Patent Publication Number: US-2021164275-A1

Title: Door-Lock Device for Household Appliance, In Particular Dishwashers

Description:
FIELD OF THE INVENTION 
     This invention concerns a door-lock device for appliances, in particular for dishwashers. 
     DESCRIPTION OF THE RELATED TECHNIQUE 
     EP-A-2643535 of the same Applicant describes a door-lock device for appliances, in particular for dishwashers, comprising a support frame, a lock element rotationally carried by the support frame around an axis which is transversally movable with respect to the support frame. The lock element cooperates with elastic means that make the lock element rotate between a first set position wherein the lock element engages a door strike and a second set position wherein the lock element does not engage the door strike. 
     The door-lock device known from EP-A-2643535 is subject to certain inconveniences, among which: 
     a floating mechanism is necessary to rearrange the lock element after the opening of the door; 
     the lock element is held in a set manner in the open position and in the closed position by means of helical springs under traction which exhibit lesser characteristics as regards duration and reliability, 
     the door-lock device comprises a high number of components and it is hardly compact. 
     Purpose and Synthesis of the Invention 
     The aim of this invention is that of supplying a door-lock device for appliances that overcomes the inconveniences of the prior art. 
     According to this invention, this purpose is achieved by a door-lock device having the characteristics forming the object of claim  1 . 
     As regards the invention, the claims are an integral part of the teaching provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention will be described in detail with reference to the annexed drawings, data that are provided merely as an example and without limitation, wherein: 
         FIG. 1  is an exploded perspective view of a door-lock device according to this invention, 
         FIG. 2  is a perspective view illustrating the door-lock device of  FIG. 1  mounted on an appliance, 
         FIG. 3  is a partially sectioned perspective view of the part indicated by the arrow III in  FIG. 2 , 
         FIG. 4  is a perspective view of the part indicated by the arrow IV in  FIG. 2 , and 
         FIGS. 5 and 5  are axial sections along the V-V line of  FIG. 2  illustrating the closing phase of the door. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , the number  10  indicates a door-lock device for appliances, in particular for dishwashers. 
     The door-lock device  10  comprises a support  12  which can be made up of injection molded plastic material. The support  12  can comprise a central part  14  and two support arms  16  extending from the central part.  14  according to a general forked configuration. The two support arms  16  carry a first pivot  18  which defines an axis of rotation A which is fixed with respect to the support  12 . The pivot.  18  can be inserted through the respective holes  20  of the support arms  15  aligned in relation to each other along the axis A, and which retain the opposite ends of the first pivot  18 . The support  12  can carry a second pivot  22  which is parallel to the first pivot  18  and inserted in holes  24  of the central part  14 . 
     The central part  14  of the support  12  can have first guidance groove  26  and a second guidance groove  23  which are orthogonally oriented with respect to the axis of rotation. A 
     The support  12  can comprise two guidance portions  30  having their respective seats  32  orthogonally oriented to the axis of rotation A. The guidance portions  30  can be located adjacent to the respective support arms  16  and on the inside with respect to the support arms  16 . The central part  14 , the support arms  15  and the guidance portions  30  of the support  12  can be formed in one sole piece, for example, of injection molded plastic material. 
     The door lock device  10  comprises a lock wheel  34  rotationally carried by the support  12  around the axis A. The lock wheel  34  comprises a hub  35  and a plurality of locking arms  38  radially protruding from the hub  35 . The hub  36  has a hole  40  through which the first pivot  18  extends. The hub  36  and the locking arms  38  can be formed in one sole piece, for example, of injection molded plastic material or of zinc alloy (for example, zamak). The locking arms  38  can be equidistantly arranged from one another, at an angle. In one or more embodiments, four locking arms  38 , equidistantly arranged from one another at an angle of 90°, can be foreseen, 
     With reference to  FIGS. 3 and 4 , each locking arm  38  can have a radial stop surface  42  and a head having a circumferential protrusion  44 . 
     The hub  36  can have two elongated sections in the direction of the axis A, located on opposite sides with respect to the locking arms  38 . Each section of the hub  36  has an external cam surface, with a plurality of retention surfaces  46  which are identical to one another and spaced at an angle to one another around the axis A. The number of retention surfaces  46  can be equal to the number of the locking arms  38 . 
