GB2058457A

GB2058457A - An electrical disconnecting switch

Info

Publication number: GB2058457A
Application number: GB8023635A
Authority: GB
Original assignee: Kiepe Electric GmbH Germany; Kiepe Bahn Elektrik GmbH
Current assignee: Kiepe Electric GmbH Germany; Kiepe Bahn Elektrik GmbH
Priority date: 1979-09-01
Filing date: 1980-07-18
Publication date: 1981-04-08
Also published as: GB2058457B; DE2935420B1; IT1136542B; DE2935420C2; FR2464547B1; IN154833B; FR2464547A1; IT8083642A0

Abstract

A disconnecting switch suitable for snatch-cord emergency switching in a conveyor installation, comprises control contacts 2 operable by a lever (3) moving a rotary cam. The lever 3 is mounted on a shaft (5) which carries a transmission lever (6) which through a member (7) hinged thereto, is connected to strikers (8, 9) which engage in a respective diametrically opposed cut-outs 10, 11 on a striker disc (12) on the cam shaft 13. The cut-outs are each provided with a stop face (10a, 11a), the stop faces being effective in the same direction of rotation of the disc 12, the length of the cut-outs and the distances of the strikers 8, 9 from the hinge 6a of the member 7 on the transmission lever (6) are such that movement of the lever 3 in either direction, from the position shown, will produce clockwise rotation of the disc 12 and shaft 13 to a position (Figs. 2 and 3) in which the cam projection 4 actuates contacts 2 and subsequent movement of the lever 3 has no influence on the disc 12 etc. A spring 16 provides for snap-action movement between the two positions of the cam shaft 13 and a lever 19 thereon provides for resetting. <IMAGE>

Description

SPECIFICATION Electrical disconnecting mechanism This invention relates to an electrical disconnecting mechanism operable for example by an emergency snatch-cord, having a housing containing control switches which can be acutated from an actuator lever through a cam roller.

Emergency switch mechanisms of such kind are arranged for example at intervals along extended conveyor installations, and serve for switching off the installation in an emergency.

Usually a snatch-cord is fastened to the actuator lever running away from it in both directions along the conveyor installation, by means of which from any point on the conveyor installation switching off is possible by pulling on the snatch-cord.

With such known snatch-cord emergency switch mechanisms, after actuation of the switch mechanism they are secured in the disconnected position in such a way that the actuator lever is locked by a locking device, for example by a drop pawl. Unlocking is possible only at the switch itself through an unlocking lever by means of a resetting spring.

The known emergency switch mechanisms have certain disadvantages which impair their usefulness as emergency switches. Thus for example with such arrangements it is possible that by a violent tug on the snatch-cord, the locking mechanism does not operate, the actuator lever being carried back into the switched-on position, the disconnection of the installation being thereby cancelled.

Furthermore with the known switches it is difficult to ensure that also after a period of use the point of switching and the point of locking of the switching mechanism exactly coincide. This coincidence of the point of switching and the point of locking is particularly important for the safe functioning of the switch mechanism as an emergency switch mechanism. If the point of locking lies in front of the point of switching, the switching mechanism may become locked before it is disconnected. If the point of locking lies after the point of switching, the switching mechanism is in fact disconnected but not locked, and switches itself on again by the spring return.If for example through wear which occurs in service on the locking parts, maladjustment between the point of switching and the point of locking occurs, the absolute security of disconnection of the switch mechanism is not guaranteed, which greatly increases the risk of accident. It is particularly difficult to ensure that satisfactory adjustment is achieved permanently in both directions of actuation. In particular through the wear of the locking mechanisms themselves the risk of maladjustment is very great.

A further disadvantage of known switching mechanisms lies in the forces from the snatchcord acting directly upon the locking mechanism and thereby influencing the unlocking forces.

The invention is directed to a disconnecting mechanism whereby no problems of adjustment arise as regards the point of switching and point of locking, and that the disconnecting mechanism can no longer by violent operation be brought via the actuator lever, out of the disconnected position into the switched-on position and the unlocking or restoring forces are no longer influenced by the force of operation e.g. operating a snatch-cord.

The invention provides an electrical disconnecting mechanism operable for example by an emergency snatch-cord, comprising a housing containing a control switch which can be -actuated by an actuator lever moving a cam roller, characterised in that the actuator lever is rotatably mounted on a shaft for the cam roller upon which is also mounted a transmission lever which through at least one slider hinged thereto, is connected to two strikers which engage each in a cut-out portion mounted diametrically opposite to each other on a striker disc mounted on the said shaft, the said two cut-outs each being provided with a stop face the stop faces together being effective in the same direction of rotation of the striker disc, the said cut-outs and the distances of the said strikers from the hinge of the said slider(s) on the transmission lever being selected so that in the switched-on position of the cam roller both strikers rest against the stop faces of the cut-outs, and between the housing and mounting arranged on the said shaft a spring means is provided which, upon the rotation of the striker disc through a predetermined angle by the movement of the strikers on the stop faces, the cam roller is rotated with a snap actiori into the disconnected position, in which position the strikers can then slide freely in the said cut-outs.

