Small-power air pressure switch

Abstract

A small-power air pressure switch comprises a shell, a trigger button is arranged on the shell, two wiring terminals which penetrate through the shell and are used for being connected with an external circuit are arranged in the shell, and a trigger assembly is further arranged in the shell. The trigger assembly is switched to be conducted with the two wiring terminals along with the up-and-down moving process of the trigger button, the trigger assembly comprises a support and a trigger piece, the support is provided with a moving groove for the trigger piece to be clamped in, the support is provided with a receding space at the moving groove, and the receding space is communicated with the trigger piece. And the triggering piece does not make contact with the support all the time in the moving process in the receding space. The beneficial effects of the utility model are that through the arrangement of the abdicating space, the trigger piece interacts with the support only through the contact fulcrum of the moving groove in the moving process, thereby effectively avoiding the multi-point collision between the trigger piece and the support in the traditional design, and obviously reducing the frictional resistance and the mechanical interference.

Description

Technical Field

[0001] The utility model relates to a micro switch, in particular to a small power air pressure switch. Background Art

[0002] In gas water heaters, low-power air pressure switches are widely used in safety monitoring systems. They are primarily used to monitor the exhaust fan's air pressure in real time, ensuring proper exhaust of smoke and preventing hazards such as carbon monoxide accumulation. Their operation involves the negative pressure generated by the fan starting up acting on the switch's elastic diaphragm or sensitive element. When the air pressure reaches a preset threshold (typically with a trigger force of only tens of grams), a trigger element (such as a microswitch or lever mechanism) rapidly actuates, controlling the opening or closing of the gas valve through a circuit signal. This mechanism plays a critical role in water heater operation, for example, by immediately shutting off the gas supply in the event of insufficient air pressure (such as a flue blockage) to ensure user safety. Due to the minimal trigger force, the switch design must be highly precise to sensitively respond to subtle pressure changes and avoid false triggering or delays.

[0003] However, existing low-power air pressure switches have significant drawbacks, primarily due to their minimal triggering force (typically only tens of grams). This requires an extremely sophisticated structural design for the trigger element. However, the trigger element of existing air pressure switches often utilizes a rigid connecting rod or spring compensation mechanism. During operation, this can easily lead to motion compensation due to component gaps, friction, or thermal expansion, resulting in accumulated compensatory displacement and, in turn, a jamming problem. This jamming not only reduces the switch's response speed and reliability but can also cause the switch to malfunction at critical moments, preventing accurate triggering of safety controls and increasing operational risks for the water heater. Structural optimization is urgently needed to eliminate this type of failure. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a low-power air pressure switch that is more smoothly triggered.

[0005] To achieve the above-mentioned purpose, the technical solution of the utility model is as follows: a small-power air pressure switch, comprising a shell, a trigger button is provided on the shell, two terminal blocks passing through the shell and used to connect to an external circuit are provided in the shell, a trigger assembly is also provided in the shell, and the trigger assembly switches the conduction between the two terminal blocks as the trigger button moves up and down, the trigger assembly comprises a bracket and a trigger member, a movable groove is provided on the bracket for the trigger member to be clamped therein, and a clearance space is provided in the movable groove of the bracket, and the trigger member will never contact the bracket during the movement in the clearance space.

[0006] The beneficial effect of the present invention is that by providing a clearance space, the trigger member interacts with the bracket only through the movable groove as a contact fulcrum during movement, effectively avoiding the multiple collisions between the trigger member and the bracket in traditional designs, thereby significantly reducing frictional resistance and mechanical interference. This improves the smoothness and reliability of the switch operation, prevents jamming caused by collisions, and extends the service life of the switch. At the same time, this design simplifies the assembly process, reduces manufacturing tolerance requirements, and improves production yield. As a preferred embodiment, the clearance space of the bracket can be achieved by machining a recessed area into the bracket body. This recessed area forms a cavity around the movable groove, ensuring that the movement trajectory of the trigger member is completely confined within the movable groove. The depth of the recess is slightly greater than the thickness of the trigger member, avoiding any lateral contact. For example, the bracket adopts a stamping process to provide symmetrical recesses on both sides of the movable groove to form a uniform clearance space. When the trigger member slides in the groove, its edge portion always floats in the recess, with only the groove wall providing guiding support. In this way, only single-point contact force is generated during the movement, avoiding wear and noise caused by multi-point friction, and further optimizing the response speed and accuracy of the switch.

