Wire harness continuity test device

Abstract

To provide a wire harness continuity testing device that can accurately and efficiently perform continuity testing on multiple cables. [Solution] The wire harness continuity testing device 1 comprises a transmitting device 2 that transmits impulse signals with different frequencies to each of the multiple cables C of the wire harness WH, and a receiving device 3 that has a signal conversion function that converts the reflected wave signals of each cable C from the time domain to the frequency domain and from the frequency domain to the time domain, a signal separation function that separates the reflected wave signals into frequency components, and a continuity determination function that determines whether each cable C has good or bad continuity based on the time domain signals of the reflected waves for each frequency component.

Description

Technical Field

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[0001] The present invention relates to a continuity inspection device for a wire harness.

Background Art

[0002] As a continuity inspection device for cables, a device is known that selects a cable to be inspected from a plurality of cables by switching a switch, uses the non-selected cables as a common line to pass current through the cable to be inspected, and checks the continuity state of the cable to be inspected (see, for example, Patent Document 1). Further, as a continuity inspection device for a wire harness, a device is known that selects a cable to be inspected from various cables such as a signal line, a positive power supply line, and a negative power supply line of the wire harness by switching a switch, applies a voltage to the cable to be inspected, and detects disconnection, short circuit, and miswiring of the various cables (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the continuity inspection devices described in Patent Documents 1 and 2, the connection between each cable and the inspection device is switched by a switch, and thus the cable to be inspected is selected. Here, when the switch is switched, unintended pulses may be applied to the cable due to chatter, and the accuracy of the measurement result may be impaired. Further, since the continuity inspection is performed for each cable after the switch is switched, the inspection time becomes long when the number and types of cables are large.

[0005] In view of the above circumstances, the present invention aims to provide a wire harness continuity testing device that can accurately and efficiently perform continuity testing on multiple cables. [Means for solving the problem]

[0006] The continuity testing device of the present invention comprises a transmitting unit that transmits impulse signals with different frequencies for each cable to a plurality of cables of a wire harness, a receiving unit that has a signal conversion function that converts the reflected wave signals of each cable from the time domain to the frequency domain and from the frequency domain to the time domain, a separation function that separates the reflected wave signals for each frequency component, and a continuity determination function that determines whether each cable has good or bad continuity based on the time domain signals of the reflected waves for each frequency component. [Effects of the Invention]

[0007] According to the present invention, continuity testing of multiple cables in a wire harness can be performed accurately and efficiently. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows the configuration of a wire harness continuity testing device according to one embodiment of the present invention. [Figure 2] Figure 2 shows the frequency spectrum of the impulse signal transmitted from the transmitting device shown in Figure 1 to the cable. [Figure 3] Figure 3 shows the time waveform of the impulse signal transmitted from the transmitting device shown in Figure 1 to the cable. [Figure 4] Figure 4 shows the frequency spectrum of the impulse signal transmitted from the transmitting device shown in Figure 1 to the cable. [Figure 5] Figure 5 shows the frequency spectrum of the composite wave of the impulse signals transmitted from the transmitting device shown in Figure 1 to the cable. [Figure 6] Figure 6 shows the time waveform of the composite wave of the impulse signal transmitted from the transmitting device shown in Figure 1 to the cable. [Figure 7]Figure 7 is a table summarizing the frequency spectrum and time waveform of the composite wave of the impulse signal transmitted from the transmitting device to the cable shown in Figure 1. [Figure 8] Figure 8 shows the time waveforms of the impulse signal transmitted from the transmitting device to the cable shown in Figure 1 and the reflected signal received by the receiving device. [Figure 9] Figure 9 shows the configuration of the transmitting device of a wire harness continuity testing device according to another embodiment of the present invention. [Figure 10] Figure 10 shows the configuration of the receiving device of a wire harness continuity testing device according to another embodiment of the present invention. [Modes for carrying out the invention]

[0009] The present invention will be described below in accordance with preferred embodiments. However, the present invention is not limited to the embodiments shown below, and the embodiments shown below can be modified as appropriate without departing from the spirit of the invention. Furthermore, in the embodiments shown below, some components are not illustrated or described; however, details of the omitted technologies can be appropriately applied from publicly known or well-known technologies, to the extent that they do not contradict the content described below.

[0010] Figure 1 shows the configuration of a wire harness continuity testing device 1 according to one embodiment of the present invention. The continuity testing device 1 shown in this figure is a device that performs continuity testing and line length measurement of multiple cables C of a wire harness WH using the TDR (Time Domain Reflectometry) method. Furthermore, the continuity testing device 1 is a device that performs continuity testing and line length measurement of multiple cables C simultaneously (all at once) without requiring switching between the transmitting device 2 and the receiving device 3.

