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
  • F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
  • F15B20/002—Electrical failure
• • 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

Definitions

• the invention relates to a safety circuit for controlling a hydraulic drive with a drive part which can be moved in at least two different directions of travel and which can be controlled by a control circuit for any method.
• Such hydraulic drives can be formed, for example, from a hydraulic differential or synchronous cylinder, the working pistons of which execute feed movements as drive parts, for example in order to control a steam control valve or to design it itself.
• the fluid or oil supply generally takes place via pressure accumulators, with separately arranged safety pressure accumulators being used depending on the requirements.
• the steam valve can be moved to any valve position.
• the steam control valve can be designed as a shut-off and control valve with quick opening or quick closing priority and as a so-called safety valve with quick opening priority.
• the object of the invention is to create a safety circuit for controlling a hydraulic drive which is not susceptible to faults. This object is achieved by a safety circuit with the features of claim 1.
• a safety circuit is implemented which fulfills the required safety function with absolute certainty even in the event of a power failure .
• the highest priority provided in emergency operation for example in the form of the defined closing or opening of a steam control valve, is certainly fulfilled and the otherwise usual control process is switched off in a defined manner via the control circuit.
• the application of the safety circuit according to the invention need not be limited to steam control valves, in particular in the power plant sector, but can be used wherever it must be guaranteed in any case that a hydraulic switching function is established in a defined manner, regardless of the remaining system status of the hydraulic circuit and its control elements.
• the malfunctions, at any rate observed in the known electrical control system, due to failures or switching errors are certainly ruled out in the hydraulic coupling.
• the switching device according to the invention is explained in more detail below on the basis of a circuit diagram, a function table being shown at the top left when viewed in the direction of the figure.
• the safety circuit is used to control a hydraulic drive 10, which is formed from an actuating cylinder, with a double-acting piston as the drive part 12, which can be moved back and forth on both sides, in particular when looking at the circuit, and has piston rods 14 which can be moved alternately up and down .
• the hydraulic drive (actuating cylinder) 10 designed as a steam actuating valve, can change free pipe opening cross sections (not shown), completely release or close them, or the piston rods 14 mentioned can in turn act on further actuating valves (not shown).
• the possible directions of travel of the drive part (piston) 12 are shown in the circuit with arrows and provided with the words "retract" and "extend".
• the actuating cylinder 10 can be connected to a hydraulic pump P 'and the tank T' via corresponding fluid-carrying connecting lines.
• the piston 1 2 moves with its two piston rods 14 as seen in the direction of the circuit diagram downwards or upwards.
• the actuating cylinder 10 is connected to a hydraulic control block designated as a whole by 1 6, as are the hydraulic pump P 'and the tank T'.
• the corresponding connecting lines can be provided with adjustable throttles 18.
• adjustable throttles 18 For the sake of better illustration, not all of the fluid-carrying connecting lines running in the control block 16 are drawn with solid lines. Rather, the dotted and broken lines represent possible fluid-carrying connections.
• the mentioned regulation is carried out by a 3-point step controller, but can also be done by a pure pulse control or by a completely continuous regulation.
• a proportional or servo valve is used instead of the slide valve shown.
• the 4/3-way valve MV3 is connected on the output side with its two connections A, B to a first switching valve (cartridge valve) LERA and LERB.
• cartridge valves and the switching valves described below are cartridge valves, always open when there is no fluid pressure at their respective control port X, ie the control port X has been depressurized.
• the two control connections X of the first switching valves LERA and LERB are connected via the shuttle valve W3 to the fluid-carrying output A of a first safety switching part (solenoid valve) MV1 of the safety circuit in the form of a 4/2 way valve which can be excited via the assigned magnet Y1.
