WO2023235492A1

WO2023235492A1 - A system and method for controlling a portable heated product

Info

Publication number: WO2023235492A1
Application number: PCT/US2023/024155
Authority: WO
Inventors: Mark A. CASTRACANE
Original assignee: Ignik Outdoors, Inc.
Priority date: 2022-06-01
Filing date: 2023-06-01
Publication date: 2023-12-07

Abstract

An invention is described that utilizes a number of electrical taps along the length of a heating element that has a positive temperature coefficient of electrical resistance. The voltage developed at these taps can be measured and utilized by a closed loop control system to enhance temperature limiting and control. This method will also enhance the ability of said heating element to be safely utilized in rolled-up or folded product to facilitate rapid preheating of the device. An improvement in the structure of the heating element provides additional information to the signal processing circuitry to prevent overheating under various use situations. The control system for a portable heated product includes a direct current (DC) power port, a heating element connected to the DC power port, and a controller coupled between the DC power port and the heating element. The heating element includes at least one voltage tap that can be monitored by the controller. The controller is capable of determining a voltage at the at least one voltage tap to identify asymmetrical heat dissipation in the heating element and can adjust power delivered to the heating element in response to the identified asymmetrical heat dissipation.

Description

A SYSTEM AND METHOD FOR CONTROLLING A PORTABLE HEATED PRODUCT

FIELD OF INVENTION

[0001] This application is in the field of heating elements for portable products that provide for management of asymmetrical heat distribution. The invention described herein is an improvement to the delivery and control of electric heat as applied to products intended to be used in flexible heated camping gear and/or heated garments. Such an improvement would allow greater heat to be delivered while lessening the possibility of overheating if the product is folded or bunched, and also allow the heated product to be safely preheated in a rolled or folded condition.

BACKGROUND INFORMATION

[0002] Electric heating pads, electric blankets, electric throws, and other localized fabric material heating devices are well known. Such devices commonly employ a heating area, generally in the form of a fabric member which is associated with one or more heating elements, generally positioned interior of a multi-layer fabric member. Safety and control circuitry may include temperature-setting selectively actuating controls coupled to temperature sensors in the area of the elements. Such devices may be provided to operate at different voltages.

[0003] In previously described concepts of heating devices, heating element, generally a metal wire dispersed throughout the fabric, includes connections at the beginning and end of the metal wire. These connections allow the controller to ascertain the voltage across the heating element and the current through the heating element.

SUMMARY OF THE INVENTION

[0004] The present invention describes an improvement in the structure of the heating element that can provide additional information to the signal processing circuitry of a device’s control system to prevent overheating under the abnormal use situations, such as bunching or folding of a partial area of the blanket. Also, an improved method for operating a control system of a heated device based on this increased observability of temperature mapping of the heating element results in the practical ability to safely “preheat” the heated product in a symmetrically folded or rolled up condition. This allows, for example, a heated sleeping bag system to be preheated in a rolled-up condition to a higher temperature that would be utilized for sleeping while in the normal unrolled mode.

[0005] The control system for a portable heated product may include a direct current (DC) power port, a heating element connected to the DC power port, and a controller coupled between the DC power port and the heating element. The heating element includes at least one voltage tap that can be monitored by the controller. The controller is capable of determining a voltage at the at least one voltage tap to identify asymmetrical heat dissipation in the heating element. The controller adjusts the power delivered to the heating element in response to the identified asymmetrical heat dissipation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an example of a heating and control system for a portable heated product according to an exemplary embodiment of the present invention.

[0007] Figure 2 is example of a resistive wire heating device.

[0008] Figure 3 is an example of a resistive heating element for a portable heated product that is tapped according an exemplary embodiment of the present invention.

[0009] Figure 4 is an another example of a resistive heating element for a portable heated product that is tapped according to another exemplary embodiment of the present invention.

[0010] Figure 5 is an example of a control system for a portable heated product operable with a resistive heating element that is tapped according to an exemplary embodiment of the present invention.

[0011] Figure 6 is an example of a controller according to an exemplary embodiment of the present invention.

