Patent Publication Number: US-2020281439-A1

Title: Resettable door locking device for an electric household appliance, in particular a dishwasher, and electric household appliance provided therewith

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Italian Patent Application IT 102019000003155, filed 5 Mar. 2019 and PCT International Patent Application No. PCT/US2020/019926, filed 26 Feb. 2020, the priority documents corresponding to this invention, to which a foreign priority benefit is claimed under Title 35, United States Code, Section 119, and their entire teachings are incorporated, by reference, into this specification. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to a resettable door locking device for an electric household appliance in particular a dishwasher, and electric household appliance provided therewith. In particular, the invention relates to a door locking device that can be used even when one of its latching devices, for any reason, is incorrectly placed in the locking position already with the electric household appliance door still open. 
     Discussion of Related Art 
     EP1344486 is known for a door locking device of high simplicity and reduced size based on a rotating latching device combined with a bistable elastic mechanism which makes the latching device selectively assume two different stable positions, consisting respectively of a locking position, wherein the latching device engages, with the door closed, a hooking element, usually constituted by a U-shaped bracket, and in an unlocking position, wherein the latching device does not engage the hooking element. 
     It is also known, from DE 102007033451, a door locking device for a dishwasher wherein the hooking element, carried by the electric household appliance casing, is to be coupled with a revolving latching device carried by a support body, in turn in use, which can be positioned on the door of the electric household appliance. 
     However, many known devices, even when they are completely satisfactory, are generally bulky and those of a less modern conception are designed to be mounted with their bulkier part in the thickness of the electric household appliance door, this prevents the construction of electric household appliances with increased load capacity, which would be extremely useful, particularly in the dishwasher field, and the creation of thin doors. 
     In addition, in known door-locking devices, if the rotating latching device is accidentally positioned in the locking position when the electric household appliance door is still open, on the one hand it is impossible to lock the door correctly and, on the other hand, the microswitch signal of locked door, which cooperates directly with the rotating latching device or with an element associated with it, mistakenly provides a locked door signal to the electric household appliance, which can therefore be started with the consequent risk of fluid leakage to the outside. 
     Even if the user then detects the incorrect positioning of the rotating latching device, he/she should fit/reset it manually, making it rotate to the unlocked position. In order to do this, dedicated tools are indispensable, without which there is a risk for the user to get hands or fingers injured, albeit slightly. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a door locking device for an electrical household appliance, in particular a dishwasher, which is constructively simple, of reduced cost and dimensions and of high reliability and which allows to overcome the drawbacks of the prior art, in particular that allows to report any abnormal positioning of the latching device and to fit/reset the device automatically, without a manual intervention by the user. 
     Therefore, this invention relates to a resettable door locking device for an electrical household appliance, in particular a dishwasher, and to an electrical household appliance equipped with such a device, as defined in the annexed claims. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       Further characteristics and advantages of this invention will become clear from the description which is given below of a preferred embodiment, illustrated purely by way of non-limiting example and with reference to the attached drawings, wherein: 
         FIG. 1  illustrates schematically a three-quarter rear perspective view of a door locking device according to the invention applied on an electric household appliance, known and shown in broken lines only partly and only schematically for simplicity; 
         FIG. 2  illustrates schematically a three-quarter perspective view taken sideways and sectioned according to a plane II-II of the door locking device of  FIG. 1  represented in a first operating position; 
         FIG. 3  illustrates schematically the same perspective and sectioned view of  FIG. 2 , with the door locking device of the invention represented in a second operating position; 
         FIGS. 4 and 5  illustrate schematically the same perspective and sectioned view of  FIG. 2 , with the door locking device of the invention represented, respectively, in a third and fourth operating position; 
         FIGS. 6, 7 and 8  illustrate schematically the same perspective and sectioned view of  FIG. 2 , with the door locking device of the invention represented in a sequence of operating positions that show its automatic fit/reset sequence; 
         FIG. 9 , illustrates a sectioned and exploded perspective view of the door locking device of the invention; and 
         FIG. 10  illustrates an elevated and sectioned side view of the device of  FIG. 1  in a configuration immediately preceding that illustrated in  FIG. 6 . 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1 to 5  and  FIGS. 9 and 10, 1  indicates as a whole a door locking device for an electric household appliance  2 , in particular a dishwasher, of which the electric household appliance is illustrated for simplicity only part of a structural element  3 , in this particular instance, a front upper crosspiece of a casing of the electric household appliance delimiting an upper edge of an access compartment to a washing chamber or tub  4  closed in use by a closing door  5 . 
