EP0469253A1 - Flüssigkeitsstellantrieb mit Programmsteuerung - Google Patents

Flüssigkeitsstellantrieb mit Programmsteuerung Download PDF

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Publication number
EP0469253A1
EP0469253A1 EP91107470A EP91107470A EP0469253A1 EP 0469253 A1 EP0469253 A1 EP 0469253A1 EP 91107470 A EP91107470 A EP 91107470A EP 91107470 A EP91107470 A EP 91107470A EP 0469253 A1 EP0469253 A1 EP 0469253A1
Authority
EP
European Patent Office
Prior art keywords
braking
cylinder
piston
actuator according
screw shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP91107470A
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English (en)
French (fr)
Inventor
Luciano Residenza Dei Cerchi Migliori
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Univer SpA
Original Assignee
Univer SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Univer SpA filed Critical Univer SpA
Publication of EP0469253A1 publication Critical patent/EP0469253A1/de
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/26—Locking mechanisms
    • F15B15/262—Locking mechanisms using friction, e.g. brake pads
    • F15B15/264—Screw mechanisms attached to the piston
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B2015/1495—Characterised by the construction of the motor unit of the straight-cylinder type with screw mechanism attached to the piston

Definitions

  • the present invention relates to a fluid operated linear actuator comprising a cylinder and a reciprocable piston within said cylinder, and in particular is directed to a pneumatic or hydraulic actuator comprising a centrifugally actuated control means by which a extremely precise control of the stroke and positioning of the piston is possible.
  • linear actuators be they pneumatically or hydraulically operated ones
  • electromechanical or other types of actuators in particular on account of the high level of power or high working speeds, as well as the flexibility in use which is generally possible with such actuators.
  • linear actuators are used to little advantage and are unsuited owing to their insufficient working flexibility and limited positioning stability.
  • the high working speed of a pneumatic linear actuator is offset by a limited degree of precision or low resolution as regards positioning and the difficulty of programming operational cycles, while maintaining close control of the operational parameters, in particular the obtained position.
  • fluid pressure operated actuators of the type referred above have included various types of braking systems for positioning and preventing relative movement between the piston and the cylinder; some examples of said actuators are disclosed in many patents or published patent applications such as: DE-A- 2034826, GB-A- 683633, GB-A- 2154282, US-A- 2804053 and US-A-2801615.
  • a reciprocable piston member is slidably movable within a cylinder and is threadably, engaged with a screw shaft axially extending through said piston and said cylinder which screw shaft is connected to a pressure operated braking device to held the piston at any desired position along the length of its stroke;
  • a signal generator is provided within the cylinder and is connected to the screw shaft to provide a required degree of linear accurancy in positioning the piston within the cylinder. All braking or locking systems provided in said known actuator devices make use of rigid friction members which are to be kept sufficiently spaced apart to allow rotational movement of the screw shaft causing a retarded braking action and consequently an inaccurate positioning of the piston in the cylinder.
  • An object of the present invention is to provide a fluid operated linear actuator of the kind mentioned above, provided with a braking system which can be strictly controlled and which allows an extremely high degree of positioning accuracy, with a resolution of the order of hundreths, not possible with other known systems; this allows to more appropriately use the intrinsic features of fluid operated actuators.
  • a further object of the present invention is to provide a pneumatic or hydraulic cylinder provided with a centrifugally controlled braking device, which enables the overall dimensions to be considerably reduced while maintaining a compact structure and a high degree of stability of the actuator as regards positioning and control of the stroke, at comparatively low cost.
  • a further object of the present invention is to provide a linear actuator which can be programmed and controlled by an electronic processing unit and designed to allow operation at different speeds and stopping in short time, so as to considerably reduce the downtime and the duration of the working cycle, while maintaining a high degree of reliability.
  • a further object of the present invention is to provide a pneumatic or hydraulic linear actuator as referred to above, by means of which it is possible to obtain a very high working thrust, while at the same time requiring a relatively small braking and stopping torque which ensure positional stability even when the actuator is under loaded conditions in a slanted or vertical plane.
  • the actuator can be realized equally well with a normally active brake or with a passive brake, whilst maintaining all the characteristic features and fundamental principle of the invention; it is important, for the purposes of operational homogeneity, to actuate the brake using the same fluid operating the piston.
  • the linear actuator comprises a cylinder 10 provided with a braking device 11 provided in a rear extension 28 of the cylinder, which braking device is operationally connected by means of a worm-screw system to a piston 17 reciprocable within the cylinder 10.
  • the cylinder 10 comprises a barrel 12 closed by a front head-piece 13 and by an intermediate head-piece 14.