[0012] Figure 7 is a heating element structure and the equivalent resistance depiction of the heating element that is tapped according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION [0013] According to an exemplary embodiment of present invention, a system and method for controlling a portable heated product are provided that allows for asymmetrical heat distribution monitoring and regulation so that heated products can be preheated to a desired temperature such that when initially used by a user, the product will be at the desired temperature. In one aspect, an improvement in the structure of the heating element provides additional information to the signal processing circuitry and thereby prevents overheating under abnormal use situations, such as bunching or folding of a partial area of the blanket. In a further aspect, the increased observability of temperature mapping of the heating element allows for the practical ability to safely “preheat” the heated product in a symmetrically folded or rolled up condition. This allows, for example, a heated sleeping bag system or other heated device to be preheated in a rolled-up condition or nonstandard configuration to a higher temperature that is desired for immediate use in the normal operation configuration of the device, such as a sleeping bag in the normal unrolled mode that can be made ready for use.

[0014] For example, if only one-fourth of the heating element is severely folded or bunched, this can result in a significant increase of the temperature of that area, while the rest of the heating element has a more normal heat distribution profile. Since only one-fourth of the heating element will be at a high temperature, the resistance increase of the overall heating element may not be sufficient to provide effective temperature limitation information to the control circuitry to prevent overheating in the folded or bunched area.

[0015] The present invention describes an improvement of providing additional connections at various points electrically along the heating element. By examining the voltage at these additional connections, and comparing these voltages to the voltage applied to the heating element at reference points, additional information is made available to the sensing and control circuitry concerning the temperature landscape on the entire surface of the heating element.

[0016] Figure 1 illustrates an exemplary heating control system for a portable heated product which can be modified in accordance with the system and method described herein in order to achieve management of asymmetrical heat distribution.

[0017] A typical system for heating a product, shown in Figure 1, usually consists of a power source 101, microcontroller and user interface 102, power control device 103, various signal conditioning and analog circuits 104, and the resistive load to be heated 105. The typical resistive heating load often includes metallic wire or some other conductive material, distributed in a serpentine pattern on a fabric or plastic substrate. The control device would apply either alternating (AC) or direct current (DC) voltage to this equivalent resistance, and the resulting current would cause heat to be produced. The amount of heat would depend on the equivalent resistance of the heating element and the amount of current flowing through the device.

[0018] As shown in Figure 1, there is an exemplary block diagram of a control system for a heated product according to an exemplary embodiment of the present invention. The signal conditioning and analog circuitry 104 can be designed to monitor both voltage across the heating element 105 and the current flowing through the heating element 105. The ratio of these two values can be computed and utilized by the microcontroller and associated circuitry 102 to control the power delivered to the load 105. Using appropriate temperature control algorithms as desired for the particular application (e.g., sleeping bag, blanket, throw, etc.), temperature regulation can be achieved in combination with the system and method according to the present invention, described further below.

[0019] Often, the material used as the heating element will have a known, repeatable temperature coefficient of electrical resistance. For example, a heating element 105 may consist of copper wire that has a predictable positive temperature coefficient that produces an approximate 4% increase in electrical resistance for a 10-degree Celsius rise in temperature. This property has long been utilized to determine the average temperature of a heating element of a given length, because both the voltage across the heating element 105 and the current through the heating element 105 can be accurately measured at any given time. With this information, the equivalent resistance of the wire heating element can be determined at any time by comparing the “hot” value of this resistance to the “cold” value of the unheated wire. This value can be used to measure and control the average temperature of the heating element when a closed-loop control system is utilized.

[0020] Figure 2 is an example of a resistive wire heating device 105. The resistive wire heating device 105 may be in a serpentine pattern as illustrated This serpentine pattern of wire is electrically equivalent to a resistive circuit element with a predictable current to voltage ratio. Both the voltage across the heating element 105 and the current flowing through the heating element 105 may be monitored by a microcontroller. The ratio of the voltage and current values may be computed and utilized by a microcontroller 102 and associated circuitry to control the power delivered to the load or heating element 105, as described in Figure 1. With the appropriate temperature control algorithms, temperature regulation may be achieved.

