Patent Publication Number: US-2023160758-A1

Title: Temperature sensing circuit including multiple thermistors

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 62/854,690, filed May 30, 2019, the entire content of which is incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described here related to a temperature sensing circuit for a device, such as an electrical device. 
     SUMMARY 
     Temperature sensing circuits for devices described herein include a substrate material, a first conductive portion, a second conductive portion, and a third conductive portion associated with the substrate material, and a plurality of thermistors associated with the substrate material for sensing a temperature associated with the device. The plurality of thermistors include a first thermistor and a second thermistor. The first thermistor is connected to the first conductive portion. The first thermistor and the second thermistor are both connected to the second conductive portion. The second thermistor is connected to the third conductive portion. 
     Methods of determining a temperature associated with a device described herein include sensing a temperature associated with the device using a temperature sensing circuit, receiving, by a controller, a signal from the temperature sensing circuit, and determining the temperature associated with the device based on the signal. The signal corresponds to an average of temperatures sensed by the plurality of thermistors. The device includes the temperature sensing circuit connected to the controller of the device. The temperature sensing circuit includes a first conductive portion, a second conductive portion, and a third conductive portion associated with a substrate material. The plurality of thermistors include a first thermistor and a second thermistor. The first thermistor is connected to the first conductive portion. The first thermistor and the second thermistor are connected to the second conductive portion. The second thermistor is connected to the third conductive portion. 
     Temperature sensing circuits for devices described herein include a substrate material, a first conductive portion, a second conductive portion, and a third conductive portion associated with the substrate material, and a plurality of thermistors associated with the substrate material for sensing a temperature associated with the device. The plurality of thermistors include a first thermistor, a second thermistor, a third thermistor, and a fourth thermistor. The first thermistor and the second thermistor are connected to the first conductive portion. The first thermistor, the second thermistor, the third thermistor, and the fourth thermistor are connected to the second conductive portion. The third thermistor and the fourth thermistor are connected to the third conductive portion. 
     Before any embodiments are explained in detail, it is to be understood that the embodiments are not limited in its application to the details of the configuration and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The embodiments are capable of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. 
     In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and/or application specific integrated circuits (“ASICs”). As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components, may be utilized to implement the embodiments. For example, “servers” and “computing devices” described in the specification can include one or more processing units, one or more computer-readable medium modules, one or more input/output interfaces, and various connections (e.g., a system bus) connecting the components. 
     Other aspects of the embodiments will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a battery pack that includes a temperature sensing circuit. 
         FIG.  2    illustrates a power tool that includes a temperature sensing circuit. 
         FIG.  3    illustrates a battery pack charger that includes a temperature sensing circuit. 
         FIG.  4    illustrates a control system including a temperature sensing circuit. 
         FIGS.  5 A,  5 B, and  5 C  illustrate a temperature sensing circuit according to embodiments described herein. 
         FIG.  6    is an electrical schematic diagram of a temperature sensing circuit according to embodiments described herein. 
         FIGS.  7 A,  7 B, and  7 C  illustrate a temperature sensing circuit according to embodiments described herein. 
         FIGS.  8 A,  8 B,  8 C, and  8 D  illustrate a temperature sensing circuit according to embodiments described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments described herein relate to a temperature sensing circuit for a device, such as a battery pack, a power tool, or a battery pack charger. The temperature sensing circuit includes a substrate material (e.g., a flexible substrate material), a first conductive portion, a second conductive portion, a third conductive portion, and a plurality of thermistors including a first thermistor and a second thermistor. The first conductive portion is connected to the first thermistor. The first and second thermistors are connected to the second conductive portion. The third conductive portion is connected to the second thermistor. The first conductive portion and the third conductive portion are configured to connect to a controller of the device to provide a signal to the controller. The controller is configured to receive the signal and determine a temperature associated with the device based on the received signal. The signal provided to the controller corresponds to an average of temperatures sensed by the plurality of thermistors. The controller is further configured to provide one or more control signals to control the device based on the temperature associated with the device. In some embodiments, the one or more control signals are configured or operable to control one or more of turning on a fan, turning off a fan, increasing a rotational speed of a fan, and decreasing a rotational speed of a fan. 
