US3537358A - Rotary actuators - Google Patents

Rotary actuators Download PDF

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Publication number
US3537358A
US3537358A US776042A US3537358DA US3537358A US 3537358 A US3537358 A US 3537358A US 776042 A US776042 A US 776042A US 3537358D A US3537358D A US 3537358DA US 3537358 A US3537358 A US 3537358A
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Prior art keywords
pistons
guide members
actuator
chambers
cylinder
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US776042A
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English (en)
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Alan Donald Bunyard
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    • 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
    • F15B15/02—Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member
    • F15B15/06—Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member for mechanically converting rectilinear movement into non- rectilinear movement
    • F15B15/065—Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member for mechanically converting rectilinear movement into non- rectilinear movement the motor being of the rack-and-pinion type

Definitions

  • Two parallel guides extend through the two pistons, one piston being fixed to one guide and the other piston being [56] References Cited fixed to the other guide, end portions of each guide sliding in UNlTED STATES PATENTS bearings and serving to limit the extent of cocking or skewing 5 37 4/1953 Flak 2/1 1 X of one or both of the pistons and thus preventing fouling of the 2,828,722 4/1958 Bohnhoffet a1. 92/136X li d r th r by,
  • This invention relates to piston-rack rotary actuators.
  • a disadvantage of a piston-rack rotary actuator which includes a pair of pistons adapted to reciprocate in opposite directions along a pair .of opposed cylinders is that the pistons have a tendency to cock or turn in the cylinder, thereby jamming and/or damaging the radially inner surface or surfaces of the cylinders and thus, in time, the seats.
  • the principal object of the present invention is to overcome this disadvantage.
  • the present invention consists in a pneumatically operated piston-rack rotary actuator which includes two pistons adapted for reciprocating movements in opposite directions along chambersnunder the influence of fluid pressure, said pistons having integral racks meshingwith a common pinion which is connected to an output shaft of said actuator, two parallel guide members each of which is so connected to a different one of said two pistons that relative movement between saidguide member and said piston is inhibited, each guide member also extending through the other of said pistons in a manner such that relative movement between said guide member and said other of said pistons is permitted.
  • P16. 1 illustrates, in longitudinalaxial section along the line [-1 in FIG. 3, oneembodiment of a pneumatically operated piston-rack rotary actuator constructed in accordance with the present invention and including parallel guide members;
  • H6. 2 illustrates a detail section on each of the lines ll-ll in FIG. 1;
  • F IG. 3 illustrates, in side elevation, partly in section, the actuator illustrated in FIG. 1 which includes pistons movable away from one another under the influence of a fluid under pressure and movable towards one another under the influence of compression springs;
  • FIG. 4 illustrates an end elevation of the actuator illustrated in FIG. 3 as seen from the left-hand end thereof;
  • FIG. 5 illustrates an alternative embodiment of a pneumatically operated piston-rack rotary actuator'having a different means of attachment of end caps compared with the means used in said one embodiment. .1
  • FIG. 1 there is illustrated a pneumatically operated piston-rack rotary actuator which includes two pistons 10, 11 adapted for reciprocating movements in opposite directions along cylindrical chambers under the influence of fluid pressure, said pistons having integral racks 12, 13, respectively, meshing with a common mutilated pinion 14 which is connected to or is integral with an output shaft of said actuator, of which shaft the axially outermost end is provided with spanner flats 15 and of which the opposite end is recessed (not illustrated) to accommodate the free end of the stern of a valve .which is to be operated by the actuator.
  • Said pistons 10, 11 are mounted upon tubular parallel guide members 16, 17 and are keyed thereto through grub screws 18, 19, respectively.
  • the cylindrical chambers in the embodiment illustrated are coaxial, being opposed parts of a continuous cylindrical chamber 20 which is defined by a cylindrical body 21- and ,endcaps'22, 23, the end caps being spaced apart by the cylindrical body 21 and said end caps 22, 23 and said body 21 being held together by open-ended tubes 24, 25 each of which is exteriorly screw threaded at each end thereof. lnteriorly screw threaded nuts 26 are screwed'on to the left-hand ends (as seen in FIG.
