Ignition coil test bench and test method thereof

Abstract

The application provides a kind of ignition coil test bench and its testing method, including for ignition coil power supply direct current power supply, waveform generator for inputting pulse signal to ignition coil, current amplifier and current clamp for detecting primary coil magnetizing current, high voltage attenuator for detecting the voltage generated by secondary coil, oscilloscope for displaying current signal and voltage signal, high voltage resistance and capacitance for simulating spark plug, the function of primary coil is judged by current signal, and the function of secondary coil is judged by voltage signal.The test bench of the application is simple in structure, easy to use, can test the function of ignition coil separately from the whole vehicle, can simulate the signal output by engine control unit under different engine speeds, and test the function applicability of ignition coil under all engine speeds.

Description

Technical Field

[0001] This invention relates to the field of automotive parts testing technology, specifically to an ignition coil test bench and its testing method. Background Technology

[0002] The ignition coil is a crucial component of a car engine's ignition system. It converts the vehicle's low-voltage electricity into high voltage, supplying it to the spark plugs to generate an electric spark that ignites the air-fuel mixture in the cylinders. If the ignition coil fails, the spark plugs cannot ignite properly, severely impacting the vehicle's normal operation. Analyzing the causes of ignition coil failure often requires testing the coil in an environment separate from the vehicle, while simultaneously simulating the operation of the ignition coil under full-vehicle conditions. This allows for timely and accurate identification of the cause of ignition coil failure, prompting manufacturers to make improvements and enhancing the company's brand image.

[0003] Invention Patent Content

[0004] To address the aforementioned technical problems, this invention provides an ignition coil test bench and its testing method. The ignition coil is connected to the test bench, and the magnetizing current of the primary coil and the voltage generated by the secondary coil are measured. The state of the primary and secondary coils is determined based on the measurement results of the current and voltage. Furthermore, a waveform generator is used to simulate different engine speeds, and the working state of the ignition coil at different engine speeds is measured.

[0005] The present invention solves the technical problem by adopting the following technical solution:

[0006] An ignition coil test bench includes a DC power supply, a waveform generator, a current amplifier, a current clamp, an oscilloscope, a high-voltage attenuator, a high-voltage resistor, and a capacitor; wherein,

[0007] The positive terminal of the DC power supply is used to connect to the positive terminal of the ignition coil, and the negative terminal of the DC power supply is used to connect to the negative terminal of the ignition coil to supply power to the ignition coil; the waveform generator is used to connect to the ignition coil signal interface to simulate the signal output by the engine control unit and input a pulse signal to the ignition coil.

[0008] The jaws of the current clamp are used to clamp the connection between the positive terminal of the DC power supply and the positive terminal of the ignition coil. The output terminal of the current clamp is connected to the input terminal of the current amplifier, and the output terminal of the current amplifier is connected to an oscilloscope to measure the magnetizing current of the primary coil of the ignition coil.

[0009] The high-voltage resistor is connected in parallel with the capacitor. One end of the high-voltage resistor is used to ground, and the other end is used to connect to the high-voltage output terminal of the secondary coil of the ignition coil to simulate a spark plug.

[0010] The input terminal of the high-voltage attenuator is connected to the high-voltage output terminal of the secondary coil of the ignition coil, and the output terminal of the high-voltage attenuator is connected to an oscilloscope to measure the voltage generated by the secondary coil of the ignition coil.

[0011] Furthermore, the DC power supply is a constant voltage power supply; or the output voltage of the DC power supply is adjustable, and the output voltage of the DC power supply can be adjusted as needed.

[0012] Furthermore, the high-voltage resistor is a variable resistor or a fixed resistor.

[0013] Furthermore, the high-voltage resistor is composed of multiple resistors connected in series, in parallel, or in a series-parallel configuration.

[0014] Furthermore, the high-voltage resistor and capacitor are sealed by a plastic shell, thus sealing the high-voltage side and improving safety.

[0015] Furthermore, an ignition coil testing method, using the aforementioned ignition coil test bench, includes the following steps:

[0016] S1. Connect the ignition coil to the ignition coil test bench, turn on the DC power switch, and adjust the voltage to the required voltage.

