Electric heating rod capable of realizing efficient noise reduction

Abstract

The utility model relates to an electric heating rod capable of realizing efficient noise reduction. The electric heating rod comprises a resistance wire, a metal shell, a magnesium powder rod, a rubber plug cover, two guide rods and a metal end cover, the rubber plug cover and the metal end cover are respectively fixed at two ends in the metal shell, and a sealing cavity is formed inside; the magnesium powder rod is arranged in the sealing cavity, and magnesium powder is filled between the outer surface of the magnesium powder rod and the inner wall of the metal shell and between one end, close to the metal end cover, of the magnesium powder rod and the inner end of the metal end cover; the two guide rods are inserted into the two guide rod insertion holes in the magnesium powder rod, penetrate through the two preformed holes in the rubber plug cover in a sealing manner, and extend out of one end of the metal shell to form two external terminals; the two guide rods are made of low-magnetic-conductivity metal; the resistance wire is arranged in the sealing cavity and is spirally wound on the outer surface of the magnesium powder rod; and the two ends of the resistance wire are respectively and electrically connected with the two guide rods through winding welding or surface-mounted contact. The noise of the heater is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of vehicle electric heaters, and particularly relates to an electric heating rod capable of achieving efficient noise reduction. Background Art

[0002] New energy pure electric vehicles are equipped with electric heaters to meet heating, defrosting, and demisting requirements. Currently, new energy vehicles feature a wide variety of electric heaters, primarily including high-voltage electric heaters with resistance wire structures, thick-film structures, and PTC structures. Due to limitations in operating conditions, PTC-type high-voltage electric heaters are limited to voltages below 500V. For voltages greater than 500V, only resistance wire and thick-film structures are currently suitable. However, both types of heaters experience excessive sound pressure levels and poor sound quality during operation. Resistance wire-type high-voltage electric heaters primarily produce a high-frequency grating sound, while thick-film-type high-voltage electric heaters primarily produce corona noise and a high-frequency hissing sound.

[0003] There is currently no effective solution to the noise problem of electric heaters mentioned above. Therefore, in order to solve the noise problem of electric heaters, it is necessary to optimize and improve the electric heating rod inside the electric heater from the perspective of high-voltage electric heaters with resistance wire structure and develop an electric heating rod with efficient noise reduction structure. Utility Model Content

[0004] Aiming at the deficiencies of the prior art, the utility model provides an electric heating rod capable of achieving efficient noise reduction.

[0005] The above purpose of the present invention is achieved through the following technical solutions:

[0006] The electric heating rod can achieve high-efficiency noise reduction, comprising a resistance wire, a metal shell, a magnesium powder rod, a rubber plugging cover, two lead rods, and a metal end cover; the magnesium powder rod is provided with two lead rod insertion holes; the rubber plugging cover and the metal end cover are respectively fixed at two end positions in the metal shell to form a sealed cavity inside; the magnesium powder rod is placed in the sealed cavity, and magnesium powder is filled between the outer surface of the magnesium powder rod and the inner wall of the metal shell and between one end of the magnesium powder rod close to the metal end cover and the inner end of the metal end cover; the two lead rods are inserted into the two lead rod insertion holes on the magnesium powder rod, and the outer ends of the two lead rods are sealed through two reserved holes on the rubber plugging cover and extend from one end of the metal shell to form two external terminals; it is characterized in that: the material of the two lead rods is low magnetic permeability metal; the resistance wire is arranged in the sealed cavity, and the main body of the resistance wire is spirally wound on the outer surface of the magnesium powder rod; the two ends of the resistance wire are respectively electrically connected to the two lead rods by winding welding or surface-mount contact.

[0007] Moreover, the resistance wire is wound on the outer surface of the magnesium powder rod in a unidirectional spiral manner; the two lead rods are a long lead rod and a short lead rod, the inner end of the long lead rod extends to the inner end position of the magnesium powder rod, and the inner end of the short lead rod extends to the outer end position of the magnesium powder rod; the inner ends of the long lead rod and the short lead rod are respectively wound and welded to the two ends of the resistance wire.

