Note: Descriptions are shown in the official language in which they were submitted.
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VIBRA'rlNG TRANSDUCER POWER SUPPLY
FOR USE IN ABNORMAl. TIRE CONDITION WARNING SYSTEMS
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BACKGROUND OF THE INVENTION
The present invention relates to abnormal tire condition
warning systems and is more particularly directed to a vibrating
- transducer power supply for use therewith. However, it should be
appreciated by those skilled in the art that the invention has far
broader applications.
Both over and under inflated conditlons for pneumatic
tires ls a cause for e~cessive tire wear resultlng in premature tire
-- failure. Moreover, such under and over inflated tire conditions can
have an adverse effect on the efficiency o~ operation o~ the vehicle
as to both vehicle performance or handling as well as vehicle gas
mileage. Since such conditions and results have been well known for
quite some time~ there have been many attempts to develop and
provide means ~or automatically detecting and reporting themD
Recently) development efforts for a practical and inexpensive device
have become more concentrated due to the rise in fuel and tire costs
as well as vehicle operations costs in general.
While there have been quite a number of prior devlces
developed and utilized for detecting tlre inflation conditions, all
of these prior devices have had structural or operational
- shortcomings rendering them undesirable or impractical for
widespread use. While the specific prior devices have been many and
varied, most have required special wiring and the like extending
from the wheel assemblies to the vehicle chassis and then through
the vehicle body to the instrument panel. Such wiring adds
- undesired cost to the system and moreover, is extremely difficult and time consuming to install. Such installation time is
particularly important when considered on the basis of installing
the devices during original vehicle asse~bly for making them a part
of the original vehicle equipment. Further, the necessary special
wiring and associated equipment extending between the wheels and
chassis are such that they are susceptible ~o damage or breakage
from road materials, weathering and the like encountered during
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normal vehicle use.
There have also been some prior attempts at developing a
self-contained detector apparatus in an effort to eliminate the
necessity for wiring and the like between the wheels and chassis,
but these prior attempts still have not proved totally successful
and effective. Specifically, these prior self-contained units have
utilized small signal emitters such as a radio transmitter disposed
at each wheel. These emitters transmit a slgnal such as a radio
signal in response to some predetermined inflation conditlon
detected in the tire by a sensing means. The signal is then
received in the vehicle and utilized to energize a warning indicator
or light ~o adv~se the vehicle operator that an over or under
inflated tire condition is present
l~lle generally overcoming the wiring problems, the means
employed for powering the emitters has thus far proved to be
unacceptable for practical widespread vehicle application.
Typically~ these power means have comprised small batteries
associated with each wheel or other, rather exotic and complex
circuitry. Batteries must, of courseJ be periodically replaced as
their useful life expires and it is impossible to precisely
determine the exten~ of this useful li~e as it w~ll vary between
individual batteries and between individual manufacturers thereof.
Moreover, it has been generally found that many owners are extremely
lax with regard to periodic vehicle maintenance. As a result,
25 owners would also simply forget or not take the time to properly
check, maintain and replace these small batteries. Therefore, this
type of self-contained detector would often be inoperative and,
therefore, of no practical value or use. The other, rather exotic
and complex clrcuitry had the disadvantage of being costly and
; 30 subject to damage or destruction during normal vehicle use.
Still another disadvantage with prior abnormal tire
detecting and reporting devices or systems was that their
effectiveness depended to a great degree on the rotational speed of
the wheel itself. Thls fact was due to their very design and
35 construction such that the devices were really only effective at
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elevated vehlcle speeds and did not properly operate at normal city
driying speeds. Moreover, many of the prior devices were only
uni-directional and thus were only operative in one direction of
rotation. Accordingly, such devices were limited to mounting on one
side or the other of a vehicle.
Stlll another problem with the prlor devices of thls
general type has been in the necessity for providing operative
communication between stationary and rotating components. Because
the devices are generally electrically operated, prior devices found
it necessary to lnclude slip ring structures to operably
interconnect the various components and such structures were found
to be susceptible to damage or the like necessitatlng repair and/or
replacement.
OBJECTS OF THE INVENTION
An object of the present invention ls to provide a new
device for indicating the condition of a pneumatic tire.
Another object of the presen~ lnvention is to provlde a
device that lndicates the condition of a pneu~atic tire and is
simple in design, construction and installation.
Another object of the present invention i5 to provlde a
fully self-contained device for indicating a condition of a
pneumatic tire~
Stlll another object of the present invention is to
provide a power supply that can be used in any system that has
natural inherent vibratlons.
- BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, there is
provided a self~contained device ~or indicating some predetermined
condition of a penumatic tire of the type used on an automobile.
