Abstract:
A switch destined in particular for usage as a general cutout switch for batteries in low-voltage vehicle electrical systems and the like includes a supporting body carrying at least one pair of fixed electrical contacts,—a mobile element carrying at least one mobile electrical contact, cooperating with the fixed contacts and movable in a rectilinear direction between an open-contacts position and a closed-contacts position and vice versa, a rotary control member suitable for controlling the movement of the mobile element, an elastic structure that tends to push the mobile element towards the open-contacts position, mutually cooperative contact surfaces provided on the control member and on the mobile element and mutually cooperative stop mechanisms provided on the supporting body and on the rotary control member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention refers to switch, destined in particular for usage as a general cutout switch for batteries in low-voltage vehicle electrical systems and the like. 
     2. Statement of the Art 
     Switches of this type are normally equipped with at least a pair of fixed contacts and at least one mobile contact that can be shifted, with respect to the fixed contacts, between an open position and a closed position. 
     Switches destined for utilization in vehicle electrical systems as battery cutouts must be capable of guaranteeing circuit interruption in emergency situations via a simple and intuitive manoeuvre, such as simply applying pressure on a knob for example. 
     In other applications, instead, there can exist the opposite need, i.e. that of only allowing the switch to be opened or closed by personnel in possession of a special key. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of present invention is to provide a switch that is simple, robust and reliable, having a control mechanism that allows versions of the switch commanded by both knob and key to be realized. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described in detail, with reference to the enclosed drawings, which are supplied as a non limitative example and where: 
     FIG. 1 is a perspective view of a first form of embodiment of a switch in accordance with the invention, 
     FIG. 2 is a plan view of the switch in FIG. 1, 
     FIGS. 3 and 4 are sectional views along the lines III—III and IV—IV respectively, as shown in FIG. 2, 
     FIG. 5 is a perspective, cutaway view of a the switch in FIG. 1, 
     FIGS. 6 and 7 are partial sectional views illustrating the switch in FIG. 1 in the open position and closed position respectively, 
     FIG. 8 is a schematic perspective illustrating the part indicated by the arrow VIII in FIG. 2, 
     FIGS. 9,  10 ,  11  and  12  are schematic plan views perpendicular to the arrow IX in FIG. 8, and 
     FIGS. 13 and 14 are partial, perspective cutaway views of a second form of embodiment of the switch in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIG. 1, item  10  indicates a first form of embodiment of the switch in accordance with the invention, destined for utilization as a battery cutout for vehicles, boats and the like. The switch  10  includes a supporting body  12  in an injection moulded plastic material, from which two main electrical contacts  14  protrude. In the example of embodiment illustrated in the figure, the switch  10  is also equipped with a number of secondary, electrical spade terminals  16 . The switch  10  in accordance with the first form of embodiment of the present invention includes a control knob  18  that is used to control the opening and closing manoeuvres of the switch. 
     With reference to FIGS. 3 and 4, the terminals  14  carry a pair of fixed contacts  20  situated inside a cavity  22  in the main body  12 . The fixed contacts  20  cooperate with a mobile contact  24  carried on a mobile element  26 , mounted such that it can slide within a tubular portion  28  of the main body  12 . The mobile element  26  carries a coil spring  30  in compression that presses the mobile contact  24  against the seat  32  of the mobile element  26 . This mobile element cooperates with a prismatic guide  32 , created on the inside of the supporting body  12  (FIG. 5) so that it can move along the longitudinal axis  34 , but without being able to rotate around the aforesaid axis. The mobile element  26  carrying the mobile contact  24  can move between the open-contacts position illustrated in FIG. 3 and a closed position in which the mobile contact  24  is pressed against the fixed contacts  20 . The mobile element  26  is pushed towards the open position by the elastic force produced by the coil spring in compression  38 , coaxial with the longitudinal axis  34  and positioned between a wall  40  of the supporting body  12  and an appendage  42  of the mobile element  26 . 
