Hydraulic System Patents (Class 123/90.12)
  • Patent number: 6332438
    Abstract: A vane-type variable valve timing control apparatus, wherein in a feedback control for bringing a rotation phase between a crank shaft and a cam shaft into agreement with a target value, a feedback gain is changed over according to a target rotation phase and a direction in which the rotation phase is changed.
    Type: Grant
    Filed: October 4, 2000
    Date of Patent: December 25, 2001
    Assignee: Unisia Jecs Corporation
    Inventor: Kenichi Machida
  • Patent number: 6330870
    Abstract: A variable valve timing adjuster with an intermediate lock mechanism learns a lock position and a lock release control. During a lock control, a learning of the lock position from a real camshaft phase is repeated to update the learned value, and the learning is ended when it is judged that the learned values have converged. At this time, when the learned values of the lock position do not converge even if the number of learning of the lock position exceeds a predetermined value, an insufficient lock state is judged, and the learned value of the lock position is set to an initial value or the learned value at the previous lock control thereby to make a lock release control. During the lock release control, on the other hand, the control (or the lock release control) of a hydraulic control valve is learned. When the lock cannot be released during the lock release control, the lock release control (or the learned value) is corrected in a direction to facilitate the lock release.
    Type: Grant
    Filed: August 16, 2000
    Date of Patent: December 18, 2001
    Assignee: Denso Corporation
    Inventors: Masaomi Inoue, Osamu Sato, Michio Adachi
  • Patent number: 6325028
    Abstract: In an internal combustion engine having a hydraulic system for valve variable actuation and a hydraulic braking device for slowing down the valve during the final portion of its closing travel, this hydraulic braking device is arranged so as to be substantially insensitive to variations in viscosity of the fluid resulting from variations of the temperature.
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: December 4, 2001
    Assignee: C.R.F. Societa Consortile per Azioni
    Inventors: Stefano Albanello, Lorentino Macor, Francesco Vattaneo
  • Patent number: 6321703
    Abstract: A device for controlling a gas exchange valve for internal combustion engines, having a housing including an axially movable valve member, which on an end close to the combustion chamber, has a valve sealing face that cooperates with a valve seat affixed to the housing and on an end remote from the combustion chamber, has a piston that axially separates upper and lower hydraulic working chambers from each other. The lower working chamber closer to the combustion chamber acts on the valve member in the closing direction and the upper working chamber further from the combustion chamber acts on the valve member in the opening direction. The lower working chamber continuously communicates with a high pressure source and the upper working chamber can be alternatingly filled with high pressure by way of a high pressure supply line containing an electric control valve. The upper working chamber is discharged by way of a discharge line that contains an electric control valve.
    Type: Grant
    Filed: February 14, 2000
    Date of Patent: November 27, 2001
    Assignee: Robert Bosch GmbH
    Inventors: Udo Diehl, Karsten Mischker, Rainer Walter, Stefan Franzl, Volker Beuche, Stefan Reimer
  • Patent number: 6321701
    Abstract: A lost motion valve actuation system for an internal combustion engine is disclosed. The system includes a motion feedback system (100) for detecting the motion and timing of a valve actuator (130) and an engine valve (140). By providing information on the condition of the engine during operation, the motion feedback system (100) permits adjustment of the valve actuation system that can optimize operation or prevent engine damage. The motion feedback system may be used in a common rail or a lost motion valve actuation system. In alternate embodiments, the valve actuation system includes an accumulator (300) with an accumulator piston (310) whose motion is limited by an accumulator stop (330) or a control valve (200). The limited accumulator (300) controls the amount of lost motion in the valve actuation system to provide fail-safe operation in the event of electrical failure.
    Type: Grant
    Filed: November 4, 1998
    Date of Patent: November 27, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventors: Joseph M. Vorih, James F. Egan, III
  • Patent number: 6321706
    Abstract: A valve assembly having a valve (10, 110, 210, 310, 410) that is caused to reciprocate between open and closed positions by engagement of a cam follower (16, 116, 216, 316,416) with a cam (14, 114, 214, 314, 414) that is carried by a rotatable camshaft (12, 112, 212, 312, 412). The valve is resiliently urged against the cam by a coil spring (18, 118, 218, 318, 418), but its return to its closed position is delayed by application of a non-mechanical force against the valve, in opposition to the force imposed by the coil spring, by hydraulic force imposed by hydraulic fluid in a housing (22, 122, 322, 422) that acts against an enlarged portion (10c, 110c, 310c, 410c) of the valve, or by an electromagnetic force imposed by an electromagnetic device (228) that acts on an enlarged portion (210c) of the valve (210).
