Fluid pump without dead volume

A pump for the delivery of a fluid contained in an elastic phial, comprising:

• a pump body having a front end on a fluid outlet side, said front end comprising an outlet orifice (11) sealed off by an elastic membrane (24), and continuing backwards through a pump duct (18) with a fluid inlet orifice (15);
• and
• a movable piston fitted inside the pump body, the relative displacement of an end (2) of the piston in relation to the pump body between the inlet orifice (15) and a stop (16) position located towards the outlet orifice (11) thus determining the quantity of fluid expelled on displacement, the end (2) of the piston fitting hermetically by slight friction against the pump duct (18), the inlet orifice (15) being of a sufficient size for only the preset quantity of fluid to be trapped in an end of the pump duct (18) for its expulsion through the outlet orifice (11), the pump body and the piston being totally enveloped by the phial, with the exception of the front end of the pump body;
• wherein the pump has an elastic means of returning the piston to the stop position, and wherein the elastic means of returning the piston to the stop position comprises the elastic phial itself, and wherein the elastic means of returning the piston to the stop position comprises two concertinas (22, 23) located either side of a retaining ring (5) integral with the piston.

A pump for the delivery of a fluid contained in an elastic phial, comprising:

• a pump body having a front end on a fluid outlet side, said front end comprising an outlet orifice (11) sealed off by an elastic membrane (24), and continuing backwards through a pump duct (18) with a fluid inlet orifice (15);
• and
• a movable piston fitted inside the pump body, the relative displacement of an end (2) of the piston in relation to the pump body between the inlet orifice (15) and a stop (16) position located towards the outlet orifice (11) thus determining the quantity of fluid expelled on displacement, the end (2) of the piston fitting hermetically by slight friction against the pump duct (18), the inlet orifice (15) being of a sufficient size for only the preset quantity of fluid to be trapped in an end of the pump duct (18) for its expulsion through the outlet orifice (11), the pump body and the piston being totally enveloped by the phial, with the exception of the front end of the pump body;
• wherein the piston is an elongated element having a plurality of radial elements (4) as anchors which have arc-shaped elements (5) at their ends, the pump body is cylindrical and comprises a front ring (13a), a cylindrical rear ring (8), of larger diameter than the diameter of the arcs (5), the front base of the rear cylindrical ring being cut away so that the above anchors can pass through the base of said cylinder thus enabling, by means of slots corresponding to the radial elements, and made in the cylinder comprising the pump body, the longitudinal displacement of the piston.

A pump, for projecting a consistently reproducible volume of fluid into the conjunctival sac of an eye essentially without causing any sensation of pain or discomfort, comprising:

• a reservoir made of elastic material,
• a pump body in fluid communication with the reservoir, said pump body having a front end on a fluid outlet side, said front end comprising an outlet orifice (11) sealed off by an elastic membrane (24),
• a piston arranged to move inside the pump body and an elastic means for returning the piston to the stop position, said elastic means of return being calibrated so as to project a predetermined volume of fluid through the outlet orifice (11) and a separable seam defined by interface of said outlet orifice (11) and said elastic membrane (24);
• and
• an elastic phial enveloping the pump body and piston, with the exception of the front end of the pump body.