[0011] The continuity test device 1 comprises a transmitting device 2, a receiving device 3, and a storage unit 4. The storage unit 4 includes a server or recording medium for storing data such as the test results of the continuity test device 1, the part number and standard data of the wire harness WH to be tested, and other wire harness WH data. Examples of standard data for the wire harness WH include the threshold value of the amplitude of the reflected signal for each cable C, which is referenced when determining whether each cable C has continuity; the line length and frequency of each cable C, which is referenced when identifying the cable C to be tested; and the frequencies of the impulse signal and reflected signal of each cable C, which are referenced when determining whether a cable C has a short circuit.

[0012] The transmitting device 2 is a device that transmits impulse signals to multiple cables C. As will be described in detail later, the transmitting device 2 transmits an impulse signal with a different frequency for each cable C to one end of each of the multiple cables C. The receiving device 3 receives the reflected wave signals (hereinafter referred to as reflected signals) output from one end of each of the multiple cables C, and based on the received reflected signals, it performs the following: determining whether each cable C has good or bad conductivity, calculating the line length of each cable C, identifying each cable C, and determining whether each cable C is short-circuited. The continuity test device 1 will be described using the case where there are 5 cables C as an example, but the number of cables C is arbitrary, and the number of filters 222A, 222B, 222C, 222D, 222E, mixer circuits 231A, 231B, 231C, 231D, 231E, application units 24A, 24B, 24C, 24D, 24E, and detection units 31A, 31B, 31C, 31D, 31E will increase or decrease depending on the number of cables C.

[0013] The transmitting device 2 comprises an impulse signal generation unit 21, a local signal generation unit 22, a frequency conversion unit 23, and a plurality of application units 24A, 24B, 24C, 24D, and 24E. The number of application units 24A, 24B, 24C, 24D, and 24E is the same as the number of cables C. Note that when it is not necessary to explain each of the application units 24A, 24B, 24C, 24D, and 24E separately, they may be referred to as application unit 24.

[0014] The impulse signal generation unit 21 includes an impulse signal generator that generates a broadband impulse signal, and a computer that transmits a control signal to the impulse signal generator. The frequency of the impulse signal generated by the impulse signal generation unit 21 is f0. As shown in FIG. 1, the computer included in the impulse signal generation unit 21 and the computer included in the arithmetic unit 33 described later are shared, but this is not essential.

[0015] The local signal generation unit 22 includes an oscillator 221 and filters 222A, 222B, 222C, 222D, 222E. The number of filters 222A, 222B, 222C, 222D, 222E is the same as the number of cables C. In some cases, when it is not necessary to distinguish each of the filters 222A, 222B, 222C, 222D, 222E for explanation, they may be described as filter 222.

[0016] The oscillator 221 generates a broadband local signal. The plurality of filters 222 are narrowband analog filters connected to the oscillator 221, and a circuit is configured by combining resistors, coils, and capacitors. Each filter 222 passes a signal with a specific bandwidth of the broadband local signal output from the oscillator 221 and removes other frequency components.

[0017] The local signal with frequency f1’ passes through filter 222A. The local signal with frequency f2’ passes through filter 222B. The local signal with frequency f3’ passes through filter 222C. The local signal with frequency f4’ passes through filter 222D. The local signal with frequency f5’ passes through filter 222E. The frequencies f1’, f2’, f3’, f4’, f5’ are different from each other.

[0018] Note that the capacitors of the filters 222 may be variable capacitors, and the frequencies of the local signals passing through the plurality of filters 222 may be made different by making the capacitances of the capacitors of the plurality of filters 222 different due to the difference in applied voltage. In that case, the circuit configurations of the plurality of filters 222 can be shared.

[0019] The frequency conversion unit 23 includes mixer circuits 231A, 231B, 231C, 231D, and 231E. The number of mixer circuits 231A, 231B, 231C, 231D, and 231E is the same as the number of cables C. Mixer circuit 231A is connected to filter 222A via a diode. Mixer circuit 231B is connected to filter 222B via a diode. Mixer circuit 231C is connected to filter 222C via a diode. Mixer circuit 231D is connected to filter 222D via a diode. Mixer circuit 231E is connected to filter 222E via a diode. Note that when it is not necessary to distinguish between mixer circuits 231A, 231B, 231C, 231D, and 231E, they may simply be referred to as mixer circuit 231.

[0020] Mixer circuit 231 is a circuit that mixes the impulse signal generated by the impulse signal generation unit 21 with the local signal that has passed through the filter 222 to generate an impulse signal with a specific frequency component. Mixer circuit 231A mixes an impulse signal with frequency f0 with a local signal with frequency f1' to generate an impulse signal with center frequency f1. Mixer circuit 231B mixes an impulse signal with frequency f0 with a local signal with frequency f2' to generate an impulse signal with center frequency f2. Mixer circuit 231C mixes an impulse signal with frequency f0 with a local signal with frequency f3' to generate an impulse signal with center frequency f3. Mixer circuit 231D mixes an impulse signal with frequency f0 with a local signal with frequency f4' to generate an impulse signal with center frequency f4. The mixer circuit 231E mixes an impulse signal with frequency f0 and a local signal with frequency f5' to generate an impulse signal with a center frequency of f5.

