US3636816A - Power unit for a stool and the like - Google Patents

Abstract

A power unit for a stool and the like. The stool may comprise a seat mounted upon a vertical post comprising the power unit, having upper and lower parts, the post being secured to a base. The power unit has a ram which telescopes within a cylinder. The power unit further comprises a reservoir containing oil under pressure of compressed air which can be used to change the effective length of the power unit. A flow control valve and a lever controls the flow of the oil between the reservoir and the cylinder so as to regulate the mentioned effective length. The reservoir and the valve are disposed at one end of the power unit. An improved seal having a center portion and flared inner and outer lips is used to seal parts of the power unit so as to prevent leakage of air or oil.

Description

I United States Patent 1151 3,636,816 Hale 1451 Jan. 25, 1972 [54] POWER UNIT FOR A STOOL AND THE 3,l47,946 9/1964 Hale ..9l/4 LIKE 3,3l8,202 5/l967 Means ..92/245 [72] Inventor: Dean H. Hale, 2500 North Main, Logan, Primary ExaminerPaul E. Maslousky Utah 84321 Attorney-Lynn G. Foster 22 I F1led Apr 15, 1970 [57] ABSTRACT 21 l. l 1 App No 28337 A power unit for a stool and the like. The stool may comprise a seat mounted upon a vertical post comprising the power [52] us. Cl. 91/4 R, 92/240 unit, having upper an l we p r the p ng Secured to a [51] Int.Cl ..Fl5b2l/04,Fl6j 9/08 base. The power unit has a ram which telescopes within a [58] Field of Search ..9l/4 R, 4 A; 92/245, 240 cylinder. The power unit further comprises a reservoir containing oil under pressure of compressed air which can be used [56] References Cited to change the effective length of the power unit. A flow control valve and a lever controls the flow of the oil between the UNITED STATES PATENTS reservoir and the cylinder so as to regulate the mentioned ef- 1,s05,521 5/1931 Hansen ..91/4 fem? ban? The "F and the valve dispmed 1,987,083 1/1935 Smith u end of the power umt. An lmproved seal havmg a center por- 2 754 164 7/1956 Schwarz" tion and flared inner and outer lips is used to seal parts of the 3:000 358 9/1961 Marlow ..:::....91/4 Powelr as 'eakage 3 Claims, 7 Drawing Figures 1 J; 136 a t w 132 5} ll I i r 1 "6 it H0 5 1i U i. "2 i '82-s l a v 120 232 ZIZ E 222 1 I84 1 l I42 =5 1:

I48 I40 I38 2 I83 4 POWER UNIT FOR A STOOL AND THE LIKE BACKGROUND 1. Field of Invention This invention relates in general to a power unit and more particularly to a novel power unit the length of which can be extended and retracted at will by the operator and comprises a ram, a cylinder in which the ram slides, a base, a reservoir of oil pressurized by air, a valve or flow control, and at least one seal.

2. The Prior Art Power units for extending and retracting a ram within a cylinder have traditionally used O-ring seals interposed between the ram and cylinder to accommodate increased pressure on one side of the seal. In order for the O-ring to be effective as a seal, it must be urged forcefully against the surface of the ram or cylinder member which moves relative to the O-ring. It has been found that relative movement of the cylinder and ram requires an inordinate amount of displacing energy because of the force exerted through the O-ring against the movable member. Also the high resistance to movement exerted by the O-ring has been found to result in premature failure of the seal.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION The present invention has overcome the aforementioned disadvantages by providing power unit comprising a cylinder and a displaceable ram and a novel sealing unit which forms an effective fluid seal in response to a low-magnitude pressure drop across the seal. Further, the ram and cylinder can be easily moved with respect to one another without detracting from the effectiveness of the seal.

It is a primary object of this invention to provide a novel power unit for relatively displacing a ram and cylinder.

It is another primary object of the invention to provide a novel sealing unit for forming an improved seal between a ram and cylinder.

It is a further object of this invention to provide an improved valve for controlling the relative positions of the ram and cylinder.

These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a presently preferred embodiment of the power unit used to control the position of a stool seat.

