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EP0267188A1 - Unite de commande hydraulique - Google Patents

Unite de commande hydraulique

Info

Publication number
EP0267188A1
EP0267188A1 EP86904049A EP86904049A EP0267188A1 EP 0267188 A1 EP0267188 A1 EP 0267188A1 EP 86904049 A EP86904049 A EP 86904049A EP 86904049 A EP86904049 A EP 86904049A EP 0267188 A1 EP0267188 A1 EP 0267188A1
Authority
EP
European Patent Office
Prior art keywords
hydraulic
control unit
pressure
flow
supply line
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.)
Withdrawn
Application number
EP86904049A
Other languages
German (de)
English (en)
Other versions
EP0267188A4 (fr
Inventor
Bernd Hartwig Felsche
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.)
MYTTONS Ltd
Original Assignee
Myttons Ltd
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
Application filed by Myttons Ltd filed Critical Myttons Ltd
Publication of EP0267188A1 publication Critical patent/EP0267188A1/fr
Publication of EP0267188A4 publication Critical patent/EP0267188A4/fr
Withdrawn legal-status Critical Current

Links

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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/021—Valves for interconnecting the fluid chambers of an actuator
    • 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • F15B11/0445—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out" with counterbalance valves, e.g. to prevent overrunning or for braking
    • 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40553—Flow control characterised by the type of flow control means or valve with pressure compensating valves
    • F15B2211/40561—Flow control characterised by the type of flow control means or valve with pressure compensating valves the pressure compensating valve arranged upstream of the flow control 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40576—Assemblies of multiple valves
    • F15B2211/40584—Assemblies of multiple valves the flow control means arranged in parallel with a check valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41527—Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a directional control valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/47—Flow control in one direction only
    • F15B2211/473—Flow control in one direction only without restriction in the reverse direction
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F15B2211/5154—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an output member
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/575—Pilot pressure control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/615—Filtering 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/75—Control of speed of the output member

Definitions

  • THIS INVENTION relates to a hydraulic control unit.
  • the object of the present invention is to provide a con ⁇ trol system for a hydraulic circuit which enables the speed of movement being effected to be controlled automa ⁇ tically.
  • the invention resides in a hydraulic control unit for a hydraulic circuit wherein a power unit is connected to a hydraulic motor through a supply line and a return line said unit comprising means for metering the flow through the supply line in response to the load pressure therein and means for diverting excess flow in the supply line to the return line.
  • Fig. 1 is a hydraulic circuit diagram of one embodi ⁇ ment
  • Fig. 2 is an idealized graph showing the flow charac ⁇ teristics of the embodiment
  • Fig. 3 shows a unit constructed in accordance with the invention fitted to a lighting pole
  • Fig. 4 is a hydraulic circuit diagram for the appli ⁇ cation shown in Fig. 3;
  • Fig. 5 is a hydraulic circuit diagram showing the application of the invention to a wheel driven vehicle.
  • the pump supply is connected to port P, the hydraulic motor's delivery line to port A, the hydraulic motor's return line to port B and the hydraulic fluid tank to port T.
  • Flow is controlled by a balanced piston flow divider 11 divering excess flow supplied by the pump back to the tank.
  • the remaining flow from the pump passes through a metering orifice 12 resulting in a drop in pressure from the P side of the orifice to the A side.
  • the latter reduced pressure, together with a spring 13 act to balance the piston 11 against the pump line pressure so that a controlled flow passes through the metering orifice 12 to the hydraulic motor connected to port A.
  • a control piston 14 is mechanically linked to the metering orifice and progressively opens the orifice with in ⁇ creasing pressure. This is illustrated with reference to Fig. 2.
  • One particular application of the invention is a hydraulic pole raising device where a hydraulic cylinder is attached to a hinged base pole and the cylinder is extended or retracted to raise or lower the main section of the pole.
  • This application is illustrated in Figs. 3 and 4 of the drawings.
  • a mobile hydraulic unit 20 is provided with a lifting cylinder 21 one end of which is anchored to the base 22 of a pole and the upper end to the main section 23 of the pole which is arranged to rotate about a transverse hinge pin 24.
  • the hydraulic unit comprises a tank 25, a pump 26 and a motor 27. Hydraulic fluid under pressure is fed through a control valve assem ⁇ bly 28 via a pressure relief valve 30 and one-way valve 31 and a control unit 29, substantially identical with that shown in Fig. 1, to the cylinder 21.
  • the control unit's port A is connected to the head-end of the lifting cylinder. Due to the physical arrangement of the pole and cylinder, the load pressure on the head-end of the cylinder, and hence at the control unit's port A will depend on the angle of the main section of the pole above horizontal, the mass of the main section of the pole together with the weight of any attached fittings, and the location of the corresponding centre of mass.
  • control unit is in an all terrain, wheel driven vehicle wherein a separate hydraulic motor is used for each wheel and a control unit of the present invention is used to control the rate of flow to each motor.
  • a separate hydraulic motor is used for each wheel and a control unit of the present invention is used to control the rate of flow to each motor.
  • the pressure in supply line 34 to hydraulic motor 35 increases up to the maximum supplied by the pump or the maximum sustainable by the supporting surface.
  • the control unit 36 which is identical with that shown in Figs. 1 and 2 also supplies a greater rate of flow to the hydraulic motor, thereby allowing the corresponding wheel to rotate more rapidly.
  • the overall vehicle speed is set independently by varying the maximum rate of flow of hydraulic fluid to the drive circuit by adjustment of a variable displacement pump 37.
  • the effect of the control circuit is to limit the rota ⁇ tional speed of the wheels to the maximum possible under the available traction conditions.
  • the control unit may have .two further zones of operation shown in Fig. 2.
  • the first is a Trickle zone (T), where a small flow (Qmin) will always be present at low pressure. This means that a rotary hydraulic motor will rotate very slowly or a cylin ⁇ der will extend or retract very slowly under no or low loads.
  • T Trickle zone
  • the other zone is a Free Flow zone (F) where the pressure is sufficiently high to fully open the metering orifice and allow full pump flow to the outlet port A. Due to practical limitations, there will always be a small leak ⁇ age flow (Qlc) through the balanced piston flow divider.
  • Qlc leak ⁇ age flow
  • Transition between the zones depends on the control piston spring preload, stiffness and type. Also, the actual shape of the flow characteristic can be markedly affected by the changing of the viscosity of the hydraulic fluid.
  • variable metering orifice and balanced piston may be replaced by electronic pressure sensing and an electrically controlled proportional spool valve.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Valve Device For Special Equipments (AREA)