[0021] The application unit 24A is connected to the mixer circuit 231A via a diode and is also connected to one end of the first cable C, and applies an impulse signal with a center frequency of f1 generated by the mixer circuit 231A to one end of the first cable C. The application unit 24B is connected to the mixer circuit 231B via a diode and is also connected to one end of the second cable C, and applies an impulse signal with a center frequency of f2 generated by the mixer circuit 231B to one end of the second cable C. The application unit 24C is connected to the mixer circuit 231C via a diode and is also connected to one end of the third cable C, and applies an impulse signal with a center frequency of f3 generated by the mixer circuit 231C to one end of the third cable C. The application unit 24D is connected to the mixer circuit 231D via a diode and is also connected to one end of the fourth cable C, and applies an impulse signal with a center frequency of f4 generated by the mixer circuit 231D to one end of the fourth cable C. The application unit 24E is connected to the mixer circuit 231E via a diode and is also connected to one end of the fifth cable C, and applies an impulse signal with a center frequency of f5 generated by the mixer circuit 231E to one end of the fifth cable C.

[0022] Here, f1, f2, f3, f4, and f5 are in the relationship of f1 < f2 < f3 < f4 < f5 and are different from each other. f2 is f1 + Δf, f3 is f2 + Δf, f4 is f3 + Δf, and f5 is f4 + Δf. Δf is a positive constant value.

[0023] FIG. 2 is a diagram showing the frequency spectrum of the impulse signal transmitted from the transmission-side device 2 shown in FIG. 1 to the cable C. This diagram shows the frequency spectrum of the impulse signal with a center frequency of f1 applied to the first cable C.

[0024] Figure 3 shows the time waveform of the impulse signal transmitted from the transmitting device 2 shown in Figure 1 to cable C. This figure shows the time waveform obtained by transforming the frequency spectrum waveform shown in Figure 2 using IFFT (Inverse Fast Fourier Transform).

[0025] As shown in Figure 2, an impulse signal with a center frequency of f1 has a flat characteristic added to it, with a bandwidth of δF around the center frequency f1 as the reference point. As a result, as shown in Figure 3, when an impulse signal with a center frequency of f1 is converted from the frequency domain to the time domain, a steep impulse signal appears on the time axis.

[0026] If the impulse signal does not have the flat characteristic described above, the peak of the impulse signal appearing on the time axis will be smoother, and the measurement resolution will decrease. In particular, the accuracy of calculating the delay time of the reflected wave to the impulse signal, which will be described later, will decrease. Therefore, since the above δF affects the measurement resolution, it is set according to the inspection specifications.

[0027] Figure 4 shows the frequency spectrum of the impulse signal transmitted from the transmitting device 2 shown in Figure 1 to cable C. This figure shows the frequency spectrum of the impulse signal with a center frequency of f2 applied to the second cable C.

[0028] As shown in Figure 4, the center frequency f2 of the impulse signal applied to the second cable C is shifted by Δf relative to the center frequency f1 of the impulse signal applied to the first cable C. Figure 4 shows that f1 and f2 are related by f2 > f1 and f2 = f1 + Δf.

[0029] Figure 5 shows the frequency spectrum of the composite wave of the impulse signals transmitted from the transmitting device 2 shown in Figure 1 to cable C. This figure shows the frequency spectrum of the composite waveform of the impulse signals with center frequencies f1 to f5 applied to the five cables C.

[0030] As shown in Figure 5, the center frequency f3 of the impulse signal applied to the third cable C is shifted by Δf from the center frequency f2 of the impulse signal applied to the second cable C. Similarly, the center frequency f4 of the impulse signal applied to the fourth cable C is shifted by Δf from the center frequency f3 of the impulse signal applied to the third cable C. Furthermore, the center frequency f5 of the impulse signal applied to the fifth cable C is shifted by Δf from the center frequency f4 of the impulse signal applied to the fourth cable C.

[0031] The edges (tails) of the spectral waveforms of an impulse signal with a center frequency of f1 and an impulse signal with a center frequency of f2 overlap. Similarly, the edges (tails) of the spectral waveforms of an impulse signal with a center frequency of f2 and an impulse signal with a center frequency of f3 overlap. Furthermore, the edges (tails) of the spectral waveforms of an impulse signal with a center frequency of f3 and an impulse signal with a center frequency of f4 overlap. Finally, the edges (tails) of the spectral waveforms of an impulse signal with a center frequency of f4 and an impulse signal with a center frequency of f5 overlap.

