F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention:
IMPROVED TOGGLE MECHANISM FOR ELECTRICAL SWITCHING DEVICES

2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001, State of
Maharashtra, India

3. PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to electrical switching devices. More particularly the invention relates to an improved toggle mechanism for electrical switching devices.

BACKGROUND AND THE PRIOR ART

The invention relates to a switch primarily used for switching electrical equipment on or off. To achieve these functions, it is required that the position ON and OFF be defined securely by the switch. This may be performed by using springs to toggle between the two positions.

US 5934455A is related to a manually operated switch device with small operating play and precise function for the control of electrical equipment. The switch device comprises a switch housing, which has stationary contacts adapted thereto, and a contact bridging element with moving contacts, which is adapted to be movable. The switch is operated by means of an actuating member, which is adapted to be movable in the interior of the switch housing and is capable of transferring by a rotational motion of the actuating member the moving contacts to engage and disengage with the stationary contacts, and by means of a transmission means suitable for converting the rotational motion of the actuating member into an axial motion. Springs are adapted to cooperate with the transmission means so as to exert a spring force onto said transmission means for engaging and disengaging said contacts by virtue of having at least two springs employed so located at the opposite sides of the actuating member as to exert a symmetrical spring force on said actuating member and said transmission means. It is shown in Fig 1.

The article discusses the use of a double torque exerting mechanism that provides accurate positioning in ON and OFF positions for linearly sliding contacts. The prior art has the following disadvantages:
1. Not suitable for a rotary contact system.
2. Non-modular.
3. No provision for side operation.

Therefore there is a need to overcome the disadvantages of the prior art. The present invention provides a mechanism which is suitable for a rotary contact system. It is modular in spirit. Hence the same mechanism can be used for single pole, 2- pole, and so on without any modifications. Also present invention provides a provision for side operation.

OBJECTS OF THE INVENTION

A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.

Another object of the present invention is to provide improved toggle mechanism for electrical switching devices.

Another object of the present invention is to provide a modular setup for switching operation.

Yet another object of the present invention is to provide provision for side operation of toggle mechanism.

These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

There is provided an improved toggle mechanism for electrical switching devices.

According to one embodiment of the present invention, there is provided an improved toggle mechanism for electrical switching devices, said mechanism comprising a common housing means (1) providing support to said mechanism, a said housing having a plurality of slots; an actuating shaft (2) located in said housing means driving said mechanism, said actuating shaft couple to a working shaft (3) using multi toothed cam means; a rotary support means (4) having a plurality of holes; a plurality of floating spring rests (6); a plurality of mechanism spring means (7) resting on said floating rest and further connected to said working shaft; a plurality of end pins (9) whereby other end of said mechanism spring means rests; and a plurality of spring guides located on said end pins and held by said housing means.
Yet other embodiment of the present invention provides slots and holes adapted to provide side operation of toggle mechanism.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

So that those having ordinary skill in the art will more readily understand how to construct an improved toggle mechanism for electrical switching devices in accordance with the present disclosure, exemplary embodiments are described in details herein below with reference the accompanying drawings wherein:

Figure 1 illustrates the prior art corresponding to US005934455A.

Figure 2 illustrates the completely assembled mechanism.

Figure 3 illustrates the exploded view of the mechanism.

Figure 4 illustrates the construction of cage assembly.

Figure 5 illustrates the toggle linkage in OFF position.

Figure 6 illustrates the toggle linkage at dead centre position.

Figure 7 illustrates the toggle linkage in ON position.

Figure 8 illustrates the location of stoppers on the housing.

Figure 9 illustrates the functioning of the floating spring rest for dead centre instability.

Figure 10 illustrates the concept of indirect stacking.

Figure 11 illustrates the construction of C-shaped stacking box.

Figure 12 illustrates the provision for side operation of the mechanism.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.

Reference is first invited to Fig 1 where the prior art corresponding to US005934455A is shown.

Figure 2 shows the completely assembled mechanism.

Figure 3 shows the exploded view of the mechanism. It shows Common Housing, Actuating Shaft, Working Shaft, Rotary Support, Support Pin, Floating Spring Rest, and Mechanism Spring etc.

Figure 4 shows the construction of cage assembly. It shows Working Shaft, Rotary Support, Floating spring rest and rivet.

Figure 5 shows the toggle linkage in OFF position.

Figure 6 shows the toggle linkage at dead centre position.

Figure 7 shows the toggle linkage in ON position.

Figure 8 shows the location of stoppers on the housing.

Figure 9 illustrates the functioning of the floating spring rest for dead centre instability.

Figure 10 shows the concept of indirect stacking.

Figure 11 shows the construction of C-shaped stacking box.

Figure 12 shows the provision for side operation of the mechanism.

The invention is thus an improved toggle mechanism for electrical switching devices.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly in the present invention, there is provided a rotary mechanism for use in switches. The mechanism is supported on the common housing (1) (refer Figure 2). There is an actuating shaft (2) through which the mechanism is driven and this shaft is located in the common housing (bottom side).

The actuating shaft is coupled to the working shaft (3) with the help of a multi-toothed cam and both shafts rotate in planes perpendicular to each other. The working shaft together with the rotary support (4) and floating spring rests (6) forms the cage (refer Figure 3). The components in the cage are held together by rivets which do not restrict the relative rotation between them.

