Pump mechanism
A prosthetic system includes a prosthetic foot with a foot member defining a first end portion, a second end portion, and an intermediate portion defining a curvature and extending between the first and second end portions. A pump mechanism is coupled to the foot member. The pump mechanism includes a housing defining a cavity, and a membrane situated in the cavity. The pump mechanism is movable between an original configuration and an expanded configuration. A movable member includes a first portion coupled to the membrane and a second portion arranged to slidably engage the foot member. Relative movement between the first and second end portions moves the first portion of the movable member relative to the housing and slides the second portion along a length of the foot member to shift the pump mechanism between the original and expanded configurations.
1 . A pump mechanism for connecting to a prosthetic foot, the pump mechanism comprising:
a housing having an interior cavity;
a one-way valve assembly connecting to the housing and in fluid communication with the interior cavity;
a first membrane located at least in part within the interior cavity;
a first connector engaging the first membrane and protruding outside the interior cavity;
a first movable member connected to the first connector and arranged to engage the prosthetic foot;
wherein the first membrane is movable between an original configuration in which volume of a first fluid chamber defined between the first membrane and a bottom of the interior cavity is zero or near-zero, and an expanded configuration in which the volume of the first fluid chamber is increased; and
wherein relative movement of the first movable member against the prosthetic foot pulls the first membrane by the first connector to draw fluid through the one-way valve assembly.
2 . The pump mechanism of claim 1 , wherein the first connector includes an upper radial flange above the first membrane, a lower radial flange embedded in the first membrane, and a shaft portion extending between the upper and lower radial flanges.
3 . The pump mechanism of claim 2 , wherein the first and second membranes are located on opposite sides of the housing.
4 . The pump mechanism of claim 1 , wherein an upper surface of the housing complements a lower surface of the prosthetic foot, an anterior surface of the housing is curved between the upper surface and a lower surface of the housing, a posterior surface of the housing is curved between the upper and lower surfaces of the housing.
5 . The pump mechanism of claim 4 , wherein the anterior surface of the housing defines a first cavity within the interior cavity that is provided with an undercut circumferential groove between an open end of the first cavity and a closed bottom of the first cavity, an outer radial edge of the first membrane is situated in the circumferential groove such that a seal is formed between the first membrane and the housing.
6 . The pump mechanism of claim 1 , wherein the first movable member is a plate including a first portion connecting to the prosthetic foot, and a second portion connecting to the housing.
7 . The pump mechanism of claim 6 , wherein when the pump mechanism is arranged so that when the prosthetic foot is in a resting position, the first membrane is in the original configuration, whereupon heel strike, the prosthetic foot moves into expansion, which, in turn, moves the first membrane to an expanded configuration by the first movable member having a radius of curvature arranged to increase upon heel strike.
8 . The pump mechanism of claim 7 , wherein the increase of the radius of curvature or straightening out of the first movable member is arranged to pull the first membrane away from the housing to deform the first membrane between the first movable member and the housing, thereby increasing the volume of the first fluid chamber and creating a vacuum in the first fluid chamber of the pump mechanism by pulling fluid into the first fluid chamber through the one-way valve assembly.
9 . The pump mechanism of claim 8 , wherein the pump mechanism is arranged so that as the prosthetic foot moves from heel strike back toward a resting position, the first movable member returns to an un-flexed state, moving the first membrane back toward the original configuration and decreasing the volume of the first fluid chamber to a zero or near-zero volume, whereupon during the return of the first membrane toward the housing, the pump mechanism expels fluid from the fluid chambers out of a one-way valve assembly.
10 . The pump mechanism of claim 1 , further comprising:
a second membrane located at least in part within the interior cavity;
a second connector engaging the second membrane and protruding outside the interior cavity;
a second movable member connected to the second connector and arranged to engage the prosthetic foot;
wherein the second membrane is movable between an original configuration in which volume of a second fluid chamber defined between the second membrane and the bottom of the interior cavity is zero or near-zero, and an expanded configuration in which the volume of the second fluid chamber is increased; and
wherein relative movement of the second movable member against the prosthetic foot pulls the second membrane by the second connector to draw fluid through the one-way valve assembly.
