Patent Application
20230187152
The present embodiment relate generally to temperature-sensing devices. More specifically, the present embodiments relate to a temperature-sensing tape having a plurality of integrated temperature-sensing elements.
Systems and devices such as electrical devices, batteries, or other equipment can be damaged by overtemperature conditions if such conditions are allowed to persist. Thus, it is common for systems and/or devices to be equipped with temperature-sensing devices that can be used to measure temperature variations at discrete locations on the surface of an electrical device. If a measured temperature exceeds a predetermined threshold, the electrical device may be automatically shut off until the overtemperature condition subsides or is remedied, thereby mitigating damage to the device or system being protected.
Batteries, such as Lithium ion batteries are designed to operate below a threshold or maximum safe operating temperature. Accordingly, a protection sensor to protect such a battery will optimally operate to prevent operation of the battery above the threshold temperature. To this end, temperature sensors such as PTC sensors, have been developed to trip at a targeted temperature in the range of the threshold temperature of the device or system to be protected. Ideally, in operation, given PTC sensor will trip at a corresponding temperature characteristic of the PTC material used to form the PTC sensor.
However, for a given product, such as a battery system, maximum operating temperature requirements may change. Accordingly, different sensors, having different trip temperatures, may be called for to accommodate changing requirements for thermal protection.
It is with respect to these and other considerations that the present improvements may be useful.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.
In one embodiment, a temperature-sensing tape is provided. The temperature-sensing tape may include a plurality of flexible conductor portions. The temperature-sensing tape may also include a sensor array, comprising at least one temperature-sensing element, disposed in electrical series with the plurality of flexible conductor portions, where the at least one temperature-sensing element comprises a bimetallic switch.
In another embodiment, a thermal protection arrangement is provided, including a protected component; and a temperature-sensing tape, thermally coupled to the protected component. The temperature-sensing tape may include a plurality of flexible conductor portions; and a sensor array, comprising at least one temperature-sensing element, disposed in electrical series with the plurality of flexible conductor portions, where the at least one temperature-sensing element comprises a bimetallic switch.
In a further embodiment, a method of protecting a component ma include ,adhering a temperature-sensing tape to at least one protected area of the component, where the temperature-sensing tape has at least one temperature-sensing element, where the at least one temperature-sensing element includes a bimetallic switch. The method may also include determining a safe state corresponding to a logical “0” when an electrical resistance of the temperature-sensing tape is below a first threshold; and determining an unsafe state corresponding to a logical “1” when the electrical resistance of the temperature-sensing tape is above a second threshold.
Exemplary embodiments of a temperature-sensing tape in accordance with the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. The temperature-sensing tape may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey certain exemplary aspects of the temperature-sensing tape to those skilled in the art.
The present embodiments provide a temperature-sensing tape and a thermal protection arrangement and techniques, based upon a sensor array that is formed of temperature-sensing elements having a bimetallic switch. As used herein, a “tape,” “temperature-sensing tape,” or similar term, may refer to a structure having an array of temperature-sensing elements that are arranged in electrical series with a conductor, where the conductor may be integrated in a flexible tape material, integrated in a cloth material or woven structure, or may be a freestanding conductor, such as a wire. The tape may be adapted to be affixed to a protected element where temperature is to be measured, such as a battery. In particular, the tape may be affixed at least in locations of the tape where the temperature-sensing element is present, so as to impart thermal contact between the temperature-sensing element and protected element.
Referring to
A plurality of temperature-sensing elements 14 may be disposed on the substrate 12 and may be spaced apart from one another along a length of the substrate 12. Each of the temperature-sensing elements 14 may include a bimetal switch 16, acting as a temperature-sensitive switch. By way of example, the tape 10 is shown in
The tape 10 may further include a conductive circuit, formed within an electrical conductor, arranged in electrical series with the temperature-sensing elements 14. In the specific example illustrated in
As noted, the tape 10 may be sufficiently flexible to be applied to protected elements or arrays of elements that define various surfaces, including multiple surfaces extending at angles to one another, curved surfaces, and so forth.
Depending upon the exact configuration of the bimetallic element 82 and contact 84, and the normal operation temperature designed for the bimetallic switch 80, the bimetallic switch 80 may be considered a normally open switch or a normally closed switch.
Note that in accordance with known bimetallic switches, the bimetallic switches of the present disclosure may act reversibly so that when cooled from a temperature above the switch temperature, the bimetallic switch will close and return an electrical circuit to a closed circuit condition. Note also that an electrical hysteresis may be present in the bimetallic switches of the present embodiments. In particular, the switch temperature upon heating may be greater than the return temperature upon cooling, where the ‘return temperature’ refers to the temperature of the bimetallic switch during cooling from above the switch temperature, where the bimetallic switch returns to a closed configuration.
Generally, the degree of hysteresis of a bimetallic switch of the present embodiments may vary, but may be equal to one degree C. or more, several degrees, or up to tens of degrees according to some embodiments of the disclosure.
