A method for solving EMC electromagnetic interference of motor vehicle and ship speakers and speaker

Abstract

This invention discloses a method for addressing electromagnetic interference (EMC) in motor vehicle and marine horns, and a horn. In one embodiment, the horn includes at least one capacitor with a total capacitance of approximately 220-10,000 microfarads connected in parallel to the horn's power input terminal to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling. This embodiment effectively addresses the issue of severely exceeding the limits for conducted and radiated emissions in certain frequency bands when testing the horn according to CIRS25. It also addresses the issue of horn damage caused by high-frequency, high-current injection interference testing (BCI) and interference pulse injection testing according to ISO7637.

Description

Technical Field

[0001] The present invention relates to motor vehicle and ship horns, and in particular to electromagnetic compatibility (EMC) in motor vehicle horns. Background Art

[0002] Currently, 90% of the world's motor vehicle horns are electromechanical. Their advantages are low cost, but their disadvantages are short lifespan and severe electromagnetic interference. In the past, when cars had few electronic devices, this disadvantage was negligible and insignificant. With the passage of time, the number of onboard electronic devices has increased dramatically, expanding from the original radio to include engine control, anti-lock brakes, steering control, door and window control, air conditioning control, body control, information systems, and many other areas. Due to electromagnetic interference, existing horns not only interfere with radios and televisions, but in some models, honking the horn can cause the vehicle to automatically shift gears, start or stop the air conditioning, and even more seriously, temporarily disable the ABS braking system, significantly impacting driving safety.

[0003] To address this issue, electronic car horns emerged in the 1980s. While electronic horns offer significant EMC improvements over electromechanical horns, they are inherently limited by cost and space, making them ineffective at suppressing electromagnetic interference generated by the horn's solenoid coil. Furthermore, during Bulk Current Injection (BCI) testing, high-frequency, high-current injection interference (ICI) testing can cause the horn's oscillation system to malfunction or even stop oscillating at certain frequencies, potentially damaging the horn.

[0004] During the switching of on-board electrical equipment, such as the motor or ignition system, transient interference caused by the distributed capacitance and inductance of the wiring harness can cause the speaker's conducted emissions (CE, i.e., conducted electromagnetic emissions) and radiated emissions (RE, i.e., radiated electromagnetic interference) to seriously exceed certain frequency bands when tested according to CIRS25. This can even damage the speaker during the BCI high-frequency, high-current injection interference test and the interference pulse injection test specified in the ISO7637 standard. Consequently, automakers have no choice but to accept this. Substandard speaker EMC has become a major challenge for the electronic speaker industry.

[0005] Since the speaker is a fully enclosed metal shell, it is grounded whether it is being tested or installed in the vehicle. Therefore, about 95% of the conducted emission and radiated emission interference is leaked from the speaker power supply terminal. The existing speakers have seriously exceeded the international standard CIRS25 conducted emission and radiated emission standards in EMC electromagnetic compatibility tests. Figure 3To this end, electronic speaker manufacturers have tried various methods to absorb and suppress the high-frequency electromagnetic interference generated by the speakers during operation. The following are some common methods.

[0006] The first method involves using capacitors across the speaker electromagnet coils, the primary source of interference. However, increasing the capacitance beyond a certain point bypasses the audio pulses driving the speaker electromagnets. This increases the speaker drive current but reduces the electromagnet drive power, resulting in no significant improvement in interference suppression. Consequently, the speaker becomes unusable due to reduced sound quality.

[0007] The second method is to use series capacitors and resistors at both ends of the speaker driving electromagnet coil, which is the main interference source, to absorb it. Although this will reduce the current of the audio pulse string that drives the speaker electromagnet flowing through the capacitor and resistor bypass, and reduce the increase in the speaker driving current, it cannot be used because it does not effectively improve the interference suppression effect.

[0008] The third method involves installing transient diodes or fast recovery diodes across the speaker's electromagnet coil to absorb the current. However, due to the freewheeling effect of the diode switch, this increases the speaker's drive current while reducing the electromagnet's drive power. This results in excessive power consumption and reduced sound quality, rendering the speaker unusable. While adding a series resistor to the diode can somewhat reduce the increase in drive current, it doesn't effectively improve interference suppression, making it unusable.

[0009] The fourth type is that since the working current of the speaker is 2-6A, the conventional method is to install an inductor and a high-frequency capacitor below 1 microfarad and a magnetic ring filter at the power input end. However, due to their large size, they cannot be installed in the speaker and do not effectively improve the interference suppression effect, so they cannot be used.

