Improvement in a door interlock arrangement for washing machines

Abstract: Clothes washing machine comprising a washing tub containing a drum, a door for closing said drum provided with a door interlock arrangement, said door interlock arrangement comprising an electromagnet (1), a main sliding element (4), a door catch (5), a spring (6) forcing said main sliding element back to its resting position, an inclined plane (9) of the door catch, a switch (2) actuated by said main sliding element (4), a device (10) that is electrically energized during spin-extraction phases only, a peg (11) projecting from said device (10) when the latter is energized and retracting into said device (10) when the latter is not energized, a recess (12) for accomodating said projecting peg (11) in said main sliding element (4), wherein said main sliding element (4) also comprises a recess (8) for accomodating the door catch (5), and a secondary sliding element (3) is provided so as to be able to slide transversally with respect to said main sliding element (4), and a spring (7) acts upon said secondary sliding element (3), and an upper edge (13) of the main sliding element (4) is capable of cooperating by interference with a downward projection (14) of the secondary sliding element (3).

Description: This invention relates to clothes washing machines in general, and front-loading clothes washing machines in particular, which are equipped with a particular, improved type of door interlock arrangement as a safety provision. Household-type clothes washing machines are known to be equipped with different types of variously featured door interlock arrangements, wherein such door interlock systems can be grouped into one of the following categories according to their operating principle: 1) Devices keeping the door locked throughout the washing process and allowing delayed (ie. after 1 to 2 minutes) door release with respect to the actual moment in which the machine is de-energized upon completing its duty cycle. This type of safety door interlock arrangement is effective in protecting the user against his/her being able to gain access to dangerously moving parts, ie. parts rotating at dangerous speeds, such as during the spin-extraction phase of the process; it is further effective in preventing the user from unduly opening the loading door of the machine even in the remaining portions of the washing cycle in the case of a faulty condition arising in washing machines equipped with an electronically controlled driving motor. However, this type of safety door interlock arrangement has two major drawbacks: the first one is related to the fact that it forces the user to wait a couple of minutes each time that he/she wants for any reason to open the loading door of the machine during the washing cycle, even during phases thereof that do not involve dangerous rotating speeds of the drum. The second drawback is apparent when the main on-off switch of the washing machine is switched on and the loading door of the same machine is open. Under such conditions, in fact, the washing machine would readily start operating as soon as its door is closed, thereby activating the process phase that is in that very moment set on the programme selector switch and causing the loading door to be locked under the action of the door interlock device itself. Such a door closure under the above mentioned conditions may obviously occur in a fully unintentional way and, as a consequence, may give rise to accidents with serious damages not only to things, but also to children and animals that may have accidentally climbed into the drum of the washing machine when the loading door was open and the drum was standing still. 2) Devices keeping the door locked only when the drum rotates at dangerous speeds, ie. during spin-extraction phases, with provision allowing for delayed door release after de-energization of the machine. Such safety door interlock arrangements are only effective in protecting the user against accidents caused by undue door openings during spin-extraction phases (since no dangerous rotating speed is involved in the other phases of the cycle) and have the advantage of allowing the loading door to be readily opened in all other phases of the washing process. They however have a major drawback in that they practically still enable accidents of the type described as the second major drawback under 1) above to occur. 3) Devices keeping the door locked through the action of an electromagnet. These door interlock devices enable the loading door of the washing machine to be opened during any phase of the washing process in which the drum is not rotating at any dangerous speed. When on the contrary the drum is rotating at a dangerous speed, there are further devices provided inside the machine to prevent the door interlock arrangement from becoming de-energized due to normal handling by the user and, as a consequence, the loading door from being opened. However, such a type of door interlock arrangements has a third major drawback in that, if the solenoid, or coil, of the interlock device happens to be de-energized due to any faulty condition or by accident, the washing machine remains electrically energized and, therefore, enabled to keep performing all phases provided for by the washing process being carried on (including those involving dangerous operating conditions), while the door can be opened at any moment. It therefore would be desirable, and it actually is an object of the present invention, to provide a clothes washing machine equipped with a door interlock device which is capable to act so as to keep the door locked, under delayed release, only when phases involving dangerous rotation speeds of the drum are being carried out, while making it possible to readily open the door during the remaining phases of the washing process, thereby doing away with one of the afore cited drawbacks. Such a door interlock arrangement should furthermore be arranged so as to be capable of making it impossible to close the door when the washing machine is already energized, ie. the power supply has been switched on, in order to prevent it from being started unintentionally, thereby doing away with another drawback among the afore cited ones. It should also be further provided with a switch means that is operatively linked with the core of the electromagnet, ie. is dependent on the position thereof, so that the core, should the coil become de-energized following an interruption of its circuitry owing to the occurrence of a failure or breakdown, will at the same time