EP0057301A1 - Ensemble de cylindre pneumatique - Google Patents

Ensemble de cylindre pneumatique Download PDF

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Publication number
EP0057301A1
EP0057301A1 EP81300360A EP81300360A EP0057301A1 EP 0057301 A1 EP0057301 A1 EP 0057301A1 EP 81300360 A EP81300360 A EP 81300360A EP 81300360 A EP81300360 A EP 81300360A EP 0057301 A1 EP0057301 A1 EP 0057301A1
Authority
EP
European Patent Office
Prior art keywords
hydraulic
piston
cylinder
hydraulic fluid
flow
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.)
Withdrawn
Application number
EP81300360A
Other languages
German (de)
English (en)
Inventor
Henry Walter Weyman
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to EP81300360A priority Critical patent/EP0057301A1/fr
Publication of EP0057301A1 publication Critical patent/EP0057301A1/fr
Withdrawn legal-status Critical Current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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/06—Servomotor systems without provision for follow-up action; Circuits therefor involving features specific to the use of a compressible medium, e.g. air, steam
    • F15B11/072—Combined pneumatic-hydraulic systems
    • F15B11/076—Combined pneumatic-hydraulic systems with pneumatic drive or displacement and speed control or stopping by hydraulic braking
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40553—Flow control characterised by the type of flow control means or valve with pressure compensating valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41527—Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a directional control valve
    • F15B2211/41536—Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an output member
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7055—Linear output members having more than two chambers
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/885—Control specific to the type of fluid, e.g. specific to magnetorheological fluid
    • F15B2211/8855—Compressible fluids, e.g. specific to pneumatics

Definitions

  • the present invention relates to a method and apparatus for controlling the rate of flow of fluid in a high pressure hydraulic fluid circuit and is especially concerned with controlling the ram speed of a piston in a pneumatic piston and cylinder assembly incorporating hydraulic damping.
  • a metering orifice is located in the circuit to restrict the oil flow, the thrust of the piston in a pneumatic piston and cylinder assembly causes a build up of hydraulic pressure and the resulting rate of flow is dependent upon the size of the orifice and the pressure drop across it. If the orifice size is variable, for example by employing a needle valve, the rate of flow and therefore the rani speed of the pneumatic cylinder may be controlled as required; for example to control the feed rate of a cutting tool.
  • the ram speed of the pneumatic cylinder may be caused to slow down progressively along its stroke and there could even be a total loss of pneumatic piston movement.
  • control is extremely sensitive and small adjustments of orifice size result in large changes in flow rate.
  • a pressure reducing valve i.e. a low pressure governer
  • a pressure reducing valve i.e. a low pressure governer
  • the low flow rates required to produce low ram speeds are obtained at orifice opening wide enough to avoid the danger of silting and the control responses also less sensitive to adjustments of orifice size.
  • a low pressure governer enables low flow rates to be selected, maintained consistently and fine adjustment to flow rates made without the need for minute adjustments of orifice settings.
  • the low pressure governer be of a design such that the controlled pressure is substantially independent of changes in applied pressure and demanded flow rates. Furthermore, since this governer must also pass the oil through a fine restriction in order to reduce the pressure, it should also automatically clear itself of any silting.
  • the hydraulic piston has a piston rod on one side and not on the other and therefore a hydraulic fluid reservoir must be available to accept the difference in volume on the retraction stroke and to return it on the extension stroke.
  • the reservoir In order that the hydraulic fluid from the reservoir may be returned to the cylinder, the reservoir must be pressurised, for example by a piston with spring loading or by the application of external pressure such as a compressed air supply. Since this reservoir pressure is present as a back pressure on the downstream side of the control orifice, it can be used to significantly reduce the pressure drop across the control orifice thus assisting in maintaining low and consistent flow rates within the hydraulic circuit.
  • the present invention provides a method for controlling the rate of flow of hydraulic fluid in a high pressure hydraulic fluid circuit in which hydraulic fluid under high pressure is caused to pass through a variable flow control orifice to a hydraulic fluid reservoir contained in the circuit wherein the hydraulic fluid under pressure is first caused to pass through a low pressure governer whereby the pressure drop across the said flow control orifice is reduced enabling more accurate control of the rate of flow of fluid through said orifice.
  • the invention provides a pneumatic piston and cylinder assembly including means for controlling the ram speed of the piston
  • said means comprises a hydraulic piston and cylinder assembly the hydraulic piston being driven by the operation of the pneumatic piston causing hydraulic fluid to be displaced from one side of the said hydraulic piston to the other side thereof via an interconnecting hydraulic circuit
  • said hydraulic circuit including flow controlling means for controlling the rate of flow of hydraulic fluid, therein whereby the ram speed of the pneumatic piston is controlled
  • said flow controlling means including in said hydraulic circuit a variable flow control orifice and a low pressure governer located upstream of said orifice, said hydraulic circuit further including a hydraulic fluid reservoir located downstream of said variable flow orifice, which reservoir is maintained under constant pressure.
  • the low pressure governer may comprise a chamber having an inlet and outlet for the hydraulic fluid and including a movable wall connected to means for controlling the flow of fluid into the said chamber in response to a movement of said wall resulting from an increase in hydraulic pressure on the outlet side of said chamber.
  • the above mentioned chamber may be formed from a cylinder incorporating a piston and associated piston rod movable therein said piston and piston rod having coaxial passageways extending therethrough, the free end of the piston rod forming one valve seat in a valve means having two co-operating valve seats for controlling the flow of hydraulic fluid into said cylinder and free end being urged away from the co-operating valve seat by resilient means acting against said piston.
  • a pneumatic cylinder 1 has a piston 2 which slides within cylinder 1 and is sealed by means of seal 3.
  • the piston 2 is carried on a piston rod 4 which is free to slide within the end piece of the assembly (not shown).
  • One end of the assembly is sealed by a closure block 8.
  • a hydraulic damping cylinder assembly is provided within cylinder 1, the cylinder 30 being formed within the pneumatic piston rod 4.
  • a piston 5 is carried by the hydraulic piston rod 6 and slides within the cylinder 30 and is sealed against the cylinder 30 by means not shown, to provide chambers 41 and 42 on either side of said piston.
  • Piston 2 is sealed against rod 6 by means of the sealing ring 7.
  • a hydraulic fluid bore 16 runs the length of the piston rod 6 from an inlet 33 on the right hand side of piston 5 to a chamber 32 in the closure block 8.
  • a passageway 17 connects chamber 32 with a pressure governer generally indicated at 18, via inlet 19.
  • a hydraulic bore passes the length of rod 6 from an outlet 34 positioned at the front of the piston rod and to the left of piston 5 the other end communicating with an annular passageway 10, contained in closure block 8, which is interconnected via passageway 11 with the outlet side of a flow control valve 12.
  • the flow control valve 12 comprises a conical valve seat 13 with which co-operates a needle valve 14 adjustable by means of the knurled knob 15.
  • Pressure governer 18 comprises a cylindrical chamber 35 which carries a hollow piston 22 having an end face 27, and which is sealed against the cylinder 35 by sealing ring 23, and a free end 40.
  • the associated piston rod 36 is freely movable within the annular ring 24 against which it is sealed by a rubber ring (not shown).
  • the piston 22 and piston rod 36 contain an axial hollow space 37 running the full length thereof, the right hand end of the passageway 37 communicating with the space 28 between the end face 27 of the piston 22 and the end wall of the cylinder 35.
  • Outlet 20 communicates with space 23 and via the passage 21, with the inlet side of the flow control valve 12.
  • the opposite end of the axial passageway 37 communicates with inlet 19 via the annular space 33.
  • a rubber seal 26 is fixed to the end wall of the cylinder 35 opposite the free end 40 of the piston rod 36.
  • % coil spring 25 is positioned between the annular ring 24 carrying the piston rod 36 and piston 22 to normally maintain a gap 39 between the free end of the piston rod 36 and the seal 26.
  • the hydraulic fluid reservoir 41 is formed. by the chamber in the cylinder 30 on the left hand side of piston 5 and is pressurised by means of a spring loaded piston located at the end of the said chamber or by an external supply of compressed air as described in patent No. 1,320,335.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
EP81300360A 1981-01-27 1981-01-27 Ensemble de cylindre pneumatique Withdrawn EP0057301A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP81300360A EP0057301A1 (fr) 1981-01-27 1981-01-27 Ensemble de cylindre pneumatique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP81300360A EP0057301A1 (fr) 1981-01-27 1981-01-27 Ensemble de cylindre pneumatique

