A positioning device

Abstract: A hydropneumatic positioning device comprises a tubular 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 working chambers (12B), namely the working chamber remote from the piston rod (18), a compensating chamber (26) is provided. This compensating 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 passage (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 actuating 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) or as an electromagnetic coil (168A) with an armature (168B), 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: This invention refers to a method for supplementing a positioning device for hydraulic or electric actuation in response to respective requirements of various cases of application, said positioning device comprising as basic components 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 through an axial actuating rod guiding bore allocated to a respective one of said housing unit and said piston-piston rod unit. Positioning devices such as blockable gas springs and hydropneumatic springs are widely used, e.g. 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 red 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. From GB-A-1 164 155 a positioning device comprising a cylinder, a piston rod and a piston unit is known in which a fluid passage through the piston unit is controlled through actuating rod means which are guided within a bore of the piston rod and act onto a valve member. An actuating unit is fastened to the outer end of the piston rod for acting on the actuating rod means. The actuating unit comprises a sleeve member fastened to the outer end of the piston rod. This sleeve member is provided with a fastening eye on its end portion remote from the piston rod for fastening the piston rod to a structure. An actuating lever is rockably mounted on the sleeve member. A first lever arm is exposed to an external actuating force, and a second lever arm is in engagement with an outer end portion of the actuating rod means. A further embodiment of GB-A-1 164 155 shows an electromagnetic actuation of the valve member. In this case, an electromagnetic coil is located inside the piston unit and acts onto an armature structurally combined with the valve member. According to a still further embodiment of GB-A-1 164 155, a hydraulic actuation of the valve member is obtained in that a servo-piston is accommodated within the piston unit. This servo-piston is structurally combined with the valve member. The servo-piston is slidably mounted within a cylindrical bore of the cylinder unit. A hydraulic fluid is admitted to the cylindrical bore by an axial bore of the piston rod for actuating the servo-piston. From FR-A-2 620 915 a hydraulically actuated positioning device is known in which an outer casing of the positioning device accommodates adjacent an end portion remote from the piston rod a servo-piston arrangement which is non-releasably housed within the casing and is connected by a flexible tube with a master-piston for transmitting an actuating fluid from the master-piston to the positioning unit. It is a primary object of the present invention to provide a positioning device which is easily accessible to different kinds of actuation. More particularly it is an object of the present invention to provide a positioning device in which an actuating force for blocking and unblocking can be selectively applied either directly at the location of the positioning device or by remote control. It is a further object of the present invention to provide a positioning device which can be easily modified in accordance with the respective requirements of different cases of application. In consideration of the above object the method of the present invention is characterised in that device-side thread means are allocated to the respective one of said housing unit and said piston-piston rod unit in a coaxial relationship with respect to said axial actuating rod guiding bore, and in that a hydraulic or electric transforming unit provided with an adapter housing and with corresponding counterthread means is fastened to the respective one of said housing unit and said piston-piston rod unit outside said positioning device, said transforming unit having input means for applying an input pressure signal or an input current signal to a volume of hydraulic liquid or an electric coil, respectively, said transforming unit further comprising an axially movable output member subject to hydraulic pressure or electromagnetic force, respectively, and intended for being aligned and brought into an engagement position with respect to said actuating rod means, when said transforming unit is fastened with respect to the respective one of said housing unit and said piston-piston rod unit by screwing said counterthread means on said device-side thread means. Such, the positioning device may be used without an actuating signal transforming unit, in which case an actuating force is directly introduced into the actuating rod means. Alternatively, a selected actuating signal transforming unit may be fastened to the housing unit or the piston-piston rod unit. According to the selection of the actuating signal transforming unit one can enable direct or remote control, actuation with small actuation force and long actuation path or actuation with high actuation force and short actuation path. E.g., the adapter housing may have internal thread means engaging external thread means of the respective one of said housing unit and said piston-piston rod unit. The actuating signal transforming unit may be constructed as a type of hydraulic press comprising a liquid filled transforming chamber with an input piston and an output piston. Both said input piston and said output piston extend with respective first ends into the liquid-filled transforming chamber. The output piston has a second end acting on the actuating rod means. 