Electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like.

Abstract

 An electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like, comprising two mutually facing knives and a spacer which delimits the maximum mutual approach of the knives. The knives can move together in order to pass from an active position, in which their mutually facing lateral surfaces engage a main contact pin, to an inactive position, in which they are disengaged from the main contact pin, or viceversa. An element is provided which elastically contrasts the mutual spacing of the knives in order to maintain the contact of the knives, in the active position, with the main contact pin. The element comprises a contrast pin which passes through two seats which are formed in the two knives and are mutually aligned along a direction which is substantially perpendicular to the planes of arrangement of the knives. The contrast pin has, at its axial ends, two portions which form two mutually opposite shoulders which engage the lateral surfaces of the knives that lie opposite with respect to the mutually facing lateral surfaces. The two portions of the contrast pin can move away from each other in contrast with elastic means contained within the axial dimensions of the contrast pin.

Description

[0001] The present invention relates to an electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like.

[0002] Among the various kinds of electric contact with insertion coupling used in disconnectors, switches or the like, twin-knife insertion-coupling contacts are known which are substantially constituted by two mutually facing and spaced knives which are hinged, at one of their longitudinal ends, to a supporting structure; their opposite longitudinal end can engage or disengage, by virtue of their ability to oscillate about their pivoting axis, with a main contact pin so as to close or open the electric circuit on which the knives and the main contact pin are arranged.

[0003] A spacer is generally located in an intermediate region of the longitudinal extension of the two knives and delimits the maximum mutual approach of the two knives; said spacer can be constituted by the arm that connects the two knives to the actuator and can be actuated on command in order to cause the oscillation of the two knives about their pivoting axis.

[0004] In order to maintain contact between the main contact pin and the two knives when they are moved into engagement with the main contact pin, elastic means are provided which act on the two knives so as to contrast their mutual spacing.

[0005] Said elastic means are generally constituted by two helical springs which are fitted around a pin which passes through two aligned seats formed in the two knives and is arranged so that its axis lies at right angles to the plane of arrangement of the two knives. Two portions of said pin protrude from the lateral surfaces of the two knives that lie opposite with respect to the mutually facing lateral surfaces, and the two springs are fitted around these portions and are interposed between the outer lateral surface of the corresponding knife and a shoulder formed by a washer which is fitted around the pivot.

[0006] The locking of the washers that form the shoulders for the springs further forces to have a head which is larger than the diameter of the stem of the pin at one end of said pin and a lock nut at the other end of the pin.

[0007] This arrangement of the pin that supports the elastic means for contrasting the mutual spacing of the two knives entails relatively large external dimensions of the knives, causing problems particularly in the presence of a plurality of electric phases.

[0008] In this case there are in fact, for each phase, two knives and a corresponding main contact pin and the knives of the various electric phases are arranged side by side. The presence of the parts of the pins that support the springs, which contrast the mutual spacing of each pair of knives, is a limitation for a compact construction of the twin-knife insertion-coupling contacts of the three phases.

[0009] The excessive distance between the pairs of knives of the various phases is a problem affecting the dimensions of the entire disconnector, since the distance between the knives also constrains the dimensions of the other components of the disconnector.

[0010] The aim of the present invention is to solve the above-mentioned problems by providing an electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like, which can be very compact along a direction which is perpendicular to the plane of arrangement of the two knives.

[0011] Within the scope of this aim, an object of the present invention is to provide an electric contact with twin-knife insertion coupling which ensures high precision in the execution of the mounting of the knives.

[0012] Another object of the present invention is to provide an electric contact with twin-knife insertion coupling which provides high safety against the danger of accidental disassembly.

[0013] Another object of the present invention is to provide an electric contact with twin-knife insertion coupling in which it is possible to take up any play arising from the wear of said knives and of the main contact pin without thereby having to replace the knives or the main contact pin.

[0014] This aim, these objects and others which will become apparent hereinafter are achieved by an electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like, comprising two mutually facing knives and a spacer which delimits the maximum mutual approach of said knives, said knives being movable together in order to pass from an active position, in which their mutually facing lateral surfaces engage a main contact pin, to an inactive position, in which they are disengaged from said main contact pin, or viceversa, an element being provided which elastically contrasts the mutual spacing of said knives in order to maintain the contact of said knives, in said active position, with said main contact pin, characterized in that said element comprises a contrast pin which passes through two seats which are formed in said two knives and are mutually aligned along a direction which is substantially perpendicular to the planes of arrangement of said knives, said contrast pin having, at its axial ends, two portions which form two mutually opposite shoulders which engage the lateral surfaces of said knives that lie opposite with respect to the mutually facing lateral surfaces, said two portions of the contrast pin being movable away from each other in contrast with elastic means contained within the axial dimensions of said contrast pin.

[0015] Further characteristics and advantages of the present invention will become apparent from the following detailed description of an electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a schematic lateral elevation view of the electric contact with twin-knife insertion coupling according to the invention;

Figure 2 is a top plan view of a detail of the electric contact according to the invention;

Figure 3 is an enlarged-scale sectional view of Figure 2, taken along the plane III-III;

Figure 4 is an exploded perspective view of the contrast pin;

Figure 5 is an axial sectional view of the contrast pin with a pair of gauged-thickness disks fitted thereto.

