TWI785260B - overcurrent protection device - Google Patents

Abstract

An overcurrent protection device includes a positive temperature coefficient (PTC) polymer element, two electrodes and a no power trip indicator. The positive temperature coefficient polymer element has two opposing surfaces. The two electrodes are respectively connected to the two surfaces. The no power trip indicator is formed on at least one of the electrodes to sense the temperature of the overcurrent protection device. When the overcurrent protection device of the present invention is in a tripped state, it can be identified immediately, and its overall production cost and manufacturing process can be greatly reduced.

Description

overcurrent protection device

The present invention relates to an over-current protection device, in particular to an over-current protection device including a no-power trip indicator for sensing its temperature.

A positive temperature coefficient (PTC) device has a PTC effect, making it useful as a circuit protection device (eg, a fuse).

Referring to Fig. 1, the existing circuit protection device comprises a PTC polymer material 8 and two electrodes 9 respectively connected to two opposite surfaces 81 of the PTC polymer material 8, and the PTC polymer material 8 comprises a crystal region and a A polymer substrate in the amorphous region, and a granular conductive filler dispersed in the amorphous region of the polymer matrix and forming a continuous conductive path for electrically connecting the electrodes 9 . The PTC effect refers to a phenomenon that when the temperature of the crystalline region is raised to its melting point, crystals in the crystalline region start to melt, thereby creating a new amorphous region. When the new amorphous region increases to a degree that merges into the original amorphous region, the conductive path of the granular conductive filler will be transformed into discontinuity and the resistance of the PTC polymer material 8 will increase sharply, causing the There is no electrical conduction between the electrodes 9 .

The Republic of China Patent No. TW 424929 describes an electronic fuse, which includes a housing, a filler filled in the housing, conductive particles contained in the filler, two conductive sheets extending into the housing, and a jumper Light emitting diodes (LEDs) of the conductive sheets. The packing can expand to increase the reaction temperature. The conductive sheets are connected to the filler and spaced apart from each other at a proper distance. The light emitting diode is connected in parallel with the filler. When the circuit is short-circuited, the filler will expand due to temperature rise, and the conductive particles will be separated from each other. Therefore, current passes through the LED instead of the filler, causing the LED to emit light.

However, the configuration of the above-mentioned electronic fuse increases the complexity and the manufacturing cost, therefore, an over-current protection device that can be easily produced and meets the needs of the industry remains to be developed.

Therefore, the object of the present invention is to provide an overcurrent protection device that can overcome at least one of the above-mentioned disadvantages of the prior art.

Therefore, the overcurrent protection device of the present invention includes a positive temperature coefficient (PTC) polymer element, two electrodes and a no power trip indicator. The positive temperature coefficient polymer element has two opposing surfaces. The two electrodes are respectively connected to the two surfaces. The no power trip indicator is formed on at least one of the electrodes to sense the temperature of the overcurrent protection device.

The effect of the present invention is that: when the overcurrent protection device of the present invention is in a tripped state, it can be recognized immediately, and the overall production cost and process of the overcurrent protection device of the present invention can be greatly reduced.

The content of the present invention will be described in detail below:

In some embodiments of the present invention, the dead power trip indicator is in direct contact with the at least one electrode.

Preferably, the dead power trip indicator comprises a thermochromic material. More preferably, the overcurrent protection device has a trip surface temperature which is equal to or higher than the discoloration temperature of the no-power trip indicator. Still more preferably, the trip surface temperature of the overcurrent protection device is higher than 70°C.

Preferably, the discoloration temperature of the no-power trip indicator is higher than 60°C. More preferably, the discoloration temperature of the no-power trip indicator is higher than 60°C and not higher than 200°C.

In some embodiments of the present invention, the overcurrent protection device further includes a covering layer disposed between the no-power trip indicator and the at least one electrode. Preferably, the dead power trip indicator is in indirect contact with the at least one electrode through the covering layer. Optionally, the covering layer surrounds the PTC polymer element and the electrodes, and is made of a thermally conductive insulating material.

Preferably, the positive temperature coefficient polymer element includes a polymer substrate and a granular conductive filler dispersed in the polymer substrate. More preferably, the granular conductive filler is selected from carbon black powder, metal powder, conductive ceramic powder or a combination thereof. Still more preferably, the granular conductive filler is carbon black powder.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same numerals.

Referring to FIG. 2 , a first embodiment of the overcurrent protection device of the present invention includes a positive temperature coefficient (PTC) polymer element 2 , two electrodes 3 and a no-power trip indicator 4 . The PTC polymer element 2 has two opposing surfaces 21 . The two electrodes 3 are respectively connected to the two surfaces 21 . The no power trip indicator 4 is formed on at least one of the electrodes 3 to sense the temperature of the overcurrent protection device. In the first embodiment, the no-power trip indicator 4 is in direct contact with the at least one electrode 3 .

