Integrated multi-PTC heating hair curler

Abstract

The utility model belongs to the field of beauty and hairdressing product technology, specifically speaking is a kind of integrated multiple PTC heating hair curler, including a cylindrical heating tube and the heating and temperature control system in its inside;The heating tube is made of high thermal conductivity aluminum material, and its outer cylindrical surface constitutes the working surface directly contacted with user's hair;In the cross section of the heating tube, four PTC heating elements are evenly arranged along the circumferential direction, the circumferential angle between the center lines of each PTC element is 90 °, and the four-quadrant heat source layout is formed in orthogonal symmetry distribution. The heat conduction distance from any point on the surface of the heating tube to the nearest heat source can be greatly shortened, and the temperature difference caused by uneven heat diffusion can be significantly reduced. Each PTC is equipped with an independent temperature control circuit to achieve accurate heat compensation on demand and avoid energy redundancy and local overheating caused by overall heating.

Description

Technical Field

[0001] This utility model belongs to the field of beauty and hair care product technology, specifically an integrated multi-PTC heating curling iron. Background Technology

[0002] In the field of beauty and hair care products, curling irons are an important tool for daily styling. Their core performance largely depends on the stability and uniformity of the heating system. Currently, most curling irons on the market adopt a dual PTC (positive temperature coefficient thermistor) heating structure, which usually arranges two PTC elements in a 180° symmetrical manner inside the heating tube. This structure has significant drawbacks in practical use: due to the limited number and concentrated distribution of PTCs, the heat transfer on the surface of the heating element is uneven, the area far from the PTC heats up slowly and dissipates heat quickly, resulting in insufficient thermal compensation.

[0003] During operation, the temperature of the entire tube fluctuates greatly, making it difficult to maintain a constant set value. Especially when in contact with wet hair or during continuous operation, the temperature drops significantly, requiring repeated heating to restore the styling effect. This temperature instability and uneven heat distribution not only affect the uniformity of hair softening by heat, reducing the curl setting effect and durability, but also aggravate hair damage due to local overheating or repeated pulling. Furthermore, existing dual-PTC solutions have limitations in temperature control accuracy and response speed, and cannot achieve dynamic zone adjustment, making it difficult to meet users' needs for efficient, gentle, and stable temperature control. Therefore, an integrated multi-PTC heating curling iron is proposed to address the above problems. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology and solve at least one of the technical problems mentioned in the background technology, this utility model proposes an integrated multi-PTC heating curling iron.

[0005] The technical solution adopted by this utility model to solve its technical problem is as follows: The integrated multi-PTC heating curling iron of this utility model includes a cylindrical heating tube and a heating and temperature control system disposed inside it; the heating tube is made of aluminum material with high thermal conductivity, and its outer cylindrical surface forms a working surface that directly contacts the user's hair. Within the cross-section of the heating element, four PTC heating elements are evenly arranged circumferentially, with a circumferential angle of 90° between the centerlines of each PTC element, forming a four-quadrant heat source layout. Each PTC heating element is bonded to the inner wall of the heating element with thermally conductive grease or adhesive, and a mechanical clamping structure ensures that there are no air gaps between it and the inner wall, maximizing heat conduction efficiency. This four-point surrounding layout ensures that the straight-line distance from any circumferential position of the heating element to the nearest PTC heat source does not exceed one-quarter of the circumference, significantly shortening the heat conduction path, reducing thermal resistance, and thus suppressing surface temperature differences.

[0006] Preferably, each PTC heating element is equipped with an independent temperature sensing unit and an independent driving circuit, forming four physically isolated and logically independent temperature control zones; the temperature sensing unit is an NTC thermistor mounted on the PTC body or adjacent to its installation position, used to detect the local temperature of the corresponding zone in real time; the driving circuit of each zone includes MOSFET switching elements and current limiting protection modules, which are uniformly scheduled by the main control MCU. Preferably, the main control MCU pre-stores the target operating temperature threshold and periodically collects temperature data from four zones, with a sampling period of no more than 100 milliseconds. When the measured temperature of any zone is lower than the set threshold and the duration exceeds a preset judgment window (e.g., 200 milliseconds), the main control MCU starts the drive circuit corresponding to that zone and applies the operating voltage to the PTC for heating. When the temperature of that zone rises back above the set threshold, the power supply to the PTC is immediately cut off. The other three zones maintain their current operating state during this process and do not participate in the linkage control. This zone closed-loop control mechanism enables the system to perform thermal compensation only on the areas where the actual temperature drop occurs, avoiding energy waste and local overheating caused by overall heating.

