JP2012104352A - Wire harness and shield wire connecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire harness and a shield wire connecting method which are capable of effectively suppressing surge voltage.SOLUTION: When an inverter 11 and a motor 12 are connected using a shield wire 1, a wire harness 10 provided with resistive elements 6 electrically connected to a braided shield wire 5 of the shield wire 1 is used to connect the braided shield wire 5 of the shield wire 1 and grounds of the inverter 11 and the motor 12 via the resistive elements 6.

Description

  The present invention relates to a method for connecting a wire harness and a shielded electric wire, and more particularly to a wire harness and a method for connecting a shielded electric wire that are preferably used for connecting an inverter and a motor.

  Conventionally, when an inverter is used to drive a motor, the inverter 101 and the motor 102 are connected by a shielded electric wire 103 as shown in FIG. In general, the shielded electric wire 103 is covered with an insulator around the conductor, and the outer periphery of the insulator is covered with a shield material such as a braided shield wire.

  When the motor 102 is rotated in the connection state shown in FIG. 8A, the relationship between the voltage at the connection point (point A) between the shielded wire 103 and the motor 102 (hereinafter referred to as output voltage) and time is shown in the graph of FIG. It is like this. As shown in FIG. 9, when the motor 102 starts rotating immediately after the power is turned on, the voltage fluctuates up and down and a large surge voltage is generated. This surge voltage is one transient phenomenon, and the voltage fluctuation becomes smaller and converges with time.

  As shown in FIG. 9, when a large surge voltage is generated at the beginning of the rotation of the motor, a voltage higher than a specified voltage is applied to the motor 102. Such a large voltage may cause damage due to a short circuit at a connection portion between the shielded electric wire 103 and the motor 102, wiring inside the motor 102, or the like.

  The connection shown in FIG. 8A can be represented by a circuit diagram shown in FIG. 8B when the shielded electric wire 103 is considered as a part of the electric circuit. As shown in the figure, the shielded electric wire 103 between the inverter 101 and the motor 102 is configured as an electric wire capacitance 103C with a wire resistance 103R, an electric wire inductance 103L, and a gap between the conductor and the braid serving as a capacitor.

  In other words, when the power is turned on, the shielded wire 103 is presumed to have a large surge voltage due to voltage fluctuation due to resonance between the wire inductance 103L and the capacitance 103C of the capacitor.

  As a method for reducing the surge voltage when power is turned on, a surge suppression cable is known (see, for example, Patent Document 1). In this surge suppression cable, the drive insulation core consisting of multiple wires and the high-frequency leakage current return line are closely adjacent to each other in the vicinity of the drive insulation core, and at the same time arranged in parallel in the length direction and twisted. A sheath is applied to the outside without a seal.

International Publication W2008 / 041708 Pamphlet

  Since the conventional shielded electric wire (surge suppression cable) described in Patent Document 1 can reduce the wire inductance, the surge voltage can be reduced to some extent. However, since the wire capacitance component remains, resonance cannot be completely eliminated. Therefore, the generation of the surge voltage could not be completely prevented.

  The present invention has been made to solve the above-described drawbacks of the prior art, and an object of the present invention is to provide a wire harness and a shielded wire connecting method capable of effectively suppressing a surge voltage.

  In order to solve the above-mentioned problem, the wire harness of the present invention is a wire harness using a shielded electric wire in which a conductor is covered with an insulator and a periphery of the insulator is covered with a shield. The gist is that a resistor is connected to the body for connection to an external ground.

  In the wire harness, the resistor is preferably made of a plate material.

  In the wire harness, the resistance value of the resistor is preferably larger than the resistance value of the shield body.

  In the wire harness, the resistor is preferably made of SUS304.

  The shielded wire connecting method of the present invention is a shielded wire connecting method in which a conductor is covered with an insulator and the insulator is covered with a shield. Are connected using a resistor.

  In the method for connecting the shielded wires, it is preferable that the resistor is made of a plate material.

  In the connection method of the shielded wire, it is preferable that the resistance value of the resistor is larger than the resistance value of the shield.

  Moreover, as for the connection method of the said shield wire, it is preferable that the said resistor consists of SUS304.

