US2453855A

US2453855A - Hydraulic lock

Info

Publication number: US2453855A
Application number: US787349A
Authority: US
Inventors: Wilbur C Ollver
Original assignee: Adel Precision Products Corp
Current assignee: Adel Precision Products Corp
Priority date: 1947-11-21
Filing date: 1947-11-21
Publication date: 1948-11-16
Anticipated expiration: 1965-11-16

Description

NUV. 16, 1948. w, C, QLNER 2,453,855

'HYDRAULIC LocK Y Filed Nov. 21, 1947 /NvENTo/a. 1 W/Luf? C. OLII/ER BY 'HIS ATTORNEYS. YHfa/m/s, K/EcH, FOSTER a: HARK/.s

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for controlling Patented Nov. 16, 1948 UNITEDA STATE S PATENT vOFFICE 1 Adel Precision Products a corporation of Califo Corp., Burbank, Calif.,

mia

Application November 21, 1947, `Serial No. 787,349

l Claims. 1

This invention relates to Ilocking devices and particularly to a locking device of a hydraulic type having a cylinder and a piston slidable in the cylinder, the cylinder being adapted for' connection to one of :two relatively movable elements of mechani-sm and the piston being adapted to be connected to the -other of said elements, the arrangement being su-ch that flow of iluid from either side of the piston to -the other side thereof permits relative movementl between said elements but the prevention of such flow serves to lock said piston and Icylinder against relative movement of said elements. More specifically, the invention .pertains to a hydraulic lock which includes means the flow of iluid between the opposite sides of the piston in such a manner that the elements of mechanism can -be relatively adjusted toward each other at th-e will of an operator i and thereafter automatically locked in such adjusted relationship. However, the elements can be relatively separated at any time wi-thout disturbing the locking thereof against relative movement toward each other. The hydraulic device thus permits relative adjustment between the elements and automatically locks the elements in their adjusted position. The presentlocking device can be advantageously employed, for example, in prosthetic devices ofthe general type dis- -closed in an application for patent on hydraulically controlled artificial leg led concurrently herewith, for controlling the flexing of the knee and ankle in such manner that collapse of the leg under the weight of an amputee is positively prevented.

One object of the present invention is to provide an adjustment-permitting and locking device, of the character referred to, which permits infinite degrees of relative adjustment of two elements of mechanism between nected.

Another object is to provide a hydraulic device of the type indicated which includes a cylinder and a pis-ton slidable in the cylinder, said device embodying control means for controlling the flow of hydraulic uid in one direction within the cylinder so that the cylinder and pistoncan be relatively contracted to infinite degrees and thereafter automatically locked against further contraction, said control means having no effect upon flow of the fluid in the opposite direction so that relative extension of the cylinder and piston is permitted at all times. l

Another object is to provide a. hydraulic device of the specified type in which the piston has a main passage between its opposite sides and a whi-ch the device is con-v manuallyrcontrolled, normally closed, main valve adapted'to be actuated to open the passage to permit relative contraction and relative extension of the cylinder and piston, 4the device also including -a second passage yformed in the piston and main valve yand an lauxiliary valve normally operative'to close said second passage, the auxiliary valve being adapted to be opened in response to an external force tending to effect relative extension of the cylinder and piston so that such extension is permitted but contraction is prevented.

Another object is to provide a device, oi' the character referred to, which includes a relief valve which functions to relieve sudden increases in pressure of the fluid in one end of the cylinder, due to shock loads imposed externally against the device and tending to relatively contract the cylinder and piston, so as to prevent damage o1' the ,parts of the device.

Another object is to provide -a device having means whereby volumetric changes in the uid content of the cylinder are compensated for automatically.

Another object is to provide a device, of the class referred to, in which the main valve is adapted Ito be slid axially within the piston to closed position by spring means, .and adapted to be slid in thereverse direction to open position by means of a manually-operable valve-actuating rod slidable axially within the piston rod and engageable with the valve.