       FIG.  1    illustrates a battery pack  100  that includes a temperature sensing circuit. The battery pack  100  includes a housing  105  and an interface portion  110  for connecting the battery pack  100  to a device (e.g., a power tool). The temperature sensing circuit includes a plurality of thermistors for sensing a temperature associated with the battery pack  100 . The temperature sensing circuit is configured to provide a signal to a controller of the battery pack  100 . The controller of the battery pack  100  is configured to receive the signal from the temperature sensing circuit and determine a temperature associated with the battery pack  100  based on the signal received from the temperature sensing circuit. A temperature sensing circuit that can be used with the battery pack  100  is described below with respect to  FIGS.  5 A,  5 B,  5 C,  7 A,  7 B,  7 C,  8 A,  8 B,  8 C, and  8 D . 
       FIG.  2    illustrates a power tool  200  that includes a temperature sensing circuit. The power tool  200  includes a housing  205  and an interface portion  210  for connecting the power tool to a battery pack (e.g., battery pack  100 ). The temperature sensing circuit includes a plurality of thermistors for sensing a temperature associated with the power tool  200 . The temperature sensing circuit is configured to provide a signal to a controller of the power tool  200 . The controller of the power tool  200  is configured to receive the signal from the temperature sensing circuit and determine a temperature associated with the power tool  200  based on the signal received from the temperature sensing circuit. A temperature sensing circuit that can be used with the power tool  200  is described below with respect to  FIGS.  5 A,  5 B,  5 C,  7 A,  7 B,  7 C,  8 A,  8 B,  8 C, and  8 D . 
       FIG.  3    illustrates a battery pack charger  300  that includes a temperature sensing circuit. The battery pack charger  300  includes a housing  305  and interface portions  310 ,  315  for connecting the battery pack charger  300  to one or more battery packs (e.g., battery pack  100 ). The temperature sensing circuit includes a plurality of thermistors for sensing a temperature associated with the battery pack charger  300 . The temperature sensing circuit is configured to provide a signal to a controller of the battery pack charger  300 . The controller of the battery pack charger is configured to receive the signal from the temperature sensing circuit and determine a temperature associated with the battery pack charger  300  based on the signal received from the temperature sensing circuit. A temperature sensing circuit that can be used with the battery pack charger  300  is described below with respect to  FIGS.  5 A,  5 B,  5 C,  7 A,  7 B,  7 C,  8 A,  8 B,  8 C, and  8 D . 
       FIG.  4    illustrates a control system  400 . The control system  400  can be included in, for example, the battery pack  100 , the power tool  200 , or the battery pack charger  300 . The control system  400  includes a controller  405 . The controller  405  is electrically and/or communicatively connected to a variety of modules or components of the battery pack  100 , the power tool  200 , or the battery pack charger  300 . For example, the illustrated controller  405  is connected to an interface  410  (e.g., an interface of the battery pack  100 , the power tool  200 , or the battery pack charger  300 ). The controller  405  is also connected to one or more temperature sensors or temperature sensing circuits  415 . The controller  405  includes combinations of hardware and software that are operable to, among other things, control the operation of the battery pack  100 , the power tool  200 , or the battery pack charger  300 , measure a temperature associated with the battery pack  100 , the power tool  200 , or the battery pack charger  300 , etc. 
     In some embodiments, the controller  405  includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller  405  and/or the battery pack  100 , the power tool  200 , or the battery pack charger  300 . For example, the controller  405  includes, among other things, a processing unit  420  (e.g., a microprocessor, a microcontroller, or another suitable programmable device), a memory  425 , input units  430 , and output units  435 . The processing unit  420  includes, among other things, a control unit  440 , an ALU  445 , and a plurality of registers  450  (shown as a group of registers in  FIG.  4   ), and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit  420 , the memory  425 , the input units  430 , and the output units  435 , as well as the various modules connected to the controller  405  are connected by one or more control and/or data buses (e.g., common bus  455 ). The control and/or data buses are shown generally in  FIG.  4    for illustrative purposes. The use of one or more control and/or data buses for the interconnection between and communication among the various modules and components would be known to a person skilled in the art in view of the invention described herein. 
