JP5989445B2 - Shock absorber for operating mechanism for switchgear - Google Patents

Description

  An embodiment of the present invention is an apparatus used in an operating mechanism for an opening / closing device that operates a moving body including an electrical contact to operate an opening / closing operation of the opening / closing device, and is a shock absorber for braking the operated moving body About.

  In general, a high-voltage switchgear is provided with an operation mechanism that drives a moving body including an electrical contact at high speed. The operation mechanism operates the opening / closing operation (shut-off operation and closing operation) of the opening / closing device by reciprocally driving the moving body including the electrical contacts between the open and closed positions. In order for the switchgear to exhibit excellent blocking performance, it is important for the operating mechanism to drive the moving body including the electrical contact at a high speed until just before reaching the end position of the blocking operation.

  In order to realize such an operation of the moving body, a shock absorber is adopted as the operation mechanism. The shock absorber is a device that decelerates and brakes a moving body that moves at high speed just before the end of the blocking operation. Patent document 1 etc. are proposed as a prior art example of the buffer device used for the operating mechanism for switchgear.

  Usually, the shock absorber is provided with a piston rod so as to collide with a moving body including an electrical contact. A piston is attached to the piston rod. The piston rod and the piston are slidably disposed inside the cylinder. The cylinder is filled with hydraulic oil that is compressed by the piston. A packing is provided at a sliding portion between the cylinder and the piston rod. The piston rod is provided with a rod return spring for returning to the initial position.

  In the shock absorber having the above configuration, the moving body driven at high speed collides with the end of the piston rod just before the closing operation of the opening / closing device is completed. The piston rod that collides with the moving body enters the cylinder at a high speed while compressing the rod return spring in a shocking manner. As the piston rod enters, the piston also enters the cylinder at a high speed, and the piston rapidly compresses the hydraulic oil. The rapidly compressed hydraulic oil exerts a reaction force to push back the piston. This reaction force is transmitted to the moving body via the piston rod and brakes the moving body.

  According to the above shock absorber, only when the closing operation of the switchgear is finished, the braking force is generated, the speed of the moving body including the electrical contact can be reduced, and the moving body can be stopped. Therefore, the operation mechanism can drive the moving body including the electrical contact at a high speed until shortly before reaching the end position of the blocking operation.

  An opening / closing device operated by such an operation mechanism can exhibit excellent blocking performance. Further, in the closing operation of the switchgear, the engagement between the moving body including the electrical contact and the piston rod is canceled, so that the piston rod returns to the initial position by the restoring force of the compressed rod return spring, and the piston Also return to the initial position.

JP 2011-80566 A

  However, the conventional shock absorber has the following problems. That is, when the piston rod receives the impact of the moving body and enters the cylinder at a high speed just before the closing operation of the opening / closing device, the rod return spring is rapidly compressed along with the operation of the piston rod and deformed by the impact. Happens. Generally, when a spring is deformed due to an impact, the end of the spring is locally deformed, so that the strands of the spring are easily brought into close contact with each other. As a result, the rod return spring may be deformed or damaged, and the spring strength may be reduced.

  In order to increase the braking capacity of the shock absorber, it is effective to increase the stroke (displacement amount) of the piston rod. To this end, it is necessary to increase the spring length of the rod return spring. However, when the free length of the rod return spring is extended and the stroke (displacement amount) of the piston rod is also extended, the rod return spring is likely to buckle. If the rod return spring buckles, not only will the spring force not be generated as designed, but the spring wire will contact the surrounding structure. As a result, the rod return spring may be deformed or damaged, and the spring strength may also decrease.

  The shock absorber of the switchgear operating mechanism according to the present embodiment is made to solve the above-described problems. An object of the present embodiment is to improve reliability by avoiding a decrease in spring strength due to deformation or damage of the spring or buckling.

