JP3608817B2 - Airtight structure in the penetrating part of the rotating shaft - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a hermetic structure in which a hermetic reliability of a gap portion between a rotary shaft and a bearing that are attached to the hermetic case is increased.
[0002]
[Prior art]
For example, in a gas switch in which an airtight case is filled with SF ₆ gas, the penetrating part of the handle shaft, the penetrating part of the pointer shaft, the pressure-releasing cover of the pressure-releasing part have an O-ring type airtight holding structure. .
[0003]
In particular, an airtight holding structure in a penetrating portion of a rotating shaft such as a handle shaft is considered to be technically difficult.
That is, in the prior art, as shown in FIG. 4, the pipe-shaped bearing 101 penetrating and fixing in the airtight case 100 passes through the handle shaft, that is, the rotating shaft 103, and is further engraved on the coaxial outer peripheral surface 103a. The O-ring 104 is fitted into the O-ring groove 103b, and the O-ring 104 is compressed between the outer peripheral surface 103a of the rotating shaft 103 and the inner peripheral surface 101a of the bearing 101, and the repulsion of the O-ring occurs during the compression. The O-ring 104 is brought into close contact with the inner peripheral surface 101a of the bearing and the O-ring groove 103b (more precisely, the bottom surface 103b 'of the O-ring groove) on the outer peripheral surface 103a of the rotary shaft by force, and the airtightness of the shaft penetrating portion is maintained. It has become so.
[0004]
[Problems to be solved by the invention]
In the above conventional structure, since both side wall surfaces (thrust direction) of the O-ring groove 103b are fixed, the gap dimension between the inner peripheral surface 101a of the bearing 101 and the bottom surface 103b 'of the O-ring groove is larger than a predetermined value (design value). If it is large, the O-ring 104 is not compressed as prescribed, and the contact pressure on the both surfaces 101a and 103b 'is insufficient, causing gas leakage.
[0005]
On the other hand, when the gap between the both surfaces 101a and 103b 'is smaller than a predetermined value (design value), the O-ring 104 is over-pressed in the diameter direction of the rotating shaft 103. In this case, since the both side wall surfaces of the O-ring groove 103b are fixed, the bulging deformation on both sides of the O-ring 104 (the axial direction side of the rotating shaft 103) is restrained by the both side wall surfaces of the O-ring groove 103b. 104 is compressed excessively, stress cracks occur over time, and gas leakage occurs.
[0006]
Therefore, when the gap dimension between the bearing and the bottom surface of the O-ring groove is not accurately formed to a predetermined value as described above, it is difficult to maintain airtightness for a long time in the through portion.
[0007]
As the above measures, conventionally, the dimensional accuracy of parts is increased and strictly controlled in order to make the gap dimension between the inner peripheral surface of the bearing and the bottom surface of the O-ring groove predetermined (as designed). There is a problem that this leads to a rise in the cost of parts and, consequently, the cost of the switch.
[0008]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an airtight structure in which an O-ring can be compressed as predetermined (designed) without significantly increasing the processing accuracy of the gap dimension, and high airtight reliability can be ensured. .
[0009]
[Means for Solving the Problems]
The present invention has been made to solve the above problems by a novel method. The first invention according to claim 1 is characterized in that the rotary shaft (4) penetrates the bearing (3) rotatably, in those rotating shaft (4) and the bearing (3) O-ring for gas-tight seal between the (11 ₁₎ so as to be interposed, the side surface of the O-ring (11 _1), through the response ring (10) And a large-diameter engaging portion (10c) is formed in the response ring (10), and the engaging portion (10c) is formed on the bearing (3) side. ) Contact with each other to form an inner step portion (3e) that prevents the response ring (10) from entering the O-ring (11 ₁ ) .
[0010]
In addition to the O-ring (11 ₁ ) pressed by the responsive ring (10) of the first invention, the second invention described in claim 2 further includes another O-ring (11 ₂ ), (11 ₃ ). ) In parallel, and these O-rings (11 ₂ ) and (11 ₃ ) are installed so that the pressing force of the coil spring (9) acts.
