Prosthetic leg with a hydraulic control

• US 4,212,087 A
• Filed: 11/16/1978
• Issued: 07/15/1980
• Est. Priority Date: 11/16/1978
• Status: Expired due to Term

• Current Assignee: Lavaugh L. Mortensen
• Original Assignee: Lavaugh L. Mortensen
• Inventors: Mortensen, LaVaugh L.
• Primary Examiner(s): Frinks, Ronald L.
• Application Number:
  US05/961,114
• Time in Patent Office: 607 Days
• Field of Search: 3/1.2, 3/2, 3/22, 188/313, 188/311, 188/318
• US Class Current: 623/26
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/68 Operating or control means
• CPC Class Codes: A61F 2/74 fluid , i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2/748 Valve systems

Abstract

The hydraulic knee control for a prosthetic leg has a cylinder and piston assembly. In addition, within the cylinder is disposed a free floating plug so that the space between the free plug and the head end is filled with air or a compressible fluid, and the spaces between the free plug and the crank end is filled with a liquid or hydraulic fluid. The piston is disposed within this liquid and has sealing means which prevents the liquid from bypassing therearound. Disposed outside of the cylinder are two bypass passageways wherein one end of each passageway communicates with the cylinder in the region between the piston and crank end and the other end of each passageway communicates with the cylinder in the region between the piston and the floating plug. One of the passageways has a one-way adjustable valve which allows the liquid to move only from the head end to the crank end in a controlled manner, and the other passageway has a one-way adjustable valve which allows the liquid to move only from the crank end to the head end in a controlled manner.

Claims

1. A leg prosthetic comprising:

an upper thigh member;

a lower shank member;

a knee joint pivotably connecting said members; and

first means pivotably connected between said members for control of said knee joint and comprising;

a cylinder having a head end and a crank end, and pin-connected at said head end to one of said members;

a piston slidably disposed within said cylinder with sealing means therebetween;

a connecting rod connected at one end to said piston and extending out of said crank end, and having the other end thereof pin-connected to the other one of said members;

second means for slidably sealing said crank end around said rod;

a first one-way by-pass valve and a second one-way by-pass valve disposed exterior of said cylinder and each having an inlet port and an outlet port;

said cylinder having a first pair of radial ports and a second pair of radial ports, spaced axially from said first pair;

said inlet port of said first valve and said outlet port of said second valve, each communicating with a respective one of said first pair of radial ports;

said outlet port of said first valve and said inlet port of said second valve each communicating with a respective one of said second pair of radial ports; and

hydraulic fluid disposed within said cylinder.

2. The leg prosthetic of claim 1 wherein said first means further comprises:

means within each one of said one-way valves for controlling the rate of flow of said fluid therethrough as said piston slides axially within said cylinder.

3. The leg prosthetic of claim 2 wherein a floating plug is slidably disposed within said cylinder between said piston and said head end;

sealing means are provided between said floating plug and said cylinder so that a compressible fluid is capable of being contained between said floating plug and said head end;

third means is provided to control the pressure of said compressible fluid.

4. The leg prosthetic of claim 3 wherein said third means comprises:

a moveable plug disposed within said cylinder and between said floating plug and said head end;

sealing means for providing a seal between said moveable plug and said cylinder;

an axially aligned screw threaded through said head end and making contact with said moveable plug so that as the screw is threaded into the cylinder said moveable plug moves axially away from said head end.

5. The leg prosthetic of claim 4 wherein said third means further comprises:

a compression spring disposed between said floating plug and said moveable plug;

said floating plug has a well wherein said spring is disposed;

said moveable plug has a protrusion for nesting within said spring and said well so that minimum volume can be obtained between said plugs.

6. The leg prosthetic of claim 1 wherein said second means comprises:

a sleeve disposed within said cylinder and having said rod protruding therethrough;

sealing means disposed between said sleeve and said rod;

said cylinder having an internal circumferential groove disposed near its crank end;

a split ring nested within said groove so that said sleeve is internal of said ring;

an aperture cover covering the end of said crank end and having screws therein for engaging said sleeve;

said sleeve having an external shoulder near its end adjacent to the crank end, and a bevel formed on the axial end thereof so that, as said screws in said cover are tightened, said bevel forces said ring into said groove and locks the ring in place, and said shoulder bears against said ring to prevent said sleeve from being pulled out of said cylinder and said cover prevents said sleeve from moving into said cylinder.

7. The leg prosthetic of claim 1 wherein said oneway valve includes;

an elongated body having a pair of wells formed therein and each opening at one end of said body;

each of said wells having a bottom portion of a given small diameter, a middle portion of a given median diameter so that a shoulder is formed therebetween and an exposed portion having threads therein;

a stem having a head portion with external threads for coacting with the threads in each of said wells and having a body portion with a diameter smaller than the diameter of said middle portion;

one of said valves has an elongated tube slidably disposed within said middle portion in sealing relationship therewith, and disposed between said stem and said shoulder so that whenever pressure is applied at said outlet port, said tube bears against said stem to prevent fluid flow, and whenever pressure is applied at said inlet, said tube bears against said shoulder to allow fluid to flow;

the other of said valves has an elongated pin slidably disposed within said middle portion and has one end adjacent to said shoulder, which end has a diameter larger than said bottom portion and smaller than said middle portion so that when pressure is applied at said outlet port, said pin bears against said shoulder to prevent fluid flow, and whenever pressure is applied at said inlet port, said pin moves away from said shoulder to allow fluid flow;

both of said stems being capable of being screwed down into said well to restrict fluid flow.

8. The leg prosthetic of claim 4, wherein:

said second means comprises;

a sleeve disposed within said cylinder and having said rod protruding therethrough;

sealing means disposed between said sleeve and said rod;

said cylinder having an internal circumferential groove disposed near its crank end;

a split ring nested within said groove so that said sleeve is internal of said ring;

an aperture cover covering the end of said crank end and having screws therein for engaging said sleeve;

said sleeve having an external shoulder near its end adjacent to the crank end, and a bevel formed on the axial end thereof so that, as said screws in said cover are tightened, said bevel forces said ring into said groove and locks the ring in place, and said shoulder bears against said ring to prevent said sleeve from being pulled out of said cylinder and said cover prevents said sleeve from moving into said cylinder.

9. The leg prosthetic of claim 8, wherein:

each of said one-way valves includes;

an elongated body having a pair of wells formed therein and each opening at one end of said body;

each of said wells having a bottom portion of a given small diameter, a middle portion of a given median diameter so that a shoulder is formed therebetween and an exposed portion having threads therein;

a stem having a head portion with external threads for coacting with the threads in each of said wells and having a body portion with a diameter smaller than the diameter of said middle portion;

one of said valves has an elongated tube slidably disposed within said middle portion in sealing relationship therewith, and disposed between said stem and said shoulder so that whenever pressure is applied at said outlet port, said tube bears against said stem to prevent fluid flow, and whenever pressure is applied at said inlet, said tube bears against said shoulder to allow fluid to flow;

the other of said valves has an elongated pin slidably disposed within said middle portion and has one end adjacent to said shoulder, which end has a diameter larger than said bottom portion and smaller than said middle portion so that when pressure is applied at said outlet port, said pin bears against said shoulder to prevent fluid flow, and whenever pressure is applied at said inlet port, said pin moves away from said shoulder to allow fluid flow;

both of said stems being capable of being screwed down into said well to restrict fluid flow.