  • the integral racks 12, 13 are formed in axially extending sleeves 30, 31 which formparts of said pistons 10, 11.
  • the pistons 10, ,11 not only have the guide members 16, 17 extending through the sleeves 30, 31 thereof, respectively, but also have the other of the guide members 17, 16 extendin'g through apertures in which are located bearing bushes 32, 33, respectively, which are made of a material having a low coefficient of friction (for example Delrin", P.T.F.E., or the like).
  • Sealing rings 34, 35 are provided in seats therefor.
  • Each of the end caps 22, 23 is provided with axially spaced seats for the accommodation of a bearing bush 36 and a sealing ring 37 each of which encircles the guide member 16 and also with a seat for the accommodation of a bearing bush 38 which encircles the guide member 17.
  • Each of the bearing bushes 3,6, 38 is made of the same material as are the bearing bushes 32, 33 and each of the fourbearing bushes 32, 33, 36, .38 is discontinuous not only to enable them to be fitted and to allow for thermal expansion but also for the purpose of providing a passageway 39 (see FIG.
  • the tube 24 is similarly providedwithat least one hole 41 and the guide member 16 (unlike the guide member 17) is provided with at leastonehole 42.
  • Each end cap 22, 23 is provided with a plurality of axially extending recesses 43 (FIG. 3 and 4), each recess accommodating one end of at least one helical compression spring.
  • two compression springs 44, 45 are illustrated in Fig. 3, one within the other and the convolutions of one extending in a helix of opposite sense to that of the helix of the other.
  • a hose or other conduit (not illustrated) has one end thereof screwed into the bore 28 of that nut which is screwed onto the tube 24, the other end of said hose or conduit being connected directly or indirectly to a supply of fluid (for example air) under pressure.
  • fluid for example air
  • said fluid passes through the hole 41 but is unable to pass the sealing rings 37 and so passes through the hole 42 in the guide member 16 into the space between thepistons l0, 11 with the result that said pistons move away from one another (against the influence of the plurality of springs 44, 45 which act against the axially outer faces of the pistons 10, 11) into the relative positions thereof which have been illustrated in FIG. 1.
  • the actuator described above can be operated by omission of the sets of springs 44, 45 and the connection to that one of the nuts 27 which isscrewed on to the tube 25 of another hoseor other conduit.
  • the two hoses or conduits are connected to a valve and a supply of fluid under pressure, the arrangement beingsuch that, as the valve is usedto operate the actuator, to rotate the output shaft, the fluid previously applied to one side of each of the pistons is vented to atmosphereto enable the fluid being applied to the pistons simultaneously in the relative directions.
  • a pneumatically operated actuator which is devoid of said tubes 24, 25 and of the ancillary nuts 26, 27 is illustrated in FIG. and includes the same (or closely similar) cylindrical body 21, the same pistons l0, 11 with their .integral racks l2, 13, respectively, whose teeth mesh with the two sets of teeth of the mutilated pinion 14, and so on, the parts common to the two embodiments being indicated by the same reference numerals.
  • the principal differences stem from the omission of the tubes which acted as tie rods, and include end plates 50, 51.
  • the end plate 50 has formed therein spaced cylindrical cavities 52, 54 which are open at only one end and the end plate 51 has formed therein spaced cylindrical cavities 53, 55 which are open at both ends.
  • the cavities 52 and 53 are in axial alignment with one another when the end caps are properly assembled with the body 21 as also are the cavities 54 and 55, and the cavities 52, 53 accommodate the end portions of the guide member 17 (which is plugged at 17') whilst the cavities 54, 55 accommodate the end portions of the guide member 16.
  • Each of the cavities 52, 53 is provided with a seat for a bearing bush 36 and each of the cavities 54, 55 is provided with a bearing bush 38 which creates the passageway 39 which has been described above with reference to FIG. 2, the only difference being that in the embodiment now being described the bushes 38 encircle the guide member 16 whereas in the other embodiment they encircle the guide member 17.
  • Each of the end caps 50, 51 isfurther provided with a radially outwardly facing seat portion which, when the cap has been inserted into the respected end of the cylindrical body 21, is in radial alignment with a complementary radially inwardly facing seat portion, said two seat portions constituting a seat for the accommodation of a square section metal (preferably stainless steel) wire 57 which is formed with a loop or the like (not illustrated) at one end.
