EP3166123A1 - Electrical switch - Google Patents

Abstract

The present invention relates to an electrical switch (10) comprising: a hollow cylindrical housing (11) delimiting a cavity (12), an actuator (16) slidable within said cavity (12) along an axial direction (X) defined by the housing (11), said actuator (16) comprising at least one upper portion (16j) disposed at least partially outside the housing (11) and at least one lower portion (16i) disposed within said cavity (12), a contact block (25) able to move under the action of said actuator (16) along said axial direction (X) between two specific positions, namely an upstream contact position and a downstream contact position, said contact block (25) having at least two conductive regions (25i, 25j), respectively an upstream conductive zone (25j) and a downstream conductive zone (25i), disposed at both ends of an oblong opening (26) formed at the inside said contact block (25), said ends being positioned offset in said axial direction (X), a pair of electrical contacts (21, 22), respectively an upstream electrical contact (21) and a downstream electrical contact (22), opening into said oblong opening (26), wherein said upstream (25j), respectively downstream (25i) and upstream (21) respectively downstream electrical contact (22) are electrically connected in the upstream or downstream contact position respectively of said contact block (25); ), thereby closing a first electrical circuit, respectively a second electrical circuit.

Description

Technical area

The present invention relates to an electrical switch comprising an actuator movable axially inside the switch housing.

State of the art

There is currently a relatively wide range of sensors that can be used in automated process control facilities. One of the possible sensors consists of an electrical switch actuated by a push button and positioned to detect a limit state of a given device. One of the possible applications may for example consist in detecting the opening and closing of an electromagnetic brake. This is done by placing an electrical switch so that it is operated in the middle of the air gap of the electromagnetic brake. When the brake closes, the air gap also closes, thus activating the switch. When the brake is opened, the switch is actuated when the opening of the air gap is beyond the point of release of the switch. The electrical switches used in this type of application, generally operate on the principle of a snap closure in which the push button, by pressing a spring, changes the position of a movable electrical contact. These snap action switches, however, are characterized by a differential movement of the spring, which generates a hysteresis phenomenon. Indeed, when the device returns to its original state, the push button of the snap action switch releases its pressure on the spring, which changes the position of the movable electrical contact. But, due to the differential movement of the spring during this release phase, closing or opening of the first and second electrical circuits does not occur for the same limit states as during the compression phase of the spring. This results in a lack of reliability of this type of electrical switches that do not accurately detect the variation of a small air gap.

In addition, brake manufacturers have an interest in controlling brake wear, which results in an increase in the air gap. This control requires the use of a second switch in sudden action.

The present invention therefore aims to provide an electrical switch does not have the drawbacks of snap action electrical switches and allowing by means of a single switch to monitor both the opening of the air gap and brake wear.

Disclosure of the invention

• un boîtier cylindrique creux délimitant une cavité,
• un actionneur disposé au moins partiellement dans ladite cavité de manière à pouvoir coulisser à l'intérieur de ladite cavité le long d'une direction axiale définie par le boîtier,
• un bloc de contact apte à se déplacer sous l'action dudit actionneur le long de ladite direction axiale entre deux positions spécifiques, à savoir une position de contact amont et une position de contact aval, ledit bloc de contact comportant au moins deux zones conductrices, respectivement une zone conductrice amont et une zone conductrice aval, disposées aux deux extrémités d'une ouverture oblongue formée à l'intérieur dudit bloc de contact, lesdites extrémités étant positionnées de manière décalée selon ladite direction axiale,
• une paire de contacts électriques, respectivement un contact électrique amont et un contact électrique aval, débouchant dans ladite ouverture oblongue,

dans lequel ladite zone conductrice amont, respectivement aval, et ledit contact électrique amont, respectivement aval, sont reliés électriquement dans la position de contact amont, respectivement aval, dudit bloc de contact, fermant ainsi un premier circuit électrique, respectivement un second circuit électrique.For this purpose, according to the invention, there is provided an electrical switch comprising:

• a hollow cylindrical housing delimiting a cavity,
• an actuator disposed at least partially in said cavity so as to be able to slide inside said cavity along an axial direction defined by the housing,
• a contact block able to move under the action of said actuator along said axial direction between two specific positions, namely an upstream contact position and a downstream contact position, said contact block comprising at least two conductive zones, respectively an upstream conductive zone and a downstream conductive zone, disposed at both ends of an oblong opening formed inside said contact block, said ends being positioned offset in said axial direction,
• a pair of electrical contacts, respectively an upstream electrical contact and a downstream electrical contact, opening into said oblong opening,

wherein said upstream, respectively downstream, conductive zone and said upstream, respectively downstream electrical contact, are electrically connected in the upstream contact position respectively downstream of said contact block, thereby closing a first electrical circuit, respectively a second electrical circuit.

