GB2097192A - Anti-pumping interlock for circuit-interrupters - Google Patents

Abstract

An operating mechanism with anti-pumping interlock device comprises a closing pushbutton (36), a closing support (28) normally engaging a cam roller (16) on a closing cam (10) to prevent the rotation of the cam (10), and a double closure preventing plate (58) pivotally disposed on the pushbutton (36). During the closing of a contact set (22) of a circuit interrupter, the depression of the pushbutton (36) causes the plate (58) to abut against a stopping pin (64) on the support (28) to disengage the support (28) from the cam roller (16) to permit the cam (10) to rotate under the action of a spring 50 to close the contact set (22) through a main link (18) and a linkage (20). In the closed position of the contact set (22) the depression of the pushbutton (36) prevents the plate (58) from abutting against the stopping pin (64) to maintain the engagement of the support (28) with the cam roller (16). The depression of the pushbutton (36) in the tripped position prevents the rotation of the cam (10) because the support (28) engages the cam roller (16). The main link (18) is held spaced from the cam by the plate (58) (10) until the pushbutton is released. <IMAGE>

Description

SPECIFICATION Improvements in or relating to interlocking device This invention relates to improvements in an interlock device used in an operating mechanism for a circuit interrupter, a switching device or the like.

A conventional interlock device of the type referred to has comprised a closing cam rotatable only in one direction about the longitudinal axis of a crank shaft through an angle of 1 80 degrees at a time, a cam roller disposed within the closing cam, a main link including a roller disposed at one end thereof and normally falling into a recess on the closing cam to transmit the rotation of the closing cam to a linkage for opening and closing a contact set, and interlock pin connected to the linkage through a lever and including two operating positions corresponding to the open and closed positions of the contact set respectively.The device further comprises a spring loaded, pivotal closing support detachably engaging the cam roller to prevent normally the rotation of the closing cam, a closing pushbutton, a closing clutch pivotally connected to the closing pushbutton, and a closing lever engaged at both ends by the closing clutch and support respectively.

With the contact set put in its open position, the closing pushbutton is depressed to rotate the closing clutch into engagement with the interlock pin in one position thereof corresponding to the open position of the contact set and then rotate the closing lever until the cam roller disengages from the closing support. Thereafter the closing cam is rotated through an angle of 1 80 degrees about the axis of the crank shaft to put the main contact set in its closed position with the interlock pin displaced to the other position thereof corresponding to the closed position of the main contact set.

With the contact set put in its closed position, an operating mechanism involved may be operated to rotate the closing cam in the manner as described above to engage again the cam roller with the closing support resulting in the closure reset state in which the contact set is still in its closed position. As the interlock pin is fixed to the other position thereof by the lever connected to the linkage, the depression of the closing pushbutton permits the closing clutch to be rotated in a direction in which the closing lever acts to prevent the closing support from being rotated so as to disengage from the cam roller. Thus it is ensured that the closing support is maintained in engagement with the cam roller resulting in the prevention of the so-called double closure.

In the conventional interlock device as described above, the closing pushbutton may be maintained depressed while the main link disengages from the closing cam by a trip mechanism involved. At that time the interlock pin is in the one position thereof corresponding to the opening of the contact set and the operating mechanism can be operated to energize a closing spring to rotate the closing cam in the same manner as described above without the closing support engaged by the cam roller. This prevents the movement of the closing cam from being transmitted to the linkage resulting in the so-called trip-free phenomenon that the contact set is not brought into its closed position. If the operating mechanism continues to be operated then the closing spring is again energized resulting in the repetition of the trip-free phenomena which is called a pumping phenomenon.Therefore the conventional interlock device has been disadvantageous in that the crank shaft and other components may be badly damaged.

Accordingly it is an object of the present invention to provide a new and improved interlock device for the cam closure type of circuit interrupters and switching devices including an operating mechanism having a long operational life and improved reliability, by preventing the occurrence of the pumping phenomenon.

The present invention provides an interlock device for the cam closure type of circuit interrupters and switching devices comprising a closing support for bearing the rotation of a closing cam, a main link for transmitting the rotation of the closing cam to a linkage for opening and closing a contact set, and a double closure preventing plate for transmitting the movement of a closing pushbutton to the closing support in accordance with a position of the main link.

