Abstract:
A device for amplifying the movement of an operating button of a switch, wherein the switch is fixed in a body of the device. The device includes a pusher that is translatable along an central longitudinal axis of the body. The translation of the pusher constitutes the amplified motion. The device also includes a varying-diameter cylindrical member, and a first support region. The first support region is capable of moving along a ramp of the pusher, when the pusher moves along the central longitudinal axis of the body. The varying-diameter cylindrical member includes a second support region in permanent contact with a region of the body, whatever the position of the pusher, and a third support region in contact with the operating button of the switch.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to and claims priority, under 35 U.S.C. §119, from French Patent Application No. 99 13612, filed on Oct. 29, 1999, the entire contents of which is hereby incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device to amplify the movement of an operating button for a switch, which is used especially when the operating button of the switch has a small range of travel, for example, about one millimeter. 
     2. Discussion of Background 
     Switches, of the type discussed above, are used when fast selection switching is required, for example, to prevent rebounding between the contacts of the switch. 
     In a movement-amplifying device, the operating button is not operated directly, but by means of a pusher that is movable in translation and has a range of travel, for example, about 5 millimeters, which is far greater than the range of travel of the operating button, i.e., about 1 millimeter. The amplified range of travel of the pusher is especially useful for broadening the manufacturing tolerance values for mechanisms, such as a cam, for example, which operate the pusher. 
     The prior art movement-amplifying devices are complicated. They comprise a large number of mechanical parts, and especially several springs. 
     SUMMARY OF THE INVENTION 
     The present invention is aimed at simplifying the complicated movement-amplifying devices of the prior art. 
     To achieve this aim, an object of the present invention is to provide a device to amplify the movement of an operating button of a switch, wherein the switch is fixed in a body of the device. The device includes a pusher which is translatable along a central longitudinal axis of the body and the central longitudinal axis of the body is coincident with a central longitudinal axis of the pusher. The translation of the pusher constitutes the amplified motion. The device includes a varying-diameter cylindrical member having first, second, and third support regions. The first support region of the cylindrical member is capable of moving along a ramp of the pusher when the pusher moves along the central longitudinal axis of the body. The second support region of the cylindrical member is in permanent contact with a region of the body whatever the position of the pusher. The third support region of the cylindrical member is in contact with the operating button of the switch. 
     An advantage of the present invention is that the movement-amplifying device provides for the depressed and released positions of the pusher to be reversed from the depressed and released positions of the operating button of the switch. In other words, when the pusher is at rest or in a released position, the operating button of the switch is in a depressed position and when the pusher is in a depressed position, the operating button of the switch is in a released position. The reversed states of the depressed and released positions for the pusher and the operating button of the switch are advantageous, particularly for small-motion switches which cannot withstand the sudden action of having their operating button pressed upon because such sudden pressing action could cause damage to the switch. Because of the reversed states of the depressed and released positions of the pusher and the operating button of the switch, the speed with which the operating button is pressed is related to the structure for providing permanent contact between the second support region of the cylindrical structure and the region of the body, for example, by using a spring that maintains this contact. The calibration of this spring controls the speed at which the operating button is pressed and prevents sudden depressing of the operating button so that the switch will not be damaged. 
     Another advantage of the present invention is that the movement-amplifying device enables the progress of the travel of the operating button to be set as a function of the progress of travel of the pusher. This setting of the progress of the travel of the operating button of the switch as a function of the progress of travel of the pusher is obtained by adapting the shape of the ramp. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     The present invention will be understood more clearly and other advantages will appear from the following detailed description of an embodiment illustrated by the appended drawing in which the different figures show several positions of the same device. More specifically: 
     FIG. 1 is a cross-sectional view of a movement-amplifying device showing a pusher in a released position; 
     FIG. 2 is a cross-sectional view of the movement-amplifying device of FIG. 1 with the pusher in an intermediate position; and 
     FIG. 3 is a cross-sectional view of the movement-amplifying device of FIG. 1 with the pusher in a depressed position. 
