Temperature-sensing PTC (Positive Temperature Coefficient) heating wire

Abstract

The invention discloses a temperature-sensing PTC heating wire, which comprises a roll core, a first layer of heating wire is wound outside the roll core, a middle heating layer is covered outside the roll core and the first layer of heating wire, a second layer of heating wire is wound outside the middle heating layer, and a film layer is covered outside the middle heating layer and the second layer of heating wire. The thin film layer is covered with an outer skin layer; the pure nickel metal is adopted to manufacture the heating wire, the heating wire can be ensured to have a stable and controllable temperature coefficient through the wire drawing and winding process, and the stable heating performance of the heating wire is ensured; the middle layer is made of polyvinyl chloride with NTC (Negative Temperature Coefficient) characteristics, so that the temperature of the heating wire can be self-adjusted to a certain extent, and the use safety and stability are improved; after the product is used, the heating temperature can be controlled without adding an NTC (Negative Temperature Coefficient) temperature sensor probe, and the product can be arranged in a textile and is convenient to use.

Description

Technical Field

[0001] The invention relates to a heating wire, in particular to a temperature-sensitive PTC heating wire. Background Art

[0002] PTC is the abbreviation of Positive Temperature Coefficient, which means positive temperature coefficient and generally refers to semiconductor materials with large positive temperature coefficient. The PTC we usually refer to is positive temperature coefficient thermistor, referred to as PTC thermistor or PTC electric heater. PTC electric heater is a typical semiconductor resistor with temperature sensitivity. When the temperature exceeds a certain temperature (Curie temperature), its resistance value increases stepwise with the increase of temperature. PTC electric heaters are divided into positive temperature coefficient thermistor (referred to as PTC electric heater) and negative temperature coefficient thermistor (referred to as NTC electric heater) according to different temperature coefficients. NTC is the abbreviation of Negative Temperature Coefficient, which means negative temperature coefficient and generally refers to semiconductor materials or components with large negative temperature coefficient. The so-called NTC electric heater is a negative temperature coefficient electric heater. Existing heating blankets, electric blankets, pet mats, heating boots, massage heating pads, local heating products for human body, tire warming pads, plate heating pads and other heating elements in the insulation and heating series of items often use electric heaters with PTC characteristics.

[0003] However, the traditional heating wire only has a heating layer and no temperature-sensing protective layer. After being installed in the heating blanket, the heat is uneven, the temperature is uncontrollable, and it is not safe to use, posing a safety hazard. In addition, most of the current heating blankets do not have good temperature control during use. To improve the temperature control, either the heating blanket must be replaced or enough NTC temperature sensor probes must be added, which is troublesome and cannot meet the usage requirements. Summary of the invention

[0004] To solve the above technical problems, the technical solution provided by the present invention is: a temperature-sensitive PTC heating wire, comprising a winding core, a first layer of heating wire is wound around the winding core, an intermediate heating layer is covered outside the winding core and the first layer of heating wire, a second layer of heating wire is wound around the intermediate heating layer, the intermediate heating layer and the second layer of heating wire are covered with a thin film layer, and the thin film layer is covered with an outer skin layer.

[0005] In some embodiments, the winding core is made of polyester thread.

[0006] In some embodiments, the first layer of heating wire is made of pure nickel metal.

[0007] In some embodiments, the second layer of heating wires is made of copper wires.

[0008] In some embodiments, the intermediate heating layer is made of polyvinyl chloride NTC.

[0009] In some embodiments, the film layer is made of polyvinyl chloride film.

[0010] In some embodiments, the outer skin layer is a PVC outer skin.