[0021] Further in regard to Figure 2, an exemplary heating element structure and its equivalent resistance is shown which came operate in connection with the exemplary system shown in Figure 1. As shown in Figure 2, the heating element 105 can include a metallic wire or some other conductive material distributed in a serpentine pattern on a fabric or plastic substrate and can be energized with an applied voltage at points A and B, and the resulting current of this excitation can be monitored. The amount of heat generated in the heating element would depend on the equivalent resistance of the heating element in the amount of current flowing through the device. Heating element 105 can have any desired length, for example from a few centimeters or inches to a meter or foot or more, particularly in light of the type of portable heated product that is involved such as a sleeping bag, blanket, throw or other product.

[0022] A typical resistive heating load may consist of metallic wire or some other conductive material, distributed in a serpentine or other pattern on a fabric or plastic substrate. The control device may apply either Alternating Current (AC) or Direct Current (DC) voltage to this equivalent resistance, and the resulting current causes heat to be produced. The amount of heat may depend on the equivalent resistance of the heating element and the amount of current flowing through the device.

[0023] One significant limitation of the conventional approach for a temperature control system concerns the geometry and size of the actual heating element 105 and the drawback of the conventional approach to only measure the average temperature of the heating element 105. For example, problems arise in accurately monitoring the temperature of the heating element when the heating element 105 includes heating wire that is distributed over a large surface area that is both flexible and foldable onto itself. In such a circumstance, it is necessary for safety and performance issues that the maximum temperature of the heating element 105 be limited at any location on the heated surface. When only the average temperature of the heating element 105 can be determined, this gives rise to a deficiency in that the conventional approach for control systems will not be able to safely monitor the temperature of a fractional area of the heating element 105 if, for example, that fractional area is asymmetrically folded or bunched.

[0024] Referring now to Figures 1 and 3, a heating element structure and its equivalent resistance depiction are shown. The heating element 305 is energized by power supply 301 that applies voltage at points A and B. This results in current through the heating element and the excitation can be monitored. According to an aspect of the present invention, an improvement over the prior art approaches can be achieved by providing additional connections at various points electrically along the heating element 305. Exemplary connection points are indicated in Figure 3 by connection point 310 and connection point 320. By examining the voltage of these additional connection points 310, 320 and comparing these voltages to the voltage applied to the heating element 305 at points A and B, additional information is available to the microcontroller 102, signal conditioning circuitry 104 and power control device 103 (shown in Figure 1) concerning the temperature landscape on the entire surface of the heating element 305.

[0025] In Figure 3, heating element 305 and its equivalent resistive representation is “tapped” at the 2/3 and 1/3 position along its length indicated as connection points 310, 320. The serpentine heating element 305 has, for example, a uniform amount of resistance per linear dimension. Under conditions of uniform mechanical conditions of the entire heating element 305 (that is, when the entire length of the heating element 305 is roughly at the same temperature), the electrical potential measured at point VI should be 2/3 of that measured at point A, both with respect to ground. Likewise, the potential measured at point V2 should be 1/3 of that measured at point A, both with respect to point B.

[0026] If an area of the heating element 305 is subjected to different mechanical conditions than the rest of the structure, however, the resistance of the heating element 305 may not be uniform over its entire length. Such a condition could occur, for example, if one area of the heating element 305 was bunched or folded while the other was in free air. The departure of voltages at points VI and V2 via connection points 310, 320 from their expected values can be measured by the signal conditioning circuitry 104 and interpreted by the microcontroller 102 (see Figure 1). In the event that higher than expected voltages are detected at one of the connection points 310 or 320, the the microcontroller 102 can instruct that the overall power delivered by power source 101 to the device 105/305 be lowered, thus lessening the chance of any one area of the heating element 105/305 reaching too high a temperature.

[0027] The algorithm will be used to calculate a deviation from the originally supplied current and voltage. The algorithm will use the originally supplied values of both the current and voltage stored in the microcontroller and compare those values to a measurement obtained from voltage taps along the heating element. The algorithm will then compare the current values with the stored values to determine an offset. If the offset deviation is within a predetermined range, for example, 3%- 10% off the originally supplied values, the controller will not make any adjustments. If the offset deviation is outside of the predetermined range, the controller will make the necessary adjustments by either increasing or decreasing the current and voltage supplied.

