US3757646A - Safety circuit for a working cylinder - Google Patents

Safety circuit for a working cylinder Download PDF

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Publication number
US3757646A
US3757646A US00142192A US3757646DA US3757646A US 3757646 A US3757646 A US 3757646A US 00142192 A US00142192 A US 00142192A US 3757646D A US3757646D A US 3757646DA US 3757646 A US3757646 A US 3757646A
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United States
Prior art keywords
valve
piston
duct
cylinder
safety
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.)
Expired - Lifetime
Application number
US00142192A
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English (en)
Inventor
R Rohner
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.)
Sulzer AG
Original Assignee
Sulzer AG
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
Priority claimed from CH751470A external-priority patent/CH524076A/de
Application filed by Sulzer AG filed Critical Sulzer AG
Application granted granted Critical
Publication of US3757646A publication Critical patent/US3757646A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
    • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
    • F16K17/10—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with auxiliary valve for fluid operation of the main valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D17/00—Regulating or controlling by varying flow
    • F01D17/20—Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted
    • F01D17/22—Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted the operation or power assistance being predominantly non-mechanical
    • F01D17/26—Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted the operation or power assistance being predominantly non-mechanical fluid, e.g. hydraulic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/16—Trip gear
    • F01D21/18—Trip gear involving hydraulic means
    • 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
    • F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
    • F15B20/004—Fluid pressure supply failure