[0011]
[Action]
In the first aspect of the present invention, the gap between the rotary shaft (4) and the bearing (3) in the portion where the O-ring (11 ₁ ) is interposed is larger than a predetermined dimension, and the rotary shaft (11 ₁ ) of the O-ring (11 ₁ ) 4) When the contact pressure on the bearing (3) is insufficient, the pressing force of the coil spring (9) overcomes the repulsive force (elastic force) of the O-ring, and the pressing force causes the side surface of the O-ring (11 ₁ ). Is pressed and the O-ring (11a) is reduced and deformed, and the stress is increased, and the contact pressure of the O-ring (11 ₁ ) with respect to the rotating shaft (4) and the bearing (3) is increased to a predetermined pressure.
[0012]
On the contrary, when the clearance between the rotating shaft (4) and the bearing (3) is smaller by a predetermined dimension and the O-ring (11 ₁ ) is compressed more than a predetermined amount in the radial direction of the rotating shaft (4), the O The ring (11 ₁ ) tends to bulge and deform in the side direction (the direction of the responding ring (10)) which is the axial direction of the rotating shaft (4). At this time, when the stress of the O-ring (11 ₁ ) overcomes the pressing force of the coil spring (9), the O-ring (11) pushes and moves the responding ring (10) to the side of the O-ring (11 ₁ ). Swelling deformation is allowed. As a result, the stress of the O-ring (11 ₁ ) does not increase above the predetermined pressure. Therefore, the contact pressure of the O-ring (11 ₁ ) with respect to the rotating shaft (4) and the bearing (3) is maintained at a predetermined pressure.
[0013]
In the invention described in claim 2, a plurality of O-rings (11 _{1 to} 11 ₃ ) can be operated in the same manner as described above.
[0014]
【Example】
Next, a first embodiment of the present invention shown in FIG. 1 will be described. In FIG. 1, the lower half of the bearing portion is omitted, and the lower portion from the middle line of the rotating shaft 4 has the same structure as the upper portion.
[0015]
Reference numeral 1 denotes an airtight case of a gas switch that is filled with SF ₆ gas 2 until a predetermined pressure is reached, and is made of stainless steel. Reference numeral 3 denotes a pipe-like bearing fixed in a state of penetrating the case, which is also made of stainless steel, and its small-diameter inner peripheral surface 3a is finished with a relatively high accuracy unlike other parts.
[0016]
Reference numeral 4 denotes a rotary shaft that passes through the coaxial receiver 3 in a freely rotating manner and penetrates the case 1 in a state of passing through the inside and the outside. The outer peripheral surface 4a of the large-diameter portion is finished with relatively high accuracy, as shown in FIG. This corresponds to the rotating shaft 4 ′ of the operating handle shaft 7 of the switch or the pointer shaft 4 ″ of the pointer 20. Reference numeral 5 denotes an operating lever integrally connected to the end 4b of the rotating shaft 4 located on the inner side A of the case. Reference numeral 6 denotes a handle holding bracket fixed to the end 4f located on the opposite outer side B of the case, and the handle 7 is fastened to the bracket 6 with screws, etc. Reference numeral 8 denotes between the rotary shaft 4 and the bearing 3. An intervening bearing metal is provided at the end of the case inside A. 9 is a coil spring, and a large-diameter inner peripheral surface 3b of the bearing 3 and a small-diameter outer peripheral surface 4b of the rotary shaft 4. The coil spring 9 is fitted in the gap C between It is interposed in a compressed state between a concave spring receiving portion 10a of Le holding fitting 6 and the driven ring 10.
[0017]
10 is a response kinetic ring described above, stainless steel, is made of brass or metal material, is formed in a ring shape to slidably fit between the rotating shaft 4 and the bearing 3. Further the response dynamic ring 10, the pressing end 10b side of the front are in a state of slightly enters into the gap between the small-diameter outer peripheral surface 4b of the rotary shaft 4 and the small diameter inner peripheral surface 3a of the bearing 3 and the rear A large-diameter spring receiving portion 10a is formed, and the locking portion 10c abuts against the inner step portion 3e on the bearing 3 side to prevent further entry. Then, the response dynamic ring 10 is pressed to always forward into (Case interior side) by the coil spring 9.
