Title of Invention

IMPROVED VALVE UNIT FOR TIRE PRESSURE MONITORING SYSTEM AND A PROCESS FOR INCORPORATING THE UNIT IN TUBE-TIRES

Abstract

The invention disclosed in this apphcation relates to an improved valve unit for tire pressure monitoring system and a process for incorporating the unit in tube-tires. The present invention also relates to a tire incorporating the said improved valve unit and a sensor unit. Further more the present invention also relates to a Tire Pressure Monitoring System (TPMS) for Tube-Tires incorporating the said tube.

Full Text

the sensor units via inbuilt antennas. The signals are received by the display unit and are displayed after suitable processing. A typical TPM System of tubeless tires a consists of a valve unit, a sensor unit and a display unit. A typical TPM System (for example that of Orange Electronics, Taiwan) as mounted in a automobile wheel and a valve Unit of the TPM System of tubeless tires are shown in the Fig s 1 & 2 , respectively of the drawing accompanying this specification, The TPM system consists of a valve unit (1) and a sensor box (2). The valve unit (1) is fixed in the rim of the wheel (3) and the sensor unit (2) is located in the cavity (4) formed between the rim (3) and the tube-less tire (5). The sensor box (2) has a hollow portion (11) which fits in the dome (6) of the valve unit (1) and is held together by means of bolt (12) which has an axial through hole to facilitate inflation. The valve unit (1) has a cylindrical metallic stem (5) and a dome (6) which is an integral part of the cylindrical stem , the dome being provided with a threaded hole(7) and a rubberized portion (8). The rubberized portion (8 ) has a circumferential groove (9) for fixing in the corresponding edge of hole (10) in the rim of the wheel (3) as shown in Fig.l. The sensor box (2) houses the electronic components namely, the pressure and temperature sensors, the controller chip, the transmitter circuitry, the antenna and battery (not shown). Another TPM System available, for example that by Tire Sentry, USA. where the sensor units are attached from outside the tires, and are merely screwed on the valve stem externally which is shown in Fig. 3 . This system consists of a sensor unit (13) and a valve unit (14) The valve unit (14) is fixed inside the wheel rim (15). The rim (15) supports the tire (16). The sensor unit (13) houses the pressure sensor, the associated electronics, the transmitter and battery (not shown). The sensor unit (13) has a threaded hole (17) which communicates with the pressure sensor within the sensor unit (13). The threaded hole (17) of the sensor unit (13) is screwed in from outside to the threaded neck (18) of the valve unit (14), thereby communicating the pressure within the tire (16) to the sensor unit (13). All TPM Systems such as the one explained above, presently available for fitment inside are designed for tube-less tires. The one TPM System available for tube tires involves fixing the sensor unit outside tube. Such systems have the major drawback of ease of pilferage, as they can be easily removed from parked vehicles. Moreover, these units have to be removed each time the tires have to be inflated. Hence such systems are not likely to be popular. Tubeless tires are predominant in the western developed world. In India, though tube-less tires have entered the market, the predominant design are the conventional tube-tires. Thus the currently available TPM Systems cannot be fitted in a majority of the vehicles in India and several other countries. In other words, currently there is no suitable TPM System for tube- tires which is safe and economical. It would be useful, if a suitable TPM system which is useful in tube tires, is made available which would be useful to monitor the pressure and temperature of each individual tube tire, both when the vehicle is stationary and when it is moving. Such a system would also help in increasing the safety and also would help in maintaining the correct pressures in the tube tires, thereby improving fuel consumption and life of the tube- tires. Therefore the main objective of the present invention is to provide an improved valve unit useful in a Tire Pressure Monitoring System (TPMS) for incorporating in Tube-Tires. Another objective of the present invention is to provide a method of incorporating the improved valve unit and a sensor unit in Tube-Tires. Still another objective of the present invention is to provide a tire tube incorporating the improved valve unit and a sensor unit inside it. Yet another objective of the present invention is to provide a TPM System with a tube tire incorporating the improved valve unit and a sensor unit. The above