    
    
     For greater convenience, the same structural elements of the device will bear the same reference numerals in the different figures. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The different structural elements of the movement-amplifying device, according to the present invention, will now be described with reference to FIGS. 1-3. Referring to FIG. 1, a body  1  is shown and bears the other structural elements of the device. More particularly, the body  1  has a first cavity in which a switch  3  is fixed. The switch  3  has, for example, a parallelepiped shape. The lower part of the switch has electrical connection pins  4 ,  5 , and  6 . The upper part of the switch  3  has an operating button  7  capable of translation, for example, back and forth between several positions. The switch  3  sets up contact between certain ones of the pins  4 ,  5 , and  6  of the switch  3  as a function of the position of the operating button  7 . For example, the switch  3  has three pins  4 ,  5 , and  6  and the operating button  7  can move between two positions, i.e., a depressed position and a released position. In the depressed position, the operating button  7  places the pins  4  and  5  of the switch  3  in contact and in the released position, the operating button  7  places the pins  4  and  6  of the switch  3  in contact. The operating button  7 , shown in FIG. 1, is in a depressed position. 
     Of course, it is possible to implement the present invention with a switch  3  comprising several separate circuits and/or a switch  3  having operating button  7  which can take more than two positions, wherein each of the positions put different pins  4 ,  5 , and  6  of the switch  3  into contact. 
     Above the first cavity  2 , the body  1  has a second cavity  8  communicating with the first cavity  2 . The second cavity  8  has an aperture  9  which opens out on the top of the body  1 . The second cavity  8  and the aperture  9  are cylindrical, for example, along a central longitudinal axis  10  of the body  1  and the pusher  12 . The diameter of the aperture  9  is smaller than the diameter of the second cavity  8  so that a shoulder  11  is formed inside of the body  1 . 
     The device also comprises a pusher  12 , substantially formed by a cylindrical part  13  along the central longitudinal axis  10  of the body  1  and an annular flange  15  at a lower end  14  of the cylindrical portion  13  of the pusher  12 . The diameter of the annular flange  15  of the pusher  12  as well as the diameter of the cylindrical portion  13  are such that the cylindrical portion  13  can move freely in the aperture  9  until the annular flange  15  comes to abut the shoulder  11  formed between the second cavity  8  and the aperture  9 , as is the case shown in FIG.  1 . The cylindrical portion  13  of the pusher  12  extends along the central longitudinal axis  10  of the body  1  up to an end  16 , which is located above the top surface of the body  1 . 
     The device furthermore has a varying-diameter cylindrical member  20 , which is substantially generated by revolution. The central longitudinal axis of the varying-diameter cylindrical member  20  is substantially coincident with the central longitudinal axis  10  of the body  1 , when the device is in the position shown in FIG.  1 . The varying-diameter cylindrical member  20  has a first finger  21 . The first finger  21  has an end which is in contact with the operating button  7  of the switch  3 . 
     Advantageously, the surface of the end of the finger  21  which is in contact with the surface of the operating button  7  are substantially convex so as to provide for a substantially localized contact. 
     The varying-diameter cylindrical member  20  furthermore has a flange  22  designed to press against a region of the body  1 . 
     Advantageously, the external diameter of the flange  22  is substantially the same as the internal diameter of the second cavity  8  and a support region belonging to the body  1  is formed by an added-on part  23  fixed to the body  1  so that the varying-diameter cylindrical member  20  can be supported inside of the body  1 . 
     The added-on part  23  is, for example, a flat washer crimped in the body  1 . The internal diameter of this flat washer is smaller than the outer diameter of the flange  22 . As an alternative, the added-on part  23  may also be an internal circlip mounted in a groove of the body  1 . In that case, the internal diameter of the internal circlip would be, similar to the flat washer, smaller than the outer diameter of the flange  22 . The varying-diameter cylindrical member  20  also has a second finger  24 . An end  25  of the second finger  24  is supported against a ramp  30  belonging to the pusher  12 . The first finger  21  and the second finger  24  both extend advantageously along the central longitudinal axis of the varying-diameter cylindrical member  20 , which as shown in FIG. 1 is coincident with the central longitudinal axis  10  of the body, on either side of the flange  22 . 
     Advantageously, the end  25  of the second finger  24  has a convex surface so that the support against the ramp  30  is substantially localized. 