[0010] Various methods similar to the above mentioned ones are used to absorb the back electromotive force of the coil. In the final analysis, they are all attempts to solve the CIRS25 interference failure problem by suppressing absorption. However, due to poor results, the EMC indicators of the speakers always fail to meet the CIRS25 standards. Summary of the Invention

[0011] The object of the present invention is to provide a circuit that can overcome the above-mentioned disadvantages.

[0012] In a first aspect, embodiments of the present invention provide an electronic or electromechanical horn for use in motor vehicles or marine applications, comprising at least one capacitor having a total capacitance of approximately 220 to 10,000 microfarads connected in parallel to the horn's power input terminal to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling. The total capacitance of the capacitor is preferably 470 to 6,000 microfarads, and more preferably 1,000 to 4,000 microfarads.

[0013] In a second aspect, embodiments of the present invention provide an electronic or electromechanical horn for use in motor vehicles or marine applications, comprising at least one capacitor connected in parallel across a horn power supply, wherein the capacitor has a capacitance sufficiently large to ensure an internal resistance below a threshold relative to the horn's operating frequency. The threshold is approximately 2Ω, preferably below 1Ω, and more preferably below 0.5Ω.

[0014] In a third aspect, embodiments of the present invention provide a method for eliminating electromagnetic interference from electronic or electromechanical horns for vehicles and ships. The method comprises connecting at least one capacitor with a total capacitance of approximately 220 to 10,000 microfarads in parallel to the horn's power input terminal to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling. The total capacitance of the capacitor is preferably approximately 470 to 6,000 microfarads, and more preferably approximately 1,000 to 4,000 microfarads.

[0015] In a fourth aspect, embodiments of the present invention provide a method for eliminating electromagnetic interference from electronic or electromechanical horns used in vehicles and ships. The method comprises connecting at least one capacitor in parallel across a horn power supply. The capacitor is sufficiently large to ensure that its internal resistance relative to the horn's operating frequency is less than a threshold. The threshold is approximately 2Ω, and preferably, the capacitor's internal resistance is less than 1Ω, and more preferably, less than 0.5Ω.

[0016] In a fifth aspect, embodiments of the present invention provide an electronic device for use in a motor vehicle or vessel, comprising at least one capacitor having a total capacitance of approximately 220 to 10,000 microfarads connected in parallel to a power input terminal to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling. The total capacitance of the capacitor is preferably approximately 470 to 6,000 microfarads, and more preferably approximately 1,000 to 4,000 microfarads.

[0017] In a sixth aspect, an embodiment of the present invention provides a method for eliminating electromagnetic interference in electronic equipment used in motor vehicles and ships, comprising connecting at least one capacitor with a total capacity of approximately 220-10,000 microfarads in parallel at the power input end of the electronic equipment to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling.

[0018] In a seventh aspect, embodiments of the present invention provide a motor vehicle comprising an electronic device and at least one capacitor connected in parallel to a power supply terminal or circuit of the electronic device, wherein the capacitor has a sufficiently large capacitance, with a total capacitance of approximately 220 to 10,000 microfarads, to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling. The total capacitance of the capacitor is preferably approximately 470 to 6,000 microfarads, and more preferably approximately 1,000 to 4,000 microfarads.

[0019] In an eighth aspect, embodiments of the present invention provide a method for eliminating electromagnetic interference in a vehicle or vessel, wherein the vehicle or vessel includes electronic equipment. The method comprises connecting at least one capacitor in parallel to a power supply terminal or circuit of the electronic equipment. The capacitor has a sufficiently large capacity, with a total capacity of approximately 220 to 10,000 microfarads, to eliminate electrical interference caused by electromagnetic radiation, conduction, and coupling. The total capacity of the capacitor is preferably approximately 470 to 6,000 microfarads, and more preferably approximately 1,000 to 4,000 microfarads.

