Miniature transformer suitable for low-power-consumption charger and rapid assembling method of miniature transformer

Abstract

The invention relates to a miniature transformer suitable for a low-power-consumption charger and a rapid assembling method of the miniature transformer. The miniature transformer comprises a fixed iron core and a movable iron core which are arranged on a base, and an air gap is reserved between the fixed iron core and the movable iron core; a limiting seat positioned at one end of the framework is detachably mounted on the base; the movable iron core is positioned between the limiting seat and the framework; a plurality of bimetallic strips are mounted on one side, close to the limiting seat, of the framework, and the bimetallic strips are configured to control the air gap to be increased during temperature rise; a plurality of shape memory alloy springs are arranged between the limiting seat and the movable iron core, and the shape memory alloy springs are configured to be converted into an austenite phase and softened when the temperature rise exceeds the phase change temperature of the shape memory alloy springs; and when the temperature is reduced to the phase transition temperature, the shape memory alloy spring is converted into a martensite phase and recovers elasticity to drive the movable iron core to be far away from the limiting seat, so that the air gap is reduced. According to the invention, the air gap is automatically adjusted along with the temperature rise, and the temperature rise is controlled, so that the electromagnetic efficiency in different load states is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and in particular to a miniature transformer suitable for a low-power charger and a rapid assembly method thereof. Background Art

[0002] The micro transformer in the low-power charger is an electronic component used for voltage conversion and isolation. Different from the large transformer in the traditional linear power supply, the micro transformer has the characteristics of small size, light weight and high efficiency. It mainly includes a skeleton, a primary coil, a secondary coil and an insulating material used to isolate the primary coil and the secondary coil. The primary coil serves as the input end and the secondary coil serves as the output end. The number of turns of the primary coil is much larger than the number of turns of the secondary coil, which can convert high voltage into low voltage. When winding on the skeleton, the "sandwich" winding method is generally adopted, that is, a group of primary coils are wound on the inner circle and then several groups of secondary coils are wound. Finally, a group of primary coils connected in series with the primary coil of the inner circle are wound on the periphery, which can improve the efficiency of magneto-electric conversion.

[0003] In the related technology, a Chinese patent with application number CN202311349390.9 proposes a micro transformer suitable for a low-power charger and a quick assembly method thereof, wherein the micro transformer comprises a skeleton, which is arranged on a base; an iron core, which comprises two half-core parts, and the two half-core parts are symmetrically arranged on the outside of the skeleton; a coil winding, which comprises two primary coil windings and a plurality of secondary coil windings wound on the skeleton; a pin, which is arranged on the skeleton; a potting space is formed between the base and the iron core, and the potting space is filled with epoxy resin. The epoxy resin is cured and formed to form an integral structure of the skeleton, the iron core, the coil winding and the pin, which increases the connection strength of the transformer, thereby improving the overall strength of the transformer, and avoiding the problem of structural scattering and contact point breakage caused by the transformer falling or colliding in the charger; on the other hand, it plays a role of insulation protection. The transformer formed by epoxy resin potting is waterproof and moisture-proof, and improves the insulation performance of the transformer in the charger.

[0004] The above-mentioned related technologies have the following defects: for the half-iron core, it is generally made of an outer frame and an iron column part in one piece. During assembly, the two iron columns in the two half-iron cores penetrate into the hollow part of the skeleton. The two iron columns serve as the magnetic path of the transformer, and the air gap set between the two iron columns can be used to control the magnetic flux density and adjust the performance of the transformer to avoid the two iron columns from affecting the magneto-electric conversion efficiency and increasing heat dissipation after magnetic saturation. The current air gap is generally an optimal air gap determined under all working conditions. For transformers under different loads, this optimal air gap is not the optimal air gap; and when the transformer is under high load, the constant air gap will cause the iron core iron loss to increase and the heat generation to increase, which is not conducive to the control of the overall efficiency of the transformer. Summary of the invention

[0005] In order to improve the problem that the constant air gap of the existing transformer is not conducive to improving the overall efficiency of the transformer, the present application provides a miniature transformer suitable for a low-power charger and a quick assembly method thereof.

