Three-position switch

Abstract

A three-position switch includes a common housing and an operating mechanism. A double-break switch device is installed in a sealed chamber in the common housing. The double-break switch device includes an isolating contact seat mechanism, a grounding contact seat mechanism and a moving contact mechanism. The output end of the operating mechanism is connected to a transmission connection shaft. The other end of the transmission connection shaft supports and fixes an insulating shaft that penetrates multiple sealed chambers. The insulating shaft is an integrally formed whole shaft, and a plurality of driving members arranged at intervals along the axial direction are provided on the insulating shaft. Under the cooperation of the driving member and the driven member, the moving contact mechanism moves in the sealed chamber driven by the insulating shaft to realize the operation of the double-break switch device. The power transmission process of the three-position switch of the present invention is simple. The moving contact mechanism only needs to go through two-stage power transmission to obtain power. It will not produce cumulative transmission angle errors, meet the three-phase synchronization requirements, and improve the transmission efficiency.

Description

Technical Field

[0001] The invention relates to the field of high-voltage electric power equipment, and in particular to a three-position switch. Background Art

[0002] At present, in high-voltage combination electrical appliances, three-position switches mostly adopt a three-phase sub-box structure. This combination switch uses two mechanisms to operate the isolation and grounding positions respectively. Not only is the transmission chain complex and exposed to the outside, but the transmission efficiency is low and it is easy to get stuck due to ice. At the same time, its manufacturing and maintenance costs are extremely high.

[0003] There are a few three-phase common box structures. Although this type of structure is significantly improved over the three-phase split box structure, it still has the following problems: First, the insulating shaft used to operate the break switch devices in multiple sealed chambers is connected together by multiple insulating rods through spline shaft transmission. Since there is a gap in the spline shaft connection, it is easy to accumulate transmission angle errors; second, when the operating mechanism transmits power to the moving contact, since the insulating rods are connected by spline shafts, the power transmission needs to go through multiple stages, and the power transmission between two adjacent insulating rods still needs to be transmitted through the spline shaft. The power transmission process is relatively complicated, especially the moving contacts of the three phases A, B, and C receive power through a large number of transmission stages and the transmission stages of each phase are inconsistent. Under the same processing accuracy conditions, the accumulated errors are inconsistent, and theoretically, the three-phase synchronization cannot be met, and there is a design defect; fourth, long-term wear can easily lead to eccentricity of the spline shaft, resulting in improper meshing of the gear rack and loss of isolation and grounding function. Summary of the invention

[0004] The object of the present invention is to overcome the defects of the prior art and provide a three-position switch with high reliability.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A three-position switch comprises a common box shell and an operating mechanism, wherein a plurality of sealed chambers connected in sequence are arranged in the common box shell, and a group of double-break switch devices are installed in each sealed chamber, wherein the double-break switch device comprises an isolation contact seat mechanism, a grounding contact seat mechanism and a moving contact mechanism arranged in the middle of the sealed chamber respectively, the gap between the moving contact mechanism and the isolation contact seat mechanism serves as an isolation break, and the gap between the moving contact mechanism and the grounding contact seat mechanism serves as a grounding break; the output end of the operating mechanism is connected to a transmission connecting shaft, and the other end of the transmission connecting shaft supports and fixes an insulating shaft that passes through a plurality of sealed chambers, the insulating shaft is an integrally formed whole shaft, and a plurality of driving members arranged at intervals along the axial direction are provided on the insulating shaft, the operating mechanism drives the insulating shaft to rotate, and under the cooperation of the driving member and the driven member arranged on the moving contact mechanism, the moving contact mechanism moves in the sealed chamber driven by the insulating shaft to realize the operation of the double-break switch device.

[0007] Furthermore, the insulating shaft includes an insulating rod body and a connecting shaft, the transmission connecting shaft and the connecting shaft are made of metal material, the insulating rod body is made of epoxy resin casting, and the transmission connecting shaft and the connecting shaft are cast together to achieve the insulating rod body, the transmission connecting shaft and the connecting shaft being cast into a whole.

[0008] Furthermore, the insulating shaft comprises a plurality of insulating rods and a plurality of connecting shafts, the insulating rods and the connecting shafts are arranged alternately in sequence, a shaft shoulder is arranged on the periphery of the connecting shaft, and a driving member for transmitting power of the connecting shaft to the moving contact mechanism is sleeved on the shaft shoulder;

[0009] Both ends of the connecting shaft are convex arcs protruding outwards, and one end of the transmission connecting shaft is provided with a connecting convex arc, so that when the insulating rod body is cast by epoxy resin, the convex arc and the connecting convex arc are completely fixed and clamped in the insulating rod body.

[0010] Furthermore, the operating mechanism is arranged on the outside of the common box shell, and a connecting hole is provided on the side wall of the common box shell adjacent to the operating mechanism. A sealing device for sealing the common box shell is provided in the connecting hole, and the sealing device is provided with a connecting groove. A bearing for matching the transmission connecting shaft is provided in the connecting groove. The transmission connecting shaft passes through the connecting groove to connect the insulating shaft to the operating mechanism, and the sealing device enables the power transmission between the operating mechanism and the transmission connecting shaft to be in a sealed state.

[0011] Furthermore, the sealing device includes a sealing body, the middle part of the sealing body protrudes to form a central protrusion that can be extended into the connecting hole, and the edge surrounding the central protrusion is located between the common box shell and the operating mechanism; the connecting groove is arranged through the middle part of the central protrusion, a bearing and an internal sealing structure are arranged in the connecting groove, and an external sealing structure is arranged around the edge of the central protrusion on the side of the sealing body close to the common box shell.

[0012] Furthermore, the connecting groove has a structure that is thick at both ends and thin in the middle. The connecting groove serves as an installation groove at the end close to the operating mechanism and as a shielding groove at the end close to the transmission connecting shaft. The thinner part between the shielding groove and the installation groove serves as a sealing groove, and an internal sealing structure is arranged in the sealing groove.

[0013] Furthermore, the internal sealing structure includes an end cover and a lip seal ring, wherein the end cover is located at one end close to the operating mechanism, the outer diameter of the end cover is larger than the outer diameter of the sealing groove, the end cover is fixedly installed in the installation groove, and an oil seal is provided on the side of the end cover away from the sealing groove; multiple lip seal rings are stacked and arranged on one side of the sealing groove close to the bearing, and a sealing ring partition is provided between adjacent lip seal rings; the bearing is arranged in the sealing groove, and one end of the transmission connecting shaft used for connecting to the operating mechanism passes through the bearing, the lip seal ring, the oil seal and the end cover in sequence to be connected to the operating mechanism, and the other end of the transmission connecting shaft is provided with a connecting convex arc, and the connecting convex arc extends into the shielding groove.

