Patent EP-0091348-A1 (EP)
Inventor: TANGUY CHRISTIAN
IPC: B60T13/18
Filed: 1983-03-24
Abstract: 1. Flow regulator for a hydraulic circuit comprising a reservoir (12) and a pressure generator (10), the delivery conduit (14, 16) of which is connected, on the one hand, to the inlet of a make-break switch (26), a first outlet of which permanently connects a closed-centre assistance device possessing a pressure accumulator (24) to the said pressure generator and a second outlet (28) of which is in communication with the said pressure generator (10), when the pressure prevailing in the said accumulator (24) is higher than a specific lower limit, and, on the other hand, to an inlet (60) of the said flow regulator (32), one outlet (44) of which is intended to be connected to an open-centre assistance device (22), the said flow regulator (32) comprising a housing (34) in which are formed : a first cavity (36), of which one end, called the upper end, is connected to the said second outlet (28) of the said make-break switch (26) and of which the other end, called the lower end, is connected to the said outlet (44) of the said flow regulator, having a first passage (50) opening out in the wall of the said first cavity (36) and connected to the said reservoir (12), a main regulator slide (56) defining a first throttle (sigma 1 ) between the ends of the said first cavity (36) and mounted slidably in the said first cavity (36), and a first spring (58) pushing the said slide (56) away from the said lower end into a rest position, in which the said slide (56) masks the said first passage (50), the characteristics of the first throttle (sigma 1 ), of the main slide (56) and of the first spring (58) being selected for the purpose of maintaining a predetermined nominal flow (Q2 ) through the said first throttle (sigma 1 ) ; a second cavity (38), of which one end, called the upper end, is connected to the said inlet (60) of the said flow regulator, having a second passage (62) opening out in the wall of the said second cavity (38) and connected to the upper end of the said first cavity (36), an additional regulator slide (64) defining a second throttle (sigma 2 ) between the ends of the said second cavity (38) and mounted slidably in the said second cavity (38), and a second spring (66) pushing the said additional slide (64) towards the said upper end into a rest position, in which the said additional slide (64) exposes the said second passage (62), the characteristics of the second throttle (sigma 2 ), of the additional slide (64) and of the second spring (66) being selected for the purpose of maintaining a predetermined reduced flow (Q1 ) through the said second throttle (sigma 2 ) ; a third cavity (40), of which one end, called the upper end, is connected to the said inlet (60) of the said flow regulator and of which the other end, called the lower end, is connected to the said reservoir (12), having a third passage (68) opening out in the wall of the said third cavity (40) and connected to the lower end of the second cavity (38), a valve slide (70) mounted slidably in the said third cavity (40), and a valve spring (72) pushing the said valve slide (70) towards the said upper end into a rest position, in which the said valve slide masks the said third passage (68), a third throttle (sigma 3 ) being provided between the said upper end and the said valve slide (70).