11 . The pump mechanism of claim 10 , wherein the second connector includes an upper radial flange above the second membrane, a lower radial flange embedded in the second membrane, and a shaft portion extending between the upper and lower radial flanges.
12 . The pump mechanism of claim 10 , wherein an upper surface of the housing complements a lower surface of the prosthetic foot, an anterior surface of the housing is curved between the upper surface and a lower surface of the housing, a posterior surface of the housing is curved between the upper and lower surfaces of the housing.
13 . The pump mechanism of claim 12 , wherein the anterior surface of the housing defines a second cavity that is provided with an undercut circumferential groove between an open end of the second cavity and a closed bottom of the second cavity, an outer radial edge of the second membrane is situated in the circumferential groove such that a seal is formed between the second membrane and the housing.
14 . The pump mechanism of claim 10 , wherein the second movable member is an elongated plate extending at an angle between the prosthetic foot and the second membrane.
15 . The pump mechanism of claim 14 , wherein the second movable member includes a first portion arranged to engage a dorsal aspect of the prosthetic foot, and a second portion coupled to the second membrane via the second connector.
16 . The pump mechanism of claim 15 , wherein the second movable member is arranged to slide along a length of the prosthetic foot without flexing or bending the second movable member, thereby leaving the second membrane in the original configuration.
17 . The pump mechanism of claim 15 , wherein an edge of the housing is arranged to apply a downward force on the second movable member and the second movable member is arranged so that an upward force is urged by prosthetic foot to cause the second movable member to pivot around the edge of the housing, which, in turn, moves the second portion of the second movable member to move away from the housing.
18 . The pump mechanism of claim 17 , wherein the second movable member is arranged so that as the second portion moves away from the housing, the second movable member pulls the second membrane away from the housing, moving the second membrane to the expanded configuration and increasing the volume of the second fluid chamber to pull fluid into the pump mechanism through the one-way valve assembly.
19 . A pump mechanism for connecting to a prosthetic foot, the pump mechanism comprising:
a housing having an interior cavity;
a one-way valve assembly connected to the housing and in fluid communication with the interior cavity;
a first membrane located at least in part within the interior cavity;
a first connector engaging the first membrane and protruding outside the interior cavity;
a first movable member connected to the first connector and arranged to engage the prosthetic foot, wherein relative movement of the first movable member against the prosthetic foot pulls the first membrane by the first connector to draw fluid through the one-way valve assembly;
a second membrane located at least in part within the interior cavity;
a second connector engaging the second membrane and protruding outside the interior cavity;
a second movable member connected to the second connector and arranged to engage the prosthetic foot, wherein relative movement of the second movable member against the prosthetic foot pulls the second membrane by the second connector to draw fluid through the one-way valve assembly; and
wherein the first and second membranes are located on opposite sides of the housing, and the first and second connectors connecting to the first and second movable members.
20 . A pump mechanism for connecting to a prosthetic foot, the pump mechanism comprising:
a housing having an interior cavity;
a one-way valve assembly connected to the housing and in fluid communication with the interior cavity;
a first membrane located at least in part within the interior cavity and formed by an elastomeric material;
a first connector engaging the first membrane and protruding outside the interior cavity, the first connector including an upper radial flange above the first membrane, a lower radial flange embedded in the first membrane, and a shaft portion extending between the upper and lower radial flanges;
a first movable member connected to the first connector and arranged to engage the prosthetic foot, the first movable member being a plate including a first portion connecting to the prosthetic foot, and a second portion connecting to the housing, the first movable member having a radius of curvature adapted to vary according to movement by the prosthetic foot; and
wherein the pump mechanism is arranged so that when prosthetic foot is in a resting position, the first membrane is in an original configuration, wherein upon heel strike, the prosthetic foot moves into expansion, which, in turn, moves the first membrane to an expanded configuration by the radius of curvature of the first movable member increasing upon heel strike.