GB2162240A

GB2162240A - Delayed-release door lock

Info

Publication number: GB2162240A
Application number: GB08515940A
Authority: GB
Inventors: Giancarlo Attena; Ciro Calenda; Giuseppe Notaro
Original assignee: Texas Instruments Italia SRL
Current assignee: Texas Instruments Italia SRL
Priority date: 1984-06-22
Filing date: 1985-06-24
Publication date: 1986-01-29
Also published as: SE8502968L; GB8515940D0; ES8700351A1; ES8706875A1; FR2566438A1; DE3521777A1; GB2162240B; ES544395A0; SE8502968D0; ES553743A0

Abstract

A delayed-release door lock, particularly for washing machines and the like comprises a bimetallic plate (4) having two different stable curved positions at different temperatures. Power to the device is supplied via terminals (1, 2); current passing through the cylinder (3) causes it to warm up and the plate to trip to its second curvature. Its moving end acts upon two pegs (X, Y) and causes a locking member (5) to rotate to a locking position. When the power is switched off, the cylinder gradually cools and the plate eventually trips back, allowing the door to be opened. The mains power supply and the door-locking functions may be separated but contained in a single unit. <IMAGE>

Description

SPECIFICATION Delayed-release door lock The present invention relates to a delayed-release door lock; that is, safety locking device for, for example, the doors of washing-machines, dish washers, and the like. The lock is of the type which allows the door to be opened only after a fixed time has elapsed after the end of (for example) a washing cycle. The device is suitable for integration with the mains power switch of the apparatus, as well as being of a simplified structure, and of high reliability, operational safety and useful life.

The basic problem addressed by the present invention is well known: the point is that of realizing a safety locking device for the doors of, for example, household electrical apparatus and appliances such as washing-machines, dish washers and the like. These often include dangerous items such as a rotating basket and, in some operating stages, they may also contain high-temperature water at a level higher than the level of the door. The device of the present invention ensures the closed state of the door during the operation of the apparatus, and allows opening of the door of the apparatus only after a sufficient time has passed after the end of the machine cycle for the rotating mass to come to rest, or for there to be no danger of hot water coming out.

The locking problem has been dealt with in the prior art by employing, for instance, a bimetallic strip which is heated by a heating member (a positive temperature coefficient cylinder or PTC pellet) through which an electric current flows, the strip acting through other intermediate members on a locking member (or pawl) which locks the slider of the door lock.

However, the conversion of the linear motion of the end of the bimetallic tripping strip into the necessarily longer linear motion of the locking member through the intermediate members involves a quite complex structure of the device itself, and consequently a higher cost, quite apart from the bulkiness of a device of such structure and the associated assembly problems.

Thus, it is one aim of the present invention to provide a locking device for the doors of, for example, washing machines, the device being of a very simple structure comprising a very low number of members and capable of giving a very high reliability.

According to the present invention, a delayed-release door lock comprises a bimetallic strip or plate member having a first curvature at a first temperature and a second curvature at a second, higher temperature; a heating device for heating the bimetallic member when the door is closed and electric current is supplied to the device; and a locking member, operatively coupled to the bimetallic member and arranged for rotational motion between a free position in which the door can be opened and a locking position in which it is locked; whereby, when current is supplied to the heating device, the temperature of the bimetallic member is increased so that this bimetallic member trips into its second curvaturestate, thereby causing the locking member to rotate to its locking position, and, when current is no longer supplied to the heating device, the bimetallic member cools and trips back to its first curvature state, after an interval, thereby causing or allowing the locking member to rotate to its free position. Preferably the bimetallic member or strip is of the preformed type, so as to have well determined bending inversion temperatures and consequently quick trip inversions. The bimetallic member may be heated in a known way by direct contact with a heating cylinder (positive temperature coefficient pellet) which forms part of the electrical circuit.

