Hydraulic pump with double direction of rotation

Abstract

A hydraulic pump with two rotation directions has axial pistons bearing against a swashplate, the pump with a head having two chambers to be connected to a high-pressure circuit and to a low-pressure circuit. A port plate in the form of a flat plate is arranged between a rotary barrel and the head and has two identical ports passing through the thickness of the flat plate. The port plate pivots about an axis to be able to occupy two angular positions according to the direction of rotation of the pump. The pump has a hydraulic-control device for controlling the angular position of the port plate and is able automatically to bring about a change in angular position of the port plate when the direction of rotation of the pump is reversed, under the effect of a pressure differential between the two chambers of the head.

1 . A hydraulic pump with two directions of rotation, comprising axial pistons ( 1 ) bearing against a swashplate ( 2 ), the pump comprising a rotary barrel ( 20 ) rotated by a shaft ( 21 ) and bearing cylinders ( 1   a ) in which the pistons ( 1 ) slide, the pump comprising a head ( 40 ) comprising two chambers ( 49 ) which are intended respectively to be connected to a high-pressure circuit and to a low-pressure circuit, the pump porting being performed by a port plate ( 3 ) defining an intake port and a delivery port, each cylinder ( 1   a ) being equipped at its base with an orifice ( 4 ) which passes in succession past the intake port and the delivery port as the barrel ( 20 ) rotates, the pump comprising
 a hydraulic-control device ( 38 ,  39 ,  42 ) for controlling the angular position of the port plate ( 3 ) and able automatically to bring about a change in angular position of the port plate when the direction of rotation of the pump is reversed, under the effect of the pressure differential between the two chambers ( 49 ) of the head ( 40 ),   characterized in that the port plate ( 3 ) is produced in the form of a flat plate arranged between the rotary barrel ( 20 ) and the head ( 40 ), the port plate ( 3 ) having two identical ports ( 22 ,  23 ) passing through the thickness of the flat plate and arranged facing two chambers ( 49 ) of the head and able to constitute the intake port and the delivery port in each direction of rotation of the pump, said port plate ( 3 ) being able to pivot about an axis ( 21 ) so as to be able to occupy two angular positions according to the direction of rotation of the pump,   the hydraulic control device comprising a free piston ( 38 ) mounted in a cylinder ( 39 ) which is connected at each of its ends to one of the two chambers ( 49 ) of the head ( 40 ).   
     
     
         2 . The hydraulic pump as claimed in  claim 1 , in which the free piston ( 38 ) is provided with a finger ( 37 ) the end of which is engaged in a housing ( 36 ) formed at the periphery ( 35 ) of the port plate ( 3 ). 
     
     
         3 . (canceled)