Power plug

Abstract

To provide a power plug that can eliminate or reduce noise with a simple configuration without increasing the size or weight of charging cables, etc. [Solution] A power plug 3 in which a first metal plate 10 interposed between the first plug blade portion 7 and the power line L, and a second metal plate 11 interposed between the ground terminal portion 8 and the ground line G are arranged parallel to each other, and a dielectric 12 is sandwiched between these first metal plate 10 and second metal plate 11 to form a noise filter 13. Since a capacitor is formed by interposing metal plates 6 and 7 between the plug blade portion 7 and the ground terminal portion 8 and the cables L and G that are conductive to them, the overall structure can be made smaller and lighter.

Description

Technical Field

[0001] The present invention relates to a power plug inserted into a power outlet, and particularly to a power plug provided in a charging cable or the like for charging an electric vehicle.

Background Art

[0002] Electric vehicles such as battery electric vehicles (BEVs) and plug-in hybrid vehicles (PHEVs) supply power for driving from an in-vehicle battery to a motor. Therefore, since the cruising range of an electric vehicle is limited by the remaining charge (SOC) of the battery, the battery has been increased in capacity to increase the cruising range per charge. In addition, in order to shorten the charging time, increasing the power during charging has been considered. As technical problems when charging an electric vehicle, heat generation and noise generation due to contact resistance and tracking phenomena between the outlet and the plug are known. Regarding heat generation, the temperature is detected by a thermistor, and the current is controlled based on the detection signal. In a charging cable equipped with a controller, a thermistor is provided in the power plug, and the detection signal is sent to the controller to control the charging current. In that case, since it is desirable for the thermistor to accurately detect the temperature of the power plug, in the power cable described in Patent Document 1, the power plug is configured such that the thermistor is located above the plug blade in a state where the power plug is connected to the power outlet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The power cable described in Patent Document 1 has a configuration to deal with heat generation, but it cannot reduce the noise that inevitably occurs during charging. Normal mode noise and common mode noise are known to occur during charging. Of these, common mode noise is difficult to counter due to its complex propagation pattern, but it is said that it can be removed or reduced by using shielded wires. However, electric vehicle charging cables are often handled by ordinary people in homes and charging stations in urban areas, so they need to be lightweight and easy to handle, as well as low-cost. Therefore, charging cables with added shielding for noise reduction have the disadvantage of being thicker and heavier overall due to the addition of the shielding.

[0005] This invention was made in view of the above-mentioned technical problems, and aims to provide a power plug that can eliminate or reduce noise with a simple configuration without increasing the size or weight of charging cables, etc. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a power plug having at least one pair of plug blades, a first plug blade portion and a second plug blade portion, a ground terminal portion for grounding, a first cable that is conductive to the first plug blade portion, a second cable that is conductive to the second plug blade portion, and a third cable that is conductive to the ground terminal portion, characterized in that a first metal plate is interposed between any of the first plug blade portion and the second plug blade portion and the ground terminal portion and any of the first cable, the second cable, and the third cable that is conductive to any of the first plug blade portion and the second plug blade portion and the ground terminal portion, and a second metal plate is interposed between any of the other of the first plug blade portion and the second plug blade portion and the ground terminal portion and any of the other of the first cable, the second cable, and the third cable that is conductive to any of the other of the first plug blade portion and the second plug blade portion and the ground terminal portion, and a dielectric is sandwiched between the first metal plate and the second metal plate, so that a noise filter is formed by the first metal plate, the second metal plate and the dielectric.

[0007] In the present invention, the noise filter is further housed in an electrically insulating housing that holds the first plug blade portion, the second plug blade portion, and the ground terminal portion in a state where they protrude toward the tip side, and the noise filter is housed inside the housing, and the first plug blade portion and the first cable are connected inside the housing, the second plug blade portion and the second cable are connected, and the ground terminal portion and the third cable are connected.

[0008] In the present invention, the first metal plate is interposed between the first plug blade and the first cable, and the second metal plate is interposed between the second plug blade and the second cable, and a thermistor may be attached to either the first metal plate or the second metal plate. [Effects of the Invention]

[0009] According to the present invention, a capacitor is formed by the first and second metal plates and the dielectric between them, which functions as a filter that removes or reduces noise. Since these metal plates are provided between either the plug blade portion and the ground terminal portion and the corresponding cable, forming a noise filter, the noise filter is built into the power plug, which in turn allows the power plug to be made smaller and lighter, and consequently, the charging cable with the power plug can be made easier to handle.

