SINGLE-PISTON THREE-POSITION HYDRAULIC ACTUATOR
An actuator assembly includes a housing, a piston disposed within a portion of the housing. The piston has a movable range along a working-axis, and separates a first volume and a second volume within the housing. The assembly also includes a biasing feature disposed within the second volume, where the piston is configured to engage the biasing feature within a first portion of the movable range, and configured to not engage the biasing feature within a second portion of the movable range.
1 . A three-position actuator assembly comprising:
a housing;
a piston disposed within a portion of the housing and having a movable range along a working-axis, the piston separating a first volume and a second volume within the housing; and
a biasing feature disposed within the second volume; the piston configured to engage the biasing feature within a first portion of the movable range, and configured to not engage the biasing feature within a second portion of the movable range.
2 . The actuator assembly of claim 1 , wherein the biasing feature is a first biasing feature, the assembly further comprising a second biasing feature configured to engage the piston throughout the movable range.
3 . The actuator assembly of claim 1 , wherein the biasing feature includes a spring.
4 . The actuator assembly of claim 3 , wherein the biasing feature further includes a contact ring.
5 . The actuator assembly of claim 1 , wherein the housing includes a land, and the biasing feature is configured to apply a force to the land when the piston is in the second portion of the movable range.
6 . The actuator assembly of claim 5 , wherein the housing includes two fluidly connected cavities having different cross-sectional profiles, and wherein the land comprises a shoulder between the two cavities.
7 . The actuator assembly of claim 1 , wherein a pressure difference between the first and second volumes imparts a net hydraulic force to the piston, and a net hydraulic force in a first range causes the piston to assume a first position along the working-axis, a net hydraulic force in a second range causes the piston to assume a second position along the working-axis, and a net hydraulic force in a third range causes the piston to assume a third position along the working-axis.
8 . The actuator assembly of claim 7 , wherein the piston is positionally stable within each of the first, second and third net hydraulic force ranges.
9 . The actuator assembly of claim 7 , wherein one of the positions along the working-axis is within the second portion of the movable range.
10 . The actuator assembly of claim 7 , wherein the housing includes a plurality of apertures, and the pressure gradient is altered by controllably allowing fluid to pass through an aperture.
11 . A three-position actuator for engaging a transmission synchronizer, the actuator comprising:
a housing;
a piston disposed within a portion of the housing and having a movable range along a working-axis, the piston separating a first volume and a second volume within the housing;
a biasing feature disposed within the second volume; the piston configured to engage the biasing feature within a first portion of the movable range, and configured to not engage the biasing feature within a second portion of the movable range; and
an actuator rod coupled with the piston and mechanically connected with a synchronizer gear assembly.
12 . The actuator of claim 11 , wherein the biasing feature is a first biasing feature, the assembly further comprising a second biasing feature configured to engage the piston over the entire range.
13 . The actuator of claim 11 , wherein the biasing feature includes a spring.
14 . The actuator of claim 13 , wherein the biasing feature further includes a contact ring, and wherein the spring is configured to apply a force between the contact ring and the housing.
15 . The actuator of claim 11 , wherein the housing includes a land, and the biasing feature is configured to apply a force to the land when the piston is in the second portion of the movable range.
16 . The actuator of claim 15 , wherein the housing includes two fluidly connected cavities having different cross-sectional profiles, and wherein the land comprises a shoulder between the two cavities.
17 . The actuator of claim 11 , wherein a pressure difference between the first and second volumes imparts a net hydraulic force to the piston, and a net hydraulic force in a first range causes the piston to assume a first position along the working-axis, a net hydraulic force in a second range causes the piston to assume a second position along the working-axis, and a net hydraulic force in a third range causes the piston to assume a third position along the working-axis.
18 . The actuator of claim 17 , wherein one of the positions along the working-axis is within the second portion of the movable range.
19 . The actuator of claim 17 , wherein the housing includes a plurality of apertures, and the pressure gradient is altered by controllably allowing fluid to pass through an aperture.
20 . The actuator of claim 17 , wherein the piston is positionally stable within each of the first, second and third net hydraulic force ranges.