Definitions

  • This invention relates to a safety circuit and, more particularly, to a safety circuit for a hydraulic or pneumatic valve installation.
  • safety circuits with a hydraulic or pneumatic working cylinder for example, for controlling a valve
  • a double acting piston in the cylinder which is adapted to traverse into a safety position due to the action of an energy source in the event of a pressure drop of the medium in the working cylinder.
  • these working cylinders have had cylinder chambers which are separated by the piston and which communicate with each other through valve means which are biased by a safety signal.
  • a safety circuit of this kind has been proposed for a by-pass valve disposed on a live steam line. Also, in order to minimize the losses of hydraulic medium, it has been necessary for the valve means to be constructed with small clearances.
  • valve means may become blocked by resinous matter, for example, due to gumming of the hydraulic medium, so that a substantial force is required to actuate the valve means. if this occurs, the means for controlling the valve means such as an electro-magnet which supplies the force, is then unable to ensure reliable functioning of the safety circuit.
  • the invention provides a servomotor for operating a valve with a safety circuit which is able to actuate the servomotor to move a piston thereof into a safety position.
  • the valve may, for example, be a bypass valve in a vapor generating plant while the servomotor utilizes an energy source to initiate movement of a piston.
  • This energy source may be represented by the pressure of the flow medium which acts on the valve body of the valve or by a spring disposed in the working cylinder.
  • the servomotor has a piston therein which divides a working cylinder of the servomotor into two chambers while the safety circuit includes a valve means which is connected to the cylinder chambers for moving the piston in response to a safety signal and a power amplifier which isdisposed in the path of the safety signal.
  • the power amplifier is connected via an automatic selector circuit to a source of pressure medium for the servomotor and to the working cylinder side which corresponds to the safety position of the piston.
  • the selector circuit advantageously comprises two non-return valves whose operating directions are in opposition to each other.
  • the power amplifier ensures actuation of the valve means even if the valve means has become jammed by resinous matter after prolonged idleness. Also, if the pressure of the medium diminishes or drops below a certain value at the moment at which a safety signal appears, and if the piston nevertheless does not traverse .into the safety position, the selector circuit will come into action and ensure that the piston nevertheless traverses into the safety position.
  • a non-return valve is disposed between the valve means and the cylinder chamber. disposed opposite to the cylinder chamber corresponding to,the safety position of the piston.
  • This non' return valve is constructed. to permit flow only from cylinder chamber to cylinder chamber and the actuation of the valve means is performed from that flow side of the valve means which is disposed between the valve means and the non-return valve.
  • the power amplifier can be constructed with a multiple piston or as a simple change-over element.
  • the amplifier comprises a control valve with a single-acting piston.
  • the advantage of this latter construction is that the power amplifier has only a single piston clearance at which the pressure medium may escape to the relief side. This advantage becomes effective if the medium, controlled by the abovementioned valve, is used as the pressure medium in the safety circuit.
  • FIG. 1 illustrates a safety circuit according to the invention connected to a servomotor for a valve
  • FIG. 2 illustrates a modified safety circuit according to the invention.
  • a servomotor 1 includes a hydraulic (or pneumatic) working cylinder 2 and a double-acting piston 3 which is slidably mounted in the working cylinder 2 to divide the cylinder 2 into two chambers 2a, 2b.
  • the piston 3 also carries a piston rod 4 which connects to a valve body 5 of a valve 6 such that the servomotor l is adapted to drive the valve body 5.
  • the valve 6 controls the transfer of a flow medium from a chamber or inlet port 6a to a chamber or outlet port 6b.
  • the working cylinder 2 of the servomotor l is also provided with an energy accumulator 110 in the form of a spring 10 which acts on the piston 3 so that the valve 6 opens when the pressure of a control fluid in the cylinder chamber 2a of the working cylinder 2 diminishes or drops below a defined value, and is retained in an open state, independently of any static or dynamic forces of the flow medium controlled by the valve 6 acting on the valve body 5.
  • the energy source may also be represented by the pressure of the flow medium which acts on the valve body 5 coupled to the valve rod 4.
  • the servomotor 1 is controlled by a control valve 13 through ducts ill, 12 which are connected to the chambers 2a, 2b.
  • the control valve 13 includes a control piston 15 which bears on a spring 116 and a signal line 18, through which control signals reach the control valve 13 is connected to the valve 13.
  • the control valve T3 is provided with a port 19 which communicates through a pressure fluid duct 20 to a pressure fluid pump 21 while a pair of other ports 22, 23 of the control valve 13 are connected to an oil sump through a discharge duct 24 for the control fluid.
  • control piston l3 When disposed in a suitable position, the control piston l3 connects the cylinder chamber 2a through the duct 11 with the pressure fluid duct and connects the cylinder chamber 2b with the discharge duct 24 so that the piston is moved in the direction of the cylinder chamber 2b under the influence of the control fluid.
  • a safety circuit is connected to the servomotor 1 and includes ducts 30, 31 which are respectively connected to the cylinder chambers 2a, 2b on both sides of the piston 3 of the servomotor 1.
  • a pair of nonreturn valves 32, 33 are disposed between the ducts 30, 31 with the valve body 32a of the non-return valve 32 being biased by a spring 321) while the valve body 330 of the non-return valve 33 is connected to a piston 34 which is adapted to move axially in a housing 35.
  • the non-return valve 33 is also associated with a hydraulic or pneumatic power amplifier which takes the form of a control valve 40.
  • the control valve 40 is controlled by an electro-magnet 41 with a plunger armature 41a which is coupled to a control piston 40a in the control valve 40.
  • the control valve 40 is constructed to have a substantial amount of clearance so that it can be easily operated by the electro-mag'net 41.
  • a fluid discharge duct 45 extends from the control valve 40 to the oil sump 25. Redundance elements 32, 33', 40, 41', and 32", 33", 40", 41" to increase the reliability of the system are connected in parallel to the non-return valves 32, 33 and the associated control valves 40 and electro-magnet 41.
  • the control valve 40 is connected through a duct 42 and a distribution duct 43, on the one hand, through a duct 44 to a fluid duct 20 and, on the other hand, through a duct 51 to the duct 30 of the working cylinder 2.
