DESC:Field of invention

The present invention relates to a switch, particularly, the present invention relates to a snap action type electric switch, more particularly, the present invention related for a mechanism of a snap action electrical switch for fast making and breaking of contacts.

Background of the invention

Snap action electric switches are generally known for operating one or more circuits. In a snap action switch there is provided with a contact bridge which bridges the fixed contacts of a circuit. If the snap action switch is configured to operating two circuits in which only one electrical circuit (say first circuit) is closed at one time by the contact bridge. The contact bridge is actuated or moved to close or bridge the fixed contact of the other one (say second circuit) of the two circuits and opening the first circuit. It is desirable, in a snap action switch that there is discrete change over between the closing of two circuits (first and second circuit). In other words, when the first circuit is closed and the snap action switch is actuated to close the second circuit, the contact bridged should move quickly to open and first circuit and closing the second circuit.

GB 886, 253 discloses a snap action type electrical switch as shown in Figures 1 (a) and 1 (b). Referring to Figure 1(a), the switch (1) is in normal state and the circuit is in between terminal-1 (T1) and terminal 2 (T2). To make the circuit between terminal 3 (T3) and terminal 4 (T4), plunger (2) is pressed downwards for moving a contact plate (3) for bridge the terminal 3 (T3) and terminal 4 (T4). The movement of plunger (2) is transferred to the moving contact plate (3) by a pair of springs (4) which are connected with moving contact plate (3). However, the said springs (4) are not guided results into formation of bow type structure (i.e. buckling) in the springs (4) which may lead to the failure of the springs (4) due to buckling when plunger (2) is pressed downward. Further, buckling (or formation of bow) in the springs (4) results in no contact condition in second circuit even after the full movement of the plunger (2) and thus defeats the intended function of the switch (1).

Referring to Figures 1 (a)-(b), the two springs (4) apply opposite forces on the plunger (2) when the plunger (2) is pressed downward and therefore, the switch (1) shown in Figure 1 does not have a discrete changeover point from circuit 1 to circuit 2. In other words, when the plunger (2) is pressed downwards, a direct load from spring (4) transfers on the plunger (2) resulting in restriction in vertical movement of the plunger (2) and hence causes in sticky movement. As plunger (2) is forced to slide in the housing due to axial force applied by the spring (4), excessive wear and tear of the parts may take place which leads to premature failure.

Referring to Figure 1 (a)-(b), ends of the each spring (4) are rested in cup shape washers (5). At one end, the cup shape washer (5) is supported on the edge of the plunger (2) and on the other end, the cup shape washer (5) is supported is supported on an edge of moving contact holder. This shows that no rigid locking of the spring (4) was provided and will have tendency to fall off or popping of spring outside and will have difficult in assembly and will promote the causes of no contact.

When the plunger (2) is pressed to close/make the circuit between terminal 3 (T3) and terminal 4 (T4), there is no discrete stopper for the plunger moment even after the changeover to second circuit (i.e. circuit between terminal 3 (T3) and terminal 4 (T4)). In second circuit position, the plunger (2) can be over pressed since there are Gaps (G) as shown in Figure 1(b) and hence results in the no contact in second circuit.

The moving contact (3) is a leaf spring in switch as shown in Figures 1 (a)-(b). The leaf spring type moving contact unbends and gets straightened when the contact is made and the moving contact bends back when the contact is break. This bending and unbending of moving contact result in formation of the stress and leads to breakage of moving contact before intended number of cycles thereby resulting in loss of continuity. In addition, number of parts in the moving contact assembly is more which actually increase the thickness of moving contact assembly and requirement of flexible contacts which actually limits the size of current carrying parts in the assembly, results in thin cross-section of the conductor in the switch and hence results in switch which is meant for lesser ampere switching.

Therefore, there exists a need to develop a snap action switch which provides a discrete changeover or toggle point when changing from the one circuit position to the other circuit position and which overcomes at least one of the problems associated with the existing/prior art switch. The main aim of the present invention is to provide a snap action switch for fast making and breaking of contacts and which overcomes at least one of the problems associated with the prior art/existing snap action switch.