[0007] Furthermore, the trigger member includes a resting piece, one end of the resting piece rests on the trigger button, and the other end is clamped in the movable groove. The bracket includes an arc-shaped giving portion, and the movable groove is arranged at the center of the giving portion. The giving space is located between the giving portion and one end of the resting piece clamped in the movable groove.

[0008] This technical solution ensures the effective formation of a clearance space through the coordination of the arc-shaped clearance portion and the abutment piece, thereby simplifying the bracket structure and reducing manufacturing costs. The arc-shaped design provides a natural space avoidance, reduces material usage, and optimizes the movement path of the trigger to avoid poor contact caused by offset. In addition, the location of the movable groove at the center ensures the symmetry and stability of the trigger movement, improving the triggering accuracy and repeatability of the switch. As a preferred method, the arc-shaped clearance portion of the bracket can be achieved through a single bending process, such as using a metal sheet to be bent at a specific radius to form a semicircular or U-shaped channel, and the movable groove is punched or milled at the bend apex, and the clearance space is naturally formed between the inner wall of the bend and the end of the abutment piece. This structure is not only easy to manufacture, but also ensures that the abutment piece always maintains a gap with the arc surface when moving, avoiding lateral friction, and further improving the durability and smoothness of the component. For example, the bending angle is controlled within the range of 90-120 degrees, the inner wall of the positioning part is smoothed, and the end of the abutment piece is designed with a rounded corner. The two work together to achieve interference-free sliding, optimizing the overall performance and assembly efficiency of the switch.

[0009] Furthermore, the end of the trigger button that contacts the abutment sheet is arranged in a plane, and the abutment sheet includes a bent portion, and the bent portion abuts against the trigger button.

[0010] This design, through point contact between the flat trigger button and the bent portion, ensures concentrated and evenly distributed contact force during the triggering process, reducing frictional and energy losses. This point contact mechanism avoids the sticking or uneven sliding that can occur with surface contact, improving the switch's responsiveness and consistent operation. Furthermore, the bent portion structure simplifies the manufacturing of the abutment plate, enhancing its rigidity and preventing functional failure due to deformation. Preferably, the bent portion can be designed with an acute angle or a small radius bend, forming a sharp or slightly convex contact point, while the flat end of the trigger button is polished to reduce the coefficient of friction. During operation, the tip of the bent portion maintains single-point pressure contact with the flat end of the button. The lever mechanism efficiently transmits the trigger button's displacement to the movable slot, ensuring full point contact without offset. For example, the bent portion is stamped from stainless steel, resulting in a contact point harder than the trigger button material. This maintains stable contact performance during repeated operation, avoiding stalling caused by accumulated wear and optimizing the switch's reliability and lifespan.

[0011] Furthermore, the trigger member also includes a contact piece, a card slot is provided on the abutting piece, one end of the contact piece is clamped in the card slot, and the other end is provided with moving contacts on both sides of the contact piece, and the wiring terminal is provided with a static contact corresponding to the moving contact; the contact piece is extended from the end where the moving contact is provided with a reset spring piece, and the other end of the bracket corresponding to the reset spring piece is provided with a reset groove for it to be clamped in.

