Thermal Buffer Device and Installation Method Therefor

Abstract

A thermal buffer device and installation method therefor are disclosed. The device includes a body and a fastening system. The body has a substantially planar rear surface, is generally cubic in shape, and is formed from a solid piece of thermally insulating material. The fastening system secures the rear surface of the body against an attachment surface within a temperature controlled enclosure, where the attachment surface is at a location in the enclosure selected for temperature monitoring. A temperature probe inserts into the body. The device is designed to resist air temperature changes in the temperature controlled enclosures in which the device is installed (i.e. to operate as a temperature buffer). In a preferred embodiment, the fastening system enables positive mechanical mounting of the device within the temperature controlled enclosures.

Claims

1. A thermal buffer device of a temperature monitoring system, the device comprising: a body including a substantially planar rear surface, wherein the body is formed from a solid piece of thermally insulating material; and a fastening system for securing the rear surface of the body against an attachment surface within a temperature controlled enclosure, wherein the attachment surface is at a location in the enclosure selected for temperature monitoring.

2. The thermal buffer device of claim 1, wherein the body is generally cubic in shape.

3. The thermal buffer device of claim 1, wherein the fastening system provides positive mechanical mounting of the thermal buffer device.

4. The thermal buffer device of claim 1, wherein the fastening system includes one or more screws that are introduced into thru-holes of the body, at a front surface of the body that opposes the rear surface, and wherein heads of the screws are countersunk below a plane of the front surface to secure the rear surface of the body against the attachment surface.

5. The thermal buffer device of claim 1, wherein the attachment surface is substantially planar.

6. The thermal buffer device of claim 1, wherein the attachment surface is stationary.

7. The thermal buffer device of claim 1, wherein the fastening system includes pieces of hook and loop fastening material affixed to the rear surface of the body and the attachment surface.

8. The thermal buffer device of claim 1, wherein the body has a front surface that includes a logo.

9. The thermal buffer device of claim 1, wherein the temperature controlled enclosure is a refrigerated enclosure.

10. The thermal buffer device of claim 1, wherein the temperature controlled enclosure is a heated enclosure.

11. The thermal buffer device of claim 1, wherein the temperature controlled enclosure is a room within a premises.

12. The thermal buffer device of claim 1, wherein the thermally insulating material is polyethylene.

13. A method of installation for a thermal buffer device of a temperature monitoring system, the method comprising: identifying a temperature controlled enclosure; selecting a location in the temperature controlled enclosure for temperature monitoring and an attachment surface at the monitored location; placing a substantially planar rear surface of a body of the thermal buffer device to be disposed towards the attachment surface; and securing the rear surface of body against the attachment surface.

14. The method of claim 13, further comprising the body of thermal buffer device being substantially cubic in shape.

15. The method of claim 13, wherein securing the rear surface of body against the attachment surface is accomplished via a fastening system of the thermal buffer device.

16. The method of claim 13, wherein securing the rear surface of the body against the attachment surface comprises: using screws as the fastening system, by introducing the screws from a front surface of the body into thru-holes of the body, the front surface opposing the rear surface; and tightening the screws.

17. The method of claim 13, wherein selecting an attachment surface at the monitored location comprises identifying surfaces at the monitored location, and selecting a surface that is substantially planar.

18. The method of claim 13, wherein selecting an attachment surface at the monitored location comprises identifying surfaces near the monitored location, and selecting a surface that is stationary.

19. The method of claim 13, further comprising the temperature controlled enclosure being a refrigerated enclosure.

20. The method of claim 13, further comprising the temperature controlled enclosure being a heated enclosure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings:

[0038] FIG. 1 is a diagram of an exemplary temperature monitoring system that includes a proposed thermal buffer device, where the device is installed in a medical refrigerator as an example of a temperature controlled enclosure;

[0039] FIG. 2 is a perspective view of a thermal buffer device installed in a room of a premises as the temperature controlled enclosure, where the device is mounted near a floor of the room for monitoring the temperature of a water pipe;

