US3416546A

US3416546A - Power-operated crutch

Info

Publication number: US3416546A
Application number: US686509A
Authority: US
Inventors: William T Carpenter
Original assignee: Individual
Current assignee: Texas A&M University Development Foundation
Priority date: 1967-11-29
Filing date: 1967-11-29
Publication date: 1968-12-17
Anticipated expiration: 1985-12-17

Description

1968 w. T. CARPENTER POWER-OPERATED CRUTCH Filed Nov. 29, 1967 .4 Viz W. T. CARPENTER "-2 INVENTOR.

BY M,

FIG. 3

ATTORNEYS United States Patent 3,416,546 POWER-OPERATED CRUTCH William T. Carpenter, Houston, Tex. (Rte. 1, Box 102 A, Ragley, La. 10657) Filed Nov. 29, 1967, Ser. No. 686,509 20 Claims. (Cl. 135-49) ABSTRACT OF THE DISCLOSURE This application discloses a crutch of the type used by handicapped persons, the crutch being expandable under power whereby the user may raise himself from sitting to a standing position. The crutch includes upper and lower telescoping sections which provide a hydraulic piston and cylinder arrangement, with extension of the crutch being provided by forcing hydraulic fluid under pressure into the cylinder. A hydraulic reservoir having a floating piston therein is used for supplying fluid to the cylinder, the power for moving the floating piston being compressed gas. A gas chamber located in the crutch as sembly stores high pressure gas, and the reservoir may be charged with a small volume of the high pressure gas through a valve arrangement as the first step in the operating cycle. Secondly, hydraulic fluid is admitted into the cylinder by another valve to extend the telescoping sections. To lower or retract the crutch, the user first vents the gas in the reservoir by a valve, then opens another valve to allow the hydraulic fluid to cycle back into the reservoir.

Power-operated crutches have been devised which are used by handicapped persons as an assist in raising themselves from a sitting position to a standing position, or lowering themselves to a sitting position. Crutches of this type are shown in U.S. Patents 3,157,188 and 3,157,189 issued Nov. 17, 1964 to George R. Farnham, these crutches employing electrical or hydraulic motive power systems which are operated by the handicapped persons using fingertip controls. While the crutches according to the Farnham patents have been acclaimed as providing a major advance in the art, the difficulty of fabricating miniature, lightweight components such as electrical motors as used in these devices has markedly restricted their utility.

The potential improvement in mobility and freedom of action for a handicapped person provided by a poweroperated crutch is surprisingly great. Invalids, otherwise confined to the bed or wheelchair unless aided by another person in raising themselves to an upright condition so that conventional crutches may be used, are able to be much more active, independent and self-sufficient. However, the crutches previously proposed, while potentially quite eifective, have required especially made electro-mechanical components which resulted in the crutches being produced only on a very limited basis, one at a time, with the resultant high costs rendering the devices virtually unavailable to the handicapped, these being persons inherently of limited resources.

It is the primary feature of the power operated crutch of this invention that it may be readily manufactured using simple, rugged and readily available parts. Another feature is the simplicity, positive operation, and maintenance-free construction of the air-gas motive power system which is utilized. Other features include costs advantages and facility of manufacture which reduce the time required in obtaining parts and completing the fabrication cycle.

In accordance with this invention, a power-operated crutch is provided using a pair of telescoping, tubular sections which function as the piston and cylinder of a hydraulic arrangement. An auxiliary hydraulic reservoir 3,416,546 lc Patented Dec. 17, 1968 having a floating piston is used to force hydraulic oil into the cylinder or receive oil from the cylinder. A high pressure gas supply located within the crutch assembly is connected to the reservoir on one side of the floating piston by a valve which permits admitting a charge of high pressure gas to the reservoir. Another valve, manually operated by a fingertip control adjacent the handle of the crutch gripped by the user, permits fluid to be admitted into the cylinder from the reservoir to raise the crutch. The crutch is lowered by venting the reservoir, again by a fingertip control, and then opening the valve to allow fluid to re-enter the reservoir from the cylinder. All of these components are located within a small, lightweight crutch assembly which is of rugged and trouble-free construction.

