A positioning device

Abstract: A hydropneumatic positioning device comprises a tu­ bular container (10). A hollow piston rod (18) is guided through one end of the tubular container (10). A piston (22) is connected with the piston rod (18) within a cavity (12) of the tubular container. The piston (22) divides the cavity (12) into two working chambers (12a, 12b). The working chambers (12a, 12b) contain a liquid. Adjacent one of the work­ ing chambers (12b), namely the working chamber remote from the piston rod (18), a compensating chamber (26) is provided. This compen­ sating chamber (26) contains a pressurized gas and is separated from the adjacent working chamber by a floating separating wall (28). A flow passage (24a to 24e) extends through the piston (22) between the two working chambers (12a, 12b). A valve (30) is allocated to the flow pas­ sage (24a to 24e). The valve (30) can be opened by an actuating rod (32) extending through an axial bore (34) of the hollow piston rod (18). The actuat­ ing rod (32) extends beyond an outer end of the piston rod (18). An actuating signal transformer (11) is fastened to the outer end of the piston rod (18). The signal transformer (11) is constructed as a hydraulic press with a liquid chamber (44), an input piston (56), and an output piston (48). The output piston (48) acts onto the outer end (36) of the actuating rod (32) and the input piston (56) can be actuated manually.

Description: According to an illustrative example of the present invention a hydropneumatic positioning device comprises a tubular container. A hollow piston rod is guided through one end of the tubular container. A piston is connected with the piston rod within a cavity of the tubular container. The piston divides the cavity into two working chambers. The working chambers contain a liquid. Adjacent one of the working chambers, namely the working chamber remote from the piston rod, a compensating chamber is provided. This compensating chamber contains a pressurized gas and is separated from the adjacent working chamber by a floating separating wall. A flow passage extends through the piston between the two working chambers. A valve is allocated to the flow passage. The valve can be opened by an actuating rod extending through an axial bore of the hollow piston rod. The actuating rod extends beyond an outer end of the piston rod. An actuating signal transformer is fastened to the outer end of the piston rod. The signal transformer is constructed as a hydraulic press with a liquid chamber, an input piston, and an output piston. The output piston acts onto the outer end of the actuating rod and the input piston can be actuated manually. This invention is related to positioning devices such as blockable gas springs and hydropneumatic springs are widely used, for example for height adjustment of tables and chairs. For blocking and unblocking such positioning devices a valve is provided between two fluid-filled working chambers of the positioning device. The valve is frequently operated through a rod or pin extending beyond a piston rod or a housing of the positioning device. The requirements as to the actuation of this actuating rod are different depending on the various constructions of which the positioning device forms a part. Sometimes a remote actuation is desired, sometimes a direct actuation of the piston rod is possible, sometimes a long actuation path is acceptable and a low actuation force is required. In other situations a high actuation force is available and a short actuation path is required. From German patent 1 554 478 a gas spring is known with a cylinder and a piston rod extending inwards and outwards of the cylinder. A piston is connected with the piston rod within the cylinder. The piston separates the cavity within the cylinder into two working chambers which are both filled with a pressurized gas. A flow passage is provided for selectively connecting and separating the two working chambers from each other. This flow passage extends across the piston. A valve member is provided within an axial bore of the piston rod. For selectively opening and closing the flow passage an actuating piston is provided adjacent the outer end of the piston rod within the bore thereof. A liquid filling is provided between the valve member and the actuating piston. An actuating force exerted on the outer end of the input piston is transmitted through the liquid filling to the valve member. According to another embodiment disclosed in German patent 1 554 478 the bore of the piston rod is closed adjacent the outer end thereof. The bore of the piston rod is connected through a flexible tube to a pressure generator in which pressure may be generated by pressing an input piston into a pressure chamber connected with the flexible conduit. In the GB-A-1 164 155 a stepless adjustable support device is known in a plurality of embodiments. According to the embodiment of Fig. 4 of this British patent, two working chambers of a cylinder cavity are separated from each other by a piston unit. The piston unit is fastened inside the cylinder cavity to a piston rod which passes through a guiding and sealing unit adjacent one end of the cylinder and has an outer end outside of the cylinder cavity. A valve unit is provided