AN EXTERNAL TIRE PRESSURE MONITORING SYSTEM FOR OFF-HIGHWAY VEHICLES
FIELD OF INVENTION
[0001] The embodiments herein generally relate to tire pressure monitoring systems. More particularly, the invention relates to a wheel mounted tire pressure monitoring system for monitoring tire pressure of an off-highway construction or earthmoving vehicle through wireless communication.
BACKGROUND AND PRIOR ART
[0002] In general, a tire pressure monitoring system is basically a system that is electronic in nature and is designed to be able to monitor the amount and consistency of air pressure prevalent on the inside of pneumatic tires on any sort of vehicles. It is a known fact that a pneumatic tire’s dynamic behavioral mechanism is closely associated with that of its inflation pressure. The air pressure in the vehicle pneumatic tires should be maintained within a particular range to protect against tire damage or failure and to promote safe and efficient operation of the vehicle. For example over inflated or under inflated tires may cause wear, internal tire damage and increased risk of tire penetration by sharp objects, tire blow outs and or reduced fuel economy. The system is generally designed to be able to report information with regard to real-time tire pressure to the driver, usually via a pictogram display and to generate an alert if the tire pressure falls outside of the desirable range for the tire. This system is available to be included both at the factory level as well as an aftermarket solution.
[0003] The tire pressure system can be operated in two different ways either by measuring the pressure directly through pressure sensor or by relying on speed sensors attached to the wheels. The direct tire pressure monitoring system typically relies on the pressure monitoring sensors installed inside each tire so as to be able to provide very accurate data in reference to the same and provide a comparatively better output than the indirect mechanism which relies on the wheel speed sensors.

[0004] A TPMS module may incorporate a sensor attached to the tire or wheel rim and means for transmitting the pressure information to a receiver. In addition to that, the tire pressure monitoring system can be positioned either externally or internally. [0005] In the prior art US8373551, a pressure sensor module is installed inside the tire. The pressure sensor module configured for transmitting the pressure data by wireless RF signal to the monitor located in the driver compartment of the vehicle is disclosed. But with this method the system installation and battery replacement may be very inconvenient. Also the signal transmission is weak and blocked by the steel belts embedded inside the tire.
[0006] In another prior art US 8567241, a pressure sensing and transmission device is mounted in the inner end of the tire valve. In this method also battery replacement would be inconvenient. Also this arrangement is not suitable for earth moving and construction vehicle rims which are having flat base and no well. As a result the mounting and removal of tires would be inconvenient.
[0007] In another prior art US 20090058667, a pressure sensor is secured to the inside of the tire surface by a patch. In this method the rotation of the tire from one position to other on the vehicle becomes tedious as it involves recalibration or removal and pasting the patch on the new tire in the field.
[0008] In some other prior US7441452B2, a pressure sensor is removably attached to the wheel and secured by a band and buckle. The assembly and removal of tires becomes tedious and care to be taken to avoid damages to sensor during such operations.
[0009] In yet another prior art familiar to those in this trade, a pressure sensor is mounted on the valve stem outside the tire. This method has the advantages of easy installation and good signal transmission. With this method, user must remove the sensor to refill the tire with air and then reinstall the sensor back on the valve stem. In addition to the inconvenience, frequent sensor removal and reinstallation would damage the air seal and cause air leak, thereby creating safety hazard for the user. Also

[00010] Therefore, there is a need to develop a Tire Pressure Monitoring System (TPMS) or an adaptor for monitoring tire pressure wirelessly and that can be easily attached to an earthmoving or construction vehicle wheel. Further, there is a need to develop a TPMS that should have simple structure, relatively inexpensive and overcoming the drawbacks explained above for the prior arts.
OBJECTS OF THE INVENTION
[00011] Some of the objects of the present disclosure are described herein below:
[00012] A main object of the present invention is to provide an external tire pressure
monitoring system which can be mounted on a wheel internally in such a way that to
place a sensor module outside a tire cavity for monitoring tire pressure of an
earthmoving or off-highway vehicle wheels.
[00013] Another object of the present invention is to provide an external tire pressure
monitoring system that can be mounted securely and has an anti-theft protection to the
sensor.
[00014] Still another object of the present invention is to provide an external tire
pressure monitoring system that utilizes a reliable RF signal transmission from the
sensor without a need for an external antenna as the sensors are placed outside the tire
cavity.
[00015] Yet another object of the present invention is to provide an external tire
pressure monitoring system that has a hassle free assembly.
[00016] Another object of the present invention is to provide an external tire pressure
monitoring system that allows a user to remove the tire easily over the rim without any
damage to the sensor.
[00017] Another object of the present invention is to provide an external tire pressure
monitoring system that facilitates easy tire rotation without the need for location
sensing of tires.

