A hot wire ignition device and test method for internal ignition testing of electrical appliances

Abstract

The application discloses a hot-wire ignition device and a test method for internal ignition test of an electrical appliance. The hot-wire ignition device comprises a heating assembly, a base, a top pressure providing seat and a clamping force providing seat. The heating assembly comprises a ceramic rod, a heating wire and a temperature sensor. The top pressure providing seat comprises a sleeve, a sliding rod slidingly arranged in the sleeve, a distance adjusting nut and a top pressure providing spring. The clamping force providing seat comprises a fixed crossbar, a clamping rod and a clamping force providing spring. The clamping rod is connected to the fixed crossbar, and the clamping force providing spring provides pressure to the clamping rod. The sleeve of the top pressure providing seat and the fixed crossbar of the clamping force providing seat are fixedly connected to the base. The test method adopts the hot-wire ignition device to perform the test. The application can test fixed non-metal parts and unfixed non-metal parts in the electrical appliance, simulate heating of conductors in the electrical appliance, and evaluate whether the electrical appliance can be ignited and whether the flame can spread outside the product.

Description

Technical Field

[0001] This invention belongs to the technical field of fire hazard assessment of electrical products, specifically relating to a hot wire ignition device and test method for internal ignition testing of electrical appliances. Background Technology

[0002] Electrical products generate heat in their conductors due to the electric current. When the temperature is high enough, it can ignite surrounding organic non-metallic materials such as plastics and rubber, posing a fire hazard. Therefore, safety testing of electrical products must include fire risk assessment.

[0003] The commonly used method for assessing the fire hazard of electrical products is the glow wire test method based on the GB / T 5169.10 (IEC 60695-2-10, IDT) standard. This method uses a 4mm diameter nickel-chromium alloy wire of a specific shape to simulate a heating conductor. The temperature of the wire is adjusted by regulating the current passing through it. The wire is then brought into contact with the non-metallic material or component to be assessed, thereby evaluating the ignition risk of that non-metallic material or component.

[0004] Typical glow wire testing apparatus used in the above methods includes, for example: Figure 11 and Figure 12 As shown, a sample holder 22 is fixedly mounted at one end of a base plate 21, and a vertical rod 27 is fixedly mounted near the other end of the base plate 21. A fixing block 26 is mounted on the upper end of the vertical rod 27, and a horizontally sliding crossbar 24 is mounted in the fixing block 26. The crossbar 24 is in contact with a roller 30 on the fixing block 26 to achieve a sliding connection. A pulley 29 is mounted at one end of the crossbar 24, and a tension rope 25 is wound around the pulley 29. One end of the tension rope 25 is connected to the fixing block 26, and the other end of the tension rope 25 is connected to a weight 28. The weight 28 provides a pushing force to the crossbar 24 towards the sample holder 22. A glowing wire 23 is mounted at the other end of the crossbar 24, facing the sample holder. During the test, the non-metallic component of the electrical product to be tested is fixed on the sample holder 22. Then, the glowing wire 23 is energized to heat it up, and the glowing wire 23 comes into contact with the non-metallic component to be tested, thus realizing the test.

[0005] However, the aforementioned glow wire test method and apparatus are only applicable to non-metallic materials or components outside the main body of the electrical product, and not to non-metallic materials or components installed inside the electrical product. This is because the glow wire test apparatus itself, due to size limitations, cannot be applied to the inside of the product; or it requires damaging part of the product structure to apply the test; or it requires disassembling the non-metallic materials or components inside the electrical product for testing. While this can assess the fire risk of the test component itself, it cannot fully simulate the internal combustion situation of the electrical product under normal or abnormal operating conditions. It is difficult to accurately assess the impact of the test component's results on the overall fire risk of the electrical product, because the location of the test component within the electrical product and the product structure also have a significant impact on the overall fire risk of the electrical product. Summary of the Invention

[0006] The first objective of this invention is to provide a hot wire ignition device for internal ignition testing of electrical appliances.

[0007] A second objective of the present invention is to provide a test method for conducting tests using the above-described hot filament ignition device.

