Patents Assigned to Mannesmann Rexroth GmbH
  • Patent number: 4924754
    Abstract: For path control of a plurality of drives, i.e. for driving a plurality of drives in different axes in geometrical path dependence, to obtain high accuracy it is necessary for the lag error of the drives to remain constant. According to the invention for this purpose a circuit arrangement is proposed in a cascade structure in which from the speed of each individual path drive and the control deviation determined from the actual value and desired value of the position a difference signal is formed which is integrated and added to the output signal of a P controller.
    Type: Grant
    Filed: March 6, 1989
    Date of Patent: May 15, 1990
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Alfred Feuser, Joachim Neumann, Walter Voxbrunner
  • Patent number: 4924671
    Abstract: For the production and exact control and regulation of very high pressures, in particular for actuating a press, two pressure intensifiers are provided which each have a differential piston. The second pressure intensifier is connected via a shutoff valve to the first pressure intensifier and to the load or consumer. Both pressure intensifiers have a small volume compared with the volume required by the consumer. By activating the second pressure intensifier fluid can be exchanged between the consumer and the first pressure intensifier to replenish the first pressure intensifer in a pressure buildup phase and to empty the first pressure intensifier in a pressure relief phase.
    Type: Grant
    Filed: November 24, 1987
    Date of Patent: May 15, 1990
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Michael Reinert
  • Patent number: 4920748
    Abstract: The torque of a hydraulic machine is dependent of the fluid pressure delivered to the machine and is further dependent of the adjustment of its volume of through-put. In response to a load coupled to the machine, a speed results which is controlled by a speed control system acting on the adjusting system of the hydraulic machine. According to the invention, an electro hydraulic speed control comprises a pair of control circuits which are connected to, but operate independent of each other. Thus the electrical control circuit produces a control signal y.sub.e1 from the difference of the actual value and the desired value of the speed for adjusting a hydraulic restricting means which produces a hydraulic pressure signal p.sub.st in the hydraulic control circuit which pressure signal is compared with a hydraulic reference signal p.sub.o to produce a differential pressure signal p.sub.o -p.sub.st which is applied to the adjusting cylinder of the hydraulic machine.
    Type: Grant
    Filed: August 10, 1984
    Date of Patent: May 1, 1990
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Rolf Kordak, Heinrich Nikolaus, Frank Metzner
  • Patent number: 4905535
    Abstract: A hydrostatic gear wheel mechanism has two intermeshing gear wheels in the work space of a housing. To continuously rinse the gear wheel and housing surfaces which slide on each other, grooves on the gear wheel convey lubricant from the work space to between the gear wheel front faces and the axial end walls of the work space.
    Type: Grant
    Filed: October 28, 1987
    Date of Patent: March 6, 1990
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Werner Ludwig, Rainer Nickel
  • Patent number: 4901624
    Abstract: A hydraulic driving device includes a working cylinder for moving a machine component, and an electro-hydraulic servo system. The servo system includes a servo-valve, a position-error control, a circuit for emulating speed and acceleration of the working cylinder, and a regulator for weighting the ascertained position error according to the emulated speed and acceleration, and generating a setting signal for the servo valve.
    Type: Grant
    Filed: June 20, 1988
    Date of Patent: February 20, 1990
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Alfred Feuser
  • Patent number: 4896694
    Abstract: To reduce the noise on response of a pressure-limiting valve, downstream of the valve seat an annular space, an annular gap and a further annular space are provided. This flow-off system gives a reduction of the noise level. Moreover, in pressureless circulation the flow resistance of the valve is low because the annular gap is freed by the piston.
    Type: Grant
    Filed: March 16, 1989
    Date of Patent: January 30, 1990
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Georg Rausch
  • Patent number: 4883092
    Abstract: A control valve apparatus is described which is intended for selective transmission of pressure to at least two pressure spaces. A magnetic control device is provided for selectively applying a hydraulic system pressure to the respective pressure spaces. As another function, the apparatus may simultaneously depressurize the two pressure spaces through the application of a control pressure to the control valve apparatus. To minimize the required installation space and the manufacturing cost, the control valve apparatus is comprised of a single control valve, the control piston means of which can be exposed to the control pressure against the force of a restoring device and can be moved into intermediate control positions by means of the magnetic control device.