     A small, sliding shaft  44  is arranged along the longitudinal axis  34  and carries an auxiliary mobile contact  45  that cooperates with the auxiliary fixed contacts  46  connected to the auxiliary terminals  16 . The shaft  44  is associated with a spring in compression  48  that tends to push it towards the open-contacts position. The appendage  42  of the mobile element  26  rests against the upper end of the shaft  44  in the closed-contacts position and, in turn, presses the shaft  44  in the auxiliary closed-contacts position. 
     With reference to FIG. 5, at its upper end, the mobile element  26  carries a cam-shaped surface  50 , with substantially the form of a wedge obtained from a circular profile. The mobile member  36  is preferably equipped with two or more cam-shaped surfaces  50 , angularly equidistant along the upper circumferential border of the mobile element  26 . Each of these cam-shaped surfaces  50  cooperates with a presser element  52  carried by a rotary control member  54 . The rotary control member  54  is arranged coaxially to and above the mobile element  26  and has an upper surface  56  that faces onto a seat  58  that is fixed with respect to the main body  12  and is preferably obtained as an integral part of the upper end of the tubular portion  28 . The rotary control member  54  is pushed against the seat  58  by the elastic force of the spring  38 . In fact, the load on the spring  38  pushes the mobile element  26  upward, which in turn, pushes the rotary element  54  upwards via contact between the cam-shaped surfaces  50  and the presser elements  52 . The upper surface  56  of the rotary control member  54  is equipped with at least one catch  60  that is destined to cooperate with a corresponding catch  62  present on the contact surface  58  (see FIGS.  6  and  7 ). As is illustrated in FIG. 7, the reciprocal engagement between the catches  60  and  62  occurs when the angular position of the rotary control member  54  corresponds to the closed-contacts position, i.e. the condition in which the mobile member  26  is in its lowermost position. The rotary control member  54  is also free to move in the direction of the longitudinal axis  34  to disengage the catches  60  and  62 , and so allow the switch to return to the open-contacts position. Two or more pairs of cooperating catches  60  and  62  could be provided for on the mutually facing surfaces  56  and  58 . 
     With reference to FIGS. 2 and 5, the rotary control member  54  has an axial portion  64  that protrudes upwards and is equipped with a pair of appendages  66  that engage with respective arched grooves  68  formed inside the control knob  18  and with their centre on the longitudinal axis  34 . A return spring  69  is positioned around the appendage  64  and has its ends anchored to the supporting body  12  and control knob  18  respectively. The grooves  68  have an angular extension of approximately 90°, which corresponds to the angular travel that the control knob  18  must be subjected to in order to bring the switch from the open position to the closed position. The return spring  69  applies an elastic force to the control knob  18  that tends to make it turn in the opposite direction to that in which it must be turned in the manoeuvre to close the switch, or rather the manoeuvre that brings the switch from the open-contacts position to the closed-contacts position. The arched grooves  68  of the control knob  18  appear on the outer surface of the knob, so that the appendages  66  are visible when viewing the switch from above. Preferably, the appendages  66  should be coloured so that they are easily visible and “ON” and “OFF” indicators provided on the top surface of the knob  18  so that the state of the switch, in the respective open-contacts or closed-contacts positions, can be visually determined. 