[0011] The invention also discloses a processing method thereof, comprising the following steps:

[0012] Step S1: Preparation of roll core:

[0013] Use high-strength, high-temperature resistant polyester thread as the winding core; install the polyester thread on the pay-off rack of the winding equipment to ensure smooth pay-off process and uniform tension;

[0014] Step S2: Winding the first layer of heating wire:

[0015] Use a precision metal wire drawing machine to draw pure nickel rods into thin wires, and control the PTC characteristics of the nickel wire through cold processing technology; install the drawn heating nickel wire on a special wire winding machine, and spirally wind the heating nickel wire on the polyester wire;

[0016] Step S3, middle layer extrusion:

[0017] Use modified polyvinyl chloride raw materials with NTC characteristics, add them into the barrel of the wire extruder, feed the polyester wire wrapped with heating nickel wire into the extruder, extrude the transparent middle layer heating wire, and make the middle layer heating wire cover the first layer heating wire;

[0018] Step S4: Winding the second layer of heating wire:

[0019] The copper wire is drawn through multiple passes, and the drawn pure copper wire is installed on a wire winding machine so that the copper wire is wound around the middle layer heating wire;

[0020] Step S5, thin film layer covering:

[0021] Select a plastic film tape made of polyvinyl chloride and install it on the covering equipment. Through the control of the equipment, the plastic film tape is evenly and tightly covered on the middle layer of the wound copper wire.

[0022] Step S6: extrusion of outer skin:

[0023] The middle layer heating wire covered with plastic film is sent to another wire extruder. PVC raw materials with a maximum temperature resistance of 115°C are added to the extruder barrel to extrude the PVC evenly, and the middle layer heating wire wrapped with copper wire and covered with plastic film is wrapped to form a white heating wire.

[0024] Step S7: Quality inspection

[0025] Conduct appearance inspection on the produced heating wires to check whether the surface is smooth and whether there are any defects such as bubbles and scratches;

[0026] Conduct electrical performance tests, including resistance measurement, temperature coefficient test, and withstand voltage test, to ensure that the performance of the heating wire meets the design requirements;

[0027] High-temperature aging tests are conducted on random samples to simulate the actual usage environment and test the stability and reliability of the heating wires under high temperature conditions.

[0028] The advantages of the present invention compared with the prior art are:

[0029] (1) The present invention uses pure nickel metal to make the heating wire, and through the wire drawing and winding process, it can ensure that the heating wire has a stable and controllable temperature coefficient, thereby ensuring the stability of the heating performance of the heating wire; the middle layer uses polyvinyl chloride with NTC characteristics, which can self-regulate the temperature of the heating wire to a certain extent, thereby improving the safety and stability of use.

[0030] (2) Using polyester thread as the winding core has relatively low cost and good mechanical properties, which can meet the requirements of winding and subsequent processing.

[0031] (3) After using this product, the heating temperature can be controlled without adding an NTC temperature sensor probe. It can be installed in textiles for easy use. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the internal structure of a temperature-sensitive PTC heating wire of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Example:

[0035] The present embodiment discloses a temperature-sensitive PTC heating wire, comprising a winding core 1, a first layer of heating wire 2 is wound around the winding core 1, an intermediate heating layer 3 is covered around the winding core 1 and the first layer of heating wire 2, a second layer of heating wire 4 is wound around the intermediate heating layer 3, a film layer 5 is covered around the intermediate heating layer 3 and the second layer of heating wire 4, and an outer skin layer 6 is covered around the film layer 5; specifically, the winding core 1 is made of polyester thread; the first layer of heating wire 2 is made of pure nickel metal; the second layer of heating wire 4 is made of copper wire; the intermediate heating layer 3 is made of polyvinyl chloride NTC; the film layer 5 is made of polyvinyl chloride film; and the outer skin layer 6 is made of PVC outer skin.