  • 15 and 16 in figure 1 denote, respectively, the inlet and/or outlet ports for a pressurized fluid, for example compressed air, through the two head-pieces of the cylinder.
  • a piston member 17 Inside the cylinder 10 slides, a piston member 17 having a hollow piston rod 18 axially extending within the cylinder, which rod 18 is guided and protrudes outwardly from the front head-piece 13 of the cylinder.
  • the piston 17 is prevented from rotating, providing means to prevent rotation during sliding movement of the piston 17, for example by giving the said piston 17 and the barrel 12 of the cylinder a polygonal cross-section, or by providing rods or guiding means for the piston inside or outside the cylinder.
  • the piston 17 and the piston rod 18 are axially hollow so as to allow the passage of a screw shaft 19 which is threadly engaged by a nut screw 20 fixed inside the piston 17.
  • the screw shaft 19 is connected or forms part of a control shaft 21 which extends through the intermediate head piece 14 of the cylinder, said control shaft 21 being connected to the braking device 11 described below.
  • the screw shaft 19 and the control shaft 21 for entraining the brake in rotation are rotatably supported, by means a ball bearing 22 in the intermediate head-piece 14 of the cylinder and, respectively, by means of a bush 23 at the front end of the screw shaft 19; the bush 23, in addition to support the screw shaft 19, also serves to guide the rod 18 of the cylinder during its axial movement.
  • the mounting of the screw shaft 19 into the nut screw 20 is of the direct type, that is with a long-pitch thread so as to allow high speed of travel for the piston and high actuating power.
  • the choice of the screw pitch and its diameter may vary in each case; in general they must be such as to allow a high reduction in the torque exerted on the braking device 11, whilst ensuring a high degree of stoppage stability for the piston 17 and a brake with considerably reduced dimensions.
  • the piston 17 may comprise permanent magnets 24 which, during the reciprocating movement, actuate switch devices or magnetic sensors 25, the position of which along the cylinder 10 can be suitably adjusted; these sensors supply signals indicating the position of the piston 17 to an electric or electronic control circuit, not shown.
  • the pneumatic actuator may comprise a signal generator such as an encoder 26 designed to emit control signals for controlling the position of the piston, within the cylinder, which signals are sent to an electronic control unit, not shown.
  • the encoder 26 is connected, by means of a coupling 27, to the control shaft 21 and screw shaft 19 which operate the braking device 11 so as to provide a direct relationship between the position of the piston 17 within the cylinder and the control signals emitted by the encoder 26.
  • the braking device 11 is a braking device which is controlled centrifugally and actuated by the same pressurized fluid which causes travel of the piston; the braking device 11 may be equally well of the active type or passive type, as described below.
  • the braking device 11 is provided inside an extension 28 of the barrel 12 of the cylinder, suitably fixed at the opposite end of the intermediate head-piece 14 or integral with said barrel 12; a third head-piece 29 defining the housing 30 for the encoder 26 closes the brake housing at the rear.
  • the braking device 11 in the form shown in Fig. 1, essentially comprises a first fixed braking disc 31, connected to the intermediate head-piece 14 of the cylinder, as well as a second rotating braking disc 32 connected so as to rotate with the control shaft 21 of the screw shaft 19.
  • This second braking disc 32 is made of elastically yieldable material , for example elastomeric material or the like, and is provided with a laterally protruding annular braking rim 33 facing towards the fixed braking disc 31.
  • the annular rim 33 may be formed or provided with a suitable layer of frictional material having a high coefficient of friction, designed to cooperate with the fixed disc 31 so as to brake the sliding movement of the piston 17 and to retain the same steady in any desired position of its stroke.
  • FIG. 3 This mode of operation is schematically shown in Fig. 3, where continuous lines and phantom lines denote, respectively, the two positions of engagement and disengagement between the annular rim 33 of the rotating disc 32 and the fixed braking disc 31, owing to the lateral flexion of the disc 32 caused by the moment generated by the centrifugal force as a result of the lateral disposition of the centre of gravity of the abovementioned braking rim, with respect to the plane of symmetry of the disc itself.
  • the centrifugal force on the rotating braking disc 32 which as a result of the displacement of the centre of gravity of the rim 33 gives rise to a torque tending to move this rim away from the fixed disc, therefore has the function of controlling the respective engaged or disengaged positions of the brake; the actual braking action or force, in the case of figure 1, however, is provided by a set of cup springs 34 or other equivalent elastic means, located between a thrust member 35 which acts against the braking disc 32 and counteracting elements 36 inside the sleeve 28.
  • the brake when the cylinder is at a standstill, the brake is normally activated in that the springs 34 act on the thrust member 35 so as to move it forwards and cause it to strongly press the rotating braking disc 32 against the fixed braking disc 31.
  • Deactivation of the brake occurs in a manner which is controlled and coordinated with the movement of the piston 17 of the actuator 10, using the same control fluid.
  • the thrust member 35 is connected to a hollow stem 37, coaxial with the shaft 21, which extends through the block 36 and is connected to the piston 38 of a single-acting cylinder 39 forming part of the braking device 11.
