A device for indicating, on the vehicle's control panel inside the driver's cabinet during driving or stopping, the minimum and the maximum pneumatic pressure limits (lower and upper safety thresholds) in the inflated tyres of the vehicle.

Claim 1

A device for indicating, on the vehicle's control panel inside the drivers cambinet at any time during driving or stopping, the maximum and the minimum pressure limits (lower and upper safety thresholds) in the vehicle's inflated tyres, consists of a special system of metallic strips (2, 3, 4) or (151, 152, 153) that are either one complete metallic circu­lar annular strip (2) and two segments of metallic circular strips (3, 4) parallel to (2) or one complete metallic cylind­rical surface (151) and two segments of co-axial metallic cy­lindrical surfaces (152, 153), where the strips (2, 3) from a plane condenser and (151, 152) from a cylindrical condencer of the circuit (28,1,32,5,8,9,10,27) of a high voltage transfo­rmer (10,11,12) with a ferrite core of small permeability, one amplifier (13) or (17, 16, 15, 11), one analog or digital oscillator or multivibrator or alternating current generator of frequencies 10kHz to 10MHz (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) or (14), one conductor (30) which is insulated or earthed big enough to absorb the noise alternating current which is due to the parasitic capacitance, one photodiode or loudspeaker (5) which emmits a signal to indicate the danger­ous limits of the tyre pressure,two variable resistances (9, 33) to counterbalance the variable electric resistance which appears in the rotating ballbearings on the axle of the wheels and is due to the lubricant substance that covers the ball­bearing's globules during the rotation of the wheels, one variable resistance (29) to compensate between the noise cur­rent of stray (parasitic) capacitance and the main current so that the photodiode (5) should not be activated by the noise current but only by the main current, one only battery (26) which is the car's battery, one system (4, 153, 6, 34) to screen from the stray (parasitic) capacities and this system consists of the strips (4, 153) and the external conductors (34, 6), finally of one pressure gauge (1) which acts as a transducer converting the changes of the air pressure inside the inflated tyre to mechanical movements of one diaphragm (40, 54) made by elastic durable material (rubber) or a tube that one of the ends is closed (69, 77, 78, 81, 82, 83, 89, 91, 101) or one bellows tube (114) so that the wire (45) can come in contact with one of the wires (43) or one of the pins (53, 58, 62, 72, 86, 104, 134) can come in contact with one of the wires (49, 59, 80) or with one of the conductors (73, 90, 92, 103, 126) where some of these contacts can be connected with the earth (28) and some of them with the strip (2) and therefore the pres­sure gauge (1) can play the role of a switch of the electrical circuit (28, 1, 2, 3, 7, 5, 9, 10, 27).

Claim 2

A device for indicating, on the vehicle's control panel inside the drivers cambinet at any time during driving or stopping, the maximum and the minimum pressure limits (lower and upper safety thresholds) in the vehicle's inflated tyres, consists of a special system of metallic strips (2, 3, 4) or (151, 152, 153) that are either one complete metallic circu­lar annular strip (2) and two segments of metallic circular strips (3, 4) parallel to (2) or one complete metallic cylind­rical surface (151) and two segments of co-axial metallic cy­lindrical surfaces (152, 153), where the strips (2, 3) from a plane condenser and (151, 152) from a cylindrical condencer of the circuit (28,1,32,5,8,9,10,27) of a high voltage transfo­rmer (10,11,12) with a ferrite core of small permeability, one amplifier (13) or (17, 16, 15, 11), one analog or digital oscillator or multivibrator or alternating current generator of frequencies 10kHz to 10MHz (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) or (14), one conductor (30) which is insulated or earthed big enough to absorb the noise alternating current which is due to the parasitic capacitance, one photodiode or loudspeaker (5) which emmits a signal to indicate the danger­ous limits of the tyre pressure,two variable resistances (9, 33) to counterbalance the variable electric resistance which appears in the rotating ballbearings on the axle of the wheels and is due to the lubricant substance that covers the ball­bearing's globules during the rotation of the wheels, one variable resistance (29) to compensate between the noise cur­rent of stray (parasitic) capacitance and the main current so that the photodiode (5) should not be activated by the noise current but only by the main current, one only battery (26) which is the car's battery, one system (4, 153, 6, 34) to screen from the stray (parasitic) capacities and this system consists of the strips (4, 153) and the external conductors (34, 6), finally of one pressure gauge (1) which acts as a transducer converting the changes of the air pressure inside the inflated tyre to mechanical movements of one diaphragm (40, 54) made by elastic durable material (rubber) or a tube that one of the ends is closed (69, 77, 78, 81, 82, 83, 89, 91, 101) or one bellows tube (114) so that the wire (45) can come in contact with one of the wires (43) or one of the pins (53, 58, 62, 72, 86, 104, 134) can come in contact with one of the wires (49, 59, 80) or with one of the conductors (73, 90, 92, 103, 126) where some of these contacts can be connected with the earth (28) and some of them with the strip (2) and therefore the pres­sure gauge (1) can play the role of a switch of the electrical circuit (28, 1, 2, 3, 7, 5, 9, 10, 27).

