JPH05161668A - Hydraulic control unit for artificial leg - Google Patents

Abstract

PURPOSE: To reduce the size and weight of a liquid pressure control unit for artificial leg by providing an oil accumulator in a piston rod. CONSTITUTION: An aluminum tubelike housing 22 is attached in a back-lining manner by cylindrical sleeves 48, 97 which surround a cylindrical control bush 55 completely and operate in cooperation with it to form an alley of liquid pressure control ports through which oil passes and flows to generate variable buffer force and which are arranged in a hound's-tooth check and a passage extending in the axial direction. Moreover, a tubelike piston rod 28 surrounds a thin and long movable rubber bag 140 in which pressurized gas is filled through a valve 134. When the piston rod 28 moves into the housing 22 and pressure applied to oil and the piston rod 28 increases gradually as an angle at which a knee is bent increases, the bag 140 operates in cooperation with the piston rod 28 to form an oil accumulator. At this time, oil in the bag 140 generates upward bias force in the piston rod 28 and pushes it up to the position where a leg is stretched.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD AND PRIOR ART A hydraulic control cylinder or unit for use in the knee joint of a prosthesis, such as disclosed in US Pat. No. 2,859,451 assigned to the assignee of the present invention. The technology provides a variable and adjustable cushioning force or moment when flexing or extending the knee, as well as a variable biasing force that moves the leg to an extended position while reducing the size and weight of the unit. It is desirable to minimize it. U.S. Pat.
As disclosed in the '451 patent, the hydraulic control unit generally comprises a housing forming an oil reservoir, and a cylinder projecting downwardly into the housing in a spaced relationship therewith. The cylinder contains a control bush that forms an array of staggered ports. Said port is at the opposite end of the bush by means of an axially extending channel corresponding to the port, the oil flow as the piston and piston rod move axially within the bush to create a variable damping force. Connected to a tapered passage or gap that controls The bushing is axially adjustable in the cylinder so that the tapered gap can be adjusted independently depending on the constant damping force desired.

A hydraulic control unit for a hydraulic machine of the type disclosed in 2,859,451 also has, by the applicant's assignee, an annular seal disposed between the housing and the cylinder surrounding the cylinder. And a compression coil spring that engages the piston. The spring and the annular piston form an oil accumulator that receives the hydraulic mechanical fluid that is displaced when the piston rod is pushed into the cylinder and housing.
The spring-biased annular piston also produces an increased biasing force on the oil when bending the knee, and also pushes the piston rod outward to return the artificial leg to its extended or nearly straight position. Function. Another form of hydraulic control unit for a hydraulic machine for a prosthesis is described in US Pat.
No. 3,316,558, No. 4,065,815, No. 4,212,087, No.
4,578,082 and 4,595,179.

[0003]

SUMMARY OF THE INVENTION The present invention is used in the knee joint of a prosthesis and produces a variable force to normally move the prosthesis over a wide range of walking speeds. The aim is to obtain an improved hydraulic control unit that approximates the movement of the legs of the. The control unit of the present invention can reduce size and weight, conveniently adjust the variable biasing force applied to extend the prosthesis,
It also provides the desirable features and advantages of conveniently adjusting the cushioning force applied when flexing and extending the knee. Moreover, the control unit of the invention requires fewer parts, is structurally more economical, and is more reliable in operation.

The above advantages are provided in the preferred embodiment of the invention in which the aluminum tubular housing defines a reservoir for hydraulic mechanical fluid or oil and a bore for receiving a pivot pin. The housing extends axially with an array of staggered hydraulic control ports that tightly surrounds and cooperates with the cylindrical control bush to allow oil to flow therethrough to create a variable damping force. It is lined with a cylindrical sleeve that forms a channel or passage. A tubular piston rod extends through the control bush into the housing and supports the piston in sliding contact with the bush. Annular one-way check valve
Adjacent to the tapered annular flow control gap in the opposite end portion of the bushing, and the bushing and sleeve being axially adjustable in the housing, the desired constant to resist flexion and extension of the knee. Can be independently adjusted to select the damping force of