Another object isl to provide an adjusting and in construction, manufacture and performing its intended funclight in weight, economical to highly eiiicient in tion.

Further objects of the invention will be apparent from the following description and from the drawing, which is intended for the purpose of illustration, and in lwhi-ch:

Fig. 1 is a longitudinalsectional view through the improved adjusting and locking device showing the device extended;

Fig. 2 is a fragmentary longitudinal sectional view of a portion oi' the hydraulic cylinder and the piston, taken on the line 2-2 of Fig. 1, showing the main valve closed;

Fig. 3 is a view similar to Fig. 2 but showing the main valve open; and

Fig. 4 is ya cross-sectional view taken on line 4 4 of Fig. 2.

Referring to the drawing in detail, my improved device is shown as applied to use in controlling relative movement of a first element 5 and a second element 6. In one typical embodiment. the

element may represent; the thigh member of an artificial leg while the element 8 might be the foot member ol the prosthetic device disclosed in my pending application referred to previously. In any event, it is desirable that the elements 5 and 6 berelatively adjustable :toward and away f rom each other and, in the typical case discussed above, it is imperative that the elements, having once been adjusted, be locked against movement toward each other to prevent collapse of the structure of which they form an important part.

The present device functions to permit such relative adjustment of the elements of mechanism in response to movement of a manually controlled valve, forming a part of the device, and to positively lock the kelements against further relative movement toward each other. In certain mechanisms, it is desirable that one element be movable in a direction away from the other element without requiring the manipulation of control means and the present device is so constructed that relative movement of the elements 5 and Ii away from each other can be readily accomplished by merely drawing one element away from the other. In the event that the locking device is incorporated in an artificial leg in the manner referred to above, it is essential that the device be extensible and contractible during certain phases of a locomotion cycle to permit ilexing and unflexing of the knee and ankle, and that the device be extensible but not contractible during other phases of the cycle so as to allow straightening of the leg while preventing flexing of the knee which might result in collapse of the leg and injury to the amputee.

The adjusting and locking device I8 includes a hydraulic cylinder II having one end closed by an end wall I2. The end wall I2 may have a threaded extension in the form of a stud I3 onto which may be screwed a connector member I4. The connector member I4 may be pivotally joined to the element 5 by means of a pin I5 in the manner illustrated in Fig. 1. ing I6 is provided in the end wall I2 through which hydraulic fluid can be introduced into the cylinder I I, the opening being normally closed by a filler plug I1. Secured within the opposite end of the cylinder II is an annular head I8 which has a series of ports I8 extending therethrough. The head I8 may b e sealed by a resilient sealing ring I9'.

Slidable within the cylinder Il is a piston 20 which has a hub portion 2l at its end nearest the head I8 and an axial extension 22 directed toward the end wall I2. The piston 20 divides the cylinder II into two

chambers

23 and 24, the chamber 23 being hereinafter referred to as a lowpressure chamber, and the chamber 24 being termed a high-pressure chamber. The piston 28 has a peripheral groove 25 in which is disposed a sealing ring 26 for preventing leakage of iluid through the annular clearance space between the exterior of the piston and the interior wall of the cylinder II. The piston 20 has an axial bore 28 extending throughout the greater portion of its length, the bore being enlarged at 29 and again at 30 to provide a valve-seat 3l between the enlarged portions. Within the hub portion 2| is a transverse wall 32 in which the bore is substantially reduced in diameter for a purpose to be later explained. Above the wall 32 is a radial hole 32 which communicates between the chamber 23 and the bore 28.

Drilled diagonally through the piston 20 and communicating between the bore 28 and the low- A filler openpressure chamber 23 is a series of holes or ducts 33. A plurality of radial orifices 34 are provided in the extension 22 and communicate between the bore 28 and the high-pressure chamber 24. The ducts 33 and orifices 34, together with the bore 28, provide a main or primary passage through which hydraulic fluid is adapted to pass from either

chamber

23 or 24 to the other chamber. Adjacent its end, the extension 22 has a plurality of ports 35 which communicate between the enlarged portion -38 of the bore 28 and the highpressure chamber 24.

