PPTC Actuator Heater

Abstract

A novel heater for a temperature sensitive actuator is disclosed. The heater is a polymeric positive temperature coefficient (PPTC) device consisting of conductive fillers and a semi-crystalline polymer. The PPTC heater is strategically designed to have a pre-determined self-regulating temperature suitable for any application in which the heater is utilized. The physical characteristics of the PPTC heater, such as gap width and thickness, allow strategic control of the current flow through the heater.

Description

[Technical Field]

[0001] TECHNICAL FIELD Embodiments of the present disclosure relate to PPTC devices, and more particularly to PPTC devices operating as heaters. [Background technology]

[0002] Positive Temperature Coefficient (PTC) and Polymer PTC (PPTC) devices are utilized in circuits to interrupt overcurrent and overvoltage conditions that could damage expensive circuitry in electronic systems. PTCs contain materials that change physical properties when heated. As the temperature of a PTC increases due to increased current flow, its resistance increases. Once the fault condition is removed, the PTC device cools back to its original setting. Therefore, PTCs and PPTCs are considered resettable fuses.

[0003] More recently, PTC technology has been used in heater applications, but the size and shape of PTC devices make them unsuitable for some applications, as they must have a much higher power density than is necessary to be effective in heating applications.

[0004] It is with respect to these and other considerations that the present improvements may be useful. Summary of the Invention

[0005] 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 to aid in determining the scope of the claimed subject matter.

[0006] An exemplary embodiment of a polymeric positive temperature coefficient (PPTC) heater according to the present disclosure may include a first electrode connected to a first electrical wire, a heater body composed of a PPTC polymer matrix, where the PPTC polymer matrix includes both a conductive filler and a semi-crystalline polymer. The PPTC heater also includes a second electrode connected to a second electrical wire, with the PPTC polymer matrix between the first and second electrodes forming a sandwich. A bending process is used to form the sandwich into a ring shape.

[0007] Another exemplary embodiment of a PPTC heater according to the present disclosure may include a heater body including a conductive filler and a semi-crystalline polymer, the heater body configured as a rectangular sheet of a predetermined thickness, a first electrode disposed on a side of the heater body at a first end, the first electrode connected to a first wire, and a second electrode disposed on the same side of the heater body at a second end, the second electrode connected to a second wire. A gap is between the first electrode and the second electrode, the gap being horizontal to the first and second wires. The gap has a second predetermined thickness, and the heater body between the first electrode and the second electrode is exposed by the gap. The PPTC heater is formed in a circular ring shape with the first electrode and the second electrode facing the inner surface.

[0008] Another exemplary embodiment of a PPTC heater according to the present disclosure may include a heater body including a polymer matrix, the heater body configured as a rectangular sheet of a predetermined thickness, a first electrode disposed on a side of the heater body at a first end, the first electrode connected to a first wire, and a second electrode disposed on the same side of the heater body at a second end, the second electrode connected to a second wire. A gap is between the first electrode and the second electrode, the gap being perpendicular to the first and second wires. The gap has a second predetermined thickness, and the heater body between the first electrode and the second electrode is exposed by the gap. The PPTC heater is formed in a circular ring shape with the first electrode and the second electrode facing the inner surface. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment. [Figure 1B] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment. [Figure 1C] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment.

[0010] [Figure 2A] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment. [Figure 2B] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment. [Figure 2C] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment.

[0011] [Figure 3A] 1A-1C and 2A-2C show characteristics of the PPTC heaters according to exemplary embodiments. [Figure 3B] 1A-1C and 2A-2C show characteristics of the PPTC heaters according to exemplary embodiments. [Figure 3C] 1A-1C and 2A-2C show characteristics of the PPTC heaters according to exemplary embodiments.

[0012] [Figure 4A] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment. [Figure 4B] 1 is an equivalent circuit of a PPTC heater according to an example embodiment.

[0013] [Figure 5] FIG. 1 is a diagram of a PPTC heater according to an exemplary embodiment.

[0014] [Figure 6A] FIG. 1 illustrates a PPTC heater according to an exemplary embodiment. [Figure 6B] FIG. 2 illustrates an equivalent circuit of a PPTC heater according to an exemplary embodiment. [Figure 6C] FIG. 1 illustrates a PPTC heater, including an equivalent circuit, according to an exemplary embodiment. [Figure 6D] FIG. 1 illustrates a PPTC heater, including an equivalent circuit, according to an exemplary embodiment.

[0015] [Figure 7A] FIG. 1 is a diagram of an actuator actuated by a PPTC heater according to an exemplary embodiment. [Figure 7B] FIG. 1 is a diagram of an actuator actuated by a PPTC heater according to an exemplary embodiment. [Figure 7C] FIG. 1 is a diagram of an actuator actuated by a PPTC heater according to an exemplary embodiment. [Figure 7D] FIG. 1 is a diagram of an actuator actuated by a PPTC heater according to an exemplary embodiment.

[0016] [Figure 8] 1A-1C are diagrams of heater bodies of any of the disclosed PPTC heaters, according to exemplary embodiments.

[0017] [Figure 9A] 1 is a test circuit associated with testing a PPTC heater, according to an exemplary embodiment. [Figure 9B] 10 is a graph associated with testing of a PPTC heater, according to an example embodiment. [Figure 9C] 10 is a graph associated with testing of a PPTC heater, according to an example embodiment.

[0018] [Figure 10A] 1 is a test circuit associated with testing a PPTC heater, according to an exemplary embodiment. [Figure 10B] 10 is a graph associated with testing of a PPTC heater, according to an example embodiment. [Figure 10C] 10 is a graph associated with testing of a PPTC heater, according to an example embodiment.

[0019] [Figure 11A] 10A-10C illustrate the effect of bending a PPTC heater, according to an exemplary embodiment. [Figure 11B] 10A-10C illustrate the effect of bending a PPTC heater, according to an exemplary embodiment.

[0020] [Figure 12] FIG. 1 illustrates a flow diagram for manufacturing a PPTC heater according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] According to embodiments described herein, a novel heater for temperature-sensitive actuators, such as waste heat recovery systems, is disclosed. The heater is a polymeric positive temperature coefficient (PPTC) device comprised of a conductive filler and a semi-crystalline polymer. The conductive filler may be a carbon / graphene combination, as an example, but PPTC heaters can be made from a variety of conductive fillers. The PPTC heater is strategically designed to have a predetermined self-regulating temperature suitable for any application in which the heater is utilized. The physical characteristics of the PPTC heater, such as gap width and thickness, allow strategic control of current flow.