[0006] The first aspect of the present application provides a micro transformer suitable for a low-power charger, which adopts the following technical solution: A micro transformer suitable for a low-power charger, comprising a base, a frame, a primary coil and a secondary coil, wherein the base is provided with an input pin connected to the primary coil and an output pin connected to the secondary coil, an insulating layer is provided between the primary coil and the secondary coil, the base is provided with a fixed iron core fixed to the base and a movable iron core slidably provided on the base, the fixed iron core and the movable iron core both comprising an outer frame portion and an iron column portion, and an air gap is reserved between the two iron column portions; A limit seat located at one end of the frame is detachably mounted on the base, and the movable iron core is located between the limit seat and the frame; A plurality of bimetallic strips are installed on one side of the frame close to the limit seat, and the bimetallic strips are configured to deform and warp toward a side away from the frame when the temperature they sense increases, and push the movable iron core close to the limit seat, so as to increase the air gap; A plurality of shape memory alloy springs are arranged between the limit seat and the movable iron core. The shape memory alloy springs are configured such that when the temperature sensed by them exceeds their phase transition temperature, the shape memory alloy springs transform into an austenite phase and soften; and when the temperature sensed by them is lower than their phase transition temperature, the shape memory alloy springs transform into a martensite phase and restore elasticity to drive the movable iron core away from the limit seat so that the air gap is reduced.

[0007] Furthermore, the bimetallic strips are provided in plurality and are distributed in an equally spaced circular array along the central axis of the cylindrical portion of the skeleton, a plurality of insert seats are fixedly connected to the skeleton, the insert seats have an insert opening for inserting the head end of the bimetallic strip, the insert seats with two insert openings facing each other form a group, and the two ends of the bimetallic strip are respectively inserted into the two insert seats of the same group.

[0008] Furthermore, the limiting seat has a plurality of accommodating grooves for embedding and fixing one end of a plurality of the shape memory alloy springs.

[0009] Furthermore, a plurality of limiting protrusions corresponding to the movable iron core are fixedly connected to one side of the limiting seat close to the frame. When the movable iron core slides to abut against the limiting protrusions, the air gap between the two iron column parts of the movable iron core and the fixed iron core is 1 mm.

[0010] Furthermore, when the movable iron core slides to abut against the embedded seat, the air gap between the movable iron core and the two iron column parts of the fixed iron core is not less than 0.1 mm.

[0011] Furthermore, the base and the inner circumferential wall of the cylindrical portion of the skeleton are both provided with polytetrafluoroethylene patches, and the polytetrafluoroethylene patches are provided corresponding to the movement trajectory of the movable iron core.

[0012] Furthermore, a buckle cover is fixed on the base and wrapped around the outer frame of the fixed iron core and the movable iron core. The buckle cover is opened at both axial ends of the cylindrical portion of the skeleton. The inner wall of the buckle cover is tightly pressed against the fixed iron core and a sliding gap is reserved between the buckle cover and the movable iron core.

[0013] Furthermore, two opposite side walls of the base are fixedly connected with a plurality of tenons at the joints corresponding to the two outer frame parts, and one end of the buckle cover close to the base is fixedly connected with a tenon seat which is clamped with the tenons.

[0014] The second aspect of the present application provides a method for quickly assembling a micro transformer suitable for a low-power charger, which adopts the following technical solution: A method for quickly assembling a micro transformer suitable for a low-power charger, based on the above-mentioned micro transformer suitable for a low-power charger, comprises the following steps: S1. Coil winding, winding the primary coil and the secondary coil on the cylindrical portion of the frame by a sandwich method, and mounting the frame on the base; S2 core installation, the fixed core and the movable core are placed at both ends of the frame, and the two iron column portions are inserted into the hollow portion of the cylindrical portion of the frame; S3. Installing accessories, installing a plurality of the bimetallic strips at one end of the frame close to the active iron core, and then placing the active iron core completely close to the frame, installing a plurality of the shape memory alloy springs on the limit seat, and then installing the limit seat on the base, and adjusting the shape memory alloy springs to align with the active iron core; S4. Momentum verification: place the base horizontally, slide the movable iron core left and right in the gap between the limit seat and the frame and detect the size of the air gap to verify that the size of the air gap is not less than 0.1 mm and not more than 1 mm under the limit momentum of the movable iron core in two directions.

[0015] Furthermore, in step S2, before installing the movable iron core, a polytetrafluoroethylene patch is provided at a position of the base and the frame corresponding to the motion track of the movable iron core; In step S3, a buckle cover mounted on the base is also assembled at the joint of the two outer frame parts, and the buckle cover is used to assist in fixing the fixed iron core and limit the shaking amount of the movable iron core.

