Device for rapid locking and delayed unlocking a door, more particularly of a washing machine

Abstract: The invention relates to a device for locking doors of machines containing rotating members which closes the contacts of an electrical switch subsequent to locking the door and opens the contacts prior to unlocking the door. It is characterized by the fact that hook 5 of the door is retained by a block 4 which is rotated about its axis due to the action of hook 5 while closing the door so that after the locking of the rotating block 4, hook 5 can no longer be drawn out. Rotating block 4 is fixed on a small shaft 3 with which it rotates, said small shaft 3 having in turn a second substantially cylindrical block 7 which has a peripheral surface shaped as a cam and which has in the end opposite the first block 4 a cavity 8 to house the tail 27 of a locking bolt 9 which moves parallel to the axis of said small shaft 3, the opposite end 26 of locking bolt 9 working on the moving contact 10 of the electrical switch 11. When the end of locking bolt 27 enters the cavity 8 it locks block 7 and therefore block 4 against rotation, thereby locking the door. The operation of the various parts of the device is obtained by means of two mobile boxes moving parallel to the axis of the shaft 3, of which one 14 cooperates with cam 7 arranged on shaft 3 and the other 13 cooperates with the front part 29 of locking bolt 9 and with a lever arm 19 rotating about a pivot 20 with the opposite end connected to a small piston 22 of an electromagnet 23.

Description: This invention in general lies in the field of locking systems of closing means of doors of machines containing parts subjected to inertial rotation, and in particular it refers to locking systems of washing machine doors which, when working with electromechanical programmers, aim at locking the closing device of the machine door when the machine is started up and unlocking it with a certain delay after the electric current has been cut off to the moving parts of the machine so as to avoid the opening of the door when certain parts of the machine may still be subjected to inertial rotation (in particular the drum of the centrifuge). Other devices are known in the field, of the type in which the locking and the respective delayed opening is obtained through the effect of the action of a bimetallic strip and of the cooling time of the same. In the field are also known various other devices, some of which belonging to the same inventor, capable of accomplishing the cited functions using other means: magnetic, wax thermostats etc. Technical progress in this field and the availability of washing machines that are more and more sophisticated, have induced producers of said machines to replace the mechanical programmer with a microprocessor onto which are set the various possible working cycles. In this case it is no longer necessary for the locking device of the closing means of the door to incorporate in itself the means for the delayed unlocking, since the microprocessor accomplices this function, nor is it necessary for the said closing means of the door to be locked immediately after the beginning of operation since it can be locked only when the machine works at certain cycles when an unintentional opening of the door may cause damage to the user, thus limiting the locking of the door to centrifruging operations which as we know, in modern machines occur at high speed. One such device is described in the Italian Patent Application No.22439 A/89 belonging to the same inventor. In all of these known devices however, it is possible to turn on the machine without the the door being locked because the locking occurs when the series switch is closed or immediately after, since it is the series switch that allows the current to flow to the programming and driving means of the machine, it is sufficient to close the door either deliberately or accidentally to activate said series switch. German Patent DE-B-2.942.515 described a device similar to that of this Application in which the hook is locked after the closing of the door and opening by means of a magnet, but in the case of Patent DE-B-2.942.515 the whole force of opening of the hook and the simultaneous force of closing of the switch are exerted by the magnet. Contrary to this, because of the particular composition of the constituent parts of this invention, the magnet has to exert a very limited force to open, in particular only the force required to overcome the attrition of the parts in contact, with a substantial reduction in its dimensions and its cost. The first aim of this invention is to eliminate said inconvenience and exclude any possible, or even deliberate, tampering with the device guaranteeing maximum safety, offering a locking device which is basically mechanical in which the contacts of the series switch are closed only after the door has been securely closed; the second aim of the invention is that of presenting an extremely simple device which also guarantees lasting and safe functioning; the third aim is that of the automatic opening of the door occuring simultaneously to the unlocking; the fourth aim is that, with the addition of a device on the feed circuit of the current to the power supply of the locking device, its use can be extended to operate on machines working with traditional electromechanical programmers. The invention consists in using: as a retainer for the hook of the door, a block which swings around its axis due to the action of hook while closing the door, so that after the locking of the swinging block hook can no longer be drawn out; said swinging block is fixed on a small shaft with which it rotates, said small shaft having in turn a second substantially cylindrical block which has a peripheral surface