A method of measuring and transmitting at ultra low temperatures, and a sensor

Abstract

A method (13) of measuring and wirelessly transmitting at ultra low temperatures comprising the steps of, providing (14) a sensor device (1) comprising, an electronic power converter (4) with a primary side (6) and secondary side (7), the electronic power converter (4) configured to convert a primary voltage to a secondary voltage, 5 a first battery cell (2) and a second battery cell (3), wherein the first battery cell and the second battery cell are connected in series and connected to the primary side (6), a sensor unit (5a), configured to generate a measurement signal, a transmission unit (5b) connected to the secondary side (7) and configured to receive a measurement signal and transmit a radio signal indicative of the measurement 10 signal, and a housing (9) configured to enclose at least the electronic power converter (4), first battery cell (2) and second battery cell (3), providing the sensor unit (5a) and the transmission unit (5b) with electric power, generating the measurement signal using the sensor unit, and transmitting the radio signal indicative of the measurement signal using the transmission unit.

Description

[0001] Title

[0002] A method of measuring and transmitting at ultra low temperatures, and a sensor device.

[0003] Field of the invention

[0004] The invention relates to the field of methods of measuring and sensor devices. Especially to the field of methods involving wireless radio transmission for extreme cold conditions, and sensor devices for the same.

[0005] Background

[0006] In the field of wireless sensor devices there is a need to operate at extreme temperatures. Modern industrial processes may have process steps where operating temperatures lie between minus 90 and plus 150 degrees Celsius. This creates significant challenges when it comes to operating battery powered sensor modules for surveying those processes, as the behavior of power sources and electronics change from one end to the other of this temperature range. All while the sensor device is constrained by size so that it can fit into places with limited space. This poses a significant challenge as the heat capacity of the sensor device is so small that the sensor device reaches in its core surrounding temperature quickly. And this means that the sensor and its components may be at extreme temperatures for extended periods of time. Actively regulating the temperature of electronics and batteries may be unfeasible due to limited energy or the risk of influencing a measurement.

[0007] Therefore, an object of the invention is to provide a method of measuring and a sensor device which enables wireless communication at ultra low temperatures.

[0008] Summary

[0009] The object is achieved by, a first aspect relating to a method of measuring and wirelessly transmitting at ultra low temperatures comprising the steps of: providing a sensor device comprising, an electronic power converter with a primary side and secondary side, the electronic power converter configured to convert a primary voltage on the primary side between 3 volt and 15 volt to a secondary voltage between 1,5 volt and 15 volt on the secondary side, a first battery cell and a second battery cell, wherein the first battery cell and the second battery cell are connected in series and connected to the primary side, a sensor unit, configured to generate a measurement signal, a transmission unit connected to the secondary side and configured to receive a measurement signal and transmit a radio signal indicative of the measurement signal, and a housing configured to enclose at least the electronic power converter, first battery cell and second battery cell; providing the sensor unit and the transmission unit with electric power using the electronic power converter, the first battery cell, and the second battery cell; generating the measurement signal using the sensor unit; and transmitting the radio signal indicative of the measurement signal using the transmission unit.

[0010] The batteries are connected in series such that the resulting voltage on the primary side 6 is double the voltage of each battery cell alone. At ultra low temperatures the voltage of the battery cells may be reduced by more than 50 percent in comparison to at 20 degree Celsius.

[0011] It has been shown that battery cells in series provide sufficient power and voltage for the sensor device to operate at ultra low temperatures.

[0012] This aspect allows measurement data to be transmitted wirelessly under ultra-low temperature conditions, thereby enabling a user to monitor one or more parameters in such environments. Furthermore, it may facilitate the observation of parameters in hard-to-access locations where a wired connection would be impractical.

[0013] Additionally, the method enables radio transmission from ultra low temperature enviroments with the use of a compact sensor device, as the required voltage for the electronic power converter is provided, and power for the transmission unit. Ultra low tempertaure conditions may constitute temperatures below minus 80 degree Celsius, such as below minus 85 degree Celsius or below minus 90 degree celcius. The electronic power converter may be configured to regulate the voltage on the secondary side between 3,2 and 3,4 volt. This may be advantagous as many off the shelf components are configured to operate at this voltage. Alternatively, the electronic power converter may be configured to regulate the voltage on the secondary side between 4,8 to 5 volt. Alternatively, the electronic power converter may be configured to regulate the voltage on the secondary side between 1,7 to 1,9 volt. The secondary voltage may lay between 1,5 volt and 5 volt.

[0014] The radio signal may be indicative of the measurement signal in various ways. In one embodiment, the measurement signal may be digitized using an analog-to-digital converter, and the resulting digital value may be encoded into a data packet which is transmitted via radio frequency using a wireless communication protocol, such as Zigbee, Bluetooth Low Energy. In another embodiment, the measurement signal may modulate a carrier wave used for radio transmission, for example, by varying the amplitude, frequency, or phase of the carrier in accordance with the measurement signal, such that the received radio signal inherently reflects the measurement signal without requiring packet-based transmission.