    Type: Grant
    Filed: August 10, 2000
    Date of Patent: November 27, 2001
    Assignee: BorgWarner Inc.
    Inventor: Braman C. Wing
  • Patent number: 6321702
    Abstract: A system for controlling a gas exchange valve for internal combustion engines, comprising a movable valve member in a housing which, on an end close to the combustion chamber, has a valve sealing face that cooperate with a valve seat in order to control an inlet or outlet cross section at the combustion chamber of the engine. On an end remote from the combustion chamber a working piston defines at least one hydraulic working chamber, whose alternating filling and discharging with a pressure fluid can be used to move the valve member in the opening and closing direction. The supply pressure of the pressure fluid supplied for the actuation of the gas exchange valve member is adjusted step wise as a function of current operating parameters of the engine.
    Type: Grant
    Filed: May 11, 2000
    Date of Patent: November 27, 2001
    Assignee: Robert Bosch GmbH
    Inventors: Udo Diehl, Karsten Mischker, Rainer Walter, Stefan Franzl, Volker Beuche, Stefan Reimer
  • Patent number: 6314926
    Abstract: A valve control apparatus is provided for an internal combustion engine having a valve and a camshaft. The camshaft has an axis of rotation, a first lobe and a second lobe adjacent to the first lobe. The second lobe is angularly spaced-apart about the axis from the first lobe. The apparatus includes a follower operatively engagable with the camshaft and the valve. The follower has a first operational mode where the first lobe operatively engages the follower on each revolution of the camshaft to open the valve a first time on each revolution. There is a mechanism for selectively putting the follower in a second operational mode where the second lobe operatively engages the follower to open the valve a second time on each revolution of the camshaft. The mechanism puts the follower in the second operational mode on each revolution of the camshaft before the second lobe is fully aligned with the follower.
    Type: Grant
    Filed: May 24, 1999
    Date of Patent: November 13, 2001
    Assignee: Jenera Enterprises Ltd
    Inventors: Vincent A. Meneely, Robert B. Price
  • Patent number: 6315265
    Abstract: The invention involves a variable valve timing actuator that allows the opening and closing of engine valves to be variably and individually controlled without using a camshaft. The invention utilizes energy regeneration so energy delivered to a valve while accelerating it is recovered while it is decelerating. Regeneration is preferably provided by potential energy storage devices such as springs. Energy losses are made up by adding energy to the actuator while the valve is stationary (or nearly so) in an open or closed state. This is done by (1) moving the spring seats in relation to the valve, thereby “charging” the springs in relation to the valve, and/or by (2) moving the valve with respect to the spring seats to “charge” the springs with respect to the valve. This energy addition is extremely efficient because it is performed after the potential energy within the springs has already been expended and the valve is sitting stationary in its open and closed positions.
    Type: Grant
    Filed: April 13, 2000
    Date of Patent: November 13, 2001
    Assignee: Wisconsin Alumni Research Foundation
    Inventors: Scott Peter Adler, Norman Henry Beachley, Frank John Fronczak, Ahmad Mohammad Sabri
  • Patent number: 6308690
    Abstract: An internal combustion engine that contains a controller which controls different components such as a fuel injector, an exhaust valve and a by-pass valve of a pump with digital control signals. The engine may have an hydraulically driven fuel injector which ejects a volume of fuel into an internal combustion chamber. The flow of air into the internal combustion chamber and the flow of exhaust gas out of the chamber may be controlled by camless hydraulically driven intake and exhaust valves. The hydraulic actuation of the fuel injector and valves are controlled by solenoid actuated latching fluid control valves. The operation of the injector and the valves is controlled by a controller which provides digital signals to actuate and latch the solenoid control valves. The digital signals consume minimal power and actuate the valves at relatively high speeds. The engine further contains a pump that pumps the hydraulic fluid to the control valves.
    Type: Grant
    Filed: September 11, 1996
    Date of Patent: October 30, 2001
    Assignee: Sturman Industries, Inc.
