Automatic test system for PTC (Positive Temperature Coefficient) element

Abstract

The utility model belongs to the field of PTC (Positive Temperature Coefficient) elements, and particularly discloses an automatic test system for PTC elements, which comprises an element conveying line and a maximum current test device arranged on the element conveying line, the maximum current testing device comprises a heating unit, a first temperature measuring unit, a second temperature measuring unit and a current measuring unit along the conveying direction of the element conveying line; the first temperature measuring unit, the second temperature measuring unit and the current measuring unit are respectively provided with a temperature sensor corresponding to each PTC element. The PTC element automatic test system further comprises a central control device which is in signal connection with the heating unit, the first temperature measurement unit, the second temperature measurement unit and the current measurement unit. According to the invention, the temperature of the PTC element can be continuously measured, the adjustment can be conveniently carried out under the condition that the environment temperature is changed, and the maximum current measurement can be carried out under the most suitable temperature state; and the measurement error caused by the change of the normal temperature resistance of the PTC element and the inherent characteristics of the material and the change of the environment temperature is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of PTC elements, and more particularly relates to an automatic testing system for PTC elements. BACKGROUND

[0002] PTC elements generally refer to a kind of thermistor elements with positive temperature coefficient of resistance, which are widely used in communication equipment, household appliances, electric vehicles and other industries.

[0003] The maximum current (Imax) of a PTC element refers to the maximum transient current flowing through the element when a certain voltage is applied to the PTC element. The conventional method for measuring the maximum current value is to directly apply a certain voltage V to the product at room temperature (25℃) and measure the Imax value flowing through the sample. However, a large number of test facts have shown that the above method often results in different measurement results for multiple measurements, poor repeatability of measurement results, and poor stability of the final product due to inconsistent power matching, which may cause safety hazards.

[0004] Patent document CN117870912A discloses a method and device for measuring the maximum current of a PTC element, which uniformly applies a voltage to all PTC elements and measures their maximum current. However, due to the possible changes in the environmental temperature of the production line, and the differences in the actual temperatures of different samples after heating under the same voltage and time due to their different resistance values, the time for reducing to the optimal measurement temperature range is also different. If the measurement is performed simultaneously under pressure, measurement errors may occur. UTILITY MODEL CONTENT

[0005] In view of the defects of the prior art, the purpose of the present application is to improve the measurement accuracy of the maximum current testing device by setting multiple temperature sensors for each PTC element to be measured along the element conveying line.

[0006] To achieve the above purpose, the present application provides an automatic testing system for PTC elements, which comprises an element conveying line and a maximum current testing device arranged on the element conveying line. The maximum current testing device comprises, in sequence along the conveying direction of the element conveying line, a heating unit, a first temperature measuring unit, a second temperature measuring unit, and a current measuring unit. Temperature sensors corresponding to each PTC element are arranged on the first temperature measuring unit, the second temperature measuring unit, and the current measuring unit.

[0007] The automatic testing system for PTC elements further comprises a central control device signal-connected with the heating unit, the first temperature measuring unit, the second temperature measuring unit, and the current measuring unit, respectively.

[0008] The element conveying line is used to transport the PTC element between different devices or units, the heating unit is used to heat the PTC element to make its temperature exceed its Curie temperature Tc, the first temperature measuring unit and the second temperature measuring unit are used to monitor the temperature of the PTC element moving on the element conveying line, and the current measuring unit is used to apply a measuring voltage to the PTC element and measure its maximum current when the temperature of the PTC element drops to a preset measuring temperature.

[0009] The central control device is used to collect the measuring signals of the temperature sensors and control the current measuring unit to apply a measuring voltage to the PTC element and measure its maximum current.

[0010] Preferably, the current measuring unit comprises measuring probes corresponding to the number of PTC elements, the temperature sensors are arranged on the measuring probes, and each measuring probe further comprises a pressurizing element and a current detecting element.

[0011] Preferably, along the element conveying line, a grading unit connected to the central control device in signal is further included after the current measuring unit.

[0012] As a further preference, a first screening unit connected to the central control device in signal is further included between the first temperature measuring unit and the second temperature measuring unit, and a second screening unit connected to the central control device in signal is further included between the current measuring unit and the grading unit.

[0013] As a further preference, a packaging unit is further included along the element conveying line after the grading unit.

