Contact system of dual-power change-over switch

Abstract

The invention relates to the technical field of dual-power change-over switches, in particular to a contact system of a dual-power change-over switch, which comprises two wire inlet end static contacts, a load end static contact and a moving contact group, and is characterized in that the moving contact group comprises a moving contact bracket, two moving contacts, two independent contact springs and two independent spring brackets; two sides of the moving contact support are provided with through holes for axial sliding of the moving contact, and are provided with two independent installation cavities. Each spring support and one corresponding contact spring are jointly accommodated in one corresponding installation cavity, one end of each contact spring abuts against the corresponding spring support, the other end of each contact spring abuts against the inner side end face of one corresponding moving contact, and therefore two independent elastic pressure units are formed. The pressure spring is used for providing pressure between the moving contact and the static contact, so that the processing error of the spring can be effectively controlled, and burnout accidents caused by over-high temperature rise of the switch contact are avoided.

Description

Technical Field

[0001] This invention relates to the field of dual power transfer switch technology, and more particularly to a contact system for a dual power transfer switch. Background Technology

[0002] Dual power transfer switches are widely used terminal electrical appliances. They mainly control the operation of the contact system through an operating mechanism to connect or disconnect the main power supply and the backup power supply, thereby ensuring the safety of the power system and the continuity of production.

[0003] Currently, commonly used dual-power transfer switches mainly consist of a housing, contact system, switching mechanism, and manual / automatic operation mechanism. The contact system is the mechanism directly connected to the power supply in the transfer switch. Contacts in the contact system are classified into moving contacts and stationary contacts based on whether they move, and into finger-type snap-fit ​​and knife-type insertion types based on their engagement method. Knife-type insertion contacts are widely used in low-voltage switchgear. Their stationary contacts consist of multiple trapezoidal contact fingers, and the moving contact is a circular conductive rod, maintained by spring pressure. Insufficient contact pressure can lead to excessive temperature rise, or even contact burnout, causing switchgear failure. To ensure reliable dynamic and thermal stability, the contact pressure must be increased. However, excessive contact pressure increases the operating force, causing inconvenience to the user. Furthermore, most existing older structures use leaf springs, whose manufacturing process significantly affects the spring force parameters, resulting in large tolerances that are difficult to control, negatively impacting the product's normal operation and lifespan. Summary of the Invention

[0004] To overcome the above deficiencies, the present invention provides a contact system for a dual power transfer switch, which aims to improve the contradiction between contact pressure and operating torque in the prior art and the problem of poor pressure consistency of traditional leaf springs.

[0005] A contact system for a dual-power transfer switch includes two stationary contacts at the input end, a stationary contact at the load end, and a group of moving contacts. The moving contact assembly includes a moving contact support, two moving contacts, two independent contact springs, and two independent spring supports. The moving contact bracket has through holes on both sides for axial sliding of the moving contact, and has two independent mounting cavities. Each of the spring supports and a corresponding contact spring are housed together in a corresponding mounting cavity. One end of each contact spring abuts against its corresponding spring support, and the other end abuts against the inner end face of a corresponding moving contact, thereby forming two independent elastic pressure units that provide elastic pre-pressure to the two moving contacts to extend outward. The moving contact assembly is rotatably configured and has three working positions: In the first working position, one moving contact on the moving contact assembly is in electrical contact with one of the incoming line stationary contacts, while another moving contact on the moving contact assembly is in electrical contact with the load end stationary contact; In the second working position, all moving contacts are disconnected from both the incoming line stationary contact and the load end stationary contact; In the third working position, one moving contact on the moving contact assembly is in electrical contact with another of the incoming line stationary contacts, while another moving contact on the moving contact assembly is in electrical contact with the load end stationary contact. When any of the moving contacts engages with the corresponding inlet stationary contact or the load stationary contact, the moving contact is forced to slide inward and compress the corresponding contact spring, thereby increasing the contact pressure at the contact point adaptively.

[0006] Preferably, the two independent mounting cavities are two blind holes formed at the bottom of the moving contact bracket.