inside the piston unit. This valve unit can be opened or closed by a valve member. The valve member is combined with a valve actuating piston which is guided within a bore inside the piston unit. This valve actuating piston is exposed to a pneumatic or hydraulic actuating medium inside the bore of the cylinder unit. The bore inside the piston unit is connected though a longitudinal bore of the piston rod to a source of compressed gas or liquid. By exposing the valve actuating piston to such compressed gas or liquid, the valve member can be opened. For admitting the compressed gas or liquid to the valve actuating piston via the longitudinal bore of the piston rod, a fluid tight line must be connected to the longitudinal bore at the outer end of the piston rod. From Fig. 5 of the British patent GB-A-1 164 155 a further embodiment is known in which a valve system is provided inside a piston unit of a cylinder piston device in which the piston unit is again fastened for common movement to a piston rod sealingly guided through one end of a cylinder. For actuating this valve system the piston rod is again provided with an axial bore extending from the piston unit to an outer end of the piston rod outside of the cylinder cavity. A mechanical actuating unit is provided at the outer end of the piston rod. This mechanical actuating unit comprises an actuating lever pivotally mounted on a basic member of the mechanical actuating unit. This actuating lever has a first arm acting onto an actuating pin extending through a longitudinal bore of the piston rod into engagement with the valve system. A helical compression spring acts through said first lever arm onto the actuating pin. A second lever arm of the actuating lever can be manually actuated against the action of the helical compression spring such that the actuating pin can be moved into an opening position. When the second lever arm is free of actuating force, the helical compression spring urges the valve system through the first lever arm and the actuating pin into a closed position in which the two working chambers on both sides of the piston unit are separated from each other. FR-A-2 620 917 shows a chair the height of which can be adjusted by a gas spring disposed in the internal space of a seat column. The gas spring has an actuating pin projecting beyond one end thereof. A hydraulic actuating unit is provided for acting onto the actuating pin adjacent a respective end of the gas spring cylinder. The hydraulic actuating unit comprises an actuating piston acting onto the actuating pin. This actuating piston is exposed to one side of a membrane sealingly disposed within the hydraulic actuating unit. The other side of this membrane is exposed to hydraulic pressure which is admitted to the other side of the membrane through a tube from a hydraulic pilot cylinder unit. This pilot cylinder unit is fastened at the lower side of a seat plate and comprises a master cylinder with a master plunger. The master plunger is movable with respect to the master cylinder by a pushing member accessible to the operator's hand. By pushing the pushing member in a predetermined direction, fluid can be expelled from the master cylinder towards the second side of the membrane, such as to urge the actuating piston against the actuating pin and to make thereby the gas spring adjustable. The present invention concerns a positioning device comprising a housing unit having an axis, a piston rod axially extending inwards and outwards of said housing unit, a piston unit connected to said piston rod within said housing unit, said piston rod and said piston unit forming a piston-piston rod unit, said piston unit separating two working chambers from each other within said housing unit, said working chambers containing a fluid, said working chambers being interconnected by a fluid passage, said fluid passage being selectively closable and openable by valve means allocated to said fluid passage, said valve means being actuable by actuating rod means guided within and projecting beyond one of said housing unit and said piston-piston rod unit, an actuating signal transforming unit being rigidly connected to the respective one of said housing unit or said piston-piston rod unit by interengaging fastening means of said actuating signal transforming unit and the respective one of said housing unit or said piston-piston rod unit, said actuating signal transforming unit having an adapter housing fastened to the respective one of said housing unit or said piston-piston rod unit outside said housing unit, said adapter housing accommodating a liquid filled transforming chamber therein, an output piston of said liquid filled transforming chamber being substantially aligned with an actuating pin of said actuating rod means and having a first end portion exposed to a liquid pressure within said liquid filled transforming chamber and a second end portion adapted for abutting engagement onto said actuating pin. It is an object of the present invention to provide a positioning device of the before mentioned type with a signal transforming unit which can be completed and filled with the liquid before being mechanically assembled with a respective part of the positioning device and which can be mechanically