The door-locking device is preferably made up of a plastics material housing, a PTC capsule, cylinder or pellet placed within a suitable space in the housing, with one of its faces placed on an electrical terminal, a bimetallic strip or plate arranged on the other face of the cylinder, a second electrical terminal that is in contact with one of the two ends of the plate, a locking member or pawl rotatably pivoted on a pivot within the housing and coupled with the other end of the bimetallic plate so that, when the bending of the plate is inverted, the movement of one end of the plate causes the pawl to trip into rotation around the pivot from the free or rest position to an operative or locking position in which the door of the washing machine is locked.

When the working cycle of the machine is over and the electric circuit is disconnected, the bimetallic plate starts to cool and when it reaches the inversion temperature it trips back to its initial position. This causes the locking members to perform a quick rotatory motion through preferably 900 in the opposite direction so as to come back to its free position and to unlock the door of the machine.

The present invention also aims at solving the problem of realizing the independence of the safety locking function of the door of the machine and of the electric powering function of the machine itself. In all known devices of the prior art as well as in two embodiments of the present invention (to be described), the function by which the door of the machine is locked, (which is realized by means of a mechanical delay device), and the function by which the machine itself is electrically powered coincide. This has the drawback that the door remains locked during the whole working cycle, and not only during the working stages which are considered dangerous and which may represent just a minor part of the whole cycle.Thus, it would be very useful to have a device capable of making the two functions of mechanical delay and electric powering completely independent, so that the user is given the possibility of opening the door of the machine during the stages that are considered of no danger, for instance in order to introduce into the washing machine a number of garments or other articles to be washed, previously neglected or requiring a lighter washing cycle.

A further specific object of the present invention consists in the separation of these two functions, so that they operate independently of one another and the door of the machine can be locked in the desired cycle stages only; that is, when the opening of the door is actually dangerous and/or when the technical instructions explicitly require the locking of the door.

A further embodiment of the present invention, wherein the two actuators are integrated but are independent, may comprise a plastic material envelope, a PTC cylinder or pellet arranged within a suitable space in the housing, with one of its faces placed on a first electrical terminal, a bimetallic strip or plate arranged on the other face of the cylinder, a second electrical terminal contacting a first end of the plate strip, a locking member or pawl which is rotatably pivoted on a pivot within the housing and is coupled with the second end of the plate through some coupling means, so that the bending tripping inversion of the bimetallic plate causes the locking member to rotate between the locking position and the unlocking position; the embodiment also comprising a third and a fourth electrical terminal having a contact strip therebetween and being fixed to the fourth electrical terminal, and capable of tripping from a normal rest position in which the contact with the third terminal is open to an operational position in which the contact with the third terminal is closed, the embodiment also comprising a slider that is urged by a spring towards a rest position corresponding to the opening condition of the door of the machine.

When the door is closed the slider may move to an operative position in which it acts (by means of a small protruberance) on the contact strip, causing this to pass to the closing position. The slider also carries a locking indentation or aperture of its own into a position in which it may be engaged with a part of the locking member.

The contact strip may be of the elastic tripping type, i.e. of the type that has a stable rest position, and that passes from the first position to the second one as a result. of an external action, and that trips back automatically to the starting position when the external action ends.

The invention may be carried into practice in various ways and three specific embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a top view of a first embodiment of the device, the locking pawl being shown in the rest position; Figure 2 is a view similar to that shown in Figure 1, but with the pawl shown in the locking position; Figure 3 is a side view of the device, the pawl being shown in the rest position; Figure 4 is a similar view of Figure 3 but with the pawl being shown in the locking position; Figure 5 is a front view of the pawl in the rest position, the two pivots shown being capable of engaging with the ends of the bimetallic strip; Figure 6 is a view similar to that of Figure 5 but with the pawl being shown in the locking position; Figure 7 is a side view of a second embodiment of the invention;; Figure 8 is a similar view to Figure 7 but with the pawl being shown in the locking position; Figure 9 is a rear view of the device, in the direction of the arrow in Figure 8; Figure 10 is a top view of a device in which the two functions of mechanical dealy action and of electrical energization are independent; Figure 11 is a cross-sectional side view of the device shown in Figure 10; Figure 12 is a top view of the slider; and Figure 13 is a side view of the slider.