[0007] Preferably, the four PTC heating elements are electrically connected in parallel, but each parallel branch has an independent power control channel. The main control MCU adjusts the duty cycle of each PTC through four PWM signals to achieve precise control of the heating power of each zone. During the initial startup phase, the four PTCs heat up at full power synchronously, so that the surface of the heating element reaches the target operating temperature of 180℃±5℃ within 25 seconds. After entering steady-state operation, the system switches to zoned dynamic compensation mode: when the user wraps their hair around the heating tube and pulls their hair, the temperature of the contact area drops due to heat conduction to the hair. After the temperature sensor of the corresponding zone detects this change, the main control MCU activates the PTC of that zone in the next control cycle, so that it completes the temperature recovery compensation within 2 seconds, and restores the surface temperature to the set value. This temperature recovery process does not affect the temperature stability of other undisturbed zones, thereby maintaining the surface temperature fluctuation range of the entire tube within ±3℃.

[0008] Specifically, to improve the uniformity of heat conduction, the inner wall of the heating tube is provided with local grooves or flat contact surfaces at the four PTC mounting positions, so that the heating surface of the PTC element forms a surface-to-surface contact with the tube wall rather than a point contact. The external dimensions of each PTC element match the corresponding contact area, and the contact area is not less than 90% of the total area of ​​the PTC bottom surface; In addition, the space between the PTC element and the tube wall is filled with a thermally conductive medium with a thermal conductivity of not less than 3.0 W / (m·K) to further eliminate interfacial thermal resistance; The main types of heat transfer media that can be selected include: Thermal conductive silicone pads / sheets: They have good flexibility and insulation, can closely fit the contact surface between PTC elements and aluminum tube walls, are suitable for slight surface unevenness, have a thermal conductivity of 3.0-12W / (m·K), and can cover the normal operating temperature of hair curlers. They are easy to install and have strong stability, making them a common choice for such small heating devices.

[0009] Thermal grease: It is a paste-like thermally conductive medium with excellent filling properties. It can fully fill the tiny gaps on the contact surface and completely eliminate the thermal resistance caused by air gaps. The thermal conductivity of high-quality thermal grease can reach 3.0-20W / (m·K), which is suitable for scenarios with high requirements for thermal conductivity. It is important to choose high-temperature resistant products to avoid problems such as drying and loss under long-term high temperature.

[0010] Thermally conductive ceramic sheet: a rigid thermally conductive medium with a thermal conductivity generally above 10-30 W / (m·K). It has high thermal conductivity, excellent high temperature resistance, strong chemical stability, and is not prone to aging. It needs to be used in conjunction with a mechanical clamping structure to ensure a tight fit with the PTC element and the tube wall. It is suitable for designs with high requirements for thermal conductivity stability and service life.

[0011] Thermally conductive potting compound: If the installation location of PTC element needs to be sealed and protected, thermally conductive potting compound can be selected. After curing, it can form a tight thermally conductive interface and has functions such as waterproofing, insulation and shock resistance. The thermal conductivity is mostly between 3.0-8W / (m·K), which is suitable for scenarios that require integrated protection and thermal conductivity. Structurally, four PTCs are arranged centrally along the heating element axis, and their effective heating length covers more than 80% of the working area of ​​the heating element, ensuring axial temperature consistency. Meanwhile, heat insulation rings, made of high-temperature resistant plastic or ceramic materials, are provided at both ends of the heating element to block heat conduction to the handle end and ensure user safety.

[0012] Preferably, the main control MCU has built-in temperature anomaly protection logic; Preferably, if any zone fails to recover its temperature three times consecutively within a set time (i.e., the temperature remains below the lower threshold), the system determines it to be in an abnormal heat dissipation state (such as wet hair wrapped around the area or prolonged contact), automatically reduces the maximum allowable heating power of that zone, and triggers a user alert signal. If two or more of the four zones simultaneously exhibit abnormal temperatures, the entire unit enters a low-power standby mode to prevent overheating risks. This protection mechanism works in conjunction with zone temperature control to maintain optimal thermal response performance while ensuring safety.