The positive temperature coefficient polymer element 2 includes a polymer substrate and a granular conductive filler dispersed in the polymer substrate. In some embodiments of the invention, the polymer substrate is made of polyvinylidene fluoride (PVDF). In other embodiments, the polymeric substrate is made of polymers comprising crystalline polyolefins selected from non-grafted polyolefins [e.g. non-grafted high-density polyethylene (HDPE), non-grafted low-density polyethylene (LDPE), non-grafted ultra-low-density polyethylene (ULDPE), non-grafted medium-density polyethylene (MDPE), non-grafted polypropylene (PP) ], grafted polyolefins (e.g. polyethylene grafted with carboxylic anhydride) or combinations thereof, or copolymers of olefin monomers and anhydrides [e.g. ethylene/maleic anhydride copolymer (PE/MA), ethylene /butyl acrylate/maleic anhydride terpolymer (PE/BA/MA)].

The granular conductive filler is selected from carbon black powder, metal powder, conductive ceramic powder or a combination thereof. In some embodiments of the present invention, the particulate conductive filler is carbon black powder.

The no power trip indicator 4 includes a thermochromic (thermochromic) material, which can be but not limited to Chroma Life Technology Ltd. or New Prismatic Enterprise Co. ., Ltd.) is a commercially available product.

As used herein, the term "thermochromic material" refers to a substance that responds to changes in temperature by changing its ability to absorb, transmit or reflect light. Therefore, in this document, the term "thermochromic" and the "color" change based on thermochromism refer to any visual change of the non-power trip indicator 4 . The visual changes include strictly defined visible color changes, changes in fluorescence, changes in luminescence, changes in phosphorescence, and changes that may indicate the occurrence of a color or visual phenomenon, the disappearance of a color or visual phenomenon, or change to another color or other visual phenomenon. Phenomena and similar phenomena change. The change is visualized, in other words, it is any apparent change in the unpowered trip indicator 4 when viewed with the naked eye, whether through filtering or not, and whether through optical stimuli (e.g., ambient lighting or specific wavelength of light exposure).

According to the present invention, the thermochromic material can be dispersed throughout the dead power trip indicator 4 , or concentrated in one area or multiple discrete areas of the dead power trip indicator 4 . When the thermochromic material concentrates on the area of the no-power trip indicator 4, the area can be in a specific shape, or arranged in a predetermined shape, figure or pattern.

In some embodiments of the present invention, the no-power trip indicator 4 has a color change temperature (T _cc ). The discoloration temperature may be higher than 60°C. The discoloration temperature may not be higher than 200°C.

According to the present invention, the overcurrent protection device has a trip surface temperature, which is equal to or higher than the discoloration temperature of the no-power trip indicator 4 . That is to say, the thermochromic material of the non-power trip indicator 4 can change color to reflect a trip state (refer to FIG. 3 ). Specifically, in a normal state, the surface temperature of the overcurrent protection device is usually between 25° C. and 50° C., which is lower than the discoloration temperature of the no-power trip indicator 4 . However, when the overcurrent protection device trips, the surface temperature of the overcurrent protection device increases sharply to its trip surface temperature, which exceeds the discoloration temperature of the no-power trip indicator 4 . Therefore, the temperature change of the thermochromic material of the non-power trip indicator 4 can be observed to indicate a tripped state.

In some specific embodiments of the present invention, the trip surface temperature of the overcurrent protection device is higher than 70°C.

Referring to Fig. 4, a second embodiment of the overcurrent protection device of the present invention is similar to the first embodiment, the difference is that the second embodiment also includes a power-off trip indicator 4 and the at least A covering layer 5 between the electrodes 3 . In the second embodiment, the no-power trip indicator 4 is in indirect contact with the at least one electrode 3 through the covering layer 5 . In addition, the covering layer 5 surrounds the PTC polymer element 2 and the electrodes 3 .

The covering layer 5 can be made of a thermally conductive insulating material. Examples of thermally conductive insulating materials may include, but are not limited to, solder mask, tape, epoxy resin or silicone resin. The covering layer 5 can protect the PTC polymer element 2 and the electrodes 3 from being damaged by external forces or environmental factors.

The present invention will be further described with reference to the following examples, but it should be understood that these examples are for illustrative purposes only, and should not be construed as limitations on the implementation of the present invention.