As shown in Figures 1 -4, a bimetallic strip (or shaped plate) 4 is arranged on a capsule or pellet 3 which is made of a positive temperature coefficient material (or PTC material), the bimetallic plate being in electrical contact with a first terminal 1.

The terminal 1 includes an end A which is bent through 900 and keeps the bimetallic plate 4 in place on the cylinder 3. One of the ends of the said plate 4 passes between and engages two small pivots X and Y of a locking pawl 5 which is freely pivoted by means of a pivot 20 mounted on the envelope or housing 6 of the device. The other face of the pellet 3 is in contact with a second terminal 2 of the electric circuit,(as shown in Figure 4).

The terminals 1 and 2 are part of the circuit for the supply of electric power to the machine, so that when the machine itself is operating, current is flowing through the device.

The geometrical arrangement and the shapes of the two small pivots X and Y are shown in Figures 5 and 6 (which are views of the end of the locking pawl 5). it can be observed that, in this embodiment, the small pivot X has a circular cross-section, whereas the cross-section of the pivot Y is semi-circular. In the rest position, (that is, when the pellet 3 and the bimetallic plate 4 are cool), the end of the plate between the small pivots X and Y rests on the hemispherical pivot Y along a resting or supporting line only.

The operation of the device is as follows. Electric current, passing through the terminals 1 and 2, heats the pellet 3 and thus the bimetallic plate 4.

Eventually, the bimetallic plate reaches its bending temperature and the end of the plate moves upwards, exerting a force on the small pivot X. This force causes the locking pawl 5 to rotate through 900 about the pivot 20 until the operative position (shown in Figure 6) is reached in which the strip 4 rests on the flat face of the small pivot Y. In this position the door to the appliance is locked. A stop B is provided on the terminal 1, on which stop the end of the bimetallic plate 4 rests in its high-temperature bent position. This stop acts as a reaction point for the force of the panel on the other end of the plate. At the end of the operative cycle of the machine, (that is, when the electric power to the machine is swtiched off), the pellet 3 and the strip 4 cool and when the bending temperature is reached, the opposite occurs: that is, the strip moves back to its rest position so causing the locking pawl 5 to rotate through 900 in the opposite direction and return to its inoperative (unlocked) position.

As shown in Figures 5 and 6, the pivots X, Y are both arranged offset from the longitudinal symmetry plane of the pawl 5, at different distances from this plane, and spaced apart from one another at approximately the thickness of the bimetallic plate in the longitudinal sense of the pawl. The pivot 20, around which the pawl 5 can rotate, is arranged on the longitudinal symmetry plane of the pawl, and lies above the pivot X when the pawl is in its rest position.

In a second embodiment shown in Figures 7, 8 and 9, the device is identical with the first embodiment except for the configuration of the locking pawl and the way in which it engages with the end of the bimetallic plate.

The locking pawl 7 of the embodiment (illustrated in its rest position in Figure 7) is L-shaped and it is freely pivoted on the housing 6 by means of a pivot 10. This pivot is substantially parallel to the plane of the bimetallic plate 4; the pawl 7 thus pivots about an axis perpendicular to that of the panel 5 of the first embodiment. A small peg 8 projects out from the longest stem of the pawl 7, and has the end of a spring 9 attached thereto. The other end of the spring is attached to a second peg 11 which is integral with or attached to the housing 6.