    Type: Grant
    Filed: September 8, 1988
    Date of Patent: November 28, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Winfried Rub
  • Patent number: 4878543
    Abstract: A method of controlling an attachment to an agricultural tractor in which the absolute movement of the attachment is determined by a motion sensor mounted thereon and is utilized as a control standard while the relative motion of the attachment with respect to the tractor, influenced by the controller and carried out by a power lift, is determined in such a way that the absolute movement of the attachment becomes zero. This control method achieves that the attachment maintains a constant position in space in spite of the pitch movements of the tractor acting as disturbances. This guarantees an automatic tilling process, for instance a uniform depth of the furrows when plowing. By utilizing superimposed feedbacks of further control standards, such as relative position and motor load, changes in the absolute position of the attachment are possible and overloading of the motor is avoided.
    Type: Grant
    Filed: April 20, 1987
    Date of Patent: November 7, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Wolfgang Kauss
  • Patent number: 4862691
    Abstract: Speed regulation of pump drive is set by a pressure-regulating valve providing a constant control pressure for a plurality of normal loads. If a high fluid consumption load such as the lifting cylinder of a forklift truck is to be simultaneously actuated the pump speed and net volumetric displacement must be increased. A higher speed-regulating control pressure from the pressure-regulating valve is required. The control valve for the high consumption load has a spool with an extending inclined cam contacting the biasing spring of the pressure-regulating valve. Upon actuation of this control valve the preload of the biasing spring is increased thereby adjusting the speed-regulating control pressure output of the pressure regulating valve. The pump engine or drive speed and the net volumetric displacement are increased.
    Type: Grant
    Filed: April 22, 1988
    Date of Patent: September 5, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Werner Peschel
  • Patent number: 4862919
    Abstract: A hydraulic system includes a multi-position valve which controls the flow of system fluid pressure to various work stations. The multi-position valve is biased by a centering spring to a neutral position from which it can be shifted to a selected working position. A retaining mechanism is able to retain the valve in the selected working position when the system pressure is in a prescribed pressure range. The retaining mechanism is urged to its retaining position by a control fluid pressure which is derived from the system pressure. When the system pressure is below or above the prescribed pressure range the retaining mechanism is unable to resist the force of the centering spring and the valve assumes a neutral position. When the system pressure is in the prescribed range, a constant control pressure is supplied to the retaining mechanism for effectively resisting the force of the centering spring.
    Type: Grant
    Filed: January 4, 1989
    Date of Patent: September 5, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Frank Stemmer
  • Patent number: 4864210
    Abstract: An electro-hydraulic servo-valve having a valve spool and comprising: an adjustment motor, and a control apparatus for adjusting said adjustment motor to depending on the input nominal value, wherein said adjustment motor transmits its movement directly to the valve spool of the hydraulic valve, and wherein a preferably electrically operating additional drive is provided which will be switched on in case the valve spool gets stuck so as to release the valve spool from its stuck condition.
    Type: Grant
    Filed: February 8, 1988
    Date of Patent: September 5, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Jorg Dantlgraber
  • Patent number: 4860634
    Abstract: For setting and guiding a band running round two rolls the bearings of the roll on either side are each adjustable by a hydraulic or lifting cylinder. Each hydraulic cylinder comprises a position control circuit. The position desired value applied jointly to the position control circuits is varied by a tension-dependent control in such a manner that in the position adjustment a maximum admissible tension force is not exceeded. Furthermore, the position desired value has superimposed thereon a correction control by which the center setting of the band is monitored. The arrangement is preferably provided for positioning and tension-dependent adjustment of the encircling metal band of a sheet casting apparatus.
    Type: Grant
    Filed: August 8, 1988
    Date of Patent: August 29, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Theo Hein
  • Patent number: 4856278
    Abstract: According to the parent patent on inadequate power of the delivery pump the flow rate set at the directional control valves for the consumers is reduced in equal proportions in that electrical signals proportional to the flow rates are supplied to a summation stage and the sum voltage is compared in a comparison stage with a limit value corresponding to the maximum pump delivery flow. When the limit value is exceeded a control signal is generated with which the stroke of all the driven directional control valves can be jointly reduced. According to the application of addition the signal voltage supplied to the summation stages and corresponding to the respective flow rate can be obtained in a displacement pickup associated with each directional control valve or in a pressure pickup measuring the pilot pressure if the directional control valves are not controlled electrically but hydraulically.
    Type: Grant
    Filed: December 29, 1987
    Date of Patent: August 15, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Karlheinz Widmann, Norbert Kreth, Martin Schmitt, Armin Stellwagen
  • Patent number: 4850191
    Abstract: A pump supplies a plurality of consumers each via a directional control valve with pressure balance. When the pump delivery is not adequate, manifesting itself in a dropping of the pump pressure, the pressure balance of the consumer with the highest load pressure is displaced out of the end position of its regulating position into a further control position in which a control pressure line is connected via a throttle point to a discharge so that by means of the throttle point a control pressure is generated which is used for equiproportional reduction of the supply flow to the consumers. This is done either by reducing the stroke of the directional control valves or by acting on the pressure balances in the closure direction.
