CAM ACTUATED SWITCH MODULE AND MANUFACTURING METHOD THEREOF

Abstract

 The present invention refers to a cam actuated switch module and to its manufacturing method. The module is made up of two identical semi-modules attachable to each other, the semi-modules comprising two identical casing halves and two identical switches, respectively fitted inside the first and second casing halves. A rotatable cam is placed inside the casing and configured for selectively open and close the first and second switches upon rotation of the cam. The first and second casing halves have at least one recess, such as when they are attached to each other, the recesses define an opening, and a part of the cam is received in the opening and it is rotatable therein. One of the first fixed contact is conformed such as when the first and second casing halves are assembled to each other, its part protruding outside the casing, is in contact with the corresponding fixed contact, thus, the use of external bridges is eliminated.

Description

Object of the invention

[0001] The present invention refers in general to the construction of cam actuated switches and changeover switches.

[0002] An object of the invention is to provide a low cost cam operated switch, by reducing manufacturing costs, and simplifying manual assembly of the switch in order to reduce production times.

[0003] Another object of the invention is to provide a more efficient change over switch (commutator), that reduces power losses during stationary state, that is, when current is flowing through the switch.

[0004] A further object of the invention is to provide a switch of reduced size, and with increased endurance, that is, that it is capable of performing a large number of switching operations.

Background of the invention

[0005] It is known that cam switches typically comprise two or more pairs of fixed contacts to be connected to respective electric circuits, and movable contacts provided to act on the fixed contacts to selectively close and open the above mentioned electric circuits upon rotation of a cam. Commonly, cam switches are used as switching modules to construct a switching block, wherein an array of switching modules are stacked together about a common shaft or spindle.

[0006] The operation of the movable contacts is performed by a drive shaft rotatably engaged through the switching modules and engaged with a plurality of cams. Each of said cams is associated with a switching module in order to produce, due to the rotation motions imparted to the drive shaft, the translation of the movable contacts from a closure state in which the movable contacts are in contact with the fixed contacts, to a break state in which the movable contacts are separated from the fixed contacts.

[0007] The European patent applications EP-0.297.055A1 and EP-0.910.859 A1, are examples of conventional cam operated switches and switching blocks.

[0008] The construction of these type of switches is complex and expensive, because a large number of different components have to be produced and assembled together, usually by hand.

[0009] A widespread solution among the manufacturers to build a changeover switch or commutator, is to assemble two switches together to form a double-switch unit. To obtain a common electrical terminal, two terminals of the switches are electrically connected with a metallic plates, known as bridges, fixed by screws to the terminals.

[0010] However, the use of bridges imply several drawbacks, namely: increased electrical resistant of the terminals, which in turn increase power losses, increase in the use of raw material for the construction of the switch, and enlarged size of the same. Additionally, the interface areas between the bridge and the terminals to which it is screwed, are hot spots which significantly increase power (heat) losses.

[0011] It is known that society today has a greater demand of more efficient and environment-friendly products. Furthermore, the society today has a greater dependence on electrical supplies and there is a growing demand for continuous and uninterrupted use of the systems electrical, continuous process industry, hospitals, data centers, etc.

[0012] It has been detected the need in this technical field, for more efficient switches, with reduced power losses and more sustainable, especially in the range of medium intensities 63 A - 125 A.

Summary of the invention

[0013] The present invention is defined in the attached independent claims, and it refers to a switch module made up of two identical semi-modules attachable to each other, wherein each semi-module comprises two identical casing halves and two identical switches fitted inside the respective case. Therefore, the invention is a double-switch that can be used as a change-over switch, when two terminals of the two switches are connected to form a common terminal.

[0014] Since the two semi-modules are identical, the number of different components to be produced for the manufacture of the switch is reduced, thus, the manufacturing cost is significantly reduced compared with traditional switches. The provision of different tooling, like molds and stamping dies for the manufacture of the switch, is reduced significantly.

[0015] Additionally, the invention provides that two terminals of the two switches are conformed to be directly in contact, forming a common terminal of the overall switch module. In this way, the use of external bridges and connection screws is eliminated.

