Servocontrol valve and system

Claim 2

A hydraulic servo control valve comprising a casing having a bore therein, a spool slidably mounted in said bore and movable between a central neutral position to two extreme positions on each side respectively of said neutral position, said casing having a pressure inlet port and two control ports on each side respectively of said pressure inlet port, said spool having a central control portion and two annular sealing portions on each side respectively of said central control portion, an internal annular groove in said bore aligned with said pressure inlet port and of width slightly greater than said central control portion, said central control portion having opposed edges slightly spaced from the adjacent edges of said annular groove to provide restricted flow between said pressure inlet port and both said control ports when said spool is in neutral position, said casing having two fluid returns return ports, said annular sealing portions of said spool controlling communication between said control ports and the associated return port on the same side of the inlet port and normally cutting off flow between both of said return ports and said pressure inlet port when said spool is in neutral position, the travel of the spool from neutral position toward each extreme point and corresponding movement of the central control portion cutting off communication between the inlet port and the associated control port prior to opening communication between the return port and said control port.

Claim 3

A hydraulic servo control valve comprising a casing having a bore therein, a spool slidably mounted in said bore and movable between a central neutral position to two extreme positions on each side respectively of said neutral position, said spool having two spaced annular grooves defining a central control portion therebetween and two end control portions, said casing having two control ports in communication respectively with said annular grooves in all positions of said spool, and an annular groove means betwEen said control ports defining a pressure inlet aligned with said central control portion of said spool in neutral position, the opposed edges of said central control portion being located inwardly from the side edges of said pressure inlet groove means and slightly spaced laterally therefrom, whereby both of said annular grooves will be in communication with said pressure inlet port in neutral position of said spool and one of said two control ports will be in communication with the associated annular groove and said pressure inlet in all positions of said spool, said casing having two annular grooves aligned respectively with and closed by the end control portions of said spool when the latter is in neutral position and defining fluid return outlets, the distance between the inner edge of each of said return annular grooves and the inner edge of the associated end control portion being greater than the distance between the edge of the central control portion and the adjacent edge of the pressure inlet groove means and means to effect movement of said spool to either side of its neutral position.

Claim 4

A hydraulic servo control valve comprising a casing having a bore therein, a spool slidably mounted in said bore and movable between a central neutral position to two extreme positions on each side respectively of said neutral position, said spool having two spaced annular grooves defining a central control portion therebetween and two end control portions, said casing having two control ports in communication respectively with said annular grooves in all positions of said spool, and an annular groove means betwEen said control ports defining a pressure inlet aligned with said central control portion of said spool in neutral position, the opposed edges of said central control portion being located inwardly from the side edges of said pressure inlet groove means and slightly spaced laterally therefrom, whereby both of said annular grooves will be in communication with said pressure inlet port in neutral position of said spool and one of said two control ports will be in communication with the associated annular groove and said pressure inlet in all positions of said spool, said casing having two annular grooves aligned respectively with and closed by the end control portions of said spool when the latter is in neutral position and defining fluid return outlets, the distance between the inner edge of each of said return annular grooves and the inner edge of the associated end control portion being greater than the distance between the edge of the central control portion and the adjacent edge of the pressure inlet groove means and means to effect movement of said spool to either side of its neutral position.

Claim 5

The combination set forth in claim 2 in which each of said end control portions between its inner and outer edge has a reduced diameter portion defining an annular capillary recess of length greater than the distance between the inner edge of the associated end control portion and the outer edge of the associated return annular groove when the spool is in neutral position.

Claim 6

The combination set forth in claim 3 in which the diameter of the end control portion is just slightly smaller than the diameter of said bore to define a sliding fit therein, said reduced diameter portion is slightly spaced from the inner edge of each end control portion to define a guide rim at each of such inner ends, said rims each having passageways therethrough leading from the associated annular groove into the recess defined by said reduced diameter portion.

Claim 7

A servocontrol valve comprising a casing having a bore therein, a spool slidably mounted in said bore and movable between a central neutral position to two extreme positions on each side respectively of said neutral position, said spool having two spaced annular grooves defining a central control portion therebetween and two end portions, said central control portion comprising two spaced annular sealing portions defining a central annular groove therebetween, said casing having two pairs of spaced annular grooves aligned respectively with said spaced annular sealing portions when said spool is in neutral position, said casing having two control ports in communication respectively with each pair of spaced annular grooves, and a pressure inlet port in communication with the central annular groove in said spool in all positions of said spool, the opposed inner edges of said annular sealing portions adjacent the central annular groove being located inwardly from the inner edge of the adjacent one of each pair of spaced annular grooves to define a relatively narrow passageway between the central annular grooves when the spool is in neutral position, the outer edges of each of said annular sealing portions extending beyond the outer edge of the other annular groove of each pair of annular grooves when the spool is in neutral position, said casing having two return ports in communication respectively with each of said first pair of annular grooves in all positions of said spool, the distance between the inner edges of each of said annular sealing portions and the inner edge of the associated annular groove being less than the distance between the outer edge of each of said annular sealing portions and the outer edge of the associated annular groove and means to effect movement of said spool to either side of its neutral position.

Claim 8

A servocontrol valve comprising a casing having a bore therein, a spool slidably mounted in said bore and movable between a central neutral position to two extreme positions on each side respectively of said neutral position, said spool having two spaced annular grooves defining a central control portion therebetween and two end portions, said central control portion comprising two spaced annular sealing portions defining a central annular groove therebetween, said casing having two pairs of spaced annular grooves aligned respectively with said spaced annular sealing portions when said spool is in neutral position, said casing having two control ports in communication respectively with each pair of spaced annular grooves, and a pressure inlet port in communication with the central annular groove in said spool in all positions of said spool, the opposed inner edges of said annular sealing portions adjacent the central annular groove being located inwardly from the inner edge of the adjacent one of each pair of spaced annular grooves to define a relatively narrow passageway between the central annular grooves when the spool is in neutral position, the outer edges of each of said annular sealing portions extending beyond the outer edge of the other annular groove of each pair of annular grooves when the spool is in neutral position, said casing having two return ports in communication respectively with each of said first pair of annular grooves in all positions of said spool, the distance between the inner edges of each of said annular sealing portions and the inner edge of the associated annular groove being less than the distance between the outer edge of each of said annular sealing portions and the outer edge of the associated annular groove and means to effect movement of said spool to either side of its neutral position.

Claim 9

The combination set forth in claim 5 in which each of said sealing portions between its inner and outer edges and its central annular rim has a reduced diameter portion defining an annular capillary recess.