Door-lock for home appliances

A door-lock for a home appliance is provided. The door-lock has a cam that cooperates with a hook and can rotate between two end positions and an intermediate hook holding position. A locking slider cooperates with the cam to lock it and an actuator-controlled locking pin can lock the locking slider. A switch is switchable between open and closed positions, respectively corresponding to the unlocking and locking positions of the locking pin. A cam support carries a trigger element and/or base plate and has a stop that locks the locking slider. A portion of the cam disengages the trigger element from the locking slider when the cam is in an end position opposite a hook release position. The locking slider can rotate beyond the cam locking position to push the locking pin toward the unlocking position with a protrusion when the trigger element is disengaged from the locking slider.

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 claim1.

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

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 toFIGS. 1 and 2, the numeral reference10indicates a door lock for household appliances, in particular for washing machines, laundry dryers and the like. The door lock10comprises a base plate11having an opening14within which a hook16(FIGS. 3-6) carried by the door of the household appliance is intended to be inserted.

Referring toFIGS. 2 and 3 to 5, the door lock10comprises a earn18rotatably carried by a cam support12around a first axis A. The cam18has a general C-shape and is intended to engage the hook16. The cam18cooperates with a spring20having a bistable function. The spring20elastically biases the cam18towards two stable end positions shown inFIG. 3andFIG. 6, respectively. When the hook16engages the cam18the cam18is held in position intermediate between said stable end positions, shown inFIGS. 4 and 5. The cam18has a protrusion50whose function will be described in the following.

Referring toFIGS. 2-6, the door lock10comprises a locking slider22rotatable with respect to the cam support12about a second axis B transverse with respect to the first axis A. The locking slider22cooperates with a second spring24that elastically biases the locking slider22in the direction indicated by arrow C.

Referring toFIGS. 3-6, the door lock10comprises a trigger element26carried by the cant support12and/or base plate11. The trigger element26forms a stop against which the locking slider22abuts under the elastic force of the spring24. As shown in detail inFIG. 7, the locking slider22has a projection28that comes into contact with a corresponding projection30of the trigger element26. The trigger element26may be connected to the cam support12and/or base plate11by means of a yielding connection portion, for example of flexible plastic material. The trigger element may be molded integrally with the cam support12and/or base plate11.

When the cam18or the hook16break or when the user inserts an object through opening14, the trigger element26is displaced from a stop position shown inFIG. 7to a release position shown inFIG. 8, as will be described in the following. In the stop position, the projection30of the trigger element26interferes with the projection28of the locking slider22and forms a stop for the locking slider22. In the release position shown inFIG. 8, the projection30of the trigger element26is disengaged from the projection28of the locking slider22and allows the locking slider22to rotate around the axis B in the direction indicated by the arrows C inFIGS. 3-6beyond the hook holding position in the normal working condition of the appliance.

The door lock10comprises a locking pin32capable of locking the locking slider22and consequently the cam18when the locking slider22and the cam18are in a locking position. The locking pin32is movable along a straight line between an unlocking position and a locking position, and vice versa. The direction along which the locking pin32is movable may be parallel to the axis B around which the locking slider22is rotatable. The movement of the locking pin32along a direction D1between the unlocking position and the locking position is controlled by an actuator34, which may be an electromagnetic actuator. The actuator34drives a transmission element36which is movable in a rectilinear direction orthogonal to direction D1. The transmission element36is connected to the locking pin32by means of a ramp surface38(FIGS. 5 and 6) that moves the locking pin32as a result of the movement of the transmission element36in the direction E.

The door lock10comprises a switch40that can be switched between an open position and a closed position, indicative of the unlocked/locked door status, respectively. The switch40comprises a fixed contact42and a movable contact44having a contact rivet45. The movable contact44may be formed by a flexible lamina which normally keeps the contact rivet45in contact with the fixed contact42.

The movable contact44is engaged with the locking pin32. The switch40is in an open position when the locking pin32is in the release position (FIGS. 3, 4 and 6) and is in a closed position when the locking pin32is in the locking position (FIG. 5). The switch40has two or more terminals47, for instance three terminals, which are intended to be connected to the control unit of the appliance.

The operation of the door lock10is as follows.

FIG. 3shows the door lock10in the open-door configuration. The hook16is disengaged from the cam18. The cam18is held by the spring20in the open-door position, in which the open side of the cam18is facing the hook insertion opening14. In this position, the cam18holds the locking slider22in an unlocking position. In this position, a surface46of the locking slider22faces a front end of the locking pin32and prevents a movement of the locking pin32from the unlocking position to the locking position.

FIG. 4illustrates the position of door lock10in the condition where the door is closed but not yet locked. In this condition, the hook16engages the cam18. The hook16keeps the cam18in an intermediate position between the two stable end positions. The locking slider22under the action of the spring24rotates in the direction C towards a locking position. In this position, the locking slider22abuts against the trigger element26. A recess48of the locking slider22faces the front end of the locking pin32. Therefore, the locking pin32is free to move from the unlocking position to the locking position in the direction D1. The locking pin32is biased in the direction D1by the elasticity of the movable contact44.

When the locking slider22is in the configuration ofFIG. 4(closed and unlocked door), activation of the actuator34moves the locking pin32from the unlocking position (FIG. 4) to the locking position (FIG. 5). In the locking position, the locking pin32engages the recess48of the locking slider22and prevents rotation of the slider22around the axis B in the direction opposite to the direction indicated by the arrow C inFIG. 5. In this condition, the locking slider22locks the cam18and prevents rotation of the cam18towards a disengagement position of the hook16. In this condition, the switch40is in the closed position and through the terminals47provides to the control unit of the appliance a signal that the door is closed and locked.

FIG. 6shows the door lock10in a condition in which the hook16and/or the cam18are broken. The same condition ofFIG. 6is obtained when the cam.18is rotated in the absence of the hook16, for example by inserting a pointed object, such as the tip of a screwdriver, inside the opening14of the base plate11.

In this condition, the cam18rotates under the action of the spring20beyond the hook holding position illustrated inFIG. 5and reaches the stable end position opposite the hook release position shown inFIG. 3. When the cam18is in the end position shown inFIG. 6, a protrusion50of the cam18presses on the trigger element26and moves the trigger element26to the release position shown inFIG. 8. In this position, the locking slider22is disengaged from the trigger element26and is free to rotate around the axis B in the direction indicated by the arrow C under the action of the spring24. The further rotation of the locking slider22beyond the locking position brings a protrusion52of the locking slider22in contact with the front end of the locking pin32(FIG. 6) and pushes the locking pin32to the release position in the direction indicated by D2inFIG. 6. Therefore, the locking pin32opens the switch40, which signals to the appliance control unit that the door is not locked.

The door lock10according to the present invention is therefore provided with an additional safety function which prevents the switch40from indicating a door locked state in the case of breakage of the hook16and/or of the cam18or in the case of rotation of the cam.18in the absence of hook16.

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.