[0013] The beneficial effects of this utility model are: By evenly distributing four PTCs at 90° around the circumference, the heat conduction distance from any point on the heating element surface to the nearest heat source is significantly shortened, thus significantly reducing the temperature difference caused by uneven heat diffusion. Each PTC is equipped with an independent temperature control circuit to achieve precise heat compensation as needed, avoiding energy redundancy and local overheating caused by overall heating. The high thermal conductivity aluminum tube and optimized interface contact structure ensure efficient heat transfer from the PTC to the working surface; the zoned dynamic control strategy significantly shortens the warm-up time after a single pull-out, which is significantly better than existing dual PTC products. The temperature difference across the entire tube surface is controlled within an extremely low range under steady-state operation, while the temperature difference in traditional structures is significantly greater. These technical features work together to minimize temperature differences across different parts of the hair during curling, resulting in uniform softening and a consistent, long-lasting styling effect. Simultaneously, by avoiding unnecessary high-temperature exposure and repeated heating, protein denaturation and moisture loss are reduced, minimizing hair damage. This structure is suitable for various handheld curling irons, straighteners, and other hair styling equipment, demonstrating clear feasibility and industrialization value. Attached Figure Description

[0014] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and are used to explain the present invention, but do not constitute an undue limitation of the present invention.

[0015] In the attached diagram: Figure 1 This is a schematic diagram of the overall structure of a dual PTC heating curling iron in the prior art; Figure 2 This is a schematic diagram of the internal structure of the heating curling iron of this utility model; Figure 3 This is a schematic diagram of the structure of the PTC heating element of this utility model.

[0016] Legend: 1. Heating element; 2. PTC heating element; 3. Temperature sensing unit; 4. Mounting bracket; 5. Main control MCU. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0018] Specific embodiments are given below. Please refer to [link / reference]. Figures 1-3 This utility model provides an integrated multi-PTC heating curling iron. The core component of the curling iron is a cylindrical heating tube 1, which is made of aluminum alloy material with high thermal conductivity, and the outer surface serves as the working surface that directly contacts the user's hair. Within the cross-section of the heating tube 1, multiple PTC heating elements 2 are evenly arranged along the circumferential direction, especially four PTC heating elements 2. The following description uses four PTC heating elements 2. The center lines of each PTC heating element 2 are at a 90° angle to each other, forming an orthogonally symmetrical four-quadrant heat source layout. Each PTC heating element 2 is bonded to the inner wall of the heating tube 1 via a thermally conductive medium (such as thermally conductive grease or thermally conductive adhesive), and a mechanical clamping structure ensures that there are no air gaps between them, thereby maximizing heat conduction efficiency. This structure ensures that the straight-line distance from any circumferential position of the heating tube 1 to the nearest PTC heating element 2 does not exceed one-quarter of the circumference, significantly shortening the heat conduction path and effectively suppressing surface temperature differences.

[0019] In this embodiment, each PTC heating element 2 is equipped with an independent temperature sensing unit 3 and an independent driving circuit, forming four physically isolated and logically independent temperature control zones; the temperature sensing unit 3 is preferably an NTC thermistor, which is attached to the body of the PTC heating element 2 or adjacent to its installation position, and is used to detect the local temperature of the corresponding zone in real time. The drive circuit includes MOSFET switching elements and a current limiting protection module, which is uniformly scheduled by the main control MCU5. The main control MCU5 has a pre-stored target operating temperature threshold (e.g., 180℃) and periodically collects temperature data from four zones at a sampling period of no more than 100 milliseconds. When the measured temperature of any partition is lower than the set threshold and the duration exceeds the preset judgment window (e.g., 200 milliseconds), the main control MCU5 will start the drive circuit corresponding to that partition and apply the working voltage to the PTC heating element 2 for heating; when the temperature of that partition rises back to above the set threshold, the power supply to the PTC heating element 2 will be cut off immediately. The other three zones maintain their current operating state during this process and do not participate in the linkage control. This zone-based closed-loop control mechanism ensures that the system only performs thermal compensation on the areas where a temperature drop actually occurs, avoiding energy waste and localized overheating caused by overall heating.

