Sealing structure of wax motor thermal actuator

Abstract

A sealing structure for a wax motor thermal actuator includes an upper housing and a lower housing that can be spliced ​​together. The upper and lower housings, when spliced, form a wax motor mounting groove. A wax motor and contact plates abutting against both sides of the wax motor are disposed within the mounting groove. Symmetrical through-slots for the output shaft of the wax motor are provided on both the upper and lower housings. A sealing element with one end abutting against the through-slot is disposed within the wax motor mounting groove. Waterproof bosses are formed around the outer edges of the wax motor mounting groove after the upper and lower housings are spliced. The upper and lower housings are fixed together by welding or potting. The beneficial effect of this invention is that the synergistic effect of the waterproof bosses and the welding / potting process forms a continuous closed physical barrier layer around the wax motor mounting groove, effectively improving the overall sealing performance.

Description

Technical Field

[0001] This utility model relates to a sealing structure, and more particularly to a sealing structure for a wax motor thermal actuator. Background Technology

[0002] Wax motor actuators are widely used in temperature control systems. Their core principle is to utilize the thermal expansion and contraction properties of wax materials to drive mechanical components. In applications such as thermostatic valves in water heaters, cooling circulation systems in automobile engines, and HVAC damper adjustments, these actuators sense environmental changes through temperature-sensitive elements. When the temperature reaches a set threshold, the wax material undergoes a phase change and expands, pushing a piston rod to produce axial displacement, thereby opening or closing valves or switching contacts. For example, in storage-type water heaters, when the water temperature exceeds a safe value, the wax motor pushes a metal push rod to cut off the heating circuit. This process is characterized by fast response and high driving torque. Its structure typically includes a sealed housing, a wax column cavity, a return spring, and conductive contact plates. With its passive operating mechanism that requires no external power supply, it exhibits unique advantages in explosion-proof and energy-saving applications.

[0003] The reliability bottleneck of existing wax motor actuators mainly lies in the failure of the contact plates. Because the actuator operates in high-temperature and high-humidity environments for extended periods, moisture can easily penetrate the cavity when there are minute gaps in the housing's sealing structure or when the sealing material ages. This infiltrated moisture condenses under temperature cycling, causing oxidation on the copper contact plate surface, forming an insulating oxide layer, or triggering electrochemical corrosion under DC conditions. This phenomenon is particularly pronounced in coastal areas with high salt spray; abnormally increased contact resistance can cause circuit continuity issues, and in severe cases, complete contact erosion. Although some products employ plating protection, repeated mechanical friction can damage the protective layer, while strengthening the seal significantly increases structural complexity and production costs. This contradiction has become a key technical challenge restricting product lifespan. Utility Model Content

[0004] In view of the shortcomings of the prior art, this utility model provides a sealing structure for a wax motor thermal actuator that achieves a better sealing effect on the wax motor part in the actuator.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a sealing structure for a wax motor thermal actuator, comprising an upper housing and a lower housing that can be spliced ​​together. The upper housing and the lower housing are spliced ​​together to form a wax motor mounting groove. A wax motor and contact plates respectively abutting against both sides of the wax motor are disposed in the wax motor mounting groove. The upper housing and the lower housing are symmetrically provided with through grooves for the output shaft of the wax motor to extend out. A sealing element with one end abutting against the through groove is disposed in the wax motor mounting groove. After the upper housing and the lower housing are spliced ​​together, waterproof bosses are formed around the outer edge of the wax motor mounting groove. The upper housing and the lower housing are fixed together by welding or potting.

[0006] The beneficial effects of this invention are as follows: Through the synergistic effect of the waterproof boss and the welding / grouting process, a continuous closed physical barrier layer is formed around the wax motor mounting groove, effectively improving the overall sealing performance. The waterproof boss acts as a guide and positioner during assembly, ensuring precise alignment of the upper and lower housings. The sealing element forms an axial compression seal against the through groove, providing double protection with the external welding / grouting layer. As a preferred embodiment, the waterproof boss can be designed as a stepped interlocking structure, forming grooves filled with molten material during welding, which enhances structural strength and extends the moisture penetration path. Furthermore, the grouting process can use a low-viscosity epoxy resin material, which penetrates into the gaps of the boss through capillary action, forming a seamless composite sealing layer after curing. As another preferred method, the upper and lower shells are fixed together by ultrasonic welding. Ultrasonic welding achieves material fusion through high-frequency vibration and friction to generate heat. It has significant advantages in the sealing field: First, it is consumable-free and pollution-free, requiring no glue / solvent, which is environmentally friendly and reduces costs; second, it provides precise temperature control (only local melting), avoiding heat damage to sensitive components; and finally, the weld has high density and airtightness compared to traditional processes.

