WO2010053439A1

WO2010053439A1 - Remote monitoring of storage containers for pressurized beer

Info

Publication number: WO2010053439A1
Application number: PCT/SE2009/051257
Authority: WO
Inventors: Janis Platbardis
Original assignee: Tnt-Elektronik Ab
Priority date: 2008-11-07
Filing date: 2009-11-05
Publication date: 2010-05-14
Also published as: SE0850069A1; EP2352973A4; SE533115C2; EP2352973A1

Abstract

Method for remote monitoring of storage containers (1) for beer by means of a remote monitoring system, which has a sensor unit placed in each storage container, a receiving unit (19) arranged adjacent to the storage containers, and a data storage unit (23) arranged at a distance from the storage containers. The sensor unit has a distance meter, a processor, a radio transmitter and a pulse circuit. The method comprises the step of the pulse circuit initiating a measurement sequence by sending an initialisation signal to the processor, which measurement sequence has the steps of the distance meter measuring the distance to the liquid surface of the beer and a volume value for the quantity of beer being estimated. The method furthermore has the step that a reporting sequence is initiated, which has the steps that a data message is composed, comprising the volume value and a unique identification number for the sensor unit, the data message is sent to the radio transmitter, which sends out the data message as a radio signal internally in the storage container so that it reaches the receiving unit, which receives the radio signal and relays the volume value and identification number to the data storage unit, which keeps these in a database.

Description

Remote monitoring of storage containers for pressurized beer

The present invention concerns a method for remote monitoring of a plurality of storage containers for beer by means of a remote monitoring system.

The present invention also concerns a system for remote monitoring of a plurality of pressurized storage containers for beer placed in a cold room.

In particular, the invention concerns such a system for remote monitoring of the degree of filling of storage containers for large-volume customers of pressurized beer.

The handling of beer in question is so-called "bulk handling", where the larger buyers such as restaurants, banquet halls, festivals, amusement parks, etc., have such large sales that storage containers with volumes of 0.5 or 1 cubic meter are used.

The number of customers of this size buying beer in bulk throughout Sweden is around 500 for each of the three biggest breweries. Such a customer has at least two storage containers, so that sales can occur from one of them, and filling up at the proper time can occur in the other one. The larger customers can have up to 6 storage containers, each of 1 m³.

The logistics of bulk handling of beer is such that the content in a full container is the property of the brewery in its so-called outside storage. Once a seal is broken, or a code to a code lock is given out, the actual sale of the beer occurs and the beer becomes the property of the buyer, while the alcohol tax etc. is levied. The buyer himself, with or without the co-operation of the brewery, performs the switch from a hopefully empty storage container to a full one.

The entire logistical handling with switching between storage containers, which may sometimes not be entirely empty, and full ones, is occurring at present without any real control of the actual level of beer in the storage containers .

The contact with and control of the outside storage which the brewery has at present consists of the visit which the brewery's tank truck with driver makes during scheduled or on-call filling of one or more storage containers. To be sure, there are two small inspection windows of glass at one end of the container and it is possible to call the restaurant staff and ask them to make a visual inspection and report, but the situation is often in fact misjudged and the glass of the inspection window can become misted over on the inside. Sometimes the restaurant can report misleading information for its own purposes.

These situations lead to unwanted expenses for the breweries and inefficiency in the bulk handling of beer, which due to its large volume nature should be as cost-effective as possible.

It often happens that the restaurant staff, who do not always have the time or ability to inspect the status and function of the system, switch the taps to a new container before it is empty. As a result, the remaining beer, which can amount to 100-200 litres or in certain cases even half the container, has to be thrown out.

It often happens that the larger sales locations may unexpectedly run out of beer on a Friday or weekend evening. Then a tank truck from the brewery will have to be dispatched regardless of business hours and other circumstances, at great expense and inconvenience, for otherwise the restaurant's business could suffer as a result .

It also happens that some restaurateurs with credit problems manage to gain access to the brewer's outside storage located near them. They break open seals and/or code locks and in this way gain entry to the contents, sell them, and use the proceeds to pay for goods on delivery.

It has also happened that restaurateurs whose credit has been frozen have arbitrarily shifted between storage containers without permission from the brewery.