[0007] Preferably, the two end faces of the moving contact support are respectively provided with protrusions and recesses of matching shapes to realize inter-electrode linkage between multiple contact systems.

[0008] Preferably, each of the moving contacts is composed of two parallel strip conductors. When current flows through the two moving contacts in the same moving contact group, the current in the two strip conductors is in the same direction, generating an electromotive force that attracts each other.

[0009] Preferably, the contact spring is a helical compression spring.

[0010] Preferably, the moving contact is in line contact with the stationary contact at the input end and the stationary contact at the load end.

[0011] Preferably, the moving contact assembly rotates under the drive of an external operating mechanism to switch between the three working positions.

[0012] Preferably, the stationary contact at the input end or the stationary contact at the load end is a knife-shaped insert-type stationary contact.

[0013] Preferably, the blade-shaped insertable stationary contact includes a stationary contact portion composed of multiple contact fingers for accommodating and clamping the end of the moving contact.

[0014] Preferably, the elastic pressure unit formed by each spring bracket, contact spring and corresponding moving contact is independent of each other, so that the contact pressure between the two moving contacts and the corresponding inlet end stationary contact or load end stationary contact can be independently adjusted and kept consistent.

[0015] The present invention has the following beneficial effects: 1. In this invention, a compression spring is used to provide pressure between the moving and stationary contacts, which can effectively control the spring's processing error and avoid burnout accidents caused by excessive temperature rise of the switch contacts. In addition, the moving contact group structure in this contact system consists of two independent contact spring structures, which respectively ensure the contact pressure of the moving and stationary contacts at the inlet and load ends, and the pressure of the upper and lower moving contacts is always consistent with that of the stationary contacts. It has the advantages of reasonable and simple structural design, low cost, and ease of production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the main circuit closure of the power supply I of the contact system of a dual power supply changeover switch proposed in this invention. Figure 2 This is a schematic diagram of the dual-state contact system of a dual-power transfer switch proposed in this invention. Figure 3 This is a schematic diagram of the power supply backup circuit closure of the contact system of a dual power supply changeover switch proposed in this invention. Figure 4 This is a three-dimensional schematic diagram of the moving contact assembly of a contact system for a dual power supply changeover switch proposed in this invention. Figure 5 This is a cross-sectional schematic diagram of the moving contact assembly of the contact system of a dual power supply changeover switch proposed in this invention; Figure 6 This is an exploded schematic diagram of the moving contact assembly of the contact system of a dual power supply changeover switch proposed in this invention. Figure 7 This is a three-dimensional schematic diagram of the contact system of a dual power supply changeover switch proposed in this invention.

[0017] Among them, 1. contact bracket; 2. moving contact; 3. contact spring; 4. spring bracket; 5. stationary contact at the inlet end; 6. stationary contact at the load end; 7. moving contact group. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see the appendix Figure 1 -Appendix Figure 7 As shown, a contact system for a dual power supply changeover switch includes two stationary contacts 5 at the input end, a stationary contact 6 at the load end, and a moving contact group 7. The moving contact assembly 7 includes a moving contact support 1, two moving contacts 2, two independent contact springs 3, and two independent spring supports 4; The moving contact bracket 1 has through holes on both sides for the moving contact 2 to slide axially, and has two independent mounting cavities; Each spring bracket 4 and a corresponding contact spring 3 are housed together in a corresponding mounting cavity. One end of each contact spring 3 abuts against its corresponding spring bracket 4, and the other end abuts against the inner end face of a corresponding moving contact 2, thereby forming two independent elastic pressure units, which respectively provide elastic pre-pressure to the two moving contacts 2 to extend outward. The moving contact group 7 is rotatably configured and has three working positions: In the first working position, one moving contact 2 on the moving contact group 7 is in electrical contact with one incoming line stationary contact 5, while another moving contact 2 on the moving contact group 7 is in electrical contact with the load-side stationary contact 6; In the second working position, all moving contacts 2 are disconnected from both the incoming line stationary contact 5 and the load-side stationary contact 6; In the third working position, one moving contact 2 on the moving contact group 7 is in electrical contact with another incoming line stationary contact 5, while another moving contact 2 on the moving contact group 7 is in electrical contact with the load-side stationary contact 6. When any moving contact 2 engages with the corresponding inlet stationary contact 5 or load stationary contact 6, the moving contact 2 is forced to slide inward and compress the corresponding contact spring 3, thereby increasing the contact pressure at the contact point adaptively.