[0008] The first objective of this invention is achieved through the following technical solution:

[0009] A hot wire ignition device for internal ignition testing of electrical appliances, characterized in that it includes a heating element, a base, a top pressure providing seat for testing fixed non-metallic parts inside the appliance, and a clamping force providing seat for testing non-fixed non-metallic parts inside the appliance. The heating element includes a ceramic rod, a heating wire wound around the ceramic rod near its front end, and a temperature sensor installed inside the ceramic rod. The top pressure providing seat includes a sleeve, a slide rod, a distance adjusting nut, and a top pressure providing spring. The slide rod slides through the sleeve, and the top pressure providing spring applies a forward thrust to the slide rod. On the rod, the front end of the sliding rod can be connected to the rear end of the ceramic rod, and the rear end of the sliding rod extends to the rear of the sleeve and is connected to the distance adjusting nut; the clamping force providing seat includes a fixed crossbar, a clamping rod and a clamping force providing spring, the front end of the fixed crossbar can be connected to the rear end of the ceramic rod, one end of the clamping rod is movably connected to the top of the fixed crossbar, and the other end of the clamping rod extends to the front of the fixed crossbar, and the clamping force providing spring provides pressure to the clamping rod toward the fixed crossbar; the base can be fixedly installed inside the electrical product, and the sleeve of the top pressure providing seat and the fixed crossbar of the clamping force providing seat can both be fixedly connected to the base.

[0010] A further technical solution of the present invention is as follows: a front thread section is provided near the front end of the ceramic rod, and the heating wire is wound along the spiral groove at the front thread section.

[0011] A further technical solution of the present invention is as follows: the ceramic rod has an axial central hole, the side of the ceramic rod has a side hole communicating with the central hole, the temperature sensor is located at the front end of the central hole, and the wire connected to the temperature sensor passes through the side hole.

[0012] A further technical solution of the present invention is that the front end of the ceramic rod is hemispherical.

[0013] A further technical solution of the present invention is as follows: the rear end of the ceramic rod is provided with a rear threaded section, and the front end of the slide bar and the front end of the fixed crossbar are both provided with threaded connection holes that can be connected to the rear threaded section.

[0014] A further technical solution of the present invention is as follows: a radially extending screw is connected to the top of the fixed crossbar, a collar is provided at one end of the clamping rod, the collar is sleeved on the screw, a clamping force providing spring is sleeved on the screw, and a clamping force adjusting nut is threadedly connected to the screw, with the clamping force providing spring located between the clamping force adjusting nut and the collar.

[0015] A further technical solution of the present invention is as follows: the hot wire ignition device further includes a fixed connecting column, and threaded connecting sleeves are provided on the top of the base, the side of the sleeve and the side of the fixed crossbar. The two ends of the fixed connecting column are respectively provided with external threaded connecting sections that can be connected to the threaded connecting sleeves.

[0016] A further technical solution of the present invention is as follows: the hot wire ignition device also includes a controller, and the heating wire and temperature sensor are respectively connected to the controller by wires.

[0017] The second objective of this invention is achieved through the following technical solution:

[0018] A test method using the above-mentioned hot wire ignition device is characterized in that: during the test, the non-metallic component to be tested inside the electrical appliance remains connected inside the electrical appliance, and the test method includes a test method for non-metallic components fixed inside the electrical appliance and a test method for non-fixed non-metallic components inside the electrical appliance.

[0019] The test method for the non-metallic parts fixed inside the electrical appliance is as follows: During the test, the base is fixed inside the electrical appliance, the top pressure supply seat is installed on the base, the heating element is connected to the slide rod, the front end of the ceramic rod abuts against the non-metallic parts fixed inside the electrical appliance, the top pressure supply spring is compressed, there is a set distance between the distance adjusting nut and the rear end face of the sleeve, a layer of gauze is covered on the outside of the electrical appliance, and then the test is carried out by controlling the current of the heating wire.

[0020] The test method for non-fixed non-metallic parts inside the electrical appliance is as follows: During the test, the base is fixed inside the electrical appliance, the clamping force supply seat is installed on the base, the heating element is connected to the fixed crossbar, the non-fixed non-metallic parts inside the electrical appliance are clamped between the ceramic rod and the clamping rod, the clamping force supply spring is compressed, a layer of gauze is covered on the outside of the electrical appliance, and then the test is carried out by controlling the current of the heating wire.

[0021] A further technical solution of the present invention is as follows: the method of conducting the experiment by controlling the current of the heating wire includes the following methods:

[0022] The first method is to gradually increase the current in the heating wire until the non-metallic parts ignite;

[0023] The second method is to gradually increase the current of the heating wire to the maximum current set in the test.