  • the cylinder 39 is supplied with pressurized fluid through an inlet 40 so as to move the piston 38 and allow the backward movement of the thrust member 35 against the action of the counter springs 34, when the brake must be deactivated.
  • the stable position of the piston 17 is also ensured in the case where a high axial force acts on the stem 18 of the cylinder, since this force is reduced considerably by means of the direct connection between screw shaft 19 and nut screw 20 as a result of the long pitch of the thread and the relatively small lever arm of the couple exerted by the nut screw, compared to the mean lever arm exerted by the braking device.
  • This makes it possible to operate with comparatively small braking and locking forces and hence realize a braking device 11 of limited dimensions, such that it can be easily accommodated in the extension of the barrel of the cylinder 10. In this way it is possible to realize an actuator with extremely small overall dimensions, suitable even for cylinders of small diameter, which have not been possible in operating and braking systems known hitherto.
  • Figure 4 of the accompanying drawings shows and alternative solution as regards the braking device 10 which in this case allows an active action, opposite to that of the braking device 10 in the preceding example.
  • FIG 4 parts identical or equivalent to those in figure 1 have been denoted by the same reference numbers.
  • the example in figure 4 differs from that shown in figure 1 in that the rotating braking disc 32 is in the form of a piston member having an annular braking rim on one side and a peripheral lip on the opposite side, which piston member is actuated, during activation of the brake, by the pressurized fluid in place of the elastic means or the counter springs 34 previously mentioned. Therefore, in the case of figure 4, the rotating braking disc 32 is directly designed as means for activating the brake, while centrifugal control of the braking disc 32 is still possible in the deactivated condition of the brake during travel of the piston 17 in either direction.
  • a pneumatic or hydraulic actuator comprising a centrifugally controlled brake means which is operated, during activation or deactivation, by the same pressurized fluid, so as to ensure a precise stopping action and stable positioning of the piston 17 in any programmable position controlled by means of the encoder 26, while observing very rigorous positioning tolerances of the order of one hundreths of a millimetre.
  • the actual arrangement of the braking device in addition to achieving the aforementioned advantages, owing to the considerable reduction in the overall dimensions, allows the braking device to be applied even to cylinders of considerably small dimensions.
  • Figures 5 and 6 show some possible variations of the movable braking disc 32.
  • the braking rim 33 protrudes on the same side of the fixed braking ring or disc 31, or equivalent braking element, so as to obtain lateral displacement of the centre of gravity of the abovementioned ring which is directed towards the fixed braking element, so as to exploit the centrifugal effect in order to move one braking element away from the other.
  • the same effect can be achieved with the solution of figure 5 or with that of figure 6.
  • the disc 32 along the peripheral rim 33 has a braking ring 33a consisting of material with a high coefficient of friction; the braking rim 33 in these cases does not protrude from the plane of the disc; however, the higher weight of the braking ring 33a is such as to cause a forward displacement of the centre of gravity of the entire braking rim, therefore still allowing the centrifugal effect to be used to advantage in the manner previously mentioned; this centrifugal effect which detaches the movable disc from the fixed disc can be accentuated or improved, for example designed so as to be slightly conical with respect to the disc 32, as shown in figure 6.
  • Figure 7 of the drawings shows a further characteristic feature of the actuator according to the present invention, which allows free orientation and displacement of the piston 17 and its hollow stem 18 with respect to the screw shaft 19 and the nut screw 20; this solution proves to be particularly useful for pneumatic actuators where the piston has a small degree of play with respect to the barrel of the cylinder, which, in the event of unbalanced loads, can cause slight axial displacement between worm screw and hollow stem of the piston.
  • the above was obtained by providing sufficient radial play between the nut screw 20 and the hollow piston 17, supporting this screw nut by means of two opposing self-aligning bearings arranged on the two sides of a radial flange 42.
  • the nut screw 20 is prevented from rotating with respect to the piston 17, for example by means of diametrically opposite pins 43 slidably inserted in respective holes 44 in the nut screw 20 and in an elongated hole or eyelet 45 in the piston, oriented in the axial direction of the actuator.
  • the use of self-aligning bearings in which the races of the balls consist of an annular surfaces arranged in a radial plane, and the corresponding possibility for the nut screw 20 to perform a translational movement parallel to itself, without any displacement in the axial direction advantageously also allow a skew arrangement of the screw shaft and the associated nut screw, with respect to the piston of the actuator.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vehicle Body Suspensions (AREA)
  • Power Steering Mechanism (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Actuator (AREA)
EP91107470A 1990-07-30 1991-05-08 Flüssigkeitsstellantrieb mit Programmsteuerung Ceased EP0469253A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT02111990A IT1243464B (it) 1990-07-30 1990-07-30 Attuatore lineare, programmabile, azionato a fluido.
IT2111990 1990-07-30