  • a square section metal (preferably stainless steel) wire 57 which is formed with a loop or the like (not illustrated) at one end.
  • the other end of said wire is inserted into an enlarged circumferential slit (not illustrated) in the cylindrical body 21, said slit being in radial register with the seat formed by the said two seat portions and being in communication with said seat, and said wire is pushed through said slit into said seat until the whole or substantially the whole of said seat has been occupied by said wire.
  • the loop or the like protrudes from said slit to an extent which is such as to enable any person wishing to remove the respective one of the end caps 50, 51 to grip the said loop with a pair of pliers and to extract the wire from its seat.
  • Said wire being a tight push fit in said seat, keeps the end cap firmly in place and the end cap is made pressure-tight by a sealing ring 58 accommodated in a seat which is formed in the cylindrical body 21 and which is located adjacent to and axially inwardly of the seat which accommodates the wire 57.
  • each of said cavities 53, 55 is open at both ends.
  • the end wall of each of said cavities 53, 55 is drilled and tapped to provide a bore 59 whereby an exteriorly screw threaded union (not illustrated) on one end of a hose or other conduit (not illustrated) can be connected to the actuator, the other end of said hose or other conduit being connected to a supply of fluid (for example air) under pressure by way of the customary three-way valve.
  • the sleeve 31 of the piston 11 and also the guide member 17 are drilled to provide a port 60 by which the interior or bore of the tubular guide member 17 and the space between the axially inner faces of the pistons 10, 11 are placed in communication with one another.
  • the pistons 10, 11 will consequently move simultaneously towards one another, displacing the fluid which is in the space between their axially inner faces through the port 60, through the end part of the bore of the guide member 17, through the cavity 53 and the hose or conduit which is screwed into the bore 59 which communicates with said cavity 53, and so to atmosphere via the three-way valve and rotating the output shaft in an anticlockwise direction.
  • fluid under pressure will be supplied to the cavity 53 from which it will pass through the port 60 to the space between the axially inner faces of the pistons l0, 11.
  • the pistons 10, 11 will thereupon move away from one another, thereby displacing the fluid which is in the space between the axially outer face of each piston and the axially inner face of the respective end cap past the bushes 38 into and through the cavity 55, through the hose or conduit which is screwed into the bore 59 which communicates with said cavity 55, and so to atmosphere via the three-way valve and rotating the output shaft in a clockwise direction.
  • each of the end caps 50, 51 can be modified in the manner which has been indicated on and which will now be described with reference to the end cap 50.
  • Said end cap 50 is shown by the dotted line 61 to have been increased in thickness over the greater part of its area when seen in plan; thus modified, the end cap 50 will not consist of a flat plate having two protuberances which will provide the cavities 52, 54 but will consist of a thick end cap having an outwardly directed flange whose thickness is considerably less than that of the remainder of said cap.
  • the increased thickness will enable the requisite number of recesses 43 (only one recess is shown in FIG. 5) to be formed in the end cap for the accommodation of one end of at least one compression spring.
  • FIGS. 1 to 4 and to FIG. 5 The two exemplary embodiments of an actuator according to the present invention which have been described above with reference, respectively, to FIGS. 1 to 4 and to FIG. 5 as supplemented or modified by any of FIGS. 1 to 4 operate very satisfactorily because the bearing bushes 36, 38 are spaced apart by substantially the greatest distance which is possible in the actuator and because each of the bearing bushes 36, 38 is also spaced from the point of loading by substantially the greatest distance which is possible in the actuator.
  • FIG. 5 without the modification which involves the introduction of the springs accommodated in recesses 43, as fluid under pressure is supplied to the axially outer faces of the pistons 10, 11, the guide members 16, 17 bow outwardly and in so doing ultimately make contact with the bearing bushes 33, 32, respectively.