[0012] This solution achieves a complete motion mechanism for the trigger assembly through the integrated design of the contact piece, slot, and reset spring, ensuring reliable switching and rapid reset. The slot secures the contact piece in place, preventing wobbling during movement, while the corresponding arrangement of the moving and stationary contacts ensures a stable circuit connection. The reset spring, in conjunction with the reset slot, provides an automatic return function, reducing the need for manual intervention. This improves the switch's dynamic response efficiency and electrical performance while simplifying the internal structure for easier maintenance. As a preferred approach, the contact piece's slot can be designed as a U-shaped opening or dovetail groove. Once inserted, one end of the contact piece locks in place through an interference fit or snap-on design, ensuring a secure connection. The reset spring is made of an elastic metal sheet (such as phosphor bronze) and extends in an L-shape or arc. Its free end is embedded in the reset slot, compressing to store energy during the triggering process and pushing the contact piece back into place when released. For example, during operation, the trigger button presses down against the contact piece, driving the contact piece to move, causing the moving contact to separate or contact the stationary contact. The reset spring deforms within the reset groove, storing elastic potential energy. When the external force is removed, the spring expands, pushing the contact piece back to its original position. This makes the entire movement process smooth and controllable, avoiding hysteresis or false operation, and optimizing the safety and durability of the switch.

[0013] Furthermore, the movable contact and the stationary contact are both provided with a conical contact portion with an arc-shaped tip. The movable contact and the stationary contact are in contact through the two conical contact portions, and the cross section of the two conical contact portions is cross-shaped after the tips thereof are in contact.

[0014] The cross-shaped contact tip of the tapered contact portion significantly reduces the surface area between the contacts, effectively reducing oxide layer buildup and contact resistance, thereby improving electrical continuity reliability and switch life. The cross-shaped contact ensures concentrated contact pressure, enhances vibration and shock resistance, and reduces the risk of arcing. This design also simplifies contact manufacturing and improves overall performance consistency. Preferably, the tapered contact portion can be designed with a conical or pyramidal tip. During assembly, the moving and stationary contacts are aligned to ensure that the tips form an orthogonal cross when in contact (e.g., along the X or Y axis). In terms of operation, when the moving contact moves, its cone tip presses perpendicularly against the cone tip of the stationary contact, minimizing the point contact area and piercing the oxide film under high pressure. After contact, the cross-shaped cross-section minimizes the current path and reduces heat accumulation. For example, the contact material is a silver alloy with a gold-plated surface for oxidation protection. This maintains low resistance even during frequent operation, avoids the carbon deposit problem associated with traditional surface contacts, and optimizes the switch's electrical stability and response speed.

[0015] Furthermore, an anti-falling inclined surface is provided at the upper end of the reset groove for preventing the reset spring from falling out of the reset groove.

[0016] The anti-slip bevel effectively prevents the reset spring from falling out of the reset slot during movement or vibration, ensuring stable reset of the trigger assembly and improving the reliability and safety of the switch. The bevel allows for smooth insertion of the spring while restricting its reverse escape, reducing assembly and maintenance difficulties while also preventing mechanical failure or electrical interruption caused by escape. As a preferred approach, the anti-slip bevel can be designed as a barbed hook or ramp structure with an angle (e.g., 30-45 degrees) located at the upper edge of the reset slot opening; the end of the reset spring is provided with a matching protrusion or bend. During operation, when the reset spring is compressed, its end slides along the bevel to the bottom of the slot. When the spring expands and resets, the bevel blocks its upward movement, allowing only lateral or axial displacement. For example, the bevel can be stamped or injection molded onto the bracket, with a smooth surface to reduce friction. The end of the spring is bent into a hook shape to engage with the bevel. This way, the spring remains in the groove during repeated switch operations, ensuring consistent reset force, avoiding performance degradation caused by accidental dislocation, and optimizing the durability and overall functionality of the component.

[0017] Furthermore, the terminal block is provided with two snap-fitting protrusions, one of which rests on the outer surface of the shell, and the other is located inside the shell and rests on the shell, and the two snap-fitting protrusions cooperate to form a stable connection between the terminal block and the shell.

