State maintaining travel switch

Abstract

The utility model provides a state keeping travel switch, which comprises a shell, an arrowhead-shaped trigger pin, a sliding contact with a hemispherical head, a sliding guide sleeve and a contact spring. The sliding contact and the sliding guide sleeve are conductive, and the shell and the trigger pin are non-conductive when the sliding contact and the sliding guide sleeve are connected into a circuit. In an initial state, the trigger pin extends out of the guide hole of the shell, the sliding contacts on the two sides are in contact and are pressed by the contact spring, and a circuit is kept to be conducted; when the upper end of the trigger pin bears a load, the trigger pin slides downwards and contracts into the shell, the sliding contacts on the two sides are separated, and the circuit is disconnected. The arrowhead part of the trigger pin and the hemispherical head part of the sliding contact are mutually clamped, so that the trigger pin is kept at a retraction position, and the travel switch is stabilized in an open-circuit state. When reset is needed, the reset tool is inserted from the reset hole of the shell to jack up the trigger pin, the sliding contacts on the two sides make contact again, and the circuit recovers the conducting state. The device is simple in structure, light in weight, low in clamping stagnation risk and high in working reliability, and has a state keeping function.

Description

Technical Field

[0001] This utility model relates to the field of limit switch technology, and in particular to a limit switch capable of maintaining a state. Background Technology

[0002] In mechanical engineering, especially in the aerospace and aviation fields, there are many separable mechanisms. These mechanisms are connected or retracted to other equipment in one state, and need to be separated or deployed under certain conditions or at certain times. Examples include the separation of a satellite from a launch vehicle, the separation of solar panels from a spacecraft, the retraction and extension of aircraft landing gear, and the deployment and dismantling of a jettisonable black box. Limit switches are commonly used components in the separation / deployment process. Their function is to monitor the position status of the separation mechanism and output a position signal of the separation mechanism based on the on / off state of the control circuit, so that the control system or operator can make a precise selection of the next working direction. Limit switches, whether for aerospace or aviation use, must meet two requirements: first, they must be small in size and light in weight, suitable for confined space environments; second, they must have high reliability and be able to accurately output signals to the control system indicating whether the separation process is complete or whether the deployment mechanism is in position.

[0003] Patent CN115424880B discloses a limit switch (see...) Figure 6 When the limit switch is connected to the device under test, the load causes the trigger pin 2 to move downward, the limit switch is in a compressed state, the top of the trigger pin 2 is limited by the device under test, and the trigger pin 2 is pressed into the longitudinal stepped cylindrical cavity of the housing 3. The conical tip at its lower end separates the left and right sliding contacts 5, and the circuit is broken. When the device under test moves and removes the load from the top of the trigger pin 2, the restoring force of the reset spring 4 drives the trigger pin 2 to move upward, the sliding contact 5 loses its inner limit, and is pressed towards the middle by the contact spring 8 so that the left and right sliding contacts 5 contact each other, and the circuit is connected.

[0004] The limit switch of this invention is lightweight, with point contact between the sliding contact and the trigger pin, resulting in a low risk of jamming. It features two symmetrically arranged sliding contacts with a large working stroke; operation of either contact assembly will automatically eject the sliding contact to its designated position, connecting the circuit and ensuring high reliability. However, the free state of this limit switch is the conducting state. Once the load on the trigger pin is removed, the trigger pin automatically resets and moves upward, meaning the circuit cannot remain in an open state (i.e., an open circuit). Therefore, it is not suitable for applications requiring a continuous open circuit output. Summary of the Invention

[0005] The technical problem to be solved by this utility model is to provide a limit switch with higher reliability and lighter weight, while also being able to maintain the open circuit state.

[0006] The technical solution adopted by this utility model to solve the above-mentioned technical problems is: a state-holding limit switch, including a housing, a trigger pin and a contact assembly.