[0028] The above system is of course not limited to the number of voltage taps or connection points 310, 320 shown, nor to their location in the voltage divider position of the entire heating element 305. Many configurations of a tapped heating element 305, or multiple heating elements 305, are possible. In an alternative method of construction according to another exemplary embodiment of the present invention, two parallel connected heating elements 305, each with a tap at the 1/2 length point, can be utilized, as illustrated in Figure 4.

[0029] Since Figure 3 illustrates one configuration of the many that can be utilized, the actual position of the taps or connections 310, 320 and the number of parallel heating element structures 305 can be optimized for the geometry of the heated device. The signals developed in this enhanced system of measurement of the positive temperature coefficient sensing can be utilized as the only sensing device of a closed-loop temperature control system, or be part of a multiple sensor system incorporating NTC sensors and mechanical thermostats.

[0030] Figure 5 is an exemplary control system for a portable heated product. According to this exemplary embodiment of the present invention, the control system 500 for a portable heated product includes a direct current (DC) power port 501, a heating element 503 connected to the DC power port 501, and a controller 502 coupled between the DC power port 501 and the heating element 503. The heating element 503 includes at least one voltage tap 504 that is monitored by the controller 502. The controller 502 is capable of determining a voltage at the at least one voltage tap 304 to identify asymmetrical heat dissipation in the heating element 303.

[0031] The controller 502 retrieves the voltage at the at least one voltage tap 504 and compares it to the overall voltage supplied to the heating element 503. In response to this calculation, the controller 302 may adjust power delivered to the heating element 503 in response to the identified asymmetrical heat dissipation. If the voltage retrieved at the at least one voltage tap 304 is higher than the power supplied to the heating element, the controller 502 may decrease the power.

[0032] At least one voltage tap 504 may be placed at a fixed position between a beginning and an end of the heating element 503. This voltage tap 504 may be placed equidistant between the beginning and end of heating element 503 or at any point along the heating element 303. Additionally or alternatively, the heating element 503 may include multiple voltage taps, and each voltage tap may be placed at a fixed position along the heating element, generally equally spaced apart or at any part along the heating element.

[0033] The heating element 503 may have a length capable of being placed in a rolled condition and can have one or more voltage tap disposed along the length. The controller 502 may operate to heat the heating element in the rolled position. For example, when the heating element is in the rolled position, the controller 502 may monitor multiple voltage taps along the length and compare the average power supplied to get an accurate mapping of the temperature along the entire heating element. The mapping of the voltage taps allows the circuitry to get a clear picture of whether the power needs to be increased or decreased to maintain a consistent temperate throughout the heating element.

[0034] The DC power port 501 may be between 5 and 24 volts. The DC power port 501 may supply up to 12 amps of current. The DC power port 301 may be one of USB, USB-C, or USB-C PD (Power Delivery Protocol), or a vehicle DC power port such as a car lighter outlet. The DC power port 501 also may include a battery bank, a lithium battery, a portable battery bank equipped with an Anderson Power Pole® connector or a coaxial power outlet. Alternatively, the power port 301 may be an AC power port in other exemplary embodiments. [0035] The voltage determined by the controller 502 may be a continuous voltage measurement across the heating element. The heating element may include multiple voltage taps and the voltage determined by the controller 502 may be a continuous voltage measurement across the heating element 505, as well as the current through the heating element 505.

[0036] The heating element 505 may include flexible copper wire. The flexible copper wire may be 24 gauge to 34 gauge or suitable wire gauges to achieve the desired resistance. The heating element 505 may alternatively include flexible nickel, nickel/copper alloy wire, or flexible iron wire. This heating element wire may be the entire structure of the heating element, or may be part of a more complex structure such as a coaxial heating element.

[0037] The controller 502 may further include a timer function. The timer function may control a duration of voltage applied to the heating element.

[0038] Figure 6 is an example of a controller according to an exemplary embodiment. As shown in Figure 6, controller 600 includes flexible cable 605 which on one end is coupled to a multi pin connector 6f 0. The body 6f 5 of controller 600 includes housing with on off buttons and a display 620. The other end of the flexible cable 605 includes a power input connector 625. Parameter adjustment button 630 also can be included on the side of housing 615 to be controlled by the operator.