[0015] In some embodiments the first battery cell and the second battery cell are lithium thionyl chloride battery cells. The inventors have determined that this type of battery is beneficial for the use at ultra low temperatures, as it can reliably provide electric power at those temperatures, increasing the reliablity with which the sensor device operates.

[0016] In some embodiments the electric power converter is a buck-boost converter. This is advantagous for embodiments where the primary side voltage may be larger at some times and smaller at other times of operation than the desired secondary side voltage. In some embodiments the method further comprises a method step of placing the sensor device inside a production line. This may allow to observe parameters inside a production line, where wired access during operation is not possible due to process constraints. This may be valuable as a production process in the prodcution line may run for long time, such as for example a week, and being able to have information from inside the process allows to abort the process should there be unwanted conditions inside this process. This may save energy which is needed to cool the process to ultra low temperatures. Even in short process times, such as 2 hours, energy may be saved. Also a new process may be started earlier and the overall time for performing an operation may be reduced.

[0017] In a further embodiment the method step of placing the sensor device inside a production line comprises inserting the sensor device in a mount. The sensor device may project from the This may ensure the position of the sensor device inside the process line even under circumstances involving high flow of fluids, or when mounted on moving parts of the production line.

[0018] A cylindrical part of the housing may be partly inserted in the mount. This may ease the mounting of the sensor device in the mount.

[0019] Alternatively, the part of the housing may not be rotational symmetric such that the orientation of the sensor device inside the process line is stable and does not change. This may be particular relevant for measurements where a certain orientation of the sensor device is critical, such as for example a measurement of a flow direction.

[0020] In some embodiments, the method further comprises a method step of receiving the radio signal by a receive unit. This may allow to display the measurement signal to a user, or control an observed process in a cloosed loop manner. The receive unit comprises a radio interface suitable to receive the transmitted radio signal of the sensor device, and may comprise a receive unit controller configured to steer a process depending on the received measurement signal.

[0021] In some embodiments the steps of providing the sensor unit and the transmission unit with electric power, generating the measurement signal, and transmitting the radio signal are carried out periodically at predetermined intervals. This may reduce the energy consumption of the sensor device per unit time, effectively prolonging an operational time of the sensor device. Alternative only the transmission of the measurement signal is carried out periodically at predetermined intervals. It has been found that the wireless transmission of the radio signal is energy expensive, and limiting only the transmission still allows to collect measurement signals covering the time span between transmissions. This may allow to maintain a full picutre of the observed parameter while extending the opertional time of the sensor device, before the batteries are not providing sufficient power anymore.

[0022] For example, the measurement signal may be indicative of any one of, a temperature, a pressure, relative humidity, and a gas concentration. Temperature, pressure, relative humidity, and gas concentration are valuable parameters to observe and may reveal critical information about a process line. Additionally or alternatively, the measurement signal may be indicative of a flow speed or a flow direction.

[0023] A second aspect relates to a sensor device comprising an electronic power converter with a primary side and secondary side, the electronic power converter configured to convert a primary voltage on the primary side between 3 volt and 15 volt to a secondary voltage between 1,5 volt and 5 volt on the secondary side, a first battery cell and a second battery cell, wherein the first battery cell and the second battery cell are connected in series and connected to the primary side, a sensor unit, configured to generate a measurement signal, a transmission unit connected to the secondary site and configured to receive a measurement signal and transmit a radio signal indicative of the measurement signal, and a housing configured to enclose at least the electronic power converter, first battery cell and second battery cell.

[0024] In some embodiments, the housing encloses an antenna configured to transmit the radio signal, and the housing comprises a section of a nonmetallic material, configured to allow the radio signal to exit the housing. Alternatively, the antenna may be located outside the housing, thus the sensor device would not require a section of a nonmetallic material.

[0025] In some embodiments a sensor of the sensor unit is located outside the housing. This allow for faster reaction in the measurement to changes in the observed parameter.

[0026] The first and second aspect may generally have the same features and advantages as the respective other aspect.

[0027] In summary there is disclosed a method of measuring and wirelessly transmitting at ultra low temperatures comprising the steps of, providing a sensor device comprising, an electronic power converter with a primary side and secondary side, the electronic power converter configured to convert a primary voltage to a secondary voltage, a first battery cell and a second battery cell, wherein the first battery cell and the second battery cell are connected in series and connected to the primary side, a sensor unit, configured to generate a measurement signal, a transmission unit connected to the secondary side and configured to receive a measurement signal and transmit a radio signal indicative of the measurement signal, and a housing configured to enclose at least the electronic power converter, first battery cell and second battery cell, providing the sensor unit and the transmission unit with electric power, generating the measurement signal using the sensor unit, and transmitting the radio signal indicative of the measurement signal using the transmission unit. Brief description of drawings

[0028] Fig. 1 shows a system overview of a sensor device with two battery cells. Fig. 2 shows a system overview of a sensor device with three battery cells. Fig. 3 shows a flowchart of a method of measuring.