shaped as a cam and which has, in the end opposite to the first block, a cavity to house the tail of a locking bolt which moves parallel to the axis of said small shaft, under the action of the spring, the opposite end of the locking bolt working on the moving contact of the series switch, so that when the tail of the locking bolt is inserted in the cavity it locks cam and therefore block against rotation, thereby locking hook. The operation of the various parts of the device is obtained by means of two mobile slide boxes moving according to the axis of the shaft, of which one cooperates with the cam arranged on shaft and the other cooperates with the front part of locking bolt and with a lever arm rotating around a pivot, with a tooth facing tooth of the slide box and the opposite end connected to a small piston of an electromagnet. The invention will be better understood with the description of an embodiment to be taken as being exemplifying and not limitative, illustrated with reference to the enclosed drawings in which: Fig. 1 - represents the device turned off, that is with the door open seen as a flat cross section. Fig. 2 - a section according to B-B of fig. 1 representing the hook of the door and the locking block of the hook with the door open. Fig. 3 - a section according to A-A of fig. 1 representing the two boxes responsible for the movement of the various parts of the device and the drive cam of the same when the device is open. Fig. 4 - represents the device when locked, that is with the door closed and hook locked in a flat section view. Fig. 5 - a section according to B-B of fig. 4 representing the hook of the door, and the locking block of the hook with the door closed. Fig. 6 - a section according to A-A of fig. 4 representing the two boxes responsible for the movement of the various parts of the device and the driving cam of the same when device is closed. Fig. 7 - represents how the device works during unlocking that is as it occurs when the contacts of the series switch are opened the unlocking of the door. Fig. 8 - a section according to B-B of fig. 7 showing how the hook continues to stay locked for some time after the contacts of the series switch are opened; Fig. 9 - a section according to A-A of fig. 7 showing the reciprocal position of the two boxes of movement. Furthermore, in two successive drawings is illustrated a variation of the invention that is, how said device can be applied also to washing machines with electromechanical programmer applying a component to the device according to the invention, and using a particular wiring diagram. Fig. 10 - the device in locking position with the component allowing it to be applied to washing machines with electromechanical programmer. Fig. 11 - the relative electric wiring diagram for the working of the device according to the variation of fig. 10. With reference to figs. 1,2,3,4,5,5,7,8 and 9, the device according to invention 1 is made up by an external box shaped casing 2 provided with a lid, not illustrated, to contain the various parts of the device consisting in: a shaft 3, arranged according to the longitudinal axis of the external casing 2, free to rotate around its longitudinal axis and arranged in a cylindrical housing 12 obtained in the casing and in the corresponding part in the lid; a gauge block 4 properly shaped to join with the hook of the door 5 of the washing machine, so as to lock it for example as indicated in fig. 2,5,8 fixed on shaft 3. Said stop gauge block 4 is substantially a cylinder which presents inside it a cavity 6 fit to join with the stop tooth of the hook 5 so that when the block 4 is locked in the position of fig. 4 and 5, the hook cannot be drawn out and the relative door opened; a second cylindrical block which has a peripheral surface shaped as a cam 7, also fixed to shaft 3 adjacent to the stop gauge block 4 of the hook. It also has, in correspondance to the side opposite to the one facing the gauge block 4, a cavity 8 to house one end 27 of a locking bolt 9 to lock hook 5 by means of stop block 4, the other end of the locking bolt 26 working on the mobile contact 10 of the series switch two slide boxes 13 and 14 containing respectively two helicoidal springs 15 and 16 free to move backwards and forwards according to the longitudinal axis of the casing 2, housed inside the casing 2 and arranged in continuation to the shaft 3 and of the relative gauge block 4 and cam 7. the slide box 14, has an end 17 shaped into an inclined plane as well as an appendix 18 which fits into box 13 and onto which rests one end of spring 15 contained in the slide box 13 which with the other end leans on the front internal wall of the slide box 13, whose corresponding external wall lies infront of the abutment 29 of the locking bolt 9 of the slide box 14 opposite to the one shaped into a inclined plane and open, so that the spring 16 contained in said slide box leans with one end against a fixed vertical surface 29' drawn out in the casing 2 and with the other end against the wall of said casing externally shaped into an inclined plane; a lever arm 19 hinged to an end 20 of the casing 2 is connected with the other end to a small piston 22 of an electromagnet 23 having in a determined position a tooth 24, which when the small piston of the electromagnet is retracted - corresponding to the device when not working, arm 19 lowered - interferes with a tooth 25 arranged in a position which corresponds to the outside part of box 13. It works as follows: with the door opened, the various parts of the device are arranged as illustrated in figs. 1,2,3 that is with the rod 3 rotated by the action of spring 16 so that the stop gauge block 4 of the hook 5 presents itself as in fig. 2 in such a position as to receive the hook; bolt 9 leans with its