     Although the following non-limiting description refers to the case of a dishwasher with front door, it remains clear that the door locking device  1  according to the invention can be applied both to doors with horizontal rotation axis and to doors with vertical rotation axis. Therefore, the invention can also be used on drawer dishwasher machines. 
     The door locking device  1  comprises a support body  6  configured to be fixed in a known way to the door  5  of the electric household appliance  2 , a bracket  7 , for example U-shaped or frame-shaped, and configured to be fixed in a known way to the structural element  3  and a latching device  8  carried by the support body  6  and configured to cooperate in use with the bracket  7 , in the manner that will be illustrated later. 
     The latching device  8  in turn comprises a locking tooth  10  carried by the support body  6  and constrained to the support body  6  so as to be able to rotate relatively thereto around a first A axis ( FIGS. 2 and 9 ) and, at the same time, according to an aspect of the invention, so that the first A axis can, as will be illustrated later, translate relatively to the support body  6 . 
     The locking tooth  10  comprises a first hook-shaped end  12 , configured to couple with a transversal element  11  of the bracket  7  to lock in use, in a known way, the door  5  against the structural element  3  of the electric household appliance  1 . 
     The latching device  8  further comprises a stem  13  carried by the support body  6  sliding along a symmetry B axis ( FIG. 9 ) of the stem  13  itself and cooperating with a second end  14  of the locking tooth  10 , opposite the end  12 . 
     Furthermore, the end  14  is delimited by a first cam profile  15  which cooperates in contact with a second cam profile  16  obtained on a head  17  of the stem  13  facing the locking tooth  10 . 
     In combination with the foregoing, the latching device  8  also includes, in addition to the stem  13  and the respective cam profiles  15 ,  16 , a compression spring  18 , in the non-limiting example illustrated a helical spring, operatively associated with the stem  13  and configured to thrust cam profiles  15  and  16  into contact with each other. 
     Here and below, by “compression spring” is intended an elastically deformable spring configured/mounted so as to be subjected, both at rest and during its operation, to only compression stresses. 
     According to an aspect of the invention, the latching device  8  finally comprises a frame-shaped tilting element  19 , in the illustrated example configured as a substantially quadrangular frame, and hinged to the support body  6  so as to be able to rotate relatively thereto around a second C axis parallel to the first A axis; in addition, the tilting element  19  is configured to cooperate with the transversal element  11  of the bracket  7  regardless of the locking tooth  10 . 
     In fact, the tilting element  19  is mounted externally on the support body  6  to which it is hinged around the C axis in a distal and independent position of the A axis and has opposite ends  20 ,  21  ( FIG. 9 ) defined by crosspieces of the tilting frame element  19  which are parallel to the transversal element  11  of the bracket  7  and are arranged, respectively, the end  20  on the part of the end  12  of the tooth  10 , adjacent thereto, and the end  21  on the part of the stem  13 , adjacent to a seat  22  ( FIG. 1 ) for a known microswitch  23  carried externally jointly and severally by the support body  6 , preferably obtained integrally as a piece therewith. 
     According to an aspect of the invention, the cam profiles  15 ,  16  are configured to form, together with the locking tooth  10 , the support body  6 , to the stem  13  and to the compression spring  18 , a bistable mechanism  24  ( FIG. 2 ) adapted to selectively causing the locking tooth  10  to assume a receiving position, shown in  FIGS. 2 and 3 , and a locking position, shown in  FIG. 5 . 