[0014] Furthermore, an annular groove surrounding the central protrusion is provided on one side of the sealing body close to the common box shell, and an external sealing structure is provided in the annular groove, and the external sealing structure is an airtight sealing ring.

[0015] Furthermore, the moving contact mechanism includes a moving contact and a supporting structure, the moving contact is provided with a driven member cooperating with the driving member, the supporting structure is provided with a guide groove for movement of the moving contact and a receiving groove for rotationally installing the insulating shaft, and a connecting groove for cooperation between the driving member and the driven member is provided between the receiving groove and the guide groove.

[0016] Furthermore, the accommodating groove includes a shielding groove, a lubrication groove and a driving groove with different inner diameters, the inner diameter of the lubrication groove is the smallest, and the inner diameter of the lubrication groove is greater than or equal to the outer diameter of the shoulder of the connecting shaft, the inner diameter of the shielding groove is greater than or equal to the outer diameter of the convex arc of the connecting shaft, and the driving groove is located in the middle of the accommodating groove for accommodating the driving member, the two lubrication grooves are symmetrically arranged on both sides of the driving groove for accommodating the shoulder of the connecting shaft, and the shielding grooves are symmetrically arranged at both ends of the accommodating groove for accommodating the convex arc of the connecting shaft.

[0017] Furthermore, the moving contact mechanism is fixed on an insulating basin in the sealed chamber, and the insulating basin enables the isolation contact seat mechanism, the grounding contact seat mechanism and the moving contact mechanism to maintain a coaxial line.

[0018] Furthermore, the isolation contact seat mechanism includes an isolation contact seat, a mounting groove is provided in the middle of the isolation contact seat, a self-powered arc-striking contact is installed in the mounting groove, one end of the self-powered arc-striking contact is plum blossom-shaped, the plum blossom-shaped end of the self-powered arc-striking contact is in contact with the moving contact and can contract when receiving extrusion pressure.

[0019] Furthermore, the grounding contact seat mechanism includes a grounding contact seat and a grounding insulator, the grounding contact seat is arranged at one end in the sealed chamber, one end of the grounding insulator is connected to the grounding contact seat, the other end of the grounding insulator passes through the common box shell and extends out of the sealed chamber, and a grounding copper bus is provided at the end extending out of the sealed chamber.

[0020] The three-position switch of the present invention is used to operate the insulating shaft of the moving contact mechanism in multiple sealed chambers, which is fixedly connected by an insulating rod body and a connecting shaft into an integral structure instead of using the existing spline connection. Its power transmission process is simple, and the moving contact mechanism only needs to obtain power through two-stage power transmission, which will not produce cumulative transmission angle errors, and can make the moving contacts in multiple sealed chambers move synchronously, meet the requirements of three-phase synchronization, and improve transmission efficiency. At the same time, the fixed connection of the non-spline shaft will not cause the problem of spline shaft eccentricity due to wear and tear, resulting in poor fit.

[0021] In addition, the insulating shaft is an integral structure, so that the insulating shaft can be supported in the common box shell by only one end. In this way, a transmission connecting shaft is only set at one end to connect with the operating mechanism, avoiding the need to set a structure for supporting the insulating shaft on the common box shell, which is beneficial to saving space in the common box shell and ensuring internal sealing; a sealing device is set between the transmission connecting shaft and the operating mechanism, and the sealing device makes the power transmission between the operating mechanism and the transmission connecting shaft in a sealed state, avoiding the transmission chain from being exposed to the outside and affected by ice.

[0022] In addition, the moving contact mechanism is fixed on the insulating basin in the sealed chamber so that the moving contact mechanism, the grounding contact seat mechanism and the isolation contact seat mechanism maintain a coaxial center. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a three-position switch of the present invention;

[0024] Figure 2 yes Figure 1 AA section view;

[0025] Figure 3 yes Figure 1 BB cross-sectional view;

[0026] Figure 4 yes Figure 1 CC section view;

[0027] Figure 5 yes Figure 1 A partial enlarged view of the D part in FIG.

[0028] Figure 6 It is a structural schematic diagram of the insulating shaft in the three-position switch of the present invention;

[0029] Figure 7It is a structural schematic diagram of the transmission connecting shaft in the three-position switch of the present invention;

[0030] Figure 8-9 It is a structural schematic diagram of the connecting shaft in the three-position switch of the present invention;

[0031] Fig.10 It is a structural schematic diagram of a sealing body in a three-position switch of the present invention;

[0032] Fig.11 It is a schematic diagram of a sealing body in a three-position switch of the present invention being arranged in a common box housing;

[0033] Fig.12 It is a schematic diagram of the insulating shaft of the three-position switch of the present invention being arranged in a common box housing;

[0034] Fig.13 It is a structural schematic diagram of the upper support in the three-position switch of the present invention;

[0035] Fig.14 It is a structural schematic diagram of the lower support of the three-position switch of the present invention;

[0036] Fig.15 yes Fig.13 and Fig.14 Schematic diagram of the support structure formed by the combination;

[0037] Fig.16 It is a structural schematic diagram of a moving contact in a three-position switch of the present invention;

[0038] Fig.17 yes Fig.13 Side view of

[0039] Fig.18 It is a schematic diagram of a moving contact and an upper support in a three-position switch of the present invention;

[0040] Fig.19 It is a schematic diagram of the insulating shaft and the supporting structure in the three-position switch of the present invention;

[0041] Fig. 20 It is a structural schematic diagram of the isolating contact seat mechanism in the three-position switch of the present invention;

[0042] Fig.21 It is a structural schematic diagram of a self-powered arc-striking contact in a three-position switch of the present invention;

[0043] Fig. 22 yes Fig.21 A top view of

[0044] Fig.23 It is a structural schematic diagram of the ground contact seat mechanism in the three-position switch of the present invention;

[0045] Fig.24It is a schematic diagram of the structure of the adsorption device in the three-position switch of the present invention;

[0046] Fig.25 It is a structural schematic diagram of a cover shell in a three-position switch of the present invention. DETAILED DESCRIPTION

[0047] The following is combined with Figures 1 to 25 The following examples are provided to further illustrate the specific implementation of the three-position switch of the present invention. The three-position switch of the present invention is not limited to the description of the following examples.

[0048] A three-position switch comprises a common housing 1 and an operating mechanism 2, wherein a plurality of sealed chambers 11 connected in sequence are arranged in the common housing 1, wherein a group of double-break switch devices are installed in each sealed chamber 11, wherein the double-break switch devices comprise an isolating contact seat mechanism, a grounding contact seat mechanism and a moving contact mechanism arranged at the middle of the sealed chamber 11 respectively, wherein the gap between the moving contact mechanism and the isolating contact seat mechanism serves as an isolating break, and the gap between the moving contact mechanism and the grounding contact seat mechanism serves as a grounding break; wherein the moving contact mechanism comprises a supporting structure and a moving contact, wherein the moving contact is supported by the supporting structure and moves in a straight line between the isolating contact seat mechanism and the grounding contact seat 71 under the drive of the operating mechanism 2, wherein one end of the moving contact close to the isolating contact seat mechanism serves as an isolating moving contact, and when the isolating moving contact cooperates with the isolating contact seat mechanism, the isolating break is conducted; and one end of the moving contact close to the grounding contact seat mechanism serves as a grounding moving contact, and when the grounding moving contact cooperates with the grounding contact seat mechanism, the grounding break is conducted.

