Shutoff valve mechanism for the oral evacuator of a dental unit

A shutoff valve mechanism (40) for use in conjunction with a oral evacuator of a dental unit, said mechanism being connectable to a suction tube (14) communicating with a vacuum pump, said shutoff valve mechanism (40) comprising non-moving elements (41, 42, 43, 44, 45, 46) permanently attached to the suction tube (14) and elements (49, 50, 51, 52, 53, 54, 55) adapted movable relative to said non-moving elements, both sets of elements incorporating a flow channel (41a,42a, 43a, 53a) and the latter set (49, 50, 51, 52, 53, 54, 55) of elements being attached to a body part (53) of the shutoff valve mechanism capable of accommodating the connection of an evacuator tip (30) of the oral evacuator, said shutoff valve mechanism (40) further comprising a valve element (48) and a compatible seating element (42), and said valve closing and staying closed (FIG. 3A) by virtue of a vacuum maintained in the suction tube (14), and said shutoff valve mechanism further comprising an articulated joint assembly (45, 51, 54) capable of opening the shutoff valve mechanism by rotation about an axis or axes oriented nonparallel with the center axis (K--K) of the shutoff valve mechanism (40), characterized in that one (48/42) of the valve elements (48) and seating elements (42) is permanently attached to said body part (53), while the other element (42/48) is attached to the adapter member (41) of the suction tube (14) so that the shutoff valve mechanism incorporates two partial entities mutually rotatable about said rotation axis or axes, said partial entities being mutually adapted to provide a high lever arms ratio or long lever arm for the opening operation of the mechanism, thereby achieving a sufficient opening force actuated by the weight of the suction tube and/or flection force imposed.