WO2019179595A1 - Système hydraulique à alimentation électrique et procédé de commande d'un système hydraulique à alimentation électrique - Google Patents

Système hydraulique à alimentation électrique et procédé de commande d'un système hydraulique à alimentation électrique Download PDF

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Publication number
WO2019179595A1
WO2019179595A1 PCT/EP2018/056861 EP2018056861W WO2019179595A1 WO 2019179595 A1 WO2019179595 A1 WO 2019179595A1 EP 2018056861 W EP2018056861 W EP 2018056861W WO 2019179595 A1 WO2019179595 A1 WO 2019179595A1
Authority
WO
WIPO (PCT)
Prior art keywords
working
electric motor
working machine
user input
electrically powered
Prior art date
Application number
PCT/EP2018/056861
Other languages
English (en)
Inventor
Michael Schwall
Original Assignee
Volvo Construction Equipment Ab
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 Volvo Construction Equipment Ab filed Critical Volvo Construction Equipment Ab
Priority to PCT/EP2018/056861 priority Critical patent/WO2019179595A1/fr
Publication of WO2019179595A1 publication Critical patent/WO2019179595A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
    • E02F9/2062—Control of propulsion units
    • E02F9/207—Control of propulsion units of the type electric propulsion units, e.g. electric motors or generators
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/422—Drive systems for bucket-arms, front-end loaders, dumpers or the like
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
    • E02F9/2062—Control of propulsion units
    • E02F9/2075—Control of propulsion units of the hybrid type