[0049] like Figure 1 , 11 As shown in Figures 1 and 12, the operating mechanism 2 operates the double-break switch device in each sealed chamber 11 through an insulating shaft 4 that passes through multiple sealed chambers 11. The output end of the operating mechanism 2 is connected to a transmission connecting shaft 3, and the other end of the transmission connecting shaft 3 supports and fixes an insulating shaft 4 that passes through multiple sealed chambers 11. Only one end of the insulating shaft 4 is supported in the common box housing 1 through the transmission connecting shaft 3, avoiding the need to set support members at both ends of the common box housing 1, which can reduce the number of parts in the common box housing 1 and avoid opening support holes in the common box housing 1, thereby ensuring the sealing of the common box housing 1. Figure 1 , 6 , 11 and 12, the insulating shaft 4 is an integral structure, a plurality of driving members 43 are arranged on the insulating shaft 4, and the plurality of driving members 43 are arranged at intervals along the axial direction, and the driving member 43 is used to cooperate with the follower 62 of the moving contact mechanism (see the follower 62 Figure 2 , 3, 4 and 16), the insulating shaft 4 is preferably composed of an insulating rod body 41 and a connecting shaft 42 that are fixedly connected at the ends to form an integral structure, and the operating mechanism 2 drives the insulating shaft 4 to rotate so that the driving member 43 cooperates with the follower 62 arranged on the moving contact mechanism, and the moving contact mechanism moves in the sealed chamber 11 driven by the insulating shaft 4 to operate the double break switch device.

[0050] Compared with the existing scheme, the insulating rod body 41 and the connecting shaft 42 that form the insulating shaft 4 are fixedly connected to form a whole, so that the operating mechanism 2 can directly transmit the driving force to the insulating shaft 4, and then the power of the driving member 43 on the insulating shaft 4 is transmitted to the moving contact in each sealed chamber 11 through the follower 62, avoiding power transmission between the insulating rod body 41 and the connecting shaft 42, so that the power obtained by the moving contact only needs to go through two stages of power transmission, avoiding cumulative transmission angle errors, and ensuring the synchronization of the movement of multiple moving contacts; at the same time, the insulating shaft 4 can be rotatably supported in the common box shell 1 only by a transmission connecting shaft 3, reducing the number of components in the common box shell 1, which is conducive to reducing the overall volume.

[0051] like Figure 6 , 8 As shown in Figure 9, the driving member 43 is preferably an outer gear ring sleeved on the insulating shaft 4, and the driven member 62 of the moving contact is a rack meshing with the outer gear ring. The operating mechanism 2 drives the insulating shaft 4 to rotate through the transmission connecting shaft 3. With the cooperation of the outer gear ring and the rack, each moving contact makes reciprocating motion along a straight line in its respective sealed chamber 11 to realize the operation of the double break switch device.

[0052] like Figure 1 , 6 -9 and Figure 11-12 As shown, the insulating shaft 4 includes multiple insulating rod bodies 41 and multiple connecting shafts 42. The multiple insulating rod bodies 41 and the multiple connecting shafts 42 are fixedly connected at the ends to form a whole. The end connection between the insulating rod bodies 41 and the connecting shafts 42 is preferably a concave-convex fit to enhance the stability of the fixed connection.

[0053] Specific as Figure 6-9 As shown, three insulating rods 41 are connected to three connecting shafts 42 at intervals, each connecting shaft 42 corresponds to one of the three phases A, B, and C, and two adjacent insulating rods 41 are connected together through a connecting shaft 42. Each connecting shaft 42 is provided with at least one driving member 43 for operating a moving contact mechanism. The insulating rod 41 is made of epoxy resin material, and the connecting shaft 42 is made of metal material. A shoulder 421 is provided in the middle of the connecting shaft 42, and preferably a wear-resistant dielectric coating is coated on the shoulder 421 to enhance the wear resistance. Figure 8 , 9As shown, at least one driving member 43 is arranged on the shaft shoulder 421. The driving member 43 is preferably an outer gear ring sleeved on the shaft shoulder 421. The outer gear ring is meshed with a rack as a follower 62 on the moving contact to drive the moving contact to move. Convex arcs 422 protruding outward are arranged at both ends of the connecting shaft 42. Preferably, the three insulating rod bodies 41 and the three connecting shafts 42 are cast together to form an integrated whole. The spherical convex arc 422 facilitates uniform electric field and the convex arc 422 is enclosed in the insulating rod body 41, which is beneficial for electric field shielding of the convex arc 422. It should be noted that the connecting shaft 42 is not arranged at the end of the insulating shaft 4 close to the operating mechanism 2. Figure 6 , 7 As shown, at this time, the end close to the operating mechanism 2 is connected to the transmission connection shaft 3, and the transmission connection shaft 3 is made of metal material. It is preferred that the transmission connection shaft 3 and the insulating rod body 41 are cast together to form a whole, that is, the insulating rod body 41 is made of epoxy resin casting, and the transmission connection shaft 3 and the connecting shaft are cast together to achieve that the insulating rod body 41, the transmission connection shaft 3 and the connecting shaft 42 are cast into a whole. A connection convex arc 31 is protruded at one end of the transmission connection shaft 3, and the connection convex arc 31 is enclosed in the insulating rod body 41. The other end of the transmission connection shaft 3 is an outer hexagonal structure 32 connected to the operating mechanism 2. The transmission shaft at the end of the insulating rod away from the operating mechanism 2 can be as follows Fig. 9 As shown, a convex arc 422 is provided at one end close to the insulating rod body 41 , and no convex arc 422 is provided at one end away from the insulating rod body 41 .

[0054] The insulating rod body 41 is fixedly connected to the connecting shaft 42 so that the insulating shaft 4 forms an integrated whole, thereby avoiding power transmission between two adjacent insulating rod bodies 41 through a spline-like structure. In addition, the insulating shaft 4 is fixedly connected to the transmission connecting shaft 3 to form a whole, so that the power of the operating mechanism 2 is directly transmitted to the insulating shaft 4. Compared with the traditional spline transmission method, it not only reduces the difficulty of parts docking, but also improves the transmission efficiency, and further ensures the synchronization of the actions of multiple moving contacts.

