Electrical switch

Abstract

The object of the present invention is an electrical switch (20) comprising: a base (22); an actuation lever (24) comprising a lateral wall (94) guided in a hole (80) of said base (22); a return spring (28) of said lever (24) which moves with respect to said base (22) and comprises a last elastic turn (122) which, during the actuation stroke of said lever (24), abuts against an abutment surface (84) of said base (22) and cooperates with a slope formed in said lateral wall (94), said slope causing a radial deformation of said elastic ring, characterized in that said hole (80) has a series of axial ribs (52) which project into said hole (80), each of said axial ribs being slidably housed in a complementary axial slot (116) formed in said lateral wall (94), and in that a radially upper end face (84) of each axial rib (82) forms part of the fixed abutment surface (84).

Description

TECHNICAL FIELD

[0001] The present invention relates to an electrical switch of long life and high reliability, which provides an excellent tactile sensation when operated in the axial direction.

[0002] The present invention relates more precisely to an electrical switch in which the tactile sensation is generated by the cooperation of an elastically deformable ring (and for example the free end turn of a compression coil spring) with the slope of the upper actuation stem, said slope being deformed radially by the elastic ring during the actuation stroke of the switch. BACKGROUND

[0003] Document - FRA1 - 2420834 proposes a design of an electrical switch with tactile effect and axial actuation, also called an electrical switch, comprising:

[0004] - a lower base or housing 6;

[0005] - an upper actuation stem or push button 1 comprising a section 18 of its cylindrical lateral wall axially guided in a manner sliding in a guide hole formed in the lower base;

[0006] - an elastic member 4 for returning the upper actuation stem to the high rest position,

[0007] the switch, under the effect of an actuation force applied to the upper actuation stem and against the force exerted by the elastic return member, the upper actuation stem 1 moves axially along the actuation stroke relative to the lower base 6 to a mobile lower position for changing the state of at least one electrical switching mode,

[0008] and comprising an elastic ring 17:

[0009] - which is arranged in a peripheral housing formed in said lateral wall;

[0010] - which is axially crossed by said section of the upper actuation stem;

[0011] - which bears axially downwards during the actuation stroke of the upper actuation stem 1 against a fixed stop face 18 belonging to the lower base 6;

[0012] - and which cooperates during the actuation stroke of the upper actuation stem 1 with a cam profile 20 formed in said lateral wall, said cam profile deforming radially said elastic ring to generate an elastic resistance to the actuation of the upper actuation stem.

[0013] The aim of this design is to solve the problem of the user's uncertainty about the authenticity of the implementation of the function controlled by the member of the switch acting on the upper actuation stem.

[0014] This is achieved by the tactile sensation that it perceives when it acts on the upper actuation stem.

[0015] C&K implements this principle in the design of the "K12S" push button switch.

[0016] The last free turn of the return spring interacts with the actuator ramp, generating several forces, including a radial force that causes the opening of the last turn and determines the mechanical characteristics of the switch and an axial force that pushes the last turn of the return spring axially downwards in the direction of the actuation stroke, which is axially stopped in principle by a fixed annular stop face belonging to the lower base.

[0017] The combination of these two forces causes the last turn to be pushed radially outwards.

[0018] The last turn of the spring can get stuck between the ramp of the upper actuation rod and the lower base, which then causes a significant increase in the actuation force and / or an uncontrolled variation of the actuation force and an increase in the range of values of this actuation force in the technical specifications of the product. SUMMARY

[0019] To remedy this drawback, the present invention proposes an electrical switch of the type described above, characterized in that:

[0020] - the guide hole comprises a series of axial ribs, each of which projects radially towards the inside of the guide hole and is slidably housed in a complementary axial slot formed in the side wall; and

[0021] - the fixed stop face is constituted by the upper radial end face of each axial rib.

[0022] According to other characteristics of the invention:

[0023] - the housing is axially bounded downwards by a lower radial shoulder and is defined upwards by the cam profile;

[0024] - the cam profile is a conical section, the apex of which is oriented axially downwards, forming a ramp that cooperates with the elastic ring;

[0025] - each axial slot formed in the side wall extends axially upwards beyond the cam profile;

[0026] - the elastic return member is a helical compression spring, the section of the upper actuation rod axially passes through the helical compression spring, and its lower turn constitutes the elastic ring;

[0027] - the spring is axially compressed mounted in the section of the upper actuation rod, and its lower turn constitutes the elastic ring;