It is particularly advantageous if the maximum angle of swing of the transmission lever is so dimensioned that the cam roller can by the strikers engaging in the cut-outs in the striker disc be carried positively out of the switched-on position into the disconnected position.

Stops may with advantage be arranged between the striker disc and the housing, which limit the angle of rotation between the switchedon position and the disconnected position.

Moreover it is useful to provide a re-setting lever functioning as a position indicator arranged on the shaft of the cam roller.

In a particularly advantageous embodiment a slider formed in the shape of a fork with two arms is hinged onto the transmission lever, the strikers being arranged respectively at the ends of the two arms of the slider. The cut-outs in the striker disc may be elongate arc-shaped apertures which are so dimensioned that in the disconnected position they enable free mobility of the strikers between two angular positions fixed by stops. Moreover the striker disc may be part of the cam roller.

As hereinafter described in one embodiment of the invention, the disconnecting mechanism of the invention has the great advantage that in the disconnected position no locking of the actuator lever takes place at all, but upon actuation the cam roller drops by a snap mechanism into the disconnected position and in doing so the actuator lever becomes uncoupled from the cam roller. The cam roller becomes secured in the disconnected position by the spring means, particularly a leaf spring, without its being possible for this position to be influenced by actuation of the actuator lever.

In this manner no problems of adjustment arise of the point of locking, since the switch mechanism from a particular position of the actuator lever in which it is lying neither in a disconnected position nor in a locked position drops as it were automatically into the disconnected position with positive opening of the contacts, out of which it can only be brought again via a resetting mechanism. In this way a very high degree of switching safety and mechanical safety is achieved.

One embodiment of the disconnecting mechanism in accordance with the invention is hereinafter described and illustrated in the accompanying drawings, of which Figure 1 is a representative side view of a disconnecting mechanism in accordance with the invention in the switched-on position; Figure 2 shows the disconnecting mechanism of Figure 1 in the disconnected position after actuation in one direction; and Figure 3 shows the disconnecting mechanism of Figure 1 in the disconnected position after actuation in the opposite direction.

In Figures 1 to 3 there is shown only the parts of the mechanism essential to the invention. Thus details of a housing surrounding the mechanism and of the actuator cord are not shown.

Referring to the drawings, a housing partly shown at 1 contains a control switch 2 which is controlled by a cam roller 4 of a striker disc 12 mounted on a shaft 1 3. A plurality of such control switches may be provided, either side-by-side or at different angular positions round the circumference of the cam roller 4. The cam roller 4 may be built up if desired from a plurality of discs which are arranged on a common shaft. An actuator shaft 5 is arranged in the housing, on which is pivoted actuator lever 3, extending in practice to outside the housing. A transmission lever 6 inside the housing is also provided on the shaft 5. A fork-shaped slider 7 is connected to the transmission lever 6 by a hinge connection 6a.

The two arms 7a and 7b of the slider 7 may, as shown in the Figures provide a V-shaped configuration, but other configurations may be adopted, for example having arms disposed in parallel with one another.

Strikers 8 and 9 made, for example in the form of studs, are provided at the ends of the two striker arms 7a and 7b. These strikers 8, 9 engage in cut-out portions 10, 11 in the said striker disc 12. In the embodiment illustrated the striker disc 12 is integral with the cam roller 4, which is for example one of the discs of the cam roller. It is possible however for the striker disc to be a separate item, mounted firmly on the shaft 13.

The cut-outs 10 and 11 are fashioned in the form of elongate apertures, and lie diametrically opposite one another on each side of the shaft 13.

One end of each of the two elongate apertures 10 and 11 acts as a stop face 1 Oa and 1 a respectively. In the switched-on position of the cam roller illustrated in Figure 1, the strikers 8 and 9 are resting against the respective stop faces. As shown in the drawings, the stop faces are arranged in such a way that the forces exerted by the strikers 8 and 9 upon the striker disc 12 can at any time become effective only in one of the two directions of rotation and thereby generate a torque.

Between the housing partly shown at 1 and a mounting 1 5 fastened to the shaft 13 there is arranged a leaf spring 1 6. Furthermore stops 1 7a and 1 7b are arranged on the striker disc 12 (or on the cam roller 4), which co-operate with a stop 18 on the housing 1 in such a way that rotation of the striker disc 12 is possible only-within a certain predetermined angular range.

A resetting lever 19 is fastened to the shaft 13 'of the cam roller 4, and functions also as a position indicator for the switched-on position "I" or the disconnected position "0".

Stops 20a and 20b are provided on the housing, which restrict the two end positions of the actuator lever 3.

The method of operation of the disconnecting mechanism illustrated is as follows: In figure 1 the switched-on position is shown.

The cam roller 4 is lying in a position in which the control switches 2 are not being actuated. The position indicator 1 9 is pointing to "I" and the strikers 8 and 9 are resting against the stop faces 1 Oa and 1 1 a of the cut-outs 10 and 11. For disconnection the actuator lever 3 is swung clockwise into the position illustrated in Figure 2.

