Temperature sensing devices
A digitally based system is designed to sense temperatures at a plurality of places and transmit temperature data along a hard-wire cable or distributed (wireless) network to an integrated data collection and control appliance. The system can perform single “spot” measurements or arrange multiple readings in a database for later use. Semiconductor-based sensors with digital output and data transmission capabilities allow large numbers of sensors to be placed along extended lengths of signal cable consisting of only three or four wires. The device incorporates electrical insulating materials, encapsulants, and mechanical strain relief designed to protect the sensors and transmission lines from failures related to exposure to extreme cold. Though described here for cold region applications, the embodiment of this invention encompasses moderate and tropical environments as well, or temperatures ranging from −40 C. to +85 C.
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This patent resulted from a continuation application of U.S. patent application Ser. No. 11/890,661, filed Aug. 7, 2007, U.S. Pat. No. 7,736,052, Issue Date Jun. 15, 2010, which was based on U.S. Provisional Patent Application No. 60/837,183, filed Aug. 11, 2006, entitled “Multipoint Digital Temperature Acquisition System”, and the teachings of all the applications are incorporated herein by reference.
BACKGROUND OF THE INVENTION Field of the InventionThe invention pertains generally to ambient air, soil, and water temperature sensing and reporting instrumentation. More specifically, the invention discloses an assembly of temperature sensor modules specially adapted for repeated and prolonged use in harsh outdoor, underground and underwater conditions, especially at low ambient temperatures (i.e. to at least −40 degrees C./F.), and designed to resist damage from mechanical stresses arising from actions on the assembly such as flexure, twisting, kinking, and tension. The invention can be provided with a standard format electrical connector for electrical association with a separate external device via a signal cable. Alternatively the invention can utilize available wireless digital communication technology to operate without hard wire connections. The temperature sensors can be placed at any position along the signal cable.
The preferred embodiment of the invention features encapsulated sensor modules with integral strain relief and robust environmental protection. The materials and methods of construction offer superior extreme low temperature performance (i.e. to at least −40 degrees C./F.) and enable the sensor elements to tolerate more coil and uncoil cycles than the prior art.
BACKGROUNDThe short cool summers and long cold winters that typify the climatic conditions found at high latitudes are conducive to the formation of permafrost or perennially frozen ground. Climatic conditions at very high latitudes also result in seasonal and multiyear ice formations on many lakes and offshore (marine) environments. Permafrost soils present unique design and construction challenges in cold regions around the world for a broad range of projects including community housing, schools, utilities, roads and bridges, airports, resource development, and defense. The occurrence of freshwater ice on inland water bodies and sea ice in the offshore realm also has ongoing relevance to commercial and academic interests focused on resource development and transportation.
Continuous records of accurate ground temperature data highly resolved with depth are required for engineering, construction, and scientific purposes on a regional, local and site specific basis. The invention addresses a need to improve the reliability and performance over previous art while achieving user cost reductions.
DESCRIPTION OF PRIOR ARTThe prior art has been known and widely used for at least three decades. The prior art accomplishes temperature measurement using a plurality of analog sensors mounted on dedicated circuits within a multiconductor signal cable. The analog sensors typically consist of thermistors, temperature sensitive resistors, which exhibit a temperature dependent resistance. A separate conductor within a cable must be allocated to each sensor although multiple sensors of this type can share a common ground. DC resistance is the measured parameter for this type of sensor. Measurements are typically, accomplished in the field by connecting the leads from a conventional test meter to one dedicated circuit at a time and manually recording resistance values. Often a manual switching device is used between the test meter and multiconductor cable to improve the quality of the connections and speed of the procedure. Generic automated analog polling and data logging devices have also been used in cases where relatively few sensors are installed on a long-term basis such as under buildings or remote land-based or sea-based monitoring stations. The measured resistance is later converted to a temperature using the Hart-Steinhardt Equation with appropriate input parameters for the specific thermistor employed.
The use of thermistors for several decades has led to general acceptance of the methodology for obtaining multipoint temperature data as well as incremental improvements to the art. However, inherent limitations to the prior art persist. The signal cable must possess a separate conductor for each analog sensor plus one additional conductor to be used for ground. For applications that require many sensors, specialty signal cable with an unusually large number of conductors or more than one smaller multiconductor cable must be used to provide the required dedicated circuits. The use of cables with high numbers of conductors also increases manufacturing costs, and the cost of maintenance and repair. Large cables also tend to be heavy and inflexible for the end user who must carry, deploy, and recover the cables multiple times. The installation of analog sensors within a cable is typically completed using heat sensitive shrink materials which frequently form an unreliable seal with the outer jacket material and introduce areas of concentrated bending stress on either side of the splice area. Cold temperature failures of the outer cable jacket are common.
The invention possesses numerous benefits and advantages over known multipoint temperature sensing cables for cold regions. In particular, the invention utilizes an established digital communication protocol to reduce the number of required conductors within a cable, thereby affording lower weight and increased flexibility to the user.