Thus, there is a need among beer suppliers for a simple system of continuously and automatically measuring the beer level in the storage containers making up the supplier's outside storage. It should also be easy to install this system at the storage containers which the breweries presently have in their outside storage lager.

Attempts have been made with level metering tubes, but the method has not been found to be practicable, since the storage containers today have a rational system with inner exchangeable and disposable plastic bag to avoid washing and hygiene problems. Abandoning this system to be able to meter the level with level metering tubes entails more drawbacks than benefits, since in this case the beer would be kept directly inside the storage container. For example, GB 2 273 560 describes a system for metering of beer level by means of a level tube.

Other attempts have been made by weighing the storage containers with load cells. However, the technique has been too costly and complicated, and furthermore it hinders a simple exchange system for storage containers, where the beer distributor changes the physical position of a storage container.

The purpose of the present invention is to solve the aforementioned problems and provide a method and a system allowing continuous and automatic metering of the beer level in the storage containers making up a brewery's outside storage, which system furthermore is easy to install at existing outside storages and enables an exchange system for the storage containers in the outside storage .

This purpose is achieved with a method according to claim 1 and a system which comprises: a sensor unit arranged in each storage container, a receiving unit placed in the cold room, and a data storage unit placed at a distance from the cold room, which sensor unit is attached to the inside of the storage container at a level above the maximum allowable liquid level of the storage container and comprises: a distance meter, a temperature pickup, - a processor, a battery, a radio transmitter and a pulse circuit, which pulse circuit is designed to initiate a measuring sequence at predetermined intervals by sending an initialisation signal to the processor, which processor is designed, upon receiving the initialisation signal, to measure the temperature of an air volume above said liquid level by means of the temperature pickup and measure the distance between the sensor unit and the liquid surface of the beer by means of the distance meter and estimate a volume value for the quantity of beer remaining in the storage container from the measured distance, which processor moreover is capable of producing a data message, which contains the temperature value measured by the temperature pickup, the aforesaid volume value, and a unique identification number for the sensor unit, and sending this data message to the radio transmitter, which radio transmitter is designed, upon receiving the data message, to send out the data message as a radio signal internally in the storage container so that it emanates from the storage container, which receiving unit is designed to receive the radio signal and relay the temperature value, the volume value, and the unique identification number of the sensor unit to the data storage unit, and which data storage unit is designed to store the temperature value, the volume value, and the unique identification number of the sensor unit in a database.

The invention is based on placing a sensor unit inside the pressure vessel making up the storage container. The sensor unit is secured to the roof of the storage container with an adhesive, such as polybutylene butyl, two-sided adhesive tape, Velcro strips or the like. The sensor unit is battery-operated and has a built-in radio transmitter and thus needs no connection or pass through in or out of the walls of the pressure vessel. The fact that no intervention is required is of great value, since the closed storage containers are classified as a pressure vessel. Thus, in the system of the invention, the storage containers lack waveguide wall entrances for the radio signals which are sent out by the radio transmitters .

Thanks to a pulse circuit, the sensor unit is for the most part in a passive state of rest, in which the sensor unit consumes only around one millionth of an ampere from the battery. Approximately once a minute, or up to once every ten minutes, the sensor unit is awakened by the pulse circuit and performs its work within a fraction of a second. Preferably, the sensor unit is designed to report a measured value of a parameter only if the value differs from the last measured value of the same parameter. A typical time it takes to measure the parameter value is 30 ms, and in the event that the conditions have changed the time taken for measuring and reporting is 300 ms . Hence, the battery has a lifetime of several years, up to ten years. In practice, this means a maintenance-free installation in the relatively closed space of the storage container.

The sensor has electronics that measures the distance to the beer surface when the beer is in place in its plastic bag. Since the vessel is pressurized, the plastic bag functions such that it is not inflated inside the storage container, but rather lies flat against the liquid surface of the beer. The distance is measured to this surface. Various techniques are conceivable to accomplish this. One such technique is ultrasound radar. The distance is measured by the sensor sending out a well defined, very short ultrasound pulse. The sensor then listens for the echo from the pulse sent out. The time until the echo returns determines the distance. Preferably, the temperature inside the storage container is also measured, in part to get a temperature value in proximity to the beer, in part to allow for correcting the speed of sound of the pulse sent out and its echo, which is temperature-dependent.

