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Publication numberUS3584331 A
Publication typeGrant
Publication dateJun 15, 1971
Filing dateJun 13, 1969
Priority dateJun 13, 1969
Publication numberUS 3584331 A, US 3584331A, US-A-3584331, US3584331 A, US3584331A
InventorsHooge Richard E D
Original AssigneeRixson Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hydraulic door checking mechanism
US 3584331 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

R. E. D'HooGE. HYDRAULIC DOOR CHECKING MECHANISM Filed June 13, 1969 2 Sheets-Sheet 1 han@ i5, N71 R. E. DHOOGE 3,534,333

HYDRAULIC DOOR CHECKING MECHANISM Filed June 1:5, 1969 2 sheets-smet 2 102 1 "5v K f5 L50 25,6 i 95 d@ JQ,

46 Z4 Jag 42N J6 35 32 QT- L 6525453 T A 22 d* T 4 n 1 7110 93 /m f" f M 7' 9 4 6.375 75 66 (s2 ya .9095@ JUZ ,700 n rdf/ United States Patent O 3,584,331 HYDRAULIC DOOR CHECKING MECHANISM Richard E. DHooge, Wood Dale, Ill., assignor to Rixson Inc., Franklin Park, Ill. Filed June 13, 1969, Ser. No. 832,900 Int. Cl. Ef 3/12 U.S. Cl. 16-82 8 Claims ABSTRACT OF THE DISCLOSURE A hydraulic door checking mechanism, for a door control device, having a single hydraulic cylinder and a selfcontained fluid system with a piston having a piston rod movable into and out of the iiuid system and providing door checking in both directions of operation and latch control, together with sealing means for the shaft and a variable volume reservoir for the hydraulic iluid.

BACKGROUND OF THE INVENTION In prior hydraulic door checking mechanisms for providing a door checking action in both directions of movement of the door it has been known to have a pair of hydraulic cylinders, each with a piston and a piston rod, one cylinder and piston serving to check the door action in one direction, and the other cylinder and piston serving to check ythe door action in the other direction. See, for example, Ellis Pat. No. 2,866,224. In many such structures the hydraulic uid is discharged from the cylinders into the housing of the door control device while in others there is a self-contained hydraulic fluid system. In all such structures the added cos-t, increase weight and increased size resulting from two pistons and cylinders present disadvantages.

Due to the fact that in current building construction there is less space available than formerly for door control devices, more narrow devices have been devised such as the -Door Closer Mechanism of Ellis Pat. No. 3,040,- 372. That structure employs a self-contained hydraulic system having a pair of pistons working in unison in a pair of side by side cylinders which are interconnected and have associated fluid reservoirs. In one form of the device of that patent the reservoirs, which supply makeup uid to fill the space vacated by the pistons as they leave the hydraulic cylinders during door opening movement, are shown as expandible and contractible. The pistons of that door closer mechanism each have a unidirectional check valve which is operative on door opening to allow ready door opening movement, and there is no back check provided by the hydraulic system.

In providing back check in the structure of the present invention which has a single double acting piston in a single cylinder of a self-contained hydraulic system, the piston must have no check valve in it. In using such piston and at the same time in permitting rapid opening of the door with back check, while also seeking to use a flexible reservoir, the problem of blowing out, or rupturing, the ilexible reservoir was encountered, due particularly to heavy fluid surges distributed to the reservoir during door opening movements. Ultimately II was able to overcome the problem, while yet providing back check and also stroke and latch control with a compact double-acting piston in a self contained hydraulic system by inventing the structure described and claimed hereinafter.

Accordingly it is an object of this invention -to provide a closed circuit hydraulic door checking mechanism which is compact and simple in construction while yet providing the desired functions of back check and stroke and latch control.

It is another object to provide such a mechanism in rice the form of a readily removable and replaceable component for a door control device.