[0020] Specifically, the contact system of the dual power supply transfer switch provided by this invention is mainly used to realize reliable automatic or manual switching between the main power supply and the backup power supply, ensuring the continuity of power supply to the load. This contact system mainly includes two incoming stationary contacts 5, one load-side stationary contact 6, and a moving contact group 7. The two incoming stationary contacts 5 are spatially spaced and are used to connect the main power supply circuit and the backup power supply circuit, respectively. The load-side stationary contact 6 is located between the two and is used to connect the load circuit. The moving contact group 7 is the core component for performing the switching function. Its specific structure includes a moving contact support 1, two moving contacts 2, two independent contact springs 3, and two independent spring supports 4. The moving contact bracket 1, serving as the supporting framework and moving carrier of the entire moving contact assembly 7, is typically made of high-strength insulating material. Two through holes are symmetrically formed on its left and right sides, constituting the sliding channels of the moving contact 2. At the bottom of the moving contact bracket 1, corresponding to the inner sides of the two sliding channels, two independent mounting cavities are machined. Preferably, these two mounting cavities are bottom blind holes. Furthermore, on the two opposite end faces of the moving contact bracket 1, protrusions and recesses of mutually matching shapes are provided. When multiple of these contact systems are installed side-by-side to form a multi-pole switch, the protrusions and recesses on the end faces of adjacent moving contact brackets 1 can engage with each other, thereby achieving synchronous operation of all poles. The two moving contacts 2, serving as the main current-carrying conductors, are made of a material with good conductivity, such as copper or a copper alloy. They are slidably inserted into the through holes on the left and right sides of the moving contact support 1, and can slide freely along their axial direction within the through holes. In a preferred embodiment, each moving contact 2 is composed of two parallel strip conductors. This design ensures that when current flows through the two moving contacts 2 on the same moving contact group 7, the current in each strip conductor is in the same direction. According to electromagnetic principles, currents in the same direction will generate an electromotive force that attracts each other. This electromotive force can help enhance the contact pressure between the moving contact 2 and the stationary contact, especially when subjected to large current or short-circuit current impacts, significantly improving the dynamic stability of the contact system. Two spring supports 4 and two contact springs 3 together constitute an elastic system that provides contact pressure. Each spring support 4 is paired with one contact spring 3, forming an independent pressure module. During assembly, the two contact springs 3 are first placed into their corresponding spring supports 4. Then, the two assembled "spring support 4-contact spring 3" modules are inserted into the two mounting cavities at the bottom of the moving contact support 1 until they are in place. The contact spring 3 is preferably a helical compression spring, which has a mature manufacturing process, easily controllable force parameters, and stable and reliable performance. After the above assembly is completed, one end of each contact spring 3 abuts against the bottom inner wall of its corresponding spring bracket 4, and the other end abuts against the inner end face of a corresponding moving contact 2. Simultaneously, the side wall of the spring bracket 4 also interacts with the inner end face of the moving contact 2. Through this arrangement, the two contact springs 3 are pre-compressed, applying an outward elastic preload to the two moving contacts 2, forcing the moving contacts 2 to tend to extend outward. Thus, two completely independent and non-interfering elastic pressure units are