Secured within a counterbore 31 in the end of the hub portion 2I -of the piston 20 by means of screws 38, is one end of a tubular piston rod 40 which is adapted to slide axially through the axial hole in the cylinder head I8. The outer end of the piston rod 40 is preferably screwthreaded to adapt it to be screwed into the element Ii as shown in Fig'. 1, the rod being held in place by a lock nut 4I.

A main valve 44 is slidable in the bore 28 of the piston 20 and has a peripheral groove or channel 45 which, when the Valve is in the position shown in Fig. 3, serve as part of the main fluid passage, referred to previously, through which fluid can pass from the chamber 23 to the chamber 24, and vice versa to permit extension and contraction in the over-ali length of the device. The main valve 44 has a bore v4I; in its end which is disposed nearest the end of the extension 22, and a, by-pass opening 41 communicating between the channel 45 and the bore 46. A compression spring 48 is disposed between the inner end of the bore 46 and an annular element 48,A

held in place by a snap ring 50, and is adapted to normally urge the main valve 44 in a direction to cause the latter to overlie and close the orifices 34.

The main valve 44 is adapted to Ibe slid from the position shown in Fig. 2 to that illustrated in Fig. 3 by means of a manually controlled pushrod 52, which is slidable within the piston rod 40, the inner end of the push-rod being adapted to engage the en d of the valve. The outer extremity of the push-rod l52 extends into an opening 53 in the element 6 to adapt it to be eng-aged by a finger 54 projecting laterally from a slide member 55 slidable on the element. A sealing ring 455 is employed for preventing leakage of iluid around the push-rod 52. The slide member l55 may be actuated by any suitable means such as the cord or cable 56 shown herein, or by afoot contact member as disclosed in my pending application. The inward sliding movement of the push-rod 52 may be limited by an adjustable setscrew 5`I on the element 6 engageable 'with the finger 54. The push-rod 52 and nger 54 are normally urged to the position shown in Fig. 1 under the influence of the spring 48, and such outward sliding movement of the push-rod may be limited by one or more shims 58 on the element 6, against which the end of the rod engages.

Secured to the outer face of the head I8, in any suitable manner, is one end of a tubular expansible-contractible element 60 which preferably is in the form of a metal bellows. The bellows element 60 has an annular end plate 6| through which the piston rod 40 extends and is adapted to slide. A sealing ring 62 is carried by the end plate 6i and engages the periphery of the piston rod 40 to prevent leakage of fluid through the annular clearance space between vthe piston rod and the end plate.' It will be noted, by reference to Fig. 1, that the bellows element 68 provides an expansion chamber 63 into which hydraulic uid can flow chamber 23, by way of the ports I'3 in the head I8. By this means, the changes in volume of the hydraulic fluid occurring in the low-pressure chamber 23 during sliding movement of the piston 20 in opposite directions' is accommodated.

by the bellows element which is adapted to expand and contract axially in response to such changes in volume.

An auxiliary valve 65 is extension 22 of the piston of thimble shape as shown in rim of the valve spherical flange -56 which is adapted to engage the valve seat 3l of the piston 20. The valve 65 is normally held in suchfclosed position by means of)a compression spring 61 having one of its ends disposed within the 20 and is preferably Figs. 2 and 3. The

engaging the side of the flange 6B and its other end seated against an annular element 63 held in the enlarged bore 30 lby means ofl a snap ring 69. It is thus apparent that the valve 65 is normally held in closed position by the spring 61 so as `to prevent passage of hydraulic fluid from the high- .25