actuated without using liquid connecting tubes outside the positioning device. This object is obtained in that said adapter housing is further provided with an input piston, said input piston having a first end portion exposed to said liquid pressure within said liquid filled transforming chamber and a second end portion accessible to an actuating force from outside said liquid filled transforming chamber. The present invention allows easy adaptation in accordance with the respective requirements of different cases of application. It is further easily possible to selectively either actuate the valve means with smaller actuating force and longer actuating path at the input piston or with larger actuating force and shorter actuating path at said input piston. The adapter housing may be fastened to the respective one of said housing unit or said piston-piston rod unit by screw means. E.g., the adapter housing may be provided with internal thread means engaging external thread means of the respective one of said housing unit or said piston-piston rod unit. The input piston and the output piston may be exposed with respective effective cross-sectional areas to the liquid pressure within the liquid filled transforming chamber. If a high actuation force is acceptable and a short actuation path is desired, the output piston may have a smaller effective cross-sectional area than said input piston. If, on the other hand, a low actuation force is required and a long actuation path is acceptable, the output piston may have a larger effective cross-sectional area than said input piston. The positioning device of the present invention can be easily incorporated in a respective construction, if the actuating signal transforming unit is provided with mechanical connection means for being connected to a structural member. According to a preferred embodiment of the present invention, a respective one of the housing unit or the piston-piston rod unit has a terminal portion substantially coaxial with the axis of said housing unit. The actuating pin can extend through a bore of this terminal portion and beyond an outer end of this terminal portion. The terminal portion may be provided with external thread means. The signal transforming unit may have a substantially tubular adapter housing. The substantially tubular adapter housing is substantially coaxially fastened to the terminal portion by internal thread means engaging said external thread means of said terminal portion. In the adapter housing a substantially central cavity accommodates an end portion of the actuating pin. In the adapter housing there is further provided a liquid filled transforming chamber axially adjacent the cavity. This transforming chamber is closed by a cover member adjacent an end of the adapter housing remote from the respective one of said housing unit and said piston-piston rod unit. An axial bore extends between the cavity and the transforming chamber. An output piston is sealingly guided through said axial bore between said cavity and said transforming chamber. The output piston is substantially aligned with the actuating pin and has its first end within said cavity and its second end within said transforming chamber. A further bore extends through said cover member between said transforming chamber and atmosphere. The input piston is sealingly guided within said further bore and has its first end within said transforming chamber and its second end outside said cover member. The cover member may be provided with fastening means for being fastened to a respective structural member. The cover member may be provided with mechanical connection means for being fastened to a respective structural member. The mechanical connection means may comprise thread means concentric with the above-mentioned axis. The input piston may be substantially aligned with the actuating pin. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in grater detail hereinafter with reference to embodiments shown in the accompanying drawings in which FIGURE 1 shows a hydraulic press type actuating signal transforming unit; FIGURE 2 shows a hydropneumatic positioning device with an actuating signal transforming unit according to Figure 1 fastened to the outer end of a piston rod, and FIGURE 3 shows a gas spring with an actuating signal transforming unit of Figure 1 fastened to the housing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In Figure 2 the positioning device comprises a cylinder 10 which defines a cavity 12 therein. The cylinder 10 has a lower end wall 14 with a connecting bolt 16 for being connected to a first structural member of a construction not shown. A piston rod 18 sealingly extends through an upper end wall 20 of the cylinder member 10. A piston unit 22 is connected with the piston rod 18 within the cavity 12. A flow passage 24a, 24b, 24c, 24d, 24e extends across the piston unit 22 and connects two working chambers 12a and 12b, which are separated from each other by the piston unit 22. The working chambers 12a and 12b are filled with a liquid. A compensation chamber 26 is provided adjacent the working chamber 12b and separated therefrom by a floating piston 28. The compensation chamber 26 is filled with a pressurized gas. The flow passage 24a to 24e is