During the closure of the contact set, the double closure preventing plate may be preferably held in its position where the movement of the closing pushbutton is not transmitted to the closing support thereby to prevent the denergization of a closing spring.

In order to prevent the pumping phenomenon during the opening of the contact set with the closing spring energized in the operated state of the closing pushbutton, the double closure preventing plate may be held in its position where the movement of the closing pushbutton is not preliminarily transmitted to the closing support and said closing spring is prevented from being deenergized thereby to prevent the occurrence of a pumping phenomenon.

The present invention will become more readily apparent from the following detailed description given by way of example only and in conjunction with the accomanying drawings in which: Figure 1 is a fragmental elevational view of a conventional interlock device for a circuit interrupter illustrated at its open position; Figure 2 is a view similar to Fig. 1 but illustrating a transition position from the open to a closed position with parts omitted; Figure 3 is a view similar to Fig. 1 but illustrating the closed position; Figure 4 is a view similar to Fig. 1 but illustrating a closure reset position; Figure 5 is a fragmental elevational view of one embodiment according to the interlock device of the present invention for a circuit interrupter illustrated at its open position;; Figure 6 is a view similar to Fig. 5 but illustrating a transition point from the open to a closed position; Figure 7 is a view similar to Fig. 5 but illustrating a transition position from the closed to a closure reset position; Figure 8 is a view similar to Fig. 5 but useful in explaining the prevention of the double closure which may otherwise occurs at the closed position; and Figure 9 is a view similar to Fig. 5 but illustrating a transition position from the closed to the open position.

In a conventional interlock device for a circuit interrupter shown in Fig. 1, a closing cam 10 is rotatably connected to a lateral plate 1 2 through a crank shaft 14 so that it is rotatable only in a counterclockwise direction as viewed in Fig. 1 about the longitudinal axis of the crank shaft 14 through an angle of 1 80 degrees at a time by means of an operating mechanism (not shown). A cam roller 1 6 is fixedly secured to the closing cam 10 adjacent to the periphery and near to a recess disposed on the periphery, and a main link 1 8 includes a roller disposed at one end thereof and normally falling into the recess on the closing cam 10 and the other end connected to a linkage 20.The main link 1 8 serves to transmit the rotation of the closing cam 10 to the linkage 20 which, in turn, opens and closes a contact set 22 of a circuit interrupter.

In Fig. 1 the contact set 22 is shown as being in its open position.

The arrangement shown in Fig. 1 comprises further a lever 24 connected between the linkage 20 and a interlock pin 26 to bring the pin 26 into its position a during the opening of the contact set 22 and into its position b during the closure thereof. Then a closing support 28 is pivotally mounted on a pivot pin 30 suitably fixed to the lateral plate 12 and includes one end separably engaging the cam roller 1 6 and the other end connected to a stationary pin 32 through a tensioning spring 34. The closing support 28 in its position illustrated prevents the rotation of the closing cam 10 and the tensioning spring 34 is operated to hold the closing support 28 so as not to disengage from the cam roller 16.

The arrangement comprises further a closing pushbutton 36 pivotally mounted on a pivot pin 38 subsequently fixedly secured to the lateral plate 12, a closing clutch 40 pivotally mounted to a pivot pin 42 disposed on the closing pushbutton 36, and a closing lever 44 pivotally mounted to a pin 46 fixed to the lateral plate 1 2 at the lefthand and lower corner as viewed in Fig. 1. The closing lever 42 includes one end engaging the closing clutch 40 and the other end engaging the closing support 28 to transmit the movement of the closing clutch 40 to the closing support 28.

The operation of the arrangement shown in Fig. 1 will now be described. In Fig. 1 the contact set 22 is in its open position as described above and therefore the interlock pin 26 is in its position a. At that time, the depression of the closing pushbutton 36 causes the same to be rotated about the longitudinal axis of the pivot pin 38 in the the counterclockwise direction as viewed in Fig. 1 while at the same time moving the pivot pin 42 in the same direction. This movement of the pivot pin 42 causes the closing clutch 40 to be rotated in a clockwise direction as viewed in Fig. 1 about a fulcrum formed of that portion thereof engaged by the closing lever 42 until the closing clutch 40 abuts against the interlock pin 26. The term "counterclockwise" or "clockwise direction" used herein means a rotational direction as viewed in the associated Figure.