[0016] With reference to the above figures, the electric contact with twin-knife insertion coupling according to the invention, generally designated by the reference numeral 1, comprises two knives 2a and 2b which face each other and are preferably hinged at one of their longitudinal ends to a supporting structure 3 about a pivoting axis 4.

[0017] A main contact pin 5 is fixed to the supporting structure 3 and is spaced from the pivoting axis 4, so that it can be engaged or disengaged by the longitudinal end of the two knives 2a and 2b that lies opposite to the end that is hinged to the supporting structure 3 following the actuated oscillation of the knives 2a and 2b about the pivoting axis 4.

[0018] A spacer is interposed between the two knives 2a and 2b and delimits the maximum mutual approach of the two knives 2a and 2b. Said spacer, as shown, can be constituted by the end of a linkage 6 which connects the knives 2a and 2b to an actuator 7 which can be actuated in order to cause the oscillation of the knives 2a and 2b about the pivoting axis 4 and therefore to produce their transfer from an active position, in which their mutually facing lateral surfaces engage the main contact pin 5, to an inactive position, in which they are disengaged from the main contact pin 5, or viceversa.

[0019] The electric contact according to the invention also comprises an element which elastically contrasts the mutual spacing of the two knives 2a and 2b in order to maintain the contact of the knives 2a and 2b with the main contact pin 5 in the active position.

[0020] Said element comprises a contrast pin, generally designated by the reference numeral 8, which passes through two through seats 9a and 9b formed in the two knives 2a and 2b and mutually aligned. The contrast pin 8 is arranged so that its axis is perpendicular to the planes of arrangement of the two knives 2a and 2b.

[0021] The contrast pin 8 has, at its axial ends, two portions 10 and 11 which form two mutually opposite shoulders 10a and 11a which engage the lateral surfaces of the knives 2a and 2b that lie opposite with respect to the mutually facing lateral surfaces. These two portions 10 and 11 of the contrast pin 8 can move mutually apart in contrast with elastic means which are contained within the axial dimensions of the contrast pin 8.

[0022] Conveniently, said elastic means are arranged inside the contrast pin 8.

[0023] More particularly, the contrast pin 8 comprises a substantially cylindrical body 12 inside which, starting from its axial end provided with the portion 10, a coaxial cylindrical cavity 13 is formed.

[0024] The cavity 13 is open at the longitudinal end of the body 12 provided with the portion 10 and has, at the opposite end of the body 12, a bottom 14 which is crossed centrally by a hole 15.

[0025] The portion 10 that forms the shoulder 10a is constituted by a flanged part of the lateral surface of the body 12 at the corresponding axial end.

[0026] The second portion 11 that forms the shoulder 11a is instead associated with a shaft 16 which is partially accommodated coaxially in the cavity 13 and protrudes, through the hole 15, from the axial end of the body 12 that lies opposite with respect to the end provided with the portion 10.

[0027] The elastic means are accommodated in the cavity 13 and are interposed between the bottom 14 of the cavity 13 and the axial end of the shaft 16 which lies opposite with respect to the axial end provided with the second portion 11. The axial end of the shaft 16 that abuts against the elastic means is conveniently constituted by a head 16a which has a larger diameter than the remaining part of the shaft 16 so as to form a shoulder against which the elastic means engage.

[0028] The elastic means are preferably constituted by a pack of Belleville spring washers 17 which are fitted around the shaft 16.

[0029] The portion 11 is preferably constituted by a disk-like element which is fitted on the end of the shaft 16 that protrudes from the body 12; said disk-like element is locked, in the opposite direction with respect to the body 12, by means of a locking element, preferably a dowel 18, which passes transversely through the shaft 16 and abuts against the face of the disk-like element that is directed away from the body 12, so as to prevent the extraction of the disk-like element from the shaft 16.

[0030] The dowel 18 is conveniently contained within a recess 19 formed in the face of the disk-like element, which constitutes the portion 11, that is directed away from the body 12.

[0031] As an alternative, the elastic means can be constituted by a helical spring instead of by Belleville spring washers, said spring being interposed between the head 16a of the shaft 16 and the bottom 14 of the cavity 13.

[0032] Advantageously, it is possible to interpose at least one disk 20 between the face of the disk-like element that constitutes the portion 11 and the axial end of the body 12 that is directed toward said disk-like element; said disk is perforated so as to allow the passage of the shaft 16 and has a gauged thickness in order to limit by the desired extent the maximum mutual approach of the shoulder 11a and of the shoulder 10a.

[0033] The disk-like element that constitutes the portion 11 has, on its face directed toward the body 12, a cylindrical protrusion 22 whose diameter is equal to the outside diameter of the body 12, so as to center the disk-like element in the seat 9a.

