JPH04335170A - Inspection method and device of wire harness - Google Patents

Abstract

PURPOSE:To easily perform a conduction check of the outside conductor of a shield wire and an earth circuit in a short time and to achieve highly reliable inspection. CONSTITUTION:A capacitor 51 is connected between a joint terminal 4 and an earth of a shield wire 1. A power source 52 for generating alternating current output voltage is connected between another terminal 10 connected to a core 8 of the shield wire 1 and the earth. The capacity of the capacitor 51 is set to that almost equal to the electrostatic capacity between the core wire 8 and an outside conductor 3 of the shield wire 1. The voltage across the capacitor 51 is amplified by an amplifier 53, converted into a specified signal form by convertor 54 and compared with a reference value by a comparator 55. A switch 56 is operated in accordance with a comparison result by the use of the comparator 55.

Description

Description: [0001] The present invention relates to a wire harness testing method and apparatus, and more particularly to a wiring harness testing method that can improve the efficiency of continuity testing of a ground circuit of a shielded wire. METHODS AND APPARATUS. 2. Description of the Related Art Shield wires used in wire harnesses are processed and incorporated into the harness as shown in FIG. That is, in FIG. 5, PVC (polyv
A shielded wire 1 covered with a sheath 2 such as inyl chloride is peeled off at both ends, and an outer conductor 3 constituting a shielding layer is pulled out at only one end and connected to earth via a joint terminal 4. It is connected to one end of the bond line 5. The earth bond wire 5 is made of a lead wire such as an AV wire (vinyl insulated wire for automobiles), and the other end thereof is connected to the earth terminal 6. The other end of the outer conductor 3 is cut off together with the outer sheath. A core wire 8 is disposed inside the outer conductor 3 via an internal insulator 7, the internal insulator 7 is peeled off at both ends, and terminals 9 and 10 are connected to both ends of the core wire 8, respectively. Terminals 9 and 10 are each set in a connector housing (not shown). In some cases, the outer conductor 3 may be connected to the earth terminal 6 by caulking directly without using the earth bond wire 5. A ground terminal 6 is connected from the lead-out portion of the outer conductor 3 through a joint terminal 4 and a ground bond wire 5.
The portion leading to the ground circuit is a ground circuit, and the exposed portions of the ground circuit, such as the lead-out portion of the outer conductor 3 and the joint terminal 4, are insulated by being wrapped with insulating tape. The shield wire 1 processed in this way is further bundled with other wires, wrapped with tape,
The exterior is made of corrugated material. By the way, after the wire harness has gone through the manufacturing process, it is subjected to a continuity check and an appearance check in the inspection process. A continuity check is performed to confirm that there are no disconnections, incorrect alignment, missing lines, etc. Next, an example of a wire harness checker used for such a continuity check will be described. The wire harness checker shown in FIG. 7 includes a controller 31, a demultiplexer 32, a multiplexer 33, a plurality of inverters 34, a plurality of pull-up resistors 35, and a plurality of check terminals 36. Each output of the demultiplexer 32 is connected to a plurality of check terminals 36 including terminals a, b, c, d, e, . . . via a plurality of inverters 34, respectively. Terminals a, b, c, d,
A plurality of check terminals 36 consisting of e, ... are connected to a plurality of resistors 3.
5, respectively, and are commonly connected to the power supply VCC. The outputs of the plurality of inverters 34 are connected to each input of the multiplexer 33, respectively. Each terminal a, b, c, d of the check terminal 36
, e, . . . terminals at both ends of the wire harness are connected in combinations corresponding to each other. In this case, for example, terminals a, b, and c correspond to wire number 1, and terminals d and e correspond to wire number 2. Taking the wire number 1 as an example, the inspection will be specifically explained. The circuit with wire number 1 is, for example, a circuit formed by a wire whose one end is connected to one terminal at one end of the wire harness and whose other end is commonly connected to two terminals at the other end of the wire harness. One terminal at the one end of the wire harness corresponding to wire number 1 is connected to terminal a, and two terminals at the other end of the wire harness are connected to terminals b and c. The circuit with wire number 2 is
For example, the circuit is formed by a wire having one end connected to one terminal at one end of a wire harness and the other end connected to one terminal at the other end of the wire harness. One terminal at the one end of the wire harness corresponding to wire number 2 is connected to the terminal d, and one terminal at the other end of the wire harness is connected to the terminal e. From the controller 31 to the demultiplexer 3
2, and one of the outputs of the demultiplexer 32 corresponding to any one of terminals a, b, and c connected to the circuit with wire number 1 is set to a high potential (hereinafter referred to as "H"). ), and the inverter 34 connects the terminals a, b and c.
Drop one of them to ground. If the circuit with wire number 1 is normal, terminals a and b
and c become a low potential (hereinafter referred to as "L"). If there is a break in the circuit with wire number 1, only one or two of terminals a, b, and c, for example, only terminals a and b, become "L". If it is short-circuited to a circuit of another wire number, for example, if it is short-circuited to a circuit of wire number 2, terminal a,
b, c, d and e all become "L". The multiplexer 33 receives the potentials of the terminals a, b, . . . and sends them to the controller 31. controller 3
1 compares the data given from the multiplexer 33 with normal data stored in advance corresponding to the data supplied to the demultiplexer 32, and if it matches the normal data, it is normal, and if they do not match, there is a disconnection or It is determined that a short circuit abnormality has occurred. [0012] Problems to be Solved by the Invention [0012] The core wires of ordinary electric wires and shielded wires have terminals protruding from both ends, and continuity can be checked using the above-mentioned wire harness checker in that state. The outer conductor 3 of the shield wire 1 is