The tubular piston rod encloses an elongated flexible rubber bag which is filled with pressurized gas through a valve in the outer end portion of the rod. The pressurized gas bag is
It cooperates with the tubular piston rod to form an oil accumulator as the pressure on the oil and piston rod gradually increases as the piston rod moves into the housing and the knee bend angle increases. Pressurized oil in the bag creates an upward biasing force on the piston rod to push the legs to the extended position, and the pressure on the oil also pushes the oil into the control bushes, where it is stretched at the end of its useful life. Moves any oil that is lost.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a prosthetic or artificial leg 10 having a bracket 11 secured to a cup-shaped socket portion 12 adapted to receive the thigh portion of the leg of a person undergoing amputation surgery.
Is shown. The prosthesis 10 also comprises a hollow lower leg portion 14 which projects upwardly from the foot portion 16 and which is pivotally connected by a hinge pin 17 to the bracket 11 to form a knee joint 18. In accordance with the present invention, hydraulic control unit 20 extends between bracket 11 and lower leg portion 14 and comprises a machined aluminum cylinder or housing 22. The housing 22 has an axis A and is pivotally connected to the lower leg portion 14 by a pair of pivot pins 23. A pivot pin 23 extends from the leg portion 14 into a threaded hole 24 (FIG. 2) formed in an outwardly projecting boss 26 of the housing 22 and corresponding to the pin 23. The unit 20 also comprises a tubular chrome-plated steel piston rod 28 projecting from the housing 22 and connected to the bracket 11 by a pivot pin 31. The pin 31 extends through a side hole 32 (FIG. 2) formed in the aluminum mounting portion 34. The aluminum mounting portion 34 is threaded into the outer end portion of the piston rod 28 and includes an elastic O-ring 36 to provide a fluid tight seal between the fitting 34 and the outer end portion of the piston rod 28. To form.

Referring to FIG. 2, the lower end portion of the housing 22 is a cylindrical hydraulic machine fluid or oil reservoir 42.
To form. The reservoir 42 is closed by a bottom cap 44 threaded onto the lower end portion of the housing 22 and sealed to the housing by a resilient O-ring 46.
The upper end portion of the housing 22 defines a cylindrical hole 47.
The cylindrical bore 47 has a tapered or frusto-conical lower end surface 51 and an externally threaded upper end portion 52 that engages an internal thread 53 formed in the upper end portion of the housing 22. Cylindrical brass liner or sleeve 48 having
Accept. The sleeve 48 is press fit into a brass liner or control bush 55. The control bush 55 has a tapered frustoconical lower end surface matching the surface 51 and a tapered or frustoconical upper end surface 58.

The control bush 55 also has axially and circumferentially staggered flow control passages or ports 60. Ports 60 are channels or passages 62 circumferentially spaced correspondingly axially extending through the bushing and formed in the outer surface of the bushing.
Extend into. As a result of the interference fit of the control bush 55 within the sleeve 48, each channel 62 forms an oil flow control passage. This passage extends from the port to either the lower tapered end surface 51 of the sleeve 48 or the upper tapered end surface 58 of the control bush 55.

The tubular piston rod 28 has an inner end portion with a flange 66 that projects into the housing 22 and forms the inner end of the piston rod. The flange 66 engages at right angles with a guide bearing 68 having four sets of circumferentially spaced axially extending oil flow passages 69. Bearing 68 guides the inner end portion of piston rod 28 as piston rod 28 moves axially into housing 22, and also piston rod 28 moves outwardly as shown in FIGS. Limit movement to the extended position.

The piston rod 28 has a pair of retaining rings 73.
Has a cylindrical steel piston 70 carried by a pair of annular collars 72 located on the piston rod 28. A pair of resilient O-rings 76 form a fluid-tight seal between collar 72 and piston rod 28, and a larger resilient O-ring 77 limits rotation of sleeve 48. An annular rubber-like flexible valve element 82 has a control bush 55 between a ring 83 and a ring 84 seated on a bearing 68.
Is retained in the counterbore formed in the lower end portion of the. Element 82 controls the oil from the outer surface of piston rod 28 and the control bush.
It forms a one-way check valve that can only flow upward into an annular chamber 85 formed between it and the inner surface of 55.