[0010] Furthermore, by connecting the above-mentioned metal plates to the first and second plug blade sections to form a noise filter, and by attaching a thermistor to either of the metal plates, the temperature difference at each plug blade section becomes small due to heat transfer by the dielectric. As a result, the temperature can be accurately or precisely detected with a single thermistor, and consequently, the number of thermistors and other components required can be reduced, making the power plug smaller or lighter. [Brief explanation of the drawing]

[0011] [Figure 1] This is a side view showing an example of a charging cable to which the present invention can be applied. [Figure 2] This is a front view of the power plug. [Figure 3] This is a schematic cross-sectional view showing the internal structure of a power plug. [Figure 4] This is a cross-sectional view along the line IV-IV in Figure 1. [Figure 5] This is a schematic cross-sectional view similar to Figure 3, illustrating another example of the present invention. [Figure 6] This is a schematic cross-sectional view showing the configuration with a thermistor added to the configuration shown in Figure 5. [Modes for carrying out the invention]

[0012] Next, embodiments of the present invention will be described with reference to the attached drawings. Note that the embodiments described below are merely examples of how the present invention can be implemented and do not limit the invention.

[0013] Figure 1 shows a charging cable 1 to which the present invention can be applied. The charging cable 1 shown here is a "Mode 2" cable, in which a power plug 3 is provided at one end of the cable section 2, a charging connector 4 is provided at the other end opposite to it, and a controller 5 is provided in the middle of the cable section 2. The power plug 3 is configured to be plugged into a power outlet of a charger (not shown), and as shown in the front view of Figure 2, it has two plug blades 6 and 7 for hot and cold, and a ground terminal 8 for grounding. The power plug 3 is housed in a housing 9 made of an electrically insulating material such as synthetic resin, and the plug blades 6 and 7 and the ground terminal 8 are held by the housing 9 in a state where they protrude toward the tip from the housing 9.

[0014] Figure 3 shows a schematic cross-sectional view illustrating the internal structure of the power plug 3. The cross-section shown here is obtained by cutting through a plane passing through one of the plug blades 7, which corresponds to the first plug blade, and the ground terminal 8. The plug blade 7, the ground terminal 8, and the plug blade 6, which corresponds to the second plug blade (not shown in Figure 3), have their longitudinal intermediate portions embedded (molded) in a material such as resin that makes up the housing 9, and are held in the housing 9. The rear ends are inside the housing 9, to which metal plates 10 and 11 are connected, respectively.

[0015] The metal plates 10 and 11 are essentially conductive plate-shaped members, and may be solid plate-shaped metals such as busbars. In principle, they may also be members in which the surface of some plate-shaped member is covered with a highly conductive material. These metal plates 10 and 11 are fixed inside the housing 9, arranged parallel to each other with a predetermined distance between them. A suitable dielectric material 12 is sandwiched between the metal plates 10 and 11. The dielectric material may be any known suitable material, such as ceramic, synthetic resin, or mica, with solid dielectric materials being particularly preferred. Thus, these metal plates 10 and 11 and the dielectric material 12 constitute a capacitor and act as a noise filter 13.

[0016] A power line L, corresponding to the first cable, is connected to a metal plate 10 that is electrically connected to the plug blade portion 7, and a ground line G, corresponding to the third cable, is connected to a metal plate 11 that is electrically connected to the ground terminal portion 8. The connections may be made by any appropriate method, such as crimping, welding, soldering, or screwing. Therefore, the metal plate 10 corresponding to the first metal plate is interposed between the plug blade portion 7 and the power line L, making them electrically connected. Similarly, the metal plate 11 corresponding to the second metal plate is interposed between the ground terminal portion 8 and the ground line G, making them electrically connected. Although not shown in Figure 3, a power line N, corresponding to the second cable, is electrically connected to another plug blade portion 6 corresponding to the second plug blade portion. The power lines L, N and the ground line G are collectively covered by a sheath and form part of the cable portion 2, which is connected to the controller 5 mentioned above. Furthermore, a signal line CPLT, which transmits control signals (control pilot signals: CPLT signals), runs through the inside of cable section 2. This configuration is schematically shown in a cross-sectional view in Figure 4.

[0017] In the above power plug 3 according to the present invention, some signals that return through the ground, the housing 9, etc. become noise (common mode noise or common noise). However, since the charges in the above capacitor change when some of these signals return, the noise is removed or reduced. In particular, in the power plug 3 described above, a capacitor composed of metal plates 10, 11 and a dielectric 12 is formed between the plug blade portion 7 or the power line L and the ground terminal portion 8 or the ground line G, so that common noise can be removed or reduced. Further, the power plug 3 according to the present invention described above has a configuration in which metal plates 10, 11 are interposed between the plug blade portion 7 or the ground terminal portion 8 and the power line L or the ground line G that is respectively conductive, and the dielectric 12 is sandwiched between these metal plates 10, 11. Therefore, it is possible to obtain a small and lightweight power plug 3 in which a capacitor or the like is accommodated inside the housing 9. As a result, according to the power plug 3 of the present invention, a charging cable with little noise and easy to handle can be obtained.