Since only one end has a terminal, it is not possible to check the continuity of the outer conductor 3 and the ground circuit, especially in the vicinity of the joint terminal 4. Conventionally, the continuity of the outer conductor 3 of the shielded wire 1 and the ground circuit as shown in FIG. 5 was checked by the following method. (1) Connect a check electrode to the outer conductor 3 of the shielding layer on the terminal 10 side that is slightly peeking out from the cut-off point. (2) As shown in FIG. 6, the check electrode 21 is shaped like a needle, and the needle-shaped electrode 21 is pierced from the outside of the jacket 2 and connected to the outer conductor of the shielding layer. In FIG. 6, a lamp 22 and a DC power supply 23 are connected in series between the earth terminal 6 and the needle electrode 21, and the outer conductor 3 and the earth circuit are turned on/off depending on whether the lamp 22 is lit or not. Determine. However, all of these methods are unreliable and inefficient. Furthermore, the method of piercing the outer sheath 2 with a needle electrode as in (2) may cause a failure. Furthermore, on the outside of the shield wire,
If there is an exterior made of tape or corrugated material, the inspection must be performed through gaps in the exterior or by partially removing the exterior, making the inspection work extremely complicated. Furthermore, since the continuity check of the outer conductor 3 and the ground circuit is performed separately from the continuity check of other circuits such as the core wire by the wire harness checker, two steps are required for the checking operation. The present invention has been made in view of the above circumstances, and provides a wire that allows continuity checks of the outer conductor of a shielded wire and a ground circuit to be easily and quickly performed, and that also has high test reliability. The object of the present invention is to provide a harness inspection method and a device directly used for its implementation. Means for Solving the Problems [0017] A wire harness inspection method according to the present invention provides a grounding circuit for a shielded wire of a wire harness incorporating a shielded wire in which only one end of a shielding layer is connected to a grounding terminal. (a) A capacitance between the core wire of the shielded wire to be tested and the shielding layer is installed at the end of the shielded wire to be tested that is connected to the ground terminal of the shielding layer. (b) apply an AC voltage between the core wire of the shielded wire to be inspected and the other end of the capacitor; (c)
) The present invention is characterized in that the voltage generated between the terminals of the capacitor is determined to detect the presence or absence of a break in the ground circuit of the shielded wire to be inspected. The wire harness inspection device according to the present invention is a device directly used for carrying out the above method, and is a device for inspecting the shield of a wire harness incorporating a shield wire in which only one end of the shielding layer is connected to the ground terminal. In a wire harness testing device for testing the continuity of the ground circuit of a wire, one end is connected to the end of the shielded wire to be tested that is connected to the ground terminal of the shielding layer, and the core wire of the shielded wire to be tested and the shielding layer are connected to each other. A capacitor having a capacitance of approximately the same order as the capacitance between the capacitor and the power supply that applies an alternating current voltage between the core wire of the shielded wire to be inspected and the other end of the capacitor, and the terminals of the capacitor. The present invention is characterized by comprising a determination circuit that determines the voltage applied to the shielded wire to detect whether or not there is a disconnection in the ground circuit of the shielded wire to be inspected. [Operation] In the wire harness testing method according to the present invention, one end of the capacitor is connected to one end of the shielding layer of the shielded wire to be tested, and the core wire of the shielded wire to be tested and the other end of the capacitor are connected to each other. Since the presence or absence of a break in the ground circuit is detected by applying an alternating current voltage between the terminals of the capacitor and determining the voltage generated between the terminals of the capacitor, there is no need to remove the outer sheath, sheath, etc. of the shielded wire to be inspected. The workability of the continuity test of the ground circuit of the shielded wire is good, the test can be performed in a short time, and the test reliability is high. In the wire harness inspection apparatus according to the present invention, a capacitor having one end connected to one end of the shielding layer of the shielded wire to be inspected, and a capacitor having one end connected to the other end of the shielding layer of the shielded wire to be inspected and the other end of the capacitor. A simple configuration is provided by comprising a power source that applies an alternating voltage to the capacitor, and a determination circuit that determines the voltage generated between the terminals of the capacitor and detects whether or not there is a disconnection in the ground circuit of the shielded wire to be inspected. Since it can be tested almost in the same way as other ordinary circuits, the continuity test of the shielded wire ground circuit can be performed with good workability and in a short time, and is highly reliable. Moreover, since it has a simple configuration, it can be easily incorporated into a wire harness checker. [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a wire harness inspection device according to a first embodiment of the present invention. In FIG. 1, a CL is connected between the joint terminal 4 of the shielded wire 1 and the ground, similar to that shown in FIG.
A capacitor 51 having a capacitance of A power source 52 that generates an AC output voltage V0 is connected between the terminal 10 connected to the core wire 8 of the shielded wire 1 and the ground. The capacitance CL of the capacitor 51 is set to be approximately equal to the capacitance CS between the core wire 8 of the shield wire 1 and the outer conductor 3. The voltage across capacitor 51 is amplified by amplifier 53, converted from alternating current to direct current by converter 54, and further compared with a preset reference value by comparator 55. The comparator 55 switches the switch 5 according to the comparison result.
