The screw connection structure of the trip unit and the energy meter with it

Abstract

This utility model provides a screw connection structure for a trip unit and an energy meter having the same. The trip unit includes a housing, within which a coaxial stationary iron core, a moving iron core, and a screw are arranged. The screw penetrates the stationary iron core from the stationary iron core toward the moving iron core. A return spring is arranged between the stationary and moving iron cores and is sleeved on the screw. A step is provided between the outer circular wall of the middle part of the screw and the inner circular wall of the stationary iron core to restrict the screw from moving toward the moving iron core. The end of the screw away from the moving iron core abuts against the inner wall of the housing in a reverse installation manner. By using the step limit and the existing housing, the screw is limited on both sides, improving the reliability of the trip unit. It eliminates the need for threaded connections, reducing operational difficulty and improving production efficiency. It avoids the use of thread-locking adhesive, preventing quality risks such as missed application or adhesive contamination, and reducing material usage costs.

Description

Technical Field

[0001] This utility model relates to the field of trip unit technology, specifically to a screw connection structure for a trip unit and an energy meter having the same. Background Technology

[0002] Currently, as shown in the attached document Figure 1 and 2 As shown, the screw in the trip unit is mainly assembled by screwing into the stationary iron core from the driven iron core side using a threaded connection. During the engagement process, the screw moves downwards while rotating, and threadlocker is applied to the threaded connection to enhance the fixing strength. However, after actual production verification and long-term use feedback, this structure and assembly method have some defects.

[0003] Most importantly, this assembly method is a unidirectional constraint structure, relying solely on one side of the thread and thread-locking adhesive to create a single constraint on the screw's movement to the other side, lacking effective restriction on the reverse degree of freedom. During actual product operation, the periodic movement and instantaneous impacts of internal components will continuously act on the screw. If the thread-locking adhesive is not applied properly or is unevenly or insufficiently applied, the screw is very likely to loosen or even detach from the unconstrained direction, affecting the normal contact between the moving and stationary iron cores. This will cause the trip unit to fail to complete its operation as designed, leading to product malfunction.

[0004] Furthermore, the thread fitting and adhesive application process is complex, resulting in low production efficiency and long processing time, which increases the assembly cycle of a single product. This process is also highly dependent on manual operation; core steps such as thread alignment and adhesive dosage control are difficult to achieve stable and efficient batch operations using existing automated equipment, hindering capacity increases and process modernization. Moreover, excessive application of thread-locking adhesive or overflow can contaminate the mating surfaces of the moving and stationary iron cores, causing them to stick together and hindering their normal separation. This can lead to delayed product response, malfunctions, and in severe cases, even complete product failure. In addition, the use of thread-locking adhesive increases material costs, negatively impacting the product's cost advantage in the market.

[0005] Therefore, it is necessary to redesign the screw structure and its fixing process to improve product reliability and consistency, while achieving automated production, increasing production efficiency, and reducing material and manufacturing costs. Summary of the Invention

[0006] The purpose of this utility model is to provide a screw connection structure for a trip unit and an energy meter having the same, so as to solve the above-mentioned problems.

[0007] The technical solution adopted in this utility model is as follows: A screw connection structure for a trip unit is disclosed. The trip unit includes a housing, and a coaxial stationary iron core, a moving iron core, and a screw are disposed within the housing. The screw passes through the stationary iron core from the stationary iron core toward the moving iron core. A return spring is disposed between the stationary iron core and the moving iron core and is sleeved on the screw. A step is provided between the outer circular wall of the middle part of the screw and the inner circular wall of the stationary iron core to restrict the movement of the screw toward the moving iron core. The end of the screw away from the moving iron core abuts against the inner wall of the housing.

[0008] As a further improvement of this utility model, a first step extending radially inward is provided on the inner circular wall of the stationary iron core. The screw includes a rod body and a second step extending radially outward from the rod body. A connecting through hole is provided on the first step. The connecting through hole is coaxially arranged with the first step. The diameter of the connecting through hole is smaller than the diameter of the second step. The rod body passes through the connecting through hole. The second step abuts against the radial end face of the first step away from the moving iron core.

[0009] As a further improvement of this utility model, a limiting through hole is formed from the radial end face of the first step away from the moving iron core to the radial end face of the stationary iron core away from the moving iron core, and the second step cooperates with the limiting through hole.

[0010] As a further improvement of this utility model, the second step is fitted with a clearance fit or an interference fit with the limiting through hole.