[0007] The housing is a cavity component, with cavity structures arranged in both the transverse and longitudinal directions, and the two cavities are orthogonally connected. The transverse cavity is a stepped cylindrical cavity used to accommodate the transverse movement of the contact assembly; the longitudinal cavity is divided into upper and lower sections by the transverse cavity, with the upper section being a guide hole for accommodating the vertical sliding of the trigger pin, and the lower section being a reset hole for inserting a reset fixture to reset the trigger pin.

[0008] The trigger pin is arrow-shaped with a conical head and a reverse conical surface at the top. In the ON state, the reverse conical surface is limited by a limiting structure on the housing, preventing the trigger pin from dislodging upwards. In the OFF state, the arrow and sliding contact engage, keeping the trigger pin in the retracted position, thus stabilizing the limit switch in the open circuit state. When the trigger pin slides downwards into the stepped cylindrical cavity of the housing, it separates the left and right sliding contacts.

[0009] The contact assembly consists of two identical, symmetrically arranged sets, one on the left and one on the right. Each side of the contact assembly comprises a sliding guide sleeve, a sliding contact, and a contact spring. The sliding guide sleeve is a cylindrical structure with a handle and uniform inner diameter, while the sliding contact is a cylindrical structure with a hemispherical head. The sliding guide sleeve is fixed in a transverse stepped cylindrical cavity, allowing the sliding contact to slide freely within the sliding guide sleeve while maintaining contact. A wire is connected to the handle of the sliding guide sleeve, thus connecting the sliding contact and the sliding guide sleeve to the circuit. The contact spring is a compression spring, with one end supported inside the sliding contact and the other end supported inside the sliding guide sleeve, providing driving force for the transverse movement of the sliding contact.

[0010] The sliding guide sleeve and sliding contact are conductive, while the housing and trigger pin are not conductive.

[0011] In the initial state, the trigger pin extends from the guide hole of the housing, and the sliding contacts on both sides are in contact and pressed by the contact spring, thus conducting the circuit. When the trigger pin is subjected to a load, the trigger pin slides down and retracts into the housing, separating the sliding contacts on both sides and breaking the circuit. Because the arrowhead of the trigger pin head and the hemispherical head of the sliding contact interlock, the trigger pin remains in the retracted position, thereby keeping the limit switch in the open circuit state.

[0012] Furthermore, the housing is also equipped with a connection structure for connecting to the device under test.

[0013] Furthermore, the limiting structure at the lower end of the guide hole to prevent the trigger pin from slipping is a limiting cone surface, which matches the reverse cone surface of the trigger pin.

[0014] Furthermore, the cylindrical structures of the sliding guide sleeve and the sliding contact have openings facing each other and are slidably fitted, resulting in low friction. One end of the contact spring is supported inside the cylindrical portion of the sliding contact, and the other end is supported inside the cylindrical portion of the sliding guide sleeve.

[0015] Furthermore, the outer wall of the cylindrical portion of the sliding guide sleeve is stepped, which cooperates with the step of the transverse stepped cylindrical cavity of the shell to provide lateral positioning for the sliding guide sleeve.

[0016] Furthermore, the connection between the sliding guide sleeve and the housing can be achieved by bonding, threaded connection, or welding.

[0017] Furthermore, when the sliding guide sleeve is fixed to the housing by adhesive bonding, after the contact assembly is assembled in the transverse stepped cylindrical cavity, potting compound is injected into both ends of the cavity. The potting compound is allowed to cure and form an insulating plug, thereby fixing the sliding guide sleeve in the transverse stepped cylindrical cavity of the housing and providing lateral limit for the contact spring.

[0018] Furthermore, the transverse stepped cylindrical cavity is provided with multiple annular grooves at both ends. When the potting compound is poured, the compound flows into the annular grooves and forms an insulating plug with an embedded structure after curing. Such an insulating plug can not only protect the reliable connection of the solder joints connecting the wire and the sliding sleeve, but also ensure the firm connection between the sliding sleeve and the housing.

[0019] Furthermore, the lateral travel of the sliding contact is greater than the diameter of the lower end of the trigger pin, so that the circuit can be turned on when either side of the contact assembly is working.

