WO2009149712A1 - Système de commande servant à commander un écoulement de fluide depuis une source d’alimentation - Google Patents

Système de commande servant à commander un écoulement de fluide depuis une source d’alimentation Download PDF

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Publication number
WO2009149712A1
WO2009149712A1 PCT/DK2009/000140 DK2009000140W WO2009149712A1 WO 2009149712 A1 WO2009149712 A1 WO 2009149712A1 DK 2009000140 W DK2009000140 W DK 2009000140W WO 2009149712 A1 WO2009149712 A1 WO 2009149712A1
Authority
WO
WIPO (PCT)
Prior art keywords
flow rate
auxiliary
steering
pump
control system
Prior art date
Application number
PCT/DK2009/000140
Other languages
English (en)
Inventor
Hans Jørgen JENSEN
Stephan Kaiser
Per Nielsen Lindholdt
Original Assignee
Sauer-Danfoss Aps
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 Sauer-Danfoss Aps filed Critical Sauer-Danfoss Aps
Publication of WO2009149712A1 publication Critical patent/WO2009149712A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/07—Supply of pressurised fluid for steering also supplying other consumers ; control thereof

Definitions

  • the present invention relates to a control system for steering a mobile machine or vehicle and for controlling the movement of a tool associated with the machine.
  • the invention relates to an electronic control system adapted to allocate a necessary flow rate of a hydraulic fluid to a steering actuator based on a steering command.
  • the invention further relates to a mobile machine provided with such a control system.
  • Vehicles and in particular off-highway machinery such as wheel loaders, excavators, dozers, articulated vehicles, tractors, harvesters and similar heavy duty machines, in the following referred to generally as mobile machines, often operate with hydraulic, electro-hydraulic, and electric steering systems.
  • the steering system receives a steering command from an operator of the mobile machine.
  • the input could be provided via input means such as a joystick, a steering wheel, or the input could be derived from a GPS system or a similar system for positioning and tracking.
  • the input is converted into a movement of a valve which controls a flow of a hydraulic fluid between a hydraulic pump and a steering actuator, typically being a hydraulic cylinder arranged to move a wheel of the mobile machine.
  • Steering systems are disclosed e.g. in US 6,668,967 and in EP0856453.
  • mobile machines have various auxiliary actuators connected to the same hydraulic pump.
  • functions powered by such actuators are bachhoe, boom or bucket functions of a back-hoe digger, or the mobile machine may simply have a hydraulic power outlet for connecting any kind of hydraulically driven auxiliary machinery.
  • control systems are typically designed not to allow operation of the auxiliary functions while the steering function is active, or only to allow certain auxiliary functions while the steering function is active.
  • mechanically operating priority valves graduate the flow between the steering system and auxiliary functions on the machine.
  • the invention provides a system of the kind mentioned in the introduction wherein the control system is further adapted to allocate an auxiliary flow rate of the hydraulic fluid to at least one auxiliary actuator, the allocation of the auxiliary flow rate being based on an auxiliary control command, a limit flow rate, and the necessary flow rate to the steering actuator.
  • the auxiliary actuators may always be provided with as much hydraulic fluid as a specific steering situation allows. If the mobile machine moves in a constant path without needing a fluid flow for steering purpose, the auxiliary actuators may have all the available fluid flow, or at least a very large portion of the available flow, and as soon as the operator of the machine commands a change in the driving path, the auxiliary flow may be scaled down based on the newly defined necessary flow rate to the steering actuator.
  • the electronic control system may be implemented in any kind of computing means, and the communication between the control system and external sensors, pumps etc. may be based on standard communication already known for mobile machines, e.g. CAN.
  • flow rate should be understood in the broadest sense and covers an amount of fluid, a flow speed of the fluid and/or a pressure of the fluid.
  • the steering command should be understood as any signal indicative of a desired steering activity for the mobile machine.
  • the steering command may be an electrical signal generated in a steering system with a joy-stick, an electronic steering wheel, or any kind of handle by which an operator may indicate a desired steering activity.
  • the steering command may also be provided by a flow of a hydraulic fluid, e.g. from a hydraulic control handle, or as a mechanical input, e.g. from a steering wheel, e.g. via a control device from the company Sauer-Danfoss sold generally under the name OSP.
