Patent Description:
In general, a tire pressure monitoring system (TPMS) 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 an 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.

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.

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.

In the prior art <CIT>, 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.

In another prior art <CIT>, 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.

In another prior art <CIT>, 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.

In some other prior art <CIT>, 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.

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 this design does not ensure protection against the sensor theft in the field.

In the prior art <CIT>, the apparatus for monitoring inflation pressure of a pneumatic tire is mounted on the valve stem of the wheel rim. The apparatus provides a transponder including sensors mounted on the valve stem, wherein the transponder is positioned either internal or external to the wheel rim.

In the prior art <CIT>, the tire pressure warning device is integrated with the valve stem of the wheel.

<CIT> discloses a pressure sensor mounted on a two-port valve stem. However, there are no separate compartment for sensors and battery such that both the sensors and the batteries can be accessed independently.

Therefore, there is a need to develop a Tire Pressure Monitoring System or an adaptor for monitoring tire pressure wirelessly and thereby easily attachable to a standard hole of a rim of the earthmoving or construction vehicle wheel. Further, there is a need to develop a simple and relatively less expensive adapter for monitoring tire pressure level.

Some of the objects of the present invention are described herein below:
A main object of the present invention is to provide an adapter externally that are mountable on a standard hole of a rim 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 wheel.

Another object of the present invention is to provide an adapter that are securely mountable and has an anti-theft protection to the sensor module.

Still another object of the present invention is to provide an adapter that utilizes a reliable RF signal transmission from the sensor module without a need for an external antenna as the sensor module are placed outside the tire cavity.

Yet another object of the present invention is to provide an adapter that has a hassle free assembly.

Another object of the present invention is to provide an adapter that allows a user to remove the tire easily over the rim without any damage to the sensor.

Another object of the present invention is to provide an adapter that facilitates easy tire rotation without the need for location sensing of tires.

Another object of the present invention is to provide an adapter that facilitates easy removal and replacement of the battery without the need for removal of tires.

Another object of the invention is to provide an adaptor with a female threaded hole arrangement to receive a valve core housing and/ or tire inflation valve and thereby eliminating the need for separate holes on the rim for holding the TPM adaptor and the tire inflation valve.

Another object of the invention is to provide an adapter that is available to be included at the factory level as well as an aftermarket solution.

According to the space and other practical constraints, various modifications may occur to those skilled in the art without departing from the scope of this invention as defined in the appended claims.

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.

In view of the foregoing, an embodiment herein provides an adapter for monitoring tire pressure level of an off-highway vehicle wheel and/ or earthmoving vehicle wheel through wireless communication. The adapter comprises of a sensor housing, wherein said sensor housing includes a sensor module, an internal gallery and a battery. The sensor housing further includes a male portion with external threads for mounting the adapter in a standard hole of a rim to face tire cavity region of the rim and a female threaded hole arrangement to receive a valve core housing and/or a tire inflation valve. The internal gallery is provided to establish connectivity between the sensor module, the tire inflation valve and the tire cavity. The sensor housing further includes at least two compartments for embedding the sensor module and the battery separately.

According to an embodiment, the sensor module compartment includes a stepped hole, a grommet, a filter, a rectangular recess, a sealing element and sensor electronic parts. According to an embodiment, the sensor electronic parts includes a microcontroller with plurality of sensor and/ or sensor chip, an antenna, a radio frequency matching circuit, a signal conditioning unit, leads for connecting to said battery and a common printed circuit board. The sensor module compartment is connected to a cross hole provided in the internal gallery through the stepped hole provided at top of the sensor module compartment.

According to an embodiment, the filter and the grommet are attached and connected together to a counter bore of the stepped hole and thereby providing tight seal and protection for the sensor electronic parts from contaminants present in the inflated air.

According to an embodiment, the microcontroller with plurality of sensors or sensor chip, the radio frequency matching circuit and the signal conditioning unit are mounted on the common printed circuit board on a side facing the cross hole and the antenna positioned on other side of the printed circuit board and together mounted over a surface inside the sensor module compartment and potted using a suitable epoxy based resin.

According to an embodiment, the rectangular recess provided along boundary of the grommet and the microcontroller and thereby acts as a protective frame for the microcontroller.

According to an embodiment, at least two ribs rise vertically from bottom of the rectangular recess creating a gap along walls of the rectangular recess and allow positioning of the sealing element into the gap and thereby preventing the epoxy based resin entering the rectangular recess.