[0020] The embodiment of the present invention effectively solves the problem of serious over-limit of some frequency bands of conducted emission and radiated emission of the loudspeaker when tested according to CIRS25. It also solves the problem of even causing damage to the loudspeaker during the BCI high-frequency large current injection interference test and the interference pulse injection test in the ISO7637 standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The motor vehicle horn according to an embodiment of the present invention;

[0022] Figure 2 This is the test graph for the 0.53-1.7MHz frequency band in the CIRS25 test when no capacitor of 220-10000 microfarads or more is added to the speaker power supply terminal;

[0023] Figure 3 This is the test graph of adding a 4400 microfarad capacitor to the speaker power supply end in the 0.53-1.7MHz frequency band in the CIRS25 test. DETAILED DESCRIPTION

[0024] The present invention is described below in detail, clearly, and completely with reference to the accompanying drawings and specific embodiments. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0025] Investigations and research have revealed that in the past, car horn manufacturers have used high-frequency suppression and absorption methods to address the problem of substandard high-frequency electromagnetic radiation from the speakers. However, this has always been ineffective. This is mainly because the standard for the interference level of conducted and radiated emissions generated by the speakers is very low, at 42dBuV. The internal resistance of conventional interference elimination devices is far from sufficient to effectively absorb low-amplitude conducted and radiated emissions.

[0026] After numerous tests and studies, the applicant has found that for electronic speakers of varying designs, simply connecting one or more capacitors with a total capacitance of 220 to 10,000 microfarads (capacitors of various types, including electrolytic capacitors) in parallel across the speaker power supply can completely resolve the issue of excessive CIRS25 radiation. Furthermore, significant improvements are seen in tests for RE (Radiated Emission), CE (Conducted Emission), and BCI (Bulk Current Injection), ensuring that all EMC indicators for the electronic speaker fully meet the standard. The total capacitance of the capacitors is preferably 470 to 6,000 microfarads, and more preferably 1,000 to 4,000 microfarads.

[0027] According to the capacitive reactance formula (Xc = 1 / (2πf C),) it can be seen that as long as the capacitance of the capacitor connected in parallel across the speaker power supply is large enough and its internal resistance relative to the speaker's operating frequency (300-600Hz) is below a certain threshold, as low as milliohms (mΩ), it can effectively short-circuit and absorb the various conducted and radiated emissions generated by the speaker's electromagnet. This threshold is approximately 2Ω. Preferably, the capacitor's internal resistance is less than 1Ω, and more preferably, less than 0.5Ω. At the same time, the suppression of high-frequency, high-current injection (BCI), as well as various interference caused by conduction and coupling, meets the requirements of CIRS25 and ISO7637 standards.

[0028] Figure 1 This is a motor vehicle horn according to an embodiment of the present invention. Figure 1 As shown, the motor vehicle horn includes a coil SP, and the oscillating circuit OSC provides a driving signal to the power amplifier circuit T1, which generates a power current signal. The power current signal is filtered by the capacitor C2 and then passes through the coil SP to make the horn sound.

[0029] By connecting at least one capacitor C1 with a total capacitance of approximately 220-10,000 microfarads in parallel to the speaker power input, electromagnetic radiation, conduction, and coupling-induced electrical interference are eliminated. In another example, the capacitance of the at least one parallel capacitor is large enough to reduce the internal resistance to milliohms (mΩ) relative to the speaker's operating frequency (300-600 Hz).

[0030] This example uses a 4400 microfarad high-frequency, low-resistance electrolytic capacitor, ensuring that all EMC indicators of the electronic speaker fully meet standards. Capacitors greater than 10,000 microfarads offer little improvement in electromagnetic radiation, and are relatively insignificant due to capacitor size and cost.

[0031] Figure 2This is the test graph of the 0.53-1.7 MHz frequency band speaker power supply without adding a 220-10000 microfarad capacitor in the CIRS25 test. Figure 2 As shown, the standard requires that the radiation should not exceed 42dBuV, but the actual maximum value has reached 87dBuV, which is seriously exceeded.

[0032] Figure 3 This is the test graph of adding a 4400 microfarad capacitor to the power supply end of the speaker in the 0.53-1.7 MHz frequency band in the CIRS25 test. The standard requires that the radiation should not exceed 42dBuV, and the actual maximum value is only 18dBuV, which is a very significant effect.

[0033] This method of eliminating conducted and radiated emissions interference by connecting one or more capacitors with a total capacitance of 220 to 10,000 microfarads in parallel across the power supply of an onboard terminal electronic device (equipment) is not only widely applicable to various electronic horns, but is also highly effective in eliminating conducted and radiated emissions interference from electromechanical horns, greatly expanding the application range of electromechanical horns. It can also be applied to various onboard electronic devices and equipment to eliminate conducted and radiated emissions interference. It can also be applied to the wiring harness connecting all electrical devices in a vehicle.

[0034] In another embodiment, in an electromechanical horn for automobiles or ships, at least one capacitor with a total capacitance of approximately 220 to 10,000 microfarads is connected in parallel to the horn's power input terminal to eliminate electromagnetic radiation, conduction, and electrical interference caused by coupling. The total capacitance of the capacitor is preferably 500 to 6,000 microfarads, and more preferably 1,000 to 4,000 microfarads.

