CN115966433A

CN115966433A - Anti-oxidation device for contact of outdoor isolating switch of 110kV or below

Info

Publication number: CN115966433A
Application number: CN202211511235.8A
Authority: CN
Inventors: 马云; 汤建磊; 吴波; 李源; 吴封禹; 马德收; 梁凯; 蒋羽鹏; 陈道杨; 杨志; 孙若峰; 张羽翔; 刘成君; 潘巍; 董朝理; 袁忠; 张毅; 金磊; 杨丽芬; 罗福强
Original assignee: Yunnan Power Grid Co Ltd
Current assignee: Yunnan Power Grid Co Ltd
Priority date: 2022-11-29
Filing date: 2022-11-29
Publication date: 2023-04-14

Abstract

The invention discloses an anti-oxidation device for contacts of an outdoor isolating switch of 10kV or below, which comprises a protection unit, a first lock unit and a second lock unit, wherein the protection unit comprises a protective cover, a cavity is formed in the wall of the protective cover, a contact mounting shell is inserted into the protective cover, a contact is fixedly arranged at the tail end of the contact mounting shell, the first lock unit comprises a clamping plate, the clamping plate is movably arranged in the formed groove a, a pull rod is movably arranged on the upper surface of the clamping plate, a fixing block is movably hinged at the tail end of the pull rod, the second lock unit comprises a cylindrical rod, chamfering processing is carried out on the upper surface of the cylindrical rod, the cylindrical rod is lapped on the upper surface of a stop block, the stop block is attached to the inner wall of the cavity of the protective cover, and a fixing rod is fixedly arranged on the surface of the stop block.

Description

Anti-oxidation device for contact of outdoor isolating switch of 110kV or below

Technical Field

The invention relates to a protection device, in particular to an anti-oxidation device for a contact of an outdoor isolating switch of 110kV or below.

Background

The isolating switch is the most used equipment in 110kV high-voltage switch electrical equipment, and can visually reflect that the equipment has obvious disconnection points with the operation equipment in a circuit, so that the equipment is conveniently isolated and maintained, and the normal operation of the isolating switch is the guarantee of the safe operation of a power grid. At present, part of isolating switches are in a standby state due to the requirement of a matching operation mode, and a moving contact is exposed to sunlight, rainwater or a polluted environment for a long time, so that the oxidation of the moving contact causes the increase of contact resistance and generates heat. The standby isolating switch is forced to be powered off for maintenance when needing to be put into operation. The risk of the power grid and the operation risk are increased, and the stable operation of the power grid is damaged.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments, and in this section as well as in the abstract and the title of the invention of this application some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions are not intended to limit the scope of the invention.

This patent mainly solves 110kV and following outdoor horizontal rotation type isolator contact and exposes in the air for a long time, and sunshine insolatees and the contact oxidation corrosion problem that rainwater corrodes and lead to.

An anti-oxidation device for contacts of outdoor disconnecting switches of 110kV or below comprises,

the protection unit comprises a protection cover, a cavity is formed in the wall of the protection cover, a contact mounting shell is inserted in the protection cover, and a contact is fixedly arranged at the tail end of the contact mounting shell;

the first locking unit comprises a clamping plate, the clamping plate is movably arranged in the groove, a pull rod is movably arranged on the upper surface of the clamping plate, the tail end of the pull rod is movably hinged with a fixed block, a pair of first connecting rods are movably arranged on the surface of the fixed block, and the pair of first connecting rods are symmetrically distributed on the surface of the fixed block; and (c) a second step of,

the second lock catch unit comprises a cylindrical rod, the upper surface of the cylindrical rod is subjected to chamfering treatment, the cylindrical rod is arranged on the upper surface of the stop block in an overlapping mode, the stop block is arranged on the inner wall of the cavity of the protective cover in a laminating mode, a fixed rod is fixedly arranged on the surface of the stop block, and a second slider is fixedly arranged at the tail end of the fixed rod.