objectives of the present invention have been achieved by us by developing an improved valve unit which can be used to house the sensor unit within the tube and can be used along with the known TPM System. In the accompanying figures, Fig 4 shows the improved valve unit of the present invention; Fig 5 shows the sensor unit provided with an abutment; Fig 6 shows the sensor unit attached to the improved valve unit of the invention; Fig 7 shows the tube tire incorporating the improved valve unit of the present invention together with the sensor unit; and, Figs 8 (A) & 8( B) show the TPM System for tire-tube . Accordingly, the present invention provides an improved valve unit (19) for tire pressure monitoring system which comprises a cylindrical hollow metallic stem (20 ) provided with a threaded hole (21) at its bottom through which a dome (22), which is capable of being fixed to the metallic stem ( 20) through the hole (23), the metallic stem ( 20) being also provided with an internal thread into which a valve core ( 24 ) capable of being screwed in, a moulded rubber flange ( 25 ) being bonded to the metallic stem (20) at the valve neck (36) to form a hermetic seal, the sensor unit (26) being provided with a sensor box (27) which is hollow , within which the sensors for pressure and temperature, electronics unit with transmitter, antenna, battery and control logic are capable of being housed , the top of the sensor box (27) being provided with a hollow domed surface (28) having a hole (29), an abutment piece (30) made of hard rubber being attached to the longer side of the sensor box (27),the abutment piece (30) being designed such a way that after final assembly, a gap (37) is maintained between the valve stem (20) and wheel rim (32) to facilitate inflation of the tire. According to another embodiment of the present invention there is provided a method of incorporating the improved valve unit and a sensor unit inside a tube -tire which comprises (i) Fixing the improved valve unit (19) defined above into the wall of the tire- tube (31) through the rubber flange (25) by a conventional vulcanising process, (ii) Curing the tire - tube so obtained in step (i) by conventional method, (iii) Slitting the tire- tube obtained in step (ii) at a place proximal to the place where the valve unit is fixed, to provide an opening for insertion of the sensor unit, (iv) Attaching a sensor box (27) with an abutment piece (30) on the side of the sensor box (27) to the inner surface of the tube on the edge of the wheel rim (32), (v) fixing the sensor unit (26) with the abutment (30) and a dome (22) to the valve unit (19) which is affixed to the tube, by means of a bolt (33) with an axial hole in such a way that the dome (22) mates with the hollow domed surface (28) of the sensor box (27) and that the abutment fixed to the sensor box, firmly resting on the inner surface of the tube (31), (vi) Resealing the slit made in the tube in step (iii) above by conventional vulcanizing process to restore the closed tire tube and (vii) Fixing the tube resulting in step (vi) on to the wheel rim (32) and tire (34) by conventional method, with the metallic stem (20) of the valve unit inserted through hole (35) in the wheel rim (32). The slitting of the tube in step (iii) may be a radial cut which completely severs the tube or providing a small incision in the tube the former being the preferred one. The preferred way of joining the slit tube in step (vi) is through a lap joint. An important consideration for the tube-TPMS is the proper location of the sensor unit within the tube so that all the loads imposed on it are properly supported. In particular, there is a strong centrifugal force on the sensor unit (26) as it rotates within the wheel. For example when the automobile is traveling between 100 kmph to 150 kmph, the centrifugal force would vary from about 6 kg to about 10 kg. This force is transmitted partially through the abutment (30) attached to the sensor box and partly through bending of the valve neck (36) of the valve unit (19). The valve neck (36) is partly supported by the edge of the hole (35) in the wheel rim (32). The abutment (30) fixed to the sensor box ensures that a gap (37) of about 3 mm is maintained between the valve stem (20) and the rim of the wheel ( 32 ). The rubber portion of the valve unit (19) and the tube components have to be designed to avoid high local stresses within the valve tube assembly. Another important consideration for incorporating the sensor unit within a tube is to avoid exposure of the sensor unit to the high temperature steam environment used in the manufacture of the tube, which could damage the electronic contents of the sensor box. This