The device includes a power supply which is comprised of a housing
attached to the tire rim, an arm that is attached at one end to the
housing, a weight attached to the other end of the arm, and a
transducer attached to the arm such that normal wheel vibrations
will cause the arm to vibrate thus flexing the transducer, thereby
produclng electrical energyO This power supply energi~es the
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remainder oE the device such that the device can send an electronic
signal to a monitoring device within the automobile.
In accordance with another aspect of the present invention
an electronic circuit which is powered from the above-mentioned
power supply is provided for electronic processing of the abnormal
condition signal from the sensor.
- In still another aspect of the present invention, an
antenna is provlded for transmitting the electronic signal
indicative of the abnormal signal to a monltoring de~ice.
BRIEF DESCRIPTION OF T~IE DRA~INGS
The invention may take physical form in certain parts and
, arrangements of parts, an embodiment of which will be described in
detail in the specification and illustrated in the accompanying
drawings which form a part hereof and wherein:
Figure 1 is a side elevational view in partial
cross-section of a vehicle wheel assembly having the device of the
present invention installed thereon;
Figure 2 is an enlarged side elevational view in partial
cross-section of the device shown in Figure l;
Figure 3 is a side elevational view in partial
cross-section of a vehicle wheel assembly having the device of the
present invention installed in another configuration;
Figure 4 is a side elevational view in partial
cross-section of a vehicle wheel assemhly having the device of the
- 25 present invention installed in yet another configuration;
Figure 5 is an enlarged side elevational view in partial
cross-section of the vibrating transducer system in another
configuration; and
Figure 6 is an enlarged side elevational view in partial
cross-section of the vibrating transducer system in yet another
configuration.
DESCRIPTION OF TIIE PREFERRED EMBODIMENTS
A description of the invention follows, referring to the
- ~ Figures in which like reference numerals denote like elements of
structure in each of the several Figures.
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Referring now to the drawings, ehere is shown in Flgures 1
and 2 a housing 2, mounted on the inside of a wheel rim 4, by an
attachment means such as bolt 6, and nut 8. The bolt 6 can be an
inte~ral part of housing 2, such that the t:Lghtening of nut 8
secures the housing 2 to rim 4~ A rubber pad 10 is provided in
order to for~ an airtight seal between the housing 2 and rim 4.
Also~ the surface 12 of housing 2 :Ls preferably curved and coneoured
to match that of rlm 4. This aids in forming an airtight seal
between the housing 2 and rim 4. It will be apparent to those
skilled in the art that there are other methods of attaching housing
2 to wheel rim 4 such as shown in Figure 4 wherein housing 2 is
fixedly attached by means of a band 9. Band 9 may take the
form of any known adjustable type construction described.
In both Eigures 1 and 4 housing 2 is fixedly mounted on the rim 4
such ~hat the housing 2 i6 within the cavity of the pneumatic tire
14.
A sensor 16 i5 provided to sense an abnormal condition
within tire 14. The sensor 16 is mounted on the outsid~ of ~housing
2 such that a condition within tire 14 can be detected. An
electronic circui~ 18, located within housing 2, is eiectrically
connected to the sensor 16 by wires 20. The electronic circuit 18
processes the signal from the sensor 16 and ~hen transmits a signal
lndicative of the sensed condition by way of antenna 22 to a
monitoring device, not shown. Electronic circuit 18 is preferably
- 25 of the type described in Canadian Patent No. 1,136,242 issued
November 23, 1982 to David Betts and assigned to the same assignee
of the present invention. It is contemplated that the sensor 16 will
shunt out the voltage generated by the vibrating transducer system 24
; when the condition is within acceptable limits. When the condition
falls outside the acceptable limits, the voltage generated by system 24
will pass to electronic circuit 18. The voltage passed will be used
to charge a capacitor. When the capacitor charge reaches a
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specific level, a counter will begln counting tlle transducer pulses.
When the counter reaches a predetermined count, a signal will then
be transmitted to a monitoring device. The monitoring device is a
receiver located within the interior of the vehicle and can be
equipped with a warning light9 a warning buzzer or an analog
indicator. The antenna 22 will preferably take the form of a wire
that can be molded into the housing itself for added durability or
can be moun~ed on the electronic circuit board, not shown.
Referring to Figure 2, the electric energy to power ~he electronic
circuit 1~ is generated by the vibrating transducer 9ystem 24. The
vibrating transducer system 24 comprises an arm 26, fixedly attached
at one end to housing 2 by bracket 28, a weight 30 attached to arm
-~ 26 at the free end and transducer 32 is fixedly attached to arm 26.
