EP4176139A1 - Système de commande d'un bras d'un véhicule chargeur (cwl) - Google Patents

Système de commande d'un bras d'un véhicule chargeur (cwl)

Info

Publication number
EP4176139A1
EP4176139A1 EP21737672.2A EP21737672A EP4176139A1 EP 4176139 A1 EP4176139 A1 EP 4176139A1 EP 21737672 A EP21737672 A EP 21737672A EP 4176139 A1 EP4176139 A1 EP 4176139A1
Authority
EP
European Patent Office
Prior art keywords
pump
hydraulic
accumulator
arm
actuator
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.)
Pending
Application number
EP21737672.2A
Other languages
German (de)
English (en)
Inventor
Adriano GARRAMONE
Mario GIRARDI
Andrea Gravili
Stefano Liberti
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.)
CNH Industrial Italia SpA
Original Assignee
CNH Industrial Italia SpA
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 CNH Industrial Italia SpA filed Critical CNH Industrial Italia SpA
Publication of EP4176139A1 publication Critical patent/EP4176139A1/fr
Pending legal-status Critical Current

Links

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
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • 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
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump

Definitions

  • the present invention relates the field of the control systems of the loader vehicles and in particular compact wheel loaders.
  • a wheel loader is a heavy machine used in construction to move earth or materials such as asphalt, demolition debris, snow, feed, gravel, logs, raw minerals, recycled material, rock, sand, wood chips, etc. . in or on top of another type of machinery, such as a truck, conveyor belt, feed hopper, or rail car.
  • mechanical loaders which, depending on the design and application, are called by various names, including bucket loader, front loader, front loader, loader, shovel, shovel, skip loader, wheel loader or shovel compact or Compact wheel loader.
  • the movement of the boom and shovel is controlled by the user via a joystick placed inside the cab to accommodate the operator of the work vehicle.
  • the compact loaders due to their compactness, are equipped with a prime mover, an internal combustion engine with reduced power.
  • the prime mover drives in rotation a hydraulic pump that powers the on-board actuators, including that of the arm and that of the blade and the hydrostat pump.
  • the arm for a first end, is hinged to the vehicle frame, while the bucket is hinged to a second end of the arm, opposite to the first.
  • a hydraulic motor is operatively connected with the hydraulic pump defining a so-called hydrostat, in which a hydraulic outgoing line F and a hydraulic return line R interconnect the hydraulic pump with the hydraulic motor.
  • Scope of the present invention is to improve the lifting speed of a load of a compact wheel loader, equipped with a hydrostatic transmission.
  • the basic idea of the present invention is to install a hydraulic oil accumulator arranged to be loaded with pressurized hydraulic oil during the recovery of kinetic energy during vehicle braking and arranged to power the arm actuator during its lifting.
  • the recuperator is connected exclusively to the boom lifting actuator and a processing unit allows to combine the flow of oil coming from the hydraulic pump with the flow of oil coming from the recuperator to operate the actuator of the arm as quickly as possible.
  • Figure 1 shows an example of a propulsion scheme of a work or agricultural vehicle according to the known art, closest to the present invention
  • Figure 2 shows a hydraulic diagram of a preferred implementation of the present invention
  • Figure 3 shows a compact wheel loader object of the implementation of the present invention
  • Figure 4 shows a flow chart representative of an example of operation of the system object of the present invention.
  • the same reference numbers and letters in the figures identify the same elements or components or functions.
  • second component does not imply the presence of a “first” component. These terms are in fact used as labels to improve clarity and should not be understood in a limiting or ordinal way.
  • Solid lines indicate plumbing connections, while dashed lines indicate electrical or data bus connections.
  • Figure 1 shows a schematic of the propulsion system of a compact work or agricultural vehicle.
  • the propulsion system comprises a prime mover E, generally an internal combustion engine, for example Diesel or with positive ignition.
  • a prime mover E generally an internal combustion engine, for example Diesel or with positive ignition.
  • the prime mover is configured to drive a hydrostat HY in rotation, that is a variable geometry pump HP, which feeds a hydraulic motor HM by means of a forward F and return hydraulic line R.
  • the hydraulic motor has a shaft operatively associated with a driving axle RA of the vehicle.
  • this association is achieved by means of a discrete gearbox GB.
  • the secondary shaft of the gearbox GB rotates a port of a differential DF, to guide in rotation the two drive shafts of the driving axle RA.
  • the configuration shown in Figure 1 is four-wheel drive, so that a rear driving axle RA and a front driving axle FA are identified.
  • the configuration shown by itself is known.
  • the pump and the hydraulic motor can be controlled independently of each other by means of respective electro-hydraulic valves, not shown.
  • the prime mover is in no way connected with the driving axles, except through the hydrostat. In other words, the prime mover is connected to at least one driving axle by means of only the hydrostat.
  • An engine control processing unit ECU controls the operation of the prime mover.
  • a vehicle processing unit UCM interfaces with the engine control processing unit ECU and controls the hydraulic transmission HY as well as monitors the position of vehicle control levers, buttons and commands, both in relation to vehicle movement and operation of the arm, shovel, etc. which the work vehicle is equipped with or can be equipped.
  • the existence of two distinct processing units is completely optional.
  • a single processing unit can control both the prime mover and all the other vehicle functions and monitor the activation of commands by the operator.
  • FIG 2 shows a preferred electro-hydraulic circuit HC to implement the present invention, to be implemented in a compact wheel loader CWL shown in Figure 3.
  • This diagram is, in some ways, horizontally overturned with respect to the diagram in Figure 1, since the prime mover E is shown on the right.
  • the only component extraneous to the electrohydraulic circuit is the prime mover E, which is however represented to clarify the interaction between the electro-hydraulic circuit and the prime mover.
  • the prime mover drives in rotation the hydrostat pump HP and a pump P for powering, exclusively, the hydraulic actuators of the users, including the actuator A1 for lifting (and lowering) the arm and the actuator A2 for adjusting the inclination of the tool which can be a shovel or a fork.
  • the hydraulic motor is connected directly to the wheels of the vehicle, but it is not excluded that there may be additional mechanical components, such as a discrete gearbox, differentials, and transmission shafts as shown in figure 1.