[0055] like Figure 1-4 , 13-15 and 17-19, the supporting structure of the moving contact mechanism is provided with a guide groove 641 for the moving contact to move and a receiving groove 642 for the insulating shaft 4 to be rotatably installed. The receiving groove 642 preferably only receives the connecting shaft 42 of the insulating shaft 4. A connecting groove is provided between the receiving groove 642 and the guide groove 641. The connecting groove is used to make the driving member 43 of the insulating shaft 4 match with the driven member 62 of the moving contact. The receiving groove 642 is formed by the arc grooves of the upper support 64 and the lower support 65. The guide groove 641 and the receiving groove 642 are preferably kept perpendicular to each other, and the guide groove 641 is provided on the upper support 64 to facilitate the installation of the insulating shaft 4. Of course, the guide groove 641 can also be provided on the lower support 65.

[0056] The receiving groove 642 for installing the insulating shaft 4 is formed by the arc groove of the upper support 64 and the lower support 65, which reduces the difficulty of installing the insulating shaft 4 and avoids the need to dock the insulating shaft 4 in the common box shell 1 when installing the insulating shaft 4. It should be noted that the insulating shaft 4 installed in the receiving groove 642 formed by the encirclement can be an insulating shaft 4 fixedly connected as an integral whole by multiple insulating rod bodies 41 and multiple connecting shafts 42 as described above, or it can be an insulating shaft 4 connected by multiple insulating rod bodies 41 and multiple connecting shafts 42 through a transmission connection. The transmission connection method can be a spline connection, but the transmission connection method of multiple insulating rod bodies 41 and multiple connecting shafts 42 has the defect that the three phases cannot be synchronized.

[0057] Specifically, Fig.15 As shown, the receiving groove 642 includes a driving groove a1+a2 for receiving the driving member 43, and the driving groove a1+a2 is preferably located in the middle of the receiving groove 642. The groove wall of the driving groove a1+a2 is provided with a connecting groove, and a guide groove 641 is provided on the upper support 64. The upper support 64 and the lower support 65 are respectively provided with a first semicircular arc groove I and a second semicircular arc groove II. Of course, the arc groove provided on the upper support 64 and the arc groove provided on the lower support 65 only need to be surrounded to form a full circle, so the arc grooves of the two can be asymmetric arc grooves. The first semicircular arc groove I and the second semicircular arc groove II are combined to form the receiving groove 642, and the driving groove a1+a2 for receiving the driving member 43 is provided at intervals along the axial direction of the receiving groove 642, and the driving groove a1+a2 is coaxial with the receiving groove 642. The driving groove a1+a2 is provided with a connecting groove on the side close to the guide groove 641, and the connecting groove provides a matching space for the matching of the driving member 43 and the driven member 62.

[0058] The receiving groove 642 also includes a lubrication groove b1+b2, and the lubrication groove b1+b2 is coaxial with the receiving groove 642. The lubrication groove b1+b2 is symmetrically arranged on both sides of the driving groove a1+a2. By adding paste grease into the lubrication groove b1+b2, the friction between the connecting shaft 42 and the supporting structure during rotation is reduced, thereby enhancing the lubrication effect of the supporting structure and the connecting shaft 42.

[0059] The accommodating groove 642 also includes a shielding groove c1+c2 coaxial with the accommodating groove 642, and the shielding groove c1+c2 is used to shield the electric field of the connecting shaft 42. The shielding groove c1+c2 is symmetrically arranged at both ends of the accommodating groove 642. Preferably, the inner diameter of the shielding groove c1+c2 is greater than or equal to the outer diameter of the convex arc 422 at the end of the connecting shaft 42, so that the convex arc 422 arranged on the connecting shaft 42 is accommodated in the shielding groove c1+c2, and the shielding groove c1+c2 is symmetrically arranged on both sides of the lubrication groove b1+b2.

[0060] Since the receiving groove 642 is formed by the arc grooves of the upper support 64 and the lower support 65, the installation of the insulating shaft 4 is more convenient. This structure is conducive to the installation and positioning of the variable diameter connecting shaft 42. Figure 13-15 As shown, the accommodating groove 642 includes a shielding groove c1+c2, a lubrication groove b1+b2 and a driving groove a1+a2 with different inner diameters. Preferably, the inner diameter of the lubrication groove b1+b2 is the smallest, and the inner diameter of the lubrication groove b1+b2 is greater than or equal to the outer diameter of the shoulder 421 of the connecting shaft 42. The inner diameter of the shielding groove c1+c2 only needs to be greater than or equal to the outer diameter of the convex arc 422 at the end of the connecting shaft 42. The driving groove a1+a2 is located in the middle of the accommodating groove 642, preferably between the two lubrication grooves b1+b2. When installing the connecting shaft 42, it is only necessary to separate the upper support 64 from the lower support 65, and place the various parts of the connecting shaft 42 into relative grooves to prevent axial movement and radial runout during rotation.

[0061] like Fig.13 As shown, a circular through groove running longitudinally through the upper portion of the upper support 64 is provided as a guide groove 641 for the movable contact to move, and a first semicircular arc groove I is provided on the lower side of the middle portion of the upper support 64, wherein the central axis of the first semicircular arc groove I is perpendicular to the central axis of the guide groove 641, and the radius of the middle portion of the first semicircular arc groove I is increased to form a third semicircular arc groove a1, and a connecting groove connected to the guide groove 641 is provided on the groove wall of the third semicircular arc groove a1; the radius of the middle portion of the first semicircular arc groove I is reduced to form a fifth semicircular arc groove b1, and the number of the fifth semicircular arc grooves b1 is two, and the two fifth semicircular arc grooves b1 are symmetrically located on both sides of the third semicircular arc groove a1; a seventh semicircular arc groove c1 is provided at both ends of the first semicircular arc groove I, and the radius of the seventh semicircular arc groove c1 is substantially equal to that of the third semicircular arc groove a1;

[0062] Correspondingly, such as Fig.14 As shown, a second semicircular arc groove II corresponding to the first semicircular arc groove I is provided on the upper middle side of the lower support 65, the middle radius of the second semicircular arc groove II is increased to form a fourth semicircular arc groove a2, and the radius of the fourth semicircular arc groove a2 is equal to the radius of the third semicircular arc groove a1; the middle radius of the second semicircular arc groove II is reduced to form a sixth semicircular arc groove b2, the radius of the sixth semicircular arc groove b2 is equal to the radius of the fifth semicircular arc groove b1, the number of the sixth semicircular arc grooves b2 is two, and the two sixth semicircular arc grooves b2 are symmetrically located on both sides of the fourth semicircular arc groove a2; an eighth semicircular arc groove c2 corresponding to the seventh semicircular arc groove c1 is provided at both ends of the second semicircular arc groove II.