be able to cause the contacts of said switch means to separate, ie. to break, when sliding back to the position it has when the electromagnet is in its de-energized state. Under the circumstance, the switch means will in turn switch off the whole machine and in this way protect the user against dangerous conditions, thereby doing away also with the third one among the afore cited drawbacks. Such a door interlock arrangement shall further be of simple and cost-effective construction, reliable operation, and shall make use of normally available manufacturing techniques. These and further aims are reached in a clothes washing machine provided with a door interlock arrangement as substantially described in the appended claims. In order to let it be more clearly understood, the invention will be further described by way of non-limiting example with reference to the accompanying drawings, in which: Figure 1 is a schematical view of a door interlock arrangement according to the present invention, in the condition in which the washing machine is not energized and the loading door is open; Figure 2 is a view showing the door interlock arrangement of Figure 1, in the condition in which the loading door is closed, while the machine is not yet energized; Figure 3 is a view showing the door interlock arrangement of Figure 1 in the condition in which the loading door is closed, the washing machine is energized and a spin-extraction phase is going on; Figure 4 is a view showing the door interlock arrangement of Figure 1 in the condition in which the washing machine is energized and an attempt is being made to close the loading door. In each one of the above mentioned Figures, the right-side portion thereof shows a cutaway view of the drawing on the left side (European projection). The devised solution according to the present invention essentially involves providing a door interlock arrangement with two sliding elements, of which the first sliding element co-operates with an appropriate recess to stop the movement of the door locking catch and the second sliding element blocks said door catch in the opposite direction with respect to said movement, wherein said first sliding element is being prevented from sliding by a peg as controlled by the electric circuit of the washing machine. Referring now to the Figures, following component parts of the door locking arrangement according to the present invention can be noticed: 1 - Electromagnet 2 - Switch means connected in series with the power supply the drum driving motor, and actuated by the sliding element 4 3 - Secondary sliding element that slides in a vertical direction (with respect to the Figures, and not in an absolute sense, since the arrangement itself can be made according to different embodiment forms and be positioned in different ways) 4 - Main sliding element that slides in a horizontal direction (with respect to the Figures, and not in an absolute sense, since the arrangement itself can be made according to different embodiment forms and be positioned in different ways) 5 - Door catch. This door catch moves by sliding from right to left, with reference to the Figures, when the door is being closed 6 - Spring that forces back the main sliding element into its resting position (when the machine is de-energized and the loading door is open). Such a spring is normally relieved and is loaded by compression when the electromagnet 1 is energized 7 - Spring that forces back the secondary sliding element into its resting position. Such a spring is normally relieved and is compression-loaded to act against the structure of the door interlock device when the inclined plane 9 of the door catch 5 comes into contact with the secondary element 3, thereby lifting it and compressing said spring 8 - Recess through which the door catch 5 enters into the sliding element 4 9 - Inclined plane of the door catch 5 10 - Device that is energized electrically during spin-extraction phases only, so as to cause the peg 11 to jut out 11 - Peg. It recedes approx. 1 minute after the device 10 has been de-energized 12 - Recess through which the peg 11 enters into the sliding element 4 13 - Left-side upper edge of the sliding element 4 14 - Downward projection of the sliding element 3 15 - Downward projection of the door catch 5 The operation of the described door interlock arrangement is as follows: A = Resting state (see Figure 1). Washing machine de-energized, loading door open: electromagnet 1 in its resting state (not energized); switch means 2 with open contacts, in series with the drum driving motor power supply; sliding element 3 in its lowered position sliding element 4 in such a position as to let the recess 8 enable the door catch 5 to slide thereinto. B - Energization Loading door is closed while the machine is de-energized: After loading the clothes into the drum, the loading door of the washing machine is closed and the door catch 5 slides into the recess 8 (by moving from right to left when looking the right-side portion of Figure 2). When entering in such a way into said recess, the door catch 5, through the inclined plane 9, displaces the sliding element 3 upwards so as to enable the sliding element 4 to move leftwards as it is attracted by the electromagnet 1. The washing machine is switched on and the electromag_ net 1 is energized automatically. As a consequence, the sliding element 4 is attracted to move leftwards, thereby causing the contacts of the switch means 2 to close (see Figure 3). With the arrangement in this setting, the door catch 5 can no longer be retracted, since its lower downward projection 15 is now interfering with the new position of the sliding element 4. C = Normal operation During the normal operation of the washing machine, the loading door thereof can only be opened readily if the washload-holding drum is not rotating at a high speed, ie. the machine is not performing spin-extraction. As a matter of fact, it is only during a spin-extraction phase that the device 10 is energized by an appropriate electrical circuit, thereby causing the peg 11 to jut out and set down on the edge of an appropriately provided recess 12 of the sliding element 4 so as to prevent the latter from sliding back for a period of approx. 