[0020] Furthermore, the hemispherical head of the sliding contact is located inside the housing, and its contact with the trigger pin is a point contact, which helps to reduce the friction between the two, prevent jamming during operation, and improve the working reliability of the limit switch.

[0021] Furthermore, the inner surface of the cylindrical part of the sliding guide sleeve, the surface of the trigger pin, and the outer surface of the sliding contact are all smooth surfaces with low friction, which makes the movement of the sliding contact and the trigger pin smoother.

[0022] Furthermore, the arrowhead portion of the trigger pin, both at its largest diameter and at the tip of the arrow, features a rounded transition to ensure minimal resistance, low risk of jamming, and smoother sliding when the trigger pin moves up and down.

[0023] Furthermore, the sliding contact and sliding guide sleeve are made of conductive materials such as metal, while the remaining parts are made of non-metals with low density such as various polymers, such as polyimide, polysulfone, polyetheretherketone, etc.

[0024] Furthermore, the insertion part of the reset tool is preferably made of a non-metallic material with a hardness lower than that of the trigger pin, so as to avoid scratching the head of the trigger pin and the hemispherical head of the sliding contact.

[0025] This utility model has the advantages of simple structure, light weight, low risk of jamming, and high reliability. Compared with the existing limit switches, it also has a state holding function. It adopts an arrow-shaped trigger pin. Once an external force is applied to press the trigger pin into the housing, the arrow part of the trigger pin will be stuck between the hemispherical heads of the sliding contacts on both sides. The trigger pin and the sliding contacts limit each other, so that the limit switch is stably kept in the open circuit state. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of the limit switch of this utility model in the on state;

[0027] Figure 2 This is a cross-sectional view of the limit switch of this utility model in the open circuit state;

[0028] Figure 3 This is a schematic diagram of the trigger pin structure of this utility model;

[0029] Figure 4 This is a schematic diagram of the shell structure of this utility model;

[0030] Figure 5 This is a schematic diagram of the reset operation of this utility model;

[0031] Figure 6 This is a schematic diagram of the existing technology. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] This utility model provides a state-holding limit switch. Figure 1 , 2 The schematic diagrams of the limit switch of this utility model in the conducting state and the open-circuit state are given respectively. It mainly includes a trigger pin 1, a housing 2, a sliding guide sleeve 3, a sliding contact 4, a contact spring 5, an insulating plug 6, and a wire 7.

[0034] Trigger pin 1 is arrow-shaped in general, and its specific structure is as follows: Figure 3 As shown, the head of the arrow is tapered, with a preferred angle of 80° to 100°. The upper part of the tapered head has a reverse tapered surface 101, which, in the conductive state, engages with the limiting structure on the housing 2 to prevent the trigger pin 1 from dislodging upwards; and in the reset state after circuit breaking, it is used to open the sliding contacts 4 on both sides. The largest diameter part of the arrowhead has a rounded transition 102, and the tip of the arrowhead has a rounded head 103 to ensure smooth sliding of the trigger pin 1.

[0035] The specific structure of shell 2 is as follows Figure 4As shown, it has through-cavity structures in both the horizontal and vertical directions, with the two cavities orthogonally connected. The upper part of the vertical direction has a guide hole 201 for accommodating the vertical sliding of the trigger pin 1; the lower end of the guide hole 201 has a limiting cone surface 202 to prevent the trigger pin 1 from slipping upwards out of the guide hole 201; the lower part of the vertical direction has a reset hole 204 for inserting a reset rod to reset the trigger pin 1. The horizontal direction has a stepped cylindrical cavity 203 for accommodating the lateral movement of the contact assembly. Multiple annular grooves 205 are provided on the side walls at both ends of the stepped cylindrical cavity 203 for forming an inlay structure after glue filling.