The sensor unit's processor converts the measured distance between the sensor unit and the beer surface into a volume measure for the beer in the storage container. The volume of the liquid remaining in the storage container, the temperature at the sensor unit and the sensor unit ' s own identity are placed in a data message, which is sent out like a radio message via a radio transmitter, which is arranged inside the sensor unit.

This radio message bounces between the walls inside the storage container and acts on the inspection lid, which is situated in one end of the storage container. The inspection lid, in turn, relays the radio waves, albeit somewhat attenuated, but nonetheless still capable of being detected, out into the surroundings of the storage container.

Alternatively, the radio signal inside the storage container can be capacitively coupled to a conductive body situated on the outside of the storage container, which body in turn rebroadcasts the radio signal outside the storage container.

In the cold room there is a radio receiver, which receives the message from the sensors at the storage containers in the cold room. Normally there are 2-6 storage containers in a cold room. Since each radio message contains the sensor's unique identity, one can distinguish the measured values from different storage containers .

Besides the measured values, each radio message also contains information on the sensor's own functions, battery voltage, etc., and the message number and a so-called "cyclic redundancy check" (CRC) , which is used to decide how correct or corrupt the radio message contents are.

The receiver sends the information in each radio message via a gateway and a client on the Internet to a server, where a database is maintained, containing current information about the storage containers and their sensors, such as the level of fill, the temperature and the sensor status.

This database is accessible via Internet from ordinary computers with web capability. Here the brewery, restaurateurs, etc. can gain access to real-time information on, e.g., the fill level and temperature inside the various storage containers. The invention also allows for saving a fill history in the server, which enables calculations to predict the time for the next fill-up of the storage container.

Thus, the invention provides the benefit that the brewery can obtain real-time information on the fill level in its outside storage. Moreover, the brewery's customers, i.e., the buyers of the beer in the outside storage, are afforded the possibility of seeing their stockpile in a very simple way, which helps the buyers plan their activity. Because the system of the invention provides ongoing monitoring of the beer level inside the storage containers in the outside storage, it is possible for the brewery to predict the date of upcoming delivery orders in its logistical system.

Moreover, there is the benefit of quality assurance of the beer, since its temperature is measured, and the throughput and turnover can be monitored. This also leads to better quality insofar as the information from the invention is utilised in the brewery's logistics.

Sometimes storage containers in the outside storage are replaced or moved to another location. This handling is not in any way disrupted by the system of the invention, but rather it is supported in that the system ensures that the sensor in each storage container has a unique identity. Thus, the system lets the brewery obtain ongoing information as to which storage containers are situated at which service locations.

The system of the invention helps lower the brewery's customer losses by decreasing theft of beer and providing better handover of payments. In this way, doubtful and difficult customers can be kept with minimum risk of credit losses, etc. This has positive importance for the ability of the brewery to keep or surpass market shares calculated by number of buyers.

The system of the invention also allows the brewery to increase the outside storage at its existing purchasers without increased risk, thus resulting in a reservation of market space. The invention therefore has great market-strategic significance to the brewery which utilises the system of the invention in its logistics.

Moreover, the system of the invention offers the brewery the further advantage, when a shutoff valve controlled by the system is incorporated in the storage tanks, of selling its product in a new way. By utilising the system, the brewery can sell any desired quantity of beer, instead of one or more whole storage containers, as at present.

The system of the invention means that the present hygienic and rational handling of beer can be further rationalised in a totally new way and to a substantial degree, without any modification.

There are large quantities of storage containers in standardised design with volumes of 0.5 m³ and 1 m³. The system according to the invention does not prevent the current handling of either beer or the storage containers, but instead improves and facilitates both. Moreover, an installation of the system of the invention in an outside storage does not in any way affect the storage containers in the stockpile, which storage containers are classified as pressure vessels and subject to rigorous requirements. The installation is simple, without modifying the storage containers in the outside storage, and therefore the pressure vessels making up the storage containers do not have to be pressure tested, reclassified, inspected or approved in any way. However, the sensor does have to be designed to withstand and be able to function without hindrance at the maximum occurring pressure in the storage container, which is typically 3.5 atm, i.e. around 3.5 bar (3.5-10⁵ N/m²) .

