US3777621A - Double-acting servomotor - Google Patents

Double-acting servomotor Download PDF

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Publication number
US3777621A
US3777621A US00112679A US3777621DA US3777621A US 3777621 A US3777621 A US 3777621A US 00112679 A US00112679 A US 00112679A US 3777621D A US3777621D A US 3777621DA US 3777621 A US3777621 A US 3777621A
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Prior art keywords
piston
chambers
actuating fluid
bleed
piston members
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Expired - Lifetime
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US00112679A
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English (en)
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P Blok
T Viersma
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Individual
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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
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/149—Fluid interconnections, e.g. fluid connectors, passages

Definitions

  • ABSTRACT [30] Foreign Application Priority Data Double-acting servomotor comprising a cylinder and a Feb. 5, 1970 Netherlands 7001609 Piston System with Piston rods, wherein the clearance extending along the surfaces of the piston system and 52 U.S.
  • the invention relates to a double acting servomotor actuated by a pressure fluid and comprising a cylinder and a piston system with piston rods, said piston system and cylinder being able to make a movement relatively to each other and said cylinder comprising two working chambers, each of said chambers being delimited as its one end by a movable piston surface and at its other end by an end wall rigidly connected to the cylinder, said end wall provided with a passage for a piston rod, said two chambers each being connected via a conduit with a valve device which controls the supply of pres sure fluid to said working chambers. It is an object of the invention to provide such a servomotor which works with a very low friction.
  • the clearance extending along the surfaces of said piston system and said cylinder movable relatively to each other and connecting the one of said working chambers with the other of said working chambers is divided into two divisonal clearances lying in line, said divisional clearances being separated by a circular groove, each of said divisional clearances being at its one end wider than at its other end whereas the total clearance at its outer ends has the same width, the circular groove being connected with a space in which in operation the pressure has such a value that the pres sure at the smaller ends of the divisional clearances is always lower than the pressure at the wider ends of said divisional clearances, and the clearances extending along the surfaces of the parts of the working chambers movable relatively to each other and connecting the working chambers with the atmosphere have a width which decreases from the inside to the outside.
  • the piston system consists of two pistons spaced apart and being connected by a piston rod passing through an intermediate wall separating the working chambers and forming part of the cylinder wall, the passage for the piston rod having at its ends a larger diameter than in the middle between its ends and the passage at its smaller diameter being provided with a circular groove which is connected with a space in which in operation the pressure is lowered than the pressure in the working chambers and the conduit for the supply of the pressure fluid open into the working chambers on both sides of the intermediate wall in the immediate vicinity of said wall.
  • the conduit for the supply of the pressure fluid can be very short.
  • the discharge of the pressure fluid to the space of low pressure can occur through a fixed not-moving part if the cylinder is used as the stationary part of the motor.
  • an extra conduit for the supply of pressure fluid opens into each working chamber, said conduit being provided with a restriction for allowing to pass an amount of fluid corresponding with the amount of fluid leaking away through the clearances.
  • the piston system consists of two pistons spaced apart and being connected by a piston rod passing through an intermediate wall separating the working chambers and forming part of the cylinder wall, the passage for the piston rod having at its ends a smaller diameter than in the middle between its ends and the passage provided at its larger diameter with a circular groove which is connected with a space in which in operation the pressure is higher than the pressure in the working chambers and the conduit for the supply of the pressure fluid open into the working chambers on both sides of the intermediate wall in the immediate vicinity of said wall.
  • pressure fluid upon closing the main supply of pressure fluid to the working chambers, pressure fluid will leak through the clearances along the piston rod to the working chambers and along the pistons the pressure fluid will leak away to the outside.
  • the compensation of the leakage is obtained without supplying extra means.
