Patent Description:
Large flow meters typically used in commercial, municipal and/or industrial applications are often expensive, because their large flow tube is typically made of cast steel. Longevity is therefore of particular importance for such large flow meters. It is nowadays expected by commercial, municipal and/or industrial customers that battery-powered flow meters have a life span of ten years or more.

It is known that utility providers of water, gas and/or thermal energy use automatic meter reading (AMR) systems or advanced meter infrastructure (AMI) systems to efficiently and reliably manage customer billing. Such systems may be referred to as "dedicated" meter reading systems. Dedicated meter reading systems are characterised in that consumption meters are installed in a plurality of locations and communicate consumption data to a head-end-system (HES) via a wireless communication with dedicated data collectors. A single data collector may collect the consumption data read by thousands of consumption meters. Several data collectors may be distributed over a city or region to cover all consumption meters located therein. Typically, the consumption meters communicate with the data collectors wirelessly using license-free frequency bands in a manner that saves as much battery-power of the consumption meters as possible, because there is usually no opportunity for recharging or exchanging the consumption meter battery. It is therefore a constant challenge to be able to guarantee a minimum battery lifetime, for example of at least <NUM>, <NUM> or preferably even <NUM> years with hourly or daily readings.

In order to reduce the cost of implementing and maintaining an infrastructure of dedicated data collectors, a public cellular communications network may be used instead of dedicated data collectors to collect the consumption data. For instance, the consumption meters may comprise a connection module, e.g. a modem, to connect to a Low Power Wide Area Network (LPWAN) provided by a public cellular communications network, e.g. a Narrowband Internet-of-Things (NB-IoT) or Long-term Evolution Machine Type Communication (LTE-M) network, e.g. LTE Cat NB1, LTE Cat NB2, LTE Cat M1 or LTE Cat M2. The frequency bands used in such a LPWAN are licensed, but have a large link budget. It is therefore desirable to provide a battery-powered consumption meter that is able to efficiently register consumption data regularly via a LPWAN, e.g. hourly or once per day, over a guaranteed minimum lifetime, e.g. <NUM> or <NUM> years.

In contrast to "dedicated" meter reading systems that "own" (includes lease) the data collector infrastructure, a public cellular communications network is part of a "generic" meter reading system, in which the wireless communication infrastructure between the consumption meter and the HES, i.e. the LPWAN, is owned, maintained and controlled by external parties, e.g. mobile network operators (MNO). Using a generic meter reading system, a utility provider (UP) of water, gas and/or thermal energy only owns (or leases), maintains and controls the consumption meters and the HES, but not the LPWAN between them.

Especially a cellular communication via a "generic" meter reading system using a Low Power Wide Area Network (LPWAN) provided by a public cellular communications network, e.g. NB-loT, is very challenging in terms of energy consumption. There is thus a certain risk that a large expensive flow meter of a commercial, municipal and/or industrial customer uses up too much energy for radio transmission and has to be exchanged prematurely. One solution to this problem may be to make the battery rechargeable via cables and terminals leading from an outside power supply to the interior battery. This may, however, lead to frequent charging sessions and a potential degradation of the battery over time.

Another solution may be to replace only the battery by a new one, but implies that a user or a service technician must penetrate into the inside of the flow meter. This, however, opens up other problems, i.e. on one hand an access to electronics that are regulated by authorities and on the other hand a risk of tampering. For example, <CIT> describes an all-electric utility gas meter with a separate battery chamber accommodating an exchangeable battery. Such a solution, however, would require too many fundamental modifications to the Applicant's typical cylindric flow meter design.

<CIT> describes a fluid meter, in particular for water, including a totaliser having electronic elements, this totaliser being covered by a cover and this cover itself being covered by a cap which ensures tamper-proof operation; the said cap is fixed to the said cover by means of at least one fixing element which is accessible from the exterior and of which the removal necessitates its destruction.

Usually, tampering of flow meters is prevented by not allowing access to or opening of the flow meter by using a non-exchangeable battery. However, the flow meter must apply self-restrictions of radio transmission to guarantee a minimum life span with a non-exchangeable and non-rechargeable battery.

It is thus an object of the present invention to provide a battery-powered flow meter that needs less self-restrictions of radio transmission and that is protected against tampering.

The battery of the flow meter according to the present disclosure is exchangeable and its electronics is protected against tampering.