    Inventor: Oded E. Sturman
  • Patent number: 6308673
    Abstract: In an internal combustion engine having a hydraulic valve characteristic control mechanism for altering phase of a cam driving a suction valve and an oil pressure control valve for controlling pressure of working oil supplied to the valve characteristic control mechanism, a chain chamber comprising a case formed by an engine main body and a cover closing the case. The oil pressure control valve is attached to the engine main body surrounded by a timing chain. In order to position the oil pressure control valve outside of the chain chamber, the cover has an opening for inserting the oil pressure control valve and the case has an attachment section around the oil pressure control valve to which a whole marginal edge of the opening is touched in liquid-tight and fixed.
    Type: Grant
    Filed: July 17, 2000
    Date of Patent: October 30, 2001
    Assignee: Honda Giken Kogyo Kabushiki Kaisha
    Inventor: Tosihiki Kobayashi
  • Publication number: 20010023671
    Abstract: A lost motion engine valve actuation system and method of actuating an engine valve are disclosed. The system may comprise a valve train element, a pivoting lever, a control piston, and a hydraulic circuit. The pivoting lever may include a first end for contacting the control piston, a second end for transmitting motion to a valve stem and a means for contacting a valve train element. The amount of lost motion provided by the system may be selected by varying the position of the control piston relative to the pivoting lever. Variation of the control piston position may be carried out by placing the control piston in hydraulic communication with a control trigger valve and one or more accumulators. Actuation of the trigger valve releases hydraulic fluid allowing for adjustment of the control piston position. Means for limiting valve seating velocity, filling the hydraulic circuit upon engine start up, and mechanically locking the control piston/lever for a fixed level of valve actuation are also disclosed.
    Type: Application
    Filed: December 29, 2000
    Publication date: September 27, 2001
    Inventor: Joseph M. Vorih
  • Patent number: 6293237
    Abstract: A lost motion engine valve actuation system and method of actuating an engine valve are disclosed. The system may comprise a valve train element, pivoting bridge, an adjustable tappet, and a valve stem. The pivoting bridge may include a first end for contacting the adjustable tappet, a second end for contacting the valve stem and a pivot point between the first and second ends for contacting the valve train element. The amount of lost motion provided by the system may be selected by varying the position of the adjustable tappet relative to the pivoting bridge. Variation of the adjustable tappet position may be carried out by placing the adjustable tappet in hydraulic communication with a control trigger valve. Actuation of the trigger valve releases hydraulic fluid allowing for adjustment of the adjustable tappet position.
    Type: Grant
    Filed: June 16, 2000
    Date of Patent: September 25, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventor: Joseph M. Vorih
  • Publication number: 20010022171
    Abstract: A fuel injection pump for internal combustion engines is proposed, which has additional means for feeding a fluid from a second low-pressure side to a second high-pressure side. With this fluid, a hydraulic valve controller of the engine can be driven.
    Type: Application
    Filed: March 2, 2001
    Publication date: September 20, 2001
    Applicant: Robert Bosch GmbH
    Inventors: Hermann Gaessler, Udo Diehl, Karsten Mischker, Rainer Walter, Bernd Rosenau, Juergen Schiemann, Christian Grosse, Georg ` Mallebrein, Volker Beuche, Stefan Reimer
  • Patent number: 6289859
    Abstract: A V-shaped internal combustion engine in which banks of cylinders are V-shaped relative to each other and in which an intake manifold 40 is disposed between the V-shaped banks of cylinders, wherein a hydraulic pressure control valve 50 for controlling hydraulic pressures that are supplied to a hydraulic pressure control device is disposed at an end of a cylinder block 4 in a direction of a crankshaft between the V-shaped banks of cylinders.
    Type: Grant
    Filed: November 19, 1999
    Date of Patent: September 18, 2001
    Assignee: Honda Giken Kogyo Kabushiki Kaisha
    Inventors: Noriaki Fujii, Kouta Yoshiura
  • Patent number: 6273057
    Abstract: An apparatus for limiting the travel of a slave piston (110) in a slave piston cylinder (100) in a compression release engine brake is disclosed. The apparatus provides stroke-limiting means and independent lash adjustment means which may be installed in a common rail, variable valve actuation system. The independent lash adjustment means comprises a sleeve (300) around the slave piston (110), threadably mounted in the brake housing (40). The stroke-limiting means comprises a slave piston (110) in a slave piston cylinder (100), a trigger valve (90) and a hydraulic circuit connected thereto. The slave piston stroke is limited when a lower flow port (130) in the slave piston cylinder (100) is opened to drain (81) slightly before high-pressure flow is cut off through an upper flow port (120) in the slave piston cylinder (100).