Then the closing clutch 40 causes the closing lever 44 to be rotated in the clockwise direction about a fulcrum formed of that portion thereof engaged by the interlock pin 26.

This is because the interlock pin 26 is fixed to its position a by the lever 24. This rotation of the closing lever 44 results in the transmission of a force from the closing clutch 40 applied to the closing lever 44 to the closing support 28. Thus the closing support 28 is rotated in the counterclockwise direction about the axis of the pivot pin 30 against the action of a force exerted by the tensioning spring 34 until the closing support 28 disengages from the cam roller 1 6 as shown in Fig.

2 wherein the arrangement of Fig. 1 is illustrated at transition position from its open to its closed position.

Therefore a closing spring (not shown) acts to rotate the closing cam 10 in the counterclowise direction through an angle of 180 degrees about the axis of the crank shaft 14 thereby to bring the contact set 22 into its closed position through the main link 1 8 and the linkage 20. At that time the interlock pin 26 is moved from its position a to its position b, and fixed to the latter.

Fig. 3 shows the arrangement brought into its closed position as described above.

Then the closing cam 10 put in its position as shown in Fig. 3 can be rotated in the counterclockwise direction through an angle of 180 degrees about the axis of the crank shaft 14 by means of the operating mecha nism (not shown). This results in the cam roller 16 engaging the closing support 28. In other words, the arrangement is brought into its closure reset state, in which the closing cam 10 and the closing support 28 occupy their positions relative to the main link 1 8 as shown in Fig. 4 with the contact set 22 maintained in its closed position.If the cam roller 1 6 disengages from the closing support 28 with the contact set 22 maintained in its closed position, that is to say, if the double closure is effected then the closing cam 10 is rotated in the manner as described above by means of the action of the closing spring (not shown). Thus the main link 18 is moved while contacting the closing cam 10 until the main link 1 8 is permitted to falls into the recess on the closing cam 10 (see Fig. 1). This causes a change in position of the main link 18 so that the contact set 22 changes from its closed to its open position and then again to its closed position resulting in an objectionable phenomenon that the contact set 22 damages and so on.

In order to prevent the occurrence of this objectionable phenomenon, the interlock pin 26 is held in its position b during the closure of the contact set 22 as shown in Fig. 4. In this case, when the closing pushbutton 36 is depressed, the closing clutch 40 is rotated in the clockwise direction about a fulcrum formed of that portion thereof engaging the closing lever 44. Therefore the closing support 28 is not permitted to be rotated in the counterclockwise direction through the closing lever 42. As a result, the closing support 28 is kept in engagement with the cam roller 1 6 to prevent the so-called double closure.

In the conventional interlock device for preventing the double closure as described above, an interlock (not shown) for deenergizing the closing spring or the like (not shown) may maintain the closing pushbutton 36 in its depressed state while a trip mechanism (not shown) is operated to maintain a tripped state in which the main link 1 8 disengages from the closing cam 1 0. Under these circumstances, the interlock pin 26 is in its position a shown in Fig. 2 and when the closing spring (not shown) is energized by the operating mechanism (not shown), the closing cam 10 is rotated in the counterclockwise direction through an angle of 1 80 degrees about the axis of the crank shaft 14 by means of the action of the closing spring (not shown) without the closing support 28 engaging the cam roller 1 6. As the tripped state is now maintained, the movement of the closing cam 10 is not transmitted to the linkage 20 resulting in the occurrence of the so-called trip-free phenomenon that the contact set 22 is not brought into its closed position.

If the operating mechanism (not shown) is not released from the operation then the closing spring (not shown) is again energized resulting in the repetition of the trip-free phenomena which is called a pumping phenomenon. This has resulted in the disadvantage that the crank shaft 14 and others damage greatly.

In Fig. 5 wherein like reference numerals designate the components identical or corresponding to those shown in Fig. 1, there is illustrated one embodiment according to the interlock device of the present invention used with a circuit interrupter. In the arrangement illustrated a crank 48 is fixed secured to the crank shaft 14 and connected to a closing spring 50 subsequently connected to a stationary pin 52. Then a trip mechanism 54 is operatively coupled to the free end of the main link 1 8 to maintain the latter normally engaged by the recess on the closing cam 10 through the roller disposed on the free end thereof.

