Fluid dispenser pump

1. A fluid dispenser pump comprising: a pump body; a pump chamber; at least a first piston that slides in said pump chamber between a rest position and an actuated position so as to dispense the fluid; and a dispenser orifice; said pump chamber including an inlet valve that separates the pump chamber from a channel that extends towards a fluid reservoir, a bypass being provided between said channel and said pump chamber, said bypass being disposed upstream from said inlet valve, wherein said bypass connects the pump chamber to the reservoir when the piston is in its actuated position, each time the pump is actuated;

wherein said first piston is secured to a hollow rod that forms, at least in part, said channel, said inlet valve, and said bypass;

wherein said hollow rod includes, in or on its outside surface, between said bypass and said first piston, a passage that connects the pump chamber and the bypass when the first piston is in its actuated position, regardless of the deformation of the components of the pump under the effect of the suction generated on each actuation; and

wherein the bypass is a lateral borehole formed in a valve seat upstream of the valve inlet.

2. A pump according to claim 1 , in which the inlet valve comprises both a valve member and the valve seat that is secured to the first piston, said first piston sliding in leaktight manner in said pump body, said pump body including at least one opening that co-operates with the first piston in its actuated position so as to open said bypass and enable pressure to be equalized between the pump chamber and the reservoir.

3. A pump according to claim 1 , in which said pump includes a dispenser head that incorporates said dispenser orifice.

4. A pump according to claim 1 , in which said pump includes a plug that is displaceable and/or deformable between a closed position of the dispenser orifice and an open position of the dispenser orifice.

5. A pump according to claim 4 , wherein the pump comprises a dispenser head that incorporates the dispenser orifice and in which said plug includes at least a second piston that co-operates in leaktight manner with the head, in any position.

6. A pump according to claim 4 , in which the pump body is made integrally with said plug.

7. A pump according to claim 4 , in which said plug is urged resiliently, in particular by a spring, towards its closed position, and is moved or deformed towards its open position by the pressure of the fluid contained in the pump chamber.

8. A pump according to claim 2 , in which the valve member is a ball.

9. A pump according to claim 4 , in which a single spring urges said first piston towards its rest position, and said plug towards its closed position.

10. A pump according to claim 9 , in which said spring does not come into any contact with the fluid.

11. A pump according to claim 1 , in which said first piston and said valve seat are made integrally with a fastener element, such as a snap-fastenable, crimpable, or screw-fastenable ring, that is adapted to fasten said pump on the fluid reservoir.

12. A pump according to claim 1 , in which said hollow rod is connected to a dip tube that extends into said reservoir.

13. A pump according to claim 1 , in which said passage means comprise at least one groove or spline.

14. A fluid dispenser device including a fluid reservoir, said device being characterized in that it further includes a pump according to claim 1 .