Isolator switch with safety operating device

Abstract: An isolator switch with a safety device, consisting of a casing housing on one side a mobile contact element and on the other a mechanical operating device associated with an electromagnetic safety element which can be externally energized under danger or emergency conditions, the mechanical device being controlled by the operating shaft of the isolator switch.

Description: This invention relates to an isolator switch with a safety operating device. Many types of manually operated isolator switches are known which under normal conditions properly perform their basic switching function but which sometimes in emergency situations have the drawback that their mechanical tripping system becomes locked. Another problem of known switches of this type is that the switch has to be completely disassembled to provide access to the tripping mechanism. A switch comprising the features of the pre-characterising part of claim 1 is illustrated in EP-A-0 080 687. An object of the present invention is to provide a switch comprising both a mechanical tripping system and a safety device associated with the mechanical system. A further object of the present invention is to provide a casing in which the tripping mechanisms although protected are accessible with the casing assembled, both for emergency repair and for maintenance or parts replacement. These objects are attained according to the present invention by an isolator switch according to claim 1. The separate seat is accessible from the outside via at least one door. Preferably said seat is accessible via two doors, one provided in a position substantially corresponding with said mechanical operating device, and the other in a position substantially corresponding with said coil. According to the invention, said operating device is controlled by a shaft provided with a knob, said shaft passing centrally through said casing and said knob being positioned externally to said casing on the opposite side to said seat which houses the operating device and the safety tripping coil. According to the present invention said operating device consists of a horizontally disposed profiled lever provided laterally with a pair of vertical profiled plates, said plates being provided at one end with slots engaging a fixed pin, a pair of springs being provided fixed to said fixed pin and to a crosspiece of said profiled lever, said crosspiece carrying a further spring disposed centrally to said pair and fixed to a fixed point, there being also provided a movable member controlled by said shaft and engaged with said profiled lever and with a mobile spring-loading element, said profiled lever also being provided at its free end with a tang engageable either with a coil or with a fixed pin. According to a preferred form of the invention said vertical profiled plates form the positioner for said operating device and define positions of said movable member, namely a switch open position, a switch closed position and a switch loaded position. In addition said movable member preferably consists of a U-piece with tapered free ends and fixed at one end to said control shaft and at its other end, via a pin, to said loading element. Said loading element may consist of a pair of flat bars provided at one end with a slot movably engaging said pin of said U-piece, their other ends being bent outwards from said lever and pivoted on support bushes on the same axis as said control shaft but on the opposite side of said lever, said flat bars slidingly supporting a loading spring. The technical characteristics and further advantages of the present invention will be more apparent from the following description given by way of non-limiting illustration with reference to the accompanying drawings in which: Figure 1 is a partly sectional plan view of a switch in a first operating position; Figure 2 shows the elements of Figure 1 in a second operating position; Figure 3 shows the elements of Figure 1 in a third operating position; and Figure 4 is a section on the line IV-IV of Figure 1. In the figures the reference numeral 11 indicates overall an isolator switch according to the present invention. The switch 11 consists of a casing constructed in two halves, or half-casings 12 and 13 housing a mobile contact element 14, the half-casing 13 being also provided with a seat 15 in which a mechanical operating device indicated overall by 16 and a trip or safety opening coil 17 are