Also the closing pushbutton 36 is pivotally secured to the pivot pin 38 and connected to a resetting spring 56 serving to return the pushbutton 36 rotated in the counterclockwise direction about the axis of the pivot pin 38 back to its original position shown in Fig. 5. A double closure preventing plate 58 is mounted on a pin 60 disposed on the closing pushbutton 36 for the rotation about the axis of the pin 60 and connected at one end to a tensioning spring 62 tending to rotate the same in the counterclockwise direction about the axis of the pin 60. Further the closing support 28 is pivotally mounted adjacent one end thereof to the pivot pin 38 and engaged at the other end by the cam roller 1 6 disposed on the closing cam 10 adjacent to the crank 48.The closing support 28 has a stopping pin 64 fixedly secured thereon adjacent to the other end thereof to transmit the movement of the double closure preventing plate 58 to the closing support 28.

In other respects the arrangement of Fig. 5 is substantially identical to that shown in Fig.

1.

The operation of the arrangement shown in Fig. 5 will now be described in conjunction with Figs. 5 to 9 inclusive. In Fig. 5 wherein the contact set 22 is shown as being in its open position, the main link 1 8 is in its position illustrated to engage the double closure preventing plate 58 with the roller on the main link 1 8 by means of the action of the spring 62 while closing spring 48 is put in its energized state. At that time, when the closing pushbutton 36 is forced or depressed in the direction of the arrow P shown in Fig. 5, the same is rotated in the counterclockwise direction about the axis of the pivot pin 38 which is attended with the rotation of the pin 60 on the pushbutton 36 about the axis of the pivot pin 38.This rotation of the pin 60 causes the double closure preventing plate 58 to be rotated in the clockwise direction about a fulcrum formed of that portion thereof en gaged by the main link 1 8 until the double closure preventing plate 58 abuts against the stopping pin 64. When the closing pushbutton 36 is further depressed in the direction of the arrow P, the double closure preventing plate 58 pushes against the stopping pin 64 to rotate the closing support 28 in the counterclockwise direction about the axis of the pivot pin 38. This results in the disengagement of the closing support 28 from the cam roller 1 6 as shown in Fig. 6 wherein the arrangement of Fig. 5 is illustrated at a transition position from its open to its closed position.Thereafter the closing spring 50 is operated to rotate the closing cam 10 in the counterclockwise to force the main link 1 8 toward the linkage 20. Thus the main link 18 partly retrogrades into the linkage 20 which, in turn brings the contact set 22 in its closed position as shown in Fig. 7.

In Fig. 7 wherein the contact 22 is shown as being in its closed position the main link 1 8 occupies its position illustrated where it partly retrogrades into the linkage 20 as described above while the double closure preventing plate 58 disengages from the main link 1 8 by means of the action of the spring 62. At that time the depression of the closing pushbutton 36 in the direction of the arrow P shown in Fig. 7 repeats the process as described above excepting that the double closure preventing plate 58 is rotated in the clockwise direction about the axis of the pin 60 on the closing pushbutton 36 by means of the action of the spring 62 thereby to prevent the double closure preventing plate 58 from engaging the pin 64 as shown in Fig. 8.

Therefore the closing support 28 is maintained in engagement with the cam roller 1 6 resulting in the prevention of the rotation of the closing cam 10 and accordingly of the socalled double closure.

The arrangement of Fig. 5 will now be described in conjunction with means for preventing the pumping phenomenon as described above. it is now assumed that the trip mechanism 54 has been tripped, that is, the arrangement of Fig. 5 is in the tripped state.

Under the assumed conditions, the trip mechanism 54 is released from the function of maintaining the main link 1 8 in engagement with the closing cam 10 but a resetting spring (not shown) disposed within the trip mechanism 54 is operated to pull the main link 1 8 toward the trip mechanism 54. Therefore the main link 18, the double closure preventing plate 58, the closing pushbutton 36 and the closing support 28 maintain the positional relationship as shown in Fig. 5. At that time, the depression of the closing pushbutton 36 in the direction of the arrow P shown in Fig. 5 results in the arrangement illustrated in Fig. 6.That is to say, the closing cam 10 is rotated in the counterclockwise direction but the rotation of the closing cam 10 is not transmitted to the linkage 20 through the main link 1 8 because of the presence of the tripped state. Thus the contact set 22 is not brought into its closed position so that the so-called trip-free phenomenon is caused.