end 27 on the external part of the side of cam 7; slide boxes 13 and 14 are both drawn back with spring 15 relaxed and spring 16 slightly compressed enough to keep slide box 14 in an off position; the other end 25 of bolt 9 presses on the moving contact 10 of the switch 11 keeping the contacts of the same open and pressing the spring 19 of same switch; arm 19 is pulled down by return spring of the small shaft of the electromagnet 23 and with tooth 24 facing tooth 25 of the slide box 13; the inclined plane 17 of the box 14 holds up the inferior part of cam 7. When the door is closed, see figs. 4,5,6, hook 5 makes it turn to the position shown in fig. 5 by pressing on gauge block 4; with it also turns rod 3 and cam 7 which working with the diameter slowly increasing onto the inclined plane of slide box 14 pushes it forwards causing the compression of the spring 16 against the fixed wall 29' and with its arm 18 the compression of spring 15 against the front wall of slide box 13 whose tooth 25, under these circumstances is pushed with pressure against tooth 24 of arm 19 and the outside part of the front wall meets spur 29 of bolt 9. Only when the operation has been concluded can tail 27 of bolt 9 enter cavity 8 drawn out of the side wall of cam 7 due to the effect of the push exerted on end 26 of locking bolt by spring 28 of the series switch 11 and it is only under these circumstances that it is possible for the contacts of the switch 11 to close. From the above description we can deduce that even if one should involuntarily or accidentally close the door up/to but without reaching the locking position the tail of the bolt 9 will not be able to enter housing 8 and therefore make it impossible to induce the contacts of the series switch to close. To open the door, see figs. 7,8,9, it is sufficient to actuate the small piston 22 giving tension to the electromagnet 23 so that the piston 22 rises taking with it the head of the rod 19 freeing the slide box 13 which springs forward dragging forward the locking bolt 9 due to the effect of the thrust exerted by the external front wall of slide box 13 against the spur 29 of the bolt 9 so that the moving contact 10 of the series switch 11 opens and cam 7 unclamps. Almost instantly, but successively, due to the thrust exerted by the inclined plane 17 under the action of spring 16 contained in the slide box 14 and previously compressed, slide box 14 recoils causing rotation in the opposite direction of the cam 7 and therefore of gauge block 4 locking hook 5 which is pushed outside causing the automatic opening of the door, and at the same time with its arm 18 drags slide box 13 backwards allowing the lever arm 19 connected to the head of the small piston 22 of the electromagnet to be drawn downwards. It has also been found that because the particular lay out of the relationship between the arm 19 and the box 13, to make the arm 19 lift - unlocking operation - it is sufficient only to have an electromagnet much smaller in size than the ones normally used for the unlocking of similar types of door locking systems in that only a very small force is necessary to work on the lever 19 and this is a further advantage of the invention. The electromagnet 23 can be actuated manually, working on I the push button placed on the control panel of the machine, when the machine is not working or when it has reached a stage of the cycle allowing this operation, or automatically when the cycle has finished using a control accepted by the processor. With reference to fig. 10, to be able to use this type of door locking device as described above also in washing machines having the cycle controlled by an electromechanical programmer, it is sufficient - and it is also a claim of the patent - to assemble thermistor (P.T.C.) 30 on one of the two current conductors to the electromagnet 23 which, when the door is closed and series switch 11 also closes at the same time, warms up thus interrupting the flow of one of the supply conductors of the current to the electromagnet 23, so that it can be operated either manually or by a command sent by the programmer, only when the P.T.C. has cooled and the flow of the current in the conductor which was previously interrupted is restored. It has also been found that, by appropriately connecting the conductors which supply the current to the electromagnet 23, it is possible, even in washing machines with a cycle comanded by a normal mechanical programmer, to realize the locking of the hook of the door both during the whole cycle, as usually occurs in these types of programmers with known devices, or only during the centrifugal phase as shown in the operation scheme illustrated in fig. 11, in which "F" indicates wires connected to phase and "N" wires connected to neutral. With reference to fig. 11, to wire 31 is connected the phase coming from the line and which when switch 11 is closed, corresponding to as mentioned above to the closing of the door comes out from 32 to reach the electromechanical programmer and proceeds to begin the cycle. To the two faces of the P.T.C. 30 are connected, to one side a shunt 34 of phase 32, and to the other line 33 coming from the neutral wire. When P.T.C. is cold the current phase from wire 32 can pass to wire 34 so that when pressing the push-button 37 a binding clamp of which is connected to wire 36 in turn connected to neutral, it is possible actuate electromagnet 23 to open the door. When through the programmer is connected wire 33 with the neutral line at the beginning of the cycle or only at the beginning of the centrifuging phase, the P.T.C. heats up and remains heated for the whole time of said operation interrupting the continuity between wire 32 and 34 and preventing the actuation of magnet 23. Only at the end of the cycle and after