Method for judging iron punching position of wire harness by using milliohm meter

Abstract

The invention discloses a method for judging a wire harness tapping position by using a milliohm meter. The method comprises the following steps: confirming a faulty wire harness subjected to tapping; a standard wire is selected according to the fault wire harness, the standard wire and the fault wire harness are the same in material and cross section area, and the length of the standard wire is set to be L0; measuring the resistance R0 of the standard lead by using a four-probe method of a milliohm meter; breaking elements at the two ends of the fault wire harness, and measuring the resistance R1 between the measuring end of the fault wire harness and the iron hitting point of the fault wire harness by using a four-probe method of a milliohm meter; and calculating the wire harness length L1 between the measuring end of the fault wire harness and the iron hitting point of the fault wire harness according to L1 = (R1 / R0) * L0. The method has the advantages that the four-probe method of the milliohm meter is used for measuring the resistance of the wire harness, the influence of contact resistance on testing instrument equipment can be reduced as much as possible, the accurate position of the iron punching point of the wire harness can be determined by comparing the resistance with the resistance of the standard wire with the same wire diameter and the known length, and the method is simple, efficient and accurate in fault point searching.

Description

Technical Field

[0001] The invention relates to the technical field of automobile wiring harnesses, in particular to a method for judging a forging position of a wiring harness by using a milliohmmeter. Background Art

[0002] According to statistics, the probability of electrical problems in vehicles is around 15%. Electrical failures caused by various wiring harness problems in cars account for 70% of all electrical failures, and failures caused by wire crimping account for 9.3% of wiring harness problems. When the wires are crimped severely, it is easy for the wiring harness to form breakpoints, and most of the breakpoints will be connected to the car body and cause a short circuit.

[0003] A multimeter can be used to find the wire harness where the wire is pressed, but it is very tedious and time-consuming to find the specific location of the wire pressing. After a wire pressing failure occurs, the truncation method is generally used to find the wire pressing location. The specific steps are as follows:

[0004] Step 1: Cut the problematic wiring harness in the middle and use the on / off setting of a multimeter to measure which section is crimping the wire.

[0005] Step 2: Cut the problematic wire harness in the middle and use the multimeter to measure which section is crimping.

[0006] Step 3: Repeat step 2 until the pressing line position is found.

[0007] When the truncation method is used to find the wire crimping position, in order to facilitate cutting the wire harness, a large range of the wire harness and surrounding parts need to be disassembled. Each repair takes at least 30 minutes, which consumes a long time. Summary of the invention

[0008] In order to solve at least one of the above technical problems, the present invention provides a method for determining the location of a wire harness hit using a milliohmmeter. The resistance of the faulty wire harness is measured using a milliohmmeter, and then the resistance is compared with that of a standard wire of the same diameter and known length to determine the exact location of the hit point of the wire harness.

[0009] The present invention solves the technical problem by adopting the following technical solution:

[0010] A method for determining a wire harness forging position using a milliohm meter comprises the following steps:

[0011] Step 1: Confirm the faulty wiring harness;

[0012] Step 2: Select a standard wire according to the faulty wire harness, wherein the standard wire has the same material and cross-sectional area as the faulty wire harness, and the length of the standard wire is set to L0;

[0013] Step 3: Use the four-probe method of the milliohm meter to measure the resistance R0 of the standard wire;

[0014] Step 4: Disconnect the components at both ends of the faulty wiring harness, and use the four-probe method of the milliohm meter to measure the resistance R1 between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness;

[0015] Step 5: Calculate the harness length L1 between the measuring end of the fault harness and the forging point of the fault harness according to formula (1):

[0016] L1=(R1 / R0)*L0, formula (1).

[0017] Furthermore, the method includes searching for a faulty wiring harness through a multimeter, which is simple to search and easy to operate.

[0018] Furthermore, the length L0 of the standard wire is set to 50-100 cm, which facilitates operation and improves measurement accuracy.

[0019] Furthermore, the method further includes measuring the resistance R0 of the standard wire and the resistance R1 between the measuring end of the faulty wire harness and the ironing point of the faulty wire harness using a four-probe method of a milliohm meter, performing multiple measurements, and calculating the corresponding average values. and , improve the accuracy of measurement.