In order to achieve the above object, a shock absorber for an operating mechanism for a switching device according to an embodiment of the present invention opens and closes the switching device by reciprocating a moving body including an electrical contact between an open and a closed position. A shock absorber used for an operation mechanism for operating an operation includes the following (1) to (6).
(1) Outer cylinder and inner cylinder arranged coaxially.
(2) A first piston slidably disposed inside the inner cylinder.
(3) A second piston slidably disposed inside the outer cylinder.
(4) A piston rod that is slidably disposed on the second piston and is fixed to the first piston.
(5) A high-pressure chamber formed by being surrounded by the inner cylinder and the first piston and filled with hydraulic oil that is compressed by the piston rod and the first piston being pushed in.
(6) A return spring disposed between the outer cylinder and the second piston and biased in a direction to separate the outer cylinder and the second piston.

Sectional drawing which shows the initial state of 1st Embodiment which concerns on this invention. Sectional drawing which shows the braking operation completion state of the buffering device of FIG. Sectional drawing which shows the return middle state of the buffering device of FIG. The AA arrow directional view of the shock absorber of FIG. Sectional drawing which shows the initial state of 2nd Embodiment which concerns on this invention. Sectional drawing which shows the braking operation completion state of the shock absorber of FIG. Sectional drawing which shows the initial state of 3rd Embodiment which concerns on this invention. Sectional drawing which shows the braking operation completion state of the shock absorber of FIG. Sectional drawing which shows the initial state of 4th Embodiment which concerns on this invention.

Hereinafter, an example of an embodiment of a shock absorber for an opening / closing device operating mechanism according to the present invention will be specifically described with reference to the drawings.
[First Embodiment]
(Constitution)

  A first embodiment according to the present invention will be described with reference to FIGS. 1 is a cross-sectional view showing an initial state of the shock absorber 10 of the opening / closing device operating mechanism, FIG. 2 is a cross-sectional view showing a braking operation completion state of the shock absorber 10 shown in FIG. 1, and FIG. 3 is a shock absorber shown in FIG. Sectional drawing which shows the state in the middle of the return operation | movement which transfers to the initial state from the braking operation completion state of the apparatus 10, FIG. 4 is AA arrow directional view of the buffering apparatus 10 shown in FIG.

  As shown in FIGS. 1 and 2, the switching device is provided with an operating mechanism for operating the opening / closing operation of the movable contact 1 that is an electrical contact. The operation mechanism is configured to operate a cutoff operation or a closing operation of the movable contact 1 in response to a cutoff command or a closing command from a control device (not shown).

(Configuration of operation mechanism)
The operating mechanism is provided with a cutoff spring 2 that opens and closes according to a command from a control device (not shown). The movable end 3 of the cutoff spring 2 is attached to the cutoff spring receiver 4. A spring rod 5 is fixed to the cutoff spring receiver 4. The spring rod 5 is coupled to the movable contact 1 through a connecting portion 8.

  Here, the member group which operates integrally with the movable contact 1 is the cutoff spring 2, the cutoff spring receiver 4, and the spring rod 5, and a movable body including an electrical contact is constituted by these members. This moving body is housed inside the support structure 6. A stop plate 7 is fixed to the support structure 6 so as to face the blocking spring receiver 4.

(Configuration of shock absorber)
In the stop plate 7, the shock absorber 10 is fixed to the surface opposite to the surface on which the support structure 6 is fixed. The shock absorber 10 is for reducing the speed of the moving body including the movable contact 1. The shock absorber 10 is a device that encloses hydraulic oil 24 (detailed later) and generates a braking force by compressing the hydraulic oil 24 slightly before the movable contact 1 reaches the end position of the operation. is there.

  The components of the shock absorber 10 are as follows. The shock absorber 10 includes a return spring receiver 19, a stud 26, a bottom plate 23, a bottom lid 17, an outer cylinder 11 and an inner cylinder 12 having the same central axis, and first and second pistons 13 and 14. A single piston rod 15, a return spring 20, a high pressure chamber 25, a low pressure chamber 27, a liquid chamber 28, and three packings 16, 18, and 22 are included.

The components of the shock absorber 10 will be described in detail.
(Return spring support, stud, bottom plate, bottom lid)
The return spring receiver 19 and the stud 26 are fixed to the stop plate 7. A plurality of studs 26 are arranged so as to surround the return spring receiver 19 from the outside. The stud 26 extends in a direction opposite to the support structure 6 of the operation mechanism. The bottom plate 23 is fixed to the end portion of the stud 26. The bottom cover 17 is disposed adjacent to the bottom plate 23. The bottom cover 17 is fitted to the end of the outer cylinder 11 and is in contact with the end of the inner cylinder 12.