[0063] like Fig.15As shown, when the first semicircular arc groove I of the upper support 64 and the second semicircular arc groove II of the lower support 65 are combined to form a full circular accommodating groove 642, the third semicircular arc groove a1 and the fourth semicircular arc groove a2 are combined to form a full circular driving groove a1+a2, and the radius of the driving groove a1+a2 is greater than the radius of the accommodating groove 642, the fifth semicircular arc groove b1 and the sixth semicircular arc groove b2 are combined to form a full circular lubrication groove b1+b2, and the lubrication grooves b1+b2 are arranged on both sides of the driving groove a1+a2, the seventh semicircular arc groove c1 and the eighth semicircular arc groove c2 are combined to form two shielding grooves c1+c2, and the shielding grooves c1+c2 are located at both ends of the accommodating groove 642. Of course, the shielding grooves c1+c2 can also be irregular structures.

[0064] Preferably, the contact surface between the support structure and the moving contact and the contact surface between the support structure and the insulating shaft 4 are plated with silver, which is beneficial to reducing the contact resistance and improving the conductivity.

[0065] like Figure 1-4 , 11, 13, 15 and 17-18, the support structure also has a heat dissipation portion 66 for increasing the heat dissipation area, and the heat dissipation portion 66 is used to dissipate the heat transferred from the moving contact to the support structure and the heat generated by the friction of the components arranged in the support structure. The heat dissipation portion 66 is located at the upper part of the support structure. The heat dissipation portion 66 preferably protrudes outward from the upper part of the support structure to form a protrusion that increases the heat dissipation area. The support structure provided with the heat dissipation portion 66 has a structure that is larger at the top and smaller at the bottom as a whole. The protrusion shape of the heat dissipation portion 66 can be a circular protrusion, a rectangular protrusion or a protrusion of other shapes. The number of heat dissipation portions 66 can be multiple or an integral structure. The heat dissipation portion 66 can also be located at other parts of the support structure, such as at the end edge of the guide groove 641 that protrudes outward evenly to increase the heat dissipation area. Preferably as Fig.15 As shown, the heat dissipation portion 66 is an integral structure, and the upper portion of the upper support 64 protrudes upward to form a circular protrusion heat dissipation portion 66. The heat dissipation portion 66 is located above the guide groove 641, so that the upper support 64 with the heat dissipation portion 66 is in a "convex" shape with a high middle and low sides. A groove is provided in the center of the heat dissipation portion 66, and the central axis of the groove is perpendicular to the central axes of the guide groove 641 and the accommodating groove 642. The groove can further increase the heat dissipation surface area, and also helps to reduce the weight of the parts.

[0066] like Figure 1-4As shown, the sealed chamber 11 also includes a plurality of insulating basins 12, and the double-break switch device is fixedly installed in the sealed chamber 11 through the insulating basins 12. The insulating basins 12 can be used to adjust the relative positions of the isolation contact seat mechanism, the grounding contact seat mechanism and the moving contact mechanism so that the three maintain a coaxial center; the insulating basins 12 are used to fix the moving contact mechanism and make the moving contact mechanisms in each sealed chamber 11 coaxial, and the lower support 65 of the moving contact mechanism is fixedly installed on the insulating basin 12, which further ensures the synchronization when the insulating shaft 4 operates multiple moving contacts, and also reduces the difficulty of assembly, especially reduces the difficulty of docking between the various insulating rods 41 in the insulating shaft 4. In addition, an airtight sealing ring 91 and a waterproof sealing ring 92 are installed in the insulating basin 12. The airtight sealing ring 91 and the waterproof sealing ring 92 are usually arranged on the side close to the common box shell 1 and the side away from the common box shell 1, which is conducive to ensuring the airtightness and waterproofness of the sealed chamber 11.

[0067] like Figure 1 , 5 As shown in Figures 10 and 10, the operating mechanism 2 is arranged outside the common box housing 1, and a connecting hole is provided on the side wall of the common box housing 1 adjacent to the operating mechanism 2. A sealing device for sealing the common box housing 1 is provided in the connecting hole, and the sealing device is provided with a connecting groove. A bearing 38 for fitting and installing the transmission connecting shaft 3 is provided in the connecting groove. The transmission connecting shaft 3 passes through the connecting groove to connect the insulating shaft 4 to the operating mechanism 2, and the sealing device enables the power transmission between the operating mechanism 2 and the transmission connecting shaft 3 to be in a sealed state.

[0068] like Fig.10 As shown, the sealing device includes a sealing body 33, the middle part of the sealing body 33 protrudes to form a central protrusion that can be inserted into the connecting hole, and the edge surrounding the central protrusion is located between the common box shell 1 and the operating mechanism 2; the connecting groove is set in the middle of the central protrusion, a bearing 38 and an internal sealing structure are arranged in the connecting groove, and an external sealing structure is provided on the edge surrounding the central protrusion.

[0069] The connecting groove is preferably a structure with thick ends and thin middle. The connecting groove is used as a mounting groove 33a at the end close to the operating mechanism 2 and as a shielding groove 33b at the end close to the transmission connecting shaft 3. The thinner part between the shielding groove 33b and the mounting groove 33a is used as a sealing groove. An internal sealing structure is arranged in the sealing groove, and the internal sealing structure includes an end cover 34 and a lip sealing ring 36. The end cover 34 is located at the end close to the operating mechanism 2. Preferably, the outer diameter of the end cover 34 is larger than the outer diameter of the sealing groove. The end cover 34 is fixed in the mounting groove 33a. As shown in the figure, it is fixed in the groove 33a by screws. An oil seal 35 is provided on one side, and the lip seal ring 36 is arranged on one side of the sealing groove close to the bearing 38. Preferably, a plurality of stacked lip seal rings 36 are provided in the sealing groove, and a seal ring partition 37 is provided between adjacent lip seal rings 36 to enhance the sealing effect of the lip seal ring 36. Preferably, the outer diameter of the lip seal ring 36 is equal to the inner diameter of the sealing groove; the bearing 38 is preferably arranged in the sealing groove, and one end of the transmission connecting shaft 3 used for connecting with the operating mechanism 2 passes through the bearing 38, the lip seal ring 36 and the end cover 34 in sequence to be connected with the operating mechanism 2. The transmission connecting groove is provided with an end of the connecting convex arc 31 located in the shielding groove 33b, and the shielding groove 33b is used to perform electric field shielding on the connecting convex arc 31 of the transmission connecting shaft 3.

[0070] An annular groove surrounding the central protrusion is provided on the edge surrounding the central protrusion, and an external sealing structure is provided in the annular groove. The annular groove is located on the side of the sealing body 33 close to the common box housing 1, and an airtight sealing ring 91 is installed in the annular groove. Preferably, an annular mounting groove for installing a waterproof sealing ring 92 is provided on the side of the common box housing 1 close to the operating mechanism 2, and a waterproof sealing ring 92 is installed in the annular mounting groove, and a double-channel sealing of the waterproof sealing ring 92 and the sealing device is adopted, especially a sealing method combining an internal sealing structure and an external sealing structure is adopted, which ensures that the power transmission is in a fully sealed environment, which is both waterproof and dustproof and can ensure airtightness, and does not need to set up additional waterproof and dustproof structures, so as to avoid rainwater inflow or atmospheric corrosion during use.