formed, corresponding to the contact points at the inlet and load ends, respectively. The entire moving contact assembly 7 is rotatably mounted on the switch housing or base via its moving contact bracket 1. Driven by an external operating mechanism, such as a manual operating handle or an electric drive, the moving contact assembly 7 can rotate as a whole. The moving contact assembly 7 has three distinct operating positions, as shown in the attached diagram. Figure 1 , 2 As shown in Figure 3, the first working position (main power on): Figure 1 As shown, when the moving contact group 7 rotates clockwise or in a specific direction to this position, one of its moving contacts 2 makes electrical contact with the stationary contact 5 at the input end connected to the normal power supply, and simultaneously, the other moving contact 2 makes electrical contact with the stationary contact 6 at the load end. At this time, the power supply circuit from the normal power supply to the load is connected, and the second operating position (double disconnection) is as follows: Figure 2As shown, the moving contact group 7 is in the middle position. At this time, both moving contacts 2 are separated from the two incoming stationary contacts 5 and the load stationary contact 6, forming a clear isolation gap. The power supply is completely disconnected from the load, ensuring maintenance safety. Third working position (backup power on): As shown... Figure 3 As shown, when the moving contact group 7 rotates counterclockwise (or in the opposite direction) to this position, one of its moving contacts 2 connects to the other incoming stationary contact 5 of the backup power supply, while the other moving contact 2 remains connected to the load-side stationary contact 6. At this time, the power supply circuit from the backup power supply to the load is connected. When the moving contact assembly 7 rotates, causing the moving contact 2 to engage with the corresponding inlet stationary contact 5 or load stationary contact 6, the stationary contact exerts a counterforce on the end of the moving contact 2. This force compresses the moving contact 2 inward along its sliding channel. This sliding action further compresses the contact spring 3 corresponding to the moving contact 2. According to Hooke's Law, the greater the compression of the spring, the greater the resulting counterforce, i.e., the contact pressure. This significantly reduces the torque required by the operating mechanism, making manual operation easier or allowing for the use of a smaller electric mechanism. Furthermore, since the two elastic pressure units are independent of each other, the pressure at the two contact points at the input and load ends can be formed and adjusted independently without affecting each other. This ensures the balance and consistency of the contact pressure on both sides, avoiding adverse effects on the overall performance of the switch due to pressure changes on one side. At the same time, the spring force acts directly on the inner end face of the moving contact 2 through the spring bracket 4. The point of application is close to the actual contact point of the moving and stationary contacts, and the lever arm is short, effectively reducing the pressure transmission loss caused by the excessively long lever arm in traditional structures, allowing the spring force to be converted into contact pressure more efficiently. The two independent mounting cavities are two blind holes opened at the bottom of the moving contact bracket 1. The two end faces of the moving contact bracket 1 are respectively provided with protrusions and recesses of matching shapes to realize the inter-pole linkage between multiple contact systems. Each moving contact 2 is composed of two parallel strip conductors. When the current flows through the two moving contacts 2 on the same moving contact group 7, the current in the two strip conductors is in the same direction, generating an electro-force that attracts each other. The contact spring 3 is a helical compression spring. The moving contact 2 is in line contact with the stationary contact 5 at the inlet end and the stationary contact 6 at the load end.