problem has been obviated in the process of the present invention as follows. During the manufacture of the tube, only the valve unit, without the sensor unit, is vulcanized and cured with the tube as described in steps (i) to (iii) described above . Also, the resealing of the slit in step (vi), involves local vulcanizing which does not affect the sensor unit fixed within the tube. According to another embodiment of the invention there is provided a tire-tube incorporating the improved valve unit of the invention together with a sensor unit. According to still another embodiment of the invention there is provided a TPM System comprising the tire tube incorporating the improved valve unit of the invention together with a sensor unit in each tire of the vehicle and a display unit located inside the vehicle. The functioning of the TPM System for the tube tire according to the present invention is described below with reference to fig 8(A)&(B). The automobile (38) has four wheels fitted with tube tires (34) incorporating the improved valve unit(19) of the invention attached to the sensor unit (26) by the method as explained above. The display unit (39) of the TPM System is located within the car cabin at any suitable place easily visible to the driver. The cable (40) is attached to the display unit (39) and plug (41) inserted into the standard cigarette-lighter socket (not shown) in the car, to provide electrical power to the unit. The display unit (39) houses the usual receiver electronics, antenna, display electronics (not shown) and display devices. In one embodiment of the invention , the front face of the display unit has four light emitting diodes (l.e.d.s) (42) representing each of the car wheels; two l.e.d.s (43) indicating the parameters being displayed, viz. the tire pressure (psi) or the tire temperature (° C); a digital display (44); a function button (45) and an audio alarm (46). When the ignition switch of the car is switched on, the TPM System is activated. The sensors present in the sensor units (26) which are located in the tires continuously sense the pressure and temperature within the tube-tires. The digital values of the pressure and temperatures are periodically and sequentially transmitted through the built-in radio transmitters in the sensor units. The data are received by the receiver in the display unit (39) and displayed through the l.e.d.s (42) and digital display (44). Different modes of display are provided which can be selected through operation of the mode button (45). In one mode, the pressure value in each of the tires is periodically displayed on the display (44). The respective l.e.d. (42) lights up, indicating the particular wheel of which the pressure is being currently indicated. The l.e.d. glows in green colour if the pressure is above a pre-set limit. In case the pressure is below the pre-set limit, the l.e.d. glows in red colour and also the audio alarm (46) within the display unit (39) is set off, thus warning the driver of an abnormal condition in the tires. In another mode, the temperature in the tube-tires is similarly indicated through the l.e.d.s (42) and the digital display (44). The l.e.d. (42) glow in green colour if the temperature is below a preset value and in red colour when the temperature is above the preset value. The l.e.d.s (43) indicate which parameter (ie. pressure or temperature) is being currently indicated. The mode button (45) can also be used to preset the levels of pressure and temperature at which the alarms are activated. In this way the driver is continuously informed about the pressure (and temperature) in each of the tube-tires, both when the vehicle is stationary and when it is moving. Thus before driving off, the driver can inspect the pressures in all the tires and inflate the tires if necessary. During travel, if there is a pressure loss in any tire, the driver is immediately warned through the audio-visual alarm in the display unit and necessary corrective action can be taken. Advantages of the invention 1. The TPM System incorporating the improved valve unit of the present invention is useful for tire- tubes. 2. The TPM System incorporating the improved valve unit of the present invention helps to monitor the pressure and temperature of each individual tube tire , both when the vehicle is stationary and when it is moving. 3. The TPM System incorporating the improved valve unit of the present invention helps in increasing the safety of the vehicle and occupants by giving immediate alarm in case of drop in pressure of any tube tire, 4. The TPM System incorporating the improved valve unit of the present invention helps in maintaining the correct pressures in the tube tires, thereby improving fuel consumption of the vehicle and life of the tube tires. 