Summary of the present invention

The present invention provides a snap-action type electrical switch. The switch, comprising a housing having an interior and a pair of fixed-contact assemblies oppositely disposed in the housing, each of the fixed contact assembly comprises a pair of contact-terminals. The switch also includes an actuator plate comprising a central opening and said actuator plate is moveable between the pair of fixed-contact assembly defining a first position and a second position, in the each position the actuator plate bridges the contact-terminals of the one fixed contact assembly. An actuator assembly is provided for moving the actuator plate between the first position and the second position. The actuator assembly comprises a carrier supported on a first spring disposed in the housing so that the carrier is moveable under a force of the main spring between the first position and the second position of the actuator plate. The actuator assembly also comprises a first arm and a second arm, each having a proximal end hingedly secured to opposing sides of the actuator plate and a distal end supported on the carrier; and a second spring is disposed between the proximal end and distal end of the first arm. The distal ends of the first arm and the second arm are secured to each other by a connection which allows relative movement there between and so that the vertical movement of the carrier forces the first arm and the second arm against a force of the second spring towards the central opening. The distal end of the second arm is formed to define a toggle point between the first position and the second position of the actuator plate and wherein the toggle point is defined as a point immediately after which the position of the actuator plate changes from first position to the second position or vice versa.

Brief description of drawings

Figures 1 (a) -1(b) illustrate existing/prior art construction of the snap action switch.
Figure 2(a)-(b) illustrate a snap-action type switch according to an embodiment of the present invention.
Figures 3(a)-(d) and 4(a)-(g), illustrate some of the major components of the switch shown in Figure 2.

Detailed description of the present invention

While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims.

Before describing in detail the various embodiments of the present invention it may be observed that the novelty and inventive step that are in accordance with the present invention resides in the construction of snap-action type switch. It is to be noted that a person skilled in the art can be motivated from the present invention and modify the various constructions of snap-action type switch. However, such modification should be construed within the scope and spirit of the invention.

Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

The terms “comprises”, “comprising”, “including” or any other variations thereof, are intended to cover a non-exclusive inclusion, such that an assembly, mechanism, setup, that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such assembly, mechanism or setup. In other words, one or more elements in snap-action type switch or assembly proceeded by “comprises a” does not, without more constraints, preclude the existence of other elements or additional elements in the assembly or mechanism. The following paragraphs explain present invention and the same may be deduced accordingly.

Accordingly, the present invention provides a snap-action type electrical switch, comprising:
a housing having an interior;
a pair of fixed-contact assemblies oppositely disposed in the housing, each of the fixed contact assembly comprises a pair of contact-terminals.
an actuator plate comprising a central opening and said actuator plate is moveable between the pair of fixed-contact assembly defining a first position and a second position, in the each position the actuator plate bridges the contact-terminals of the one fixed contact assembly;
an actuator assembly for moving the actuator plate between the first position and the second position; the actuator assembly comprising:
a carrier supported on a first spring disposed in the housing so that the carrier is moveable under a force of the main spring between the first position and the second position of the actuator plate;
a first arm and a second arm, each having a proximal end hingedly secured to opposing sides of the actuator plate and a distal end supported on the carrier;
a second spring is disposed between the proximal end and distal end of the first arm;
wherein the distal ends of the first arm and the second arm are secured to each other by a connection which allows relative movement there between and so that the vertical movement of the carrier forces the first arm and the second arm against a force of the second spring towards the central opening, and the distal end of the second arm is formed to define a toggle point between the first position and the second position of the actuator plate and wherein the toggle point is defined as a point immediately after which the position of the actuator plate changes from first position to the second position or vice versa.

In an embodiment of the present invention the housing is provided with guide-ways for guiding outer edges of the actuator plate.

In another embodiment of the present invention the actuator plate is provided with guiding-pads at the opposing outer edges for freely guiding actuator plate within the housing.

In still another embodiment of the present invention the carrier comprises
a first end secured to a plunger for applying actuating force;
a second end opposite to the first end, and supported on the first spring; and
an intermediate portion between the first end and the second end, for supporting the distal ends of the first arm and the second arm.

In yet another embodiment of the present invention the connection connecting the first arm and second arm, comprising
a connecting pin provided at the distal end of the first arm;
an elongated slot disposed at the distal end of the second arm for receiving the connecting pin thereby securing the distal ends of the first arm and the second arm; and the slot is sized to cooperate with the connecting pin so as to allow relative movement there between the distal ends of the first and second arms.