pressure chamber 24 to the low-pressure chamber 23 by way of the secondary passage which includes the ducts 33, channel 45, by-pass opening 41, bores 28, 23 and 30, and the ports 35. However. the valve 65 is adapted to open against the action ofthe spring 61 in response to fluid pressure developed within the bore 28 in excess of the pressure within the chamber 24, when the main valve 44 is in the closed position shown in Fig. 2. By this provision, even though the main valve 44 is closed, that is, in a position to cover the orices 34, the fluid is permitted to flow from the chamber 23 into the chamber 24 so that relative extension of the hydraulic locking device and separation of the elements 5 and 6 are permitted. Moreover, due to the provision of the hole 32' and

passages

33, 45 and 41, the pressure in the chamber 23 is exerted against both the lower and upper ends of the valve 44 so that the valve is balanced regardless of any pressure dilerential between opposite sides of the piston 20. Consequently, themain' valve 44 can be operated by consistent valve operating forces of relatively low magnitude.

The auxiliary valve 65 is provided with an opening 10 in its end wall and this opening is normally closed by a pressurerelief valve element which may be in the form oi' a ball 1I. The ball 1I, which is disposed within the hollow valve 65, is normally held in a position to close the opening 10 by means of a spring 12 which has one of its ends engaging the ball and its other end resting against a snap ring 13 within the valve 65. One or more shims 14 may be interposed between the spring 12 and the snap ring 13 to accurately adjust the force applied by the spring and thus ad` just the valve 1I to cause it to openinresponse to pressures in excess-of a predetermined value. The purpose of the relief valve 'II is to relieve the uid pressure in the high-pressure chamber 24 when the pressure therein is suddenly increased due to any sudden shocks imposed against the element 5 and cylinder II, so as to prevent damage to the parts of the hydraulic locking device I0.

For the purpose of illustration, let us assume that the cylinder II of the hydraulic locking defrom the low-pressure.

65 is provided with a part-- Ymember 55 is in the from the chamber 24 into the 3 a mechanism. When inder II are in the relative positions Fig. 1, the element 5 is spaced from the element 6'to nearly maximum extent. When the slide position shown in Fig. 1, and the push-rod 52 is thus in its outermost position, the main valve 44 assumes the position shown in Fig. 2 so that the orifices -34 are closed thereby. y Consequently, passage of hydraulic fluid chamber 23 through the primary passage, which includes the ducts 33, channel 45 and orifices 34, is prevented. Likewise, the auxiliary valve 65 prevents such flow of fluid through the secondary passage, which includes the ports 35, bores 30, 29, 28, bypass opening 41, channel 45 and ducts 33, so that the cylinder II and piston 2U are locked against relative contraction. That is to say, the cylinder I I is prevented from moving downwardly with respect to the piston 20, as viewed in Fig. 1, so,` that the element 5 is thus prevented from moving closer to the element 6 and this safeguards against collapse of the structure.

The hydraulic locking device IIl will withstand considerable force applied against the element However, should the element 5 be subjected to a force of such magnitude that damage to the various parts of the locking meansv might result, such shock loads will tend to cause a sudden increase of fluid pressure within the chamber 24 which is immediately relieved by the valve 1I,

vice I 0 is connected to the element 5, which is movable toward and away from the element 8, and that the piston rod 40 is joined to the element 6, which may be considered a fixed part of which opens in response Ato such sudden increases ln pressure to permit momentary flow of the uid through the valve element 65, bores 29, 28 bypass opening 41 and ducts 33 and into the lowpressure chamber 23. I

It has been explained that the elements 5 and 6 can be 4relatively separated, even though the main valve 44 is closed, such movement being desirable in some mechanisms in order to permit the element 5 to be moved away from the element 6, Without necessitating unlocking of the hydraulic lock. To effect such adjustment of the element 5, the latter'is merely drawn for- 'wardly and such force tends to increase the fluid pressure within the chamber 23 of the fluid-filled cylinder I I. When the pressure within the chamber 23 overcomes the combined pressure in the chamber 24 and the force of the valve spring 61, the auxiliary valve 65 will be unseated, as

indicated by dot-and-dash lines in Fig. 2, so as flow from the chamber 23 into the chamber 24 by way of the

secondary passage

33, 41, 28', 23, 30 and 35. It is apparent, therefore, that the element 5 can be adjusted to a position more remote from the element 6 by merely drawing the element 5 to permit iiuid to justed in this direction, is prevented from moving in the opposite direction due to the fact that the valve 65 is then closed automatically by the spring 61.