[0035] In another embodiment, at least one capacitor with a total capacity of about 220-10,000 microfarads can be connected in parallel to the power input end of electronic equipment used in motor vehicles and ships to eliminate electromagnetic radiation and electrical interference caused by conduction and coupling.

[0036] In another embodiment, in a motor vehicle or ship including electronic equipment, at least one capacitor is connected in parallel to the power supply terminal or circuit of the electronic equipment, and the capacitance is large enough, with a total capacitance of about 220-10,000 microfarads, so as to eliminate electromagnetic radiation and electrical interference caused by conduction and coupling.

[0037] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electronic or electromechanical horn for motor vehicles or ships, characterized in that: It includes at least one capacitor with a total capacity of 220-10000 microfarads connected in parallel to the speaker power input end. The capacitor is used to eliminate the electromagnetic radiation generated by the speaker electromagnetic coil and leaked through the power supply terminal when the speaker is working, as well as the electrical interference caused by conduction and coupling.

2. The electronic or electromechanical horn for motor vehicles or ships according to claim 1, characterized in that: The total capacity of the capacitor is 500-6000 microfarads.

3. The electronic or electromechanical horn for motor vehicles or ships according to claim 2, characterized in that: The total capacity of the capacitor is 1000-4000 microfarads.

4. A method for eliminating electromagnetic interference from electronic or electromechanical horns for motor vehicles and ships, characterized in that: It includes connecting at least one capacitor with a total capacity of 220-10000 microfarads in parallel to the speaker power input end. The capacitor is used to eliminate the electromagnetic radiation generated by the speaker electromagnetic coil and leaked through the power supply terminal when the speaker is working, as well as the electrical interference caused by conduction and coupling.

5. The method according to claim 4, wherein The total capacity of the capacitor is 500-6000 microfarads.

6. The method according to claim 5, wherein The total capacity of the capacitor is 1000-4000 microfarads.

7. An electronic device used in a motor vehicle or ship, characterized in that: It includes at least one capacitor with a total capacity of 220-10000 microfarads connected in parallel at the power input end. The capacitor is used to eliminate the electromagnetic radiation generated by the speaker electromagnetic coil and leaked through the power supply terminal when the speaker is working, as well as the electrical interference caused by conduction and coupling.

8. The electronic device according to claim 7, wherein: The total capacity of the capacitor is 500-6000 microfarads.

9. The electronic device according to claim 8, wherein The total capacity of the capacitor is 1000-4000 microfarads.

10. A method for eliminating electromagnetic interference of electronic equipment used in motor vehicles and ships, characterized in that: It includes at least one capacitor with a total capacity of 220-10000 microfarads connected in parallel at the power input end of the electronic device. The capacitor is used to eliminate the electromagnetic radiation generated by the speaker electromagnetic coil and leaked through the power supply terminal when the speaker is working, as well as the electrical interference caused by conduction and coupling.

11. The method according to claim 10, wherein The total capacity of the capacitor is 500-6000 microfarads.

12. The method according to claim 11, wherein The total capacity of the capacitor is 1000-4000 microfarads.

13. A motor vehicle ship, characterized in that: It includes an electronic device and at least one capacitor connected in parallel in the power supply terminal or circuit of the electronic device, with a total capacity of 220-10000 microfarads. The capacitor is used to eliminate the electromagnetic radiation generated by the speaker electromagnetic coil and leaked through the power supply terminal when the speaker is working, as well as the electrical interference caused by conduction and coupling.

14. The motor boat according to claim 13, characterized in that: The total capacity of the capacitor is 500-6000 microfarads.

15. The motor boat according to claim 14, characterized in that: The total capacity of the capacitor is 1000-4000 microfarads.

16. A method for eliminating electromagnetic interference of motor vehicles and ships, characterized in that: The motor vehicle or vessel includes electronic equipment, and the method includes connecting at least one capacitor in parallel in the power supply terminal or circuit of the electronic equipment, with a total capacity of 220-10,000 microfarads. The capacitor is used to eliminate electromagnetic radiation generated by the horn electromagnetic coil and leaked through the power supply terminal when the horn is working, as well as electrical interference caused by conduction and coupling.

17. The method according to claim 16, wherein The total capacity of the capacitor is 500-6000 microfarads.

18. The method according to claim 17, wherein The total capacity of the capacitor is 1000-4000 microfarads.

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