[0008] Moreover, the resistance wire is wound on the outer surface of the magnesium powder rod in a unidirectional spiral manner, and the two lead rods are both short lead rods. The inner ends of the two lead rods extend to the outer end positions of the magnesium powder rod, and the two lead rods are respectively in surface contact with the two ends of the resistance wire.

[0009] Moreover, the resistance wire is wound on the outer surface of the magnesium powder rod in a unidirectional spiral manner; the two lead rods are both coaxially arranged two-section structures, including an outer lead rod section body and an inner magnesium rod section, the inner ends of the two inner magnesium rod sections extend to the inner end position of the magnesium powder rod, and the two lead rods are respectively in surface contact with the two ends of the resistance wire.

[0010] Moreover, a cylindrical boss is provided at the middle part of the end of the magnesium powder rod extending away from the lead rod, and the resistance wire is wound on the outer surface of the magnesium powder rod in a bidirectional spiral manner, and the middle part of the resistance wire forms a solid fit with the cylindrical boss; both ends of the resistance wire are arranged near the outer end of the magnesium powder rod, and the two lead rods are both short rods, and the inner ends of the two lead rods extend to the outer end position of the magnesium powder rod, and the inner ends of the two lead rods are respectively wound and welded with the two ends of the resistance wire.

[0011] Moreover, a cylindrical boss is provided at the middle part of the end of the magnesium powder rod extending away from the lead rod, and the resistance wire is wound on the outer surface of the magnesium powder rod in a bidirectional spiral manner, and the middle part of the resistance wire forms a solid fit with the cylindrical boss; both ends of the resistance wire are arranged near the outer end of the magnesium powder rod; the two lead rods are both coaxially arranged two-section structures, including a lead rod segment body and a magnesium rod segment, and the inner ends of the two inner magnesium rod segments extend to the inner end position of the magnesium powder rod, and the two lead rods are respectively in surface-mounted contact with the two ends of the resistance wire.

[0012] Moreover, the size of the end of the resistance wire welded to the lead rod is half the size of the resistance wire wound around the lead rod, and the welding position is the position where the end of the resistance wire is away from the middle body of the resistance wire.

[0013] Moreover, the cross-section of the guide rod is circular, elliptical or rounded rectangular.

[0014] The advantages and positive effects of the utility model are:

[0015] 1. The utility model adopts low magnetic permeability metal as the lead rod material of the electric heating rod. The heating rod of this structure is applied to the high-voltage electric heater, which greatly reduces the magnetic field noise generated by the high-frequency change of the electromagnetic field, so that the noise index of the heater meets the use requirements.

[0016] 2. The reduction in length of the metal lead rod and the change in cross-sectional shape of the present invention effectively reduce the magnetic field strength of the heating rod when it is working, thereby reducing the noise of the heater.

[0017] 3. The utility model changes the winding direction of the resistance wire from unidirectional spiral winding to bidirectional spiral winding, and adopts metal with poor magnetic conductivity as the lead rod of the electric heating rod. The heating rod of this structure is applied to high-voltage electric heaters, which can also effectively reduce the magnetic field noise generated by high-frequency changes in the electromagnetic field, so that the noise index of the heater meets the use requirements.

[0018] 4. The optimized adjustment of the welding structure between the resistance wire and the lead rod of the utility model improves the reliability of the use of the resistance wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a cross-sectional schematic diagram of an existing electric heating rod;

[0020] Figure 2 It is a physical structure diagram of an existing electric heating rod;

[0021] Figure 3 It is a three-dimensional schematic diagram of the surface contact between the existing resistance wire and the lead rod;

[0022] Figure 4 It is a schematic diagram of the existing current flow and electromagnetic field;

[0023] Figure 5a This is a cross-sectional view of a first embodiment of the electric heating rod of the present utility model;