Other advantageous configurations of the present invention are defined in dependent claims 2 to 15.

Thus configured, the electrical switch of the present invention will have many advantages over abrupt electric switches. First, it will be easily achievable because of its low structural complexity. This will result in a low manufacturing cost. Secondly, unlike snap action switches, it will not produce the aforementioned hysteresis phenomenon. Precise detections will therefore be possible due to the absence of this hysteresis phenomenon. Thirdly, the opening or closing of the electrical circuits will occur systematically for the same values of external thrust exerted on the actuator. Fourth, it can easily adapt to the needs of users because of the use of a single contact block bringing together the pair of movable electrical contacts. Thus, by changing the spacing between these movable electrical contacts, that is to say the axial width of the oblong opening formed inside said contact block, it will be possible to change the stroke to move from the position opening the first electrical circuit to the closed position.

Brief description of the drawings

• la figure 1 est une vue en perspective partiellement arrachée d'un interrupteur selon l'invention ;
• la figure 2 est une vue en coupe axiale de l'interrupteur représenté sur la figure 1, dans une première position d'utilisation de l'interrupteur, le premier circuit électrique étant ouvert et le second circuit électrique étant fermé;
• la figure 3 est une vue similaire à la figure 2, mais dans une deuxième position d'utilisation de l'interrupteur, le premier circuit électrique étant fermé et le second circuit électrique étant ouvert;
• la figure 4 est une vue en coupe suivant la ligne A-A de la figure 2.

Other features and advantages of the present invention will be better understood on reading a particular embodiment of the invention and with reference to the drawings in which:

• the figure 1 is a partially cutaway perspective view of a switch according to the invention;
• the figure 2 is an axial sectional view of the switch shown on the figure 1 in a first use position of the switch, the first electrical circuit being open and the second electrical circuit being closed;
• the figure 3 is a view similar to the figure 2 but in a second position of use of the switch, the first electric circuit being closed and the second electric circuit being open;
• the figure 4 is a sectional view along line AA of the figure 2 .

Detailed description of an embodiment of the invention

With reference to Figures 1 to 4 , there is shown an electrical switch according to the invention. This electrical switch 10 is formed of a hollow cylindrical casing 11 open at its lower ends 11 i and upper 11 j and delimiting an internal cavity 12 of circular section. According to other exemplary embodiments, the cavity 12 may obviously have a rectangular cross section or any other suitable form.

In the present description, unless otherwise specified, an axial direction is a direction parallel to the main axis X of the cavity. In addition, a radial direction is a direction perpendicular to the main axis X of the cavity and intersecting this axis. Unless stated otherwise, the adjectives and adverbs axial, radial, axially and radially are used with reference to the aforementioned axial and radial directions. In the same way, an axial plane is a plane containing the main axis X of the cavity and a radial plane is a plane perpendicular to this axis. Similarly, an axial section is a section along an axial plane, and a radial section is a section along a radial plane.

Furthermore, unless otherwise stated, the upper and lower adjectives are used with reference to the X-axis as shown in the figures 2 and 3 . Thus, the X axis is directed from the upper end of the housing towards its lower end.

Finally, the upstream and downstream terms are defined with respect to the direction of the X axis, which corresponds to the direction of movement, within the cavity, of the actuator which will be defined in the rest of this presentation.

The outer periphery of the housing 11 is advantageously provided with a thread 13 over almost its entire length so as to facilitate its attachment to a support structure by screwing. Inside the cavity 12 has been inserted a plastic sleeve 14 of substantially tubular shape. Bushing 14 defines an inner housing 15 within which an actuator 16 is slidably received. As shown in FIG. figure 3 , this inner housing 15 is delimited, on the one hand, by an upper annular shoulder 18 which limits the movement of the actuator 16 in the upstream direction, and, on the other hand, by a cap 19 attached to the lower end of the sleeve 14, said cap 19 limiting the movement of the actuator 16 in the downstream direction. As shown on the figure 2 the actuator 16 is in the form of two parts, namely an upper part 16j, protruding from the housing 11 at its upper end 11j, and a lower part 16i which slides inside the inner housing 15 of the sleeve 14. The upper part 16j of the actuator 16 is completely covered by an elastic membrane 17 whose edges are clamped between the upper end 11j of the housing 11 and the upper annular shoulder 18 of the sleeve 14, said membrane 17 thus preventing any infiltration of dust or liquid inside the housing 11.

The actuator 16 is configured to modify the operating state of the switch 10 as a function of the axial thrust exerted on the upper part 16j of said actuator. Indeed, depending on the intensity of this axial thrust, the actuator 16 can move downstream or upstream, thereby triggering the opening or closing of electrical circuits. These electrical circuits are formed in particular by fixed electrical contacts and by movable electrical contacts intended to come into contact with said fixed electrical contacts when the actuator 16 is in a so-called opening position and to no longer be in contact with said contacts. when the actuator is in a so-called closing position.