(Outer cylinder and inner cylinder)
The outer cylinder 11 is disposed so as to be sandwiched between the return spring receiver 19 and the bottom plate 23. For this reason, the outer cylinder 11 is set to a length over the entire area of the stud 26 in the length direction.

  The inner cylinder 12 is movably disposed inside the outer cylinder 11 with a predetermined gap, and is set to a length that is about half of the length of the outer cylinder 11. A plurality of through holes 21 are opened in the inner cylinder 12. A space formed by a gap between the inner cylinder 12 and the outer cylinder 11 is a low pressure chamber 27.

  An oil return path 12a is opened at the end of the inner cylinder 12 on the bottom lid 17 side. At both ends of the inner cylinder 12, a notch 12 c and a protrusion 12 d are disposed, and the protrusion 12 d is disposed in substantially the same plane as the through hole 21. Further, a groove 12e is disposed on the end surface of the inner cylinder 12 that contacts the second piston 14 (the protrusion 12d and the groove 12e are shown in FIG. 4).

(First piston and second piston)
The first piston 13 is slidably disposed inside the inner cylinder 12, and the second piston 14 is slidably disposed inside the outer cylinder 11. In the initial state of the shock absorber 10 shown in FIG. 1, the second piston 14 is stationary at a position in contact with the end of the inner cylinder 12, and the first piston 13 is stationary at a position in contact with the second piston 14.

  The first piston 13 and the second piston 14 are adjacent to each other as shown in FIG. 1 in the initial state, and are moved away from each other as shown in FIG. 2 when the braking operation is completed. . When the movable contact 1 shifts from the on state to the shut off state (from the state of FIG. 1 to the state of FIG. 2), the shock absorber 10 performs a braking operation.

  At this time, the first piston 13 moves to the left in the drawing, and the second piston 14 moves to the right in the drawing. That is, the first piston 13 and the second piston 14 are moved away from each other. This is because the piston rod 15 enters the space filled with the hydraulic oil 24 as will be described later, and the second piston 14 moves to the right by the volume change. That is, the second piston 14 operates so as to absorb the volume change of the hydraulic oil 24.

(Piston rod)
The piston rod 15 is slidably disposed with respect to the second piston 14. The piston rod 15 enters a space filled with the hydraulic oil 24. The first piston 13 is fixed to the end of the piston rod 15 on the inner cylinder 12 side, and the piston head 15a is fixed to the other end. The piston head 15a is composed of a circular convex surface portion 15c having a gentle convex surface and a flat surface 15d. The flat surface 15d is disposed on the opposite side of the circular convex surface portion 15c in the piston head 15a.

  The circular convex surface portion 15c faces the spring rod 5 and can contact and separate from the spring rod 5, and the flat surface 15d faces the stop plate 7 and can contact and separate from its end portion. In the throwing state shown in FIG. 1, the circular convex surface portion 15 c is separated from the spring rod 5, and the opposite flat surface 15 d is also separated from the end portion of the stop plate 7. In the shut-off state shown in FIG. 2 from such a charged state, the circular convex surface portion 15c is in contact with the spring rod 5, and the flat surface 15d is also in contact with the end portion of the stop plate 7 and is stationary.

(Return spring)
The return spring 20 is disposed between a return spring receiver 19 installed in the outer cylinder 11 and the second piston 14, and a spring force is always urged in a direction separating the return spring receiver 19 and the second piston 14. ing. The spring force of the return spring 20 is set so as to pressurize the entire hydraulic oil 24 higher than the atmospheric pressure by the second piston 14.