[0016] In summary, the beneficial technical effects of this application are: 1. When the temperature rise of the micro-transformer during operation is sensed by the multiple shape memory alloy springs on the limit seat, once the temperature rise exceeds the phase change temperature of the shape memory alloy spring, the shape memory alloy spring transforms into austenite and softens, and its own elastic force decreases or even disappears, and it can no longer push the movable iron core, so that the iron column of the movable iron core can slide freely in the cylindrical part of the skeleton at this time; and the bimetallic strip expands and deforms due to heat, so that its middle part is strongly bent in the direction away from the skeleton. Under the push of the bending deformation force of multiple bimetallic strips, the movable iron core can move toward the limit seat. At this time, the distance between the two iron columns is enlarged, so that the air gap is increased, which can control the temperature rise of the transformer to a certain extent, avoid overheating, and ensure the electromagnetic efficiency of the micro-transformer; 2. When the temperature of the micro-transformer decreases, based on the principle of thermal expansion and contraction, the bending tendency of the middle part of the bimetallic strip weakens, the pushing effect on the movable iron core is lost, and it shrinks to the corresponding bending degree according to the corresponding temperature; and for the shape memory alloy spring, once the temperature of the micro-transformer drops to the temperature sensed by the shape memory alloy spring is lower than the phase transition temperature, the shape memory alloy spring transforms into the martensite phase and restores its elasticity to drive the movable iron core away from the limit seat, so that the movable iron core moves to be close to the bent parts of the multiple bimetallic strips, and at this time the distance between the two iron column parts is reduced to reduce the air gap; 3. Through the arrangement of multiple bimetallic strips and multiple shape memory alloy springs, the air gap between the movable iron core and the fixed iron core increases with the temperature rise of the micro-transformer, and decreases and recovers with the temperature drop of the micro-transformer, thereby realizing the dynamic adjustment of the air gap of the micro-transformer, and autonomously controlling its temperature rise to ensure its electromagnetic efficiency under different load conditions as much as possible; 4. Since both ends of the bimetallic strip are embedded in the embedding seats at both ends, the bending deformation thrust of the bimetallic strip is increased while the actuation stroke is reduced, which is particularly suitable for high-precision adjustment of the air gap within the range of 0.1mm to 1mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application; Figure 2It is a side view of the overall structure of an embodiment of the present application; Figure 3 is a top view of the overall structure of an embodiment of the present application; Figure 4 is along Figure 3 Schematic diagram of the cross-sectional structure along the AA line; Figure 5 It is a schematic diagram of the explosion structure of an embodiment of the present application; Figure 6 is a schematic diagram of an exploded structure from another perspective of an embodiment of the present application; Figure 7 is along Figure 3 Schematic diagram of the cross-sectional structure along line BB.

[0018] Description of reference numerals: 1. Base; 11. Input pin; 12. Output pin; 13. Tenon; 14. Fixing hole; 15. Positioning hole; 2. frame; 21. seat; 211. inlay; 31. primary coil; 32. secondary coil; 41, fixed iron core; 42, movable iron core; 401, outer frame; 402, iron column; 43, air gap; 5. Limiting seat; 51. Accommodating groove; 52. Limiting protrusion; 53. Fixing column; 54. Fixing screw; 61. Bimetallic strip; 62. Shape memory alloy spring; 7. Buckle cover; 71. Sliding gap; 72. Tenon seat; 73. Positioning column. DETAILED DESCRIPTION

[0019] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0020] The present application embodiment discloses a micro transformer suitable for a low power consumption charger. Figure 1-Figure 4 It includes a base 1, a frame 2, a primary coil 31 and a secondary coil 32. The base 1 is provided with an input pin 11 connected to the primary coil 31 and an output pin 12 connected to the secondary coil 32. An insulating layer is provided between the primary coil 31 and the secondary coil 32.

[0021] The base 1 is provided with a fixed iron core 41 fixed on the base 1 and a movable iron core 42 slidably arranged on the base 1. The sliding direction of the movable iron core 42 is arranged along the axial direction of the cylindrical part of the skeleton 2. The fixed iron core 41 and the movable iron core 42 both include an outer frame part 401 and an iron column part 402, and the outer frame part 401 and the iron column part 402 are in an "E" shape as a whole. An air gap 43 is reserved between the two iron column parts 402. Based on the conventional setting of the micro transformer, the size range of the air gap 43 is 0.1mm~1mm. A limit seat 5 located at one end of the frame 2 is detachably installed on the base 1, and the iron column portion 402 of the movable iron core 42 is located between the limit seat 5 and the frame 2. Specifically, the limit seat 5 is L-shaped, and its horizontal section is penetrated by a plurality of fixing screws 54 threadedly connected to the base 1, and its vertical section bottom end is fixedly connected to a plurality of fixing columns 53 penetrating the base 1, and a fixing hole 14 is penetrated on the base 1 for the fixing column 53 to pass through, thereby the stability of the limit seat 5 on the base 1 can be greatly improved through the staggered fixation of the fixing column 53 and the fixing screw 54.

