United States Patent [19]
`Achterholt
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,040,561
`Aug. 20, 1991
`
`[54] SIGNAL GENERATING TIRE VALVE
`Inventor: Rainer Achterholt, Sportplatzweg 7,
`[76]
`D-8968 Durach/Weidach, Fed. Rep.
`of Germany
`[21] Appl. No.: 586,777
`[22] Filed:
`Sep. 7, 1990
`[30]
`Foreign Application Priority Data
`Sep. 12, 1989 [DE] Fed. Rep. of Germany ....... 3930479
`[ 51]
`Int. Cl. s .. . .. .. • • ... ... ••• . •• • . • • .. • .. ••• .. • • . .... •• • • B60C 23/02
`[52] U.S. Cl .................................. 137/227; 116/34 R;
`73/146.5; 340/447
`[58] Field of Search ............. 137/223, 227; 116/34 R,
`116/34 A, 34 B; 73/146.3, 146.4, 146.5;
`340/442, 447
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,537,068 10/1970 Amundsen, Jr ..................... 340/442
`3,760,350 9/1973 Johnson .............................. 340/442
`4,037, 192 7 /1977 Cowit .................................. 340/447
`4,048,614 9/1977 Shumway ........................... 340/447
`4,174,515 11/1979 Marzolf ............................... 340/447
`4,177,671 12/1979 Ichihara et al. .................... 73/146.5
`4,562,874 1/1986 Scheller ......................... 73/146.5 X
`4,816,802 3/1989 Doerksen et al. ................... 340/447
`
`Primary Examiner-John Rivell
`Attorney, Agent, or Firm-Pollock, Vande Sande &
`Priddy
`
`ABSTRACT
`[57]
`A tire valve comprises means for generating a wireless
`transmittable pressure drop indicating signal. The valve
`comprises a valve foot attachable to a tire rim and a
`valve shaft extending from said valve foot. A signal
`generating means is mounted on said valve foot ai a
`valve foot side remote from said valve shaft. Said signal
`generating means comprises a reference pressure cham(cid:173)
`ber which is admittable with a desired pressure. A dia(cid:173)
`phragm defines said reference pressure chamber and is
`admittable with the tire pressure to be controlled. Fur(cid:173)
`ther, said signal generating means includes a transmitter
`means, a power supply means and switching means
`which is regularly hold in an opened position, but
`which is closed with a diaphragm deflection, where(cid:173)
`upon the transmitter means is activated. The transmitter
`circuit comprises a sequence control which terminates a
`signal transmission after a short duration thereof and
`resets the transmitter means in a state to become acti(cid:173)
`vated again.
`
`15 Claims, 2 Drawing Sheets
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`US. Patent
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`Aug. 20, 1991
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`1
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`SIGNAL GENERATING TIRE VALVE
`
`5,040,561
`
`The present invention is related to a valve having
`means for generating a wireless transmittable pressure
`drop indicating signal. This valve is especially suited for
`tires of passenger cars, lorries, trucks and the like. This
`valve may be used with tube tires and with tube-less
`tires.
`,
`There are some prior proposals to provide a tire
`valve which generates a pressure drop indicating signal.
`For example, the German Offenlegungsschrift No. 36
`05 661 discloses a tire valve having means for generat~
`ing a wireless transmittable pressure drop indicating
`signal. Said known tire valve comprises a valve foot
`which is attachable to a tire rim. A valve shaft is extend-
`ing from said valve foot, and a tire valve means is 'ar4
`ranged within said valve shaft. A signal generating
`means comprises a diaphragm which may be admitted
`with the tire pressure to be controlled and which is
`deflectable due to an anomal tire pressure. Further, said
`signal generating means comprises a transmitter means,
`a power supply means and a mechanical switching
`means being regularly opened and adapted to be com-
`pleted with a deflection of said diaphragm, wherein a
`switching means completion causes an activation of said
`transmitter means.
