DE102009035570A1 - Hydro-pneumatic piston-cylinder arrangement, particularly for use as suspension strut in vehicle-suspension system, comprises cylinder and piston rod of piston, where piston rod is guided outwards from open end of cylinder - Google Patents

Abstract

The hydro-pneumatic piston-cylinder arrangement comprises a cylinder and a piston rod (6) of a piston (7), where the piston rod is guided outwards from an open end (5) of a cylinder (2). A piston bottom (8) faces away from the piston rod, where a pneumatic spring accumulator (9) is provided as a bladder accumulator or a hydraulic accumulator (10) that is arranged in the cylinder.

Description

The The invention relates to a hydropneumatic piston-cylinder arrangement, in particular for use as a suspension strut in vehicle suspension systems, for example in the context of automotive and mobile crane solutions, with a cylinder and one in it with a hydraulic fluid filled cylindrical space guided axially movable, with one sealed from an open end of the cylinder externally guided piston rod one with this connected piston, the piston rod facing away from the piston rod in fluid-conducting operative connection with a pneumatic Spring memory can be brought.

hydropneumatic Axle suspensions with such hydropneumatic piston-cylinder arrangements are known and used for example in car crane systems. Commercial vehicles, such as mobile cranes or mobile cranes, require an axle suspension, so that a safe participation on the usual road traffic is possible and in construction site operation or other uses is a Blocking the axle suspension required, for example, a safe lifting or transporting of loads enable.

The DE 36 13 677 A1 describes a shock and vibration damping system consisting of a piston-cylinder assembly with a single-ended cylinder and a piston axially movable therein, which is connected to a protruding from the open end of the cylinder hollow piston rod whose protruding from the cylinder end by a Bottom is closed, wherein within the hollow piston rod, a separating piston guided axially movable and between the bottom and the separating piston is a compressible medium. Further, the cylinder includes an incompressible hydraulic medium which is pressable through a flow opening of the piston into the hollow piston rod between the piston and the separating piston and back, wherein the flow of the hydraulic medium through the flow openings of the piston for damping by means of a flow control valve is controllable. The compressible medium contained between the bottom of the piston rod and the separating piston is a gas which is adjustable under such a prestressing pressure, which elastically absorbs the static and dynamic pressure forces acting in the axial direction on the piston-cylinder arrangement from the gas medium as a pneumatic spring accumulator to limit the pressure of the gas medium in the hydraulic circuit, a pressure medium of the hydraulic medium limiting pressure relief valve is arranged.

To this end, known solutions can have a high internal adhesion and have sliding friction in the piston movement, so that Such piston-cylinder arrangements basically only for applications prove suitable with correspondingly high loads.

The DE 35 12 232 A1 further describes a hydropneumatic axle suspension for vehicles, preferably car and mobile cranes whose chassis are supported by hydraulic cylinders on their hinged to the frame axles, which in turn are connected by means of hydraulic lines and lockable valves with hydraulic gas or spring storage, outside the respective hydraulic cylinder arranged externally via fill and drain valves are connected to supply and discharge lines for the hydraulic fluid. Characterized in that in this known solution, the hydraulic cylinder of two axes are provided with activatable by a switch switching elements that produce in predetermined extended positions of the hydraulic cylinders, in which the chassis are at a horizontal level, the filling and discharge valves actuated signals, is an automatic level control allows for the chassis of said vehicle. By activating the switching elements they actuate the filling or discharge valves of the feed and discharge lines of the hydraulic cylinders, so that they adjust to positions corresponding to the horizontal level of the chassis or the parallel alignment of the chassis to the respective underground. If the leveling of the chassis is reached, the switching elements are brought into their inactive position, so that the vehicle is properly compressed according to its load or load distribution. Although the known solution is low-friction in operation; However, the space requirement due to the outsourced gas or spring storage together with associated control is correspondingly high and due to the long Ansteuerwege on said valves together with supply and discharge lines, the response of the suspension is subject to hysteresis and takes place with a time delay.

outgoing From this state of the art, the invention has the task a space-saving, low-friction in operation and functionally reliable and temporally responsive, hydropneumatic piston-cylinder arrangement to accomplish.

According to the invention this object by a hydropneumatic piston-cylinder assembly, the having the features of claim 1 in its entirety, solved.