Claim 4

The device for indicating, on the vehicle's driving panel during driving or stopping, the minimum and the maximum pressu­re limits (safety thresholds) in the vehicle's tyres according to the claims 1 and 2 is characterized by the pressure gauge (1) which can transform the alterations of the air pressure in the vehicle's tyre to mechanical displacement either of a me­mbrane (54) with elastic properties or of a piston (137) whi­ch are pressed either by springs (55, 140) or by a compressed gas contained in a small chamber (64). The system of contacts (49, 53, 59, 58, 62) can be either in the compartment of the pressure gauge (1) which communicates with the interior of the tyre or in a compartment from the other side of membrane where the spring (55) or the compressed gas are present (situated). The elastic properties of the metallic membrane (149) can balance the air pressure.

Claim 5

The device for indicating, on the vehicle's driving panel during driving or stopping, the minimum and the maximum pres­ sure limits (safety thresholds) in the vehicle's tyres accor­ding to the claims 1, 2 and 3, is characterized by the pres­sure gauge (1) which can transform the alterations of the air pressure in the vehicle's tyres to mechanical displacements of one closed end (76, 80, 104) of various curved tubes (69, 77, 78, 82, 83, 89, 91, 99, 101) and the other end of those tubes communicates with the interior of the tyre. The displa­cement of the closed end of the tube is due to the tendency (feature) of the curved tube to become straight when a gas pressure is applied to the other open end of the tube. The pressure of the air is balanced either by the elastic featu­re (property) of the metallic tubes to keep (maitain) their curved shape or by the help of a spring (70, 71, 84, 96). The open end (85) is mounted on the base (87) and is fastened with the screws (88) where the cylindrical base (87) of a small height is made by light and durable material with a ra­dial slid and the contact (80) can move inside this slid. The thin stainless steel wire (70) has one or more turns in the place of the greater curvature so that their plane coinsides with the plane of the curvature. The tube (93, 97, 99) is a combination of cylindrical and plane tube (flat) with a stain­less steel wire (96, 97) or one thin elastic tube (96, 97) along the axis of the tube (99). The tube (101) has spiral shape around the stem (102) and the pressure gauge, which com­prises the tube (101) combines also valve's properties for air inlet in the interior of the tyre.

Claim 6

The device for indicating, on the vehicle's driving panel during driving or stopping, the minimum and the maximum pres­sure limits in the vehicle's tyres (lower and upper thresholds) according to the claims 1, 2, 3 and 4, is characterized by the pressure gauge (1) which can convert the changes of the air pressure inside the vehicle's tyres to mechanical displace­ments of one end of cylindrical tube with very thin walls that form foldings of wavy shape like bellows (114). The air pressure is balanced by the spring (121) that presses and closes the two ends of the tube (114) making an airproof se­al by the help of the flanges (120). The above pressure gauge also combines valve's properties for air inlet in the inte­rior of the tyre.