' When it is desired to move the element 5 closer to the element 6, the operator merely pulls the cord 56 or other means, such as a rod, and pushes away therefromy and that the element 5, having once been ad-4 Achamber 23, by way oi .the main passage 3l, l!

and 33, so that the wardly with respect to lock the element 5 against further movement in a direction toward the iixed element 6 but allows the element 5 to be moved to a more remote position as previously explained. During the extension of the locking device, volumetric changes in the fluid within the chamber 23 are compensated for by the bellows element 6B which is capable of expanding and contracting longitudinally. The small radial hole 32', previously mentioned,l serves to balance the valve 44 by exposing both ends of the valve to the same pressure, and thus prevents a hydraulic lock in the chamber 23 by permitting the free flow of fluid through the passages 33, Mi and 4l.

The present locking device is applicable for use with various mechanisms wherein it is desirable that relative movement be permitted between two elements of mechanism and that the elements be locked in their adjusted positions in such a manner that unwarranted movement of the elements toward each other is prevented but relative movementof the elements away from each other is readily attained without readjusting the internal valving mechanism of the locking device. Y

While I have herein shown and described the adjustment-permitting and locking device as embodied in 'a preferred form of construction, and applied to use in a particular manner, it Will be apparent that various changes might be made therein without departing from the spirit of the invention. Consequently, I do not Wish to be limited in this respect, but desire to be afforded the full scope of the appended claims.

I claim as my invention:

1. In an adjustment-permitting and locking device adapted to adjustably'interconnect two relatively movable elements, the combination of i a fluid lled cylinder adapted to be connected to one of the elements; a piston slidable in said cylinder .and provided with a rod adapted to be connected to the other of the elements, said piston having a first fluid passage therein adapted to communicate with the interior of said cylinder at opposite sides of said piston, said piston also having a port therein; a main iluid balanced valve movable in said piston and having a by-pass opening in fluid communication with said port, said by-pass and port providing a second iiuid passage through which fluid can pass from one end of said cylinder to the other end thereof; spring means operable to move said main valve in one direction to close said first passage so as to lock said cylinder and said piston to prevent longitudinal contraction of the device; manually operable means for moving said main valve in the opposite direction to open said rst passage so as to unloclf: said cylinder and said piston and permit relative movement thereof in opposite directions so as to allow longitudinal extension and contraction of the device; and an auxiliary valve in said piston between said by-pass and said port and normally operative to close said second fluid passage but adapted to be opened in response to fluid pressure in said by-pass opening, when said main valve is closed, so as to permit longitudinal extension of said device.

2. A device as defined in claim l, wherein said piston has a bore in which said main valve and said auxiliary valve are movable, said bore being enlarged at one end to define a valve seat disposed between said by-pass opening and said port and against which said auxiliary valve is adapted to normally seat, said bore forming part of said first and second fluid passages.