`The signal generating means is mounted sidewise to
`the valve shaft of the known tire valve and may impair
`the optical impression and may interfere with any at-
`tachment of other wheel components such as ornamen-
`tal hub caps and the like. The diaphragm of the known
`device is biased by a spring. Typically said type of ar-
`rangement
`is designed for a narrow pressure range
`which is limitated by the spring constant. The known
`diaphragm is continuously biased by the tire pressure
`which reduces any response of the instrument. Further,
`a typical tire use includes admitted tire pressure varia-
`tions which may cause a diaphragm deflection and a
`respective false alarm. The continuously biased dia-
`phragm is arranged to actuate a switching means due to
`an anomal tire pressure, and said switching means will
`activate the transmitter means. As long as the anomal
`tire pressure is prevailing,
`the transmitter means re-
`mains activated and draws electrical energy from the
`power supply means. There are severe doubts whether
`the known tire valve device is realizable or has been
`realized in the past.
`Further, US. Pat. No. 4,819,686 (Achterholt) dis-
`closes a tire valve cap providing a visible pressure drop
`indicating signal. The known valve cap comprises a
`deflectable diaphragm which separates a housing inte-
`rior into a first chamber which is admitted with the tire
`pressure to be controlled and into a reference pressure
`chamber which is admitted with a desired pressure
`when the valve cap is screwed onto a tire valve. Said
`reference pressure chamber is partly defined by a trans-
`parent housing portion. Any reduction of the tire pres-
`sure to be controlled relative to the desired pressure
`will cause the diaphragm to converge toward the trans-
`parent housing portion, thus serving as an indication.
`The known valve cap is not adapted to generate a wire-
`less signal transmission.
`It is a primary object of the present invention to pro-
`vide a tire valve having means for generating a wireless
`transmittable pressure drop indicating signal, which tire
`valve is not distinguishable with respect to optical im-
`pression and handling from known tire valves, the sig-
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`nal generating means thereof is highly sensitive and
`works in a wide range of different tire pressures and is
`not disturbed by usual admitted tire pressure variations,
`and the transmitter means thereof is maintenancefree
`and designed for a multi-years usage duration including
`a large number of alarm signals which may be distin-
`guished safely from other false or foreign signals.
`According to a further object of the present invention
`said tire valve is of simple structure and can be fabri-
`cated economically.
`In accordance with the present invention, a tire valve
`is provided having means for generating a wireless
`transmittable pressure drop indicating signal, wherein
`the tire valve is comprising:
`a valve foot attachable to a tire rim;
`a valve shaft extending from said valve foot;
`a tire valve means arranged within said valve shaft;
`and
`a signal generating means mounted on said valve foot
`at a valve foot side remote from said valve shaft, and
`comprising:
`a power supply means;
`a transmitter means which—when activated—gener-
`ates a signal
`transmission and comprising a se-
`quence control which terminates said signal trans-
`mission after a short duration thereof and resets
`said transmitter means in a state to become acti-
`vated again;
`a diaphragm being admittable with the tire pressure
`to be controlled and being deflectable due to an
`anomal tire pressure;
`'
`a mechanical
`switching means being regularly
`opened and adapted to be completed with a deflec-
`tion of said diaphragm, said switching means com-
`pletion causes an activation of said transmitter
`means; and
`a reference pressure chamber being admittable with a
`desired pressure when the tire valve means is
`opened and adapted to be closed pressure-tight
`when the tire valve means is closed,
`wheren said reference pressure chamber being partly
`defined by said diaphragm which takes a position
`deflected away from said reference pressure cham-
`ber and causes completionof said switching means
`whenever the tire pressure to be controlled is
`lower than the desired pressure.