     The lock wheel  34  can be rotated around the axis A, allowing for an angular extension greater than 360°. The lock device  10  comprises at least one retention element to hold the lock wheel  34  in a locking position. With reference to  FIG. 1 , in the illustrated embodiment, the door-lock device  10  comprises two retention elements  48  which cooperate with respective sections of the hub  36 . The retention elements  48  are housed within their respective seats  32  of the guidance portions  30  of the support  12  and are movable with reference to the support  12  in a direction that is orthogonal with respect to the axis of rotation A. The retention elements  48  cooperate with respective helical springs  50 , under compression, which press the retention elements  48  against the respective sections of the hub  36 . The retention elements  48  have head surfaces  52  which can have a form which is complementary to that of the retention surfaces  46  of the hub  36 . As illustrated in  FIG. 4 , each retention element  49  is housed in a respective seat  32  of the respective guidance portion  30  in a sliding manner along a direction that is orthogonal to the axis of rotation A. The head surface  52  of each retention element  48  is pressed into contact with the respective section of the hub  36 . Each helical spring  50 , under compression, is housed in a respective seat  32  and is arranged between a rear wall of the seat  32  and an inside wall of the retention element  48 . The helical springs  50  elastically press the retention elements  48  in contact with one of the retention surfaces  46  of the hub  36 . The elastic force of the springs  50  retains the lock wheel  34  in a set position. In order to make the lock wheel  34  rotate around the axis A, it is necessary to apply a torque to the wheel that is sufficient to make the retention elements  48  retract into their respective seats  32  against the force of the springs  50 . The shape of the retention surfaces  46  can be asymmetrical in such a way that the necessary torque to make the lock wheel  34  rotate in an unlock direction (clockwise direction in  FIGS. 3 and 4 ) is greater than the torque necessary to make the lock wheel  34  rotate in a lock direction (counter-clockwise direction. in  FIGS. 3 and 4 ). 
     With reference to  FIGS. 1 and 3 , the door-lock device  10  can comprise a door detection indicator  54  which cooperates with a door detection switch  56 . The door detection indicator  54  is carried by the support  12  in a movable manner along a direction B which is orthogonal with respect to the axis of rotation A. The door detection indicator  54  can have a protrusion  56  which engages the first guidance groove  26  of the central part  14  and an edge  58  which engages the second guidance groove  28  of the central part  14 . The door detection indicator  54  has a eyelet  60  through which the second pivot  22  of the support  12  is inserted, in such a way to define two end positions of the door detection indicator  54  with respect to the support  12 . The door detection indicator  54  has a first end  62  which cooperates with the appliance door and a second end  64  which cooperates with a button  66  of the door detection switch  56 . The door detection indicator  54  cooperates with a helical spring  68  which tends to elastically push the door detection indicator  54  towards the appliance door. 
       FIG. 2  schematically shows the door-lock device  10  fixed to an upper cross member  70  of a dishwasher basin. The support  12  of the door-lock device  10  can be fixed to the dishwasher basin by means of a snap engagement or one with fastening screws. The means to fix the support  12  to the dishwasher basin are not shown. In  FIG. 2  the support of the door detection switch  56  is also not shown. In  FIG. 2  the door detection switch  56  is shown oriented transversally, in such a way that the door detection indicator  54  directly operates the button  66  of the switch  56 . Alternatively, the door detection switch  56  could be oriented parallel to the direction of movement of the door detection indicator  54  and, in this case, the button  56  could be operated by means of a cam. In dishwashers provided with an automatic door-opening device, the support  12  of the door-lock device  10  could be fixed to the movable element of the automatic door-opening device. 
     In  FIG. 2 , the number  72  indicates a dishwasher door that is articulated around a lower horizontal axis. The door  72  comprises a strike  74  protruding from an upper edge  76  of the door  72 . 
     With reference to  FIG. 5 , as the door  72  closes, the strike  74  comes into contact with the circumferential protrusion of one of the locking arms  38  of the lock wheel  34 . The movement of the strike  74  in the closing direction, indicated by the arrow C in  FIG. 5 , provokes the rotation of the lock wheel  34  around the axis A in the direction indicated by the arrow D. 
       FIG. 6  shows the door  72  in the closed position. In this position, with respect to the position of  FIG. 5 , the lock wheel  34  is rotated by an angle equal to the angular pitch between the locking arms  38 . The radial wall  42  of one of the locking arms  38  blocks the strike  74  in the closed-door position. The strike  74  in the closed-door position comes into contact with the door detection indicator  54  and pushes it towards a closed-door position in which the indicator  54  pushes the button  66  of the door detection switch  56 . In this state, the door detection switch  56  sends a signal which indicates that the door  72  is closed and locked. 
     In the configuration of  FIG. 6 , the door  72  opens in the direction indicated by the arrow H and provokes a rotation of the lock wheel  34  in the direction indicated by the arrow F. 
     The shape of the heads of the locking arms  38  is such that the force required to close the door  72  is less than the force required to open it. This because, during the closing ( FIG. 5 ), the strike  74  engages a locking arm  38  at a distance H 1  from the axis of rotation, which is greater than the distance of engagement H 2  in the opening phase ( FIG. 6 ) Moreover, the retention surfaces  46  of the hub  36  can be asymmetrical in such a way to require a lesser torque for the rotation of the lock wheel in the closing direction and a greater torque of the lock wheel  34  in the opening direction. 
     The opening and closing force can vary depending on the application, using springs  50  having different stiffness. 
     The door-lock device according to this invention can present one or more of the following advantageous elements; 
     the device has a more compact design than that of other devices that are currently on the market; 
     the device does not require a bistable floating mechanism given that the lock wheel  34  always has a locking arm in the engagement position; 
     the device uses springs under compression that have a greater lifespan and reliability than the traction springs; 
     the device has a lower number of components than that of other devices that are currently on the market. 
     Naturally, notwithstanding the basic principles, it is possible that there are variations, including considerable ones, in the construction particulars and the embodiments, when. compared to that which is described and illustrated, without however straying from the scope of protection. Said scope of protection is defined in the claims below.