JP2022076062A - Earth structure - Google Patents

Abstract

To provide an earth structure which can secure the degree of freedom of an earth connection position of an electrical component and a power source mounted on a vehicle and obtain the noise reduction effect.SOLUTION: An earth structure 100 comprises a conductor plate 101 which is earth-connected with a battery 1 and an electrical component supplied with power from the battery 1 and which is electrically insulated from a body 110. A plurality of slits 101S are formed with an interval in the direction along a peripheral part of the conductor plate 101 in the peripheral part of the conductor plate 101.SELECTED DRAWING: Figure 1

Description

The present invention relates to a ground structure for a vehicle.

A first area provided with the first device and a second area provided with the second device for the purpose of suppressing the influence of noise between the devices grounded to the vehicle body. There is known a vehicle body member provided with an obstructing member that inhibits the transmission of high frequencies at the boundary with the ground (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-215842

In the vehicle body member described in Patent Document 1, the region where noise is transmitted in the body can be limited, but the noise itself cannot be reduced. Further, in order to limit the region where noise is transmitted in the body, the ground connection position is limited to the noise transmission limiting region, and the degree of freedom of the ground connection position is impaired.

In view of the above circumstances, it is an object of the present invention to provide a grounding structure capable of ensuring a degree of freedom in the grounding connection position of electrical components and power supplies mounted on a vehicle and obtaining a noise reduction effect.

The ground structure of the present invention includes a conductor in which a power source and an electrical component supplied from the power source are connected to the ground and are electrically insulated from the vehicle body, and a plurality of slits are provided on the peripheral edge of the conductor. It is formed at intervals in the direction along the portion.

According to the present invention, since a plurality of slits are formed at the peripheral edge of the conductor at intervals along the peripheral edge, the degree of freedom in the ground connection position of the electrical components and the power supply mounted on the vehicle is ensured, and at the same time, the degree of freedom is secured. A noise reduction effect can be obtained.

FIG. 1 is a plan view showing a ground structure for a vehicle according to an embodiment of the present invention. FIG. 2 is a diagram showing a simulation model for confirming the effect of the ground structure shown in FIG. FIG. 3 is a graph showing the results of a simulation for confirming the effect of the ground structure shown in FIG. FIG. 4 is a diagram showing a simulation result of a current distribution when an electromagnetic field analysis is performed on a “normal” conductor plate. FIG. 5 is a diagram showing a simulation result of a current distribution when the conductor plate of the simulation model shown in FIG. 2 is subjected to electromagnetic field analysis. FIG. 6 is a diagram showing a ground structure for a vehicle according to another embodiment of the present invention. FIG. 7 is a plan view showing a ground structure for a vehicle according to another embodiment of the present invention.

Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the embodiments shown below, and can be appropriately modified without departing from the spirit of the present invention. Further, in the embodiments shown below, some parts of the configuration are not shown or explained, but the details of the omitted techniques are within the range where there is no contradiction with the contents described below. Needless to say, publicly known or well-known techniques are applied as appropriate.

FIG. 1 is a plan view showing a ground structure 100 for a vehicle according to an embodiment of the present invention. As shown in this figure, the ground structure 100 includes a conductor plate 101 mounted on the body 110 of the vehicle 10. The body 110 is a body panel or a skeleton member formed of a conductive reinforcing fiber and a resin, and is, for example, a floor panel formed of a carbon fiber reinforced resin or a glass fiber reinforced resin.

The conductor plate 101 is a plate-shaped or sheet-shaped conductor, and is arranged so as to face the body 110. The negative electrode of the battery 1 is grounded to the conductor plate 101 via the ground cable 2, and electrical components (not shown) such as vehicle accessories supplied from the positive electrode of the battery 1 are connected to the ground cable 3. It is grounded via. The conductor plate 101 is, for example, a steel plate. The negative electrode of the alternator as a power source may be grounded to the conductor plate 101 via the ground cable 2, and the positive electrode of the alternator may supply power to the electrical components.

The conductor plate 101 extends in the vehicle front-rear direction and the vehicle width direction. The connection portion 101A to which the ground cable 2 is connected is arranged on the front side of the vehicle and on the right side in the vehicle width direction, while the connection portion 101B to which the ground cable 3 is connected is located on the rear side of the vehicle and on the left side in the vehicle width direction. It is arranged.

The conductor plate 101 is electrically insulated from the body 110 by being mounted on the body 110 which is a resin body. Further, both the upper and lower surfaces and the peripheral portion of the conductor plate 101 are electrically insulated from other components of the vehicle 10. As a result, the current flowing from the electrical components to the conductor plate 101 through the ground cable 3 flows to the negative electrode of the battery 1 through the ground cable 2 without flowing to the components of the vehicle 10 around the conductor plate 101.

Here, a plurality of slits 101S are formed on the peripheral edge of the conductor plate 101. The conductor plate 101 has four sides, and a plurality of slits 101S are formed on each side of the conductor plate 101. A plurality of slits 101S formed on each side of the conductor plate 101 are arranged at equal intervals along each side, and extend linearly from each side in the in-plane direction. In this embodiment, each slit 101S is perpendicular to each side of the conductor plate 101.