     The memory  425  is a non-transitory computer readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, such as a ROM, a RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. The processing unit  420  is connected to the memory  425  and executes software instructions that are capable of being stored in a RAM of the memory  425  (e.g., during execution), a ROM of the memory  425  (e.g., on a generally permanent basis), or another non-transitory computer readable medium such as another memory or a disc. Software included in the implementation of the battery pack  100 , the power tool  200 , or the battery pack charger  300  can be stored in the memory  425  of the controller  405 . The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller  405  is configured to retrieve from the memory  425  and execute, among other things, instructions related to the control processes and methods described herein. In other constructions, the controller  405  includes additional, fewer, or different components. 
     The interface  410  includes a combination of mechanical components and electrical components configured to and operable for interfacing (e.g., mechanically, electrically, and communicatively connecting) the battery pack  100 , the power tool  200 , or the battery pack charger  300  with another device. For example, the interface  410  is configured to receive power via a power line  460  between the controller  405  and the interface  410 . The interface  410  is also configured to communicatively connect to the controller  405  via a communications line  465 . 
     The controller  405  determines a temperature associated with the battery pack  100 , the power tool  200 , or the battery pack charger  300  using the one or more temperature sensors or temperature sensing circuits  415 . After determining the temperature of the battery pack  100 , the power tool  200 , or the battery pack charger  300 , the controller  405  is configured to provide information and/or control signals to another component of the battery pack  100 , the power tool  200 , or the battery pack charger  300  (e.g., a fan, a charge FET, a discharge FET, etc.). The control signals can be configured to, for example, turn a fan ON, turn a fan OFF, increase the rotational speed of the fan, decrease the rotational speed of the fan, etc. In other embodiments, the controller  405  takes a different control action based on the one or more signals received from the one or more temperature sensors or temperature sensing circuits  415  (e.g., disabling the battery pack  100 , turning OFF the power tool  200 , or turning OFF the battery pack charger  300 ). 
       FIGS.  5 A,  5 B, and  5 C  illustrate a temperature sensing circuit  500  according to embodiments described herein. The temperature sensing circuit  500  includes a material or substrate material  505 . The material  505  forms, for example, a flexible printed circuit board that includes a plurality of thermistors  510 ,  515 ,  520 , and  525 . The thermistors  520  and  525  are each connected to a first conductive portion  530  of the temperature sensing circuit  500 . The thermistors  510 ,  515 ,  520 , and  525  are each connected to a second conductive portion  535  of the temperature sensing circuit  500 . The thermistors  510  and  515  are each connected to a third conductive portion  540  of the temperature sensing circuit  500 . The first conductive portion  530  and the third conductive portion  540  are configured to connect to, for example, the controller  405 . In some embodiments, the signals provided to the controller  405  from the temperature sensing circuit  500  correspond to an average of the temperatures sensed by each of the thermistors  510 ,  515 ,  520 , and  525 . 
