TEXT OF THE DESCRIPTION

Field of the invention

The present invention relates to a door lock for home appliances such as washing machines, laundry dryers and the like.

Background of the invention

A door lock for household appliances is an electromechanical device designed to lock the door of the machine in a closed position and provided with terminals connected to a control unit of the appliance. Examples of door locks for household appliances are described, for instance, in WO2016102565 and WO2017155627. The devices described in these documents include:

- a housing including a cam support and a base plate having an opening for inserting a hook carried by the appliance door,

- a cam rotating with respect to the cam support around a rotation axis between two opposite end positions and a hook holding position intermediate between said end positions,

- a locking slider cooperating with the cam and capable of locking the cam in the hook holding position, and

- an actuator, for instance an electromagnetic actuator, comprising a locking pin capable of locking the locking slider in the cam locking position.

The locking pin is normally associated with a switch that can be switched between an open position and a closed position corresponding to the unlocking position and locking position of the locking pin. The switch provides to the control unit of the appliance a signal indicating the locked door condition when the locking pin is properly engaged with the slider to lock it into the cam locking position. However, in known devices the switch associated with the locking pin may provide information that the door is properly locked when the hook or cam is broken or when the cam is rotated to the lock position in the absence of the hook.

Object and summary of the invention The object of the present invention is to provide a door lock for appliances having a safety function that prevents closure of the switch associated with the locking pin in the event of a hook or cam break or when the cam is rotated to the end position in the absence of the hook.

According to the present invention, this object is achieved by a door lock having the features of claim 1.

The claims form an integral part of the teaching given in connection with the invention.

Brief description of the drawings

The present invention will now be described in detail with reference to the accompanying drawings, given as a non-limiting example, in which:

- Figure 1 is a perspective view of a base plate of a door lock according to the present invention,

- Figure 2 is a perspective view of a door lock with the base plate removed, - Figure 3 is a perspective view of the door lock of Figure 2 in an open-door position with some components removed,

- Figure 4 is a perspective view similar to Figure 3 illustrating the door lock in a closed and unlocked door position,

- Figure 5 is a perspective view corresponding to Figures 3 and 4 and illustrating the door lock in a closed and locked door position,

- Figure 6 is a perspective view corresponding to Figures 3, 4 and 5 illustrating the door lock in a broken hook/cam position or with the cam rotated in an end position in the absence of the hook; and

- Figures 7 and 8 are enlarged details of the parts indicated by arrows VII and VIA in Figures 5 and 6.

It will be appreciated that for simplicity and clarity of illustration the figures may not be reproduced in the same scale and that in some figures some of the components are not illustrated to simplify the understanding of the figures.

Detailed description

Referring to Figures 1 and 2, the numeral reference 10 indicates a door lock for household appliances, in particular for washing machines, laundry dryers and the like. The door lock 10 comprises a base plate 11 having an opening 14 within which a hook 16 (Figures 3-6) carried by the door of the household appliance is intended to be inserted.

Referring to Figures 2 and 3 to 5, the door lock 10 comprises a cam 18 rotatably carried by a cam support 12 around a first axis A. The cam 18 has a general C -shape and is intended to engage the hook 16. The cam 18 cooperates with a spring 20 having a bistable function. The spring 20 elastically biases the cam 18 towards two stable end positions shown in Figure 3 and Figure 6, respectively. When the hook 16 engages the cam 18 the cam 18 is held in position intermediate between said stable end positions, shown in figures 4 and 5. The cam 18 has a protrusion 50 whose function will be described in the following.

Referring to Figures 2-6, the door lock 10 comprises a locking slider 22 rotatable with respect to the cam support 12 about a second axis B transverse with respect to the first axis A. The locking slider 22 cooperates with a second spring 24 that elastically biases the locking slider 22 in the direction indicated by arrow C.

Referring to Figures 3-6, the door lock 10 comprises a trigger element 26 carried by the cam support 12 and/or base plate 11. The trigger element 26 forms a stop against which the locking slider 22 abuts under the elastic force of the spring 24. As shown in detail in Figure 7, the locking slider 22 has a projection 28 that comes into contact with a corresponding projection 30 of the trigger element 26. The trigger element 26 may be connected to the cam support 12 and/or base plate 11 by means of a yielding connection portion, for example of flexible plastic material. The trigger element may be molded integrally with the cam support 12 and/or base plate 11.

When the cam 18 or the hook 16 break or when the user inserts an object through opening 14, the trigger element 26 is displaced from a stop position shown in Figure 7 to a release position shown in Figure 8, as will be described in the following. In the stop position, the projection 30 of the trigger element 26 interferes with the projection 28 of the locking slider 22 and forms a stop for the locking slider 22. In the release position shown in Figure 8, the projection 30 of the trigger element 26 is disengaged from the projection 28 of the locking slider 22 and allows the locking slider 22 to rotate around the axis B in the direction indicated by the arrows C in Figures 3-6 beyond the hook holding position in the normal working condition of the appliance.