[0021] Specifically, the two independent mounting cavities at the bottom of the moving contact bracket 1 are preferably designed as blind hole structures. These two blind holes are arranged parallel to each other at the bottom, with their axial direction approximately perpendicular to or at a predetermined angle to the sliding direction of the moving contact 2. The depth and diameter of the blind holes are designed to match the dimensions of the spring bracket 4 and the contact spring 3 to ensure they can be securely accommodated and accurately positioned. The inner wall of the blind holes may be provided with guide ribs or slots, which cooperate with the corresponding structure on the outer wall of the spring bracket 4 to prevent the spring bracket 4 from rotating or shifting within the cavity. To achieve synchronous operation of multi-pole switches, complementary protrusions and recesses are machined on the two outer end faces of the moving contact bracket 1 along the rotation axis. For example, one end face can be provided with one or more columnar bosses, while the opposite end face has corresponding grooves in number and position. When it is necessary to assemble two-pole, three-pole, or more-pole switches, simply bring the end faces of the moving contact brackets 1 of two adjacent contact systems close to each other, so that the protrusion of one bracket end face is embedded in the recess of the other bracket end face, thus achieving a rigid mechanical connection. When the external operating mechanism drives the moving contact group 7 of one pole to rotate, the meshing transmission between the protrusion and the recess can drive the moving contact groups 7 of all poles to rotate synchronously and at the same angle, ensuring that each pole completes the state switching simultaneously. Each moving contact 2 is composed of two strip conductors of the same material, shape, and size, tightly fixed side by side. These two strip conductors can be joined together by riveting, welding, or integral molding to make them electrically connected in parallel. The cross-section of the strip conductors can be rectangular or approximately rectangular to provide a larger current-carrying area. When the switch is closed, as current flows from the stationary contact 5 at the input end through one of the moving contacts 2 to the stationary contact 6 at the load end, the current is shunted through the two strip conductors of the moving contact 2. According to the principles of electromagnetism, the same-direction current flowing through two parallel and adjacent conductors will generate a Lorentz force that attracts each other. This electrodynamic force acts between the two conductors, and its effect is to make the overall structure of the moving contact 2 tend to tighten inward. This additional electrodynamic pressure acts directly on the contact area between the moving contact 2 and the stationary contact, which can significantly compensate for and offset the huge electrodynamic repulsion generated when large currents, especially short-circuit fault currents, pass through, thereby effectively enhancing the contact tightness and dynamic stability of the contacts under extreme conditions and preventing arc welding caused by repulsion. The contact spring 3 is preferably a helical compression spring. The helical compression spring is made of spring steel wire. Compared with the leaf spring that may be used in the traditional way, the helical compression spring has more stable force characteristics, smaller manufacturing tolerances, higher batch production consistency, and is less affected by stress relaxation after long-term use, thus ensuring the reliability of the contact pressure of the product throughout its entire life cycle. The electrical contact between the moving contact 2 and the stationary contact 5 at the input end and the stationary contact 6 at the load end is a line contact. Specifically, the contact surface at the end of the moving contact 2, especially when the moving contact 2 is composed of two strip conductors, forms a line contact with the contact areas of the stationary contact 5 at the input end and the stationary contact 6 at the load end. This type of contact has a higher contact pressure than surface contact, which is beneficial for piercing the oxide film and dirt layer on the contact surface, exhibiting good self-cleaning ability. At the same time, the contact resistance of line contact is more stable and less prone to drastic fluctuations due to slight surface changes or assembly tolerances, which helps reduce heat generation during energization and improve long-term operational reliability. The stationary contact 5 at the input end and the stationary contact 6 at the load end preferably adopt a knife-shaped insertion structure. Taking the stationary contact 5 at the input end as an example, it mainly includes a clamping part composed of multiple elastic conductive fingers. These fingers are usually stamped into a trapezoidal shape from copper alloy sheets and then arranged in a circle to form a plum blossom-like constricted structure. The roots of all the fingers are fixed on a common conductive base. When the end of the moving contact 2 is rotated and inserted into the clamping part, the multiple fingers hold it tightly under elastic action, forming multiple parallel current channels. The stationary contact 6 at the load end can adopt the same or similar structure. This multi-finger design results in high static current carrying capacity, good heat dissipation, and a certain adaptive tolerance for the insertion position of the moving contact 2, which can be well matched with the floating characteristics of the moving contact 2 in this embodiment. The line contact edge of the moving contact 2 is directly opposite the inner surface of these fingers to ensure reliable contact.