[0040] FIG. 3 is a perspective view of a walk-in freezer as an example of a temperature controlled enclosure, where three thermal buffer devices are installed in different locations of the walk-in freezer;

[0041] FIG. 4 is a flow chart that describes a method of installation for a thermal buffer device; and

[0042] FIG. 5 and FIG. 6 are tables of temperature measurements taken over at least a 25 minute time period, for a temperature buffer device in the freezer of FIG. 3, where the measurements were taken to highlight the temperature buffering capabilities of the device during installation in FIG. 5, and after installation and upon removal of the device from the freezer in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0044] As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. Further, the singular forms and the articles a, an and the are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms: includes, comprises, including and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Further, it will be understood that when an element, including component or subsystem, is referred to and/or shown as being connected or coupled to another element, it can be directly connected or coupled to the other element or intervening elements may be present.

[0045] It will be understood that although terms such as first and second are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, an element discussed below could be termed a second element, and similarly, a second element may be termed a first element without departing from the teachings of the present invention.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0047] FIG. 1 shows an exemplary temperature monitoring system 100. The system 100 monitors temperaure in different locations of a temperature controlled enclosure. Here, the enclosure is a type of refrigerated enclosure, a medical refrigerator 64.

[0048] The system 100 includes various components. The components include thermal buffer devices 10, temperature probes 20, a wireless gateway 16, and a control unit 52.

[0049] The medical refrigerator 64 provides a temperature controlled environment 70 for medical products. The refrigerator has a door 32 that is pivotally attached using hinges 44. A medical bottle 66 placed on a shelf 65 of the refrigerator 64. In the figure, only a top portion of the refrigerator 64 is shown. A back wall 36 of the refrigerator 64 is visible.

[0050] The system 100 supports temperature monitoring of different locations N within the refrigerator 64. For this purpose, multiple temperature probes 20-1 through 20-N are each inserted into corresponding thermal buffer devices 10-1 through 10-N. The devices 10 are then installed at each of the different locations.

[0051] Thermal buffer device 10-1 is shown and is installed at location L1. Location L1 was selected to be close to items placed on the shelf 65. Specifically, the device is mounted to the back wall 36 of the refrigerator 64 as an attachment surface. The back wall 36 is substantially planar.

[0052] In more detail, the thermal buffer device 10-1 has a body 22 and a fastening system 12. The body has a top surface 27, a rear surface, a temperature sensing channel 19, a sensing point 21 and a front surface 28. The front surface 28 is facing the viewer. The channel 19 is centrally located within the body 22 and extends from the top surface 17 partially down into the body 22, ending at the sensing point 21. The rear surface is attached to the back wall 36 using screws as the fastening system 12. A logo 31 is also attached to the front surface 28.

[0053] The body 22 is made from a thermally insulating material such as polyethylene or polytetrafluoroethene (PTFE) that resists changes in temperature. These materials are also extremely rigid so as to protect the probe 20 from everyday usage when the device 10 in hostile kitchen and food service environments. Polyethylene, in particualar, is food safe, and is approved by the US Food and Drug Administration (FDA) for many uses in the food service and food equipment industries, in examples.

[0054] High Density Polyethylene (HDPE) is the preferred material for the body 22. HDPE is preferred because it is a material approved for contact with food or drinking water by multiple government and industry regulatory agencies. HDPE is approved as food safe by both the United States Department of Agriculture (USDA) and the FDA, in examples. The non-governmental industry agency known as the National Sanitation Foundation (NSF) also certifies HDPE under its standard 51, also known as NSF 51.

[0055] HDPE has many properties that make it a very suitable material for installation in food service equipment, in particular. It is acid, odor, moisture and mildew resistant. It has a melting point of 266 degrees F. (Fahrenheit) and an operating range of 150 to 200 degrees F. In the food service industry, for example, 190 deg F is the standard warming box temperature.

[0056] The temperature probe 20-1 has a head 18 that inserts into the channel 19. The head 18 typically includes a thermocouple device. The head 18 seats at the sensing point 21 of the channel 19. The sensing point 21 is typically located at least halfway down from the top surface 27, such that the probe head 18 is located below a plane of the top surface 27 when seated in the sensing point 21.