[0022] 1A-1C are representative drawings and illustrations of a novel PPTC heater 100 for operating an actuator, or PPTC actuator heater 100, according to an exemplary embodiment. FIGS. 1A and 1B show a side view and a top cross-sectional view, respectively, of the PPTC heater 100. The PPTC heater 100 includes a heater body 104 made of a PTC material. The heater body 104 is substantially flat with two opposing surfaces. In an exemplary embodiment, the heater body 104 has a thickness of less than 1 mm. The heater body is further described and illustrated in FIG. 8 below.

[0023] The PPTC heater 100 includes a first electrode 106 and a second electrode 102, both of which are disposed on a first opposing surface of a heater body 104. The electrodes 102 / 106 are conductive layers separated by a gap 116, where the conductive layers are absent and the heater body 104 is exposed. In the side view of FIG. 1A , the gap 116 is horizontally disposed, with the first electrode 106 below the gap 116 and the second electrode 102 above the gap. A first electrical wire 108 is connected to the first electrode 106, while a second electrical wire 110 is connected to the second electrode 102.

[0024] 1B further shows a third electrode 118 disposed on a second, opposing side of the heater body 104, the second side being opposite the first side on which the first and second electrodes 106 and 102 are disposed; the third electrode 118 is not visible in FIG. 1A. The heater body 104 has a thickness 120. Thus, the heater body 104 is sandwiched between the electrodes 102 / 106 on one side and the electrode 118 on the other side, with a gap 116 exposing the heater body between the electrodes 102 and 106.

[0025] FIG. 1C is a diagram of a PPTC heater 100 according to an exemplary embodiment. The PPTC heater 100 is in the shape of a ring suitable for placement around a cylindrical device to be heated. In the exemplary embodiment, the device to be heated is an actuator. An actuator is a device that moves or operates something. An actuator converts an energy source (electrical, hydraulic, or pneumatic) into physical mechanical movement. The actuator can move in a linear or circular (rotational) direction. In the exemplary embodiment, heating the actuator with the PPTC heater 100 actuates the actuator, causing it to move in a linear or rotational direction.

[0026] 1C, electrodes 102 and 106 are disposed on the inner annular surface of PPTC heater 100, while electrode 118 is disposed on the outer surface. The PPTC material of heater body 104 is shown both between electrodes 102 and 106 (as horizontally disposed openings) and along the top edge of the ring. Electrical wires 108 and 110 are disposed on inner electrodes 102 and 106, respectively.

[0027] In an exemplary embodiment, the annular shape of the PPTC heater 100 is wrapped around the thermoelectric element of a cylindrical actuator. Thus, the PPTC heater 100 contacts the thermoelectric element of the actuator, allowing the actuator to rapidly heat up and activate for movement. In this way, the PPTC actuator heater 100 offers advantages in applications for waste heat recovery systems where an actuator activates a piston for linear movement (forward and backward). Furthermore, the annular shape of the PPTC heater 100 is a temperature-limiting feature, as the heater limits heat placement to a precise location (the thermoelectric element of the actuator). Therefore, by limiting heating to the thermoelectric element, the PPTC heater ensures consistent output of linear piston movement.

[0028] In exemplary embodiments, the PPTC actuator heater 100 is thin (less than 1 mm thick) and small (less than 1 cm in diameter). This small size, in some embodiments, allows the PPTC actuator heater 100 to be in direct contact with the thermoelectric element of the actuator, resulting in high thermal efficiency. Thus, the cylindrical PPTC heater 100 can be attached to the area of ​​the actuator to be heated.

[0029] In addition to reducing heat loss, in exemplary embodiments, the design of the PPTC heater 100 is simpler than some conventional PPTC devices, potentially saving manufacturing costs. Currently available conventional PPTC or ceramic PTC (cPTC) devices are typically flat, rectangular, or round in shape and over 1 mm thick. In applications with limited space and / or electrical insulation requirements, these PTC heating elements cannot be placed close to the target area. The placement of conventional PTC devices results in slower heating of the target surface and high heat loss. In one example, using a conventional PTC device to heat a target surface results in the PTC device reaching a surface temperature of approximately 200°C, while the target surface only reaches 100°C, making it highly inefficient.

[0030] Although there are some thin-film PPTC devices with thicknesses of less than 1 mm, the power density of these devices is very low. Therefore, such thin-film PPTC devices must be large enough to generate sufficient heat for a short period of time. In one embodiment, the PPTC heater 100 has a much higher power density than existing thin-film PPTC devices.

[0031] 2A-2C are representative diagrams related to a PPTC heater for operating an actuator, according to an exemplary embodiment. FIGS. 2A and 2B respectively show a side view and a top cross-sectional view of a PPTC heater 200, according to an exemplary embodiment. The PPTC heater 200 includes a heater body 204 made of a PTC material. The heater body 204 is substantially flat, having two opposing surfaces. In an exemplary embodiment, the heater body 204 has a thickness of less than 1 mm. The heater body is further described and illustrated in FIG. 8 below.

[0032] The PPTC heater 200 includes a first electrode 206 and a second electrode 202, both of which are disposed on a first opposing surface of a heater body 204. The electrodes 202 / 206 are conductive layers separated by a gap 216, where the conductive layer is absent and the heater body 204 is exposed. In the side view of FIG. 2A , the gap 216 is vertically oriented, with the first electrode 206 on the left side of the gap and the second electrode 202 on the right side of the gap. A first electrical wire 208 is connected to the first electrode 206, while a second electrical wire 210 is connected to the second electrode 202.

[0033] 2B further shows a third electrode 218 disposed on a second, opposing side of the heater body 204, the second side being opposite the first side on which the first and second electrodes 206 and 202 are disposed; the third electrode 218 is not visible in FIG. 2A. The heater body 204 has a thickness 220. Thus, the heater body 204 is sandwiched between the electrodes 202 / 206 on one side and the electrode 218 on the other side, with a gap 216 exposing the heater body between the electrodes 202 and 206.

[0034] 2C is a diagram of a PPTC heater 200 according to an exemplary embodiment. The PPTC heater 200 is in the shape of a ring suitable for placement around a cylindrical device to be heated. In the exemplary embodiment, the heated device is an actuator. In the exemplary embodiment, heating of the actuator by the PPTC heater 200 actuates the actuator, causing it to move linearly or rotationally.

[0035] 2C, electrodes 202 and 206 are disposed on the inner annular surface of PPTC heater 200, while electrode 218 is disposed on the outer surface. The PPTC material of heater body 204 is shown both between electrodes 202 and 206 (as vertically disposed openings) and along the top edge of the ring. Electrical wires 208 and 210 are disposed on inner electrodes 206 and 202, respectively. PPTC heaters 100 and 200 exhibit the same general power design, with N=1 (where N represents the total number of grooves on both sides of the heater electrodes).