Novel features which are believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as other features and advantages thereof, may best be understood by reference to the following detailed description of a particular embodiment, when read in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a pictorial view of a power-operated extendable crutch according to one embodiment of the invention;

FIGURE 2 is a detail view, partly in section and partly in schematic form, of the motive power system and control arrangement for the crutch assembly of FIGURE 1; and

FIGURE 3 is a view similar to FIGURE 2 in a different operating stage.

The drawings are considered a part of this specification and are incorporated herein. It is noted that like parts appearing in several views of the drawing bear like reference numerals.

With reference to FIGURE 1, a power-operated crutch according to an embodiment of the invention is shown externally. This device consists of an elongated crutch body 10 which may include an upper telescoping section having an outer tubular portion 11 and an inner tubular portion 12, the tube 12 telescoping into the tube 11 to adjust the height of the upper part of the crutch. A knurled collar 13 fitted on a threaded and slotted lower portion of the tube 11 may be turned to a bold position or a release position as is conventional. In like manner, the lower part of the crutch may be adjusted to fit the users height as it comprises an outer tube 14 and an inner tube 15 which are secured to one another by a releasable knurled collar 16. Connected to the upper end of the tube 11 is an armpit rest 17, while a resilient foot member 18 is fitted over the lower end of the tube 15 in conventional manner. Centrally located along the crutch body 10 is a housing 19 containing the air-hydraulic power mechanism, with a handle or hand-grip 20 being secured to the upper part of the housing. Push-button type control valves 21 are positioned on the top of the housing 19 adjacent the handle 20 to be conveniently operated by the thumb of the user while he is gripping the handle. It is noted that this power-operated crutch is a convenient self-contained unit which is rather small and lightweight. A left-hand crutch is illustrated, it being understood that a similar crutch having the control buttons 21 properly positioned would provide the right-hand unit of a pair. In operation, the user would first adjust the

telescoping sections

11 and 12 by means of the collar 13 so that the distance between the armpit rest 17 and the handle 20 corresponds comfortably to the length of his arms. In like manner, the

telescoping tubes

14 and 15 would be adjusted by the collar 16 so that the overall length of the crutch body 10 from the armpit rest 17 to the foot 18, with the power operated mechanism in the extended condition as will be described, would support the user comfortably in a standing position according to his height. Now, by manipulating the controls 21. for each crutch with his thumb in the manner set forth below, the user may cause the section 14 to telescope within the section 12 through the housing 19 to lower himself in a controlled manner to a sitting position; likewise, once in a sitting position he may cause the

sections

12 and 14 to extend with respect to one another under power to raise himself to a standing position. The retraction and expansion operations are controlled in speed, but yet comfortably rapid, so that the user is not unduly upset by use of the crutch, while at the same time the operation is not tediously slow. The power mechanism will now be described in detail.

With reference now to FIGURE 2, there is illustrated an enlarged detail view of the operating mechanism, artly in schematic form, as principally located within the housing 19. It is noted that the lower tube 14 which telescopes within the upper tube 12 is of appreciably smaller diameter, and this tube is sealed on its upper end by a cap 22 so that the tube 14 acts as a piston. The cap 22 is slightly larger than the diameter of the tube 14 so that when the

telescoping sections

12 and 14 are in the extended condition (FIGURE 2 illustrates these elements in the retracted or telescoped condition) the cap 22 will engage the upper edge of a sleeve or gland 23 and act as a stop. The sleeve 23 is rigidly secured and sealed to the inner diameter of the tube 12, and the tube 14 slides within the sleeve 23, an O-ring seal 24 preventing loss of hydraulic fluid which is contained within a chamber 25 between the smaller tube 14 and the larger tube 12. The upper end of the tube 12 is sealed by a cap 26, and the chamber 25 is filled with hydraulic oil, the piston or tube 14 being driven to an extended position for the crutch by forcing fluid into the chamber 25 under pressure, or the crutch being allowed to retract by venting fluid from the chamber 25 through an inlet port 27 as will be described. The O-ring seal 24 prevents loss of hydraulic oil around the tube 14, but in order to avoid wetting of the exposed portion of the tube 14 with hydraulic oil when the crutch is run up to its extended position, a felt wiper 28 of annular configuration is positioned in a collar 29 which is fitted onto the lower end of the sleeve 23 by a thread arrangement. The collar 29 is removable to permit replacement of the wiper 28 when it becomes saturated with hydraulic oil.