[0018]
Reference numerals 4d and 4e denote two O-ring grooves which are located on the inner peripheral surface 3a of the small diameter portion of the bearing 3 and are engraved on the outer peripheral surface 4a of the large diameter portion on the rotating shaft 4 side, including the bottom surfaces 4d 'and 4e'. The groove is finished with high accuracy.
[0019]
11 _{1, 11} 2, 11 ₃ is O-ring made of the O-ring groove 4d, 4e and fluorine rubber or EPR rubber were fitted positioned between pressing end 10b and Jikudan portion 4g of the response dynamic ring 10, In the embodiment of the present invention, three O-rings are used to form a triple airtight holding structure.
[0020]
The above coil spring 9, presses the O-ring 11 ₁ interposed between said response kinetic ring 10 and Jikudan portion 4g through the response dynamic ring 10 is deformed, whereby the O-ring 11 ₁ of the bearing 3 This is for keeping constant the contact pressure with respect to the small diameter inner peripheral surface 3a and the contact pressure with respect to the small diameter outer peripheral surface 4b of the rotary shaft 4, and the small diameter outer peripheral surface 4b of the rotary shaft 4 and the small diameter inner peripheral surface 3a of the bearing. the spacing is large, these surfaces 4b, the state where the contact pressure of the O-ring 11 ₁ is insufficient for 3a (when O-ring due to the repulsive force is small), the repulsive pressure of the coil spring 9 is O-ring 11 ₁ overcoming the force (elastic force), O-ring 11 ₁ Jikudan portion pressing to deform the 4g direction forward, and serves to act in a direction to increase the contact pressure on both sides 4a, 3a, said double-sided reversed Between 4a and 3a When intervals as is excessive small the contact pressure (when the repulsive force of the O-ring is greater) response kinematic ring pressing force of the coil spring 9 is lost to the O-ring 11 ₁ of the repulsive force and the Jikudan portion 4g A coil spring having a spring which is pushed and moved to the opposite side and does not accumulate excessive stress in the O-ring 111 ₁ , that is, acts to reduce the contact pressure is used.
[0021]
That is, the spring force of the coil spring 9 is set so that the compression rate of the O-ring 11 ₁ is 20 to 30% in order to maintain airtightness, and this action causes the rotating shaft 4 and the bearing 3 of the O-ring 11 _{1 to} move. The contact pressure is always kept constant, and airtightness is secured at the penetrating portion of the rotating shaft over a long period of time.
[0022]
In the above description, the O-rings 11 ₂ and 11 ₃ fitted in the first O-ring groove 4d and the second O-ring groove 4e are designed to have a compression rate of 20 to 30% as described above. Strictly speaking, the compression ratios of the O-rings 11 ₂ and 11 ₃ change depending on the size of processing variations of the bearing 3 and the rotating shaft 4.
[0023]
In general, fluorocarbon rubber and EPR rubber are used as the material for the O-ring used to maintain airtightness in the penetrating part such as the rotating shaft of a gas switch. It is properly used. Further, the sealing effect of the O-ring can be determined from the compressive strain, and generally it is said that the reliability is lost when it becomes 80% or more. In addition, in the case of fluoro rubber O-rings, it takes about 30 years for compression strain to reach 50% in the case of continuous use at 100 ° C at a compression rate of 20% from the viewpoint of compression strain characteristics. Yes. Further, if the compression rate is increased, the compressive strain can be reduced, but if it is too high, stress cracking occurs. Therefore, the compression rate is up to 35%. Therefore, the gas switch is designed to have a compression rate of 20 to 30%.
[0024]
Next, FIG. 2 shows a second embodiment of the present invention. FIG. 2 is similar to FIG. 1 except that the lower half of the bearing portion is omitted, and the lower part from the middle line of the rotating shaft 4 has the same structure as the upper part.