It is not essential that the conductor plate 101 has a large area so that one conductor plate 101 corresponds to the entire vehicle 10, and a plurality of conductor plates 101 correspond to the entire vehicle 10 or one. The area and the number of conductor plates 101 may be set so that the conductor plate 101 of the above corresponds to a part of the vehicle 10 (for example, the right half). When the conductor plate 101 is provided so as to correspond to a part of the vehicle 10, the connection position of the ground cable 3 including high frequency noise may be set at the position where the conductor plate 101 is provided.

As shown by the arrows in the figure, the high frequency signal mainly flows along the peripheral edge of the conductor plate 101 on which the slit 101S is formed. As a result, the effect of reducing high frequency noise can be obtained. This point will be described below.

FIG. 2 is a diagram showing a simulation model for confirming the effect of the ground structure 100 shown in FIG. In the simulation model shown in this figure, the conductor plate 101 is a rectangular flat plate made of iron. Further, in this simulation model, the connection portion 101A of the ground cable 2 (see FIG. 1) connected to the negative electrode of the battery 1 (see FIG. 1) is set in the upper left of the figure of the conductor plate 101, and is an electrical component (not shown). The connection portion 101B of the ground cable 3 connected to (omitted) is set at the lower right in the figure of the conductor plate 101. Further, in this simulation model, six slits 101S are set at equal intervals on the long side of the conductor plate 101, and three slits 101S are set at equal intervals on the short side of the conductor plate 101.

Here, the high frequency signal tends to flow on the end face of the conductor due to the skin effect. Therefore, when a high-frequency signal is passed through the conductor plate 101, the high-frequency signal mainly flows along the peripheral edge of the conductor plate 101. When the slit 101S is not formed on the peripheral edge of the conductor plate, the path length of the high frequency signal is close to the sum of the length of one long side and the length of one short side of the conductor plate. On the other hand, when a high-frequency signal is passed through the conductor plate 101 represented by the simulation model shown in FIG. 2, the high-frequency signal follows a meandering path mainly connected to the peripheral edge of the conductor plate 101 and the edge of the slit 101S. It will flow along. Therefore, the path length of the high frequency signal is longer than that of the conductor plate in which the slit 101S is not formed. As a result, the attenuation effect of the high frequency signal on the conductor plate 101 on which the slit 101S is formed becomes larger than the attenuation effect of the high frequency signal on the conductor plate on which the slit 101S is not formed. Therefore, the effect of reducing high frequency noise in the conductor plate 101 in which the slit 101S is formed is larger than the effect of reducing high frequency noise in the conductor plate in which the slit 101S is not formed.

Further, as shown in an enlarged manner in FIG. 2, a high frequency signal flowing in the first direction (direction of arrow A in the figure) along the slit 101S and a second direction (direction of arrow B in the figure) along the slit 101S. The high frequency signal flowing in the direction is opposite to that of the high frequency signal flowing in the first direction, and the high frequency noise flowing in the first direction and the high frequency noise flowing in the second direction are close to each other at the same frequency, the same level, and opposite phases. As a result, the effect of canceling the magnetic flux is generated between the high frequency signal flowing in the first direction and the high frequency signal flowing in the second direction, and the effect of reducing high frequency noise can be obtained.

In this simulation, the attenuation characteristic (S21 characteristic) between the connection portion 101B (input) and the connection portion 101A (output) (between input and output) and the current distribution in the conductor plate 101 are confirmed.

FIG. 3 is a graph showing the results of a simulation for confirming the effect of the ground structure 100 shown in FIG. “Normal” shown in this graph is a damping characteristic when a conductor plate in which the slit 101S is not formed is used. The “straight_slit” shown in this graph is the damping characteristic of the simulation model shown in FIG.

From the results shown in the graph of FIG. 3, it can be confirmed that the attenuation characteristic of the simulation model shown in FIG. 2 has a higher degree of deterioration than the attenuation characteristic of "normal" in the high frequency region of several MHz or more. .. That is, it can be confirmed that the noise reduction effect of the simulation model shown in FIG. 2 is larger than the noise reduction effect of "normal" in the high frequency region of several MHz or more.

On the other hand, it can be confirmed that there is no difference between the attenuation characteristics of the simulation model shown in FIG. 2 and the attenuation characteristics of "normal" in the low frequency region. That is, it can be confirmed that in the low frequency range, it functions as a normal DC GND without any loss.

FIG. 4 is a diagram showing a simulation result of a current distribution when an electromagnetic field analysis is performed on a “normal” conductor plate. FIG. 5 is a diagram showing a simulation result of a current distribution when the conductor plate 101 of the simulation model shown in FIG. 2 is subjected to electromagnetic field analysis. These figures show that the hatch density increases as the amount of current increases. Further, FIGS. 4 and 5 show the current distribution when a 10 MHz signal is passed through the conductor plate.