The gas-hydraulic power mechanism for operating the telescoping piston-cylinder arrangement of FIGURE 2 will now be described. It is noted that the inlet 27 to the chamber 25 is located within a manifold block 30 which surrounds the tube 12 and provides a rigid support for the handle 20, as well as containing various ports, passages, and valves for the control mechanism which is schematically represented. This manifold block may be a solid aluminum member suitably shaped and bored.

Located within the housing 19 is a large gas and oil reservoir 31 which is connected at the lower end by a conduit 32, through an orifice 33 and a push-button operated valve 34, to the inlet port 27. A floating piston separates the hydraulic oil in the lower portion of the chamber 31 from pressurized gas in the upper end of the reservoir. When the floating piston 35 is pushed downward by gas pressure, hydraulic oil flows from the lower end of the reservoir through the conduit 32, if the valve 34 is opened, and into the port 27, thus forcing the tube or piston 14 downward. The rate at which fluid can pass through the conduit 32 into the port 27 is determined by the orifice 33 which is dimensioned to limit the maximum rate of operation of the crutch to avoid injury to or unbalance of the user. The valve 34 is a metering type valve biased in the closed position by a spring and opened by a push-button as will be explained.

Compressed gas is admitted to the upper end of the reservoir 31, above the floating piston 35, from a pressure cylinder 36 through conduit 37, a valve 38, and a conduit 39 which leads into a small chamber-40. The chamber 40 is defined in the upper end of the reservoir by a sleeve 41 which, when the piston 35 is in its uppermost position, provides a chamber to receive a charge of compressed gas. The valve 38 is normally closed, and the cylinder 36 contains a gas such as CO at perhaps 900 p.s.i. or other convenient pressure. When the valve 38 is opened briefly, the chamber 40 will be charged to the cylinder pressure, but the floating piston 35 will not move so long as the valve 34 is closed. The cylinder 36 usually would contain mostly liquid CO and this cylinder includes an external fitting 42 of conventional type which is exposed at the outer face of the housing 19 to permit recharging of the cylinder 36. The chamber 40 may be vented to atmosphere through a conduit 43 and a normally-closed valve 44 which is operated by a push-button. A muffier 45 comprising a small chamber with bafiles would be used to avoid noise when the gas is vented.

The fingertip control arrangement 21 employs three push-

buttons

46, 47, and 48, as seen in FIGURE 2, for operating the

valves

38, 34 and 44, respectively. These push-buttons are operated by the thumb of the user for each hand to raise and lower the power-operated crutches. Each of the

valves

38, 34 and 44 is normally closed, and is opened by depressing the corresponding push-button. The operation will be explained in detail below.

While the particular dimensions employed in this embodiment of the invention are not critical, it will be an aid in understanding the invention to consider the relative sizes of the variou components. The stroke of the piston defined by the upper end of the tube 14 is about 18", this being the operating or lifting range of the crutch. The diameter of the chamber 25 is about 1", whereas the effective diameter of the piston 14 is about so the volume of hydraulic oil needed to be added to the chamber 25 to drive the piston from fully retracted to fully extended positions is about 5 in. Accordingly, the reservoir 31 must contain at least this quantity of oil, indeed the chamber 31 preferably contains about 7 in. of hydraulic oil to account for losses due to slight leakage over several months of operating time. The reservoir 31 is about 1 /2" diameter and 6" long to fit conveniently within the housing 19. For operation at about 900 p.s.i. pressure in the cylinder 36, the chamber 40 should be about diameter by 1" length to receive a charge of compressed gas which is sufficient to drive the floating piston 35 the length of the reservoir 31, against the weight of a 240 lb. person supported by two crutches. With these ratios, and using a cylinder 36 of about 2 /2" by 8" or 40 in. there would be enough pressurized CO for about strokes. It has been found that the average person used the power-operated feature of the crutch about thirty times per day, and so one charge of the CO cylinder 36 would last for about three days on average. In this example, the sleeve or gland 23 is about 5" in length, and this member may be composed of honed cast iron to provide the necessary tolerance. The piston or tube 14 fitting within this gland could be formed of cold drawn steel seamless tubing which is ground to size, chromed and polished, or perhaps stainless steel which is ground and polished, the tolerance between the OD of the piston 14 and the ID of the gland 23 preferably being about 0.002". These specific dimensions of course are merely illustrative.