[0057] The temperature probes 20-1 through 20-N also connect to individual ports 11-1 through 11-N of the wireless gateway 16. The wireless gateway 16 has a wireless antenna 14 and communicates over a wireless communications channel 99 with the control unit 52.

[0058] The control unit 52 has a display 50 and a wireless antenna 14. Via its wireless antenna 14, the control unit 52 communicates with the wireless gateway 16 over the wireless channel 99. The control unit 52 is a computer device such as a computer workstation, laptop, tablet/phablet, or cellular smart phone device, in examples.

[0059] The wireless gateway 16 provides a source of power to the probes 20 at each of its ports 11, and receives voltages associated with temperature sent from each of the probes. The gateway 16 periodically gathers the voltages received at each of the ports 11 at a rate known as a heartbeat of the gateway 16.

[0060] The control unit 52 executes software programs for controlling the gateway 16, and displays temperature information sent from the probes 20. To control the gateway 16, the control unit 52 sends control messages over the wireless channel 99. The control messages enable or disable the ports 11 and adjust its heartbeat, in examples.

[0061] The system 100 generally operates as follows. The temperature probes 20-1 installed in each of the thermal buffer devices 10-1 through 10-N report the temperature at each of the monitored locations L1 through L10 to the wireless gateway 16. The reported temperatures are represented by voltages that are proportional to changes in the temperature detected by the heads 18 of the probes 20. The gateway 16 accesses the ports 11 according to the heartbeat, converts the voltages to associated temperature values, and reports the temperature values to the control unit 52. The control unit 52 displays the temperature values for the probes 20 at each of the locations L on its display 50.

[0062] At the control unit 52, an operator typically defines a range of allowed temperature values for each of the probes 20/locations L, and possibly one or more temperature threshold values. When the temperatures reported by each of the probes 20 are outside the allowed range and/or exceed the threshold values for each location L, the control unit 52 generates alarm messages. The alarm messages notify operators of possible problems at the locations L.

[0063] More recently, some components of the temperature monitoring systems 100 are incorporating Internet of Things (IoT) capabilities. IoT-capable objects can communicate wirelessly to form networks of internet-connected objects that are able to collect and exchange data. Examples of IoT-capable components in the temperature monitoring systems 100 can include the control units 52, the gateways 16, the temperature probes 20, and possibly even the thermal buffer devices 10.

[0064] To add IoT capabilities to an object, a small footprint, single board computer system is attached to the object. The single board computer system typically includes one or more low-cost computer processor cores with wireless networking interfaces, about 1 gigabyte (GB) of random access memory, a battery as a source of power, and a substrate. The processor cores, the memory, and the battery mount to the substrate and are connected to one another using wires or printed circuit traces within and/or upon the substrate. An operating system loaded into the memory of and executing on the processing cores of each IoT-equipped object enable the object to form the networks of internet-connected objects and exchange data. A common IoT single board computer system is Raspberry Pi.

[0065] The temperature monitoring systems 100 are also increasingly becoming more distributed in nature. Here, the control units 52 of these systems 100 might be connected to a computer network at a site or facility that is remote to/separate from the buildings or facilities where the temperature controlled enclosures are located. These remote networks are often owned and managed by a third party business entity (i.e. service provider) that is different from the business entities that own the temperature controlled enclosures to be monitored. In this way, the service provider can provide a cloud based temperature monitoring service for managing and operating the temperature monitoring systems 100 of multiple different business entities as clients. Typically, the gateways 16 of the systems 100 at each business entity communicate with the control units 52 at the service provider networks via cellular phone-based or Ethernet-based wireless communications, in examples.

[0066] FIG. 2 shows an embodiment of a thermal buffer device 10-2 of a temperature monitoring system. The device 10-2 is installed in a heated room 200 of a premises as the temperature controlled enclosure. The device 10-2 is mounted to a substantially planar wall 36 as the attachment surface.