[0036] 3A-3C are representative diagrams illustrating the characteristics of PPTC heaters 100 and 200 according to exemplary embodiments. FIG. 3A shows the equivalent circuit of PPTC heaters 100 (FIGS. 1A-1C) and 200 (FIGS. 2A-2C) according to exemplary embodiments. R0 and R7 represent the resistances of wires 108 / 208 and 110 / 210, respectively (and vice versa), R1 and R6 represent the resistances of electrodes 102 / 202 and 106 / 206, respectively (and vice versa), R3 represents the resistance of electrodes 118 / 218, and R2, R4, and R5 represent the heater body 104 / 204 (PTC material). In the exemplary embodiment, resistance R4 is much larger than resistances R2 or R5.

[0037] Although there is a single heater body 104 / 204 of PTC material, current flow through the heater 100 / 200 can take three possible paths through the PTC material of the heater body 104 / 204, as given by R2, R4, and R5. FIG. 3B illustrates three possible current paths through the heater body that can occur in both PPTC heaters 100 and 200 according to an exemplary embodiment. Arrows 302, 304, and 306 indicate the direction of current flow through the PPTC material. FIG. 3A illustrates two possible paths for current flow. The first current path passes through R0, R1, R2, R3, R5, R6, and R7. Arrows 302 and 304 are therefore sub-paths of the first current path. The second current path passes through R0, R1, R4, R6, and R7. Arrow 306 is therefore part of the second current path.

[0038] At resistor R2 (indicated by arrow 302), current flows through the PPTC material between electrodes 106 / 206 (R1) and 118 / 218 (R3). At resistor R5 (indicated by arrow 304), current flows through the PPTC material between electrodes 118 / 218 (R3) and 102 / 202 (R6). At resistor R4 (indicated by arrow 306), current flows through the PPTC material between electrodes 106 / 206 (R1) and 102 / 202 (R6). Because resistor R4 is significantly larger than resistors R2 or R5, in the exemplary embodiment, the third current flow direction (R4) is less likely to occur than the other current flow directions provided by resistors R2 or R5.

[0039] FIG. 3C is a representative drawing of a circular PPTC heater 100 or 200 according to an exemplary embodiment. FIG. 3C is used to illustrate possible current flow directions through the circular PPTC heaters 100 and 200. The circular ring consists of a central heater body 104 / 204, a third electrode 118 / 218 surrounding the outer surface of the ring, and a first electrode 106 / 206 and a second electrode 102 / 202 disposed on the inner surface of the ring. In the case of the PPTC heater 100, the second electrode 102 is disposed above the first electrode 106 on the inner surface of the ring (see also FIGS. 1A and 1C). In the case of the PPTC heater 200, the first electrode 206 is disposed on one side of the inner surface of the ring, while the second electrode 202 is disposed on the other side of the inner surface of the ring (see also FIGS. 2A and 2C).

[0040] As in FIG. 3B, arrows indicate the possible directions of current flow. Starting at the conductor 108 / 208 (indicated by arrow 308 and resistor R2), current flows from the electrode 106 / 206 across the PPTC material of the heater body 104 / 204 to the electrode 118 / 218 located on the opposite side of the heater body. Current flows along the electrode 118 / 218 (indicated by arrow 310 and resistor R3). Current then flows from the electrode 118 / 218 across the PPTC material of the heater body 104 / 204 to the conductor 110 / 210 (indicated by arrow 312 and resistor R5). Alternatively, current can flow between the electrode 106 / 206 and the electrode 102 / 202, as indicated by arrows 314 and 316 (or vice versa), and also as indicated by resistor R4.

[0041] In various embodiments, the heater body and electrode designs of PPTC heaters 100 and 200 may be such that the value of R4 is much larger than the values ​​of R2 or R5 (FIG. 3A). This situation may be achieved in PPTC heater 100 (FIGS. 1A and 1B) and PPTC heater 200 (FIGS. 2A and 2B) by configuring the thickness 120 / 220 of heater body 104 to be relatively smaller than the gap 116 / 216. In exemplary embodiments, the thickness 120 (FIG. 1B) of the heater body 104 or the thickness 220 (FIG. 2B) of the heater body 204 is between 3 mils (0.076 mm) and 120 mils (3.0 mm) in various non-limiting embodiments, and between 5 mils (0.13 mm) and 10 mils (0.25 mm) in some embodiments, while the value of either the horizontally disposed gap 116 (FIG. 1A) between the electrodes 102 and 106 or the vertically disposed gap 216 (FIG. 2A) between the electrodes 202 and 206 is relatively larger than the thickness 116 / 216 of the respective heater body 104 / 204. For example, if the thickness 120 of the heater body 104 is 10 mils (0.25 mm), the value of the gap 116 or 216 can be 50 mils (1.3 mm) or greater, ensuring that R4 is much larger than R2 or R5.

[0042] In an exemplary embodiment, the resistance of the PPTC heaters 100 and 200, as represented by the equivalent circuit (FIG. 3A), is approximately the initial resistance multiplied by 4 (R≈4R when R=R and the heater is in an untripped state). i ). According to variations of these embodiments, the design of the groove (gap 116 or gap 216) position can determine the heating effect (higher on one side; lower on the other side by controlling the resistance of each PPTC segment) at the top and bottom (PPTC heater 100) or left and right sides (PPTC heater 200). In one embodiment, the design of PPTC heater 100 has better mechanical strength than PPTC heater 200 in the example where the entire heater is bent into a ring shape.

[0043] FIG. 4A features a side view of a PPTC heater 400 according to an exemplary embodiment. Similar to the previous embodiment, the design of the PPTC heater 400 also features two electrodes connected to external wires located on the same side of the device. Electrode 406 is connected to wire 408, and electrode 402 is connected to wire 410. Electrode 402 is separated from electrode 406 by grooves 420 and 412, where the conductive layer is absent and the heater body 404 of PPTC material is exposed. Additionally, a conductive region 422 is located between grooves 412 and 420, where material, such as the material of electrodes 402 and 406, is present. Thus, grooves 420 and 412 define an area along the surface of the PPTC heater 400 that is relatively high resistance compared to the resistance of the material of electrodes 402, 406 and conductive region 422. 4A, grooves 412, 420 are arranged to extend perpendicular to the general direction of wires 408 and 410. In addition to electrodes 402, 406 and conductive region 422, PPTC heater 400 includes conductive region 414 and conductive region 418, each disposed on opposite sides of heater body 404 and separated by groove 416. Grooves 416 are shown in a lighter shade because they are on opposite sides of the heater body.