  • a fluid operated piston-rack rotary actuator comprising, an open-ended cylinder, end caps sealingly closing each end of the cylinder, a pair of axially adjacent pistons reciprocably mounted on said cylinder, a rotatably mounted output shaft extending radially through the wall of said cylinder between said pistons, gear teeth on said shaft, a toothed rack on each of said pistons cooperatively mating with the gear teeth on said shaft for rotating said shaft upon reciprocation of said pistons, said pistons in sealing sliding engagement with the inner surface of said cylinder and defining with said cylinder and with said end caps a pair of chambers at opposite ends of said cylinder between said pistons and said end caps and an intermediate chamber between said pistons, a pair of spaced guide bores in the inner surface of each said end cap in axial alignment with the spaced guide bores in the other end cap, a
  • a fluid operated piston-rack rotary actuator comprising a cylinder having closedends, a pair of pistons reciprocably mounted within said cylinder, a shaft extending radially through the side of said cylinder, cooperating gear means on said shaft and on said pistons for causing said shaft to' rotate upon reciprocation of said pistons, a pair of guide bores in each end of the cylinder in axial alignment with the guide bores in the other end of the cylinder, a pair of parallel reciprocable guide members each fixed to a different one of said pistons and slidably received through the other of said pistons, the opposite ends of said guide members extending beyond said pistons and slidably received in said guide bores in said cylinder ends throughout the entire stroke of said pistons, and means for introducing fluid under pressure to said cylinder and pistons to cause said pistons to reciprocate, said guide members and said guide bores cooperating with said pistons to prevent canting and binding of said pistons in said cylinder due to lateral forces imposed on said pistons caused by engagement of said cooperating gear means
  • each guide member is tubular and wherein there is a bearing made of a material having a low coefficient of friction carried byeach of said pistons, said one of said guide members extending through that bearing which is carried by said other of said pistons and said other of said guide members extending through that bearing which is carried by said one of said pistons.
  • each spring of each set consists of a single helical compression spring.
  • each spring of each set consists of a pair of helical compression springs nested one within the other, the helix of said one spring of said pair of springs being wound in a sense opposite to that in which the helix of said other spring of said pair of springs is wound.
  • a pneumatically operated piston-rack rotary actuator which includes means defining two chambers, two parallel guide members having a nonfixed mounting relationship with said means, a rotatably mounted output shaft located between said two chambers, gear teeth carried by said shaft, :1 piston located in each of said twochambers, atoothed rack connected to each piston, the teeth of each rack being in permanent engagement with some of the gear teeth carried by said shaft, one of said pistons being fixed to one of said guide members for reciprocating movements in opposite directions with said one of said guide members and the other of said pistons being fixed to the other of said guide members for reciprocating movements in opposite directions with said other of said guide members, bearing means made of a material having a low coefficient of friction and disposed between said means defining two chambers on the one hand and the respective guide members on the other hand, said one of said guide members also extending through said other of said pistons with freedom for sliding movement therealongand said other of said guide members also extending through said one of said pistons with freedom for sliding movement therealong, means permissive of
  • a pneumatically operated piston-rack rotary actuator which includes means defining two chambers, two parallel guide members having a nonfixed mounting relationship with said means, a rotatably mounted output shaft located between said two chambers, gear teeth carried by said shaft, a piston located in each of said two chambers, a toothed rack connected to each piston, the teeth of each rack being in permanent engagement with some of the gear teeth carried by said shaft, one of said pistons being fixed to one of said guide members for reciprocating movements in opposite directions with said one of said guide members and the other of said pistons being fixed to the other of said guide members for reciprocating movements in opposite directions with said other of said guide members, bearing means made of a material having a low coefficient of friction and disposed between said means defining two chambers on the one hand and the respective guide members on the other hand, said one of said guide members also extending through said other of said pistons with freedom for sliding movement therealong and said other of said guide members also extending through said one of said pistons with freedom for sliding movement therealong, means permissive of the

