CA1178079A - Tire pressure communication devices - Google Patents

Tire pressure communication devices

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Publication number
CA1178079A
CA1178079A CA000440136A CA440136A CA1178079A CA 1178079 A CA1178079 A CA 1178079A CA 000440136 A CA000440136 A CA 000440136A CA 440136 A CA440136 A CA 440136A CA 1178079 A CA1178079 A CA 1178079A
Authority
CA
Canada
Prior art keywords
tire
tire pressure
core
pressure
aircraft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000440136A
Other languages
French (fr)
Inventor
Richard L. Crossman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Goodyear Aerospace Corp
Original Assignee
Goodyear Aerospace Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/061,580 external-priority patent/US4237445A/en
Application filed by Goodyear Aerospace Corp filed Critical Goodyear Aerospace Corp
Priority to CA000440136A priority Critical patent/CA1178079A/en
Application granted granted Critical
Publication of CA1178079A publication Critical patent/CA1178079A/en
Expired legal-status Critical Current

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Abstract

TIRE PRESSURE COMMUNICATION DEVICES

ABSTRACT OF THE DISCLOSURE

Disclosed are devices for transmitting signals from a rotatable tire to a stationary recei-ver which correspond to the internal pressure of the tire. In one embodiment, a Bourdon tube communicates with internal tire pressure to regulate the magnetic gap of an electromagnetic induction configuration.
Changes in the magnetic gap result in corresponding changes in an output signal strength. In another embodiment of the invention, a bellows is provided in communication with tire pressure for regulating the position of the core of an LVDT. The core position and, accordingly, the output of the LVDT corresponds to tire pressure. In yet another embodiment, strain gauges or other appropriate electrical signal genera-tors are connected to the tire and interconnected with a rotating race. A plurality of ball bearings are maintained in a preloaded condition between the rotating race and a stationary race, the latter race communicating signals to a tire pressure meter or the like.

Description

~lt~079 1.

BACXG~OUND OF THE INVENTION

The instant invention resides in the art of monitoring devices and is more particularly related to such devices for aircraft. It is extremely impor-tant that aircraft tire pressure be known to the pilot to reduce the possibility of blowouts. It is well known that the likelihood of a blowout substan-tially increases with tire pressure changes above or below a particular desired level, and that such blow-outs not only result in a loss of the tire itself, but seriously increase the likelihood o~ further property damage or human injury.
Heretofore in the art, applicant has not been made aware of any tire pressure monitoring sys-tems which will allow a continual monitoring of the tire pressure during both static and dynamic condi-tions. Brushes have been used in the past to act as commutators for transferring an electrical signal from a rotating to a stationary member. However, t 20 "brush dancing" is experienced when used in the environment of an aircraft wheel and noise or spuri-ous signals are generated which substantially reduce the integrity of the sensing system. Eurther, brush-es are subject to contamination in the wheel environ-ment and are generally characterized by an undesir-ably high resistance path.
The prior art has also taught certain types of interconnections between rotating and stationary members for transmitting tire pressure signals util-izing an induction technique. However, such systems have generally required close tolerances between the static and dynamic coils, which tolerances must not change with movement of the wheel. Accordingly, concentricity problems have made such systems unsuit-able for the aircraft industry.

'7~

Other approaches to sensing and transmit-ting electrical signals indicative of tire pressure have utilized magnets maintained within the wheel, operating upon a magnetic field principle. However, problems have been experienced with the carrying of magnets within the wheel due to size and weight requirements. Such systems have generally not been accepted. Similarly rejected as being insufficient have been the tire pressure indicators utilizing apparatus producing an audible signal. However, such systems have been of a nature that a signal is emit-ted only during the period that the tire is actually going flat or losing pressure. If the operator is not near the tire or vehicle during the period that pressure is being lost, the signal will no~ be dis-cerned by anyone and the usefulness of such system will be totally lost.
It has therefore ~ecome desirable to pro-vîde in the art, a tire pressure communication device which provides substantially noise-free output sig-nals while being of sufficiently simplistic nature '~- that it is capable of operating in the severe envir-onment of an aircraft wheel without reduction of system inteqrity.
ASPECTS OF THE INVENTION