[00018] Another object of the present invention is to provide an external tire pressure monitoring system that facilitates easy removal and replacement of the battery without the need for removal of tires.
[00019] Another object of the invention is to provide the TPMS adaptor with air flow through feature. The need for separate holes on the rim one for holding the TPMS adaptor and the other for a tire inflation valve are eliminated. The TPMS adaptor is provided with a hole on one of its sides to receive the large bore valve core housing. [00020] Another object of the invention is to provide a system that is available to be included both at the factory level as well as an aftermarket solution. [00021] According to the space and other practical constraints, various modifications may occur to those skilled in the art without departing from the true scope and spirit of this invention.
[00022] The other objects and advantages of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings, which are incorporated for illustration of preferred embodiments of the present invention and are not intended to limit the scope thereof.
SUMMARY OF THE INVENTION
[00023] In view of the foregoing, an embodiment herein provides a tire pressure monitoring system (TPMS) for monitoring pressure level of an off-highway vehicle wheel. The TPMS comprises of a tire pressure monitoring system (TPMS) adaptor, a rim, a tire, an air inflation valve and a tire cavity. The TPMS adaptor may include but is not limited to at least one main housing, at least one stem and so on. The rim is provided with a suitable counter bore or a hole for receiving the TPMS adaptor. The size of the hole is same as that for receiving a standard valve spud. This is to ensure that the TPMS can be retro-fit at the field when the Customer decides so. Further, the counter bore with a larger diameter is made to face air side of the rim. The TPMS adaptor is mounted on to the rim internally by keeping the sensor housing external to the tire cavity thereby to ensure the signal transmission is not blocked by the tire. The

TPMS adaptor is integrated with the air inflation valve for refilling air through the sensor housing.
[00024] According to the embodiment, the TPMS adaptor may further include but is not limited to at least two radial seal O-ring, at least one face seal O ring, at least one spud, at least one lock nut, at least one swivel nut, at least one rubber grommet, at least one set screw and so on. The spud is provided with threads on its external and internal surfaces. The external thread is machined to match the lock nut and internal thread is machined to match the threads on the stem.
[00025] The main housing is provided with a through hole which is used to place the housing on the middle step of the stem. The main housing is secured to the stem with plurality of set screws which are passed through the holes provided on the side opposite to the sensor electronics module. The main housing is provided with a cylindrical hole for receiving sensor electronics components on one end and a suitable provision to receive the valve core housing of standard large bore valve stem on other end. [00026] According to the embodiment, the stem is a stepped cylindrical member. Further, external threads are provided on a smallest diameter step of the stepped cylindrical member of the stem. A blind-hole starting from the smaller end of the stem and running up to three fourths of its length called main gallery is provided on the stem. The main gallery can establish connectivity between the tire air cavity and the main housing when assembled to the rim. Further, the middle portion of the stem is provided with two suitable grooves for accepting two radial static seals. The two O-rings are disposed on the grooves to provide air tight seal between the main housing and the stem. A cross hole is provided in the stem between the two O-ring grooves; and wherein the cross hole establishes connectivity to the tire air cavity region through the main gallery.
[00027] According to the embodiment, the rubber grommet is placed over the external step of the spud. The spud with the rubber grommet is placed over the counter bore seating surface of the hole on the rim circumference. The O ring static seal is disposed at the chamfer of the spud to provide air tight seal across the spud and stem interface.