[0071] like Figure 1-4 As shown in Figures 16 and 20, the double-break switch device arranged in the sealed chamber 11 includes a moving contact mechanism and an isolating contact seat mechanism with a heat dissipation structure, the moving contact mechanism includes a moving contact body 61, and the moving contact body 61 is provided with a radial heat dissipation channel 611 and an axial heat dissipation channel 612 as a heat dissipation structure, the isolating contact seat mechanism includes an isolating contact seat 51, and the isolating contact seat 51 is provided with a heat dissipation hole 511 as a heat dissipation structure. When the moving contact mechanism cooperates with the isolating contact seat mechanism, the heat dissipation structure dissipates the heat of the isolating contact seat 51 and the moving contact, so as to avoid welding between parts due to the inability to dissipate the heat in the core.

[0072] Specifically, Fig.16 As shown, the moving contact seat mechanism includes a moving contact, and the moving contact includes a moving contact body 61, a follower 62 and a copper tungsten member 63; the moving contact body 61 is a strip conductor, and the follower 62 is arranged on the outer side of the moving contact body 61 along the axial direction of the moving contact, and the follower 62 is used to cooperate with the driving member 43 of the insulating shaft 4 to drive the moving contact to reciprocate in the sealed chamber 11, and the follower 62 is preferably a rack, and the rack is fixed to the outer wall of one side of the moving contact body 61; a plurality of radial heat dissipation channels 611 are provided on the side opposite to the follower 62, and the plurality of radial heat dissipation channels 611 are arranged at intervals along the axial direction, and the radial heat dissipation channels 611 are preferably countersunk holes that pass through the axis of the moving contact body 61 and are perpendicular to the driving member 43 ... A connecting screw for connecting with the follower 62 is installed in the heat dissipation channel 611. In this way, the connecting screw is installed in the radial heat dissipation channel 611 to connect the follower 62 and the moving contact body 61 together, avoiding the opening of too many groove structures on the moving contact body 61; a blind hole is provided in the middle of one end of the moving contact body 61, and a copper tungsten part 63 is installed at the outer end of the blind hole. The copper tungsten part 63 is hollow cylindrical and is arranged close to the side wall of the blind hole. The inner end of the blind hole serves as an axial heat dissipation channel 612. Preferably, the axial heat dissipation channel 612 is communicated with at least one radial heat dissipation channel 611. One end of the moving contact provided with the axial heat dissipation channel 612 cooperates with the isolation contact seat mechanism, and the other end of the moving contact cooperates with the grounding contact seat mechanism. Of course, a through hole can also be set in the middle of one end of the moving contact as an axial heat dissipation channel 612. In this case, the copper tungsten part 63 can be set at both ends or one end of the axial heat dissipation channel 612, but the isolation contact seat mechanism needs to be matched with the end with the copper tungsten part 63.

[0073] like Fig.15 , 17 As shown in FIG. 19, the movable contact mechanism also includes a supporting structure, the supporting structure is provided with a guide groove 641 for the movable contact to move, conductive contact fingers 93 are respectively installed at both ends of the guide groove 641, and a center retaining sleeve 643 is installed in the middle of the guide groove 641. The center retaining sleeve 643 is arranged circumferentially along the side wall of the guide groove 641, and a notch is provided on one side of the center retaining sleeve 643. The movable contact is inserted in the middle of the conductive contact finger 93 and the center retaining sleeve 643, and the follower 62 of the movable contact passes through the notch and cooperates with the driving member 43 of the insulating shaft 4 in the connecting groove. It is preferred to evenly apply conductive paste on the outside of the movable contact body 61 of the movable contact. The positioning pin 67 is used to connect the follower 62 with the movable contact body 61, further ensure the accuracy of the rack installation and positioning, and strengthen the shear resistance of the bolt.

[0074] like Figure 20-22As shown, the isolation contact seat mechanism includes an isolation contact seat 51, a mounting groove is provided in the middle of the isolation contact seat 51, and a heat dissipation hole 511 connected to the mounting groove is provided on one side of the isolation contact seat 51; when the isolation contact seat mechanism cooperates with the moving contact mechanism, the heat of the isolation contact seat mechanism and the moving contact can be dissipated through the axial heat dissipation channel 612, the radial heat dissipation channel 611 and the heat dissipation hole 511, thereby reducing the heat of each component and preventing welding between parts. A self-powered arc-striking contact 52 is installed in the mounting groove, and a conductive contact finger 93 is sleeved on the outer side of the self-powered arc-striking contact 52. The self-powered arc-striking contact 52 includes a first connecting piece 521 and a second connecting piece 522. One end of the first connecting piece 521 is installed in the installation groove of the isolation contact seat 51, and the other end of the first connecting piece 521 is arranged as a retractable petal structure. The second connecting piece 522 includes a plurality of petal structures. The second connecting piece 522 is arranged on the petal structure of the first connecting piece 521 so that the end of the self-powered arc-striking contact 52 that contacts the moving contact is in a plum blossom shape. The plum blossom-shaped end of the self-powered arc-striking contact 52 can be retracted when subjected to extrusion force.

[0075] Preferably, the first connecting member 521 is integrally formed of a chrome bronze material, and the second connecting member 522 is formed of a copper tungsten material.

[0076] The double-break switch device also includes a grounding contact seat mechanism, the grounding contact seat mechanism is as follows Fig.23 As shown, it includes a grounding contact seat 71 and a grounding insulator 72, the grounding contact seat 71 is arranged in the sealed chamber 11, and a mounting groove is provided in the middle of the grounding contact seat 71, and a conductive contact finger 93 is installed in the mounting groove for cooperating with the moving contact; the grounding insulator 72 is connected to the grounding contact seat 71 and passes through the common box shell 1 to extend out of the sealed chamber 11, and a grounding copper bar 73 is provided at one end of the grounding insulator 72 that passes through the common box shell 1 and extends out of the sealed chamber 11. Preferably, the grounding copper bar 73 is L-shaped, one end of the grounding copper bar 73 is connected to the grounding insulator 72, and the other end is connected to the common box shell 1. This method of converging with the common box shell 1 can greatly reduce the use of the grounding copper bar 73, and also helps to reduce the size of the grounding insulator 72, saving costs.