According to a first aspect of the present disclosure, a flow meter is provided comprising:.

The battery is located in a battery cartridge, wherein the battery cartridge is arranged in an operating position within the electronics housing and removable from the electronics housing through the mounting side when the electronics housing is unmounted from the flow tube element. A first part of the electronics is protected against tampering by a first anti-tampering element being arranged between the first part of the electronics and the battery cartridge in the operating position. The flow meter is characterized in that a second part of the electronics is protected against tampering by a second anti-tampering element being mounted directly or indirectly to the flow tube element independently from the electronics housing, so that the second part of the electronics and the second anti-tampering element remain mounted to the flow tube element when the electronics housing is unmounted from the flow tube element.

The battery of the flow meter can be easily and safely replaced by unmounting the electronics housing from the flow tube element and taking the battery cartridge out of the unmounted electronics housing. It may be possible that the battery cartridge may stick on the second anti-tampering element and remain in electrical connection with the second part of the electronics when the electronics housing is unmounted from the flow tube element. The battery cartridge can then be pulled off easily for replacement. The battery cartridge may contain one or more batteries, which may be fixed to the cartridge or releasable therefrom. It is possible to replace one or more or all of the batteries only, or the battery cartridge as a unit together with the one or more batteries therein.

Optionally, the second anti-tampering element may be essentially cup-shaped and/or the second part of the electronics may reside at least partly within a cavity of the flow tube element. The second anti-tampering element may be nested within the electronics housing as long as the electronics housing is mounted to the flow tube element.

Optionally, the first anti-tampering element may be essentially disc-shaped and may separate a first cavity within the electronics housing from a second cavity within the electronics housing, wherein the first cavity is inaccessible and contains the first part of the electronics, and wherein the second cavity is accessible though the mounting side and contains the removable battery cartridge. The first anti-tampering element may comprise one or more openings through which an electrical connection between the battery and the first part of the electronics may lead.

Optionally, a third cavity may be defined in the electronics housing between the battery cartridge in the operating position and the mounting side of the electronics housing, wherein the second anti-tampering element and/or the second part of the electronics reside(s) at least partly within the third cavity.

Optionally, the first part of the electronics may be located on a first printed circuit board, PCB, and wherein second part of the electronics may be located on a second printed circuit board, PCB.

Optionally, the first PCB and/or the second PCB may be arranged parallel to each other and/or parallel to the mounting side of the electronics housing. So, the PCBs preferably extend in parallel planes, preferably in parallel to the mounting side of the electronics housing. This has the advantage that the battery cartridge is inserted into the electronics housing and removed from the electronics housing essentially perpendicular to the first PCB, so that an electrical connection can be achieved by one or more male connector(s) extending perpendicular to the first PCB. The male connector(s) may be contact knives or pins as part of the battery cartridge. The first PCB may comprise corresponding female connector(s) for receiving the male connector(s) of the battery cartridge. Alternatively, or in addition, the first PCB may comprise male connector(s) and the battery cartridge may comprise corresponding receiving female connector(s) for receiving the male connector(s) of the first PCB. The electrical connection between the first PCB and the battery cartridge may also provide for a frictional mechanical connection that is manually releasable when the battery cartridge is manually pulled out of the electronics housing.

Optionally, the flow tube element comprises a metallic main body defining a flow tube, pipe mounting flanges, sensor cavities accommodating the sensors and a mounting portion to which the electronics housing is releasably mounted. Preferably, the pipe mounting flanges are coaxially arranged to each other, so that the flow tube defines a main flow direction. The electronics housing is preferably mounted essentially perpendicular to the main flow direction, so that the mounting side of the electronics housing faces towards a central flow axis of the flow tube element extending along the main flow direction.

Optionally, the second anti-tampering element may be directly or indirectly fixed to the main body at the mounting portion of the main body. Preferably, the second anti-tampering element is cup-shaped and mounted to a glass or plastic base plate comprising through-going electrical contacts. The base plate may be fixed to the flow tube element by a ring mount. The second anti-tampering element may be fixed to the base plate by a screw comprising a screw head being at least partially sunk into the second anti-tampering element. The screw head may be covered by a security seal in form of a vulnerable sticker.

Optionally, the second part of the electronics may be located closer to the flow tube element than the first part of the electronics, wherein the battery cartridge in the operating position is located between the first part of the electronics and the second part of the electronics. The electronics housing may preferably have a cup-shape defining a longitudinal axis perpendicular to the mounting side and/or the main flow axis.