  • the prime mover E is not mechanically connected to the wheels, except through the hydrostat HY.
  • a first electro-hydraulic valve VI is interposed between the flow lines F and return R of the hydrostat, identifying two branches FI, F2 of the flow line and two branches R1 and R2 of the return line.
  • the first valve VI includes three boxes, with a stable position schematized by the central box, indicated with 2. Therefore, the notation Vl_2 indicates the configuration relating to the box number 2 of valve VI.
  • the boxes 1 and 3 are intended to perform the regenerative braking backwards and forwards respectively, in relation to the indication of the forward and return lines. In fact, it is assumed that during forward travel, the pressure in the flow line F1/F2 is greater than in the return line R1/R2.
  • the diagram refers, from a functional point of view, to the diagram of figure 1.
  • the hydraulic motor HM acts as a pump and therefore the pressure on the return line R1/R2 is higher than in the forward line F1/F2 (F).
  • the first valve VI is commanded to activate the third box Vl_3, according to which the forward line F is kept active, i.e. the branches FI and F2 remain interconnected, while the branch R2 is disconnected from the branch R1 and is connected to the line AP, which feeds the hydraulic accumulator ACC.
  • the branch R1 of the return line is connected with the hydraulic oil tank T, so that the hydraulic pump HP can suck hydraulic oil from the hydraulic oil tank T.
  • This hydraulic line AP is the only line that feeds the hydraulic accumulator.
  • the hydraulic accumulator can only be pressurized by the hydrostat and in particular by the first valve VI arranged between the hydrostat supply and return lines. If the pressure measured in the accumulator ACC by the sensor SAC exceeds the maximum pressure value Pmax with which the accumulator can be charged, then the first valve VI is deactivated and returns to the released condition Vl_2 by stopping the charging of the accumulator. In the event that, during regenerative braking, the accumulator pressure is already greater than Pmax, valve VI remains in the released position and the accumulator is not recharged. Conversely, when the vehicle travels in reverse, the hydraulic oil pressure is higher on the R1/R2 (R) return line than on the F1/F2 (F) forward line.
  • the hydraulic motor acts as a hydraulic pump. Then, the pressure present in the delivery line is used to pressurize the hydraulic accumulator ACC.
  • the first valve VI is commanded to activate the first box Vl_l, according to which the return line is kept active, i.e. the branches R1 and R2 are mutually interconnected, the branch F2 is connected to the AP line to pressurize the hydraulic accumulator ACC, while the branch FI is connected to the hydraulic oil tank T, so that the hydraulic pump HP can suck hydraulic oil from the hydraulic oil tank T.
  • a first valve CK1 is arranged on the line AP in order to prevent any pressurized oil reflux towards the hydrostat HY.
  • Pump P powers several actuators.
  • the pump P feeds the actuator A1 through a conduit PI and a third valve V3.
  • the third valve V3 includes three boxes 1 - 3.
  • the third valve connects the pipe PI with the hydraulic oil tank T, closing the opposing chambers of the actuator A1.
  • the hydraulic actuator A1 shown in figure 2 includes two opposing chambers, "Lift UP" and “Lift down” and depending on the pressurized chamber, determines the displacement of a mobile piston in extension or retraction.
  • the chambers are indicated with the same function, according to Anglo-Saxon terminology, that they perform. Therefore, the Lift up chamber determines the lifting of the arm B of the CWL vehicle .
  • the Lift down chamber determines the lowering of arm B.
  • the first box V3_l of the third valve V3 determines the connection of the pipe PI with the Lift up chamber, while the opposite Lift down chamber is connected with the hydraulic oil tank T.
  • the third box V3_3 of the third valve V3 determines the connection of the pipe PI with the Lift down chamber, while the opposite Lift up chamber is connected with the hydraulic oil tank T. Therefore when the first box V3_l is active the arm is raised, while, when the second box V33 is active the arm is lowered.
  • valve V3 may have a built-in or implicit non-return valve, this is explicitly shown as "CK3" arranged on line PI.
  • the accumulator ACC is connected exclusively to the Lift up chamber of the A1 actuator. Therefore, the accumulator is arranged to supplement the second pump exclusively to power the first actuator A1 arranged at least for lifting the arm.
  • a second valve V2 for example of the ON/OFF type, normally closed.
  • a second non-return valve CK2 is arranged between the second valve V2 and the Lift up chamber.
  • the output of the first box V3_l of the third valve and the output of the second valve V2 converge on a common duct PLU connected to the Lift Up chamber .
  • the lifting of the arm is always operated by switching the third valve so as to activate the first box V3_l.
  • the second valve V2 is enabled to switch to ON, causing an acceleration (boost) of the boom lifting .
  • the command signal is proportional to the inclination of the control lever or to the lowering of a pedal.
  • the command signal exceeds a corresponding threshold value DP which cooperates to cause the activation of the boost function.
  • step S12 it is checked whether the pressure measured in the accumulator is higher than the pressure generated by pump P to lift arm B, further to the aforementioned predetermined value DX.
  • the pressure value DX is a so-called guard value chosen in order to ensure a significant flow rate of additional hydraulic oil.
  • step S14 the second valve V2 is commanded to open, otherwise, if any of the checks S10, Sll, S12 return a negative result, then the second valve V2 is commanded to close and it starts again from steps S10, Sll.
  • steps S10 and Sll are of equal rank, in the sense that they can be performed in parallel or in succession to each other without detecting appreciable operating differences in the lifting system of the arm B.
  • step S13 is replicated in two points of the diagram only for greater clarity of the same diagram.
  • each of the three-box valves VI and V3 has the central box n.2 as a released condition, that is the spool that is activated naturally when no command is applied to the same valves. Furthermore, these three-box valves can be replaced by groups of valves which have functions equivalent to those described here.
  • the diagram in figure 4 is performed cyclically indefinitely and assumes that the Boost function is enabled.
  • Enabling the Boost function can be done in several ways. According to a preferred variant of the present invention, a first three-position slider MDA is arranged on the dashboard .
  • a first position A indicates the automatic activation of the boost function
  • a second position D deactivates the boost function
  • a third position M activates the boost function manually .
  • the vehicle can also be equipped with an hand accelerator lever HT.
  • regenerative braking can occur only when the vehicle is in motion and the accelerator lever is released.

