High-pressure pre-compression pump

A pump for dispensing a fluid product comprising a piston secured to an actuating stem and which slides in a pump body having a pump chamber defined between an inlet valve and an outlet valve, said outlet valve comprising an outlet valve element sliding during actuation in a sealed manner along the pump chamber, said pump chamber comprising passage means such that, at the end of actuation of the pump, said outlet valve element co-operates in a non-sealed manner with said passage means in order to open said outlet valve to allow the expulsion of the product contained in the pump chamber, said inlet valve comprising an inlet valve element which slides after closure of the inlet valve in a sleeve of the pump body, said sleeve having a reduced diameter and containing a spring pressing firstly on said inlet valve element and secondly on a bottom of said sleeve, said spring, in addition expelling the product, also returning the piston into its rest position, wherein said outlet valve element is formed by a separate part which is inserted movably in said piston, with the interposition of a second spring, the force exerted by said second spring being greater than the force exerted by said spring in position at rest, and less than the force exerted by said spring in the actuated position;

• wherein the pump chamber includes a pump chamber shoulder disposed above the sleeve, said pump chamber shoulder having a reduced diameter from the pump chamber;
• wherein a reinforcement sleeve is inserted into said pump body and placed into contact with the pump chamber shoulder to reinforce the side wall of said pump chamber, forming a double wall in the pump chamber to avoid a deformation of said side wall due to high pressure created during actuation;
• and
• wherein said reinforcement sleeve includes a shoulder defining said passage means of said outlet valve.