According to the invention, the battery compartment includes an internal thread for receiving a threaded lid and a groove provided beneath the internal thread to receive a static seal. According to an embodiment, the leads for connecting to the battery are taken from the printed circuit board and runs through an internal hole connecting the sensor module compartment and the battery compartment.

According to an embodiment, the valve core housing and/ or the tire inflation valve includes a swivel nut for establishing a tight seal between the valve core housing and/ or the tire inflation valve and the female threaded hole arrangement of the sensor housing. According to an embodiment, the adapter is connected to the standard hole of the rim through a spud. According to an embodiment, the spud includes internal threads to receive the external threads of the male portion of the sensor housing and external threads to match internal threads of a lock nut provided beneath the spud. The adapter enters into the spud and secured by driving a set screw at a mating thread interface between the spud and external threads of the sensor housing.

According to an embodiment, a seal is disposed at a chamfer of the spud to provide an air tight seal between the spud and the sensor housing interface. According to an embodiment, a rubber grommet is placed over an external step of the spud.

In the figures, the left-most digit (s) of a reference number identifies the figure in which the reference number first appears.

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. 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.

As mentioned above, there is a need to develop an adapter for monitoring tire pressure level of an off-highway vehicle wheel and/ or earthmoving vehicle wheel through wireless communication. The embodiments herein achieve this by providing a simple, relatively less expensive adapter with an anti-theft protection for monitoring tire pressure level of an off-highway vehicle wheel and/ or earthmoving vehicle wheel that are mounted to a standard hole of a rim. Further, the adapter is convenient to use in any off-highway vehicle wheel and/ or earth moving vehicle wheel without being damaged during tire installation.

<FIG> illustrates a cross section view <NUM> of a rim <NUM>, according to an embodiment of the present invention. The cross section view <NUM> of the rim <NUM> includes a tire <NUM>, a tire cavity <NUM>, an adapter104 and a standard hole <NUM>. The cross section view of the rim <NUM> that is installed with the adapter <NUM> clearly illustrates position of the adapter <NUM> onto the rim <NUM>. According to an embodiment, a sensor module of the adapter <NUM> is kept external to the rim <NUM> and away from the tire cavity <NUM>, so that there is no blocking of RF signals by steel belts embedded inside the tire <NUM>. To describe explicitly, the adapter is an internally mounted external tire pressure monitoring (TPM) device.

<FIG> illustrates a pictorial view <NUM>(A) of an adapter <NUM>, according to an embodiment of the present invention. An adapter <NUM> for monitoring tire <NUM> pressure level of an off-highway vehicle wheel or earthmoving vehicle wheel through wireless communication, wherein said adapter <NUM> comprises of a sensor housing <NUM>, wherein said sensor housing <NUM> includes a sensor module, an internal gallery and a battery. According to an embodiment, the sensor housing <NUM> further includes a male portion with external threads <NUM> for mounting said adapter <NUM> in a standard hole <NUM> of a rim <NUM> to face the tire cavity region <NUM> of the rim <NUM> and a female threaded hole arrangement <NUM> to receive a valve core housing and/or a tire inflation valve. According to an embodiment, the sensor housing <NUM> further includes at least two compartments for embedding the sensor module and the battery separately.

<FIG> illustrates a pictorial view <NUM>(B) of the adapter <NUM>, according to an embodiment of the present invention. According to an embodiment, the male portion <NUM> of the sensor housing <NUM> is provided with external threads <NUM> for mounting the adapter <NUM> in the standard hole <NUM> of the rim <NUM> to face the tire cavity region <NUM> of the rim <NUM>. According to an embodiment, the battery compartment <NUM> is covered with a threaded lid <NUM>.

<FIG> illustrates a cross sectional view <NUM>(A) of the adapter <NUM> showing connection to a standard hole <NUM> through a spud <NUM>, according to an embodiment of the present invention. The adapter <NUM> comprises of a sensor housing <NUM>, wherein said sensor housing <NUM> includes a sensor module, an internal gallery <NUM> and a battery. The sensor housing <NUM> further includes a male portion <NUM> with external threads <NUM> for mounting the adapter <NUM> in the standard hole <NUM> of the rim <NUM> to face the tire cavity region <NUM> of the rim <NUM> and the female threaded hole arrangement <NUM> to receive a valve core housing <NUM> and/or a tire inflation valve. According to an embodiment, the internal gallery <NUM> is provided to establish connectivity between the sensor module, the tire inflation valve and the tire cavity <NUM>.