[0067] The installation location of the device 10-2 is indicated by reference L2. The location L2 is adjacent to a floor 62 of the room 200 and near a water pipe 33. Here, the device 10-2 is installed to monitor the air temperature near the water pipe 33 to determine whether the pipe may freeze.

[0068] The view provided by the figure shows detail for the thermal buffer device 10-2 than was not possible in the device 10-1 of FIG. 1. Specifically, thru-holes 26 of the body 22, the rear surface 29 of the body 22, and dimensions of the body 22 are shown. In addition, more detail for the location of the temperature sensing channel 19 within the body 22 is shown.

[0069] The body 22 is generally cubic in shape, with dimensions of length, width, and height indicated by references l, w, and h, respectively. In one example, the dimensions l, w, and h are 1.75 inches (in), 0.75 in, and 2.25 in, respectively.

[0070] The front surface 28 is opposite to the rear surface 29, and the rear surface 29 is substantially planar.

[0071] The thru-holes 26 extend from the front surface 28 towards the rear surface 29 in a manner that is substantially parallel to a plane of the top surface 27. Center lines 17 that run through a center of the thru-holes 26 are shown.

[0072] A screw as the fastening system 12 is also shown and is exploded from one of the thru-holes 26. In one example, self-tapping stainless steel screws are used.

[0073] The screw as the fastening system 12 provides positive mechanical mounting of the rear surface 29 of the body 22 against the wall 36. Preferably, the thru-holes are chamfered within the block, indicated by reference 26c. This enables the head 13 of each screw to be countersunk below a plane of the front surface 28 when the body 22 is secured to the attachment surface/wall 36.

[0074] In another implementation, rather than the rear surface 28 being mounted directly against the attachment surface, the rear surface 28 is mounted such that an air gap is maintained between the rear surface 22 and the attachment surface. For this purpose, standoffs such as neoprene standoffs might be placed between the rear surface 28 and the attachment surface. In this way, the device 10-2 is not affected by possible differences in heating/cooling between the material of the rear surface 28 and that of the attachment surface.

[0075] Other embodiments of the fastening system 12 are possible. In one example, the fastening system 12 includes pieces of hook and loop fastening material. An exemplary piece of hook and loop fastening material is manufactured by Velcro BVBA. The material is affixed to the rear surface 28 of the body 22 and the attachment surface. In another example, the fastening system 12 includes pieces of interlocking material affixed to the rear surface 28 of the body 22 and the attachment surface that provides an interference fit/press fit. In one example, the material is food grade plastic.

[0076] The probe head 18 is seated within the temperature sensing channel 19 and is seated at the sensing point 21. The channel 19 is drilled or formed to provide a friction fit/snug fit of the head 18 within the body 22, and protects the head 18. Thermal paste may also be used to provide improved heat conduction between the head 18 and the block 22 and to more securely seat the probe head 18 within the body 22.

[0077] In another implementation, the device 10-2 is formed by creating the body around the probe head 20, such as via an injection molding process.

[0078] The temperature buffer device 10 can be used to monitor temperature controlled enclosures in many industries and applications. These industries and applications include agricultural monitoring, apartment property management, art gallery light and temperature monitoring, bank owned property monitoring, bed bug extermination temperature monitoring, beer cooler temperature monitoring, boat bilge pump monitoring, and boiler temperature monitoring, cold chain monitoring, cold weather protection, college dormitory monitoring, commercial and residential plumbing monitoring, property management and monitoring, commercial refrigeration monitoring, construction equipment monitoring, convenience store management, crawl space monitoring.

[0079] Other industries and applications include dairy cooler temperature monitoring, data center temperature monitoring, deli food cooler temperature monitoring, environmental monitoring solutions for wood floor maintenance, facility monitoring, farm to fork monitoring, fleet management, food service temperature monitoring, foreclosed property management, frozen pipes, greenhouse monitoring, grocery and cold chain monitoring, heating and cooling system monitoring, ice maker temperature monitoring, ice freezer/cooler temperature monitoring, industrial pressure sensors and monitoring, inventory tracking, k9 unit temperature monitoring, laboratory monitoring, m2m - machine to machine solutions, medical refrigerator temperature monitoring, morgue temperature monitoring, mortuary cooler temperature monitoring, and organ and tissue transplant cooler monitoring.