The operation of the second embodiment is as follows. Current passing through the device heats the cylinder 3, and this heat is transferred to the bimetallic plate. At the bending temperature the plate trips upwards, causing the pawl 7 to rotate around the pivot 10, slightly farther than the liningup positon of the three points 8, 10 and 11. Here, the pawl loses cpntact with the plate and continues its 900 rotation by the action of the spring 9. Finally; as shown in Figure 8, it rests in the locking position in which the bimetallic strip 4 rests on the shortest stem of the pawl 7.When the current is switched off and the cylinder 3 and bimetallic plate 4 have cooled below the bending temperature the opposite action occurs and the pawl 7 moves suddenly to a position slightly below the alignment line of the points 8, 10 and 11, after which the pawl 7 moves to the unlocking position by the action of the spring 9.

In Figure 9, the pawl 7 is shown in its locking position. In this position it is retained in a recess of a slider 12, which locks the machine door lock.

Use of one or the other of these two embodiments thus allows a choice of the length of the pawl as well as of the rotational axis of the pawl, and accordingly the direction of action of the actual locking part. Thus, according to the particular requirement the pawl can be caused to rotate through 90 around either one of the axes which are mutually at right angles from the position in which the machine door is locked, to a rest position in which the door is unlocked so that it can be opened.

In the embodiments previously disclosed the locking action is linked to the action of supplying electrical power to the apparatus, so that it is impossible to unlock and open the machine door if the machine itself is operating.

With reference to Figures 10 -13, a third preferrred embodiment will now be described in which these two functions are completely independent, in as much as they are performed by separate parts of the device. It can be seen that the device comprises a housing 19 with four electrical terminals 21, 22, 23 and 24, the two first terminals 21 and 22 performing the locking function and being directly controlled by the timer or programmer of the apparatus (and/or by suitable sensors), the programmer determining the time when the locking function is to be operational or non-operational; and the two second terminals 23, 24 performing the function of supplying electrical power to the apparatus. A slightly curved flexible strip 25, capable of elastically tripping under the action of a suitable force, is fastened to the fourth electrical terminal 24.The strip is shown in Figure 10 in the stable normal rest position, and is able to switch to the other (activation) position in which it closes the contact with the third terminal 23, thus allowing power to flow to the machine. Pressing upon one side of the strip is an actuating member 26 which is part of a slider 27 (shown in Figures 12 and 13).

The slider 27 includes, at the far end from the actuating member, a space 28 in which the catch of the door engages when it is closed. It also includes an aperture 29 into which is received the locking pawl 5 in the operative (locking) position. The slider 27 is urged towards its rest (unlocked) position, (the right in Figure 10), by a spring 30 which is located between a fastening member 31 fixed to the housing 19 of the device and an abutment on the slider 27. The rightmost position of the slider is defined by two flanges 33, 34 of the slider 27, which stop against the inside wall of the housing 20, as is shown in Figure 10.

The operation occurs as follows. When the door is closed the door catch engages with the space 28 of the slider 27 and moves the slider to the left (in Figure 10). On movement of the slider 27, the actuating member 26 acts directly on the contact mobile strip 25 of the section that works as a switch (an electric actuator) so that the contact through which the apparatus is supplied with electrical power is closed. In the position of the slider, and in this position only, the slider 27 offers its locking aperture 29 for engagement with the locking pawl 5 that can prevent the slider from coming back and therefore can prevent the door from opening. As mentioned above, the rotation of the pawl 5 only occurs when the cylinder 3 is energized by means of a control action programmed by the timer or other similar device.When the energizing action stops, (this also being determined by the timer or the like), the pawl comes back to its original position unlocking the slider 27 which can again come back to its starting position in which the machine door can be opened.

As shown, the two functions are independent though they are integrated in the form of a single device; however, the integration of all components within a common housing allows one to obtain a control device of extremely limited size and low cost. The control device is suitable for insertion in the machine in any position, including positions which are difficult to reach for the devices that are commercially available at the present time.

It is to be remarked that, introducing obvious changes in the integrated device disclosed above, it is possible to employ either of the two forms of the locking pawl described previously, or any other suitable embodiment of the invention.