[0020] Furthermore, the method further comprises: and Calculate the harness length L1 between the measuring end of the fault harness and the ironing point of the fault harness. .

[0021] Furthermore, the method also includes: when the Kelvin clamp cannot be directly inserted into the accommodating space of the faulty wiring harness measuring end terminal to clamp the pin of the measuring end terminal, a corresponding transition terminal is connected to the measuring end terminal, and the Kelvin clamp is used to clamp the pin of the transition terminal, which is flexible and convenient to operate.

[0022] Furthermore, the method also includes: removing vehicle components that are at a distance L1 from the faulty wiring harness measuring end along the extension direction of the faulty wiring harness, so that a portion of the wiring harness that is at a distance L1 from the faulty wiring harness measuring end is exposed, and the disassembly range is small.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Using the four-probe method of the milliohm meter to measure the wiring harness resistance can minimize the influence of the contact resistance on the test instrument equipment, thereby achieving high-precision, accurate measurement of small resistances. By comparing it with the resistance of a standard wire of the same wire diameter and known length, the exact location of the wire harness strike point can be determined. Ohm's law can be directly applied to the maintenance and diagnosis of automotive electrical faults. It is simple and efficient, and the fault point can be accurately found.

[0025] (2) The wire resistance is measured with a milliohm meter to determine the wire harness strike point. The wire harness is not damaged during the test, which is simple to implement and reduces damage to interior parts. In addition, the work time is short, and the fault analysis and wire harness repair can be completed in about 10 minutes, saving more than 400,000 yuan in repair costs each year. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to better understand the above and other purposes, features, advantages and functions of the present invention, reference may be made to the embodiments shown in the accompanying drawings. The same reference numerals in the accompanying drawings refer to the same components. It should be understood by those skilled in the art that the accompanying drawings are intended to schematically illustrate the preferred embodiments of the present invention and have no limiting effect on the scope of the present invention, and the components in the drawings are not drawn to scale.

[0027] Figure 1 The present invention is a flow chart of a method for determining the forging position of a wiring harness using a milliohm meter. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0029] The insulation of the wiring harness is damaged due to damage to the outer sheath, improper operation or incorrect installation of the wiring harness. When the damaged position of the wiring harness is connected to the vehicle body (the vehicle body is connected to the negative pole of the power supply), causing the wiring harness to short-circuit to the negative pole of the power supply, the wiring harness is hit, that is, a wire pressing fault occurs. The hit position is the position where the insulation of the wiring harness is damaged and connected to the vehicle body.

[0030] In order to determine the location of the wire harness being struck, the present invention provides a method for determining the location of the wire harness being struck using a milliohmmeter, referring to Figure 1 As shown, the following steps are included:

[0031] Step 1: Confirm the faulty wiring harness;

[0032] Step 2: Select a standard wire according to the faulty wire harness, wherein the standard wire has the same material and cross-sectional area as the faulty wire harness, and the length of the standard wire is set to L0;

[0033] Step 3: Use the four-probe method of the milliohm meter to measure the resistance R0 of the standard wire;

[0034] Step 4: Disconnect the components at both ends of the faulty wiring harness, and use the four-probe method of the milliohm meter to measure the resistance R1 between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness;

[0035] Step 5: Calculate the harness length L1 between the measuring end of the fault harness and the forging point of the fault harness according to formula (1):

[0036] L1=(R1 / R0)*L0, formula (1).

[0037] When electrical components and corresponding wiring harnesses are assembled in the vehicle, if a short circuit fault occurs during the inspection of the electrical components, the wiring harness with the short circuit fault can be found through a multimeter, that is, the faulty wiring harness can be confirmed through the multimeter, which is simple to find and easy to operate. The resistance of several commonly used wires in vehicles is in the milliohm level per meter. The minimum range of the ohm range of an ordinary multimeter is 200 ohms, and the accuracy is generally 0.1 ohms. Using a multimeter can only find the faulty wiring harness, but cannot measure the resistance value of the wiring harness. The milliohm range accuracy of the milliohm meter can reach 0.1 milliohm, which can be used to measure the resistance value of the wiring harness.