closed by a valve member 30. This valve member 30 is openable by an actuating pin 32 which extends through an axial bore 34 of the piston rod 18. The upper end portion 36 of the actuating pin 32 extends beyond the upper end of the piston rod 18. A tubular adapter housing 38 is screwed to the upper end portion of the piston rod 18 by thread means 40. The end portion 36 of the actuating pin 32 extends into a cavity 42 of the adapter housing 38. In the adapter housing 38 there is provided a liquid filled chamber 44. A bore 46 extends from the cavity 42 to the liquid filled chamber 44. An output piston 48 is sealingly guided within said bore 46 by a sealing ring 50. A head portion 51 of the output piston 48 is opposite to the end portion 36 of the actuating pin 32. A cover member 52 is screwed on the upper end of the tubular adapter housing 38. This cover member is provided with a hollow axial extension 54 in which a piston rod 56a of an input piston 56 is guided. The input piston 56 is sealingly guided by a sealing ring 58 which is supported by a spacer sleeve 60. The tubular extension 54 is provided with an external thread 62 which can be fastened to a further structural member of the respective construction. The actuating pin 32 is sealed against the bore 34 by a sealing ring 64. The valve member 30 is biased into closing position by the liquid pressure within the working chamber 12b. For opening the valve member 30 an actuating force P is applied to the input piston rod 56a. As a result thereof, the output piston 58 is urged downwards through the liquid 44 and acts upon the upper portion 36 of the actuating pin 32. The transmission ratio of the hydraulic press type actuating signal transforming unit 11 depends on the effective cross-sectional areas of the input piston 56 and the output piston 48 exposed to the liquid filling within the liquid chamber 44. In the illustrated embodiment the effective cross-sectional area of the input piston 56 is larger than the effective cross-sectional area of the output piston 48. Only a small actuating path is necessary and correspondingly high actuating force for moving the valve member 30 towards its opening position. The hydraulic press type actuating signal transforming unit 11 is shown in an increased scale in Figure 1. In the embodiment of Figure 3 the hydraulic press type actuating signal transforming unit 11 is combined with a gas spring. This gas spring comprises a cylinder 210 with a piston rod 218 and a piston unit 222 fastened to the piston rod 218. The piston 220 divides the cavity 212 into two working chambers 212a and 212b. The working chambers 212a and 212b are filled with pressurized gas and are interconnected by a flow passage 224a, 224b, 224c. The flow passage 224a to 224c is closed by a valve member 230. The valve member 230 is provided with a valve shaft 230a which is sealingly guided by a sealing ring 264 against a bore 234 of a plug member 235 closing the upper end of the cylinder member 210. The valve shaft 230a is actuated by an actuating pin 232 which has an end portion 236 accommodated by the cavity 42. The adapter housing 38 is fixed by the thread means 40 on an end portion 237a of a plug member 237. The plug member 237 is fastened to the upper end of an outer sleeve 239 surrounding the cylinder member 210. The actuating pin 232 extends through a bore 241 of the plug member 237. The valve member 230 is biased towards its closing position by the pressure of the pressurized gas within the working chamber 212 b. The valve member 230 is moved towards its opening position by downward movement of the actuating rod 232. This downward movement is obtained by exerting an actuating force P onto the input piston 56a which results in a downward movement of the output piston 48 against the upper end portion 236 of the actuating pin 232. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention will be embodied otherwise without departing from such principles. The reference numerals in the claims are only used for facilitating the understanding and are by no means restrictive.

Claims: A positioning device comprising a housing unit (10; 210) having an axis, a piston rod (18; 218) axially extending inwards and outwards of said housing unit (10; 210), a piston unit (22; 222) connected to said piston rod (18; 218) within said housing unit (10; 210), said piston rod (18; 218) and said piston unit (22; 222) forming a piston-piston rod unit (18, 22; 218, 222), said piston unit (22; 222) separating two working chambers (12a, 12b; 212a, 212b) from each other within said housing unit (10; 210), said working chambers (12a, 12b; 212a, 212b) containing a fluid, said working chambers (12a, 12b; 212a, 212b) being interconnected by a fluid passage (24a to 24e; 224a to 224c), said fluid passage (24a to 24e; 224a to 224c) being selectively closable and openable by valve means (30; 230) allocated to said fluid passage (24a to 24e; 224a to 224c), said valve means (30; 230) being actuable by an actuating rod means guided within and projecting beyond one of said housing unit and said piston-piston rod unit (18, 22), an actuating signal transforming unit (11) being rigidly connected to the respective one of said housing unit (210) or said piston-piston rod unit (18,22) by