According to an embodiment, the valve core housing <NUM> and/ or the tire inflation valve is pushed inside the female threaded hole arrangement <NUM> of the sensor housing <NUM>. The valve core housing <NUM> and/ or the tire inflation valve includes a swivel nut <NUM> for establishing a tight seal between the valve core housing <NUM> and/ or the tire inflation valve and the female threaded hole arrangement <NUM> of the sensor housing <NUM>. The valve core housing <NUM> may include but not limited to different configurations such as angled stem, curved stem, hook shaped stem to match requirement of practical conditions.

According to an embodiment, the adapter <NUM> is connected to the standard hole <NUM> of the rim <NUM> through a spud <NUM>. The standard hole <NUM> with a larger diameter is made to face the air cavity region102 of the rim <NUM>. The size of the standard hole <NUM> is same as that for receiving the spud <NUM>. This is to ensure that the adapter <NUM> can be retro-fit at the field when the customer decides so. According to an embodiment, the spud <NUM> includes internal threads to receive external threads <NUM> of the male portion <NUM> of the sensor housing <NUM> and external threads to match internal threads of a lock nut <NUM> provided beneath the spud <NUM>.

The adapter <NUM> is entered into the spud <NUM> by allowing the external threads <NUM> of the sensor housing <NUM> to face the tire cavity <NUM> region of the rim <NUM> and thereby secured by driving a set screw <NUM> at a mating thread interface between the spud <NUM> and external threads <NUM> of the sensor housing <NUM>. This is to prevent unauthorised removal of the sensor in the field as the disassembly of sensor housing <NUM> is possible only after the removal of the tire <NUM> which is done by authorised personnel. According to an embodiment, a seal <NUM> is disposed at a chamfer of the spud <NUM> to provide an air tight seal between the spud <NUM> and the sensor housing <NUM> interface and a rubber grommet <NUM> is placed over an external step of the spud <NUM>.

<FIG> illustrates a sectional view <NUM> (B) of the spud <NUM>, according to an embodiment of the present invention. The external threads <NUM> of the sensor housing <NUM> is entered completely into the spud <NUM> in such a way that the both the male portion <NUM> of the sensor housing <NUM> and a mating surface <NUM> of the spud <NUM> touches each other. The spud <NUM> includes internal threads <NUM> to receive the external threads <NUM> of the male portion <NUM> of the sensor housing <NUM> and external threads <NUM> to match internal threads of a lock nut <NUM> provided beneath the spud <NUM>. A seal <NUM> is disposed at the chamfer <NUM> of the spud <NUM> to provide an air tight seal between the spud <NUM> and the sensor housing <NUM> interface.

<FIG> illustrates an orthographic sectional view <NUM>(A) of the adapter <NUM> showing a sensor module compartment <NUM>, according to an embodiment of the present invention. The sensor housing <NUM> is a casing that includes separate compartments for embedding the sensor module and the battery. According to an embodiment, the sensor module compartment <NUM> includes a stepped hole <NUM>, a grommet <NUM>, a filter <NUM>, a rectangular recess <NUM>, a sealing element <NUM> and sensor electronic parts. According to an embodiment, the sensor electronic parts includes a microcontroller with plurality of sensor and/ or sensor chip <NUM>, an antenna <NUM>, a radio frequency matching circuit <NUM>, a signal conditioning unit <NUM>, leads <NUM> (a, b) for connecting to said battery <NUM> and a common printed circuit board (<NUM>). According to an embodiment, the sensor module compartment <NUM> is connected to a cross hole <NUM> provided in the internal gallery <NUM> through the stepped hole <NUM> provided at top of the sensor module compartment <NUM>.

According to an embodiment, the filter <NUM> and the grommet <NUM> are attached and connected together to a counter bore <NUM> of the stepped hole <NUM> and thereby providing tight seal and protection for the sensor electronic parts from contaminants present in the inflated air.