[0007] Furthermore, in addition to the end face with the through groove, the upper housing has a first waterproof protrusion at the outer edge of the other three end faces. The upper housing also has a second waterproof protrusion on the end face with the through groove along the inner and outer edges of the wax motor mounting groove, the end face close to the through groove, and the end face close to the seal. The lower housing has a corresponding waterproof embedded platform. The wax motor mounting groove is defined by the first waterproof protrusion, the second waterproof protrusion, and the waterproof embedded platform.

[0008] By employing a staggered arrangement of multiple bosses and inserts, a labyrinthine sealing structure with multiple detour paths is constructed, significantly increasing the resistance to moisture intrusion. The second waterproof boss forms reinforcing ribs at key stress points, enhancing the rigidity of the shell structure. As a preferred approach, the first waterproof boss can be designed with a continuous wavy profile, forming a multi-level staggered engagement with the serrated edges of the waterproof insert, with each level of staggering creating an airtight chamber structure. This design, without increasing the number of components, optimizes the geometry to force moisture to undergo multiple directional changes before passing through, significantly improving sealing reliability. As another preferred approach, the waterproof insert is fitted to the inner side of the first waterproof boss and is approximately the same height as the first waterproof boss, forming a labyrinthine channel after welding to prevent moisture intrusion. Furthermore, the wax motor mounting groove is provided with a sealing groove for placing the sealing element on the side near the through groove. The diameter of the sealing groove is larger than the diameter of the through groove. The second waterproof bosses are connected to form a T-shape. The part of the waterproof embedded platform corresponding to the second waterproof boss is inserted into the second waterproof boss.

[0009] The dimensions of the sealing groove are designed to provide pre-compression space for the seal, ensuring uniform deformation during assembly. The T-shaped boss structure forms a three-dimensional sealing surface, and its nesting fit with the inner platform can offset assembly stresses in different directions. As a preferred option, the lateral extension of the T-shaped boss can be designed as a beveled guide structure, which fits with the chamfer of the inner platform, facilitating assembly positioning and increasing the contact area.

[0010] Furthermore, a channel is formed between the second waterproof protrusion and the first waterproof protrusion for inserting a waterproof inner platform, the height of which is approximately equal to the height of the first waterproof protrusion.

[0011] The integrated waterproof recessed platform design eliminates the seam defects inherent in split structures, and the continuous, uninterrupted channel ensures the recessed platform forms a complete closed loop. The highly fitted design maintains uniform contact pressure on the mating surfaces of the upper and lower shells. As a preferred option, flow-guiding grooves can be provided on the inner wall of the channel to guide molten material to critical joint areas during welding. A wedge-shaped locking structure can be provided at the ends of the waterproof recessed platform to generate radial expansion force after assembly, enhancing interface adhesion.

[0012] Furthermore, the wax motor is provided with a waterproof cover on one side of the output shaft of the wax motor, and the inner diameter surface of the seal is tightly fitted on the outer peripheral surface of the waterproof cover. The waterproof cover extends from the wax motor toward the output shaft of the wax motor.

[0013] The waterproof cover and seals form a dynamic sealing interface, compensating for clearance changes caused by the output shaft's movement. The extended cover structure provides guiding protection for the output shaft. As a preferred option, the outer surface of the waterproof cover can be machined with spiral drainage grooves to generate a centrifugal drainage effect when the shaft rotates. The inner layer of the cover can be laminated with a hygroscopic material layer to actively absorb trace amounts of permeated moisture.

[0014] Furthermore, the inner diameter surface of the sealing groove is provided with a plurality of positioning grooves, and the outer peripheral surface of the sealing element is provided with positioning ribs that match the number of positioning grooves.