Definitions

  • the invention relates to an electrically powered hydraulic system and to a method for controlling an electrically powered hydraulic system.
  • the invention is applicable on working machines within the fields of industrial construction machines or construction equipment, in particular wheel loaders. Although the invention will be described with respect to a wheel loader, the invention is not restricted to this particular machine, but may also be used in other working machines such as articulated haulers, excavators and backhoe loaders.
  • An operator of a working machine such as a wheel loader may control the operation of hydraulic functions by displacing e.g. a joystick.
  • the degree of displacement may be related to the operation speed of the hydraulic function.
  • the hydraulic pressure provided by the hydraulics of the wheel loader is typically varied. For instance, a higher pressure may enable a higher operation speed.
  • a power source for powering the hydraulic control system of a working machine may be shut down when the operator does not issue any commands for changing a state of hydraulic cylinders in the hydraulic control system, as is disclosed in US2016/0281330.
  • the power source is shut down when no user input commands have been issued for 30 seconds.
  • An object of the invention is to provide an electrically powered hydraulic system with improved energy consumptions and reduced restart delays.
  • the object is achieved by a system according to claim 1.
  • an electrically powered hydraulic system for a wheel loader comprises: an electric motor to power a working hydraulic pump to operate at least one hydraulic function of the working machine, and a control unit configured to monitor user input related to operating the working machine, and to detect a working cycle of the working machine based on detected pattern in a series of user inputs compared to pre-stored reference usage data, wherein the control unit is further configured to maintain the electric motor in an at least partly active state while the working machine is determined to be in the working cycle.
  • the present invention is based on the realization that a working machine often operates in repetitive patterns which may be related to user input for operating the propulsion and steering of the working machine but also controlling attachments of the working machine. It was realized that the patterns may be analysed in order to predict if the operator is going to provide further user input soon, and in such case the electric motor is maintained in the at least partly active state in order to avoid inconvenient restart of the electric motor.
  • the control of the electric motor is more adapted to the actual working situation of the working machine.
  • the electric motor for the hydraulic system is not simply shut off according to some fixed threshold condition. Instead, the electric motor is maintained in an at least partly active state as long as the working machine is in a working cycle.
  • a working machine that is in a working cycle may be understood as a working machine which is still operative at a work site performing operational tasks.
  • An at least partly active state of the electric motor may be that the electric motor is powered on.
  • the at least partly active state may be that the electric motor is powered on and at a working operation speed higher than an idle speed.
  • the user input that is monitored may be related to operating the hydraulic function of the working machine.
  • the user input may be provided from operator input devices in the working machine, such as e.g. joystick positions, activation buttons and switches.
  • control unit may further be configured to monitor a machine operation state as part of the user input, and to detect the working cycle further based on a series of detected machine operation states. Accordingly, detecting the working cycle may be based on detected patterns also in in user input related to machine operation states to thereby further improve the accuracy for detecting working machine working cycles.
  • Machine operation states may relate to working machine speed or travelling direction, e.g. as provided form steering input by the operator.
  • the hydraulic function may be a lift or tilt function of a working machine attachment.
  • the user input for controlling a working machine attachment is advantageously used for detecting a working cycle since the attachment is typically frequently used by the operator of the working machine.
  • control unit is configured to transition the electric motor to an at least partly in-active state when determining that the working machine is not in a working cycle, and no user input is received.
  • the electric motor may advantageously be transitioned to the at least partly in-active state when it is predicted that it will not be used, i.e. when the working machine is determined to not be in a working cycle.
  • the control unit may advantageously be configured to transition the electric motor to an at least partly in-active state based on receiving a safety warning signal.
  • the hydraulic system may be powered down in case of an emergency.
  • the electric motor is a first electric motor, wherein the electrically powered hydraulic system may further comprise a second electric motor to power the drivetrain of the wheel loader.
  • That the electric motor is in an at least partly in-active state may be that the electric motor is shut off, or in an idle state at low operational speed.
  • wheel loader comprising the electrically powered hydraulic system according to the first aspect or embodiments thereof.
  • a method for controlling the working state of an electric motor arranged to power a working hydraulic of a working machine comprising the steps of: receiving a series of user input commands related to operating the working machine, comparing the series of user input commands to pre stored reference usage data to detect a working cycle for the working machine in the series of user input commands, maintaining the electric motor in an at least partly active state when the working machine is determined to be in a working cycle.
  • the method may comprise receiving machine operation state data as part of the user input data, and to detect the working cycle further based on the machine operation state data compared to the reference usage data.
  • the method may comprise transitioning the electric motor to an at least partly in-active state when it is determined that the working machine is not in a working cycle, and no user input is received.
  • a computer program comprising program code means for performing the steps of the method according to the second aspect when said program is run on a computer.
  • a computer readable medium carrying a computer program comprising program code means for performing the steps of the method according to the second aspect when said program product is run on a computer.
  • control unit for controlling an electrically powered hydraulic system for a working machine, the control unit being configured to perform the steps of the method according to the second aspect.
  • Fig. 1 illustrates an example working machine in the form of a wheel loader
  • Fig. 2 is an overview of an example electrically powered hydraulic system
  • Fig. 3 conceptually illustrates an example working cycle
  • Fig. 4 shows a set of graphs that represent example user input versus time for the working cycle illustrated in fig. 3;
  • Fig. 5 is a flow-chart of method steps according to an embodiment of the invention.
  • Fig. 1 illustrates a working machine in the form of a wheel loader 3.
  • the wheel loader 3 comprises an electrically powered hydraulic system 1 for controlling at least one hydraulic function.
  • the hydraulic function may relate to controlling the operation speed of a wheel loader attachment such as a bucket 15, or the operation speed of the boom 16.
  • the electrically powered hydraulic system 1 of the wheel loader 3 comprises an electric motor 5 for powering a working hydraulic pump (not shown).
  • the wheel loader 3 may optionally further comprise another electric motor 34 for providing propulsion for the wheel loader 3.
  • the wheel loader 3 may be an all electric wheel loader 3 particularly suitable for indoor operation.
  • Fig. 2 is an overview of the electrically powered hydraulic system 1 .
  • the system comprises an operator input device which may be in the form of a joystick 19 which allow the operator 4 to control the operation of a hydraulic function 7 via input commands using the joystick 19.
  • operator input devices are a drive pedal 17, and a steering wheel 21.
  • User input may be provided from any one of the joystick 19, the drive pedal, or the steering wheel 21 , as a result of operation of the respective input device.
  • An electric control unit 1 1 is configured to receive user input control signals form the input device 19, and to interpret the signals and control the hydraulic function 7 by varying a flow of hydraulic fluid to the hydraulic function 7.
  • the electric control unit 1 1 is configured to control the operation speed of an electric motor 5 which is arranged to power a working hydraulic pump 13.