Another annular valve element 82 and ring 83 are retained within the counterbore formed in the lower end portion of bush 55 to provide a one-way check valve that allows oil to flow only downwardly into chamber 85. Form. The upper annular valve element 82 is suspended or fastened to an annular cover screw 90 having a lower end portion threaded into the housing 22 directly above the threaded upper end portion of the sleeve 48. It is retained in the counterbore by an annular collar 87 having a raised upper portion. The cover screw 90 is rotatable on the upper end portion of the housing 22, and the elastic O-ring 92 is a screw.
It forms a fluid-tight seal between the 90 and the housing 22 and limits rotation of the screw 90. The groove 93 forms a screw burr on the screw. The tapered frustoconical inner surface is formed within the annular cover screw 90, and the bushing is
Opposed to a matching tapered surface 58 on the upper end portion of 55 to form an upwardly tapered tapered flow passage or gap 96 therebetween. An annular titanium sleeve 97 is seated at the lower end of bore 47 and has an inner tapered or frustoconical shape that forms a lower flow passage or gap 98 with opposing corresponding tapered surfaces 51. Has a surface. Upper gap
96 is a winding cap that is fastened to the cover screw.
It can be adjusted by rotating the cover screw 90 with 105. The limiting pin 107 is threaded into the cap 105 and extends into a notch or recess 10 extending about 330 ° around the circumference of the upper end portion of the housing 22.
9 Stick out. The limit pin 107 is also an indicator ring mounted for rotation on the upper end portion of the howling 22.
The upper end portion of 114 projects into a recess 111 extending circumferentially about 180 °. Elastic O-ring 116 is ring 114
Holds indicator ring 114 on housing 22 after is set.

The radial pin 118 projects from the cover screw 90 through a notch or recess that extends circumferentially about 180 ° in the upper end portion of the control bush 55. pin
The inner end portion of 118 is received in an annular recess formed in the outer portion of the ring or collar 87. Therefore, by rotating the cover screw 90 with the cap 105, the assembly of the sleeve 48 and the control bush 55 is rotated and the assembly is adjusted to the hole 47 to adjust the bottom tapered gap 98. It can be adjusted in the axial direction. And the upper tapered gap
96 is adjusted by rotating the cover screw 90 with the cap 105 against the assembly of sleeve and control bush.

The cover screw 90 also has a piston rod 28.
Also retains an annular oil seal 121 that slidably engages the outer surface of the piston, and the exposed surface portion of the piston rod that engages the seal 121 is protected by a bellows-type collapsible tube or casing 124. It The lower end portion of the protective casing 124 is retained by an annular ring 126 which is press fit into the upper end portion of the cover screw 90 above the rod seal 121, the upper end portion of the protective casing sliding on the piston rod 28. It is tightly attached to the felt ring 128.

The upper, internally threaded end portion of the piston rod 28 surrounds a tubular fitting 132 which receives a Schrader type valve 134 having a spring biased, depressible valve stem 136. ..
The elastic O-ring 138 forms a fluid-tight seal between the mounting portion 34 and the fitting 132. Fixture 132
Projects into the upper end portion of an elongated rubber flexible bag 140 that extends to the tubular piston rod 28 and has a closed lower end. The bag 140 is glued to the fixture 132 and the elastic O-ring 142 forms a fluid-tight seal between the upper end portion of the bag 140 and the piston rod 28. The bag 140 is inflated through a valve 134 with a pressurized gas such as nitrogen.

After the entire hydraulic control unit 20 is assembled and the reservoir 42 and chamber 85 are filled with a predetermined amount of hydraulic mechanical fluid, such as oil, the bag 140 is attached to the mounting portion 34.
Before being assembled, it is inflated by the gas supplied through Schrader valve 134. The gas is pressurized so that a predetermined pressure is applied to the oil in the reservoir chamber 42 and the lower end portion of the piston rod 28. The pressurized oil exerts an outward force on the piston rod 28, which causes the rod to be in the extended position of the leg 10 of FIGS.
Bias to normal stretched position as shown in. This variable biasing force exerted by the oil
It can be conveniently and easily adjusted by changing the pressure of the gas in 0.

