SURGE ARRESTER, AND MANUFACTURING PROCESS FOR A SURGE ARRESTER

Abstract

A surge arrester includes a fluid-tight housing and a pressure relief assembly constructed to provide a fluid-conducting connection to the outside of the housing if a gas pressure inside the housing exceeds a threshold value. The pressure relief assembly is secured to the housing by at least one twist lock or lockable rotary closure. A corresponding manufacturing process for a surge arrester is also provided.

Claims

1-13. (canceled)

14. A surge arrester, comprising: a fluid-tight housing having an outside; a pressure relief assembly configured to provide a fluid-conducting connection to said outside of the housing if a gas pressure inside said housing exceeds a threshold value; and at least one lockable rotary closure securing said pressure relief assembly to said housing.

15. The surge arrester according to claim 14, wherein said lockable rotary closure includes a plurality of locking projections being secured by rotating in complementary recesses of said housing.

16. The surge arrester according to claim 14, wherein said pressure relief assembly includes a substantially cup-shaped locking device having a base and a side wall.

17. The surge arrester according to claim 16, wherein: said cup-shaped locking device has a cup interior; said side wall has an inner side facing toward said cup interior; and said locking device includes a plurality of support ribs disposed along said inner side.

18. The surge arrester according to claim 16, wherein said housing has an interior, and said side wall includes a first outflow opening connected in a fluid-conducting manner to a second outflow opening in said housing in an assembled state, causing a deflection of a fluid flow out of said cup-shaped locking device through said first and second outflow openings to take place if a fluid flows out of said interior of said housing.

19. The surge arrester according to claim 16, wherein: said cup-shaped locking device has a cup interior; said side wall has an outer side facing away from said cup interior; and said lockable rotary closure includes at least three locking projections disposed along said outer side.

20. The surge arrester according to claim 16, wherein said cup-shaped locking device has a cup interior, and said base bulges toward said cup interior.

21. The surge arrester according to claim 14, which further comprises: ends of the surge arrester; said pressure relief assembly being disposed at one of said ends of the surge arrester; and said pressure relief assembly including a membrane constructed to tear if the threshold value for the gas pressure is exceeded.

22. The surge arrester according to claim 21, which further comprises: first and second contact pressure devices; said membrane having a side facing towards the surge arrester being laid on said first contact pressure device; and said membrane having a side facing away from the surge arrester being secured by said second contact pressure device.

23. The surge arrester according to claim 20, wherein said pressure relief device includes an assembly projection on a side of said base facing away from said cup interior for transmitting a rotational movement.

24. A process for manufacturing a surge arrester, the process comprising the following steps: placing a membrane on a fluid-tight housing; placing a pressure relief assembly having at least one lockable rotary closure on the housing; locking the rotary closure on the housing while securing the membrane; and using the pressure relief assembly to provide a fluid-conducting connection to an outside of the housing if a gas pressure inside the housing exceeds a threshold value.

25. The manufacturing process according to claim 24, which further comprises placing the membrane between first and second contact pressure devices by placing the first contact pressure device on a side of the membrane facing toward the surge arrester and placing the second contact pressure device on a side of the membrane facing away from the surge arrester.

26. The manufacturing process according to claim 24, which further comprises: forming the pressure relief device as a substantially cup-shaped locking device having a base and a side wall; locking the locking device on the housing by exerting an assembly machine force on an assembly projection on a side of the base facing away from a cup interior of the locking device; and securing the locking device on the housing by rotating.

Description

[0021] For better explanation of the invention, a preferred and advantageous embodiment of the surge arrester according to the invention is explained hereafter in greater detail on the basis of three figures. In the figures:

[0022] FIG. 1 shows a locking means according to the invention,

[0023] FIG. 2 shows a cross section through a surge arrester having a pressure relief assembly according to the invention, and

[0024] FIG. 3 shows a further cross section through the surge arrester having the pressure relief assembly according to the invention.

[0025] FIG. 1 shows a locking means 1, which is formed essentially cup-shaped. A side wall 7 in the form of a cylindrical jacket comprises an outer side 55 and an inner side 56. A base 60 comprises a base inner side 2, which is oriented toward the cup interior. A test opening 3 is located in the center of the base 60. The test opening 3 is used for test purposes in order to check a fluid-tightness in the assembled state on the surge arrester. Before use of the surge arrester, the test opening 3 is closed by a plug (not shown). The base 60 bulges toward the cup interior and in this way forms three regions 31, 32, 33, which are each formed ring-shaped and have the widths 4, 5, 6. Support ribs 18 are provided in the cup interior, which are attached to the side wall 7, on the one hand, and to the base 60, on the other hand. The support ribs 18 form a disk-type terminus on the open side of the cup together with an upper edge 57 of the side wall 7, which terminus is suitable for also contacting the support ribs 18 by applying a contact pressure means (not shown) to the upper side wall 57. In this manner, the support ribs 18 and also the upper side wall 57 as contact regions transmit mechanical forces to the cup base 60, which relieves the side wall 7. The support ribs 18 thus enhance the mechanical stability of the locking means 1.

