FR2814984A1 - Device, for warning driver of tractor-trailer or truck of low tyre pressure, has sensors placed in wheel rim which send signal to driver's cabin in case of under-pressure - Google Patents

Abstract

The device includes a casing (4) having an electronic unit, the pressure sensor, an inertial contact and a battery block (5) fixed about the wheel rim (1) by two collars (2, 3). The pressure sensor is open if the pressure is at the right value. When the wheel rotates, the contact is closed and current flows to the sensor. If the pressure is low the sensor closes the circuit and the electronic unit sends a signal to a unit in the driver's cabin, which sounds an alarm or lights up a warning light.

Description

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pneumatiques surtout sur la remorque Le résultat est souvent la destruction du pneumatique. The present invention relates to a device for detecting tire pressure in good time on trucks and their trailers as well as on coaches. While driving it is very difficult for a truck driver to notice one of his driver's deflation in time.

tires especially on the trailer The result is often the destruction of the tire.

Currently, there is no device that can be easily installed on trucks or coaches that would allow tire pressure to be detected in time.

The device according to the invention overcomes this drawback. It is an electronic system composed of a pressure sensor and a transmitter whose range is sufficient to reach a receiver placed in the cab of the truck. The system is fixed inside the rim by two long plastic clamps, and is only active when the vehicle is running, this thanks to an inertial contact inserted in its supply line When the pressure is correct the pressure sensor cuts the power supply to the transmitter, if the pressure drops below a certain threshold the sensor authorizes the power supply to the transmitter which will send a coded signal received by the receiver.

 The accompanying drawings illustrate the invention Figure 1 shows the device fixed to the rim Fig 2 shows the base of the sensor seen from above and in section Figure 3 shows! the upper part of the sensor seen from above and in section Figure 4 shows the sensor assembled and \ u in section.

Figure 5 is the block diagram of the device.

Figure 6 is the diagram of the electronics placed in the rim.

 FIG. 7 is the diagram of the receiver placed in the cabin. FIG. 8 represents the printed circuit of the transmitter.

FIG. 9 represents the printed circuit of the receiver.

Figure 10 shows the battery pack.

FIG. 11 represents the assembled electronic part. FIG. 12 represents the box intended to receive the electronics.

Figure 13 is a sectional view of the electronics permanently fixed in its housing.

 Figure 14 shows the passage of the clamps fixing the battery pack and the electronics block.

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1 Figure 15 detailc c inertial contact by a sectional view, a top view and a bottom view.

With reference to these drawings as shown in FIG. 1, the two co1Jiers (2 and 3) fix the h around the rim (1)! oc (4) containing the electronics. ! c pressure sensor and inertia contact, opposite the pi block! es (5).

The pressure sensor (6) consists of two blades. The first is the base detailed in Figure 2. By a \ ue top and a sectional view This one consists of a piece mcta! ! ique (6-l) square about 1 5mm thick and 2.4cm side which has in the center a circular bowl (6-2) deep îmm, with a diameter of 1. 6cm and pierced with a very small, bare (6-3) of some tenths of a mm. A metal wire artery, of which A '(6-4) about one cm long is fixed to the bottom by a weld ( 6-6). A plastic washer (6-5) with a diameter of about imm and a height of about 0.4mm is glued to the blade (6-4). The second part of the sensor 1 tl '-' above, and a view which is! he upper part is represented by a top view and a cross-section view in FIG. 3. It is composed of a metallic sheet (6-7) square of about 2.4 cm on side, 0.3 mm thick and drilled in the center of a hole (6-8) 2mm in diameter.

At 2mm from the hole and arranged in a circle to be leveled, 6 silicone dots (6-9) are glued with a height of approximately 0 6mm and the sides of which are approximately i. 5mm. The movable part of the sensor is then glued to the upper face of the sheet (6-7). It is a flexible metal feutlle (6-10) with a square shape of about 2. 3cm on the side and 8 hundredths of a mm in size (r) latct'6-1 0-1 key 1 thick . e! ! c has in the center a platc circcary part (6-10-I) of 1 cm in diameter raised by about 0.6 mm by its inc edge! iné (6-i0-2).