    Type: Grant
    Filed: August 19, 1999
    Date of Patent: August 14, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventors: John A. Schwoerer, Eric Day
  • Patent number: 6269785
    Abstract: A cylindrical bush is provided at the distal end of an oil distributor inserted from the front cover side of a housing to prevent pressure oil from leaking from hydraulic chambers via a clearance formed between the hydraulic chambers and the housing. Further, sealing members are provided on both sides in the axial direction of a connecting section between an oil passage for supplying pressure oil to advancing hydraulic chambers and the oil distributor. The sealing members prevent a leakage from the connecting section.
    Type: Grant
    Filed: April 10, 2000
    Date of Patent: August 7, 2001
    Assignee: Denso Corporation
    Inventor: Michio Adachi
  • Patent number: 6267098
    Abstract: A valve actuation system for an internal combustion engine is disclosed. The system includes two hydraulic plungers (master pistons) that are selectively hydraulically coupled to a slave piston. The hydraulic motion from one of the hydraulic plungers may provide a valve opening motion to the slave piston and the hydraulic motion from the other hydraulic plunger may provide a valve closing motion. The net hydraulic motion of both hydraulic plungers may be zero, so that when both plungers have hydraulic communication with the slave piston, no slave piston motion occurs. The system may provide full authority over all engine valve actuations, such as main intake, main exhaust, compression release, and exhaust gas recirculation.
    Type: Grant
    Filed: November 24, 1998
    Date of Patent: July 31, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventor: Richard Vanderpoel
  • Patent number: 6263842
    Abstract: A hydraulically-assisted engine valve actuator for assisting in the actuation of an engine valve, includes a servo piston being operably coupled to the engine valve. A translatable pilot valve is in fluid communication with the servo piston and the main piston and is operably coupled to and controlled by a pilot valve positioning system. The pilot valve positioning system controls a translational stroke of the pilot valve to meter hydraulic fluid under pressure to and from the servo piston. A stroke magnifier magnifies a stroke of the pilot valve positioning system.
    Type: Grant
    Filed: March 2, 2000
    Date of Patent: July 24, 2001
    Assignee: International Truck and Engine Corporation
    Inventors: William De Ojeda, Pranab K. Das
  • Patent number: 6257183
    Abstract: A lost motion variable valve actuation system utilizing a single solenoid valve or trigger valve to vary the timing of the intake and exhaust valves for a cylinder of an internal combustion engine. The solenoid controls the oil supply to the tappets, which in turn, determine valve motion in response to a camshaft lobe The system allows independent control of each valve and provides for advanced features such as enhanced intake air swirl, two-valve or four-valve operation and staggered valve opening. The invention provides for valve operation even in the event of a total loss of system hydraulic pressure. The invention provides the practical benefits of a fully-variable system while preserving the security and reliability of a mechanical, cam-driven valve train. The invention provides for filling the exhaust and intake tappets independently without connecting their respective hydraulic circuits.
    Type: Grant
    Filed: November 4, 1998
    Date of Patent: July 10, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventors: Joseph M. Vorih, Mark A. Israel
  • Publication number: 20010006049
    Abstract: The reciprocating valve actuation and control system includes a poppet valve moveable between a first and second position; a source of pressurized hydraulic fluid; a hydraulic actuator including an actuator piston coupled to the poppet valve and reciprocating between a first and second position responsive to flow of the pressurized hydraulic fluid to the hydraulic actuator; an electrically operated valve controlling flow of the pressurized hydraulic fluid to the actuator; and an engine computer that generates electrical pulses to control the electrically operated valve. The electrically operated valve preferably comprises a three path rotary latched magnetic motor actuating a rotary valve portion having a housing, a rotor, and a stator receiving and supplying hydraulic fluid pressure to the rotor, which alternately directs the hydraulic fluid pressure to the valve cylinder for opening of the valve, or to return to the engine oil sump, for closing the valve.
