Grounding device

Abstract

To provide a grounding device capable of suppressing a noise current generated in a component from flowing toward a connected metal structure.SOLUTION: A grounding device provided in a component mounted on a vehicle includes a first ground wire electrically connecting the component and a body of the vehicle, and a second ground wire electrically connecting the component and the body in parallel with the first ground wire and resonating at a resonance frequency of a metal structure mounted on the vehicle and connected to the component.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an earthing device that implements measures to cause earthing line resonance in order to suppress radiation noise caused by resonance of a metal structure. [Background technology]

[0002] Patent Document 1 discloses a medical device that can reduce power line noise to comply with EMC conducted noise regulations and also reduce leakage current to comply with leakage current regulations. In this medical device, components such as converters and inverters are connected to the device GND (power supply ground) by earth wires to reduce noise generated by the components, and a noise filter is inserted between the power line and the device GND to reduce noise propagated from the components to the power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-052155 Summary of the Invention [Problem to be solved by the invention]

[0004] In vehicle construction, there are cases where a self-resonating metal structure is attached to a part of the vehicle body to which the earth wire is connected, such as when a metal structure called an engine muffler is connected to a part called an engine, or when a metal structure called a rear drive shaft is connected to a part called a motor generator (MGR).

[0005] With such a structure, at frequencies at which the metal structure self-resonates, noise currents generated in the components flow not to the earth wire but to the metal structure, which has a lower impedance than the earth wire, resulting in the problem of high radiation noise being generated from the metal structure.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an earthing device that can prevent noise currents generated in components from flowing toward connected metal structures. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of the disclosed technology is an earthing device provided on a component mounted on a vehicle, the earthing device comprising: a first earth wire that electrically connects the component to the vehicle body; and a second earth wire that electrically connects the component to the body in parallel with the first earth wire and resonates at the resonant frequency of a metal structure mounted on the vehicle that is connected to the component. [Effects of the Invention]

[0008] According to the earthing device of the present disclosure, an earth wire (second earth wire) that resonates at the resonant frequency of the metal structure is additionally provided in parallel with the earth wire (first earth wire) that connects the component and the body, thereby preventing noise current generated in the component from flowing toward the metal structure and suppressing the generation of radiated noise. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view illustrating a structural example of a vehicle provided with an earthing device according to an embodiment of the present disclosure; [Figure 2] FIG. 1 is a diagram illustrating an electrical connection structure between the earthing device and a vehicle. [Figure 3] Example of the correspondence between the resonance frequency of a metal structure and the impedance of an earthing device DETAILED DESCRIPTION OF THE INVENTION

[0010] The earthing device disclosed herein is configured such that, when earthing is performed on an engine connected to a muffler in a vehicle, an auxiliary earth wire that resonates at the resonant frequency of the muffler is provided in parallel with the main earth wire connecting the engine housing to the vehicle body. With this configuration, noise currents generated at frequencies below the resonant frequency of the muffler are allowed to flow to the vehicle body via the main earth wire, and noise currents generated at the resonant frequency of the muffler are allowed to flow to the vehicle body via the auxiliary earth wire. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [structure] Fig. 1 is a view showing an example of the structure of a vehicle 100 provided with a grounding device 200 according to an embodiment of the present disclosure, seen from above the vehicle 100 through a body 130. The vehicle 100 shown in Fig. 1 includes an engine 110, a muffler 120, and the grounding device 200. Fig. 2 is a schematic diagram for explaining the electrical connection structure between the grounding device 200 and the vehicle 100.

[0012] The engine 110 is an internal combustion engine that is a power source for the vehicle 100, and is one of the components mounted on the vehicle 100.

[0013] Muffler (engine muffler) 120 is a metal structure (part of a component) connected to a component called engine 110. This muffler 120 is a component that is responsible for reducing noise and suppressing exhaust gas when exhaust gas is discharged from engine 110 to the outside of vehicle 100. Muffler 120 has a natural resonant frequency that self-resonates.