[0015] The interlocking convex-concave structure achieves precise circumferential positioning, preventing the seal from twisting or shifting. The meshing action of the convex ribs and grooves enhances the interfacial sealing pressure, thus ensuring that the waterproof cover fitted inside the seal does not move while maintaining the seal's position. As a preferred approach, the positioning grooves can be designed with an involute tooth pattern, causing the seal to self-tighten under pressure. Elastic barbs can be provided at the top of the ribs, generating a progressive biting force during assembly to ensure stable positioning of the seal.

[0016] Furthermore, the contact point is located at the center of the wax motor, and the contact point is provided with an elastic limiting member, through which the contact point abuts against the wax motor.

[0017] The central positioning design balances the forces at the front and rear ends, and the elastic limiting component can absorb dimensional changes caused by thermal expansion and contraction. As a preferred approach, the elastic limiting component can adopt a double-wave spring structure to provide graded elastic support in the axial direction. The surface of the spring can be coated with an insulating and wear-resistant coating to ensure conductivity and extend service life.

[0018] Furthermore, the wax motor mounting groove is also provided with abutting platform that forms abutting relationship with the end of the wax motor, and both ends of the abutting platform are provided with positioning bosses to prevent the end of the wax motor from shifting.

[0019] The end positioning mechanism and the front mid-section limiting structure form a three-point support system, ensuring the stability of the wax motor axis. This stability, combined with the stable wax motor axis, ensures the waterproof cover remains centered and does not shift during wax motor operation, achieving a good seal. The angled design of the positioning boss optimizes stress distribution. As a preferred method, a thermally conductive silicone pad can be placed on the abutment platform surface to cushion vibration and enhance heat conduction. The positioning boss incorporates a magnetic element that attracts the magnetic material of the wax motor housing, aiding in positioning.

[0020] Furthermore, the upper housing is provided with a pinhole for the electrode to pass through, and the end of the electrode located outside the pinhole is sealed by dispensing adhesive, and the dispensing area completely covers the pinhole position.

[0021] Dispensing sealant forms a chemical barrier independent of structural sealant, providing dual protection to ensure the reliability of electrical connections. The full-coverage design eliminates capillary penetration paths. As a preferred method, the dispensing process can employ a layered application of UV-curable adhesive, first filling pinhole gaps and then covering the surface. Conductive microparticles can be incorporated into the adhesive to enhance the electromagnetic interference resistance of the electrical contacts while maintaining insulation. Attached Figure Description

[0022] Figure 1 This is an internal view of an embodiment of the present utility model; Figure 2 This is an internal view of the upper and lower shells of an embodiment of the present invention; Figure 3 This is a partial enlarged view of the sealing groove on the upper shell of this utility model embodiment; Figure 4 This is a partial enlarged view of the sealing groove of the lower shell in an embodiment of this utility model; Figure 5 This is a top view of the upper housing of the present invention, in which a wax motor, a contact plate, and a seal are internally installed; Figure 6 This is a cross-sectional view of an embodiment of the present utility model; Figure 7 This is an isometric view of the electrical contact point in an embodiment of this utility model. Detailed Implementation

[0023] This utility model provides a sealing structure for a wax motor thermal actuator, such as... Figure 1-7 As shown: The device includes an upper housing 1 and a lower housing 2 that are joined together to form a mounting groove 4 for accommodating a wax motor 3. The mounting groove 4 contains the wax motor 3 and its two side contact plates 5. The contact plates 5 are in contact with the wax motor 3 via an elastic limiting member 51. The end of the wax motor 3 is supported by an abutment platform 41, which has positioning bosses 42 at both ends to prevent displacement.

[0024] The upper housing 1 and lower housing 2 have symmetrical through slots 6 for the output shaft 31 of the wax motor to pass through. A sealing slot 7, larger in diameter than the through slot 6, is provided near the mounting slot 4. A sealing element 71 is embedded in the sealing slot 7, and the inner wall of this sealing element fits tightly with the waterproof cover 32 at the front end of the wax motor 3. A positioning groove 72 is provided on the inner wall of the sealing slot 7, and a corresponding positioning rib 73 is provided on the outer wall of the sealing element 71 to form a snap-fit ​​connection.

[0025] The upper housing 1 has first waterproof protrusions 11 on three sides, and a T-shaped second waterproof protrusion 12 on the end face near the through groove 6. A waterproof embedded platform 21 is provided at a corresponding position on the lower housing 2, its height being flush with the first waterproof protrusions 11. A channel 13 is formed between the second waterproof protrusion 12 and the first waterproof protrusion 11, and the waterproof embedded platform 21 is inserted into this channel to form a labyrinth seal. The housing joints are fixed by welding or potting, and the pinhole 8 through which the contact piece 5 protrudes from the housing is completely sealed by applying adhesive 81.