As an improvement of the invention, the lower surface of the protective cover is fixedly provided with a character groove, the tail end of the character groove is movably inserted with a push rod, the shape of the push rod is the same as that of the character groove, and the tail end of the push rod is fixedly provided with a ball.

As an improvement of the invention, a countersunk groove is formed in the lower surface of the inner cavity of the protective cover, a cylindrical rod is movably inserted in the countersunk groove, the tail end of the cylindrical rod is movably inserted in a mounting hole formed in the bottom of the contact mounting shell, the contact mounting shell is in a stepped shape, and a plurality of transverse plates are formed on the surface of the contact mounting shell.

As an improvement of the invention, the left side and the right side of the fixed block are fixedly provided with first synchronous rods, the tail ends of the first synchronous rods on the two sides are fixedly provided with first sliding blocks, the first sliding blocks are arranged in the limiting guide rails in a sliding manner, and the limiting guide rails are fixedly arranged in cavities formed in the inner sides of the walls of the protection cover plates.

As an improvement of the invention, the tail ends of the two first connecting rods are slidably provided with lantern rings, the lantern rings are slidably arranged on the first limiting rods, the first limiting rods are fixedly arranged on the inner wall of the protective cover, the surfaces of the lantern rings are movably provided with swing rods, the swing rods are movably provided with driven racks, and the driven racks are in a vertical state.

As an improvement of the invention, the surface of the driven rack is engaged with a driving gear, the surface of the driving gear is engaged with a driving rack, the tail end of the driving rack is fixedly provided with a fixture block, the fixture block is slidably arranged on the surface of the positioning guide rail, the lower surface of the driven rack is provided with a limiting sleeve rod, and the limiting sleeve rod is inserted and arranged in the protective cover.

As an improvement of the invention, a cylindrical cavity is formed in the fixture block, the size of the cylindrical cavity is matched with that of the ball, limiting sleeves are fixedly arranged on two sides of the fixture block, a return spring is fixedly arranged in each limiting sleeve, a protrusion is fixedly arranged at the tail end of each return spring, the outer diameter size of each protrusion is matched with the inner diameter size of each limiting sleeve, and chamfering treatment is carried out on the surface of each protrusion.

As an improvement of the invention, the tail end of the limiting sleeve rod is movably provided with a second connecting rod, the tail end of the second connecting rod is movably provided with a sliding sleeve, the second connecting rod and the sliding sleeve are obliquely arranged, the sliding sleeve is arranged on the second limiting rod in a sliding manner, and the second limiting rod is welded in the inner cavity of the protective cover.

As an improvement of the invention, the tail end of the sliding sleeve is movably provided with a swing arm, the swing arm is movably provided with a second sliding block, and the second sliding block is arranged in a sliding groove formed in the bottom of the protective cover in a sliding mode.

As a modification of the invention, a second synchronous rod is fixedly arranged on the surface of the second sliding block, and another second sliding block with the same function is fixedly arranged at the tail end of the second synchronous rod.

The beneficial effects of the invention are: the protection device is arranged at the left moving contact and the right moving contact of the isolating switch through the push rod, and the operation push rod is pulled out after the protection device is arranged in place, so that the contact is firm, and the operation is convenient. Because the use scene is the electric power high-risk place, therefore regard isolator as electrified equipment at any moment. By adopting the protection device, the left and right moving contacts of the standby isolating switch are protected from being exposed to sunlight, rainwater or polluted environment for a long time, the moving contacts are oxidized to increase the contact resistance to generate heat, and the operation is convenient and fast.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

fig. 1 is a schematic three-dimensional structure diagram of an anti-oxidation device for contacts of an outdoor disconnecting switch of 110kV and below, which is provided by the invention;

FIG. 2 is a three-dimensional view of the position A of the contact anti-oxidation device for the outdoor disconnecting switch of 110kV and below, provided by the invention;

FIG. 3 is a structural view of a first locking unit in the contact oxidation prevention device for the outdoor disconnecting switch of 110kV and below, which is provided by the invention;

fig. 4 is a cross-sectional view at the position B of the anti-oxidation device for the contact of the outdoor disconnecting switch of 10kV and below, which is provided by the invention;