[00028] According to the embodiment, the valve core housing with the O ring is pushed inside a lateral hole provided on the main housing. Further, the valve core housing is secured by the swivel nut provided. The valve core housing may include but not limited to different configurations such as angled stem, curved stem, hook shaped stem to match requirement of practical conditions.
[00029] The sensor assembly consisting of main housing along with the stem and the air inflation valve stem is entered in to the spud from a weather side and screwed in to the spud thereby to allow the thread portion of the stem to face the tire cavity region of the rim. The sensor assembly is secured with the spud by driving a set screw in the hole at mating thread interface between spud and the stem. This is to prevent unauthorised removal of the sensor assembly in the field as the disassembly of sensor is possible only after the tyre is removed which is done by authorised personnel. [00030] The main housing further includes a microcontroller with a plurality of sensors configured to communicate with a receiver unit using an encoded RF wireless transmission and to send alerts to the vehicle driver or operator when the vehicle tire pressure falls out of the desired range. The plurality of sensors includes a transmitter unit which integrates a pressure sensor, an acceleration sensor, a temperature sensor, an antenna, and a battery level sensor.
[00031] According to the embodiment, the plurality of sensors further configured to display an individual tire pressure, temperature and other values on the panel while the vehicle is in stationary or in moving condition. The pressure sensor, the acceleration sensor, the temperature sensor and the battery level sensor are housed in the microcontroller with a sensor chip positioned directly facing the main gallery for connecting with the air inside the tire cavity. The microcontroller with the plurality of sensors, a RF matching circuit, a power supply and a signal conditioning unit are mounted on a common printed circuit board on a side facing the main gallery; and wherein the antenna is positioned on the other side of the printed circuit board. Leads for connecting to the power supply is taken from the printed circuit board; and wherein the circuit board along with the mentioned components are potted inside the sensor

housing using a suitable epoxy based resin. The whole sensor module is sealingly covered by a lid provided with a static seal of suitable material and secured by a circlip. By this arrangement, the battery replacement can be effected by removing the lid without removal of the tyre.
[00032] According to the embodiment, the transmitter unit may include but not limited to a low-voltage power supply, built-in microcontroller and wireless FSK/ASK (Frequency Shift Keying/Amplitude Shift Keying) UHF (Ultra High Frequency) transmitter. The transmitter unit may further include an intelligent wakeup mechanism internally configured to reduce power consumption and an interval timer configured to control a timing of measurements and transmissions.
[00033] According to the embodiment, the TPMS adaptor is integrated with the air inflation valve for refilling air through the main housing.
[00034] According to another embodiment, the design of stem is modified to allow the tyre inflation valve to enter from the bottom of the stem. Another embodiment can be applied for critical space constraint. The electronics portion of the sensor module is oriented vertically and further in parallel to the main gallery of the stem. [00035] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[00036] The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.

[00037] Fig.1 illustrates a cross section view of a rim, according to an embodiment of
the present invention herein;
[00038] Fig. 2 illustrates detail-A of fig.1 showing the cross section view of TPMS
according to an embodiment of the present invention herein;
[00039] Fig. 3 illustrates a detailed cross section view of a TPMS, according to an
embodiment of the present invention herein;
[00040] Fig. 4 illustrates the stem of the TPMS, according to an embodiment of the
present invention herein;
[00041] Fig. 5 illustrates a detailed cross section view of a sensor of the TPMS,
according to another embodiment of the present invention herein;
[00042] Fig. 6 illustrates the stem of the TPMS, according to another embodiment of
the present invention herein;
[00043] Fig. 7 illustrates a detailed cross section view of the spud of the TPMS,
according to an embodiment of the present invention herein;
[00044] Fig. 8 illustrates a block diagram of wireless communication in the
microcontroller of the TPMS, according to an embodiment of the present invention
herein.
[00045] Fig.9 illustrates a cross section view of a rim, according to yet another
embodiment of the present invention herein;
[00046] Fig. 10a illustrates side view of the detail-A of fig.9 showing the cross section
view of TPMS according to the yet another embodiment of the present invention
herein;
[00047] Fig. 10b illustrates top view of the detail-A of fig.9 showing the cross section
view of TPMS according to the yet another embodiment of the present invention
herein;
[00048] Fig.11a illustrates side view of the main housing of yet another embodiment of
present invention herein;

[00049] Fig.11b illustrates top view of the main housing of yet another embodiment of
present invention herein;
[00050] Fig.12 illustrates the plug with rubber seal used in yet another embodiment of
present invention herein; and
[00051] Fig. 13 illustrates the shortened stem used in yet another embodiment of the
present invention herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00052] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[00053] As mentioned above, there is a need to develop a tire pressure monitoring system (TPMS) for monitoring pressure level of an off-highway vehicle wheel with a simple, relatively inexpensive device with an anti-theft protection. The embodiments herein achieve this by providing an external tire pressure monitoring system (TPMS) for monitoring pressure level of an off-highway vehicle wheel that can be mounted internally through the rim. Further, the TPMS has a simple structure and convenient to use in any off-highway vehicles without being damaged during tire installation. Referring now to the drawings, and more particularly to FIGS. 1 through 13, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[00054] Fig.1 illustrates a cross section view 100 of a rim, according to an embodiment of the present invention. The cross section view of the rim 103 that is installed with TPMS clearly illustrates the position of the TPMS onto the rim 103. The sensor portion of the TPMS is kept external to the rim 103 and away from the tire cavity 102 and in