[0024] The third method is to gradually increase the current of the heating wire to the set current and then maintain it for the set time.

[0025] The fourth method is to control the current of the heating wire, which heats the ceramic rod to a set temperature and then maintains it for a set time.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The hot wire ignition device of the present invention can be directly and fixedly installed inside an electrical appliance, thereby enabling testing on fixed non-metallic parts and non-fixed non-metallic parts inside the appliance to simulate the heating of internal conductors, thereby assessing whether it can ignite the inside of the electrical product and whether the flame will spread outside the product.

[0028] The test method of the present invention keeps the non-metallic component to be tested inside the electrical appliance connected during the test, which can better simulate the fire situation under normal use of the electrical appliance. It can assess the fire risk of the entire product and the risk of flame spreading to the outside of the product based on the fire test of a specific non-metallic component inside the product. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the ceramic rod according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the heating component according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the slide bar according to an embodiment of the present invention;

[0032] Figure 4 A schematic diagram of the structure of the top pressure support according to an embodiment of the present invention;

[0033] Figure 5 This is a top view of the clamping rod according to an embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram of the structure of the fixed crossbar according to an embodiment of the present invention;

[0035] Figure 7 A schematic diagram of the structure of the clamping force providing seat according to an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the base structure according to an embodiment of the present invention;

[0037] Figure 9 This is a schematic diagram of the structure when testing a fixed non-metallic part according to an embodiment of the present invention;

[0038] Figure 10 This is a schematic diagram of the structure when testing a non-fixed non-metallic part according to an embodiment of the present invention;

[0039] Figure 11 A frontal view of an existing hot wire testing apparatus;

[0040] Figure 12 This is a top view of an existing hot wire testing apparatus.

[0041] Meaning of the labels in the attached diagram:

[0042] 1-Ceramic rod; 1.1-Front threaded section; 1.2-Helical groove; 1.3-Central hole; 1.4-Side hole; 1.5-Rear threaded section; 1.6-Front end of ceramic rod; 2-Heating wire; 3-Temperature sensor; 4-Wire connected to temperature sensor; 5-Slide rod; 5.1-Threaded connection hole of slide rod; 5.2-Annular stainless steel washer; 5.3-External thread at the rear end of slide rod; 6-Top pressure providing spring; 7-Sleeve; 8-Threaded connection sleeve; 9-Distance adjusting nut; 10-Clamping rod; 10.1-Collar; 11-Fixing crossbar ; 11.1-Threaded connection hole for fixing crossbar; 12-Clamping force adjusting nut; 13-Clamping force providing spring; 14-Fixed connecting column; 14.1-External threaded connection section; 15-Base; 15.1-Fixed hole; 16-Fixed non-metallic part; 17-Screw; 18-Screw rod; 19-Controller; 20-Non-fixed non-metallic part; 21-Base plate; 22-Sample holder; 23-Heating wire; 24-Crossbar; 25-Tightening rope; 26-Fixed block; 27-Upright pole; 28-Weight; 29-Pulley; 30-Roller. Detailed Implementation

[0043] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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 limiting this invention.

[0044] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0045] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0046] The present invention will be further described below with reference to embodiments.

[0047] Example:

[0048] like Figures 1 to 10 The diagram shows a hot wire ignition device for internal ignition testing of electrical appliances according to this embodiment. It includes a heating element, a base 15, a fixed connecting column 14, a top pressure providing seat, and a clamping force providing seat. The top pressure providing seat is used when testing fixed non-metallic parts 16 inside the electrical appliance, while the clamping force providing seat is used when testing non-fixed non-metallic parts 20 inside the electrical appliance. The fixed non-metallic parts 16 refer to components that are fixedly installed inside the electrical appliance and will not shift under force, such as components fixed internally by screws or clips. The non-fixed non-metallic parts 20 refer to components that are not fixedly installed and will shift under force, such as certain terminals that, although connected to internal wires, do not have a fixed position and will move under force.

[0049] like Figure 1 and Figure 2 As shown, the heating component includes a ceramic rod 1, a heating wire 2, and a temperature sensor 3.

