SMD type miniature current transformer

Abstract

The utility model relates to an SMD (Surface Mount Device) type miniature current transformer which comprises a rectangular transformer shell, one side surface of the transformer shell is provided with an open cavity, the center of the open cavity is provided with an insulating column arranged along the opening direction, the insulating column of the open cavity is sleeved with a circular ring-shaped secondary coil, and the secondary coil is provided with a secondary coil. The secondary coil comprises an annular iron core framework, a coil is wound on the iron core framework, binding posts are arranged at the two ends of the coil, epoxy resin is filled in the open containing cavity, and a sealing cover is arranged at an opening of the open containing cavity. A through core hole is formed in the insulation column, a wire column arranged in the opening direction is arranged at one corner of the open containing cavity, a through wire core hole is formed in the wire column, and a wire groove is formed in the outer side face, corresponding to the bottom face of the open containing cavity, of the mutual inductor shell. The core hole, the wire groove and the wire core hole form a U-shaped cavity, and a U-shaped primary coil is installed in the U-shaped cavity.

Description

Technical Field

[0001] This utility model relates to the field of current transformer technology, and in particular to an SMD type miniature current transformer. Background Technology

[0002] A current transformer is an instrument that measures current by converting a large primary current into a small secondary current based on the principle of electromagnetic induction. A current transformer consists of a closed iron core and windings. Its primary winding has very few turns and is connected in series with the circuit whose current needs to be measured.

[0003] Therefore, it often carries the entire current of the circuit, resulting in a relatively large number of turns in the secondary winding. Connected in series with measuring instruments and protection circuits, the secondary circuit of the current transformer is always closed during operation. Consequently, the impedance of the series coils in the measuring instruments and protection circuits is very small, and the operating state of the current transformer is close to a short circuit. The current transformer converts a large primary current into a small secondary current for measurement; the secondary side must not be open-circuited.

[0004] In fields such as instrumentation and new energy, secondary current transformers are required. These current transformers typically have an input of only a few A and an output of mA, and they occupy a very small space. Therefore, it is necessary to design a secondary miniature current transformer that meets the requirements. The challenges of this type of transformer are: small size, compact design; and consideration of safety regulations, ensuring that the primary and secondary currents are isolated. Utility Model Content

[0005] The purpose of this invention is to overcome the defects in the existing technology and provide an SMD type miniature current transformer that is small in size and has strong insulation capability.

[0006] To achieve the above objectives, the technical solution of this utility model is to design an SMD type miniature current transformer, including a rectangular transformer housing. One side of the transformer housing is an open cavity, which is rectangular. An insulating post is located at the center of the open cavity, extending along the opening direction. A ring-shaped secondary coil is mounted on the insulating post. The secondary coil includes a ring-shaped iron core frame around which the coil is wound. Terminals are located at both ends of the coil. The open cavity is filled with epoxy resin to fix the secondary coil and terminals inside the open cavity. A cap is provided at the opening of the open cavity. The current transformer housing is connected as follows: the insulating post has a through core hole, and a conductor post is provided at one corner of the open cavity along the opening direction. The conductor post has a through conductor core hole. A conductor groove is provided on the outer side of the current transformer housing corresponding to the bottom surface of the open cavity. One end of the conductor groove is connected to the end face of the conductor core hole with a rounded transition, and the other end of the conductor groove is connected to the end face of the core hole with a rounded transition. The connected core hole, conductor groove, and conductor core hole form a U-shaped cavity. A U-shaped primary coil is installed in the U-shaped cavity. The two separate ends of the U-shaped primary coil pass through the core hole and the conductor core hole respectively and are exposed outside the current transformer housing.

[0007] A further preferred technical solution is that the connecting part of the U-shaped primary coil is inserted into the wire groove, so that the connecting part of the U-shaped primary coil is flush with the transformer housing.

[0008] A further preferred technical solution is that the terminal is elongated, and a protruding post is provided at each of the two other corners of the open cavity, with each protruding post connected to one side of the open cavity at the corresponding corner and forming a slot with the other side, and the terminal is installed in the slot.

[0009] A further preferred technical solution is that the two protruding pillars are disposed at the corners of two adjacent open cavities and the two protruding pillars are symmetrically disposed on a pair of symmetrical inner surfaces of the open cavities.

[0010] A further preferred technical solution is that one protrusion is disposed on one inner side of the open cavity, and another protrusion is disposed on another symmetrical inner side of the open cavity, and then a groove is formed between the two symmetrical surfaces and away from the inner side of the wire post, and the terminal post is installed in the groove.

[0011] A heat-conducting rod is fixedly connected to the middle of the inner liner of the lower sand box. The heat-conducting rod is fixedly connected to the outer wall of the inner liner of the lower sand box. Through the above structure, a large amount of heat energy released by the molten metal during the casting process can be dissipated in time, reducing the decline in casting quality and performance caused by high molten metal temperature, and effectively improving the heat dissipation efficiency during the casting process.