[0024] Figure 5b This is a perspective exploded view of the first embodiment of the electric heating rod of the utility model;

[0025] Figure 6 This is a three-dimensional schematic diagram and a partial diagram of the welding of the resistance wire and the lead rod in the first embodiment of the present utility model;

[0026] Figure 7 7a is a sectional view and 7b is a three-dimensional diagram of the cooperation of the 1 / 3 metal lead rod and the magnesium rod in the first embodiment of the present invention;

[0027] Figure 8 This is a schematic diagram of the cross-sectional structure of the lead rod of the utility model;

[0028] Figure 9 This is a schematic diagram of the current flow and electromagnetic field of the first embodiment of the utility model;

[0029] Figure 10 10a is a cross-sectional view and 10b is a perspective exploded view of a second embodiment of the electric heating rod of the present invention;

[0030] Figure 11 This is a three-dimensional schematic diagram of a magnesium powder rod and a bidirectional spiral resistance wire in the second embodiment of the present invention;

[0031] Figure 12 12a is a three-dimensional schematic diagram of the bidirectional spirally wound resistance wire structure in the second embodiment of the present invention; 12b is a surface mount type;

[0032] Figure 13 This is a three-dimensional schematic diagram of the cooperation between the 1 / 3 metal lead rod and the magnesium rod of the bidirectionally wound resistance wire in the second embodiment of the present invention;

[0033] Figure 14 This is a schematic diagram of the electromagnetic field of the second embodiment of the present utility model;

[0034] Figure 15 Comparison of spectrum diagrams before and after electric heater structure optimization. DETAILED DESCRIPTION

[0035] The structure of the present invention will be further described below with reference to the accompanying drawings and through examples. It should be noted that the present examples are descriptive rather than restrictive.

[0036] The heating carrier of the resistance wire structure vehicle high voltage electric heater adopts an electric heating rod with a resistance wire. This electric heating rod is a single-head rod, as shown in the diagram Figure 1 .

[0037] The noise from electric heaters is primarily a high-frequency, harsh sound with periodic pulse spikes. This noise is caused by electromagnetic induction noise generated by the heating rod. Electromagnetic induction occurs when the heating rod is powered, and this is due to the physical structure of the heating rod.

[0038] The physical structure of the electric heating rod is shown in Figure 1 and Figure 2 , mainly including resistance wire 4, metal outer shell 6, magnesium powder rod 3, rubber plugging cover 2, two lead rods 1, metal end cover 7, magnesium powder 5. There are two lead rod insertion holes 3.1 on the magnesium powder rod. The material of the resistance wire is nickel-chromium alloy wire, and the material of the lead rod is nickel rod. Both the resistance wire and the lead rod have good magnetic conductivity. The resistance wire is unidirectional spirally wound, and its main part is wound around the outside of the magnesium powder rod, with the lead rod inserted in the middle. The two ends of the resistance wire are in surface-mounted contact with the two lead rods to form an electrical connection. The surface of the resistance wire and the surface of the lead rod fit tightly, see the local structure Figure 3 The two guide rods are respectively inserted into the two through holes on the magnesium powder rod. According to Ampere's circuit theorem and Faraday's law of electromagnetic induction, the electric heating rod generates an electromagnetic field when it is energized, forming three magnetic fields, namely, strip magnetic field A, annular magnetic field B and annular magnetic field C. These three magnetic fields are mutually intertwined. Figure 4Typically, at 50V, the magnetic field strength is greater than 15mG. The higher the voltage, the larger the outer diameter of the lead rod, and the larger the outer diameter of the resistance wire, the greater the magnetic field strength. Because the heater's power supply frequency is controlled by the controller's PWM control signal, frequent on and off cycles result in frequent fluctuations in the heater's electromagnetic field strength. These fluctuations directly generate high-frequency noise. The higher the PWM control signal frequency, the greater the audio sound pressure level of the noise.