[0077] An annular sealing cover 15 device is provided between the grounding insulator 72 and the sealed chamber 11. A central hole is provided in the middle of the annular sealing cover 15 device for the grounding insulator 72 to pass through. A sealing plug 74 is provided in the central hole. An annular groove is provided on the annular sealing cover 15 device on one side close to the sealed chamber 11. An airtight sealing ring 91 and / or a waterproof sealing ring 92 are installed in the annular groove. In the present invention, an airtight sealing ring 91 or a waterproof sealing ring 92 is installed in each annular groove, and the inner diameter of the annular groove in which the waterproof sealing ring 92 is provided is greater than the outer diameter of the annular groove in which the airtight sealing ring 91 is provided.

[0078] like Figure 1 , 3 As shown in Figures 24 and 25, a three-position switch includes a common box housing 1 and an operating mechanism 2, wherein a plurality of sealed chambers 11 which are longitudinally connected in sequence are arranged in the common box housing 1, and a double-break switch device controlled by the operating mechanism 2 is installed in each sealed chamber 11, and the double-break switch device includes an isolating contact seat mechanism, a grounding contact seat mechanism and a moving contact mechanism; a side wall of the sealed chamber 11 is provided with a closable opening, and the opening is provided with a sealing cover device for sealing, wherein at least one sealing cover device is provided with an adsorption device for adsorbing moisture in the sealed chamber 11, and a dust removal device for removing metal powder is provided around the moving contact mechanism.

[0079] The sealing device covers the opening of the sealed chamber 11 on the outside, and an annular groove with an inner diameter larger than the outer diameter of the opening is provided on the side of the sealing device close to the opening. An airtight sealing ring 91 and / or a waterproof sealing ring 92 is installed in the annular groove. The number of the annular grooves is preferably multiple. The multiple annular grooves can make it possible to install the airtight sealing ring 91 and the waterproof sealing ring 92 separately. Preferably, the waterproof sealing ring 92 surrounds the outside of the airtight sealing ring 91.

[0080] like Fig.24 , 25 As shown, the adsorption device comprises a cover 81 with an opening facing upward, an adsorption tank for accommodating an adsorbent is provided in the middle of the cover 81, a vent hole 81a is provided on the tank wall of the adsorption tank, and the cover 81 is fixedly connected to the cover device to close the adsorption tank. Figure 1 , 3 As shown, the adsorption device is arranged at the opening at the top of the sealed chamber 11, and only a vent hole 81a is opened on the side wall of the adsorption tank to prevent granular adsorbent from falling through the vent hole 81a and causing electrical failure. It is best to put the adsorbent into an adsorption bag and then put it into the adsorption tank to further ensure that the adsorbent particles fall.

[0081] like Figure 2-4 As shown, the dust removal device is a particle capture trap 82 arranged on both sides of the moving contact mechanism. The particle capture trap 82 collects the metal powder generated after friction in the particle capture trap 82 to prevent discharge caused by the metal powder falling into the insulating basin 12. The particle capture trap 82 is preferably formed by bending the side wall of the common box shell 1 around the moving contact mechanism outward to form a groove structure facing the inside of the sealed chamber 11.

[0082] The openings arranged on the side wall of the sealed chamber 11 include a first opening, a second opening, a third opening and a fourth opening. The first opening and the second opening are arranged opposite to each other in the horizontal direction of the sealed chamber 11, and the central axes of the first opening and the second opening coincide with each other. The isolation contact seat mechanism is installed on the closing device of the first opening of the cover, and the grounding contact seat mechanism is installed on the closing device of the second opening of the cover; the third opening and the fourth opening are arranged opposite to each other in the vertical direction of the sealed chamber 11, the moving contact mechanism is installed on the closing device of the third opening of the cover, and the adsorption device is installed on the closing device of the fourth opening of the cover.

[0083] The closing devices of the first opening and the third opening are both insulating basins 12, and the insulating basin 12 has a "convex" structure with a high center and low edges as a whole, and its central protrusion extends into the sealed chamber 11, and its edge is provided with an annular groove surrounding the central protrusion, and an airtight sealing ring 91 and / or a waterproof sealing ring 92 are installed in the annular groove to ensure the sealing of the sealed chamber 11; the moving contact mechanism is arranged near the third opening, and the side wall of the common box shell 1 around the third opening is preferably bent outward to form a groove with an opening facing the inside of the sealed chamber 11, and the groove serves as a particle capture trap 82 for adsorbing metal powder. The closing device of the second opening is an annular sealing cover 15 device, and a through central hole is provided in the middle of the annular sealing cover 15 device, and the central hole is for the grounding insulator 72 to pass through and connect with the grounding contact seat 71 in the sealed chamber 11. The central hole is provided with a sealing plug 74 for sealing the gap between the insulating grounding element and the central hole. An annular groove surrounding the central hole is provided on the annular sealing cover 15 device, and the annular groove is preferably located on a side close to the sealed chamber 11, and an airtight sealing ring 91 and / or a waterproof sealing ring 92 are installed in the annular groove. The sealing device of the fourth opening is a sealing cover 14, which is preferably circular. An annular groove with an inner diameter larger than the fourth opening is provided on the side of the sealing cover 14 close to the fourth opening. An airtight sealing ring 91 and / or a waterproof sealing ring 92 is installed in the annular groove. The number of the annular grooves can be multiple. The airtight sealing ring 91 and the waterproof sealing ring 92 can be respectively arranged in different annular grooves. Preferably, the waterproof sealing ring 92 surrounds the outside of the airtight sealing ring 91. The adsorption device is installed in the sealed chamber 11 and connected to the sealing cover 14.

[0084] like Figure 1 , 3As shown, the common box housing 1 is also provided with an exhaust port and an explosion-proof port. The exhaust port is equipped with a gas filling and discharging device 84, and the explosion-proof port is equipped with an explosion-proof membrane device 83. When the pressure in the sealed chamber 11 rises to a certain level, the explosion-proof membrane device 83 releases the pressure first to avoid the danger caused by the explosion of the common box housing 1. The exhaust port and the explosion-proof port are usually only provided on the common box housing 1, preferably in the sealed chamber 11 in the middle position. The common box housing 1 provided in this embodiment includes A-phase, B-phase, and C-phase sealed chambers 11 connected in sequence, and the explosion-proof port is provided in the B-phase sealed chamber 11 located in the middle.