It is yet another object to provide a hydraulic door checking mechanism having a single cylinder and single double-acting piston with a single piston rod, and with a self contained fluid system, which has greater reliability of performance under varying conditions.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. l is a small scale diagrammatic plan view of a door control device with its cover plate removed showing the location o'f the hydraulic cylinder of a hydraulic door checking mechanism, a spring and spring housing, and interconnecting linkage which joins the spindle of the door closing mechanism with the spring and with the piston rod of the hydraulic cylinder;

FIG. 2 is a semi-diagrammatic sectional View showing the hydraulic cylinder and associated structure in larger scale with the piston being disposed in the hydraulic cylinder in a position corresponding to a closed door position;

FIG. l3 is a view similar to FIG. 2' but showing the piston in a different position corresponding to an opening movement of the door, With the arrows indicating the direction of fluid flow in response to piston movement;

FIG. 4 is a view similar to FIG, 2 but showing the piston in a position corresponding to that part of the door opening movement wherein back checking begins to take place and by-passing of fluid around the piston lthrough the by-pass line has just terminated;

FIG. 5 shows the piston in a position corresponding to approximately the end of the door opening movement and checking of the door, the arrows showing the path of `iiuid flow from one side of the piston to the other through the metering valve and reservoir;

FIG. 6 shows the piston in a position corresponding to a door closing movement with the movement of the door being checked and the fluid flowing in the direction indirected by the arrows through a metering valve and the reservolr;

FIG. 7 shows the piston in a position corresponding t0 the nearly closed position of the door when the metering valve for checking the closing movement of the door has been closed off by the piston and uid iiow is shown by the arrows as passing through the latch metering valve and passageway;

FIG. 8 is a plan View, on smaller scale, of a modified exible Wall portion of the reservoir; and

FIG. 9 is a plan view, also on smaller scale, of the cover plate for the reservoir.

GENERAL DESCRIPTION OF THE STRUCTURE While there will be described below an exemplary embodiment of the invention, it will be appreciated that the invention lends itself to other embodiments or modifications within the scope of the appended claims.

Referring now to FIG. 1 of the drawings there is shown, diagrammatically and on small scale, a door control unit, indicated generally by the reference numeral 10, which has a housing 12 the cover plate of which has been removed in order to show the internal components. Interiorly of the housing 12 is shown a spring housing 14 for a spring 16 which has one end abutting against a wall 18 within the housing. At the right hand end of the spring, as viewed in FIG. 1, there may be connected a shaft 20 which extends through the center of the spring 16 and housing 14 and passes through an aperture (not shown) in the abutting wall 18. Shaft 20, when moved toward the left, compresses spring 16.

The hydraulic door checking mechanism, indicated generally by the reference numeral 22 comprises a hydraulic housing 24 out of which extends a piston rod 26 which also extends through the abutting wall 18. Linkage, indicated generally by the reference numeral 28 serves to connect both the shaft 20 and piston rod 26 to the spindle 30, which spindle in turn is connected to an driven by a door (not shown) which is to be controlled by the door control um't 10.

Details concerning the foregoing structural elements and the manner in which they are supported in the housing 12 can be found in the co-pending application of William A. Czapar, Ser. No. 790,089, led Jan. 9, 1969, for Door Control Means.

Considering now in greater detail the hydraulic door checking mechanism, reference should be made to FIGS. 2 through 7. The housing 24 is closed at one end as at 32 and deines a bore 34 which extends the long way of housing 24. A piston 36 has a close sliding fit within the bore 34 and is connected by a pin 38 to a piston rod 40. The piston rod 40 extends outwardly of the end of the housing 24 opposite from its closed end 32 and in so doing passes through an end cap indicated generally by the reference number 42. Cap 42 has a threaded portion 44 adapted to be secured within the end of the housing 24 which is internally threaded, as at 46- An end tiange 48 on cap 42 bears against an end surface 50 of the housing and sealing gasket 52 is compressed between the flange 48 and end of the housing. The end cap 42 has a passageway or opening 54 extending through it and in alignment with the piston rod 40. Piston rod 40 passes through the passageway or opening 54 in extending outwardly of the hydraulic cylinder.

