Hydraulic device

Abstract

Hydraulic device such as a motor or a pump comprising a first assembly of parts ( 1 C) including a housing part, and a second assembly of parts ( 1 D) fixed to said first assembly. Said assemblies present respectively a first and a second contact face ( 1 C′, 1 D′), which are stressed towards each other and placed in mutual contact by means ( 15 ) exerting axial stress. One at least of the first and second contact faces has a rough friction surface. Because of the latter, high torque can be transmitted between the two assemblies. Production process for such a hydraulic device.

1 . A hydraulic device such as a motor or a pump comprising a first assembly of parts comprising a housing part wherein is arranged a cylinder block, and a second assembly fixed to said first assembly,
 said assemblies having respectively a first and a second contact face, the two contact faces being pushed towards each other and placed in mutual contact by means exerting axial stress,   wherein at least one of said first and second contact faces has a rough friction surface for transmission of high torque between the two assemblies.   
     
     
         2 . The device as claimed in  claim 1 , wherein said first assembly also comprises a fastening plate;
 said first and second contact faces are formed respectively on walls opposite said fastening plate and said second assembly;   also, a third and a fourth contact face are formed respectively on walls opposite said housing part and said fastening plate; and   one of said third and fourth contact faces has a rough friction surface for transmission of high torque between said housing part and said fastening plate.   
     
     
         3 . The device as claimed in  claim 2 , wherein said friction surfaces are aligned axially on either side of the fastening plate. 
     
     
         4 . The device as claimed in  claim 2 , wherein the second and/or the third contact face has an uptake recess for the plate provided to receive the fastening plate. 
     
     
         5 . The device as claimed in  claim 4 , wherein one only of the second and the third contact faces comprises an uptake recess for the plate, the other contact face being provided a recess. 
     
     
         6 . The device as claimed in  claim 2 , wherein the plate is a washer arranged about an axis of rotation of the device. 
     
     
         7 . The device as claimed in  claim 1 , wherein said friction surface or one of said friction surfaces has a roughness index Ra greater than 12 μm or a roughness index Rz greater than 80 μm. 
     
     
         8 . The device as claimed in  claim 1 , wherein the projecting parts on said friction surface or on at least one of said friction surfaces are pointed. 
     
     
         9 . The device as claimed in  claim 1 , wherein said friction surface or at least one of said friction surfaces has a Vickers hardness greater than 450 HV. 
     
     
         10 . The device as claimed in  claim 1 , wherein at least one contact face placed opposite a friction surface has a surface hardness less than that of said friction surface. 
     
     
         11 . The device as claimed in  claim 1 , wherein the device comprises sealing means to prevent radial fluid passage between two contact faces in mutual contact. 
     
     
         12 . The device as claimed in  claim 11 , wherein the sealing means comprise at least one sealing joint, arranged so as to create sealing between both a plane surface and also a groove formed in a contact face and arranged so as to receive said sealing joint and allow deformation of the latter. 
     
     
         13 . The device as claimed in  claim 11 , wherein the sealing means comprise a joint interposed between the second and the third contact face and placed directly in contact with each of these faces. 
     
     
         14 . A production process of a hydraulic device comprising the following steps:
 a) a first and a second assembly of parts are provided, such that:
 the two assemblies are capable of being fixed to each other to constitute a hydraulic device such as a motor or a pump, 
 the two assemblies present respectively a first and a second contact face, 
 the first assembly comprises a housing part wherein is arranged a cylinder block; 
   d) the two assemblies are assembled so as to place the two contact faces in mutual contact by means of means exerting axial stress,   the process wherein it also comprises a following step b):   b) a rough friction surface is formed on one of said contact faces to enable transmission of high torque between the two assemblies.   
     
     
         15 . The production process as claimed in  claim 14 , also comprising after step b) the following step c):
 c) surface treatment increasing the surface hardness of the friction surface is carried out such that the contact face placed opposite said friction surface has a surface hardness of less than that of the friction surface.