the weather side 104 so that there is no blocking of RF signals by the steel belts embedded inside the tire. Further, another portion containing the spud of the TPMS is mounted on to the rim 103 internally. The spud portion of the TPMS is made to be in contact with air side 102 of the rim 103. The air side 102 of the rim 103 is covered by a tire 101 that is fitted over a tire cavity of the rim 103. Both the sensor and spud portions of the TPMS are secured by driving a set screw 301 from the air side 102. This arrangement prevents unauthorized removal of the TPMS at the field. The disassembly of TPMS is possible only after the removal of the tyre which is done only by the authorized personnel. To describe explicitly, the TPMS is an internally mounted external tire pressure monitoring device. The TPMS is integrated with a tyre air inflation valve 203 through which refilling of air to the tire 101 is performed. [00055] Fig. 2 illustrates detail-A of fig.1 showing the cross section view 200 of TPMS, according to an embodiment of the present invention the tire pressure monitoring system (TPMS) for monitoring pressure level of an off-highway vehicle wheel. The TPMS comprises of a tire pressure monitoring system (TPMS) adaptor 106, a rim 103, a tire 101, an air inflation valve 203, and a tire cavity 102. The TPMS adaptor 106 may include but is not limited to at least one main housing 209, at least one valve core housing 203, stem 208 and so on. The rim 103 is provided with a suitable counter bore or a hole 201 for receiving the TPMS adaptor 106. Further, the counter bore 201 with a larger diameter is made to face air side 102 of the rim 103. The size of the hole is same as that for receiving a standard valve spud. This is to ensure that the TPMS can be retro-fit at the field when the Customer decides so.
[00056] According to an embodiment, the TPMS adaptor 106 is mounted on to the rim 103 internally by keeping the sensor portion of the main housing 209 external to the tire cavity thereby to ensure the signal transmission is not blocked by the tire 101. The main housing 209 is provided with a through hole which is used to place the housing on the middle portion of the stem 208 over the step 403. The main housing 209 is secured to the stem 208 with plurality of set screws 212 which are passed through the holes provided on the side opposite to the sensor electronics module. The main housing 209

is provided with a cylindrical hole for receiving sensor electronics components on one end and a suitable provision to receive the tyre inflation valve core housing 203 of standard large bore valve stem on other end.
[00057] According to the embodiment, the TPMS adaptor 106 may further include components such as but not limited to at least one stem 208, at least two radial seal O-ring 210, at least one face seal O-ring 202, at least one spud 205, at least one lock nut
207, at least one swivel nut 204, at least one rubber grommet 206, at least one set screw
301 and so on. The components are connected in such a way that to protect the TPMS
by not allowing any unauthorized person to remove. The spud 205 is provided with
threads on its external and internal surfaces. In that, the external thread is machined to
match the lock nut 207 and internal thread is machined to match the threads on the stem
208. The main housing 209 is placed in the middle step of the stem 208. The main
housing 209 is provided with suitable provision to receive the valve core housing 203
of standard large bore.
[00058] Fig. 3 illustrates a detailed cross section view 300 of a TPMS, according to the embodiment of the present invention. According to the embodiment, the stem 208, is a stepped cylindrical member. Further, external threads are provided on a smallest diameter step of the stepped cylindrical member of the stem 208. A blind-hole starting from the smaller end of the stem 208 and running up to three fourths of its length called main gallery 304 is provided on the stem 208. The main gallery 304 can establish connectivity between the tire air cavity 102 and the main housing 209 when assembled to the rim 103. Further, referring to the figure 4, the middle portion of the stem 208 is provided with two suitable grooves 401 for accepting two radial static seals. The two O-rings 210 are disposed on the grooves 401 to provide air tight seal between the stem 208 and the main housing 209. A cross hole 303 is provided in the stem 208 between the two O-ring grooves 401. The cross hole 303 can establish connectivity to the tire air cavity region through the main gallery 304.
[00059] According to the embodiment, the valve core housing 203 with the O ring is pushed inside a lateral hole provided on the main housing 209. Further, the valve core