[0016] The elimination of bridges achieves the object of minimizing the use of raw materials (mainly copper), reducing heat losses which in turn increase energy efficiency (the dissipated power is directly proportional to the electrical resistance). In this way, the invention minimizes energy losses produced by heating in the connections with screws of the bridges due to the known "Joule Effect", obtaining thereby a more efficient product in its use and with less environmental impact throughout its life cycle. Due to the elimination of bridges, the size of the switch module is also reduced.

[0017] More in detail, an aspect of the invention refers to a cam actuated switch module comprising a casing obtained from a moldable and electrically insulating material, and made up of first and second casing halves attachable to each other. The switch module additionally comprises first and second switches respectively fitted inside the first and second casing halves. A rotatable cam is placed inside the casing and retained by (or assembled between) the two casing halves, and configured for selectively actuate (open and close) the first and second switches upon rotation of the cam.

[0018] The first and second casing halves are substantially identical to each other, that is, they are of identical construction in that they have been molded with the same mold. Therefore, first and second casing halves are a copy of each other, and have the same shape and dimensions.

[0019] Casing halves with small differences caused by normal imperfections of the manufacturing molding process, or minor changes added after the molding like: perforations, cut-out parts etc, have to be regarded as entirely equivalent to the term identical, for the assessment of the scope of protection defined in the attached claims.

[0020] Moreover, each of the first and second casing halves has a bottom base and side walls projecting from the bottom base forming together a chamber inside which the respective first and second switch is fitted. The free edges of the side walls forms a perimetric edge having interlocking means, which are configured to engage with the interlocking means of other casing halve, when the first and second casing halves are brought together during the assembly of the switch.

[0021] The interlocking means are configured such as the first and second casing halves can be attached together only in one relative position between casing halves. This facilitates the manual assembly of the switch module, since the assembly process is very intuitive in that the correct position of the casing halves for their assembly, is given by the design of the casing halves and interlocking means.

[0022] The invention also refers to a switch block formed by an array of the above-defined switching modules, stacked together about a common shaft or spindle passing through the modules for rotating the cams.

[0023] Another aspect of the invention, refers to a method for manufacturing the cam actuated switch module previously defined. The method comprises the steps of manufacturing two or more semi-module switches and at least one cam (2), wherein each semi-module switch comprises a casing halve and a switch made up of first and second fixed contacts and a movable contact. The method further comprises the step of assembling together two of the semi-modules switches and one cam to form a switch module, and in such a manner that the cam is placed between the two semi-module switches and it is rotatable while being retained by the semi-modules switches.

[0024] The casing halves are produced by injection-molding a plastic material from the same mold. The first fixed contact is obtained by press-stamping a plate with the same stamping die, and similarly the second fixed contact is obtained by press-stamping a plate with the same stamping die (different than the previously mentioned stamping die). After stamping, the second fixed contact is bended in such a manner that when two semi-modules are assembled together, the second fixed contacts of each semi-module get in contact with each other.

[0025] Some of the advantages of the invention are summarized below:

• reduction up to 50 % of power losses by eliminating the need of interconnecting bridges at the common terminal;
• reduction of the working temperature, so that by avoiding excessive heating of the components, potential breakdowns derived from it are reduced;
• enhanced electrical endurance of the equipment by 60%, reaching a lifespan up to 6000 maneuvers under load;
• reduced size of the equipment, the change in size of the set will allow a smaller installation infrastructure allowing greater space optimization.

Brief description of the drawings

[0026] Preferred embodiments of the invention are henceforth described with reference to the accompanying drawings, wherein:

Figure 1.- shows a perspective view of a preferred embodiment of the switch module of the invention, with the two semi-modules spaced apart.

Figure 2.- shows in drawing (A) a partially cut-away perspective view of a semi-nodule; in drawing (B) a perspective view of one of the switches.

Figure 3.- shows a perspective view of the two witches in an operative arrangement together with the cam.