  • the working chambers can be separated by a piston having at its ends a larger diameter than in the middle and being provided at its smaller diameter with a circular groove which is connected with a space in which in operation the pressure is higher than the pressure in the working chambers.
  • Thepressure fluid leaking into the working chambers along the piston can escape through the clearances along the piston rod. Also in this embodiment of the servomotor an automatical compensation of the leakage is obtained without applying extra means.
  • FIG. 1 is a servomotor according to the invention in a longitudinal section.
  • FIG. 2 a longitudinal section according to FIG. 1 of a servomotor in another embodiment
  • FIG. 3 a detail from FIG. 2 in another embodiment
  • FIG. 4 a detail from FIG. 1 in another embodiment.
  • the servomotor shown in FIG. 1 consists of a cylinder 1 with a piston system movable in said cylinder 1 and comprising a piston 2 and piston rod 3 and 4.
  • the piston rod 3 at the end of the cylinder 1 passes through a closure member 5 that is provided with a part 6 for guiding the piston rod.
  • the part 7 is provided with an O-ring seal 8 and a device 9 for stripping dirt.
  • the O -ring seal causes very little friction as the space 11 to be sealed is not under pressure.
  • the part 6 has a conical shape so that the clearance 10 at the end directed to the piston 2 is wider than at the other end. The clearance opens with its narrow end into an annular groove 11 which is connected via a conduit 12 with a conduit 13 which opens into a reservoir 14.
  • a closure member 15 which is provided with sealing rings and the part for guiding the piston rod has a clearance 16, the width of said clarance decreasing in the direction of the end directed away from the piston.
  • an annular groove 17 which is connected with a conduit 18 which also opens into the reservoir 14.
  • the piston 2 has a double conical shape so that the width of the clearance 19 and 20 between the piston 2 and the cylinder 1 decreases from the ends to the middle.
  • the clearances 19 and 20 open at the middle of the piston into a circular groove 21 in the piston, which groove 21 is connected via a canal 22 and a flexible duct 23 with the reservoir 14.
  • ducts 26 and 27 Into the working chambers 24 and 25 of the cylinder 1 open ducts 26 and 27.
  • the ducts 26 and 27 are connected with a valve 28.
  • the valve 28 is supplied with pressure fluid through the conduit 29 and this fluid is supplied from the reservoir 14 via a duct 30.
  • a pump 31 By means of a pump 31 the fluid is presurized and supplied to a reservoir 32 which is connected with the duct 29.
  • the pressure in this duct 29 can be controlled by means of a pressure control valve.
  • the valve 28 is controlled in a way not shown.
  • the pressure fluid can be applied to the working chamber 24 or 25 at will.
  • the pressure fluid which is discharged from one of the working chambers 24, 25 flows through the duct 53 back to the reservoir 14.
  • the duct 34 which contains a restriction 36 opens into the duct 27.
  • the duct 35 contains a corresponding restriction 37 whereas this duct 35 opens into the duct 26.
  • the restrictions 36 and 37 are dimensioned in such a way that always through the ducts 34 and 35 such an amount of pressure-fluid is flowing to the chambers 24 and 25 that the leakage losses through the clearances are compen sated.
  • the increasing or decreasing width of the clearances is obtained by means of the conical shape. It is also possible to apply a stepped shape, thus the width of the clearances is changing discontinuously. Nevertheless the same centering action is obtained.
  • the servomotor according to FIG. 2 consists of a cylinder 40 in which two pistons 41 and 42 can move.
  • the pistons 41 and 42 are connected by a piston rod 43.
  • a member 44 connected with the piston 41 is functioning s piston rod and passes to the outside of the cylinder.
  • the working chamber 45 and 46 in the cylinder are separated by a part 47 which is fixedly arranged in the cylinder 40.
  • the piston rod 43 passes through a passage in the part 47.
  • the part 47 has a double conical shape so that clearances 48 and 49 exist, the width of these clearances decreases from the end adjacent the working chambers to the other end.
  • the clearances 48 and 49 open into a groove 50 which is connected through a canal 51 in a way not shown with a pressureless reservoir.
  • Around the cylinder are mounted sleeves 52.
  • the space inside the sleeves 52 is connected with the space at the pressure less side of the I pistons 41 and 42.
  • the pressureless space 53 behind the piston 2 for example is connected through the duct 54 with the space 55 inside the sleeve 52.
  • the space 55 is through the conduit 56 also connected to the pressureless duct 51.
  • pressure fluid can be supplied to the ducts 58 or 59.
  • These ducts 58 and 59 open into the working chambers 45 and 46 on both sides of the part 47. Independently of the magnitude of the stroke of the pistons 41 and 42 the ducts 58 and 59 can be very short.
  • the discharge of the pressureless fluid through the duct 51 takes place only through stationary parts. The centering action on the moving parts in relation to each other is obtained in the same way as is described for the embodiment according to FIG. 1.