[0032] Here, the characteristics of filter 222 are set so that the edges of the spectral waveforms of adjacent impulse signals overlap in a bandwidth outside the occupied bandwidth of each impulse signal. For example, to minimize the influence of interference between adjacent impulse signals, the characteristics of filter 222 are set so that the edges of the spectral waveforms of adjacent impulse signals overlap at a signal level at least 20 dB lower than the peak signal level of each impulse signal. In this embodiment, the edges of the spectral waveforms of adjacent impulse signals overlap at a signal level 30 dB lower than the peak signal level of each impulse signal. 30 dB corresponds to 99.9% of the entire signal. Note that 30 dB is just an example and will be determined appropriately depending on the spectral waveform of the impulse signals, etc.

[0033] The attenuation curve of the frequency separation function (frequency separation filter) of the calculation unit 33, described later, changes the frequency range required for the signal level of the impulse signal to attenuate to 20 dB or more below its peak. As a result, the value of Δf fluctuates. The steeper the attenuation curve of the frequency separation filter, the shorter Δf can be.

[0034] As shown in Figure 1, the receiving device 3 comprises detection units 31A, 31B, 31C, 31D, and 31E, a measurement unit 32, and a calculation unit 33. The same number of detection units 31A, 31B, 31C, 31D, and 31E as the number of cables C. Note that when it is not necessary to explain each of the detection units 31A, 31B, 31C, 31D, and 31E separately, they may be referred to simply as detection unit 31.

[0035] Detection unit 31A is connected to one end of the first cable C and also to the common signal line L0 via a diode, and detects the reflected signal output from one end of the first cable C. Detection unit 31B is connected to one end of the second cable C and also to the common signal line L0 via a diode, and detects the reflected signal output from one end of the second cable C. Detection unit 31C is connected to one end of the third cable C and also to the common signal line L0 via a diode, and detects the reflected signal output from one end of the third cable C. Detection unit 31D is connected to one end of the fourth cable C and also to the common signal line L0 via a diode, and detects the reflected signal output from one end of the fourth cable C. Detection unit 31E is connected to one end of the fifth cable C and also to the common signal line L0 via a diode, and detects the reflected signal output from one end of the fifth cable C.

[0036] The measurement unit 32 includes a computer that has the function of observing the waveform of the reflected signal detected by the detection unit 31 in both the time domain and the frequency domain. The measurement unit 32 is connected to the detection unit 31 via a common signal line L0 and a diode, and is also connected to the calculation unit 33.

[0037] Figure 6 shows the time waveform of the composite wave of the impulse signal transmitted from the transmitting device 2 shown in Figure 1 to cable C. This figure shows the time waveform obtained by transforming the frequency spectrum waveform shown in Figure 5 using IFFT.

[0038] Here, the reflected signals detected by the detection units 31A, 31B, 31C, 31D, and 31E are input to the measurement unit 32 together via the common signal line L0. As a result, the measurement unit 32 observes a time-domain waveform as shown in Figure 6.

[0039] Figure 7 is a table summarizing the frequency spectrum and time waveform of the impulse signal transmitted from the transmitting device 2 shown in Figure 1 to cable C. In the table, FΣ is the composite wave of the impulse signals with center frequencies f1 to f5 shown in Figures 5 and 6. The upper part of the table shows the waveform of the impulse signal on the frequency axis, and the lower part of the table shows the waveform of the impulse signal on the time axis.

[0040] The measurement unit 32 shown in Figure 1 is equipped with a signal conversion function that converts the reflected signal from the time domain to the frequency domain using FFT (Fast Fourier Transform) and converts the reflected signal from the frequency domain to the time domain using IFFT. As a result, the measurement unit 32 can observe the reflected signal in both the time domain and the frequency domain.

[0041] The calculation unit 33 shown in Figure 1 is a computer that has a signal separation function for separating the reflected signal measured by the measurement unit 32 into frequency components, a continuity determination function for determining whether the continuity is good or bad for each frequency component, a line length calculation function for calculating the line length of cable C for each frequency component, and a short-circuit determination function for determining whether or not there is a short circuit in cable C.

[0042] Here, there is no difference between the frequency components of the impulse signal applied to each cable C and the frequency components of the reflected signal output from each cable C. The first cable C outputs a reflected signal with a center frequency of f1. The second cable C outputs a reflected signal with a center frequency of f2. The third cable C outputs a reflected signal with a center frequency of f3. The fourth cable C outputs a reflected signal with a center frequency of f4. The fifth cable C outputs a reflected signal with a center frequency of f5.

[0043] The calculation unit 33 converts a signal containing reflected signals with center frequencies f1 to f5 from the time domain to the frequency domain using FFT, separating it into frequency components with center frequencies f1 to f5. Subsequently, the calculation unit 33 converts each frequency component from the frequency domain to the time domain using IFFT.