[0022] And, refer to Figure 4 , Figure 5 and Figure 6 A plurality of bimetallic strips 61 are installed on the side of the skeleton 2 close to the limit seat 5. The bimetallic strips 61 are configured to deform and warp toward the side away from the skeleton 2 when the temperature they sense increases, and push the movable iron core 42 close to the limit seat 5, so as to increase the air gap 43. Specifically, the bimetallic strips 61 are copper-iron-nickel bimetallic strips 61, and the iron-nickel metal strips are arranged on the side close to the skeleton 2, and the copper metal strips are arranged on the side close to the limit seat 5. The copper metal strips can undergo a large expansion deformation at 40°C to 60°C.

[0023] At the same time, a plurality of shape memory alloy springs 62 are arranged between the limit seat 5 and the movable iron core 42. The shape memory alloy springs 62 are configured to transform into an austenite phase and soften when the temperature sensed by them exceeds their phase transition temperature; and when the temperature sensed by them is lower than their phase transition temperature, the shape memory alloy springs 62 transform into a martensite phase and restore elasticity to drive the movable iron core 42 away from the limit seat 5, so as to reduce the air gap 43. When specifically set, the phase transition temperature range of the shape memory alloy springs 62 can be any value between 40°C and 60°C, which can be selected according to the working conditions of the micro-transformer. And under the initial normal temperature, the elastic deformation force of the shape memory alloy springs 62 pushes the movable iron core 42 to press against the skeleton 2, and at this time, the air gap 43 reaches the set minimum value.

[0024] Among them, refer to Figure 5There are multiple bimetallic strips 61 and they are distributed in an evenly spaced circular array with the central axis of the cylindrical portion of the skeleton 2. A plurality of embedding seats 21 are fixedly connected to the skeleton 2. The embedding seats 21 have embedding openings 211 for the head ends of the bimetallic strips 61 to be embedded. The embedding seats 21 with two embedding openings 211 facing each other form a group and the two ends of the bimetallic strip 61 are respectively embedded in the two embedding seats 21 of the same group; and in actual installation, when the two ends of the bimetallic strip 61 are completely embedded in the two embedding seats 21 of the same group, the middle part of the bimetallic strip 61 has a certain tendency to bend in the direction away from the skeleton 2, and when the outer protrusion thereof is at the farthest distance from the skeleton 2, it does not exceed the thickness of the embedding seat 21.

[0025] In this way, when the micro-transformer of the present application is working, a large amount of heat is usually generated due to copper loss and iron loss. This heat is accumulated in the charger used to assemble the micro-transformer. Usually, this low-power charger is not equipped with an active heat dissipation system, resulting in heat being stored in the charger housing for a long time. The copper loss (winding loss) and iron loss (core loss) will increase with the increase in temperature, which will further lead to a decrease in the electromagnetic efficiency of the micro-transformer.

[0026] When these temperature rises are sensed by the multiple shape memory alloy springs 62 on the limit seat 5, once the temperature rise exceeds the phase change temperature of the shape memory alloy spring 62, the shape memory alloy spring 62 transforms into austenite and softens, and its own elastic force is reduced or even disappears, and it can no longer push the movable iron core 42, so that the iron column portion 402 of the movable iron core 42 can slide freely in the cylindrical portion of the skeleton 2.

[0027] At the same time, these temperature rises are also detected by the multiple bimetallic strips 61 on the skeleton 2. The thermal expansion deformation of the copper metal strip on the bimetallic strip 61 is much greater than the thermal expansion deformation of the iron-nickel metal strip. On the one hand, both ends of the bimetallic strip 61 are inserted into the embedded seats 21 at both ends. On the other hand, the bimetallic strip 61 has a bending tendency in the middle away from the skeleton 2. Therefore, the deformation difference between the copper metal strip and the iron-nickel metal strip in the bimetallic strip 61 is reflected in the middle of the bimetallic strip 61, that is, the middle of the bimetallic strip 61 is strongly bent in the direction away from the skeleton 2. Under the push of the bending deformation force of multiple bimetallic strips 61, the movable iron core 42 can be moved toward the limit seat 5. At this time, the distance between the two iron column parts 402 is enlarged, so that the air gap 43 is increased. When the air gap 43 is increased, the magnetic resistance will increase, thereby reducing the magnetic flux density, which helps to prevent core saturation, reduce hysteresis loss and eddy current loss (iron loss). Therefore, the temperature rise of the transformer can be controlled to a certain extent, overheating can be avoided, and the electromagnetic efficiency of the micro transformer can be ensured. Furthermore, since both ends of the bimetallic strip 61 are embedded in the embedding seats 21 at both ends at this time, the bending offset of the middle portion of the bimetallic strip 61 is much smaller than the bending offset when one end of the bimetallic strip 61 is fixed and the other end is movably set. This increases the bending deformation thrust of the bimetallic strip 61 while reducing the actuation stroke, and is particularly suitable for high-precision adjustment of the air gap 43 within the range of 0.1mm to 1mm.