provided. The half-casing 13 is also provided with a cover 18 in which doors 19 and 20 are provided to give partial access to the seat 15 without having to entirely disassemble the switch 11. The operating device 16 is controlled by a shaft 21 provided with a knob 22 and passing centrally through the half-casings 12 and 13. The knob 22 is provided on the opposite side of the casing to the cover 18. With particular reference to Figures 1 to 3, the operating device 16 consists essentially of a horizontally disposed profiled lever 23 provided laterally with a pair of vertical profiled lateral plates indicated overall by 24, said plates being provided at one end with slots 25 in sliding engagement with a pin 26. Said lateral plates 24 are also provided with stop teeth 45 and shaped guide portions 46 and 47 disposed on opposite sides of the stop teeth. A pair of springs 28 are fixed between the pin 26 and a crosspiece 27, a further spring 29 being provided centrally between the springs 28 and fixed to the crosspiece 27 and to a fixed point 30. There is also provided, in association with the lever 23, a movable member indicated overall by 31 and rotated by the shaft 21. The movable member 31 consists of a U-piece 32 having tapered free ends and fixed at one end to the control shaft 21 and at its other end, via a pin 33, to a mobile loading element indicated overall by 34. The mobile loading element 34 consists of a pair of flat bars 35 provided at one end with a slot 36 movably engaging the pin 33, while their other ends 37 are bent and pivoted by means of support bushes 38 on the same axis as the control shaft 21 but on the opposite side of the lever 23. On the flat bars there is slidingly mounted a loading spring 39 engaged with the bent ends 37 and with the pin 33. The lever 23 is also provided at its free end with an inclined tang 40 which can be moved by the action of a plunger 41 in a coil 17 positioned in its proximity, or be engaged during manual opening of the switch by a fixed pin 60 which progressively moves it upwards. The coil 17 can be energized from the outside when under emergency conditions, independently of the switch operation. Figure 1 shows the switch of the invention when open, with the movable member 31 and the loading element 34 shifted towards the profiled portion 46; the loading spring 39 is completely unloaded and the lever 23 is completely raised from the coil 17 and its plunger 41. If the shaft 21 is now rotated clockwise by the knob 22 (Figure 2), the movable member 31 and the loading element 34 move into proximity with the profiled portion 47, so moving the switch into its closed position in this manner. An anticlockwise half turn of the shaft 21 (Figure 3) is required to complete the closure of the switch and thus put it into its loaded state. In Figure 3 the movable member 31 has its pin 33 engaged with the tooth 45 of the lever 23, and the spring 39 retained by it is loaded. In this configuration the lever 23 is lowered with the tang 40 in contact with the coil plunger 41, the mobile contact element 14 closes its contacts (not shown) and the position of the pin 33 has shifted to the left of the line joining the axis of rotation of the movable member 31 and the loading element 34, the reaction of the spring 28 being sufficient when in this position to balance the action of the loading spring 39 and prevent the movable member tripping into the open position. The spring 28 is assisted by the spring 29 the purpose of which is to keep the lever 23 and in particular the tooth 45 in contact with the pin 33 of the movable member. The switch can be opened either manually by turning the knob anticlockwise (with respect to the figures) to return the switch to the position of Figure 1, or, if the shaft is locked or in any other abnormal or emergency situation, by the action of the coil 17, which forces the plunger upwards to shift the lever 23 so that the pin 33 is released from the tooth 45 and the movable member 31 and loading element 34 are able to trip towards the portion 46. In the case of manual opening, on rotating the shaft 21 the pin 33 engaged in the tooth 45 urges the lever towards the left to bring the tang 40 into contact with the pin 60. It should be noted that the lever 23 is able to move towards the left because of the slot engaged with the pin 26. During the opening movement the fixed pin 60 lifts the lever 23 and thus allows disengagement between the pin 33 and tooth 45, so enabling the switch to open.