At the left end, as viewed in FIGS. 2 and 7, the end cap 42 is recessed as at 56 and receives a seal 57 which is in engagement with the piston rod 40. Toward the right end of the end cap there is disposed internally of the cap a bearing 58 Ifor the piston rod 40. That bearing, together with a radially inwardly directed ange 60 of the end cap confines an O-ring type of seal 42 which also engages the piston rod 40. The inner space of the end cap 42 which surrounds the piston rod 40 and lies between the low pressure seal 57 and the bearing 58 is a low pressure chamber 64 which, for example, might retain a pressure in the area of pounds per square inch, whereas the pressure inside the bore 34 to the right of the end cap, as viewed in FIGS. 2 through 7, may be in the area of 1000 pounds per square inch. The low pressure chamber 64 communicates with a reservoir, indicated generally by the reference numeral 66, by a passageway 68 in the end cap 42 which passageway communicates with a passage 70 in the housing 24 leading to one end of the reservoir 66. Because of the high pressure within the bore 34 it may cause a slight amount of hydraulic fluid to pass along the piston rod 40 toward the exterior of the housing. However, the fluid does not escape from the housing because the uid reaches the low pressure chamber 64 from which it may pass to the reservoir rather than escaping outwardly of the housing 24 and its bore 34.

The reservoir 66 is formed of a recess 72 in the side of the side of the housing 24 over which recess is disposed and sealed a cover plate indicated generally by the reference numeral 74. The recess extends `generally along the side of the housing and almost from end to end thereof. It will be observed that the recess 72 lies alongside the bore 34 and in a generally parallel relationship to it. Recess 72 is deeper at its central portion and at that central portion there is disposed a liexible wall portion for the reservoir, that Wall portion being indicated generally by the reference numeral 76. The resilient wall port 76 is formed as a shallow recessed member having a peripheral ange 78 by lwhich it is secured to the inner side of the cover plate 74 and is adapted to be explained toward that cover plate when the reservoir 66 fills with added liquid when the piston rod 40 enters the hydraulic system during a door closing operation. Consequently the reservoir 66 is a variable volume reservoir. The cover plate 74 is aperture, generally in its central portion, where it lies over the resilient Wall portion 76. As may be seen in FIG. 8, on smaller scale, the liexible wall portion 76 may have its shallow recessed structure divided by a rib 80 to give the wall portion greater rigidity. The apertured cover plate 74, as shown on smaller scale in FIG. 9, may have its apertured center portion 82 provided with a portion which overlies the rib 80.

The entire hydraulic system is lilled with hydraulic fluid and no air is used or desired. Prior hydraulic systems for door closer mechanisms which have used an air cushion in the hydraulic liuid reservoir suier from several disadvantages among which are the greater dimensions which are required, limitations on the position in which the door closer mechanism may be placed, and faulty operation due to air becoming distributed in the system when the mechanism is shipped or handled.

At each end of the bore 34 there are a pair of passageways, such as passageways 84 and 86 at one end, and 84 and 86' at the other end, which extend between the bore 34 and opposite ends of the reservoir 66. Passage- Way 84 has a back check metering valve 88 which is adjustable to permit greater or lesser flow through the passageway 84, and passageway 84 has a stroke metering valve which is also adjustable. Passageway 86 communiactes with an overpressure safety valve 92 in the wall of the housing 24 and also leads to a ball check valve 94. If the housing 24 is to be used in a position inverted from that shown, then valve 94 should be spring loaded. Similarly passageway 86 leads to 4an over-pressure safety valve 98 in the wall of housing 24 and to a spring loaded ball check valve 96. It will be seen that metered iiow of hydraulic fluid may pass from one side of the piston 36 to the other (with the direction of fluid depending upon the direction of movement of said piston) with the liquid flow passing, in series, through the reservoir 66.