[0039] In operation, a user of heated product can operate controller 600 to set desired temperature and monitor information provided by the control system. For example, one controller 600 may be used for multiple devices, such as a heated sleeping bag liner or a heated throw. The usage profiles for various devices may differ, and as such it may be advantageous for the controller 600 to know what device it is connected to optimize the operational modes available. The number and location of the taps along the heating element 305 may be utilized to tell the controller 600 what device has been connected.

[0040] Figure 7 is an exemplary heating element structure 705 and the equivalent resistance depiction of the heating element according to an exemplary embodiment. The heating element 705 may be energized with an applied voltage, for example at points A 701 and B 702, and the resulting current of this excitation may be monitored by the controller. Providing additional connections, for example, at voltage taps/connection points VI 710 and V2 720, at various points electrically along the heating element, results in a more accurate mapping of the overall temperature supplied to the heating element 705.

[0041] By examining the voltage at these additional voltage taps/connection points 710 and 720, and comparing these voltages to the voltage applied to the heating element 705 at points A 701 and B 702, additional information may be available to the sensing and control circuitry concerning the temperature landscape on the entire surface of the heating element 705. The controller may monitor the voltage taps along the length and compare this to the overall voltage of the heating element 705. The sensing of the voltage taps allows the circuitry to get a clear picture of whether the power needs to be decreased to prevent overheating in the area of the heating element associated with the voltage sensed at that tap.

[0042] Based on the additional information available to the sensing and control circuitry from the voltage tap, the controller may make adjustments to the voltage supplied to the heating element. For example, the controller may make small or big adjustments, or simply shut off the heating element altogether. The controller may monitor any deviations, small or large, between points A 701 and B 702 and the voltage taps 710, 720 and make adjustments accordingly. When the voltage deviates a predetermined range at any one of the voltage taps, for example, 3%-l 0% off the originally supplied voltage, the controller may make the necessary adjustments by either increasing or decreasing the voltage supplied.

[0043] The controller can use an algorithm to calculate a deviation from the originally supplied current and voltage. The algorithm will use the originally supplied values of both the current and voltage stored in the microcontroller and compare those values to a measurement obtained from voltage taps along the heating element. The algorithm will then compare the current values with the stored values to determine an offset. If the offset deviation is within a predetermined range, for example, 3%- 10% off the originally supplied values, the controller will not make any adjustments. If the offset deviation is outside of the predetermined range, the controller will make the necessary adjustments by either increasing or decreasing the current and voltage supplied. [0044] The exemplary system illustrated in Figure 7 is not limited to the number of voltage taps shown, nor to their location in the voltage divider position of the entire heating element. Many configurations of a tapped heating element, or multiple heating elements, may be possible. In an alternative method of construction, two parallel connected heating elements, each with a tap at the 1/2 length point, may be utilized.

[0045] Figure 6 is an example of one configuration of the many that may be utilized. The actual position of the taps and the number of parallel heating element structures may be optimized for the geometry of the heated device. The heating element may be any shape and size. The signals developed in this enhanced system of measurement of the positive temperature coefficient sensing may be utilized as the only sensing device of a closed-loop temperature control system, or be part of a multiple sensor system incorporating NTC sensors and mechanical thermostats.

[0046] The controller may be able to identify the heating device via a location and a number of voltage taps on the heating element. In an example, two devices, such as a heated sleeping bag liner and a heated throw, both have heating elements with a total resistance that is the same, say 3 ohms. Even though the overall resistance is the same, the application is different in that the two devices may be served by different operational modes of the controller. For example, the heated sleeping bag liner would only need to deliver a small amount of heat over an 8-hour period, while the heated throw would deliver a larger amount of heat over a shorter interval. The number and location of the taps of the heating elements of the two devices are utilized to inform the controller what load/device it is connected to.

[0047] The sleeping bag liner may have two voltage taps at the 1- and 2-ohm points along the heating element and are connected to inputs A and B on the controller. The heated throw on the other hand may have the same 1 and 2 ohm tap points but may now be connected to inputs B and A on the control. These connections would immediately let the controller identify which device it is connected to and allow the controller to optimize performance for that device. As another example, a heated sleeping pad cover may utilize just one tap at the 1.5 ohm position, and may be connected to the A input of the control, while leaving the B input open. Similarly, a heated seat cover could have its lone voltage tap connected to input B of the control, while input A is left open. The location of the voltage taps and their connection to the controller provide the necessary information to identify the heating device to provide optimum performance.