In operation of the gas-hydraulic powered crutch as described above, it will be first assumed that the crutch is in condition of FIGURE 2, i.e., in the retracted condition as when the user is seated. To raise himself to the standing position, the user would lean forward and place the two crutches under his arms and grasp the handles 20, then with his thumb he would press the push-button 46 of the control unit 21 for each crutch. This would serve to open the valve 38 and admit a charge of gas at 900 p.s.i. into the chamber 40. The push-button 46 would be released so the valve 38 would close, and the mechanism would remain in this condition, the chamber 40 pressurized, until the push-button 47 is depressed. When the latter button is operated, the valve 34 would open to a degree dependent upon how far the button 47 is pushed. This permits hydraulic oil to pass out of the reservoir 31 as the floating piston 35 is driven down by gas pressure, and the oil will pass through the orifice 33 which determines the maximum rate and into the chamber through the inlet 27. This drives the piston 14 downward, and this condition will continue until suflicient fluid has moved from the reservoir 31 to the chamber 25 to drive the piston 14 to the position seen in FIGURE 3, the cap 22 ultimately contacting the upper rim of the gland 23, and the floating piston moving to near the bottom of the reservoir 31. The button 47 would be held down to hold the valve 34 open during the time required to move the piston 14 all the way to the extended position of FIGURE 3, this requiring perhaps several seconds with the valve 34 all the way open, or a longer period if the valve is not opened fully. Now the valve 34 will be closed by releasing the thumb pressure on the button 47, and the crutch Will remain in this extended position indefinitely since the hydraulic fluid cannot escape. To lower the crutch, first the valve 44 would be opened by depressing the button 48 to permit the gas in the top of the reservoir 31 to be vented to atmosphere thnough the mufiler 45. Assuming no gas leakage from the chamber 31 while the crutch was in the extended condition, the pressure with in the reservoir 31 will still be perhaps 300 p.s.i. (assuming that about /3 in. at 900 p.s.i. has expanded to about 5 /2 in. in the reservoir 31). Except for leakage, this pressure will be maintained, and the crutch could not retract until the pressure is vented. After the pressure is vented and the button 48 released to close the valve 44, the reservoir 31 will again be sealed. Now the valve 34 is again opened to permit flow of hydraulic oil in the other direction, by pressing the button 47, and so the weight of the user bearing down on the crutches will cause the piston 14 to be forced back into the chamber 25 toward the condition illustrated in FIGURE 2, this filling up the reservoir 31 and forcing the floating piston 35 back up to the top. This will compress the gas trapped within the chamber 40, building up a pressure of perhaps 20 p.s.i. This gas pressure is maintained so that when the cycle is repeated a small amount of the gas pressure is conserved since the pressure in the chamber need not be brought up from zero. It is thus seen that either raising or lowering the crutch is a two-step process. For lowering, first the button 48 is depressed, then it is released and the button 47 is depressed. Likewise, for raising, first the button 46, then the push-button 47 is operated.

In the construction of the power-operated crutch of the invention, it may be noted that the manifold block 30 would be a major structural member consisting of an aluminum block perhaps 1 /2" thick and of a size equal to that of the top of the housing 19. This block would be suitably drilled and shaped to provide the various passageways and positions for the

valves

34, 38 and 44 along with the push-buttons 46-48 which are spring biased in the upward position. In addition, the block would provide a firm support for the handle 20.