Publications (1)

Publication Number Publication Date
EP0057301A1 true EP0057301A1 (fr) 1982-08-11

Family

ID=8188202

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81300360A Withdrawn EP0057301A1 (fr) 1981-01-27 1981-01-27 Ensemble de cylindre pneumatique

Country Status (1)

Country Link
EP (1) EP0057301A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2178109A (en) * 1985-07-25 1987-02-04 David William Arnold Actuator

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2326498A (en) * 1939-09-22 1943-08-10 Nat Automatic Tool Co Hydropneumatic machine tool feed
US3029904A (en) * 1959-09-28 1962-04-17 Modernair Corp Motion checking cylinder
US3176801A (en) * 1962-10-12 1965-04-06 Northrop Corp Precision motion control device
GB1320335A (en) * 1969-11-25 1973-06-13 Weyman H W Pneumatic cylinder assemblies
US3890999A (en) * 1972-12-15 1975-06-24 Eugene D Moskow Fluid pressure regulator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2326498A (en) * 1939-09-22 1943-08-10 Nat Automatic Tool Co Hydropneumatic machine tool feed
US3029904A (en) * 1959-09-28 1962-04-17 Modernair Corp Motion checking cylinder
US3176801A (en) * 1962-10-12 1965-04-06 Northrop Corp Precision motion control device
GB1320335A (en) * 1969-11-25 1973-06-13 Weyman H W Pneumatic cylinder assemblies
US3890999A (en) * 1972-12-15 1975-06-24 Eugene D Moskow Fluid pressure regulator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2178109A (en) * 1985-07-25 1987-02-04 David William Arnold Actuator

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): DE FR IT NL SE

17P Request for examination filed

Effective date: 19830204

STAA Information on the status of an ep patent application or granted ep patent

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18D Application deemed to be withdrawn

Effective date: 19850120