[0022] The moving contact assembly 7 rotates under the drive of an external operating mechanism to switch between three working positions.

[0023] Specifically, the external operating mechanism typically includes a power source, a motion conversion and transmission mechanism, and a positioning device. The power source can be a manual operating handle or an electric drive device, such as a motor or electromagnet. The function of the motion conversion and transmission mechanism is to convert the output motion of the power source into the rotational motion required to drive the moving contact assembly 7. For manual operation, a handle typically drives a set of linkages or gears, ultimately driving an output shaft that is fixedly connected to the moving contact support 1 or coupled via a coupling structure. For electric operation, the motor, through a reduction mechanism, drives the same output shaft to rotate. The moving contact bracket 1 is rotatably supported on the switch housing or frame via a shaft hole located at its center or an appropriate position. A reliable transmission connection is established between the moving contact bracket 1 and the output shaft of the external operating mechanism. For example, the moving contact bracket 1 may have a flat section, keyway, or spline to mate with the corresponding structure at the end of the output shaft, ensuring effective torque transmission. When the external operating mechanism is activated, the rotation of the output shaft directly drives the entire moving contact assembly 7 to rotate synchronously around its rotation center. To ensure that the moving contact assembly 7 can accurately and stably stop at three preset working positions and to prevent accidental displacement due to vibration or external force, a precision positioning device is integrated into the external operating mechanism. This positioning device typically includes a positioning element that rotates with the moving contact assembly 7 or the output shaft, and a positioning plate or similar component fixed to the housing. The positioning plate has three clearly defined positioning grooves or holes corresponding to the three working positions. The positioning element has elastically retractable balls, steel balls, or protrusions. When the moving contact assembly 7 rotates to the target working position, the ball bearing on the positioning component is precisely engaged in the corresponding groove on the positioning plate under the action of the spring force, generating a clear positioning feeling and realizing mechanical self-locking, thereby firmly holding the moving contact assembly 7 in that position. The specific switching process is as follows: When it is necessary to switch from the second working position to the first working position, the external operating mechanism drives the output shaft to rotate the moving contact group 7 in the first direction. The moving contact 2 on the moving contact group 7 rotates together with the contact support 1, gradually approaching and finally embedding into the corresponding input end stationary contact 5 and load end stationary contact 6. During this process, the moving contact 2 is squeezed inward by the stationary contact and slides, compressing the corresponding contact spring 3. When the moving contact group 7 rotates to the position and the positioning device locks, the contact spring 3 is compressed to the predetermined stroke, providing the set contact pressure. At this time, the first power supply circuit is reliably connected. When it is necessary to return from the first working position to the second working position, the operating mechanism drives the moving contact group 7 to rotate in the opposite direction. The moving contact 2 gradually withdraws from the stationary contact, and the compression of the contact spring 3 is gradually released until the moving contact 2 is completely separated from the stationary contact. The system returns to the double-break state. When it is necessary to switch from the second working position to the third working position, the operating mechanism drives the moving contact group 7 to rotate in the second direction, which is opposite to the aforementioned first direction. Another moving contact 2 on the moving contact assembly 7 rotates and engages with another inlet stationary contact 5, while the original moving contact 2 remains in contact with the load-side stationary contact 6. Similarly, during engagement, the corresponding contact spring 3 is compressed to provide pressure. Once in position, the positioning device locks, and the second power supply circuit is reliably connected. Through the coordinated action of the aforementioned external operating mechanism and the moving contact group 7, a fast, reliable, and clearly position-indicating switching operation between the two power supplies is achieved. The operating force of the entire system is mainly consumed in overcoming the resistance of the positioning device and the friction of the rotating parts, while the final contact pressure between the moving contact 2 and the stationary contact is provided by the built-in independent contact spring 3. This greatly optimizes the operating force requirements, making manual operation easy and allowing for the use of lower-power drive components for electric operation.

[0024] The stationary contact 5 at the input end and the stationary contact 6 at the load end are knife-type insertion stationary contacts. The knife-type insertion stationary contact includes a stationary contact portion composed of multiple contact fingers, which is used to accommodate and clamp the end of the moving contact 2.