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 the 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. According to a further embodiment the actuating signal transforming unit comprises a solenoid with an electromagnetic coil and an armature which acts on the actuating rod means. The electromagnetic coil has electric connection means for being connected to an electric power source. The positioning device 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 respective structural member. It is of considerable advantage, if the actuating rod means extend outwards of the respective one of said housing unit and said piston-piston rod unit for the event that a direct actuation of the actuating rod means is desired. In such case it is nevertheless possible to easily connect the actuating signal transforming unit with the housing unit or the piston-piston rod unit, if the actuating signal transforming unit comprises a cavity accommodating an outer end portion of an actuating pin or an outer end of the actuating rod means. A most simple and compact embodiment of a positioning device according to this invention is obtained, if a respective one of the housing unit and the piston-piston rod unit has a terminal portion substantially coaxial with the axis of said housing unit. The actuating rod means 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 rod means. 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 rod means and has one end within said cavity and another end within said transforming chamber. A further bore extends through said cover member between said transforming chamber and atmosphere. An input piston is sealingly guided within said further bore and has one end within said transforming chamber and another end outside said cover member. The cover member may be provided with fastening means for being fastened to a respective structural member. In the case of an electromagnetic actuation a most simple and compact construction may be obtained as follows: A respective one of said housing unit and said piston-piston rod unit has a terminal portion substantially coaxial with the axis of the housing unit. The actuating rod means extend through a bore of this terminal portion and beyond an outer end thereof. This terminal portion is provided with external thread means. The signal transforming unit has a substantially tubular adapter housing. This adapter housing is substantially coaxially fastened to the terminal portion by internal thread means engaging the external thread means of the terminal portion. The adapter housing has a substantially central cavity accommodating an end portion of the actuating rod means. The adapter housing further accommodates a solenoid within a solenoid chamber axially adjacent the cavity. The solenoid chamber is provided with a cover member. This cover member may be provided with electric connectors for connecting the solenoid with an electric power source. The cover member may be provided with fastening means for being fastened to a respective structural member of the construction of which the positioning device forms a part. The invention will be explained in greater 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 solenoid type actuating signal transforming unit; Figure 3 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 4 shows a gas spring with an actuating signal transforming unit of Figure 1 fastened to the housing. In Figure 3 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 rod 32 which extends through an axial actuating rod guiding bore 34 of the piston rod 18. The upper end portion 36 of the actuating rod 32 extends beyond the upper end portion 37a of the piston rod 18. A tubular adapter housing 38 of a hydraulic transforming unit 11 is screwed to the upper end portion of the piston rod 18 by thread means 40. These thread means 40 comprise external device-side thread means 40a and internal counterthread means 40b of said tubular adapter housing 38. The end portion 36 of the actuating rod 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 rod 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 an input 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 rod 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 48 is urged downwards through the liquid 44 and acts upon the upper portion 36 of the actuating rod 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 of the input piston rod 56a is necessary and correspondingly a high value of actuating force P 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. The hydraulic press type actuating signal transforming unit 11 may be replaced by a solenoid type actuating signal transforming unit as shown in Figure 2. In Figure 2 one recognizes the upper end portion of the piston rod 18, the thread means 40a of Figure 3 and the upper end portion 36 of the actuating rod 32. An adapter housing 38' is fastened to the piston rod 18 by internal thread means 40'b cooperating with the external thread means 40a of the piston rod 18. The end portion 36 of the actuating rod again is accommodated by a cavity 42'. A solenoid chamber 44' of the adapter housing 38' accommodates a solenoid 68' with an electromagnetic coil 68'a and an armature 68'b. The solenoid chamber 44' is closed by a cover member 52' which is fixed to the solenoid housing 38' by thread means 52'a. Electric conductors 70' for the energization of the electromagnetic coil 68'a extend through the cover member 52'. The cover member 52' is provided with a fastening extension 54' with external thread means 62' for connecting the positioning device with a structural member of the respective construction. The valve member 30 of Figure 3 is opened by energization of the solenoid 68' which urges the armature 68'b towards the end portion 36 of the actuating rod 32. In the embodiment of Figure 4 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 222 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 rod 232 which has an end portion 236 accommodated by the cavity 42. The adapter housing 38 is fixed by the internal counter-thread means 40b on thread means 240a of a plug member extension 237a of a plug member 237. The plug member 237 is fastened to the upper end of an outer sleeve 239 surrounding the clyinder member 210. The actuating rod 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 212b. 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 rod 232.