[0018] Incidentally, the power plug 3 of the present invention can also be configured to handle normal noise. An example thereof is shown in FIG. 5, which is a schematic cross-sectional view similar to FIG. 3. In the configuration shown in FIG. 5, for example, another metal plate 14 is arranged in parallel with the metal plate 10 connected to the plug blade portion 7 on the cold side, and this metal plate 14 is connected to the plug blade portion 6 on the hot side, for example. The other metal plate 14 may have the same configuration as the metal plates 10 and 11 described above. And a dielectric 15 is sandwiched between these metal plates 10 and 14 to form a capacitor. That is, a noise filter 16 is provided between each of the plug blade portions 6 and 7, or between the power line L and the other power line N. Other configurations are the same as those described above.

[0019] In the example shown in FIG. 5, since a capacitor is provided between the power lines, the noise generated by the power supply can be bypassed, and thereby the noise (normal mode noise) can be removed or reduced. Also, similar to the example shown in FIG. 3, it is possible to obtain a small and lightweight power plug 3 in which a capacitor or the like is accommodated inside the housing 9.

[0020] The power plug 3 according to the present invention can be provided with a configuration for protection from heat generation, similar to the conventional one. FIG. 6 shows an example in which a thermistor 17 for limiting current based on temperature is provided. FIG. 6 is a cross-sectional view schematically showing an example in which the thermistor 17 is added to the configuration shown in FIG. 5 described above. The thermistor 17 is disposed on the back surface (the surface opposite to the dielectric 15 side) of one metal plate (for example, the metal plate 10 connected to the plug blade portion 7 on the cold side) via a fixing portion 18 on a sheet made of an electrical insulator. This thermistor 17 is connected to the controller 5 described above.

[0021] When heat is generated due to contact resistance or tracking phenomenon during charging, the heat of one plug blade portion 7 is transmitted to the thermistor 17 through the metal plate 10 connected thereto, and its temperature is detected by the thermistor 17 as an increase in its resistance value. Also, the heat of the other plug blade portion 6 is transmitted to the metal plate 14 connected thereto, and further transmitted to the thermistor 17 through the dielectric 15 and one metal plate 10. That is, since the dielectric 15 functions as a heat transfer medium, the thermistor 17 receives the heat from the other plug blade portion 6, detects its temperature, and outputs a detection signal as an increase in the resistance value. That is, in the configuration shown in FIG. 6, even if two plug blade portions 6 and 7 that may generate heat are provided, a capacitor is provided between them, and the thermistor 17 is attached to one of the metal plates constituting the capacitor. Therefore, only one thermistor 17 as a detection unit sensitive to temperature is sufficient. Therefore, in the power plug 3 according to the present invention, the required components can be reduced, and in this regard, miniaturization, weight reduction, and cost reduction can be achieved.

[0022] Note that the present invention is not limited to the above-described specific examples, and the charging cable to which the present invention can be applied may be a "Mode 1" cable or a "Mode 3" cable. Also, in the present invention, as long as each plug blade portion or ground terminal portion and the metal plate are electrically connected, each plug blade portion or ground terminal portion and the metal plate may be integrally formed as a single member. [Explanation of symbols]

[0023] 1 Charging cable 2 Cable section 3 Power plug 4 Charging connector 5 Controllers 6,7 Plug blade section 8. Ground terminal section 9 Housing 10,11,14 Metal plate 12,15 Dielectrics 13,16 Noise filter 17 Thermistor 18 Fixed part CPLT signal line G Ground Line L,N power line

Claims

1. A power plug having at least one pair of plug blades, a first plug blade and a second plug blade, a ground terminal for grounding, a first cable connected to the first plug blade, a second cable connected to the second plug blade, and a third cable connected to the ground terminal, A first metal plate interposed between the first plug blade portion, the second plug blade portion, and the ground terminal portion, and between the first cable, the second cable, and the third cable which are electrically connected to the first plug blade portion, the second plug blade portion, and the ground terminal portion, A second metal plate interposed between the first plug blade portion, the second plug blade portion, and the ground terminal portion, and the first cable, the second cable, and the third cable, which are electrically connected to the first plug blade portion, the second plug blade portion, and the ground terminal portion, and They are arranged parallel to each other, and A dielectric material is sandwiched between the first metal plate and the second metal plate, A noise filter is formed by the first metal plate, the second metal plate, and the dielectric. A power plug characterized by the following features.

2. A power plug according to claim 1, The present invention further comprises an electrically insulating housing that holds the first plug blade portion, the second plug blade portion, and the ground terminal portion in a state where they protrude toward the tip side, The noise filter is housed inside the housing. Inside the housing, the first plug blade is connected to the first cable, the second plug blade is connected to the second cable, and the ground terminal is connected to the third cable. A power plug characterized by the following features.

3. A power plug according to claim 1 or 2, The first metal plate is interposed between the first plug blade and the first cable, and the second metal plate is interposed between the second plug blade and the second cable. A thermistor is attached to either the first metal plate or the second metal plate. A power plug characterized by the following features.

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