FIG. 2 is an enlarged fragmentary cross-sectional view of the upper portion of the embodiment of FIG. 1;

FIG. 3 is an enlarged fragmentary cross-sectional view of the lower portion of the embodiment of FIG. 1;

FIG. 4 is a cross-sectional view of another presently preferred power unit embodiment of the invention particularly illustrating improved valve structure;

FIG. 5 is a cross-sectional view of still another presently preferred power unit embodiment of the present invention illustrating alternative valve structure;

FIG. 6 is a top perspective view of the presently preferred sealing unit used with the power unit embodiments of FIGS. 1, 4 and 5; and

FIG. 7 is a perspective view of the underside of the sealing unit of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the FIGS. 1, 2 and 3, the power unit generally designated 10 is illustrated as forming part of a vertically displaceable stool, although the power unit 10 may be used in any of a wide variety of compatible structures and may be disposed vertically or horizontally. In the illustrated embodiment, the power unit 10 comprises a seat 12 on the upper end of a hollow vertical post I4. Post I4 has a sleeve 18 which telescopes over and is movable vertically relative to a cylinder 20 secured to a hub 22 of base 16.

The sleeve 18 of the post 14 has a depending skirt 36 which telescopically receives at least part of the length of cylinder 20 and protects moving parts of the power unit 10 from dust and foreign particles. Sleeve I8 is provided with a cup-shaped ring 30 into which a downwardly tapering conical-shaped housing 28 is secured. The housing 28 is integrally joined to a seat mounting plate 26 which is, in turn, secured by bolts 38 to a rigid support 40 of seat 12. Spacers 42 circumscribe the bolts 38 to maintain a spaced distance between plate 26 and support 40. An actuating lever or plate 24 interposed between the plate 26 and support 40 is manually movable or pivotable toward the underside of the seat to permit elevation of the seat or lowering of the seat as will be hereinafter more fully described.

The actuating plate 24 is preferably generally annular in configuration and tapers upwardly toward the center so as to have a generally inverted dish-shape appearance. An annular projection or boss 62 selectively engages the seat board 40 to serve as a fulcrum for the plate 24 so that the plate may be rocked upon the fulcrum 62 to change the vertical position of the plate 24. Also, a plurality of spaced apertures 64 are located so as to loosely circumscribe the spacers 42 so that the spacers 42 do not inhibit the rocking movement of the plate 24.

As can be appreciated by reference to FIG. I, the elongated valve stem 52 normally impinges upon the plate 24. The stem 52 is urged upwardly against the plate 24 by a compression spring 54 which exerts a constant upward force upon the stem 52 through the transverse pin 58. The stem 52 is situated within the stepped annular bore 50 of plug 44, the stepped bore forming a shoulder 56 upon which the lower end of spring 54 rests.

The plug 44 has a diametral dimension which is substantially the same as the inside diametral dimension of hollow ram 32. The position of plug 44 is maintained by annular flange 48 which rests upon the terminal end of the ram 32. The leading end of the plug 44 above the flange 48 projects through an aperture 46 in the plate 26. Preferably, the ram 32, plug 44 and plate 26 are immovably secured together.

Stem 52 has a diametrally reduced portion 57 situated within the diametrally reduced length of the stepped bore 50. An improved sealing unit 60, according to the presently preferred embodiment of the invention, is situated within the annularly reduced portion 57 so as to form a fluid seal between the plug 44 and the stem 52. The structure and operation of the sealing unit 60 will be hereinafter more fully described.

Ram 32 is provided with a plurality of radially spaced apertures 34 which communicate the interior of the ram 32 with the interior of the conical housing 28. Apertures 34 allow fluid, normally stored within the conical housing 28 to pass between the valve stem 52 and the walls of ram 32 as will now be more fully described.

The lower end of the ram 32 is permanently connected to a head 66 having a stepped bore 68 which intersects an intermediate coaxial recess 70 of larger diameter to form a valve seat 72. The recess 70 intersects an outer coaxial recess 74 of still larger diameter and fonns therewith a shoulder 76. The lower part 78 of the valve stem 52 preferably has a triangular cross section and extends through the bore 68 of the head 66. A valve head 77 is integral with the valve stem 52 and is adapted to engage the seat 72 in fluidtight relation when the spring 54 urges the stem 52 to the upwardmost position against plate 24. Valve head 77 allows fluid within the ram 32 to pass into the recess 74 when the stem 52 is displaced downwardly against the bias of spring 54 by the plate 24. The valve head 77 is in the open position in FIG. 1.