  The wire harness of the present invention is a wire harness using a shielded electric wire in which the conductor is covered with an insulator and the insulator is covered with a shield body, and is connected to the shield body with an external ground. By adopting the configuration in which the resistor is connected, the wire capacitance component generated in the shielded wire can be canceled by the resistor, and resonance between the wire inductance component and the wire capacitance component can be prevented. By absorbing the surge voltage of the shielded electric wire, it is possible to prevent the voltage applied to the device such as the motor with respect to the input voltage from greatly fluctuating up and down even immediately after the power is turned on. In the wire harness of the present invention, there is no possibility that an excessive voltage is applied to a connected device or the like to damage the device, and the device can be operated safely.

  The shielded wire connecting method of the present invention is the shielded wire connecting method in which the conductor is covered with an insulator and the insulator is covered with the shield. By adopting the method of connecting the resistors using the resistor, the wire capacitance component generated in the shielded wire can be canceled by the resistor and the resonance between the wire inductance component and the wire capacitance component can be prevented. As a result, it is possible to absorb the surge voltage of the shielded wire and prevent the voltage applied to the device such as the motor with respect to the input voltage from greatly fluctuating even immediately after the power is turned on. According to the method for connecting shielded wires of the present invention, there is no possibility that an excessive voltage is applied to the connected device or the like and the device is damaged, and the device can be operated safely.

It is explanatory drawing which shows an example of this invention. It is an enlarged view of the shielded electric wire terminal of FIG. It is the sectional view on the AA line of FIG. It is the enlarged view of a shielded wire terminal which shows the other example of this invention. It is the BB sectional view taken on the line of FIG. It is a circuit diagram at the time of using this invention for the connection of an inverter and a motor. It is a graph which shows the relationship between the voltage at the time of driving a motor using this invention for the connection of an inverter and a motor, and time. (A) is explanatory drawing which shows the usage example of the conventional shielded electric wire, (b) is a circuit diagram of (a). It is a graph which shows the relationship between the voltage at the time of driving a motor using the conventional shield electric wire, and time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an example of the present invention. The connecting method of the shielded wire shown in FIG. 1 is that when the shielded wire 1 is used to connect an external device 11 (for example, an inverter) and an external device 12 (for example, a motor), the braided shielded wire 5 ( The shield 6) and the ground of the casings of the devices 11 and 12 connected by the shielded electric wire 2 are connected by the resistor 6.

  2 is an enlarged view of the shielded wire terminal of FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. As shown in FIG. 3, the shielded electric wire 1 includes a shield body in which the conductor 2 is covered with an insulator 3 and the insulator 3 is composed of a braided shield wire 5 as shown in FIGS. 2 and 3. It has the structure covered with.

  Further, as shown in FIGS. 2 and 3, a double ring 9 comprising an inner metal ring 7 and an outer metal ring 8 covering the periphery thereof is caulked to the insulator 3 at the end of the shielded electric wire 1. ing. The double ring 9 is attached to the shielded electric wire 1 with the braided shield wire 5 sandwiched between the inner ring 7 and the outer ring 8. Although the shielded electric wire 1 is not particularly illustrated, the conductor 2 is electrically connected to predetermined terminals of the devices 11 and 12.

  The resistor 6 shown in FIGS. 2 and 3 is composed of four resistors 6 (6a, 6b, 6c, 6d) made of SUS springs. Each resistor 6a-6d is attached to the predetermined position of the apparatus 12 so that the circumference | surroundings of the double ring 9 may be surrounded. Each resistor 6a-6d is arrange | positioned at equal intervals on the circumference | surroundings of the shield electric wire 1 as shown in FIG. 3, and is being fixed to the apparatus 12 with the set screw.

  Each resistor 6 a to 6 d surrounds the periphery of the double ring 9 of the shielded electric wire 1, is pressed against the double ring 9 by a spring force, and is connected to the shielded electric wire 1. The resistor 6 is in contact with the surface of the ring 8 outside the double ring 9. Since the double ring 9 is connected to the braided shield wire 5, the braided shield wire 5 and the resistor 6 are in an electrically connected state. On the other hand, the device 12 side of the resistor 6 is in contact with a ground such as a housing and is conductive. The braided shield wire 5 of the shield wire 1 and the ground of the device 12 are electrically connected via a resistor 6. The double ring 9 and the device 12 are insulated from each other, and the braided shield wire 5 and the device 12 are electrically connected only through the resistor 6.