Optionally, the first anti-tampering element may be fixed within the electronics housing. Preferably, the first anti-tampering element is inserted into the electronics housing from a top side opposite to the mounting side, wherein the top side is closed by a closing lid after the first cavity is fully equipped with the first part of the electronics during manufacturing and assembling of the flow meter. The first anti-tampering element preferably rests on one or more support surface(s) defined by the electronics housing in the second cavity and facing away from the mounting side.

Optionally, the battery cartridge may define a desiccant cavity at least partly filled with a desiccant. This is particularly beneficial if the battery cartridge is exchanged as a whole unit, because the desiccant is then replaced automatically with each battery replacement.

Optionally, the battery cartridge may comprise an electrical connection protruding through an opening in the first anti-tampering element to connect to the first part of the electronics and protruding through an opening in the second anti-tampering element to connect to the second part of the electronics. So, the second part of the electronics may be powered via the first part of the electronics, or vice ver-sa.

Optionally, the electronics housing may define at least one inner positive fit element engaging with at least one corresponding outer positive fit element of the battery cartridge for guiding the battery cartridge into and out of the operating position in a well-defined manner. The form fit elements preferably extend along the longitudinal axis of the electronics housing, i.e., perpendicular to the mounting side. Preferably, an axial (upper) end of one or more of the inner positive fit element(s) may define a support surface for the first anti-tampering element to rest on.

Optionally, the second anti-tampering element defines at least one positive fit element engaging with at least one corresponding positive fit element of the battery cartridge for guiding the electronics housing in a well-defined manner when it is mounted to the flow tube element. The form fit elements preferably extend along the longitudinal axis of the electronics housing, i.e., perpendicular to the mounting side.

Optionally, the electronics housing may comprise a closing lid at a side opposite to the mounting side and forms a cup-shape only accessible through the mounting side when the electronics housing is unmounted from the flow tube element. This has the advantage that the electronics housing cannot be opened as long as it is mounted to the flow tube element.

Optionally, the electronics housing may comprise a mounting flange at the mounting side of the electronics housing.

Optionally, the first part of the electronics may be configured to display values and/or transmit wirelessly values to an automatic reading system, wherein the second part of the electronics is configured to receive and/or process the signals generated by the sensors.

Optionally, the flow meter may be an ultrasonic flow meter, wherein the sensors are ultrasonic transducers.

An embodiment of the present disclosure will now be described by way of an example with reference to the following figures of which:.

<FIG> and <FIG> show a flow meter <NUM> in form of a large ultrasonic flow meter for measuring high fluid flows and for automatically transmitting wirelessly consumption values. The flow meter <NUM> comprises a flow tube element <NUM> and electronics housing <NUM> being releasably mounted to the flow tube element <NUM>. The flow tube element <NUM> comprises sensors <NUM> in form of ultrasonic transducers being configured and arranged to generate signals for measuring a fluid flow through the flow tube element <NUM>.

In order to facilitate the spatial orientation, each figure shows a local right-handed Cartesian coordinate system. The shown local coordinate system refers to an operational position when all components are installed and mounted for operation as shown in <FIG>, <FIG> and <FIG>. It should be understood that the flow meter <NUM> can be installed in any spatial orientation. However, in order to facilitate the description by using spatial terms like "up", "down", "axial" and "lateral", the z-axis shall be directed vertically upward, the x-axis shall be directed horizontally along a main flow direction L through the flow tube element <NUM>, and the y-axis shall be directed horizontally perpendicular to the main flow direction L.

The flow tube element <NUM> defines the main flow direction L extending from a fluid inlet port <NUM> of the flow tube element <NUM> to a fluid outlet port <NUM> of the flow tube element <NUM>. The fluid inlet port <NUM> and the fluid outlet port <NUM> are coaxially aligned to each other and to the main flow direction L. Each of the fluid inlet port <NUM> and fluid outlet port <NUM> comprise a connector flange for connecting a fluid pipe (not shown) to the flow tube element <NUM>. The flow tube element <NUM> further defines a central flow section <NUM> located between the fluid inlet port <NUM> and the fluid outlet port <NUM>. The central flow section <NUM> has a smaller inner diameter than the fluid inlet port <NUM> and the fluid outlet port <NUM> (see <FIG>). Therefore, the cross-section through which the fluid flows through the flow tube element <NUM> is defined by the central flow section <NUM>, where the cross-section is the smallest along the flow tube element <NUM>.