    Type: Application
    Filed: January 16, 2001
    Publication date: July 5, 2001
    Inventors: Harry W. Buehrle, Raymond C. Clark, Jarrid Gross, Ron Long, Lance E. Nist
  • Patent number: 6244257
    Abstract: An internal combustion engine has electrically controlled hydraulic linkages between engine cams and engine cylinder valves. If it is desired to skip a cam lobe or to modify the response of an engine cylinder valve to a cam lobe, hydraulic fluid is selectively released from the associated hydraulic linkage to permit lost motion between the cam and the engine cylinder valve. Electrically controlled hydraulic fluid valves are used to produce the selective release of hydraulic fluid from the hydraulic linkages. The mode of operation of the engine can be changed (e.g., from positive power mode to compression release engine braking mode or vice versa), or more subtle changes can be made to modify the timing and/or extent of engine cylinder valve openings to optimize engine performance for various engine or vehicle operating conditions (e.g., different engine or vehicle speeds). The valves can be controlled to produce an exhaust gas recirculation event during various operating modes of the engine.
    Type: Grant
    Filed: July 31, 2000
    Date of Patent: June 12, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventor: Haoran Hu
  • Patent number: 6237551
    Abstract: A multi-cylinder Diesel engine, for trucks, particularly of the type supercharged by a turbo-supercharger actuated by the exhaust gases, is provided with a variable valve actuation system for actuating the intake and exhaust valves, which, in combination with a specific geometry of the cams driving the valves, provides the possibility of a plurality of different modes of operation of the engine which can be selected according to the conditions of operation of the engine and including, in addition to the regular mode of operation, at least one mode of operation of the engine as a brake.
    Type: Grant
    Filed: October 8, 1999
    Date of Patent: May 29, 2001
    Assignee: C.R.F. Societa Consortile per Azioni
    Inventors: Lorentino Macor, Andrea Pecori
  • Patent number: 6227154
    Abstract: A valvegear for an engine of reciprocating piston type is disclosed. The valve gear includes a cam, a camshaft and a cam piston, where the cam is mounted to rotate on the camshaft and is in contact with the cam piston. The cam piston is movably arranged within a pressure chamber and is adapted to be moved by the cam away from the camshaft to pressurize a fluid within the pressure chamber. The valvegear further includes an engine valve which is movable between an open position and a closed portion, a restoring spring associated with each engine valve, a valve piston which is movable arranged in an actuating chamber, the engine valve is arranged to be moved into the open position against the force of the restoring spring by the valve piston, where the valve piston is arranged to move in the actuating chamber by the pressure produced in said pressure chamber by movement of said cam piston.
    Type: Grant
    Filed: March 22, 2000
    Date of Patent: May 8, 2001
    Assignee: Ricardo Inc.
    Inventor: Russell John Wakeman
  • Patent number: 6223846
    Abstract: A method and a system for converting kinetic energy of a vehicle and part of energy supplied by its engine into energy of compressed air and using it to assist in vehicle propulsion later. A novel system of valves employing variable valve timing and valve deactivation is used to implement and control a two-way flow of compressed air between the engine and an air-reservoir where air-temperature control is maintained. During operation with compressed-air assist the engine operates both as an air-motor and as an internal combustion engine during each cycle in each cylinder. The engine can selectively and interchangeably operate either as a four-stroke or as a two-stroke internal combustion engine.
    Type: Grant
    Filed: June 15, 1998
    Date of Patent: May 1, 2001
    Inventor: Michael M. Schechter
  • Patent number: 6213076
    Abstract: A tappet (1) for a valve drive of an internal combustion engine is so designed as to be switchable for different valve lifts and includes an outer circular ring shaped section (5) which encloses a circular section (6). Both sections (5, 6) are acted upon by cams of different lifts, and selectively interconnectable together by coupling elements (9). According to the invention, a juncture (12) for hydraulic fluid is positioned in the skirt (2) and extending from a feed bore (13) in the cylinder head (4) at a lowest point of the tappet (1), when viewed in direction of gravity, in order to install the tappet (1) in an extreme slanted disposition. In opposition thereto, a port (21) of the channel (27), following the juncture (12), is arranged at a highest section of the tappet (1), when viewed in the direction of gravity.