FIG. 5 is an internal view of a first locking unit in the contact oxidation prevention device for the outdoor disconnecting switch of 110kV and below, which is provided by the invention;

fig. 6 is a structural view of a second locking unit in the contact oxidation prevention device for the outdoor disconnecting switch of 110kV and below.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Example 1:

referring to fig. 1 to 6, the embodiment provides an anti-oxidation device for contacts of outdoor disconnectors of 110kV and below, comprising,

the protection unit 100 comprises a protection cover 102, a cavity is formed in the wall of the protection cover 102, a contact mounting shell 101 is inserted into the protection cover 102, a contact 104 is fixedly arranged at the tail end of the contact mounting shell 101, and the contact 104 is sleeved through the protection cover 102, so that the contact 104 in the protection cover 102 can be protected.

First latch unit 200, including cardboard 209, cardboard 209 activity sets up inside the recess 209a of seting up, and cardboard 209 upper surface activity is provided with pull rod 208, the terminal activity of pull rod 208 hinges and is provided with fixed block 207, fixed block 207 surface activity is provided with a pair of head rod 206, and a pair of head rod 206 is the symmetric distribution on fixed block 207 surface, install through cardboard 209 slope, thereby fixed effect has been played, and fixed block 207 can control the wobbling position of cardboard 209 this moment.

Second locking unit 300, including cylinder pole 308, cylinder pole 308 upper surface carries out the chamfer and handles, and cylinder pole 308 overlap joint sets up at dog 307 upper surface, and dog 307 laminating sets up at protective cover 102 cavity inner wall, and dog 307 fixed surface is provided with dead lever 306, the fixed second slider 305 that is provided with in dead lever 306 end, remove through second slider 305, thereby can promote dog 307 this moment, thereby played the effect of jacking cylinder pole 308, the effect of fixed contact installation shell 101 bottom has finally been played, and mutually support with cardboard 209, the stability of connecting has been improved.

Example 2:

referring to fig. 1 to 6, this embodiment provides an anti-oxidation device for contacts of outdoor disconnecting switches of 110kV and below, which is different from embodiment 1, and comprises,

the lower surface of the protective cover 102 is fixedly provided with a T-shaped groove 103a, the tail end of the T-shaped groove 103a is movably inserted with a push rod 103, the shape of the push rod 103 is the same as that of the T-shaped groove 103a, and the tail end of the push rod 103 is fixedly provided with a round ball 103b, so that the protective cover 102 and the push rod 103 can be ensured to form a whole through the mutual matching of the T-shaped groove 103a and the push rod 103, and the possibility of the self-rotation of the protective cover 102 under the condition of external force is reduced.

Referring to fig. 1 to 6, a countersunk groove 106 is formed on the lower surface of the inner cavity of the protective cover 102, a cylindrical rod 308 is movably inserted into the countersunk groove 106, the end of the cylindrical rod 308 is movably inserted into a mounting hole formed at the bottom of the contact mounting casing 101, the contact mounting casing 101 is stepped, a plurality of transverse plates 105 are formed on the surface of the contact mounting casing 101, the distance of the protective cover 102 moving to the right is limited by the mutual matching of the transverse plates 105 and the clamping plates 209,

referring to fig. 1 to 6, first synchronizing rods 207a are fixedly disposed on the left and right sides of the fixing block 207, first sliding blocks 207b are fixedly disposed at the ends of the first synchronizing rods 207a on the two sides, the first sliding blocks 207b are slidably disposed inside the limiting guide rails 207c, the limiting guide rails 207c are fixedly disposed in cavities formed in the inner side of the plate wall of the protecting cover 102, and the fixing block 207 can move only in the horizontal direction by moving the first sliding blocks 207b inside the limiting guide rails 207 c.