  • the steering command may also be generated in an auto-steering service e.g. including GPS or radar based navigation means.
  • an auto-steering service e.g. including GPS or radar based navigation means.
  • the steering command may specify not only a desired path of the mobile machine or a desired orientation of a front wheel or a similar steering component of the mobile machine, but also a speed by which the steering activity should preferably be carried out.
  • the control system Based on the steering command, the control system allocates a necessary flow rate, i.e. a flow rate which is necessary for a steering actuator, e.g. a hydraulic cylinder, to perform the desired steering activity.
  • a necessary flow rate i.e. a flow rate which is necessary for a steering actuator, e.g. a hydraulic cylinder, to perform the desired steering activity.
  • the control system may comprise an electronically operated valve, or it may comprise the above-mentioned OSP steering fluid controller from the company Sauer- Danfoss. The valve controls the fluid communication between the pump which delivers the hydraulic flow and the steering actuator.
  • the pump is considered as that system which delivers the fluid flow for the steering and for the auxiliary actuator.
  • the pump may be driven by an electrical motor or by a combustion engine, e.g. by the main engine of the mobile machine.
  • the pump is nevertheless considered to be the total system which delivers the fluid flow, i.e. the pump and the power means which is connected thereto for driving the pump.
  • the auxiliary flow rate of the hydraulic fluid is allocated to at least one auxiliary actuator, e.g. a hydraulic cylinder of a crane or any similar auxiliary.
  • the auxiliary control command may thus be a command generated by manual operation of a joystick by which an operator of the mobile machine indicates lifting of a boom, a crane, a plough etc, or the auxiliary control command could be generated automatically by peripheral equipment of the mobile machine.
  • the control is an electronic system adapted to compare a limit flow rate with the flow rate which is necessary for the actual steering activity and the auxiliary command, and based thereon to determine an auxiliary flow rate
  • the response time may be improved relative to that of traditional systems based on mechanical priority valves in which the control is based on changes in a pressure in the hydraulic system.
  • the allocation of the auxiliary flow rate may generally be based on a calculation including insignias representing the auxiliary control command, the limit flow rate, and the necessary flow rate to the steering actuator.
  • the auxiliary control command, the limit flow rate, and the necessary flow rate to the steering actuator may each be represented by a value which is included in arithmetic operations based on which the auxiliary flow rate is allocated.
  • One way of determining the auxiliary flow rate is to calculate a theoretically demanded flow rate which corresponds to the auxiliary control command. The theoretical flow rate is added to the necessary flow rate, and the total flow rate is compared with the limit. If the total flow rate exceeds the limit, the auxiliary flow rate is scaled down, e.g. until the limit is reached, or until the total flow rate is lower than the limit.
  • the limit flow rate may e.g. correspond to that flow rate which is available from the hydraulic pump which delivers the hydraulic fluid, i.e. the maximum which can be delivered by the pump.
  • the limit flow rate can be defined either by the pump itself, by a power source driving the pump, e.g. the main engine of the mobile machine, or by other limiting structures of the system, e.g. valves etc.
  • the limit could be defined as a percentage, e.g. 90 pet of the available flow rate.
  • the limit may also be defined as a variable percentage of the available flow rate, the variable percentage depending on operational conditions of the mobile machine, e.g. the driving speed of the mobile machine, the number of revolutions per minute of the pump or the engine powering the pump, the pressure of the hydraulic fluid at a selected place in the fluid distribution system between the pump and the actuators, a flow rate of the fluid etc.
  • the available flow rate often depends on various operating conditions of the mobile machine. Since the hydraulic pump is typically driven by the main engine of the mobile machine, the available flow rate depends on the amount of power which is delivered by the main engine to the pump versus which is used for other purposes. It may also depend on the number of revolutions for the main shaft of the pump or the number of revolutions for the main engine etc.
  • the control system may be adapted to determine the available flow rate by communication either with the pump, with the main engine, with a sensor, e.g. a pressure or a flow sensor or with any other kind of sensor capable of providing an insignia for the available flow rate.