The lowennost or outer recess 74 in the head 66 contains a disc flow control 88 which has a diameter less than that of recess 74 and greater than the diameter of recess 70. The flow control 88 is thus free to move axially or float" within the recess 74 between an elevated position in engagement with shoulder 76, at the bottom of recess 48, and a lowered position spaced from shoulder 76. Outward movement of the disc flow control 88 from recess 74 is limited by a stop, shown as transverse pins 90 which extend through and are supported upon the wall of head 66 at the mouth of the recess 74. A small central opening or orifice 92 is formed in the disc flow control to provide a bleed passage for fluid when the flow control is elevated. The relative diameters of the disc flow control 88 and recess 74 are such that fluid flow between the control disc and the side of the recess is substantially unrestricted when the disc 88 is lowered. However, when the disc flow control 88 is in the elevated or closed position, the disc fully overlays the recess 70. When the disc 88 is in the elevated position, fluid flow from beneath the ram 32 is restricted by orifice 92 to safely limit the rate of descent of the seat structure 12.

The cylindrical member comprises an outer tube or cylinder 80 which is secured in and closed by the hub 22 of the base 16, as above described. The outer tube 80 extends upwardly from the hub for a substantial part of the length of the vertical post 14 and has a sleeve 82 secured to the inside of the upper end of the cylinder. The inside diameter of sleeve 82 is sized so as to snugly and slidingly engage the outer surface of the ram 32. The inside diameter of the outer tube 80 is slightly greater than the outside diameter of the ram 32. The head 66 on the lower end of the ram 32 has a ridge 84 which slidingly engages the outer tube 80. An improved sealing unit 85 is carried in a groove in the ridge 84 so as to form a fluidtight seal between the head 66 and the cylinder 20. The sealing unit will be subsequently more fully described. A bearing sleeve 86 on the lower part of the head 66 limits lateral play between parts.

The upper limit of movement of the outer sleeve 18 and ram 32 relative to the cylinder 20 is determined by abutment of the ridge 84 against the lower end of the sleeve 82. The lower limit of such movement is provided by abutment of the lower end of the head 66 with the bottom of the hub 22 on base 16.

Fluid under pressure is contained within a reservoir comprising the conically shaped housing 28 and plate 26 and the exterior of the upper part of the ram 32.. Fluid pressure is also contained within the interior of the ram 32 between the plug 44 at the top and the head 66 at the bottom. The upper portion of the conical housing 28, for example, may be and preferably is filled with a gas such as compressed air and the remainder of the reservoir contains a hydraulic fluid such as oil. When the seat and ram 32 are in the lowest position, the fluid under pressure is contained within the structure having minimum volume. The spring 54 urges the valve stem upwardly to close the valve head 77 against the seat 72 and valve actuating plate 24 is equally spaced from the marginal edges of the seat 12.

In order to elevate the seat, the plate 24 is pivoted about the fulcrum 62 to depress the valve stem 52 and move the valve head 77 off the seat 72. Because the pressure of fluid within the ram 32 is greater than the pressure below the head 77, the hydraulic fluid flows through the bore 68 of the head 66 and recesses 70 and 74 around the periphery of the disc flow control 88 to the underside of the head 66. This creates a differential pressure between the underside of the head and the annular space between the outer tube 80 and the ram 32 and causes the entire seat structure, including the head 66 and ram 32 to rise until the ridge 84 abuts sleeve 82 on the inside of cylinder 20 or until the valve head 77 is closed by release of the actuating plate 24. If the seat 12 is to be elevated while it is occupied, the user lifts his weight from the seat sufficiently to allow the seat to rise to the desired height, and, closing of the valve head 77 then traps the hydraulic fluid under the head 66 where it supports the full weight of the user.