Publications (1)

Publication Number Publication Date
EP0469253A1 true EP0469253A1 (de) 1992-02-05

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ID=11177023

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EP91107470A Ceased EP0469253A1 (de) 1990-07-30 1991-05-08 Flüssigkeitsstellantrieb mit Programmsteuerung

Country Status (2)

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EP (1) EP0469253A1 (de)
IT (1) IT1243464B (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0562462A1 (de) * 1992-03-25 1993-09-29 UNIVER S.p.A. Pneumatischer Stellantrieb mit brems- und micrometrischer Verstelleinrichtung
EP0648942A1 (de) * 1993-10-06 1995-04-19 UNIVER S.p.A. Lineares pneumatisches Stellorgan mit einer umorientierbaren Verriegelungseinrichtung
EP1777432A1 (de) * 2005-10-19 2007-04-25 UNIVER S.p.A. Bremse für rotierende Welle
CN109578371A (zh) * 2018-12-05 2019-04-05 陕西理工大学 一种锁紧气缸
CN110925267A (zh) * 2020-01-07 2020-03-27 长春工业大学 基于丝杆锁紧式减摩驱动型直线定位气缸及其控制方法
DE102019103916A1 (de) * 2019-02-15 2020-08-20 Schunk Gmbh & Co. Kg Spann- Und Greiftechnik Greif- oder Spannvorrichtung mit einer Brems- und/oder Festsetzeinheit
DE102019103917A1 (de) * 2019-02-15 2020-08-20 Schunk Gmbh & Co. Kg Spann- Und Greiftechnik Greif- oder Spannvorrichtung mit einer Brems und/oder Festsetzeinheit
EP3842334A1 (de) * 2019-12-27 2021-06-30 Hamilton Sundstrand Corporation Kolbenanordnung für flugzeugtür