It sometimes happens that the refrigerating equipment of the cold room fails in some way, resulting in higher temperature in the cold room than the desired +4 degrees. Preferably, therefore, the system of the invention also includes equipment for measuring and reporting of the temperature of the cool room and sending an alarm when the temperature is not right. Wastage can be prevented in this way. If the temperature becomes too high, the beer becomes cloudy and spoiled. Furthermore, repair costs for the refrigeration system can be spared by discovering faulty temperature in good time, making it possible to order service during normal business hours and at the lowest possible price. To monitor the refrigeration system of the cold room, the system according to the present invention can be advantageously supplemented with a monitoring system according to EP 1 906 290.

The invention will now be described more closely with reference to the enclosed patent drawings.

Figure 1 shows a storage container which is provided with a first embodiment of a sensor unit in a system according to the invention. Figure 2 shows the sensor unit of Figure 1.

Figure 3 shows a system according to the invention in which the sensor unit of Figure 2 is part of the storage containers .

Figure 4 shows a second embodiment of a sensor unit in a system according to the invention.

Figure 5 shows an antenna in a third embodiment of a sensor unit in a system according to the invention.

Figure 1 shows a closable storage container 1 for keeping of pressurized beer. The closed storage container 1 thus forms a pressure vessel. The storage container 1 is part of an outside storage of a brewery and is situated as one of a plurality of storage containers Ia, Ib, Ic in a cold room 20 of a purchaser (see Figure 3) . The purchaser is consequently a customer of the brewery.

The storage container 1 comprises, in familiar fashion, a bag 2, in which the beer 3 is kept.

The storage container 1 comprises a sensor unit 4, which is mounted in the roof of the storage container 1 by means of a fastening device 5. The fastening device 5 is of a type that does not affect the function of the storage container 1 as a pressure vessel. Preferably, the fastening device 5 is a suitable adhesive, such as polybutylene butyl, two-sided adhesive tape, a Velcro strip or the like.

The sensor unit 4 comprises a battery 12, designed to drive the parts included in the sensor unit 4. The sensor unit 4 further comprises a distance meter 6 to measure the distance between the sensor unit 4 and the portion of the bag 2 resting against the liquid surface of the beer 3. The distance meter β is preferably of the type that sends out a well defined, very short ultrasound pulse 7, listens for the echo 8 from the pulse sent out, and computes the distance to the echo source by noting the time between the sending of the pulse and the receiving of the echo. Such a distance measurement is known in itself and will not be further described here.

However, the invention places special requirements on the design of the distance meter. The electronics which performs the actual distance measurement should preferably be totally passive between measurement events, but when activated it should very quickly perform its measurement, and this with a low current consumption. For example, the distance meter β is active only 30 ms during the measurement and in this time period it consumes only 5-50 mA. Furthermore, the distance meter 6 must withstand the pressure and humidity occurring in the storage container 1.

The sensor unit 4 also comprises a temperature pickup 9 for measuring the temperature in the air volume 10 above the bag 2. This temperature is of interest first because it mostly corresponds to the temperature of the beer 3, and secondly because it can be used to compensate the distance measurement from the distance meter 6 in the case when the distance meter uses the above-described ultrasound pulse technique, in which case the measured time difference between pulse and echo is temperature-dependent .

The sensor unit 4 moreover comprises a processor 11, which is connected to the distance meter 6 and the temperature pickup 9 in order to receive the distance value and temperature value from these. The processor 11 is programmed to convert the distance value received during each measurement event into a volume value for the quantity of beer remaining in the storage container 1. If the distance meter 6 is of a type based on the above-described ultrasound pulse technique, it is further preferred that the processor 11 be programmed to temperature-compensate the distance value by means of the received temperature value before the volume value is computed. If the ultrasound pulse technique is used for the distance measurement, it is further preferred that the processor 11 be designed to drive the ultrasound-emitting unit of the distance meter 6 and to receive and analyse the signal from the echo receiving microphone of the distance meter 6, which minimises the current consumption of the distance meter 6 and simplifies its construction.