The appended claims particularly point out and distinctly claim the subject matter of this invention. The various objects, advantages and novel features of this invention will be more fully apparent from a reading of the following detailed description in conjunction with the accompanying drawings in which like reference numerals refer to like parts, and in which:
The preferred embodiment of the invention uses the capability for the digital communications protocol to adapt to various network topologies shown in
The preferred embodiment may also be used in a mixed topology 26 having aspects of both star 10 and linear 18 topologies including multiple legs 14 extending from a control appliance 16 and a plurality of sensor modules 12 mounted along their length. Finally, a distributed wireless network topology 28 may be used having a plurality of sensor modules 12 attached to an interface device 30 associated with a bi-directional wireless communication unit 32. A distributed network 28 may utilize wireless mesh-type intelligence to independently form associations enabling communication between individual communication units 32 which independently would have physical separation distances exceeding their range.
The preferred embodiment includes a complete temperature acquisition system 34 illustrated diagrammatically in
The control appliance CPU 52 supports an embedded operating system capable of running a software load that controls the embodiment of the invention, issues various commands to acquire temperature data, organizes the returned data into a database file and attempts to transmit the data externally at user defined time intervals or in response to user requests.
The preferred embodiment of the invention advantageously uses the specialized signal cable 54 illustrated in
Given the cable outer diameter as a physical constraint, the use of fewer conductors than required in the prior art permits additional annular space to be allocated to other functions such as insulation, shielding, and mechanical protection improving the performance and service life of the cable. Moreover, fewer conductors diminishes manufacturing labor requirements and its associated costs.
The signal cable 54 provides a reliable path for power supply and communication between the control appliance 36 and individual sensor modules 12.
As shown in
The components of the preferred embodiment are readily available and consist of a surface mount resistor 84, polarized capacitor 86, non-polarized capacitor 88, two electrostatic discharge protection ICs 90, a diode half-wave rectifier on chip 92. The preferred embodiment of the sensor element 72 employs a digital temperature sensor IC capable of deriving power for operation from the data transmission conductor 58 by including a capacitor on chip and advantageously utilizing a communication protocol which maintains a logic level one (voltage high) state most of the time. Alternately, the digital temperature sensor IC 72 can recognize when external power is output from a diode half-wave rectifier on chip 92 and made available to the appropriate pin on the digital temperature sensor IC 72. The digital temperature sensor IC 72 can then advantageously utilize the power for improved reliability in extreme cold temperature conditions and/or where a plurality of sensors cumulatively exert to too great a current draw for regular data transmission to continue to occur reliably.
The preferred embodiment depicted as an assembled printed circuit board 70 in
Although not depicted in the preferred embodiment of the sensor module 12 shown in
The preferred embodiment also reserves a single conductor each for bi-directional data transmission 58 and data ground or reference 60.
The stability of the supplied voltage to the digital temperature sensor IC 72 is further ensured through the use of a non-polarized capacitor 88 between the regulator input 62 and drain 96. An additional polarized capacitor 86 installed between the regulator output 98 and an electrostatic discharge prevention device 90 also serves as a redundant current stabilizer in the event of momentary power loss. An additional ESD prevention device 90 functions to isolate the digital temperature sensor IC 72 from ESD events along the data transmission 58 and reference or ground lines 60.
PCBs 70 are rugged, inexpensive, and can be highly reliable. They require much more layout effort and higher initial cost than either wire-wrapped or point-to-point constructed circuits, but are much cheaper, faster, and consistent in high volume production. Also a printed circuit board can be employed as a platform for mounting the integrated circuit-based sensor 72 and allows additional mechanical isolation from stresses arising from flexure of the signal cable 54.
The control appliance 36 supports access to the data stored in memory 40 over a public data network, such as the global Internet via a network interface card 44.
In an initial step 102, the method provides for organization of future sensed temperature data into a database for storage and later retrieval. Incorporation of metadata associated with the time, or geographic position, local conditions, or purposes of one or many temperature readings benefits the consumer of the data. The initial step 102 is exemplary and other organizational schema may be implemented.
In a second step 104, substantial additional functionality beyond basic control and interaction with one or a plurality of sensor modules 12 is described for the control appliance 36. Generic computing platforms including a mobile handheld computing device are well suited for automation of many functions. Selection of upper and lower temperatures for comparison with sensed temperature data adds alarm capabilities. The frequency with which the control appliance acquires sensed temperature data and the duration of the recording period are described.
In a third step 106, sensor element property data specific to one or a plurality of sensor elements such as the digital temperature sensor IC 72 described, is determined and stored in a database and later applied to or combined with data as it is received from individual sensor modules to the control appliance 36, processed, and stored in a database. For instance, a constant offset value may be applied to each result received by the control appliance 36 from a sensor module 12.
In a fourth step 108, additional functionality is attributed to the control appliance 36 enabling configurable import and export operations to and from the control appliance via an input/output device 44 of various organizational data or data specific to one or a plurality of sensor elements.
In a fifth step 110, the method describes one means of selectively viewing previously acquired sensed temperature data either by project or by location or by time or by a combination of these criteria.