[0014] Preferably, a withstand voltage test device, a temperature stabilizing device and a zero-power resistance test device are further included in sequence along the conveying direction of the element conveying line before the maximum current test device, a surface detection device is further included along the element conveying line after the maximum current test device, and the withstand voltage test device, the temperature stabilizing device, the zero-power resistance test device and the surface detection device are respectively connected to the central control device in signal.

[0015] As a further preference, a feeding device connected to the central control device in signal is further included along the element conveying line before the withstand voltage test device.

[0016] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0017] 1. The application first heats the PTC element through a heating unit, and then monitors the temperature of the PTC element through a first temperature measuring unit and a second temperature measuring unit arranged on the element conveying line, so as to ensure continuous measurement of the temperature of the PTC element during the conveying process of the element conveying line, facilitate adjustment in the case of change in ambient temperature, and ensure that the PTC element reaches the maximum current testing device at the most suitable temperature state and performs maximum current measurement;

[0018] 2. A separate temperature sensor is arranged for each PTC element. When the temperature of the PTC element decreases to the optimal test temperature interval (i.e. between 20% and 60% of the Curie temperature Tc) on the current measuring unit, the voltage is immediately applied by the pressure element in the respective probe, and the Imax is quickly extracted by the current detection element, so that the test temperature is more accurate, the final test result is more accurate and repeatable, and the measurement error caused by the change of the normal temperature resistance of the PTC element and the inherent characteristics of the material, as well as the change of the ambient temperature, is reduced. It has been verified that the measurement fluctuation of the maximum current value can be reduced to 1% to 2%;

[0019] 3. Preferably, the PTC element testing process requires multiple parameters to be measured and screened automatically by simultaneously arranging a pressure resistance testing device, a temperature stabilizing device, a zero-power resistance testing device, etc. on the element conveying line;

[0020] 4. Preferably, a first screening unit, a second screening unit and a grading unit are arranged to automatically sort out defective products and recycle non-defective products that are not normally tested, and to automatically grade the maximum current value. The unified signal collection and control of the devices are realized through the central control device, the human factors are excluded, and the testing efficiency is greatly improved. This high-precision automatic testing method and system greatly improve the testing efficiency and testing accuracy, and reduce the cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of the front structure of the PTC element automatic testing system provided by the embodiment of the application;

[0022] Figure 2 is a schematic diagram of the middle structure of the PTC element automatic testing system provided by the embodiment of the application;

[0023] Figure 3 is a schematic diagram of the rear structure of the PTC element automatic testing system provided by the embodiment of the application;

[0024] Figure 4 is a schematic diagram of the structure of the maximum current testing device provided by the embodiment of the application;

[0025] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0026] 1-Feeding device, 2-Performance pressure testing device, 3-Temperature stabilizing device, 4-Robot material handling unit, 5-Zero power resistance testing device, 6-Heating unit, 7-Current measurement unit, 8-Surface inspection device, 9-Sorting unit, 10-Automatic guided vehicle, 11-1-First screening unit, 11-2-Second screening unit, 11-3-Third screening unit, 11-4-Fourth screening unit, 12-1-First temperature measurement unit, 12-2-Second temperature measurement unit, 13-Bag input distribution line, 14-Tooling plate conveyor line, 15-Bag output line, 16-Current detection element, 17-Temperature sensor, 18-Measuring probe, 19-Tooling plate, 20-PTC element, 21-Robotic arm. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0028] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0029] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0031] In this application, unless specifically defined and limited otherwise, the terms "mounting", "connected", "connection", "fixed", and the like, should be construed broadly and, for example, can be a fixed connection, or a detachable connection, or an integrally connected; can be a mechanical connection, or an electrical connection; can be a direct connection, or an indirect connection through an intermediate medium, or a communication inside two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0032] The application provides a PTC element automatic testing system, which comprises an element conveying line, and a feeding device 1, a pressure resistance testing device 2, a temperature stabilizing device 3, a zero-power resistance testing device 5, a maximum current testing device and a surface testing device 8 are sequentially arranged along the element conveying line; the PTC element automatic testing system is further provided with a central control device connected with the element conveying line and other devices, as shown in Figures 1-3 .