[0036] The contact assembly comprises two identical, symmetrically arranged sets, each consisting of a sliding guide sleeve 3, a sliding contact 4, and a contact spring 5. The sliding guide sleeve 3 is a cylindrical structure with a handle, and the sliding contact 4 is a cylindrical structure with a hemispherical head. The inner wall of the cylindrical portion of the sliding guide sleeve 3 is smooth and slides in contact with the outer surface of the sliding contact 4. When the sliding contact 4 slides within the sliding guide sleeve 3, the two remain in contact with minimal friction. The outer side of the cylindrical portion of the sliding guide sleeve 3 has a stepped structure, which engages with the stepped cylindrical cavity 203 of the housing 2. The contact spring 5 is a compression spring, with one end supported within the sliding contact 4 and the other end supported within the sliding guide sleeve 3, providing driving force for the lateral movement of the sliding contact 4. The handle of the sliding guide sleeve 3 is connected to a wire 7, thereby connecting the sliding contact 4 and the sliding guide sleeve 3 to the circuit. After assembly, potting compound is injected between the sliding guide sleeve 3 and the housing 2. The potting compound flows into the annular groove 205. After injection, it is left to stand and cure to form an insulating plug 6 with an embedded structure. The insulating plug 6 is reliably connected to the housing 2, thereby fixing the sliding guide sleeve 3 in the stepped cylindrical cavity 203 of the housing 2, providing lateral limit for the contact spring 5, and also protecting the reliable connection of the solder joint at the end of the wire 7 and the sliding guide sleeve 3.

[0037] The working process of this utility model is as follows: In the initial state, the trigger pin 1 extends out from the guide hole 201 of the housing 2, and the sliding contacts 4 on both sides are in contact and pressed by the contact spring 5, and the circuit remains in the conducting state; when the trigger pin 1 bears a load, the trigger pin 1 slides down and retracts into the housing 2, separating the sliding contacts 4 on both sides, and the circuit is broken; since the trigger pin 1 and the sliding contacts 4 are mutually locked, the trigger pin 1 remains in the retracted position, so the limit switch remains in the open circuit state.

[0038] When it is necessary to restore the conduction state, such as Figure 5 As shown, the tool is inserted into the reset hole 204 to push the trigger pin 1 upward. The reverse conical surface 101 of the trigger pin 1 pushes the two sliding contacts 4 open. When the trigger pin 1 moves to the point where the reverse conical surface 101 contacts the limiting conical surface 202, the reset tool is pulled out. The sliding contacts 4 on both sides re-contact under the restoring force of the contact spring 5, the circuit is turned on, and the switch enters the on state.

[0039] In addition, the working stroke of the contact spring 5 of this utility model is large enough so that the lateral stroke of the sliding contact 4 on one side is greater than the diameter of the lower end of the trigger pin 1. This design can ensure that even if the sliding contact 4 on one side is stuck, the sliding contact 4 on the other side can pop out into place, ensuring that the sliding contacts 4 on both sides are in contact, thereby making the circuit reliably conductive.

[0040] It should be noted that the above descriptions of orientation, such as up, down, inside, outside, left, right, etc., are based on the directions and positional relationships shown in the attached drawings and are only for ease of description, and do not indicate or imply that the parts involved must have a specific orientation, structure or operation.

[0041] The techniques not described in detail in this utility model are well-known in the art. The above description is merely an embodiment of this utility model and is not intended to limit this utility model in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the principles and technical essence of this utility model shall still fall within the scope of this utility model's technical solution.