[0028] - the spring is axially compressed mounted between the upper radial end face of each axial rib and the upper radial shoulder, which axially bounds the section upwards. BRIEF DESCRIPTION OF DRAWINGS

[0029] Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

[0030] Figure 1 is an exploded side view of an exemplary embodiment of an electrical switch according to the present invention;

[0031] Figure 2 is a cross-sectional view through the longitudinal and vertical mid-planes of the switch in Figure 1

[0032] Figure 3 is a cross-sectional view through the vertical and transverse mid-planes of the switch in Figure 1

[0033] Figure 4 is an exploded perspective view of the lower base plate, return spring, and upper actuating lever of the switch in Figure 1

[0034] Figure 5 is a perspective view of the upper actuating lever of the switch in Figure 1

[0035] Figure 6 is a perspective view of the upper actuating lever and return spring of the switch in Figure 1

[0036] Figure 7 is an axial end view of the upper actuating lever of the switch in Figure 1

[0037] Figure 8A is a cross-sectional view through the longitudinal and transverse mid-planes of the lower base plate, return spring, and upper actuating lever of the switch in Figure 1

[0038] Figure 8B is a view similar to Figure 8A , with the upper actuating lever shown in the active downward position without the return spring;

[0039] Figure 9 is a partial cross-sectional view along line 9-9 through the longitudinal and transverse planes of Figure 8A

[0040] Figure 10 is a view similar to Figure 9 , showing a second instance of the return spring design with a circular lower end turn. DETAILED DESCRIPTION

[0041] ​​​​​​​​For the description of the invention and the understanding of the claims, the vertical, longitudinal and transversal orientations according to the references V, L, T shown in the figures will be employed with reference to the terrestrial gravity, without limitation and not limitatively, the longitudinal L and transversal T axes of said references V, L, T extending in the horizontal plane.

[0042] By convention, the vertical axis V is oriented from bottom to top.

[0043] In the following description, identical, similar or analogous elements will be designated by identical references.

[0044] First example of embodiment

[0045] In the following example, the electrical switch 20 is generally symmetrical in design with respect to the intermediate vertical and longitudinal plane and with respect to the intermediate vertical and transversal plane.

[0046] Vertically from bottom to top, the electrical switch 20 (and in particular the upper actuation stem 24 thereof Figures 1 to 3 is described in the intermediate base 22) comprises a lower base 22 and an upper actuation stem 24 mounted so as to be slidable along the main vertical axis A with respect to the lower base 22.

[0047] The lower base 22 forming the housing is closed at the top by an upper actuation cover 26 mounted so as to be axially mobile with respect to the lower base 22.

[0048] The electrical switch 20 further comprises a compression coil spring 28 axially inserted between the upper actuation stem 24 and the lower base 22 and a flexible transversal sealing membrane 30 cooperating with the upper cover 26 and the lower base 22.

[0049] The electrical switch 20 also comprises two elastically deformable electrical contact blades 32 and 34, each of which is connected to a connection terminal 36. Thus, by way of example, the electrical switch 20 is here of the normally closed type, in which, in the absence of actuation, the two electrical contact blades 32 and 34 elastically abut against each other and establish an electrical switch manner or path between the two associated connection terminals 36.

[0050] As a non-limiting example, the electrical switch 20 is of the light-emitting type and comprises for this purpose a light source 38, for example a light-emitting diode, connected to a connection terminal 40 for its electrical supply.

[0051] The lower base 22 is moulded in plastic around the electrical connection elements of the electrical contact blades 32 and 34 and of the light source 38.

[0052] The lower base 22 is in the form of a cylindrical housing of the axis A, the lower face 42 of which has a pin 44 for fixing to a support element (not shown), for example a printed circuit board.

[0053] The body 46 of the lower base 22 defines a lower cavity 48 which is open vertically upward and a substantially cylindrical upper cavity 50 which is also open upward and is delimited by an upper edge 52 of the lower base 32.

[0054] The two cavities 48 and 50 are delimited from one another by a horizontal radial face 49 which is oriented vertically upward.

[0055] The electrical contact blades 32 and 34 extend vertically upward within the lower base 22 from a bottom 47 of the lower cavity 48. The light source 38 is also arranged in the bottom 47 of the lower cavity 48.

[0056] The side wall 54 of the lower base 22 has a lower radial groove 56 into which a complementary annular rib 58 of the sealing membrane 30 is elastically fitted and two diametrically opposite vertical axial grooves 60 which are closed at their upper end.

