Device for dispensing a washing or rinsing agent

1. Device for dispensing a washing or rinsing agent, in particular for a dishwashing machine, comprising:

a container having:

an inlet opening which is adapted to be closed in a fluid-tight manner and is able to allow filling of a quantity of a washing/rinsing agent inside the container,

an outlet opening which is adapted to be closed in a fluid-tight manner and is able to allow the dispensing of a quantity of washing/rinsing agent during an operating cycle of the dispensing device, and

a feeder screw mounted rotatably about its longitudinal axis inside the container and situated in a position substantially coaxial with the outlet opening and capable of conveying the washing/rinsing agent towards said outlet opening;

transmission members driven by a motor unit and able to impart a rotation to the screw about its axis during an operating cycle of the device; and

a closing valve unit able selectively to free and close off in a fluid-tight manner the outlet opening,

wherein the closing valve means comprise a butterfly shutter for freeing and closing off selectively the outlet opening in a manner controlled by rotation of the screw; and

wherein the screw comprises a first and a second portion which are interconnected with play in the direction of the axis of said screw, which are rotationally locked together and which are spaced by means of the action of resilient elements arranged between said first and second portions.

2. Device according to claim 1 , in which the butterfly shutter is mounted coaxially with the screw and is locked rotationally with the latter, and the closing valve unit also comprise:

a valve part mounted on the container opposite the outlet opening and having at least one shaped orifice on which the butterfly shutter slides, gradually and periodically freeing and closing off said shaped orifice.

3. Device according to claim 2 , in which the shaped orifices are a pair of shaped openings in the form of a circular sector having an angular amplitude of 90° and offset angularly at 180° with respect to each other, and the butterfly shutter has a shaped part with a form substantially complementing that of the orifices and slidable on them.

4. Device according to claim 1 , in which the screw meshes with at least one gear wheel situated inside the container for stirring and mixing the washing/rinsing agent present in the container.

5. Device according to claim 4 , in which the screw meshes with a pair of gear wheels situated inside the container.

6. Device according to claim 1 , in which the container has a neck in which the outlet opening is formed and which directs the washing/rinsing agent towards said outlet opening.

7. Device according to claim 1 , in which the closing valve unit comprises a movable shutter able to move between a closed position, where it closes the outlet opening, and an open position, where it frees said outlet opening as a result of the excitation of an electrically controlled actuating unit, against the action of a resilient return element.

8. Device according to claim 1 , in which the motor unit allows controlled driving of the screw so as to perform dispensing of an adjustable quantity of the washing/rinsing agent for variable periods and quantities.