1 minute or, anyway, for a pre-determined period of time after the subsequent de-energization of the electromagnet 1. This is effective in preventing the loading door from being opened during said pre-determined period of time starting from the moment at which the power supply is switched off and the washing machine de-energized, the drum slowing progressively down from a "dangerous" rotating speed (spin-extraction) to a full standstill state in said period of time. Such a safety provision, ie. the delayed door lock release, is a standard requirement. Once this safety period of time is elapsed, the peg 11 is retracted automatically, thereby enabling the sliding element 4 to move back rightwards under the action of the spring 6. This practically causes the sliding member 4 to be displaced into such a position as to move the recess 8 in correspondence of the door catch 5, thereby enabling said door catch 5 to be withdrawn and, as a consequence, the loading door to be opened. D - Loading door is closed during operation, ie. when the washing machine is already energized or operating In the state in which the washing machine is regularly energized while its loading door is open, the electromagnet 1 automatically attracts the sliding element 4 to move towards said electromagnet. In moving leftwards, said sliding element 4 is unable to reach its outer position to its left side, since it is stopped with its edge 13 by the downward projection 14 of the sliding element 3, which lies still in its resting position, ie. in its lowered condition (see Figure 4). When an attempt is made to close the loading door, the door catch 5 (which moves along a fixed path, as constrained by the trajectory described by the closing door) will strike against the sliding element 4, since the recess 8 has been displaced to the left by the attracting action of the electromagnet 1, so that the door catch 5 cannot get into it. The loading door is in this way prevented from getting closed through a simple action, thereby assuring at the same time compliance with a definite standard requirement. It will of course be appreciated that each washing machine may be equipped with a door interlock arrangement that is embodied in any different form as considered to be appropriate without departing from the scope of the present invention. In particular, the described sliding elements may consists of appropriate elements that are able to move according to various methods, and in various ways, by translation, rotation or a combination thereof.

Claims: Washing machine comprising a washing tub containing a rotating drum, a door for closing said drum provided with a door interlock arrangement, said door interlock arrangement comprising an electromagnet (1), a main sliding element (4), a door catch (5), a spring means (6) that forces said main sliding element back into its resting position, an inclined plane (9) of said door catch, a switch means (2) actuated by said sliding element (4), a device (10) that is electrically energized during spin-extraction phases only, a peg (11) that extends out of said device (10) when the latter is energized and recedes in said device (10) when the latter is de-energized, a recess (12) for letting said projecting peg (11) into said main sliding element (4), characterized in that said main sliding element (4) also comprises a recess (8) for accomodating the door catch (5); that a secondary sliding element (3) is provided so as to be capable of sliding transversally with respect to said main sliding element (4); that a spring means (7) is provided to act upon said secondary sliding element (3); that an upper edge (13) of said main sliding element (4) is capable of interfering with a downward projection (14) of said secondary sliding element (3). Washing machine according to claim 1, characterized in that said switch means (2) is connected in series with the power supply circuit of the machine and in parallel with said electromagnet (1), and it is caused to close by a sliding motion of said main sliding element (4); that said sliding motion of the main sliding element occurs with the energization of the electromagnet (1); that upon the de-energization of said electromagnet, said main sliding element is biased back into its resting position by the action of the spring means (6); that said main sliding element (4) is released into sliding along its sliding path by a first position of the secondary sliding element (3), and is prevented from sliding along its sliding path by a second position of said secondary sliding element (3), wherein said first position of the secondary sliding element (3) is determined by the pushing action exerted by the inclined plane (9) of the door catch (5) against said secondary sliding element when it is inserted in the door interlock arrangement, and wherein said second position of said secondary sliding element is determined by the biasing action exerted by the spring means (7) upon said secondary sliding element when the door catch is withdrawn from the door interlock arrangement. Washing machine according to claim 2, characterized in that the door catch (5) is provided with a downward projection (15) capable of being introduced in said recess (8) of said main sliding element (4) when said sliding element is not attracted by the electromagnet (1), and capable of interfering with said main sliding element when the latter is caused to slide under the action of the electromagnet (1), so that when the loading door is open said downward projection prevents it from getting closed and, when on the contrary the loading door is closed, it prevents it from being opened. Washing machine according to claim 3, characterized in that , when the main sliding element is caused to be displaced by the attracting action of the electromagnet (1), the peg (11) projecting out of the device (10) prevents the main sliding element (4) from sliding back under the biasing action of the spring means (6) even after the electromagnet (1) is de-energized and, therefore, no longer attracting. Washing machine according to claim 4, characterized in that the electromagnet (1) is energized by the power supply to the machine being switched on, as well as by provision of the programme control device of the machine. Washing machine according to any of the preceding claims 4 or 5, characterized in that said device (10) is only energized during certain process phases, as controlled by the programme control device, and causes said peg (11) to retract only after a pre-determined period of time has elapsed since its de-energization. Washing machine according to claim 6, characterized in that said sliding elements are cursor means moving by translation.

Inventors: BOTTOSSET ROBERTO, MORI MAURIZIO, BOTTOSSET, ROBERTO, MORI, MAURIZIO
Applicants: ELECTROLUX ZANUSSI ELETTRODOME, ELECTROLUX ZANUSSI ELETTRODOMESTICI S.P.A.
Application year: 1993
Main classification: D06F37
IPC codes: D06F37