Example

Preparation of polymer blend compositions

Preparation of carbon black powder (purchased from Columbian Chemicals, product model: Raven 430UB, DBP/D is 0.95, bulk density is 0.53 g/cm ) of three kinds of polymer blending compositions (being formula 1, formula 2, formula ³ ) and polymeric substrates as described below. In formula 1, the polymer substrate is ethylene/butyl acrylate/maleic anhydride terpolymer (PE/BA/MA) (available from Arkema, product model: Lotader® 3410, BA content 18.0 wt%, MA content 3.1 wt%, melting point 91 °C). In formula 2, the polymer substrate includes HDPE (purchased from Taiwan Plastic Industry Co., Ltd., product model: HDPE9002, melting point 130 ° C) as a non-grafted polyolefin, and HDPE grafted with maleic anhydride (MA -g-HDPE, purchased from DuPont, product model: MB100D, melting point 134°C) as polyolefin grafted with unsaturated carboxylic acid anhydride. In formulation 3, the polymer substrate is polyvinylidene fluoride (PVDF) (available from Arkema, product model: Kynar® 761, melting point 170° C.). The proportions of the polymer substrate and carbon black powder composed of the above three polymer blends are shown in Table 1 respectively.

The above three polymer substrates were mixed with carbon black powder in a mixer (brand: Brabender), and the temperature was 200 °C, and the stirring speed was 30 rpm for 10 minutes to obtain three polymers. Composition of blends (i.e. formula 1, formula 2, formula 3).

Preparation of small pieces (chip)

The blended compositions of the above three polymers were each placed in a mold, and hot-pressed for 4 min at a hot-pressing temperature of 200 °C and a hot-pressing pressure of 80 kg/cm ² to form three thin sheets with a thickness of 0.33 mm. The three kinds of thin slices were taken out from the mold, and each thin slice was placed in two nickel-plated copper foils (as electrodes), and hot-pressed at 200 °C and 80 kg/ ^cm2 for 4 min to form thicknesses of 0.4 mm laminates. After these laminates were cut into multiple small pieces of 8 mm × 8 mm, each small piece was irradiated with Co-60 γ-rays at a total radiation dose of 150 kGy. The initial resistance of each small piece was measured with a micro-ohmmeter at 25°C. The average initial resistance (n=100) and the calculated average volume resistivity of the three small pieces are shown in Table 1, respectively. 【Table 1】 formula Polymer Blend Composition Electricity of small pieces polymer substrate Carbon black powder (wt%) Initial resistance (Ω) Volume resistivity (Ω-cm) PE/BA/MA (wt%) HDPE (wt%) MA-g-HDPE (wt%) PVDF (wt%) 1 42.0 – – – 58.0 0.016 0.256 2 – 21.0 21.0 – 58.0 0.020 0.320 3 – – – 60.0 40.0 0.050 0.800 "–" means not added.

Preparation of overcurrent protection device

＜Example 1 (E1) >

Two metal conductor pins were respectively connected to two nickel-plated copper foils of each small piece prepared by the polymer blending composition of the above formula 1, and then the small piece was covered with a covering layer made of epoxy resin. A thermochromic material [purchased from Jiurong Shuofeng Life Technology Co., Ltd., product model: H810Kb70P40, the discoloration temperature (T _cc ) is 70°C, white when the temperature is lower than T _cc , and blue when the temperature is higher than T _cc color] screen-printed on the covering layer, and dried for about 2 minutes to obtain the E1 overcurrent protection device with a tripping indicator formed.

<Example 2 and 3 (E2 and E3) >

The process conditions of the overcurrent protection devices of E2 and E3 are similar to those of Example 1, except that the blending composition of the polymer and the thermochromic material are changed as shown in Table 2.

<Example 4 to 6 (E4-E6) >

The process conditions of the overcurrent protection devices of E4-E6 are similar to those of Examples 1 to 3, except that the thermochromic materials are changed as shown in Table 2.

＜Comparative example 1 to 3 (CE1-CE3) >

The process conditions of the overcurrent protection devices of CE1-CE3 are similar to those of Examples 1 to 3, the difference is that the trip indicator of CE1-CE3 is made of a non-thermochromic (non-thermochromic, that is, does not change with temperature Changing color) black marking ink formed (as shown in Table 2). 【Table 2】 Polymer Blend Composition Materials for escape counters formula label model T _cc (°C) Color below T _cc Color above T _cc E1 1 Jiurong Shuofeng Life Technology Co., Ltd. H810Kb70P40 70 White blue E2 2 H810Kb110P40 110 E3 3 H810Kb150P40 150 E4 1 Chong Yu Technology Co., Ltd. TM-ISI 70-3529 70 White green E5 2 TM-ISI 110-3529 110 E6 3 TM-ISI 150-3529 150 CE1 1 Markem- imaje 5751E-4 N/A black black CE2 2 CE3 3 "N/A" means not available.

