WO1998023474A1 - A hydraulic braking system - Google Patents
A hydraulic braking system Download PDFInfo
- Publication number
- WO1998023474A1 WO1998023474A1 PCT/DK1997/000532 DK9700532W WO9823474A1 WO 1998023474 A1 WO1998023474 A1 WO 1998023474A1 DK 9700532 W DK9700532 W DK 9700532W WO 9823474 A1 WO9823474 A1 WO 9823474A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- hydraulic
- pressure
- braking
- velocity
- prescribed
- Prior art date
Links
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000012530 fluid Substances 0.000 claims description 99
- 230000006870 function Effects 0.000 claims description 32
- 230000007423 decrease Effects 0.000 claims description 13
- 230000001133 acceleration Effects 0.000 claims description 11
- 230000001965 increasing effect Effects 0.000 claims description 11
- 230000001360 synchronised effect Effects 0.000 claims description 5
- 230000003247 decreasing effect Effects 0.000 claims description 4
- 230000000977 initiatory effect Effects 0.000 claims description 4
- 230000035945 sensitivity Effects 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 3
- 238000004321 preservation Methods 0.000 claims description 2
- 238000009499 grossing Methods 0.000 claims 2
- 230000011664 signaling Effects 0.000 claims 1
- 230000001276 controlling effect Effects 0.000 description 16
- 238000005259 measurement Methods 0.000 description 15
- 230000010355 oscillation Effects 0.000 description 11
- 230000005540 biological transmission Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 4
- 230000000254 damaging effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 230000003442 weekly effect Effects 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000036461 convulsion Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000008458 response to injury Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/66—Electrical control in fluid-pressure brake systems
- B60T13/68—Electrical control in fluid-pressure brake systems by electrically-controlled valves
- B60T13/686—Electrical control in fluid-pressure brake systems by electrically-controlled valves in hydraulic systems or parts thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
- B60T13/22—Brakes applied by springs or weights and released hydraulically
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D7/00—Controlling wind motors
- F03D7/02—Controlling wind motors the wind motors having rotation axis substantially parallel to the air flow entering the rotor
- F03D7/0244—Controlling wind motors the wind motors having rotation axis substantially parallel to the air flow entering the rotor for braking
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2260/00—Function
- F05B2260/90—Braking
- F05B2260/904—Braking using hydrodynamic forces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Definitions
- the hydraulic system according to the invention preferably further comprises a pressure relief valve limiting the pressure at the pressure side of the pump to a maximum threshold value defined by the relief valve, e.g., by a spring load.
- the position of at least one bu preferably both of the first and second switches can be activated by electrical signals.
- the method according to the invention may further comprise the steps of
- the eight time intervals are shorter than 1/40 of a second.
- the eight time intervals may, however, be even shorter.
- the control of the braking sequence is more accurate for the time intervals being as short as possible.
- the method according to the invention preferably further comprises the step of switching the second switch into its second position, when the velocity of the moving device exceeds a maximum threshold value .
- the method according to the invention further comprises the step of switching the second switch into its second position in any situation, where the first valve means may not be used for controlling the braking pressure.
- This situation may occur, e.g., when an error in the first valve means or in the components of the control system has been detected, or in an emergency situation, where the moving mechanical element or system has to be stopped.
- the invention further relates to a method for controlling at least two braking systems according to the invention, wherein each of the braking systems is controlled by a method according to the invention, the method comprising the steps of
- valve control means preferably comprise a processor means adapted to at each determination of the velocity:
- control system according to the invention may further comprise
- processor means for determining the desired pressure in the hydraulic fluid chamber at prescribed fifth time intervals from the determined acceleration or deceleration and from mechanical characteristics of the moving mechanical element or system and the hydraulic brake,
- control system according to the invention further comprises
- control system comprises processor means for switching the second switch into its second position in any emergency situation registered by the control system.
- An emergency situation may occur, e.g., when an error in the first valve means or in the control system has been detected.
- control system further comprises means for supervising the components of the control system, such that in case of an error being registered in the components of the control system, the braking pressure may only be increased by switching the second switch into its second position.
- the supervision of the components of the control system may, e.g., be performed electronically at regular time intervals, and may comprise checking of electric connections, power supply, electronic interfaces etc.
- the mechanical device to be braked is a rotor
- the device for measuring the velocity of the rotor is a revolution counter.