The processor 11 is moreover programmed to compare the volume value and temperature value of the present measurement event with the volume value and temperature value of the previous measurement event. If the present volume value differs from the previous volume value by more than a predetermined volume, which can be 10 litres, the processor 11 is programmed to report the present volume value and the present temperature value by composing a data message, containing said present volume value and temperature value and a unique identification number for the sensor unit 4. Likewise, the processor 11 is programmed to compose such a data message when the integral of the difference between the temperature value last reported by the processor 11, i.e., the temperature value which the processor 11 last included in a data message, and the present temperature value exceeds a predetermined temperature limit value, which can be in the range of 0.5-1.0° C. This way of monitoring the temperature entails a communications savings without the last reported temperature value in the receiver being misleading. For small changes in the temperature, a reporting thus takes place little by little, even if the temperature change between two measurement events is very slight, as long as it is present and thus is significant to report .

The above-mentioned temperature-related reporting will be explained more closely by means of an example, assuming that the last reported temperature value is 10°C and the temperature limit value is 0.7°C.

Say that the temperature value measured during the next event after the reporting is 10.5⁰C. The difference between the last reported temperature value and the present temperature value is then 10.5-10 = 0.5°C and the integral of the difference values, i.e., the aforementioned integral value, is consequently 0.5⁰C. The integral of the difference values is thus less than the temperature limit value and no reporting is done.

Say that the measured temperature value in the next event is 9.8°C. The difference between the last reported temperature value and the present temperature value is then 9.8-10 = -0.2⁰C and the integral of the difference values is consequently 0.5-0.2 = 0.3⁰C. The integral of the difference values is thus still less than the temperature limit value and no reporting is done.

Now say that the measured temperature value at the next event is 10.6⁰C. The difference between the last reported temperature value and the present temperature value is then 10.6-10 = 0.6⁰C. The integral of the difference values is consequently 0.5-0.2+0.6 = 0.9⁰C, that is, greater than the temperature limit value, and reporting is done. Preferably, the processor 11 is also programmed to include in each data message a unique message number for the present data message, information on the battery voltage of the battery 12, and a so-called cyclic redundancy check (CRC) sum, i.e., a cyclical check sum designed to determine whether the contents of the data message are correct or distorted.

The processor 11, moreover, is programmed to send the data message to a radio transmitter 13 included in the sensor unit 4, which in turn is designed to send out the data message as a radio signal 14 inside the storage container 1.

If the present volume value or temperature value does not differ from the previous volume value or temperature value, the processor 11 normally will not compose the aforesaid data message, in which case the radio transmitter 13 also will not receive any data message to send out. In this way, the sensor unit 4 avoids consuming energy in reporting no change in the storage container 1. If no change in the temperature or volume is detected over a lengthy time, say, 1-4 hours, the processor 11 is programmed to compose a control message, which contains information to the effect that nothing of importance is to be reported, yet the sensor unit 4 is functioning properly.

The sensor unit 4 also comprises a pulse circuit 15, connected to the aforesaid battery 12. The pulse circuit 15 is also connected to the distance meter 6, the temperature pickup 9, the processor 11 and the radio transmitter 13 so as to initiate at predetermined intervals, which can be for example once a minute, once every ten minutes, or some other interval, a measurement sequence and possibly a reporting sequence by sending an initialisation signal to the processor 11, which in turn controls the distance meter 6. A measurement sequence thus consists of the distance meter 6 and the temperature pickup 9 measuring the aforementioned distance between the sensor unit 4 and the bag 2 resting against the beer 3 and the aforesaid temperature in the air volume 10, the processor 11 computing the aforesaid volume value, and the processor 11 comparing the present volume value and temperature value with the previous volume and temperature value. A reporting sequence, which as described above is only done if a significant volume or temperature change is present or if a predetermined time has passed since the previous reporting, thus consists of the processor 11 composing the aforesaid data message or control message and the radio transmitter 13 sending out said radio signal 14 containing the data message or the control message.

The processor 11 is moreover designed to place the distance meter 6, the temperature pickup 9 and the radio transmitter 13 in a passive state of rest after the measurement sequence and the possible reporting sequence, when they have performed their respective tasks, and this state of rest continues until the pulse circuit 15 initiates the next measurement sequence. The time it takes for a measurement sequence is around 30 ms and the time it takes for a report sequence is around 300 ms . The time from the pulse circuit 15 initiating a measurement to the processor 11 placing the distance meter 6, the temperature pickup 9 and the radio transmitter 13 in the resting state is thus normally around 30 ms if there is nothing to report and around 300 ms if a radio message is sent out. Since the time taken for a measurement and reporting sequence is normally only fractions of a second, and since the data units 6 and 9, the processor 11 and the radio transmitter 13 are energised via the pulse circuit 15, which only consumes around a millionth of an ampere from the battery 12 in the resting state, the energy required by the sensor unit 4 is extremely low.