[0044] Therefore, the PPTC heater 400 can be characterized by the equivalent circuit shown in FIG. 4B, where R and R 12 represents the resistance of the wires 408, 410, and R1, R3, R6, R8, R 11 represents the resistance of the electrode, and R2, R5, R7, and R 10 represents the resistance of the heater body 404 to current flowing through the thickness of the heater body 404 (i.e., perpendicular to both the wires 408, 410 and the grooves 412, 416, and 420, or in the Z direction), and R4, R9, and R 13 represents the resistance of the heater body 404 to current flowing along the surface of the heater body 404 (i.e., parallel to the wires 408, 410 but perpendicular to the grooves 412, 416, and 420, or in the Y direction). In particular, during operation below the trip temperature, current in the PPTC heater 400 flows primarily through the wires 408 (R0), through the electrode 406 (R1), through the thickness of the heater body 404 (R2) (in the Z direction); along the surface of the conductive region 414 (R3) along the backside of the heater body; back in the Z direction through the thickness of the heater body 404 (R5); back to the front of the device; along the surface of the conductive region 422 (R6); through the thickness of the heater body 404 (R7) in the Z direction to the backside of the device; along the surface of the conductive region 418 (R8); and back to the front of the device through the heater body 404 (R9). 10 ) through the thickness in the Z direction; 11 ) and wire 410(R 12 ) between wire 408 and wire 410. In other words, during operation below the trip temperature, current does not jump up in the Y direction across grooves 412 or 420 on the front side of the device or across groove 416 on the back side of the device. In general, the size of grooves 416, 412, 420 (gaps) can be much larger than the thickness of heater body 404, so current typically flows through resistors R4, R9, R 13 As shown by , it does not flow along a path in the plane of the heater body (in the Y direction).

[0045] Figure 5 features a side view of a PPTC heater 500 according to an exemplary embodiment. In Figure 5, the heater configuration is generally the same as that of PPTC heater 400 (Figure 4A), except that a pair of grooves 520, 512 are arranged to extend generally parallel to the general direction of electrical wire 508 and electrical wire 510. Specifically, electrode 502 is connected to electrical wire 508, and electrode 506 is connected to electrical wire 510. Electrode 502 is separated from electrode 506 by grooves 512 and 520, which are devoid of a conductive layer and expose heater body 504. Additionally, a conductive region 522 is disposed between grooves 512 and 520, where material, such as that of electrodes 502 and 506, is present. Thus, grooves 512, 520 define areas along the surface of PPTC heater 500 that are relatively high resistance compared to the resistance of the materials of electrodes 502, 506 and conductive region 522. In addition to electrodes 502, 506 and conductive region 522, PPTC heater 500 includes conductive region 514 and conductive region 518 disposed on opposite sides of heater body 504 and separated by groove 516. Groove 516 is shown in a lighter shade because it is on opposite sides of the heater body.

[0046] Similar to PPTC heater 400 (FIG. 4A), PPTC heater 500 can be characterized by the equivalent circuit of FIG. 4B, where R and R 12 represents the resistance of the wires 508 and 510, and R1, R3, R6, R8, R 11 represents the resistance of the electrodes, R2, R5, R7, and R 10 represents the resistance of the heater body 504 to current flowing through the thickness of the heater body 504 (i.e., perpendicular to both the wires 508, 510 and the grooves 512, 516, and 520, or in the Z direction), and R4, R9, and R 13represents the resistance of the heater body 504 to current flowing along the surface of the heater body 504 (i.e., perpendicular to both the wires 508, 510 and the grooves 512, 516, and 520, or in the X direction). In particular, during operation below the trip temperature, current in the PPTC heater 500 flows primarily through the wires 510 (R0), through the electrode 502 (R1), and through the thickness of the heater body 504 in the Z direction to the back of the device (R2); along the surface of the conductive region 514 (R3), through the thickness of the heater body 504 (R5), back along the surface of the conductive region 522 (R6) in the Z direction to the front of the device; through the thickness of the heater body 504 (R7); along the surface of the conductive region 518 (R8); and again towards the front of the device through the heater body 504 (R 10 ) through the thickness of the electrode 506 and the wire 510 (R 12 ) between the wires 508 and 510. In general, the size of the grooves 516, 512, 520 (gaps) can be much larger than the thickness of the heater body 504, so that the current flows through the resistors R4, R9, R 13 As shown by , it cannot flow along a path in the plane of the heater body.

[0047] In summary, the configurations of PPTC heaters 400 and 500 provide the same power design (N=3). The resistance of a given heater resistor is approximately the initial resistance multiplied by 16 (R2=R5=R7=R 10 , when the PPTC heater is not tripped, R ≒ 16R i ).

[0048] 6A-6D are representative drawings related to a PPTC heater 600 according to an example embodiment. FIG. 6A shows a side view of the PPTC heater 600, FIG. 6B shows an equivalent circuit of the PPTC heater 600, FIG. 6C shows a photograph of the PPTC heater 600, and FIG. 6D shows a toroidal PPTC heater 600 such as may be used with an actuator. In FIGS. 6A and 6D, the PPTC heater 600 includes a heater body 604 (not visible in FIG. 6A) sandwiched between a first electrode 602 (shown on the outer surface of the toroidal shape in FIG. 6D) and a second electrode 606 (shown on the inner surface of the toroidal shape in FIG. 6D). A first electrical wire 608 is disposed on the front surface (outside the toroidal shape) of the PPTC heater 600, while a second electrical wire 610 is disposed on the back surface (inside the toroidal shape). In this example, the first electrode 602 is connected to wire 608, while the second electrode 606 is connected to wire 610. Thus, current passes through the thickness of the PPTC heater body in the Z direction. In the equivalent circuit of Figure 6B, R0 and R4 represent the resistances of the wires 608, 610, R1 and R3 represent the resistances of the electrodes 602, 606, and R2 represents the resistance of the heater body 604 to current flowing through its thickness.

[0049] Similar to PPTC heaters 100 and 200, PPTC heaters 400, 500, and 600 may be formed in an annular (ring-like) shape for use in enabling / actuating an actuator. Any of the disclosed PPTC heaters may be positioned such that the heater body of the device is positioned relative to the thermoelectric element of the actuator to cause linear or rotational movement of the actuator in response to heating by the PPTC heater.

[0050] 7A-7D are side views of a PPTC heater 700 according to an example embodiment. The PPTC heater 700 is disposed on an actuator 702. While appearing rectangular in the side views of FIGS. 7A-7D, the PPTC heater 700 is actually annular, as in FIGS. 1C, 2C, 3C, 6C, or 6D, and is disposed on top of the actuator 702 or on a thermal element 704. In one embodiment, the thermal element 704 of the actuator 702 includes a wax-like matrix 706, such as paraffin wax mixed with a metallic material, such that the wax-like matrix is ​​between the PPTC heater 700 and the actuator 702 when the PPTC heater is disposed thereon. The wax-like matrix 706 is present to facilitate control of an on-off valve (not shown) of the actuator 702. Note that, according to various embodiments, the PPTC heater 700 is disposed in the form of a thin annular ring that surrounds the periphery of the thermal element 704 (see, for example, FIG. 1C). Thus, the PPTC heater 700 heats and eventually melts the wax-like matrix 706, which then heats the thermal element 704 to actuate the actuator 702, which then moves the actuator in a linear or rotational direction. When the PPTC heater 700 cools, the melted wax-like matrix 706 re-solidifies, protecting the actuator.

