the surface52of liquid42when tire monitoring device136is positioned at the bottom position of the tire in a tire non-rotating operating condition.

Tire monitoring device air breathing tubes and the systems created by their use provide several advantages. These include: (1) a monitoring system “S” having tire monitoring device10,136positioned within a tire that includes a breathing tube connected to a pressure or sensing port such that the breathing tube extends out of an area or zone where a liquid in the tire may collect and/or submerge the tire monitor; (2) the breathing tube for tire monitoring device10having different first and second cross sectional widths, the second cross sectional width at the outer entrance sized to minimize entrance of liquid or contaminants; (3) a breathing tube for a monitoring device extending a distance in a direct, axial path away from a pressure or entrance port of the sensor such that normal internal pressure within the breathing tube acts to displace fluid or contaminants from the breathing tube; (4) an entrance opening of a breathing tube sized to prevent liquid entrance by the adhesion forces of the liquid and attraction of the liquid to the opening wall; and (5) a tube-within-a-tube aspect that provides a double isolation barrier to the entrance of liquid into the tire monitor.