    Type: Grant
    Filed: December 29, 1987
    Date of Patent: July 25, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Norbert Kreth, Martin Schmitt, Armin Stellwagen
  • Patent number: 4850394
    Abstract: A two-way control valve includes a valve member with a longitudinal bore connecting its opposite ends with each other. A housing receives the movable valve member and has two attachment ports. A control piston is operatively coupled with the valve member. To provide a two-way valve permitting pressure medium to flow in both directions when the valve member is moved from its closed position, the control piston is tightly or fixedly connected with the valve member and is arranged as an annular collar on the periphery of the valve member. The longitudinal bore is free of constrictions.
    Type: Grant
    Filed: May 30, 1985
    Date of Patent: July 25, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Rainer Imhof, Wolfgang Lukasczyk
  • Patent number: 4845950
    Abstract: Improved control of a hyrostatic drive machine at very small speeds of rotation. The rotation speed control signal in the creep rotation speed region is modified in dependence upon the actual value of the rotation angle and possibly the efficiency characteristic diagram so as to produce a regulated constant torque.
    Type: Grant
    Filed: June 5, 1987
    Date of Patent: July 11, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventor: Frank Metzner
  • Patent number: 4838765
    Abstract: The invention relates to a pump, in particular to an axial piston pump of the swash plate type, wherein the suction pressure medium is fed into the swash plate chamber, so as to be arranged in layers of different pressure. The pressure medium is removed from a desired pressure layer and supplied to the pump chamber so as to obtain a desired pump flow characteristic.
    Type: Grant
    Filed: August 20, 1986
    Date of Patent: June 13, 1989
    Assignee: Mannesmann Rexroth GmbH, Jahnstrasse
    Inventors: Peter Wusthof, Egon Eisenbacher, Manfred Lotter, Rainer Stolzer
  • Patent number: 4835966
    Abstract: A control switching arrangement for a hydraulic power lift control system comprises a power lift control valve which is controlled via control lines in a low pressure section. The main hydraulic section is controlled by the said control valve via a check valve which is hydraulically openable, at least for carrying out lowering movement by the power lift. The check valve is opened via the said control valve itself, which furnishes the switching line a pressure generally equal to the circulation pressure of the main hydraulic section. Further, means are provided whereby, in the switching state corresponding to lowering movement of the power lift, the circulation pressure of the main hydraulic section can be increased. With this control system the low pressure control section is simplified, and energy losses in the control system are kept as low as possible.
    Type: Grant
    Filed: June 16, 1987
    Date of Patent: June 6, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Wolfgang Kauss, Heinz Schulte
  • Patent number: 4832081
    Abstract: The present invention relates to the use of two different sealing means in a directional spool valve. On the one hand side, a pressure guide element is provided at the spool so as to make sure that the pressure medium can only flow in radial direction against a seal located in the housing. The second sealing means may be of different design. It is possible that a spool seat surface provided on the spool and moveable against the force of a spring is used, said spool seat surface being adapted to cooperate with a stationary seat surface provided at the housing; alternatively a plurality of control bores is provided in the housing in the area of a port, said bores having a relatively small diameter d, and wherein a seal located the spool is used for opening and closing said bores so that no damage of the seal can occur. It is also possible to make use of the last mentioned sealing principle by itself.
    Type: Grant
    Filed: July 10, 1987
    Date of Patent: May 23, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Reinhard Amrhein, Walter Heid, Gunther Muschong
  • Patent number: 4826254
    Abstract: A hydraulic dual-circuit external power brake valve of tandem design has a primary control piston and a secondary control piston, both of which are located in a valve bore of the dual-circuit external power brake valve. The control pistons are provided with bores for connection of a primary brake circuit and a secondary brake circuit to a pressure reservoir and an equalizing tank, and are movable within the valve bore. The regulating force necessary for the motion is introduced into the dual-circuit external power brake valve by a regulating spring. A pressure-transmitting piston between the primary control piston and the regulating spring. The primary control piston on its two end faces, and the pressure-transmitting piston on its face toward the primary piston, are subjected to the pressure acting in the primary brake circuit. When the primary brake circuit is intact, the pressure-transmitting piston is actuated by the regulating spring.
    Type: Grant
    Filed: December 8, 1986
    Date of Patent: May 2, 1989
    Assignee: Mannesmann Rexroth GmbH
    Inventors: Kurt Wittich, Harald Hofstotter