Figure 4.- shows several side elevational views of the switches assemblies in different positions of the cam, such as the arrows indicate current circulation. In drawing (A) the top switch is closed and the bottom switch is open; in drawing (B) the top switch is open and the bottom switch is closed; and in drawing (C) both switches are open. It is clear for a skilled person in the art, that by varying the shape of the cam, different sequences of switching operations can be obtained.

Figure 5.- shows in drawing (A) a perspective view of the switch module with the two semi-modules assembled; drawing (B) is a top plan view of the assembled module; and drawing (C) is a side elevational view of the assembled module.

Figure 6.- shows in drawings (A,B) two different perspective views respectively of the first and second semi-modules.

Figure 7.- shows several perspective views of the switch module including nut holders, wherein in drawing (A) one nut and holder are shown unassembled, in drawing (B) the nut and holder are assembled and positioned for to their coupling with the fixed contact, and in drawing (C) the nut holder is coupled with a respective fixed contacts.

Figure 8.- shows a perspective view of a switch block.

Preferred embodiment of the invention

[0027] As shown for example in figure 1, the switch module (1) of the invention is made up of two identical semi-modules (1a,1b) attached to each other, and a rotatable cam (2) retained by the two semi-modules (1a, 1b) when they are assembled together.

[0028] Each of the first and second semi-modules (1a, 1b) comprises two identical casing halves (3a,3b), and two identical switches (4a,4b) respectively fitted inside the casing halves (3a,3b). The casing halves (3a,3b) are made of a moldable and electrically insulating material, molded in the same mold, thus, they are of identical construction .

[0029] First and second casing halves (3a,3b) have two semi-circular cut-outs (9), such as when the two halves are assembled, the cut-outs define a circular opening (15), and a cylindrical part of the cam (2) is received within the opening (15) and it is rotatable and guided within the opening (15).

[0030] As shown in figure 1, each of the casing halves (3a,3b) has a bottom base (5a), and four side walls (25a,25a'26a,26a'), (25b,25b',26b,26b'), projecting from the bottom base (5a) forming together a chamber, inside which the respective switch (4a,4b) is fitted. The bottom base (5a,5b) is preferably rectangular, and each of the casing halves (3a,3b) has two opposing short side walls (26a,26a'), (26b,26b') and two opposing large side walls (25a,25a'),(25b,25b'). The semi-circular cut-outs (9) and the opening (15) are formed in the two opposing large side walls.

[0031] As shown more clearly in figure 6, each casing halve (3a,3b) has an extension (7a,7b) and a recess (8a,8b) configured to receive that extension (7a,7b), such as when two casing halves (3a,3b) are brought together for their assembly, the extension (7a,7b) of one casing halve (3a,3b) fits inside the recess (8a,8b) of the other casing halve. Since the two casing halves (3a,3b) are identical, it is assured that the first and second casing halves (3a,3b) can be attached together only in one relative position between them. For example, the two semi-modules (1a,1b) can only be assembled in their relative position shown in figure 1, such as the extension (7a) would fit inside recess (8b), and extension (7b) would fit inside extension (8a).

[0032] The extension (7a) is formed at one corner of the casing halves (3a,3b), as an enlargement of two consecutive side walls.

[0033] In this way, a human operator working in the assembly line, do not need to consider what is the right relative position between the casing halves (3a,3b), because the correct position is given by the own design of the casings halves.

[0034] The free edges of the walls forms a perimetric edge of the casing halves (3a,3b),and this edge is configured to have interlocking means (6). These interlocking means (6) are configured to engage with the interlocking means of other casing halve, when the first and second casing halves are assembled together.

[0035] The interlocking means are more clearly represented in figure 6, and comprise hooks (18a,18b) and windows (19a19b) in such a way that when two semi-modules (1a,1b) are brought together during the assembly of the switch, the hooks (18a,18b) are received (by snap-fitting) inside corresponding windows (19a19b).