The upper part and the base are then assembled which forms the 1 4 is l''t. 1 pressure sensor shown in section in Figure 4 The assembly is done by gluing with a ptastic sheet (6-H) electrically interconnecting the two parts (6-1) and (6-7). During assembly it will be glued in reinforcement between parts 6-1 and 6-7 six plastic washers (6-! 2) oi, 1 1 1c of about 2mm in diameter and 1 mm high EUes will be distributed in such a way that each one corresponds to the position of a silicon point (6-9). To create a slight vacuum. ! a meta sheet! iique) 6-i0) will be pressed until its center is in contact with the part (6-71 and will not be released until the hole (6-3) has been plugged with a cohesive point or weld point Two electrical wires (6-13) and (6-! 4) will then be soldered, 1. one on the part (6-7) and the other on the part (6-1).

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The electronic system used (es) represents in a synoptic form in FIG. 5. It comprises a power supply unit (5) composed of four small flat folds of 3 volts connected in series in order to obtain i2 \ olts. The batteries for the example of the description under Indicative, but not Hmitative will be of the CR2032 type. Between the most power supply and the most encoder transmitter M) are inserted in series, the contact has inertia) and the presslon sensor (6) When the, ducule is rolling, the contact (sI) is closed If the pressure drops below the threshold determined by the sensor (6d, this one closes, The transmitter (EM) is supplied and sends a coded signal received and identified by a small independent receiver (ROC) placed in the cabin which gives the alert by a sound and light signal.

The scheme é! The electronic encoder transmitter is shown in Figure 6. Its power is supplied by four small cr 2032 type lithium batteries placed in series. The encoder is built around an integrated circuit IChum3750m) which is an encoder whose number of possible codes is 4096 Its supply voltage must not exceed Il volts, it is inserted between the most! 2 sees and its pitch vcc '-' diodes dl and d2 which drop the voltage of 1, 2vole This circuit has an internal time base whose frequency is determined by the resistance N and the capacity cl on! a pin 15 the voltage applied to the pin! 7 determines whether the circuit will be in coding mode or in decoding mode. The voltage will be 0 \ oit in decoding mode and equal to the encoding supply potential. which is the case. Spindle ! 7 is therefore connected to pin 20 Hn code among 4096 is determined by your inputs 1 to 9 and 12 to L4 depending on whether eHes are grounded or left in the air. in the example given the code is determined by pins 2 and 6 grounded and the other pins left in the air.

Pins 10 and 1 i are not used on this circuit. The coded stgnaf goes out ~, coded tial goes out on pin 19 and is directly used to modulate the transmitter on its pin 6. This one must be able to transmit digital signals. Numerous schemes exist and the selection criteria will be based on the side therefore marked on the carrier frequency used and the transmission power. For the description, a commercial circuit has been chosen as an indication and in no way limiting: mipot tx 433. Its transmission frequency is 433. 92 MHz and its power is 8 mW. 1i receives the li \ o! ts on pins 1 and 2. Pins 3 and 4 are grounded. The signal from pin 19 of the encoder (ic!) Is applied to input 6 of the transmitter! ic2) which is its modulation input. It is a modulation in

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tout ou rien c'est a dire qu'il y a porteuse si cette entrée est à Fêta) haut et pas de porteuse si cette entrée est à l'état bas. La porteuse hui est donc découpée à Limage des créneaux qui sont appliques sur l'entrée 6. Pour assurer une portée convenable ! a porteuse sortant sur la broche 5 de ! c2 est transmise à un amplificateur hf par le condensateur c2 () OOpF) Cet amplificateur est composé des résistances r2 (68 ohms), r3 (27k), du transistor tt (bfr 90), de la seif Ll (lOmicroH), du condensateur c3 (lOOp) et de la bobine 1, 2 (4 spires de t'tl de cuivre rigide de 0 5mm de diamètre enroulées sur une longueur d'environ Icm Le diamètre des spires sera de 4mm.

