Patent ID: 7171728

Claim:
A retractable control knob for an electrical appliance, said control knob comprising: a hub having opposite front and rear ends, wherein the rear end is receivable in a seat in a housing of the appliance and engageable with a control pin of the appliance in said seat, said control pin being adapted to control at least one function of the appliance; a grip angularly fixed to, but axially slidable on, the hub; a locking mechanism for selective axial connection of the grip to the hub and for blocking said grip at a first axial position and a second axial position axially rearwardly spaced from the first axial position; an elastic element disposed between said hub and said grip and axially biasing said grip forwardly towards said first axial position, in which the grip projects in cantilever fashion from the front end of the hub and is set, in use, at least partially outside said seat, wherein, in said second axial position, the grip is fitted over the front end of said hub and is retracted, in use, within said seat; a closed chamber defined between the grip and the hub and having a volume depending on a relative axial position of the grip on the hub; a sliding seal sealing closed chamber in an airtight manner; and a calibrated orifice being carried by any of said hub and said grip for permanently fluidly connecting an interior of said chamber with the external environment for causing a variation in pressure of the air contained in said chamber as a result of an axial movement of the grip with respect to the hub, thereby dampening said axial movement; wherein said grip is cup-shaped and has a concavity facing said hub; said front end of said hub has a hole opening forwardly and having a rear end wall and a side wall projecting forwardly from said end wall; a rod fixed to and carried by said grip extends axially in cantilever fashion in said hole; a free end of said rod carries said seal which is an annular fluid-tight gasket in sliding and fluid-tight contact with the side wall of the hole, so that the side wall and the end wall of the hole, together with said free end of the rod, define said closed chamber; said grip further comprises a sleeve coaxial to said rod, extending axially in cantilever fashion inside the grip, and slidably fitted on an outer side surface of the hub in order to guide axial sliding movement of the grip with respect to the hub; said rod and said sleeve are integrally connected by a connecting portion so as to form a single connection element fixedly snapped within a seat defined by a further sleeve of the grip, said further sleeve extending in cantilever fashion inside said grip; and said locking mechanism is provided between the hub and the sleeve at substantially the same axial position as said closed chamber, thereby reducing an overall axial dimension of said knob.