The sensors <NUM> are arranged in dedicated sensor cavities defined at opposite lateral sides of the flow tube element <NUM>. In the shown embodiment, the flow tube element <NUM> comprises two pairs of ultrasonic transducers <NUM>, i. an upper pair and a lower pair. The ultrasonic transducers <NUM> of each pair face each other from opposite lateral sides of the flow tube element <NUM>, wherein the pair of ultrasonic transducers define a main ultrasonic traveling axis S directed diagonally in the xy-plane.

Thereby, ultrasonic signals exchanged between the pair of ultrasonic transducers <NUM> along main ultrasonic traveling axis S have a motion component along the main flow direction L, or opposite to it, depending on the flow direction of the ultrasonic signals along the S-axis. Thereby, it is possible to determine a flow velocity from the ultrasonic signals as readily known by skilled person. As the inner cross-section of the central flow section <NUM> is known, a fluid flow through the flow tube element <NUM> can be deduced from the flow velocity. The fluid flow may be recorded over a certain period of time in a continuous, regular and/or sporadic manner in order to determine a consumed quantity, i.e., a total volume flowing through the flow tube element <NUM> over a certain period of time. The reception, processing, storing and/or transmitting of data is performed by electronics residing in the electronics housing <NUM>.

The electronics housing <NUM> is mounted to a top side of the central flow section <NUM> of the flow tube element <NUM>. The electronics housing <NUM> therefore comprises a mounting side <NUM> at its bottom. In the shown embodiment, the electronics housing <NUM> has essentially a cylindrical shape with a vertical longitudinal axis (along the z-axis). The horizontal cross-sectional shape of the electronics housing <NUM> is thus essentially circular.

The electronics housing <NUM> cannot be opened without unmounting it from the flow tube element <NUM>. A top side of the electronics housing is closed by a closing lid <NUM>. A front face of the closing lid <NUM> is at least partially transparent to allow visual inspection of a display <NUM> located underneath. The electronics housing <NUM> further comprises an electric connection socket <NUM> at the axial top side of the electronics housing <NUM>. The electrical connection socket <NUM> allows for connecting an external power supply (not shown) to be optionally connected during maintenance and/or times of expected high electric energy consumption. The electric connection socket <NUM> may further provide the possibility to: extract data for further processing and/or transmission; and/or to set parameters; and/or to upload a program or a program update.

During normal operation of the flow meter <NUM>, the flow meter <NUM> is battery-powered and independent of an external power supply. The electrical connection socket <NUM> is not used during normal operation of the flow meter <NUM>.

As shown in <FIG>, the electronics housing <NUM> accommodates a battery <NUM> in form of two D-type battery cells. The electronics housing <NUM> further accommodates electronics located on two separate printed circuit boards (PCB) <NUM>, <NUM>. A first PCB <NUM> extends in a horizontal xy-plane in a top section <NUM> of the electronics housing <NUM>. The first PCB <NUM> contains a first part of the electronics in the electronics housing <NUM>. The display <NUM> is one component of the first part of the electronics on the first PCB <NUM>. Preferably, the first PCB <NUM> further comprises a signal transmitter and an antenna and/or antenna connectors for wirelessly transmitting consumption values to an automatic reading system (not shown). A second PCB <NUM> extends parallel to the first PCB <NUM> in a horizontal xy-plane in a bottom section <NUM> of the electronics housing <NUM>. The battery <NUM> is located in a battery cartridge <NUM> arranged in a central section <NUM> of the electronics housing <NUM> between the top section <NUM> and the bottom section <NUM>. Thus, the battery cartridge <NUM> is located within the electronics housing <NUM> between the first PCB <NUM> and the second PCB <NUM>. This is the operating position of the battery cartridge <NUM> as shown in <FIG> when the electronics housing <NUM> is mounted to the flow tube element <NUM>. As shown in <FIG> and described below, the battery cartridge <NUM> is removable from the electronics housing <NUM> through the bottom mounting side <NUM> of the electronics housing <NUM> when the electronics housing <NUM> is unmounted from the flow tube element <NUM>.