[0051] A general view of actuator 702A with a waxy matrix 706 is shown in FIG. 7A; a general view of squeeze-push actuator 702B with a waxy matrix 706 is shown in FIG. 7B; a general view of diaphragm actuator 702C with a waxy matrix 706 is shown in FIG. 7C; and a general view of plunger-piston actuator 702D with a waxy matrix 706 is shown in FIG. 7D (collectively "actuators 702"). In an exemplary embodiment, the waxy matrix 706 is a key element of thermoactuator function because, when heated, it switches the actuator on or off. The heated waxy matrix 706 compresses the elastomeric bag 708 (FIG. 7B) or membrane 712 (FIG. 7C) of actuator 702, causing piston 710 to move. Alternatively, the heated waxy matrix compresses and moves piston 710. In an exemplary embodiment, since the thermoelectric elements of the actuator 702 generally consist of metal particles in a wax-like matrix, the PPTC heater 700 is insulated with parylene by chemical vapor deposition (CVD) or other coating to avoid short circuits.

[0052] In the exemplary embodiment, the PPTC heater 700, like any of the other PPTC heaters 100, 200, 400, 500, and 600, is a self-regulating heater, with the self-regulating temperature depending on the particular application. In the exemplary embodiment, the PPTC heater 700 has a self-regulating temperature of approximately 125°C. The self-regulating temperature is therefore the upper temperature limit for the PPTC heater. Thus, the temperature of the PPTC heater 700 can rise to, but not exceed, approximately 125°C, and if the temperature is higher than 125°C, its heating power is reduced to prevent overheating of the actuator. Thus, when the PPTC heater is combined with an actuator, as in FIGS. 7A-7D , when the temperature of the PPTC heater rises to approximately 125°C, the associated wax in the actuator completely melts, causing the actuator valve to move, after which the temperature of the PPTC heater will not exceed 125°C.

[0053] FIG. 8 is a side view of a heater body of a PPTC heater according to an exemplary embodiment. Recall that the PPTC heaters disclosed herein include a heater body made of a PPTC material (see, e.g., heater body 104 in FIGS. 1A-1C ), where the PPTC material comprises 1) a conductive filler (such as carbon and / or graphene) and 2) a polymer matrix made of a semi-crystalline polymer. As shown in FIG. 8 , heater body 804 comprises a PPTC polymer matrix 802 made of a conductive filler 806 disposed within a polymer 808, with the polymer matrix sandwiched between two metal foils 810. In the exemplary embodiment, each metal foil 810 includes a grain structure (protrusions) on one side in contact with PPTC polymer matrix 802, which strengthens the bond between the foil and the matrix.

[0054] The heater body 804 can be manufactured so that the PPTC heater including the heater body has a predetermined self-regulating temperature. In an exemplary embodiment, the self-regulating temperature is 125° C., but the PPTC heater, specifically the heater body including the polymer matrix made of conductive fillers and polymers, can be designed to meet a wide range of customer temperature preferences. Specifically, the types of conductive fillers and polymers, as well as the proportions of each combination, can be adjusted to achieve a specific self-regulating temperature profile. Thus, there are many different materials that can be used to construct both the conductive filler 806 and the polymer 808 of the PPTC polymer matrix 802.

[0055] In an exemplary embodiment, the polymer 808 comprises a semi-crystalline polymer, such as polyethylene, polyvinylidene fluoride, ethylene tetrafluoroethylene, ethylene vinyl acetate, ethylene and acrylic acid copolymer, ethylene butyl acrylate copolymer, polyperfluoroalkoxy, or some combination of one or more of these materials. Furthermore, in an exemplary embodiment, the volume percentage of polymer 808 relative to conductive filler 806 within the PPTC polymer matrix 802 is between 50% and 99%, preferably between 60% and 95%. Thus, for example, at one end of the spectrum, the polymer matrix may be comprised of 50% polymer and 50% conductive filler. At the other end of the spectrum, the polymer matrix may be comprised of 99% polymer and 1% conductive filler. Preferably, the polymer matrix may be comprised of 60% polymer and 40% conductive filler at one end and 95% polymer and 5% conductive filler at the other end; between these preferences, there are many other combinations that may result in a desirable self-regulating temperature profile.

[0056] In an exemplary embodiment, the conductive filler 806 of the polymer matrix is ​​comprised of carbon, graphene, carbon and graphene, conductive ceramic, carbon nanotubes, carbon with carbon nanotubes, or graphene with carbon nanotubes. In an exemplary embodiment, the conductive filler 806 of the PPTC polymer matrix 802 has a primary particle size between 10 nm and 100 nm and a particle size of 5 cm. 3 / 100g and 500cm 3 / 100g. Preferably, the DBP value is 8cm or less. 3 / 100g and 200cm 3 / 100g. Further, in exemplary embodiments, the carbon loading is between 20% and 65%, preferably between 25% and 30%.

[0057] In an exemplary embodiment, the conductive filler 806 of the PPTC polymer matrix 802 is composed of graphene, which is prepared by mechanical or chemical methods, and the number of graphene layers ranges from one to several hundred, preferably between one and 30 layers. In an exemplary embodiment, the thickness of each graphene layer is less than 20 nm, preferably between 0.34 nm and 10.2 nm. Furthermore, in an exemplary embodiment, the graphene particle size ranges between 0.1 μm and 100 μm, preferably between 5 μm and 30 μm. The graphene loading is between 1% and 50%, preferably between 4% and 30%.

[0058] In an exemplary embodiment, the conductive filler 806 of the PPTC polymer matrix 802 is composed of carbon or a conductive ceramic, the primary particle size of the carbon being between 10 nm and 100 nm, and the thickness of the conductive filler is 5 cm. 3 / 100g and 500cm 3 DBP value between / 100g, preferably 8cm 3 / 100g and 200cm 3 The DBP values ​​range between 0% / 100% (carbon / no conductive ceramic, 100% graphene) and 100% / 0% (100% carbon or conductive ceramic, no graphene), or any value therebetween. In preferred embodiments, the ratio of carbon or conductive ceramic to graphene is between 1% and 90%, preferably between 30% and 60%.