all or nothing is to say that there is carrier if this entry is at Feta) high and no carrier if this entry is in the low state. The carrier is therefore cut out at the image of the slots which are applied on entry 6. To ensure a suitable range! has carrier going out on pin 5 of! c2 is transmitted to an hf amplifier by the capacitor c2 () OOpF) This amplifier is composed of the resistors r2 (68 ohms), r3 (27k), the transistor tt (bfr 90), the seif Ll (lOmicroH), the capacitor c3 (lOOp) and the coil 1, 2 (4 turns of rigid copper t'tl 0 5mm in diameter wound over a length of about Icm The diameter of the turns will be 4mm.

FIG. 7 represents the diagram of the reception part. As with the transmitter, many receiver schemes exist. Any scheme can agree as long as this receiver is tuned to the transmitter and accepts digital signals. This is why it has been chosen for the description, by way of indication and in no way limiting, a commercial hybrid circuit reference r am 433 compatible with the transmitter. This icr licsi receiver supplied on these pins 1.! 2 and 15 by the f 5 \ oits from the regulator (reg i) LM 7805 of which the least is connected to ground.

The input of the regulator can be connected either on batteries with a minimum voltage of about 5 volts, either on the cigar lighter socket. The signal is received by the antenna on pin 3 of icri. The digital signal goes out to pin 14 and is applied to pin 16 of the decoder (icr 2). This circuit is a UM 3750. It is the same as that used for the emission but circuit is uii UM in normal version whereas that of the emission is in cms version which ~ uc. Pins 1-, 1 1 serve 'def'n' creates a small pinout difference. Pins 1 a) 2 are used to define the codes retained. To be compatible with the coding of the transmitter, pins 2 and 6 will be grounded and the other coding pins will not be connected. To be validated as a decoder, pin 15 (select mode) is grounded. The frequency of the internal clock is determined by cry (loop) and rrl (100k) on pin 13. The 5 volts is connected to pin 18 and the least to pin 14. When a recognized signal is present on pin 16 from here 2. the output (pin! 7) goes to Fêtai bas This state ,, ur hi u bas is transmitted to the sorting base by RR3 (4, 7k) The sorting base (2n 2907) which is of pnp type becomes negative \ e with respect to its transmitter which makes the transmitter passable. The most 5 volts is therefore present on its collector which feeds the buer (hu) and the ied (1.1) which is connected by RR2 (220 ohms) The printed circuit of the transmitter with its location seen on the copper side is shown figure 8. The receiver circuit board with its layout

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vu cote composant es ! représente figure 9. Celui ci sera place dans un quelconque boitier en plastique. Sil est alimenté par pile il pourra etre intégré dans un pendentif de rétroviseur.

seen component rating es! represents figure 9. This one will be placed in any plastic case. If it is powered by battery, it can be integrated into a mirror pendant.

The battery pack (5) is shown in Figure 10 It is made up of 4 small flat and 2032 batteries (5-1) connected in series by 3 small welded strips (5-2). Two small electrical wires (5-3 and 5-4) will be soldered. one on the +12 volts and the other on the least. The assembly is then coated with a hard plastic poured over it and forming the battery pack (5). Its shape will be rectangular and it will have two slots (5-5) for the passage of the fixing collars (2 and 3). Its length will be 10 cm, its width of 2. 3 cm and its depth of It will be slightly curved in! c lengthwise to perfectly fit the shape of the rim.

The entire electronic part is then assembled as in Figure 11. The inertia contact if is connected to the printed circuit (ci) with one of its poles at point A, and the second pole at point B. The pressure sensor (6) is connected to points C and D. The two wires (5-3 and 5-4) from the power supply are connected at their respective points + and - on the printed circuit. The antenna wire is soldered to point E of the printed circuit. It will be 17 cm long.