In a sixth step 112, the primary functionality of the multipoint digital temperature acquisition system is described. The control appliance initiates interaction with one or a plurality of sensor modules electrically associated with it and acquires sensed temperature data in accordance with the metadata determined in step 102, the frequency, duration, alarm settings, and units prescribed in step 104, and the unique sensor element property data determined in step 106.
Generalized layers of a computer program product 114 embodied on a computer-readable storage medium for substantially receiving a set of instructions for execution of method 100 by a control appliance are illustrated in
In another embodiment of the invention, a sensor module 12 could be wirelessly coupled to an interface device 46. Those with skill in the art will understand that a plurality of sensor modules could be coupled to the interface device 46 without departing from the spirit and scope of this application.
In yet another embodiment of the invention, data storage modules are incorporated between sensor modules and also between a sensor module and the proximal or distal ends of the cable apparatus. This embodiment, sensor modules coupled with displaced data storage modules, provides the advantage of allowing data relevant to one or a plurality of individual sensor modules to be housed within a data storage module that is physically associated with a hard-wired cable apparatus. These data can then be passed to the control appliance 36 thereby eliminating the need for the data to be known to the control appliance a priori and reducing the need for user interaction via the control appliance I/O 44. Examples of this data are cable serial number, calibration data, etc.
Embodiments of the present invention provide a novel multipoint temperature measurement cable which successfully integrates adaptations for improved life and performance in extreme low temperature field applications (i.e. to at least −40 degrees C./F.). Although the invention has been described in connection with a preferred embodiment, it should be understood that various modifications, additions and alterations may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention as described herein.
claims 1-19. (canceled).
Claims
20. A temperature sensing device comprising:
- a housing comprising an elongated structure having opposite ends spaced from each other in the elongated direction;
- a temperature sensor in the housing; and
- a cable extending from one end of the opposite ends of the housing, the cable comprising signal communication with the temperature sensor.
21. The device of claim 20 wherein the housing comprises a single structure of material.
22. The device of claim 20 wherein the housing comprises a single structure of polymeric material.
23. The device of claim 20 wherein the one end of the housing comprises a tapered configuration extending along the elongated direction to the cable.
24. The device of claim 20 further comprising a printed circuit board in the housing and wherein the temperature sensor is mounted on the printed circuit board.
25. The device of claim 20 wherein the cable comprises a conductor dedicated solely to an unregulated input power supply, and the conductor is coupled to the temperature sensor.
26. The device of claim 20 wherein the cable comprises at least four discrete conductors.
27. The device of claim 20 wherein the housing comprises polymeric material and wherein the cable comprises polymeric material, and wherein the polymeric material of the housing and the cable are the same polymeric material.
28. The device of claim 20 wherein the housing comprises a first polymeric material and wherein the cable comprises a second polymeric material different from the first polymeric material of the housing.
29. The device of claim 20 wherein the cable comprises a first polymeric material and a second polymeric material, the first polymeric material being a different composition relative the second polymeric material.
30. The device of claim 20 wherein the cable comprises at least three discrete polymeric structures.
31. The device of claim 20 wherein the cable comprises a first polymeric material and a second polymeric material, the first polymeric material comprising a different composition relative the second polymeric material.
32. The device of claim 20 wherein the cable comprises at least three discrete polymeric structures, one of the three polymeric structures comprises a composition different from a composition of an other of the three polymeric structures.
33. The device of claim 20 wherein the cable comprises at least three discrete polymeric structures, the three polymeric structures comprising three different polymeric compositions.
34. A temperature sensing device comprising:
- a housing comprising an elongated structure extending in an elongated direction;
- a temperature sensor in the housing; and
- a cable extending from the housing and comprising an elongated structure that extends in the elongated direction with the housing, the cable comprising signal communication with the temperature sensor.
35. The device of claim 34 wherein the housing comprises an outer surface configuration having only three surfaces.
36. The device of claim 35 wherein the three surfaces comprise a central cylindrical surface between two opposite end surfaces, the two end surfaces comprising conical surfaces.
37. The device of claim 34 wherein:
- the housing comprises a first cylindrical configuration between two opposite ends;
- the cable comprises a second cylindrical configuration having diametric dimensions less than diametric dimensions of the first cylindrical configuration of the housing; and
- the two opposite ends of the housing comprise conical configurations extending between the first and second cylindrical configurations.
38. A temperature sensing device comprising:
- a temperature sensor;
- a voltage regulator coupled to the temperature sensor; and
- a housing encapsulating the temperature sensor and the voltage regulator.
39. The device of claim 38 further comprising a printed circuit board encapsulated in the housing, wherein the temperature sensor and the voltage regulator are both mounted on the printed circuit board.
Type: Application
Filed: Jun 14, 2010
Publication Date: Oct 7, 2010
Applicant:
Inventors: Brian Rafael Shumaker (Anchorage, AK), Nicole Yvonne Shumaker (Atlanta, GA), David Howard Shumaker (Hendersonville, TN)
Application Number: 12/802,811
International Classification: G01K 1/08 (20060101);