[0039] In order to reduce the noise sound pressure level, the utility model adopts optimization and improvement of the electric heating rod. The specific implementation methods of the two improvements are as follows:

[0040] Example 1: See Figure 5a and Figure 5b The electric heating rod mainly includes a resistance wire 4, a metal outer shell 6, a magnesium powder rod 3, a rubber plugging cover 2, two lead rods 1, a metal end cover 7, and magnesium powder 5. The magnesium powder rod is provided with two lead rod insertion holes. The main improvements are: the lead rods are made of metals with poor magnetic conductivity, including stainless steel, aluminum rods, copper rods, etc., but not limited to these metals. The resistance wire is unidirectionally spirally wound with a lead rod inserted in the middle. The two ends of the resistance wire can be wound in contact with the two lead rods respectively and connected by welding, see the local structure Figure 6 , the surface of the end of the resistance wire can also fit closely with the surface of the corresponding lead rod. The size of the resistance wire end welded to the lead rod is half the size of the resistance wire wrapped around the lead rod. The welding section is marked with 4A in the attached figure, and the non-welding section is marked with 4B in the attached figure. Leaving the non-welding section ensures the tightness of the resistance wire, reduces the effect of thermal expansion and contraction when the resistance wire works at high temperature, and improves its reliability. The length of the metal lead rod can also be shortened. The end of the resistance wire and the lead rod are in surface-mount contact. For example, 1 / 3 of the lead rod is replaced by a magnesium rod 8 for the remaining 2 / 3 of the length, see the local structure Figure 7 The surface of the resistance wire and the surface of the metal lead rod fit tightly. Generally, the outer diameter of the lead rod is less than 2mm, and the outer diameter of the resistance wire is less than 0.5mm. Under the premise of meeting the size requirements, the cross-sectional shape of the lead rod can be further expanded to an elliptical structure or a rounded rectangular structure, see the local structure Figure 8 The electromagnetic field generated by the heating rod with the above structure is Figure 9 Typically, at 50V, the magnetic field strength is less than 4mG. This weakening of the electromagnetic field directly affects the magnetic noise generated by high-frequency changes in the magnetic field, significantly reducing the high-frequency, harsh noise of the heater.

[0041] Implementation method 2: See Figure 10 The electric heating rod mainly includes a resistance wire 4, a metal outer shell 6, a magnesium powder rod 3, a rubber plug cover 2, two lead rods 1, a metal end cover 7, and magnesium powder 5. There are two lead rod insertion holes on the magnesium powder rod, and a cylindrical boss 3.2 is provided on the end of the magnesium powder rod away from the lead rod to fix the resistance wire. Figure 11The lead rod is made of low magnetic permeability metal. The resistance wire is bidirectionally spirally wound with the lead rod inserted in the middle. The ends of the resistance wire and the two lead rods can be welded or surface mounted. Figure 12 The surface-mount contact lead rod can be shortened, for example, 1 / 3 of the length is made of a low-magnetic-permeability metal lead rod, and the remaining 2 / 3 is replaced by a magnesium rod 8. Figure 13 The cross-sectional shape of the guide rod can also be expanded to an elliptical structure or a rounded rectangular structure. With this structure, the heating rod is heated by the electromagnetic field generated by the power supply. Figure 14 , forming two cross magnetic fields, namely magnetic field E and magnetic field F. The directions of these two magnetic fields are opposite, and the magnetic field strengths cancel each other out, which directly affects the noise and sound pressure values ​​of the heating rod and is effectively reduced.

[0042] The noise of electric heaters is mainly high-frequency harsh sound. After the electric heater adopts a heating rod with a noise reduction structure, the high-frequency harsh sound basically disappears. The noise spectrum before and after the electric heater structure is optimized is as follows Figure 15 , spectrum line 9 is the unoptimized noise, and spectrum line 10 is the optimized noise. It can be clearly seen from the figure that after optimization, the periodic pulse peaks are greatly reduced, and the noise amplitude is greatly reduced, which further proves that the improved structure of the heating rod has a good noise reduction effect.