Claims: An isolator switch (11) consisting of a casing constructed in two halves (12, 13), within which a multiple mobile contact element (14) is housed, one of said two halves (13) further housing a mechanical operating device (16) for said switch (11) in a seat (15) separated from said contact element (14), a coil (17) being associated with said mechanical operating device (16) for its safety tripping, a shaft (21), provided with a knob (22), for controlling said mechanical operating device (16) and also passing centrally through said casing and said knob (22), being positioned externally to said casing on the opposite side to said seat (15), which houses said mechanical operating device (16) and said coil (17), characterised in that said mechanical operating device (16) consists of a horizontally disposed profiled lever (23) provided laterally with a pair of vertical profiled plates (24), said plates (24) being provided at one end with slots (25) engaging a first fixed pin (26), a pair of springs (28) being provided fixed to said first fixed pin (26) and to a crosspiece (27) of said profiled lever (23), said crosspiece (27) carrying a further spring (29) disposed centrally to said pair of springs (28) and fixed to a fixed point (30), there being also provided a movable member (31) controlled by said shaft (21) and engaged with said profiled lever (23) and with a mobile spring-loading element (34), said profiled lever (23) having twc curved portions (46, 47), able to house said movable member (31) according to two fixed and separate working positions, so that said switch (11) is able to change over from a first working position to a second working position and to spring up from said two working positions, said profiled lever (23) being provided with a tooth (45) able to house said movable member (31) according to a third fixed working position, said profiled lever (23) also being provided at its free end with a tang (40), which can be moved by the action of a plunger (41) of said coil (17) when, if said shaft (21) is locked or in any other emergency situation, said coil (17) is energised from the outside and said switch (11) springs up from said first working position to said second working position, or can be engaged by a second fixed pin (60), which moves it upwards during the charging over from said third working position to said first working position, consisting of a manual turning of said knob (22) of said shaft (21), so that said lever (23) is also able to move because of said slots (25) engaged with said first fixed pin (26) and said second fixed pin (60) is able to lift said lever (23), allowing disengageament of said tang (40) from said plunger (41) of the coil (17). A switch (11) as claimed in claim 1, characterised in that said seat (15) separated from said contact element (14) is accessible from the outside via at least one door (19, 20). A switch (11) as claimed in claim 1, characterised in that said seat (15) separated from said contact element (14) is accessible via two doors (19, 20), one (19) of said two doors (19, 20) being provided in a position corresponding with said mechanical operating device (16) and the other (20) of said two doors (19, 20) being provided in a position corresponding with said coil (17). A switch (11) as claimed in claim 1, characterised in that said vertical profiled plates (24) form the positioner for said mechanical operating device (16) and define said three working positions of said movable member (31), namely said first working position being a switch opened position, said second working position being a switch closed position and said third working position being a switch loaded position. A switch (11) as claimed in claims 1 or 4, characterised in that said movable member (31) consists of a U-piece (32) with tapered free ends and fixed at one end to said shaft (21) and at its other end, via a third pin (33), to said mobile spring-loading element (34). A switch (11) as claimed in claims 1 or 5, characterised in that said mobile spring-loading element (34) consists of a pair of flat bars (35) provided at one end with a slot (36) movably engaging said third pin (33) of said U-piece (32), their other ends (37) being bent outwards from said profiled lever (23) and pivoted on support bushes (38) on the same axis as said shaft (21), but on the opposite side of said profiled lever (23), said flat bars (35) slidingly supporting a loading spring (39). A switch (11) as claimed in claim 5, characterised in that said switch opened position corresponds with the fact that said movable member (31) of said operating device (16) and said loading element (34) are shifted towards a first curved portion (46) of said lever (23), with said tang (40) completely raised from said plunger (41), said movable member (31) also having said third pin (33) engaged with said first curved portion (46) of the lever (23). A switch (11) as claimed in claim 5, characterised in that said switch closed position corresponds with the fact that said movable member (31) and said loading element (34) move into proximity with a second curved portion (47) of said lever (23), said movable member (31) also having said third pin (33) engaged with said second curved portion (47) of the lever (23), said switch closed position being assumed manually by rotating said shaft (21) by means of said knob (22) of the shaft (21), from said switch opened position. A switch (11) as claimed in claim 5, characterised in that said switch loaded position corresponds with the fact that said movable member (31) has said third pin (33) engaged with said tooth (45) of the lever (23), said tang (40) of the lever (23) being in contact with said plunger (41) and said mobile contact element (14) closing the electric circuit, said switch loaded position being assumed manually by turning said knob (22) of the shaft (21), from said switch closed position and said switch opened position being assumed manually by turning said knob (22) of the shaft (21), from said switch loaded position, so as to allow disengageament between said third pin (33) and said tooth (45).

Inventors: TOSI GIAMPIETRO, TOSI, GIAMPIETRO
Applicants: TOSI GIAMPIETRO, TOSI, GIAMPIETRO
Application year: 1990
Main classification: H01H71
IPC codes: H01H73, H01H71