With this motion the striker disc 12 is urged by the striker 8 in the direction of rotation D. After a predetermined angle of rotation the striker disc 12 under the influence of the leaf spring 16 is in known manner moved suddenly into the end position as in Figure 2. This end position is established by stopping of the stop 1 7b against the stop 1 8. In the disconnected position illustrated in Figure 2 the control switches 2 are now being actuated by the cam roller 4 and the position indicator 19 is pointing to "O". Return of the striker disc 12 by the actuator lever 3 into the position illustrated in Figure 1 is not possible, since the strikers can now slide freely in the opposite direction in the cut-outs 10 and 11. The actuator lever 3 and cam roller 4 are thereby uncoupled. Only by the resetting lever 19 can the cam roller 4 be carried back into the position as in Figure 1. From the drawings it is to be ascertained that the forces from a snatch-cord attached to the free end of the actuator lever 3 which may possibly act upon the actuator lever 3 can have no influence at all because of the uncoupling between the actuator lever 3 and the cam roller 4.

If the actuator lever 3 is moved out of the position illustrated in Figure 1 anti-clockwise, the striker disc 12 is urged by the striker 9. Rotation is effected again in the same direction of rotation D and the cam roller 4 under the action of the leaf spring 1 6 drops suddenly into the disconnected position illustrated in Figure 3. Return into the switched-on position illustrated in Figure 1 by the actuator lever 3 is again impossible because of the ability of the strikers 8 and 9 to slide freely in the cutouts 10 and 11. Resetting is possible only by actuation of the resetting lever 10. The resetting movement is in both cases limited by the cooperation of the stops 1 7a and 1 8.

As shown in Figures 1 to 3, the cut-outs 10 and 11 have a width which increases slightly away from the stop faces 1 Oa and 1 a. By this means complete uncoupling is achieved because of the ability of the strikers 8 and 9 to slide freely in both of the disconnected positions illustrated in Figures 2 and 3.

Other embodiments of the disconnecting mechanism according to the invention are possible. Thus for example the cut-outs from the striker disc may be formed as grooves made at the edge of the disc. Likewise instead of a fork-shaped slider two individual sliders may be employed which are separately hinged to the transmission lever 6.

In order to make possible secure disconnection even in the event of a breakage of the leaf spring 16, the angles of swing of the actuator lever 3 and the transmission lever 6 respectively are so designed that in such circumstances the striker disc 1 2 gets carried by the strikers 8 and 9 positively into the disconnected position illustrated in Figures 2 and 3, thereby enabling disconnection to be guaranteed.

Claims

1. An electrical disconnecting mechanism operable for example by an emergency snatchcord, comprising a housing containing a control switch which can be actuated by an actuator lever moving a cam roller, characterised in that the actuator lever (3) is rotatably mounted on a shaft (5) for the cam roller upon which is also mounted a transmission lever (6) which through at least one slider hinged thereto, is connected to two strikers (8, 9) which engage each in a cut-out portion (10, 11) mounted diametrically opposite to each other on a striker disc (12) mounted on the said shaft, the said two cut-outs each being provided with a stop face (1 Oa, 11 a) the stop faces together being effective in the same direction of rotation of the striker disc, the said cut-outs and the distances of the said strikers from the hinge of the said slider(s) on the transmission lever (6) being selected so that in the switched-on position of the cam roller (4) both strikers rest against the stop faces of the cut-outs, and between the housing and a mounting ( 1 5) arranged on the said shaft a spring means (16) is provided which, upon the rotation of the striker disc through a predetermined angle by the movement of the strikers on the stop faces the cam roller is rotated with a snap action into the disconnected position, in which position the strikers can then slide freely in the said cut-outs.

2. A mechanism as claimed in Claim 1, wherein the maximum angle of swing of the transmission lever is determined so that the cam roller can by the strikers engaging in the cut-outs in the said striker disc, be carried positively from the switched-on position into the disconnected position.

3. A mechanism as claimed in Claim 2, wherein stops are arranged between the striker disc and the housing which limit the angle of rotation between the switched-on position and the disconnected position.

4. A mechanism as claimed in any of Claims 1 to 3, wherein a resetting lever functioning as a position indicator is arranged on the shaft of the cam roller.

5. A mechanism as claimed in any of Claims 1 to 4, wherein the slider is provided with two arms and which is hinged onto the transmission lever, the strokers being arranged respectively at the ends of the two arms of the slider.

6. A mechanism as claimed in any of Claims 1 to 5, wherein the cut-outs in the striker disc are elongate arc-shaped apertures so that in the disconnected position the strikers are free to move between two angular positions fixed by stops.

7. A mechanism as claimed in any of Claims 1 to 6, wherein the striker disc is part of the cam roller.

8. An electrical disconnecting mechanism substantially as hereinbefore described and illustrated in the accompanying drawings.