In a further embodiment of the present invention the intermediate portion of the carrier is provided with an elongated slot to receive the connecting pin for supporting the distal ends of the first and second arms and the elongated slot is sized so as to accommodate lateral movement of the connecting pin resulted due to relative movement of the distal ends of the first and second arms.

In a further more another embodiment of the present invention the first arm is a rigid strip having a proximal end hingedly secured to the actuator plate and a distal end provided with a hole for receiving the connecting pin.

In another embodiment of the present invention the second spring placed around the entire length of the first arm.

In still another embodiment of the present invention the second arm comprises two identical rigid strips located spaced apart defining a gap there between and the distal end of the first arm is placed between the said gap; and wherein the each strip having a proximal end and a distal end collectively forming the proximal end and the distal end of the second arm, respectively.

In yet another embodiment of the present invention the proximal ends of the rigid strips of the second arm are hingedly secured to the actuator plate, and each of the distal ends of the rigid strips of the second arm comprises a cam.

In a further embodiment of the present invention the cams provided at the distal ends of the strips of the second arm are profiled to define the toggle point during the movement of the arms towards the central opening of the actuator plate.

In further more embodiment of the present invention the toggle point is defines so that movement of the carrier and the first and second arms towards the central opening of the actuator plate from the first or second position results in no movement of the actuator plate before the toggle point is achieved and immediately after the toggle point, the actuator plate is moved to the second or first position.

In another more embodiment of the present invention the connecting pin is located with the help of bush for supporting ends of connecting pin in the slot of the carrier and locking the ends of the connecting ping to avoid fall off the connecting from the distal ends of the first and second arms.

In one more embodiment of the present invention the actuator plate is made up of thick copper conductor.

The following description describes the snap action type switch in reference to Figures 2-4 according to an embodiment of the present invention.

Referring to Figures 2(a)-(b) and 3(a)-(d), the snap-action type switch (100) of the present invention comprises housing (101) having an interior (102). For this purpose, the housing comprises side walls (103) and a bottom wall (104) defining an interior (102), and a top opening (105) for accessing to the interior (102) of the housing (101). A pair of fixed contact assemblies (106, 107) is disposed in the housing (101) opposite to each other. The two fixed contact assemblies (106, 107), each comprising two contact-terminals (also referred herein terminals) (T10, T20, T30, T40) which are placed in a same plane substantially perpendicular to the side walls (103) (as shown in Figure 2(a)). The housing is provided with slots (108) for inserting the terminals (T10, T20, T30, T40) of the fixed contact assemblies ((106, 107)) (as shown in Figure 3(a)).

As shown in figures 2(a)-2(b), two terminals, for example, a first terminal (T10) and a second terminal (T20), together forming a fixed contact assembly (106) is disposed in the housing (101) on a plane perpendicular to the sidewalls (103) of the housing (101). Also, the other two terminals, for example, a third terminal (T30) and a fourth terminal (T40), together forming another fixed contact assembly (107) is disposed in the housing on a plane perpendicular to the sidewalls (103) of the housing (101). As can be noticed, the plane in which the first and second terminals (T10, T20) are disposed is generally parallel to the plane in which the third and fourth terminals (T30, T40) are disposed, thereby, the two contact assemblies (106, 107) are place opposite to each other.

The two terminals (T10, T20, T30, T40) in each contact assembly (106, 107) may form part of one circuit and therefore, the two contact assemblies (106, 107) may form part of two circuits. For example, the first and second terminals (T10, T20) may form part of one circuit, and the third and fourth terminals (T30, T40) may form part of other circuit. To close the circuits, the respective terminals (T10, T20, T30, T40) are required to be bridged. For this purpose, an actuator plate (109) is disposed in the housing (101). The actuator plate (109) is moveable between the pair of fixed contact assembly (106, 107) to bridge the terminals (T10, T20, T30, T40) of the fixed-contact assembly. The actuator plate (109) is a rigid plate and made up of electrically conductive material for example thick solid copper conductor. The actuator plate (109) can be moved from a first position to a second position. In the first position, the actuator plate (109) bridges the contact between the first and second terminals (T10, T20). In the second position, the actuator plate (109) bridges the contact between the third and fourth terminals (T30, T40). As shown in Figures 2(a)-(b) and 3(a), the edges of the actuator plate may be guided in the guide ways (110) formed on the side walls (103) at interior (105) of the housing (101). For this purpose, the edges of the actuator plate may be provided with a pair of lugs or guiding pads (111) (shown in Figure 4(f)) which cooperate with the guide ways (110) for freely guiding the actuator plate (109) within the housing (101).