[0036] In addition, this embodiment also discloses a processing method thereof, comprising the following steps:

[0037] Step S1, preparation of winding core 1:

[0038] Select high-strength, high-temperature resistant polyester thread as the winding core 1; install the polyester thread on the pay-off frame of the winding equipment to ensure smooth pay-off process and uniform tension;

[0039] Step S2, winding the first layer of heating wire 2:

[0040] Use a precision metal wire drawing machine to draw pure nickel rods into fine wires with a diameter of 0.05-0.2mm. The PTC characteristics of the nickel wire are controlled through cold processing technology, and the resistance temperature coefficient is ≥3000ppm / ℃; the drawn heating nickel wire is installed on a special wire winding machine, and the nickel wire is spirally wound on the polyester line with a gap of 3-5mm. The winding tension is controlled at 0.5-1.0N to ensure that the gap uniformity error is ≤±5%.

[0041] Step S3, middle layer extrusion:

[0042] Use modified polyvinyl chloride raw materials with NTC characteristics, add them into the barrel of the wire extruder, feed the polyester wire wrapped with heating nickel wire into the extruder, extrude the transparent middle layer heating wire, and make the middle layer heating wire cover the first layer heating wire 2;

[0043] Step S4, winding the second layer of heating wire 4:

[0044] The copper wire is drawn through multiple passes to 0.1-0.3 mm, and the drawn pure copper wire is installed on a wire winding machine so that the copper wire is wound around the middle layer heating wire;

[0045] Step S5, thin film layer 5 covering:

[0046] Select a plastic film tape made of polyvinyl chloride and install it on the covering equipment. Through the control of the equipment, the plastic film tape is evenly and tightly covered on the middle layer of the wound copper wire.

[0047] Step S6: extrusion of outer skin:

[0048] The middle layer heating wire covered with plastic film is fed into another wire extruder. PVC raw materials with a maximum temperature resistance of 115°C are added into the extruder barrel to extrude the PVC evenly. The middle layer heating wire wrapped with copper wire and covered with plastic film is wrapped to form a white heating wire.

[0049] Step S7: Quality inspection

[0050] Conduct appearance inspection on the produced heating wires to check whether the surface is smooth and whether there are any defects such as bubbles and scratches;

[0051] Conduct electrical performance tests, including resistance measurement, temperature coefficient test, and withstand voltage test, to ensure that the performance of the heating wire meets the design requirements;

[0052] High-temperature aging tests are conducted on random samples to simulate the actual usage environment and test the stability and reliability of the heating wires under high temperature conditions.

[0053] 1. Quality Inspection

[0054] 1. Appearance inspection

[0055] Use the naked eye to observe directly, and with the help of a magnifying glass, to check the surface of the heating wire from all directions.

[0056] Results: The surface of the heating wire is smooth and flat, without defects such as bubbles, cracks, scratches, impurities, etc.; the color is uniform and there is no discoloration; the plastic film belt and the middle layer of polyvinyl chloride fit tightly with the internal structure without delamination or wrinkles.

[0057] 2. Electrical performance testing

[0058] 2.1 Resistance measurement

[0059] Use a high-precision digital multimeter, at room temperature (25℃±2℃), connect the multimeter probes to both ends of the heating wire and measure its resistance.

[0060] Result: The resistance value is within the specified resistance value range.

[0061] 3. Temperature coefficient test

[0062] Place the heating wire in a constant temperature box with precise temperature control, and gradually increase the temperature from room temperature. Use a digital multimeter to measure the resistance of the heating wire at every 10°C temperature interval, draw a resistance-temperature curve, and calculate the temperature coefficient.

[0063] Qualified result: The temperature coefficient should meet the product design requirements.

[0064] 4. Withstand voltage test

[0065] Use a withstand voltage tester, immerse the heating wire in insulating oil, connect the high-voltage output terminal of the tester to the heating wire conductor, connect the ground terminal to the insulating oil tank, apply 1500V AC voltage, and maintain for 1 minute.

[0066] Result: During the test, the heating wire did not show breakdown or flashover, and the leakage current was less than the specified value.

[0067] 5. High temperature aging test

[0068] Place the heating wire in a high-temperature aging box, set the temperature to 110°C, and keep it powered on for 200-240 hours. During this period, regularly observe the changes in the appearance and electrical properties of the heating wire.