(High pressure chamber, low pressure chamber and liquid chamber)
The high pressure chamber 25 is a space surrounded by the inner cylinder 12 and the first piston 13 and is filled with hydraulic oil 24. The low-pressure chamber 27 is a space surrounded by the outer cylinder 11 and the inner cylinder 12. When the hydraulic oil 24 in the high-pressure chamber 25 is compressed by the operation of the first piston 13, the low-pressure chamber 27 extends from the through hole 21 of the inner cylinder 12. This is a space from which the hydraulic oil 24 is ejected. As shown in FIG. 2, in the shut-off state, the first piston 13 and the second piston 14 are separated from each other, and a space surrounded by the pistons 13 and 14 and the piston rod 15 is formed. This space is the liquid chamber 28.

  The hydraulic oil 24 that has flowed out of the through-hole 21 of the inner cylinder 12 into the low pressure chamber 27 flows into the liquid chamber 28 from the low pressure chamber 27. At this time, the protruding portion 12d of the inner cylinder 12 is arranged substantially in the same plane as the through hole 21, so that the flow of the hydraulic oil 24 is blocked. In addition, since the groove 12e is disposed on the end surface of the inner cylinder 12 in contact with the second piston 14, the hydraulic oil 24 circulates between the liquid chamber 28 and the low pressure chamber 27 even when the inner cylinder 12 and the second piston 14 are in contact with each other. It has a structure to do.

(Packing)
The packing 16 and the packing 18 are respectively provided at sliding portions of the second piston 14 between the outer cylinder 11 and the piston rod 15. As shown in FIG. 1, the packing 16 is provided at a sliding portion of the second piston 14 with the outer cylinder 11. More specifically, the packing 16 is fixed at two locations on the outer periphery of the second piston 14. Similarly, the packing 18 is provided at the sliding portion of the second piston 14 with the piston rod 15. More specifically, the packing 18 is fixed at two locations on the inner periphery of the second piston 14. The packing 22 is fixed to a sliding portion in contact with the outer cylinder 11 in the bottom lid 17. More specifically, the packing 22 is fixed to the outer periphery of the bottom lid 17 at two locations.

(Braking action)
In the first embodiment configured as described above, the braking operation of the shock absorber 10 during the shut-off operation of the switchgear will be described. The shock absorber 10 that performs the braking operation shifts from the state shown in FIG. 1 to the state shown in FIG. When the switchgear performs a shutoff operation, a shutoff command is input from a control device (not shown) to the switchgear operating mechanism, the shutoff spring 2 starts the shutoff operation, and extends to the left in the figure, which is the shutoff direction. When the cutoff spring 2 extends leftward in the drawing by a predetermined distance, the circular convex surface portion 15c of the piston head 15a contacts the end portion of the spring rod 5.

  From the moment when the circular convex surface portion 15c comes into contact with the end of the spring rod 5, the piston head 15a, the piston rod 15 and the first piston 13 start moving toward the bottom lid 17 side, and the first piston 13 has a high pressure. The compression of the hydraulic oil 24 in the chamber 25 is started. The first piston 13 closes the plurality of through holes 21 and pushes the hydraulic oil 24 in the high pressure chamber 25 toward the low pressure chamber 27 through the open through holes 21.

  The pressure generated in the high pressure chamber 25 at this time becomes a braking force and is transmitted between the piston rod 15, the piston head 15 a and the spring rod 5, and becomes a force for stopping the operation of the cutoff spring 2. The oil return path 12 a of the inner cylinder 12 is closed by the bottom cover 17 and the bottom of the inner cylinder 12 coming into contact with each other by the spring force of the return spring 20 transmitted through the second piston 14. Further, during the braking operation of the shock absorber 10, the inner cylinder 12 is pressed against the bottom lid 17 side (left side in the figure) due to the pressure difference between the high pressure chamber 25 and the low pressure chamber 27, and the closed state of the oil return path 12a is maintained. Is done.

  The flow of the hydraulic oil 24 that has flowed into the low pressure chamber 27 flows out into the liquid chamber 28 from a notch 12 c provided around the inner cylinder 12. The hydraulic oil 24 that has flowed into the liquid chamber 28 increases in volume by moving the second piston 14 toward the return spring receiver 19 (rightward in the figure), and the second piston 14 is moved by the spring force of the return spring 20. Is pressurized. FIG. 2 shows a completed state of the braking operation of the shock absorber 10 as described above.