- the control system comprises standard state-of-the-art electronic components, such as a processor, memory circuits etc.
- the electronic components may be mounted on a print and electrically connected to the switches of the valve means and to the sensing devices, e.g., velocity measuring or pressure sensing devices.
- the control system may further comprise a power supply, preferably a uninterrupted power supply (UPS) , preferably connected to an emergency power chain.
- UPS uninterrupted power supply
- the control system is programmed for adapting the braking system to different applications, in particular different functions of the velocity of the moving mechanical device or system as a function of time may be programmed into the memory of the control system.
- the synchronization thereby obtained is useful for mechanical systems, e.g., conveyor systems, comprising a number of braking systems according to the invention.
- Fig. 1 is a schematic diagram of the preferred embodiment of the hydraulic part of the braking system
- Fig. 2 is a table showing an example of equivalent brake torque related to nominal torque, braking time, partial damage per braking sequence, max. braking number before damage and lifetime in years by two weekly braking sequences,
- Fig. 3 is a graph showing an example of braking torque influence on gearbox lifetime for wind turbines
- Fig. 6 is a graph showing an example of the relative torque as a function of time for a "hard” braking sequence, using a prior art braking system
- Fig. 7 is a graph showing an example of the relative torque as a function of time for a throttled braking sequence, using a prior art braking system
- Fig. 9 is a graph showing an example of the relative torque and rpm as a function of time for a "hard" braking sequence, using a prior art braking system.
- a preferred embodiment of the hydraulic unit of the braking system is shown in fig. 1.
- the system comprises a hydraulic brake mechanism 2 with a hydraulic fluid chamber 3.
- the main components of the preferred embodiment of the braking system are shown in fig. 4.
- the hydraulic unit 1 is hydraulically connected to the hydraulic chamber 3 of the mechanical brake 2 and electrically connected to a braking controller.
- the braking controller is connected to a main controller of a moving machine, e.g., a wind turbine or a conveyer system in which the braking system of the preferred embodiment is used.
- a Soft Braking Controller (SBC) is the key control link. Communication with the main controller is made with simple on/off signals normally used for hydraulic valves, allowing the present system to be used with existing braking systems.
- the main controller preferably comprises a surveillance option for overspeed and selftest of the SBC.
- the control parameter used in a simple version of the SBC is the rpm of the brake disk or attached parts, monitored through an appropriate sensor, e.g., an inductive tacho transducer.
- an appropriate sensor e.g., an inductive tacho transducer.
- the rotating parts may be equipped with pulse magnets.
- the pressure in the hydraulic chamber 3 of the brake mechanism 2 is used as a control parameter.
- the brake 2 is constituted by a negative braking mechanism as shown in figure 1.
- the braking mechanism will brake the machine (not shown) to be braked, when a predefined pressure exerted on the fluid of the hydraulic fluid chamber 3 by a predefined load, e.g. a spring load, of the braking mechanism is greater than the hydraulic pressure in the hydraulic fluid chamber 3.
- the braking mechanism will brake the machine to be braked, when the hydraulic pressure in the hydraulic fluid chamber is greater than a predefined pressure exerted on the fluid of the hydraulic fluid chamber by a predefined load, e.g. a spring load, of the braking system.
- a predefined load e.g. a spring load
- each of the on/off valves 5 and 6 is constituted by a three-way valve.
- Other types of valves are possible, e.g. two synchronized two-way valves, substituting one three-way valve.
- a hydraulic accumulator 9 is positioned between the first valve 5 and the second valve 6 and is used to increase the displaced oil volume to or from the chamber 3, thereby reducing the sensitivity of the first and second valves 5 and 6 to conditions and the quality of the hydraulic fluid. Further, the hydraulic accumulator 9 smooths pressure variations that may exist in the hydraulic system. In an alternative preferred embodiment, the braking pressure is controlled by the pressure in the chamber 3 so as to obtain a controlled, smooth braking sequence. The control system stores a function of velocity as a function of time.
- the valve 6 When the brake is activated, the valve 6 will then be switched to its off-position by the control system, the brake system thereby performing a hard, uncontrolled braking.
- the preferred embodiment of the braking system according to the invention allows a hard, uncontrolled braking in case the electronic watch system registers an error in the electronic components of the control system.
- the source of hydraulic fluid comprises a fluid container 12, a pump 10 and a power supply 11 for supplying power to the pump 10.