     The operation of the switch in accordance with the invention will now be described, starting from the open-contacts configuration illustrated in FIGS. 3 and 6. In this condition, the knob  18  is in the position shown in FIG.  9 . The appendages  66  are in contact with the first end of the respective grooves  68 . As illustrated in FIG. 6, the position of the presser element of rotary control element  54  is level with the lowest point of the inclined surface  50  and, in consequence, the mobile element  26  is in its upper position, in which the mobile contact  24  is separated from the fixed contacts  20 . To set the switch  10  in the closed-contacts operational position, the control knob  18  is turned by approximately 90°, in a clockwise direction with reference to FIG.  9 . During this rotation, the appendages  66  are dragged into rotation around the axis  34  by contact with the ends of the grooves  68 . In consequence, the axial portion  64  carrying the appendages  66  also performs a rotation of approximately 90° and turns the rotary control member  54  by the same amount. When this rotation is complete, the configuration of the switch is that shown in FIG. 7, where the catch  60  is engaged with the stationary catch  62 . The rotation of the rotary control member  54  positions the presser element  52  level with the highest point of the inclined surface  50 . Since the mobile element  26  cannot rotate any further with respect to the stationary casing, this element is consequentially obliged to move downwards against the thrust of the spring under compression  38 . This downwards motion of the mobile element  26  brings the mobile contact  24  into contact with the fixed contacts  20 . The coil spring  30  keeps the mobile contact  24  pressed against the fixed contacts  20  and permits movement of the mobile contact to allow for play and tolerances. When the 90° clockwise rotation of the knob  28  is completed, with respect to the knob, the appendages  66  will be in the position illustrated in FIG.  10 . When the user releases the knob  18 , it will rotate anticlockwise under the action of the return spring  69 . The anticlockwise rotation terminates when the appendages  66  come into contact with the opposite ends of the grooves  68 , in the position shown in FIG.  11 . This position is a stable position for the knob  18 . The appendages  66  are positioned in correspondence to the “ON” sign, which indicates the closed-contacts operational state of the switch  10 . 
     In the closed-contacts position, the rotary control member  54  is kept in a fixed position with respect to the main body  12  by the reciprocal engagement of the teeth  60  and  62 . This engagement remains stable due to the fact that the spring  38  exerts an upward, axial thrust that keeps the rotary control member  54  pushed against the surface  58  of the main body  12 . 
     To return the casing to the open-contacts operational position, all that is needed is to push the control knob  18  downwards. This downward force produces a downward movement on the rotary control member  54  that disengages the catch  60  from the corresponding stationary catch  62 . As soon as the catch  60  disengages, the rotary control member  54  is free to rotate around the axis  34 . Due to the contact between the inclined surface  50  and the presser member  52 , the axial thrust of the spring  38  makes the control member  54  rotate and push the mobile element  26  upwards. Rotation of the rotary control member  54  stops when this member reaches an end stop on the stationary casing (not illustrated). During the rotation of the rotary control member  54 , the knob  18  remains stationary, thereby obtaining a relative rotation of  900  in the anticlockwise direction between the appendages  66  and the knob  18 . The switch thus returns to the configuration illustrated in FIG. 12, where the appendages  66  indicate the “OFF” position, corresponding to the open-contacts position. The fact that the control knob  18  can rotate and is elastically pulled in the opposite direction to that in which it is rotated to close the switch, consequently allows the operational state of the switch to be visibly checked via the appendages  66 . 
     In the device in accordance with the invention, the switch&#39;s control mechanism is suitable for realising both a knob-type control and a key-type control. FIGS. 13 and 14 illustrate a variant of the switch in accordance with the invention in which the knob  18  is replaced by a control key  70 . The key control  70  has an engagement portion  72  that is inserted via a slot  74  in the tubular portion  28  of the main body  12  and that engages with a seat  76  realised on the upper surface of  56  of the rotary control member  54 . Part of the control portion  72  extends beyond the upper surface  56  in order to form the catch  60 , as in the previously described solution. In the situation where the switch  10  is open, the seat  76  of the rotary control member  54  is aligned with the slot in the main body and the key can be inserted or removed from the switch. To close the switch, the key  70  must be inserted and turned clockwise until the tooth  60  engages with the corresponding tooth formed on the surface  58  of the main body. In this condition, the switch is closed and the key  70  cannot be extracted. To open the switch, it is sufficient to simply push the key  70  downwards. Following downwards pressure on the key, the rotary control member  54  rotates in the anticlockwise direction, returning to its position that corresponds to the open-contacts position. The operational state of the switch is indicated by the position of the key  70 . The switch in this variant of the invention can only be closed by someone possessing the specific key, which could be advantageous from the antitheft viewpoint for example. 
     The key can only be extracted when the switch is open and hence the absence of the key indicates that the switch is open.