[0050] In this embodiment, the ceramic rod 1 is made of aluminum nitride, which has good high temperature resistance, high thermal conductivity, and high insulation. The total length of the ceramic rod 1 is 25mm. Near the front end of the ceramic rod 1, there is a front thread section 1.1, which is 15mm long. The minor diameter of the thread in the front thread section 1.1 is 4mm, the major diameter is 5mm, and the pitch is 1mm. At the rear end of the ceramic rod 1, there is a rear thread section 1.5, which is 5mm long and has a single-start triangular external thread with a minor diameter of 4mm, a major diameter of 5mm, and a pitch of 1mm. The section between the front thread section 1.1 and the rear thread section 1.5 is an intermediate section, which is 5mm long and has an outer diameter of 5mm. The rear end face of the ceramic rod 1 is flat, and the front end 1.6 is a hemispherical shape with a radius of 2.5mm. A central hole 1.3 with an axial diameter of 1.1 mm is provided inside the ceramic rod 1. One end of the central hole 1.3 passes through the rear end of the ceramic rod 1, and the other end extends to the center of the hemisphere at the front end of the ceramic rod 1. A side hole 1.4 communicating with the central hole 1.3 is provided on the side of the middle section. The side hole 1.4 has a length of 3 mm and a width of 1.1 mm.

[0051] The heating wire 2 is wound in a double-wire winding method along the spiral groove 1.2 formed at the front thread section 1.1 of the ceramic rod 1. The heating wire 2 is a nickel / chromium (>77% nickel / 20±1% chromium) wire with a length of about 300 mm and a diameter of 0.5 mm to 0.8 mm. Both ends of the heating wire 2 extend from the rear end of the front thread section 1.1. During the test, both ends of the heating wire 2 are connected to the DC power supply through wires.

[0052] In this embodiment, the temperature sensor 3 is a 1mm diameter K-type or N-type armored thermocouple. The temperature sensor 3 is inserted into the front end of the central hole 1.3 through the side hole 1.4 of the ceramic rod 1. The wire 4 connected to the temperature sensor passes through the side hole 1.4. The temperature sensor 3 can detect the temperature of the ceramic rod 1. During the experiment, the temperature sensor 3 feeds back a temperature signal, and then the current of the heating wire 2 is controlled according to the temperature signal, thereby controlling the temperature of the ceramic rod 1.

[0053] like Figure 3 and Figure 4As shown, the top pressure providing seat includes a sleeve 7, a slide rod 5, a distance adjusting nut 9, and a top pressure providing spring 6. In this embodiment, the slide rod 5 is a stainless steel rod with a length of 50mm and a diameter of 6mm. The front end has a threaded connection hole with a depth of 5mm. The major diameter of the internal thread of the threaded connection hole 5.1 is 5mm, and the minor diameter is 4mm. The threaded connection hole 5.1 of the slide rod can be threaded together with the rear threaded section 1.5 of the ceramic rod 1. A ring-shaped stainless steel washer 5.2 with an outer diameter of 15mm, an inner diameter of 6mm, and a thickness of 1mm is welded to 5mm from the front end of the slide rod 5. The rear end of the slide rod 5 has a 20mm long external thread. In this embodiment, the sleeve 7 is a stainless steel tube with an outer diameter of 10mm, an inner diameter of 6.2mm, and a length of 30mm. Two threaded connecting sleeves 8 with an outer diameter of 10mm, an inner diameter of 6mm, and a length of 10mm are symmetrically welded to the middle of the sleeve 7. The threaded connecting sleeves 8 have internal threads.

[0054] The slide rod 5 slides through the sleeve 7. During assembly, before inserting the slide rod 5 into the sleeve 7, the top pressure providing spring 6 must be fitted onto the front end of the sleeve 7. After the slide rod 5 is inserted, the annular stainless steel washer 5.2 on the slide rod 5 will press against the top pressure providing spring 6. As the insertion depth increases, the spring will compress, thereby applying a forward thrust to the slide rod 5 through the top pressure providing spring 6. In this embodiment, the top pressure providing spring 6 is a compression constant force spring with an inner diameter of 10.1 mm and an original length of 20 mm (compression force of 1 N). During use, a suitable amount of lubricating oil can be applied to the inner wall of the sleeve 7 to allow the slide rod 5 to slide freely after being inserted into the sleeve 7.

[0055] The rear end of the slide rod 5 extends to the rear of the sleeve 7, and a distance adjusting nut 9 is connected at the external thread 5.3 at the rear end of the slide rod. In this embodiment, the distance adjusting nut 9 is about 3mm thick and has an outer diameter of 12mm.

[0056] like Figures 5 to 7 As shown, the clamping force providing seat includes a fixed crossbar 11, a clamping rod 10, a clamping force providing spring 13, and a clamping force adjusting nut 12.