5. The valve unit and the sensor unit attached being housed inside the tube they cannot be removed from parked vehicles. Hence there is no danger of pilferage. 6. The is no requirement of removing the valve unit and the sensor unit each time the tube tires have to be inflated. 7. The TPM System of the present invention is economical. We Claim 1. An improved valve unit (19) for tire pressure monitoring system which comprises a cylindrical hollow metallic stem (20 ) provided with a threaded hole ( 21) at its bottom through which a dome (22) , which is capable of being fixed to the metallic stem ( 20) through the hole (23), the metallic stem (20) being also provided with an internal thread into which a valve core ( 24 ) capable of being screwed in, a moulded rubber flange ( 25 ) being bonded to the metallic stem (20) at the valve neck (36) to form a hermetic seal, the sensor unit (26) being provided with a sensor box (27) which is hollow, within which the sensors for pressure and temperature, electronics unit with transmitter, antenna, battery and control logic are capable of being housed , the top of the sensor box (27) being provided with a hollow domed surface (28) having a hole (29), an abutment piece (30) made of hard rubber being attached to the longer side of the sensor box (27),the abutment piece (30) being designed such a way that after final assembly, a gap (37) is maintained between the valve stem (20) and wheel rim (32) to facilitate inflation of the tire. 2. A method of incorporating the improved valve unit and a sensor unit inside a tube -tire which comprises (i) Fixing the improved valve unit (19) defined above into the wall of the tire- tube (31) through the rubber flange (25) by a conventional vulcanising process, (ii) Curing the tire - tube so obtained in step (i) by conventional method, (iii) Slitting the tire- tube obtained in step (ii) at a place proximal to the place where the valve unit is fixed, to provide an opening for insertion of the sensor unit, (iv) Attaching a sensor box (27) being provided with an abutment piece (30) on the side of the of the sensor unit (26) to the inner surface of the tube on the edge of the wheel rim (32), (v) fixing the sensor box (27) with the abutment (30) and a dome (22) to the valve unit (19) which is affixed to the tube, by means of a boh (33) with an axial hole (in such a way that the dome (22) mates with the hollow domed surface (28) of the sensor box (27) and that the abutment fixed to the sensor box , firmly resting on the inner surface of the tube (31), (vi) Resealing the slit made in the tube in step (iii) above by conventional vulcanizing process to restore the closed tire tube and (vii) Fixing the tube resulting in step (vi) on to the wheel rim (32) and tire (34) by conventional method , with the metallic stem (20) of the valve unit inserted through hole (35) in the wheel rim (32). A method as claimed in claim 2 wherein the slitting of the tube in step (iii) is effected by providing a radial cut facilitating completely severing of the tube or by providing a small incision in the tube , the former being the preferred one. A method as claimed in claims 2 & 3 wherein joining the slit tube is effected through a lap joint. A tire- tube incorporating the improved valve as claimed in claim 1 incorporating a sensor unit. A TPM System comprising the tire- tube incorporating the improved valve imit of the invention together with a sensor unit in each tire of the vehicle and a display unit located inside the car. An improved valve imit usefiil for tire- tube monitoring system substantially as herein described with reference to the Fig. 4 A method of incorporating the improved valve unit as claimed in claiml and a sensor unit inside a tube -tire substantially as herein described. A. TPM System for tube- tire substantially as herein described with reference to the Fig 8 A and B of the drawings accompanying this specification.

Documents:

1228-CHE-2008 AMENDED PAGES OF SPECIFICATION 06-03-2013.pdf

1228-CHE-2008 AMENDED CLAIMS 06-03-2013.pdf

1228-CHE-2008 AMENDED CLAIMS 07-05-2013.pdf

1228-CHE-2008 AMENDED CLAIMS 14-02-2014.pdf

1228-CHE-2008 AMENDED PAGES OF SPECIFICATION 14-02-2014.pdf

1228-CHE-2008 CORRESPONDENCE OTHERS 06-03-2013.pdf

1228-CHE-2008 CORRESPONDENCE OTHERS 07-05-2013.pdf

1228-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 14-02-2014.pdf

1228-CHE-2008 FORM-13 06-03-2013.pdf

1228-che-2008-abstract.pdf

1228-che-2008-claims.pdf

1228-che-2008-correspondence-others.pdf

1228-che-2008-description-complete.pdf

1228-che-2008-drawings.pdf

1228-che-2008-form-1.pdf

1228-che-2008-form-18.pdf