A first antitampering element <NUM> is located within the electronics housing <NUM> underneath the first PCB <NUM>. The PCB <NUM> on its lower side (facing the anti-tampering plate <NUM>) is free - at least in its middle portion - from electronics in order to make room for the fist anti-tampering element <NUM> and the batteries <NUM> (cf <FIG>). The first anti-tampering element <NUM> is essentially disc-shaped and extends essentially in a horizontal xy-plane between the battery cartridge <NUM> and the first PCB <NUM>. The first anti-tampering element <NUM> separates a first cavity <NUM> within the top section <NUM> of the electronics housing <NUM> from a second cavity <NUM> within the central section <NUM> of the electronics housing <NUM>. The first anti-tampering element <NUM> is made as a thin plate in order not to increase the height of the electronics housing <NUM> more than necessary (cf <FIG>). The first cavity <NUM> contains the first PCB <NUM> with the first part of the electronics. The first anti-tampering element <NUM> blocks access to the first cavity <NUM> from below. The second cavity <NUM> contains the removable battery cartridge <NUM> and is accessible through the bottom mounting side <NUM> of the electronics housing <NUM> when the electronics housing <NUM> is unmounted from the flow tube element <NUM>.

The second PCB <NUM> contains a second part of the electronics in the electronics housing <NUM>, wherein the second part of the electronics comprises electronic components for receiving and processing signals generated by the sensors <NUM>. The electronics on the second PCB <NUM> is protected against tampering by a second anti-tampering element <NUM> that is mounted to the flow tube element <NUM> independently from the electronics housing <NUM>. Thereby, the second PCB <NUM> and the second anti-tampering element <NUM> remain mounted to the flow tube element <NUM> when the electronics housing <NUM> is unmounted from the flow tube element <NUM>. The second anti-tampering element <NUM> is essentially cup-shaped and nested in a third cavity <NUM> in the bottom section <NUM> of the electronics housing <NUM>. The third cavity <NUM> of the electronics housing <NUM> is defined in the electronics housing <NUM> between the battery cartridge <NUM> and the mounting side <NUM> of the electronics housing <NUM>. The second anti-tampering element <NUM> and the second part of the electronics on the second PCB <NUM> reside at least partly within the third cavity <NUM> of the electronics housing <NUM>. The second anti-tampering element <NUM> substantially fills the third cavity <NUM> within the bottom section <NUM> of the electronics housing <NUM>.

<FIG> show how the second anti-tampering element <NUM> is securely mounted to the flow tube element <NUM>. The flow tube element <NUM> comprises a main body <NUM> made of steel defining an upper mounting portion <NUM>. The flow tube element <NUM> is further equipped with a mounting base <NUM> in form of a framed glass plate being fixed to the mounting portion <NUM> of the main body <NUM>. The mounting base <NUM> comprises vertically electrical contacts <NUM> for establishing an electrical connection between the sensors <NUM> and the bottom of the second PCB <NUM>. An anchor element <NUM> protrudes vertically from below through the mounting base <NUM> to receive a securing screw <NUM> at its top end. The anchor element <NUM> protrudes also through the second PCB <NUM> with its top end. The head of the securing screw <NUM> pushes the second anti-tampering element <NUM> downward onto the second PCB <NUM> and secures both the second anti-tampering element <NUM> and the second PCB <NUM> to the mounting base <NUM> by means of the anchor element <NUM>. The head of the securing screw <NUM> is sunk into the second anti-tampering element <NUM>, such that a security seal <NUM> in form of a vulnerable sticker can be placed on the second anti-tampering element <NUM> to indicate that the securing screw <NUM> is not tampered with. A broken security seal <NUM> would indicate that the securing screw <NUM> may have been unscrewed for taking off the second anti-tampering element <NUM> for accessing the electronics on the second PCB <NUM>. The securing screw <NUM> has a further function, namely creating electrical ground connection between PCB <NUM> and the metallic main body <NUM> of the flow tube element <NUM>. This electrical ground connection is relevant for EMC protection and for the ultrasonic flowmeter passing electrical approval tests.