From FIG. 4, it can be confirmed that the high frequency signal flows mainly along the end face of the conductor, specifically along the peripheral edge of the conductor plate. On the other hand, from FIG. 5, in the conductor plate 101 on which the slit 101S is formed, the amount of current near the center of the conductor plate 101 is increased as compared with the simulation result shown in FIG. 4, and the peripheral edge of the conductor plate 101 is increased. It can be confirmed that the current is difficult to flow in the section.

As described above, according to the ground structure 100 of the present embodiment, since a plurality of slits 101S are formed on the peripheral edge of the conductor plate 101 at intervals along the peripheral edge, the electrical components and the battery 1 are grounded. It is possible to reduce high frequency noise itself without being restricted by the connection position. Further, the noise reduction effect can be adjusted by adjusting the shape, size and number of the slits 101S.

FIG. 6 is a diagram showing a ground structure 200 for a vehicle according to another embodiment of the present invention. The same components as those in the above-described embodiment are designated by the same reference numerals, and the description of the above-mentioned embodiments will be incorporated.

As shown in FIG. 6, the ground structure 200 includes a J-shaped or hook-shaped slit 201S instead of the linear slit 101S of the above-described embodiment. The shape of the slit 201S may be L-shaped instead of J-shaped. That is, it is not essential to include the third portion S3 described later. The slit 201S includes a first portion S1 extending in-plane at a right angle from the peripheral edge portion of the conductor plate 201, a second portion S2 extending parallel to the peripheral edge portion from the tip of the first portion S1, and the second portion. It is composed of a third portion S3 extending from the tip of the portion S2 of the second portion toward the peripheral edge portion.

As shown enlarged in the figure, the high-frequency signal flowing along the peripheral edge of the conductor plate 201 and the high-frequency signal flowing along the second portion S2 and the third portion S3 have opposite signal flow directions. Become. Further, the high frequency noise flowing along the peripheral edge portion of the conductor plate 201 and the high frequency noise flowing along the second portion S2 and the third portion S3 are close to each other at the same frequency, the same level, and the opposite phase. As a result, a magnetic flux canceling effect is generated between the high frequency signal flowing along the peripheral edge of the conductor plate 201 and the high frequency signal flowing along the second portion S2 and the third portion S3, and the effect of reducing high frequency noise is achieved. Will be increased.

Further, by making the slit 201S curved like a J-shape or a hook shape, a high high-frequency noise reduction effect can be obtained while suppressing the length from the peripheral portion of the slit 201S in the in-plane direction. Will be possible.

FIG. 7 is a plan view showing a ground structure 300 for a vehicle according to another embodiment of the present invention. The same components as those in the above-described embodiment are designated by the same reference numerals, and the description of the above-mentioned embodiments will be incorporated.

As shown in FIG. 7, the ground structure 300 includes a conductor 320 mounted on the body 310 of the vehicle 11. The body 310 is a body panel or skeleton member formed of a conductor such as metal, and is, for example, a floor panel made of steel.

The conductor 320 includes a conductor plate 101 and an insulating material 322 that covers the periphery of the conductor 101, and is arranged so as to face the body 310. The conductor 320 is, for example, FPC (Flexible Printed Circuits), and the insulating material 322 is, for example, a resin.

An insulating material 322 is interposed between the conductor plate 101, which is a conductor, and the body 310, which is a conductor. Further, the slit 101S is filled with the insulating material 322. As a result, the lower surface of the conductor plate 101, the peripheral edge portion, and the edge portion of the slit 101S are electrically insulated from the body 310. Further, the upper surface of the conductor plate 101 is also covered with the insulating material 322, and the upper surface of the conductor plate 101 is also electrically insulated from the surrounding conductors.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and changes may be made without departing from the spirit of the present invention. May be combined.

For example, in the above embodiment, a plurality of slits 101S and 201S are formed on the peripheral edges of the conductor plates 101 and 201 provided on the bodies 110 and 310, but a part of the body is electrically insulated from the surroundings. As a conductor, a power supply and an electrical component may be connected to the conductor by ground, and a plurality of slits may be formed at the peripheral edge of the conductor.

1: Battery (power supply)
10: Vehicle 11: Vehicle 100: Earth structure 101: Conductor plate (conductor)
101S: Slit 110: Body (body)
200: Earth structure 201: Conductor plate (conductor)
201S: Slit 300: Earth structure 310: Body (body)
320: Conductor 322: Insulator

Claims (3)

The power supply and the electrical components supplied from the power supply are grounded and provided with a conductor electrically isolated from the vehicle body.
A ground structure in which a plurality of slits are formed at a peripheral portion of the conductor at intervals in a direction along the peripheral portion. The ground structure according to claim 1, wherein the slit extends linearly or curvedly from the peripheral edge of the conductor toward the in-plane direction of the conductor. The grounding structure according to claim 1 or 2, further comprising an insulating material interposed between the conductor and the vehicle body.

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