Claims: Method for supplementing a positioning device for hydraulic or electric actuation in response to respective requirements of various cases of application, said positioning device comprising as basic components 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 actuating rod means (32;232) guided through an axial actuating rod guiding bore (34;241) allocated to a respective one of said housing unit (210) and said piston-piston rod unit (18,22), characterized in that device-side thread means (40a) are allocated to the respective one of said housing unit (210) and said piston-piston rod unit (18,22) in a coaxial relationship with respect to said axial actuating rod guiding bore (241;34), and in that a hydraulic (11) or electric (11') transforming unit (11;11') provided with an adapter housing (38;38') and with corresponding counter-thread means (40b;40'b) is fastened to the respective one of said housing unit (210) and said piston-piston rod unit (18,22) outside said positioning device, said transforming unit (11;11') having input means (56a;70') for applying an input pressure signal or an input current signal to a volume of hydraulic liquid or an electric coil, respectively, said transforming unit (11;11') further comprising an axially movable output member (48;68'b) subject to hydraulic pressure or electromagnetic force, respectively, and intended for being aligned and brought into an engagement position with respect to said actuating rod means (232;32), when said transforming unit (11;11') is fastened with respect to the respective one of said housing unit (210) and said piston-piston rod unit (18,22) by screwing said counter thread means (40b;40'b) on said device-side thread means (240a;40a). A method as set forth in claim 1, said adapter housing (38;38') having internal thread means (40b;40'b) engaging external thread means (40a) of the respective one of said housing unit (210) and said piston-piston rod unit (18,22). A method as set forth in claim 1 or 2, said actuating signal transforming unit (11) comprising a liquid filled transforming chamber (44) having an input piston (56) and an output piston (48) acting as said output member, both said input piston (56) and said output piston (48) extending with respective first ends into said liquid filled transforming chamber (44), said output piston (48) having a second end (51) acting onto said actuating rod means (232;32). A method as set forth in claim 3, said input piston (56) and said output piston (48) having respective effective cross-sectional areas exposed to said liquid within said liquid filled transforming chamber (44). A method as set forth in claim 4, said output piston (48) having a smaller effective cross-sectional area than said input piston (56). A method as set forth in claim 4, said output piston having a larger effective cross-sectional area than said input piston. A method as set forth in claim 1 or 2, said actuating signal transforming unit (11') comprising a solenoid (68') with an electromagnetic coil (68'a) and an armature (68'b), said armature (68'b) acting as said output member, said electromagnetic coil (68'a) having electric connection means (70') acting as said input means for being connected to an electric power source. A method as set forth in one of claims 1 to 7, said actuating signal transforming unit (11;11') being provided with mechanical connection means (62;62') for being connected to a structural member. A method as set forth in one of claims 1 to 8, said actuating rod means (232;32) extending outwards of the respective one of said housing unit (210) and said piston-piston rod unit (18,22), said actuating signal transforming unit (11;11') comprising a cavity (42;42') accommodating an outer end portion (236;36) of said actuating rod means (232;32). A method as set forth in one of claims 1 to 6, 8 and 9, the respective one of said housing unit (210) and said piston-piston rod unit (18,22) having a terminal portion (237a;37a) substantially coaxial with the axis of said housing unit (210;10), said actuating rod means (232;32) extending through a bore (241;34) of said terminal portion (237a;37a) and beyond an outer end of said terminal portion (237a;37a), said terminal portion (237a;37a) being provided with external thread means (40a;40'a), 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;37a) by internal thread means (40b) engaging said external thread means (240a;40a) of said terminal portion (237a;37a), said adapter housing (38) having a substantially central cavity (42) accommodating an end portion (236;36) of said actuating rod means (232;32), said adapter housing (38) further having a 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), an output piston (48) being sealingly guided through said axial bore (46) between said cavity (42) and said transforming chamber (44), said output piston (48) being substantially aligned with said actuating rod means (232;32) and having one end within said cavity (42) and another end within said transforming chamber (44), a further bore extending through said cover member (52) between said transforming chamber (44) and atmosphere, an input piston (56) being sealingly guided within said further bore and having one end within said transforming chamber (44) and another end (56) outside said cover member (52). A method as set forth in claim 10, said cover member (52) being provided with fastening means (62) for being fastened to a respective structural member. A method as set forth in one of claims 1, 2 and 7 to 9, a respective one of said housing unit (210) and said piston-piston rod unit (18,22) having a terminal portion (237a;37a) substantially coaxial with the axis of said housing unit (210;10), said actuating rod means (232;32) extending through a bore of said terminal portion (237a;37a) and beyond an outer end of said terminal portion (237a;37a), said terminal portion (237a;37a) being provided with external thread means (240a;40a), said signal transforming unit (11') having a substantially tubular adapter housing (38'), said substantially tubular adapter housing (38') being substantially coaxially fastened to said terminal portion (237a;37a) by internal thread means (40'b) engaging said external thread means (240a;40a) of said terminal portion (237a;37a), said adapter housing (38') having a substantially central cavity (42') accommodating an end portion (236;36) of said actuating rod means (232;32), said adapter housing (38') further accommodating a solenoid (68') within a solenoid chamber (44') axially adjacent said cavity (42'), said solenoid chamber (44') being provided with a cover member (52'). A method as set forth in claim 12, said cover member (52') being provided with fastening means (62') for being fastened to a respective structural member.

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