[0026] When this structure is in operation, a triple sealing system works synergistically: the first layer is a basic seal formed by the welding of a waterproof boss with the shell; the second layer extends the moisture penetration path through a labyrinthine channel; and the third layer forms a dynamic seal between the seal 71 and the waterproof cover 32. The wax motor 3 is fixed at three points: the front-end seal 71, the middle elastic limiter 51, and the end positioning boss 42, ensuring the stability of the output shaft 31 and keeping the seal 71 in close contact with the waterproof cover 32 at all times. The adhesive seal at the contact point 5 and the multi-layer waterproof structure of the shell together block the intrusion of external moisture.

[0027] The above embodiments are merely one preferred embodiment of the present utility model. Ordinary changes and substitutions made by those skilled in the art within the scope of the present utility model's technical solution are all included within the protection scope of the present utility model.

Claims

1. A sealing structure for a wax motor thermal actuator, comprising an upper housing and a lower housing that can be spliced ​​together, wherein the upper housing and the lower housing are spliced ​​together to form a wax motor mounting groove, and a wax motor and contact plates respectively abutting against both sides of the wax motor are disposed in the wax motor mounting groove, characterized in that: The upper and lower housings are symmetrically provided with through slots for the output shaft of the wax motor to extend out. A sealing element with one end abutting against the through slot is provided in the wax motor mounting slot. After the upper and lower housings are spliced ​​together, waterproof protrusions are formed at the outer edges around the wax motor mounting slot. The upper and lower housings are fixed together by welding or glue injection.

2. The sealing structure of the wax motor thermal actuator according to claim 1, characterized in that: In addition to the end face with the through groove, the upper housing has a first waterproof protrusion at the outer edge of the other three end faces. The upper housing has a second waterproof protrusion on the end face with the through groove along the inner and outer edges of the wax motor mounting groove, the end face close to the through groove, and the end face close to the seal. The lower housing has a corresponding waterproof embedded platform. The wax motor mounting groove is defined by the first waterproof protrusion, the second waterproof protrusion, and the waterproof embedded platform.

3. The sealing structure of the wax motor thermal actuator according to claim 2, characterized in that: The wax motor mounting groove is provided with a sealing groove for placing the sealing element on the side near the through groove. The diameter of the sealing groove is larger than the diameter of the through groove. The second waterproof bosses are connected to form a T-shape. The part of the waterproof embedded platform corresponding to the second waterproof boss is inserted into the second waterproof boss.

4. The sealing structure of the wax motor thermal actuator according to claim 3, characterized in that: A channel is formed between the second waterproof boss and the first waterproof boss for inserting a waterproof inner platform, the height of which is approximately equal to the height of the first waterproof boss.

5. The sealing structure of the wax motor thermal actuator according to claim 3, characterized in that: The wax motor has a waterproof cover on one side of the output shaft. The inner diameter surface of the seal is tightly fitted to the outer circumferential surface of the waterproof cover. The waterproof cover extends from the wax motor toward the output shaft of the wax motor.

6. The sealing structure of the wax motor thermal actuator according to claim 5, characterized in that: The inner diameter surface of the sealing groove is provided with a number of positioning grooves, and the outer peripheral surface of the sealing element is provided with positioning ribs that match the number of positioning grooves.

7. The sealing structure of the wax motor thermal actuator according to claim 6, characterized in that: The contact plate is located at the middle of the wax motor and is provided with an elastic limiting member. The contact plate achieves contact with the wax motor through the elastic limiting member.

8. The sealing structure of the wax motor thermal actuator according to claim 7, characterized in that: The wax motor mounting slot is also provided with abutting platform that abuts against the end of the wax motor. Both ends of the abutting platform are provided with positioning bosses to prevent the end of the wax motor from shifting.

9. The sealing structure of the wax motor thermal actuator according to claim 1, characterized in that: The upper housing is provided with a pinhole for the electrode to pass through. The end of the electrode outside the pinhole is sealed by applying adhesive, and the adhesive area completely covers the pinhole.

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