[0026] The locking means 1 comprises locking projections 8, 9, 10, 11, 12, 13 on the outer side 55 of the side wall 7. The locking projections 8-13 form a double bayonet fitting, which can be secured by rotation in complementary recesses of a housing (not shown). The locking projections 8-13 are arranged in pairs in such a way that approximately 60° of the outer wall, i.e., approximately ⅙ of the circumference of the side wall, remains free of the locking projections on the outer side 55 of the side wall 7 in each case. Due to these free regions, the locking means 1 can be inserted into a housing and secured by rotation. The locking means arranged in pairs each comprise a locking means 9, 10, 13, which is arranged directly at the upper edge 57 of the side wall 7. In this way, the locking means 9, 10, 13 additionally widen the upper edge 57 of the side wall 7 and offer, like the cooling ribs 18, a larger contact surface for a contact pressure means (not shown). The mechanical stability is also improved in this way.

[0027] Two openings 52, 53 are provided in the side wall 7, which together form a first outflow opening 52, 53 of the locking means 1. To improve the mechanical stability of the outflow openings 52, 53, the upper edge 57 of the side wall 7 is formed as a widened edge 16 in the region of the outflow openings 52, 53. The widened edge 16 comprises two protrusions 19, 20 toward the cup interior. The protrusions 19, 20 are used, similarly to the support ribs 18, for improving the mechanical stability when applying a contact pressure means (not shown).

[0028] The widened upper edge 16 is supported via a connecting part 15 on a widened base part 14. The widened base part 14 protrudes here in the same manner as the catch projections 8-13 somewhat beyond the outer wall 55 of the side wall 7, to be locked in a housing (not shown).

[0029] FIG. 2 shows in cross section how the locking means 1 together with a first contact pressure means 25, a membrane 22, 23, and a second contact pressure means 21 form a pressure relief assembly 1, 21, 22, 23, 25, which is secured by rotation in a housing 24. It is recognizable that the interior of the cup is open to the left in the direction of a second outflow opening 51 in the housing, since the first outflow opening 52, 53 and the second outflow opening 51 are brought into congruence. For the machine execution of a rotational movement, two assembly projections 35, 36 are provided on the lower side of the base 60. A ring-shaped second contact pressure means 21, which is mechanically supported by the mentioned elements 18, 9, 10, 16, is applied to the support ribs 18 and the locking means 9, 10 and also to the widened upper edge 16 and the upper side wall 57. A membrane 22, which comprises an outer edge 23 in the form of a cylindrical jacket, formed as a thin metal plate is applied to the second contact pressure means 21. The outer edge 23 is applied to the membrane 22 toward the interior of the housing 24 and thus facing away from the second contact pressure means 21. The membrane 22 is thus not supported over a large part of the cavity, which the locking means 21 provides by way of its cup-shaped formation. A seal ring 62 is arranged on the second contact pressure means 21 and enclosing the membrane 22. The seal ring 62, the membrane 22, and the membrane section 23 in the form of a cylindrical jacket form a ring-shaped peripheral recess, in which a protrusion 61, which is also ring-shaped and peripheral, of the housing 24 engages. This design is suitable for pressing the membrane 22, 23 and the seal ring 62 against the housing and securing them in a fluid-tight manner upon securing of the locking means 1 by means of the locking projections 8, 9, 10, 11 via the second contact pressure means 21. A first contact pressure means 25 is provided on the membrane 22 and enclosed by the cylindrical peripheral membrane portion 23.

[0030] FIG. 3 shows another cross-sectional view of the housing having the pressure relief assembly. It can be seen that the base 60 has a thickness 34. Three regions 31, 32, 33 result due to the bulge of the base. The first base region 31 is arranged as a concentric ring around the test opening 3 and is arranged essentially parallel to the membrane surface 22. The bulge is produced in a beveled base region 32. The base is in turn supported by the support ribs 18 and attached to the side wall in a third base region 33. The first base region 31 has a width 4. The second base region 32 has a width 5. The third base region 33 has a width 6. The path which a fluid takes when flowing out of the cup interior outward in the direction of a blowout chute if the membrane 22, 23 tears is indicated by an arrow 50.

[0031] The first contact pressure means 25 is formed essentially cross-shaped and comprises four wing sections, of which three wing sections 41, 42, 43 are recognizable. Open regions 43, 44, in which the interior of the housing or the fluid-tight gas chamber, respectively, directly encounters the membrane 22, are located between the wing sections 41, 42, 43. This is advantageous because if an overpressure arises in the interior of the surge arrester or the housing 24, respectively, the gas pressure on the regions 43, 44 may cause the membrane 22 to bulge toward the interior of the cup-shaped locking means 1 and finally tear. If the membrane tears, the gas can thus flow into the cavity of the cup, whereby a first overpressure is slightly reduced. The bulge of the base 60 effectuates improved mechanical stability. Finally, the gas flow is laterally deflected and discharged in the direction of the arrow 50 through the first and the second outflow opening 51, 52, 53 to a blowout chute (not shown) of the surge arrester.