  • the ducts 60 and 61 contain restrictions 62 and 63. Through these ducts 60 and 61 in the same way as is indicated in FIG. 1 for the ducts 34 and 35 the leakage through the clearances can be compensated.
  • FIG. 3 a part 47 with the piston rod 43 passing therethrough is shown in another embodiment. From a circular groove 64 in the middle of the part 47 to both sides clearance 65 and 66 with decreasing width are extending.
  • the groove 64 is connected through a duct 67 with a source for high pressure, for example the pump for the pressure fluid.
  • the ducts 56 for discharging the pressure fluid, which is leaking along the pistons 41 and 42, are similarly to the embodiment in FIG. 2 connected with a pressureless space.
  • the pressure fluid leaking to the inside through the clearances 65 and 66 can leak to the outside through the clearances along the pistons 41 and 42.
  • the servo valve 57 closes the supply of pressure fluid to the working chambers 45 and 46, the leakage flow is maintained so that the hydrostatic bearings remain functioning.
  • FIG. 4 is shown a further embodiment of the piston 2 from FIG. 1.
  • the piston 2 has its smallest diameter in the middle.
  • the annular space 38 is connected with the duct 29 through a duct 39.
  • pressure fluid of a higher pressure than the pressures in the working chambers 25 and 24 is supplied to the annular groove 38.
  • the pressure fluid leaking along the piston 2 can leak away through the clearances and 16. So there is also an automatic compensation of the leakage losses so that there is no need of the ducts 34 and 35.
  • the width of the clearances is of the magnitude of some hundredth of millimeters.
  • the difference in width of one and the same clearance is also of the magnitude of hundredth of millimeters.
  • a double acting servomotor comprising, in combination:
  • piston means in said cylinder for defining first and second chambers therewithin, said piston means comprising a first piston member of frusto-conical shape having its larger end defining a restricted annular clearance space with said bore, a second piston member of frusto-conical shape having its larger end defining a restricted annular clearance space with said bore, and means joining said piston members to each other for movement in unison; a source of pressurized actuating fluid; control valve means selectively connecting said source to said chambers for differentially pressurizing them selectively to move the piston members in opposite directions and for holding the pressures in said chambers to hold said piston members in selected fixed positions;
  • bleed means defining a fluid circulation flow path through each chamber and past each associated piston member for continuously conveying actuating fluid past each piston member from the small end to the large end thereof and to a bleed flow exhaust means and including means for continuously supplying actuating fluid to each flow path independently of said control valve means.
  • a double acting servomotor ay defined in claim 1 6 closing said bore between said piston members and having a double conical bore receiving said piston rod, said double conical bore having a central annular space which is common to both of said flow paths.
  • a double acting servomotor as defined in claim 1 including at least one piston rod joined to said first piston member and projecting axially of said bore in the cylinder to pass outwardly therefrom, said cylinder having an end wall provided with :a bore receiving said piston rod and there being a sleeve surrounding said piston rod and having a conical bore. tapering inwardly around the piston rod toward said end wall to define a progressively restricted passage for actuating fluid leading from that chamber defined by said first piston member.
  • a double acting servomotor of the type including piston-cylinder means having a pair of piston mem bers joined for unison movement by connection means and each having an associated chamber for receiving actuating fluid, at least one piston'rod connected to one of said piston members and control valve means connected to said chambers for differentially pressurizing them selectively to move the piston members in opposite directions and for holding the pressures in said chambers to position said piston members in selected fixed positions, the improvement which comprises:
  • bleed means for continuously circulating actuating fluid through both said chambers and past both said piston members irrespective of the operating condition of said control valve means; said piston members each being of frusto-conical shape having their smaller ends disposed upstream of the direction of actuating fluid flow effected by said bleed means whereby said piston members to the source.
  • bleed means includes a flow-restricting member in each circuit between the source of pressurized fluid and the associated chamber.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)
  • Transmission Of Braking Force In Braking Systems (AREA)
US00112679A 1970-02-05 1971-02-04 Double-acting servomotor Expired - Lifetime US3777621A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7001609A NL7001609A (enrdf_load_stackoverflow) 1970-02-05 1970-02-05