  • a non-return valve 50 is disposed in the duct 44 and a non-return valve 52 is disposed in the duct 51.
  • These two non-return valves 50, 52 have an oppositely oriented valve action. In normal operation of the plant, the non-return valve 52 remains closed by the pressure applied by a spring 52a therein and the fluid pressure in the ducts 44 and 51 acting on the valve body 52b.
  • the loading applied by the spring 50a on the valve body 50b of the non-return valve 50 is so selected that the control fluid can flow from the duct 20 without ob struction into the duct 44.
  • the two non-return valves 50, 52 represent a so-called selector circuit for the control valve 40, that is, the control valve 40 obtains a control fluid either from the pressure fluid duct 20 through the non-return valve 50 or from the duct 30 through the non-return valve 52, depending on the pressure prevailing in the pressure fluid duct 20.
  • the safety circuit operates as follows:
  • the servomotor l is controlled by the control valve 13.
  • the non-return valves 32 and 33 are closed, the non-return valve 32 due to the action of the spring 32b acting on the valve body 32a and the non-return valve 33 due to the pressure of the control fluid which biases the right-hand side (as shown) of the piston 34. Since the valve 52 is closed, the control valve 40 is fed from the fluid duct 20 via the non-return valve 50, the connecting duct 44, the distribution duct 43 and the connecting duct 42. if a safety signal reaches the electro-magnet 41 from a suitable source, the plunger armature 41a will be attacted against the force exerted by the spring 41b.
  • the control piston 40a of the control valve 40 thus moves to the right as viewed to connect the duct 42 to the non-return valve 33 so that the side 34a of the piston 34 is biased by pressure fluid and the side 34b is relieved of hydraulic fluid. Accordingly, the non-return valve 33 will open. It is thus possible for pressure fluid to be transferred from the duct 30 through the nonreturn valve 32 into the duct 31 and from there into the cylinder chamber 2b of the servomotor 1.
  • the control valve 40 will then be supplied with the pressure fluid disposed in the cylinder chamber 2a through the non-return valve 52 and the ducts 51, 43 and 42.
  • the control valve 40 will open the non-return valve 33 as described above so that fluid from the duct 30 will once again pass through the nonreturn valve 33 and through the non-return valve 32 into the duct 31 in order to reach the cylinder chamber 2b of the servomotor l.
  • the piston 4 of the servomotor 1 will, thus, once again traverse into the safety position due to the action exerted by the spring 10.
  • the non-return valve 52 is opened, the non-return valve 50 is automatically closed by the fluid pressure prevailing in the duct 44 and thus prevents the control fluid from being lost through the fluid duct 20.
  • the piston 34 is so dimensioned that the non-return valve 33 is reliably opened by a control fluid pressure which is obtained due to the action of the spring 10 immediately before the piston 3 is disposed in the cylinder chamber 2a.
  • the safety circuit can alternatively include two non-return valves 60, 61 which are serially disposed between the ducts 30, 31 connected to the cylinder chambers 2a, 2b, respectively, on both sides of the piston 3 of the servomotor I.
  • One piston 62 of the non-return valve or check valve is connected to a valve body 64 which is biased to the left as viewed by a spring 63.
  • the nonreturn valve 60 is controlled through a duct 70 from a hydraulic or pneumatic power amplifier in the form of a control valve 65 with a single-acting piston 68 or some other single-acting change-over element.
  • the control valve 65 in turn is controlled by an electromagnet 66 in a balance circuit having a plunger armature 67 which is connected to the single-acting piston 68.
  • the control valve 65 is connected through a duct 42' and the distribution duct 43 to the selector circuit, formed by the non-return valve 50 and 52, and to the fluid duct 20.
  • the non-return valve 6k prevents pressure medium from 'being transferred into the duct section between the two non-return valves 61, 66 in normal operation when the non-return valve 60 is closed so that no leakage losses in the valve 60 can be transferred through its low pressure ducts. Since the power amplifier 65 has only one single-acting piston 68, pressure medium can leak only through this single-acting piston 68 to the low'pressure side of the system so that the leakage losses remain very small.
  • a safety signal reaches the electro-magnet 66 to deactivate the electro-magnet 66, the piston 68 of the power amplifier 65 will release the connection through the duct 71) between the duct 42 and the non-return valve 60 so that the side 62a of the piston 62 is biased with pressure fluid. Accordingly, the non-return valve 60 will open. Pressure fluid may then flow from the cylinder chamber 2a of the servomotor ll connected to the duct 30 via the non-return valve 66, through its discharge duct 71l and through the non-return valve 61 into the duct 31 and from there may reach the cylinder chamber 2b of the servomotor 1 connected to the duct 3Il.
  • the pressure on the piston side 3a of the servomotor 1 therefore diminishes rapidly and, due to the action of the spring Ml, disposed in the servomotor l and acting on the piston 3, the piston 3 then moves rapidly upwardly and into the safety position.
  • the servomotor 1 will open the valve (not shown) connected to the piston rod 4 and will have fulfilled its safety function.
  • the non-return valve 52 of this circuit will also come into action by opening.
  • the power amplifier 65 will then be supplied through the non-return valve 52 and the ducts 51, 43 and 412' with the pressure fluid disposed in the cylinder chamber 2a of the servomotor 1.
  • the power amplifier 65 then opens the non-return valve as described hereinabove so that once again control fluid passes from the duct 30 through the nonreturn valve 60 and through the non-return valve 61 into the duct 31 and from there into the servomotor l.
  • the piston 3 of the servomotor 1 will then once again move into the safety position due to the action exerted by the spring 110.
  • a working cylinder (2) having a double-acting piston (3) dividing said cylinder into a first (2a) and a second (2b) chamber on opposite sides thereof; first control valve means (113) for selectively supplying pressure medium from a source of pressure medium (21) to either side of said piston (3) for moving said piston (3) between a safety position on that side of said cylinder pertaining to said first chamber (2a) and an operative position on the opposite side of said cylinder; power means (10) disposed in said cylinder to bias said piston (3) toward said safety position; duct means connecting said first and second chambers; first valve means (33) in said duct means and including actuator means (34) communicating said chambers (20, 2b) with each other in response to a safety signal; conduit means connecting said source of pressure medium and said first valve means; safety signal amplifying means (40) including a valve means and a signal responsive valve actuating means disposed in said conduit means to operate said actuator means to actuate said first valve means (33); passage means connecting said first chamber to