Operate 6. In the switch 56, both ends of the operating contact 56a are connected as a set of terminals to an appropriate terminal among terminals a, b, c, . . . of a wire harness checker similar to that shown in FIG. That is, in the wire harness checker, the ON/OFF state of the operating contact 56a is detected as conduction/non-conduction of the circuit. Terminals 9 and 10 at both ends of the core wire 8 of the shield wire 1 are connected to other terminals of the terminals a, b, c, . . . of a wire harness checker for continuity testing of the core wire 8. Next, the operation of the wire harness inspection apparatus constructed as described above will be explained. If there is no disconnection in the outer conductor 3 of the shielded wire 1 to be inspected and the ground circuit, an equivalent circuit as shown in FIG. 2 will be constructed. In FIG. 2, the capacitance CS between the core wire 8 of the shield wire 1 and the outer conductor 3 is
, the capacitance CL of the capacitor 51, and the output voltage VO of the power supply 52 are shown. At point A in the figure, a voltage VA as shown in Equation 1 below is generated. [Equation 1] VA = {CS / (CS + CL)} VO
By detecting this voltage VA, it is possible to know whether or not there is a break in the outer conductor 3 and the ground circuit. Specifically, the voltage at point A in the figure, that is, the terminal voltage of the capacitor 51, is amplified by an amplifier 53, converted from AC voltage to DC voltage by a converter 54, and then applied to a comparator 55 to obtain a preset standard. compared to the value. The comparator 55 operates the switch 56 to turn on the contact 56a when a voltage equal to or higher than the reference value is detected. If there is a break somewhere in the ground circuit, the voltage V at point A
Since A does not occur, switch 56 remains off. The switch output obtained from the contact 56a of the switch 56 is detected by the wire harness checker in the same way as continuity detection in other circuits, so it is very convenient to detect it as part of the continuity check. good. In such a configuration, it is only necessary to provide the capacitor 51, the power supply 52, and a circuit (amplifier 53, converter 54, comparator 55, switch 56, etc.) for determining the terminal voltage of the capacitor 51, and the shielded wire to be inspected Since there is no need to perform special processing such as removing the exterior or sheath, the circuit can be tested in the same way as a normal circuit.The workability of the test is good, and the test can be performed in a short time. Inspections can be performed using almost the same inspection process. In addition, higher reliability can be obtained than in the case where the inspection is performed by piercing the exterior, jacket, etc. from the outside with a needle-like electrode. In the embodiment shown in FIG. 1, the voltage V0 is constantly applied to the core wire 8 of the shielded wire 1 in order to test the earth circuit, so there is a possibility of interference with the test circuit of the core wire 8 itself. . Therefore, the second embodiment shown in FIG. 3 and the third embodiment shown in FIG. 4 are designed to prevent such interference. That is, in the configuration of FIG. 3, an OR circuit 61 is provided between the comparator 55 and the switch 56 in FIG. A switch 62 is provided, and the OR
The output of the circuit 61 is fed back to the input of this OR circuit 61 to form a self-holding circuit, and the output of this OR circuit 61 drives the switch 62. In this second embodiment, if there is no abnormality in the earth circuit as a result of checking the earth circuit, the contact output of the switch 56 is immediately given to the harness checker based on the output of the comparator 55 indicating the result. While the output state of the switch 56 is maintained, the output voltage of the power supply 52 is disconnected by the operation of the switch 62, and there is no adverse effect on the inspection of other circuits such as the core wire 8 of the same shielded wire 1. In the configuration of the third embodiment shown in FIG.
An OR circuit 6 is connected between the comparator 55 and the switch 56 in
1, and the terminal 10 of the shielded wire 1 to be inspected and the power supply 5
A switch 62 with a contact 62a inserted between it and 2 is provided,
Furthermore, a timer 63 for controlling this switch 62 and a timer switch 64 are provided in parallel with this timer 63. The timer 63 is for supplying voltage to the terminal 10 for the time required to check the earth circuit, and the switch 64 is for starting this timer 63. The output of the OR circuit 61 is fed back to the input of this OR circuit 61 to form a self-holding circuit. By operating the timer switch 64, the timer 6
3 is activated, and the output of the timer 63 drives the switch 62 to be turned on only for a predetermined short time. In this second embodiment, if there is no abnormality in the earth circuit as a result of checking the earth circuit, the contact output of the switch 56 is immediately given to the harness checker based on the output of the comparator 55 indicating the result. , the output state of the switch 56 is maintained. On the other hand, the output voltage of the power supply 52 is disconnected in a predetermined short time by the operation of the switch 62 by the timer 63, so as not to adversely affect the inspection of other circuits such as the core wire 8 of the same shielded wire 1. [0034] In each of the above embodiments, for example,
The switches 56, 62, 64, etc. are not limited to relays that actuate mechanical contacts, but may be implemented with various modifications, such as using electronic switches (semiconductor switches) that actuate electronic contacts. Further, the configuration of the present invention may be incorporated into a wire harness checker. Furthermore, the waveform of the alternating voltage may be a sine wave, a rectangular wave, a triangular wave, or a sawtooth wave. As described above, according to the present invention, one end of the capacitor is connected to one end of the shielding layer of the shielded wire to be tested, and the core wire of the shielded wire to be tested and the other end of the capacitor are connected to one end of the shielding layer of the shielded wire to be tested. By applying an alternating voltage between the capacitor terminals and determining the voltage generated between the terminals of the capacitor and detecting the presence or absence of a disconnection in the ground circuit, it has a simple configuration and is almost the same as other ordinary circuits. There is no need to remove the sheath, jacket, etc. of the shielded wire to be tested, and the workability of the continuity test of the ground circuit of the shielded wire is good, and the test can be performed in a short time. It is possible to provide a highly reliable wire harness inspection method and device. Moreover, since the wire harness inspection device of the present invention has a simple configuration, it can be easily incorporated into a wire harness checker.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram schematically showing the configuration of a wire harness inspection device according to a first embodiment of the present invention.