(Return operation)
Next, the return operation of the shock absorber 10 during the closing operation of the switchgear will be described. In the return operation, the shock absorber 10 shifts from the completion state of the braking operation shown in FIG. 2 to the initial state shown in FIG. When the opening / closing device performs a closing operation, a closing command is input to the opening / closing device operating mechanism from a control device (not shown), and the shut-off spring 2 starts the closing operation by a closing spring (not shown).

  During the closing operation of the switchgear, the blocking spring 2 starts to move in the closing direction (right direction in the figure) opposite to the blocking direction, and the blocking spring receiver 4 and the spring rod 5 connected to the blocking spring 2 also move in the closing direction. Start moving. When the spring rod 5 moves in the closing direction, the end of the spring rod 5 moves away from the piston head 15a.

  Since the second piston 14 pressurizes the entire hydraulic oil 24 higher than atmospheric pressure by the spring force of the return spring 20, the piston rod 15 is pushed out toward the spring rod 5 when the spring rod 5 is separated. At this time, since the first piston 13 has moved to the right side in the drawing, the volume of the high pressure chamber 25 increases, and the pressure in the high pressure chamber 25 becomes lower than the pressure in the low pressure chamber 27 for a moment.

  As a result, the inner cylinder 12 together with the first piston 13 starts moving toward the spring rod 5 side. Then, the bottom portion of the inner cylinder 12 is separated from the bottom lid 17 and the oil return path 12a of the inner cylinder 12 is opened. Accordingly, the hydraulic oil 24 flows into the high pressure chamber 25 from the low pressure chamber 27 side through the oil return path 12a. A state in the middle of such a return operation is shown in FIG.

  When the return operation of the shock absorber 10 further proceeds, the hydraulic oil 24 flows from the oil return path 12a of the inner cylinder 12 and the low pressure chamber 27 into the high pressure chamber 25 through the plurality of through holes 21. When the closing operation of the opening / closing device is completed, the second piston 14 returns to the initial position where it contacts the end of the inner cylinder 12 and stops there, and the first piston 13 returns to the initial position where it contacts the second piston 14. And stop there. The state where the return operation of the shock absorber 10 as described above is completed, that is, the initial state of the shock absorber 10 is shown in FIG.

(Function and effect)
The operational effects of the first embodiment described above are as follows. That is, in the first embodiment, the piston rod 15 does not have a rod return spring for returning the piston rod 15 to the initial position. The return spring 20 shown in the first embodiment is not compressed suddenly but is compressed via the hydraulic oil 24.

  Therefore, even if the piston rod 15 is suddenly displaced due to the collision with the spring rod 5 just before the closing operation of the opening / closing device is finished, the return spring 20 is not suddenly displaced. In such a return spring 20, local deformation due to impact does not occur, and the spring wires do not come into close contact with each other. As a result, the occurrence of deformation or damage can be suppressed, and excellent spring strength can be maintained.

  In addition, when extending the stroke (displacement amount) of the piston rod 15, there is no restriction on the total length or mounting dimensions of the spring for returning the piston rod 15, so that it can be relatively freely modified and can handle various braking capacities. can do. Such a return spring 20 is less likely to buckle even if the free length of the spring is extended and the stroke (displacement amount) of the piston rod 15 is extended, so that it is possible to prevent a decrease in spring strength.

[Second Embodiment]
(Constitution)
A second embodiment according to the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional view showing an initial state of the second embodiment. FIG. 6 is a diagram showing a braking operation completion state of the shock absorber 10 shown in FIG. In addition, the same code | symbol is attached | subjected about the same or similar part as the said 1st Embodiment, and the overlapping description is abbreviate | omitted. Moreover, since parts other than the shock absorber 10 are the same as those in the first embodiment, they are not shown.

  In the second embodiment, a forced return spring 30 is added to the shock absorber 10 shown in FIG. 1 and the shapes of the inner cylinder 12 and the bottom lid 17 are changed. That is, as shown in FIG. 5, the protrusion 12b is disposed on the bottom of the inner cylinder 12 on the bottom lid 17 side, and the forced return spring 30 is disposed around the protrusion 12b. A recess 17a is disposed in the bottom lid 17, and a forced return spring 30 is accommodated therein.