In light of the foregoing, in accordance with one aspect of the invention, there is provided a tire pressure communication device which, without the presence of noise and spurious signals, communicate~
a signal indicative of tire pressure from a rotatable tire to a stationary portion of the aircraft.
In accordance with another aspect of the invention, there is provided a tire pressure communi-cation device wherein no brushes are necessary for .llt~079 electrical communication from a rotating to a stationary structure.
In accordance with still another aspect of the invention, there is provided a tire pressure communication device wherein tolerance and concentricity problems inci-dent to the prior art are overcome and in which the prior art problems of contamination from the ambient are sub-stantially reduced.
In accordance with still another aspect of the invention, there are provided tire pressure communication devices which are reliable in operation, relatively simplistic in design, readily conducive to implementation of presently existing aircraft, and easily implemented using state-of-the-art apparatus.
An aspect of the invention is as follows:
Apparatus for sensing the pressure of an aircraft tire and for communicatir.g such pressure sensing from a rotating tire to a stationary portion of the aircraft, com-prising:
tire pressure sensing means connected to and rota-table with the tire;
a first electrical coil maintained about a core, said core being fixedly secured to the stationary portion of the aircraft;
a second coil maintained about said core and in inductive communication with said first coil; and an expandable and contractable circular member connected to and rotatable with the wheel, said member rotating in a path in juxtaposition to said core and operative therewith for completing a magnetic circuit for communicating a signal indicative of the tire pressure from said sensing means to said first and second coils.
DESCRIPTION OF DRAWINGS
For a complete understanding of the aspects, structure, and techniques of the invention 4.

reference should be had to the following detailed description and accompanying drawings wherein:
Fig. 1 is an illustrative view of a first embodiment of the invention utilizing a tire pressure-controlled Bourdon tube for regulating a magnetic gap;
Fig. 2 is a sectional view of another embod-iment of the in~ention wherein tire pressure is used for regulating a bellows which in turn controls the core of an LVDT; and Fig. 3 is a sectional view of a commutator made in accordance with the invention utilizing pre-loaded ball bearings for achieving necessary elec-trical communication.
DETAILED DESC~I~TIO~ ~F PR~FERRED EMB~IMENTS

Referring now to the drawings and more particularly Fig. 1, it can be seen that a first embodiment of a tire pressure communication device is designated generally by the numeral 10. That device includes a Bourdon tube 12 adapted for interconnec-tion with an aircraft wheel by means of connector straps 14~ The connector straps 14 are of a flexible nature and are adaptable for centering and maintain-ing the tube 12 appropriately within a portion of the wheel housing. Flexibility is desired since, as will be discussed immediately, the diameter of the tube 12 fluctuates with tire pressure and, accordingly, the straps 14 must be flexible to maintain the tube 12 therewithin.
A standard pressure inlet 15 is provided in communication between the tube 12 and the tire. The inlet 15 may pass through the wheel frame and into the envelope defined by the tire and the wheel for making such communication. Such interconnection is, ~1~7~079 5.

of course, well withïn the capabilities of one skilled in the art. Accordingly, there is communi-cated to the Bourdon tube 12 a pressure correspond-ing to the internal pressure of the associated tire~
A magnetic core piece 16, of suitable material for conducting magnetic flux, is fixedly secured to a nonrotating portion of the aircraft in juxtaposition to the portïon of the wheel maintain-ing the tube 12~ While the actual structure to which the core piece 16 wïll be affixed will vary from aircraft to aircraft, suita~le places for maintaining the same would be Eound on the brake frame, axle, torque tubes, or t~e like. Suffice it to say that the core piece 16 is so positioned that a magnetic gap is maintained between the faces of the core piece and the Bourdon tube 12 as the wheel carrying the tu~e is rotated.
Connected a~out the core piece 16 are inductive coils 18,20. One of these coils, in this case coil 18, is an input coil receiving an elec-trical signal from an appropriate signal source on the aircraft. This sïgnal is electromagnetically induced into the output core 20, with the signal strength being controlled ~y the size of the magnetic gap existing between t~e faces of the core 16 and the tubé 12. It will, of course, be understood that the tube 12 is metallic or of other magnetic flux-conducting material.
In operatïon, an input signal of fixed signal strength is provïded over the input lines to the coil 18. An output signal is induced into the coil 20 and sensed over the output lines 24, with the output signal strength being dependent upon the size of the magnetic gap or the proximity of the tube 12 to the faces of the core piece 16. Such proximity, or size of the magnetic gap, is directly 6.