[0011] As a further improvement of this utility model, the radial end face of the second step away from the first step abuts against the inner wall of the outer shell.

[0012] As a further improvement of this utility model, a first guide slope is provided on the end face of the limiting through hole away from the first step. The first guide slope facilitates the rod and the second step to extend into the limiting through hole.

[0013] As a further improvement of this utility model, a second guide slope is provided on the end face of the second step facing the stationary iron core. The second guide slope facilitates the second step extending into the limiting through hole.

[0014] As a further improvement of this utility model, a first mounting hole is formed from the radial end face of the first step near the moving iron core to the radial end face of the stationary iron core near the moving iron core. A second mounting hole that mates with the first mounting hole is provided in the moving iron core. One end of the return spring extends into the first mounting hole and connects to the stationary iron core, and the other end of the return spring extends into the second mounting hole and connects to the moving iron core. The return spring is sleeved on the rod body.

[0015] As a further improvement of this utility model, a third guide slope is provided on the side of the first mounting hole facing the moving iron core, and the third guide slope facilitates the insertion of the reset spring into the first mounting hole.

[0016] An electricity meter includes a screw connection structure for a trip unit as described above.

[0017] The beneficial effects of this utility model are as follows: The above structure, using a reverse installation method, utilizes the stepped limit and the existing housing to achieve double-sided limiting of the screw, improving the reliability of the trip unit; it eliminates the need for threaded connections, reducing operational difficulty and improving production efficiency; it avoids the use of thread-locking adhesive, preventing quality risks such as missed application or adhesive contamination, and reducing material usage costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the screw connection in an existing trip unit; Figure 2 This is an assembly diagram of the screw in an existing trip unit; Figure 3 This is a schematic diagram of the screw connection structure of this utility model inside the trip unit; Figure 4 yes Figure 3 Enlarged view of point A in the middle; Figure 5 This is a schematic diagram of the internal structure of the stationary iron core; Figure 6 This is an assembly diagram of the screw in the screw connection structure of this utility model.

[0019] Wherein: 1-outer shell, 2-screw, 201-rod body, 202-second step, 203-second guide slope, 3-stationary iron core, 301-first step, 302-connecting through hole, 303-limiting through hole, 304-first mounting hole, 305-first guide slope, 306-third guide slope, 4-moving iron core, 401-second mounting hole, 5-reset spring. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present invention.

[0021] If the description of this utility model involves directions (e.g., up, down, left, right, front, back, outside, inside, etc.), then the directions involved need to be defined. For example, "To clearly express the position and direction described in this utility model, the operator of the instrument is used as a reference, the end closer to the operator is the proximal end, and the end farther from the operator is the distal end." Or, the paper can be used as a reference. Of course, if the positional relationship between the two is defined by mutual reference in the subsequent description, then this definition is not required.

[0022] A screw connection structure for a trip unit, such as Figure 3 As shown, the trip unit includes a housing 1, within which a stationary iron core 3, a moving iron core 4, and a screw 2 are disposed. The stationary iron core 3, the moving iron core 4, and the screw 2 are coaxial. The screw 2 passes through the stationary iron core 3 from the stationary iron core 3 toward the moving iron core 4. A return spring 5 is disposed between the stationary iron core 3 and the moving iron core 4. The return spring 5 is sleeved on the screw 2 and is used to provide a return force, so that a sufficient distance is maintained between the moving iron core 4 and the stationary iron core 3. A step is provided between the outer circular wall of the middle part of the screw 2 and the inner circular wall of the stationary iron core 3 to restrict the movement of the screw 2 toward the moving iron core 4. The end of the screw 2 away from the moving iron core 4 abuts against the inner wall of the housing 1, which is located on the side away from the moving iron core 4 relative to the stationary iron core 3.

[0023] As one embodiment of this utility model, such as Figures 4-6 As shown, a first step 301 extending radially inward is provided on the inner circular wall of the stationary iron core 3. The screw 2 includes a rod body 201 and a second step 202 extending radially outward from the rod body 201. A connecting through hole 302 is provided on the first step 301. The connecting through hole 302 is coaxially arranged with the first step 301. The diameter of the connecting through hole 302 is smaller than the diameter of the second step 202. The rod body 201 passes through the connecting through hole 302 and enters the return spring 5. The second step 202 abuts against the radial end face of the first step 301 away from the moving iron core 4.