• a connecting line leads from the change-over valve W3 to the fluid-carrying output B of a second safety switching part (solenoid valve) MV2 in the form of a 4/2-way valve which can be controlled via the magnet Y2.
• the two solenoid valves MV1 and MV2 are shown in their de-energized, i.e. de-energized position in the circuit diagram.
• the solenoid Y1 controls the solenoid valve MV1
• it is energized and assumes its left switching position as seen in the direction of the circuit diagram.
• the supply line to the shuttle valve W3 is thus switched to the tank T and is therefore depressurized and the two control connections X of the cartridge valves LERA and LERB are also depressurized, with the result that the cartridge valves mentioned open.
• the actuating cylinder 10 is retracted or extended.
• the relevant control results from the overview table arranged above the circuit diagram.
• a defined or quick closing process should be provided for the actuating cylinder 10.
• This function with top priority is carried out via the two second switching valves (cartridge valves) LEPA and LETB.
• LETB connects the chamber B of the cylinder with the tank connection T of the control, whereas LEPA connects the chamber A with the pressure-carrying connection P of the control with the result that the piston 1 2 extends completely.
• the cartridge valves are actuated by the first safety switching part MV1.
• the two control connections X of the cartridge valves LEPA and LETB are depressurized so that the cartridge valves LEPA and LETB can open to actuate the actuating cylinder 10.
• the two tax Connections X of the first switching valves LERA and LERB are now pressurized via the shuttle valve W3, with the result that the first switching valves LERA and LERB remain closed and the control function is bridged.
• the relevant locking security function is again shown in the overview table, the magnet Y1 remaining currentless.
• the other shuttle valves W1 and W2 are also actuated, which are connected in the fluid-carrying connection between the shuttle valve W3 and the solenoid valve MV1, with the result that the two control connections X of the third switching valves (Car ⁇ tridge valves) LETA and LEPB also remain closed, since the pump pressure is present in them.
• the hydraulically superimposed safety function is set independently of the other switching state of control block 1 6, that is to say regardless of the excitation state of the other magnets Y2, Y3 and Y4.
• Another switching function "quick opening" that can be achieved with the safety circuit is carried out by activating the second safety switching part MV2.
• This function is enabled by energizing solenoid Y1 of solenoid valve MV1.
• solenoid Y2 of solenoid valve MV2 the assigned control connections X of the cartridge valves LETA and LEPB are relieved and thus depressurized.
• the cartridge valve LETA can then connect the chamber A of the cylinder to the tank connection of the control and the cartridge valve LEPB connects the chamber B of the actuating cylinder 10 to the connection P of the control.
• the shuttle valves W1 and W2 are depressurized via the port A of the solenoid valve MV1 to the tank T ', so that the depressurized control ports X of the cartridge valves LETA and LEPB cause them to open, with the result that the port B of the actuating cylinder 10 is connected to the Hydraulic pump P 'is connected and the connection A to the tank T'.
• a quick opening process can therefore be triggered as soon as the magnets Y1, Y2 are energized and bring the associated solenoid valves MV1 or MV2 into their left switching position as seen in the direction of the circuit diagram.
• an opening process can also be triggered as a safety function in the reverse sense. Even in this case, the usual regulation and closing function would then be superimposed by this highest priority with safe execution.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Fluid-Pressure Circuits (AREA)
• Air Bags (AREA)
• Cookers (AREA)
• Control Of Combustion (AREA)
• Mechanical Operated Clutches (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (1)

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Citations (6)

• 1996
  • 1996-04-06 DE DE19613848A patent/DE19613848C2/de not_active Expired - Fee Related
• 1997
  • 1997-01-17 WO PCT/EP1997/000189 patent/WO1997038228A1/de active IP Right Grant
  • 1997-01-17 JP JP9535773A patent/JP2000508409A/ja active Pending
  • 1997-01-17 DE DE59707427T patent/DE59707427D1/de not_active Expired - Fee Related
  • 1997-01-17 AT AT97901050T patent/ATE218677T1/de not_active IP Right Cessation
  • 1997-01-17 EP EP97901050A patent/EP0890030B1/de not_active Expired - Lifetime
  • 1997-01-17 CZ CZ982593A patent/CZ259398A3/cs unknown
  • 1997-01-17 SK SK1368-98A patent/SK136898A3/sk unknown
  • 1997-01-17 DK DK97901050T patent/DK0890030T3/da active

Patent Citations (6)

Non-Patent Citations (3)

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