`In accordance with the present invention, a tire valve
`is provided which generates a wireless transmittable
`pressure drop indicating signal and which may be han-
`dled like a conventional tire valve. The signal generat-
`ing means is mounted on the valve foot at a valve foot
`side remote from the valve shaft. Therefore, in use, the
`signal generating means is located within the tire inte-
`rior and cannot impair the optical impression of the
`valve or cannot interfere with any attachment of other
`wheel components like ornamental hub caps and the
`like. The components of the signal generating means are
`protected against non-admitted removal from the tire
`valve. The signal generating means including the refer-
`ence pressure chamber, the electric and/or electronic
`components of the transmitter means and the battery or
`storage battery forms a single unit which is simply de-
`signed and assembled, and which has small dimensions
`and a low weight. For example, a signal generating
`means has been formed like a cylindrical unit having an
`outer diameter of approximately 18 mm, an axial length
`of about 7 mm and a weight—including battery—of less
`than 10 g. Any presence of said signal generating means
`
`Page 000004
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`5,040,561
`
`3
`does not increase essentially any un-balance caused by
`the tire valve. Because the transmitter circuits stop any
`signal transmission automatically after a short duration
`thereof, any signal alarm requires solely a small amount
`of electrical energy. For example, a lithium—battery
`providing a voltage of 3 Volt and a capacity of approxi-
`mately 40 milli Ampere hours may be used as power
`supply means of the signal generating means. A battery
`of said type is suited to power the signal generating
`means in order to generate at least 500 to 1000 signal
`alarm pulses. Therefore, the signal generating means
`may be housed maintenancefree within the tire interior.
`Because the tire pressure is controlled with a reference
`pressure chamber wherein a given desired pressure is
`stored, the diaphragm is exposed solely to the small
`pressure differences between the tire pressure to be
`controlled and the given desired pressure. The dia~
`phragm may be formed thin and highly sensitive. A
`single embodiment of a signal generating means may be
`used with a wide range of different tire pressures, be-
`cause solely the difference between the tire pressure to
`be controlled and the desired pressure stored within the
`reference pressure chamber is monitored and used to
`trigger any signal alarm pulse. The intended reference
`pressure chamber provides optimal results with a me-
`chanically operable electrical switching means, because
`a relatively small diaphragm deflection is sufficient to
`complete the switching means which is maintained reg-
`ularly in the open status. Any diaphragm deflection
`does not require any movement of a substantial mass or
`does not require any overcoming of spring biasing. A
`high sensitivity is obtained, which is not impaired by
`usual, admitted tire pressure variations because said
`typical tire pressure variations form a pressure increase
`which does not cause any diaphragm deflection. A
`transmitter means is preferred which generates two
`different signal frequencies, which are transmitted alter-
`nately with a given pulse repetition. Thereto, a narrow
`and specific coupling with a given receiver means may
`be obtained which is practically not disturbed or im-
`paired by any other signal sources. To each transmitter
`device or to each tire valve, respectively, is attributed a
`specifically tuned receiver means, wherein the maxi-
`mum distance between receiver means and transmitter
`means is preferably less than 1000 mm. To each wheel is
`attributed a distinctive receiver means which is directly
`connected with an indication device arranged at
`the
`instrument panel of the vehicle. A single embodiment of
`the tire valve according to the present invention is
`suited for all the wheels of a vehicle. A typical vehicle
`tire comprises a cord ply made from steel; surprisingly,
`such a steel cord ply does not substantially hinder the
`transmission of signal frequencies and the safe receipt
`thereof with the receiver means. Under said conditions,
`a false alarm due to admitted tire pressure variations or
`due to foreign or external signal transmissions and in
`addition any disturbance of other receiver means is
`practically excluded.
`Advantageous embodiments and further improve-
`ments of the tire valve may also be provided according
`to the present invention.
`As stated above, the signal generating means corn-
`prises a reference pressure chamber which may be ad-
`mitted with desired pressure when the tire valve means
`is opened and which is adapted to become closed pres-
`sure—tight when the tire valve means is closed. A typi-
`cal, conventional tire valve comprises a valve foot for
`attaching the valve to a tire rim, and a valve shaft hous-
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`ing the tire valve means. Typically, said tire valve
`means comprising a valve bore provided with the valve
`seat and a valve body adapted to engage said valve seat-
`in order to close the tire valve. According to a further
`aspect of the present invention, a first passage within
`said valve shaft is provided which opens into said valve
`seat and which connects the valve bore with the refer—
`ence pressure chamber in order to admit said reference
`pressure chamber with the given desired pressure.
`Whenever the valve body is removed from the valve
`seat, for example by displacement of a valve plunger, in
`order to supply pressurized air via the tire valve into the
`tire interior, a fluid medium such as pressurized air may
`flow through the opened first passage, and the reference
`pressure chamber is admitted with the desired pressure.