Claims

1. A delayed-release door lock comprising a bimetallic strip or plate member having a first curvature at a first temperature and a second curvature at a second, higher, temperature; a heating device for heating the bimetallic member when the door is closed and electric current is supplied to the device; and a locking member, operatively coupled to the bimetallic member and arranged for rotational motion between a free position in which the door can be opened and a locking position in which it is locked; whereby, when current is supplied to the heating device, the temperature of the bimetallic member is increased so that this bimetallic member trips into its second curvature state, thereby causing the locking member to rotate to its locking position, and, when current is no longer supplied to the heating device, the bimetallic member cools and trips back to its first curvature state, after an interval, thereby causing or allowing the locking member to rotate to its free position.

2. A lock as claimed in Claim 1 in which the locking member is caused to rotate by direct mechanical contact between the locking member and a substantially linearly-moving part of the bimetallic member.

3. A lock as claimed in Claim 2 in which the locking member is provided with two actuating members, offset from the axis of rotation by different amounts, rotation being caused by direct contact between the said part of the bimetallic member and one or the other of the actuating members.

4. A lock as claimed in Claim 3 in which the said part of the bimetallic member is positioned between the actuating members and is in contact with both of them in the locked and in the free position.

5. A lock as claimed in Claim 3 or Claim 4 in which the actuating members are pegs, one having a substantially circular cross-section, the other having a substantially semi-circular cross-section.

6. A lock as claimed in Claim 5 in which the bimetallic member abuts the plane face of the semicircular peg when the locking member is in the locked position.

7. A lock as claimed in any one of Claims 3 to 6 in which the axis of rotation of the locking member is substantially parallel to the plane of the bimetallic member, both actuating members and the said part of the bimetallic member lying on the same side of the axis in the free position.

8. A lock as claimed in Claim 7 in which the actuating members lie on opposite sides of the axis in the locked position.

9. A lock as claimed in Claim 2 in which the locking member is biased towards the locking position on one side of an intermediate position and is biased towards the free position on the other side of the intermediate position, and whereby tripping of the bimetallic member causes the locking member to move from one side of the intermediate position to the other.

10. A lock as claimed in Claim 9 in which the locking member includes a substantially L-shaped part, the said part of the bimetallic member acting upon one or the other arm of the L.

11. A lock as claimed in Claim 9 in which the locking member is pivoted substantially at the angle of the L and includes biasing means attached at one end to an arm of the L and at the other to a fixed point.

12. A lock as claimed in any one of Claims 9 to 11 in which the axis of rotation is substantially parallel to, but spaced from, the general plane of the bimetallic member.

13. A lock as claimed in any one of the preceding claims in which the lock acts as a power on-off switch for the device.

14. A lock as claimed in any one of Claims 1 to 12 which includes a separately operable power onoff switch for the device.

15. A lock as claimed in Claim 14 in which the power on-off switch is operated by the opening and closing of the door, and the lock is arranged to lock the door for selected periods when the device is operational.

16. A lock as claimed in Claim 14 or 15 which includes a slider having a first aperture into which a door catch is received to close the door, and a second aperture into which a part of the locking member is received to lock the door.

17. A lock as claimed in Claim 16 in which movement of the slider into a position in which the door is held closed closes an electrical contact and provides electrical power to the device.

18. A lock as claimed in Claim 17 in which the electrical contact comprises a spring electrode which is urged into contact with a fixed electrode by means of an actuator on the slider.

19. A lock as claimed in any one of Claims 14 to 18 in which the lock and the power on-off switch are contained in a common housing.

20. A delayed-release door lock substantially as specifically described herein with reference to Figures 1 to 6 or to Figure 7 to 9 of the accompanying drawings.

21. A delayed-release door lock substantially as specifically described herein with reference to Figures 10 and 13 and 1 to 6 of the accompanying drawings, or to Figures 10 to 13 modified as shown in Figure 7 to 9.