The door lock 10 comprises a locking pin 32 capable of locking the locking slider 22 and consequently the cam 18 when the locking slider 22 and the cam 18 are in a locking position. The locking pin 32 is movable along a straight line between an unlocking position and a locking position, and vice versa. The direction along which the locking pin 32 is movable may be parallel to the axis B around which the locking slider 22 is rotatable. The movement of the locking pin 32 along a direction Dl between the unlocking position and the locking position is controlled by an actuator 34, which may be an electromagnetic actuator. The actuator 34 drives a transmission element 36 which is movable in a rectilinear direction orthogonal to direction Dl. The transmission element 36 is connected to the locking pin 32 by means of a ramp surface 38 (Figures 5 and 6) that moves the locking pin 32 as a result of the movement of the transmission element 36 in the direction E.

The door lock 10 comprises a switch 40 that can be switched between an open position and a closed position, indicative of the unlocked/locked door status, respectively. The switch 40 comprises a fixed contact 42 and a movable contact 44 having a contact rivet 45. The movable contact 44 may be formed by a flexible lamina which normally keeps the contact rivet 45 in contact with the fixed contact 42.

The movable contact 44 is engaged with the locking pin 32. The switch 40 is in an open position when the locking pin 32 is in the release position (Figures 3, 4 and 6) and is in a closed position when the locking pin 32 is in the locking position (Figure 5). The switch 40 has two or more terminals 47, for instance three terminals, which are intended to be connected to the control unit of the appliance.

The operation of the door lock 10 is as follows.

Figure 3 shows the door lock 10 in the open-door configuration. The hook 16 is disengaged from the cam 18. The cam 18 is held by the spring 20 in the open-door position, in which the open side of the cam 18 is facing the hook insertion opening 14. In this position, the cam 18 holds the locking slider 22 in an unlocking position. In this position, a surface 46 of the locking slider 22 faces a front end of the locking pin 32 and prevents a movement of the locking pin 32 from the unlocking position to the locking position.

Figure 4 illustrates the position of door lock 10 in the condition where the door is closed but not yet locked. In this condition, the hook 16 engages the cam 18. The hook 16 keeps the cam 18 in an intermediate position between the two stable end positions. The locking slider 22 under the action of the spring 24 rotates in the direction C towards a locking position. In this position, the locking slider 22 abuts against the trigger element 26. A recess 48 of the locking slider 22 faces the front end of the locking pin 32. Therefore, the locking pin 32 is free to move from the unlocking position to the locking position in the direction Dl. The locking pin 32 is biased in the direction Dl by the elasticity of the movable contact 44.

When the locking slider 22 is in the configuration of Figure 4 (closed and unlocked door), activation of the actuator 34 moves the locking pin 32 from the unlocking position (Figure 4) to the locking position (Figure 5). In the locking position, the locking pin 32 engages the recess 48 of the locking slider 22 and prevents rotation of the slider 22 around the axis B in the direction opposite to the direction indicated by the arrow C in Figure 5. In this condition, the locking slider 22 locks the cam 18 and prevents rotation of the cam 18 towards a disengagement position of the hook 16. In this condition, the switch 40 is in the closed position and through the terminals 47 provides to the control unit of the appliance a signal that the door is closed and locked.

Figure 6 shows the door lock 10 in a condition in which the hook 16 and/or the cam 18 are broken. The same condition of figure 6 is obtained when the cam 18 is rotated in the absence of the hook 16, for example by inserting a pointed object, such as the tip of a screwdriver, inside the opening 14 of the base plate 11.

In this condition, the cam 18 rotates under the action of the spring 20 beyond the hook holding position illustrated in Figure 5 and reaches the stable end position opposite the hook release position shown in Figure 3. When the cam 18 is in the end position shown in Figure 6, a protrusion 50 of the cam 18 presses on the trigger element 26 and moves the trigger element 26 to the release position shown in Figure 8. In this position, the locking slider 22 is disengaged from the trigger element 26 and is free to rotate around the axis B in the direction indicated by the arrow C under the action of the spring 24. The further rotation of the locking slider 22 beyond the locking position brings a protrusion 52 of the locking slider 22 in contact with the front end of the locking pin 32 (Figure 6) and pushes the locking pin 32 to the release position in the direction indicated by D2 in Figure 6. Therefore, the locking pin 32 opens the switch 40, which signals to the appliance control unit that the door is not locked.

The door lock 10 according to the present invention is therefore provided with an additional safety function which prevents the switch 40 from indicating a door locked state in the case of breakage of the hook 16 and/or of the cam 18 or in the case of rotation of the cam 18 in the absence of hook 16.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments can be varied with respect to those illustrated here without departing from the scope of the invention as defined by the attached claims.