[0020] In terms of electrical connection, the four PTC heating elements 2 adopt a parallel structure, but each parallel branch has an independent power control channel; The main control MCU5 adjusts the duty cycle of each PTC heating element 2 through four PWM signals to achieve precise control of the heating power of each zone. During the initial startup phase, the four PTC heating elements 2 heat up at full power simultaneously, so that the surface of the heating tube 1 reaches the target operating temperature of 180℃±5℃ within 25 seconds; After entering steady-state operation, the system switches to zone dynamic compensation mode: when the user wraps their hair around the heating tube 1 and pulls their hair, the temperature of the contact area drops due to heat conduction to the hair. After the temperature sensing unit 3 of the corresponding zone detects this change, the main control MCU 5 activates the drive circuit of that zone in the next control cycle, so that it completes the temperature recovery compensation within 2 seconds, and restores the surface temperature to the set value. This temperature recovery process does not affect the temperature stability of other undisturbed zones, thereby maintaining the surface temperature fluctuation range of the entire tube within ±3℃.

[0021] To improve the uniformity of heat conduction, the inner wall of the heating tube 1 is provided with local grooves or flat contact surfaces at the four installation positions of the PTC heating elements 2, so that the heating surface of the PTC heating element 2 forms a surface-to-surface contact with the tube wall rather than a point contact. The external dimensions of each PTC heating element 2 are matched with the corresponding bonding area, and the contact area is not less than 90% of the total area of ​​the PTC bottom surface. In addition, the space between the PTC heating element 2 and the tube wall is filled with a thermally conductive medium with a thermal conductivity of not less than 3.0 W / (m·K) to further eliminate interfacial thermal resistance. A fixing bracket 4 is provided on the inner side of the heating tube 1, and the fixing bracket 4 is made of aluminum; Structurally, four PTC heating elements 2 are arranged centrally along the axis of the heating tube 1, and their effective heating length covers more than 80% of the working area of ​​the heating tube 1, ensuring axial temperature consistency. Meanwhile, the heating element 1 is equipped with heat insulation rings at both ends, made of high-temperature resistant plastic or ceramic materials, to block heat conduction to the handle end and ensure user safety.

[0022] The main control MCU5 has built-in temperature anomaly protection logic. If any zone fails to recover its temperature three times in a row within a set time (i.e., the temperature remains below the lower threshold), the system determines it to be an abnormal heat dissipation state (such as wet hair wrapped around the area or prolonged contact), automatically reduces the maximum allowable heating power of that zone, and triggers a user prompt signal (such as LED flashing or a buzzer). If two or more of the four zones simultaneously exhibit abnormal temperatures, the entire system enters a low-power standby mode to prevent overheating. This protection mechanism works in conjunction with zone temperature control to maintain optimal thermal response performance while ensuring safety.

[0023] In practical use, after the user turns on the curling iron, the main control MCU5 controls the four PTC heating elements 2 to operate simultaneously at full power: S1: Rapidly heat the surface of heating element 1 to 180℃±5℃ within 25 seconds; S2: After entering the steady-state working stage, the main control MCU5 polls the data of the four temperature sensing units 3 at a period of 100 milliseconds; S3: When the temperature of a certain partition is detected to be lower than the set threshold and lasts for more than 200 milliseconds, the main control MCU5 immediately sends a PWM signal to the drive circuit corresponding to that partition to start the PTC heating element 2 for local heating; S4: When the temperature of this partition rises above the set threshold, the main control MCU5 cuts off the power supply to the PTC heating element 2, and the other partitions remain in their original state; S5: If a certain partition fails to complete the temperature recovery within 2 seconds three times in a row, the main control MCU5 will determine it as an abnormal state, reduce the maximum power of that partition and trigger a prompt; S6: If two or more partitions are abnormal at the same time, the whole machine will enter standby mode. Understandably, the entire control process requires no user intervention and is executed automatically by the main control MCU5.