Referring to fig. 1 to 6, the ends of two first connecting rods 206 are slidably provided with collars 205, the collars 205 are slidably disposed on first limiting rods 205a, the first limiting rods 205a are fixedly disposed on the inner wall of the protective cover 102, the surfaces of the collars 205 are movably provided with swing rods 204, the swing rods 204 are movably provided with driven racks 203, the driven racks 203 are in a vertical state, and the driven racks 203 move up and down through the driven racks 203, so that under the action of the swing rods 204, the collars 205 start to move in opposite directions to drive the fixing block 207 to move horizontally.

Referring to fig. 1 to 6, a driving gear 202 is arranged on the surface of a driven rack 203 in a meshed manner, a driving rack 201b is arranged on the surface of the driving gear 202 in a meshed manner, a fixture block 201 is fixedly arranged at the tail end of the driving rack 201b, the fixture block 201 is slidably arranged on the surface of a positioning guide rail 201a, a limiting sleeve rod 301 is arranged on the lower surface of the driven rack 203, the limiting sleeve rod 301 is inserted into the protective cover 102, the driven rack 203 is driven to move in the opposite direction by the movement of the driving rack 201b, and the reversing purpose is achieved

Referring to fig. 1 to 6, a cylindrical cavity is formed inside the fixture block 201, the size of the cylindrical cavity is matched with the size of the round ball 103b, a limiting sleeve 210 is fixedly arranged on two sides of the fixture block 201, a return spring 211 is fixedly arranged inside the limiting sleeve 210, a protrusion 211a is fixedly arranged at the tail end of the return spring 211, the outer diameter of the protrusion 211a is matched with the inner diameter of the limiting sleeve 210, chamfering is performed on the surface of the protrusion 211a, the push rod 103 continues to move downwards, the protrusion 211a at the moment can be extruded by the round ball 103b at the tail end of the push rod 103, the protrusion 211a begins to shrink towards the inside of the limiting sleeve 210, after the shrinkage is carried out to a certain degree, the round ball 103b can be separated from the limiting sleeve 210 at the moment, and the push rod 103 can be separated from the protective cover 102 at the moment.

Example 3:

referring to fig. 1 to 6, this embodiment provides an outdoor disconnector contact oxidation preventing device of 110kV and below, which is different from embodiments 1 and 2, comprising,

the second connecting rod 302 is movably arranged at the tail end of the limiting sleeve rod 301, the sliding sleeve 303 is movably arranged at the tail end of the second connecting rod 302, the second connecting rod 302 and the sliding sleeve 303 are installed in an inclined mode, the sliding sleeve 303 is arranged on the second limiting rod 303a in a sliding mode, the second limiting rod 303a is welded in the inner cavity of the protective cover 102, and the sliding sleeve 303 at the moment is pushed to move along the second limiting rod 303a through movement of the limiting sleeve rod 301.

Referring to fig. 1 to 6, a swing arm 304 is movably disposed at the end of the sliding sleeve 303, and a second sliding block 305 is movably disposed on the swing arm 304, and the second sliding block 305 is slidably disposed in a sliding slot 305a formed at the bottom of the protective cover 102. The second slider 305 at this time starts to move along the slide groove 305a by the swing arm 304 provided.

Referring to fig. 1 to 6, a second synchronization rod 305b is fixedly disposed on a surface of the second slider 305, and another second slider 305 having the same function is fixedly disposed at a tail end of the second synchronization rod 305b, and the two second synchronization rods 305b can be driven to move by the disposed second synchronization rod 305b, so as to achieve the purpose of controlling the two cylindrical rods 308 to move up and down.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

The working principle is as follows: when the contact 104 needs to be protected, the push rod 103 is inserted into the T-shaped groove 103a on the ground, at this time, the ball 103b at the end of the push rod 103 can move into the fixture block 201, at this time, the fixture block 201 will move upward, the driving rack 201b at the end at this time synchronously starts to move upward, and in the movement of the driving rack 201b, the two driving gears 202 at the side edges at this time start to rotate, the driven rack 203 meshed and connected with the driving gears starts to move downward, and at this time, the driven rack 203 and the position-limiting sleeve rod 301 synchronously start to move downward.