When the occupant desires to lower the elevated seat, he opens the valve head 77 with finger pressure on the plate 24 and permits his weight to force fluid in a reverse direction through the valve seat 72 and into the reservoir of housing 28.

As soon as this reverse flow of fluid occurs, however, the disc flow control 88 is urged by the reverse fluid pressure against the seat 76 and the flow is blocked except to the extent permitted by orifice 92. This restricted flow limits the rate of descent of the seat structure regardless of the load applied and the parts of the power unit 10 and the occupant are always assured of a gentle bottoming of the seat at the end of the descent.

The sealing unit 60 and 85, heretofore mentioned, are shown in position in a power unit 10 in FIGS. 2 and 3 and are shown removed from the power unit 10 in FIGS. 6 and 7. In the illustrated embodiment, the sealing units are generally annular in configuration and comprise an outer lip 212, an inner lip 214 and a central portion 216 to which the outer lip 212 and inner lip 214 are integrally joined. A centrally located annular aperture or opening 218 is, in the illustrated embodiment, provided for installing the seal on the valve stem 52 or annular ridge 84 (see FIGS 2 and 3). The inner surface 220 of the lip 214 continuously engages valve stem 52 or head 66 to form a seal. The outer surface 222 of the outer flange 212 similarly contacts plug 44 or cylinder 20 to form a fluid seal.

The center portion 216 terminates in a generally smooth surface 224. The outer flange 212 terminates in surface 226 and the inner flange 214 tenninates in surface 228. While the terminal surfaces 226 and 228 need not be in the same plane, in the illustrated embodiment they are shown terminating in the same plane.

The outer flange or lip 212 is generally flared outwardly and the inner flange or lip 214 is generally flared inwardly forming a V-shaped groove 213 therebetween. From the center portion 216 the outer flange 212 begins, as shown at 232, to flare outward linearly. From the center portion 216, as indicated at 234, the inner lip 214 begins to flare inwardly linearly. The linearly flared lips 212 and 214'of the sealing unit eliminate the need for close manufacturing tolerances on the sealing unit and the surfaces upon which it forms a seal.

While it may be possible to provide a seal with flanges 212 and 214 of equal thicknesses, it is presently preferred that one of the lips 212 and 214 be thicker than the other. It should also be observed that, as shown in the Figures, the lips 212 and 214 are urged together when assembled in the power unit. When urged together, the combined thicknesses of the outer lip 212 and the inner lip 214 is generally the same thickness as the center portion 216. The result of this construction is that there is no compression or deformation of the seal, but merely a displacement or movement of the lips to open or close the V- shaped groove 213. Accordingly, axial displacement between the valve stem 52 and the plug 44 and axial displacement between the head 66 and the cylinder 20 takes place readily.

As shown in the Figures, the respective sealing units 60 and 85 are assembled with the inner lips 212 and the outer lips 214 exposed at least partially to positive fluid pressure so that pressure force will open the V-shaped groove 213 and cause the lips 214 and 212 to be urged apart so as to form an effective seal.

Referring now to FIG. 4, another presently preferred power unit embodiment generally designated is illustrated as forming part of a stool comprising a seat (not shown) mounted on the upper end of a vertical post, having legs 104 on the lower end thereof. In the presently preferred embodiment, the vertical post comprises a cylindrical ram 106 and a cylinder 108. The ram 106 of the post has a solid rod 110 to which the seat (not shown) is attached. The lower end of the rod 110 telescopes within the hollow of cylinder 108. Cylinder 108 has an inner tube 112 opened at its upper end and closed at its lower end by a valve core 114 subsequently more fully described.

A hearing sleeve 116 is provided in the upper end of the tube 112, and another bearing sleeve 118 is mounted upon the lower end of the rod 110 so as to limit lateral play between the ram and the cylinder. The rod 110 is diametrally enlarged, intermediate its length, to form a shoulder 119. Shoulder 119 limits the upper travel of the rod 110 in the cylinder 112 by contacting the bottom of bearing sleeve 116. An annular groove 120 located near the bottom of the ram above the bearing sleeve 118, contains sealing unit 122. Sealing unit 122 is preferably substantially identical to sealing units 60 and 85 above described.