<FIG> shows how the battery cartridge <NUM> is removed from the electronics housing <NUM>. Preferably, the completely equipped battery cartridge <NUM> is replaced as a whole unit. The electronics housing <NUM> is unmounted from the mounting base <NUM> of the flow tube element <NUM> and pulled vertically off the flow tube element <NUM>. Thereby, the third cavity <NUM> in the bottom section <NUM> of the electronics housing <NUM> becomes accessible through the bottom mounting side <NUM> of the electronics housing <NUM>. The second PCB <NUM> remains at the flow tube element <NUM> and is protected against tampering by the second anti-tampering element <NUM> being secured to the mounting base <NUM> of the flow tube element <NUM>. The battery cartridge <NUM> can now be pulled out of the mounting side <NUM> of the electronics housing <NUM> and replaced by another battery cartridge <NUM> equipped with a fresh battery <NUM>. The cartridge <NUM> is exchangeable by hand, i.e. after lifting the electronics housing <NUM> the cartridge <NUM> can be removed with bare hands. Depending on whether the frictional contact between the battery cartridge <NUM> and the second anti-tampering element <NUM> and/or the electrical connection with the second PCB <NUM> is smaller or larger than the frictional contact between the battery cartridge <NUM> and the electronics housing <NUM> and/or the electrical connection with the first PCB <NUM>, the battery cartridge <NUM> is pulled off the flow tube element <NUM> together with the electronics housing <NUM> or remains on the flow tube element <NUM> when the electronics housing <NUM> is pulled off. In the latter case, the battery cartridge <NUM> can be easily pulled off manually off the flow tube element <NUM> for replacement.

The electronics housing <NUM> defines in the shown embodiment three inner positive fit elements <NUM> in form of longitudinal ribs extending along the z-axis. The battery cartridge <NUM> comprises corresponding female outer positive fit elements <NUM> in form of longitudinal slots extending along the z-axis. Thereby, the rotational orientation of the battery cartridge <NUM> relative to the electronics housing <NUM> in the xy-plane is well defined in order to ensure a designated electrical and mechanical contact between the battery cartridge <NUM> and the first part of the electronics on the first PCB <NUM> (not visible in <FIG>) residing within the first cavity <NUM> of the electronics housing <NUM>. As can been seen in <FIG>, the first part of the electronics on the first PCB <NUM> is protected against tampering by the first anti-tampering element <NUM>. The battery cartridge <NUM> comprises contact blades <NUM> extending vertically upward at a top side of the battery cartridge <NUM> in order to cut into female receptors <NUM> arranged at the first PCB <NUM>. The first anti-tampering element <NUM> has openings <NUM> to allow the contact blades <NUM> to cut into the female receptors <NUM> of the first PCB <NUM>. The battery cartridge <NUM> further comprises a vertically throughgoing electrical connection <NUM> electrically connecting the first PCB <NUM> with the second PCB <NUM>. Both the first PCB <NUM> and the second PCB <NUM> comprise connection sockets for receiving pins of the electrical connection <NUM> of the battery cartridge <NUM> to be plugged in. Software codes in the electronics of the first PCB <NUM> and the second PCB <NUM> are activated to ensure that these PCBs <NUM> and <NUM> still is a matching pair after replacement of the catridge <NUM>.

Once a new battery cartridge <NUM> is inserted and plugged into the electronics housing <NUM>, the electronics housing <NUM> can be mounted to the flow tube element <NUM>. In order to guide the electronics housing <NUM> in a well-defined manner regarding the rotational orientation in the xy-plane relative to the flow tube element <NUM>, the second anti-tampering element <NUM> defines in the shown embodiment two positive fit elements <NUM> engaging with two corresponding female positive fit element <NUM> of the battery cartridge <NUM>. The positive fit elements <NUM> of the second anti-tampering element <NUM> are formed as vertically extending webs that are supposed to protrude into the vertically extending slot-shaped form fit elements <NUM> at lateral sides of the battery cartridge <NUM>.

As can be seen in <FIG>, the second anti-tampering element <NUM> further comprises hooks <NUM> snapping under the second PCB <NUM> in order to protect the second part of the electronics on the second PCB from a lateral tampering attack. <FIG> also shows clearly the through-going electrical connection <NUM> provided in the battery cartridge <NUM>, so that the second PCB <NUM> and the sensors <NUM> are powered by the battery <NUM> via the first PCB <NUM> and the electrical connection <NUM>. <FIG> shows the individual components of the electronics housing <NUM>, the battery cartridge <NUM> and the mounting base <NUM>. The mounting base <NUM> is shown in <FIG> separated into a glass plate and a mounting frame. There are eight electric contacts <NUM> in form of pins provided to go through the glass plate of the mounting base <NUM>, i.e. two pins <NUM>, one pin <NUM> for each of the ultrasonic transducers <NUM>. The second PCB <NUM> comprises corresponding contact points at its bottom side for being contacted by the pins <NUM>.