Claims

1. A state-holding limit switch, comprising a housing (2), a trigger pin (1), and a contact assembly, characterized in that, The housing (2) is a cavity component, which has cavity structures in the transverse and longitudinal directions respectively, and the two cavities are orthogonally connected; the transverse cavity is a stepped cylindrical cavity (203) used to accommodate the transverse movement of the contact assembly; the longitudinal cavity is divided into upper and lower sections by the transverse cavity, and the upper part is a guide hole (201) used to accommodate the vertical sliding of the trigger pin (1). The trigger pin (1) is arrow-shaped in general, with a conical head at the tip and an inverted conical surface (101) at the top. When in the conducting state, the inverted conical surface (101) is limited by the limiting conical surface (202) on the housing (2) and will not come out upward. When in the open state, the arrow and the sliding contact (4) are locked together, keeping the trigger pin (1) in the retracted position and the limit switch stable in the open state. When the trigger pin (1) slides downward and inserts into the stepped cylindrical cavity (203) of the housing (2), it can separate the left and right sliding contacts (4). The contact assembly has two sets, left and right, with the same structure and symmetrical arrangement. They are respectively composed of a sliding guide sleeve (3), a sliding contact (4), and a contact spring (5). The sliding guide sleeve (3) is a cylindrical structure with a handle and equal inner diameter. The sliding contact (4) is a cylindrical structure with a hemispherical head. The sliding guide sleeve (3) is fixed in the stepped cylindrical cavity (203). The sliding contact (4) can slide freely inside the sliding guide sleeve (3) and maintain contact. The handle of the sliding guide sleeve (3) is connected to a wire so that the sliding contact (4) and the sliding guide sleeve (3) are connected to the circuit. The contact spring (5) is a compression spring. One end is supported in the sliding contact (4) and the other end is supported in the sliding guide sleeve (3), providing driving force for the lateral movement of the sliding contact (4). The sliding guide sleeve (3) and the sliding contact (4) are conductive, while the housing (2) and the trigger pin (1) are not conductive. In the initial state, the trigger pin (1) extends out from the guide hole of the housing (2), and the sliding contacts (4) on both sides contact and are pressed by the contact spring (5), and the circuit is connected; when the trigger pin (1) bears a load, the trigger pin (1) slides down and retracts into the housing (2), separating the sliding contacts (4) on both sides, and the circuit is disconnected; since the arrow part of the trigger pin (1) and the hemispherical head of the sliding contact (4) are mutually locked, the trigger pin (1) remains in the retracted position, so the switch remains in the open circuit state.

2. The state-holding limit switch according to claim 1, characterized in that, The cylindrical structure of the sliding guide sleeve (3) and the cylindrical structure of the sliding contact (4) are assembled with their opening directions facing each other to form a cavity for accommodating the contact spring (5).

3. The state-holding limit switch according to claim 1, characterized in that, The outer wall of the cylindrical part of the sliding guide sleeve (3) is stepped, which cooperates with the step of the transverse stepped cylindrical cavity of the shell (2) to provide transverse positioning for the sliding guide sleeve (3).

4. The state-holding limit switch according to claim 1, characterized in that, The connection between the sliding guide sleeve (3) and the housing (2) can be achieved by bonding, threaded connection or welding.

5. The state-holding limit switch according to claim 4, characterized in that, When the sliding guide sleeve (3) is connected to the housing (2) by adhesive bonding, after the contact assembly is assembled in the stepped cylindrical cavity (203), potting compound is injected into both ends of the cavity. The potting compound is allowed to stand and cure to form an insulating plug (6), thereby fixing the sliding guide sleeve (3) in the stepped cylindrical cavity (203) of the housing.

6. The state-holding limit switch according to claim 5, characterized in that, The stepped cylindrical cavity (203) is also provided with multiple annular grooves (205) at both ends. The potting compound flows into the annular grooves (205) and, after curing, forms an insulating plug (6) with an inlaid structure, making the connection between the sliding guide sleeve (3) and the shell (2) more secure.

7. The state-holding limit switch according to any one of claims 1 to 6, characterized in that, The lateral travel of the sliding contact (4) is greater than the diameter of the lower end of the trigger pin (1). When the contact assembly on either side is working, the circuit can be turned on.

8. The state-holding limit switch according to any one of claims 1 to 6, characterized in that, The arrowhead portion of the trigger pin (1) has a rounded transition at its largest diameter and at the tip of the arrowhead to ensure that the trigger pin (1) moves up and down with low resistance, low risk of jamming, and smoother sliding.

9. The state-holding limit switch according to any one of claims 1 to 6, characterized in that, The lower longitudinal part of the housing (2) is provided with a reset hole (204) for inserting a reset tool to perform a reset operation on the trigger pin (1).

10. The state-holding limit switch according to claim 9, characterized in that, The insertion part of the reset fixture is made of a non-metallic material with a hardness lower than that of the trigger pin (1) to avoid scratching the head of the trigger pin (1) and the hemispherical head of the sliding contact (4).

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