[0057] In this embodiment, the fixed crossbar 11 is a stainless steel rod with a length of 30mm and a diameter of 10mm. The front end of the fixed crossbar 11 is provided with a threaded connection hole with a depth of 5mm. The major diameter of the thread in the threaded connection hole is 5mm and the minor diameter is 4mm. The threaded connection hole 11.1 of the fixed crossbar can be threadedly connected to the rear threaded section 1.5 of the ceramic rod 1. Two threaded connecting sleeves 8 with an outer diameter of 10mm, an inner diameter of 6mm, and a length of 10mm are symmetrically welded at the middle position of the fixed crossbar 11. The threaded connecting sleeves 8 have internal threads.

[0058] The clamping rod 10 is a steel rod with a length of 30mm and a diameter of 5mm. A collar 10.1 with an outer diameter of 15mm, an inner diameter of 11mm, and a thickness of 5mm is welded to one end of the clamping rod 10.

[0059] A radially extending screw 18 is connected to a threaded connecting sleeve 8 on the fixed crossbar 11. A collar 10.1 is fitted onto the screw 18, and a clamping force providing spring 13 is fitted onto the screw 18. A clamping force adjusting nut 12 is threaded onto the screw 18. The clamping force providing spring 13 is located between the clamping force adjusting nut 12 and the collar 10.1. The pressure of the clamping force providing spring 13 on the clamping rod 10 can be adjusted by adjusting the clamping force adjusting nut 12. In this embodiment, the clamping force providing spring 13 is a compression constant force spring (compression force of 1N) with an inner diameter of 10.1mm and an original length of 20mm. The clamping force adjusting nut 12 is approximately 3mm thick and has an outer diameter of 12mm.

[0060] When the clamping rod 10 is installed on the fixed crossbar 11, one end of the clamping rod 10 extends to the front of the fixed crossbar 11. During the test, the non-fixed non-metallic part 20 will be clamped between the clamping rod 10 and the ceramic rod 1.

[0061] The base can be fixedly installed inside electrical appliances. For example... Figure 8 As shown, the base 15 in this embodiment is a square steel sheet with a side length of 30mm and a thickness of 2mm. A threaded connecting sleeve 8 with an outer diameter of 10mm, an inner diameter of 6mm, and a length of 20mm is welded to the middle of the base 15. The threaded connecting sleeve 8 has internal threads. Fixing holes 15.1 are drilled at the four corners of the base 15, which facilitate fixing the base 15 to the inner wall of the appliance with screws.

[0062] The fixed connecting post 14 has external threaded connecting sections 14.1 at both ends that can connect with the threaded connecting sleeve 8. In this embodiment, the fixed connecting post 14 can be straight or curved as needed. During testing, one end of the fixed connecting post 14 is threaded to the threaded connecting sleeve 8 of the base 15, and the other end is connected to the threaded connecting sleeve 8 of the top pressure providing seat or the threaded connecting sleeve 8 of the clamping force providing seat, thereby fixing the top pressure providing seat or the clamping force providing seat onto the base 15. By using fixed connecting posts 14 of different lengths and shapes as needed, the top pressure providing seat and the clamping force providing seat can be fixed in a suitable position.

[0063] The hot wire ignition device in this embodiment can be further equipped with a controller 19. The controller 19 contains a DC current source and a thermocouple thermometer. The DC current source has a maximum output current of approximately 30A, is adjustable, has a maximum output voltage of 36V, and a maximum output power of approximately 1000W. The thermocouple thermometer has a maximum range of approximately 1500℃. The heating wire 2 and the temperature sensor 3 are respectively connected to the DC current source and the thermocouple thermometer wires of the controller 19. The controller 19 provides DC power to the heating wire 2 through the DC current source and also receives the temperature signal detected by the temperature sensor 3. During the test, the controller 19 controls the current of the heating wire 2 according to the received temperature signal, thereby controlling the temperature of the ceramic rod 1.

[0064] The test method for conducting ignition tests on the interior of an electrical appliance using the hot wire ignition device of this embodiment includes a test method for fixed non-metallic parts inside the electrical appliance and a test method for non-fixed non-metallic parts inside the electrical appliance. During the test, the non-metallic parts to be tested inside the electrical appliance remain connected inside the electrical appliance, that is, the non-metallic parts to be tested are tested directly inside the electrical appliance.

