Hydraulic actuator

Claim 2

A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, and elongated actuator element extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely on said actuator element and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, a separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator element and associated piston to retract under the force of said biasing means and to maintain said actuator element at any one of said plurality of discrete positions when said bleed passage is closed and means for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator element is located for use in the selective operation of said pump means and the selective operation of said dump valve means.

Claim 3

A hydraulic actuator as defined in claim 1, wherein said pump means comprises a pump unit having an inlet in communication with said first chamber and an outlet in communication with said passageway, and check valve means to prevent the flow of fluid from said expandable chamber into said first chamber.

Claim 4

A hydraulic actuator as defined in claim 2, wherein said pump means further comprises an electric motor for operating said pump unit, whereby the energization of said motor is effected by said variable control signal.

Claim 5

A hydraulic actuator as defined in claim 2, wherein said pump unit comprises at least three plates stacked together in a side-by-side abutting relation to define a pump housing, one of middle of said plate including a central recess having two pairs of opposing arcuate portions, a pair of pump gears in intermeshing relation rotatably mounted between the two end plates and nested within one of said pairs of opposing arcuate portions, and a pair of openings formed through one of said end plates in alignment with said other pairs of opposing arcuate portions to define pump inlet and outlet.

Claim 6

A hydraulic actUator as defined in claim 1, wherein said position sensing means comprises a transformer coil having an axial opening disposed in the path of said actuator element and having a cross sectional area larger than the cross section of said actuator element, and wherein said actuator element comprises a non-magnetic permeable length portion and a magnetic permeable length portion.

Claim 7

A hydraulic actuator as defined in claim 5, wherein said magnetic permeable length portion includes a tapered nose segment.

Claim 8

A hydraulic actuator as defined in claim 1, wherein said dump valve means comprises a core member having an axial opening disposed in said first chamber, a valve fitting mounted in one end of said axial opening of said core member, a plunger slidably mounted inwardly of the other end of said axial opening, a ball valve disposed in said axial opening between said fitting and said plunger, an armature member carried on said plunger outwardly of said axial opening, and a field coil disposed about said core member and producing sufficient magnetic force when energized to attract said armature causing said plunger to move against said ball valve with sufficient force to close the port in said valve fitting.

Claim 9

A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, an elongated actuator means including a magnetic permeable length portion member extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely on said actuator means and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, a separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator means and said piston to retract under the force of said biasing means and alternatively to maintain said actuator means at any one of said plurality of discrete positions when said bleed passage is closed, said actuator means being extensible to a different one of said plurity of positions in response to selective operation of said pump means and closing of said dump valve means, and means operative with said magnetic member for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator means is located for use in the selective operation of said pump means and the selective operation of said dump valve means.

Claim 10

A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, an elongated actuator means including a magnetic permeable length portion member extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely on said actuator means and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, a separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator means and said piston to retract under the force of said biasing means and alternatively to maintain said actuator means at any one of said plurality of discrete positions when said bleed passage is closed, said actuator means being extensible to a different one of said plurity of positions in response to selective operation of said pump means and closing of said dump valve means, and means operative with said magnetic member for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator means is located for use in the selective operation of said pump means and the selective operation of said dump valve means.

Claim 11

A hydraulic actuator as defined in claim 8, wherein said pump means comprises a pump unit having an inlet in communication with said first chamber and an outlet in communication with said first passageway, and check valve means to prevent the flow of fluid from said expandable chamber into said first chamber.

Claim 12

A hydraulic actuator as defined in claim 9, wherein said pump means further comprises an electric motor for driving said pump unit, whereby the energization of said motor is effected by said variable control signal.

Claim 13

A hydraulic actuator as defined in claim 9, wherein said pump unit comprises three plates stacked together in side-by-side abutting relation to define a pump housing, the middle of said plate including a central cloverleaf-recess having two pairs of opposing arcuate portions, a pair of pump gears in intermeshing relation rotatably mounted between the two end plates and nested within one of said pairs of opposing arcuate portions, and a pair of openings formed through one of said end plates in alignment with said other pairs of opposing arcuate portions to define a pump inlet and outlet.

Claim 14

A hydraulic actuator as defined in claim 8 wherein said means comprises a transformer coil having an axial opening disposed in the path of said actuator means and having a cross sectional area larger than the cross section of said actuator means to accommodate the movement of said actuator means relative to said transformer coil.