[0014] The earthing device 200 is a device for providing body earthing to a component mounted on the vehicle 100, which in this embodiment is the engine 110. The earthing device 200 is composed of a first earth wire 210 (earth wire) and a second earth wire 220 (resonant earth wire) that are provided in parallel.

[0015] The first ground wire 210 is, for example, a wire harness (WH) made up of a plurality of electric wires bundled together. The first ground wire 210 is provided so as to electrically connect the housing of the engine 110 (0V reference of the components, housing GND) and a metal part of the body 130 of the vehicle 100 (0V reference of the body, body GND).

[0016] The second earth wire 220 is, for example, a wire harness (WH) that bundles together a plurality of electric wires each having a predetermined capacitor 221. Similar to the first earth wire 210, the second earth wire 220 is provided to electrically connect the housing of the engine 110 and a metal vehicle part in the body 130 of the vehicle 100, but is configured to resonate at the resonance frequency of the muffler 120 connected to the engine 110.

[0017] Fig. 3 shows an example of the correspondence relationship between the resonant frequency of muffler 120, which is a metal structure, and the impedance of earthing device 200. As shown in Fig. 3, it can be seen that the impedance of second earth wire 220 at the resonant frequency is lower than the impedance of first earth wire 210 due to the action of capacitor 221. As an example, it is desirable that the impedance (resistance value) of second earth wire 220 at the resonant frequency be 1 Ω or less.

[0018] Due to this impedance characteristic, noise current generated inside the engine 110 flows to the body 130 of the vehicle 100 via the first earth wire 210 at frequencies (low frequencies) lower than the resonant frequency of the muffler 120 (band (1) in Figure 3), and flows to the body 130 of the vehicle 100 via the second earth wire 220, which has a lower impedance than the first earth wire 210, at the resonant frequency (at resonance) of the muffler 120 (band (2) in Figure 3).

[0019] <Actions and Effects> As described above, according to the earthing device 200 of one embodiment of the present disclosure, the property of noise current flowing through a path with low impedance is utilized to add a second earth wire 220 that resonates at the resonant frequency of the muffler 120 (metal structure) connected to the engine 110 (component) in parallel with the first earth wire 210 that is originally provided.

[0020] This earth structure allows noise currents generated at frequencies lower than the resonant frequency of the muffler 120 (metal structure) to flow to the body 130 of the vehicle 100 via the first earth wire 210, which has low impedance at that low frequency, while noise currents generated at the resonant frequency of the muffler 120 (metal structure) can flow to the body 130 of the vehicle 100 via the second earth wire 220, which has low impedance at that resonant frequency.

[0021] Therefore, noise current is less likely to flow from engine 110 (component) to muffler 120 (metal structure), and radiation noise generated from muffler 120 (metal structure) can be reduced.

[0022] In the above embodiment, the engine 110 is a metal structure and the muffler 120 is used as an example of the component. However, other than this combination, for example, the same application as above is possible even when the motor generator is a component and the rear drive shaft is a metal structure. [Industrial Applicability]

[0023] The earthing device of the present disclosure can be used in vehicles and the like that are equipped with parts to which metal structures are connected (having metal structures). [Explanation of symbols]

[0024] 100 vehicles 110 Engine 120 Muffler 130 Body 200 Earthing Device 210 First ground wire 220 Second Earth Wire 221 Capacitor

Claims

1. An earthing device provided on a component mounted on a vehicle, a first ground wire electrically connecting the component and the vehicle body; a second ground wire that electrically connects the component and the body in parallel with the first ground wire and resonates at a resonance frequency of a metal structure mounted on the vehicle and connected to the component, Earthing device.

2. the second ground wire includes a capacitor for providing a lower impedance than the first ground wire at a resonance frequency of the metal structure; The earthing device according to claim 1 .

3. The component is an engine, and the metal structure is an engine muffler. The earthing device according to claim 1 or 2.

4. The component is a motor generator, and the metal structure is a rear drive shaft. The earthing device according to claim 1 or 2.

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