When the driven rack 203 starts to move downwards, the position of the swing rod 204 at this time will move, and finally the collar 205 at this time will be pushed to start to move towards both sides along the first limiting rod 205a, and the position of the first connecting rod 206 movably connected with the collar 205 at this time starts to move, and the fixed block 207 at this time will be pulled to start to move towards the right side, and at this time, due to the fact that the first sliding block 207b and the limiting guide rail 207c are received, the position where the fixed block 207 moves at this time is in horizontal movement, so that the position of the pull rod 208 which moves on the surface of the fixed block 207 changes, and the clamping plate 209 at this time can be pulled to start to contract towards the inside of the groove 207 a.

When the position-limiting sleeve rod 301 starts to move downwards, the second connecting rod 302 pushes the sliding sleeve 303 to move along the outer side of the second position-limiting rod 303a at the moment, the position of the swing arm 304 at the moment changes synchronously, the second sliding block 305 is pulled to move right along the sliding groove 305a at the moment, the stop 307 is pulled by the fixing rod 306 to be separated from the cylindrical rod 308, the cylindrical rod 308 falls at the moment, after the cylindrical rod 308 falls to a certain extent, the cylindrical rod 308 is blocked by the countersunk head groove 106, and the tail end of the cylindrical rod 308 is hidden inside the countersunk head groove 106.

Then, at this time, an operator needs to lift the protection cover 102 through the push rod 103, and finally the protection cover 102 at this time is sleeved outside the contact mounting housing 101, at this time, the push rod 103 needs to be pulled downward, and the pulling enables the driving rack 201b to move downward, and some rows of the driving rack are opposite to the transmission direction, which is not described herein in detail, first, the clamping plate 209 at this time starts to rotate downward, so that the clamping plate 209 contacts with the transverse plate 105 at the tail end, and it is ensured that the protection cover 102 at this time cannot move rightward, the clamping plate 209 is obliquely arranged and contacts with the transverse plate 105 at this time, and the stopper 307 at the lower side returns to the lower side of the cylindrical rod 308 again, so that the cylindrical rod 308 is lifted up, the cylindrical rod 308 is inserted into the contact mounting housing 101 at this time, and finally the mounting of the protection unit 100 is achieved.

When the push rod 103 is installed in place, the push rod 103 continues to move downwards, the spherical ball 103b at the tail end of the push rod 103 presses the protrusion 211a at the moment, the protrusion 211a begins to shrink towards the inside of the limiting sleeve 210, after the protrusion shrinks to a certain degree, the spherical ball 103b can be separated from the limiting sleeve 210 at the moment, and the push rod 103 can be separated from the protective cover 102 at the moment.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims

1. The utility model provides a 110kV and following outdoor isolator contact anti oxidation device which characterized in that: comprises the steps of (a) preparing a substrate,

the protection unit (100) comprises a protection cover (102), a cavity is formed in the inner wall of the protection cover (102), a contact mounting shell (101) is inserted into the protection cover (102), and a contact (104) is fixedly arranged at the tail end of the contact mounting shell (101);

the first locking unit (200) comprises a clamping plate (209), the clamping plate (209) is movably arranged in a groove (209 a) formed in the first locking unit, a pull rod (208) is movably arranged on the upper surface of the clamping plate (209), the tail end of the pull rod (208) is movably hinged with a fixing block (207), a pair of first connecting rods (206) is movably arranged on the surface of the fixing block (207), and the pair of first connecting rods (206) are symmetrically distributed on the surface of the fixing block (207); and the number of the first and second groups,

the second locking unit (300) comprises a cylindrical rod (308), the upper surface of the cylindrical rod (308) is subjected to chamfering treatment, the cylindrical rod (308) is arranged on the upper surface of a stop block (307) in an overlapping mode, the stop block (307) is arranged on the inner wall of the cavity of the protection cover (102) in a fitting mode, a fixing rod (306) is fixedly arranged on the surface of the stop block (307), and a second sliding block (305) is fixedly arranged at the tail end of the fixing rod (306).

2. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 1, wherein: the lower surface of the protective cover (102) is fixedly provided with a T-shaped groove (103 a), the tail end of the T-shaped groove (103 a) is movably inserted with a push rod (103), the shape of the push rod (103) is the same as that of the T-shaped groove (103 a), and the tail end of the push rod (103) is fixedly provided with a ball (103 b).

3. The 110kV and the following outdoor isolating switch contact anti-oxidation device as set forth in claim 1 or 2, wherein: the lower surface of the inner cavity of the protective cover (102) is provided with a countersunk groove (106), a cylindrical rod (308) is movably inserted into the countersunk groove (106), the tail end of the cylindrical rod (308) is movably inserted into a mounting hole formed in the bottom of the contact mounting shell (101), the contact mounting shell (101) is in a step shape, and the surface of the contact mounting shell (101) is provided with a plurality of transverse plates (105).

4. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 3, wherein: the left side and the right side of the fixing block (207) are fixedly provided with first synchronous rods (207 a), the tail ends of the first synchronous rods (207 a) on the two sides are fixedly provided with first sliding blocks (207 b), the first sliding blocks (207 b) are arranged inside the limiting guide rails (207 c) in a sliding mode, and the limiting guide rails (207 c) are fixedly arranged in cavities formed in the inner side of the plate wall of the protective cover (1).

5. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 4, wherein: the tail ends of the two first connecting rods (206) are provided with lantern rings (205) in a sliding mode, the lantern rings (205) are arranged on first limiting rods (205 a) in a sliding mode, the first limiting rods (205 a) are fixedly arranged on the inner wall of the protective cover (102), the surfaces of the lantern rings (205) are movably provided with swing rods (204), the swing rods (204) are movably provided with driven racks (203), and the driven racks (203) are in a vertical state.

6. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 5, wherein: driven rack (203) surface toothing is provided with drive gear (202), drive gear (202) surface toothing is provided with drive rack (201 b), drive rack (201 b) end is fixed and is provided with fixture block (201), and fixture block (201) slide and set up on location guide rail (201 a) surface, driven rack (203) lower surface sets up and is provided with spacing loop bar (301), and spacing loop bar (301) are pegged graft and are set up inside at guard shield (102).

7. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 6, wherein: the fixture block (201) is internally provided with a cylindrical cavity, the size of the cylindrical cavity is matched with the size of the round ball (103 b), the two sides of the fixture block (201) are fixedly provided with a limiting sleeve (210), the inside of the limiting sleeve (210) is fixedly provided with a return spring (211), the tail end of the return spring (211) is fixedly provided with a protrusion (211 a), the outer diameter of the protrusion (211 a) is matched with the inner diameter of the limiting sleeve (210), and the surface of the protrusion (211 a) is chamfered.

8. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 7, wherein: the tail end of the limiting sleeve rod (301) is movably provided with a second connecting rod (302), the tail end of the second connecting rod (302) is movably provided with a sliding sleeve (303), the second connecting rod (302) and the sliding sleeve (303) are installed in an inclined mode, the sliding sleeve (303) is arranged on a second limiting rod (303 a) in a sliding mode, and the second limiting rod (303 a) is welded in the inner cavity of the protective cover (102).

9. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in any one of claims 5 to 8, wherein: the tail end of the sliding sleeve (303) is movably provided with a swing arm (304), the swing arm (304) is movably provided with a second sliding block (305), and the second sliding block (305) is arranged in a sliding groove (305 a) formed in the bottom of the protective cover (102) in a sliding mode.

10. The 110kV and following outdoor isolating switch contact anti-oxidation device as claimed in claim 9, wherein: a second synchronous rod (305 b) is fixedly arranged on the surface of the second sliding block (305), and the tail end of the second synchronous rod (305 b) is fixedly provided with another second sliding block (305) with the same function.