[0024] Through the aforementioned stepped limiting design, the travel limit constraint on the screw 2 towards the moving iron core 4 is achieved. The screw 2 is installed from the stationary iron core 3 towards the moving iron core 4. Compared with the existing assembly scheme, it adopts reverse installation and abuts against the inner wall of the existing outer shell 1, thereby achieving the travel limit constraint on the screw 2 away from the moving iron core 4. Thus, there are two surfaces in the trip unit that can simultaneously constrain the screw 2, which completely restricts the axial movement displacement of the screw 2 from the design, and achieves reliable fixation of the screw 2.

[0025] As an embodiment of this utility model, a limiting through hole 303 is formed from the radial end face of the first step 301 away from the moving iron core 4 to the radial end face of the stationary iron core 3 away from the moving iron core 4. The limiting through hole 303 is coaxially arranged with the connecting through hole 302 and the limiting through hole 302 communicates with the connecting through hole 302. The second step 202 cooperates with the limiting through hole 303. The second step 202 can extend from the radial end face of the first step 301 away from the moving iron core 4 to the inner wall of the outer shell 1. That is, the radial end face of the second step 202 away from the first step 301 abuts against the inner wall of the outer shell 1 to increase the cooperation length (or cooperation area) between the second step 202 and the limiting through hole 303, thereby improving the connection stability between the two and avoiding axial displacement.

[0026] As an embodiment of the present invention, a first guide slope 305 is provided on the end face of the limiting through hole 303 away from the first step 301. The first guide slope 305 facilitates the rod 201 and the second step 202 to extend into the limiting through hole 303.

[0027] As an embodiment of the present invention, a second guide slope 203 is provided on the end face of the second step 202 facing the stationary iron core 3. The second guide slope 203 facilitates the second step 202 to extend into the limiting through hole 303 and can avoid sharp collisions between the second step 202 and the first step 301.

[0028] In one embodiment of this utility model, a first mounting hole 304 is formed from the radial end face of the first step 301 near the moving iron core 4 to the radial end face of the stationary iron core 3 near the moving iron core 4. The first mounting hole 304 is coaxially arranged with the connecting through hole 302 and communicates with the connecting through hole 302. The rod body 201 passes through the connecting through hole 302, extends into the first mounting hole 304, and extends towards the moving iron core 4. A second mounting hole 401 is provided in the moving iron core 4 to cooperate with the first mounting hole 304. The diameter of the first mounting hole 304 is the same as the diameter of the second mounting hole 401, and the diameter of the first mounting hole 304 is larger than the diameter of the connecting through hole 302. The first mounting hole 304 and the second mounting hole 401 are coaxially arranged. One end of the return spring 5 extends into the first mounting hole 304 and connects to the stationary iron core 3, and the other end of the return spring 5 extends into the second mounting hole 401 and connects to the moving iron core 4. The return spring 5 is sleeved on the screw 2.

[0029] Furthermore, a third guide slope 306 is provided on the side of the first mounting hole 304 facing the moving iron core 4, and the third guide slope 306 facilitates the insertion of the reset spring 5 into the first mounting hole 304.

[0030] When installing the screw 2, if the product does not have high displacement requirements for the screw 2, that is, if the fit requirements for the screw 2 are not high, the screw body 201 can be directly inserted into the stationary iron core 3 with the limiting through hole 303 for assembly. This can eliminate additional processes, reduce costs, and improve processing efficiency.

[0031] If there is a high displacement requirement for the screw 2, that is, if the screw 2 is required to be completely immobile, such as Figure 6 As shown, the second step 202 and the limiting through hole 303 are fitted with an interference fit. First, the rod body 201 is inserted into the stationary iron core 3 through the limiting through hole 303. Since the diameter of the second step 202 is slightly larger than the diameter of the limiting through hole 303, a press is used to rivet the second step 202 into the limiting through hole 303. During interference assembly, only the interference fit end (i.e., the second step 202) of the screw 2 is subjected to force, preventing deformation of the screw 2 due to tolerance control. Furthermore, the riveting action is unidirectional. During manufacturing, the mold for manufacturing the screw 2 can be equipped with a limiting structure to control the depth of the interference fit, enabling automated operation of the equipment.

[0032] During assembly, select clearance assembly or interference assembly according to displacement requirements. Insert the rod body 201 of the screw 2 into the limiting through hole 303, the connecting through hole 302 and the first mounting hole 304 in sequence and extend into the return spring 5 until the first step 301 abuts against the second step 202, thereby limiting the movement of the screw 2 towards the moving iron core 4. Then, install the assembled structure, including the moving iron core 4, the stationary iron core 3 and the screw 2, into the outer shell 1, so that the radial end face of the screw 2 away from the moving iron core 4 abuts against the inner wall of the outer shell 1, thereby limiting the movement of the screw 2 away from the moving iron core 4.