[0038] After confirming the faulty harness, you can select a standard wire based on the faulty harness and use the milliohmmeter's four-probe method to measure the resistance R0 of the standard wire. The standard wire and the faulty harness have the same material and cross-sectional area, so that the resistance per unit length of the standard wire and the faulty harness are the same. The standard wire can use the same harness as the faulty harness to improve the consistency of the measurement. When measuring, you can clamp the end wire of the standard wire with the milliohmmeter's Kelvin clip and press the end wire with the probe.

[0039] When measuring the resistance R1 between the measuring end of the faulty harness and the forging point of the faulty harness, it is necessary to disconnect the components at both ends of the faulty harness. After disconnecting the faulty harness from the components at both ends, either end of the faulty harness can be used as the measuring end. The body-in-white is an equipotential body. The forging point of the faulty harness is at the same potential as any position of the body-in-white. When measuring, the Kelvin clamp of the milliohmmeter can be clamped to the pin of the terminal of the faulty harness, and then the probe of the milliohmmeter can be touched to the appropriate position of the body-in-white. The probe can also be used to touch the conductor parts connected to the body-in-white, such as metal bolts, metal brackets, etc., which are at the same potential as the body-in-white. The resistance R1 between the measuring end of the faulty harness and the forging point of the faulty harness can be measured. The connection of the milliohmmeter can be flexibly operated according to the on-site situation. When the Kelvin clamp cannot be directly inserted into the accommodation space of the measuring end terminal of the faulty harness to clamp the pin of the measuring end terminal, a suitable transition terminal is connected to the measuring end terminal, and the Kelvin clamp is used to clamp the pin of the transition terminal.

[0040] After measuring the resistance R0 of the standard wire and the resistance R1 between the measuring end of the faulty wire and the ironing point of the faulty wire, the length L1 of the wire between the measuring end of the faulty wire and the ironing point of the faulty wire can be calculated by formula (1) according to Ohm's law to confirm the ironing position of the wire. By measuring the resistance R0 of the standard wire and the resistance R1 between the measuring end of the faulty wire and the ironing point of the faulty wire using the four-probe method of the milliohm meter, the influence of the contact resistance on the test instrument equipment can be minimized, thereby achieving high-precision, precise measurement of small resistances and improving the accuracy of the measurement results.

[0041] After confirming the forging position of the wire harness, it is necessary to repair the forging position of the wire harness. The method also includes: removing the vehicle parts that are L1 away from the measuring end of the faulty wire harness along the extension direction of the faulty wire harness, so that part of the wire harness that is L1 away from the measuring end of the faulty wire harness is exposed. The distance L1 between the forging point of the wire harness and the measuring end of the faulty wire harness is the length of the wire harness between the forging point of the wire harness and the measuring end. The wire harness can be arranged along a straight line, or along a curve or a broken line. According to the arrangement of the wire harness, the position of the vehicle body that is approximately L1 away from the measuring end of the faulty wire harness can be determined along the extension direction of the faulty wire harness. The surrounding parts are removed to expose the wire harness, so that it is convenient to observe the position where the faulty wire harness is damaged or exposed and in contact with the vehicle body. The forging position is repaired to eliminate the wire pressing fault. After confirming the forging position of the wire harness, only partial disassembly is required, the disassembly range is small, labor time is saved, and maintenance is convenient.

[0042] Preferably, the length L0 of the standard wire is set to 50-100 cm, for example, the length of the standard wire can be set to 50 cm, 60 cm, 70 cm, 80 cm, 90 cm, 100 cm, etc. The length L0 of the standard wire needs to be convenient for operation when measuring the resistance R0 of the standard wire, and at the same time, the standard wire is as long as possible to reduce the influence of contact resistance and improve the accuracy of measurement.