[0025] Specifically, the stationary contact 5 at the input end and the stationary contact 6 at the load end preferably adopt a knife-shaped insertion type stationary contact structure to achieve reliable electrical connection and mechanical clamping with the moving contact 2. The knife-shaped insertion type stationary contact mainly includes a mounting base, a conductive connection bar, and clamping components. The mounting base is made of insulating material and is used to fix the stationary contact as a whole to the switch housing or bracket. One end of the conductive connection bar is reliably connected to the external power supply line or load line, and the other end is electrically connected to the clamping components. The clamping component serves to accommodate and tightly hold the end of the moving contact 2. This clamping component consists of multiple independent elastic contact fingers. These fingers are typically stamped from copper alloy sheets with good conductivity and elasticity, and each finger is roughly trapezoidal or elongated in shape. The roots of all the fingers are fixed together to a conductive base by riveting, welding, or integral molding. This conductive base is connected to the aforementioned conductive connection bar. The multiple contact fingers are arranged in a circular pattern, forming a converging structure with a central opening. The inner contour of this structure matches the shape of the insertion end of the moving contact 2. When the moving contact 2 is not inserted, the multiple contact fingers maintain a small initial opening due to their own elasticity or the action of additional small springs. When the moving contact assembly 7 rotates, aligning the end of the moving contact 2 with and entering this opening, the outer surface of the moving contact 2 contacts the inner surfaces of the multiple contact fingers, forcing the fingers to elastically open outwards. The elastic restoring force generated by the contact fingers is the initial clamping force applied to the surface of the moving contact 2, thereby establishing the initial electrical contact. As the moving contact assembly 7 continues to rotate into position, the moving contact 2 is further inserted into the stationary contact. The multiple contact fingers continue to undergo elastic deformation, tightening their encirclement of the moving contact 2. At this point, on one hand, the elastic force of the contact fingers themselves constitutes part of the contact pressure; on the other hand, when the moving contact 2 is fully inserted, its inner end face is subjected to an outward pushing force transmitted from the contact spring 3 through the spring support 4. This pushing force gives the moving contact 2 a tendency to withdraw from the stationary contact, but due to the obstruction of the stationary contact fingers, this tendency is transformed into a stronger positive pressure between the outer surface of the moving contact 2 and the inner surface of the contact fingers. This pressure, combined with the elastic force of the contact fingers, constitutes the final stable and powerful contact pressure. This structure, composed of multiple independent contact fingers, offers significant advantages. First, it provides multiple parallel current paths, effectively reducing contact resistance and improving current carrying capacity and heat dissipation. Second, the elasticity of the multiple contact fingers can adaptively compensate for manufacturing tolerances, installation deviations, and wear caused by long-term use of the moving contact 2, maintaining stable contact pressure. When the moving contact 2 is inserted or removed, relative sliding friction occurs between it and the inner wall of the contact fingers. This friction has a self-cleaning effect, scraping away oxide layers and contaminants from the contact surface and maintaining the conductivity of the contact interface. Finally, when subjected to the enormous electrodynamic force generated by a short-circuit current, the multi-finger structure exhibits a contraction effect between the contact fingers, further enhancing the clamping force on the moving contact 2, thus providing excellent electrodynamic stability.

[0026] The elastic pressure unit formed by each spring bracket 4, contact spring 3 and corresponding moving contact 2 is independent of each other, so that the contact pressure between the two moving contacts 2 and the corresponding inlet end stationary contact 5 or load end stationary contact 6 can be independently adjusted and kept consistent.

[0027] Specifically, each elastic pressure unit operates independently as a self-contained mechanical module. Its working principle is as follows: In its natural assembled state, the pre-compressed contact spring 3 applies a constant outward thrust, i.e., elastic preload, to the connected moving contact 2 through its corresponding spring support 4. This preload ensures that the moving contact 2 maintains its initial outward extension posture when not engaged with the stationary contact. When the moving contact group 7 rotates, requiring a particular moving contact 2 to engage with its target stationary contact, this engagement process only triggers the operation of the specific elastic pressure unit coupled to that moving contact 2. Specifically, the reaction force of the stationary contact on the end of the moving contact 2 forces the moving contact 2 to slide axially inward. This sliding displacement directly and uniquely translates into further compression of the corresponding contact spring 3 behind it. The compressed contact spring 3, based on its own stiffness characteristics, generates a contact pressure that is proportional to the amount of compression and increases in the opposite direction. This pressure is effectively transmitted to the moving contact 2 through the spring support 4, ultimately acting on the contact interface between the moving contact 2 and the stationary contact. The other moving contact 2, which did not engage, and its associated elastic pressure unit remain completely unaffected during this process. Moving contact 2 maintains its original position, and the compression state of its corresponding contact spring 3 remains unchanged, thus maintaining the original contact pressure between it and the corresponding stationary contact. The two pressure units are isolated from each other in terms of mechanical structure, force transmission path, and pressure generation process, with no coupling or interference. By selecting contact springs 3 with different stiffnesses or pre-compression amounts, the pressure value can be independently optimized for the specific electrical and mechanical requirements of each contact point without compromise. Secondly, it ensures pressure consistency. During long-term use, if wear causes a slight change in the insertion depth of a moving contact 2, this change will only affect the compression of its corresponding spring, automatically fine-tuning the pressure at that point without any cascading effect on the pressure at the other contact point. This design eliminates the risk of performance degradation at related contact points due to single-point pressure variations, ensuring long-term stability of the overall switch performance. Furthermore, because each spring bracket 4 is independently and directly installed within the corresponding mounting cavity of the moving contact bracket 1, the point of force application of the contact spring 3 is very close to the fulcrum of the moving contact 2, resulting in a short lever arm. This design significantly reduces the unavoidable frictional torque loss and elastic deformation effects inherent in traditional long-lever lever structures, enabling the force output by the contact spring 3 to be converted into effective contact pressure with extremely high efficiency, thus improving the accuracy and responsiveness of pressure control.