[0033] The trip unit screw connection structure provided by this utility model adopts a reverse installation method, using a stepped limiter and the existing outer shell 1 to achieve double-sided limiting of the screw 2, thereby improving the reliability of the trip unit. Depending on the precision requirements of the trip unit itself, two fixing processes can be selected: reverse clearance fit assembly and reverse interference riveting. No threaded connection is required, reducing operational difficulty and saving assembly time. For interference fit, automated operation can be used, improving production efficiency. The design directly avoids the use of thread-locking adhesive, completely eliminating the quality risks of missed application or adhesive contamination, effectively ensuring the consistency and reliability of the trip unit's quality, and reducing material costs.

[0034] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0035] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this utility model, and are not intended to limit the scope of protection of this utility model. All equivalent implementation methods or modifications made without departing from the spirit of this utility model should be included within the scope of protection of this utility model.

Claims

1. A screw connection structure for a trip unit, the trip unit comprising a housing (1), wherein a coaxial stationary iron core (3), a moving iron core (4), and a screw (2) are disposed within the housing (1), characterized in that: The screw (2) passes through the stationary iron core (3) from the stationary iron core (3) toward the moving iron core (4). A return spring (5) is provided between the stationary iron core (3) and the moving iron core (4). The return spring (5) is sleeved on the screw (2). A step is provided between the outer circular wall of the middle part of the screw (2) and the inner circular wall of the stationary iron core (3) to restrict the screw (2) from moving toward the moving iron core (4). The end of the screw (2) away from the moving iron core (4) abuts against the inner wall of the outer shell (1).

2. The screw connection structure of the trip unit according to claim 1, characterized in that: A first step (301) extending radially inward is provided on the inner circular wall of the stationary iron core (3). The screw (2) includes a rod body (201) and a second step (202) extending radially outward from the rod body (201). A connecting through hole (302) is provided on the first step (301). The connecting through hole (302) is coaxially arranged with the first step (301). The diameter of the connecting through hole (302) is smaller than the diameter of the second step (202). The rod body (201) passes through the connecting through hole (302). The second step (202) abuts against the radial end face of the first step (301) away from the moving iron core (4).

3. The screw connection structure of the trip unit according to claim 2, characterized in that: A limiting through hole (303) is formed from the radial end face of the first step (301) away from the moving iron core (4) to the radial end face of the stationary iron core (3) away from the moving iron core (4), and the second step (202) cooperates with the limiting through hole (303).

4. The screw connection structure of the trip unit according to claim 3, characterized in that: The second step (202) is clearance-fitted or interference-fitted with the limiting through hole (303).

5. The screw connection structure of the trip unit according to claim 2, characterized in that: The radial end face of the second step (202) away from the first step (301) abuts against the inner wall of the outer shell (1).

6. The screw connection structure of the trip unit according to claim 3, characterized in that: A first guide slope (305) is provided on the end face of the limiting through hole (303) away from the first step (301). The first guide slope (305) facilitates the rod (201) and the second step (202) to extend into the limiting through hole (303).

7. The screw connection structure of the trip unit according to claim 3, characterized in that: A second guide slope (203) is provided on the end face of the second step (202) facing the stationary iron core (3), and the second guide slope (203) facilitates the second step (202) to extend into the limiting through hole (303).

8. The screw connection structure of the trip unit according to claim 2, characterized in that: A first mounting hole (304) is formed from the radial end face of the first step (301) near the moving iron core (4) to the radial end face of the stationary iron core (3) near the moving iron core (4). A second mounting hole (401) that mates with the first mounting hole (304) is provided in the moving iron core (4). One end of the return spring (5) extends into the first mounting hole (304) and connects to the stationary iron core (3). The other end of the return spring (5) extends into the second mounting hole (401) and connects to the moving iron core (4). The return spring (5) is sleeved on the rod body (201).

9. The screw connection structure of the trip unit according to claim 8, characterized in that: A third guide slope (306) is provided on the side of the first mounting hole (304) facing the moving iron core (4), and the third guide slope (306) facilitates the insertion of the reset spring (5) into the first mounting hole (304).

10. An electricity meter, characterized in that: It includes the screw connection structure of the trip unit as described in any one of claims 1 to 9.

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