depéndent upon the tire pressure communicated via the inlet 15 to the Bourdon tube 12. Accordingly, the signal strength of the output of the coil 20 may be directly correlated with tire pressure.
The benefit of tAe embodiment of Fig. 1 is that the core piece 16 may be mounted inside, out-side, or alongside of the expandible and contract-ible tube 12. Additionally, the input coil 18 may be excited with a large current so t~at small vari-ances in concentricity of the tube 12 or in the input signal strength will be relatively unimportant when translated to the output signal of the coil 20.
Further, means other than the Bourdon tube 12 might be utilized in the general theme of the invention to effectuate a change in the magnetic gap. For exam-ple, the Bourdon tu~e 12 could be replaced with a bellows in communication with internal tire pressure, such pressure affectuating the expansion or con-traction of the bellows which is maintained in juxta-position with a core piece for regulating a magnetic gap.
With reference now to Fig. 2, it can be seen that a second embodiment of a tire pressure communication device is designated generally by the numeral 30. Here a wheel frame 32 is provided with a characteristic passageway 34 adapted for communi-cating tire pressure from the inner cavity of a tire to a bellows 36. The ~ellows, of rubber~ flexible plastic, or other suitably expandible material, is connected to the movable core 38 of an LVDT. The core 38 is selectïvely positionable in the center of coil 40. These cores are connected to a housing 41 which is fixedly attached to a stationary and non-rotatable member of the aircraft such as an axle, torque tu~e, brake housing, or the like. A sleeve or g~ide 43 is maintained by the housing 41 and is 7.

adapted for receiving the core 38. In one embodi-ment of the inventi.on, the core 38 may rotate with the wheel frame 32 in the guide or sleeve 43~ The sial position of the core in the center of the coil 40 is controlled by the bellcws 36 via tire pressure communicatïng through the passageway 34.
With continued reference to Fig. 2, it can be seen that the sleeve 43 may be characterized by an internal hexagonal bore 44. In this embodiment, the core 38 is characterized by a spherical hex-. agonal head 46 adapted for making mating engagement with the bore 44. A driven member 48 or other appropriate shaft is connected to the guide 43 at one end thereof as s~own. The other end of the driven member 48 may be connected to the rotor of a wheel speed transducer such.as those standardly used in antiskid systems in the aircraft industry. In this embodiment, the core 38 rotates with the wheel 32 and, by means of the mating engagement at 44,46, drives a shaft or other appropriate means 48 for providing a mechanical input signal to a wheel speed transducer.
As briefly mentioned above, the tire pres-sure communicates to the bellows 36 via the passage-way 34 to longitudinally position the core 38 in the center of the coil 40 of the LVDT. The positioning of the core 38 results in a particular output signal from the LVD~ in standard fashion, which signal can be applied to appropriate meter means in the cockpit. The core 38 may either be freely rotatable within a guide or sleeve 43 or, alternatively, may be used for driving a wheel speed transducer through mating interconnection with the guide 43.
With reference now to Fig. 3, it will be noted that yet another embodiment of a tire pressure communication device is designated generally by the 07~
8.