[0017] S2. Open the waveform generator, select the PWM signal, and adjust the frequency, pulse width, and amplitude;

[0018] S3. Turn on the current amplifier, high voltage attenuator, and oscilloscope. Adjust the oscilloscope parameters so that the waveform output by the waveform generator, the current signal output by the current amplifier, and the voltage signal output by the high voltage attenuator can be displayed on the oscilloscope.

[0019] S4. Observe the current and voltage displayed on the oscilloscope to determine the state of the primary and secondary coils:

[0020] (1) If the current I is less than the lower limit of the normal magnetizing current Imin, the primary coil is open-circuited; if the current I is greater than the upper limit of the normal magnetizing current Imax, the primary coil is short-circuited between intermediate turns; if the current I is greater than or equal to the lower limit of the normal magnetizing current Imin and less than or equal to the upper limit of the normal magnetizing current Imax, the primary coil is qualified.

[0021] (2) If the voltage U is less than the standard voltage U0, the secondary coil is deemed unqualified; if the voltage U is greater than or equal to the standard voltage U0, the secondary coil is deemed qualified.

[0022] Furthermore, the lower limit Imin of the normal magnetizing current is 80%-90% of the standard current value I0, and the upper limit Imax of the normal magnetizing current is 110%-120% of the standard current value I0.

[0023] Furthermore, while keeping the amplitude and pulse width of the waveform generator constant, the frequency of the waveform generator is adjusted to output waveforms of different frequencies, simulating the signals output by the engine control unit at different engine speeds.

[0024] Furthermore, the frequency of the waveform generator includes the frequency corresponding to the lowest engine speed and the frequency corresponding to the highest engine speed, to test the working state of the ignition coil at the lowest and highest engine speeds.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) The test bench has a simple structure and is easy to use. It can test the function of the ignition coil separately from the whole vehicle and can determine the function of the primary and secondary coils of the ignition coil.

[0027] (2) The test bench can simulate the signals output by the engine control unit at different engine speeds and test the functional applicability of the ignition coil at all engine speeds. Attached Figure Description

[0028] Figure 1 This is a circuit diagram for testing the ignition coil of the present invention.

[0029] In the diagram: 1-DC power supply; 2-waveform generator; 3-current amplifier; 4-current clamp; 5-oscilloscope; 6-high voltage attenuator; 7-high voltage resistor; 8-capacitor; 9-ignition coil; 91-primary coil; 92-secondary coil. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] This invention provides an ignition coil test bench, such as Figure 1As shown, the system includes a DC power supply 1, a waveform generator 2, a current amplifier 3, a current clamp 4, an oscilloscope 5, a high-voltage attenuator 6, a high-voltage resistor 7, and a capacitor 8. The positive terminal of the DC power supply 1 is connected to the positive terminal of the ignition coil 9, and the negative terminal of the DC power supply 1 is connected to the negative terminal of the ignition coil 9. The DC power supply 1 supplies power to the ignition coil 9. When the ignition coil 9 has two negative terminals, both negative terminals must be connected to the negative terminal of the DC power supply 1. The DC power supply 1 can be a constant voltage power supply, outputting a voltage suitable for the ignition coil 9. Preferably, the output voltage of the DC power supply 1 can also be set to be adjustable, allowing adjustment of the output voltage as needed. The waveform generator 2 is connected to the signal interface of the ignition coil 9 to simulate the signal output by the engine control unit, providing a pulse signal to the ignition coil 9. The jaws of the current clamp 4 are used to clamp the connection between the positive terminal of the DC power supply 1 and the positive terminal of the ignition coil 9. The output terminal of the current clamp 4 is connected to the input terminal of the current amplifier 3, and the output terminal of the current amplifier 3 is connected to the oscilloscope 5 to acquire the magnetizing current of the primary coil 91 of the ignition coil 9. The high-voltage resistor 7 is connected in parallel with the capacitor 8. One end of the high-voltage resistor 7 is grounded, and the other end is connected to the high-voltage output terminal of the secondary coil 92 of the ignition coil 9 to simulate a spark plug. The input terminal of the high-voltage attenuator 6 is connected to the high-voltage output terminal of the secondary coil 92 of the ignition coil 9, and the output terminal of the high-voltage attenuator 6 is connected to the oscilloscope 5 to acquire the voltage generated by the secondary coil 92 of the ignition coil 9.