According to the embodiment, the plurality of sensors configured to display an individual tire pressure, temperature and other values on a panel. The pressure sensor, the acceleration sensor, the temperature sensor and the battery level sensor are housed in the microcontroller <NUM> with a sensor chip positioned directly facing the cross hole of the internal gallery <NUM> for connecting with the air inside of the tire cavity <NUM>. The microcontroller with plurality of sensors or sensor chip <NUM>, the radio frequency matching circuit <NUM> and the signal conditioning unit <NUM> are mounted on the common printed circuit board <NUM> on a side facing the said cross hole <NUM> and the antenna <NUM> positioned on other side of the printed circuit board <NUM> and together mounted over a surface <NUM> inside the sensor module compartment <NUM> and potted using a suitable epoxy based resin <NUM>.

<FIG> illustrates an orthographic pictorial view <NUM>(B) of the adapter <NUM>, according to an embodiment of the present invention herein. <FIG> illustrates a sectional view <NUM>(C) of the adapter <NUM> showing a section A-A of <FIG>, according to an embodiment of the present invention. The positioning of the rectangular recess <NUM> and at least two ribs <NUM> in the sensor module compartment <NUM> is clearly shown.

<FIG> illustrates a sectional view <NUM> (D) of the sensor module compartment <NUM> showing a section B-B of <FIG>, according to an embodiment of the present invention. According to an embodiment, the rectangular recess <NUM> provided along boundary of the grommet <NUM> and the microcontroller <NUM> and thereby acts as a protective frame for the microcontroller <NUM>. According to an embodiment, at least two ribs <NUM> rise vertically from bottom of the rectangular recess <NUM> creating a gap <NUM> along walls of the rectangular recess <NUM> and allows positioning of the sealing element <NUM> into the gap <NUM> and thereby preventing the epoxy based resin <NUM> entering the rectangular recess <NUM>.

<FIG> illustrates an orthographic sectional view <NUM>(E) of a sensor housing <NUM> showing a battery compartment <NUM> and connection between the battery compartment <NUM> and the sensor module compartment <NUM>, according to an embodiment of the present invention. According to an embodiment, said battery compartment <NUM> includes a battery <NUM>, an internal thread and a groove. According to an embodiment, the groove is provided beneath said internal thread to receive a static seal <NUM>.

<FIG> illustrates a sectional view <NUM> (F) of the battery compartment <NUM> showing a section C-C of <FIG>, according to an embodiment of the present invention. According to an embodiment, the leads <NUM> (a, b) for connecting to said battery <NUM> are taken from said printed circuit board <NUM> and run through an internal hole <NUM> connecting said sensor module compartment <NUM> and said battery compartment <NUM>.

<FIG> illustrates a sectional view <NUM>(G) of the battery compartment <NUM> showing a section D-D of <FIG>, according to an embodiment of the present invention. According to an embodiment, an internal thread <NUM> is provided for receiving a threaded lid <NUM>. A groove <NUM> is provided beneath said internal thread <NUM> to receive a static seal <NUM>. By this arrangement, the battery <NUM> replacement can be done by removing the threaded lid <NUM> without removal of the tyre <NUM>.

<FIG> illustrates a block diagram <NUM> of wireless communication in the microcontroller of the TPM adapter <NUM>, according to an embodiment of the present invention. According to an embodiment, the transmitter unit <NUM> configured to transmit measured values from the plurality of sensors to a receiver unit <NUM> for sending alert signals to a driver or operator. According to an embodiment, the transmitter unit <NUM> integrates a microcontroller <NUM>, a pressure sensor <NUM>, an acceleration sensor <NUM>, a digital signal processing ASIC (Application Specific Integrated Circuit) chip and an antenna <NUM>. The transmitter unit <NUM> further includes a highly-integrated monolithic with low-voltage power supply or battery <NUM> and a wireless FSK/ASK (Frequency Shift Keying/Amplitude Shift Keying) UHF (Ultra High Frequency) transmitter or RF transmitter <NUM>. According to an embodiment, the pressure sensor <NUM> is produced by Micro Electro Mechanical System (MEMS) technology. According to an embodiment, the ASIC chip includes a temperature sensor <NUM>, an internal clock, an analog to digital converter (ADC) <NUM>, sampling/holding (S/H), SPI (Serial Peripheral Interface), sensor data calibration, data management, ID code and battery voltage monitor circuit <NUM>. The battery voltage monitors circuit <NUM> provides a signal proportional to the supply voltage. The voltage is read by the ADC <NUM> referenced to a fixed (band gap) voltage. Function of acceleration sensor <NUM> is to sense if the vehicle is in motion or at rest.

