WO2008132183A1

WO2008132183A1 - An electric switch

Info

Publication number: WO2008132183A1
Application number: PCT/EP2008/055108
Authority: WO
Inventors: Jan Domlin; Hans Johansson; Peder TJÄDERHANE
Original assignee: Abb Ab
Priority date: 2007-04-26
Filing date: 2008-04-25
Publication date: 2008-11-06
Also published as: CN201294187Y; EP1986208B1; EP1986208A1; DK1986208T3; RU2009141586A; NO20093417L; HK1124956A1; NO340350B1; RU2453944C2

Abstract

An electric switch comprising: a housing (1); a shaft (4) provided with at least one cam(18); at least two switch chambers (11-14), each of which is provided with at least one fixed electric contact element (6); at least two movable electric contact elements (8), one for each switch chamber (11,14); wherein the shaft (4) is arranged so as to displace the movable contact elements (11-14) through the action of the at least one cam (18) upon rotation of the shaft (4). The switch also comprises a movable bridge element (5) that is provided between the shaft (4) and the movable electric contact elements (8) and through which the action of the shaft (4) is transmitted to the movable contact elements (8).

Description

An electric switch

TECHNICAL FIELD

The present invention relates to an electric switch comprising: a housing; a shaft provided with at least one cam; at least two switch chambers, each of which is provided with at least one fixed electric contact element; at least two movable electric contact elements, one for each switch chamber; wherein the shaft is arranged so as to displace the movable contact elements through the action of the at least one cam upon rotation of the shaft.

The switch is preferably a so called side-operated enclosed switch. Typically, it is to be used in low voltage applications, preferably in the range of 16-40 Amperes. However, other ranges are also within the scope of the invention. Normally, the contact elements of different switch chambers are to conduct current of different phases.

BACKGROUND OF THE INVENTION

Side-operated switches have been known since long time. They normally comprise a shaft by means of which a plurality of movable electric contact elements are acted upon for the purpose of connecting them to or disconnecting them from a corresponding plurality of fixed contact elements located inside a housing of the switch. Thereby, the shaft is manually controlled by means of a handle provided on the outside of the switch housing. The main advantage of a side-operated switch compared to a front operated switch is that the housing, or enclosure, thereof can be opened without necessitating a removal of the handle. However, the design of the components of switches of prior art are of kinds that will either complicate the assembly or result in rather complicated large sized complex movable elements.

THE OBJECT OF THE INVENTION It is an object of the invention to present an electric switch the design of which is such that it presents the advantages of a side-operated switch while, at the same time, being of relatively uncomplicated design, and of low weight, and being easier to assemble than side-operated switches of prior art.

Accordingly, the switch of the invention should be easy to open without removal of an external handle connected to the shaft thereof. Components such as fixed electric contact elements (terminals) should also, in connection to the opening of the enclosure of the switch, be easily accessible and mountable.

SUMMARY OF THE INVENTION

The object of the invention is achieved by means of the initially defined switch, characterised in that it comprises a movable bridge element that is provided between the shaft and the movable electric contact elements and through which the action of the shaft is transmitted to the movable contact elements. The bridge element will act as a seat for a plurality of movable electric contact elements each of which is associated to an individual switch chamber. Preferably, the housing comprises at least two parts that can be separated from each. Thereby, assembly of the switch will be easy since it only requires that the shaft be positioned in one of the parts of the housing, placing the bridge element on the shaft, and placing the movable electric contact elements in individual seats provided therefore on the bridge element. The fixed contact elements are, preferably, fixed to the housing and arranged in such a position in relation to the movable elements that they will be connected to or disconnected from the latter as a result of a motion of the bridge element, in its turn caused by the rotation of the shaft and the resulting action of the cam or cams thereof. Also the fixed contact elements should be arranged such that they are easily accessible once the enclosure has been opened, in order to enable easy mounting thereof. Preferably, the shaft extends such that it passes at least one of, and preferably all of, said switch chambers, wherein two or more cams, preferably one for each switch chamber, is provided in order to act on the bridge element. Preferably, the bridge element is common for all of a plurality of movable contact element, each such element being arranged in a respective pocket or seat in the bridge element.