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Actuator (AREA)
US00142192A 1970-05-21 1971-05-11 Safety circuit for a working cylinder Expired - Lifetime US3757646A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH751470A CH524076A (de) 1970-05-21 1970-05-21 Sicherheitsschaltung
CH10171A CH533245A (de) 1970-05-21 1971-01-06 Sicherheitsschaltung

Publications (1)

Publication Number Publication Date
US3757646A true US3757646A (en) 1973-09-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00142192A Expired - Lifetime US3757646A (en) 1970-05-21 1971-05-11 Safety circuit for a working cylinder

Country Status (6)

Country Link
US (1) US3757646A (de)
BE (1) BE767456A (de)
CA (1) CA930283A (de)
FI (1) FI57172C (de)
FR (1) FR2090187B1 (de)
GB (1) GB1306786A (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3971296A (en) * 1974-09-18 1976-07-27 Kelor Limited Pneumatic actuators
US4034815A (en) * 1975-03-20 1977-07-12 Caterpillar Tractor Co. Blade lift float circuit for motor graders
US4147325A (en) * 1977-03-29 1979-04-03 Combustion Engineering, Inc. Hydraulic control assembly
WO1981000249A1 (en) * 1979-07-11 1981-02-05 J Muntjanoff Self adjusting actuator system
US4313633A (en) * 1979-07-11 1982-02-02 Caterpillar Tractor Co. Self adjusting actuator system
US4337689A (en) * 1979-06-22 1982-07-06 Sulzer Brothers Limited Safety system for a double acting servomotor
EP1209394A3 (de) * 2000-11-24 2003-08-06 Voith Turbo GmbH & Co. KG Elektrohydraulischer Stellantrieb
WO2017021080A1 (de) * 2015-07-31 2017-02-09 Voith Patent Gmbh Hydraulischer antrieb zum ausführen einer linearen bewegung
CN111288044A (zh) * 2020-02-14 2020-06-16 三一汽车起重机械有限公司 液压系统和工程机械
CN113028077A (zh) * 2021-02-26 2021-06-25 重庆市江北嘴水源空调有限公司 一种江水取水用阀门