     In the receiving position, a recess  25  obtained in the first end  12  of the locking tooth  10  is directed in parallel to respective longitudinal side members  26  of the bracket  7 , perpendicular to the transversal element  11  of the bracket  7 , to receive the transversal element  7  inside it. 
     Furthermore, the support body  6  has a reception slit  27  ( FIG. 9 ) for the bracket  7 , arranged facing the locking tooth  10  and configured to be crossed through, in use, by the bracket  7  on the side of the transversal element  11  thereof to reach the locking tooth  10 . 
     In the receiving position, the tooth  10  has the recess  25  facing towards, and faces, the slit  27 ; the end  20  or crosspiece of the frame-shaped tilting element  19  also faces, and faces the, slit  27 . The end  20  also has a central portion  29  shaped like a C ( FIG. 9 ) which, in the receiving position of the tooth  10 , is arranged astride the end  12  of the tooth  10  and flanks the recess  25  on opposite sides, facing the transversal element  11  of the bracket  7  together with the recess  25  thereof. The conformation of the tilting element  19  is in any case such as to avoid any interference and/or cooperation with the locking tooth  10 . 
     In the locking position, instead, the recess  25  is directed transversely to the side members  26  of the bracket  7  and is arranged substantially perpendicular, or at least transversely, to the slit  27  ( FIG. 5 ). 
     Preferably, the head  17  of the stem  13  is hinged to an arm  30 , for example shaped like a fork ( FIG. 9 ), which in the illustrated non-limiting example protrudes overhanging from the second end  14  of the locking tooth  10 , perpendicular to the A axis, and which is obtained integrally in one piece with the end  14 , so that the head  17  of the stem  13  rotates in use relatively to the arm  30  around a third D axis ( FIG. 9 ), parallel to the first A axis. Obviously, the arm  30  could be missing or be integrated into the end  14  which in this case would preferably be fork-shaped. Other possible configurations, obvious to the person skilled in the art, are anyhow possible. 
     In the non-limiting but illustrated preferred example, the support body  6  comprises a hollow boxed portion  31  ( FIG. 9 ) housing internally the stem  13 , the compression spring  18  and the locking tooth  10 , with the exception of the end  12  of the latter, which protrudes overhanging from the support body  6  through a slit  32  ( FIGS. 1 and 9 ) of the boxed portion  31 . 
     The first A axis is defined by a pair of profiled elements  33  ( FIGS. 9 and 10 ) which protrude overhanging transversely from opposite sides of the locking tooth  10  and which are arranged between the ends  12  and  14  thereof. 
     The laterally protruded overhanging profiled elements  33  cooperate in contact with a radially internal perimeter edge  34  ( FIG. 9 ) of the boxed portion  31  of the support body  6  and the compression spring  18  is configured to keep the laterally protruded overhanging profiled elements  33  of the locking tooth  10  permanently in contact with the radially internal perimeter edge  34  of the boxed portion  31  of the support body  6 , so that the first A axis defined by the profiled elements  33  can translate relatively to the support body  6  along the profile of the perimeter edge  34 . 
     In particular, the radially internal perimeter edge  34  of the boxed portion  31  of the support body  6  forms a loop  35  ( FIGS. 6 and 7 ) configured to receive the laterally overhanging profiled elements  33  of the locking tooth  10  and within which the profiled elements  33  are normally kept by the compression spring  18 , which is pre-loaded, so as to be free to rotate relatively to the support body  6  within the loop  35  between the aforementioned receiving and locking positions. 
     The lateral protruding overhanging profiled elements  33  of the locking tooth  10 , instead of being simple pins, are also preferably shaped as rounded wedges or, anyhow, configured to cooperate selectively with respective portions of the radially internal perimeter edge  34  of the boxed portion  31  immediately adjacent, from opposite sides, to the loop  35 , to act as end stops to determine the angular position of the receiving and locking positions of the locking tooth  10  with respect to the support body  6 . 