[0033] The maximum current testing device comprises a heating unit 6, a first temperature measuring unit 12-1, a second temperature measuring unit 12-2 and a current measuring unit in sequence along the conveying direction of the element conveying line, and the first temperature measuring unit 12-1, the second temperature measuring unit 12-2 and the current measuring unit are all provided with a temperature sensor corresponding to each PTC element; the heating unit 6 is used to apply a voltage to the PTC element, so that the temperature of the PTC element is higher than its Curie temperature Tc, the current measuring unit is used to measure the maximum current value of the PTC element when the temperature of the PTC element is reduced to 20%~60% of the Curie temperature Tc; and the first temperature measuring unit 12-1 and the second temperature measuring unit 12-2 are used to monitor the temperature of the PTC element when the PTC element just passes through the position, so as to ensure that the temperature of the PTC element reaches (or is slightly higher than) the preset measurement temperature T R , T R is 20%~60% of the Curie temperature Tc. If the condition is not met, the central control device will control the heating unit 6 or the element conveying line to make corresponding power adjustment.

[0034] The current measuring unit comprises a plurality of measurement probes 18 corresponding to the number of PTC elements, each of the measurement probes 18 comprises a pressure element and a current detection element 16 in addition to a temperature sensor 17, as shown in Figure 4 ; and since the pressure element and the current detection element 16 can be integrated into the same circuit, they can perform both functions at the same time.

[0035] A first screening unit 11-1 can be arranged after the first temperature measuring unit 12-1 to screen out the PTC elements that fail to heat up due to poor contact and re-detect them; a second screening unit 11-2 and / or a grading unit 9 can be arranged after the current measuring unit; the second screening unit 11-2 is used to screen out the PTC elements whose maximum current value does not meet the requirements; and the grading unit 9 is used to grade the PTC elements according to their maximum current values and then enter a packaging unit for packaging.

[0036] Embodiment 1

[0037] The embodiment discloses a PTC element multi-parameter automatic testing, screening and grading system, which includes, along an element conveying line thereof, a feeding device 1, a pressure resistance test device 2, a temperature stabilizing device 3, a zero-power resistance testing device 5, a heating unit 6, a first temperature measuring unit, a second temperature measuring unit, a first screening unit, a current measuring unit, a second screening unit, a surface detection device 8, a grading unit 9, a packaging unit and the like.

[0038] The element conveying line includes, along a conveying direction of the PTC elements, a bin input diverging line 13, a tooling plate conveying line 14, the temperature stabilizing device 3 and a bin converging output line 15; in addition, the element conveying line also includes a robot material taking unit 4, an automatic guided vehicle 10, a tooling plate 19 and a bin; the tooling plate 19 and the bin are used to fix the PTC elements 20, and the input diverging line 13, the tooling plate conveying line 14 and the bin converging output line 15 are used to transport the tooling plate 19 or the bin in which the PTC elements 20 are fixed; the PTC elements are arranged in the bin on the bin input diverging line 13, the temperature stabilizing device 3 and the bin converging output line 15; the PTC elements are arranged on the tooling plate on the tooling plate conveying line 14; the robot material taking unit 4, a mechanical arm 21 and the automatic guided vehicle 10 are used to assist the tooling plate 19 or the bin to move between the devices.

[0039] The pressure resistance test device 2, the zero-power resistance testing device 5, the current measuring unit 7 and the surface detection device 8 are respectively used to perform the functions of pressure resistance test, zero-power resistance test, maximum current test and surface detection in the automatic testing system; the heating unit 6, the pressure resistance test device 2 and the like are provided with a voltage device specially used to apply a specific voltage to the PTC elements; and a current detection element is designed in the current measuring unit 7 and the pressure resistance test device 2 to obtain the maximum current value of the PTC elements under the target voltage.

[0040] In addition, the entire automatic testing system is controlled by the central control device. The central control device is connected with the voltage device, the current measuring unit 7, the temperature monitoring device, the screening device 12, and the central control device connected with the above four devices, collects the test results of the voltage testing device 2, the zero-power resistance testing device 5, the current measuring unit 7 and the surface detection device 8, and judges whether the element is a defective product according to the test results, sends the position of the defective product to the corresponding screening unit, and instructs the screening unit to remove the defective product. According to the test results of multiple parameters, the PTC element is graded according to the preset grading standard, and the grading result is sent to the grading unit to instruct the grading unit to grade the PTC element according to the grading result.