  • the control system may be adapted to share the auxiliary flow rate between the auxiliary actuators.
  • This sharing of the auxiliary flow rate could be based on a specification.
  • the specification may either define the share in a static manner, i.e. by what percentage the flow rate should be shared between the actuators, or the specification may be based on the actual situation, e.g. so that a specific share is used whenever the auxiliary flow rate corresponds to the theoretically demanded flow rate or if these two values are within a specific range from each other, whereas another share is used when the theoretically demanded flow rate is above a certain distance from the auxiliary flow rate.
  • the system may comprise electronically controlled proportional valves for controlling a share of the auxiliary flow rate to each auxiliary actuator.
  • the control system may comprise a steering system which is adapted to provide the steering command e.g. in the form of a hydraulic pressure signal, a mechanical signal, or in the form of an electrical signal.
  • the system may be adapted to switch between different pumps, e.g. between pumps being driven in different ways.
  • One pump may be driven by a main engine of the mobile machine and another pump may be driven electrically so that steering activities can be continued even if the main engine stops.
  • one pump drives the steering activities and another pump drives the auxiliary actuators, again, the two pumps could be powered differently.
  • the control system may be adapted to determine if the pump is overloaded.
  • overloaded is herein meant that the pump cannot provide pressurized fluid at a sufficient flow rate or at a sufficient pressure for the necessary steering function.
  • the system may reduce the necessary flow rate, it may initiate operation of an additional pump, or it may reduce the speed by which the mobile machine is moved so that the steering activity can be performed safely even though the available flow rate limits the speed by which the steering activity is carried out.
  • the mobile machine may have at least one pump which provides a variable fluid rate.
  • the fluid rate may e.g. be varied by use of electronic inlet and outlet valves in a piston pump or by means of a tiltable swash plate etc.
  • the control system may be adapted to control the pump based on the auxiliary control command and the necessary flow rate to the steering actuator so that the pump delivers a suitable flow rate taking the necessary and the auxiliary flow rates into consideration.
  • the control system may update with a specific clock frequency so that the necessary flow rate and auxiliary flow rates are determined frequently.
  • the clock frequency can be determined e.g. based on input from sensors, e.g. input relating to the pressure and/or orther flow rate related states of the hydraulic fluid, based on speed of the mobile machine, based on the steering command and/or the auxiliary command, or the clock frequency could be a fixed frequency e.g. between 1 Hz and 50 Hz.
  • the invention provides a mobile machine comprising a control system according to any of the preceding claims.
  • the mobile machine could be a wheel loader, an excavator, a dozer, an articulated vehicle, a tractor, a harvester or in general any kind of heavy duty machine.
  • FIG. 1 schematically illustrates a hydraulic actuator and steering system for a mobile machine which is provided with a control system according to the invention.
  • the hydraulic system comprises a steering actuator 1 and a number of hydraulically operated power actuators 2, 3.
  • Each hydraulic actuator is associated with a specific function on the mobile machine, e.g. for lifting a boom or bucket.
  • the steering actuator is typically connected to a steering mechanism for turning the front wheels relative to the rear wheels etc.
  • steering is traditional orbitrol steering with added sensors for measurement of service port pressures and steering wheel angle/speed.
  • a hydro mechanical load compensator In front of the steering unit is a hydro mechanical load compensator securing constant pressure drop from a pressure port to highest loaded service port and protecting against overpressure.
  • the steering actuator is controlled by a so called OSP steering unit 4 from the company Sauer-Danfoss.
  • the OSP steering unit reads a steering command via the steering wheel 5 and based on the steering command, it meters a flow of hydraulic fluid to either the right or left side of the steering cylinder.
  • the hydraulic fluid under pressure is provided by a hydraulic pump 6 which is driven by the main engine of the mobile machine.
  • the advantage of using an OSP steering unit is that it may provide the hydraulic pressure itself if the pump fails.
  • a control system is inserted between the pump 6 and the OSP steering unit 4.