Claim 15

A hydraulic actuator as defined in claim 12, wherein said magnetic permeable length portion includes a tapered segment.

Claim 16

A hydraulic actuator as defined in claim 8, wherein said dump valve means comprises a core member having an axial opening disposed in said first chamber, a valve fitting mounted in said second passageway, a plunger slidably mounted inwardly of the other end of said axial opening, a ball valve disposed in said axial opening between said fitting and said plunger, an armature member carried on said plunger outwardly of said axial opening, and a field coil disposed about said core member and producing sufficient magnetic force when energized to attract said armature causing said plunger to move against said ball valve with sufficient force to close the port in said valve fitting.

Claim 17

A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, an elongated actuator means including a magnetic permeable length portion extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely of said actuator means and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, s separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator means and said piston to retract under the force of said biasing means and to maintain said actuator means at any one of said plurality of discrete positions when said bleed passage is closed, and means operatively connected with said pump means and said dump valve means including a transformer in said second chamber for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator means is located in response to sliding movement of said magnetic member, both said pump means and said dump valve means when energized effecting movement of said actuator means to at least one of said plurality of discrete desired positions as well as effecting movement of said magnetic member toward said transformer to provide a correspondingly different value control signal for use in repositioning said actuator means, said actuator means being maintained at a desired one of said plurality of discrete positions when said pump means is deenergized and said dump valve means is energized, subsequent deenergization of said dump valve means opening said bleed passage to effect movement of said actuator means and said magnetic member by said biasing means toward another of said plurality of discrete positions and the output of a correspondingly different signal by said transformer with such movement.

Claim 18

A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, an elongated actuator means including a magnetic permeable length portion extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely of said actuator means and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, s separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator means and said piston to retract under the force of said biasing means and to maintain said actuator means at any one of said plurality of discrete positions when said bleed passage is closed, and means operatively connected with said pump means and said dump valve means including a transformer in said second chamber for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator means is located in response to sliding movement of said magnetic member, both said pump means and said dump valve means when energized effecting movement of said actuator means to at least one of said plurality of discrete desired positions as well as effecting movement of said magnetic member toward said transformer to provide a correspondingly different value control signal for use in repositioning said actuator means, said actuator means being maintained at a desired one of said plurality of discrete positions when said pump means is deenergized and said dump valve means is energized, subsequent deenergization of said dump valve means opening said bleed passage to effect movement of said actuator means and said magnetic member by said biasing means toward another of said plurality of discrete positions and the output of a correspondingly different signal by said transformer with such movement.

Claim 19

A hydraulic actuator comprising a housing having at least a first chamber, an expandable chamber, and a biased actuator means extending in said first chamber for selective positioning at a plurality of discrete positions, pump means for introducing fluid under pressure into said expandable chamber to enable movement of said actuator means in a first direction including first input means for providing energizing power to said pump means, a separate dump valve means for selectively enabling fluid to be bled from said expandable chamber to permit movement of said biased actuator means in an opposite direction, and alternatively for selectively preventing bleeding of the fluid from said expandable chamber to maintain said biased actuator means at any one of said plurality of discrete positions including second input means for providing energizing power to said dump valve means, said biased actuator means being movable in said first direction towards a different one of said plurality of discrete positions in response to simultaneous energization of said pump means and said dump valve means, said actuator means being held at said different position with deenergization of said pump means, and means for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said biased actuator means is located in response to movement of said biased actuator means in either of said first or opposite directions.

Claim 20

A hydraulic actuator comprising a housing having at least a first chamber, an expandable chamber, and a biased actuator means extending in said first chamber for selective positioning at a plurality of discrete positions, pump means for introducing fluid under pressure into said expandable chamber to enable movement of said actuator means in a first direction including first input means for providing energizing power to said pump means, a separate dump valve means for selectively enabling fluid to be bled from said expandable chamber to permit movement of said biased actuator means in an opposite direction, and alternatively for selectively preventing bleeding of the fluid from said expandable chamber to maintain said biased actuator means at any one of said plurality of discrete positions including second input means for providing energizing power to said dump valve means, said biased actuator means being movable in said first direction towards a different one of said plurality of discrete positions in response to simultaneous energization of said pump means and said dump valve means, said actuator means being held at said different position with deenergization of said pump means, and means for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said biased actuator means is located in response to movement of said biased actuator means in either of said first or opposite directions.