[0032] According to the NTC-TL82343 German Volkswagen ignition coil test standard, different high-voltage resistors 7 and capacitors 8 can be selected for testing. The high-voltage resistor 7 can be a variable resistor or a fixed resistor. Preferably, the high-voltage resistor 7 is composed of multiple resistors connected in series, parallel, or series-parallel. The high-voltage output terminal of the secondary coil 92 of the ignition coil 9 is connected to different interfaces, and high-voltage resistors 7 with different resistance values ​​can be selected. Since the secondary coil 92 of the ignition coil 9 outputs high voltage, which is dangerous, the high-voltage resistor 7 and capacitor 8 can be sealed with a plastic shell to seal the high-voltage side and improve safety.

[0033] The present invention also provides a method for testing ignition coils, using the aforementioned ignition coil test bench, comprising the following steps:

[0034] S1. Connect the ignition coil 9 to the ignition coil test bench, turn on the DC power supply 1 switch, and adjust the voltage to the required voltage.

[0035] S2. Turn on waveform generator 2, select PWM signal, and adjust frequency, pulse width and amplitude;

[0036] S3. Turn on the current amplifier 3, the high voltage attenuator 6 and the oscilloscope 5, and adjust the parameters of the oscilloscope 5 so that the waveform output by the waveform generator 2, the current signal output by the current amplifier 3 and the voltage signal output by the high voltage attenuator 6 can be displayed on the oscilloscope 5.

[0037] S4. Observe the current and voltage displayed on oscilloscope 5 to determine the state of primary coil 91 and secondary coil 92:

[0038] (1) If the current I is less than the lower limit Imin of the normal magnetizing current, the primary coil 91 is open-circuited; if the current I is greater than the upper limit Imax of the normal magnetizing current, the primary coil 91 is short-circuited between intermediate turns; if the current I is greater than or equal to the lower limit Imin of the normal magnetizing current and less than or equal to the upper limit Imax of the normal magnetizing current, the primary coil 91 is qualified.

[0039] (2) If the voltage U is less than the standard voltage U0, the secondary coil 92 is deemed unqualified; if the voltage U is greater than or equal to the standard voltage U0, the secondary coil 92 is deemed qualified.

[0040] During testing, connect the positive terminal of ignition coil 9 to the positive terminal of DC power supply 1, and connect the negative terminal of ignition coil 9 to the negative terminal of DC power supply 1. Connect the signal interface of ignition coil 9 to waveform generator 2. Connect the high-voltage output terminal of the secondary coil 92 of ignition coil 9 to the input terminals of high-voltage resistor 7 and high-voltage attenuator 6. Connect ignition coil 9 to the test bench. After connecting ignition coil 9 to the test bench, turn on the switch of DC power supply 1 and adjust the voltage to 14V to provide 14V DC voltage to ignition coil 9. Then turn on waveform generator 2, select duty cycle (PWM) signal, and adjust the frequency, pulse width, and amplitude to simulate the engine control unit outputting duty cycle signals of different frequencies at different engine speeds, inputting pulse signals to ignition coil 9. Then turn on current amplifier 3, high-voltage attenuator 6, and oscilloscope 5, and adjust the parameters of oscilloscope 5 so that the waveform output by waveform generator 2, the current signal output by current amplifier 3, and the voltage signal output by high-voltage attenuator 6 can be displayed on oscilloscope 5. Once the current and voltage signal curves appear on oscilloscope 5, the current and voltage can be monitored, and the state of the primary coil 91 and the secondary coil 92 can be determined.

[0041] If the current I displayed on oscilloscope 5 is less than the lower limit Imin of the normal magnetizing current, the primary coil 91 is determined to be open-circuited; if the current I displayed on oscilloscope 5 is greater than the upper limit Imax of the normal magnetizing current, the primary coil 91 is determined to be short-circuited between intermediate turns; if the current I displayed on oscilloscope 5 is greater than or equal to the lower limit Imin of the normal magnetizing current and less than or equal to the upper limit Imax of the normal magnetizing current, the primary coil 91 is determined to be qualified.