[0041] The working process of the PTC element multi-parameter automatic testing, screening and grading system of the embodiment is as follows:

[0042] S1. Feeding and voltage testing

[0043] In the embodiment, in order to speed up the feeding and measuring speed, two feeding devices 1-1 and 1-2 and multiple voltage testing devices 2-1, 2-2 and 2-3 are arranged in the material box input distribution line 13; the PTC element to be tested is fed from the feeding device 1 into the material box input distribution line 13, and is distributed into each voltage testing device 2; the mechanical arm 21 arranged in the voltage testing device can carry the material box from the material box input distribution line to the voltage testing device, and take out the PTC element from the material box for voltage testing. The PTC element that appears breakdown in the voltage testing belongs to defective product, which is removed by the mechanical arm screening device to the defective product receiving box. The remaining PTC elements are output by the mechanical arm to the material box converging output line 15.

[0044] S2. The automatic guided vehicle 10 carries the material box from the material box converging output line 15 to the temperature stabilizing device 3, and after the PTC element is cooled, the material box enters the robot material taking unit 4 from the temperature stabilizing device, and the robot material taking unit puts the PTC element into the tooling plate 20 arranged on the tooling plate conveying line 14; the zero-power resistance testing device 5, the heating unit 6, the current measuring unit 7, the surface detection device 8 and the robot grading unit 9 are arranged on the tooling plate conveying line 14 in sequence.

[0045] S3. The tooling plate with the PTC element is conveyed to the zero-power resistance testing device 5. The four-wire method is used to measure the zero-power resistance under the condition of 1.5V voltage and 25±2℃ constant temperature, and the central control device records the resistance value of the defective product of the PTC element and the position on the tooling plate; after the measurement, the tooling plate is conveyed to the third screening unit 11-3, the third screening unit 11-3 picks up the defective product, and puts the defective product higher than the standard resistance value interval and the defective product lower than the standard resistance value interval into different receiving boxes respectively.

[0046] S4. After the third screening unit 11-3, the tooling plate is transported to the heating unit 6, and the PTC element is heated to a temperature exceeding the Curie temperature Tc. After heating, the tooling plate is cooled naturally on the cooling buffer line, and the temperature T1 is measured by the first temperature measuring unit 12-1 and the temperature T2 is measured by the second temperature measuring unit 12-2, and the data is transmitted to the control device. The first temperature measuring unit 12-1 and the second temperature measuring unit 12-2 are both provided with temperature sensors corresponding to the PTC elements on the tooling plate. When the temperature measured by the first temperature measuring unit 12-1 or the second temperature measuring unit 12-2 is too low, which may cause the temperature of the PTC element to be lower than 0.2Tc when it reaches the current measuring unit 7, it may be that the heating power of the heating unit 6 is not enough or the movement speed of the tooling plate conveying line 14 is too fast. If the temperature measured by the first temperature measuring unit 12-1 or the second temperature measuring unit 12-2 is too high, which may cause the temperature of the PTC element to be higher than 0.6Tc when it reaches the current measuring unit 7, it may be that the heating power of the heating unit 6 is too large or the movement speed of the tooling plate conveying line 14 is too slow. The control device will adjust the heating power of the heating unit 6 or the movement speed of the tooling plate conveying line 14 according to these data. A first screening unit 11-1 is arranged between the first temperature measuring unit 12-1 and the second temperature measuring unit 12-2. If the PTC element with T1 lower than TRmin is a heating failure product, it is not a defective product, and the control device sends the position of the heating failure PTC element to the first screening unit 11-1, which is placed in the recyclable product collection box by the first screening unit 11-1.