[0059] In an exemplary embodiment, the conductive filler 806 of the PPTC polymer matrix 802 is composed of carbon nanotubes (CNTs) or graphene containing carbon, the primary particle size of the carbon being between 10 nm and 100 nm, and the thickness of the conductive filler 806 is 5 cm. 3 / 100g and 500cm 3 DBP value between / 100g, preferably 8cm 3 / 100g and 200cm 3 / 100g. In an exemplary embodiment, the nanotubes of the conductive filler 806 have a length between 10 nm and 10 μm, a diameter between 2 nm and 50 nm, and a length / diameter of the CNTs between 5 and 5000, preferably between 100 and 1000. In an exemplary embodiment, the carbon to graphene or carbon to nanotube ratio is between 1% and 90%, preferably between 30% and 60%.

[0060] Additionally, in exemplary embodiments, either the polymer 808 or the conductive filler 806 of the PPTC polymer matrix 802, or both, are supplemented with materials including, but not limited to, antioxidants, dispersants, coupling agents, cross-linking agents, arc suppressants, etc. Thus, the heater body 804 may be manufactured using a wide variety of materials, and the heater body of FIG. 8 may be part of any of the PPTC heaters disclosed and described herein.

[0061] 9A-9C and 10A-10C provide two test examples using a toroidal PPTC heater, such as the PPTC heater 100 of FIGS. 1A-1C, according to an exemplary embodiment. The first test example (FIGS. 9A-9C) tests a PPTC heater with a horizontal gap between the two internal electrodes, such as those of FIGS. 1A-1C, while the second test example (FIGS. 10A-10C) tests a PPTC heater with a vertical gap between the two internal electrodes, such as those of FIGS. 2A-2C.

[0062] 9A shows the test circuit with 12V supplied to the circuit, a maximum current of 20A, and a chamber temperature of -40°C. Both the current and voltage are measured across the PPTC heater. Additionally, the PPTC heater is determined to have an initial resistance of 0.38 Ω, a height of the PPTC heater of 9.7 mm (e.g., electrode 106 + gap 116 + electrode 102 in FIG. 1A), a thickness of the PPTC heater of 0.55 mm (e.g., electrode 102 + thickness 120 + electrode 118 in FIG. 1B), a diameter of the toroidal PPTC heater of 9.5 mm with a gap of approximately 0.4 mm (e.g., referring to FIG. 1C, the space between wires 108 and 110 is the gap), and an area of ​​the PPTC heater (i.e., the area of ​​the circle formed by the toroidal PPTC heater) of 2.5 cm 2 Furthermore, the PPTC heater has two horizontal electrodes on its inner surface (e.g., electrodes 102 and 106 in FIG. 1C) and one full-size electrode on its outer surface (e.g., electrode 118 in FIG. 1C).

[0063] Figure 9B is a graph plotting the temperature (°C) of the PPTC heater versus time (minutes). The temperature starts at the chamber temperature of -40°C and is very rapidly increased to approximately 120°C. This temperature of 120°C is maintained for the duration of the test (100 minutes). Figure 9C is a graph plotting the resistance (Ω) of the PPTC heater versus temperature (°C). As the temperature increases, the resistance of the PPTC heater remains very low, but then, after the temperature reaches approximately 100°C, there is some increase in resistance, and once the temperature reaches approximately 125°C, the resistance increases very rapidly. Furthermore, the temperature does not increase significantly above 125°C, indicating that the PPTC heater is self-regulating at approximately 125°C.

[0064] 10A-10C feature a second test example of a PPTC heater according to an exemplary embodiment. FIG. 10A shows the test circuit with 12V supplied to the circuit, a maximum current of 20A, and a chamber temperature of -40°C. Both the current and voltage are measured across the PPTC heater. Additionally, the PPTC heater has an initial resistance of 2.27 Ω; the height of the PPTC heater is 8.6 cm (e.g., electrode 206 + gap 216 + electrode 202 in FIG. 2A); the thickness of the PPTC heater is 0.34 mm (e.g., electrode 202 + thickness 220 + electrode 218 in FIG. 2B); the diameter of the toroidal PPTC heater is 1.2 cm, with a gap of approximately 0.4 mm (see, e.g., FIG. 2C); and the area of ​​the PPTC heater is 2.5 cm. 2 Furthermore, the PPTC heater has two vertical electrodes on its inner surface (e.g., electrodes 202 and 206 in FIG. 2C) and one full-size electrode on its outer surface (e.g., electrode 218 in FIG. 2C).

[0065] FIG. 10B is a graph plotting the temperature (°C) of the PPTC heater versus time (minutes). The temperature starts at a chamber temperature of -40°C and is very rapidly increased to approximately 120°C. This temperature of 120°C is maintained for the duration of the test (100 minutes). FIG. 10C is a graph plotting the resistance (Ω) of the PPTC heater versus temperature (°C). As the temperature increases, the resistance of the PPTC heater remains very low (even lower than in Example 1, FIG. 9C), but then, after the temperature reaches approximately 125°C, the resistance increases very rapidly. Furthermore, the temperature does not increase significantly above 125°C, indicating that the PPTC heater is self-regulating at approximately 125°C.

[0066] 11A and 11B are representative diagrams illustrating the effect of a bending process on the PPTC material of a PPTC heater, such as any of the PPTC heaters disclosed herein, specifically a heater body including a PPTC polymer matrix, according to an exemplary embodiment. Recall from FIG. 8 that the heater body 804 of any of the PPTC heaters illustrated and described herein is comprised of a PPTC polymer matrix 802. The PPTC polymer matrix 802 is comprised of both a conductive material (filler) 806 and a polymer 808, with the PPTC polymer matrix sandwiched between two sheets of metal foil 810. Similarly, in FIG. 11A, the heater body 1104 of the PPTC heater (PPTC heater body 1104) is comprised of a PPTC polymer matrix 1102 with metal foil 1110 disposed on either side of the polymer matrix. Because the PPTC heaters disclosed herein are bent into a circular shape, such as for use with an actuator or other cylindrical device, they are subject to a novel bending process not characteristic of conventional PPTC devices.

[0067] In an exemplary embodiment, based on its material composition, the PPTC polymer matrix 1102 can bend in the elastic-plastic range, i.e., with very little plastic deformation, as if both elastic and plastic deformation were occurring. The imaginary neutral line 1120 indicates that the PPTC polymer matrix 1102 can bend significantly. Recall that the metal foil 1110 may include a particulate structure disposed on the side adjacent to the PPTC polymer matrix 1102 to improve bonding between the two contacting surfaces. In some embodiments, the elastic modulus of the metal foil 1110 is high enough to move within the elastic range during bending. Nevertheless, this bending creates tension in the outer half of the metal foil 1110 and PPTC polymer matrix 1102, while simultaneously creating compression in the inner half of the metal foil and PPTC polymer matrix 1102. Furthermore, there is an imaginary neutral line 1120 between one half of the PPTC polymer matrix 1102 and the other half of the PTC polymer matrix 1102.