[0025]
In the second embodiment, the outer peripheral surface 4b of the small diameter portion of the rotating shaft 4 is extended forward, and all the O-rings 11 ₁ , 11 ₂ , 11 ₃ are slid on the surface 4b in the axial direction of the rotating shaft 4. rotatably fitted, O-ring 11 ₁ located backward so as to be pressed directly by the embodiment similarly to the driven ring 10, the O-ring 11 ₁ and the intermediate O-ring 11 ₂ and the front of the O-ring 11 ₃ a rotational shaft driven auxiliary ring 15 1 of stainless steel or the like to the small-diameter outer peripheral face 4b of the _4, 15 ₂ slidably interposed in the axial direction of the rotating shaft 4 between the, intermediate and front O-ring 11 ₂ and 11 ₃ receive the pressing force of the coil spring 9 via the driven auxiliary rings 15 ₁ and 15 ₂ .
[0026]
4h is a front side surface of the front O-ring 11 ₃ is in contact with the engaging stepped portion is integrally formed with the rotary shaft 4.
Other structures are the same as in the above embodiment.
[0027]
FIG. 3 shows an example of a gas switch equipped with an airtight holding structure for the through-hole portion of the rotating shaft in the present invention. 1 is an airtight case, 2 is SF ₆ gas, 3 is a side view of the airtight case. Bearings that penetrate and are fixed in a projecting manner to the side, 4 'is a rotating shaft of the operating handle, 7 is an operating handle, 6 is a handle holding bracket, 16 is an operating mechanism for transmitting the power of the handle, and 17 is an operating unit. An interlocking mechanism connected to the mechanism, 18 is a lightning arrester, 19 is an arc extinguishing device, 20 is a pointer, and 4 ″ is a pointer shaft.
[0028]
The above airtight holding structure can also be applied to the case of a sealed air switch or other sealed case.
[0029]
【The invention's effect】
According to the first aspect of the present invention, even if the gap between the rotating shaft and the bearing has a slight error from a predetermined value (design value), the contact pressure of the O-ring with respect to the rotating shaft and the bearing is set to the predetermined pressure. Therefore, it is possible to prevent the leakage of gas or the like due to insufficient contact pressure or the occurrence of stress cracking of the O-ring due to overpressure, and the airtight reliability can be improved. In addition, it is not necessary to request a high accuracy of the above gap dimension, and the high cost resulting from high machining accuracy and strict management of the conventional parts can be eliminated. Furthermore, the contact pressure of the O-ring can be set as desired by setting the biasing force of the coil spring as desired.
[0030]
In the second aspect of the invention, even when a plurality of O-rings are used, the same effect as described above can be exhibited and the airtight reliability can be further enhanced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part showing an upper half of an airtight structure portion of a rotating shaft, showing a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of an essential part showing an upper half portion of an airtight structure portion according to a second embodiment of the present invention.
FIG. 3 is a sectional view of a gas switch showing one application example of the present invention.
FIG. 4 is a longitudinal sectional view of a main part showing a hermetic structure portion, showing a conventional example.
[Explanation of symbols]
3 Bearing 4 Rotating shaft 9 Coil spring 10 Response ring 11 ₁ , 11 ₂ , 11 ₃ O-ring

Claims (2)

Rotating shaft (4) is rotatably penetrated with respect to bearing (3), and an O-ring (11 ₁ ) for maintaining airtightness is interposed between rotating shaft (4) and bearing (3). The side surface of the O-ring (11 ₁ ) is pressed by the coil spring (9) through the response ring (10), and the response ring (10) has a large-diameter engaging portion (10c). ), And the locking portion (10c) is in contact with the bearing (3) side to prevent the response ring (10) from entering the O-ring (11 ₁ ) direction (3e) airtight structure of the through portion of the rotary shaft, characterized in that the formation of the. In addition to the O-ring (11 ₁ ) pressed by the responsive ring (10) according to claim 1, further O-rings (11 ₂ ) and (11 ₃ ) are interposed in parallel, and these O-rings ( 11 ₂ ) and (11 ₃ ) are installed so that the pressing force of the coil spring (9) acts on the airtight structure in the penetrating portion of the rotating shaft.

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