According to a preferred embodiment, there is provided two fixed electric contact elements in each switch chamber, at least one of which will be electrically connected to or electrically disconnected from the movable electric contact element upon rotation of he shaft. An advantage of having double electric contact elements in each switch chamber is that it will permit a design that facilitates the assembly of the switch, since all part can be put in place from one and the same direction and need not be fixated until the switch is fully assembled. Preferably, the fixed contact elements associated to one and the same movable contact element are located such that the movable element will be connected to or disconnected from both those fixed contact elements simultaneously upon motion of the movable contact element.

According to one embodiment, the switch comprises sealing elements between the switch chambers. The purpose of the sealing elements is to prevent ionized gas, generated in the switch during operation, from transferring electric arcs between the contact elements of different switch chambers, i.e. between different electric phases. Accordingly, the sealing elements are arranged so as to prevent gas from passing from one switch chamber to another. However, a total prevention is not required, but only to such a degree that said transfer of electric arcs will be sufficiently inhibited. Accordingly, though there are provided sealing elements, there may still be channels through which some gas may pass from one switch chamber to another, but only to a limited extent. Preferably, the sealing elements are arranged such that, regardless of the position of the bridge element, there will be no straight or wide channel between the switch chambers, but only narrow channels between adjacent sealing elements. Needless to say, it is preferred that the sealing elements be made of a dielectric material.

According to another embodiment the sealing elements comprises a wall element provided on the bridge element. Preferably, the sealing elements comprise at least one wall element of the housing, said wall element of the housing being arranged so as to be in an overlapping position with regard to said wall element on the bridge element regardless of the position of the shaft. The wall element of the housing may have the shape of a flange that overlaps the wall element of the bridge element, or, preferably, a recess into which the mating wall element provided on the bridge element projects. It should be noted that the overlapping wall elements may extend either in a direction corresponding to the longitudinal direction of said shaft, in order to provide for lateral sealing, or in a direction cross-wise to the longitudinal direction of the shaft, in order to provide for a sealing in said longitudinal direction.

According to preferred embodiment, the wall element of the housing comprises a recess into which said wall element of the bridge element protrudes, wherein the wall element of the bridge element is permitted to perform a sliding motion in said recess. Thereby, the recess will have the function of a guiding member while simultaneously contributing to the sealing between switch chambers.

According to one embodiment, said wall element of the bridge element has an extension plane cross wise to the longitudinal direction of the shaft, and, on a side of the bridge where the at least one cam of the shaft will not move upon turning of the shaft between its activated and non-activated positions there is provided a lateral wall element of the bridge element, said lateral wall element being in an overlapping position with regard to an adjacent wall element of the housing regardless of the position of the bridge element. This feature is particularly important when there will be generated a spacing between the shaft and the bridge element upon rotation of the shaft into the position in which it lifts the bridge element. Preferably, such a position will correspond to the disconnection of the phases in the switch as a result of a lifting of the movable contact elements off from the fixed contact elements. The lateral wall element will prevent an open passage between the switch chambers from upcoming due to such a lifting of the bridge element. Such lateral wall elements may be provided on one or more sides of the bridge element. According to a preferred embodiment, the at least one cam forms part of the sealing elements. Thereby an even more compact design of the switch will be promoted, since specific lateral sealing wall elements on the side of the bridge element where the cams perform their motion can be excluded.

Preferably, the sealing elements comprise a wall element of the bridge element, said wall element being provided between and separating two adjacent switch chambers, and that the at least one cam of the shaft overlaps said wall element when acting on the bridge element. The cam may also, or as an alternative this overlapping, overlap a wall element of the housing irrespectively of its position between the inactive and active positions thereof. This overlapping will be in a plane cross-wise or perpendicular to the longitudinal direction of the shaft. The cams will also fill up a space or channel that otherwise, in the absence of the cam, would have been generated between the switch chambers and the shaft due to the lifting action of the cams.