[0036] The switches are shown in more detail in figures 2 - 4, wherein it can be noted that first and second switches (4a,4b) are identical to each other, that is, they are constructed with identical components. More specifically, each of the switches (4a,4b) has first and second fixed contacts (10a,11a, 10b,11b) and a movable contact (12a,12b) displaceable between a closed position and an open position of the respective switch (4a,4b). The movable contacts (12a,12b) are mounted on pins (14a, 14b), and are biased by means of springs (13a, 13b) towards the fixed contacts (10a,11a, 10b,11b).

[0037] As it can be appreciated more clearly in figure 2 (A), the fixed contacts (10a,11a, 10b,11b) consist of metallic plates having two ends, wherein one end of the fixed contacts protrude outside the respective casing halve (1a, 1b), for their connection to an external circuit. The other end of the fixed contacts are housed within the respective casing halve, and are positioned for the connection of the moveable contacts (12a,12b).

[0038] First contacts (11a,11b) of each switch (4a,4b), are identical pieces, that have been obtained by the same stamping die. Similarly, the second fixed contacts (10a,10b) of each switch (4a,4b) are also identical, but there are mounted in an inverted or flipped positions, that is, each second fixed contact is placed upside-down relative to the position of the other second fixed contact.

[0039] As per the first fixed contacts (11a,11b), these are obtained from a bended metallic plate with two folds, so that the fixed contacts (11a,11b) have double L-shaped configuration (in a side view like the one of figure 4). Additionally, the first fixed contacts (11a,11b) are conformed such as when the first and second casing halves (1a,1b) are assembled together, the part of the contacts (11a,11b) protruding outside the casing (3) are overlapped and in contact, in order to avoid the use of bridges.

[0040] By selecting a shape for cam (2), this would selectively actuate (open and close) the first and second switches (4a,4b) upon rotation of the cam (2), by contacting with pins (14a,14b) on which the moving contacts (12a,12b) are mounted.

[0041] Turning again to the second fixed contacts (10a,10b), these consist of a flat metallic plate, configured such as their two ends are offset or out-of-line. Since the relative position of the two second fixed contacts (10a,10b) is inverted, as explained above, the protruding parts of these contacts do not overlap, as it shown more clearly in figure 5 (C). This has the advantage, that when several modules (1) are stacked to construct a switch block as the one shown in figure 6, it is easier to get access to each of the second fixed contacts (10a,10b) to connect a cable by means of a screw.

[0042] Also in figure 5 (C), it can be appreciated that the module (1) has a thin profile and a reduced volume.

[0043] In a preferred embodiment of figure 7, the switch module (1) incorporates nut holders (20) coupled with each of the fixed contacts (10a,10b) and one nut holder (20) for the common contact formed by the overlapping contacts (11a,11b). The nut holders (20) server to retain a nut (21) in a fixed positon right on holes (25) of each fixed contact, in order to make easier to connect a cable by means of a screw to the fixed contacts.

[0044] Each nut holder (20) is made of an isolating material and includes a chamber configured to receive inside a nut (21), and two lateral guides (23a,23b) such as a fixed contact (10a) fits between the two guides (23a,23b), and pegs (22) configured to engage with the casing (1) as shown in drawing 7(C), and in such a way that when the nut holder (20) is properly coupled with a fixed contact, the passing-though opening of the nut is co-axial with the hole (25) of the fixed contact.

[0045] Figure 8 shows a switch block (16) comprising an array of two or more switch modules (1) as the one previously defined. The switching modules (1) are stacked together, and the block (16) includes an actuation mechanism (17) for operating the switch modules (1), for example by means of a spindle (not shown) passing through the modules for rotating the cams.

[0046] Other preferred embodiments of the present invention are described in the appended dependent claims and the multiple combinations of those claims.

Claims

1. A cam actuated switch module (1) comprising:

a casing (3) made up of first and second casing halves (3a,3b) attachable to each other,

first and second switches (4a,4b) respectively fitted inside the first and second casing halves (3a,3b),

a rotatable cam (2) placed inside the casing (3) and configured for selectively actuate the first and second switches (4a,4b) upon rotation of the cam (2),

characterized in that

the first and second casing halves (3a,3b) are identical to each other, and

wherein the cam (2) is assembled between the first and second casing halves (3a,3b).