[0044] Figure 8 shows the time waveforms of the impulse signal transmitted from the transmitting device 2 to cable C as shown in Figure 1, and the reflected signal received by the receiving device 3. As shown in this figure, the impulse signal input to cable C is attenuated and returned as a reflected signal after a delay time t' from the time of application. Because the impulse signal input to cable C undergoes multiple reflections within cable C, multiple peaks appear in the reflected signal.

[0045] The calculation unit 33 shown in Figure 1 compares the amplitude of the reflected signal converted to the time domain with the threshold value of the amplitude of the reflected signal for each frequency component stored in the storage unit 4, and determines whether the continuity of each cable C is good or bad. The calculation unit 33 determines that the continuity of each cable C is good if the amplitude of the reflected signal is greater than or equal to the threshold value, and determines that the continuity of each cable C is poor if the amplitude of the reflected signal is less than the threshold value.

[0046] The calculation unit 33 calculates the line length L of each cable C using the following equation (1). L = c × t' / 2 ···(1) However, c is the speed of light.

[0047] If there is a short circuit or break in cable C, the position of the peak of the reflected signal on the time axis changes from the standard position, and the delay time t' changes. Therefore, the calculation unit 33 compares the calculated line length L with the standard data stored in the storage unit 4 to determine whether or not there is a short circuit or break in each cable C.

[0048] Furthermore, if there is a short circuit in cable C, it is conceivable that there will be a difference between the frequency components of the impulse signal applied to the short-circuited cable C and the frequency components of the reflected signal output from the short-circuited cable C. Therefore, the calculation unit 33 performs frequency separation using FFT, compares the separated frequency components with the standard data stored in the storage unit 4, and determines that there is a short circuit in cable C corresponding to the frequency components that do not match the standard data.

[0049] As described above, the continuity testing device 1 according to this embodiment comprises a transmitting device 2 and a receiving device 3. The transmitting device 2 transmits impulse signals with different frequencies for each of the multiple cables C of the wire harness WH. The receiving device 3 comprises a signal conversion function, a signal separation function, and a continuity determination function. The receiving device 3 converts the reflected signals of each cable C from the time domain to the frequency domain and vice versa using the signal conversion function. The receiving device 3 also separates the reflected signals of the multiple cables C by frequency component using the signal separation function. Furthermore, in the continuity determination function, the receiving device 3 determines whether each cable C has good or bad continuity based on the time domain signal of the reflected wave for each frequency component.

[0050] In other words, the continuity testing device 1 according to this embodiment assigns mutually orthogonal frequency components to the impulse signal transmitted to each cable C of the wire harness WH, and determines the continuity of each cable C based on the time-domain signal of the reflected wave for each frequency component. This makes it possible to perform continuity testing of multiple cables C of the wire harness WH without requiring a switch to connect the continuity testing device 1 to each cable C. Therefore, measurement errors due to chattering when switching switches can be prevented. In addition, by performing continuity testing of multiple cables C simultaneously, the testing time can be shortened even when there are many cables C or a large number of types of cables C. Furthermore, since each cable C can be identified based on the frequency components of the reflected signal of each cable C, it is also possible to detect short circuits, miswiring, etc. in each cable C.

[0051] The receiving device 3 is provided for each cable C and comprises a plurality of detection units 31 for detecting reflected signals from each cable C, a common signal line L0 to which the plurality of detection units 31 are connected, a measurement unit 32, and a calculation unit 33. The measurement unit 32 receives the reflected signals detected by the plurality of detection units 31 via the common signal line L0. The calculation unit 33 converts the reflected signals received by the measurement unit 32 from the time domain to the frequency domain using a signal conversion function, separates them into frequency components using a signal separation function, and determines the continuity of each cable using a continuity determination function. As a result, the reflected signals output to the receiving device 3 from the plurality of cables C can be processed by the calculation unit 33 via the common signal line L0 and the common measurement unit 32. Therefore, the circuit configuration of the receiving device 3 can be simplified and the cost of the receiving device 3 can be reduced.

[0052] The transmitting device 2 comprises an impulse signal generation unit 21, a local signal generation unit 22, a plurality of mixer circuits 231, and a plurality of application units 24. The impulse signal generation unit 21 generates an impulse signal with frequency f0 as a carrier wave. The local signal generation unit 22 generates local signals with different frequencies for each cable C. The frequencies of each local signal are f1', f2', f3', f4', and f5'. The plurality of mixer circuits 231 are provided for each cable C and mix the impulse signal with frequency f0 generated by the impulse signal generation unit 21 with the local signals with frequencies f1', f2', f3', f4', and f5' generated by the local signal generation unit 22 to generate impulse signals with different frequencies for each cable C. The frequencies of the generated impulse signals are f1, f2, f3, f4, and f5. Multiple application units 24 are provided for each cable C and each mixer circuit 231, and each mixer circuit 231 applies an impulse signal with a different frequency to each cable C generated by each cable C. This makes it possible to generate multiple types of impulse signals with different frequencies for each cable C from the impulse signal generated by the common impulse signal generation unit 21 and apply them to multiple cables C. Therefore, the circuit configuration of the transmitting device 2 can be simplified and the cost of the transmitting device 2 can be reduced.

