The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Nov. 24, 1992

Filed:

Jul. 08, 1991
Applicant:
Inventor:

Pierre Lebret, Le Chesnay, FR;

Assignee:
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04B / ;
U.S. Cl.
CPC ...
417495 ; 417554 ; 417490 ;
Abstract

The hydraulic pump comprises at least one reciprocating piston (2) sliding in a stationary cylinder (4). The piston (2) comprises, on the same side as the working chamber (10), a cylindrical skirt (22) which has the inside diameter of the cylinder (4) and in which is made at least one first port (18) putting the working chamber (10) in communication with the outer wall of the skirt (22). A second port (24) puts the duct (6) upstream of the valve (12) in communication with the outer wall of the piston (2). Finally, a slot (20) of a length at least equal to the distance separating the ports (18, 24) is made in the cylinder (4) so as to cause these ports (18, 24) to communicate over a specific zone of the reciprocating movement of the piston when the piston is sensibly at mid-stroke.


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