`In the following, the valve body will engage the valve
`seat again in order to close the tire valve; concurrently
`therewith the first passage is closed, and the reference
`pressure chamber will be closed and will be maintained
`continuously closed pressure-tight.
`According to an alternative embodiment, the valve
`bore may be provided with a second passage connecting
`the valve bore with the reference pressure chamber in
`order to admit said reference pressure chamber with the
`desired pressure. An auxiliary valve is arranged within
`said second passage and adapted to become opened or
`closed common with the tire valve. For example, said
`second passage may comprise a tube section aligned
`with the valve bore. Said tube section is provided with
`an auxiliary valve seat, and the auxiliary valve is a
`spring-loaded check valve arranged within said tube
`section. Regularly, said spring-loaded check valve is
`biased towards the auxiliary valve seat and takes its
`closed position. Whenever the valve plunger is pushed
`down in order to open the tire valve, an extension of
`said valve plunger acts upon said auxiliary valve and
`opens said valve. With returning of the valve plunger,
`the spring of the spring-loaded auxiliary valve will press
`the check valve body against the auxiliary valve seat
`and the auxiliary valve becomes closed again.
`As stated above, the signal generating means com—
`prises a reference pressure chamber wherein a given
`desired pressure is stored continuously. According to a
`further aspect of the present invention said reference
`pressure chamber is formed within a flat cell comprising
`a cell bottom and a circumferential cell wall having a
`cell wall front face. A cell opening is closed with the
`diaphragm which is pressure-tightly fixed to an inner
`face of the circumferential cell wall. A cylindrical sec-
`tion of the circumferential cell wall extends beyond the
`diaphragm.
`A third passage is recessed within said circumferen-
`tial cell wall, starting at a front face of said cell wall,
`opening into the reference pressure chamber and being
`connected to the first or second passage. A fluid me-
`dium may flow through said third passage in order to
`admit the reference pressure chamber with the desired
`pressure.
`A conductor section may be fixed at opposite spots of
`the cylindrical section of the circumferential cell wall
`extending beyond the diaphragm. For example, said
`conductor section may be formed like a metallic clip or
`little rod, being electrically conductive connected with
`a circuit board of the transmitter means and forming a
`fixed arranged contact of the switching means. Said
`conductor section is arranged parallel to the diaphragm
`and in a short distance to a rest position thereof.
`
`Page 000005
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`5,040,561
`
`5
`A moveably arranged contact of the switching means
`is formed by a small metal plate which is attached to a
`central portion of the diaphragm. Said metal plate is
`electrically conductive connected with a circuit board
`of the transmitter means, and will engage the conductor
`section in order to complete a electrical circuit of the
`switching means with a respective diaphragm deflec-
`tion. Thereupon a circuit of the transmitter means will
`become activated, and the transmitter means generates
`signal frequencies. The switching means works relya—
`bly, sensibly and fast, because there is no need to over-
`come substantial counter-forces. A diaphragm deflec-
`tion of a few 1/ 10 millimeters is sufficient in order to
`complete the switching means.
`As stated above the signal generating means com-
`prises a power supply means in order to supply current-
`/voltage to the electric and/or electronic components
`of the transmitter means. For example, said power sup-
`ply means may be a lithium battery having a capacity of
`at least 40 milli Ampere hours and proving a voltage of
`3 volt. A battery of said type may be formed as a button
`cell and may be inserted within the housing of the signal
`generating means.
`Typically, a circuit of the transmitter means is main~
`tained regularly in a stand-by condition, wherein nearly
`no electrical power is drawn from the battery. Any
`transition from the stand-by condition into an activated
`state, wherein the transmitter means will generate signal
`frequencies, is caused by a completion of the switching
`means.
`
`Whenever the switching means has been completed
`or closed a signal transmission is generated for a limi-
`tated duration. Preferably said signal
`transmission is
`limitated to a duration of approximately 1 to 3 seconds.