[0053] In particular, the local signal generation unit 22 includes an oscillator 221 that generates a wideband local signal and a plurality of filters 222 provided for each mixer circuit 231. The plurality of filters 222 convert the wideband local signal generated by the oscillator 221 into local signals with different frequencies for each cable C. The frequencies of the local signals generated by each filter 222 are f1', f2', f3', f4', and f5'. This makes it possible to generate local signals with different frequencies for each mixer circuit 231 from the local signal generated by a common oscillator 221 and transmit them to multiple mixer circuits 231. Therefore, the circuit configuration of the local signal generation unit 22 can be simplified, and the cost of the transmitting device 2 can be further reduced.

[0054] The calculation unit 33 of the receiving device 3 has the function of calculating the line length L of each cable C based on the delay time t' of the reflected signal to the impulse signal applied to each cable C. This makes it possible to identify each cable C based on its line length L and to determine whether there is a short circuit or miswiring.

[0055] The calculation unit 33 in the receiving device 3 has a function to determine whether or not each cable C is short-circuited based on the frequency of the impulse signal applied to each cable C and the frequency of the reflected signal. Therefore, the calculation unit 33 can detect a short circuit in cable C when there is a mismatch in the frequencies of the impulse signal and the reflected signal for each cable C, such as when the frequency of the impulse signal applied to one cable C matches the frequency of the reflected signal of another cable C.

[0056] Figure 9 shows the configuration of the transmitting device 20 of the wire harness continuity testing device 10 according to another embodiment of the present invention. Components similar to those in the above-described embodiment are denoted by the same reference numerals, and the description of the above-described embodiment will be used accordingly.

[0057] As shown in Figure 9, the transmitting device 20 includes an impulse signal generation unit 21, a local signal generation unit 220, a frequency conversion unit 23, and a plurality of application units 24A, 24B, 24C, 24D, 24E (see Figure 1).

[0058] The local signal generation unit 220 is equipped with oscillators 221A, 221B, 221C, 221D, and 221E. The number of oscillators 221A, 221B, 221C, 221D, and 221E is the same as the number of cables C.

[0059] Oscillators 221A, 221B, 221C, 221D, and 221E generate narrowband local signals. The frequency of the local signal generated by oscillator 221A is f1'. The frequency of the local signal generated by oscillator 221B is f2'. The frequency of the local signal generated by oscillator 221C is f3'. The frequency of the local signal generated by oscillator 221D is f4'. The frequency of the local signal generated by oscillator 221E is f5'. Frequencies f1', f2', f3', f4', and f5' are all distinct from each other.

[0060] Mixer circuit 231A is connected to oscillator 221A. Mixer circuit 231B is connected to oscillator 221B. Mixer circuit 231C is connected to oscillator 221C. Mixer circuit 231D is connected to oscillator 221D. Mixer circuit 231E is connected to oscillator 221E.

[0061] The mixer circuit 231 mixes the impulse signal generated by the impulse signal generation unit 21 with the local signals generated by the oscillators 221A, 221B, 221C, 221D, and 221E to generate an impulse signal with a specific frequency component.

[0062] As described above, the local signal generation unit 220 is equipped with multiple oscillators 221A, 221B, 221C, 221D, and 221E, each provided for each mixer circuit 231. The multiple oscillators 221A, 221B, 221C, 221D, and 221E generate local signals with different frequencies for each cable C. The frequencies of each local signal are f1', f2', f3', f4', and f5'. The multiple mixer circuits 231 are provided for each cable C and mix the impulse signal with frequency f0 generated by the impulse signal generation unit 21 with the local signals with frequencies f1', f2', f3', f4', and f5' generated by the oscillators 221A, 221B, 221C, 221D, and 221E to generate impulse signals with different frequencies for each cable C. The frequencies of the generated impulse signals are f1, f2, f3, f4, and f5. Multiple application units 24 apply impulse signals with different frequencies to each cable C, which are generated by the mixer circuit 231. This allows multiple types of impulse signals with different frequencies to be generated from the impulse signal generated by the common impulse signal generation unit 21 and applied to multiple cables C. Therefore, the circuit configuration of the transmitting device 20 can be simplified, and the cost of the transmitting device 20 can be reduced.