     The stem  13  is engaged axially passing through a shoulder ring  36  ( FIGS. 2 and 9 ) hinged to the support body  6  so that the shoulder ring  36  rotates relatively to the support body  6  around a fourth E axis ( FIG. 9 ) parallel to the first A axis and preferably arranged coaxial to the second C axis. The compression spring  18  is inserted in a pack, pre-compressed, between the head  17  of the stem  13  and the shoulder ring  36 , so that it constantly thrusts the head  17  against the end  14  of the tooth  10 . 
     The recess  25  is configured to retain within it the transversal element  11  of the bracket  7  when the locking tooth  10  is in the locking position and when the recess  25  thereof has previously been engaged by the transversal element  11  of the bracket  7  with the locking tooth  10  in the receiving position (i.e. when the tooth  10  was previously in the receiving position). 
     According to a further aspect of the invention, the locking tooth  10  is delimited, between the recess  25  and the second end  14  thereof, by a plane surface  37 , obtained in a position immediately adjacent to the cam profile  15  and on the part of the recess  25 . The plane surface  37  faces towards, or on the side of, the slit  27  of the support body  6  and, in the locking position, defines an inclined plane facing the slit  27  and configured to cooperate with the transversal element  11  of the bracket  7  if the recess  25 , with the locking tooth in the locking position, had not already been engaged by the bracket  7  ( FIGS. 6 and 10 ). 
     This inclined plane defined by the surface  37  is configured to determine, as a consequence of a thrust exerted thereon by the transversal element  11  of the bracket  7 , an axial thrust on the compression spring  18 , through the stem  13 , which thrusts the first A axis to move away from the slit  27  to allow the transversal element  11  of the bracket  7  to “jump” the locking tooth  10  and snap-fit with the recess  25  thereof ( FIG. 7 ). 
     The operation of the described door locking device  1  is as follows. 
     With the door  5  open, the device  1  is in the configuration of  FIGS. 1 and 2 , wherein the tooth  10  is in the receiving position, which is one of the two stable positions allowed by the bistable mechanism  24 . This position is stable, since the elastic thrust exerted by the spring  18  is discharged to the left (in the Figures) of the A axis, retaining the profiled elements  33  pressure supported inside/against the loop  35  ( FIG. 2 ). 
     When the door  5  closes, the bracket  7  receives the slit  27 , the transversal element  11  is supported against the end  12  of the tooth  10 , up to inside the recess  25  ( FIGS. 3 and 4 ). The thrust of the bracket  7  is eccentric with respect to the A axis and therefore forces the tooth  10  to rotate around the A axis, on the hinge defined by the loop  35  and the profiled elements  33 ; consequently also the end  14  rotates and the cam profiles  15 ,  16  rotate on the E axis the stem  13  and the shoulder ring  36 , further compressing the spring  18  ( FIGS. 4 and 5 ) until the B axis exceeds the alignment position of the A axis, defined by the loop  35 , and the E axis, and moves to the right thereof in the Figures, triggering the mechanism  24  in a new stable position, bringing the tooth  10  into the locking position ( FIG. 5 ). 
     In this position the recess  25  is rotated by about 90°, and therefore engages the transversal element  11  so that it can no longer be extracted through the slit  27 . The elastic pre-load of the spring  18  also keeps the door  5  compressed in the closed position. 
     During the described movement, the tilting element  19  is also rotated by the thrust of the transversal element  11  on the C axis, bringing the end  21  against the microswitch  23 , which is activated, signaling the status of closed and locked door. 
     In the opening phase, an opposite movement takes place; starting from the configuration in  FIG. 5 . The user, in this case, to open the door  5  must exert a pull on the door handle. The transversal element  11  which engages the recess  25  urges the end  12  to rotate towards the slit  27 ; the tooth  10  rotates on the A axis producing the compression of the spring  18  and the bistable mechanism  24  snaps towards the position of  FIG. 3 , passing through a configuration wherein, during the opening phase, the crosspiece  11  of the bracket  7  is placed next to the tooth adjacent to the inclined plane  37 , while the profiled elements  33  remain engaged in the loop  35 , due to the thrust of the spring  18 , so that the A axis does not translate but the tooth  10  rotates around the A axis, which remains stationary. Once the position of  FIG. 3  is reached, the bracket  7  can be extracted from the slit  27  and return to the starting position of  FIGS. 1 and 2 , with the door  5  open. 