`Preferably said signal transmission comprises alternate
`and periodical transmission of different signal frequen-
`cies. For example, said alternate and periodical trans-
`mission of different signal frequencies may be generated
`with a transmitter means comprising essentially a digital
`circuit and an oscillating circuit provided with a coil
`' which is formed as a transmitting antenna. According to
`an essential aspect of the present invention said digital
`circuit comprises a sequence control which terminates a
`signal transmission after a short duration thereof and
`resets the transmitter means again in a stand-by condi-
`tion wherein the transmitter means is adapted to be-
`come activated again.
`According to a further aspect of the present invention
`the digital circuit comprises a number of essential func-
`tional groups, such as a RC~oscillator, a trigger circuit,
`a modulation circuit, a multi-stage frequency divider
`and a power amplifier which may be switched on or off.
`The RC-oscillator provides different signal frequencies,
`wherein each specific frequency is defined by the resis-
`tor component (R) and the capacitor component (C)
`thereof. Preferably the circuit is designed such that
`different feedbacks of the frequency divider will trigger
`respective functional groups of the digital circuit such
`that the transmitter circuit will be started or triggered
`with completion of the switching means and ~will per-
`form a complete signal
`transmission. Following said
`signal transmission, the power amplifier and the RC-
`oscillator will be switched off which reduces essentially
`the electrical power drawn from the battery. The com-
`plete circuit is switched back to a stand-by condition,
`spends nearly no electrical power and is ready for acti-
`vation for a new signal transmission, even if the switch-
`ing means remains completed or closed. A renewed
`
`6 .
`transmission starts not earlier before the dia-
`signal
`phragm has been returned in its rest position,
`the
`switching means has been opened, and the reference
`pressure chamber has sensed a tire pressure drop,
`whereupon the diaphragm is deflected again in order to
`complete the switching means.
`According to a further preferred aspect of the present
`invention the alarm signal comprises relatively long-
`waved frequencies in the kHz-range. As a matter of
`experience, nearly no disturbance due to another of
`foreign signal sources have to be expected in said kHz-
`frequency range. Nevertheless, a disturbance-free trans-
`mission of the alarm signal to the receiver means can be
`effected. Preferably, said receiver means are arranged in
`each wheel area of the vehicle. Preferably, the distance
`between each transmitter means or tire valve, respec-
`tively, and the attributed receiver means does not ex-
`ceed 1000 mm.
`In order to increase the identification between each
`transmitter means and its attributed receiver means and
`in order to exclude essentially any false indications due
`to foreign signals, each generated signal comprises pref-
`erably two different frequencies. For example, each
`complete signal may comprise a first frequency of 9.6
`kHz and a second frequency of 10.4 kHz, and each
`frequency is generated and transmitted alternately for a
`duration of about 10 to 20 milli seconds. The complete
`duration of each complete signal amounts preferably a
`few seconds, for example 1
`to 3 seconds, and more
`preferred about 1.6 seconds. Under these conditions the
`capacity of the above-mentioned lithium battery is suffi-
`cient to supply at least 500 to 1000 alarm pulses; this is
`sufficient for the complete to be expected life time of the
`tire valve according to the present invention. Thereto,
`the signal generating means including the power supply
`means may be arranged at a non-easily accessible loca-
`tion within the tire interior.
`Preferably, the complete transmitter means including
`any electric and/or electronic components thereof is
`formed like a module. The components including two
`integrated circuit chips, 3. RC-oscillator and a number
`of capacitor means and resistor means are mounted on a
`board, which is formed as a printed circuit. In a practi-
`cal embodiment a circular circuit board having a diame-
`ter of approximately 17 mm is sufficient to accept the
`complete number of components. Said circuit board
`including said components is located safely within a
`sleeve made of plastic material; said plastic sleeve com-
`prises an outer circular face, and a groove is recessed in
`said outer face; a transmitting antenna is formed like a
`wire coil and arranged within said groove. The com-
`plete signal generating means including reference pres—
`sure chamber comprising a switching means, transmit-
`ter means and power supply means may be formed as a
`single integrated unit having a diameter of about 18 mm
`and a length of about 7 mm. Aside from a third passage
`providing admittance of the desired pressure to the
`reference pressure chamber, the complete unit may be
`formed incapsulated in order to avoid any impairment
`due to components of the fluid member inside of the
`tire. The complete integrated unit has a weight of less
`than 10 g and does not increase essentially the weight of
`a conventional metal valve for tires.