The electronics housing <NUM> is water-tightly sealed by O-rings <NUM> at the top side and the bottom mounting side <NUM>. The upper O-ring <NUM> is pressed by the closing lid <NUM> to an upper rim of the electronics housing <NUM>. The lower O-ring is pressed downward by the bottom mounting side <NUM> of the electronics housing <NUM> against the glass plate of the mounting base <NUM> when the electronics housing <NUM> is fastened by screws <NUM> to the mounting base <NUM>. Instead of these fixing screws <NUM> the electronics housing <NUM> could be threaded and fixed in a corresponding thread on the mounting base <NUM>.

<FIG> shows the electronics housing <NUM> alone without any component installed therein. As can be seen, an axial top end of each of the three inner positive fit elements <NUM> provides a support surface <NUM> facing upward away from the bottom mounting side <NUM>. The first anti-tampering element <NUM> rests on these support surfaces <NUM> as shown in <FIG>. During the assembling process, the first anti-tampering element <NUM> is thus inserted as the first component into the electronics housing <NUM> from the opened top side. The installation of the first PCB <NUM> and the closing of the top side by the closing lid <NUM> follows later in the assembling process.

<FIG> show the second anti-tampering element <NUM> in more detail. The perspective bottom view of <FIG> shows in particular how the second anti-tampering element <NUM> is secured by the securing screw <NUM> and the hooks <NUM>. <FIG> shows the second anti-tampering element <NUM> with the security seal <NUM> in form of a vulnerable sticker being sticked on to cover the head of the security screw <NUM>. <FIG> shows the second anti-tampering element <NUM> before the security seal <NUM> is sticked on, so that the head of the security screw <NUM> is visible.

<FIG>show the battery cartridge <NUM> without batteries <NUM>. As can be seen in <FIG> in particular, the battery cartridge <NUM> defines a a desiccant cavity <NUM> located lateral from the batteries <NUM>. The desiccant cavity <NUM> is at least partly filled with a desiccant during the assembling process. The desiccant may be packaged or dumped into the desiccant cavity <NUM> as a bulk. If it is not packaged, it is beneficial that the desiccant cavity <NUM> is a closed cavity for securely enclosing desiccant as a bulk. The desiccant cavity <NUM> of the battery cartridge <NUM> is very useful, because it is exchanged together with the batteries <NUM> as a whole unit, so that the desiccant is replaced automatically by each battery replacement. It is also useful for storage and shipping of the battery cartridges <NUM> as a spare part of the flow meter <NUM>.

Where, in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure. It will also be appreciated by the reader that integers or features of the disclosure that are described as optional, preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

The above embodiments are to be understood as illustrative examples of the disclosure. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. While at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art and may be changed without departing from the scope of the subject matter described herein, and this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

Claim 1:
A flow meter (<NUM>) comprising:
- a flow tube element (<NUM>) comprising sensors (<NUM>) configured and arranged to generate signals for measuring a fluid flow through the flow tube element (<NUM>); and
- an electronics housing (<NUM>) comprising a mounting side (<NUM>), wherein the mounting side (<NUM>) is releasably mounted directly or indirectly to the flow tube element (<NUM>), wherein the electronics housing (<NUM>) accommodates a battery (<NUM>) and electronics, wherein the electronics and/or the sensors (<NUM>) are powered by the battery (<NUM>),
the battery (<NUM>) being located in a battery cartridge (<NUM>), wherein the battery cartridge (<NUM>) is arranged in an operating position within the electronics housing (<NUM>) and removable from the electronics housing (<NUM>) through the mounting side (<NUM>) when the electronics housing (<NUM>) is unmounted from the flow tube element (<NUM>);
a first part of the electronics being protected against tampering by a first anti-tampering element (<NUM>) being arranged between the first part of the electronics and the battery cartridge (<NUM>) in the operating position; and characterized by
a second part of the electronics being protected against tampering by a second anti-tampering element (<NUM>) being mounted directly or indirectly to the flow tube element (<NUM>) independently from the electronics housing (<NUM>), so that the second part of the electronics and the second anti-tampering element (<NUM>) remain mounted to the flow tube element (<NUM>) when the electronics housing (<NUM>) is unmounted from the flow tube element (<NUM>).