[0057] The upper actuator cover 26 comprises a horizontal top plate 62 and a cylindrical tubular side wall 64 which comprises two diametrically opposite hooks 66 which extend substantially inward and each of which is housed in the associated groove 60 in the side wall 54 of the lower base 22.

[0058] The top plate 62 is centrally perforated and is closed thereat by a translucent or transparent plate 68 which may, for example, be colored and / or have a pattern and can allow the illumination of the light source 38 to be observed.

[0059] An inner bottom face 70 of the top plate 62 defines a housing 72 which is open axially downward and has radially angularly graduated fingers 74.

[0060] A side wall 63 of the top plate 62 has an internal radial groove 76 into which a complementary annular bead 78 of the sealing membrane 30 is elastically fitted.

[0061] The lower cavity 48 of the lower base 22 has a series of axial guide holes 80 in the form of recessed segments, in this case there are six of them.

[0062] The axial guide holes 80 thus formed extend vertically upward from the bottom 47 and axially into the face 49.

[0063] According to the invention, the lower cavity 48 of the lower base 22 also has a series of vertical axial ribs 82 each of which extends radially inward from the recessed cylindrical surface of the guide hole 80.

[0064] By way of illustration, and in particular in Figure 9 It can be seen that the number of ribs 82 is eight and comprises two pairs of upper and lower ribs and two transversely opposite transverse ribs.

[0065] Each rib 82 is delimited axially upward by an upper radial end face 84 which is coplanar with the face 49.

[0066] Thus, in the sense of the application, the eight faces 84 are stop faces each constituting a part of a horizontal stop face oriented vertically upwards for the axial downward support of the return spring 28.

[0067] The lower cavity 48 of the lower base 22 has four other grooves 86 arranged at a ninety degree angle.

[0068] The upper actuation lever 24 is a plastic molded piece consisting essentially of a hollow tubular body 90 delimited by an inner recessed cylindrical wall 92 and a convex cylindrical lateral wall 94.

[0069] At its upper end, the body 90 extends into an upper cylindrical radial plate 96 which is housed in the housing 72 and has an angular indexing notch 97 in which the indexing finger 74 of the actuation cap 26 is housed.

[0070] Inside the tubular body 90, the upper actuation lever 24 has two diametral plates 98 and 100 suitable for acting on the electrical contact elements.

[0071] In the example shown in the figures, the diametral plate 98 is suitable for cooperating with the two electrical contact blades 32 and 34 to move them longitudinally away from each other in order to interrupt the associated electrical switching mode.

[0072] Thus, considering the rest position illustrated in Fig. 1, the axial downward displacement of the plate 98 causes the opening of the electrical contact constituted by the two electrical contact elements 32 and 34, on which it acts by elastically deforming them to move them away from each other. Figure 2

[0073] This actuation is obtained by acting on the upper actuation cap 26 which axially pushes on the upper radial plate 96 of the upper actuation lever 24 to move the latter axially downwards with respect to the lower base 22 and therefore with respect to the electrical contact elements 32 and 34.

[0074] The lateral wall 94 of the upper actuation lever 24 extends axially from a lower annular radial face 102 of the radial plate 96 to a lower axial annular end radial face 104.

[0075] The lateral wall 94 of the upper actuation lever 24 has an internal radial groove 106 delimited by a convex cylindrical bottom wall 108.

[0076] The groove 106 is delimited axially upwards by a frustoconical upper radial shoulder 110, the vertex of which is oriented downwards and constitutes a connecting slope between the bottom wall 108 of the radial groove 106 and the convex lateral wall 94 of the upper actuation lever 24.

[0077] ​The radial slot 106 is axially delimited upwards by a lower radial shoulder 112, which is axially delimited by an axially facing upwards radial face 114.

[0078] According to the teachings of the present application, the lateral wall 94 of the upper actuation rod 24 has a series of vertical axial slots 116, each of which extends radially inwards from the surface of the convex cylindrical lateral wall 94.

[0079] The profile of the bottom wall 118 of each axial slot 116 is here identical to the convex cylindrical profile of the bottom wall 108 of the radial slot 106.

[0080] Each axial slot 116 opens axially downwards into the annular radial lower axial end face 104.

[0081] The number, size and angular distribution of the axial slots 116 are identical and complementary to the number, size and angular distribution of the axial ribs 82 of the lower base 22.

[0082] Thus, as can be seen in particular in Figure 9 , in the assembled position in which the lateral wall 94 of the upper actuation rod 24 is housed and axially slidingly guided in the guide hole 80, each axial rib 82 is axially slidably housed in the complementary axial slot 116 of the upper actuation rod 24.