22. A device for the control of the electrical supply and for the delayed disengagement locking of machine doors, particularly of washing machine doors and the like, said device comprising a slider that engages with the tooth of the machine door and shows a space or a hole as the locking action seat, a positive temperature coefficient pellet (or PTC pellet), a bimetallic strip operatively coupled with a locking pawl, which pawl is capable of engaging with the locking space of the slider, and two terminals that carry electric current to said PTC pellet, said device being characterised in that the tripping straight-line motion of the end of the bimetallic strip is converted into a rotary motion of the locking pawl my means of the direct coupling of an end of the bimetallic strip with the locking pawl pivoted in the envelope by means of a pivot for causing the same to trip into rotation through 90 from the rest position to the operative position in which it engages with the slider and locks the same, when the bimetallic strip, heated by the PTC pellet, suddenly inverts its bending when the inversion temperature is attained, and for causing the same to come back to rest position in which it releases and unlocks said slider, when the bimetallic strip cools below said inversion temperature.

23. A device according to Claim 22, characterised in that the conversion of the straight-line motion of the end of the bimetallic strip into a rotatory motion of the pawl is performed by the action of said end of the strip on one of the two pivots provided on the pawl between which the strip itself is inserted, said pivots being both arranged on one side of the longitudinal symmetry plane of the pawl at different distances from said plane and spaced from each other of a distance about the same as the thickness of the bimetallic strip in the longitudinal sense of the pawl, said pawl being pivoted in the envelope by means of a pivot arranged on said longitudinal symmetry plane of the pawl above the pivot in the rest position of the pawl.

24. A device according to Claim 22, characterised in that the conversion of the tripping straightline motion of the bimetallic strip into the rotatory motion of the pawl occurs through the direct coupling of an end of the strip with the pawl, said pawl being L-shaped and whose longest stem rests in the inactive or rest position on said end of the strip, said pawl being pivoted in the envelope of the device by means of a pivot at a point corresponding to the angle between the longest stem and the shortest one, in the intermediate parts of the longest stem a pivot being provided with which an end of a spring is engaged, the other end of said spring being engaged with a pivot which is integral with the envelope, the arrangement of pivots being such that in the operative position as well as in the rest position the spring is located si- dewise with respect to the rotation pivot so as to urge the pawl into one of its two positions, when the pawl itself has slightly passed the alignment position of the pivots under the action of the strip on its longest stem or on its shortest stem.

25. A device according to Claim 23, characterised in that one of two said pivots is of a circular cross-section, whereas the other one is of a semicircular cross-section.

26. A device for the control of the electrical power supply and for the delayed disengagement locking of machine doors, particularly of the doors of washing machines and the like, said device comprising a slider that engages with the tooth of the door and shows a locking space, and it also comprises a positive temperature coefficient pellet (or PTC pellet), a bimetallic strip operatively coupled with a locking pawl which is suitable for engagement with the locking space of the slider, and some terminals which carry electric current to said PTC pellet, said device being characterised in that a third electrical terminal and a fourth electrical terminal are provided in order to carry into effect the supplying of electrical power to the apparatus, a tripping contact strip being fastened to the fourth terminal and suitable for closing the contact with the third terminal, said slider also having a small stake which, while the slider is moving, urges the contact strip to pass from the normal rest position, in which the contact with the third terminal is open, to the activation position, in which the contact with the third terminal is closed, said slider being caused to return to its starting position by the action of a spring.

27. A device according to Claim 26 characterised in that the locking space of the slider is arranged in a position such as to be capable of engaging with said locking pawl only when said slider is in the operative position, i.e. when the machine door is closed.

28. A device according to Claim 26, characterised in that said return spring is loaded between a fastening member fixed to the envelope of the device, and a striker provided on said slider.

29. A device according to Claim 26, characterised in that the rest position of said slider is determined by the cooperation of the ledge members provided on the slider itself, with an inside wall of said envelope.

30. A device according to Claim 26, characterised in that said contact strip is a tripping contact strip, such that the strip itself can move from the stable rest position to the activation position by the urging action of the small stake on the slider and it can come back automatically with a tripping motion to the starting position as soon as the action of said small stake stops.