The pulse circuit's 15 battery-sparing operation is thus preferably supplemented by logic in the processor 11, so that the radio message is only sent out when changes of significance have occurred or when a predetermined time has elapsed since the previous reporting. In this way, the sensor unit 4 only needs to be active for a very short time, typically 30 ms, and only somewhat longer as an exception during radio broadcasting, typically 300 ms . In this way, the battery 12 will have a lifetime of many years, up to ten years.

After being sent out from the radio transmitter 13, the radio signal 14 bounces off the inner walls 16 of the storage container 1. The radio signal 14 also acts on the metal inspection port 17 with which each storage container 1 is provided. The inspection port 17, in turn, relays the radio signal 14, albeit somewhat attenuated, outside of the storage container 1 as a radio signal 18 which can be detected in the cold room 20. For this type of indirect emitting of radio signals it is possible to use, e.g., one of the frequencies 916.5 MHz, 868.35 MHz, 433.92 MHz, 418.0 MHz, 318.0 MHz, 315.0 MHz and

303.825 MHz. In Sweden, it is preferable to use one of the license-free frequencies 434 MHz, 868 MHz or 2.4 GHz, and it is most preferable to use the lowest frequency, i.e. , 434 MHz.

Figure 4 shows a storage container 1, which has an alternative embodiment of a sensor unit 31. The sensor unit 31 is similar to the above-described sensor unit 4, but with the difference that the sensor unit 31 has an external antenna 32, which is attached to the inside of an inspection window 33 above the inspection port 17. The radio signal is taken to the antenna 32 via a waveguide in the form of an antenna cable 34. This configuration can be used to produce stronger radio signals 18 outside the storage container 1.

Figure 5 shows yet another embodiment of an external antenna 35. Preferably the antenna cable 34 in this case is coaxial and shielded, so that the radio signal to the antenna 35 is not dampened when the bag 2 is filled to maximum size, such that it is pressed tightly against the roof of the storage container 1. In this way, the radio signal is taken unaffected in the antenna cable 34 to the inspection window 33. The antenna cable 34 is terminated by a round, electrically conducting body 36 with a diameter of about 3 cm, into which body 36 the radio signal is coupled. This body 36 is attached to the inside of the inspection window 33 and encapsulated in an electrically insulating material, so that the radio signal cannot be short-circuited by any beer leaking out from the bag 2. This body 36, like the above-described antenna 32, will act as an antenna for broadcasting of the radio signal inside the container.

Preferably, however, a second, outer, electrically conducting body 37 is arranged on the outside of the inspection window 33 opposite the first, inner body 36. Thanks to this arrangement, the bodies 36 and 37 are capacitively coupled to each other through the inspection window 33, and the radio signal sent out by the inner body 36 inside the storage container 1 will be picked up by the outer body 37 through this capacitive coupling. An antenna rod 38 is attached to and sticks out from the outer body 37, which is preferably encapsulated in an insulating material, and has a length attuned to the frequency of the radio signal 18. The antenna rod 38 thus acts like a resonator, oscillating in time with the frequency of the radio signal and, consequently, thanks to the bodies 36 and 37, it will emit the radio signal broadcast inside the storage container 1 as an external radio signal 18.

In this way, a radio signal strength can be achieved that can be picked up, even with a totally full storage container 1, at a distance of up to 10-15 m from the storage container 1.

In the cold room 20 there is a receiving unit 19, which comprises a radio receiver 21 for reception of the radio signals 18 from the sensor units 4 inside the storage containers Ia-Ic. The receiving unit 19 comprises a processor 22, which is designed to record the data message in each radio signal 18 received. Since each data message contains the unique identity of the sending sensor unit 4, the data message shows which storage container the information in the data message belongs to. The processor 22 is further designed to forward the information in the data message to a data storage unit 23. This data storage unit 23 can be, e.g., a server, in which a database 24 is arranged to receive and store the information. The processor 22 can be designed, e.g., to convey the information in familiar fashion to the database 24 through the Internet 25 via a gateway and a client 26.