housing 203 is secured by the swivel nut 204 provided. The valve core housing 203 may include but not limited to different configurations such as angled stem, curved stem, hook shaped stem to match requirement of practical conditions. [00060] According to the embodiment, the plurality of sensors further configured to display an individual tire pressure, temperature and other values on the panel while the vehicle is in stationary or in moving condition. The pressure sensor, the acceleration sensor, the temperature sensor and the battery level sensor are housed in the microcontroller 302 with a sensor chip positioned directly facing the cross hole 303 of the main gallery 304 for connecting with the air inside the tire cavity. The microcontroller 302 with the plurality of sensors or sensor module, a RF matching circuit 305, a power supply and a signal conditioning unit 306 are mounted on a common printed circuit board 307 on a side facing the main gallery 304. The antenna 308 is positioned on the other side of the printed circuit board 307. Leads for connecting to the power supply battery 310 is taken from the printed circuit board 307; and wherein the circuit board along with the mentioned components except the battery 310 are potted inside the main housing 209 using a suitable epoxy based resin 309. The whole sensor module is sealingly covered by a lid 311 provided with a static seal 313 of suitable material and secured by a circlip 312. By this arrangement, the battery replacement can be effected by removing the lid 311 without removal of the tyre 101. [00061] According to the embodiment, the assembly of set screw 301 prevents the theft or unauthorised removal of sensor from the vehicle in the field. The sensor assembly is mounted such a manner the sensor portion is outside the tire 101 boundary. Unlike other sensors which are mounted inside the tire cavity, there is no blocking of RF signals by the steel belts embedded inside the tire 101. Hence clean signal from the sensor is obtained. The sensor is mounted on the rim 103 and is independent of the tire 101. Unlike the sensors that are pasted as a patch to the tire 101, the present invention facilitates easy tire 101 rotation from one position to the other on the vehicle in the field. The sensor assembly does not project inside the tire air cavity. The assembly and

disassembly of tires 101 on the rim 103 is easy and does not require any special skill or tool. Also the sensors don’t get damage during the tire 101 assembly and removal. [00062] Fig.4 illustrates the stem of the TPMS 400, according to an embodiment. The Fig. 3 shows the valve core housing 203 for a straight stem. The stem 208 along with the main housing 209 and the air inflation valve stem is entered in to the spud 205 from a weather side 104 and screwed in to the spud 205 thereby to allow the thread portion of the stem 208 to face the tire cavity region of the rim 103. The stem 208 is threaded completely into the spud 205 in such a way that the both the mating surface 402 of stem 208 and mating surface 701 of spud 205 to touch each other. The whole assembly is secured by the set screw 301 which is driven into the threaded hole provided at the mating surface of internal and external threads of the joining components. [00063] Fig. 5 illustrates a detailed cross section view 500 of a sensor of the TPMS, according to another embodiment of the present invention. According to the embodiment, the tyre inflation valve 501 with angled stem is illustrated. The tyre inflation valve 501 enters the stem 504 from the bottom.
[00064] Fig. 6 illustrates the stem 600 of the TPMS, according to another embodiment of the present invention. The stem 504 is modified to have a threaded hole 601 at the bottom accordingly as shown in fig. 6. The main housing 502 is mounted on the middle portion of the stem and secured by plurality of set screws 503. The other details are substantially same as explained earlier.
[00065] Fig. 7 illustrates a detailed cross section view of the spud 700 of the TPMS, according to an embodiment of the present invention.
[00066] Fig. 8 illustrates a block diagram 800 of wireless communication in the microcontroller of the TPMS, according to an embodiment of the present invention. The transmitter unit configured to transmit measured values from the plurality of sensors to a receiver unit for sending alert signals to the driver or operator. The transmitter unit integrates a microcontroller 804, a pressure sensor 803, an acceleration sensor 805, a temperature sensor 806, an antenna 810, and a battery level sensor or battery voltage monitor 802. The transmitter unit may include but not limited to a