The inventive arrangement of a bubble or diaphragm storage as a pneumatic spring accumulator within the cylinder, in particular in a receiving space within the Zy Linders, which extends in extension of the actual piston working space, a low-friction, compact constructive, hydropneumatic piston-cylinder arrangement is created, which allows the functionally reliable easy adjustment of their spring rate and the time immediately allows the onset of the spring action.

at a particularly preferred embodiment of the invention Solution is the memory as a separate unit with a first and second housing shell, at their edges have a peripheral contact with each other, formed. The preferred trained in the manner of a hemisphere first housing shell is in the mounted state radially full en en one Inner wall of the cylinder and is in particular with a clearance fit set there. In that regard, the spring accumulator is an integral part of the cylinder. The second housing shell of the memory is preferably as a half-shell with approximately the same receiving volume, as the first housing shell, formed, and preferably a cover for the cylinder. For the pertinent cover can be outside towards the environment an increased wall thickness, in particular, based on its horizontal wall areas, provided be. Furthermore, the end cover is preferably by a flanged edge at the free end of the cylinder wall set by this. It is also possible to to weld the two housing parts together.

The Such stiffened solution is then particularly suitable for Fixing a fastener, for example in the Art a ball joint formed, which is the articulation of the hydropneumatic Piston cylinder arrangement on a correspondingly formed chassis allows a vehicle in a hinged manner. In the area of the transition from first to second housing shell is a flexible and / or arranged elastically resilient partition, in particular in shape a membrane-like separating element, on its second housing shell facing side includes a working gas, wherein the Capacity is variable under a predetermined pressure and on the opposite side of the separator and thus adjacent to the inner wall of the first housing shell is formed a media space, preferably with hydraulic fluid or another working fluid via at least one lockable Fill opening is filled.

Preferably in the vicinity of the first housing shell arranged in the cylinder the membrane reservoir can be hydraulic fluid for damping in the space provided Add cylinder space or remove from it, so that depending on the working and damping situation the membrane of the membrane memory biased different degrees becomes. The hardness of the spring preload is determined by the in Diaphragm storage stockpiled working gas, especially in the form of Nitrogen gas, adjusted, depending on the selected System and printing parameters also completely block the Suspension is thereby achievable.

The second, the cylinder cover forming housing shell of the diaphragm accumulator has on its inside a central one preferably as a depression truncated cone shaped centering device for a superior from the membrane surface Center and stop centering on with corresponding profile cross-section like the mentioned centering device. For this purpose, the Membrane seen in its center in cross section a kind thickened Valve plate on which closing a fluid-carrying Connection between the effective cylinder chamber and the oil chamber the memory and in the other direction of movement a support at the correspondingly formed profile shape of said centering device allowed, so it in the pertinent stop position anyway not to overstretch the elastically yielding membrane material comes. If the centering device is perforated, can be in the range of the second housing shell increase the gas supply of working gas and thus the spring rate, without the membrane having to intervene in this room. Further shows the second housing shell in the area of its floor or end wall a centrally arranged closable opening for the supply and / or removal of working gas in the store on.

Around a permanent, secure attachment of the membrane inside the Membrane memory to allow the membrane is with a preferably in their wall thickness doubling circumferential bead received in a circumferential groove of a mounting ring, the C-ring formed on the inside of the membrane in this area supported as well as on wall parts of the membrane memory and the rest forms a transition to the centering device. by virtue of the intended large bending radius of the mounting ring It is ensured that the membrane during any flexing movements in their transition area to the storage enclosure large bending radii passes through, what so far gentle movement for the membrane allows.

To dampen the piston movement and as an additional drive means for the fluid guide, the piston has in its movable piston bottom flow resistances in the form of counter-acting check valves, which are reciprocally integrated in opposite directions reciprocally integrated in the piston head. The storage cylinder assembly builds up very small and all the important components of the hydropneumatic Kolbenzylindera Arrangement, such as suspension, damping and control valves, are integrated in a structural unit within the cylinder housing. It is surprising for a person skilled in the art that he can achieve effective suspension for the hydraulic damper unit of the active cylinder with a gas volume of about 0.1 to about 0.2 l for the membrane or bladder accumulator.

below the invention is closer with reference to an embodiment shown in the drawing explained. It show in principle and not to scale Presentation of the

1 a longitudinal section through a hydropneumatic piston-cylinder arrangement according to the invention;

2 a view of the hydropneumatic piston cylinder assembly in 1 in the direction of in 1 illustrated arrow X.

In 1 is a longitudinal section of a hydropneumatic piston-cylinder arrangement 1 shown for use as a vehicle, shock and vibration damper. As well as 2 in a view drawn at 90 ° around the vertical axis to the 1 according to the viewing direction along the arrow marked with X, the piston-cylinder arrangement consists of a cylinder open on one side 2 whose wall 28 over its length from the cylinder bottom to the storage enclosure has an approximately constant length. Inside the cylinder 2 is in one with hydraulic fluid 3 filled cylinder space 4 axially movable a piston 7 guided, the piston 7 seen in the direction of the figures his lowest, in the cylinder 2 retracted position. The piston 7 is also with a piston rod 6 from the open end 5 led out of the cylinder and is equipped with two circumferential seals 30 . 31 in which the piston rod 6 leading upper cylinder bottom 32 sealed. In addition to the aforementioned circumferential seals 30 . 31 the arrangement may also have corresponding guide bands, the axial movement of the piston rod 6 in the cylinder bottom 32 facilitate and establish an axial longitudinal stability for the movement.