[0047] S5. The structure of the current measuring unit 7 is shown in FIG. 6. Figure 4The maximum current and the corresponding Rmin data can be obtained when the surface temperature of the PTC element reaches TRmin (TRmin is generally 20%~60%Tc according to a large amount of measured data analysis). The current measurement unit 7 is provided with measurement probes 18 corresponding to the number of PTC elements 20 on the tooling plate 19 (10 in this example), and the current measurement unit 7 is suspended when the tooling plate moves, and will be lowered to connect with the PTC element for testing when the tooling plate reaches the corresponding test station. Each test unit is provided with a current detection element 16 and a temperature sensor 17. Each temperature sensor 17 will independently continuously measure the surface temperature of the PTC element, and when the temperature decreases to TRmin±2℃, the current detection element 16 with the function of a pressurizing element on the same measurement probe 18 immediately outputs a test voltage, records the measured maximum current value Imax, and transmits the result to the central control device. The central control device calculates the corresponding minimum resistance value Rmin according to the maximum current value Imax and records the test result. The tooling plate that has completed the Rmin measurement is conveyed to the second screening device 11-2, and the defective products are removed according to the maximum current test results recorded by the central control device; in addition, the PTC elements whose temperature has been lower than TRmin when reaching the test station are not defective products, and are placed in the recyclable product receiving box by the second screening device.

[0048] S6. The tooling plate with the PTC element that has completed the Rmin measurement is conveyed to the surface detection device. The surface detection device is provided with a camera that will take photos of the six surfaces of the PTC element, and the detection results will be sent to the connected central control device. After the surface detection is completed, the tooling plate is conveyed to the fourth screening unit 11-4, and the defective products are removed by the fourth screening device 11-4 according to the detection records of the central control device and are placed in the receiving box.

[0049] S7. The tooling plate conveying line conveys the tooling plate to the grading unit 9. The central control device grades the PTC element according to the test results of the pressure resistance test, the zero-power resistance test, the maximum current test and the surface detection, and the grading standard can be customized according to actual needs. The grading unit grades the PTC element according to the grading results and places it in the corresponding grading box.

[0050] Experimental results verification

[0051] In order to verify the high precision of the test system and the reliability of the test results of the present application, the maximum current of the PTC element is actually tested by using the automatic test system.

[0052] Ten PTC element experimental samples are selected, and the Curie temperature Tc of each sample is measured by using a conventional Curie temperature tester. C=220℃, and numbered as samples 1-10. The maximum current of each sample was measured using the high-precision test system of the present application, with the test temperature TRmin selected as 60%, i.e. 132℃. After being left at 25℃ for 48h, the test was repeated. The results of the two tests and the change rate were recorded.

[0053] Ten PTC element experimental samples with a Curie temperature Tc = 220℃ were selected, and numbered as samples 11-20. The maximum current of each sample was measured using the high-precision test system of the present application, with the test temperature TRmin selected as 20%, i.e. 44℃. After being left at 25℃ for 48h, the test was repeated. The results of the two tests and the change rate were recorded.

[0054] Ten PTC element experimental samples with a Curie temperature Tc = 180℃ were selected, and numbered as samples 21-30. The maximum current of each sample was measured using the high-precision test system of the present application, with the test temperature TRmin selected as 60%, i.e. 108℃. After being left at 25℃ for 48h, the test was repeated. The results of the two tests and the change rate were recorded.

[0055] Twenty PTC element experimental samples with a Curie temperature Tc = 220℃ were selected, and numbered as samples 31-50. The high-precision test system of the present application was still used, but without temperature control, and the maximum current Imax was measured directly under pressure using the peak table to simulate the test environment of the traditional method. After being left at 25℃ for 48h, the test was repeated. The results of the two tests and the change rate were recorded.

[0056] Ten PTC element experimental samples with a Curie temperature Tc = 180℃ were selected, and numbered as samples 51-60. The high-precision test system of the present application was still used, but without temperature control, and the maximum current Imax was measured directly under pressure using the peak table to simulate the test environment of the traditional method. After being left at 25℃ for 48h, the test was repeated. The results of the two tests and the change rate were recorded.

[0057] Ten PTC element experimental samples with a Curie temperature Tc = 220℃ were selected, and numbered as samples 61-70. The high-precision test system of the present application was used for the test, with TRmin selected as 60%, i.e. 132℃. It should be noted that the difference between this comparative example and Example 1 is that, instead of individually monitoring the temperature of each sample in samples 61-70 and applying voltage for measurement according to the temperature monitoring results, the maximum current of all samples was measured simultaneously after the average temperature of the samples reached TRmin to simulate the test environment of the traditional method. After being left at 25℃ for 48h, the test was repeated again in the same way. The results of the two tests and the change rate were recorded.

[0058] The measurement results described above are shown in Tables 1-3 below.