[0080] Yet other industries and applications include parking garage monitoring, pet kennel temperature monitoring, pharmaceutical refrigeration temperature monitoring, production line monitoring, refrigerated trailer temperature monitoring, remote monitoring for business, remote property monitoring, remote second home monitoring, remote temperature monitoring, rental tool and equipment tracking, school cafeteria cooler temperature monitoring, server room temperature monitoring, smart power monitoring, storage unit monitorin, structural monitoring, student housing monitoring, supermarket food temperature monitoring, traffic monitoring, vacant property monitoring, vacation home monitoring, walk-in cooler temperature monitoring, warehouse monitoring, wastewater monitoring, water heater monitoring, and wine storage monitoring.

[0081] FIG. 3 is a perspective view of a walk-in freezer 30. The walk-in freezer 30 is an example of food service equipment to which the thermal buffer device 10 is applicable. Here, three exemplary thermal buffer devices 10-3, 10-4, and 10-5 are mounted to different locations L3, L4, and L5 within the freezer 30. The probes 20 that insert into the devices 10-3, 10-4, and 10-5 and the other components of the temperature monitoring system 100 are not shown in the figure.

[0082] The walk-in freezer 30 has a door 32 connected to the walk-in freezer 30 via hinges 40. The door 32 is currently open. A side wall 38, a back wall 36, a ceiling 48, and the floor 62 of the freezer 30 are shown. These surfaces are all substantially planar (e.g. flat).

[0083] Each of the thermal buffer devices 10-3, 10-4, and 10-5 are mounted to different attachment surfaces at each of the locations L3, L4, L5, using different fastening systems 12. Device 10-3 uses pieces of material that form an interference fit, indicated by reference 43, as its fastening system 12. The fastening system 12 secures the rear surface 29 of the body 22 to the ceiling 48 as the attachment surface. In a similar fashion, device 10-4 uses screws as its fastening system 12 to secure the rear surface 29 of the body 22 to the back wall 36 as the attachment surface. Typically, self-tapping stainless steel screws are used in the freezer 30. Finally, device 10-5 uses pieces of hook and loop material, indicated by reference 41, as its fastening system 12. The fastening system 12 secures the rear surface 29 of the body 22 to the side wall 38 as the attachment surface.

[0084] It is also important to note that the attachment surfaces (e.g. ceiling 48, back wall 36, and side wall 38 of the freezer 30) are stationary/are surfaces of stationary objects. This means that the objects having the surfaces, and thus the surfaces themselves, either do not move or are not intended to be moved. These stationary attachment surfaces help protect the temperature probe 20 from the foot traffic and movement of food items and racks that occur daily in the walk-in freezer 30.

[0085] FIG. 4 is a flow diagram that describes a method of installation for an exemplary thermal buffer device 10. The device is a component of a temperature monitoring system 100.

[0086] In step 402, an installer identifies an enclosure within which a temperature controlled environment is maintained. According to step 404, the installer selects a location in the enclosure for temperature monitoring and an attachment surface at the monitored location. The attachment surface is a substantially planar surface such as a wall of the temperature controlled enclosure.

[0087] Then, in step 406, the installer places the rear surface 29 of the body 22 of the temperature buffer device 22 to be disposed towards the attachment surface. In step 408, using the fastening system 12, the installer secures the rear surface 29 of the body 22 against the attachment surface. In one example, the fastening system is screws that enter the thru-holes 26 at the front surface 28 of the body. The screws enable positive mechanical mounting of the body 22 against the attachment surface when the screws are tightened.

[0088] According to step 410, the installer affixes a logo 31 to the front surface 28 of the body 22. Alternatively, the logo 31 was previously affixed at the factory/prior to installation.