  • the working hydraulic pump 13 is arranged to provide a flow of hydraulic fluid to an electronically controlled control valve 25.
  • the electronically controlled control valve 25 is configured to distribute the hydraulic fluid to the hydraulic functions 7 according to instructions provided from the electric control unit 1 1 .
  • the user input signals received by the electric control unit 1 1 may indicate that a first hydraulic function and a second hydraulic function are desirable to operate.
  • the electric control unit 1 1 provides an instruction to the electronically controlled control valve 25 to open the respective valve of the electronically controlled control valve 25 to the first and second hydraulic functions according to the user input signals.
  • the electronically controlled control valve 25 may comprise several valves.
  • the electronically controlled control valve 25 may be a so called main control valve (MCV) for the hydraulic system of the working machine.
  • MCV main control valve
  • the electronic control unit 1 1 may control the variation in flow of hydraulic fluid by varying the electric motor rotational speed and/or by controlling the control valve 25, according to displacement of the operator input device 19. Accordingly, the electronic control unit 1 1 monitors user input related to operating the wheel loader, either user input related to controlling propulsion (e.g. speed and travel direction), and/or user input related to controlling the hydraulic function (e.g. lift, lower, tilt of an attachment).
  • propulsion e.g. speed and travel direction
  • hydraulic function e.g. lift, lower, tilt of an attachment
  • Fig. 3 conceptually illustrates an example working cycle for a wheel loader in which the wheel loader 3 travels between an intermediate location A, a pick up location B and a drop off location C. From the intermediate location A, the wheel loader 3 travels forward 31 , and turns left 32 and travels towards location B. While at location B, the wheel loader may pick up material (such as gravel) via a series of user inputs, such as lower the boom and tilt a bucket, travel forward to pick up material, while at the same time tilt the bucket back and raise the boom. Subsequently, the wheel loader travels rearwards 34, and subsequently, turns 35 while reversing back to a location at least near the location A.
  • material such as gravel
  • the wheel loader 3 subsequently travels forward 36 and turns right 37 in order to travel towards the drop off location C.
  • the wheel loader may drop off material from its bucket via a series of user inputs, such as tilt the bucket back and forth.
  • the wheel loader 3 may reverse 38 and turn 39 while reversing to return to a location at least near location A.
  • fig 3 only shows an example working cycle for understanding of the inventive concept.
  • a working cycle may generally comprise fewer or more events or events in another sequence than the depicted events in fig. 3.
  • a working cycle may comprise events only related to operating the hydraulic functions such as lifting the boom and/or tilting the bucket.
  • Fig. 4 illustrates graphs 41 , 42, 43, and 44 conceptually showing representations of input commands versus time for the working cycle shown in fig. 3.
  • the user input relates to hydraulic functions such as bucket tilt (graph 41 ) and boom raise/lower (graph 42), and to machine operation states such as propulsion (graph 43) and steering (graph 44) of the wheel loader 3.
  • Some of the reference numerals of the user input commands in fig. 4 refer to the wheel loader operation described with reference to fig. 3. Accordingly, starting from location A in fig. 3, a first user input 31 is to control the wheel loader to drive forward. Further, while the wheel loader is travelling forward, a user input 32 for steering the wheel loader left is received by the electronic control unit 1 1 (see fig. 2).
  • a series of user inputs may be performed in order to pick up material at the location B.
  • the user provides user input 45 to, while travelling forward 31 , lower the boom 45 such that the bucket approaches the ground, and user input 46 to tilt the bucket in a first direction such that the opening of the bucket faces the material to be picked up.
  • the operator of the wheel loader provides user input 47 to tilt the bucket in an opposite (second) direction to direct the bucket opening upwards to collect material.
  • the operator provides user input 48 to raise the boom from the ground.
  • user input 34 is provided to reverse the wheel loader away from the location B, and user input 35 to turn the wheel loader left while reversing towards a location at least near the location A.
  • user input 36 is provided to the electronic control unit 1 1 in order to control the wheel loader to travel forward.
  • user input 37 is provided for turning the wheel loader right while travelling forward. In this way, the wheel loader is controlled to travel towards drop off location C.
  • the operator desires to drop off the material picked up at location B. Therefore, the operator causes user input 49 in order to tilt the bucket to a configuration such that the material falls out from the bucket. Subsequently, user input 38 for reversing the wheel loader away from location C, and user input 39 for turning the wheel loader right is received.
  • the wheel loader 3 has again reached at least near location A and the working cycle is completed and may be initiated again.
  • a series of user input such as the user inputs described with reference to fig. 4, or at least part of the user inputs described with reference to fig. 4 is analysed in order to detect a pattern in the user input data that corresponds to a working cycle. For instance, it may be sufficient to analyse the user input related to operating the boom and bucket.
  • the series of user input may be analysed using pattern recognition methods trained on previously received reference usage data stored in a memory of the electronic control unit 1 1.
  • An algorithm for detecting a working cycle such as load and carry or pallet handling may be based on characterizing each working cycle as a distinct series of events, i.e. a pattern.
  • An event e.g. driving backward, lifting bucket or tilting bucket is detected using measured data.
  • This data comprises operator inputs like joystick usage and sensor values received from dedicated measuring points in the machine e.g. tilt angle or drive shaft speed.
  • the events need to be low complex and robust against operation disturbance.
  • pattern recognition techniques e.g. string mating
  • the series of detected events will be matched to a predefined cycle. This predefinition is based on engineering knowledge and stored in a persistent memory of the electronic control unit.
  • the algorithm is part of the application software on the electronic control unit.
  • the electric motor is maintained in the at least partly active state by the electric control unit 1 1.
  • the user input may be generated from control circuitry associate with each of the operator input devices. For instance, when the operator requests boom raise/lower, a user input control signal is sent from the control circuitry of the respective operator input device (e.g. joystick 19) to the electronic control unit 1 1 which controls the boom via the hydraulic fluid pressure.
  • the electronic control unit may further be configured to detect a pattern in the received user input control signals.
  • Fig. 5 is a flow-chart of method steps according to an embodiment of the invention.
  • a series of user input commands is received related to operating the working machine.
  • the series of user input commands is compared to pre stored reference usage data to detect a working cycle for the working machine in the series of user input commands. While it is determined that the working machine is in the working cycle the electric motor is maintained S106 in an at least partly active state. However, the electric motor is transitioned S108 to an at least partly in-active state when it is determined that the working machine is not in a working cycle, and no user input is received.
  • the electronic control unit 1 1 may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device.
  • the electronic control unit comprises electronic circuits and connections (not shown) as well as processing circuitry (not shown) such that the electronic control unit can communicate with different parts of the working machine such as the brakes, suspension, driveline, in particular an electrical engine, an electric machine, a clutch, and a gearbox in order to at least partly operate the working machine.
  • the electronic control unit may comprise modules in either hardware or software, or partially in hardware or software and communicate using known transmission buses such as CAN-bus and/or wireless communication capabilities.
  • the processing circuitry may be a general purpose processor or a specific processor.
  • the electronic control unit comprises a non-transitory memory for storing computer program code and data upon.
  • the skilled addressee realizes that the electronic control unit may be embodied by many different constructions.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