[0029] Fig. 4 shows a perspective view of a sensor device.

[0030] Fig. 5 shows a sensor device from a top view. Fig. 6 shows a sensor device from a side view. Fig. 7 shows a sensor device inside a process line.

[0031] Detailed Description

[0032] In the following embodiments are described in more detail.

[0033] Fig. 1 depicts a system overview of a sensor device 1 comprising two battery cells 2, 3 connected in series. The first battery cell 2 and the second battery cell 3 are connected to a primary side 6 of an electronic power converter 4. The electronic power converter 4 can regulate a varying voltage on the primary side 6 to a nearly constant voltage on a secondary side 7. This may be achieved by employing a closed- loop control system that adjusts a switching element based on feedback from the secondary side 7. The electronic power converter 4 typically includes a transformer or inductive component used to transfer energy from the primary side to the secondary side 7. A control circuit monitors the output voltage on the secondary side and compares it to a reference value. Based on the difference between the monitored voltage and the reference value, the control circuit generates a control signal that modulates the duty cycle or frequency of the switching element on the primary side. This modulation compensates for variations in the primary voltage, thereby maintaining the output voltage on the secondary side within a desired range. Thereby the over a temperature range varying primary side voltage is regulated to a nearly constant voltage on the secondary side. Alternatively, electromechanical voltage regulators may be used.

[0034] Typically the transmission of a radio signal requires more power than the generation of a measurement signal. The first 2 and the second battery 3 cell may be lithium thionyl chloride battery cells providing sufficient power and voltage at ultra low temperatures, as defined above. On the secondary side of the electronic power converter there is connected a sensor unit and a transmission unit. The sensor unit and the transmission unit are connected in parallel such that each one of them are provided with the full secondary side voltage. The sensor unit 5a and the transmission unit may be arranged on one circuit board. The electronic power converter 4 may also be arranged on the same circuit board.

[0035] The sensor unit 5a is configured to generate a measurement signal indicative of a desired parameter, this may be any one of a pressure, a temperature, a gas concentration, such as CO2, a flow, a flow direction, relative humidity, conductivity, vacuum, etc. The generation of the measurement signal is achieved via an electronic measurement component designed for the given parameter. The sensor unit 5a transmits the measurement signal to the transmission unit 5b where it is transformed to a radio signal and transmitted via an antenna such that it can be received from a distance.

[0036] Fig. 2 shows a system overview similar to the one shown in Fig. 1 with the difference that an additional third battery cell 8 is connected in series with the first 2 and the second battery 3 cell on the primary side. This provides a voltage that is 50 percent higher on the primary side in comparison to the system shown in Fig. 1. In principle further battery cells connected in series with the shown battery cells are feasible, as long as the power converter is designed and capable to operate over the voltage span from ultra low temperatures to room temperature.

[0037] Fig. 3 shows a flowchart of a method 13 of measuring and wirelessly transmitting at ultra low temperatures. The first step 14 is to provide a sensor device as described in the second aspect of the summary. The second step 15 is to provide the sensor unit and the transmission unit of the sensor device with electric power using the electronic power converter, the first battery cell, and the second battery cell. The third step 16 is generating the measurement signal using the sensor unit. The last step 17 is and transmitting the radio signal indicative of the measurement signal using the transmission unit. In some embodiments the steps 15, 16, 17 of providing the sensor unit and the transmission unit with electric power, generating the measurement signal, and transmitting the radio signal are carried out periodically at predetermined intervals. This means that after the first step 14 of providing the remaining steps 15, 16, 17 are periodically repeated, going from step 17, after some time, for example, any time between 1 second and 1 hour, to step 15.

[0038] Fig. 4, Fig. 5 and Fig. 6 show respectively a perspective, top, and side view of a sensor device 1. The sensor device 1 comprises all components shown in Fig. 1. Further the device comprises a housing 9 that encloses the battery cells 2, 3 , the electronic power converter 4, and the transmission unit 5b . The measurement unit 5a is partly enclosed by the housing 9 with only a sensor 10 which forms part of the sensor unit 5a being not covered by the housing 9. The housing 9 further comprises a nonmetallic section 11 to allow the radio signals emitted by the transmission unit 5b to leave the housing 9. The remaining parts of the housing 9 may be made of stainless steel for it's inert properties, so that it does not interfere with processes in which the sensor device is used. Alternatively, the entire housing may be made of a non-metallic material.