[0068] Heating the PPTC heater during bending is not required. In one embodiment, some heat is applied to the PPTC heater during bending. However, the heating temperature is maintained below the melting temperature of the semi-crystalline polymer. Otherwise, the properties of the conductive particles in the PPTC polymer matrix may change, disrupting the manufacturing process of the PPTC heater. Once the heater body 1104 has achieved the desired circular shape after bending, an annealing process may be used to release the bending stress.

[0069] 11B is a diagram illustrating the stress and tension characteristics of the PPTC heater body 1104 of FIG. 11A, according to an exemplary embodiment. The stress given by σ is the stress of the outer metal foil 1110 (σ foil ) and PPTC polymer matrix 1102 (σ pPTC The elastic modulus given by E is shown for both the outer metal foil 1110 (E foil ) and PPTC polymer matrix 1102 (E pPTC ) is also given. From this information, the tension ε for each material can be calculated using the formula σ=Eε.

[0070] FIG. 12 is a flow diagram illustrating process steps for manufacturing a PPTC heater, such as any one of PPTC heaters 100, 200, 400, 500, and 600, according to an exemplary embodiment. The manufacturing process begins with mixing a polymer and a conductive filler to form the polymer matrix (block 1202). The polymer matrix is ​​then subjected to a hot melt extrusion process (block 1204). Hot melt extrusion (HME) is a process in which heat and pressure are applied to melt the polymer and force it through an aperture in a continuous process, allowing the polymer matrix to assume a predetermined uniform shape and density. The polymer matrix is ​​then extruded into a sheet (block 1206). Metal foil is then laminated on both sides of the extruded sheet of polymer matrix (block 1208), forming a sandwich of metal foil (electrodes) with a polymer matrix, as described for the previous PPTC heaters.

[0071] Following lamination of the metal foil, a PPTC crosslinking operation is performed on the polymer matrix (block 1210). In polymer chemistry, crosslinking is used to promote changes in the physical properties of a polymer. Here, the polymer matrix is ​​crosslinked, resulting in the appearance of a PPTC with desired properties. In an exemplary embodiment, the PPTC crosslinking is achieved by electron beam irradiation, gamma irradiation, or chemical crosslinking. A foil-PPTC-foil sandwich sheet is then formed (block 1212). The sandwich sheet is then etched on one side (if N=1) or both sides (if N=3) to the designed chip size (block 1214). The sandwich sheet is then cut into individual chips based on the etching (block 1216), each of which is a sandwich of metal foil-PPTC-metal foil, as desired for a PPTC heater.

[0072] Each individual chip is then bent to form a ring shape of a specified diameter (block 1218). While the embodiments described herein are ring-shaped to fit a cylindrical actuator, the individual chips may instead be bent into other shapes suitable for the desired application. For example, the chips may be bent to form a rectangular shape to couple with an actuator or other device shaped like a cube or rectangular prism. Or, the chips may be bent into another geometric shape suitable for coupling with an actuator that is triangular, pyramidal, prismatic, trapezoidal, hexagonal, octagonal, pentagonal, or any of a variety of other geometric shapes. Or, the chips may be bent into a rectangular shape suitable for coupling with an actuator or other device having a non-geometric shape. In an exemplary embodiment, the shape of the PPTC heater is bent at this stage to fit the shape of the device to be heated.

[0073] After bending the chips into the desired shape, wire assembly is performed to attach wires (e.g., wires 108 and 110 in FIG. 1A) to the sandwiched chips (block 1220). An annealing process is then performed in which the sandwiched chips are heated and allowed to cool slowly to remove internal stresses and strengthen the material. The sandwiched chips are then coated with a suitable material (block 1222) to protect the device or add other functionality to the device. For example, in one embodiment, a temperature-sensitive coating is added that changes the color of the device at different temperatures. R testing of the device is then performed (block 1226), and the device is packaged in appropriate packaging material (block 1228). This completes the manufacturing process of the PPTC heater.

[0074] 12 may be performed in an order other than that shown, for example, the operation of block 1224 may be performed before the operation of block 1218. Those skilled in the art will recognize several ways in which these manufacturing operations may be performed.

[0075] As used herein, elements or steps described in the singular and preceded by the word "a" or "an" should be understood as not excluding a plurality of elements or steps, unless such exclusion is expressly stated. 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.