highly-integrated monolithic with low-voltage power supply or battery 801, built-in microcontroller 804 and wireless FSK/ASK (Frequency Shift Keying/Amplitude Shift Keying) UHF (Ultra High Frequency) transmitter or RF transmitter 808. The transmitter unit may further include integrated pressure sensor 803 produced by Micro Electro Mechanical System (MEMS) technology, an acceleration sensor 805 and digital signal processing ASIC (Application Specific Integrated Circuit) chip. The ASIC chip includes temperature sensor 806, internal clock, an analog to digital converter (ADC) 809, sampling/holding (S/H), SPI (Serial Peripheral Interface), sensor data calibration, data management, ID code, battery voltage monitor circuit 802 and other functions. The battery voltage monitors circuit 802 which provides a signal proportional to the supply voltage. The voltage is read by the ADC 809 referenced to a fixed (band gap) voltage. Function of acceleration sensor 805 is to sense if the vehicle is in motion or at rest. [00067] According to the embodiment, a pressure/temperature importing hole left on one side of IC facing the main gallery 304 in the housing can directly import pressure into the stress film of pressure sensor 803 and ambient temperature into the temperature sensor 806. The sensor has good long-term properties and protected from the harsh environment conditions. Pressure measurement is performed by a dedicated ROM library function. The module operates in temperature range from -40°C to +125°C and pressure range from 100kpa to 1800kpa. Supply voltage range from 1.9 V up to 3.6 V. The pressure sensor 803 provided with thermal shutdown mode for device protection at high temperatures. Measurements of pressure, acceleration, temperature, and battery voltage are performed under software control, and the data can be formatted and prepared for RF (Radio Frequency) transmission by the microcontroller 804. In transmitter side filter capacitances are configured in order to suppress noise and improve reliability since RF chip is very sensitive to electromagnetic noise of vehicle. The high working frequency of system is 433 MHz. Therefore, 18.08 MHz passive crystal and 8 pF load capacitance were selected.
[00068] According to the embodiment, the transmitter unit 816 may further include an intelligent wakeup mechanisms (807 & 813) internally configured to reduce power

consumption and an interval timer configured to control a timing of measurements and transmissions. The circuitry (not shown) can be programmed to wake up at regular intervals or it can be woken up by the integrated LF transmitter 813. Additionally, wakeup is possible by an external wakeup source circuitry (not shown) connected to a general purpose Input/output (GPIO) pins. Fine tuning of the centre frequency can be done either using the on-chip capacitors bank or adding external capacitors. A ROM library function can start up the crystal and can select it as clock source for a baud rate generator. Data bytes can be shifted to Special Function registers which automatically can enable the RF power amplifier (PA) pin and can transmit the desired data according to the configuration. After the transmissions are finished the PA pin is disabled automatically. The highly efficient power amplifier is automatically turned on by the Manchester/Bi Phase encoder as soon as data is written to a register. After the last bit is transmitted and the shift register is empty the PA is turned off again. [00069] According to the embodiment, the receiver unit 817 is highly integrated receiver chip for 433MHz frequency. It is a family of universal, highly sensitive, low power, ASK/FSK RF multi-channel receivers for Manchester-coded data signals. It is able to run in several autonomous self-polling and wakeup modes. The chips include fully integrated digital base band data processing and produce clean data output via SPI, thus significantly reducing the load on the host processor and standby power consumption. The receiver unit can communicate to the sensor through 433MHz antenna and can receive and scan the signals from the sensor unit for useful data. The received data can be scanned for certain message contents (IDs) and is stored as data buffer, accessible via the SPI host interface. The converted data can be sent to display unit 815 to display the tire pressure, temperature and other parameters namely acceleration, battery level as needed.
[00070] Fig.9 illustrates a cross section view 900 of a rim, according to the yet another embodiment of the present invention. The mounting of the TPMS is similar to first embodiment of the present invention. In this embodiment the electronics portion of the sensor module is oriented vertically and in parallel to the main gallery of the stem. The

concept and other details are identical to the first embodiment. The configuration of TPMS 906 is explained in detail in fig.10.
[00071] Fig.10a illustrates the side view of the detail A of fig-9 showing the cross section view 1000a of TPMS according to the yet another embodiment of the present invention. Further, Fig.10b illustrates the top view of the detail A of fig-9 showing the cross section view 1000a of TPMS according to the yet another embodiment of the present invention. In this embodiment the sensor module is oriented vertically and in parallel to the main gallery of the stem 1008 in order to contain the overall height 1001 of the TPMS 906. The design and function of spud 205, grommet 206, lock nut 207, set screw 301 are same as an embodiment. The height of stem 1008 is shortened as shown in fig.13. The design of main housing 1009 is modified to accommodate the vertical orientation of the sensor module. The features of main housing are explained in fig. 11. [00072] Fig.11a illustrates the side view of the main housing 1100a of yet another embodiment of present invention. Fig.11b illustrates the top view 1100b of the main housing 1100b of yet another embodiment of present invention. The main housing as shown in fig. 11 is largely a rectangular block. A near octagonal milled box 1101 is projecting from one of the wide face 1102. The sensor module compartment 1103 is accommodated in the box 1101. At the inner end of the sensor module compartment a hole 1104 is drilled through which the tyre pressure is imported by the sensor 302. A cross-hole 1002 is drilled from the side opposite to the hole for tyre inflation valve core 203. The cross-hole is extended till it joins and opens up the other cross-hole 1003 drilled from valve core 203 end. The vent 1105 created by the hole 1002 is provided with suitable thread hole 1106 so that it is sealed by using a plug 1200 shown in Fig.12. [00073] Fig.12 illustrates the plug with rubber seal 1200 used in yet another embodiment of present invention. The plug 1200 shown in fig.12 is provided with a rubber seal 1201 which will seal against the taper 1107. The main housing 1009 is secured to the stem 1008 by passing a set screw 1005 into the threaded hole at the interface of stem head 1004 and the counter bore 1108. But for the orientation the