As described in previous paragraph, that the actuator plate (109) is required to move quickly to break contact with one fixed contact assembly and quickly make contact with the other fixed contact assembly to desirable functioning of the switch. For this purpose, the snap-action type switch of the present invention comprises an actuator assembly for moving the actuator plate from first position to the second position or vice versa.

Referring to Figures 2-4, an actuator assembly (112) comprises a carrier (113) which can be supported on a spring (herein after first spring) (S1) placed in the housing (101). The carrier is having two ends, a first end (114) and a second end (115), and an intermediate portion (116) between the first end (114) and the second end (115). The first end (114) can be secured or coupled to a plunger (117) which can be used for transmitting actuating force for actuating the carrier (113). For this purpose, first end (114) may be provided a projection which can be used as a plunger or may be coupled with a separate plunger. The second end (115) of the carrier (113) is supported on the first spring (S1). For this purpose, the second end (115) is provided with a locating pin (118) for locating the carrier (113) on the first spring (113).

As shown in Figures 2(a)-(b) and 3(b), the actuator plate (109) is provided with a central opening (119) and the second end (115) of the carrier (113) access the first spring (S1) through the said central opening (119) of the actuator plate (109). Also, the central opening (119) of the actuator plate (109) is sized to allow movement of the carrier (113) through the central opening (119). It can be clearly understood from the configuration shown in Figures 2(a), any force in the direction of arrow results in movement of carrier (113) against force of the first spring (S1).

Referring to Figures 2-4, the actuator assembly (112) comprises a first arm (120) and a second arm (121) for coupling the carrier (113) with the actuator plate (109). For this purpose, the first arm (120) and the second arm (121) provided with a proximal end (P0, P1) which are hingedly secured at opposing sides of the actuator plate and a distal end (D0, D1)) which is supported on the carrier. In other words, the proximal end (P0) of the first arm (120) is hingeldy secured using a hinge (H0) to the one side of the actuator plate (109) and the proximal end (P1) of the second arm (121) is hingeldy secured using a hinge (H1) to the other side which opposite to the said one side of the actuator plate (109). The distal ends (D0, D1) of the first and second arms (120, 121) are coupled to each other and supported on the carrier (113). The proximal ends (P0, P1) of the first and second arms (120, 121) are hingedly secured to the actuator plate (109) so as to allow angular movement of the arms (120, 121) in a plane perpendicular to the plane of the actuator plate (109). The distal ends (D0, D1) of the first and second arm (120, 121) are coupled to each other by a connection so as to allow relative movement of there between. As can be observed from Figures 2(a)-(b), to allow movement of the first arm (120) and second arm (121) in a plane perpendicular to the plane of the actuator plate (109) and about the respective hinges (H0, H1) requires allowance of relative movement of the distal ends (D0, D1). The connection which allows relative movement between the distal ends (D0, D1) of the first and second arms (120, 121) can be implemented by any suitable means. In an embodiment, the distal end (D0) of the first arm (120) may be provided with a connecting pin (CP) and the distal end (D1) of the second arm (121) may be provided with an elongated slot (Sa) for receiving the said connecting pin (CP) thereby providing a connection between distal ends (D0, D1) which allows relative movement.

The distal ends (D0, D1) of the first and second arms (120, 121) are supported on the carrier (113) so that the movement of the distal ends (D0, D1) in an axial direction is constrained. The term ‘axial direction’ herein refers to a direction of the axis which passes through the first end (114), second end (115) and intermediate portion (116) of the carrier (113) and also passes through the first spring (S1). Therefore when the distal ends (D0, D1) of the first and second arms (120, 121) are supported on the carrier, the movement of the carrier (113) in the axial direction results in angular movements of the first and second arms (120, 121) about their respective hinges (H0, H1), in a plane perpendicular to the plane of the actuator plate (109) (i.e. towards or away from the central opening (119) of the actuator plate (109)).