[0076] While the present disclosure refers to particular embodiments, many modifications, alterations, and variations to the described embodiments are possible without departing from the sphere and scope of the disclosure, as defined in the appended claims. Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but rather have the full scope defined by the language of the following claims and equivalents thereof. (Other possible items) [Item 1] A polymeric positive temperature coefficient (PPTC) heater, comprising: a first electrode coupled to the first wire; a heater body having a PPTC polymer matrix, the PPTC polymer matrix including a conductive filler and a semi-crystalline polymer; a second electrode coupled to a second wire; the PPTC polymer matrix disposed between the first electrode and the second electrode to form a sandwich; and the heater body disposed in a circular ring shape. PPTC heater equipped with [Item 2] 2. The PPTC heater of claim 1, wherein a bending process is used to form the sandwich into the annular shape. [Item 3] 3. The PPTC heater according to claim 1, wherein the first electric wire is on an inner surface of the annular ring, and the second electric wire is on an outer surface of the annular ring. [Item 4] 4. The PPTC heater according to claim 1, wherein the PPTC polymer matrix further comprises a conductive filler and a semi-crystalline polymer. [Item 5] 3. The PPTC heater of claim 1, further comprising a third electrode, wherein the first electrode and the third electrode are on the inner surface of the annular ring, and the second electrode is on the outer surface of the annular ring. [Item 6] The PPTC heater of claim 5 , wherein the first wire and the second wire are on the inner surface of the annular shape. [Item 7] 7. The PPTC heater of claim 6, wherein the first electrode and the third electrode are separated by a gap of a first predetermined thickness, the gap exposing the PPTC polymer matrix of the heater body. [Item 8] 8. The PPTC heater of claim 7, wherein the heater body has a second predetermined thickness measured between the first electrode and the third electrode. [Item 9] 9. The PPTC heater of claim 8, wherein the second predetermined thickness is much thinner than the first predetermined thickness. [Item 10] 10. The PPTC heater of claim 8 or 9, wherein the second predetermined thickness is between 3 mils (0.076 mm) and 120 mils (3.0 mm). [Item 11] 11. The PPTC heater according to claim 1, wherein the conductive filler is selected from the group consisting of carbon, graphene, carbon and graphene, conductive ceramic, carbon nanotubes, carbon with carbon nanotubes, and graphene with carbon nanotubes. [Item 12] 12. The PPTC heater according to claim 1, wherein the semi-crystalline polymer is selected from the group consisting of polyethylene, polyvinylidene fluoride, ethylene tetrafluoroethylene, ethylene vinyl acetate, ethylene and acrylic acid copolymer, ethylene butyl acrylate copolymer, and polyperfluoroalkoxy. [Item 13] A polymeric positive temperature coefficient (PPTC) heater, comprising: a heater body having a conductive filler and a semi-crystalline polymer, said heater body configured into a rectangular sheet of a predetermined thickness; a first electrode disposed on a first side of the heater body at a first end, wherein the first electrode is coupled to a first wire; a second electrode disposed on the first side of the heater body at a second end, wherein the second electrode is coupled to a second wire; and a gap disposed between the first electrode and the second electrode, the gap being horizontal to the first wire and the second wire, the gap having a second predetermined thickness, wherein the gap exposes the heater body between the first electrode and the second electrode. The PPTC heater is formed in a circular ring shape, and the first electrode and the second electrode are disposed on an inner surface of the PPTC heater. [Item 14] 14. The PPTC heater of claim 13, further comprising a third electrode disposed on a second side of the heater body, the second side being opposite the first side. [Item 15] 15. The PPTC heater according to claim 13 or 14, wherein the predetermined thickness is much thinner than the second predetermined thickness. [Item 16] 16. The PPTC heater according to any one of claims 13 to 15, wherein the heater body has an automatic temperature control of 125°C. [Item 17] A polymeric positive temperature coefficient (PPTC) heater, comprising: a heater body having a polymer matrix, said heater body configured into a rectangular sheet of a predetermined thickness; a first electrode disposed on a first side of the heater body at a first end, wherein the first electrode is coupled to a first wire; a second electrode disposed on the first side of the heater body at a second end, wherein the second electrode is coupled to a second wire; and a gap disposed between the first electrode and the second electrode, the gap being perpendicular to the first wire and the second wire, the gap having a second predetermined thickness, wherein the gap exposes the heater body between the first electrode and the second electrode. The PPTC heater is formed in a circular ring shape, and the first electrode and the second electrode are disposed on an inner surface of the PPTC heater. [Item 18] 18. The PPTC heater of claim 17, further comprising a third electrode disposed on a second side of the heater body, the second side being opposite the first side. [Item 19] 19. The PPTC heater of claim 17 or 18, wherein the predetermined thickness is 10 mils (0.25 millimeters) and the second predetermined thickness is 50 mils (1.3 millimeters). [Item 20] 20. The PPTC heater according to any one of claims 17 to 19, wherein the heater body has an automatic temperature control of 125°C.

Claims

1. 1. A polymeric positive temperature coefficient (PPTC) heater, comprising: a heater body having a PPTC polymer matrix, wherein the PPTC polymer matrix includes a conductive filler and a semi-crystalline polymer; a first electrode disposed on a first surface of the heater body and coupled to a first wire; a second electrode disposed on a second surface of the heater body opposite the first surface and coupled to a second wire, wherein the heater body has a first thickness measured between the first electrode and the second electrode; and a third electrode disposed on the first surface of the heater body and spaced apart from the first electrode to define a gap therebetween, the gap having a second thickness greater than the first thickness; Equipped with the heater body, the first electrode, the second electrode, and the third electrode are arranged in a ring shape; the first surface is an inner surface of the annular shape, The second surface is the outer surface of the annular shape. PPTC heater.

2. 2. The PPTC heater of claim 1, wherein a bending process is used to form the heater body, the first electrode, the second electrode, and the third electrode into the annular shape.

3. 3. The PPTC heater according to claim 1, wherein the first electric wire is on the inner surface of the annular shape, and the second electric wire is on the outer surface of the annular shape.

4. The PPTC heater according to claim 1 , wherein the gap exposes the PPTC polymer matrix of the heater body.

5. 10. The PPTC heater of claim 1, wherein the second thickness is between 3 mils (0.076 mm) and 120 mils (3.0 mm).

6. 6. The PPTC heater according to claim 1, wherein the conductive filler is selected from the group consisting of carbon, graphene, carbon and graphene, conductive ceramic, carbon nanotubes, carbon with carbon nanotubes, and graphene with carbon nanotubes.

7. 7. The PPTC heater according to claim 1, wherein the semi-crystalline polymer is selected from the group consisting of polyethylene, polyvinylidene fluoride, ethylene tetrafluoroethylene, ethylene vinyl acetate, ethylene and acrylic acid copolymer, ethylene butyl acrylate copolymer, and polyperfluoroalkoxy.

8. 1. A polymeric positive temperature coefficient (PPTC) heater, comprising: a heater body having a conductive filler and a semi-crystalline polymer, wherein the heater body is configured into a rectangular sheet of a first thickness; a first electrode disposed on a first side of the heater body, wherein the first electrode is coupled to a first electrical wire; a second electrode disposed on the first side of the heater body and spaced apart from the first electrode to define a gap therebetween, the gap exposing the heater body and having a second thickness greater than the first thickness, the second electrode coupled to a second wire, the gap extending in a direction parallel to the first wire and the second wire; and a third electrode disposed on a second side of the heater body opposite the first side; Equipped with the heater body, the first electrode, the second electrode, and the third electrode are formed in an annular shape; the first electrode and the second electrode are disposed on an inner surface of the annular shape; PPTC heater.

9. 9. The PPTC heater of claim 8, wherein the heater body has a self-regulating temperature of 125°C.

10. 1. A polymeric positive temperature coefficient (PPTC) heater, comprising: a heater body having a polymer matrix, the heater body configured into a rectangular sheet having a first thickness; a first electrode disposed on a first side of the heater body, wherein the first electrode is coupled to a first electrical wire; a second electrode disposed on the first side of the heater body and spaced apart from the first electrode to define a gap therebetween, the gap exposing the heater body and having a second thickness greater than the first thickness, the second electrode coupled to a second wire, the gap extending in a direction parallel to the first wire and the second wire; and a third electrode disposed on a second side of the heater body opposite the first side; Equipped with the heater body, the first electrode, the second electrode, and the third electrode are formed in an annular shape; the first electrode and the second electrode are disposed on an inner surface of the annular shape; PPTC heater.

11. 11. The PPTC heater of claim 10, wherein the first thickness is 10 mils (0.25 millimeters) and the second thickness is 50 mils (1.3 millimeters).

12. 12. The PPTC heater according to claim 10, wherein the heater body has an automatic temperature control of 125°C.

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