A reservoir cylinder 124 is coaxially disposed over the tube 112 and extends generally the length of the tube 112 to form one wall of a chamber or reservoir 125. The annular reservoir 125 is closed by an upper header 126 and a lower header 128. In the illustrated embodiment, the upper header is secured to the tube 112 and the reservoir cylinder 124 by means of threaded fasteners 129. The lower header 126 is secured to the tube 112 by welding or the like and is press fit into the reservoir cylinder 124. The upper header 126 has grooves 130 and 132 on its respective inside and outside diameters which contain O- rings 134 and 136 to seal the header 126 to the tube 112 and the reservoir cylinder 124. The lower-header 128 has a groove 138 on its outside diameter and has an O-ring 140 to seal the lower header 128 to the reservoir cylinder 124.

Valve core 114, beneath the rod 110, fits within the tube 112 and has an annular recess 142 formed therein. The valve core 114 has grooves 143 and 144 in which O-rings 146 and 148 are fitted to seal the valve core to the tube 112 when the core 114 is press fit into the tube 112. An elongated bore 150, coaxial with the tube 112, is provided in the valve core 114 and communicates with the recess 142. The bore 150 is diametrally enlarged at 153 and opens to the exterior at the bottom of core 114. Ports 151 in tube 112 communicate the reservoir 125 with a transverse passageway 152 disposed in the valve core 114 between O-rings 146 and 148. The passageway 152 intersects the bore 150 so that fluid may flow between the tube 112 and the reservoir 125 when the bore 150 is unobstructed.

Bore 150 has a valve 156 including a stem 162 and a head 164. The head 164 seats at 166 in the bottom of recess 142 and the stem 162, which has a smaller outside diameter than the diameter of bore 150, is slidable within the bore 150. The valve 156 can be moved so that the head 164 engages or disengages valve seat 166. An O-ring 167 mounted in the valve head 164 seals the valve head against the seat 166. One end of a compression spring 168 impinges upon the valve core 114 in the enlarged portion 153 of bore 150. The other end of the spring 168 is snap fit into a groove 169 formed in the valve stem 162. Spring 168 continuously urges valve head 164 into a closed position against the seat 166.

A fulcrum arm 172 is rigidly mounted upon the lower end of tube 112 and is pivotally attached by a pin 174 to a foot operably lever 176. One end of lever 176 engages the bottom end of valve stem 162. The lever 176 has a peddle end 178, which when actuated downwardly, will cause the valve stem 166 to raise thereby lifting the valve head 164 away from the valve seat 166 so that hydraulic fluid may flow between the reservoir 125 and the interior of cylinder 112.

The recess 142 in valve core 114 also serves as a seat for check valve 154. In the illustrated embodiment, the check valve 154 is in the form of a ball and can be seated at 158 on the upper edge of recess 142. An orifice 160 is formed in the valve core 114 to communicate the interior of tube 112 and the recess 142 so that fluid may flow between the tube 112 and the reservoir 125 through the orifice 160 when the check valve 154 is seated on the seat 158.

The portion of the reservoir 125 above the dashed line 182 is preferably filled with compressed air and the portion of the reservoir below the dashed line 182 and the tube 112 preferably contain hydraulic fluid. An air inlet valve 183 is provided in the lower header 128 so that compressed air may be introduced periodically for recharging the reservoir 125 with air.

in the operation of the power unit, the seat (not shown) may be raised when the user removes his weight from the seat and presses the peddle 178 downwardly with his foot. Downward displacement of the peddle causes the valve head 164 to be displaced off from the seat 166. The compressed air in the reservoir 125 will then force hydraulic fluid to raise the check valve 154 from the seat 158 and the fluid thereafter flows into the tube 112 causing the ram 106 and the seat to rise.

The seat and ram 106 will rise until the shoulder 119 on the rod contacts the lower surface of the bearing 116 or alternatively, when the valve 156 is closed.

To lower the seat, the foot is again placed on the peddle 178 causing the valve 156 to open. The weight of the user is then placed on the seat so that the downward force of the weight of the user causes the ram 106 to force hydraulic fluid out of the tube 112 through the bore 150, passageway 152 and out through the apertures or ports 151. The hydraulic fluid is then forced into the reservoir thereby compressing the air in the upper portion of the reservoir.