3. In an adjustment-permitting and locking device adapted to adjustably interconnect two relatively movable elements, the combination of: a fluid lled cylinder adapted to be connected to one of the elements; a piston slidable in said cylinder and provided with a rod adapted to be connected to the other of the elements, said piston having an axial extension, a first side, a second side and an axial bore, said piston being provided with at least one duct extending between said first side and said bore, at least one orifice extending between said bore and the exterior of said piston adjacent saidsecond side, said duct and orifice defining with said bore a rst fluid passage through which fluid can pass from either side of said piston to the other side thereof, said piston also having at least one port in and adjacent the end of said extension communicating between said bore and the interior of said cylinder, said bore being enlarged adjacent the end of said extension to define a valve seat; a main fluid balanced valve slidable in said bore and having a peripheral channel through which fluid can flow between said duct and orifice, said main valve having a by-pass opening communicating between said channel and said bore within said extension, said by-pass opening and said port providing with said bore a second fluid passage through which fluid can pass from one end of said cylinder to the other end thereof; spring means operable to move said main valve in one direction to overlie said orifice and thus close said rst passage so as to lock said cyllnder and said piston against relative movement in a direction which would cause longitudinal contraction of the device; manually operable means for moving said main valve in the opposite direction to open said first passage so as to unlock said cylinder and said piston and vpermit longitudinal contraction and expansion of the device; and a spring actuated auxiliary valve in said piston normally disposed against said seat to close said second fluid passage but adapted to be opened in response to fluid pressure in said by-pass opening, when said main valve is closed, so as to permit longitudinal extension of said device.

4. A device as defined in claim 3, in which said piston divides said cylinder into a first chamber at said rst side of said piston and a second chamber at said second side thereof, said device also including a pressure relief valve movable within said extension and disposed between said second chamber and said bore, said relief valve being normally closed to prevent ilow of uid from said bore into said second chamber but adapted to be opened in response to fluid pressures in said second chamber in excess of a predetermined value so as to permit flow of fluid from said second chamber, through said bore, said by-pass opening and said duct into said iirst chamber.

5. A device as defined in claim 4, in which said auxiliary valve has an axial bore and an end Wall provided with a valve opening, said relief valve being disposed in said boreland adapted to open and close said valve opening.

6. A device as dened in claim 5, and including spring means within said auxiliary valve and engageable with said relief valve and normally operative to yieldingly maintain said relief valve in position to `close said valve opening.

7. In an adjustment-permitting and locking device adapted to adjustably interconnect two relatively movable elements, the combination of: a uid lled cylinder having a closed end adapted to be connected to one of the elements; an annular cylinder head secured to the other end of said cylinder and providing an end wall therefor, said head having at least one port therein through which the iuid can pass into and from said cylinder; a pis on slidable in said cylinder and providing a first chamber and a second chamber at opposite sides of the piston, said first chamber being located between said piston and said cylinder head, `said piston having passages therein through which uid can flow from either chamber to the other chamber; a tubular piston rod projecting from said piston and slidable axially through said head, said rod being adapted to be connected to the other of the elements; valve means movable in said piston and adapted to open and close said passages in a manner such that fluid can flow from said first chamber into said second chamber to permit relative movement between said piston and said cylinder in a direction'to allow 'adjustment of the elements away from each other, said valve means being normally operative to prevent fluid ilow from said second chamber into said irst chamber and thus lock said piston and said cylinder against relative contraction to prevent movement of the elements toward each other; manually operable means for actuating said valve means to permit fluid ow from said second chamber to said rst chamber; and a hollow, expansible-contractible member secured to said cylinder head with its interior communicating with said rst chamber through said port, said member being adapted to expand and contract to compensate for volumetric changes in the uld during relative movement between said cylinder and said piston.

8. A device as defined in claim '7, in which said expansible-contractible member is substantially cylindrical and has one end secured to said cylinder head in duid-tight relation thereto, said member projecting from said head in spaced concentric relation to saidpiston rod and having its other end joined to said rod in fluid-tight relation theretor 9. A device as defined in claim 8 in which said expansible-contractible member comprises a bellows.

10. A device as defined in claim 9, in which said otherend of said bellows includes: an annular flange surrounding said piston rod and through which said rod can4 slide; and sealing means disposed between said flange and said piston rod.

WILBUR C. OLIVER. No references cited.