Disconnecting valve mechanism for a servo-steering system of vehicles

Claim 2

An installation for disconnecting the servo force in a vehicle power steering unit, comprising: a housing, a working piston disposed in said housing dividing same into two working pressure spaces, a steering shaft operated by said working piston, passage means for interconnecting said two working pressure spaces, a pair of normally closed by-pass valve means disposed in said interconnecting means and opening into the same working pressure space with each by-pass valve means having an actuating means in said same working pressure space for opening said interconnecting means to said same working pressure space upon actuation, and means movable by said steering shaft for maintaining said by-pass valve means in said normally closed position and for opening one of said by-pass valve means when said working piston is in one end position and for opening the other of said pair of by-pass valve means when said piston is in the opposite end position, whereby said by-pass valve means, in their respective by-pass position, communicate with said interconnecting means to disconnect the servo force in the steering unit.

Claim 3

An installation according to claim 1, characterized in that said passage means is a by-pass channel.

Claim 4

An installation according to claim 1, wherein each of said actuating means includes a bushing, a spring loaded adjusting member disposed in said bushing cooperating with said control means, means on said adjusting members for defining with said bushing a longitudinal channel closed at one end and extending in the axial direction of said bushing, shoulder means on said adjusting members, cooperating, with said bushings for closing the other end of said longitudinal channel whereby, in response to said control means, said channel is opened by said adjusting members being displaced under spring force out of said bushing.

Claim 5

An installation according to claim 1, wherein said by-pass valve means are mutually offset in the circumferential direction of said steering shaft, said means for maintaining and opening said by-pass valve means includes a control cam fixed with respect to the steering shaft having three sections circumferentially disposed, a first section of said control cam having an essentially constant radius over a predetermined circumferential distance with respect to the axis of the steering shaft, the remaining sections disposed on each side of said first section, having different distances with respect to said axis, and wherein said actuating means each include an adjusting member in direct engagement with said control cam whereby when said adjusting members engage the first section of said control cam the passage means are closed, whereas, within the areas of the remaining sections of said control cam, only the adjusting member adjacent in the circumferential direction to one of the remaining sections opens the passage means while the other adjusting member continues to remain in operative engagement with the first section of said control cam.

Claim 6

An installation according to claim 4, further comprising a control valve means for controlling the working pressure in said two working pressure spaces, supporTed in proximity of the steering shaft, said control valve means including a chamber, means for communicating said by-pass valve means with said chamber of said control valve means which is in constant communication with the other working pressure space.

Claim 7

An installation according to claim 5, wherein said control valve means and said by-pass valve means are arranged substantially perpendicularly to one another.

Claim 8

An installation according to claim 5, including a valve housing for each of said by-pass valve means, wherein a movement of the adjusting member of at least one by-pass valve means is directed toward a working pressure space and abutment means for limiting said movement are provided between said at least one adjusting member and the valve housing.

Claim 9

An installation according to claim 7, wherein said abutment means includes a notched pin and a collar.

Claim 10

An installation according to claim 8, wherein said control valve means and by-pass valve means are arranged substantially perpendicularly to one another.

Claim 11

An installation according to claim 9, wherein said passage means is a by-pass channel.

Claim 12

An installation according to claim 1, further comprising a control valve means for controlling the working pressure in said two working pressure spaces, supported in proximity of a steering shaft, means for communicating said by-pass valve means with said control valve means, and additional communication means for maintaining a constant communication between said control valve and the other working pressure space.

Claim 13

An installation according to claim 11, wherein said control valve means and said by-pass valve means are arranged substantially perpendicularly to one another.

Claim 14

An installation according to claim 1, including a valve housing for each of said by-pass valve means, wherein said actuating means includes an adjusting member, wherein movement of the adjusting member of at least one by-pass valve means is directed toward a working pressure space and abutment means for limiting said movement are provided between said at least one adjusting member and the valve housing.