In the data storage unit 23, which is preferably accessible via Internet from ordinary computers with web capability, the brewery staff can study both historical and current information on the fill level and temperature inside the various storage containers Ia-Ic, which information can be used, e.g., to plan the fill-up of the storage containers.

If so desired, buyers can also be given access to the information in the data storage unit 23, and preferably to the information pertaining to the storage containers which the buyers are using.

The sensor units 4 in the various storage containers 1, the receiver 19 and the data storage unit 23 thus form a system for simple and automatic monitoring of the fill level and temperature of the storage containers Ia-Ic.

It will be appreciated that the system can also be utilised to convey other information to the brewery's staff besides information related to the storage containers. For example, information on the refrigeration system 27 of the cold room 20 can be forwarded to the receiving unit 19, which in turn can send this information to the data storage unit. For example, a monitoring system 28 of the type described in EP 1 906 290 can be connected to the refrigerating system 27, in which case the monitoring system 28 sends radio signals 29 containing information on the refrigerating system 27 to the radio receiver 21, which information is then forwarded to the data storage unit 23 of the processor 22.

It will be appreciated that the system according to the invention can also be utilised to perform certain actions in the cold room 20. The processor 22, for example, can be connected to a valve 30, which is located between the storage containers Ia-Ic and the tapping site of the buyer. If the brewery staff discover that the buyer is tapping beer from a storage container without permission, they would be able to instruct the processor 22, via Internet 25 and gateway 26, to close the valve 30. Alternatively, the processor 22 can be programmed to automatically close the valve 30 if the sensor units 4 provide information indicating such unpermitted tapping. However, this requires the processor 22 to have some kind of software logic making it possible for the processor 22 to make its own decision based on the information in the radio signals 18 received.

The invention has been described above based on a specific embodiment. However, it will be appreciated that other embodiments and variants are possible within the scope of the invention.

Claims

C L A I M S

1. A method for remote monitoring of a plurality of pressurized storage containers (1) for beer (3) by means of a remote monitoring system, which remote monitoring system comprises: a sensor unit (4, 31) placed in each storage container (1) , a receiving unit (19) arranged adjacent to the storage containers (1), and a data storage unit (23) arranged at a distance from the storage containers (1), which sensor unit (4, 31) is attached to the inside of the storage container (1) at a level above the storage tank's (1) maximum allowed liquid level and comprises: a distance meter (6), a temperature pickup (9), a processor (11) , a battery (12) , - a radio transmitter (13) and a pulse circuit (15), which method comprises the step of: the pulse circuit (15), at predetermined intervals, initiating a measurement sequence by sending an initialisation signal to the processor (11), which measurement sequence comprises the steps of: the processor (11) causing the temperature pickup

(9) to measure the temperature of an air volume

(10) above said liquid level, - the processor (11) causing the distance meter (6) to measure the distance between the sensor unit (4, 31) and the liquid surface of the beer (3), and the processor (11) estimating a volume value for the amount of beer remaining in the storage container (1) from the measured distance, which method further comprises the step of: the processor (11) initiating a reporting sequence, which comprises the steps of: the processor (11) composing a data message, containing the temperature value and the volume value obtained during the measurement sequence and a unique identification number for the sensor unit (4, 31), the processor (11) sending the data message to the radio transmitter (13), - the radio transmitter (13) sending out the data message as a radio signal (14) inside the storage container (1) so that the radio signal (14) emanates from the storage container (1) and reaches the receiving unit (19) , - the receiving unit (19) receiving the radio signal (18) emanating from the storage container (1) and relaying the temperature value, the volume value and the sensor unit ' s unique identification number to the data storage unit (23), and the data storage unit (23) storing the temperature value, the volume value and the sensor unit's unique identification number in a database (24) .

2. The method according to claim 1, characterised in that the distance meter (6) uses ultrasound pulse techniques and the temperature value is used to compensate for a temperature dependency in the speed of sound of the ultrasound pulse sent out by the distance meter ( 6) .

3. The method according to any one of claims 1 and 2, characterised in that the reporting sequence comprises the steps of: the processor (11) including in the data message a unique message number for the current data message, information on the battery voltage of the battery (12) and a cyclical check sum, the receiving unit (19), upon receiving the radio signal (18), checking the cyclical check sum and the message number, and the data storage unit (23) saving the message number and the information on the battery voltage in the database (24) .