A separate bypass line 98 has two openings leading to opposite sides of the piston during initial movement of the piston in a door opening movement and a spring loaded ball check valve 100 is disposed in the bypass line 98 to prevent ow through said line when the piston 36 is moving in a door closing direction. Said ball check valve 100 is disposed in a countersunk bore 102 in the housing 24 and that bore is closed by a `ball closure member 104 which also serves as a seat for the spring 101 of the spring loaded valve 100.

To the right of the passage way 86', as viewed in FIGS. 2 through 7, there is a latch passageway 106 leading from the bore 34 through the wall of the housing 24 and an opening 108 back to the bore 34. This latch passageway 106 has a latch metering valve 110 which is adjustable. Valve 110 and passageway 106 permit hydraulic fluid to pass around the piston during the nal closing movement of the door, for latching it, after the piston 36 has moved to cover the passageway 84' which contains the metering valve 90. Usually latch valve 110 is so adjusted as to let the door move just a little faster than previously in order that it will be sure to latch.

OPERATION OF THE HYDRAULIC DOOR CHECKING MECHANISM Assuming now that a door to be controlled by the door control unit 10 of FIG. l is in its closed position but is then moved toward an open position, the spindle 30 which will be connected with the door will be rotated and by means of the connected linkage 28 will pull both the piston rod 26 of the hydraulic door checking mechanism and also the shaft 20 which will serve to compress the spring 16. FIG. 2 of the drawings represents the position of the piston 36 within the bore 34 when the door is closed and FIG. 3 represents the position of the piston as the door is beginning its opening movement. It will be observed that piston 36 never covers passageway 86.

As the piston 36 and piston rod 40 move to the left, as viewed in FIG. 3, and away from passageway 86', passageway 84' then becomes uncovered. Bypass line 98 permits the bulk of the uid ahead of the moving piston 36 to readily iiow around the piston from one side to the other since the ball check valve 100 in line 98 is only lightly loaded toward its closed position and is readily overcome by the movement of the hydraulic fluid in the direction indicated by the arrows of FIG. 3. In this way no surge of iiuid into the reservoir will occur, so there is no danger of damaging or destroying the tiexible wall 76. Furthermore it will be observed that the bypass line 98 does not incorporate any portion of the reservoir 66 -but is entirely independent of it, and therefore there are no liquid surges of the tiuid from bypass line 98 into the reservoir which might damage the flexible wall, or diaphragm, 76 of the reservoir. While some fluid may tend to move through the passageway 84 and the metering valve 88, the bulk of the ow will be through bypass line 98 and will so readily ow th'at there is :little resistance from it to the opening movement of the door.

When the door has been opened suiciently that the piston has reached the position shown in FIG. 4, the piston will close off the bypass line 98 and back checking of the door will occur as fluid is then required to ow through the passageway 84 and metering valve 88, the reservoir 66 and past the ball check valve 96 and up through passageway 86 into the bore 34 on the opposite side of piston 36, as indicated by the arrows. This backchecking action continues as the piston further moves to the left as represented in FIGS. 4 and 5. FIG. 5 represents the position of piston 36 corresponding to the substantially fully open and checked position of the door and it will be observed that the bypass line 98 is still closed off at its left end by the piston 36. In the fully open position of the door the piston 36 never closes olf passageway 84 or 86.