Performance Testing

[ Room temperature color observation (Color observation at room temperature)]

Observe the initial colors of the trip indicators of the overcurrent protection devices of E1-E6 and CE1-CE3 at 25°C (non-trip state), and the results are shown in Table 3 respectively.

[ escape test (Trip test)]

For the overcurrent protection devices of E1-E6 and CE1-CE3, a constant voltage of 16 Vdc and a constant current of 10 A were energized for 60 s to conduct a trip test, and a thermocouple was used to measure the tripping surface temperature of the overcurrent protection device at the moment of tripping, and Observe the color of the trip indicator when the overcurrent protection device is in the trip state, and the results are shown in Table 3. 【table 3】 The initial color of escape counters escape test Trip surface temperature (°C) The color of the escape counter when in the escape state E1 White 79.4 blue E2 White 114.8 blue E3 White 154.8 blue E4 White 80.2 green E5 White 115.3 green E6 White 154.6 green CE1 black 80.1 black CE2 black 114.9 black CE3 black 155.3 black

The results in Table 3 show that when the overcurrent protection devices of E1-E6 are in the tripped state (the trip surface temperature is higher than the T _cc of the thermochromic material), the color of the trip indicator is different from its initial color, while CE1 - When the overcurrent protection device of CE3 is in the trip state, the trip indicator does not change its initial color, which means that the user can immediately identify whether the overcurrent protection device of E1-E6 is with the naked eye (that is, without any detection equipment) in a state of escape.

In summary, by including the temperature-reactive tripping indicator, when the overcurrent protection device of the present invention is in the tripped state, it can be recognized immediately through the color change of the tripping indicator, and the present invention has passed The overall production cost and manufacturing process of the current protection device can be greatly reduced, so the purpose of the present invention can indeed be achieved.

But what is described above is only an embodiment of the present invention, and should not limit the scope of the present invention. All simple equivalent changes and modifications made according to the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by the patent of the present invention.

2: Positive temperature coefficient polymer element 21: surface 3: electrode 4: No power trip indicator 5: Overlay 8: Positive temperature coefficient material 81: surface 9: Electrode

Other features and effects of the present invention will be clearly presented in the implementation manner with reference to the drawings, wherein: [Figure 1] is a schematic diagram of an existing overcurrent protection device; [Fig. 2] is a schematic diagram of the first embodiment of the overcurrent protection device of the present invention in a normal (non-tripping) state; [Fig. 3] is a schematic diagram of the first embodiment in a tripping state; and [ Fig. 4 ] is a schematic diagram of a second specific embodiment of the overcurrent protection device of the present invention.

2: Positive temperature coefficient polymer element

21: surface

3: electrode

4: No power trip indicator

Claims (10)

An overcurrent protection device comprising: a positive temperature coefficient polymer element having two opposite surfaces; two electrodes respectively connected to the two surfaces; a no power trip indicator formed on at least one of the electrodes , to sense the temperature of the overcurrent protection device; and a covering layer disposed between the passive trip indicator and the at least one electrode, the covering layer surrounding the positive temperature coefficient polymer element and the electrodes Outside, and is made of a thermally conductive insulating material. The overcurrent protection device as claimed in claim 1, wherein the no power trip indicator comprises a thermochromic material. The overcurrent protection device as claimed in claim 2, wherein the overcurrent protection device has a trip surface temperature which is equal to or higher than the discoloration temperature of the no-power trip indicator. The overcurrent protection device as claimed in claim 3, wherein the trip surface temperature of the overcurrent protection device is higher than 70°C. The overcurrent protection device as claimed in claim 1, wherein the discoloration temperature of the no-power trip indicator is higher than 60°C. The overcurrent protection device according to claim 5, wherein the discoloration temperature of the no-power trip indicator is higher than 60°C and not higher than 200°C. The overcurrent protection device as claimed in claim 1, wherein the no-power trip indicator is in indirect contact with the at least one electrode through the covering layer. The overcurrent protection device as claimed in claim 1, wherein the positive temperature coefficient polymer element comprises a polymer substrate and a granular conductive filler dispersed in the polymer substrate. The overcurrent protection device according to claim 8, wherein the granular conductive filler is selected from carbon black powder, metal powder, conductive ceramic powder or a combination thereof. The overcurrent protection device as claimed in claim 9, wherein the granular conductive filler is carbon black powder.

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