  In the above description, the ground connection between the shielded electric wire 1 and the device 12 has been described. However, as shown in FIG. And the ground of the device 111 are connected via the resistor 6.

  The conductor 2 of the shielded electric wire 1 can be a conductor wire generally used for this type of shielded electric wire. Specific conductors 2 include, for example, a single wire such as copper, a copper alloy, and aluminum, a plurality of wires, a plurality of stranded wires, and the like.

As the insulator 3 of the shielded electric wire 1, an insulator generally used for this type of shielded electric wire can be used. Specific examples of the insulator 3 include polyolefin resins such as polyethylene, vinyl chloride resins, and the like.

As the braided shield wire 5 of the shielded electric wire 1, one used as a braided wire of this kind of general shielded electric wire can be used. Specific braided shield wire 5 includes, for example, copper, copper alloy, aluminum and the like.

The resistor 6 for connecting the shielded electric wire 1 and the grounds of the devices 11 and 12 can be used as long as it functions as an electric resistance. It is preferable to use a resistor 6 having a resistance value larger than that of the braided shield wire 5 from the viewpoint of surely preventing resonance. The resistor 6 preferably has a resistance value of 10Ω or more. The resistance value of the resistor 6 is more preferably 100Ω or more. The upper limit of the resistance value of the resistor 6 is preferably 10 KΩ or less. A more preferable upper limit of the resistance value of the resistor is 1 KΩ or less.

The resistance value of the resistor 6 is the resistance between the braided shield wire 5 and the devices 11 and 12 in a state where the braided shield wire 5 is connected to the ground of the devices 11 and 12 via the resistor 6. It is the electrical resistance (at room temperature) obtained by measuring the value.

As a material used for the resistor 6, various metal materials can be used. Examples of the material of the resistor include metal materials such as iron, iron-chromium alloy, iron-chromium-nickel alloy, and nickel-chromium. Among these materials, stainless steel such as SUS304 is a common material and is a preferable material because it is easily available. Stainless steel can be made lighter when compared to iron when the resistance value is the same.

The resistor 6 can be formed to have a desired resistance value by appropriately selecting the shape, cross-sectional area, resistivity of the material itself, and the like.

The shape of the resistor 6 is not limited to this shape, although the spring body is used in the embodiment shown in FIGS. 2 and 3. As the resistor 6, for example, a plate-like body, a wire, or the like can be used. For example, when the shape of the resistor 6 is a plate-like body, there is an advantage that the protrusion for punching can be formed by pressing or the like to form the locking protrusion. When the locking projection is formed on the resistor 6, it is easy to lock the resistor 6 on the surface of the braided shield wire 5 using the locking projection.

The connection between the resistor 6 and the shielded electric wire 1 may use a method other than a mode in which the resistor 6 is biased and connected to the shielded electric wire 1 by a spring force as described above. Specifically, a wire harness in which the resistor 6 is connected and integrated in advance to the terminal of the shielded electric wire 1 by an appropriate means such as welding or caulking is used, and the device 11, 12 may be connected. In the wire harness, the resistor 6 is attached in a state of being electrically connected to the braided shield wire 5.

The double ring 9 can use metals, such as copper, iron, stainless steel, for example.

FIG. 4 shows an example of the wire harness of the present invention, and is an explanatory view showing a terminal portion connected to the device, and FIG. 5 is a cross-sectional view taken along the line BB of FIG. The wire harness 10 shown in FIGS. 4 and 5 has the double ring 9 attached to the end of the shielded electric wire 1 in the same manner as the shielded electric wire 1 shown in FIGS. Two resistors 6 and 6 for connection to an external ground are connected by welding. The wire harness 10 shown in FIG.4 and FIG.5 is the same as the aspect shown in FIG.2 and FIG.3 since the structure of the shielded electric wire 1, the double ring 9, etc. is abbreviate | omitted description. Further, the resistor 6 has the same material shape as described with reference to FIGS.

The braided shield wire 5 of the wire harness 10 and the ground of the device 12 are electrically connected via the resistor 6 by fixing the resistor 6 to the ground of the housing of the device 11 with a set screw or the like. Can be kept in a state.

The connection between the resistor 6 and the devices 11 and 12 is not limited to the connection using a set screw or the like, and various connection methods can be used. Examples of the connection method include a metal spring and soldering.