According to the embodiment, a pressure/temperature importing hole left on one side of IC facing the internal gallery <NUM> in the sensor housing <NUM> directly imports pressure into a stress film of pressure sensor <NUM> and ambient temperature into the temperature sensor <NUM>. The sensor module has good long-term properties and protected from the harsh environment conditions. The pressure measurement is performed by a dedicated ROM library function. According to an embodiment, the module operates in a temperature range from -<NUM> to +<NUM>, a pressure range from 100kpa to 1800kpa and a supply voltage range from <NUM> V up to <NUM> V. According to an embodiment, the pressure sensor <NUM> is 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 <NUM>. In transmitter unit <NUM> filter capacitances are configured in order to suppress noise and improve reliability since RF chip is very sensitive to electromagnetic noise of vehicle. According to an embodiment, a high working frequency of system is <NUM>, load capacitance is <NUM> pF and thereby a <NUM> passive crystal is selected.

According to the embodiment, the transmitter unit <NUM> may further include an intelligent wakeup mechanism (<NUM> & <NUM>) internally configured to reduce power consumption and an interval timer configured to control a timing of measurements and transmissions. The circuitry (not shown) is programmed to wake up at regular intervals or it can be woken up by the integrated LF transmitter <NUM>. 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 is done either using the on-chip capacitors bank or adding external capacitors. A ROM library function is able to 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.

According to the embodiment, the receiver unit <NUM> is highly integrated receiver chip for <NUM> 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 communicates to the sensor through <NUM> antenna and receives 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 <NUM> to display the tire pressure, temperature and other parameters namely acceleration, battery level as needed.

The main advantage of the present invention is that the adapter is mounted on a standard hole of a rim in such a way by placing a sensor module outside a tire cavity for monitoring tire pressure of an earthmoving or off-highway vehicle wheel.

Another advantage of the present invention is that the adapter provides an anti-theft protection to the sensor module.

Further advantage of the present invention is that the adapter utilizes a reliable RF signal transmission from the sensor module without a need for an external antenna as the sensor module are placed outside the tire cavity.

Additional advantage of the present invention is that the adapter has a hassle free assembly.

Another advantage of the present invention is that the adapter allows a user to remove the tire easily over the rim without any damage to the sensor module.

Another advantage of the present invention is that the adapter facilitates easy tire rotation without the need for location sensing of tires.

Another advantage of the present invention is that the adapter facilitates easy removal and replacement of the battery without the need for removal of tires.

Claim 1:
An adapter (<NUM>) for monitoring tire (<NUM>) pressure level of an off-highway vehicle wheel and / or earthmoving vehicle wheel through wireless communication, wherein said adapter (<NUM>) comprising,
a sensor for measuring pressure of said vehicle wheel tire (<NUM>);
characterized in that
said adapter (<NUM>) further includes a sensor housing (<NUM>), a valve core housing (<NUM>) and/or a tire inflation valve, wherein said sensor housing (<NUM>) includes a sensor module, an internal gallery (<NUM>) and a battery (<NUM>);
wherein said sensor housing (<NUM>) further includes a male portion (<NUM>) with external threads (<NUM>) for mounting said adapter (<NUM>) in a standard hole (<NUM>) of a rim (<NUM>) to face tire cavity region (<NUM>) of said rim (<NUM>), and a female threaded hole arrangement (<NUM>) to receive said valve core housing (<NUM>) and/or said tire inflation valve;
wherein said sensor module of the adapter (<NUM>) is kept external to the rim (<NUM>) and away from the tire cavity (<NUM>);
wherein said internal gallery (<NUM>) is provided to establish connectivity between said sensor module, said tire inflation valve and said tire cavity (<NUM>);
wherein said sensor housing (<NUM>) further includes at least two compartments for embedding said sensor module and said battery separately, a sensor module compartment (<NUM>) embedding the sensor module and a battery compartment (<NUM>) embedding the battery; and wherein said battery compartment (<NUM>) includes said battery (<NUM>),
characterised in that said battery compartment (<NUM>) further includes an internal thread (<NUM>) for receiving a threaded lid (<NUM>) and a groove (<NUM>) provided beneath said internal thread (<NUM>) to receive a static seal (<NUM>).