Ignition coil for automobile engine with magnetic field shielding function

Abstract

This invention discloses an automotive engine ignition coil with magnetic field shielding function. By embedding a filter carbon rod in the high-voltage path, it effectively suppresses alternating magnetic field radiation interference generated during ignition at the source. The filter carbon rod is formed by extruding carbon fiber monofilaments and a binder, with a continuous nickel plating layer on its surface. Without altering the external structure, it improves electromagnetic shielding effectiveness and reliability under high-temperature and vibration environments, and offers strong compatibility.

Description

Technical Field

[0001] This invention relates to the field of automotive electrical technology, and in particular to an engine ignition coil that can effectively suppress electromagnetic radiation interference. Background Technology

[0002] Automotive ignition coils operate on the principle of electromagnetic induction: a low-voltage current flows through the primary winding, creating a magnetic field. When the current is momentarily cut off, the magnetic field changes abruptly, inducing a high-voltage current in the secondary winding. This current is transmitted through the high-voltage terminal and a spring to the spark plug, generating an electric spark and igniting the engine. During the momentary switching of the high voltage, the ignition coil radiates a strong alternating magnetic field, which can easily interfere with the normal operation of the vehicle's radio, instrument panel, onboard computer, and various other automotive electrical components. Current industry solutions typically involve adding an external anti-interference resistor to the high-voltage ignition terminal or connecting an anti-interference capacitor in parallel with the ignition module.

[0003] However, the existing method has obvious drawbacks: the magnetic field attenuation effect of the external anti-interference component is limited, and the magnetic field shielding effectiveness needs to be improved; moreover, the external component has poor temperature resistance and shock resistance, and is prone to aging and failure under the long-term high temperature and vibration environment of the engine, resulting in insufficient reliability. Summary of the Invention

[0004] To address the aforementioned drawbacks, the technical problem this invention aims to solve is to provide an automotive engine ignition coil with magnetic field shielding capabilities, effectively improving magnetic field shielding performance and operational reliability. The technical solution adopted by this invention is an automotive engine ignition coil with magnetic field shielding capabilities, comprising a plug, an ignition coil composed of a primary coil and a secondary coil, and a high-voltage connecting rod; the conductive terminals of the plug are electrically connected to the primary coil; the high-voltage connecting rod has an internal cavity extending axially along its body, and a conductive mounting seat for a spark plug is provided at its lower end. The high-voltage connecting rod has an upper high-voltage spring, a filter carbon rod, and a lower high-voltage spring arranged sequentially along the axial direction within its accommodating cavity. The upper end of the upper high-voltage spring abuts against the upper end of the accommodating cavity, and the lower end abuts against the upper end of the filter carbon rod. The lower end of the lower high-voltage spring abuts against the conductive mounting seat of the spark plug, and the upper end abuts against the lower end of the filter carbon rod. The secondary coil, the upper high-voltage spring, the filter carbon rod, the lower high-voltage spring, and the conductive mounting seat are connected in series to form a continuously conductive electrical connection path. The filter carbon rod is formed by extruding carbon fiber monofilaments and binder, and then nickel-plated to form a continuous conductive and magnetic surface. The nickel content accounts for 40% to 50% of the total mass of the filter carbon rod. The diameter of the carbon fiber monofilament is 5 to 10 μm, and the aspect ratio of the carbon fiber monofilament is 10:1 to 50:1.

[0005] In one embodiment, the filter carbon rod has an outer diameter of 6-8 mm and a length of 10-20 mm.

[0006] In one embodiment, the elastic stiffness of the upper high-pressure spring is greater than that of the lower high-pressure spring, and the preload applied by the upper high-pressure spring to the filter carbon rod is greater than the supporting force of the lower high-pressure spring, thus maintaining the axial position stability of the filter carbon rod. This effectively buffers and resists severe vibrations in the engine compartment.

[0007] In one embodiment, the two ends of the filter carbon rod are respectively connected to the upper and lower high-pressure springs via conductive connectors, achieving both elastic mechanical and electrical connections.

[0008] A method for manufacturing a filter carbon rod includes the following steps: S1. Carbon fiber monofilaments are uniformly mixed with an appropriate amount of binder. The diameter of the carbon fiber monofilaments is 5-10 μm and the aspect ratio of the carbon fiber monofilaments is 10:1-50:1. The S2 mixture is placed in an extruder, extruded into rods through a die, and then thermosetting. S3 performs nickel plating on the outer surface of the filter carbon rod, so that the nickel content accounts for 40% to 50% of the total mass of the filter carbon rod; after drying, the filter carbon rod is obtained.