The unit 20 connects the knee joint and the hydraulic control unit 20 provides a prosthesis so that the piston rod 28 is pushed into the housing 22 whenever the knee bends or pivots about the cross pin 17. Mounted. As piston rod 28 moves inward, rod 70
A varying hydraulic resistance or cushioning force is exerted by a piston 70 that pushes oil outward through a control port 60 located below and through a channel or passage 62. The oil introduced by the piston rod 28 into the reservoir 42 is pushed upward into the piston rod 28, compressing and partially denting the bag 140, so that the piston rod 28 and bag 140 serve as a pressurized oil accumulator. Function. Since the gas pressure in the bladder 140 rises as the knee is bent further, the biasing force exerted by the oil on the piston rod 28 causes the lower leg portion 14 to move to the extended position shown in FIG. Increase to exert greater biasing force on the leg portion 14.

As the piston 70 moves downward in the chamber 85, the oil pushed outwardly from the chamber 85 through the port 60 is pushed upward in the corresponding channel 62 and the upper tapered limiting gap 96. Chamber 85 above the piston 70 and past the upper one-way annular check valve 82.
Pushed downwards. When the compression stroke begins, all ports 60 and channels 62 act as a restricted fluid passage. However, as the piston 70 moves downward over the staggered holes or ports 60 in the control bush 55, the angle at which the knee bends increases, thereby increasing the port 60.
Are reduced, producing higher resistance to oil flow and knee flexion. This is important to prevent the heel of the foot 16 from rising excessively over a wide range of walking speeds.

During the extension of piston rod 28 and prosthesis 10, this process is reversed and oil above piston 70 in chamber 85 is directed outward through a control passage or port 60 above piston 70. , Flows downward through a channel 62 that opens into a lower tapered gap 98, and upwards through a lower one-way check valve 82 back into chamber 85 below piston 70. .. As the knee flexes, the number of control ports and channels 62 available for draining oil decreases as the piston moves upwards toward its movement or end of stroke. The upward movement of the piston to this even higher and increasing resistance reduces the movement of the legs and the piston rod 28
It is important to prevent the legs from reaching their extension limits and suddenly stopping when they are fully extended.

In addition to the dampening curve produced by the staggered control ports 60, a dampening force is created by limiting the oil flow through the upper and lower gaps 96 and 98, respectively. As described above, the gaps sequentially cover the cover screw 90 within the housing 22.
Can be adjusted by rotating the control bush 55 axially and the cap 105 adjusting the sleeve 48. This allows independent adjustment of the upper and lower gaps, as well as resistance to knee flexion and extension, allowing each user to select the ideal setting of resistance to people's unique biomechanical requirements. To do.

As will be apparent from the drawings and the above description, a knee prosthesis with a hydraulic control unit constructed in accordance with the present invention provides desirable features and advantages. For example, the construction of the hydraulic control unit 20 with an oil accumulator in the piston rod 28 provides a significant reduction in unit size and weight, eliminates noise during operation, and eliminates wear parts. The unit 20 can also conveniently and easily adjust the pressure exerted by the hydraulic machine fluid or oil by adjusting the gas pressure within the bladder 140. In addition, the unit can be conveniently adjusted for a constant damping by independently adjusting the upper gap 96 and the lower gap 98. The structure of the control unit 20 also provides greater reliability, simplifies structure and manufacture, and allows for greater part tolerance which reduces the cost of the components assembled to form the unit 20. Also, the pressure exerted on the oil by the passage 69 in the bearing 68 and the bladder 140 will cause the rod seal to lose even after an extended period of use.
Make sure that the upper part of the unit is always full of oil, even if a little oil seeps out at 121. Preferably, the flexible wall of the bag 140 is always slightly concave so that there is no pressure loss across the bag wall due to the elasticity of the bag to resist stretch of the bag. Also, by using different materials across each gap 96 and 98, such as the titanium sleeve 97 and brass sleeve 48 in the control bush 55, the lower gap 98 will be a unit after continuous use of the leg 10. As the temperature of 20 increases, it becomes slightly thinner, which provides some compensation for the viscosity of the oil which is decreased by the higher temperature. This allows a lighter weight or aluminum housing to reduce weight and machining costs.
Twenty-two can be used.