La présente invention concerne un système hydraulique à alimentation électrique (1) pour une machine de travail (3), le système hydraulique à alimentation électrique comprenant : un moteur électrique (5) pour entraîner une pompe hydraulique de travail (13) pour faire fonctionner au moins une fonction hydraulique (7) de la machine de travail, et une unité de commande (11) configurée pour surveiller une entrée utilisateur connexe au fonctionnement de la machine de travail, et pour détecter un cycle de travail de la machine de travail sur la base d'un motif détecté dans une série d'entrées utilisateur par rapport à des données d'utilisation de référence préstockées, l'unité de commande étant en outre configurée pour maintenir le moteur électrique dans un état au moins partiellement actif alors qu'il est déterminé que la machine de travail est dans le cycle de travail.
PCT/EP2018/056861 2018-03-19 2018-03-19 Système hydraulique à alimentation électrique et procédé de commande d'un système hydraulique à alimentation électrique WO2019179595A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2018/056861 WO2019179595A1 (fr) 2018-03-19 2018-03-19 Système hydraulique à alimentation électrique et procédé de commande d'un système hydraulique à alimentation électrique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2018/056861 WO2019179595A1 (fr) 2018-03-19 2018-03-19 Système hydraulique à alimentation électrique et procédé de commande d'un système hydraulique à alimentation électrique

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4155466A1 (fr) * 2021-09-24 2023-03-29 Volvo Construction Equipment AB Procédé de commande de machine de travail, système de commande et machine de travail

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1291467A1 (fr) * 2000-05-23 2003-03-12 Kobelco Construction Machinery Co., Ltd. Engin de construction
US20140083089A1 (en) * 2012-09-21 2014-03-27 Harnischfeger Technologies, Inc. Energy management system for machinery performing a predictable work cycle
US20160281330A1 (en) 2015-03-25 2016-09-29 Caterpillar Inc. Hydraulic System Recovering Swing Kinetic and Boom Potential Energy

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1291467A1 (fr) * 2000-05-23 2003-03-12 Kobelco Construction Machinery Co., Ltd. Engin de construction
US20140083089A1 (en) * 2012-09-21 2014-03-27 Harnischfeger Technologies, Inc. Energy management system for machinery performing a predictable work cycle
US20160281330A1 (en) 2015-03-25 2016-09-29 Caterpillar Inc. Hydraulic System Recovering Swing Kinetic and Boom Potential Energy

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4155466A1 (fr) * 2021-09-24 2023-03-29 Volvo Construction Equipment AB Procédé de commande de machine de travail, système de commande et machine de travail

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