- the pump 10 At its suction side, the pump 10 is connected to the fluid container 12, and at its pressure side it is connected to the first valve 5.
- the fluid container 12 may be equipped with hydraulic standard equipment, such as a tank meter 13, a back- flow filter unit 14 comprising a filter 14a and a back valve 14b and a refill unit 15 comprising a filter 16.
- the pressure of the hydraulic fluid in the container 12 is lower than the pressure at the pressure side of the pump 10 and preferably equal to ambient pressure.
- the pressure may be limited to a maximum threshold value by a pressure relief valve 19.
- the hydraulic system 1 may further comprise a manometric switch 20 for sensing pressure in the hydraulic system at the pressure side of the pump 10 and switching the pump 10 on, when the pressure is lower than a prescribed minimum threshold value, and for switching the pump 10 off, when the pressure is greater than a prescribed maximum threshold value .
- a manometric switch 20 for sensing pressure in the hydraulic system at the pressure side of the pump 10 and switching the pump 10 on, when the pressure is lower than a prescribed minimum threshold value, and for switching the pump 10 off, when the pressure is greater than a prescribed maximum threshold value .
- the hydraulic system 1 may further comprise a throttling valve 18 and a back valve 17 at the pressure side of the pump and a two-way throttling valve 21.
- the throttling valve 18 smooths pressure variations and sudden pressure jerks on the pressure side of the pump 10 generated by the pump 10 when in operation.
- the back valve 17 will be shut, thereby preventing hydraulic fluid from flowing back to the pump 10, and thereby preserving the hydraulic pressure in the hydraulic chamber 3, when the valves 5 and 6 are in their open positions.
- the two-way throttling valve 21 is constituted by an on/off valve. During running of the hydraulic system 1, the valve 21 will be closed. The pressure in the hydraulic system may be relieved by opening the valve 21. The pressure in the hydraulic system 1 may further be relieved by manually switching the switch of the valve 5 to its off-position.
- the hydraulic system may further comprise a valve 22 at the interconnection between the braking mechanism 2 and the hydraulic system for manually interrupting the hydraulic interconnection to the hydraulic chamber 3.
- a back valve 23 may be mounted between the hydraulic system 1 and the surroundings so as to mount, e.g., a manometer or any other measuring device. The back valve 23 further allows the pressure in the hydraulic system 1 to be relieved manually.
- Example 1 generally concerns gearbox damage in a wind turbine and gear box life time in relation to the number of braking sequences
- Example 2 concerns torque measurements on a wind turbine using different braking systems, including a braking system according to the invention.
- Example 1 Gear box damage and life time
- an equivalent braking torque can be calculated from the braking torque sequence.
- This equivalent torque is the mean 'fatigue' torque that the teeth in the gearbox will experience during the braking sequence, taking into consideration that the damage response for steel is logarithmic.
- An emergency braking sequence for a wind turbine will often give an equivalent torque of 2.5 times the nominal torque.
- Fig. 2 shows the lifetime in years as calculated known formulae for different equivalent torques considering 2 weekly braking sequences (the nominal lifetime is used when accumulated partial damage is 1.0) .
- this is shown for varying numbers of braking sequences (operational loads are not included in the lifetime calculations and the equivalent braking torque is typically 20-40% larger than the nominal braking torque) .
- Fig. 2 and fig. 3 clearly illustrate that the gear box life time is determined by the equivalent brake torque and by the number of braking sequences if the braking torque is high.
- Example 2 Wind turbine testing
- the most important parameters to the lifetime of the gearbox is the maximum braking span after the brake has blocked, since the same teeth on the gear wheels are loaded on both sides, and the maximum braking torque.
- Fig. 6 shows that a hard braking sequence results in a relative torque of approximately 0.4 during a period of approximately 7 seconds from the moment, when the braking sequence is started, followed by a period of approximately 6 seconds, where the relative torque rises to approximately 2.7.
- the relative torque performs damped oscillations, where the relative torque still reaches 0.8 after a time period of 30 seconds of the braking sequence .
- the hard braking sequence shows large torque oscillations with an amplitude of up to 3. This measurement clearly illustrates the damaging effect of a hard braking sequence on the transmission system (cf . example 1 above) .
- a braking sequence for a throttled braking sequence using a prior art braking system, is shown.
- the relative torque of the throttled braking sequence varies slightly between 0.5 and 0.8 during a time period of approximately 17 seconds from the moment, when the braking sequence is started, followed by a period of approximately 12 seconds, where the relative torque is close to zero.