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US3777621A true US3777621A (en) 1973-12-11

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US (1) US3777621A (enrdf_load_stackoverflow)
CA (1) CA934345A (enrdf_load_stackoverflow)
DE (1) DE2105236A1 (enrdf_load_stackoverflow)
FR (1) FR2080961B3 (enrdf_load_stackoverflow)
GB (1) GB1346452A (enrdf_load_stackoverflow)
NL (1) NL7001609A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922902A (en) * 1973-12-06 1975-12-02 Hinson Virgil Dent removal device
DE3145494A1 (de) * 1981-11-16 1983-05-26 Wabco Westinghouse Fahrzeugbremsen GmbH, 3000 Hannover Einrichtung zur fuehrung des kolbens eines arbeitszylinders
US4998460A (en) * 1988-11-14 1991-03-12 U.S. Philips Corporation Piston engine
US5218896A (en) * 1986-11-06 1993-06-15 Canon Kabushiki Kaisha Driving mechanism with gas bearing
WO2004003356A1 (de) * 2002-06-28 2004-01-08 Daniel Cech Die dichtungs- und kühlungsart der kolbenmechanismen und die anlage zur ausführung dieser art
US8656895B2 (en) 2011-12-29 2014-02-25 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US8720317B2 (en) 2011-12-29 2014-05-13 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US8899192B2 (en) 2011-12-29 2014-12-02 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US9097203B2 (en) 2011-12-29 2015-08-04 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US9169797B2 (en) 2011-12-29 2015-10-27 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US10215229B2 (en) 2013-03-14 2019-02-26 Etagen, Inc. Mechanism for maintaining a clearance gap
US10985641B2 (en) 2018-07-24 2021-04-20 Mainspring Energy, Inc. Linear electromagnetic machine system with bearing housings having pressurized gas
US20220381269A1 (en) * 2019-06-27 2022-12-01 Robert Bosch Gmbh Hydraulic Control Block and Hydraulic Axle Therewith
US12255514B2 (en) 2021-07-30 2025-03-18 Mainspring Energy, Inc. Systems and methods for flexure-based bearing mounting

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3235784C2 (de) * 1982-09-28 1984-10-31 Festo-Maschinenfabrik Gottlieb Stoll, 7300 Esslingen Druckmittelbetätigter doppeltwirkender Arbeitszylinder
JP3825737B2 (ja) 2002-10-24 2006-09-27 住友重機械工業株式会社 精密位置決め装置及びこれを用いた加工機

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103252A (en) * 1934-03-06 1937-12-28 Sullivan Machinery Co Rock drill
US2623501A (en) * 1946-09-28 1952-12-30 Olaer Marine Soc Piston for fluid pressure cylinders
US3003471A (en) * 1958-06-23 1961-10-10 Gen Motors Corp Actuator with stroke end locking means and stroke adjusting means
US3035879A (en) * 1958-03-14 1962-05-22 Sulzer Ag Means for centering the piston of a piston compressor
US3058450A (en) * 1959-06-25 1962-10-16 Lissau Frederic Hydraulic positioning servo system
US3063423A (en) * 1961-08-17 1962-11-13 Gen Precision Inc Seal means for hydraulic actuator
US3221770A (en) * 1961-03-03 1965-12-07 Faisandier Jacques Hydraulic distributor valve and by-pass means
US3522760A (en) * 1968-07-24 1970-08-04 Westinghouse Electric Corp Hydraulic piston