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108533563A (zh) * 2018-05-10 2018-09-14 四川大学 一种基于滚珠丝杠的外置摩擦机械自锁液压缸

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB683633A (en) * 1949-02-25 1952-12-03 Gen Motors Corp Improved fluid-pressure actuator
US2801615A (en) * 1954-02-19 1957-08-06 Gen Motors Corp Actuator with multiple disc type locking means
US2804053A (en) * 1954-04-14 1957-08-27 Gen Motors Corp Actuator and locking means therefor
US2879746A (en) * 1955-12-08 1959-03-31 Gen Motors Corp Actuator with unidirectional locking means
DE2034826A1 (de) * 1969-07-17 1971-02-04 Pneumo Dynamics Corp , Cleveland, Ohio (V St A ) Hydraulische Steuervorrichtung
GB2154282A (en) * 1984-02-14 1985-09-04 H C H Manufacturing Ltd Fluid pressure actuators

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB683633A (en) * 1949-02-25 1952-12-03 Gen Motors Corp Improved fluid-pressure actuator
US2801615A (en) * 1954-02-19 1957-08-06 Gen Motors Corp Actuator with multiple disc type locking means
US2804053A (en) * 1954-04-14 1957-08-27 Gen Motors Corp Actuator and locking means therefor
US2879746A (en) * 1955-12-08 1959-03-31 Gen Motors Corp Actuator with unidirectional locking means
DE2034826A1 (de) * 1969-07-17 1971-02-04 Pneumo Dynamics Corp , Cleveland, Ohio (V St A ) Hydraulische Steuervorrichtung
GB2154282A (en) * 1984-02-14 1985-09-04 H C H Manufacturing Ltd Fluid pressure actuators

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0562462A1 (de) * 1992-03-25 1993-09-29 UNIVER S.p.A. Pneumatischer Stellantrieb mit brems- und micrometrischer Verstelleinrichtung
EP0648942A1 (de) * 1993-10-06 1995-04-19 UNIVER S.p.A. Lineares pneumatisches Stellorgan mit einer umorientierbaren Verriegelungseinrichtung
EP1777432A1 (de) * 2005-10-19 2007-04-25 UNIVER S.p.A. Bremse für rotierende Welle
US7836813B2 (en) 2005-10-19 2010-11-23 Univer S.P.A. Self-locking braking device for rotary shafts, and relevant applications
CN109578371A (zh) * 2018-12-05 2019-04-05 陕西理工大学 一种锁紧气缸
CN109578371B (zh) * 2018-12-05 2020-06-16 陕西理工大学 一种锁紧气缸
DE102019103916A1 (de) * 2019-02-15 2020-08-20 Schunk Gmbh & Co. Kg Spann- Und Greiftechnik Greif- oder Spannvorrichtung mit einer Brems- und/oder Festsetzeinheit
DE102019103917A1 (de) * 2019-02-15 2020-08-20 Schunk Gmbh & Co. Kg Spann- Und Greiftechnik Greif- oder Spannvorrichtung mit einer Brems und/oder Festsetzeinheit
EP3842334A1 (de) * 2019-12-27 2021-06-30 Hamilton Sundstrand Corporation Kolbenanordnung für flugzeugtür
US11187023B2 (en) 2019-12-27 2021-11-30 Hamilton Sundstrand Corporation Piston assembly for aircraft door
CN110925267A (zh) * 2020-01-07 2020-03-27 长春工业大学 基于丝杆锁紧式减摩驱动型直线定位气缸及其控制方法
CN110925267B (zh) * 2020-01-07 2021-08-17 长春工业大学 基于丝杆锁紧式减摩驱动型直线定位气缸及其控制方法

Also Published As

Publication number Publication date
IT9021119A1 (it) 1992-01-30
IT1243464B (it) 1994-06-15
IT9021119A0 (it) 1990-07-30

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