However, with the trip mechanism put in its tripped state, an interlock (not shown) for deenergizing the closing spring 50 may be operated to energize the latter while the closing pushbutton 36 is maintained in its depressed state as described above. This results in the arrangement as shown in Fig. 9. More specifically the engagement of the double closure preventing plate 58 with the closing support 28 has been previously broken before the closing spring 50 is energized. In other words, the closing spring 50 is energized while the double closure preventing plate 58 is maintained in disengagement from the closing support 28. Thus the main link 1 8 abuts against the double closure preventing plate 58 upon the completion of the energization of the closing spring 50. As a result, the main link 18 is not reset.Also the closing support 28 does not disengage from the cam roller 1 6. Accordingly the closing spring 50 can not be deenergized resulting in the prevention of the so-called pumping phenomenon.

When the closing pushbutton 36 in its position shown in Fig. 9 is ceased to be forced, the resetting spring 56 is operated so that the closing pushbutton 36 tends to be rotated in the clockwise direction about the axis of the pivot pin 38 to be returned back to its original position shown in Fig. 5. This causes the pin 60 on the closing pushbutton 36 to be rotated in the clockwise direction about the axis of the pivot pin 38. This rotation of the pin 60 causes the double closure preventing plate 58 to make it difficult to move the closing support 28 due to a force with which the closing spring 50 engages the cam roller 1 6 with the closing support 28.

Therefore a reaction is generated on that portion of the double closure preventing plate 58 engaged by the stopping pin 64 and then cooperates with a reaction exerted by the spring 62 to space the main link 1 8 from the closing cam 10 against the action of the resetting spring (not shown) disposed within the trip mechanism 54 until the double closure preventing plate 58 disengages from the stopping pin 64. This results in the disappearance of the reaction exerted by the stopping pin 64. Therefore the resetting spring (not shown) disposed within the trip mechanism 54 functions to rotate the main link 1 8 in a direction in which the main link 18 engages the closing cam 10 against a force exerted by the spring 62 to rotate the double closure preventing plate 58 in the counterclockwise direction. Therefore the main link 1 8 can be returned back to its reset or position shown in Fig. 5. Thus the contact set 22 is put in its open position.

From the foregoing it is seen that the present invention is constructed so that in the tripped state, the closing support is prevented from disengaging from cam roller with the closing pushbutton maintained in its depressed state. Thus the present invention can prevent the occurrence of the pumping phenomenon and decrease an impact applied to an operating mechanism involved. Accordingly the operating mechanism becomes long in life time and the resulting reliability is improved.

While the present invention has been illustrated and described in conjunction with a circuit interrupter it is to be understood that the same is equally applicable to disconnecting switches, other switching devices etc. as long as they are of the cam closure type.

Claims (4)

1. An interlock device for the cam closure type of circuit interrupters and switching devices comprising a closing support for controlling the rotation of a closing cam, a main link for transmitting of the rotation of said closing cam to a linkage for opening and closing a contact set, and a double closure preventing plate for transmitting the movement of a closing pushbutton to said closing support in accordance with the position of said main link.

2. An interlock device for the cam closure type of circuit interrupters and switching devices according to claim 1 wherein, during the closure of said contact set said double closure preventing plate is held in its position where said movement of said closing pushbutton is not transmitted to said closing support thereby to prevent the deenergization of a closing spring.

3. An interlock device for the cam closure type of circuit interrupters and switching devices according to claim 1 wherein during the opening of the main contact set with a closing spring energized in the operation of the closing pushbutton, said double closure preventing plate is held in its position where the movement of said closing pushbutton is not preliminarily transmitted to said closing support and said closing spring is prevented from being deenergized thereby to prevent the occurrence of a pumping phenomenon.

4. An interlock device substantially as hereinbefore described with reference to and as illustrated in Figs. 5 to 9 of the accompanying drawings.