[0028] When the temperature of the micro-transformer is lowered, based on the principle of thermal expansion and contraction, the bending tendency of the middle part of the bimetallic strip 61 is weakened, the pushing effect on the movable iron core 42 is lost, and the bimetallic strip 61 shrinks to the corresponding bending degree according to the corresponding temperature; and for the shape memory alloy spring 62, once the temperature of the micro-transformer drops to the temperature sensed by the shape memory alloy spring 62 is lower than the phase transition temperature, the shape memory alloy spring 62 transforms into the martensite phase and restores elasticity to drive the movable iron core 42 away from the limit seat 5, so that the movable iron core 42 moves to be close to the bending part of the plurality of bimetallic strips 61, and the spacing between the two iron column parts 402 is reduced at this time, so that the air gap 43 is reduced. Therefore, by setting a plurality of bimetallic strips 61 and a plurality of shape memory alloy springs 62, the air gap 43 between the movable iron core 42 and the fixed iron core 41 increases with the temperature rise of the micro-transformer, and decreases and recovers with the temperature drop of the micro-transformer, so that the dynamic adjustment of the air gap 43 of the micro-transformer is realized, and its temperature rise can be autonomously controlled to ensure its electromagnetic efficiency under different load conditions as much as possible.

[0029] Specifically, to ensure the effectiveness of the dynamic adjustment of the air gap 43, refer to Figure 4 and Figure 6The limit seat 5 has a plurality of accommodating grooves 51 for embedding and fixing one end of a plurality of shape memory alloy springs 62, and a plurality of limit protrusions 52 corresponding to the movable iron core 42 are fixedly connected to one side of the limit seat 5 close to the frame 2. When the movable iron core 42 slides to abut against the limit protrusions 52, the air gap 43 between the two iron column portions 402 of the movable iron core 42 and the fixed iron core 41 is 1 mm; and when the movable iron core 42 slides to abut against the embedded seat 21, the air gap 43 between the two iron column portions 402 of the movable iron core 42 and the fixed iron core 41 is not less than 0.1 mm.

[0030] In this way, by means of the setting of the accommodating groove 51, the shape memory alloy spring 62 that enters the austenite phase can be effectively accommodated to avoid affecting the normal movement of the movable iron core 42; and by controlling the size of the limiting protrusion 52 and the insert 21, the movable iron core 42 is adjusted so that the air gap 43 of the micro-transformer is always maintained within the required range of 0.1mm to 1mm, thereby ensuring that the electromagnetic efficiency of the micro-transformer is in the best possible state.

[0031] On the other hand, polytetrafluoroethylene patches (not shown in the figure) are provided on the inner walls of the base 1 and the cylindrical part of the skeleton 2. The polytetrafluoroethylene patches are arranged corresponding to the movement trajectory of the movable iron core 42. As a result, the sliding resistance of the outer frame part 401 of the movable iron core 42 on the base 1 and the iron column part 402 in the cylindrical part of the skeleton 2 can be greatly reduced, thereby ensuring the driving effect of the bimetallic strip 61 on the movable iron core 42 when it is deformed and when the shape memory alloy spring 62 restores the elastic force.

[0032] At the same time, refer to Figure 6 and Figure 7 A buckle cover 7 is fixed on the base 1, and the outer frame part 401 wrapped around the fixed iron core 41 and the movable iron core 42 is arranged on the axial part of the cylindrical part of the skeleton 2. The buckle cover 7 is opened at both ends of the axial direction of the cylindrical part of the skeleton 2. The inner wall of the buckle cover 7 is tightly pressed against the fixed iron core 41, and a sliding gap 71 is reserved between the buckle cover 7 and the movable iron core 42. Specifically, the buckle cover 7 is provided with two and is respectively arranged to cover the butt joints and adjacent parts of the two outer frame parts 401; the two opposite side walls of the base 1 are fixedly connected with a plurality of tenons 13 at the joints corresponding to the two outer frame parts 401, and the end of the buckle cover 7 close to the base 1 is fixedly connected with a tenon seat 72 that is clamped with the tenon 13. In addition, a plurality of positioning posts 73 are fixedly connected to the bottom end of one side of the buckle cover 7 extending between the iron column portion 402 and the outer frame portion 401, and a positioning hole 15 is opened on the base 1 for the positioning posts 73 to be embedded in. By means of the embedding action of the positioning posts 73 in the positioning holes 15 and the snap connection action of the tenon 13 and the tenon seat 72, the buckle cover 7 can be stably fixed on the base 1, which can play a good fixing and limiting role on the fixed iron core 41 and the movable iron core 42.