`A specific receiver means is attributed to each tire'
`valve including the transmitter means thereof. Typi-
`cally, each receiver means comprises a ferrit rod having
`a receiver antenna and a known receiver circuit. The
`electrical power need of the receiver circuit may be
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`5,040,561
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`7
`provided with the power supply of the vehicle. The
`receiver circuit comprises outputs which are opera-
`tively connected with an indicator device mounted at
`the instrument panel or the like of the vehicle. Said
`indicator device includes an evaluation circuit which
`attributes signal pulses obtained from a specific trans-
`mitter/receiver means to the attributed wheel indica-
`tion. Further, said indicator device generates a visible
`and/or audible warning signal due to the received sig-
`nal pulses; even after termination of said signal pulses
`the warning signal is maintained as long until the vehi-
`cle driver extinguishes or resets the warning signal indi-
`catiOn.
`After transmission of a number of signal pulses the
`signal generating means is renewed ready for transmis—
`sion a new sequence of signal pulses, provided that the
`diaphragm has taken its rest position again. Especially,
`the diaphragm may be returned in its rest position by
`pushing down the valve plunger of the tire valve, be-
`cause an access to the reference pressure chamber is
`opened and a pressure compensation or a new setting of
`the desired pressure may be performed.
`In the following the present invention will be ex-
`plained in more detail with reference to the drawings, in
`which:
`FIG. 1 is a schematic sectional view of a tire valve
`according to the present invention including a signal
`generating means thereof; and
`FIG. 2 is a schematic sectional view of a modified
`embodiment of the tire valve according to FIG. 1,
`showing an alternative mode for admittance the desired
`pressure to the reference pressure chamber.
`FIG. 1 illustrates an embodiment of a tire valve ac-
`
`cording to the present invention comprising a tire valve
`means 1 and a signal generating means. The valve
`means 1 includes a valve shaft 2 defining a valve bore 3.
`A valve seat 4 is formed at a inner circumferential face
`of the valve bore 3. A valve body 5 is adapted to engage
`said valve seat 4. A spring 7 may press said valve body
`5 against the valve seat 4 in order to close the valve
`means 1. A valve plunger 6 is attached in a single-piece
`embodiment to the valve body 5; by displacement of
`said valve plunger 6 the valve body 5 may be dis-
`engaged from the valve seat 4 and a pressurized fluid
`medium may flow through the valve bore 3. An exterior
`circumferential face of the valve shaft 2 may be pro-
`vided with stepped exterior threaded sections 8 and 9 in
`order to fasten the tire valve to a wheel rim with the aid
`of a nut. A valve foot 10 is attached to the valve shaft 2
`in a single-piece manner.
`In a typical manner of use the valve 1 is passed
`through a valve opening recessed in a wheel rim in such
`a manner that the valve foot 10—optionally with a—-
`non-illustrated—intermediate
`insulating
`insert—will
`engage the inner wall of the wheel rim. Further, a union
`nut is screwed on the external thread 9, and the valve 1
`is fixed to the wheel rim. In the present case, the valve
`1 is designed for a tubeless pneumatic vehicle tire. The
`complete valve 1 is typically made from metal, for ex-
`ample from a zinc/copper alloy or an aluminum alloy.
`According to an aspect of the present invention a first
`passage 12 is recessed within the valve shaft 2; at the
`one side said first passage 12 discharges into the valve
`seat 4, and at the other side said first passage 12 dis-
`charges at a front face 11 of the valve foot 10. As far as
`the valve body 5 engages the valve seat 4, the first
`passage 12 is closed. Whenever the valve body 5 is
`
`8
`removed from the valve seat 4, any pressurized fluid
`medium may flow through the first passage 12.
`At a valve foot side remote from said valve shaft 2, a'
`signal generating means is arranged in such a manner
`that a flow connection is established between the valve
`bore 3 and an interior space of the pneumatic tire.