[0085] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A three-position switch, comprising a common housing (1) and an operating mechanism (2), wherein a plurality of sealed chambers (11) connected in sequence are arranged in the common housing (1), and a set of double-break switch devices is installed in each sealed chamber (11), characterized in that: The double-break switch device comprises an isolating contact seat mechanism and a grounding contact seat mechanism respectively arranged at two ends of the sealed chamber (11) and a moving contact mechanism arranged in the middle of the sealed chamber (11); the gap between the moving contact mechanism and the isolating contact seat mechanism serves as an isolating break, and the gap between the moving contact mechanism and the grounding contact seat mechanism serves as a grounding break; the output end of the operating mechanism (2) is connected to a transmission connecting shaft (3); the other end of the transmission connecting shaft (3) supports and fixes an insulating shaft (4) that passes through a plurality of sealed chambers (11); the insulating shaft (4) is an integrally formed whole shaft, and a plurality of driving members (43) arranged at intervals along the axial direction are provided on the insulating shaft (4); the operating mechanism (2) drives the insulating shaft (4) to rotate; under the cooperation of the driving member (43) and a driven member (62) arranged on the moving contact mechanism, the moving contact mechanism moves in the sealed chamber (11) driven by the insulating shaft (4) to realize the operation of the double-break switch device; The insulating shaft (4) comprises a plurality of insulating rod bodies (41) and a plurality of connecting shafts (42), the insulating rod bodies (41) and the connecting shafts (42) are arranged alternately in sequence, a shaft shoulder (421) is arranged on the periphery of the connecting shaft (42), and a driving member (43) for transmitting power of the connecting shaft (42) to the moving contact mechanism is sleeved on the shaft shoulder (421); The transmission connecting shaft (3) and the connecting shaft (42) are made of metal material, and the insulating rod body (41) is made of epoxy resin casting, and the transmission connecting shaft (3) and the connecting shaft (42) are cast into a whole; Both ends of the connecting shaft (42) are convex arcs (422) protruding outwards, and one end of the transmission connecting shaft (3) is provided with a connecting convex arc (31) so that when the insulating rod body (41) is cast with epoxy resin, the convex arc (422) and the connecting convex arc (31) are completely fixed and clamped in the insulating rod body (41).

2. The three-position switch according to claim 1, characterized in that The operating mechanism (2) is arranged outside the common housing (1), and a connecting hole is provided on the side wall of the common housing (1) adjacent to the operating mechanism (2). A sealing device for sealing the common housing (1) is provided in the connecting hole. The sealing device is provided with a connecting groove. A bearing (38) for matching the transmission connecting shaft (3) is provided in the connecting groove. The transmission connecting shaft (3) passes through the connecting groove to connect the insulating shaft (4) with the operating mechanism (2). The sealing device enables the power transmission between the operating mechanism (2) and the transmission connecting shaft (3) to be in a sealed state.

3. The three-position switch according to claim 2, characterized in that: The sealing device comprises a sealing body (33), the middle part of which protrudes to form a central protrusion that can be inserted into the connecting hole, and the edge surrounding the central protrusion is located between the common box shell (1) and the operating mechanism (2); the connecting groove is arranged through the middle part of the central protrusion, a bearing (38) and an internal sealing structure are arranged in the connecting groove, and an external sealing structure is arranged around the edge of the central protrusion on one side of the sealing body (33) close to the common box shell (1).

4. The three-position switch according to claim 3, characterized in that: The connecting groove is a structure with thick ends and thin middle. The connecting groove serves as a mounting groove (33a) at one end close to the operating mechanism (2), and as a shielding groove (33b) at one end close to the transmission connecting shaft (3). The thinner portion between the shielding groove (33b) and the mounting groove (33a) serves as a sealing groove, and an internal sealing structure is arranged in the sealing groove.

5. The three-position switch according to claim 4, characterized in that: The internal sealing structure comprises an end cover (34) and a lip seal ring (36). The end cover (34) is located at one end close to the operating mechanism (2). The outer diameter of the end cover (34) is larger than the outer diameter of the seal groove. The end cover (34) is fixedly installed in the installation groove (33a). An oil seal (35) is provided on the side of the end cover (34) away from the seal groove. A plurality of lip seal rings (36) are stacked and arranged on one side of the seal groove close to the bearing (38). A seal ring partition (37) is provided between adjacent lip seal rings (36). The bearing (38) is arranged in the seal groove. One end of the transmission connection shaft (3) for connecting with the operating mechanism (2) passes through the bearing (38), the lip seal ring (36), the oil seal (35) and the end cover (34) in sequence to be connected with the operating mechanism (2). The other end of the transmission connection shaft (3) is provided with a connection convex arc (31). The connection convex arc (31) extends into the shielding groove (33b).

6. The three-position switch according to claim 3, characterized in that: An annular groove surrounding the central protrusion is provided on one side of the sealing body (33) close to the common box shell (1), and an external sealing structure is provided in the annular groove, wherein the external sealing structure is an airtight sealing ring (91).

7. The three-position switch according to claim 1, characterized in that: The moving contact mechanism comprises a moving contact and a supporting structure, wherein the moving contact is provided with a driven member (62) cooperating with a driving member (43), the supporting structure is provided with a guide groove (641) for movement of the moving contact and a receiving groove (642) for rotationally mounting an insulating shaft (4), and a connecting groove for cooperation between the driving member (43) and the driven member (62) is provided between the receiving groove (642) and the guide groove (641).

8. The three-position switch according to claim 7, characterized in that: The receiving groove (642) includes a shielding groove (c1+c2), a lubrication groove (b1+b2) and a driving groove (a1+a2) with different inner diameters. The inner diameter of the lubrication groove (b1+b2) is the smallest, and the inner diameter of the lubrication groove (b1+b2) is greater than or equal to the outer diameter of the shoulder (421) of the connecting shaft (42). The inner diameter of the shielding groove (c1+c2) is greater than or equal to the outer diameter of the convex arc (422) of the connecting shaft (42). The driving groove (a1+a2) is located in the middle of the receiving groove (642) for accommodating the driving member (43). The two lubrication grooves (b1+b2) are symmetrically arranged on both sides of the driving groove (a1+a2) for accommodating the shoulder (421) of the connecting shaft (42). The shielding grooves (c1+c2) are symmetrically arranged at both ends of the receiving groove (642) for accommodating the convex arc (422) of the connecting shaft (42).

9. The three-position switch according to claim 1, characterized in that: The movable contact mechanism is fixed on an insulating basin (12) in a sealed chamber (11), and the insulating basin (12) enables the isolation contact seat mechanism, the grounding contact seat mechanism and the movable contact mechanism to maintain a coaxial line.

10. The three-position switch according to claim 1, characterized in that: The isolation contact seat mechanism comprises an isolation contact seat (51), a mounting groove is provided in the middle of the isolation contact seat (51), a self-powered arc-striking contact (52) is installed in the mounting groove, one end of the self-powered arc-striking contact (52) is in a plum blossom shape, the plum blossom-shaped end of the self-powered arc-striking contact (52) contacts the moving contact and can be retracted when receiving a squeezing force.

11. The three-position switch according to claim 1, characterized in that: The grounding contact seat mechanism comprises a grounding contact seat (71) and a grounding insulator (72); the grounding contact seat (71) is arranged at one end in the sealed chamber (11); one end of the grounding insulator (72) is connected to the grounding contact seat (71); the other end of the grounding insulator (72) passes through the common box shell (1) and extends out of the sealed chamber (11); and a grounding copper busbar (73) is provided at the end extending out of the sealed chamber (11).

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