[0018] This design achieves dual securing of the terminal to the housing through the cooperation of internal and external snap-in projections, enhancing the mechanical strength and stability of the connection and preventing electrical failures caused by loosening or falling terminals. The internal projection provides tensile strength, while the external projection resists push-in forces, ensuring the terminal remains in place despite vibration and external impact, thereby improving the safety and lifespan of the switch. It also simplifies the assembly process and reduces the need for additional fasteners. Preferably, the snap-in projections can be designed as hemispherical or trapezoidal protrusions, located in the middle and end of the terminal shaft, respectively. The internal projection has a diameter slightly larger than the housing hole and snaps into place through an interference fit, while the external projection abuts against the housing surface to form a retaining force. During assembly, the terminal is inserted into the housing hole, and the internal projection elastically deforms to engage the inner wall, while the external projection conforms to the outer surface, forming a self-locking structure. For example, the terminal can be made of copper alloy, with the projections stamped and formed. The housing can also be provided with grooves or flat surfaces at corresponding locations to ensure uniform force distribution on the projections. This allows the terminal to withstand significant pull-out forces without shifting during wiring, preventing poor contact and optimizing the electrical performance and mechanical reliability of the switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 An internal view of an embodiment of the present invention;

[0020] Figure 2 This is a partial enlarged view of the space provided in the embodiment of the utility model;

[0021] Figure 3 This is a partial enlarged view of the contact point of the embodiment of the utility model;

[0022] Figure 4 This is a partial enlarged view of the bending portion of an embodiment of the present utility model;

[0023] Figure 5 This is a partial enlarged view of the clamping protrusion of the embodiment of the present utility model. DETAILED DESCRIPTION

[0024] The utility model embodiment of a small power air pressure switch such as Figure 1-5 The figure shows a shell 1, which serves as a basic structure for accommodating internal components. A trigger button 2 is provided on the shell 1, which can move up and down in the vertical direction in response to changes in external air pressure. Two wiring terminals 3 are fixedly installed in the shell 1, and the wiring terminals 3 extend from the shell 1 and are used to connect to an external circuit to achieve a current conduction function. A trigger component 4 is also provided in the shell 1, and the trigger component 4 is used to switch the conduction state between the two wiring terminals 3 during the up and down movement of the trigger button 2.

[0025] The trigger assembly 4 includes a bracket 41 and a trigger member 42. The bracket 41 is connected to the interior of the housing 1 via a fixed point. A movable groove 411 is provided on the bracket 41. The trigger member 42 is locked in the movable groove 411 and can slide along the groove. The bracket 41 forms a clearance space 412 at the movable groove 411. The clearance space 412 ensures that the trigger member 42 does not contact other parts of the bracket 41 during movement, thereby avoiding movement jams. The bracket 41 includes an arc-shaped clearance portion 413. The movable groove 411 is located at the center of the clearance portion 413. The clearance space 412 is arranged between the clearance portion 413 and the end of the trigger member 42 that is locked in the movable groove 411. The clearance space 412 can be achieved by simply bending the bracket 41. The trigger member 42 includes a support plate 421, one end of which rests against the lower end of the trigger button 2 and the other end snaps into the movable groove 411. The end of the trigger button 2 that contacts the support plate 421 is flat, and the support plate 421 is provided with a bent portion 422, which rests against the flat surface of the trigger button 2 in a point-contact manner, ensuring smooth movement. The trigger member 42 also includes a contact plate 423, the support plate 421 having a slot 424 defined therein. One end of the contact plate 423 is snapped into the slot 424, and the other end is provided with movable contacts 425 on both sides. The stationary contact 31 is mounted on the terminal 3 at the position corresponding to the movable contact 425, which is used to form a circuit path when contact is made. A reset spring 426 extends from one end of the contact piece 423, which is provided with the movable contact 425. A reset groove 414 is defined on the other end of the bracket 41, corresponding to the reset spring 426. The tip of the reset spring 426 is locked within the reset groove 414. A preventive slope 415 is formed at the upper end of the reset groove 414 to prevent the reset spring 426 from being dislodged. Both the movable contact 425 and the stationary contact 31 are provided with tapered contact portions 4251 and 311, respectively, with curved tips. When the movable contact 425 makes contact with the stationary contact 31, the tips of the two tapered contact portions 4251 and 311 contact each other, forming a cross-shaped cross-section to reduce the contact surface area and oxide layer buildup. A snap-fit protrusion 32 is provided on the terminal 3. The snap-fit protrusion 32 includes two protrusions, one of which rests against the outer surface of the shell 1, and the other protrusion is located inside the shell 1 and rests against the inner wall of the shell 1. The two protrusions cooperate to form a stable connection to prevent the terminal 3 from loosening.