The mechanism springs (7) are resting on the floating rest that form a part of the cage and are thus indirectly connected to the working shaft. The other end of the mechanism spring rests on the end pin. The spring guides (8) are located on end pins (9) that are rigidly held by the common housings. The guides are free to move through the slot provided on the floating rest but the mechanism springs are not. The top and bottom common housings are held together by means of two C-shaped stacking boxes (11).

Working:

Consider the switch to be initially in the OFF position, a position where the toggle mechanism assumes a shape as in Figure 4. The actuating shaft (2) may be driven by the operator with the help of the handle shaft (14) rotating through an angle α. The actuating shaft then drives the working shaft (3) which rotates through an angle β. α is not necessarily equal to β. As the actuating shaft is an integral part of the cage assembly (see Figure 3), the cage itself rotates by an angle β. When the cage rotates, the floating rests begin to compress the mechanism springs (7). Human effort is required to take the toggle mechanism from OFF to dead centre (see Figure 5). It is in this position that the mechanism springs are fully compressed. From here on, the mechanism springs release the stored energy to take the toggle mechanism to ON position (refer Figure 6).

The mechanism is held in either the OFF or ON position with the help of stoppers provided on the housing. The actuating shaft and the working shaft are independently held in position as shown in Figure 7. The stoppers also limit the angle of rotation of the working shaft, β and actuating shaft, α respectively.

The unique toggle mechanism functions with the help of the novel floating rest concept (refer Figure 8). Unlike the prior art wherein the spring rests on spring arm or spring guide that is pivoted at both ends, the floating spring rest (6) is pivoted only at the working shaft end. This allows for less restriction on its degrees of freedom and a better chance for it to rotate freely. Also the floating spring rest is given a loose running fit with the rivet (10). The toggling of the entire cage depends on the floating spring rest. Any slight imbalance of forces will result in the toggling of the floating spring rest which ultimately results in the toggling of the cage.

Stacking of the two mechanism common housings (1) are done with the help of two C-shaped stacking box (11). In such a highly compact construction, there is not always space to pass a stacking screw through the mechanism. So, to optimize the use of available space a C-shaped stacking box is used for indirect stacking. Please refer to Figure 9. The housings are held at either end of the stacking box with the help of stacking screws (16).The construction of the C-shaped stacking box is illustrated in Figure 10.

Figure 11 demonstrates the side operation feature of the mechanism. The rotary support (4) also performs the function of a side operator. The circular slots on the housing and the holes provided on the rotary support may be used to operate the mechanism from the side.

FEATURES:

1. The mechanism has a unique toggle feature to develop instability at the dead centre position.
2. The mechanism uses a common top and bottom housing which reduces investment cost.
3. The mechanism is highly compact in construction which is unique for any rotary mechanism. The width is 17.5mm which permits it to fit into one module of the building electrical segment.
4. It is a modular mechanism that can be used for multiple of poles of the contact system.
5. The mechanism also has a provision for side operation.
6. The stacking of top and bottom housings is done with the help of a novel C-shaped box which optimizes the use of available space thus increasing the compactness of the mechanism.

Explode Part List:

1. Common Housing
2. Actuating Shaft
3. Working Shaft
4. Rotary Support
5. Support Pin
6. Floating Spring Rest
7. Mechanism Spring
8. Spring Guide
9. End Pin
10. Rivet
11. C-shaped Stacking Box
12. Auxilliary Contact Actuator
13. Top Cover
14. Handle Shaft
15. Shaft Locking Screw
16. Stacking Screw

Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM

1. An improved toggle mechanism for electrical switching devices, said mechanism comprising:
a common housing means (1) providing support to said mechanism, a said housing having a plurality of slots (18);
an actuating shaft (2) located in said housing means driving said mechanism, said actuating shaft couple to a working shaft (3) using multi toothed cam means;
a rotary support means (4) having a plurality of holes (19);
a plurality of floating spring rests (6);
a plurality of mechanism spring means (7) resting on said floating rest and further connected to said working shaft;
a plurality of end pins (9) whereby other end of said mechanism spring means rests; and
a plurality of spring guides located on said end pins and held by said housing means.
2. Mechanism as claimed in claim 1 wherein said actuating shaft and said working shaft rotating in planes perpendicular to each other.

3. Mechanism as claimed in claim 1 wherein said working shaft together with said rotary support means and said floating spring rests forming a cage thereby holding together components using a plurality of rivets.

4. Mechanism as claimed in claim 1 wherein said spring guides adapted to move through slot provided in said floating spring rests.

5. Mechanism as claimed in claim 1 wherein said common housing means is held by a pair of stacking boxes (11), said stacking boxes substantially C shaped.

6. Mechanism as claimed in claim 1 further comprising a handle shaft (14) driving said actuating shaft.

7. Mechanism as claimed in claim 1 further comprising a plurality of stopper means (17) provided on said housing means to limit rotation of said working shaft and actuating shaft.

8. Mechanism as claimed in claim 1 wherein said slots (18) and said holes (19) adapted to provide side operation of said mechanism.

9. An improved toggle mechanism for electrical switching devices as herein described and illustrated with reference to accompanying drawings.