[0065] The test method for the non-metallic parts fixed inside the electrical appliance in this embodiment is as follows: During the test, the base 15 is fixed to the inner wall of the electrical appliance with screws 17. The top pressure providing seat is installed on the base 15 through a fixed connecting post 14 of appropriate length and bending angle (if necessary). The sleeve 7, slide rod 5, distance adjusting nut 9, and top pressure providing spring 6 of the top pressure providing seat are assembled in advance. The heating element is pre-assembled. The ceramic rod 1 of the heating element is connected to the slide rod 5, and the front end of the ceramic rod 1 abuts against the non-metallic part 16 fixed inside the electrical appliance. The top pressure providing spring 6 is compressed by 10mm. There is a distance of 7mm between the distance adjusting nut 9 and the rear end face of the sleeve 7. A layer of gauze is covered on the outer surface of the electrical appliance. The heating wire 2 is connected to the output terminal of the DC current source of the controller 19 through a flexible wire of appropriate wire diameter (usually 1.5mm² wire is appropriate) and length through the outer shell of the electrical appliance. At the same time, the temperature sensor 3 is connected to the thermocouple temperature sensor of the controller 19 through a thermocouple connecting wire of appropriate length through the outer shell of the electrical appliance. The controller 19 is located outside the electrical appliance. The assembled structure is as follows. Figure 9 As shown. The experiment was then conducted by controlling the current of the heating wire 2. During the experiment, the front end of the heated ceramic rod 1 continuously inserted into the fixed non-metallic part 16. Since the distance between the adjusting nut 9 and the rear end face of the sleeve 7 is 7mm, the maximum insertion depth into the fixed non-metallic part 16 is 7mm. Therefore, by adjusting the distance between the adjusting nut 9 and the rear end face of the sleeve 7, the insertion depth into the fixed non-metallic part 16 during the experiment can be adjusted.

[0066] The testing method for non-fixed non-metallic parts inside the electrical appliance in this embodiment is as follows: During the test, the base 15 is fixed inside the electrical appliance, and the clamping force providing seat is installed on the base 15 through a fixed connecting post 14 of appropriate length and bending angle (if necessary). The fixed crossbar 11, clamping rod 10, and clamping force providing spring 13 of the clamping force providing seat are pre-assembled. The heating element is pre-assembled, and the ceramic rod 1 of the heating element is connected to the fixed crossbar 11. The non-fixed non-metallic part 20 inside the electrical appliance is clamped between the ceramic rod 1 and the clamping rod 10. The clamping force providing spring 13 is compressed, and a layer of gauze is covered on the exterior of the electrical appliance. The heating wire 2 is connected to the output terminal of the DC current source of the controller 19 through a flexible wire of appropriate wire diameter (usually 1.5 mm² wire is appropriate) and length through the outer shell of the electrical appliance. At the same time, the temperature sensor 3 is connected to the thermocouple temperature sensor of the controller 19 through a thermocouple connecting wire of appropriate length through the outer shell of the electrical appliance. The controller 19 is located outside the electrical appliance. The assembled structure is as follows. Figure 10 As shown. Then, experiments were conducted by controlling the current in heating wire 2.

[0067] The above-mentioned methods of conducting experiments by controlling the current of the heating wire include the following:

[0068] The first method is to gradually increase the current of the heating wire 2 until the non-metallic parts ignite, and observe the fire situation of the product during the test.

[0069] The second method is to gradually increase the current of the heating wire 2 to the maximum current set in the test (this maximum current is usually determined based on the maximum current that the sample is subjected to due to the failure of the electrical product), observe the fire situation of the product during the test, and whether it can ignite the covering gauze.

[0070] The third method is to gradually increase the current of the heating wire 2 to the set current, then maintain it for the set time, and observe the ignition of the product during the test process, as well as whether it can ignite the covering gauze.

[0071] The fourth method is to control the current of the heating wire 2, heat the ceramic rod 1 to the set temperature through the heating wire 2, and then maintain the temperature for a set time, observe the ignition of the product during the test process, and whether it can ignite the covering gauze.