When the person opening the door releases it, the spring 16 of the door closing unit 10 (FIG. 1) then acts through the linkage 28 to close the door and to move the piston rod toward the right. The piston then moves from its FIG. 5 position toward the right whereupon the hydraulic uid will ow through passageway 84 and the metering valve 90, the reservoir 66 and then past the ball check valve 94 through passageway 86 to the bore 34 on the other side of the piston, as shown by the arrows of FIG. 6. No ow of hydraulic fluid in the opening 108 or passageway 106 will occur during the greater part of the door closing movement. But when the piston reaches the position shown in FIG. 7, a position corresponding to the door having nearly reached its closed position, the piston will close off passageway 84 and uncover opening 108. Hydraulic uid will then pass from the right hand side of the piston out of bore 34 only through the passageway 106 which now permits the ow of fluid since the position of the piston in FIG. 7 has uncovered the opening 108 at the far end of the passageway 106. The latch metering valve 110 in latch passageway 106 is adjusted to permit a somewhat faster flow of fluid than through the metering valve 90 so that there will be a slightly faster movement of the piston and door to assure latching of the door as it reaches its final closed position.

Referring now to the reservoir 66 and particularly the flexible wall portion 76, it will be observed as one retraces the opening and closing of the door and the corresponding positions of the piston 36 and piston rod 40 that when the piston rod has its greatest inward position in the bore 34 a substantial space is occupied by that piston rod and that means that uid in the closed system must be transferred elsewhere. With the door in its closed position as represented by FIG. 2 it will be seen that the hydraulic fluid which is displaced by the piston rod 40 has been accommodated in the reservoir 66 by the movement of the flexible wall portion 76 toward the cover plate 74 thereby automatically providing an enlarged reservoir. As the piston moves during door opening movement, the piston rod increasingly passes out of the bore 34 and fluid which is then dra-wn in behind the moving piston is extracted from the reservoir. The exible Wall portion of the reservoir finally assumes a position somewhat corresponding to that of FIG. 5 when there is the least volume of the piston rod within the bore 34. When the door then returns toward its closed position it will be seen that the flexible wall portion 76 again moves toward the cover plate 74 as more and more of the piston rod 40 re-enters the closed fluid circuit and takes up space previously occupied by the hydraulic fluid. The overlying portion 82 of cover plate 74 will prevent the liexible Iwall portion 76 from bulging excessively. It can be seen therefore that a variable volume reservoir is provided. Because the reservoir has a variable volume by reason of the flexible wall portion, the reservoir may be completely lled with uid and requires no internal cushion of air.

Since the reservoir is located alongside and generally parallel to the bore 34 in housing 24 the overall hydraulic housing can be much shorter than if the reservoir were located at one end or the other of the housing. Furthermore, by forming the reservoir partially by the housing 2.4 fewer structural parts are required thereby reducing the cost of both construction and assembly. The manner in which the hydraulic door checking mechanism may be readily removed from the door control unit for either repair or easy replacement is disclosed in the aforementioned copending application of William A. Czapar, Ser. No. 790,089, filed Jan. 9, 1969.

From the foregoing it will be understood that an advantageous and improved hydraulic door checking mechanism has been provided by this invention.

What is claimed is:

1. For use in a door control device, a hydraulic door checking mechanism having a self-contained closed fluid system and comprising a housing dening a hydraulic cylinder having a bore, a double piston reciprocable in said bore for providing a door checking action in both direetions of movement, a rod connected with said piston and extending out of said bore, sealing means between the rod and the bore, a variable volume reservoir for hydraulic fluid communicating with said bore and comprising a flexible wall portion adapted to be expanded and contracted by fluid in response to movement of said rod into and out of said bore, said bore and reservoir being a part of said closed fluid system, means defining a path of fluid flow leading around the piston to and from said bore, and not including said reservoir, valve means operatively associated with said means defining a path of fluid flow and adapted to render said path inelfective when the piston is moving in its door closing direction, said housing including a recessed portion opening toward its side and covered by said exible wall portion to deline said reservoir, means carried by said housing for controlling the position of said flexible wall portion when expanded, Where said flexible wall portion has a pair of recessed portions and a rib portion between them and wherein the means carried lby the housing comprises an apertured cover plate having a portion overlying said rib portion.