In the variant embodiment shown on the Figures 1 to 4 the electrical switch 10 comprises two fixed electrical contacts, namely an upstream fixed electrical contact 21 and a fixed downstream electrical contact 22, which are arranged in a manner offset in the axial direction inside the housing 11. Advantageously, these fixed electrical contacts 21, 22 are installed in the thickness of the sleeve 14 and are each in the form of a rod L-shaped metal of which one of the segments 21r or 22r extends radially and the other segment 21a or 22a extends axially. For this purpose, the sleeve 14 comprises several radial channels 23r and axial 23a, formed in its thickness, said channels being intended to accommodate at least partially said radial segments 21 r, 22r and axial 21a, 22a of the electrical contacts 21, 22. The radial segments 21 r, 22r of the electrical contacts 21, 22 open into a central recess 24 of the actuator 16 in two axially offset positions, the radial segment 21r of the upstream fixed electrical contact 21 being positioned upstream of the radial segment 22r of the contact fixed downstream electric 22.

Furthermore, the electrical switch 10 also comprises two movable electrical contacts, namely an upstream movable electrical contact and a downstream movable electrical contact, which are arranged in an offset manner in the axial direction inside the housing 11. In the variant illustrated, the downstream and upstream mobile electrical contacts are united within a same contact block 25 slidably housed inside the central recess 24 of the actuator 16 and are respectively in the form of conductive zones upstream 25j and downstream 25i disposed at the axial ends of an oblong opening 26 formed inside said contact block 25. The contact block 25 is arranged in such a way that the radial segments 21 r, 22r of the electrical contacts 21, 22 open into said oblong opening 26, the upstream conductive zone 25j being positioned upstream of the radial segment 21r and the conductive zone downstream 25i being positioned downstream of the radial segment 22r. Advantageously, the contact block 25 will consist entirely of a conductive material. In the variant shown, the contact block 25 is in the form of a parallelepiped block having two opposite side faces 25a, 25b which are perpendicular to the radial segments 21r, 22r of the fixed electrical contacts 21, 22. The oblong opening 26 passes through each of said lateral faces 25a, 25b of so that each of the fixed electrical contacts 21, 22 can lead into the oblong opening 26 from a different side face. The contact block 25 slides inside the central recess 24 under the combined actions of an upstream spring 27 and a downstream spring 28. The upstream spring 27 bears at its lower end on the upper face of the block contact 25 and at its upper end on an upper stop element 29j integral with the actuator 16. In the variant shown, this upper stop element 29j is constituted by the bottom of the central recess 24. Thus configured, the thrust external axial exerted on the actuator 16 tends to move the contact block 25 through the upstream spring 27 to an upstream contact position, wherein the upstream conductive zone 25j is in contact with the upstream fixed electrical contact 21. In increasing the external axial thrust on the actuator 16 from this upstream contact position, the contact block 25 will remain stationary on the fixed contact 21 under the effect of the spring 27, while the actuator 16 will produce an additional race. The downstream spring 28 is supported at its upper end on the lower face of the contact block 25 and at its lower end on a lower abutment member 29i integral with the bushing 14, and therefore the housing 11. In the variant shown, this element lower stop 29i is constituted by an inner face of the cap 19, which is recessed in the middle so as to receive said lower end. Thus configured, the downstream spring 28 exerts an axial thrust on the assembly formed by the actuator 16 and the contact block 25 so that it tends to move this assembly to a downstream contact position, in which the conductive zone downstream 25i is in contact with the downstream fixed electrical contact 22. Advantageously, this assembly will be completely formed of conductive metal. In the variant shown, the stiffness of the upstream and downstream springs 27, 28 have been chosen so that the contact block 25 is in its downstream contact position when the actuator 16 is not subjected to any external axial thrust, as illustrated on the figure 2 . Moreover, the stiffness of the upstream spring 27 will advantageously be greater than the stiffness of the downstream spring 28 so as to prevent, during the passage from the downstream contact position to the upstream contact position, the upstream spring 27 is previously compressed before the contact block 25 starts moving. This prior compression could in fact delay the opening of the electrical circuit which includes the downstream electrical contact 22, which would not immediately detect an external axial thrust exerted on the actuator. Furthermore, the stiffness of the upstream and downstream springs 27, 28 will advantageously be chosen so that the upstream spring 27 begins its compression when the contact block 25 is in its upstream contact position, as illustrated in FIG. figure 3 , and that the actuator 16 is subjected to an additional external axial thrust. Thus, an additional displacement of the actuator 16 in the downstream direction from the position represented on the figure 3 it will not generate an additional displacement of the contact block 25 in the downstream direction, but simply a compression of the upstream spring 27, thus avoiding a deterioration of the upstream fixed electrical contact 21.