2 is a diagram showing an equivalent circuit for explaining the wire harness inspection device of FIG. 1. FIG.

FIG. 3 is a configuration diagram schematically showing the configuration of a wire harness inspection device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram schematically showing the configuration of a wire harness inspection device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram schematically showing the configuration of a shielded wire incorporated into the wire harness.

FIG. 6 is a diagram for explaining an example of a conventional wire harness inspection method.

FIG. 7 is a circuit configuration diagram showing the configuration of an example of a wire harness checker.

[Explanation of symbols]

1... Shield wire, 2... Outer cover, 3... Outer conductor, 4... Joint terminal, 5... Earth bond wire, 6... Earth terminal, 7...
Internal insulator, 8... Core wire, 9, 10... Terminal, 51... Capacitor, 52... Power supply, 53... Amplifier, 54... Converter,
55...Comparator, 56, 62...Switch, 61...OR circuit, 63...Timer, 64...Switch for timer.

Claims (2)

[Claims] 1. A wire harness testing method for testing continuity of a grounding circuit of a shielded wire of a wire harness incorporating a shielded wire in which only one end of a shielding layer is connected to a grounding terminal, comprising: (a) Connect one end of a capacitor having a capacitance of approximately the same order as the capacitance between the core wire of the shielded wire to be inspected and the shielding layer to the end of the shielded wire to be inspected that is connected to the ground terminal of the shielding layer, b) Applying an alternating current voltage between the core wire of the shielded wire to be inspected and the other end of the capacitor; (c) Determining the voltage generated between the terminals of the capacitor to determine the grounding circuit of the shielded wire to be inspected. A wire harness inspection method characterized by detecting the presence or absence of a disconnection. 2. A wire harness testing device for testing continuity of a grounding circuit of a shielded wire of a wire harness incorporating a shielded wire in which only one end of a shielding layer is connected to a grounding terminal, wherein the shielded wire to be tested is a capacitor having one end connected to the end connected to the ground terminal of the shielding layer and having a capacitance of approximately the same order as the capacitance between the core wire of the shielded wire to be tested and the shielding layer; and the shield to be tested. A power supply that applies an alternating voltage between the core wire of the wire and the other end of the capacitor, and a determination that determines the voltage generated between the terminals of the capacitor to detect whether there is a break in the ground circuit of the shielded wire to be inspected. A wire harness inspection device comprising a circuit.