Claim 7

The device for indicating, on the vehicle's driving panel during driving or stopping, the minimum and the maximum pres­sure limits in the vehicle's tyres (lower and upper thresholds), according to the claims 1, 2, 3, 4, and 5, is characterized by a system of three insulating metallic strips (2, 3, 4 or 151, 152, 153), that help in transmission of the pressure gauge indications from the rotating wheel to the driver's cabinet panel without the rotating strip (2 or 151) to touch and ruin by continuous friction the stationary strip (3 or 152). Two of the above metallic strips (2, 3 or 151, 152) play the role of a plate or cylindrical air capacitor which uses the property as a condenser in order a signal to be transmitted from the wheel to the driving panel. Between the above metal­lic strips an alternating voltage is applied when the metal­lic strip (2 or 151) comes in electrical contact with the me­tallic rim of the wheel (28) that is connected electrically with the matallic chassis of the vehicle through the ball­bearing and axle of the wheel. Because of the alternating voltage an alternating current flows through the circuit and turns on the photodiode (5) or loudspeaker which gives a lu­minous or audible signal. Therefore the signals are transmitted through the air without electrical contacts (brush contacts) which need often substitute. The metallic strip (2) which has the form of a very thin circular annulus, can be covered by a thin layer of rubber on the lateral vertical side of the tyres (special manufacturing of tyres) or can be fixed by strong plastic holders from the circumference of the rim where the leaden balance weight are fixed on the internal side of the rim. The plane of the annular strip (2) is parallel to the lateral vertical rubber surface of the tyre and some dis­tance away from the wheel's rim not to generate a sufficient current of parasitic capacity that can turn on the photodiode (5). Current of parasitic capacity flows in the electric cir­cuit, where is the photodiode (5), when there is not any ele­ctric contact between (45) and (43). The surface of the strip (2), which is facing the vertical rubber surface of the tyre, is covered by insulating material of certain thickness which has a very small dielectric constant in order to minimize the parasitic capacity between the metallic strip (2) and the wi­re guard netting which there is inside the rubber of the ty­re. This wire guard netting can be substituted by a special plastic guard netting (kevlar) in order to reduce the parasi­tic capacity. The other side (surface) of the metallic strip (2) is covered by insulating material which has high diele­ctric constant. The same conditions are valid also for the case where the strip (2) (of very small thickness) is embodi­ed inside the rubber of the tyres that is the surface of the strip (2) facing the interior of the tyre is covered by mate­rial of small dielectric constant while the other side (sur­face) is covered by a thin layer of material of high diele­ctric constant. The strip (2) must be very near to the exter­nal surface of the wheel's rubber. The metallic strip (3) is a part (segment) of a complete circular annular strip, appro­ximately one third of the annular strip (2) of equal radius and is placed (fixed) in a proper not-rotating part of the vehicle very near and parallel to the annular strip (2). The annular strips (2 , 3) form a plane capacitor where in betwe­en the plates there is a thin insulating layer of high die­lectric constant and a thin layer of the air. The strip (4), which is covered completely by insulating material, is sligh­tly bigger than the strip (3) and is placed from the other side (back) of the strip (3) and in parallel position so that to screen electrostatically the three sides of the strip (3) from the metallic chassis of the vehicle and this strip (3) is connected with the external conductor (6) of the co-axial cable (6 , 7) to reduce the current of parasitic capacity. Circular annular strip (2) can be also formed on the vertical rubber surface of the tyre by special metallic paint. The me­tallic strips are not effected by weather conditions because the strips are insulated and for rainy weather the outer rub­ber surface of the tyres must be covered by a hydrophobia (water not loving) elastic material of small dielectric con­stant. Also another system of three metallic strips (151, 152, 153) can be used instead of the circular annular strips where the strip (151) is a complete cylindrical surface and its axis coinsides with the wheel's axis and also the length of the radius of the strip (151) is in between the radius of the wheel's rim and the outer radius of the tyre, the radii of the cylindrical strips (152, 153) are slightly bigger or smal­ler than the radius of the strip (151) and these strips (152, 153) are parts (segments) of complete cylindrical surfaces. The strip (151) is placed either on the rubber vertical sur­face of the tyre and is fastened by strong plastic holders of small dielectric constant on the circumference of the wheel's rim or it (151) is embodied inside the rubber of the tyre while the strips (152, 153) are fixed on the not rota­ting part of the vehicle. The same way of insulating and scre­wning for the circular strips is valid and for the case of the cylindrical strips. For the front wheels the strips (3 , 4) or (152 , 153) are fastened on a place which belongs to the steering wheel system. The wheel system can be electrical­ly isolated from the metallic chassis of the vehicle. Also the above strip system can be fixed in any other proper place of the wheel so that to be protected by weather conditions and to increase the capacitance of the capacitor strip system.