`Said signal generating means includes a sleeve 20
`made from plastic material and comprising a circumfer-
`ential inner and outer face; a circumferential groove21
`is recessed in the outer face. The inner face is provided
`with a circumferential shoulder 22, and a circuit board
`23 is supported on said shoulder 22. The electric and/or
`electronic components 24, 24’, 24” and 24’” of a trans-
`mitter means are mounted on said circuit board 23.
`Further, the transmitter means includes a transmitter
`antenna 25 which is formed like a wire coil and ar-
`ranged within the groove 21 recessed in the outer face
`of the sleeve 20. Further, a button cell 26 is arranged
`and fixed within the interior of the sleeve 20. The button
`cell 26 is provided with terminals 27 and 28, being oper-
`atively connected with the circuit board 23.
`Further, the signal generating means includes a flat
`cell 30 comprising a cell bottom 31 and a circumferen<
`tial cell wall 32 having a wall front face 35. A cell open-
`ing is covered by a diaphragm 40 which is fixed at the
`inner side of the circumferential cell wall 32. A small
`metal plate is attached to a central section of the dia-
`phragm 40. Said cell bottom 31, said cell circumferen-
`tial wall 32 and said diaphragm 40 define a reference
`pressure chamber 44. A third passage 36 is recessed
`within the circumferential cell wall 32, which opens to
`the cell wall front face 35 and into the reference pres-
`sure chamber 44. Said third passage 36 is aligned with a
`section of the first passage 12 recessed within the valve
`foot 10 providing a flow connection from the valve seat
`4 through the first passage 12 and the third passage 36
`into the reference pressure chamber 44.
`A circumferential section of the cell wall 32 is extend-
`ing beyond the diaphragm 40. A conductor section 42 is
`mounted to said extending cell section 32. Said conduc—
`tor section 42 is arranged parallel to the diaphragm 40
`and in a small distance to a rest position of the dia-
`phragm 40. The moveably arranged small metal plate 41
`and the fixed arranged conductor section 42 form to-
`gether a regularly opened mechanical switching means.
`Both, the metal plate 41 and the conductor section 42
`are operatively connected with the circuit board 23.
`Any sufficient deflection of the diaphragm 40 will en-
`gage the metal plate 41 with the conductor section 42,
`and will close an electric circuit, which will activate a
`digital circuit of the transmitter means whereupon a
`signal transmission is generated.
`As illustrated in FIG. 1, the sleeve 20 and the cell 30
`including their specific components are mechanically
`connected with each other and form together a inte-
`grated unit. Said unit may be embedded within a casting
`resin 39 or may be incapsulated in another way in order
`to provide protection against the components of the
`pressurized fluid medium within the tire. Said unit may
`comprise an additional cover plate 37 which protects
`the diaphragm 40 against any direct impact of the pres—
`surized fluid medium. An opening 38 is recessed within
`said cover plate 37 and allowing the tire pressure to be
`controlled to admit the diaphragm 40.
`The FIG. 2 illustrates an alternative embodiment of
`the tire valve according to the present invention, having
`a signal generating means which is identical with the
`signal generating means of the embodiment according
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`50
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`55
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`65
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`9
`to FIG. 1. Contrarily, the valve means 1 comprises a
`conventional valve core 13 within a valve bore 3.
`Within said valve bore 3 and aligned with the valve
`core 13 is a tube section which is provided with an
`auxiliary valve seat 19. An auxiliary valve 15, for exam-
`ple a spring-loaded check valve is arranged within said
`tube section. A spring 18 pushes a valve body 17 of the
`auxiliary valve 15 against the auxiliary valve seat 19.
`The tube section is in flow connection with a second
`
`passage 12 and with the third passage 36. A rod 14 is
`mounted to and extends beyond the valve core 13.
`Whenever the valve plunger 6 is actuated, said rod 14
`will strike the valve body 17 of the auxiliary valve 15
`and will dis-engage said valve body 17 from the auxil-
`iary valve seat 19. Pressurized fluid medium may enter
`into the tube