The embodiment variant represented on the Figures 1 to 4 is obviously not limiting for the invention. It is only one of the possibilities of realizing the invention. However, it differs from other possibilities in the choice to use two perfectly separate subassemblies, namely a first subassembly formed by the housing only, and a second subassembly formed by the plastic bushing in which were arranged the actuator, the movable contact block, the pair of fixed electrical contacts and the upstream and downstream springs. Thus configured, the assembly and disassembly of the electrical switch will be easily executable by simply inserting the second subset within the first subset. The user can easily change the electrical switch by changing only the second subset without changing the first subset.

Claims (15)

An electric switch (10) comprising: a hollow cylindrical housing (11) delimiting a cavity (12), an actuator (16) slidable within said cavity (12) along an axial direction (X) defined by the housing (11), said actuator (16) comprising at least one upper portion (16j) disposed at least partially outside the housing (11) and at least one lower portion (16i) disposed within said cavity (12), a contact block (25) able to move under the action of said actuator (16) along said axial direction (X) between two specific positions, namely an upstream contact position and a downstream contact position, said contact block (25) having at least two conductive regions (25i, 25j), respectively an upstream conductive zone (25j) and a downstream conductive zone (25i), disposed at both ends of an oblong opening (26) formed at the inside said contact block (25), said ends being positioned offset in said axial direction (X), a pair of electrical contacts (21, 22), respectively an upstream electrical contact (21) and a downstream electrical contact (22), opening into said oblong opening (26), wherein said upstream (25j), respectively downstream (25i) and upstream (21) respectively upstream electrical contact (22) are electrically connected in the upstream or downstream contact position respectively of said contact block (25); ), thereby closing a first electrical circuit, respectively a second electrical circuit. An electric switch (10) according to claim 1, wherein said actuator (16) has a central recess (24) within which the contact block (25) is slidably housed. An electric switch (10) according to claim 2, wherein the contact block (25) slides within said central recess (24) under the combined actions of an upstream spring (27) and a downstream spring (28). ), said upstream spring (27) being configured to move the contact block (25) to its upstream contact position and said downstream spring (28) being configured to move the contact block (25) to its downstream contact position. An electric switch (10) according to claim 3, wherein the stiffness of the upstream spring (27) is greater than the stiffness of the downstream spring (28). Electrical switch (10) according to one of claims 3 and 4, wherein the upstream spring (27) bears at its upper end on an upper stop element (29j) integral with the actuator (16) and at its end lower on an upper face of the contact block (25). An electric switch (10) according to claim 5, wherein the upper stop member (29j) is an inner face of the actuator (16) which defines the bottom of the central recess (24). Electrical switch (10) according to one of claims 3 to 6, wherein the downstream spring (28) bears at its lower end on a lower abutment member (29i) integral with the housing (11) and at its upper end on a lower face of the contact block (25). An electric switch (10) according to claim 7, wherein the lower stop member (29i) is constituted by an inner face of a cap (19) attached to the lower end of a plastic sleeve (14) of a shape substantially tubular, inserted inside the housing (11), said cap (19) being recessed in its middle to receive the lower end of the downstream spring (28). An electric switch (10) as claimed in any one of the preceding claims, wherein the contact block (25) is formed entirely of metal. An electric switch (10) according to claim 9 when dependent on one of claims 7 and 8, wherein the downstream spring (28) and the lower stop member (29i) are formed entirely of metal. An electric switch (10) according to any one of the preceding claims, wherein the contact block (25) is in its downstream contact position when the actuator (16) is not subjected to any axial external force. An electrical switch (10) according to any one of the preceding claims, wherein each of the electrical contacts (21, 22) is in the form of an L-shaped metal rod having at least a first segment (21 r, 22r ) extending perpendicular to the axial direction (X) defined by the housing (11) and at least one second segment (21a, 22a) extending parallel to said axial direction (X). An electric switch (10) according to claim 12 when dependent on claim 8, wherein the plastic sleeve (14) has one or more channels (23a, 23r) formed in its thickness, said channels (23a, 23r) being intended at least partially housing said first and / or second segments (21a, 22a, 21r, 22r) of said metal rods. An electric switch (10) according to any one of the preceding claims, wherein an elastic membrane (17) completely covers the upper portion (16j) of the actuator (16), thereby preventing the infiltration of dust or liquid into the inside the housing (11). Electrical switch (10) according to any one of the preceding claims, wherein the housing (11) has at its periphery at least one threaded zone (13).

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