Abstract

Une unité de commande hydraulique permet de commander automatiquement le régime d'un moteur hydraulique soumis à des charges variables dans un circuit hydraulique où un groupe moteur est connecté au moteur hydraulique par une conduite d'alimentation et par une conduite de retour. L'unité de commande hydraulique comprend une ouverture de dosage (12) maintenue fermée par un ressort et reliée mécaniquement à un piston de commande (14), la pression de la lumière de pression (A) du moteur hydraulique s'exerçant sur le piston de commande, et un distributeur d'écoulement (11) à piston équilibré par lequel l'écoulement excédentaire retourne au réservoir (T). Le distributeur d'écoulement (11) est connecté par une extrémité à la conduite d'alimentation, à un point situé entre la pompe (P) et l'ouverture de dosage, et par l'autre extrémité à la conduite de retour. En fonctionnement, lorsque la pression de la lumière de pression (A) décroit, l'ouverture de dosage se ferme progressivement, ce qui provoque une chute croissante de pressionà travers l'ouverture de dosage. Cette chute de pression agit sur le distributeur d'écoulement à piston équilibré de façon à faire retourner de plus en plus l'écoulement vers le réservoir. Inversement, lorsque la pression de la lumière de pression (A) augmente, un écoulement progressivement réduit retourne vers le réservoir. Deux applications sont proposées pour cette unité de commande. La première concerne la commande d'un dispositif d'érection de poteaux, la deuxième concerne la commande de moteurs hydrauliques séparés qui entraînent les roues d'un véhicule tout terrain.
EP19860904049 1985-07-15 1986-07-15 Unite de commande hydraulique. Withdrawn EP0267188A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU1506/85 1985-07-15
AUPH150685 1985-07-15

Publications (2)

Publication Number Publication Date
EP0267188A1 true EP0267188A1 (fr) 1988-05-18
EP0267188A4 EP0267188A4 (fr) 1989-09-19

Family

ID=3771180

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860904049 Withdrawn EP0267188A4 (fr) 1985-07-15 1986-07-15 Unite de commande hydraulique.

Country Status (3)

Country Link
EP (1) EP0267188A4 (fr)
AU (1) AU590317B2 (fr)
WO (1) WO1987000589A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8824539D0 (en) * 1988-10-20 1988-11-23 Dosco Overseas Eng Ltd Automatic speed control

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2005666A1 (de) * 1970-02-07 1971-08-12 P Leistritz Maschf Vorrichtung zum Steuern bzw Rgeln der Fahrgeschwindigkeit von hydraulischen Auf zügen od dgl
FR2230578B1 (fr) * 1973-05-25 1976-11-12 Poclain Sa
DE2514624C3 (de) * 1975-04-03 1986-10-23 Danfoss A/S, Nordborg Steuereinrichtung für mindestens einen hydraulisch betriebenen doppeltwirkenden Verbraucher
SU580368A1 (ru) * 1975-08-18 1977-11-15 Предприятие П/Я В-2248 Насосный гидропривод
DE2701509C2 (de) * 1977-01-15 1985-10-31 Robert Bosch Gmbh, 7000 Stuttgart Hydraulische Steuereinrichtung für wenigstens zwei hydraulische Verbraucher
US4206688A (en) * 1978-06-09 1980-06-10 Caterpillar Tractor Co. Overrunning load control for hydraulic motors
DE2943642A1 (de) * 1979-10-29 1981-05-07 G.L. Rexroth Gmbh, 8770 Lohr Vorrichtung zum steuern eines einfach wirkenden arbeitszylinders, insbesondere eines pressenarbeitszylinders
JPS56122774A (en) * 1980-02-26 1981-09-26 Oirudoraibu Kogyo Kk Oil pressure elevator
CA1164314A (fr) * 1981-01-30 1984-03-27 Willard L. Chichester Selecteur a regulateur de debit sur circuit hydraulique

Also Published As

Publication number Publication date
AU6139086A (en) 1987-02-10
AU590317B2 (en) 1989-11-02
WO1987000589A1 (fr) 1987-01-29
EP0267188A4 (fr) 1989-09-19

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19871215

AK Designated contracting states

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Effective date: 19890919

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Owner name: MYTTONS LIMITED

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18D Application deemed to be withdrawn

Effective date: 19910719

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Inventor name: FELSCHE, BERND, HARTWIG