  The forcible return spring 30 is always urged by a compressive force between the inner cylinder 12 and the bottom cover 17. The inner cylinder 12 is pressed against the bottom lid 17 side by the spring force of the return spring 20 via the second piston 14, and the movement of the inner cylinder 12 is restricted. That is, the spring force of the forced return spring 30 is set smaller than that of the return spring 20.

  In the state where the braking operation is completed as shown in FIG. 6, the inner cylinder 12 is moved toward the second piston 14 by the spring force of the forced return spring 30, but the end of the first piston 13 and the high pressure chamber 25 side of the inner cylinder 12 are located. It is restrained at the position where the bottom of the unit comes into contact. In this state, the oil return path 12a is open.

(Braking action)
In the second embodiment having the above configuration, the same operation as that of the first embodiment is performed in the braking operation. However, after the braking operation is completed, the inner cylinder 12 is moved to the second piston by the spring force of the forced return spring 30. It moves to 14 side, and is restrained in the position where the 1st piston 13 and the bottom part of the inner cylinder 12 contact | connect.

(Return operation)
In the second embodiment, in the return operation, the same operation as that of the first embodiment is performed, and the closing operation in the second embodiment can be easily estimated from the description of the above-described blocking operation. Therefore, the detailed description is omitted. . However, when the braking operation is completed as shown in FIG. 6, the oil return path 12a is already open, and the inflow of the hydraulic oil 24 from the low pressure chamber 27 to the high pressure chamber 25 can be started even if the inner cylinder 12 does not move. it can.

(Function and effect)
In the second embodiment configured as described above, in addition to the same function and effect as those of the first embodiment described above, the piston in the process from the shut-off state to the closing state is provided by arranging the forced return spring 30. The response time for starting the operation of the rod 15 can be shortened.

  In general, when the sliding surfaces of the packings 16 and 18 remain stationary for a long time, the oil film decreases, and in the worst case, the packings 16 and 18 and the sliding member (in this case, the piston rod 15) are fixed. And may not slide. Even when the packings 16 and 18 and the piston rod 15 are not fixed, if the frictional force between the sliding surfaces of the packings 16 and 18 increases, the return time until the piston rod 15 reaches the closing position from the blocking position is delayed. Further, if the frictional force changes, the return time varies. Therefore, in the present embodiment, the spring force of the forced return spring 30 is added as a force that cancels the frictional force that acts when the piston rod 15 starts to operate. According to the second embodiment as described above, it is possible to eliminate the delay of the return time, reduce the variation in the return time, and give preferable characteristics to the shock absorber.

  In the second embodiment, the sudden displacement of the piston rod 15 during the shut-off operation is not directly transmitted to the forced return spring 30 but is transmitted via the hydraulic oil 24. Therefore, the forced return spring 30 does not cause local deformation. Accordingly, the strands of the spring are not in close contact with each other, it is possible to suppress the occurrence of deformation or damage, and maintain excellent spring strength.

[Third Embodiment]
(Constitution)
Next, a third embodiment according to the present invention will be described with reference to FIGS. FIG. 7 is a cross-sectional view showing an initial state of the third embodiment. FIG. 8 is a diagram showing a braking operation completion state of the shock absorber 10 shown in FIG. In addition, the same code | symbol is attached | subjected about the same or similar part as the said 1st Embodiment, and the overlapping description is abbreviate | omitted. Moreover, since parts other than the shock absorber 10 are the same as those in the first embodiment, they are not shown.

  In the third embodiment, a force return spring 30, a force return piston 31, and a guide 32 are added to the shock absorber 10 shown in FIG. That is, as shown in FIG. 7, a concave guide 32 is fixed to the bottom lid 17. A convex forcible return piston 31 is slidably disposed on the guide 32.

  The forced return spring 30 is housed inside the forced return piston 31, and a compressive force is always urged between the forced return piston 31 and the bottom cover 17. A space formed by the inside of the forced return piston 31, the bottom lid 17 and the guide 32 is a second high pressure chamber 33, and the hydraulic oil 24 in the second high pressure chamber 33 is compressed as the forced return piston 31 moves. It has a structure.