  • the control system allocates a necessary flow rate of a hydraulic fluid to the steering purpose based on the steering command received via the OSP steering unit 4.
  • the steering command is determined by the control system based on a pressure drop or flow rate between the pump 6 and the steering actuator 1.
  • the control system could be directly connected to the steering wheel or similar control handle or to a GPS and based on an electrical or hydraulic signal received therefrom, it may calculate a theoretically needed flow rate of the fluid for the steering purpose.
  • the steering wheel speed may be measured and provided to the control system which then calculates a flow rate which is necessary for causing a comparable steering activity.
  • the hydraulic system comprises at least one control handle (not shown).
  • the operator of the mobile machine can specify an auxiliary control command, e.g. specifying lifting of a bucket or boom.
  • Each auxiliary actuator is controlled by a separate proportional valve 7, 8, 9, and each proportional valve is provided with a sensor and a processor so that opening of the valves and thus the auxiliary flow rate can be controlled.
  • the valves have electronic control of pressure and flow to the actuators.
  • a valve group is designed to control functions with SIL 2 safety requirements. Safe state of the valve implies a P-block valve function which isolates the valve section from the pump.
  • the valve groups have internal CAN communication between sections and gateway to the internal CAN communication. The valves are designed with self diagnostics and monitoring.
  • an inlet module is provided. Sensors, for example for measuring pressure and flow, can be located in this inlet module. Together with a processor, these sensors will provide the system with the same information as would sensors arranged in each of the valves. This ensures that also simple valves can be used in such a system.
  • the auxiliary control command is received either directly by the control system or it is received by the proportional valves 7, 8, 9 which then provide a required flow to the control system.
  • the control system Based on the control command, either as received directly or as received indirectly as a requirement for flow to a proportional valve, the control system allocates an auxiliary flow rate of the hydraulic fluid to at least one of the auxiliary actuators 2, 3. In this process, the control system takes into consideration not only the auxiliary control command but also the necessary flow rate to the steering actuator and a limit which is specified for the mobile machine.
  • the limit from which the auxiliary flow rate is calculated corresponds to the available flow rate subtracted a safety margin to ensure that sufficient flow is always available for steering purpose.
  • the pump 6 has electronic flow control and pressure control. Safe state of the pump will be max pressure and variable displacement performed by hydro-mechanical means.
  • the pump is designed with self diagnostics and monitoring.
  • a swash plate controls the displacement of fluid from the pump, and the swash plate angle is controlled by the control system which thereby becomes capable of changing the available flow rate of the hydraulic fluid and thereby provides a suitable match between the demand from the steering system, the demand from the auxiliary actuators and the capacity of the pump.
  • the control system comprises a processing unit operating with a software instruction set which specifies prioritization of steering so that steering is secured all the flow it requires in case of a flow limitation, i.e. when reaching a limit of the pump capacity.
  • the control system :
  • control system checks the supply of hydraulic fluid from the pump, and in case of failure, e.g. in case of engine fall-out, pump failure, valve failure etc, the steering function will use a secondary supply - i.e. an additional safety pump, e.g. an electrically powered pump.
  • a secondary supply i.e. an additional safety pump, e.g. an electrically powered pump.
  • the control system 10 comprises a steering speed and pressure sensor input 11.
  • the steering speed signal is obtained from a sensor which is attached to the steering wheel 5 and the pressure signal is obtained from a pressure sensor.
  • a pressure signal 12 is generated e.g. directly at the proportional valves 7, 8, 9. Also, directly at the proportional valves, is generated a signal 13 which indicates temperature and spool position in the proportional valves.
  • a swash plate angle which indicates a setting of the pump 6 is exported via the external CAN signal 14 to external devices and via the internal CAN signal 15 to the control system 10.
  • the control system 10 communicates with the proportional valves 7, 8, 9.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Steering Mechanism (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