Preferably, the at least one cam overlaps said wall element (either of the bridge element or the housing) irrespectively of its position between its activated a deactivated positions.

According to one embodiment, the shaft is arranged so as to move between an activated position, in which the at least one cam lifts the bridge element, and a deactivated position, and, irrespectively of the position of the shaft between the activated and deactivated positions, the sealing elements will define a wall that fully separates two adjacent switch chambers as seen in the longitudinal direction of the shaft. Preferably, there are also provided lateral sealing elements that provide for a lateral sealing. Preferably, such elements include the wall elements described earlier, as well as the cams. According to the invention, the sealing elements comprise pairs of adjacent, overlapping surfaces of the bridge element and the housing and adjacent, overlapping surfaces of the bridge element and the at least one cam.

Preferably, the housing comprises a first part which forms a seat for the shaft and the bridge element, and a second part which forms a top. Thereby, assembly of the switch will be facilitated.

According to one embodiment, the switch comprises a prestress element provided so as to act upon the shaft. The objective of this pre-stressing of the shaft is to promote its rotation to either of an active or an inactive position of the cam or cams of the shaft.

According to a preferred embodiment, the prestress element is a spring element provided on the side of the shaft opposite to the side thereof at which the bridge element is located.

Preferably, the prestress element is located in the area of a switch chamber, and, preferably, the switch chamber in the area of which the prestress element is located is a switch chamber used for a neutral electric phase or for a auxiliary contact.

According to one embodiment, the switch comprises at least one ventilation opening extending from at least one switch chamber to the outside of the housing, wherein the distances between adjacent sealing elements between said at least one switch chamber and an open space between the bridge element and the shaft are adapted such that the pressure fall between said switch chamber and said open space is larger than the pressure fall between said switch chamber and the outside of the housing via said ventilation opening. In other words, the sealing elements are arranged so as to guarantee that ionized gas is ventilated out through the ventilation opening rather than from one switch chamber to another through the open space between the shaft and the bridge element. Preferably, each switch chamber is provided with a ventilation opening. Further features and advantages of the invention will be presented in the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter preferred embodiments of the invention will be described by way of example with reference to the annexed drawing, on which:

Fig. 1 is an exploded view of an electric switch according to the invention,

Fig. 2 is a cross-section of the assembled switch in a first position of a shaft thereof,

Fig. 3 is a cross section according to fig. 2 and HI-III in fig. 4, but showing the switch with the shaft in a second position,

Fig. 4 is a cross section according to IV-IV in fig 3,

Fig. 5 is a perspective view of a bridge element of the switch, and

Fig. 6 is a perspective view of a first part of a housing of the switch.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows the main components of a switch according to the invention. The switch comprises a housing generally indicated with 1 and comprising a first part 2 and a second part 3, a shaft 4, a bridge element 5, a plurality of fixed electric contact elements 6, means 7 for the fixation of the fixed contact elements, a plurality of movable electric contact elements 8, springs 9 for the biasing of the movable contact elements 8 towards the bridge element 5, and a prestress element 10 for stabilising the position of the shaft 4. Preferably, the switch will be enclosed in an enclosure (not shown), and preferably it also comprises lever or arm (not shown) that connects the shaft 4 to a handle or the like on the outside of such an enclosure. The handle is supposed to be manually manoeuvred for the execution of electric connection and disconnection by means of the switch. The switch is if a side-operated kind that allows opening of the enclosure and the housing 1 without necessitating any removal of the handle or the shaft 4.