[0012] The advantages and beneficial effects of this utility model are as follows: the scheme of using a U-shaped primary coil with an internal transformer housing on one side helps users solve the space problem on the primary coil side. At the same time, since the primary side is fixed, the redundant space of the secondary coil can be minimized, making the inner hole of the secondary coil small enough. It also greatly improves the insulation capability of the primary and secondary coils. Furthermore, the central position of the insulating column ensures both the insulation and the fixed position of the insulating column. Epoxy resin can also effectively fix the insulating column. Attached Figure Description

[0013] Figure 1 This is the exploded stereoscopic view of the present invention. Figure 1 ;

[0014] Figure 2 This is a perspective view of the present invention;

[0015] Figure 3 This is a partial view of the perspective of this utility model;

[0016] Figure 4 This is the exploded stereoscopic view of the present invention. Figure 2 ;

[0017] In the diagram: 10. Transformer housing; 11. Open cavity; 12. Slot; 13. Protrusion; 14. Insulating post; 15. Conductor post; 16. Conductor core hole; 17. Conductor groove; 18. Core hole; 20. U-shaped primary coil; 21. Separating end; 30. Secondary coil; 31. Iron core frame; 32. Terminal post; 40. Cover. Detailed Implementation

[0018] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0019] like Figures 1 to 4As shown, an SMD type miniature current transformer includes a rectangular transformer housing 10. One side of the transformer housing 10 is an open cavity 11, which is rectangular. An insulating post 14 is located at the center of the open cavity 11, extending along the opening direction. The insulating post 14 has a through core hole 18. A conductor post 15 is located at one corner of the open cavity 11, extending along the opening direction. The conductor post 15 has a through conductor core hole 16. A conductor groove 17 is provided on the outer surface of the transformer housing 10 corresponding to the bottom surface of the open cavity 11. One end of the wire groove 17 is connected to the end face of the wire core hole 16 with a rounded transition, and the other end of the wire groove 17 is connected to the end face of the core hole 18 with a rounded transition. The connected core hole 18, wire groove 17, and wire core hole 16 form a U-shaped cavity. A U-shaped primary coil 20 is installed in the U-shaped cavity. The two separate ends 21 of the U-shaped primary coil 20 pass through the core hole 18 and the wire core hole 16 respectively and are exposed outside the transformer housing 10. The connecting part of the U-shaped primary coil 20 is inserted into the wire groove 17 so that the connecting part of the U-shaped primary coil 20 is flush with the transformer housing 10.

[0020] A ring-shaped secondary coil 30 is fitted onto the insulating post 14 of the open cavity 11. The secondary coil 30 includes a ring-shaped iron core frame 31 around which the coil is wound. The two ends of the coil are provided with terminals 32. In one embodiment, the terminals 32 are elongated. At the other two corners of the open cavity 11, there is a protrusion 13 arranged along the opening direction. Each protrusion 13 is connected to one side of the open cavity 11 at the corresponding corner and forms a slot 12 with the other side. The terminals 32 are installed in the slots 12. The open cavity 11 is filled with epoxy resin to fix the secondary coil 30 and terminals 32 in the open cavity 11. A cover 40 is provided at the opening of the open cavity 11 and connected to the transformer housing 10.

[0021] In one embodiment, two protrusions 13 are disposed at the corners of two adjacent open cavities 11 and the two protrusions 11 are symmetrically disposed on a pair of symmetrical inner surfaces of the open cavities 11, that is, one protrusion 13 is disposed on one inner surface of the open cavity 11 and the other protrusion 13 is disposed on another relatively symmetrical inner surface of the open cavity 11, and then a groove 12 is formed between the two symmetrical surfaces and away from the inner surface of the wire post 15, and the terminal post 32 is installed in the groove 12.

[0022] The design adopts a U-shaped primary coil 20 with the transformer housing 10 built inside. This helps users solve the space problem on the primary coil side. At the same time, since the primary side is fixed, the redundant space of the secondary coil 30 can be minimized, making the inner hole of the secondary coil small enough. It also greatly improves the insulation capability of the primary and secondary coils. In addition, the central insulating column 14 is centered, which ensures the insulation and fixed position of the insulating column 14. Epoxy resin can also effectively fix the insulating column 14.

[0023] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A miniature current transformer of the SMD type, comprising a rectangular transformer housing, wherein one side of the transformer housing is an open cavity, and the open cavity is a rectangular cavity, characterized in that: An insulating post is positioned at the center of the open cavity, running along the opening direction. A ring-shaped secondary coil is mounted on the insulating post. The secondary coil includes a ring-shaped iron core frame around which the coil is wound. Terminals are located at both ends of the coil. The open cavity is filled with epoxy resin to fix the secondary coil and terminals within the cavity. A cap is provided at the opening of the cavity, connecting to the transformer housing. A through-hole is provided on the insulating post, and a [missing information - likely a design feature] is located at one corner of the open cavity. A conductor post is provided along the opening direction, and a through conductor core hole is provided on the conductor post. A conductor groove is provided on the outer side of the current transformer housing corresponding to the bottom surface of the opening cavity. One end of the conductor groove is connected to the end face of the conductor core hole with a rounded transition, and the other end of the conductor groove is connected to the end face of the core hole with a rounded transition. The connected core hole, conductor groove, and conductor core hole form a U-shaped cavity. A U-shaped primary coil is installed in the U-shaped cavity. The two separate ends of the U-shaped primary coil pass through the core hole and the conductor core hole respectively and are exposed on the outside of the current transformer housing.

2. The SMD type miniature current transformer according to claim 1, characterized in that: The connecting part of the U-shaped primary coil is inserted into the wire groove so that the connecting part of the U-shaped primary coil is flush with the transformer housing.

3. The SMD type miniature current transformer according to claim 1, characterized in that: The terminal is elongated, and at each of the two corners of the open cavity, there is a protruding post arranged along the opening direction. Each protruding post is connected to one side of the open cavity at the corresponding corner and forms a slot with the other side. The terminal is installed in the slot.

4. The SMD type miniature current transformer according to claim 3, characterized in that: The two protruding pillars are located at the corners of two adjacent open cavities and are symmetrically arranged on a pair of symmetrical inner surfaces of the open cavities.

5. The SMD type miniature current transformer according to claim 4, characterized in that: One protrusion is disposed on one inner side of the open cavity, and another protrusion is disposed on another symmetrical inner side of the open cavity, and then a groove is formed between the two symmetrical surfaces and away from the inner side of the wire post, and the terminal post is installed in the groove.

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