[0033] In this way, when the fixed iron core 41 and the movable iron core 42 are installed to the two ends of the frame 2, the two are basically limited in position, and the addition of the buckle cover 7 can assist in fixing the fixed iron core 41, so that the fixed iron core 41 can be firmly fixed on the base 1, and the assembly efficiency of the micro transformer can be improved; at the same time, the buckle cover 7 can limit the outer frame 401 of the movable iron core 42 to limit the shaking amount of the movable iron core 42, so that the movable iron core 42 has the ability to slide while not affecting the effective adjustment effect of the bimetallic strip 61 and the shape memory alloy spring 62 on the movable iron core 42 due to its own excessive shaking, thereby ensuring the dynamic control effect of the air gap 43.

[0034] To this end, after the micro-transformer of the present application is installed in the low-power charger, it is also necessary to ensure that when the low-power charger is working, the active iron core 42 of the micro-transformer should be located in a horizontal state on the horizontal base 1 to avoid the gravity of the active iron core 42 itself affecting the adjustment effect of the bimetallic strip 61 and the shape memory alloy spring 62.

[0035] The embodiment of the present application discloses a method for quickly assembling a micro transformer suitable for a low-power charger. Based on the above-mentioned micro transformer suitable for a low-power charger, referring to Figure 1 , which comprises the following steps: S1. Coil winding, winding the primary coil 31 and the secondary coil 32 on the cylindrical part of the skeleton 2 by the sandwich method, and install the skeleton 2 on the base 1; specifically, first wind the inner circle of the primary coil 31 on the cylindrical part of the skeleton 2, wrap it with an insulating layer, and then wind a number of secondary coils 32, and each layer of the secondary coils 32 is also wrapped with an insulating layer, and after the outermost layer of the secondary coil 32 is wound, another layer of insulating layer is wound, and a number of secondary coils 32 are connected in series; then, wind the outer circle of the primary coil 31, and connect the inner and outer circle primary coils 31 in series; then, connect the primary coil 31 to the input pin 11, and connect the secondary coil 32 to the output pin 12.

[0036] S2. Install the iron core. Place the fixed iron core 41 and the movable iron core 42 at both ends of the frame 2, and insert the two iron column parts 402 into the hollow part of the cylindrical part of the frame 2. If necessary, apply glue on the fixed iron core 41 to stably fix the fixed iron core 41 on the base 1.

[0037] S3. Installation of accessories: install a plurality of bimetallic strips 61 at one end of the skeleton 2 close to the movable iron core 42, and arrange the plurality of bimetallic strips 61 symmetrically on the skeleton 2 in the form of an equally spaced circular array. Specifically, after the two ends of the bimetallic strips 61 are embedded in the two sockets 21 of the same group, the middle part of the bimetallic strips 61 is kept to have a certain tendency to bend outward; then, the movable iron core 42 is completely close to the skeleton 2, and a plurality of shape memory alloy springs 62 are installed on the limit seat 5, and then the limit seat 5 is installed on the base 1, and the shape memory alloy springs 62 are adjusted to align with the movable iron core 42.

[0038] S4. Momentum verification: place the base 1 horizontally, slide the movable iron core 42 left and right in the gap between the limit seat 5 and the frame 2, and detect the size of the air gap 43 to verify that the size of the air gap 43 of the movable iron core 42 is not less than 0.1 mm and not more than 1 mm under the limit momentum of the movable iron core 42 in two directions.

[0039] In addition, in step S2 , before installing the movable iron core 42 , polytetrafluoroethylene patches are provided at positions of the base 1 and the frame 2 corresponding to the movement trajectory of the movable iron core 42 to reduce the sliding resistance of the movable iron core 42 .