In the cylinder bottom 32 is a through hole 33 brought in with a capping screw 34 is closed to the outside and in addition to a Erstbefüllung the cylinder chamber 4 also a refilling and replacement of the hydraulic medium 3 in the cylinder room 4 allows. Furthermore, the screw 34 for venting the cylinder chamber 4 serve if necessary. At its seen in the direction of the figures upper free end, the piston rod 6 for its attachment to a chassis part of a motor vehicle or utility vehicle, not shown, a ball head 35 on the piston rod 6 attached, in particular screwed on.

The cylinder space 4 is fluid leading to a pneumatic spring accumulator 9 connected in the illustrated piston position after the 1 directly at the bottom of the piston crown 8th inside the cylinder 2 followed. The spring store 9 is in the preferred embodiment as a membrane memory 10 formed and consists of a first housing shell 11 , which is hemispherical in shape and preferably with a clearance fit on the inner wall 12 of the cylinder 2 is guided, wherein the first housing shell 11 axially on the inner wall 12 of the cylinder 2 supported. The first upper housing shell 11 forms an axial stop on its upper side 36 from, in the position shown in the piston crown 8th with its bottom on the top of the diaphragm storage 10 can put on. As between the case back 8th and the top of the first housing shell 11 Hydraulic fluid is clamped, the pertinent stop movement, however, takes place in a correspondingly damped manner. A through hole 37 is central through the first housing shell 11 guided and thus allows the flow of hydraulic fluid 3 that in the store 10 stored, between the separation membrane 18 and the inner peripheral side of the first housing shell 11 ,

A second housing shell 13 is with the interposition of a trained as an O-ring sealing element 29 in the cylinder 2 used and defined with their also half-shell-shaped shape together with the first housing shell 11 the effective volume of the membrane reservoir 10 , The two housing shells 11 and 12 are welded together to prevent escape of the working gas. A peripheral edge 38 the second housing shell 13 has a paragraph 39 on, the first housing shell 11 oriented and projects beyond the free end face of the first housing shell in this area from the inside 11 , The second housing shell 13 of the membrane reservoir 10 is further from its peripheral edge 38 Seen in the direction of the figures downwards equipped with increasing wall thickness, extending up to a multiple of the original wall thickness in its horizontal, a lid 14 for the cylinder 2 expanding field. This lid 14 has centrally one or more pieces with the housing shell 13 formed screw-on 40 on, over the another ball head 41 on the cylinder 2 attached, in particular screwed on. The ball head 41 serves as well as the ball head 35 as a fastener 15 establishing the hydropneumatic piston-cylinder arrangement 1 on the chassis of a motor vehicle or utility vehicle, not shown.

Central is in the neck 40 a hole 42 with internal thread, which serves as a filling opening 22 of the storage room 16 of the membrane reservoir 10 for a working gas, in particular in the form of nitrogen gas, is used. Also in this respect can on the filling 22 a first filling, refilling or replacement of the working gas done. To trap the gas in the storage room 16 is the hole 42 certainly with a security screw 43 as shown, closed. The second housing shell 13 is also on its outer side in the transition region of its axially extending wall to the mounting boss 40 with a peripheral inclined surface 44 provided, the attachment of the free end edge of the cylinder wall 28 after the forming or advancing movement on the second housing shell 13 serves. A nose-like projection from the peripheral wall of the second housing shell 13 out in radially outward direction serves to form an axially effective undercut in the sense of an abutment for fixing the second housing shell 13 in the wall 28 of the cylinder 2 ,

The said membrane 18 , which is preferably formed from an elastomeric material, with its multiple bead having its remaining wall thickness circumferential bead 23 in the axial direction of the membrane memory 10 considered approximately centrally located in the storage enclosure. The circumferential bead 23 the rest in its rest position hemispherical-shaped membrane 18 comes in a circumferential groove 24 on the inside 25 the first housing shell 11 to lie. She is with a the peripheral bead 23 inside C-shaped ring enclosing 46 as a fastening ring in the circumferential groove 24 pressed. A dashed line, trough-shaped stop 19 is optional on the ring 46 set and serves with its truncated cone-like depression 47 as centering and stop device 20 for one in the storage room 16 from the wall of the membrane 18 protruding frustoconical thickening 21 , which has the function of a poppet valve for closing the hole 37 in the first housing shell 11 , provided the separation membrane 18 arrived in its uppermost deflection position. In this closed position then flows no hydraulic medium from the inside of the memory to the outside in between the bottom of the piston crown 8th and the top of the housing shell 11 lying cylinder space 4 ,