2. For use in a door control device, a hydraulic door checking mechanism having a self-contained closed uid system and comprising a housing defining a hydraulic cylinder having a bore, a double acting piston reciprocable in said bore for providing a door checking action in both directions of movement, a rod connected with said piston and extending out of said bore, sealing means between the rod and the bore, a variable volume reservoir for hydraulic uid disposed in side by side relation to said bore and disposed in series in a path of fluid flow bet-Ween opposite sides of said piston, said bore and reservoir being a part of said closed fluid system, and means defining a path of fluid flow leading around the piston to and from said bore, and not including said reservoir, and valve means operatively associated with said means defining a path of uid ow and adapted to render said path ineffectivee when the piston is moving in its door closing direction, where said path of uid flow between opposite sides of said piston through the reservoir comprises a pair of passageways on either side of saidrpiston leading in parallel from said bore to said reservoir, one passageway of each pair serving to meter the flow of fluid from the bore and the other passageway being closed as the piston moves toward the pair in one direction of movement, and at least one of the passageways of the other pair of passageways on the other side of said piston then permitting ready access of the metered uid to the bore on said other side of said piston as the piston moves away from said other pair of passageways.

3. The mechanism of claim 2 wherein the pairs of passageways leading from the bore at opposite sides of said piston communicate with the reservoir at its opposite ends.

4. The mechanism of claim 2 together with a latch return line for uid leading from a position ahead of said piston during movement in its door closing direction and discharging into said bore on the opposite side of said piston when said piston closes the metering passageway toward which it is moving.

5. The mechanism of claim 2 wherein the iiuid in the bore on both sides of said piston is under high pressure and wherein a low pressure chamber is disposed in alignment with said bore and is traversed by said rod and is sealed relative thereto, and communicates with said reservoir.

6. The mechanism of claim 2 wherein the reservoir comprises a recessed portion in a side of the housing, an apertured cover plate having a sealed relation to said housing and overlying said recessed portion, and exible Wall means disposed in sealed relation in said recessed portion inwardly of said cover plate and expandable toward said plate.

7. The mechanism of claim 6 wherein the iiexible Wall means is secured to said apertured cover plate.

8. For use in a door control device, a hydraulic door checking mechanism having a self-contained closed iluid system and comprising a housing defining a hydraulic cylinder having a bore; a double acting piston reciprocable in said bore for providing a door checking action in both directions of movement, a rod connected with said piston and extending out of said bore; a variable volume reservoir for hydraulic fluid communicating with said bore, said reservoir comprising a recessed portion in a side of the housing, an apertured cover plate having a sealed relation to said housing and overlying said recessed portion, and exible wall means disposed in sealed relation in said recessed portion inwardly of said cover plate and expandable toward said plate, said flexible Wall means being secured to said apertured cover plate and having a pair of recessed portions and a rib portion between them, and said apertured cover plate having a portion overlying said rib portion with said plate being adapted to control the position of the exible overlying wall when it is expanded in response to movement of said rod into said bore; means dening a path of fluid tiow leading around the piston to and from said bore, said path comprising a pair of passageways on either side of said piston leading in parallel from said bore to said reservoir, one passageway of each pair serving to meter the ow of Huid from the bore and the other passageway being closed as the piston moves toward the pair in one direction of movement, and at least one of the passageways of the other pair of passageways on the other side of said piston then permitting ready access of the metered fluid to the bore .on said other side of said piston as the piston moves away from said other pair of passageways, said pair of passageways leading from the bore at opposite sides of the piston communicating with the reservoir at its opposite ends; a latch return line for uid leading from a position ahead of said piston during movement in its door closing direction and discharging into said bore on the opposite side of said piston when said piston closes the metering passageway toward which it is moving; a separate Pny-pass line leading around said piston during initial movement of said piston in its door opening direction and opening into the :bore by two openings, one of said openings being closed off by the piston when the piston is moved to a position in the bore corresponding to movement of the door to a substantially open position, and valve means operatively associated with said by-pass line and adapted to render said line ineffective when the piston is moving to its door closing direction; said reservoir being disposed alongside said bore and in series With the path of fluid flow between opposite sides of said piston through said pairs of passageways.