[0089] Finally, in step 412, the installer inserts the probe head 18 of the temperature probe 20 within the body 22 of the temperature buffer device 22. For this purpose, the installer places the probe head 18 in the temperature sensing channel 19 until the head 18 seats at the sensing point 21.

[0090] FIG. 5 and FIG. 6 are tables of temperature measurements taken over time for a thermal buffer device 10 in FIG. 3. These measurements illustrate the temperature buffering capabilities of the device 10. The dimensions l, w, and h for this device are 1.75 inches (in), 0.75 in, and 2.25 in, respectively.

[0091] In FIG. 5, the measurements began once the device 10 was installed in the freezer 30.

[0092] The table of FIG. 5 is arranged into rows 510 and columns 520. There are 31 rows, numbered 510-1 through 510-31. There are three columns, 520-1, 520-2, and 520-3.

[0093] Column 520-1 indicates the measurement number (1-31). Column 520-2 includes the temperature measurement reported by the probe 20 in the temperature buffer device 10. Column 520-3 shows elapsed time, in seconds, to achieve a 1 deg F temperature rise, relative to the time of the last/prior measurement.

[0094] Row 510-1 shows that the initial temperature of the device 10 was 60 deg F (15.56 C) when it was installed into the temperature controlled environment of the freezer 30. A second, unbuffered probe reported that the temperature of the freezer was 15 degrees F. (9.44 C).

[0095] Row 510-2 shows the time taken for the device 10 to decrease 1 deg F from the last measurement taken, in row 510-1. In a similar fashion, row 510-3 shows the time taken for the device 10 to decrease 1 deg F from the last measurement taken, in row 510-2. This repeats until the last measurement 31 in row 510-31.

[0096] As the number of measurements increase, the time that it takes for the device to decrease 1 deg F from each prior measurement gradually becomes greater, and then stabilizes. For example, the time values in column 510-3 for rows 510-27, 510-28, 510-29, 510-30, and 510-31 are 120 sec, 119 sec, 120 sec, 130 sec, and 160 sec, respectively.

[0097] The last portion of measurements 510-27 through 510-31 illustrate that once the device 10 has been installed for a time period of approximately 15 minutes, it takes nearly a minute and a half for the device 10 to sense a 1 deg F decrease in temperature.

[0098] The final time of 1780 seconds (29.66 minutes) is indicated by reference 530. This value is the sum of the time values in column 510-3, for each of the rows 510-1 through 510-31.

[0099] In FIG. 6, the measurements began after the device 10 had been installed for a time period within the freezer 30, and then removed from the freezer 30 to a room with a 60 deg F (15.56 C) ambient temperature. As in FIG. 5, the unbuffered temperature of the freezer was 15 deg F.

[0100] The table of FIG. 6 is arranged into rows 610 and columns 620. There are 31 rows, numbered 610-1 through 610-31. There are three columns, 620-1, 620-2, and 620-3.

[0101] Column 620-1 indicates the measurement number (1-31). Column 620-2 includes the temperature measurement reported by the probe 20 in the temperature buffer device 10. Column 620-3 shows elapsed time, in seconds, to achieve a 1 deg F temperature rise, relative to the time of the last/prior measurement.

[0102] Row 610-1 shows that the temperature of the device 10 for the first measurement was 30 deg F.

[0103] Row 610-2 shows the time taken for the device 10 to increase 1 deg F from the last measurement taken, in row 610-1. In a similar fashion, row 610-3 shows the time taken for the device 10 to increase 1 deg F from the last measurement taken, in row 610-2. This repeats until the last measurement 31 in row 610-31.

[0104] As the number of measurements increase, the time that it takes for the device to increase 1 deg F from each last/prior measurement gradually becomes greater, and then stabilizes. For example, the time values in column 610-3 for rows 610-27, 610-28, 610-29, 610-30, and 610-31 are 113 sec, 107 sec, 117 sec, 110 sec, and 105 sec, respectively.

[0105] The final time of 1558 seconds (25.96 minutes) is indicated by reference 630. This value is the sum of the time values in column 610-3, for each of the rows 610-1 through 610-31.

[0106] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.