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103252A (en) * 1934-03-06 1937-12-28 Sullivan Machinery Co Rock drill
US2623501A (en) * 1946-09-28 1952-12-30 Olaer Marine Soc Piston for fluid pressure cylinders
US3035879A (en) * 1958-03-14 1962-05-22 Sulzer Ag Means for centering the piston of a piston compressor
US3003471A (en) * 1958-06-23 1961-10-10 Gen Motors Corp Actuator with stroke end locking means and stroke adjusting means
US3058450A (en) * 1959-06-25 1962-10-16 Lissau Frederic Hydraulic positioning servo system
US3221770A (en) * 1961-03-03 1965-12-07 Faisandier Jacques Hydraulic distributor valve and by-pass means
US3063423A (en) * 1961-08-17 1962-11-13 Gen Precision Inc Seal means for hydraulic actuator
US3522760A (en) * 1968-07-24 1970-08-04 Westinghouse Electric Corp Hydraulic piston

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922902A (en) * 1973-12-06 1975-12-02 Hinson Virgil Dent removal device
DE3145494A1 (de) * 1981-11-16 1983-05-26 Wabco Westinghouse Fahrzeugbremsen GmbH, 3000 Hannover Einrichtung zur fuehrung des kolbens eines arbeitszylinders
US5218896A (en) * 1986-11-06 1993-06-15 Canon Kabushiki Kaisha Driving mechanism with gas bearing
US4998460A (en) * 1988-11-14 1991-03-12 U.S. Philips Corporation Piston engine
WO2004003356A1 (de) * 2002-06-28 2004-01-08 Daniel Cech Die dichtungs- und kühlungsart der kolbenmechanismen und die anlage zur ausführung dieser art
WO2004003370A1 (de) * 2002-06-28 2004-01-08 Daniel Cech Kolbenmotor
US9004038B2 (en) 2011-12-29 2015-04-14 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US10006401B2 (en) 2011-12-29 2018-06-26 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US8770090B2 (en) * 2011-12-29 2014-07-08 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US8899192B2 (en) 2011-12-29 2014-12-02 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US8656895B2 (en) 2011-12-29 2014-02-25 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US9097203B2 (en) 2011-12-29 2015-08-04 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US9169797B2 (en) 2011-12-29 2015-10-27 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
US8720317B2 (en) 2011-12-29 2014-05-13 Etagen, Inc. Methods and systems for managing a clearance gap in a piston engine
USRE49259E1 (en) 2011-12-29 2022-10-25 Mainspring Energy, Inc. Methods and systems for managing a clearance gap in a piston engine
US10215229B2 (en) 2013-03-14 2019-02-26 Etagen, Inc. Mechanism for maintaining a clearance gap
US10985641B2 (en) 2018-07-24 2021-04-20 Mainspring Energy, Inc. Linear electromagnetic machine system with bearing housings having pressurized gas
US11616428B2 (en) 2018-07-24 2023-03-28 Mainspring Energy, Inc. Linear electromagnetic machine system
US20220381269A1 (en) * 2019-06-27 2022-12-01 Robert Bosch Gmbh Hydraulic Control Block and Hydraulic Axle Therewith
US11873848B2 (en) * 2019-06-27 2024-01-16 Robert Bosch Gmbh Hydraulic control block and hydraulic axle therewith
US12255514B2 (en) 2021-07-30 2025-03-18 Mainspring Energy, Inc. Systems and methods for flexure-based bearing mounting

Also Published As

Publication number Publication date
FR2080961B3 (enrdf_load_stackoverflow) 1973-10-19
GB1346452A (en) 1974-02-13
CA934345A (en) 1973-09-25
NL7001609A (enrdf_load_stackoverflow) 1971-08-09
DE2105236A1 (de) 1971-08-19
FR2080961A3 (enrdf_load_stackoverflow) 1971-11-26

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