     The ramp  30  is made, for example, by means of a bore made in the pusher  12 . A central longitudinal axis  31  of the bore is parallel to and slightly offset from the central longitudinal axis  10  of the body  1 . The bore comprises a smooth, cylindrical blind hole  32 . The bore opens out on the lower end  14  side of the pusher  12  through a countersunk feature  33 . In the embodiment shown in FIG. 1, the distance the central longitudinal axis  31  of the bore is offset from the central longitudinal axis  10  of the body  1  is such that a part of the countersunk feature  33  is located outside of the pusher  12 . 
     The dimensions of the different parts comprising the device are such that when the pusher  12  is in the highest possible position, namely, when the annular flange  15  of the pusher  12  substantially contacts the shoulder  11  between the second cavity  8  and the aperture  9 , the flange  22  is substantially supported on an entire perimeter thereof against the added-on part  23 . Advantageously, an elastic element  35  is provided to ensure this support. This elastic element  35  is also used to make the annular flange  15  of the pusher  12  approach the shoulder  11  between the second cavity  8  and the aperture  9 . The elastic element  35  is, for example, a helical spring placed between the pusher  12  and the flange  22 . The central longitudinal axis of the helical spring is substantially merged with the central longitudinal axis  10  of the body  1 . 
     It is clearly not possible to obtain perfect contact simultaneously between the flange  22  and the added-on part  23 , the end  25  of the second finger  24  and the ramp  30 , and the annular flange  15  and the shoulder  11  between the second cavity  8  and the aperture  9 . Advantageously, a functional clearance is planned between the end  25  of the second finger  24  and the ramp  30 . Thus, the other contacts will be obtained surely and precisely. 
     When the pusher  12  is in its highest possible position, the first finger  21  presses the operating button  7  of the switch  3  and holds it in the depressed position. When the contact between the flange  22  and the added-on part  23  is obtained with precision, the pressing of the first finger  21  and the operating button  7  is controlled with greater certainty. 
     FIG. 2 shows the structural element of the device shown in FIG.  1 . Here the pusher  12  has been slightly pushed in along the central longitudinal axis  10  of the body  1 . The difference between the positions of the pusher  12  shown in FIG.  1  and FIG. 2 is that the end  25  of the second finger  24  of the varying-diameter cylindrical member  20  has slid along the countersunk feature  33 , and the flange  22  has become partially detached from the added-on part  23  so as to keep only a substantially localized contact  26  with the added-on part  23 . The first finger  21  remains in contact with the operating button  7  of the switch  3 , and when the operating button  7  of the switch is lifted, the operating button  7  of the switch  3  is placed in a released position. 
     The varying-diameter cylindrical member  20  pivots about the substantially localized contact  26  when the pusher  12  is depressed. It is not necessary to know the position of the substantially localized contact  26  since the substantially localized contact  26  can be located anywhere on the added-on part  23 . The position of the substantially localized contact  26  is a function of the position of the ramp  30  and therefore, of the angular orientation of the pusher  12  around the central longitudinal axis  10  of the body  1 . However, once all of the pusher  12 , the elastic element or helical spring  35 , the varying-diameter cylindrical member  20 , and the added-on part  23  are assembled, this angular orientation or position of the pusher  12  has no influence on the operation of the device. 
     FIG. 3 again shows the same structural elements. This time, the pusher  12  has been completely depressed downwardly along the central longitudinal axis  10  of the body  1  until the elastic element or helical spring  35  is compressed to the maximum. Advantageously, the varying-diameter cylindrical member  20  is provided with a stop  40 . The stop  40  stops the downward travel of the pusher  12  along the central longitudinal axis  10  of the body  1 . As an alternative, the stop  40  could also be provided on the body  1 . The operating button  7  of the switch  3  is thus in the released position, as shown in FIG.  2 . 
     The shape of the ramp  30 , shown in the different figures, is such that the movement of the operating button  7  of the switch  3  is obtained on a small part of the travel of the pusher  12 . More specifically, the operating button  7  of the switch  3  is released at the very beginning of the downward travel of the pusher  12  when the end  25 , of the second finger  24  of the varying-diameter cylindrical member  20 , moves along the countersunk feature  33 . Of course, it is possible to give the ramp  30  any shape enabling the activation of the operating button  7  at another position of the pusher  12 . It is also possible to obtain variations in the speed of actuation of the operating button  7  with respect to the speed of movement of the pusher  12  by modifying the slope of the countersunk feature  33 .