During a movement of the piston 7 under load will be in the direction of the spring accumulator 9 hydraulic fluid 3 then in the opposite direction through the hole 37 in the first housing shell 11 pressed into the memory and then acted on the extent biased by the working gas outside 17 the membrane 18 , which is a kind of spring accumulator for the hydropneumatic piston-cylinder arrangement 1 forms and the vehicle or cabin suspension serves. The mentioned bias of the membrane 18 can be determined by the memory pressure in the memory space 16 to adjust; as well can be via a radial in the wall 28 of the cylinder 2 introduced filling nozzle 48 for hydraulic fluid, the level for the piston-cylinder arrangement 1 to adjust. The others in the cylinder room 4 stored amount of hydraulic fluid 3 serves for damping during the movement of the piston-cylinder arrangement.

For frictionless operation and effective damping for the hydropneumatic piston-cylinder assembly 1 to get the piston points 7 in the area of its piston crown 8th two passages each with a defined flow resistance 26 forming 9 check valve 27 on. The two check valves 27 are each in the opposite direction of the hydraulic fluid 3 can be flowed through as a function of the displacement position of the piston 7 inside the cylinder 2 , By choosing the gas pressure in the storage space 16 , the amount of hydraulic fluid 3 in the cylinder room 4 , the flow resistance 6 and the physical properties of the fluid used 3 can be in dependence on the given requirements, the characteristic of the hydropneumatic piston-cylinder assembly 1 vary and in particular adjust as needed.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3613677 A1 [0003]
• - DE 3512232 A1 [0005]

Claims (10)

Hydro-pneumatic piston-cylinder arrangement, in particular for use as a suspension strut in vehicle suspension systems, having a cylinder ( 2 ) and one in which with a hydraulic fluid ( 3 ) filled cylinder space ( 4 ) axially movably guided, with a sealed from an open end ( 5 ) of the cylinder ( 2 ) outwardly guided piston rod ( 6 ) of a connected with this piston ( 7 ), whose from the piston rod ( 6 ) facing away from the piston head ( 8th ) in fluid-carrying operative connection with a pneumatic spring accumulator ( 9 ), characterized in that the pneumatic spring accumulator ( 9 ) a bladder or diaphragm accumulator ( 10 ), which is in the cylinder ( 2 ) is arranged. Piston cylinder arrangement according to claim 1, characterized in that a first housing shell ( 11 ) of the memory ( 10 ) on an inner wall ( 12 ) of the cylinder ( 2 ) is supported radially and / or axially. Piston cylinder arrangement according to claim 1 or 2, characterized in that a second housing shell ( 13 ) of the memory ( 10 ) a lid ( 14 ) for the cylinder ( 2 ). Piston cylinder arrangement according to one of claims 1 to 3, characterized in that the second housing shell ( 13 ) with at least one fastening element ( 15 ) for determining the cylinder arrangement ( 1 ) is attachable to a chassis of the vehicle and thereby all on the cylinder ( 2 ) transmits introduced forces to the chassis. Piston cylinder arrangement according to one of claims 2 to 4, characterized in that between the first housing shell ( 11 ) of the memory ( 10 ) and the piston crown ( 8th ) from outside the cylinder ( 2 ) fillable and emptiable storage space ( 16 ) for hydraulic fluid ( 3 ) arranged with an outside ( 17 ) an elastically and / or flexible resilient partition ( 18 ) of the memory ( 10 ) is in fluid-carrying operative connection. Piston cylinder arrangement according to one of claims 1 to 5, characterized in that an axial stop ( 19 ) for the partition ( 18 ) inside the memory ( 10 ) is provided, which has a centering device ( 20 ) for a centrally arranged plate-like thickening ( 21 ) of the partition ( 18 ) having. Piston cylinder arrangement according to one of claims 1 to 6, characterized in that the second housing shell ( 13 ) a closable opening ( 22 ) for the supply and / or removal of gas from inside the store ( 10 ) having. Piston cylinder arrangement according to one of claims 1 to 7, characterized in that an edge peripheral bead ( 23 ) of the partition ( 18 ) in a circumferential groove ( 24 ) on the inside ( 25 ) of the first housing shell ( 11 ). Piston cylinder arrangement according to one of claims 1 to 8, characterized in that in the piston head ( 8th ) Flow resistances ( 26 ) are installed, the total of a flow through the piston crown ( 8th ) with hydraulic fluid in opposite directions. Piston cylinder arrangement according to claim 9, characterized in that the flow resistances ( 26 ) from check valves ( 27 . 27 ' ) are formed, which have oppositely arranged opening directions.

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