the cut off of the current to wire 33, and only after the P.T.C. has cooled, is it possible to actuate the electromagnet either again using pushbutton 37 or through the transfer of the current through wire 35 connected through the wire 38 to an appropriate control provided on the programmer, to obtain the automatic opening of the door. Furthermore the P.T.C. 30 thus connected to the coil of the electromagnet also performs the function of protecting the electric winding of the same coil, in that in case of accidental prolonged feeding of electric current to the coil of the electromagnet due to damage of the programmer or of the microswitch 11, it is sufficient to induce heating of P.T.C. 30 and consequently the interruption of the current to the electromagnet 23. Finally recently it has been found that for better results we could substitute the PTC with a delaying device which has been the object of the European Application No. 88900820.7. It has been found infact that although the PTC works perfectly as mentioned above, if the distracted or impatient operator should insistently press the push-button 37, the P.T.C. will heat up and the door will lock. Fig. 12 shows a flat section of the device as described above, not working that is with tne door open. With reference to fig. 12 we find a second system which has been further improved to be able to use the door locking system object of the present invention in washing machines driven by a mechanical programmer and substituting the P.T.C. of fig. 10 on the wiring diagram of fig. 11 the delaying device described in the European Application No. 88900820.7 in which the opening is actuated by the mobile contact plate 43 of a microswitch, by means of a rocker arm 42 moved by a bi-metallic strip 40 suitably electrically heated, an appropriate part of the mobile contact plate 43 of the microswitch being, in its turn, subjected to the load of an eccentric ratchet 44, said load having the function, by increasing and decreasing, of correcting the insertion time and the delayed opening of the door-lock, the bimetallic strip being heated by means of a P.T.C. 41, and the bimetallic strip 40, the P.T.C. 41 and the rocker arm 42 simply resting on one another in order to guarantee, for these conditions, that the curving and straightening times of the bimetallic strip 40 remain stable through time.

Claims: Device for rapid locking and delayed unlocking doors of machines containing rotating members which closes the contacts of an electrical switch subsequent to locking the door and opens the contacts prior to unlocking the door, of the type in which the opening is controlled by a electromagnet, characterized by the fact that hook (5) of the door is retained by a block (4) which swings around its axis due to the action of hook (5) while closing the door, so that after the locking of the swinging block (4) hook (5) can no longer be drawn out; said swinging block (4) is fixed on a small shaft (3) with which it rotates, said small shaft (3) having in turn a second substantially cylindrical block which has a peripheral surface shaped as a cam (7) and which has, in the end opposite to the first block (4), a cavity (8) to house the tail (27) of a locking bolt (9) which moves parallel to the axis of said small shaft (3), under the action of a spring (28), the opposite end (26) of the locking bolt (9) working on the moving contact (10) of the series switch (11), so that when the tail (27) of the locking bolt (9) is inserted in the cavity (8) it locks cam (7) and therefore block (4) against rotation, thereby locking hook (5); the operation of the various parts of the device is obtained by means of two mobile slide boxes moving according to the axis of the shaft (3), of which one (14) cooperates with the cam (7) arranged on shaft (3) and the other (13) cooperates with the front part (29) of locking bolt (9) and with a lever arm (19) rotating around a pivot (20), with a tooth (24) facing tooth of the slide box (13) and the opposite end connected to a small piston (22) of an electromagnet (23). Device according to claim 1, characterized by the fact that the moving box (13) contains a spring (15) which during the locking phase is compressed by an arm (18) connected to the slide box (14) against which leans one end of the spring (15) while the other end of the spring (15) thrasts the front wall of said slide box (13). Device according to claims 1 and 2, characterized by the fact that the slide box (14) holds an inclined plane (17) on the side opposite to the cam (7) which cooperates with said cam (7) and housing a spring (16) one end of which leans against the back wall of the slide box (14) and the other leaning against a retainer (29') which is part of the container (2) of the device. Device according to claims 1, 2 and 3, characterized by the fact that during unlocking phase of the door, obtained raising with piston (22) the end (21) of the arm (19), springs (15 and 16) contained in boxes (13 and 14) when stretched out make slide boxes (13 and 14) recoil, and pushing the cam (7) stimulates rotation in the opposite direction of the block (4) of the hook (5), with the contemporary expulsion of the hook (5) from the block (4) and the consequent automatic opening of the washing machine door. Device according to claim 1 characterized by the fact that inserting a thermistor (P.T.C.) (30) onto a wire which supply the current to the electromagnet (23) the device can be applied to washing machines which have an electromechanical programmer commanding of the known type so that the P.T.C. can operate the delayed opening of the door.

Inventors: ROCCHITELLI ONOFRIO, ROCCHITELLI, ONOFRIO
Applicants: ROCCHITELLI ONOFRIO, ROCCHITELLI, ONOFRIO
Application year: 1990
Main classification: D06F37
IPC codes: E05B47, D06F37