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)
US776042A 1967-11-25 1968-11-15 Rotary actuators Expired - Lifetime US3537358A (en)

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GB5373167 1967-11-25

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US776042A Expired - Lifetime US3537358A (en) 1967-11-25 1968-11-15 Rotary actuators

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US (1) US3537358A (enrdf_load_stackoverflow)
BE (1) BE724375A (enrdf_load_stackoverflow)
BR (1) BR6804267D0 (enrdf_load_stackoverflow)
DE (1) DE1811427B2 (enrdf_load_stackoverflow)
FR (1) FR1592924A (enrdf_load_stackoverflow)
GB (1) GB1251805A (enrdf_load_stackoverflow)
IL (1) IL31096A (enrdf_load_stackoverflow)
SE (1) SE337746B (enrdf_load_stackoverflow)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638424A (en) * 1969-12-08 1972-02-01 Charbonnages De France Device for driving a hub in continuous unidirectional rotation by means of rectilinear toothed racks
US3672260A (en) * 1970-12-14 1972-06-27 Jean Gachot Compressed-air actuator
US4167897A (en) * 1975-06-19 1979-09-18 Bunyard Alan D Rotary actuators
US4271750A (en) * 1978-07-08 1981-06-09 Lucas Industries Limited Servo boosters for vehicle braking systems
US4307570A (en) * 1978-12-12 1981-12-29 Lucas Industries Limited Boosted master cylinder assemblies for vehicle braking system
US4328738A (en) * 1978-09-20 1982-05-11 Tokico Ltd. Vacuum servo booster
US4338854A (en) * 1978-11-21 1982-07-13 Lucas Industries Limited Servo boosters for vehicle braking systems
US4339921A (en) * 1978-07-10 1982-07-20 Itt Industries, Inc. Brake booster for an automotive vehicle
US4347779A (en) * 1979-05-10 1982-09-07 Itt Industries, Inc. Vacuum brake booster
US4353287A (en) * 1979-05-10 1982-10-12 Itt Industries, Inc. Brake booster
US4370917A (en) * 1979-07-14 1983-02-01 Bunyard Alan D Piston-rack rotary actuator
US4417500A (en) * 1978-05-31 1983-11-29 Tokico Ltd. Air pressure servomotor
US4527465A (en) * 1981-10-06 1985-07-09 Nissan Motor Company, Limited Cylinder apparatus for rack and pinion type power steering mechanism of motor vehicle
US4970944A (en) * 1985-02-07 1990-11-20 Conbraco Industries, Inc. Rotary actuator
US6626055B2 (en) * 2000-04-12 2003-09-30 Smc Corporation Rack and pinion type swing actuator
CN101858458A (zh) * 2010-06-08 2010-10-13 清华大学 一种驱动阀门的气动执行器
US20100294963A1 (en) * 2006-10-20 2010-11-25 Tiziano Bravo Pneumatic actuator, in particular for valves
US20110220819A1 (en) * 2010-03-05 2011-09-15 Krones Ag Actuator
US20230008971A1 (en) * 2019-12-02 2023-01-12 Shailesh SHARMA Methods and systems relating to improvements in reliability of fluid power actuators
US20230184268A1 (en) * 2020-05-14 2023-06-15 Ponsse Oyj Pressure medium cylinder and method for moving toothed bar and work machine