2. A switch module according to claim 1 wherein the first and second casing halves (3a,3b) have at least one cut-out (9), such as when they are attached to each other, the cut-outs (9) define an opening (15), and wherein part of the cam (2) is received within the opening (15) and it is rotatable guided by the opening (15).

3. A switch module according to claim 1 or 2 wherein each of the first and second casing halves (3a,3b), has a bottom base (5a) and side walls projecting from the bottom base, forming together a chamber inside which the respective first and second switch (4a,4b) is fitted, and wherein the side walls forms a perimetric edge having interlocking means (6), wherein the interlocking means (6) are configured to engage with the interlocking means of other casing halve when the first and second casing halves (3a,3b) are assembled together.

4. A switch module according to claim 3 wherein the bottom base (5a) is rectangular and each of the casing halves (3a,3b) has two opposing short side walls, and two opposing large side walls, and wherein at least one of the side walls of one casing halve, has an extension (7a,7b) and another side wall of the same casing halve has a recess (8a,8b) configured to receive that extension (7a,7b), such as when two casing halves (3a,3b) are brought together during the assembly of the switch, the extension of one casing halve fits inside the recess of the other casing halve.

5. A switch module according to claim 4 wherein the extension (7a,7b) and the recess (8a,8b) are configured such as the first and second casing halves (3a,3b), can be attached together only in one relative position between them.

6. A switch module according to any of the preceding claims, wherein the first and second switches (4a,4b) are identical to each other.

7. A switch module according to any of the preceding claims, wherein each of the first and second switches (4a,4b) has first and second fixed contacts and a movable contact (12a,12b) displaceable between a closed position and an open position of the switches, and wherein the movable contact (12a,12b) is biased by means of an elastic element (13a,13b) towards the fixed contacts, and wherein the first and second fixed contacts protrudes outside the casing (3).

8. A switch module according to claim 5 wherein one of the first fixed contact has a part protruding outside the casing, and wherein the first fixed contact is conformed such as when the first and second casing halves (3a,3b) are attached to each other, its part protruding outside the casing halve, is in contact with the corresponding fixed contact.

9. A switch module according to claim 6 wherein the first fixed contact is a folded metallic plate comprising an L-shaped part.

10. A switch module according to any of the claims 3 to 8, wherein the interlocking means comprises hooks and windows, in such a way that when two casing halves (3a,3b) are brought together during the assembly of the switch, the hooks are received inside corresponding windows.

11. A switch module according to any of the claims 6 to 9, wherein the second fixed contact is a substantially flat metallic plate having two ends, and wherein these two ends are offset.

12. A switch module according to any of the preceding claims, further comprising at least one nut holder (20) coupled with one fixed contact (10a,10b,11a,11b) and with the casing (3), and wherein a nut (21) is received within the holder (20).

13. A switch block (16) comprising an array of two or more switch modules (1) as the one defined in any of the previous claims, wherein the switching modules (1) are stacked together, and the block (16) further comprises an actuation mechanism (17) for operating the switch modules (1).

14. Method for manufacturing the cam actuated switch module (1) defined in any of the claims 1 to 12, the method comprising the steps of manufacturing two or more semi-module switches (1a,1b) and at least one cam (2), wherein each semi-module switch (1a,1b) comprises a casing halve (3a,3b) and a switch made up of first and second fixed contacts (10a,10b,11a,11b) and a movable contact (12a), wherein the method further comprises the step of assembling together two of the semi-modules switches (1a,1b) and one cam (2) to form a switch module (1), and in such a manner that the cam (2) is placed between the two semi-module switches (1a,1b) and it is rotatable while being guided by the two semi-modules switches (1a,1b).

15. Method according to claim 14 further comprising the step of producing a two or more casing halves (3a,3b) by injection-molding a plastic material from the same mold, and producing two or more first fixed contacts by press-stamping with the same first stamping die, and producing two or more second fixed contacts by press-stamping with the same second stamping die, and additionally bending the second fixed contact such as when two semi-modules (1a, 1b) are assembled together, the second fixed contacts of each semi-module get in contact with each other.

Drawing