[0072] The above embodiments of the present invention are not intended to limit the scope of protection of the present invention. The implementation of the present invention is not limited thereto. All other modifications, substitutions or alterations made to the above structure of the present invention based on the above content of the present invention, in accordance with ordinary technical knowledge and common practice in the field, without departing from the basic technical idea of ​​the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A hot wire ignition device for internal ignition testing of electrical appliances, characterized in that: The device includes a heating element, a base, a pressure-providing seat for inspecting fixed non-metallic parts inside the appliance, and a clamping force-providing seat for inspecting non-fixed non-metallic parts inside the appliance. The heating element includes a ceramic rod, a heating wire wound around the ceramic rod near its front end, and a temperature sensor installed inside the ceramic rod. The pressure-providing seat includes a sleeve, a slide rod, a distance adjusting nut, and a pressure-providing spring. The slide rod slides through the sleeve, and the pressure-providing spring applies a forward thrust to the slide rod. The front end of the slide rod can be connected to the rear end of the ceramic rod. The rear end of the slide rod extends to the rear of the sleeve and connects to the distance adjusting nut; the clamping force providing seat includes a fixed crossbar, a clamping rod, and a clamping force providing spring. The front end of the fixed crossbar can be connected to the rear end of the ceramic rod. One end of the clamping rod is movably connected to the top of the fixed crossbar, and the other end of the clamping rod extends to the front of the fixed crossbar. The clamping force providing spring provides pressure to the clamping rod towards the fixed crossbar; the base can be fixedly installed inside the electrical product, and both the sleeve of the top pressure providing seat and the fixed crossbar of the clamping force providing seat can be fixedly connected to the base; The test method for the hot filament ignition device is as follows: During the test, the non-metallic component to be tested inside the electrical appliance remains connected inside the appliance. The test method includes a test method for fixed non-metallic components inside the electrical appliance and a test method for non-fixed non-metallic components inside the electrical appliance. The test method for the non-metallic parts fixed inside the electrical appliance is as follows: During the test, the base is fixed inside the electrical appliance, the top pressure providing seat is installed on the base, the heating element is connected to the slide rod, the front end of the ceramic rod abuts against the non-metallic parts fixed inside the electrical appliance, the top pressure providing spring is compressed, there is a set distance between the distance adjusting nut and the rear end face of the sleeve, a layer of gauze is covered on the outside of the electrical appliance, and then the test is carried out by controlling the current of the heating wire. The test method for the non-fixed non-metallic parts inside the electrical appliance is as follows: During the test, the base is fixed inside the electrical appliance, the clamping force providing seat is installed on the base, the heating component is connected to the fixed crossbar, the non-fixed non-metallic parts inside the electrical appliance are clamped between the ceramic rod and the clamping rod, the clamping force providing spring is compressed, a layer of gauze is covered on the outside of the electrical appliance, and then the test is carried out by controlling the current of the heating wire.

2. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The ceramic rod has a front thread section near its front end, and the heating wire is wound along the spiral groove at the front thread section.

3. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The ceramic rod has an axial central hole, and the side of the ceramic rod has a side hole that communicates with the central hole. The temperature sensor is located at the front end of the central hole, and the wire connected to the temperature sensor passes through the side hole.

4. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The front end of the ceramic rod is hemispherical.

5. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The ceramic rod has a rear threaded section at its rear end, and the front end of the slide bar and the front end of the fixed crossbar are both provided with threaded connection holes that can be connected to the rear threaded section.

6. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: A radially extending screw is connected to the top of the fixed crossbar. One end of the clamping rod is provided with a collar, which is sleeved on the screw. The clamping force providing spring is sleeved on the screw. A clamping force adjusting nut is threaded onto the screw. The clamping force providing spring is located between the clamping force adjusting nut and the collar.

7. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The hot wire ignition device also includes a fixed connecting column. Threaded connecting sleeves are provided on the top of the base, the side of the sleeve, and the side of the fixed crossbar. Both ends of the fixed connecting column are respectively provided with external threaded connecting sections that can be connected to the threaded connecting sleeves.

8. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The hot wire ignition device also includes a controller, and the hot wire and temperature sensor are respectively wired to the controller.

9. The hot wire ignition device for internal ignition testing of electrical appliances according to claim 1, characterized in that: The methods for conducting experiments by controlling the current of the heating wire include the following: The first method is to gradually increase the current in the heating wire until the non-metallic parts ignite; The second method is to gradually increase the current of the heating wire to the maximum current set in the test. The third method is to gradually increase the current of the heating wire to a set current and then maintain it for a set time; The fourth method is to control the current of the heating wire to heat the ceramic rod to a set temperature and then maintain it for a set time.

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