design, configuration and function of sensor module is identical to an embodiment of the present invention.
[00074] Fig. 13 illustrates the shortened stem 1300 used in yet another embodiment of the present invention. The height of stem 1008 is shortened in yet another embodiment of the present invention.
[00075] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

We Claim:
1. An external tire pressure monitoring system (TPMS) for monitoring pressure
level of an off-highway vehicle wheel comprises of,
a tire pressure monitoring system (TPMS) adaptor, a rim 103, a tire 101, an air
inflation valve and a tire cavity;
characterized in that
the TPMS adaptor 106 includes at least one main housing 209 and at least one
stem 208 and valve core 203;
wherein the rim 103 is provided with a suitable counter bore 201 or a hole for
receiving the TPMS adaptor 106; wherein the size of the hole is same as that for
receiving a standard valve spud thereby to ensure that the TPMS retro-fit at the
field according to a customer requirement;
wherein the counter bore 201 with a larger diameter is made to face air side 102
of the rim 103;
wherein the TPMS adaptor 106 is mounted on to the rim 103 internally by
keeping the main housing 209 external to the tire cavity thereby to ensure the
signal transmission is not blocked by the tire 101; and
wherein the TPMS adaptor 106 is integrated with the air inflation valve 203 for
refilling air through the main housing 209.
2. The external tire pressure monitoring system as claimed in claim 1, wherein the
TPMS adaptor 106 further includes at least one stem 208, at least two radial seal
O-ring 210, at least one face seal O-ring 202, at least one spud 205, at least one
lock nut 207, at least one swivel nut 204, at least one rubber grommet 206, and
at least one set screw 301.

3. The external tire pressure monitoring system as claimed in claim 2, wherein the spud 205 is provided with threads on its external and internal surfaces; and wherein the external thread is machined to match the lock nut 207 and internal thread is machined to match the threads on the main housing 209.
4. The external tire pressure monitoring system as claimed in claim 1, wherein the main housing 209 is placed in the middle step of stem 208; wherein the main housing 209 is provided with suitable provision to receive the valve core housing 203 of standard large bore on one end and sensor module on the other end; and wherein the main housing 209 is secured with the stem 208 by using plurality of set screws 212.
5. The external tire pressure monitoring system as claimed in claim 1, wherein the stem 208 is a stepped cylindrical member; and wherein external threads are provided on a smallest diameter.
6. The external tire pressure monitoring system as claimed in claim 5, wherein a blind-hole starting from the smaller end of the stem 208 and running up to three fourths of its length called main gallery 304 is provided on the stem 208; and wherein the main gallery establishes connectivity between the tire air cavity and the main housing 209 when assembled to the rim 103.
7. The external tire pressure monitoring system as claimed in claim 1, wherein a middle portion of the stem 208 is provided with two suitable grooves 401 for accepting two radial and face or static seals; and wherein the two O-rings are disposed on the grooves 401 to provide air tight seal between the main housing 209 and the stem 208.
8. The external tire pressure monitoring system as claimed in claim 1, wherein a cross hole 303 is provided in the stem 208 between the two O-ring grooves 401;