[0063] Figure 10 shows the configuration of the receiving device 30 of the wire harness continuity testing device 100 according to another embodiment of the present invention. Components similar to those in the above-described embodiment are denoted by the same reference numerals, and the description of the above-described embodiment will be used accordingly.

[0064] As shown in Figure 10, the receiving device 30 comprises detection units 31A, 31B, 31C, 31D, 31E, measurement units 32A, 32B, 32C, 32D, 32E, and a calculation unit 330. The measurement units 32A, 32B, 32C, 32D, 32E are equipped with computers that have the function of observing the reflected signal detected by the detection unit 31 in both the time domain and the frequency domain.

[0065] The measurement units 32A, 32B, 32C, 32D, and 32E are individually connected to the detection unit 31 and individually connected to the calculation unit 330. Measurement unit 32A is connected to the detection unit 31A via signal line L1 and a diode, and to the calculation unit 330 via signal line L11. Measurement unit 32B is connected to the detection unit 31B via signal line L2 and a diode, and to the calculation unit 330 via signal line L12. Measurement unit 32C is connected to the detection unit 31C via signal line L3 and a diode, and to the calculation unit 330 via signal line L13. Measurement unit 32D is connected to the detection unit 31D via signal line L4 and a diode, and to the calculation unit 330 via signal line L14. Measurement unit 32E is connected to the detection unit 31E via signal line L5 and a diode, and to the calculation unit 330 via signal line L15.

[0066] The calculation unit 330 compares the amplitude of the reflected signal with center frequency f1 observed by the measurement unit 32A with the threshold value of the reflected signal with center frequency f1 stored in the storage unit 4 to determine whether the first cable C has good or bad continuity. The calculation unit 330 determines that the first cable C has good continuity if the amplitude of the reflected signal is greater than or equal to the threshold value, and determines that the first cable C has poor continuity if the amplitude of the reflected signal is less than the threshold value.

[0067] The calculation unit 330 compares the amplitude of the reflected signal with center frequency f2 observed by the measurement unit 32B with the threshold value of the reflected signal with center frequency f2 stored in the storage unit 4 to determine whether the continuity of the second cable C is good or bad. The calculation unit 330 determines that the continuity of the second cable C is good if the amplitude of the reflected signal is greater than or equal to the threshold value, and determines that the continuity of the second cable C is poor if the amplitude of the reflected signal is less than the threshold value.

[0068] The calculation unit 330 compares the amplitude of the reflected signal with a center frequency of f3 observed by the measurement unit 32C with the threshold value of the reflected signal with a center frequency of f3 stored in the storage unit 4 to determine whether the continuity of the third cable C is good or bad. The calculation unit 330 determines that the continuity of the third cable C is good if the amplitude of the reflected signal is greater than or equal to the threshold value, and determines that the continuity of the third cable C is poor if the amplitude of the reflected signal is less than the threshold value.

[0069] The calculation unit 330 compares the amplitude of the reflected signal with a center frequency of f4 observed by the measurement unit 32D with the threshold value of the reflected signal with a center frequency of f4 stored in the storage unit 4 to determine whether the continuity of the fourth cable C is good or bad. The calculation unit 330 determines that the continuity of the fourth cable C is good if the amplitude of the reflected signal is greater than or equal to the threshold value, and determines that the continuity of the fourth cable C is poor if the amplitude of the reflected signal is less than the threshold value.

[0070] The calculation unit 330 compares the amplitude of the reflected signal with a center frequency of f5 observed by the measurement unit 32E with the threshold value of the reflected signal with a center frequency of f5 stored in the storage unit 4 to determine whether the fifth cable C has good or bad continuity. The calculation unit 330 determines that the fifth cable C has good continuity if the amplitude of the reflected signal is greater than or equal to the threshold value, and determines that the fifth cable C has poor continuity if the amplitude of the reflected signal is less than the threshold value.

[0071] The calculation unit 330 calculates the line length L of each cable C using equation (1) above. Then, the calculation unit 330 compares the calculated line length L with the standard data stored in the storage unit 4 to determine whether there is a short circuit or an open circuit in each cable C.

[0072] The calculation unit 330 compares the frequency of the reflected signal observed by the measurement unit 32A with the standard data (frequency f1) stored in the storage unit 4. If they do not match, it determines that there is a short circuit in the first cable C. The calculation unit 330 also compares the frequency of the reflected signal observed by the measurement unit 32B with the standard data (frequency f2) stored in the storage unit 4. If they do not match, it determines that there is a short circuit in the second cable C. The calculation unit 330 also compares the frequency of the reflected signal observed by the measurement unit 32C with the standard data (frequency f3) stored in the storage unit 4. If they do not match, it determines that there is a short circuit in the third cable C. The calculation unit 330 also compares the frequency of the reflected signal observed by the measurement unit 32D with the standard data (frequency f4) stored in the storage unit 4. If they do not match, it determines that there is a short circuit in the fourth cable C. Furthermore, the calculation unit 330 compares the frequency of the reflected signal observed by the measurement unit 32E with the standard data (frequency f5) stored in the storage unit 4, and if they do not match, it determines that there is a short circuit in the fifth cable C.