  FIG. 6 is a circuit diagram when the shielded electric wire 1 and the resistor 6 are viewed as part of the circuit when the inverter and the motor are connected using the connection method of the present invention shown in FIG. In the circuit diagram of FIG. 6, the shielded wire 1 between the inverter 11 and the motor 12 has a wire resistance 1R, a wire inductance 1L, and a gap formed by the insulator 3 between the conductor 2 and the braided shield wire 5 becomes a wire capacitance 1C. ing. The resistor 6 provided between the braided shield wire 5 and the devices 11 and 12 can be shown as a resistor 6R connected in series to the wire capacitance 1C. FIG. 3 corresponds to the circuit diagram of FIG. 6B using a conventional shielded wire. The circuit diagram of FIG. 3 is different from the circuit diagram of FIG. 8B in that the wire resistance 6R by the resistor 6 is connected to the wire capacitance 1C.

  When the connection method of the present invention provided with the resistor 6 as shown in FIG. 6 is used, the wire capacitance 1C is compared with the case where the shielded wire without the resistor shown in FIG. 8A is used. The resistance 6R of the resistor 6 can be canceled out. In this way, in the circuit shown in FIG. 6, since the wire capacitance 1C is suppressed from resonating with the wire inductance 1L, generation of a surge voltage due to resonance can be prevented.

  FIG. 7 is a graph showing the relationship between voltage and time when the motor is driven using the connection method of the present invention shown in the circuit diagram of FIG. In FIG. 7, the voltage output from the inverter 11 shown in FIG. 6 is shown as “input voltage” to the motor 12, and the voltage at the connection point (point A) between the shielded electric wire 1 and the motor 12 in FIG. As shown. As shown in the graph of FIG. 7, by using a method of connecting the braided shield wire and the earth of the device via a resistor, the generation of a surge voltage is prevented, and the voltage fluctuation is substantially equal to the input voltage from the beginning of power-on. A flat output voltage with no noise can be obtained. As described above, according to the present invention, the output voltage to the device when the power is turned on does not greatly fluctuate up and down, and the generation of the surge voltage can be suppressed. Therefore, an excessive voltage is not input to a device such as a motor connected to a power source such as an inverter by a shielded wire, and the device can be safely operated while preventing damage to the device.

  Since the resistor 6 is previously connected to the shielded electric wire 1 and attached to the shielded electric wire 1, the wire harness of the present invention is easy to connect the shielded electric wire and the earth of the device.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above aspect, the braided shield wire 5 is used as the shield body of the shielded electric wire 1. However, the shield body may be a material having shielding performance, and a material other than the braided shield wire may be used. Examples of the material having a shielding performance that can be used as such a shield body include copper, a copper alloy, and aluminum.

Further, in the above embodiment, the shielded electric wire 1 having a single core wire is described as an example. However, in the connection method of the present invention, a multi-core shielded electric wire in which a plurality of core wires are arranged is used. You may connect with.

Moreover, you may use what gave tin plating to copper and a copper alloy as a shield body. When tin plating is applied, the standard potential difference is reduced and electric corrosion can be suppressed.

INDUSTRIAL APPLICABILITY The present invention can be optimally used as a wire harness for connecting between an inverter and a motor, and a method for connecting shielded wires.

1 shielded wire 2 conductor 3 insulator 5 braided shield wire 6 resistor 10 wire harness 11 equipment (inverter)
12 Equipment (motor)

Claims (8)

  A wire harness using a shielded wire in which a conductor is covered with an insulator and a periphery of the insulator is covered with a shield, and a resistor for connecting to an external ground is connected to the shield. A wire harness characterized by   The wire harness according to claim 1, wherein the resistor is made of a plate material.   The wire harness according to claim 1 or 2, wherein a resistance value of the resistor is larger than a resistance value of the shield body.   The wire harness according to any one of claims 1 to 3, wherein the resistor is made of SUS304.   In the method for connecting a shielded wire in which the conductor is covered with an insulator and the insulator is covered with a shield, the shield of the shielded wire and an external ground are connected using a resistor. A characteristic shielded wire connection method.   The shielded wire connection method according to claim 5, wherein the resistor is made of a plate material.   The method for connecting shielded wires according to claim 5 or 6, wherein a resistance value of the resistor is larger than a resistance value of the shield.   The method for connecting shielded wires according to claim 5, wherein the resistor is made of SUS304.

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