[0048] Additionally, a bead-type thermistor may be used to determine temperature. Bead-type thermistors are often used because they offer high stability, fast response times, and they may operate at high temperatures. Bead-type thermistors come in small sizes and exhibit low dissipation constants

Claims

WHAT IS CLAIMED IS:

1. A control system for a portable heated product, comprising: a direct current (DC) power port; a heating element connected to the DC power port; and a controller coupled between the DC power port and the heating element, wherein the heating element includes at least one voltage tap that can be monitored by the controller, wherein the controller is capable of determining a voltage at the at least one voltage tap to identify asymmetrical heat dissipation in the heating element, and wherein the controller adjusts a power delivered to the heating element in response to the identified asymmetrical heat dissipation.

2. The control system of claim 1, wherein the heating element has a length capable of being placed in a rolled condition and has more than one voltage tap disposed along the length.

3. The control system of claim 2, wherein the controller operates to heat the heating element in the rolled position.

4. The control system of claim 1, wherein the DC power port is between 5 and 24 volts.

5. The control system of claim 1, wherein the DC power port is one of USB, USB-C, or USB-CPD (Power Delivery Protocol).

6. The control system of claim 1, wherein the DC power port includes a battery bank or a lithium battery.

7. The control system of claim 1, wherein the voltage determined by the controller is a continuous voltage measurement across the heating element.

8. The control system of claim 7, wherein the heating element includes multiple voltage taps and the voltage determined by the controller is a continuous voltage measurement across the heating element as well as the current through the heating element.

9. The control system of claim 1 , wherein the heating element includes flexible copper wire.

10. The control system of claim 9, wherein the flexible copper wire is 24 gauge to 34 gauge.

11. The control system of claim 1, wherein the heating element includes flexible nickel or nickel /copper alloy wire.

12. The control system of claim 1, wherein the heating element includes flexible iron wire.

13. The control system of claim 1, wherein the controller further includes a timer function.

14. The control system of claim 13, wherein the timer function controls a duration of voltage applied to the heating element.

15. The control system of claim 1, wherein the heating element is part of a seat cover, a mattress cover, a blanket or a sleeping bag.

16. A method for controlling a portable heated product, the method comprising the steps of: coupling a heating element of said portable heated product to a direct current (DC) power port; and controlling said heating element to a controller coupled between the DC power port and the heating element, wherein said controller is operable to monitor at least one voltage tap of the heating element, determine a voltage of at the at least one voltage tap, identify asymmetrical heat dissipation in the heating element, and adjust a power delivered to the heating element in response to the identified asymmetrical heat dissipation.

17. The method of claim 1, wherein the heating element has a length capable of being placed in a rolled condition and has more than one voltage tap disposed along the length.

18. The method of claim 17, wherein the controller adjusts the power to the hearting elements when the heating element is in a rolled position.

19. The method of claim 16, wherein the DC power port is between 5 and 24 volts.

20. The method of claim 16, wherein the DC power port is one of USB, USB-C, or USB- CPD (Power Delivery Protocol).

21. The method of claim 16, wherein the DC power port includes a battery bank or a lithium battery.

22. The method of claim 16, wherein the voltage determined by the controller is a continuous voltage measurement across the heating element.

23. The method of claim 16, wherein the heating element includes multiple voltage taps and the voltage determined by the controller is a continuous voltage measurement across the heating element as well as the current through the heating element.

24. The method of claim 16, wherein the heating element includes flexible copper wire.

25. The method of claim 24, wherein the flexible copper wire is 24 gauge to 34 gauge.

26. The method of claim 16, wherein the heating element includes flexible nickel or nickel

/copper alloy wire.

27. The method of claim 16, wherein the heating element includes flexible iron wire.

28. The method of claim 16, wherein the controller further includes a timer function.

29. The method of claim 28, further comprising the controller uses the the timer function to control a duration of voltage applied to the heating element.

30. The method of claim 16, wherein the heating element is part of a seat cover, a mattress cover, a blanket or a sleeping bag.