[0009] The beneficial effects of this invention are as follows: Using the above technical solution, the carbon fiber skeleton and nickel plating form a conductive path. When an alternating magnetic field passes through, eddy currents are induced within it. According to Lenz's law, these eddy currents generate a magnetic field opposite to the original magnetic field, thereby weakening the magnetic energy passing through it and forming an effective electromagnetic shielding mechanism. Simultaneously, the high nickel content provides a low magnetic reluctance path for the magnetic field, guiding and diverting some magnetic lines of force, causing them to close inside the carbon rod and reducing the outward radiated magnetic flux. This invention places the filter carbon rod in the high-voltage path of the main magnetic field generation and propagation. While the high voltage is conducting, the filter carbon rod can effectively filter, absorb, and attenuate the high-frequency magnetic field radiation during ignition.

[0010] Unlike traditional "end-point treatment" methods using external resistors / capacitors, this invention directly integrates the shielding functional component (filter carbon rod) into the core path (high-voltage connecting rod) where high-voltage current and magnetic fields are generated. This allows for immediate processing after interference occurs, preventing coupling and radiation of interference along the transmission path. It suppresses electromagnetic interference at its source, effectively improving magnetic field shielding performance.

[0011] This built-in integrated structure facilitates use with externally added anti-interference resistors and capacitors to form a multi-layered, multi-level protection mechanism. The built-in filter carbon rod primarily suppresses magnetic field radiation interference. The external resistors are mainly used to dampen ignition spike voltage, while the capacitors are used to filter out conducted interference in specific frequency bands. Due to their different mechanisms of action and frequency band focuses, their synergistic use can achieve wider-band, more comprehensive interference suppression, further improving magnetic field shielding capabilities.

[0012] The filter carbon rod has a high structural strength and is protected by being built into the middle of the upper and lower high-pressure springs. It is resistant to high temperature and vibration, and is not easy to break. It is suitable for the long-term high-temperature operation of the engine, and is stable, reliable and has a long service life.

[0013] Without altering the original ignition coil's overall installation shape and assembly interface, it is directly compatible with existing vehicle installation structures, exhibiting strong versatility.

[0014] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0015] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0016] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0017] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0018] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the automotive engine ignition coil with magnetic field shielding function according to the present invention.

[0020] Figure labeling: 1—Plug, 2—Ignition coil, 3—High-voltage connecting rod, 4—Upper high-voltage spring, 5—Filter carbon rod, 6—Conductive mounting base, 7—Spark plug, 8—Lower high-voltage spring, 9—Conductive connector. Detailed Implementation

[0021] See appendix Figure 1 This illustrates a specific structure of the present invention. The basic structure of the automotive engine ignition coil with magnetic field shielding function includes a plug 1, an ignition coil 2 consisting of a primary coil and a secondary coil, and a high-voltage connecting rod 3.

[0022] In the example, the plug 1 is fixed to the side of the ignition coil 2 near the input end, and the conductive terminals of the plug 1 are electrically connected to the primary coil input end of the ignition coil 2. The high-voltage connecting rod 3 is fixed to the side of the ignition coil 2 near the output end, and the high-voltage connecting rod 3 has an accommodating cavity that extends along the axial direction of the rod body. The lower end of the high-voltage connecting rod 3 is provided with a conductive mounting seat 6 for the spark plug 7.

[0023] The high-pressure connecting rod 3 has an upper high-pressure spring 4, a filter carbon rod 5, and a lower high-pressure spring 8 arranged sequentially along the axial direction within its accommodating cavity. The upper end of the upper high-pressure spring 4 abuts against the upper end of the accommodating cavity, and the lower end of the upper high-pressure spring 4 abuts against the upper end of the filter carbon rod 5. The lower end of the lower high-pressure spring 8 elastically abuts against the conductive mounting seat 6 of the spark plug 7, and the upper end of the lower high-pressure spring 8 abuts against the lower end of the filter carbon rod 5. Together, they form an elastic mechanical fixing structure.

[0024] The secondary coil, upper high-voltage spring 4, filter carbon rod 5, lower high-voltage spring 8, and conductive mounting base 9 are connected in series to form a continuously conductive electrical connection path.

[0025] In the example, the two ends of the filter carbon rod 5 are connected to the upper and lower high-voltage springs via conductive connectors 9, achieving both elastic mechanical and electrical connections. This facilitates assembly.

[0026] In the example, the filter carbon rod has an outer diameter of 6-8 mm and a length of 10-20 mm.

[0027] In the example, the elastic stiffness of the upper high-pressure spring is greater than that of the lower high-pressure spring, and the preload applied by the upper high-pressure spring to the filter carbon rod is greater than the supporting force of the lower high-pressure spring, so that the filter carbon rod maintains a stable axial position.

[0028] The filter carbon rod 5 has a rod structure, which is integrally formed by extruding carbon fiber monofilaments with a binder. The outer surface of the rod has a continuous nickel plating layer, with nickel accounting for 40%–50% of the total mass of the filter carbon rod. The diameter of the carbon fiber monofilaments is 5–10 μm. These carbon fiber monofilaments belong to the small tow category, and mainstream brands include Toray Industries (T700, T800), Mitsubishi Chemical (M40J, M60J), Hercules (IM7, IM9), Zhongfu Shenying (SY45S), and Jilin Carbon Valley (JLG-12K). The effective aspect ratio for application is typically controlled between 10:1 and 50:1 to ensure dispersibility and composite performance.