       FIG.  6    is an electrical schematic diagram of a temperature sensing circuit  600 . The temperature sensing circuit  600  corresponds to, for example, the temperature sensing circuit  500  illustrated and described with respect to  FIG.  5   . The temperature sensing circuit  600  includes a first thermistor  605  (“R 1 ”), a second thermistor  610  (“R 2 ”), a third thermistor  615  (“R 3 ”), and a fourth thermistor  620  (“R 4 ”). The first thermistor  605  is connected in parallel with the second thermistor  610 . The third thermistor  615  is connected in parallel with the fourth thermistor  620 . A combined resistance of the first thermistor  605  and second thermistor  610  is connected in series with a combined resistance of the third thermistor  615  and the fourth thermistor  620 . A total combined resistance, R C , of the first thermistor  605 , the second thermistor  610 , the third thermistor  615 , and the fourth thermistor  620  can be calculated as shown below in EQN. 1: 
     
       
         
           
             
               
                 
                   
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     The combined resistance, R C , of the first thermistor  605 , the second thermistor  610 , the third thermistor  615 , and the fourth thermistor  620  approximately equals the average resistance of the first thermistor  605 , the second thermistor  610 , the third thermistor  615 , and the fourth thermistor  620 . The average resistance corresponds to the average sensed temperature of the thermistors. As an illustrative example, for R 1 =15Ω, R 2 =20Ω, R 3 =20Ω, and R 4 =25Ω, EQN. 1 produces approximately the average resistance of 20Ω for the four thermistors. The combined resistance, R C , forms a voltage divider circuit with a fifth thermistor  630  (“R 5 ”). A tap point  625  of the voltage divider circuit can be provided to the controller  405 . Based on the value of the voltage signal the controller  405  receives, the controller  405  determines the approximate average temperature sensed by the first thermistor  605 , the second thermistor  610 , the third thermistor  615 , and the fourth thermistor  620 . As such, the temperature sensing circuit  600  is configured to produce a four-point average temperature measurement related to, for example, the battery pack  100 , the power tool  200 , and/or the charger  300 . In other embodiments, a different number of thermistors is used. In some embodiments, the number of parallel connected thermistors in each circuit branch equals the number of series connected branches (e.g., three circuit branches of three parallel connected thermistors). 
       FIGS.  7 A,  7 B, and  7 C  illustrate a temperature sensing circuit  700  according to embodiments described herein. The temperature sensing circuit  700  includes a material or substrate material  705 . The material  705  forms, for example, a flexible printed circuit board that includes a plurality of thermistors  710 ,  715 ,  720 , and  725 . The thermistors  720  and  725  are each connected to a first conductive portion  730  of the temperature sensing circuit  700 . The thermistors  710 ,  715 ,  720 , and  725  are each connected to a second conductive portion  735  of the temperature sensing circuit  700 . The thermistors  710  and  715  are each connected to a third conductive portion  740  of the temperature sensing circuit  700 . The first conductive portion  730  and the third conductive portion  740  are configured to connect to, for example, the controller  405 . In some embodiments, the signals provided to the controller  405  from the temperature sensing circuit  700  correspond to an average of the temperatures sensed by each of the thermistors  710 ,  715 ,  720 , and  725 . The temperature sensing circuit  700  is configured to produce a four-point average temperature measurement related to, for example, the battery pack  100 , the power tool  200 , and/or the charger  300 , as described above with respect to temperature sensing circuit  600  and  FIG.  6   . 
       FIGS.  8 A,  8 B,  8 C, and  8 D  illustrate a temperature sensing circuit  800  according to embodiments described herein. The temperature sensing circuit  800  includes a circuit board holder  805  having a retention structure or member  810  for receiving a printed circuit board  815 . The printed circuit board  815  is similar to the materials  505  and  705  described above with respect to  FIGS.  5 A,  5 B,  5 C,  7 A,  7 B, and  7 C . The printed circuit board  815  is, for example, a flexible circuit board that is configured to be received by the circuit board holder  805 . In some embodiments, the circuit board holder  805  and the printed circuit board  815  are each configured to be flexible or bendable and the temperature sensing circuit  800  can be folded around, for example, a battery cell or multiple battery cells. The retention structure  810  is configured to, for example, hold the printed circuit board  815  in place when the printed circuit board  815  is wrapped around a battery cell. The printed circuit board  815  includes a first conductive portion  820  and a second conductive portion  825 . In some embodiments, the temperature sensing circuit  800  includes a plurality of thermistors (e.g., four or more thermistors) like the temperature sensing circuits  500 ,  700 . 
     Thus, embodiments described herein provide, among other things, a temperature sensing circuit that includes a plurality of thermistors. Various features and advantages are set forth in the following claims.