[0040] Furthermore, in step S3, a buckle cover 7 installed on the base 1 is assembled at the joint of the two outer frame parts 401, and the buckle cover 7 is used to assist in fixing the fixed iron core 41 and limit the shaking amount of the movable iron core 42. Therefore, while ensuring the mobility of the movable iron core 42, the rapid assembly efficiency of the micro transformer of the present application can be ensured.

[0041] The implementation principle of a micro transformer suitable for a low-power charger in the embodiment of the present application is as follows: When the micro-transformer of the present application is working, heat is generated, resulting in temperature rise. When these temperature rises are sensed by the multiple shape memory alloy springs 62 on the limit seat 5, once the temperature rise exceeds the phase change temperature of the shape memory alloy spring 62, the shape memory alloy spring 62 is transformed into austenite and softened, and its own elastic force is reduced or even disappears, and it can no longer push the movable iron core 42, so that the iron column portion 402 of the movable iron core 42 can slide freely in the cylindrical portion of the skeleton 2.

[0042] At the same time, these temperature rises are also detected by the multiple bimetallic strips 61 on the frame 2. The bimetallic strips 61 are deformed by heat expansion, causing the middle part of the bimetallic strips 61 to be strongly bent in the direction away from the frame 2. Under the push of the bending deformation force of the multiple bimetallic strips 61, the movable iron core 42 can move toward the direction close to the limit seat 5. At this time, the distance between the two iron column parts 402 is enlarged, so that the air gap 43 is increased, which can control the temperature rise of the transformer to a certain extent, avoid overheating, and ensure the electromagnetic efficiency of the micro transformer. Moreover, since both ends of the bimetallic strip 61 are embedded in the embedding seats 21 at both ends, the actuation stroke is reduced while the bending deformation thrust of the bimetallic strip 61 is increased, which is particularly suitable for high-precision adjustment of the air gap 43 within the range of 0.1mm to 1mm.

[0043] When the temperature of the micro-transformer drops, based on the principle of thermal expansion and contraction, the bending tendency of the middle part of the bimetallic strip 61 weakens, the pushing effect on the movable iron core 42 is lost, and it shrinks to the corresponding bending degree according to the corresponding temperature; and for the shape memory alloy spring 62, once the temperature of the micro-transformer drops to the temperature sensed by the shape memory alloy spring 62 is lower than the phase transition temperature, the shape memory alloy spring 62 transforms into the martensite phase and restores its elasticity to drive the movable iron core 42 away from the limit seat 5, so that the movable iron core 42 moves to be close to the bent parts of the multiple bimetallic strips 61, and at this time, the distance between the two iron column parts 402 is reduced to reduce the air gap 43.

[0044] Therefore, by setting up multiple bimetallic strips 61 and multiple shape memory alloy springs 62, the air gap 43 between the movable iron core 42 and the fixed iron core 41 increases with the temperature rise of the micro-transformer, and decreases and recovers with the temperature drop of the micro-transformer, thereby realizing the dynamic adjustment of the air gap 43 of the micro-transformer, and its temperature rise can be autonomously controlled to ensure its electromagnetic efficiency under different load conditions as much as possible.

[0045] Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. The words "first", "second", "third" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. "One" or "one" and similar words do not indicate a quantitative limit, but indicate that there is at least one. "Include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0046] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A micro transformer suitable for a low-power charger, comprising a base (1), a frame (2), a primary coil (31) and a secondary coil (32), wherein the base (1) is provided with an input pin (11) connected to the primary coil (31) and an output pin (12) connected to the secondary coil (32), and an insulating layer is provided between the primary coil (31) and the secondary coil (32), characterized in that: The base (1) is provided with a fixed iron core (41) fixed on the base (1) and a movable iron core (42) slidably arranged on the base (1), the fixed iron core (41) and the movable iron core (42) both comprising an outer frame portion (401) and an iron column portion (402), an air gap (43) being reserved between the two iron column portions (402); A limit seat (5) located at one end of the frame (2) is detachably mounted on the base (1), and the movable iron core (42) is located between the limit seat (5) and the frame (2); A plurality of bimetallic strips (61) are installed on a side of the frame (2) close to the limit seat (5), and the bimetallic strips (61) are configured to deform and warp toward a side away from the frame (2) when the temperature they sense increases, and to push the movable iron core (42) close to the limit seat (5), so as to increase the air gap (43); A plurality of shape memory alloy springs (62) are arranged between the limit seat (5) and the movable iron core (42), and the shape memory alloy springs (62) are configured such that when the temperature sensed by the shape memory alloy springs (62) exceeds the phase transition temperature thereof, the shape memory alloy springs (62) are transformed into an austenite phase and soften; and when the temperature sensed by the shape memory alloy springs (62) is lower than the phase transition temperature thereof, the shape memory alloy springs (62) are transformed into a martensite phase and restore elasticity to drive the movable iron core (42) away from the limit seat (5), so that the air gap (43) is reduced.