When the switch is assembled, the housing 1, together with the bridge element 5, delimits a plurality of switch chambers 11, 12, 13 (see figs. 2-4). In each of these switch chambers 11-13 there is provided two opposite fixed electric contact elements 6' and 6". Each pair of contact elements 6', 6" represents one electric phase. Here there are proved three switch chambers 11-13, one for each of the phases of an electric distribution net connected to the switch. There is also provided a further, fourth switch chamber 14 that is used for a neutral electric phase or as an auxiliary switch chamber. The switch chambers 11-14 are arranged in a series, and the shaft 4 extends in the direction of that series of chambers 11-14, such that it passes under each chamber 11-14. The shaft is separated from the switch chambers 11-14 by a bottom part of the bridge element 5.

The bridge element 5 that contributes to the delimiting of the switch chambers 11-14 forms a seat for a plurality of movable electric contact elements 8, one for each switch chamber 11-14. The bridge element 5 is arranged such as to be able to move, preferably by way of sliding, from a first inactive position of the switch in which the movable contact elements 8 are in contact with the fixed electric contact elements 6 to an active position in which the movable contact elements 8 are removed, and thereby electrically disconnected, from the fixed contact elements 6. The bridge element 5 comprises a plurality of wall elements 15 that separate the switch chambers 11-14 from each other and that are arranged so as to slide in recesses 16 arranged in wall elements 17 of the surrounding housing 1. The wall elements 15 of the bridge element 5 and the recesses 16 of the wall elements 17 of housing will overlap each other in such a way that a sealing function is obtained between the individual switch chambers 11-14. The sealing function will help to prevent the upcoming of electric arcs between the individual switch chambers 11-14 due to the flow of ionized gases between individual switch chambers 11-14.

The shaft 4 comprises a plurality of cams 18, one for each switch chamber 11-14 and in alignment with each in the longitudinal direction of the shaft 4. In an inactive position, shown in fig. 2, in which the cams 18 of the shaft 4 do not act upon the bridge element 5, the cams 15 will point in a lateral direction towards a first lateral wall 19 of the first part 2 of the housing 1. In an active position shown in figs. 3 and 4, in which the shaft 4 is turned 90° from the inactive position, the cams 18 will be pointing towards the bridge element 5, thereby lifting the latter and the movable contact elements 8 seated therein such that there will be an electric disconnection of the latter from the fixed contact elements 6.

Upon motion of the shaft 4 between the inactive position shown in fig. 2 and the active position shown in fig. 3, an open space or channel 20 will appear between the shaft 4 and the bottom of the bridge element 5. In order to provide for a design as compact as possible, lateral openings are provided in the bridge element 5 between wall elements 15 that separate the switch chambers 11-14, the cams 18 being designed so as to protrude in the lateral direction through these openings in a first position, here the inactive position, and to obstruct or fill these openings, irrespectively of its position between the inactive and active positions. Thereby, the cams 18 of the shaft 4 will contribute to the sealing between the switch chambers 11- 14. Should the cams 18 not fill these lateral openings, there would be an open channel between the switch chambers due to the appearance of the open space 20 in connection to the motion of the cam shaft 4. However, as an alternative to the design shown here, one or more of the cams may be omitted from, whereby there should be provided a lateral wall element, preferably on the bridge element 5, for the purpose of preventing an open connection or channel from appearing between the open space 20 and the switch chambers 11-14. Such lateral wall elements 21 are provided on the lateral side of the bridge element on which the cams 18 will not be present. Corresponding lateral wall elements 22 are arranged in the housing, whereby the lateral wall elements 21 of the bridge element are to be in close and overlapping relation with regard to said lateral wall elements 22 of the housing 1 regardless of the position of the bridge element 5 between the active and inactive positions described earlier.