The box containing this assembly is shown in Figure 12. It is a plastic box (4) having a length of 13 cm, a width of approximately 2.5 cm and a thickness of 5 mm. It has 2 slots (4-1) intended for the passage of the 2 fixing collars (2 and 3). Its underside has a slight rounded shape to adapt to the rim. The electronics are then placed in the casing and then permanently fixed by an adhesive or a resin (4-2) cast over it. Only the upper part of the sensor will not be covered.

The completed assembly is shown in section in Figure 13.

bloqués par collage. Leur position sera telle qu'une fois ! e système piacë sur lajante. tls se retrouvent dlaméu'a ! ement opposés Les deux colliers et 3) pourront cire des colliers rilsan comme ceux utilisés pour fixer les cables électriques. Un des deux colliers supportera les fils 5-3 et 5-4 et l'autre le fil (anti qui fait office d'antenne. As shown in Figure 14 the battery block (5) and the electronic block (4) are then assembled with the two fixing collars (2 and 3) then

blocked by gluing. Their position will be such as once! e piacë system on the rim. They find themselves dlaméu'a! The two collars and 3) can wax Rilsan collars like those used to fix the electric cables. One of the two collars will support wires 5-3 and 5-4 and the other the wire (anti which acts as an antenna.

The detai! of the inertia contact is shown in Figure 15 by a view in 'e detail of the contact'c inet @ tie is shown in section, a top view and a bottom view.

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pour cela que l'on s'élOIgne de la présente Invention. It is a 3cm long plastic case. 5mm wide and 5mm thick. One of its ends is thicker and supports a flexible contact blade 1 with a length of -, - iron 2. 8 cm and about i 5mm wide At the end of this blade is a counterweight (5- 1-3) about 1 gram A second lamc. fixed .. (5-1-4) is coiled in front of the end of the first (5-1-2) When the vehicle is moving, the counterweight by centrifugal force pushes the blade (5-1-2) which comes into contact with the blade (5-1-4) It is understood that the present invention is not limited to the embodiment given for the description as an indication but in no way limitative and that numerous modifications can be made without

for this reason, we depart from the present invention.

The retaining collars (2 and 3) may be of a material other than plastic.

qu'il ne soit pas trop sensible à ta vitesse de rotation de la roue et aux écarts de température Dans un exemple non représenté un seul collier plus large pourrait etre utilisé pour la fixation à la place des colliers (2) et (3). The pressure sensor may be of a different design provided

that it is not too sensitive to your speed of rotation of the wheel and to temperature differences In an example not shown, a single larger collar could be used for fixing in place of the collars (2) and (3).

In another example not described, a small thermal contact could be added in parallel to the pressure sensor (6) which would make it possible to detect overheating of the rim.

The device according to the invention is particularly intended for on-board detection of tire pressure on trucks and coaches.

Claims (1)

 l) Device for the future the driver of a truck with or without a trailer or of a coach for a loss of pressure on one of e'-. tires characterized in that it comprises a very flat battery block and a flat electronic control unit capable of transmitting an alarm in the passenger compartment by radio link when the vehicle is traveling and fixed around the inside of the rim by two fixing cookers. 2) Device according to claim 1 characterized in that the two fixing collars (2 eT 3) support and fIxent the battery block (5) and the electronic block (4) around the inside of the rim. 3) device according to claim 1 characterized in that the electronic (ci, SI and 6 is integrated in a very flat boitl'erl "4) fixed on the inside of the rim and the underside of which follows the roundness of the rim 4) Device according to a claim, characterized in that the batteries (5-1) have coated you with a plastic poured over them forming their boot (5) whose shape matches the rounded rim of the rim. 5) device! on (a claim i characterized in that 1 electronic comprises a Hienie contact (SI) making it active only when the vehicle is wheeled 6) device according to claim j characterized in that the electronics directly reach the passenger compartment by radio wave. 7) device according to claim) or! has claim 6 characterized in that the signa! is received and transmitted to the driver by a small independent receiver (rock) placed in the passenger compartment