In normal operation o~ the vehicle, the tire is ~ubject to natural
vibrations such as wheel'hop and the like as well as road
conditions. Wheel hop is an inherent oscillation that occurs in'all
motor vehicles. Since a wheel system is designed to try and smooth
the vehicle ride by use of springs and shock absorbers9 the wheel
has a tendency to hop even on smooth roads. It has been found that~ 0
a wheel hop of approximately~rHZ occurs in a typical passenger ~
vehicle. These vibrations will cause the arm to vibrate, thus l~21-19
causing the transducer 32 to flex. Transducer 32 will preferably be
; a piezoelectric element. This type of transducer is well kno~n in
the art. A piezoelestric transducer converts mechanical energy into
electrical energy. The type of piezoelectric contemplated by the
present invention would preferably be a double layer piezoelectric
that is polarized in opposite directions and electrically connected
in series. The voltage generated by the piezoelectric element will
then be the sum of the individual layer outputs. It is this
generated voltage that is used to power electronic circuit 18. The
energy produced from vibrating transducer system 24 is passed to
- electr'onic circuit 18 via wires 34.
As will be appreciated by those skilled in the art9 the
electronic clrcuit 18 can process the condition signal from sensor
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16 in many different ways. For example, tlle electronlc clrcult 18
,nay transmit a si~nal only when the conditLon ln the cavlty exceeds
some predetermined level. By way of another example, the circuit 18A
may trans~it a continuous signal indlcatlve of the ca~lty conditlon.
The type of signal transmitted may also be quite varied. For
example, the electronic circuit 1B may transmit a coded, digital
signal or it may transmit a basic FM or AM signal. Different
methods of transmitting an abnormal condition signal are described
in the aforementioned Canadian Patent and in Canadian Patent No.
1,145,829 to D. Betts, R Sobecks and R. Green issued M~y 3, 1983.
Figure 3 shows another embodiment of the present invention
in which housing 2 is~mounted externally to the cavity of tire 14.
The sensor 16 is then mounted such that it can sense the cavity
condition.
Figures 5 and 6 show two alternative methods of mountlng
the vibrating transducer system 24. Referring to Figure 5, arm 26
is fixedly attached at both ends by rigid support 28a. The
piezoelectric 32 is attached to arm 26 between the supports 2~a.
The weight 30a is attached to piezoelectric 32 at approximately half
way between supports 28a such that wheel vibrations will cause the
arm 26 to ~ibrate? thus causing the piezoelectric 32 to flex.
Referring to F~gure 69 piezoelectric 32 is attached to arm 26~
Piezoelectric 32 is then mounted in rigid support member 28b such
that the piezoelectric 32 and arm 26 protrude outwardly therefrom.
Weigh~s 30b ars then fixedly attached to the ends of arm 26 sùch
! that wheel vibrations will cause arm 26 to vibrate, thus causing the
piezoelectric 32 to flex. It will be apparent to those skilled in
the art that there are other methods of mounting the vibrating
transducer system. The three ways described are only given by way
of example and are not meant to limit the scope of the inventlon.
The use of the vibrating transducer power supply is not
limited to use in tire condition warning systems. Any system that
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is subject to vibrations can use this type of power supply. Also, a
system can be designed that generates mechanical vibrations in the
` arm that would, in turn, generate electrical power. Such a system
could comprise a mechanical spring or oscillator that would vibrate
S the arm. This type of system would yield a portable power supply
that would be small, compact, reliable and permit versatility for
in-the-field uses.
In operation the syst~em of the present invention
continuously monitors the conditlon of the vehicle's pneumatic tires
while the vehi-cle is in motion. As the vehicle wheels are put in
motion, vibrations in the wheels are caused by road conditions and
7 natural wheel hop. These vibrations cause the housing fixedly
attached to the to the wheel rim to vibrate which, in turn, produces
flexing of the welghted transducer assembly. That is, the weighted
arm 26 of the vibrating transducer system ~4 will vibrate thus
causing transducer 32 to flex, thus transforming the mechanical
energy caused by the wheel vlbrations into electrical energy. It is
this electrical energy that provides power for the remainder of the
device. Preferably, the electrical energy produced by the vibrating
transducer system 2~ will be shunted out until an abnormal condition
occurs. At such time9 the energy produced will pass to the
electronic circuit 18 so that it can be processed. A signal will
then be transmitted to a monltoring device located within the
passenger compartment which is indicative of the abnormal sensed
condition.
Thls invention has been described with reference to
preferred embodiments. Obvious modifications and alterations will
occur to others upon reading and understanding of this
specification. Such modifications include the sensing of tire
pressure, tire temperature, etc. The intention is to include all
such modifications and alteratioDs insofar as they come within the
scope of the appended claims or the equivalent ~hereof.
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