Claim 8

The device for indicating, on the vehicle's driving panel during driving or stopping, the minimum and the maximum pres­sure limits in the vehicle's tyres (lower and upper thresholds) according to the claims 1, 2, 3, 4, 5 and 6, is characterized by one electronic circuit (28, 1, 2, 3, 4, 5, 6, 7, 9, 10 up to 34) which is used for the total number of wheels (any num­ber of wheels). The final alternating main current depends on the frequency, magnitude and wave form of the alternating voltage of multivibrator or oscillator or alternating voltage generator (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 14) and on the amplifier (11, 15, 16, 17 or 13). The multivibra­tor, which consists of the resistances (25, 24, 22) with abo­ut 40Ω , 60Ω and 11Ω respectively, the capacitor (23) with 680 pF and 63 V, a power transistor NPN(21) with characteris­tics 2A, 300V, 1MHz (0.5 up to 5MHz) a transformer (17, 18, 19, 20) with a ferrite core (20) of special permeability and coils (17, 18, 19) with 500, 100 and 200 turns respectively, gives an alternative signal of some mWatt and frequency of about 50 kHZ. The isolated wire of the coils has 0.31 diame­ter. The frequency of the alternative voltage of the multivi­brator can vary (variate) from 10kHz up to 10MHz. Also other kinds of multivibrators or oscillators or generators of alter­native voltage with integrated circuits and crystal vibra­tors can be used. The frequency and the exit power of the signals of the multivibrator depends mainly on the capacity of the capacitor (23) (of some µF up to 500pF and 100V), on the resistances (24) (of 52kΩ up to 62kΩ ) and (22) (0.5kΩ up to 12 kΩ ) and on the variable resistance (25) (of 5Ω up to 40Ω ). This signal is amplified by the amplifier (11, 15, 16, 17) which consists of the transistor PNP(15) with characteri­stics 2A up to 10A, 400V, 0.5 up to 10MHz and the capacitor (16) of some µF which gives output of some Watts (about30V and 250mA). The transformer (10, 11, 12) with ferrite core (10) of special permeability and coils (11, 12) with high number of turns and big ratio of about 15 to 40, transforms the signal from low voltage and high current to high voltage and low current with which feeds the final circuit (27, 10, 5, 3, 2, 28). The distance between the coils (11, 12) is up to 2cm in order to avoid current of stray (parasitic) capaci­tance. The above values can be vary from aminimum up to a maximum value for increasing of the output signal and redu­cing of the stray (parasitic) capacitance current. Also dif­ferent types of transformers can be used. The external line (6) of the coaxial cable is connected with the metallic strip (4) and the one end of the coil (10) to minimize the stray (parasitic) capacitance current (noise). The frequency of the signal can be vary from few kHz to some MHz. The final power output of the circuit can vary from some tens of mWatt up to some Watts. The variable resistance (9) counterbalances the variable electric resistance, between the metallic frame of the wheel's (rim) and the chassis of vehicle, which is due to the lubricant that covers the globules of ball-bearing during the rotation and increases with the rotation speed. The resis­tance (9) reduces automaticly by a logic system if the light of diode (5) becomes weak. The intensity of the main alterna­ting current which activates the photodiode (5) depends main­ly on the dielectric constant of the substance between the strips (2, 3) or (151, 152), the area of the strip surfaces and the distance between the strips (2, 3) or (151, 152), the voltage, the frequency and the kind of the signal waveform on the ends of the coil (10) as well as the impetance of the cir­cuit (28, 2, 3, 5, 7, 8, 9, 10, 27). The power variable resis­tance (33), which is connected in parallel with the photodio­de (5), takes values of 4kΩ up to 1.5kΩ with 2.2kΩ and a tole­rance of 10% for maximum signal. The electronic circuit also contains a system of electrostatic screening (34) for stray (parasitic) capacities of the sections (33, 5, 8, 9) and vari­ous current conductors, one analog or digital milliamperome­ter (8) one isolated conductor (30) quite large for the abso­rption of the stray (parasitic) capacities of alternative cur­rent and one variable power resistance (29) for setting the current which is due to the stray capacities. So that this current must not activate the photodiode and at the same time the main alternating current not to be significantly attenua­ted. The electrostatic screening (34) is connected with the one end of the coil (10) with which the strips (4) or (153) are connected through the resistance (29). The whole system (34, 4, 153, 6, 29, 30) is used to minimize the stray (parasi­tic) capacity current. To avoid large stray (parasitic) capa­ cities, which could activate a loudspeaker or the photodiode (5) more circuits are used (28, 2, 3, 4, 5, 10, 27) or ( 28, 151, 152, 153, 5, 10, 27) that is for each such circuit a small number of wheels is used. So in the driving vehicle's panel more photodiodes are used of which each one corresponds in a small number of wheels. In this way the wheel which has the dangerous pressure is detected in shorter time. A techni­que to avoid the stray (parasitic) currents is to use a spe­cial relay current governor in the circuit (28, 2, 3, 4, 10, 27) instead of the photodiode (5). The relay current governor, which is energized only by the main current and not by the current which is due to stray (parasitic ) capacitance, clo­ses one separate circuit which contains one electric bulb 12V and the vehicle's accumulator (battery). In another type of oscillator a gate NAND is used to produce square signals. The frequency of oscillation depends on the resistance which is connected with the output and input of the NAND and one capa­citor between the input and the ground. The connected transis­tor NPN is used as an amplifier and is connected also with the coil (11) which is used as a load of the transistor. In order to increase the current there is a possibility to use two tra­nsistors in DARLINGTON connection instead of one. The situati­on is improved when the gap between the two parts of the ferri­te core (12) is minimized and also when the number of turns in the coils (11) and (10) are inreased as more as possible. In some special case the outer conductor (6) can be connected only with the conductor (30) through the variable resistance (29) and not with the high voltage coil (10). One of these cases is that when the wheel system is isolated from the chas­sis of the vehicle and so that the conductor (30) can be con­nected with the negative of the battery and this conductor (30) can be also the metallic box of the electronic device. The other end of the coil (10) is connected with the isolated wheel system and there is not electrical conduct between the two coils (10) and (11). Also in order to reduce parasitic capacitances the strip (2) is not a complete ring (annulus) but only a part (segment) of it which has a surface about equ­ivalent to the surface of the strip (3). The strip (3) is bet­ter to be surrounded by the strip (4) around the three sides so that no parasitic capacitances will be possible with the metallic chassis of the vehicle. The parasitic current will be cut off by a comparator. The area of the strips (2) and (3) can be increased by folding and making double the one surface and inserting the other one.

Claim 10

The device for indicating, on the vehicle's driving panel during driving or stopping, the lower and the upper limits (lower and upper thresholds) of the pressure in the tyres, according to the claims 1, 2, 3, 4 and 5, is characterized by contacts of special substances (ceramic or other substan­ces) which have conducting properties and they are worn out hardly. In this case the circuit is very simple, that is, it consists of one pressure-gauge (1) conduction system, an elec­tric bulb and the vehicle's accumulator with the grounds (27) connected with the vehicle's chassis and (28) connected with the wheel's rim. The contact system consists of an isolated electrically metallic ring, which is placed on the metallic frame of the wheel (rim) or on the rubber of the tyre and of the substance which is in contact continually with the metal­lic ring. Also the present invention can transmit signals from the wheels to the driver's cambinet with electromagnetic cou­pling by using electromagnetic coils on the rotating and not rotating part of the vehicle instead of the system of the strips (2, 3, 4) or (151, 152, 153).