[0028] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A contact system for a dual-power transfer switch, comprising two stationary contacts (5) at the input end, a stationary contact (6) at the load end, and a moving contact group (7), characterized in that: The moving contact assembly (7) includes a moving contact support (1), two moving contacts (2), two independent contact springs (3), and two independent spring supports (4). The moving contact bracket (1) has through holes on both sides for the moving contact (2) to slide axially, and has two independent mounting cavities; Each of the spring brackets (4) and a corresponding contact spring (3) are housed together in a corresponding mounting cavity. One end of each contact spring (3) abuts against its corresponding spring bracket (4), and the other end abuts against the inner end face of a corresponding moving contact (2), thereby forming two independent elastic pressure units that provide elastic pre-pressure to the two moving contacts (2) to extend outward. The moving contact group (7) is rotatably configured as a whole and has three working positions: in the first working position, one moving contact (2) on the moving contact group (7) is in electrical contact with one of the incoming line stationary contacts (5), and at the same time, another moving contact (2) on the moving contact group (7) is in electrical contact with the load end stationary contact (6); in the second working position, all moving contacts (2) are disconnected from the incoming line stationary contact (5) and the load end stationary contact (6); in the third working position, one moving contact (2) on the moving contact group (7) is in electrical contact with another incoming line stationary contact (5), and at the same time, another moving contact (2) on the moving contact group (7) is in electrical contact with the load end stationary contact (6); When any of the moving contacts (2) engages with the corresponding inlet stationary contact (5) or the load stationary contact (6), the moving contact (2) is forced to slide inward and compress the corresponding contact spring (3), thereby increasing the contact pressure at the contact point adaptively.

2. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The two independent mounting cavities are two blind holes opened at the bottom of the moving contact bracket (1).

3. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The two end faces of the moving contact support (1) are respectively provided with protrusions and recesses of matching shapes, which are used to realize the inter-electrode linkage between multiple contact systems.

4. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: Each of the moving contacts (2) consists of two parallel strip conductors. When current flows through the two moving contacts (2) on the same moving contact group (7), the current in the two strip conductors is in the same direction, generating an electromotive force that attracts each other.

5. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The contact spring (3) is a helical compression spring.

6. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The moving contact (2) is in line contact with the incoming stationary contact (5) and the load stationary contact (6).

7. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The moving contact assembly (7) rotates under the drive of an external operating mechanism to switch between the three working positions.

8. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The stationary contact (5) at the input end or the stationary contact (6) at the load end is a knife-shaped insertion type stationary contact.

9. The contact system of a dual power supply transfer switch according to claim 8, characterized in that: The blade-shaped insert stationary contact includes a stationary contact portion composed of multiple contact fingers, used to accommodate and hold the end of the moving contact (2).

10. The contact system of a dual power supply transfer switch according to claim 1, characterized in that: The elastic pressure unit formed by each spring bracket (4), contact spring (3) and corresponding moving contact (2) is independent of each other, so that the contact pressure between the two moving contacts (2) and the corresponding inlet stationary contact (5) or load stationary contact (6) can be independently adjusted and kept consistent.

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