- the relative torque then rises from zero to 1 with a dynamic peak of approximately 2.3, after which the relative torque performs damped oscillations during the remaining part of the braking sequence, the amplitude of the oscillations varying from approximately 1 down to approximately 0.25, the torque still oscillates after 60 seconds.
- the throttled braking sequence reduces the magnitude of the relative torque during most of the " braking sequence compared to the hard braking of fig. 6, the amplitude of the oscillations is still very high, resulting in reduced life time of the transmission system.
- the torque for a braking sequence using a braking system according to the invention is shown in fig. 8.
- the relative torque is almost constant at a value of approximately 0.2, followed by a period of approximately 20 seconds, where the relative torque is close to zero with very small variations.
- the oscillations following this period have an amplitude of only 0.8 at the most, and after 45 seconds of braking and during the remaining part of the braking sequence, the oscillations have an amplitude of less than 0.2.
- the braking sequence does not imply a relative braking torque greater than 1 at any point, the life time of the transmission system is not reduced by the braking sequence, which is not the case for any of the prior art braking systems used for the measurements of figs. 6 and 7.
- the relative braking torque is 0.8 at the most when using a braking system according to the invention, the limit of 1 is even kept with a considerable margin.
- Fig. 9 repeats the relative torque curve (upper trace) of fig. 6 and shows the rpm (lower trace) as a function of time for a 'hard' braking sequence using a prior art braking system.
- the rpm drops almost instantaneously from 1000 rpm to zero, when the braking torque increases after approximately 7 seconds of braking.
- the torque of figure 7 is repeated as absolute torque (upper trace) , and the rpm (lower trace) as a function of time is shown as well.
- the measurements were performed on a prior art throttled braking system. Due to an error in the measurement system, the curve of rpm drops to zero between approximately 14 and 17 seconds of braking. As it can be seen, the rpm decreases approximately linearly from the 17th to 29th second of braking, and again linearly, but with a greater slope, from the 31st to the 34th second of braking.
- the effect of using a throttled braking system is illustrated clearly by the curve of rpm, but as for the hard braking sequence, the torque shows large oscillations after the rotor has been stopped.
- the torque curve of fig. 8 is repeated (upper trace) , and the rpm (lower trace) as a function of time is shown.
- the curves were obtained by measurements performed when using a braking system according to the invention. Due to an error in the measurement system, the curve of the rpm shows oscillations between the 32nd and 35th second of the braking sequence. Apart from this error in the measurement system, the rpm curve follows the prescribed curve, that in this case was an approximation of a logarithmic function. The effect of using a braking system according to the invention and the effect of prescribing the rpm as a function of time is clearly seen from the torque curve. Other functions of the velocity are possible, and may easily be programmed into the memory of the control system according to the invention.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU50483/98A AU729248B2 (en) | 1996-11-22 | 1997-11-20 | A hydraulic braking system |
US09/308,588 US6254197B1 (en) | 1996-11-22 | 1997-11-20 | Hydraulic braking system |
EP97913119A EP0939712A1 (en) | 1996-11-22 | 1997-11-20 | A hydraulic braking system |
CA002272489A CA2272489A1 (en) | 1996-11-22 | 1997-11-20 | A hydraulic braking system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DK133796 | 1996-11-22 | ||
DK1337/96 | 1996-11-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998023474A1 true WO1998023474A1 (en) | 1998-06-04 |
Family
ID=8103738