[0059] Table 1 Imax measurement results of samples 1-10, 31-40, 61-70 (unit: A)

[0060]

[0061] From the table, it is not difficult to see that:

[0062] ① The maximum current value Imax of samples 31-40 is the widest (0.249-0.328 A), the maximum current value Imax of samples 61-70 is relatively narrow (0.276-0.302 A), and the maximum current value Imax of samples 1-10 is the most concentrated (0.285-0.299 A);

[0063] ② The change rate between two measurements of samples 31-40 is larger (5.65%-11.9%), the change rate between two measurements of samples 61-70 is slightly smaller (1.75%-3.23%), and the change rate between two measurements of samples 1-10 is the smallest (0.33%-1.39%).

[0064] Table 2 Imax measurement results of samples 11-20, 41-50 (unit: A)

[0065]

[0066] From the table, it is not difficult to see that:

[0067] ① The maximum current value Imax of samples 41-50 is wider (0.244-0.340 A), and the maximum current value Imax of samples 11-20 is narrower (0.267-0.308 A);

[0068] ② The change rate between two measurements of samples 41-50 is larger (6.42%-11.97%), and the change rate between two measurements of samples 11-20 is smaller (0.68%-2.78%).

[0069] Table 3 Imax measurement results of samples 21-30, 51-60 (unit: A)

[0070]

[0071] From the table, it is not difficult to see that:

[0072] ① The maximum current value Imax of samples 51-60 is wider (0.339-0.426 A), and the maximum current value Imax of samples 21-30 is narrower (0.371-0.393 A);

[0073] The change rate between two measurements of samples 51-60 is relatively large (5.91%~12.30%), and the change rate between two measurements of samples 21-30 is relatively small (0.27%~1.58%).

[0074] From the above tests, it can be seen that no matter what the Curie temperature Tc of the PTC element is, when the voltage is cut off after the temperature of the PTC element is heated to exceed its Curie temperature in advance, and the maximum current value is measured again when the temperature drops to 20%~60% of the Curie temperature, the accuracy of measuring the maximum current value of the PTC element can be improved, and the stability and reliability of the electronic element made of the PTC element are improved. In addition, it can be seen from the test results of Example 1 and Comparative Example 3, which both use this method to test the maximum current value, that due to the high sensitivity of the performance of the PTC element to the test temperature, accurate temperature monitoring of each PTC element can further significantly improve the accuracy and repeatability of the test results.

[0075] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A PTC element automatic test system comprising an element conveying line and a maximum current test device provided on the element conveying line, characterized by, The maximum current testing device comprises, in sequence along the conveying direction of the element conveying line, a heating unit, a first temperature measuring unit, a second temperature measuring unit and a current measuring unit; the first temperature measuring unit, the second temperature measuring unit and the current measuring unit are all provided with temperature sensors corresponding to each PTC element; The PTC element automatic testing system further comprises a central control device signal connected with the heating unit, the first temperature measuring unit, the second temperature measuring unit and the current measuring unit respectively.

2. The PTC element automatic test system according to claim 1, wherein The current measuring unit comprises measuring probes corresponding to the number of PTC elements, and the temperature sensors are arranged on the measuring probes; each measuring probe further comprises a pressure element and a current detecting element.

3. The PTC element automatic test system according to claim 1, wherein Along the element conveying line, a grading unit signal connected with the central control device is further arranged after the current measuring unit.

4. The PTC element automatic test system according to claim 3, wherein A first screening unit signal connected with the central control device is further arranged between the first temperature measuring unit and the second temperature measuring unit, and a second screening unit signal connected with the central control device is further arranged between the current measuring unit and the grading unit.

5. The PTC element automatic test system according to claim 3, wherein Along the element conveying line, a packaging unit is further arranged after the grading unit.

6. The PTC element automatic test system according to claim 1, wherein Before the maximum current testing device, along the conveying direction of the element conveying line, a voltage-withstanding test device, a temperature stabilizing device and a zero-power resistance testing device are further arranged in sequence; after the maximum current testing device, along the element conveying line, a surface detection device is further arranged; the voltage-withstanding test device, the temperature stabilizing device, the zero-power resistance testing device and the surface detection device are all signal connected with the central control device.

7. The PTC element automatic test system according to claim 6, wherein Along the element conveying line, a feeding device signal connected with the central control device is further arranged before the voltage-withstanding test device.

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