  The forcible return piston 31 is provided with a stepped portion 31a, and the guide 32 is provided with a stepped portion 32a. The range of movement of the forcible return piston 31 and the guide 32 is restricted by the contact between the step portions 31a and 32a. The forcible return piston 31 is provided with a protrusion 31b, which protrudes into the high pressure chamber 25 through the oil return path 12a.

  The forced return piston 31 is formed with an oil passage 31c for allowing the second high pressure chamber 33 and the high pressure chamber 25 to communicate with each other. In addition, the hole diameter of the oil return path 12a is larger than the shaft diameter of the protrusion 31b, and is set so that the hydraulic oil 24 flows. The inner cylinder 12 is pressed against the end face of the guide 32 by the spring force of the return spring 20 via the second piston 14, and the movement of the inner cylinder 12 is stopped. At this time, the oil return path 12a is closed.

  In the state where the braking operation shown in FIG. 8 is completed, the protrusion 31b of the forced return piston 31 is in contact with the end surface of the second piston 14, and the forced return spring 30 is compressed. The second piston 14 and the piston rod 15 are pushed in the closing operation direction by the spring force of the forced return spring 30. The stroke (displacement amount) of the forced return piston 31, that is, the stroke of the forced return spring 30 is set longer than the width of the packing 18. This is because the oil film on the sliding surface is formed again if the piston rod 15 moves more than the width fixed to the packing 18.

(Braking action)
In the third embodiment having the above-described configuration, the same operation as that of the first embodiment is performed in the braking operation, but immediately before the completion of the braking operation, the end of the second piston 14 abuts on the protrusion 31b, The forced return piston 31 is pushed into the bottom lid 17 side. At this time, the pressure is increased by compressing the hydraulic oil 24 in the second high pressure chamber 33. This pressure becomes the braking force of the forced return piston 31. The hydraulic oil 24 in the second high pressure chamber 33 flows out to the high pressure chamber 25 side through the oil passage 31c.

(Return operation)
In the third embodiment, in the closing operation, the same operation as that of the first embodiment is performed, and the return operation in the third embodiment can be easily estimated from the description of the braking operation. Therefore, the detailed description is omitted. . However, in the braking operation completion state shown in FIG. 8, the forced return piston 31 always pushes the second piston 14 and the piston rod 15 toward the second piston 14 by the spring force of the forced return spring 30. For this reason, even when the frictional force between the piston rod 15 and the packing 18 changes, the piston rod 15 immediately starts the return operation at the start of the return operation.

(Function and effect)
In the third embodiment configured as described above, the same operational effects as those of the first and second embodiments described above can be obtained. That is, even if the sliding resistance increases as the oil film between the piston rod 15 and the packing 18 decreases, the return time delay and variation can be prevented by the forced return spring 30 and the forced return piston 31, and the buffering The device can be given favorable characteristics.

  Further, since the sudden displacement of the piston rod 15 during the shut-off operation is not directly transmitted to the forced return spring 30, the forced return spring 30 is not locally deformed and the spring strength is reduced. There is nothing to do. Furthermore, the second high pressure chamber 33 can have an excellent braking effect, and further, it is possible to prevent a sudden displacement of the forced return spring 30 and there is no fear of causing deformation of the spring.

[Fourth Embodiment]
(Constitution)
Next, a fourth embodiment according to the present invention will be described with reference to FIG. FIG. 9 is a cross-sectional view showing a fourth embodiment of the shock absorber 10 of the opening / closing device operating mechanism. In addition, the same code | symbol is attached | subjected regarding the same or similar part as the said 3rd Embodiment, and the overlapping description is abbreviate | omitted. Moreover, since parts other than the shock absorber 10 are the same as those in the third embodiment, they are not shown.

  In the fourth embodiment, the guide 32 of the shock absorber 10 shown in FIG. 7 is omitted, and a stop plate 34 for restricting the amount of movement of the forced return piston 31 is added. That is, as shown in FIG. 9, a recess is formed in the bottom lid 17, the convex forcible return piston 31 is slidably disposed inside the bottom lid 17, and the stopper plate 34 is fixed to the end surface of the bottom lid 17. Let The protrusion 31b of the forcible return piston 31 has a structure that protrudes toward the inner cylinder 12 through a hole disposed in the stop plate 34. The stepped portion 31 a of the forcible return piston 31 is in contact with the stop plate 34 so that the movement range is restricted.