It is noted that the armpit rest 17 illustrated is of the non-padded type to reduce the bulkiness of the unit, and so to overcome the additional discomfort which might occur due to the added force applied during the raising operation, the rests 17 are especially shaped. The shaping includes a recess 49 in the front upper end of each rest to aid in fitting the contour of the body and relieving nerve pressure or restriction of circulation in the arm of the user.

It is further noted that the cap 26 in the upper end of the tube 12 includes a bleeder fitting 50 which is used to bleed air out of the hydraulic cylinder to avoid spongy operation. Slight amounts of air or gas may leak into the hydraulic system over long periods of time, but this is easily remedied by the bleeder fitting.

The purpose of the floating piston 35 in the assembly described above is to separate the pneumatic and hydraulic portions of the system. This function may be accomplished by the use of a hydraulic accumulator of the type having an expandable bladder to receive the oil within a chamber, the chamber containing the gas around the exterior of the bladder so that by changing the gas pressure the oil may be forced out into the driving cylinder or allowed to drain back into the bladder. However, the float ing piston arrangement is preferred from a cost, size and reliability standpoint. In like manner, this separation function could be dispensed with and the assembly would operate in the same manner, but there may be a problem of air getting into the oil cylinder 25, producing a spongy effect, or oil escaping through the muflier 45 where the air is vented, this being annoying to the user. An air-oil separator could be used at the rnuifler, but this would be needlessly bulky and expensive. Thus, the floating piston feature is most preferable.

In place of the charging chamber 40, a pressure regulator could be used in the output line 37 from the air cylinder 36 to provide a constant low pressure to the reservoir, but this would require a different operating cycle in that the valve 46 would have to be open during the entire time the floating piston moved downward, and also the pressure regulator is bulky and expensive.

As a safety feature, the orifice 33 may be located at the tip of the inlet 27, just at the point where it enters the chamber 25, so that the oil cannot escape faster than a certain valve even though the valve or line might fail. Thus, the crutch would not collapse, but instead would contract fairly slowly.

While the invention has been described with reference to a particular embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as other embodi ments of the invention, maybe obvious to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.

What is claimed is:

1. A power-operated crutch of the type including an elongated crutch body assembly having a pair of elongated telescoping sections, and a crutch handle located at an intermediate point along the crutch body assembly:

one of the telescoping sections fitting coaxially within,

and being substantially smaller than, the other of the telescoping sections to provide a hydraulic piston and cylinder arrangement,

a hydraulic reservoir,

means for introducing compressed gas into the hydraulic reservoir,

means including a manually-operated valve for connecting the hydraulic reservoir to the hydraulic cylinder between the telescoping sections.

2. A power-operated crutch according to claim 1 wherein the size of the upper end of the lower one of the telescoping sections is substantially less than the interior dimension of the lower end of the .upper one of the telescoping sections, whereby suflicient interior space is provided between the sections to permit introduction of hydraulic fluid in the vicinity of said handle at said intermediate point.

3. A power-operated crutch according to claim 2 wherein annular wiper means is provided at the lower end of the upper telescoping section to prevent exposure of fluid-wetted portions of said lower telescoping member upon extension of the crutch assembly.

4. A power-operated extenda'ble crutch according to claim 3 wherein a cylindrical sleeve secured to the interior of the lower end of the upper telescoping section surrounds the upper end of the lower telescoping section,

and a stop member located on the upper tip of the lower telescoping section engages said sleeve upon maximum extension of the crutch assembly.

5. A power-operated crutch according to claim 1 wherein the effective operating displacement provided by movement of gas into said hydraulic reservoir is slightly greater than the maximum eflective displacement of said piston and cylinder arrangement provided by the telescoping sections.

6. A power-operetad crutch according to claim 1 wherein an orifice is interposed between said reservoir and said hydraulic cylinder to restrict the maximum rate of extension of the crutch assembly, and said manuallyoperated valve for admitting hydraulic fluid into said piston and cylinder arrangement may be variably positioned to control the rate of extension of the crutch assembly.