numeral 50. This apparatus includes a stationary housing 52 adapted to be secured to a stationary part of the aircraft such as an a~le, brake hous-ing, or the like. A bushing 54 i~ provided with appropriate insulators to maintain races 56,57 within the housing 52. A driving arm 58, connected to and rotatable with a wheel (not shown), receives an inner portion of each of the races 56,57, while the outer portions thereof are received by the housing 52. Leads 60-66 are interconnected with the races 56,57 with the first two such leads being connected to the inner races and rotatable there-with as driven by the arm 58. ~hese leads may be connected to a standard pressure transducer or appropriate pressure sensing means maintained within the tire itself. Communication from the leads 60,62 is made with the leads 64,66 via ball bearings 68 maintained between the inner and outer portions of the races 56,57.
The ball bearings 68 are maintained between the race surfaces as f~ur-point contact bearings which have been preloaded therebetween~
In other words, the inner and outer races are each characterized by "V" grooves such that the ball bearings contact on only two points on each of the "V" surfaces on both the inner and outer race portion. Preloading is accomplished in the stand-ard fashion of thermally assembling the races to achieve forced contacting engagement in a four point pre-loaded manner. Further, the races 56,57 may be packed with a conductive grease serving to both reduce friction and aid in conductivity.
In operation, the leads 60,62 rotate with the inner race portions of the races 56,57 while the wheel i5 rotating. The leads 60,62 communicate with the pressure transducer to trans-mit an electrical signal back to the inner race portions which are, in turn, passed across the ball bearings 68 to the outer race portion and thence, by leads 64,66, to appropriate meters in the cockpit.
of course, a large plurality of ball bear-ings 68 are maintained by each of the races 56,57 and, wïth a large plurality of such ball bearings being present, intercommunicating with each other on each race by means of conductive grease and by being thermally preIoaded, chatter and bounce are substan-tially elïminated such that the output signal of the pressure monitor is a pure signal as passed to the meter.
Thus it can be seen that the objects of the invention have been satisfied by the structure presented hereinabove. While in accordance with the patent statutes, only the best modes and preferred embodiments of the invention have been presented and described in detail, it is to be understood that the invention is not limited thereto or thereby.
Consequently, for an appreciation of the true scope ` and breadth of the invention, reference should be had to the appended claims.

Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. Apparatus for sensing the pressure of an aircraft tire and for communicating such pressure sensing from a rotating tire to a stationary portion of the aircraft, com-prising:
tire pressure sensing means connected to and rota-table with the tire;
a first electrical coil maintained about a core, said core being fixedly secured to the stationary portion of the aircraft;
a second coil maintained about said core and in inductive communication with said first coil; and an expandable and contractable circular member connected to and rotatable with the wheel, said member rotating in a path in juxtaposition to said core and operative therewith for completing a magnetic circuit for communicating a signal indicative of the tire pressure from said sensing means to said first and second coils.
2. The apparatus according to claim 1 wherein said sensing means comprises an air pressure inlet in communi-cation between the tire and said member, communicating the pressure of the tire to said member.
3. The apparatus according to claim 2 wherein said member comprises a Bourdon tube.
CA000440136A 1979-07-30 1983-10-31 Tire pressure communication devices Expired CA1178079A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA000440136A CA1178079A (en) 1979-07-30 1983-10-31 Tire pressure communication devices

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US06/061,580 US4237445A (en) 1979-07-30 1979-07-30 Tire pressure communication devices
US61,580 1979-07-30
CA000352948A CA1175125A (en) 1979-07-30 1980-05-29 Tire pressure communication devices
CA000440136A CA1178079A (en) 1979-07-30 1983-10-31 Tire pressure communication devices

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CA000352948A Division CA1175125A (en) 1979-07-30 1980-05-29 Tire pressure communication devices

Publications (1)

Publication Number Publication Date
CA1178079A true CA1178079A (en) 1984-11-20

Family

ID=27166695

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000440136A Expired CA1178079A (en) 1979-07-30 1983-10-31 Tire pressure communication devices

Country Status (1)

Country Link
CA (1) CA1178079A (en)

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