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1430612A (en) * 1973-06-26 1976-03-31 Keystone Int Valve actuator
SE8700976L (sv) * 1987-03-09 1988-09-10 G L C I Fjugesta Ab Cylinderkolvanordning
FR2736972B1 (fr) * 1995-07-17 1997-08-29 Ksb Sa Actionneur du type comprenant un verin

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638424A (en) * 1969-12-08 1972-02-01 Charbonnages De France Device for driving a hub in continuous unidirectional rotation by means of rectilinear toothed racks
US3672260A (en) * 1970-12-14 1972-06-27 Jean Gachot Compressed-air actuator
US4167897A (en) * 1975-06-19 1979-09-18 Bunyard Alan D Rotary actuators
US4417500A (en) * 1978-05-31 1983-11-29 Tokico Ltd. Air pressure servomotor
US4271750A (en) * 1978-07-08 1981-06-09 Lucas Industries Limited Servo boosters for vehicle braking systems
US4339921A (en) * 1978-07-10 1982-07-20 Itt Industries, Inc. Brake booster for an automotive vehicle
US4328738A (en) * 1978-09-20 1982-05-11 Tokico Ltd. Vacuum servo booster
US4338854A (en) * 1978-11-21 1982-07-13 Lucas Industries Limited Servo boosters for vehicle braking systems
US4307570A (en) * 1978-12-12 1981-12-29 Lucas Industries Limited Boosted master cylinder assemblies for vehicle braking system
US4347779A (en) * 1979-05-10 1982-09-07 Itt Industries, Inc. Vacuum brake booster
US4353287A (en) * 1979-05-10 1982-10-12 Itt Industries, Inc. Brake booster
US4370917A (en) * 1979-07-14 1983-02-01 Bunyard Alan D Piston-rack rotary actuator
US4527465A (en) * 1981-10-06 1985-07-09 Nissan Motor Company, Limited Cylinder apparatus for rack and pinion type power steering mechanism of motor vehicle
US4970944A (en) * 1985-02-07 1990-11-20 Conbraco Industries, Inc. Rotary actuator
US6626055B2 (en) * 2000-04-12 2003-09-30 Smc Corporation Rack and pinion type swing actuator
US20100294963A1 (en) * 2006-10-20 2010-11-25 Tiziano Bravo Pneumatic actuator, in particular for valves
US8056466B2 (en) * 2006-10-20 2011-11-15 Omal S.P.A. Pneumatic actuator, in particular for valves
US20110220819A1 (en) * 2010-03-05 2011-09-15 Krones Ag Actuator
US8667887B2 (en) * 2010-03-05 2014-03-11 Krones Ag Actuator for a closing element of a valve
CN101858458A (zh) * 2010-06-08 2010-10-13 清华大学 一种驱动阀门的气动执行器
CN101858458B (zh) * 2010-06-08 2012-02-22 清华大学 一种驱动阀门的气动执行器
US20230008971A1 (en) * 2019-12-02 2023-01-12 Shailesh SHARMA Methods and systems relating to improvements in reliability of fluid power actuators
US20230184268A1 (en) * 2020-05-14 2023-06-15 Ponsse Oyj Pressure medium cylinder and method for moving toothed bar and work machine
US12055163B2 (en) * 2020-05-14 2024-08-06 Ponsse Oyj Pressure medium cylinder and method for moving toothed bar and work machine

Also Published As

Publication number Publication date
GB1251805A (enrdf_load_stackoverflow) 1971-11-03
BR6804267D0 (pt) 1973-05-15
IL31096A (en) 1973-04-30
BE724375A (enrdf_load_stackoverflow) 1969-05-02
DE1811427B2 (de) 1975-10-30
DE1811427A1 (de) 1969-07-24
IL31096A0 (en) 1969-01-29
SE337746B (enrdf_load_stackoverflow) 1971-08-16
FR1592924A (enrdf_load_stackoverflow) 1970-05-19

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