While a control unit 20 or device of the type described herein constitutes a preferred embodiment, the present invention is not limited to this exact form of the device, and the scope of the appended claims. It should be understood that modifications can be made here without departing from the scope and spirit of the invention as described in.

[Brief description of drawings]

FIG. 1 is a side view of a partial leg prosthesis showing an apparatus of a hydraulic control unit constructed in accordance with the present invention.

2 is an axial cross-sectional view of the hydraulic control unit shown in FIG. 1, enlarged to about twice its normal size to show the detailed structure of the unit.

[Explanation of symbols]

10 ... Prosthesis, 18 ... Knee joint, 20 ... Hydraulic control unit, 22 ...
Housing, 28 ... Piston rod, 42 ... Reservoir, 47 ...
Cylindrical hole, 48,97 ... Sleeve, 51 ... Lower end surface, 53 ...
Female thread, 55 ... Bushing, 60, 62, 69 ... Passage, 68 ... Bearing, 70 ... Piston, 85 ... Chamber, 98 ... Gap, 105 ... Cap, 132 ... Fixture, 134 ... Valve, 136 ... Valve stem, 140 ... bag.

Claims (8)

[Claims] 1. An elongate tubular housing having an axis, said housing forming a reservoir and a lower end portion forming an axially extending bore with the upper end portion; A sleeve at the end portion for axially adjustable movement, a control bush forming a chamber within the sleeve for receiving hydraulic fluid, wherein the bush and sleeve are from the chamber to the bush. Means for forming an in-line flow control passage extending axially therethrough between the bush and the sleeve and having an inner portion extending to the chamber and an outer portion protruding from the housing A piston rod, a piston in the inner part of the piston rod for slidably engaging the bush, the flow of which is the piston and the piston rod; Used in a knee joint of a prosthesis, wherein the reservoir and the chamber are provided with a source of hydraulic mechanical fluid that flows through the passageway and buffers the piston rod in response to axial movement; A hydraulic control unit for approximating the movement of a prosthesis to that of a normal leg over a wide range of walking speeds, wherein the sleeve is lined in the hole and slidably supported in the hole. And the piston rod is tubular, has an inner end opening to the reservoir, and is free to limit the fluid for hydraulic machinery between the reservoir and the chamber in the piston rod. An expandable and compressible member within the chamber of the tubular piston rod forming a flow chamber for hydraulic machinery due to inward movement of the piston rod into the reservoir. Hydraulic pressure control unit, characterized in that the free flow of liquid into the piston rod chamber from the reservoir in response to resiliently bias the movement of. 2. Means for accurately adjusting the biasing force exerted by the extendable and compressible member within the piston rod at the outer portion of the piston rod in response to personal choice of the prosthesis user. The control unit according to claim 1, further comprising: 3. The expandable and compressible member within the piston rod is provided in the flexible rubber bag and within the outer portion of the piston rod for the hydraulic machine fluid and the piston rod. 2. A control unit according to claim 1, further comprising a check valve for guiding and confining a quantity of pressurized gas into the bag to select the biasing force. 4. The control unit of claim 1 including a fitting axially threaded into the outer portion of the piston rod and the valve having a spring biased valve member carried by the fitting. .. 5. The upper end portion of the housing has an internal thread, the sleeve has an external thread that engages the internal thread, and for rotating the sleeve for axial adjustment of the sleeve. A control unit according to claim 1, wherein means are mounted on said housing. 6. The control bush has a frustoconical lower end surface and the ring member has an inwardly frustoconical inner surface disposed in the bore of the housing and surrounding the lower end surface. Forming a gap between them,
The control unit of claim 1, wherein the control bushing and ring member are formed of different materials to control the gap in response to increasing temperature of the unit and lower viscosity of the liquid. 7. The control unit of claim 6, wherein the housing is formed of a material that weighs substantially less than the material forming the ring member. 8. The housing retains an annular bearing having a bore slidably supporting the inner portion of the piston rod, the bearing having at least one passage for axially directing liquid through the bearing. The control unit according to claim 1.