Landscapes

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

Abstract

L'invention concerne un procédé de commande d'un bras (B) d'une pelle mécanique (CWL), la pelle mécanique étant équipée d'une transmission hydrostatique (HY) comprenant une première pompe hydraulique (HP) agencée pour alimenter uniquement un moteur hydraulique (HM), une seconde pompe (P) agencée pour alimenter des actionneurs hydrauliques de véhicule (A1, A2, ...), comprenant un premier actionneur (A1) agencé pour commander au moins le levage du bras (B), un accumulateur hydraulique (ACC) pour accumuler de l'énergie sous la forme de pression, le procédé comprenant les étapes suivantes : mise sous pression de l'accumulateur exclusivement par ledit moteur hydraulique, fonctionnant comme pompe, lors d'un freinage régénératif, ajout de ladite seconde pompe par ledit accumulateur (ACC) exclusivement pour alimenter le premier actionneur lors d'au moins le levage du bras (B).
EP21737672.2A 2020-07-01 2021-07-01 Système de commande d'un bras d'un véhicule chargeur (cwl) Pending EP4176139A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102020000015922A IT202000015922A1 (it) 2020-07-01 2020-07-01 Sistema di controllo di un braccio di una pala meccanica
PCT/EP2021/068126 WO2022003085A1 (fr) 2020-07-01 2021-07-01 Système de commande d'un bras d'un véhicule chargeur (cwl)

Publications (1)

Publication Number Publication Date
EP4176139A1 true EP4176139A1 (fr) 2023-05-10

Family

ID=72473863

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21737672.2A Pending EP4176139A1 (fr) 2020-07-01 2021-07-01 Système de commande d'un bras d'un véhicule chargeur (cwl)

Country Status (3)

Country Link
EP (1) EP4176139A1 (fr)
IT (1) IT202000015922A1 (fr)
WO (1) WO2022003085A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9096115B2 (en) * 2011-11-17 2015-08-04 Caterpillar Inc. System and method for energy recovery
CN106133332B (zh) * 2014-02-04 2018-05-25 意大利德纳股份有限公司 集成到液压混合系统内的行进和作业功能
US9809958B2 (en) * 2015-03-25 2017-11-07 Caterpillar Inc. Engine assist by recovering swing kinetic energy
JP6993899B2 (ja) * 2018-02-26 2022-01-14 川崎重工業株式会社 建設機械の油圧システム

Also Published As

Publication number Publication date
IT202000015922A1 (it) 2022-01-01
WO2022003085A1 (fr) 2022-01-06

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