[0042] If the voltage U displayed by the oscilloscope 5 is less than the standard voltage U0, it is determined that the secondary coil 92 is unqualified; if the voltage U displayed by the oscilloscope 5 is greater than or equal to the standard voltage U0, it is determined that the secondary coil 92 is qualified.

[0043] The upper limit Imax and lower limit Imin of the normal magnetizing current can be obtained from the standard current value I0, wherein the lower limit Imin of the normal magnetizing current is 80%-90% of the standard current value I0, and the upper limit Imax of the normal magnetizing current is 110%-120% of the standard current value I0.

[0044] According to the NTC-TL82343 test standard for ignition coils of Volkswagen Group Germany, the frequency of the waveform generator 2 can be set to 50 Hz, the amplitude can be set to 5 V, and the pulse width can be set to 2 ms. In this case, the standard current value I0 is 7 A. When the magnetizing current of the primary coil 91 of the ignition coil 9 is about 7 A, the primary coil 91 is qualified; the upper limit Imax of the normal magnetizing current can be set to 8 A, and the lower limit Imin of the normal magnetizing current can be set to 6 A. When I < 6 A, it can be determined that an open circuit occurs in the primary coil 91. When I > 8 A, it can be determined that inter-turn short circuit occurs in the primary coil 91. When 6 A ≤ I ≤ 8 A, it can be determined that the primary coil 91 is qualified.

[0045] According to the NTC-TL82343 test standard for ignition coils of Volkswagen Group Germany, as shown in Table 1 below, it is the high voltage required for spark plug ignition when different high-voltage resistors 7 are selected to match capacitors 8 to simulate spark plugs.

[0046] Table 1 High voltage standards to be generated by the secondary coil

[0047]

[0048] In the present invention, a high-voltage resistor 7 of 1 MΩ and a capacitor 8 of 25 pF can be selected. In this case, the standard voltage U0 is 28.5 kV, and the quality of the secondary coil 92 can be determined by comparing the voltage U displayed by the oscilloscope 5 with the standard voltage U0. When U < 28.5 kV, the secondary coil 92 can be determined to be unqualified; when U ≥ 28.5 kV, the secondary coil 92 can be determined to be qualified. When the high-voltage resistor 7 is configured as a variable resistor, high-voltage resistors 7 with different resistance values and different standard voltages U0 can be selected by connecting the high-voltage output end of the secondary coil 92 of the ignition coil 9 to different interfaces.

[0049] When the engine operates at different speeds and the engine control unit outputs duty cycle signals of different frequencies, the ignition coil 9 must function normally. Therefore, functional testing of the ignition coil 9 is necessary across all engine speed ranges. When adjusting the pulse signal of the waveform generator 2, the amplitude and pulse width of the waveform generator 2 can be kept constant while adjusting its frequency to output waveform signals of different frequencies, simulating the signals output by the engine control unit at different engine speeds. The frequency of the waveform generator 2 needs to include the frequencies corresponding to the lowest and highest engine speeds. Measuring the operating status of the ignition coil 9 at the lowest and highest engine speeds allows for assessment of its functionality. Furthermore, the function of the ignition coil 9 can be measured at multiple frequencies between the lowest and highest frequencies of the waveform generator 2. This allows for measurement of the ignition coil 9's functionality across all engine speeds, determining whether its function is normal across the entire engine speed range.

[0050] Taking a specific engine as an example, the engine speed ranges from 680U / min to 6400U / min, corresponding to frequencies of 11.3Hz to 107Hz. During testing, the waveform generator 2 is kept at an amplitude of 5V and a pulse width of 2ms. The frequencies of the waveform generator 2 are adjusted to 11.3Hz and 107Hz respectively to test the ignition coil 9, measuring its functionality at both the lowest and highest engine speeds. If the magnetizing current of the primary coil 91 and the high voltage generated by the secondary coil 92 are normal, it indicates that the ignition coil 9 functions normally at both the lowest and highest engine speeds. The frequency of the waveform generator 2 is then adjusted to several other frequencies between 11.3Hz and 107Hz, such as 20Hz, 30Hz, 40Hz, 50Hz, ..., 100Hz, and the functionality of the ignition coil 9 is measured again. If the ignition coil 9 functions normally at all tested frequencies, it indicates that the ignition coil 9 is qualified. If the ignition coil 9 fails to function properly at a certain frequency or at certain frequencies, it indicates that the ignition coil 9 is defective.