[0029] An example of the manufacturing method of the filter carbon rod is as follows: S1 involves uniformly mixing carbon fiber monofilaments (7µm in diameter, with an aspect ratio of approximately 30:1) with phenolic resin binder at a weight ratio of 3:1. The S2 mixture is placed in an extruder and extruded through a die into cylindrical rods with a diameter of 7 mm and a length of 15 mm, and then thermosetting (e.g., the die temperature is set to 160℃~190℃). S3 uses an electroplating process to plate nickel onto the surface of the rod, so that the nickel content accounts for about 45% of the total mass of the carbon rod; after drying, the carbon rod is obtained.

[0030] The specific process parameters for this example are as follows: Surface treatment: The carbon rod substrate is subjected to chemical degreasing and roughening, stannous chloride sensitization, and palladium chloride activation treatment in sequence; The electroplating solution used is Watt's nickel plating solution (NiSO4·6H2O 250~300g / L, NiCl2 40~60g / L, H3BO3 35~45g / L); The carbon rod is obtained by electrodepositing a nickel layer uniformly over the substrate surface under the following conditions: current density of 1.5 A / dm², temperature of 50–55 °C, and pH of 4.0–4.5. After drying, the carbon rod exhibits a shielding effectiveness of up to 45 dB against electromagnetic radiation in the 30 MHz–1 GHz frequency band.

[0031] The aforementioned filter carbon rod 5 is embedded between the upper and lower conductive connectors 9 in the accommodating cavity of the high-voltage connecting rod 3. The upper high-voltage spring 4 and the lower high-voltage spring 8 achieve stable axial pre-tightening positioning of the filter carbon rod 5, while the accommodating cavity achieves radial positioning of the filter carbon rod 5. It forms a series circuit with the ignition coil and spark plug.

[0032] The embodiments of the present invention disclosed above are merely illustrative of the invention. The embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and describes these embodiments in conjunction with the accompanying drawings to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. However, the invention can be implemented in many ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the invention. Therefore, the invention is limited only by the claims and their full scope and equivalents, and not by the specific embodiments disclosed.

Claims

1. An automotive engine ignition coil with magnetic field shielding function, comprising a plug, an ignition coil consisting of a primary coil and a secondary coil, and a high-voltage connecting rod; the conductive terminals of the plug are electrically connected to the primary coil; the high-voltage connecting rod has an accommodating cavity extending axially along its body, and a conductive mounting seat for a spark plug is provided at its lower end; characterized in that, The high-voltage connecting rod has an upper high-voltage spring, a filter carbon rod, and a lower high-voltage spring arranged sequentially along the axial direction within its accommodating cavity. The upper end of the upper high-voltage spring abuts against the upper end of the accommodating cavity, and the lower end abuts against the upper end of the filter carbon rod. The lower end of the lower high-voltage spring abuts against the conductive mounting seat of the spark plug, and the upper end abuts against the lower end of the filter carbon rod. The secondary coil, upper high-voltage spring, filter carbon rod, lower high-voltage spring, and conductive mounting seat are connected in series to form a continuous conductive electrical connection path. The filter carbon rod is formed by extruding carbon fiber monofilaments and binder, and is nickel-plated to form a continuous conductive and magnetic surface. The nickel content accounts for 40% to 50% of the total mass of the filter carbon rod. The diameter of the carbon fiber monofilament is 5 to 10 μm, and the aspect ratio of the carbon fiber monofilament is 10:1 to 50:

1.

2. The automotive engine ignition coil with magnetic field shielding function as described in claim 1, characterized in that, The filter carbon rod has an outer diameter of 6-8 mm and a length of 10-20 mm.

3. The automotive engine ignition coil with magnetic field shielding function as described in claim 1, characterized in that, The elastic stiffness of the upper high-pressure spring is greater than that of the lower high-pressure spring, and the preload applied by the upper high-pressure spring to the filter carbon rod is greater than the supporting force of the lower high-pressure spring, so that the filter carbon rod maintains a stable axial position.

4. The automotive engine ignition coil with magnetic field shielding function as described in claim 1, characterized in that, The two ends of the filter carbon rod are respectively connected to the upper and lower high-pressure springs through conductive connectors, achieving both elastic mechanical and electrical connections.

5. A method for manufacturing a filter carbon rod, comprising the following steps: S1. Carbon fiber monofilaments are uniformly mixed with an appropriate amount of binder. The diameter of the carbon fiber monofilaments is 5-10 μm and the aspect ratio of the carbon fiber monofilaments is 10:1-50:

1. The S2 mixture is placed in an extruder, extruded into rods through a die, and then thermosetting. S3 performs nickel plating on the outer surface of the filter carbon rod, so that the nickel content accounts for 40% to 50% of the total mass of the filter carbon rod; after drying, the filter carbon rod is obtained.

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