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0496021B1 (de) * 1991-01-25 1994-11-30 Asea Brown Boveri Ag Zuschaltventil und hydraulisches Sicherheits- und Kraftölsystem, in welchem das Zuschaltventil verwendet wird
CN109404065B (zh) * 2018-10-12 2021-12-17 上海华电电力发展有限公司 防止主机汽门遮断电磁阀故障引起机组跳闸的控制方法
JP7321201B2 (ja) 2021-03-18 2023-08-04 三菱重工業株式会社 蒸気弁

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2352334A (en) * 1942-06-09 1944-06-27 Macomber Thomas Wesson Aircraft control system
US2427549A (en) * 1942-08-08 1947-09-16 Weatherhead Co Gyroscopic apparatus
US2855900A (en) * 1954-11-02 1958-10-14 British Messier Ltd Fluid pressure servo system with valve actuating means having a differential feel
US3604313A (en) * 1970-05-14 1971-09-14 Gen Signal Corp Hydraulic power circuit with rapid lowering provisions
US3608431A (en) * 1969-07-14 1971-09-28 Lummus Industries Control system for the ram of vertically disposed fluid pressure cylinders

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE517780A (de) * 1952-02-21

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2352334A (en) * 1942-06-09 1944-06-27 Macomber Thomas Wesson Aircraft control system
US2427549A (en) * 1942-08-08 1947-09-16 Weatherhead Co Gyroscopic apparatus
US2855900A (en) * 1954-11-02 1958-10-14 British Messier Ltd Fluid pressure servo system with valve actuating means having a differential feel
US3608431A (en) * 1969-07-14 1971-09-28 Lummus Industries Control system for the ram of vertically disposed fluid pressure cylinders
US3604313A (en) * 1970-05-14 1971-09-14 Gen Signal Corp Hydraulic power circuit with rapid lowering provisions

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3971296A (en) * 1974-09-18 1976-07-27 Kelor Limited Pneumatic actuators
US4034815A (en) * 1975-03-20 1977-07-12 Caterpillar Tractor Co. Blade lift float circuit for motor graders
US4147325A (en) * 1977-03-29 1979-04-03 Combustion Engineering, Inc. Hydraulic control assembly
US4337689A (en) * 1979-06-22 1982-07-06 Sulzer Brothers Limited Safety system for a double acting servomotor
WO1981000249A1 (en) * 1979-07-11 1981-02-05 J Muntjanoff Self adjusting actuator system
US4313633A (en) * 1979-07-11 1982-02-02 Caterpillar Tractor Co. Self adjusting actuator system
EP1209394A3 (de) * 2000-11-24 2003-08-06 Voith Turbo GmbH & Co. KG Elektrohydraulischer Stellantrieb
WO2017021080A1 (de) * 2015-07-31 2017-02-09 Voith Patent Gmbh Hydraulischer antrieb zum ausführen einer linearen bewegung
US10578227B2 (en) 2015-07-31 2020-03-03 Voith Patent Gmbh Hydraulic drive for executing a linear movement
CN111288044A (zh) * 2020-02-14 2020-06-16 三一汽车起重机械有限公司 液压系统和工程机械
CN113028077A (zh) * 2021-02-26 2021-06-25 重庆市江北嘴水源空调有限公司 一种江水取水用阀门
CN113028077B (zh) * 2021-02-26 2022-09-16 重庆市江北嘴水源空调有限公司 一种江水取水用阀门

Also Published As

Publication number Publication date
FR2090187B1 (de) 1975-07-04
GB1306786A (en) 1973-02-14
CA930283A (en) 1973-07-17
FR2090187A1 (de) 1972-01-14
FI57172C (fi) 1980-06-10
BE767456A (fr) 1971-11-22
FI57172B (fi) 1980-02-29

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