The seat and ram 106 can be lowered until the bottom of rod 110 contacts the top of the valve core 114 or until the valve 156 is closed. As soon as the flow of hydraulic fluid from the tube 112 is directed to the reservoir 125, the check valve 154 moves downwardly and seats over recess 142. Fluid flow is therefore restricted to flow through the small orifice in the valve core 114. Thus, the seat and ram 106 will descend gradually to the restrictive flow of fluid. It is also noted that the check valve 154 will fit into a recess 184 in the bottom of the rod 110 when the seat is fully lowered.

Reference is now made to FIG. 5 wherein the power unit generally designated is shown. Power unit 190 is similar in many respects to the power unit illustrated in FIG. 4, like parts having like numerals throughout. The power unit 190 differs from the power unit 100 in that a reservoir housing 196 is substituted for the cylinder 124. The housing 196 has an upper portion 192 secured in fluidtight relation to the tube 112 and has a generally bell-shaped configuration which supports the power unit 109 upon the floor. A reservoir 125 is formed between the tube 112, the bell-shaped housing 196 and a dishshaped bottom 198 secured, such as by welding to the tube 112 and the bell-shaped housing 196. In the FIG. 5 embodiment, a foot lever 200 has been extended through an opening 202 in the bell-shaped housing 196. Lever 200 operates in a manner substantially similar to lever 176 above described.

A boss 204 has been formed in the dish-shaped bottom 198 and the boss receives an air inlet 206 so that compressed air may be injected into the reservoir 125 to recharge the power unit 190 when necessary.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. An extensible power unit comprising:

a ram;

an annular reservoir having an axial bore defining a cylinder having selective open communication with said reservoir at one end of said cylinder and telescopically receiving said ram at the other end of said cylinder;

fluid seal means interposed between said ram and said cylinder,

valve means comprising a valve core mounted in the one end of the cylinder, in communication with the reservoir, the valve means comprising a valve stem axially aligned with the cylinder and having an actuating end exposed through the core exterior of the power unit, a valve head positionable upon a matting valve seat formed in said valve core and lever means actuating the valve stem to a selected open or closed position; and

check valve means comprising a spherical ball and a mating seat formed in said valve core permitting, when the valve means is open, rapid flow of fluid in one direction between the cylinder and the reservoir and restricted flow tion and having the member engaging surfaces of said lips formed relatively smooth to minimize friction between said members and said seal.

3. The device of claim 1 wherein:

difierential pressure is maintained across said seal, and

said seal is disposed with said central portion extending on the low-pressure side of said seal and said lips extending on the high-pressure side of said seal.

l 1' II t

Claims (3)

1. An extensible power unit comprising: a ram; an annular reservoir having an axial bore defining a cylinder having selective open communication with said reservoir at one end of said cylinder and telescopically receiving said ram at the other end of said cylinder; fluid seal means interposed between said ram and said cylinder, valve means comprising a valve core mounted in the one end of the cylinder, in communication with the reservoir, the valve means comprising a valve stem axially aligned with the cylinder and having an actuating end exposed through the core exterior of the power unit, a valve head positionable upon a mating valve seat formed in said valve core and lever means actuating the valve stem to a selected open or closed position; and check valve means comprising a spherical ball and a mating seat formed in said valve core permitting, when the valve means is open, rapid flow of fluid in one direction between the cylinder and the reservoir and restricted flow of fluid in the other direction between the cylinder and the reservoir.

2. The device of claim 1 wherein said fluid seal means comprises: an annular seal formed of resilient material having a generally V-shaped cross section with a central portion and inner and outer lips which diverge linearly from said central portion to engage adjacent members and which, when displaced towards each other, present a combined thickness substantially equal to that of said central portion and having the member engaging surfaces of said lips formed relatively smooth to minimize friction between said members and said seal.

3. The device of claim 1 wherein: differential pressure is maintained across said seal, and said seal is disposed with said central portion extending on the low-pressure side of said seal and said lips extending on the high-pressure side of said seal.

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