[0043] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various replacements, changes and modifications are possible without departing from the spirit of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. An electric heating rod capable of achieving efficient noise reduction, comprising a resistance wire, a metal shell, a magnesium powder rod, a rubber plugging cover, two lead rods, and a metal end cap; the magnesium powder rod is formed with two lead rod insertion holes; the rubber plugging cover and the metal end cap are respectively fixed at two end positions within the metal shell, forming a sealed cavity inside; the magnesium powder rod is placed in the sealed cavity, and magnesium powder is filled between the outer surface of the magnesium powder rod and the inner wall of the metal shell, and between the end of the magnesium powder rod close to the metal end cap and the inner end of the metal end cap; the two lead rods are inserted into the two lead rod insertion holes on the magnesium powder rod, and the outer ends of the two lead rods are sealed through two reserved holes in the rubber plugging cover and extend from one end of the metal shell to form two external wiring terminals; the characteristics are: The two lead rods are made of low-magnetic-permeability metal; the resistance wire is arranged in a sealed cavity, and the main body of the resistance wire is spirally wound on the outer surface of the magnesium powder rod; the two ends of the resistance wire are electrically connected to the two lead rods through winding welding or surface-mount contact.

2. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: The resistance wire is wound on the outer surface of the magnesium powder rod in a unidirectional spiral manner; the two lead rods are a long lead rod and a short lead rod, the inner end of the long lead rod extends to the inner end position of the magnesium powder rod, and the inner end of the short lead rod extends to the outer end position of the magnesium powder rod; the inner ends of the long lead rod and the short lead rod are respectively wound and welded to the two ends of the resistance wire.

3. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: The resistance wire is wound in a unidirectional spiral on the outer surface of the magnesium powder rod. The two lead rods are both short lead rods. The inner ends of the two lead rods extend to the outer end positions of the magnesium powder rod. The two lead rods are respectively in surface contact with the two ends of the resistance wire.

4. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: The resistance wire is wound on the outer surface of the magnesium powder rod in a unidirectional spiral manner; the two lead rods are both coaxially arranged two-section structures, including an outer lead rod section body and an inner magnesium rod section, the inner ends of the two inner magnesium rod sections extend to the inner end position of the magnesium powder rod, and the two lead rods are respectively in surface contact with the two ends of the resistance wire.

5. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: A cylindrical boss is provided at the middle of one end of the magnesium powder rod extending away from the lead rod, and the resistance wire is wound on the outer surface of the magnesium powder rod in a bidirectional spiral manner, and the middle part of the resistance wire forms a solid fit with the cylindrical boss; both ends of the resistance wire are arranged near the outer end of the magnesium powder rod, and the two lead rods are both short rods, and the inner ends of the two lead rods extend to the outer end position of the magnesium powder rod, and the inner ends of the two lead rods are respectively wound and welded to the two ends of the resistance wire.

6. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: A cylindrical boss is provided at the middle of one end of the magnesium powder rod extending away from the lead rod, and the resistance wire is wound on the outer surface of the magnesium powder rod in a bidirectional spiral manner, and the middle part of the resistance wire forms a solid fit with the cylindrical boss; both ends of the resistance wire are arranged near the outer end of the magnesium powder rod; the two lead rods are both coaxially arranged two-section structures, including a lead rod segment body and a magnesium rod segment, the inner ends of the two inner magnesium rod segments extend to the inner end position of the magnesium powder rod, and the two lead rods are respectively in surface-mounted contact with the two ends of the resistance wire.

7. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: The size of the end of the resistance wire welded to the lead rod is half the size of the resistance wire wound around the lead rod, and the welding position is the position where the end of the resistance wire is away from the middle body of the resistance wire.

8. The electric heating rod capable of achieving efficient noise reduction according to claim 1, characterized in that: The cross-section of the guide rod is circular, elliptical or rounded rectangular.

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