La présente invention se rapporte à un système de commande électronique pour une machine mobile telle qu’un semi-remorque, une moissonneuse, etc. Le système de commande attribue un débit d’un fluide hydraulique à un actionneur de direction sur la base d’une commande de direction. Pour s’assurer que l’activité de direction est maintenue même en cas de pompe à fluide surchargée, le système de commande attribue un fluide hydraulique à différents services sur la machine mobile non seulement sur la base d’une commande opérateur, mais également en prenant en compte un débit limite, par exemple la limite de la pompe et du débit qui est nécessaire à la direction.
PCT/DK2009/000140 2008-06-11 2009-06-09 Système de commande servant à commander un écoulement de fluide depuis une source d’alimentation WO2009149712A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200800806 2008-06-11
DKPA200800806A DK200800806A (en) 2008-06-11 2008-06-11 A control system for controlling a flow of a fluid from a power source

Publications (1)

Publication Number Publication Date
WO2009149712A1 true WO2009149712A1 (fr) 2009-12-17

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Application Number Title Priority Date Filing Date
PCT/DK2009/000140 WO2009149712A1 (fr) 2008-06-11 2009-06-09 Système de commande servant à commander un écoulement de fluide depuis une source d’alimentation

Country Status (2)

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DK (1) DK200800806A (fr)
WO (1) WO2009149712A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3088279A4 (fr) * 2013-12-27 2018-01-10 KCM Corporation Système d'entraînement hydraulique
EP3832033A1 (fr) * 2019-11-26 2021-06-09 J.C. Bamford Excavators Limited Système hydraulique

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2397967A1 (fr) * 1977-07-23 1979-02-16 Zahnradfabrik Friedrichshafen Systeme de direction a double circuit pour vehicules a moteur
DE19742187A1 (de) * 1997-09-24 1999-03-25 Linde Ag Hydrostatisches Antriebssystem
US20010008068A1 (en) * 1997-11-21 2001-07-19 Komatsu Ltd. Hydraulic circuit for working vehicle
DE202004010530U1 (de) * 2004-07-06 2004-12-09 Deere & Company, Moline Hydraulischer Schaltkreis
US20060219466A1 (en) * 2005-03-31 2006-10-05 Caterpillar Inc. On-demand electro-hydraulic steering system
EP1724233A2 (fr) * 2005-05-17 2006-11-22 Nissan Motor Co., Ltd. Contrôle de l'alimentation hydraulique sous pression pour un véhicule industriel
EP1826415A2 (fr) * 2006-02-28 2007-08-29 AGCO GmbH Système hydraulique pour véhicules utilitaires, en particulier pour tracteurs agricoles

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2397967A1 (fr) * 1977-07-23 1979-02-16 Zahnradfabrik Friedrichshafen Systeme de direction a double circuit pour vehicules a moteur
DE19742187A1 (de) * 1997-09-24 1999-03-25 Linde Ag Hydrostatisches Antriebssystem
US20010008068A1 (en) * 1997-11-21 2001-07-19 Komatsu Ltd. Hydraulic circuit for working vehicle
DE202004010530U1 (de) * 2004-07-06 2004-12-09 Deere & Company, Moline Hydraulischer Schaltkreis
US20060219466A1 (en) * 2005-03-31 2006-10-05 Caterpillar Inc. On-demand electro-hydraulic steering system
EP1724233A2 (fr) * 2005-05-17 2006-11-22 Nissan Motor Co., Ltd. Contrôle de l'alimentation hydraulique sous pression pour un véhicule industriel
EP1826415A2 (fr) * 2006-02-28 2007-08-29 AGCO GmbH Système hydraulique pour véhicules utilitaires, en particulier pour tracteurs agricoles

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3088279A4 (fr) * 2013-12-27 2018-01-10 KCM Corporation Système d'entraînement hydraulique
US10202986B2 (en) 2013-12-27 2019-02-12 Kcm Corporation Hydraulic drive system
EP3832033A1 (fr) * 2019-11-26 2021-06-09 J.C. Bamford Excavators Limited Système hydraulique
GB2591725A (en) * 2019-11-26 2021-08-11 Bamford Excavators Ltd Hydraulic system
US11846089B2 (en) 2019-11-26 2023-12-19 J. C. Bamford Excavators Limited Hydraulic system
GB2591725B (en) * 2019-11-26 2024-04-24 Bamford Excavators Ltd Hydraulic system

Also Published As

Publication number Publication date
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