[0069] Results: After the aging test, there is no obvious change in the appearance of the heating wire, the resistance value changes by no more than ±10% of the initial value, the temperature coefficient is still within the qualified range, and the withstand voltage test can still meet the requirements.

[0070] 6. Low temperature test

[0071] Place the heating wire in a low temperature test box, lower the temperature to -20℃, keep it for 4h-6h, then take it out and restore it to room temperature for 1h. Observe the appearance of the heating wire and measure the electrical performance.

[0072] Results: There is no cracking or deformation on the heating wire. The resistance value, temperature coefficient and withstand voltage performance have no obvious changes compared with before the test, and meet the qualification standards.

[0073] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A temperature-sensitive PTC heating wire, characterized in that: It includes a winding core, a first layer of heating wire is wound outside the winding core, an intermediate heating layer is covered outside the winding core and the first layer of heating wire, a second layer of heating wire is wound outside the intermediate heating layer, the intermediate heating layer and the second layer of heating wire are covered outside a film layer, and the film layer is covered outside an outer skin layer.

2. A temperature-sensitive PTC heating wire according to claim 1, characterized in that: The winding core is made of polyester thread.

3. The temperature-sensitive PTC heating wire according to claim 1, characterized in that: The first layer of heating wire is made of pure nickel metal.

4. The temperature-sensitive PTC heating wire according to claim 1, characterized in that: The second layer of heating wire is made of copper wire.

5. The temperature-sensitive PTC heating wire according to claim 1, characterized in that: The middle heating layer is made of polyvinyl chloride NTC.

6. The temperature-sensitive PTC heating wire according to claim 1, characterized in that: The film layer is made of polyvinyl chloride film.

7. The temperature-sensitive PTC heating wire according to claim 1, characterized in that: The outer skin layer adopts PVC outer skin.

8. The temperature-sensitive PTC heating wire according to claim 1, wherein the processing method thereof comprises the following steps: Step S1: Preparation of roll core: Use high-strength, high-temperature-resistant polyester thread as the winding core; install the polyester thread on the pay-off rack of the winding equipment to ensure smooth pay-off process and uniform tension; Step S2: Winding the first layer of heating wire: Use a precision metal wire drawing machine to draw pure nickel rods into thin wires, and control the PTC characteristics of the nickel wire through cold processing technology; install the drawn heating nickel wire on a special wire winding machine, and spirally wind the heating nickel wire on the polyester wire; Step S3, middle layer extrusion: Use modified polyvinyl chloride raw materials with NTC characteristics, add them into the barrel of the wire extruder, feed the polyester wire wrapped with heating nickel wire into the extruder, extrude the transparent middle layer heating wire, and make the middle layer heating wire cover the first layer heating wire; Step S4: Winding the second layer of heating wire: The copper wire is drawn through multiple passes, and the drawn pure copper wire is installed on a wire winding machine so that the copper wire is wound around the middle layer heating wire; Step S5, thin film layer covering: Select a plastic film tape made of polyvinyl chloride and install it on the covering equipment. Through the control of the equipment, the plastic film tape is evenly and tightly covered on the middle layer of the wound copper wire. Step S6: extruding the outer skin: The middle layer heating wire covered with plastic film is sent to another wire extruder. PVC raw materials with a maximum temperature resistance of 115°C are added to the extruder barrel to extrude the PVC evenly, and the middle layer heating wire wrapped with copper wire and covered with plastic film is wrapped to form a white heating wire. Step S7: Quality inspection Conduct appearance inspection on the produced heating wires to check whether the surface is smooth and whether there are any defects such as bubbles and scratches; Conduct electrical performance tests, including resistance measurement, temperature coefficient test, and withstand voltage test, to ensure that the performance of the heating wire meets the design requirements; conduct high-temperature aging tests on samples to simulate the actual use environment and test the stability and reliability of the heating wire under high temperature conditions.

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