    Type: Grant
    Filed: August 11, 1999
    Date of Patent: April 10, 2001
    Assignee: INA Wälzlager Schaeffler OHG
    Inventors: Gerald Fischer, Michael Haas, Gerhard Maas
  • Patent number: 6192841
    Abstract: An internal combustion engine valve actuation system is disclosed. The present invention provides a hydraulic actuator for operating an engine valve, which includes a control element for controlling the seating velocity of the valve. The present invention provides for free, unrestricted movement of the valve during opening, and an unrestricted return of the valve until the valve is within a predetermined distance of the valve seat. Once within this predetermined range, the return velocity of the engine valve is limited by the rate at which a fluid may escape through a flow restriction. The restriction is calibrated to provide the desired maximum valve seating velocity.
    Type: Grant
    Filed: November 20, 1998
    Date of Patent: February 27, 2001
    Assignee: Diesel Engine Retarders, Inc.
    Inventors: Joseph M. Vorih, Kevin J. Kinerson
  • Patent number: 6178935
    Abstract: A valve control device for an internal combustion engine having a gas exchange valve for controlling an inlet and/or outlet cross section in the combustion chamber of the engine. The valve control device has an axially movable gas exchange valve member whose valve member shaft is coupled to a piston rod to a differential piston that can be hydraulically actuated. The differential piston is embodied as two piston parts, wherein the two piston parts are disposed in relation to one another in such a way that they are operatively connected to each other in the axial direction and can execute a radial relative movement in relation to each other.
    Type: Grant
    Filed: May 8, 2000
    Date of Patent: January 30, 2001
    Assignee: Robert Bosch GmbH
    Inventors: Udo Diehl, Karsten Mischker, Rainer Walter, Stefan Franzl, Volker Beuche, Stefan Reimer, Ulrich Kappenstein
  • Patent number: 6173684
    Abstract: The reciprocating valve actuation and control system includes a poppet valve moveable between a first and second position; a source of pressurized hydraulic fluid; a hydraulic actuator including an actuator piston coupled to the poppet valve and reciprocating between a first and second position responsive to flow of the pressurized hydraulic fluid to the hydraulic actuator; an electrically operated valve controlling flow of the pressurized hydraulic fluid to the actuator; and an engine computer that generates electrical pulses to control the electrically operated valve. The electrically operated valve preferably comprises a three path rotary latched magnetic motor actuating a rotary valve portion having a housing, a rotor, and a stator receiving and supplying hydraulic fluid pressure to the rotor, which alternately directs the hydraulic fluid pressure to the valve cylinder for opening of the valve, or to return to the engine oil sump, for closing the valve.
    Type: Grant
    Filed: January 10, 2000
    Date of Patent: January 16, 2001
    Inventors: Harry W. Buehrle, II, Raymond C. Clark, Jarrid Gross, Ron Long, Lance E. Nist
  • Patent number: 6173685
    Abstract: A valve module that can be assembled to an internal combustion engine chamber. The valve module may have a first intake valve, a second intake valve, a third intake valve, a first exhaust valve and a second exhaust valve. The valves may be driven to an open position by hydraulically driven first pins. The exhaust valves may further have hydraulically driven second pins. The additional pins may increase the hydraulic forces which allow the exhaust valves to be opened even when there is a large pressure in the combustion chamber. The first pins of the exhaust valves may be controlled by a microprocessor controlled first control valve. The second pins may be controlled by a microprocessor controlled second control valve. The separate control valves and additional hydraulic force of the second pins may allow the microprocessor to open the exhaust valves at any point during a cycle of a combustion engine.
    Type: Grant
    Filed: March 22, 2000
    Date of Patent: January 16, 2001
    Inventor: Oded E. Sturman
  • Patent number: 6167853
    Abstract: The invention relates to a hydraulic control device for a lifting valve, the said device comprising a valve stem capable of being moved by two spring means acting in opposition to one another, the valve stem being capable of being activated hydraulically in the region of its end positions. According to the invention, the hydraulic control device contains a hydraulically regulatable spring means which is assigned a hydraulically acting auxiliary control member, by means of which the working fluid of the hydraulically regulatable spring means can be relieved of pressure.
    Type: Grant
    Filed: March 22, 2000
    Date of Patent: January 2, 2001
    Assignee: DaimlerChrysler AG
    Inventor: Ulrich Letsche