To allow relative movement between the distal ends (D0, D1) of the first and second arms (120, 121), an elongated slot (SC) extending in a direction perpendicular to the axial direction, is disposed on the intermediate portion (116) of the carrier (113) which receives the connecting pin (CP) thereby providing a support for the distal ends (D0, D1) of the first and second arms (120, 121) and also the elongated slot (SC) is sized to accommodate lateral displacement of the distal ends (D0, D1) resulting from the angular movements of the first and second arms (120, 121) about the respective hinges (H0, H1).

As shown in Figures 2(a), 2(b) and 4(a), the first arm (120) is provided with a second spring (S2) disposed between the proximal end (P0) and the distal end (D0) of the first arm (120). Preferably, the second spring (S2) is disposed around the entire length of the first arm (120). The second spring (S2) is disposed so that the movement of the second arm (121) towards central opening (119) of the actuator plate (109), the distal end (D1) of the second arm (121) compresses the second spring (S2). Thus, the movement of the first arm (120) and the second arm (121) towards central opening (119) is under force of the second spring (S2).

Referring to Figures 4(a)-(e), the first arm (120) is in the form of a rigid strip (120a) and the second arm (121) is formed of two rigid strips (121a, 121b). The term ‘strip’ herein refers to an elongated plate type construction having thickness smaller than the width and width smaller than the length. The second arm (121) is formed of the two rigid strips (121a, 121b) located spaced apart so as to define a gap there between. Each of the two strips (121a, 121b) of the second arm comprises a proximal end and a distal end together/collectively forming the proximal and the distal ends (P1, D1) of the second arm (121). Each of the two strips (121a, 121b) of the second arm (121) comprises an elongated slot so that when the two strips are placed spaced apart, the elongated slots together forms the elongated slot (Sa) of the second arm (121). The distal end (D0) of the first arm (120) provided with a hole (H) for receiving the connecting pin (CP) and the distal end (D0) of the first arm (120) is received within the gap between the strips (121a, 121b) of the second arm (121) and the connecting pin (CP) is inserted through the slot (Sa) of the second arm (121) and through the hole (H) provided at the distal end (D0) of the first arm (120) thereby coupling the first arm (120) and the second arm (121).

The proximal ends (P0, P1) of the first and second arms (120, 121) are connected with respective hinges (H0, H1) for hingedly securing the same with the actuator plate (109). As shown in figure 4(b), the distal ends of the rigid strips (121a, 121b) of the second arm (121) are profiled to form a cam (122) at the distal end (D1) of the second arm (121) to define toggle point when the distal ends (D0, D1) of the first arm (120) and the second arm (121) are secured with each other. The ‘toggle point’ referred herein defines a point which changes the orientation of the first arm (120) and the second arm (121) with respect to the actuator plate (109).

Referring to Figures 2-4, the actuating force applied on the carrier (113) in the direction of arrow (as shown in Figures 2(a)-(b)) moves the carrier (113) in axial direction against the force of the first spring (S1). The movement of the carrier (113) pushes the distal ends (D0, D1) of first and second arms (120, 121) towards the actuator plate (109) (i.e. towards central opening (119) of the actuator plate(109)). Since the proximal ends of the first and second arms are secured to the actuator plate, the distal ends (D0, D1) move relative to each other against the force of the second spring (S2). The first arm (120) is provided with a pair of washers (123) each provided at both ends of the second spring (S2) so that the distal end (D1) or the cam (122) formed at the distal end (D1) of the second arm (121) does not come in direct contact with the second spring (S2). As the distal end (D1) of the second arm (121) moves towards the central opening (119) of the actuator plate (109) against the force of the second spring (S2), the cam (122) formed at the distal end (D1) of the second arm (121) rotates and compresses the spring (S2) which is coupled with washer (123) during the movement of carrier thereby achieving the toggle point. After the toggle point (as shown in figures 2(a) and 2(b)), the first and second arms (120, 121) tend to move quickly, due to the cam profile (122), away from the actuator plate (109) in the axial direction towards the first spring (S1). This movement quickly moves the actuator plate (109) to come in contact with the third and fourth terminals (as shown in 2(b)) (T30, T40). As soon as actuation force is removed, the first spring (S1) pushes the carrier (113) in axial direction away from the first spring (S1) which moves first and second arms (120, 121) towards the actuator plate (109) till the toggle point is arrived. After the toggle point (as shown in figures 2(a) and 2(b)), the first and second arms (120, 121) tend to move quickly, due to the cam (122) profile, away from the actuator plate (109) in the axial direction away from the first spring (S1). This movement quickly moves the actuator plate (109) to come in contact with the first and second terminals (T10, T20) (as shown in figures 2(a)).