     During these opening movements, the microswitch  23  is disconnected since the tilting element  19  is rotated in the inverted direction either by the thrust of the microswitch  23  thereof (which is internally equipped with a spring) or by a specially provided spring (not shown) for example on the C axis, following the backward movement of the transversal element  11  with the end  20  thereof. 
     With specific reference to  FIGS. 6 to 8 and 10 , the tooth  10  could accidentally find itself already in the locking position, while the door  5  is open ( FIG. 10 ). In this case, the door locking device  1  is able to reset itself automatically without manual intervention by the user. 
     Firstly, the user is informed of the anomaly in the event that the door  5  is half-closed, but not locked, since even if the tooth  10  is in the locking position, the absence of the bracket  7  within the slit  27  does not cause the rotation of the tilting element  19  and therefore does not activate the microswitch  23 . 
     Secondly, by thrusting the door  5  towards the closed position, the user thrusts the bracket  7  into the slit  27 . The tooth  10  is in the locking position. This implies that the inclined plane defined by the plane surface  37  faces the slit  27  and therefore intercepts the transversal element  11  of the bracket  7 , which begins to slide along the inclined plane  37  while the door  5  progressively approaches the closed position. 
     This movement involves an axial thrust against the stem  13  which compresses the spring  18 , but the B axis remains to the left of the rotation A axis of the tooth  10 . 
     Therefore, the tooth  10  is pushed to move away from the slit  27  descending into the boxed portion  31  through the slit  32 , following a straight section  38  ( FIG. 9 ) of the edge  34  against which the elements  33  are thrusted by the spring  18 . 
     Consequently, the tooth  10  assumes sequentially the positions of  FIGS. 6, 7 and 8 , thanks to which the element  11  jumps the tooth  10  which is thrusted downwards and goes to engage the recess  25 . As soon as this occurs, the thrust on the inclined plane  37  ceases and under the thrust of the spring  18  the tooth  10  rises again ( FIG. 8 ) until it assumes the correct position of  FIG. 5 . 
     To mount the latching device  8  within the boxed portion  31  it is possible to obtain the support body  6  by means of a single block. Thanks to the elasticity of the thermoplastic material and the entrance  39 , it is possible to snap-fit the shoulder ring  36  and the different components of the latching device  8  described within the boxed portion  31 , in containment holes  28 ( 6 ). 
     Through the containment holes  28 , the shoulder ring  36  rotates relatively to the support body around a fourth E axis, passing through the center of the containment holes  28 . 
     Finally, from what has been described it is clear that the invention also relates to an electric household appliance  2 , in particular a dishwasher, comprising a structural element  3  delimiting an access compartment a washing chamber or tub  4  and a door  5  operatively associated with the access compartment and configured to assume an open position, wherein it allows access to the washing chamber or tub  4 , and a closed position wherein it is locked against the structural element  3 . 
     The electric household appliance  2  comprises a door locking device  1  as described having the support body  6  fixed jointly and severally to the door  5  in a known way, for example by means of screws not illustrated for simplicity, and the bracket  7  fixed jointly and severally to the structural element  3 , also in a known way and not illustrated for simplicity. 
     The support body  6  has a lateral seat  22  housing a microswitch  23  and the frame-shaped tilting element  19  is configured to cooperate with the microswitch  23  only when the transversal element  11  of the bracket  7  engages the recess  25  of the locking tooth  10 , thus warning the user in case of anomalies or in any case preventing the electric household appliance  2  from starting if the door  5  is not locked. 
     All the purposes of the invention are therefore achieved.