2. A micro transformer suitable for a low power consumption charger according to claim 1, characterized in that: The bimetallic strips (61) are provided in plurality and are distributed in a circular array at equal intervals about the central axis of the cylindrical portion of the frame (2); the frame (2) is fixedly connected with a plurality of insert seats (21); the insert seats (21) have an insert opening (211) for inserting the head end of the bimetallic strip (61); the insert seats (21) with two opposite insert openings (211) form a group, and the two ends of the bimetallic strip (61) are respectively inserted into the two insert seats (21) of the same group.

3. A micro transformer suitable for a low power consumption charger according to claim 1, characterized in that: The limiting seat (5) is provided with a plurality of accommodating grooves (51) for embedding and fixing one end of a plurality of the shape memory alloy springs (62).

4. A micro transformer suitable for a low power consumption charger according to claim 3, characterized in that: A plurality of limiting protrusions (52) corresponding to the movable iron core (42) are fixedly connected to one side of the limiting seat (5) close to the frame (2); when the movable iron core (42) slides to abut against the limiting protrusions (52), the air gap (43) between the two iron column parts (402) of the movable iron core (42) and the fixed iron core (41) is 1 mm.

5. A micro transformer suitable for a low power consumption charger according to claim 2, characterized in that: When the movable iron core (42) slides to abut against the embedded seat (21), the air gap (43) between the movable iron core (42) and the two iron column parts (402) of the fixed iron core (41) is not less than 0.1 mm.

6. A micro transformer suitable for a low power consumption charger according to claim 1, characterized in that: The base (1) and the inner circumferential wall of the cylindrical portion of the frame (2) are both provided with polytetrafluoroethylene patches, and the polytetrafluoroethylene patches are provided corresponding to the movement trajectory of the movable iron core (42).

7. A micro transformer suitable for a low power consumption charger according to claim 1, characterized in that: A buckle cover (7) is fixed on the base (1) and is wrapped around the outer frame portion (401) of the fixed iron core (41) and the movable iron core (42). The buckle cover (7) is provided with openings at both axial ends of the cylindrical portion of the frame (2). The inner wall of the buckle cover (7) is tightly pressed against the fixed iron core (41), and a sliding gap (71) is reserved between the buckle cover (7) and the movable iron core (42).

8. A micro transformer suitable for a low power consumption charger according to claim 7, characterized in that: A plurality of tenons (13) are fixedly connected to two opposite side walls of the base (1) at the joints corresponding to the two outer frame parts (401), and a tenon seat (72) is fixedly connected to the tenons (13) at one end of the buckle cover (7) close to the base (1).

9. A method for quickly assembling a micro transformer suitable for a low-power charger, based on a micro transformer suitable for a low-power charger as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Coil winding, winding the primary coil (31) and the secondary coil (32) on the cylindrical portion of the frame (2) by a sandwich method, and mounting the frame (2) on the base (1); S2. installing the iron core, placing the fixed iron core (41) and the movable iron core (42) at both ends of the frame (2), and inserting the two iron column parts (402) into the hollow part of the cylindrical part of the frame (2); S3. Installing accessories, installing a plurality of the bimetallic strips (61) on one end of the frame (2) close to the movable iron core (42), and then placing the movable iron core (42) completely close to the frame (2), installing a plurality of the shape memory alloy springs (62) on the limit seat (5), and then installing the limit seat (5) on the base (1), and adjusting the shape memory alloy springs (62) to align with the movable iron core (42); S4. Momentum verification: the base (1) is placed horizontally, and the movable iron core (42) is slid left and right in the gap between the limit seat (5) and the frame (2) to detect the size of the air gap (43) to verify that the size of the air gap (43) is not less than 0.1 mm and not more than 1 mm under the limit momentum of the movable iron core (42) in two directions.

10. A quick assembly method for a micro transformer suitable for a low power consumption charger according to claim 9, characterized in that: In step S2, before installing the movable iron core (42), a polytetrafluoroethylene patch is provided at a position of the base (1) and the frame (2) corresponding to the movement track of the movable iron core (42); In step S3, a buckle cover (7) mounted on the base (1) is also assembled at the joint of the two outer frame parts (401), and the buckle cover (7) is used to assist in fixing the fixed iron core (41) and limit the shaking amount of the movable iron core (42).

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