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/DK1997/000532 WO1998023474A1 (en) | 1996-11-22 | 1997-11-20 | A hydraulic braking system |
Country Status (5)
Country | Link |
---|---|
US (1) | US6254197B1 (en) |
EP (1) | EP0939712A1 (en) |
AU (1) | AU729248B2 (en) |
CA (1) | CA2272489A1 (en) |
WO (1) | WO1998023474A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0909690A2 (en) * | 1997-10-17 | 1999-04-21 | Deere & Company | Brake system and vehicle |
EP2284390A1 (en) * | 2009-07-10 | 2011-02-16 | Vestas Wind Systems A/S | Hydraulic station and method for controlling pressure in a hydraulic system of a wind turbine |
CN102116260A (en) * | 2009-12-30 | 2011-07-06 | 通用电气公司 | Methods and systems for providing variable mechanical brake torque |
US8123304B2 (en) | 2009-06-16 | 2012-02-28 | Vestas Wind Systems A/S | Hydraulic system and method for operating a brake of a wind turbine |
WO2013075721A3 (en) * | 2011-11-24 | 2013-07-25 | Vestas Wind Systems A/S | A yawing system comprising a preload mechanism |
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WO2003080414A1 (en) * | 2002-03-23 | 2003-10-02 | General Electric Company | Hydraulic brake system for a wind energy plant |
EP1490250B1 (en) * | 2002-03-23 | 2010-07-07 | General Electric Company | Hydraulic brake system for a wind energy plant |
DE10320580A1 (en) * | 2003-05-07 | 2004-11-25 | Bosch Rexroth Ag | Braking device for a wind power plant with a rotor converting the wind energy into a rotary movement and method for operating such a braking device |
JP4280656B2 (en) * | 2003-06-20 | 2009-06-17 | キヤノン株式会社 | Image display device and image display method thereof |
US20050006950A1 (en) * | 2003-07-07 | 2005-01-13 | Versteyhe Mark Rj | Method and apparatus for a vehicle braking system |
ITBO20060714A1 (en) * | 2006-10-16 | 2008-04-17 | Cnh Italia Spa | PARKING BRAKE, IN PARTICULAR FOR AN AGRICULTURAL TRACTOR, EQUIPPED WITH A SAFETY DEVICE |
DE102007002137A1 (en) * | 2007-01-10 | 2008-07-17 | Nordex Energy Gmbh | Wind energy plant with a hydraulically actuated rotor brake |
DE102007002136B4 (en) * | 2007-01-10 | 2010-02-18 | Nordex Energy Gmbh | Wind energy plant with a hydraulically actuated rotor brake and method for hydraulic control of a rotor brake |
WO2009126696A1 (en) * | 2008-04-08 | 2009-10-15 | Ufo Wind Llc | Wind-driven generation of power |
ATE552421T1 (en) * | 2008-05-14 | 2012-04-15 | Alstom Wind Sl | METHOD FOR REDUCING TORSIONAL VIBRATIONS IN THE DRIVE TRAIN OF A WIND TURBINE |
DE102009006054A1 (en) | 2009-01-24 | 2010-07-29 | Robert Bosch Gmbh | Stationary power generation plant with a deceleration device |
US8269367B2 (en) * | 2010-01-13 | 2012-09-18 | Hiwin Mikrosystem Corp. | Shaft brake mechanism of wind power generator |
DE102010041824B3 (en) * | 2010-09-30 | 2012-03-08 | Repower Systems Se | Hydraulic braking device for a wind energy plant |
US8491262B2 (en) | 2011-10-27 | 2013-07-23 | General Electric Company | Method for shut down of a wind turbine having rotor blades with fail-safe air brakes |
CN102493916B (en) * | 2011-12-19 | 2013-09-18 | 湘电风能有限公司 | Off-course hydraulic braking device of wind generating set |
DE102012107812A1 (en) * | 2012-08-24 | 2014-05-28 | Krones Ag | Apparatus and method for treating containers with a mechanical braking device |
DE102012222637A1 (en) * | 2012-12-10 | 2014-06-12 | Senvion Se | Turn drive for a wind turbine and method for rotating the rotor shaft of a wind turbine |
US9267491B2 (en) | 2013-07-02 | 2016-02-23 | General Electric Company | Wind turbine rotor blade having a spoiler |
US9790922B2 (en) * | 2013-07-04 | 2017-10-17 | Orenda Energy Solutions Inc. | Overrun protection for wind turbines |
CN104074841B (en) * | 2014-07-16 | 2016-06-08 | 上海豪高机电科技有限公司 | Digital valve pilot system |
GB2538750B (en) * | 2015-05-27 | 2020-08-12 | Ecotricity Group Ltd | Method of determining a wind speed and a braking torque of a wind turbine |
EP3104001B1 (en) * | 2015-06-11 | 2018-02-28 | Nordex Energy GmbH | Rotor brake for a wind turbine |