Note that the above examples illustrate that a temperature-sensing element configured with a bimetallic switch may provide a truly digital response where current flow is abruptly cut off or returned at a given temperature. While the above examples may be implemented in a bimetallic switch configured with a bimetal strip foil, in other non-limiting embodiments, a bimetallic switch may be a bi-metal arm, a bi-stable disk, a micro-electromechanical system (MEMs) structure, or a metal wire structure. Moreover, a bimetallic switch using a MEMs structure, may include a MEMs structure formed on a printed circuit board substrate.
Referring to
The tape 10 may be adhered to the battery 110, with the temperature-sensing elements 14 disposed on surfaces of respective cells (cells 112) of the battery 110. Particularly, each of the temperature-sensing elements 14 may be positioned so as to be under the thermal influence of a respective one of the cells 112 such that an increase in a temperature of one of the cells 112 may cause an increase in a temperature of a respective one of the temperature-sensing elements 14 disposed thereon.
The protection arrangement 100 may further include a control element 116 (e.g., a digital control element such as an ASIC, a microprocessor, etc.) that may be electrically connected to the flexible conductors 18 of the tape 10 and that may be configured to monitor a resistance in the tape 10 as further described below. The control element 116 may also be operatively connected to a disconnect switch 118 (e.g., a FET, a relay, etc.) that may be connected in electrical series intermediate the battery 110 and the load 114.
During normal operation of the protection arrangement 100, the battery 110 may supply electrical power to the load 114, and the temperatures of the cells 112 may be within a normal operating range (e.g., less than 60 degrees Celsius, less than 80 degrees Celsius, etc.). However, upon the occurrence of an overtemperature condition, the temperature of one or more of the cells 112 may increase above the normal operating range, which increase may in-turn cause the temperatures of respective temperature-sensing elements 14 of the tape 10 to increase. If the temperature of one or more of the temperature-sensing elements 14 increases above the switching temperature, the resistance in the tape 10 may increase sharply as the bimetallic switch 16 causes an electrical open. An increase in the temperatures of the cells 112 may result from exposure to an external heat source (e.g., the protection arrangement 100 sitting out in the sun), or from an overcurrent condition caused by an internal fault in the battery 110, for example.
The control element 116 may be configured to monitor a resistance of the tape 10, or a voltage change, for example, and to control operation of the protection arrangement 100 accordingly. For example, when a bimetallic switch of the temperature-sensing element 14 is closed, the control element 116 measures a relatively low resistance in the tape 10, indicating that the temperatures of the temperature-sensing elements 14 are below the switch temperature. The control element 116 may determine that the temperatures of the cells 112 are within a normal, safe operating range. However, if the control element 116 measures a relatively high resistance in the tape 10, indicating that the temperature of one of more of the temperature-sensing elements 14 is above the switch temperature, the control element 116 may determine that the temperature of one or more of the cells 112 has exceeded the normal, safe operating range. If the control element 116 determines that the temperature of one or more of the cells 112 has exceeded the normal, safe operating range, the control element 116 may open the disconnect switch 118, thereby arresting the flow of current in the protection arrangement 100 and preventing or mitigating damage that could otherwise result if the overtemperature or overcurrent condition were allowed to persist.
In additional non-limiting embodiments, a protected component may include a power tool having a battery pack, an e-scooter or other electric vehicle, a laptop computer, a notebook computer, a large battery system. Ad advantage afforded by a flexible tape of the present embodiments is the ability to conveniently place a sensor of plurality of temperature sensors, as well as fuse elements at any suitable location in a three-dimensional object having any arbitrary shape.
Regarding the aforementioned embodiments, in some variants, the substrate 12 may have an adhesive on a bottom side of the tape 10, for attachment to a device being protected, on a bottom side of the tape 10, for attachment to a device being protected. In some embodiments, adhesive can be applied to just sections under a temperature-sensing element 14, to improve thermal contact to a surface of a device being protected. In particular embodiments, additives that have high thermal conductivity may be arranged within an adhesive, such as a high thermal conductivity powder, to improve thermal conductivity of the adhesive, and thus provide better thermal contact between a temperature-sensing element 14 and device being monitored or protected. Non-limiting examples of thermal high conductivity materials include intrinsic (low electrical conductivity) ZnO, Al2O3, AlN diamond paste, or high-thermal-conductivity electrically conductive particles including ceramic, metal or carbon based particles, fibers etc.
At block 604, a safe state corresponding to a logical “0” (or alternatively a logical “1”) is determined when the resistance of the temperature-sensing tape lies below a first threshold. At block 606 an unsafe state corresponding to a logical “1” (or alternatively a logical “0”) is determined when the resistance of the temperature-sensing tape is above a second threshold. The second threshold may generally be greater than the first threshold.
In sum, the present embodiments provide various advantages for temperature-sensing and overtemperature control. For one, the use of a bimetallic switch provides a truly digital response as the switch transitions abruptly between an open circuit and closed circuit configuration. A tape arranged with bimetallic switch sensor of the present embodiments may be configured to provide switching temperatures over a wide temperature range, based on the same device. In addition, such a tape should pass reliability requirements well above an activation temperature.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
While the present disclosure makes reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claim(s). Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.