References Cited UNITED STATES PATENTS 2,701,383 2/1955 Billeter 16-59 2,301,613 3/1957 Plaee et a1. 92-36x FOREIGN PATENTS 277,182 4/ 1962 Netherlands 18S- 100 6403323 9/1964 Netherlands 188-100 BOBBY R. GAY, Primary Examiner P. A. ASCHENBRENNER, Assistant Examiner U.S. Cl. X.R.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3887961 *Jun 12, 1974Jun 10, 1975Jaakko SaajosDamping assemblies for doors or the like
US3944031 *Jun 18, 1974Mar 16, 1976Institut Francais Du PetroleShock absorber
US4067084 *Feb 28, 1977Jan 10, 1978Dorma-Baubeschlag G.M.B.H. & Co. K. G.Automatic door closer
US4075734 *Jul 21, 1976Feb 28, 1978Tokico Ltd.Door closer
US4180888 *Mar 14, 1978Jan 1, 1980Tokico Ltd.Door closer
US4291788 *Feb 11, 1980Sep 29, 1981Tokico Ltd.Cylinder head
US4349939 *Jun 9, 1980Sep 21, 1982Dorma-Baubeschlag Gmbh & Co. KgAutomatic door closer
US4659538 *Jan 6, 1984Apr 21, 1987Commissariat A L'energie AtomiqueApparatus for limiting the effect of axial hydraulic flow force exerted on fuel assemblies of water-cooled nuclear reactors
US4693454 *Aug 16, 1984Sep 15, 1987Matsushita Electric Industrial Co., Ltd.Air pressure shock absorber
US4697674 *Jun 17, 1985Oct 6, 1987Industrie Pirelli S.P.AOleoelastic energy accumulator
US4928799 *May 15, 1989May 29, 1990Lisega GmbhHydraulic dashpot
US5031509 *Aug 31, 1989Jul 16, 1991Titan Tool, Inc.Anti-leak seal for pump motor
US5090089 *Jun 10, 1988Feb 25, 1992Eco Schulte Gmbh & Co. KgAutomatic door closing device
US5259090 *Jul 31, 1991Nov 9, 1993Emhart IncFluid door closer with means to permit entrapped gases to move
US5410777 *Nov 1, 1991May 2, 1995Multimatic Inc.Automatic checking mechanism
US5410947 *Sep 17, 1993May 2, 1995Moog Inc.In a fluid-powered actuator
US5456283 *Aug 25, 1993Oct 10, 1995Itt CorporationInfinite hydraulic check
US5487480 *Jun 10, 1994Jan 30, 1996Oleo International Holdings LimitedHydro-pneumatic cushioning device
US5787790 *Dec 27, 1995Aug 4, 1998Automotive Produscts, PlcActuator with an overflow chamber and means for returning the fluid from the overflow chamber during a reverse stroke
US5800566 *Jun 9, 1993Sep 1, 1998Gramnaes; FinnArtificial joint with a hydraulic damping cylinder
US7516514 *Dec 21, 2005Apr 14, 2009Dr. Ing. H.C.F. Porsche AktiengessellschaftDoor stopper for a motor vehicle door and motor vehicle door for a motor vehicle with a door stopper of this type
US7677155 *Jan 13, 2006Mar 16, 2010Gm Global Technology Operations, Inc.Statically sealed high pressure fuel pump and method
US20120048665 *Sep 6, 2011Mar 1, 2012John MarkingCompression isolator for a suspension damper
US20130264157 *Mar 18, 2013Oct 10, 2013Medi GmbH & Co., KGAdjustment-free cushioning air cylinder
Classifications
U.S. Classification16/82, 16/51, 188/287, 92/86, 188/298
International ClassificationE05F3/04, E05F3/00
Cooperative ClassificationE05F3/04
European ClassificationE05F3/04