7. A power-operated crutch according to claim 1 wherein an orifice is interposed between said other end of the reservoir and said hydraulic cylinder to restrict the maximum rate of extension of the crutch assembly, and said manually-operated valve for admitting hydraulic fluid into said piston and cylinder arrangement may the variably positioned to control the rate of extension of the crutch assembly.

8. A power-operated extendable crutch according to claim 1 wherein a gas charging chamber is provided at one end of said hydraulic reservoir, and manually-operated valve means are provided for charging said chamber from a supply of pressurized gas.

9. A power-operated crutch according to claim 8 wherein further manually-operated valve means connect said charging chamber to atmosphere whereby said one end of the reservoir may be vented.

10. A power-operated crutch according to claim 8 wherein said chamber is vented to atmosphere through a mufiier.

11. A power-operated crutch of the type including an elongated crutch body assembly having a pair of elongated telescoping sections, a power system housing and a crutch handle located at an intermediate point along the crutch body assembly, and an armpit rest at the upper end of the crutch body assembly, said crutch comprising:

a hydraulic piston and cylinder arrangement provided at the telescoping portion of the sections,

a hydraulic reservoir having a floating piston therein,

means for introducing a charge of compressed gas into the hydraulic reservoir on one side of the floating piston,

a valve for connecting the hydraulic reservoir at the other side of said floating piston to the hydraulic cylinder to selectively admit or vent hydraulic liquid to or from said piston and cylinder arrangement.

12. A power-operated crutch according to claim 11 wherein the telescoping sections fit coaxially to provide the piston and cylinder, the size of the upper end of the lower one of the telescoping sections is substantially less than the interior dimension of the lower end of the upper one of the telescoping sections, whereby suflicient interior space is provided between the sections to permit introduction of hydraulic fluid in the vicinity of said power system housing at said intermediate point of the crutch body assembly.

13. A power-operated crutch according to claim 12 wherein the effective operating displacement provided by movement of said floating piston Within said hydraulic reservoir is slightly greater than the maximum eflective displacement of said piston and cylinder arrangement provided by the telescoping sections.

14. A power-operated extendable crutch according to claim 13 wherein a gas charging chamber is provided at said one side of said floating piston in said hydraulic reservoir, and manually-operated valve means are provided for charging said chamber from a supply of pressurized gas.

15. A power-operated crutch according to claim 14 wherein the valve connecting the hydraulic reservoir to the hydraulic cylinder is manually operated by a push-button located on said housing closely adjacent said handle and closely adjacent a push-button for actuating said manually operated valve means for charging said chamber.

16. A power-operated crutch according to claim 15 wherein further manually-operated valve means connect said charging chamber to atmosphere whereby said one end of the reservoir may be vented, such further valve means being actuated by a push-button located closely adjacent said other push-button.

17. A power-operated crutch according to claim 16 wherein the push buttons are located on the top of said housing within convenient reach of the thumb of the user gripping said handle.

18. A power-operated crutch according to claim 17 wherein all of said valves and valve means are spring biased to a normally closed position; and wherein a twostep procedure of cycling the valves is required for extending or retracting the crutch assembly.

19. A power-operated crutch according to claim 13 wherein annular wiper means is provided at the lower end of the upper telescoping section to prevent exposure of fluid-wetted portions of said lower telescoping member upon extension of the crutch assembly.

20. A power-operated crutch according to claim 13 wherein a cylindrical sleeve secured to the interior of the lower end of the upper telescoping section surrounds the upper end of the lower telescoping section, and a stop member located on the upper tip of the lower telescoping section engages said sleeve upon maximum extension of the crutch assembly.

References Cited UNITED STATES PATENTS 710,074 9/1902 Pratt 62 2,426,594 9/1947 Buell et a1. 135-61 2,479,667 8/1949 Shellhouse et al. 13561 X 3,157,188 11/1964 Farnham 1355O 3,157,189 11/1964 Farnham 135-50 3,158,851 11/1964 Ruthven 13547 X PETER M. CAUN, Primary Examiner.

U.S. Cl. X.R. 135--50