[0026] The operating principle of this small-power pneumatic switch is as follows: When external air pressure acts on trigger button 2, trigger button 2 moves downward, driving the bent portion 422 of the abutment piece 421 to slide in a point-contact manner. The abutment piece 421 moves within the movable groove 411. Due to the presence of the clearance space 412, the trigger member 42 only contacts the bracket 41 through the movable groove 411 during movement, avoiding collisions and jams. The movement of the abutment piece 421 drives the contact piece 423 through the locking groove 424, causing the moving contact 425 to approach the static contact 31. When the two tapered contact portions 4251 and the tips of 311 come into contact to form a cross-shaped cross section, the circuit is connected, and current is connected to the external circuit through the terminal 3. When the air pressure decreases, trigger button 2 moves upward, and reset spring 426 provides an elastic reset force within reset groove 414, pushing contact piece 423 back to its original position. Moving contact 425 separates from stationary contact 31, disconnecting the circuit. The anti-slip slope 415 of reset groove 414 prevents reset spring 426 from falling out. Throughout this process, the engaging protrusion 32 keeps terminal 3 securely installed.

[0027] The above embodiment is only one preferred embodiment of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A small-power pneumatic pressure switch, comprising a housing, a trigger button disposed on the housing, two terminals disposed within the housing and extending therethrough for connection to an external circuit, and a trigger assembly disposed within the housing, the trigger assembly switching conduction between the two terminals as the trigger button moves up and down, characterized in that: The trigger assembly includes a bracket and a trigger member. The bracket is provided with a moving groove for the trigger member to be clamped therein. The bracket is provided with a clearance space at the moving groove. The trigger member will never contact the bracket during the movement in the clearance space.

2. The low-power air pressure switch according to claim 1, characterized in that: The trigger member includes a resting piece, one end of the resting piece rests on the trigger button, and the other end is clamped in the movable groove. The bracket includes an arc-shaped giving part, and the movable groove is arranged at the center of the giving part. The giving space is located between the giving part and one end of the resting piece clamped in the movable groove.

3. The low-power air pressure switch according to claim 2, characterized in that: The end of the trigger button that contacts the abutment sheet is arranged in a plane. The abutment sheet includes a bent portion, and the bent portion abuts against the trigger button.

4. The low-power air pressure switch according to claim 2, characterized in that: The trigger member also includes a contact piece, a card slot is provided on the abutting piece, one end of the contact piece is clamped in the card slot, and the other end is provided with moving contacts on both sides of the contact piece, and the wiring terminal is provided with a static contact corresponding to the moving contact; the contact piece is extended from the end provided with the moving contact to provide a reset spring piece, and the other end of the bracket corresponding to the reset spring piece is provided with a reset groove for it to be clamped therein.

5. The low-power air pressure switch according to claim 4, characterized in that: The movable contact and the stationary contact are both provided with a conical contact portion with an arc-shaped tip. The movable contact and the stationary contact are in contact through the two conical contact portions, and the cross section of the two conical contact portions is cross-shaped after the tips thereof are in contact.

6. The low-power air pressure switch according to claim 4, characterized in that: The upper end of the reset groove is provided with an anti-slip inclined surface for preventing the reset spring from escaping from the reset groove.

7. The low-power air pressure switch according to claim 1, characterized in that: The connection terminal is provided with two snap-fitting protrusions, one of which abuts against the outer surface of the shell, and the other is located inside the shell and abuts against the shell. The two snap-fitting protrusions cooperate to form a stable connection between the connection terminal and the shell.

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