[0024] Compared to the existing dual PTC structure (two PTC heating elements are arranged symmetrically at 180°), this utility model, through the orthogonal distribution of four PTCs, shortens the distance from any point on the surface of the heating tube 1 to the nearest heat source to half that of the traditional structure, greatly reducing the temperature difference caused by uneven heat diffusion. Experimental data show that the maximum temperature difference on the entire tube surface under steady-state operation of this invention does not exceed 6℃, while the traditional dual PTC structure is usually above 10-15℃. Furthermore, the warm-up time after a single hair pull is reduced to less than 4 seconds, significantly better than the 8-10 seconds of existing products. These technical features work together to minimize temperature differences across the hair during the curling process, ensuring consistent softening and a uniform, long-lasting styling effect. Meanwhile, by avoiding unnecessary high-temperature exposure and repeated heating, it reduces protein denaturation and moisture loss, thus minimizing hair damage. This structure is suitable for various handheld curling irons, straighteners, and other beauty and hairdressing equipment, demonstrating clear feasibility and industrialization value.

[0025] By evenly distributing four PTCs at 90° circumference, the heat conduction distance from any point on the heating element surface to the nearest heat source is shortened to half that of the traditional dual PTC structure, significantly reducing the temperature difference caused by uneven heat diffusion; each PTC is equipped with an independent temperature control circuit to achieve precise heat compensation on demand, avoiding energy redundancy and local overheating caused by overall heating. The high thermal conductivity aluminum tube and optimized interface contact structure ensure efficient heat transfer from the PTC to the working surface; the zoned dynamic control strategy reduces the recovery time after a single pull to less than 4 seconds, which is significantly better than the 8-10 seconds of existing dual PTC products. The maximum temperature difference across the entire tube surface under steady-state operation does not exceed 6℃, while traditional structures typically exceed 10-15℃. These technical features work together to minimize temperature differences across the hair during curling, resulting in uniform softening and a consistent, long-lasting style. Simultaneously, by avoiding unnecessary high-temperature exposure and repeated heating, protein denaturation and moisture loss are reduced, minimizing hair damage. This structure is suitable for various handheld curling irons, straighteners, and other hair styling equipment, demonstrating clear feasibility and industrialization value.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. An integrated multi-PTC heating curling iron, characterized in that: It includes a cylindrical heating element (1) and a heating and temperature control system disposed inside the heating element (1); The heating element (1) is made of aluminum with high thermal conductivity, and its outer cylindrical surface forms the working surface; Within the cross-section of the heating tube (1), multiple PTC heating elements (2) are uniformly arranged along the circumferential direction, with the circumferential angle between the center lines of each PTC heating element (2) being 90°, and they are orthogonally symmetrically distributed. A fixing bracket (4) is provided on the inner side of the heating tube (1). Each PTC heating element (2) is bonded to the inner wall of the heating tube (1) through a heat-conducting medium, and a mechanical clamping structure is used to ensure that there is no air gap between it and the inner wall; Each PTC heating element (2) is equipped with an independent temperature sensing unit (3) and an independent driving circuit, forming multiple physically isolated and logically independent temperature control zones; The temperature sensing unit (3) is an NTC thermistor mounted on the body of the PTC heating element (2) or adjacent to its installation position; each driving circuit is uniformly scheduled by the main control MCU (5), the main control MCU (5) periodically collects temperature data of multiple zones, and independently controls the on / off of the corresponding PTC heating element (2) according to the comparison results of the measured temperature of each zone and the pre-stored target working temperature threshold.

2. The integrated multi-PTC heating curling iron according to claim 1, characterized in that: Multiple PTC heating elements (2) are connected in parallel. Each parallel branch has an independent power control channel. The main control MCU (5) adjusts the duty cycle of each PTC heating element (2) through multiple PWM signals.

3. The integrated multi-PTC heating curling iron according to claim 1, characterized in that: The inner wall of the heating tube (1) has local grooves or flat contact surfaces at the installation positions of multiple PTC heating elements (2), so that the heating surface of the PTC heating element (2) and the tube wall form a surface-to-surface contact. The external dimensions of each PTC heating element (2) are matched with the corresponding bonding area.

4. The integrated multi-PTC heating curling iron according to claim 1, characterized in that: Multiple PTC heating elements (2) are arranged axially along the heating tube (1).

5. The integrated multi-PTC heating curling iron according to claim 1, characterized in that: The heating element (1) has heat insulation rings made of high-temperature resistant plastic or ceramic material at both ends.

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