4. The method according to any one of claims 1-3, characterised in that the measurement sequence comprises the step of: the processor (11) comparing the volume value obtained in the current measurement sequence with a volume value from the immediately prior measurement sequence, and also in that the processor (11) initiates the reporting sequence only if the difference between said volume values exceeds a predetermined volume limit value.

5. The method according to claim 4, characterised in that the measurement sequence comprises the step of: the processor (11) computing, as a difference, the difference between the temperature value obtained in the current measurement sequence and the temperature value which the processor (11) last included in a data message, and also in that the processor (11) initiates the reporting sequence only if the integral of the differences in the measurement sequences since the last data message exceeds a predetermined temperature limit value .

6. The method according to claim 5, characterised in that the measurement sequence comprises the step of: the processor (11) recording the time elapsed since the volume limit value or the temperature limit value was last exceeded, and also in that the processor (11), if the elapsed time exceeds a predetermined time limit value, initiates a second type of reporting sequence, which comprises the steps of: the processor (11) composing a control message, containing the unique identification number for the sensor unit (4, 31) and information that nothing of importance is to be reported, yet the sensor unit (4) is working properly, the processor (11) sending the control message to the radio transmitter (13), - the radio transmitter (13) sending out the control message as a radio signal (14) internally in the storage container (1) so that the radio signal (14) emanates from the storage container (1) and reaches the receiving unit (19), - the receiving unit (19) receiving the radio signal

(18) emanating from the storage container (1) and relaying the information in the control message to the data storage unit (23) , and the data storage unit (23) saving the information in the control message in the database (24) .

7. The method according to any one of claims 1-6, characterised in that the processor (11), if no reporting sequence is initiated, places the distance meter (6), the processor (11) and the radio transmitter (13) in a passive resting state after the measurement sequence, or in that the processor (11), if no reporting sequence is initiated, places the distance meter (6), the processor (11) and the radio transmitter (13) in the resting state after the radio transmitter (13) has sent out the radio signal (14) .

8. A system for remote monitoring of a plurality of pressurized storage containers (1) for beer (3) that are placed in a cold room (20), characterised in that the system comprises: - a sensor unit (4, 31) placed in each storage container (1) , a receiving unit (19) arranged in the cold room (20), and a data storage unit (23) arranged at a distance from the cold room (20) , which sensor unit (4, 31) is attached to the inside of the storage container (1) at a level above the storage tank's (1) maximum allowed liquid level and comprises: a distance meter (6), - a temperature pickup (9), a processor (11), a battery (12) , a radio transmitter (13) and a pulse circuit (15), which pulse circuit (15) is designed to initiate at predetermined intervals a measurement sequence by sending an initialisation signal to the processor (11), which processor (11) is designed, upon receiving the initialisation signal, to measure the temperature of an air volume (10) above said liquid level by means of the temperature pickup (9) and measure the distance between the sensor unit (4, 31) and the liquid surface of the beer (3) by means of the distance meter (6) and estimate a volume value for the quantity of beer remaining in the storage container (1) from the measured distance, which processor (11) moreover is capable of producing a data message, which contains the temperature value measured by the temperature pickup (9), the aforesaid volume value, and a unique identification number for the sensor unit (4, 31), and sending this data message to the radio transmitter (13), which radio transmitter (13) is designed, upon receiving the data message, to send out the data message as a radio signal (14) internally in the storage container (1) so that it emanates from the storage container (1), which receiving unit (19) is designed to receive the radio signal (18) and relay the temperature value, the volume value, and the unique identification number of the sensor unit to the data storage unit (23) , and which data storage unit (23) is designed to store the temperature value, the volume value, and the unique identification number of the sensor unit in a database (24) .

9. The system according to claim 8, characterised in that the system comprises, for each storage container

(1), an antenna (32, 36) for broadcasting the radio signal (14) inside the storage container (1) .

10. The system according to claim 9, characterised in that the system comprises, for each storage container

(1), a body (37) arranged on the outside of the storage container (1), which body (37) is electrically conductive and capacitively coupled to the antenna (36) to relay the radio signal (18) outside the storage container (1) .

11. The system according to any one of claims 8-10, characterised in that each storage container (1) in the system is without a waveguide passthrough for the radio signal (14) .