Claim 15

An installation according to claim 13, wherein said abutment means includes a notched pin and a collar.

Claim 16

An installation for effectively turning off the servo force in a servo steering system, comprising: a working cylinder, a working piston arranged in said cylinder and defining two working pressure spaces, a steering shaft operatively connected to said working piston displaceable between two end portions, a by-pass line operatively connected to said two working spaces, a pair of normally closed by-pass valve means arranged in said by-pass line and opening into the same working pressure space, each of said by-pass valve means having an actuating means in said same working space for opening said by-pass line to said same working pressure space upon actuation, and control means movable by said steering shaft for maintaining said by-pass valve means in said normally closed position and for opening one of said by-pass valve means as said working piston approaches one of said two end positions and for opening the other of said by-pass valve means as said piston approaches the other of said two end positions thereby selectively turning off the servo force in the servo-steering system.

Claim 17

An installation for effectively turning off the servo force in a servo steering system, comprising: a working cylinder, a working piston arranged in said cylinder and defining two working pressure spaces, a steering shaft operatively connected to said working piston displaceable between two end portions, a by-pass line operatively connected to said two working spaces, a pair of normally closed by-pass valve means arranged in said by-pass line and opening into the same working pressure space, each of said by-pass valve means having an actuating means in said same working space for opening said by-pass line to said same working pressure space upon actuation, and control means movable by said steering shaft for maintaining said by-pass valve means in said normally closed position and for opening one of said by-pass valve means as said working piston approaches one of said two end positions and for opening the other of said by-pass valve means as said piston approaches the other of said two end positions thereby selectively turning off the servo force in the servo-steering system.

Claim 18

An installation according to claim 15, wherein only a single by-pass line is used which contains both said by-pass valve means.

Claim 19

An installation according to claim 15, wherein said control means includes a control surface substantially coincident with the axis of said steering shaft and rotatable in unison therewith, said pair of by-pass valve means being arranged in spaced relationship along the circumference said control surface.

Claim 20

An installation according to claim 17, wherein said control surface includes a control cam, non-rotatably connected with said steering shaft, having a central section of substantially constant radial dimension and two end sections of a Radial dimension differing from said constant radial dimension, a respective by-pass valve means being displaced into its opening position when in engagement with a respective end section of the control cam.

Claim 21

An installation according to claim 18, wherein said by-pass line is in constant communication with one of said working pressure spaces and includes a control valve means for controlling the working pressure in said working pressure spaces.

Claim 22

An installation according to claim 15, wherein said control means includes a control cam, non-rotatably connected with said steering shaft, having a central section of substantially constant radial dimension and two end sections of a radial dimension differing from said constant radial dimension, a respective by-pass valve means being displaced into an open position when in engagement with a respective end section of the control cam.

Claim 23

An installation according to claim 15, wherein said by-pass line is in constant communication with one of said working pressure spaces and includes a control valve means for controlling the working pressure spaces.

Claim 24

An installation according to claim 18, wherein each of said actuating means includes a bushing having disposed therein a spring loaded adjusting member, means on said adjusting member for defining with said bushing a longitudinal channel, closed at one end, in the axial direction of said bushing, means on said adjusting member cooperating with said bushings for closing the other end of said channel whereby said longitudinal channel is opened when a respective adjusting member engages a respective end section of said control cam and is displaced under the spring force out of said bushing.

Claim 25

An installation according to claim 15 wherein said control means includes a control surface coincident with the axis of said steering shaft and rotatable therewith, and wherein each of said actuating means includes a bushing, a spring loaded adjusting member, disposed in said bushings, engageable with said control surface, means on said adjusting member for defining with said bushing a longitudinal channel closed at one end and extending in the axial direction of said bushing, shoulder means on said adjusting members, cooperating with said bushings, for closing the other end of said longitudinal channel whereby, in response to a predetermined movement of said control surface, said longitudinal channel is opened by said adjusting members being displaced under spring force out of said bushings.