and wherein the cross hole 303 establishes connectivity to the tire air cavity region through the main gallery 304.
9. The external tire pressure monitoring system as claimed in claim 1, wherein the valve core housing 203 with the O ring is pushed inside a lateral hole provided on the main housing 209 and secured by the swivel nut 204 provided; and wherein the valve core housing 203 includes different configurations such as angled stem, curved stem, hook shaped stem to match requirement of practical conditions.
10. The external tire pressure monitoring system as claimed in claim 1, wherein the main housing 209 along with the stem 208 and the air inflation valve stem 203 is entered in to the spud 205 from a weather side 104 and screwed in to the spud 205 thereby to allow the thread portion of the stem 208 to face the tire cavity region of the rim 103.
11. The external tire pressure monitoring system as claimed in claim 1, wherein the rubber grommet 206 is placed over the external step of the spud 205; and wherein the spud 205 with the rubber grommet 206 is placed over the counter bore seating surface 211 of the hole on the rim 103 circumference.
12. The external tire pressure monitoring system as claimed in claim 1, wherein the O ring static seal is disposed at the chamfer 602 of the spud 205 to provide air tight seal across the spud 205 and stem 208 interface.
13. The external tire pressure monitoring system as claimed in claim 1, wherein the main housing 209 includes a microcontroller 704 with a plurality of sensors 302 configured to communicate with a receiver unit using an encoded RF wireless transmission and to send alerts to the vehicle driver or operator when the vehicle tire pressure falls out of the desired range.

14. The external tire pressure monitoring system as claimed in claim 13, wherein the plurality of sensors 302 includes a transmitter unit which integrates a pressure sensor 703, an acceleration sensor 705, a temperature sensor 706, an antenna 710, and a battery level sensor 702.
15. The external tire pressure monitoring system as claimed in claim 13, wherein the plurality of sensors 302 further configured to display an individual tire pressure, temperature and other values on the panel while the vehicle is in stationary or in moving condition.
16. The external tire pressure monitoring system as claimed in claim 15, wherein the pressure sensor 703, the acceleration sensor 705, the temperature sensor 706 and the battery level sensor 702 are housed in the microcontroller 704 with a sensor chip positioned directly opposite the main gallery 304 for connecting with the air inside the tire cavity.
17. The external tire pressure monitoring system as claimed in claim 13, wherein the microcontroller 704 with the plurality of sensors 302, a RF matching circuit 305, a power supply and a signal conditioning unit are mounted on a common printed circuit board 307 on a side facing the main gallery 304; and wherein the antenna 308 is positioned on the other side of the printed circuit board 307.
18. The external tire pressure monitoring system as claimed in claim 17, wherein leads for connecting to the power supply is taken from the printed circuit board 307; and wherein the circuit board along with the mentioned components are potted inside the main housing 209 using a suitable epoxy based resin 309.
19. The external tire pressure monitoring system as claimed in claim 14, wherein the transmitter unit 716 includes a low-voltage power supply, built-in microcontroller 704 and wireless FSK/ASK (Frequency Shift

Keying/Amplitude Shift Keying) UHF(Ultra High Frequency) transmitter 708;
and
wherein the transmitter unit 716 further includes an intelligent wakeup
mechanisms (707, 713) internally configured to reduce power consumption and
an interval timer configured to control a timing of measurements and
transmissions.
20. The external tire pressure monitoring system as claimed in claim 1, wherein the main housing 1009 is secured to the stem 1008 by passing a set screw 1005 into the threaded hole at the interface of stem head 1004 and the counter bore 1108.
21. The external tire pressure monitoring system as claimed in claim 1, wherein the sensor module oriented horizontally and in parallel to the central axis of the housing 209.
22. The external tire pressure monitoring system as claimed in claim 1, wherein the sensor module oriented vertically and in parallel to the main gallery of the stem 1008 in order to contain the overall height 1001 of the TPMS 906.
23. An external tire pressure monitoring system (TPMS) for monitoring pressure level of an off-highway vehicle wheels comprises of,
a tire pressure monitoring system (TPMS) adaptor, a rim 103, a tire 101, an air
inflation valve and a tire cavity;
characterized in that
the TPMS adaptor 906 includes at least one main housing 1009, a stem 1008
and at least one valve core housing 203;
wherein the rim 103 is provided with a suitable counter bore 201 or a hole for
receiving the TPMS adaptor 906; wherein the counter bore 201 with a larger
diameter is made to face air side 102 of the rim 103;

wherein the TPMS adaptor 906 is mounted on to the rim 103 internally by
keeping the main housing 1009 external to the tire cavity thereby to ensure the
signal transmission is not blocked by the tire 101;
wherein the TPMS adaptor 906 is integrated with the air inflation valve for
refilling air through the main housing 1009; and
wherein the main housing 1009 is incorporated in the stem 1008 so that the total
height 1001 of the TPMS adaptor 906 reduced for being accommodated in the
wheels where there is a space constraint.