interengaging fastening means of said actuating signal transforming unit (11) and the respective one of said housing unit (210) or said piston-piston rod unit (18,22), said actuating signal transforming unit (11) having an adapter housing (38) fastened to the respective one of said housing unit (210) or said piston-piston rod unit (18,22) outside said housing unit (10;210), said adapter housing (38) accommodating a liquid filled transforming chamber (44) therein, an output piston (48) of said liquid filled transforming chamber (44) being substantially aligned with an actuating pin (32;232) of said actuating rod means and having a first end portion exposed to a liquid pressure within said liquid filled transforming chamber (44) and a second end portion (51) adapted for abutting engagement onto said actuating pin (32; 232), characterized in that said adapter housing (38) is further provided with an input piston (56,56a), said input piston (56,56a) having a first end portion (56) exposed to said liquid pressure within said liquid filled transforming chamber (44) and a second end portion (56a) accessible to an actuating force (p) from outside said liquid filled transforming chamber (44). The positioning device as set forth in claim 1, said adapter housing (38) being fastened to the respective one of said housing unit (210) or said piston-piston rod unit (18,22) by screw means (40). The positioning device as set forth in claim 2, said adapter housing (38) having internal thread means engaging external thread means of the respective one of said housing unit (210) or said piston-piston rod unit (18,22). The positioning device as set forth in one of claims 1 to 3, said input piston (56) and said output piston (48) having respective effective cross-sectional areas exposed to said liquid pressure within said liquid filled transforming chamber (44). The positioning device as set forth in claim 4, said output piston (48) having a smaller effective cross-sectional area than said input piston (56). The positioning device as set forth in claim 4, said output piston having a larger effective cross-sectional area than said input piston. The positioning device as set forth in one of claims 1 to 6, said actuating signal transforming unit (11) being provided with mechanical connection means (62) for being connected to a structural member. The positioning device of one of claims 1 to 7, said actuating pin (32;232) extending outwards of the respective one of said housing unit (210) of said piston-piston rod unit (18,22), said actuating signal transforming unit (11) comprising a cavity (42) accommodating an outer end portion (36;236) of said actuating pin (32;232). The positioning device of one of claims 1 to 8, a respective one of said housing unit (210) or said piston-piston rod unit (18,22) having a terminal portion (237a) substantially coaxial with the axis of said housing unit (10;210), said actuating pin (32;232) extending through a bore of said terminal portion (237a) and beyond an outer end of said terminal portion (237a), said terminal portion (237a) being provided with external thread means, said signal transforming unit (11) having a substantially tubular adapter housing (38), said substantially tubular adapter housing (38) being substantially coaxially fastened to the terminal portion (237a) by internal thread means engaging said external thread means of said terminal portion (237a), said adapter housing (38) having a substantially central cavity (42) accommodating an end portion (36;236) of said actuating pin (32;232), said adapter housing (38) further having said liquid filled transforming chamber (44) axially adjacent said cavity (42), said transforming chamber (44) being closed by a cover member (52) adjacent an end of said adapter housing (38) remote from the respective one of said housing unit (210) and said piston-piston rod unit (18,22), an axial bore (46) extending between said cavity (42) and said transforming chamber (44), said output piston (48) being sealingly guided through said axial bore (46) between said cavity (42) and said transforming chamber (44), said output piston (48) having said first end thereof within said cavity (42) and said second end thereof within said transforming chamber (44), a further bore extending through said cover member (52) between said transforming chamber (44) and atmosphere, said input piston (56) being sealingly guided within said further bore and having said first end thereof within said transforming chamber (44) and said second end (56a) thereof outside said cover member (52). The positioning device as set forth in claim 9, said cover member (52) being provided with mechanical connection means (62) for being fastened to a respective structural member. The positioning device as set forth in one of claims 7 to 10, said mechanical connection means (62) comprising thread means concentric with said axis. The positioning device as set forth in one of claims 1 to 11, said input piston (56,56a) being substantially aligned with said actuating pin (32;232).

Inventors: ENDERS STEPHEN DIPL-ING, POERTZGEN GREGOR DIPL-ING, ENDERS, STEPHEN, DIPL.-ING., POERTZGEN, GREGOR, DIPL.-ING.
Applicants: STABILUS GMBH
Application year: 1990
Main classification: A47C3
IPC codes: A47B9, F15B7, A47C3