(Function and effect)
In the fourth embodiment having the above-described configuration, the same operation as that of the third embodiment can be performed in the braking operation and the return operation, and the same effect as the above-described third embodiment can be obtained. .

[Other Embodiments]
In addition, said embodiment is shown as an example in this specification, Comprising: It does not intend limiting the range of invention. In other words, the present invention can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof in the same manner as included in the scope and gist of the invention. For example, although the compression coil spring is used for the return spring 20 and the forced return spring 30 in the above embodiment, other elastic elements such as a disc spring may be used.

DESCRIPTION OF SYMBOLS 1 ... Movable contact 2 ... Shut-off spring 3 ... Movable end 4 ... Shut-off spring receiver 5 ... Spring rod 6 ... Support structure 7 ... Stop plate 8 ... Connection part 10 ... Shock absorber 11 ... Outer cylinder 12 ... Inner cylinder 12a ... Oil feedback Path 12b ... Projection 12c ... Notch 12d ... Projection 12e ... Groove 13 ... First piston 14 ... Second piston 15 ... Piston rod 15a ... Piston head 15c ... Circular convex surface 15d ... Plane 16 ... Packing 17 ... Bottom cover 17a ... recess 18 ... packing 19 ... return spring receiver 20 ... return spring 21 ... through hole 22 ... packing 23 ... bottom plate 24 ... hydraulic oil 25 ... high pressure chamber 27 ... low pressure chamber 28 ... liquid chamber 30 ... forced return spring 31 ... forced return Piston 31a ... Step part 31b ... Projection part 31c ... Oil passage 32 ... Guide 32a ... Step part 33 ... Second high pressure chamber 34 ... Stop plate

Claims (6)

In a shock absorber used for an operation mechanism that operates a switching body of an opening / closing device by reciprocating a movable body including an electrical contact between an open and a closed position,
An outer cylinder and an inner cylinder arranged coaxially;
A first piston slidably disposed inside the inner cylinder;
A second piston slidably disposed inside the outer cylinder;
A piston rod slidably disposed on the second piston and secured to the first piston;
A high-pressure chamber formed by being surrounded by the inner cylinder and the first piston, and filled with hydraulic oil that is compressed when the piston rod and the first piston are pushed in;
A return spring disposed between the outer cylinder and the second piston and biased in a direction to separate the outer cylinder and the second piston;
A shock absorber for an operating mechanism for a switchgear. The switchgear operating mechanism has a stop plate and a blocking spring,
A cutoff spring receiver is fitted to the end of the cutoff spring,
A blocking spring rod is fixed to the blocking spring receiver,
Engaging the piston rod and the shut-off spring rod detachably,
The shock absorber of the operating mechanism for the switchgear according to claim 1. Disposing a forced return spring between the inner cylinder and the bottom lid ;
The shock absorber of the operating mechanism for the switchgear according to claim 1 or 2. A guide is fixed to the bottom lid,
A forced return piston is slidably disposed inside the guide,
The end face of the forcible return piston is in contact with the end face of the first piston so as to be detachable.
Disposing a forced return spring between the bottom lid and the forced return piston;
The shock absorber of the operation mechanism for switchgear according to any one of claims 1 to 3. A forced return piston is slidably arranged inside the bottom lid,
The end face of the forcible return piston is in contact with the end face of the first piston so as to be detachable.
A forced return spring is disposed between the bottom lid and the forced return piston;
A stopper plate for restricting a movable range of the forced return piston is fixed to an end surface of the bottom lid;
The shock absorber of the operation mechanism for switchgear according to any one of claims 1 to 3. The second piston has a packing fixed to a sliding portion between the outer cylinder and the piston rod,
The stroke of the forced return spring is not less than the width of the packing;
The shock absorber for an operating mechanism for a switchgear according to any one of claims 3 to 5.

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