[0039] The housing further has a cylindrical part 12 comprising the battery cells. The battery cells are stacked on top of each other to achieve a series connection of the battery cells on the primary side. The battery comprising part 12 has a diameter DI between 20 and 40 mm, such as 25 mm, and may be connected to the remaining part of the housing via a threaded connection. D2 is a diameter of a remaining part of the sensor device comprising at least the transmission unit D2 is between 20 mm and 40 mm, such as 30 mm. The height of the housing H is between 60 mm and 120 mm, such as 80 mm.

[0040] Fig. 7 shows a sensor device 1 placed inside a production line 20, and emitting a radio signal 18 which is received by a receive unit 19. The receive unit 19 comprises an antenna suitable to receive the radio signal 18, decodes it and then makes it available to, for example, a user.

[0041] Reference Numerals

[0042] 1 sensor device

[0043] 2 first battery cell

[0044] 3 second battery cell

[0045] 4 electronic power converter

[0046] 5a sensor unit

[0047] 5b transmission unit

[0048] 6 primary side

[0049] 7 secondary side

[0050] 8 third battery cell

[0051] 9 housing

[0052] 10 sensor

[0053] 11 nonmetallic section

[0054] 12 cylindrical part of housing comprising battery cells

[0055] DI diameter of cylindrical part of housing comprising battery cells

[0056] D2 diameter of housing at top

[0057] H height of housing

[0058] 13 method

[0059] 14 method step of providing sensor device

[0060] 15 method step of providing electric power

[0061] 16 method step of generating measurement signal

[0062] 17 method step of transmitting

[0063] 18 radio signal

[0064] 19 receive unit

[0065] 20 production line

Claims

PATENT CLAIMS1. A method (13) of measuring and wirelessly transmitting at ultra low temperatures comprising the steps of,- providing (14) a sensor device (1) comprising, an electronic power converter (4) with a primary side (6) and secondary side (7), the electronic power converter (4) configured to convert a primary voltage on the primary side (6) between 3 volt and 15 volt to a secondary voltage between 1,5 volt and 15 volt on the secondary side (7), a first battery cell (2) and a second battery cell (3), wherein the first battery cell (2) and the second battery cell (3) are connected in series and connected to the primary side (6), a sensor unit (5a), configured to generate a measurement signal, a transmission unit (5b) connected to the secondary side (7) and configured to receive the measurement signal and transmit a radio signal (18) indicative of the measurement signal, and a housing (9) configured to enclose at least the electronic power converter (4), first battery cell (2) and second battery cell (3),- providing (15) the sensor unit (5a) and the transmission unit (5b) with electric power using the electronic power converter (4), the first battery cell (2), and the second battery cell (3),- generating (16) the measurement signal using the sensor unit (5a), and- transmitting (17) the radio signal (18) indicative of the measurement signal using the transmission unit (5b).

2. A method according to the previous claim, wherein the first battery cell (2) and the second battery cell (3) are lithium thionyl chloride battery cells.

3. A method according to any one of the previous claims, wherein the method further comprises a method step of placing the sensor device (1) inside a production line (20).

4. A method according to the previous claim, wherein the method step of placing the sensor device (1) inside a production line (20) comprises partly inserting the sensor device (1) in a mount.

5. A method according to any one of the previous claims, wherein the method further comprises a method step of receiving the radio signal (18) by a receive unit (19).

6. A method according to any one of the previous claims, wherein the steps of providing the sensor unit (5a) and the transmission unit (5b) with electric power, generating the measurement signal, and transmitting the radio signal are carried out periodically at predetermined intervals.

7. A method according to any one of the previous claims, wherein the measurement signal is indicative of any one of, a temperature, a pressure, relative humidity, and a gas concentration.

8. A sensor device (1), comprising, an electronic power converter (4) with a primary side (6) and secondary side (7), the electronic power converter (4) configured to convert a primary voltage on the primary side (6) between 3 volt and 15 volt to a secondary voltage between 3 volt and 5 volt on the secondary side (7), a first battery cell (2) and a second battery cell (3), wherein the first battery cell (2) and the second battery cell (3) are connected in series and connected to the primary side (6), a sensor unit (5a), configured to generate a measurement signal, a transmission unit (5b) connected to the secondary side (7) and configured to receive a measurement signal and transmit a radio signal indicative of the measurement signal, anda housing (9) configured to enclose at least the electronic power converter (4), first battery cell (2) and second battery cell (3).

9. A sensor device (1) according to the previous claim, wherein the housing (9) encloses an antenna configured to transmit the radio signal, and the housing (9) comprises a section of a nonmetallic material, configured to allow the radio signal to exit the housing (9).

10. A sensor device (1) according to the previous claims, wherein a sensor (10) of the sensor unit (5a) is located outside the housing (9).

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