[0051] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ignition coil test bench, characterized in that, This includes a DC power supply, waveform generator, current amplifier, current clamp, oscilloscope, high-voltage attenuator, high-voltage resistor, and capacitor; among which, The positive terminal of the DC power supply is used to connect to the positive terminal of the ignition coil, and the negative terminal of the DC power supply is used to connect to the negative terminal of the ignition coil. The waveform generator is used to connect to the ignition coil signal interface and can output waveform signals of multiple frequencies corresponding to the engine's lowest to highest speeds. The jaws of the current clamp are used to clamp the connection between the positive terminal of the DC power supply and the positive terminal of the ignition coil. The output terminal of the current clamp is connected to the input terminal of the current amplifier, and the output terminal of the current amplifier is connected to an oscilloscope to acquire the magnetizing current of the primary coil of the ignition coil. The high-voltage resistor is connected in parallel with the capacitor. One end of the high-voltage resistor is used to ground, and the other end is used to connect to the high-voltage output terminal of the secondary coil of the ignition coil. The input terminal of the high voltage attenuator is used to connect to the high voltage output terminal of the secondary coil of the ignition coil, and the output terminal of the high voltage attenuator is connected to an oscilloscope to acquire the voltage generated by the secondary coil of the ignition coil. The oscilloscope is used to display the magnetizing current of the primary coil of the ignition coil and the voltage generated by the secondary coil of the ignition coil. It is also used to compare the current displayed on the oscilloscope with the normal magnetizing current to determine whether the primary coil is open-circuited or whether there is a short circuit between intermediate turns. Furthermore, it is used to compare the voltage displayed on the oscilloscope with the standard voltage to determine whether the secondary coil is qualified.

2. The ignition coil test bench according to claim 1, characterized in that, The DC power supply is a constant voltage power supply; or the output voltage of the DC power supply is adjustable.

3. The ignition coil test bench according to claim 1, characterized in that, The high-voltage resistor is either a variable resistor or a fixed resistor.

4. The ignition coil test bench according to claim 3, characterized in that, The high-voltage resistor is composed of multiple resistors connected in series, in parallel, or in a series-parallel configuration.

5. The ignition coil test bench according to claim 3 or 4, characterized in that, The high-voltage resistor and capacitor are sealed with a plastic casing.

6. A method for testing an ignition coil, characterized in that, Using the ignition coil test bench according to any one of claims 1-5, the following steps are included: S1. Connect the ignition coil to the ignition coil test bench, turn on the DC power switch, and adjust the voltage to the required voltage. S2. Open the waveform generator, select the PWM signal, and adjust the frequency, pulse width, and amplitude; S3. Turn on the current amplifier, high voltage attenuator, and oscilloscope. Adjust the oscilloscope parameters so that the waveform output by the waveform generator, the current signal output by the current amplifier, and the voltage signal output by the high voltage attenuator can be displayed on the oscilloscope. S4. Observe the current and voltage displayed on the oscilloscope to determine the state of the primary and secondary coils: If the current I is less than the lower limit of the normal magnetizing current Imin, the primary coil is considered to be open-circuited; if the current I is greater than the upper limit of the normal magnetizing current Imax, the primary coil is considered to be short-circuited between intermediate turns; if the current I is greater than or equal to the lower limit of the normal magnetizing current Imin and less than or equal to the upper limit of the normal magnetizing current Imax, the primary coil is considered to be qualified. If the voltage U is less than the standard voltage U0, the secondary coil is considered unqualified; if the voltage U is greater than or equal to the standard voltage U0, the secondary coil is considered qualified.

7. The ignition coil testing method according to claim 6, characterized in that, The lower limit Imin of the normal magnetizing current is 80%-90% of the standard current value I0, and the upper limit Imax of the normal magnetizing current is 110%-120% of the standard current value I0.

8. The ignition coil testing method according to claim 6, characterized in that, Keeping the amplitude and pulse width of the waveform generator constant, adjust the frequency of the waveform generator to output waveforms of different frequencies.

9. The ignition coil testing method according to claim 8, characterized in that, The frequency of the waveform generator includes the frequency corresponding to the lowest engine speed and the frequency corresponding to the highest engine speed.

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