[0043] The method further includes using a milliohmmeter's four-probe method to measure the resistance R0 of the standard conductor and the resistance R1 between the measuring end of the faulty harness and the ironing point of the faulty harness, performing multiple measurements, for example, 2, 3, 4, 5 measurements, etc., and calculating the corresponding average values. and , improve the accuracy of measurement, and make the measurement result accurate and reliable. Accordingly, the method also includes the following steps: and Calculate the harness length L1 between the measuring end of the fault harness and the ironing point of the fault harness. . Preferably, more than three measurements can be performed and the average value can be taken to increase the accuracy of the measurement. For example, the faulty wiring harness is a wire with a cross-sectional area of ​​0.75 mm², and the indoor temperature is about 20°C. The resistance R0 of the standard wire with a cross-sectional area of ​​0.75 mm² and a length L0 of 50 cm and the resistance R1 between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness are measured using the milliohm range of the METRA HIT 27I milliohm meter. The measurement results are shown in Table 1:

[0044] Table 1 Resistance values ​​measured using a milliohm meter

[0045]

[0046] The average value of the resistance of 50cm long standard wire measured 4 times 20.1mΩ, the average value of the resistance between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness is 58.7mΩ, The length L1 of the faulty wire harness between the measuring end of the faulty wire harness and the forging point of the faulty wire harness is about 150 cm. It can be determined that along the extending direction of the faulty wire harness, the point about 150 cm from the measuring end of the faulty wire harness is the forging position of the wire harness.

[0047] The layout of automotive wiring harnesses is complex on vehicles. After measuring the resistance R0 of a standard wire with the same wire diameter and known length as the faulty wiring harness and the resistance R1 between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness through a milliohm meter, the location of the ironing point, that is, the wire pressing position, can be accurately found by comparing the resistance R1 with the resistance R0. The Ohm's law can be directly applied to the maintenance and diagnosis of automotive electrical faults. It is simple and efficient, the fault point is found quickly and accurately, and the wiring harness is not damaged during detection, and the implementation is simple. After removing the surrounding parts at the wire pressing position, the ironing position of the wiring harness can be repaired, and the connection between the faulty wiring harness and the car body can be eliminated. Large-scale disassembly of the automotive wiring harness and surrounding parts can be avoided. Only partial disassembly is required, and the disassembly range is small, which reduces damage to interior parts, short working hours, and high efficiency. Fault analysis and problem wiring harness repair can be completed in about 10 minutes, which can save more than 400,000 yuan in maintenance costs each year.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the position of a wire harness using a milliohm meter, characterized in that: The following steps are involved: Step 1: Confirm the faulty wiring harness; Step 2: Select a standard wire according to the faulty wire harness, wherein the standard wire has the same material and cross-sectional area as the faulty wire harness, and the length of the standard wire is set to L0; Step 3: Use the four-probe method of the milliohm meter to measure the resistance R0 of the standard wire; Step 4: Disconnect the components at both ends of the faulty wiring harness, and use the four-probe method of the milliohm meter to measure the resistance R1 between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness; Step 5: Calculate the harness length L1 between the measuring end of the fault harness and the forging point of the fault harness according to formula (1): L1=(R1 / R0)*L0, formula (1).

2. The method for determining the forging position of a wiring harness using a milliohmmeter according to claim 1, characterized in that: The method includes finding the faulty wiring harness by using a multimeter.

3. The method for determining the forging position of a wiring harness using a milliohmmeter according to claim 1, characterized in that: The length L0 of the standard wire is set to 50-100 cm.

4. The method for determining the forging position of a wiring harness using a milliohmmeter according to claim 1, characterized in that: The method further includes using a milliohmmeter's four-probe method to measure the resistance R0 of the standard conductor and the resistance R1 between the measuring end of the faulty wiring harness and the ironing point of the faulty wiring harness, performing multiple measurements, and calculating the corresponding average values. and .

5. The method for determining the forging position of a wiring harness using a milliohmmeter according to claim 4, characterized in that: The method further comprises the step of averaging and Calculate the harness length L1 between the measuring end of the fault harness and the ironing point of the fault harness. .

6. The method for determining the forging position of a wiring harness using a milliohmmeter according to claim 1, characterized in that: The method further comprises: when the Kelvin clamp cannot be directly inserted into the accommodation space of the faulty wiring harness measuring end terminal to clamp the pin of the measuring end terminal, connecting a matching transition terminal to the measuring end terminal and using the Kelvin clamp to clamp the pin of the transition terminal.

7. The method for determining the forging position of a wiring harness using a milliohmmeter according to claim 1, characterized in that: The method further includes: removing vehicle components that are at a distance L1 from the measuring end of the faulty wire harness along the extending direction of the faulty wire harness, so that a portion of the wire harness that is at a distance L1 from the measuring end of the faulty wire harness is exposed.

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