In order to provide for a ventilation of each switch chamber 11-14 in which ionized gas might be generated upon operation, ventilation openings 30 extend from the switch chambers 11-14 to the outside of the housing 1. The ventilation openings 30 extend through the top of the second, upper part 3 of the housing 1. The dimensions of these ventilation openings are such that the pressure fall over each of them will be lower than the pressure fall from each corresponding switch chamber 11-14 to the open space 20 between the shaft 4 and the bridge element. Thereby, gathering of ionized gas in the open space 20 will be inhibited, and ionized gases generated in the switch chambers 11-14 during operation will tend to be ventilated via said ventilation openings 30.

The first part 2 of the housing 1 comprises a seat 23 for receiving the shaft 4. Here the seat 23 comprises a plurality of arc-shaped rims arranged at the bottom of the first part 2 of the housing 1. From the lateral wall portion 19 of the first part 2 of the housing 1, wall elements 24 that form part of the wall elements 17, in which the recesses 16 for guiding the wall elements 15 of the bridge element 5, project into and fill the spacing between individual cams 18, at least in the inactive position of the latter. On the opposite lateral side of the first part 2 of the housing 1 the above- mentioned lateral wall elements 22 are arranged, as well as the wall elements 17 in which the recesses 16 for the guiding of the wall elements 15 of the bridge element 5 are provided.

The second part 3 of the housing 1 mates the first part 2 thereof, also in said second part there are provided wall elements 17 in which the recesses 16 are arranged, in alignment with the corresponding wall elements and recesses in the first part 2. The second part 3 of the housing 1 also comprises lateral wall elements 25 extending between the wall elements 17, thereby contributing to the delimitation of the switch chambers 11-14. It also comprise opposite end walls 26 and 27 extending cross wise to the longitudinal direction of the shaft 4 and forming the end limitation walls of the two outermost 11 and 14 of the switch chambers. Those end limitation walls could, as an alternative be formed by wall elements like the wall elements 15 of the bridge element 5. However, the described, preferred embodiment will permits the omission of such further wall elements 15 and contributes to a more compact and less material-requiring design. The second part 3 of the housing 1 also comprises seats 28 for the biasing elements 9, formed by helical springs, that will act on the movable contact elements 8 in a direction towards the fixed contact elements 6. Accordingly, the seats 28 as well as the biasing elements 9 will be located in the switch chambers.

The switch also comprises a prestress element 10 formed by a leaf spring provided on the bottom of the first part 2 of the housing 1 and acting on the cam shaft 4 in a direction towards the bridge element 5. Thereby, a sufficient sealing function will be promoted also if there should be a play between the shaft 4 and the bridge element 5, for example due to a deformation or wear of any of the components of the switch. The presence and function of the prestress element will also contribute to a more stable and high-qualitative impression given by the switch, since it will prevent any play between shaft 4 and bridge 5. In the embodiment shown, the prestress element 10 is located in the region of one of the outermost located switch chambers, more precisely the one 14 used for a neutral phase of auxiliary contact.

Claims

PATENT CLAIMS

1. An electric switch comprising

- a housing (1), - a shaft (4) provided with at least one cam (18),

- at least two switch chambers (11-14), each of which is provided with at least one fixed electric contact element (6),

- at least two movable electric contact elements (8), one for each switch chamber (11,14), - wherein the shaft (4) is arranged so as to displace the movable contact elements (11-14) through the action of the at least one cam (18) upon rotation of the shaft (4), characterised in that it comprises a movable bridge element (5) that is provided between the shaft (4) and the movable electric contact elements (8) and through which the action of the shaft (4) is transmitted to the movable contact elements (8).

2. An electric switch according to claim 1, characterised in that there is provided two fixed electric contact elements (6', 6") in each switch chamber (11-14), at least one of which will be electrically connected to or electrically disconnected from the movable electric contact element (8) upon rotation of he shaft (4).

3. An electric switch according to claim 1 or 2, characterised in that it comprises sealing elements (4, 15, 17, 21, 22, 24, 26, 27) between the switch chambers (11-14).

4. An electric switch according to claim 3, characterised in that the sealing elements (4, 15, 17, 21, 22, 24, 26, 27) comprise a wall element (15) provided on the bridge element (5).