[0073] As described above, in the receiving device 30, the first cable C is connected to the calculation unit 330 via the detection unit 31A, signal line L1, measurement unit 32A, and signal line L11; the second cable C is connected to the calculation unit 330 via the detection unit 31B, signal line L2, measurement unit 32B, and signal line L12; the third cable C is connected to the calculation unit 330 via the detection unit 31C, signal line L3, measurement unit 32C, and signal line L13; the fourth cable C is connected to the calculation unit 330 via the detection unit 31D, signal line L4, measurement unit 32D, and signal line L14; and the fifth cable C is connected to the calculation unit 330 via the detection unit 31E, signal line L5, measurement unit 32E, and signal line L15. As a result, reflected signals with different frequencies for each of the multiple cables C are separated by frequency component and input to the calculation unit 330. This allows the calculation unit 330 to process the reflected signals output to the receiving device 30 from multiple cables C, component by component.

[0074] Although the present invention has been described above based on the above embodiments, the present invention is not limited to the above embodiments, and modifications may be made to the above embodiments without departing from the spirit of the present invention, or publicly known or well-known technologies may be combined as appropriate. [Explanation of symbols]

[0075] 1: Continuity testing device 2: Transmitter-side device (transmitter unit) 3: Receiving device (receiving unit) 10: Continuity testing device 20: Transmitter-side device (transmitter unit) 21: Impulse signal generation unit (carrier wave generation unit) 22: Local signal generation unit 24: Application section 24A: Application section 24B: Application section 24C: Application section 24D: Application section 24E: Application part 30: Receiving device (receiving unit) 31: Detection unit 31A: Detection unit 31B: Detection unit 31C: Detection unit 31D: Detection unit 31E: Detection unit 33: Arithmetic section 100: Continuity testing device 220: Local signal generation unit 221: Oscillator 222: Filter 222A: Filter 222B: Filter 222C: Filter 222D: Filter 222E: Filter 231: Mixer Circuit 231A: Mixer circuit 231B: Mixer circuit 231C: Mixer circuit 231D: Mixer circuit 231E: Mixer circuit C: Cable L:Line length L0: Common signal line (common signal line) t': delay time WH: Wire harness

Claims

1. A transmitting unit that sends impulse signals with different frequencies to multiple cables in a wire harness, A receiving unit comprising: a signal conversion function that converts the reflected wave signals of each cable from the time domain to the frequency domain and from the frequency domain to the time domain; a signal separation function that separates the reflected wave signals into their respective frequency components; and a continuity determination function that determines the quality of continuity of each cable based on the time domain signals of the reflected waves for each frequency component. A wire harness continuity test device equipped with [specific features / features].

2. The receiving unit is Each cable is provided with a plurality of detection units for detecting the reflected wave signal, A common signal line to which the multiple detection units are connected, A calculation unit receives the reflected wave signals detected by multiple detection units via a common signal line, converts the received reflected wave signals from the time domain to the frequency domain using the signal conversion function, separates them into frequency components using the signal separation function, and determines the quality of continuity of each cable using the continuity determination function. The wire harness continuity testing device according to claim 1, comprising:

3. The aforementioned transmitting unit A carrier wave generating unit that generates a carrier wave, A local signal generation unit that generates local signals with different frequencies for each cable, A plurality of mixer circuits are provided for each cable, which mix the carrier wave generated by the carrier wave generation unit and the local signal generated by the local signal generation unit to generate impulse signals with different frequencies for each cable, Each cable and each mixer circuit is provided with a plurality of application units that apply the impulse signals, each with a different frequency for each cable, generated by the mixer circuit, to each cable. A wire harness continuity testing device according to claim 1 or 2, comprising:

4. The local signal generation unit is An oscillator that generates a wideband local signal, Each mixer circuit is provided with a plurality of filters that convert the broadband local signal generated by the oscillator into a local signal with a different frequency for each mixer circuit. Equipped with, The mixer circuit generates the impulse signal by mixing the carrier wave generated by the carrier wave generation unit with the local signal converted by the filter. The wire harness continuity testing device according to claim 3.

5. The wire harness continuity testing device according to claim 1 or 2, wherein the receiving unit has a function to calculate the line length of each cable based on the delay time of the reflected wave signal with respect to the impulse signal.

6. The wire harness continuity test device according to claim 1 or 2, wherein the receiving unit has a function to determine whether or not there is a short circuit in each cable based on the frequency of the impulse signal and the frequency of the reflected wave signal.

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