[0034] The actuator 7 can be a mechanical actuator or a fluid-driven actuator, as shown, of a known kind, which acts on the linkage 6, for example by means of a triangular articulation 21, so as to cause the oscillation of the knives 2a and 2b through an arc of preset breadth about the pivoting axis 4 in order to achieve their transfer from the active position to the inactive position or viceversa.

[0035] Owing to the fact that differently from conventional electric contacts with twin-knife insertion coupling the elastic means that contrast the mutual spacing of the two knives 2a and 2b in order to maintain the contact of said knives in the active position with the main contact pin 5 are arranged within the axial dimensions of the contrast pin 8, whose dimensions are only slightly larger than the overall transverse dimensions of the knives 2a and 2b, the electric contact according to the invention has significantly smaller dimensions than conventional electric contacts with twin-knife insertion coupling.

[0036] By virtue of this fact, particularly in the production of electric contacts with twin-knife insertion couplings for lines with a plurality of electric phases, it is possible to reduce the distance between the pairs of knives of the various phases, achieving an extremely compact set of electric contacts.

[0037] If the gauged-thickness disks 20 are used and wear of the main contact pin 5 or of the knives 2a and 2b occurs which entails a loss of adhesion force between the knives 2a and 2b and the main contact pin 5, it is possible to restore the required adhesion force simply by removing one of the gauged-thickness disks 20 without thereby having to replace the knives 2a and 2b or the main contact pin 5.

[0038] In practice it has been observed that the electric contact with twin-knife insertion coupling according to the invention fully achieves the intended aim and objects, since by virtue of the particular execution of the contrast pin and of the elastic means that contrast the mutual spacing of the two knives its dimensions transversely to the two knives are considerably reduced with respect to conventional electric contacts with twin-knife insertion coupling.

[0039] In practice, the materials used, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art.

[0040] The disclosures in Italian Utility Model Application No. MI98U000275 from which this application claims priority are incorporated herein by reference.

[0041] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. An electric contact with twin-knife insertion coupling, particularly for disconnectors, switches or the like, comprising two mutually facing knives and a spacer which delimits the maximum mutual approach of said knives, said knives being movable together in order to pass from an active position, in which their mutually facing lateral surfaces engage a main contact pin, to an inactive position, in which they are disengaged from said main contact pin, or viceversa, an element being provided which elastically contrasts the mutual spacing of said knives in order to maintain the contact of said knives, in said active position, with said main contact pin, characterized in that said element comprises a contrast pin which passes through two seats which are formed in said two knives and are mutually aligned along a direction which is substantially perpendicular to the planes of arrangement of said knives, said contrast pin having, at its axial ends, two portions which form two mutually opposite shoulders which engage the lateral surfaces of said knives that lie opposite with respect to the mutually facing lateral surfaces, said two portions of the contrast pin being movable away from each other in contrast with elastic means contained within the axial dimensions of said contrast pin.

2. The electric contact according to claim 1, characterized in that said elastic means are accommodated in said contrast pin.

3. The electric contact according to claims 1 and 2, characterized in that said contrast pin comprises a substantially cylindrical body inside which, starting from one of its axial ends, a coaxial cylindrical cavity is formed; a first one of said two portions being constituted by a flanged portion of the lateral surface of said body at said axial end, the second one of said portions being associated with a shaft which is accommodated coaxially in said cavity and protrudes from the opposite axial end of said body with respect to the axial end provided with said flanged portion, said elastic means being accommodated in said body and being interposed between the bottom of said cavity and the axial end of said shaft which lies opposite with respect to the end provided with said second portion.

4. The electric contact according to one or more of the preceding claims, characterized in that said second portion is constituted by a disk-like element which is fitted on the end of said shaft that protrudes from said body, a locking element being provided which contrasts the extraction of said disk-like element from said shaft away from said body.

5. The electric contact according to one or more of the preceding claims, characterized in that said locking element comprises a locking dowel which passes transversely through said shaft and abuts against the face of said disk-like element that is directed away from the body.

6. The electric contact according to one or more of the preceding claims, characterized in that said dowel is contained in a recess formed in the face of said disk-like element that is directed away from said body.

7. The electric contact according to one or more of the preceding claims, characterized in that the opposite end of said shaft with respect to the end provided with said disk-like element has a head provided with a larger diameter which forms a shoulder for one end of said elastic means.

8. The electric contact according to one or more of the preceding claims, characterized in that said elastic means comprise a pack of Belleville spring washers fitted on said shaft and interposed between the head of said shaft and the bottom of said cavity.

9. The electric contact according to one or more of the preceding claims, characterized in that said elastic means comprise a helical spring which is interposed between the head of said shaft and the bottom of said cavity.

10. The electric contact according to one or more of the preceding claims, characterized in that it comprises at least one disk which is centrally perforated and has a gauged thickness and can be interposed between said disk-like element and the axial end of said body that is directed toward said disk-like element in order to limit the maximum approach of said disk-like element to said flanged portion.

11. The electric contact according to one or more of the preceding claims, characterized in that said disk-like element has, on its face directed toward said body, a cylindrical protrusion whose diameter is equal to the outside diameter of said body for centering in the corresponding seat formed in the knife.

Drawing