Figure 2(a) shows that the switch (100) is in normal state and circuit is made between terminal 1 (T10) and terminal 2 (T20). The second spring (S2) is used in the switch (100) and entire length of the spring (S2) is guided in the strip (120a) of the first arm (120) (as shown in Figure 4(a)) hence the same defeats or reduces the chances of buckling of spring (S2) and eliminates chance of no contact zone. As shown in Figures 2(b), when the plunger (117) is pressed and circuit is made between terminal 3 (T30) and terminal 4 (T40) and the plunger/carrier movement is stopped just after toggle point which ensures positive contact pressure during formation of contact in second circuit and eliminates the chances of no contact zone. For this purpose, the housing interior (105) and the second end (115) of the carrier (113) is provided with abutting surfaces (124, 125) which cooperates with each other to acts as stopper to stop the plunger/carrier movement just after toggle point.

The actuator plate (109) may be provided with contacts points which contact with the terminals. The actuator plate (109) has a thickness to withstand to the forces which are caused by the spring during make and break of the contacts. As shown in Figure 3 (b) and (c), the actuator plate (109) of the switch of the present invention has plate type construction which does not go in to any type of deformation adding more life-cycle to the switch. The actuator plate may be made of thick solid copper conductor. As can be clearly understood, the actuator plate in the switch of the present invention is single solid conductor of more thickness which can carry more current and occupies less space. Further in terms of thickness, flexibility is not required in the actuator plate of switch of the present invention. Since the mechanism spring are used for contact pressure results in switch which is meant for more ampere switching.

Referring to Figures 2-4, the switch has discrete changeover point because compression of second spring (S2) depends on cam (122) formed at the distal ends (D1) of the two strip (121a, 121b) of the second arm (121) which sandwich the strip (120a) of the first arm (120) in between. As shown in Figure 4(b), the cam (122) is in the form of detent. When the plunger (117) is pressed downward, due to a detent or cam (122) in the second arm (121), pushes the washers (123) which covers both ends of second spring (S2) result in uniform compression of spring (S2), just after full compression of the spring (S2) changeover happens to second circuit at toggle position/point (when detent will be normal to the washer of the first arm) and hence results in discrete change over position. The construction of the switch (100) of the present invention has slot (SC) in the carrier which allows no interference/ pressure on the carrier/plunger when pressed down due to spring compression and slot (SC) on the carrier (113) gives the clearance to the connecting pin (CP) for horizontal movement when the plunger/carrier is pressed down gradually and hence result in smooth operation and less wear and tear of the parts lead to extended number of operation.

Referring to figure 4, in the switch of the present invention assembly proximal ends of the strips of the first and second arms are doweled or riveted with the holder/hinges and the distal ends of strips of the first and second arms are coupled together with the connecting pin (CP) and bush (B). The bush (B) locks ends of the connecting pin (CP) to avoid falling off the ping from the distal ends of the first and second arms. The carrier can also be made up of plastic material The bush can be made up of plastic material which is received in the slot formed in the carrier so that there is lesser friction between the bush and the carrier due to the movement of the connecting pin and the bush lateral to the axial direction. This complete assembly is riveted (RT) to the actuator plate (109) by means of riveting of holder/hinges (H0, H1) on the actuator plate (109) hence results in rigid assembly with no chance of no contact zone.

The snap-action type of the snap action type switch of the present invention can be used for various applications. Some of the applications of the snap action type switch of the present invention are, but not limited to, Brake Switch, Clutch Switch, Door Switch, Four-Wheel Drive Switch.