[0083] The return spring 28 is a helical compression spring, also known as a coil spring, the cylindrical body of which is penetrated by the upper actuation rod 24.

[0084] The upper end spiral 120 is here of generally circular shape and is axially supported on the lower annular radial face 102 of the radial plate 96.

[0085] The lower end turn 122, also known as the last turn or coil of the return spring 28, is here of generally triangular shape and axially abuts the axially facing upwards radial face 114 of the lower radial shoulder 112.

[0086] Thus, as can be seen in particular in Figure 6 , when the spring is assembled onto the actuation rod, the return spring is installed in slight axial compression, without play between the opposite radial faces 102 and 114.

[0087] In this initial state of the return spring 24, and as can also be seen in Figure 2 and 3 , the last turn 122 is arranged in a recess in the lateral wall 94 of the upper actuation rod 24 constituted by the radial slot 106.

[0088] The average internal diameter of the last turn is reduced relative to the internal diameter of the other turns, so as to abut the convex cylindrical lateral wall of the radial slot 106. In this way, the turn 122 is axially supported on the face 84 and the haptics during actuation are optimised.

[0089] In the upper rest position of the upper actuation rod 24, the last turn 122 abuts axially against the radial face 49 of the lower base 22 and the spring 24 exerts an elastic return force on the upper actuation rod 24, this upper rest position being determined by the hook 66 abutting axially upwards against the upper bottom 61 of the axial slot 60.

[0090] As can be seen in detail in Figure 9 the different sections of the last turn 122 of the return spring 28 abut axially against or extend with respect to the abutment faces 84 of the axial ribs 82.

[0091] Thus, when the switch is actuated and the upper actuation rod 24 is pushed axially downwards against the elastic return force exerted on it by the spring 28, the last turn 122 is axially supported on the face 84 without any risk of this turn 122 being trapped between the upper actuation rod 24 and the lower base 22, even when the last turn 122 cooperates with the cam profile constituted by the frustoconical ramp 110.

[0092] Second example embodiment

[0093] In the second embodiment shown, Figure 10 In the second embodiment shown, the last turn 122 is substantially circular in shape.

Claims

1. An electrical switch (20) with axial actuation, comprising: - a lower base (22); - an upper actuation stem (24) comprising a section of its cylindrical lateral wall (94) axially slidingly guided in a guide hole (80) formed in the lower base (22); - an elastic return member (28) for returning the upper actuation stem (24) to a high rest position, wherein under the effect of an actuation force applied to the upper actuation stem (24) and against the force exerted by the elastic return member (28), the upper actuation stem (24) is axially displaced along an actuation stroke towards a mobile lower position relative to the lower base (22) to change the state of at least one electrical switching mode (32, 34), and comprising an elastic ring (122): - which is arranged in a peripheral housing (106) formed in the lateral wall (94), - which is axially crossed by the section of the upper actuation stem (24), - which bears axially downwards against a fixed stop surface belonging to the lower base (22) during the actuation stroke of the upper actuation stem (24); - and which cooperates with a cam profile (110) formed in the lateral wall (94) during the actuation stroke of the upper actuation stem (24), the cam profile radially deforming the elastic ring so as to exert an elastic resistance to the actuation of the upper actuation stem (24), characterized in that: - the guide hole (80) comprises a series of axial ribs (82), each of which projects radially inwards from the guide hole (80) and is slidingly housed in a complementary axial slot (116) formed in the lateral wall (94); and - the fixed stop surface is constituted by a radially upper end face (84) of each axial rib (82).

2. The electrical switch of claim 1, wherein The peripheral housing (106) is axially downwardly delimited by a lower radial shoulder (112) and upwardly defined by the cam profile (110).

3. The electrical switch of claim 1, wherein The cam profile (110) is a conical section, the apex of which is oriented axially downwards, forming a slope with which the elastic ring (122) cooperates.

4. The electrical switch of claim 1, wherein Each axial slot (116) formed in the lateral wall (94) extends axially upwards beyond the cam profile (110).

5. The electrical switch of claim 1, wherein, The elastic return member (28) is a helical compression spring, the section of the upper actuation stem (24) axially passing through the helical compression spring, a lower turn (122) of which constitutes the elastic ring.

6. The electrical switch of claim 2, wherein, The elastic return member (28) is axially compressively mounted between the radially upper end face (84) of each axial rib (82) and an upper radial shoulder (102) axially upwardly delimiting the section.

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