US10343684B2 (en) | 2016-03-30 | 2019-07-09 | Toyota Motor Engineering & Manufacturing North America, Inc. | Systems and methods for smooth stopping of a vehicle |
EP3633188B1 (en) * | 2018-10-02 | 2021-07-14 | Siemens Gamesa Renewable Energy A/S | Variable flow hydraulic circuit for a wind turbine |
GB2591725A (en) * | 2019-11-26 | 2021-08-11 | Bamford Excavators Ltd | Hydraulic system |
US11480153B2 (en) | 2020-05-21 | 2022-10-25 | General Electric Company | System and method for controlling a wind turbine to protect the wind turbine from anomalous operations |
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US5630489A (en) * | 1995-11-29 | 1997-05-20 | Deere & Company | Electrohydraulic parking brake control system for preventing brake engagement when vehicle is in motion |
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JPS56165696A (en) | 1980-05-26 | 1981-12-19 | Komatsu Mfg Co Ltd | Brake gear for oil pressure type crane winch |
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1997
- 1997-11-20 US US09/308,588 patent/US6254197B1/en not_active Expired - Fee Related
- 1997-11-20 CA CA002272489A patent/CA2272489A1/en not_active Abandoned
- 1997-11-20 AU AU50483/98A patent/AU729248B2/en not_active Revoked
- 1997-11-20 WO PCT/DK1997/000532 patent/WO1998023474A1/en not_active Application Discontinuation
- 1997-11-20 EP EP97913119A patent/EP0939712A1/en not_active Withdrawn
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US3990352A (en) | 1974-10-11 | 1976-11-09 | Kabushiki Kaisha Komatsu Seisakusho | Control valve |
US4458791A (en) * | 1982-07-12 | 1984-07-10 | Caterpillar Tractor Co. | Brake control system with metering pump relief |
US4664247A (en) * | 1984-04-30 | 1987-05-12 | Westinghouse Electric Corp. | Conveyor brake control |
US5052532A (en) * | 1990-05-29 | 1991-10-01 | Trak International, Inc. | Vehicle brake system |
US5203616A (en) * | 1992-01-21 | 1993-04-20 | Deere & Company | Electrohydraulic parking brake control system |
US5630489A (en) * | 1995-11-29 | 1997-05-20 | Deere & Company | Electrohydraulic parking brake control system for preventing brake engagement when vehicle is in motion |
US5611199A (en) * | 1995-12-13 | 1997-03-18 | Caterpillar Inc. | Two stage electrohydraulic pressure control valve |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
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EP0909690A2 (en) * | 1997-10-17 | 1999-04-21 | Deere & Company | Brake system and vehicle |
EP0909690A3 (en) * | 1997-10-17 | 2000-04-12 | Deere & Company | Brake system and vehicle |
US8123304B2 (en) | 2009-06-16 | 2012-02-28 | Vestas Wind Systems A/S | Hydraulic system and method for operating a brake of a wind turbine |
EP2284390A1 (en) * | 2009-07-10 | 2011-02-16 | Vestas Wind Systems A/S | Hydraulic station and method for controlling pressure in a hydraulic system of a wind turbine |
US7997074B2 (en) | 2009-07-10 | 2011-08-16 | Vestas Wind Systems A/S | Hydraulic station and method for controlling pressure in a hydraulic system of a wind turbine |
CN102116260A (en) * | 2009-12-30 | 2011-07-06 | 通用电气公司 | Methods and systems for providing variable mechanical brake torque |
EP2341244A3 (en) * | 2009-12-30 | 2014-01-01 | General Electric Company | Brake system for a wind turbine drive train |
CN102116260B (en) * | 2009-12-30 | 2015-01-28 | 通用电气公司 | Methods and systems for providing variable mechanical brake torque |
WO2013075721A3 (en) * | 2011-11-24 | 2013-07-25 | Vestas Wind Systems A/S | A yawing system comprising a preload mechanism |
CN104093972A (en) * | 2011-11-24 | 2014-10-08 | 维斯塔斯风力系统有限公司 | A yawing system comprising a preload mechanism |
CN104093972B (en) * | 2011-11-24 | 2016-11-02 | 维斯塔斯风力系统有限公司 | Yaw system including pre-load mechanism |
US9551319B2 (en) | 2011-11-24 | 2017-01-24 | Vestas Wind Systems A/S | Yawing system comprising a preload mechanism |
Also Published As
Publication number | Publication date |
---|---|
EP0939712A1 (en) | 1999-09-08 |
US6254197B1 (en) | 2001-07-03 |
AU5048398A (en) | 1998-06-22 |
CA2272489A1 (en) | 1998-06-04 |
AU729248B2 (en) | 2001-01-25 |
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