,CLAIMS:1. A snap-action type electrical switch, comprising:
a housing having an interior;
a pair of fixed-contact assemblies oppositely disposed in the housing, each of the fixed contact assembly comprises a pair of contact-terminals.
an actuator plate comprising a central opening and said actuator plate is moveable between the pair of fixed-contact assembly defining a first position and a second position, in the each position the actuator plate bridges the contact-terminals of the one fixed contact assembly;
an actuator assembly for moving the actuator plate between the first position and the second position; the actuator assembly comprising:
a carrier supported on a first spring disposed in the housing so that the carrier is moveable under a force of the main spring between the first position and the second position of the actuator plate;
a first arm and a second arm, each having a proximal end hingedly secured to opposing sides of the actuator plate and a distal end supported on the carrier;
a second spring is disposed between the proximal end and distal end of the first arm;
wherein the distal ends of the first arm and the second arm are secured to each other by a connection which allows relative movement there between and so that the movement of the carrier forces the first arm and the second arm against a force of the second spring towards the central opening, and the distal end of the second arm is formed to define a toggle point between the first position and the second position of the actuator plate and wherein the toggle point is defined as a point immediately after which the position of the actuator plate changes from first position to the second position or vice versa.

2. A snap-action type electrical switch as claimed in claim 1, wherein the housing is provided with guide-ways for guiding outer edges of the actuator plate.

3. A snap-action type electrical switch as claimed in claim 1, wherein the actuator plate is provided with guiding-pads at the opposing outer edges for freely guiding actuator plate within the housing.

4. A snap-action type electrical switch as claimed in claim 1, wherein the carrier comprises
a first end secured to a plunger for applying actuating force;
a second end opposite to the first end, and supported on the first spring; and
an intermediate portion between the first end and the second end, for supporting the distal ends of the first arm and the second arm.

5. A snap-action type electrical switch as claimed in claim 1, wherein the connection connecting the first arm and second arm, comprising
a connecting pin provided at the distal end of the first arm;
an elongated slot disposed at the distal end of the second arm for receiving the connecting pin thereby securing the distal ends of the first arm and the second arm; and the said slot is sized to cooperate with the connecting pin so as to allow relative movement there between the distal ends of the first and second arms.

6. A snap-action type electrical switch as claimed in claims 4 and 5, wherein the intermediate portion of the carrier is provided with an elongated slot to receive the connecting pin for supporting the distal ends of the first and second arms and the elongated slot is sized so as to accommodate lateral movement of the connecting pin resulted due to relative movement of the distal ends of the first and second arms.

7. A snap-action type electrical switch as claimed in claims 1 to 5, wherein the first arm is a rigid strip having a proximal end hingedly secured to the actuator plate and a distal end provided with a hole for receiving the connecting pin.

8. A snap-action type electrical switch as claimed in claims 1 and 7, wherein the second spring placed around the entire length of the first arm.

9. A snap-action type electrical switch as claimed in claim 1 and 7, wherein the second arm comprises two identical rigid strips located spaced apart defining a gap there between and the distal end of the first arm is placed between the said gap; and wherein each strips having a proximal end and a distal end collectively forming the proximal end and the distal end of the second arm, respectively.

10. A snap-action type electrical switch as claimed in claim 9, wherein the proximal ends of the rigid strips of the second arm are hingedly secured to the actuator plate, and each of the distal ends of the rigid srips of the second arm comprises a cam.

11. A snap-action type electrical switch as claimed in claims 1 and 9, wherein the cams provided at the distal ends of the strips of the second arm are profiled to define the toggle point during the movement of the arms towards the central opening of the actuator plate.

12. A snap-action type electrical switch as claimed in claim 1, wherein the toggle point is defines so that
movement of the carrier and the first and second arms towards the central opening from the first or second position results in no movement of the actuator plate before the toggle point is achieved and immediately after the toggle point, the actuator plate is moved to the second or first position.

13. A snap-action type electrical switch as claimed in claims 1-12, wherein the connecting pin is located and locked with the help of bush for supporting ends of connecting pin in the slot of the carrier and locking the ends of the connecting ping to avoid fall off the connecting from the distal ends of the first and second arms.
14. A snap-action type electrical switch as claimed in claims 1, wherein the actuator plate is made up of thick copper conductor.