5. An electric switch according to claim 3 or 4, characterised in that the sealing elements (4, 15, 17, 21, 22, 24, 26, 27) comprise at least one wall element (17) of the housing (1), said wall element (17) of the housing (1) being arranged so as to be in an overlapping position with regard to said wall element (15) on the bridge element (5) regardless of the position of the shaft (4).

6. An electric switch according to claim 5, characterised in that said wall element (17) of the housing (1) comprises a recess (16) into which said wall element (15) of the bridge element (5) protrudes, wherein the wall element (15) of the bridge element (5) is permitted to perform a sliding motion in said recess (16).

7. An electric switch according to any one of claims 3-6, characterised in that said wall element of the bridge element (5) has an extension plane cross wise to the longitudinal direction of the shaft (4), and that, on a side of the bridge element (5) where the at least one cam of the shaft (4) will not move upon turning of the shaft (4) between its activated and non-activated positions there is provided a lateral wall element (21) of the bridge element (5), said lateral wall element (21) being in an overlapping position with regard to an adjacent wall element (22) of the housing (1) regardless of the position of the bridge element (5).

8. An electric switch according to any one of claims 3-7, characterised in that the at least one cam (18) forms part of the sealing elements.

9. An electric switch according to claim 8, characterised in that the sealing elements (4, 15, 17, 21, 22, 24, 26, 27) comprise a wall element (15) of the bridge element (5), said wall element (15) being provided between and separating two adjacent switch chambers (11-14), and that the at least one cam (18) of the shaft (4) overlaps said wall element (15) when acting on the bridge element (5).

10. An electric switch according to claim 9, characterised in that the at least one cam (18) overlaps said wall element (15) irrespectively of its position between its activated a deactivated positions.

11. An electric switch according to any one of claims 3-10, characterised in that the shaft (4) is arranged so as to move between an activated position, in which the at least one cam (18) lifts the bridge element (5), and a deactivated position, and that irrespectively of the position of the shaft (4) between the activated and deactivated positions the sealing elements (4, 15, 17, 21, 22, 24, 26, 27) will define a wall that fully separates two adjacent switch chambers as seen in the longitudinal direction of the shaft (4).

12. An electric switch according to any one of claims 3-11, characterised in that the sealing elements comprises pairs of adjacent, overlapping surfaces of the bridge element (5) and the housing (1) and adjacent, overlapping surfaces of the bridge element (5) and the at least one cam (18).

13. An electric switch according to any one of claims 1-12, characterised in that the housing (1) comprises a first part which forms a seat (23) for the shaft (4) and the bridge element (5), and a second part which forms a top.

14. An electric switch according to any one of claims 1-13, characterised in that it comprises a prestress element (10) provided so as to act upon the shaft (4).

15. An electric switch according to claim 14, characterised in that the prestress element (10) is a spring element provided on the side of the shaft (4) opposite to the side thereof at which the bridge element (5) is located.

16. An electric switch according to claim 14 or 15, characterised in that the prestress element (10) is located in the area of a switch chamber (11-14).

17. An electric switch according to claim 16, characterised in that the switch chamber (14) in the area of which the prestress element (10) is located is a switch chamber (14) used for a neutral electric phase or for a auxiliary contact.

18. An electric switch according to any one of claims 1-17, characterised in that it comprises at least one ventilation opening (30) extending from at least one switch chamber (11-14) to the outside of the housing (1).

19. An electric switch according to claim 18, characterised in that the distances between adjacent sealing elements (4, 15, 17, 21, 22, 24, 26, 27) between said at least one switch chamber (11-14) and an open space (20) between the bridge element (5) and the shaft (4) are adapted such that the pressure fall between said switch chamber (11-14) and said open space (20) is larger than the pressure fall between said switch chamber (11-14) and the outside of the housing (1) via said ventilation opening (30).