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
  • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• • 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
  • E02F3/34—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 with bucket-arms, i.e. a pair of arms, e.g. manufacturing processes, form, geometry, material of bucket-arms directly pivoted on the frames of tractors or self-propelled machines
  • E02F3/3405—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 with bucket-arms, i.e. a pair of arms, e.g. manufacturing processes, form, geometry, material of bucket-arms directly pivoted on the frames of tractors or self-propelled machines and comprising an additional linkage mechanism
  • E02F3/3408—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 with bucket-arms, i.e. a pair of arms, e.g. manufacturing processes, form, geometry, material of bucket-arms directly pivoted on the frames of tractors or self-propelled machines and comprising an additional linkage mechanism of the parallelogram-type
• • 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
  • E02F3/96—Dredgers; Soil-shifting machines mechanically-driven with arrangements for alternate or simultaneous use of different digging elements
  • E02F3/963—Arrangements on backhoes for alternate use of different tools
  • E02F3/964—Arrangements on backhoes for alternate use of different tools of several tools mounted on one machine
• • 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
  • E02F9/226—Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating

Definitions

• the invention relates to the field of public works vehicles, and more particularly vehicles designed to perform loader functions, and also lifting functions.
• the invention relates more particularly to an architecture of the hydraulic circuit of such machines which allows optimal operation of the machine in loader mode, for leveling functions, while maintaining a high level of safety when the machine is in mode. lifting.
• a special case of using a loader comes in for leveling operations.
• the movement of the arm relative to the chassis is left floating, so that the bucket can move by rubbing on the ground, and regularly compact the pile of soil above which it supports.
• the two chambers of the jack responsible for its orientation are generally placed in communication. The machine then operates according to a so-called "floating" control mode.
• this so-called "floating" command is obtained by a reconfiguration of the hydraulic circuit caused by the displacement of the control manipulator in a particular position.
• a manipulator comprises a lever movable in inclination so as to deliver a variable control pressure, as a function of this inclination.
• the so-called "floating" control position is generally at the end of the manipulator's travel, and therefore makes it possible to generate an overpressure in the control circuit.
• This overpressure causes the drawers of the main distributor to move so that the two chambers of the jack in question are connected.
• this same type of machine can also be used to perform lifting functions.
• the tool installed at the end of the working arm is suitable for these functions, and can for example be a pallet carrying fork or any other mechanism intended for lifting functions.
• the hydraulic circuit for controlling the jacks is generally fitted with so-called "safety" valves, intended to isolate the chamber of the jack under pressure following the weight of the load lifted.
• a safety issue can arise with equipment that can operate in both the loader mode and the lifting mode. Indeed, if, while it is in lifting mode, a driver inadvertently moves the manipulator in the so-called floating control position, then the two chambers of the jack are in communication, and the load falls on the ground. This situation is of course unacceptable for obvious security reasons.
• An object of the invention is to be able to combine both the possibility of a floating position for use as a loader, with a high level of safety.
• the invention therefore relates to a public works machine which comprises, in known manner: "work equipment including one or more arms, articulated relative to the chassis of the machine;” a set of at least a hydraulic cylinder ensuring the movement of the work equipment relative to the chassis; "a hydraulic circuit supplying these jacks according to control orders from a hydraulic manipulator.
• This machine is of the multifunction type, that is to say it is capable of operating in two distinct modes. Thus, it can operate to provide lifting functions, and also loader functions. In the latter case, the stroke of the jack causing the movement of the work equipment relative to the chassis can be made free, when the manipulator is placed in a particular position, corresponding to a so-called "floating" control position.
• the machine is characterized in that it comprises means for making the floating control position of the manipulator inactive, when the machine is operating in lifting mode.
• the invention consists in inhibiting the command to switch to the "floating" position, when the machine is operating in lifting mode. It is thus prevented that by an involuntary operation, the tool passes into floating position, which would cause the load to fall. The safety of the machine is therefore ensured in lifting mode, and performance remains high since leveling operations remain authorized with a floating bucket.
• the passage of the manipulator in the so-called floating control position generates an overpressure in the control portion of the hydraulic circuit.
• a pressure reducer inserted into the circuit is activated in order to limit or even cancel the effect of this overpressure.
• the driver places the manipulator in the so-called floating control position the corresponding overpressure is not taken into account by the hydraulic power circuit.
• a bypass valve can be arranged in parallel with the pressure reducer, so as to bypass the reducer when it is not to produce its effect.
• the pressure reducer is bypassed, so that the overpressures generated by the manipulator in the floating control position are effectively transmitted to the rest of the hydraulic circuit.
• the regulating valve is blocked, so that the pressure reducing valve performs its function, and therefore blocks the overpressure generated by the manipulator in the event that, unfortunately, the driver places the manipulator in the floating control position.
• the configuration of the hydraulic circuit in lifting or loader mode can be carried out by means of a manual selector, which controls the bypass valve located in parallel with the reducer.
• Figure 1 is a side view of a public works machine operating in loader mode.
• Figure 2 is a side view of the same machine, operating in lifting mode.
• Figure 3 is a side view of the visible part of the control manipulator.
• Figure 4 is a diagram illustrating the hydraulic circuit of such a machine.
• the machine (1) illustrated schematically in Figure 1, conventionally comprises a frame (2) receiving a cabin (3). It includes working equipment (4) at the rear allowing it to operate as an excavator, and articulated working equipment (5) at the front allowing it to perform the loader functions. More specifically, this work equipment (5) comprises an arm (6) articulated with respect to the chassis, which is movable by means of a lifting cylinder (7). At the end of the arm (6), an articulated bucket (10) is arranged which is movable relative to the arm (6) by means of a bucket cylinder (11), associated with a parallelogram system (12). Thanks to the bucket cylinder (11), it is therefore possible to ensure the inclination of the bucket.
• the bucket (5) can be replaced, as illustrated in FIG. 2, by a pallet-carrying fork (15), or various other accessories making it possible to perform the lifting functions.
• the machine can work in loader mode, allowing a particular operation, called “floating control”.
• the lifting cylinder (7) exerts no force on the arm (6), and the position of the latter is therefore free relative to its articulation with respect to the chassis (2).
• This so-called "floating" position is obtained by placing the hydraulic manipulator in a particular position.
• a hydraulic manipulator (20) comprises a lever which can be tilted forward and backward, to ensure the tilting of the arm either upwards or downwards .
• the manipulator passes into the so-called "floating control" position, when its inclination reaches a more advanced position (23).
• an additional pressure typically of the order of 27 bars, is delivered to the distributor (27).
• the fourth drawer (31) communicates the two chambers (32, 33) of the lifting cylinder (7), which therefore makes the arm floating.
• the hydraulic circuit comprises, on the fraction which supplies the chamber (33), a safety valve (36).
• This valve controlled electrically or as the illustrated form, hydraulically, makes it possible to isolate the chamber (33) from the jack (7) in the event of a rupture of a hose located downstream, in order to prevent the chamber (33) does not empty, thereby causing the load to drop.
• the overpressure generated by the over-travel of the manipulator (20) to put the bucket in the floating position is canceled when the machine operates in lifting mode.
• the hydraulic circuit is reconfigured accordingly. More precisely, as illustrated in FIG.
• a pressure reducer (40) is inserted between the manipulator (20) and the distributor (7).
• This reducer (40) delivers the maximum pressure, limited to approximately 23 bars, corresponding to the pressure delivered by the manipulator at the limit of normal stroke (22).
• This maximum pressure value of 23 bars is delivered, even when the manipulator is placed involuntarily in its overtravel zone, corresponding to the floating position of the bucket. It will be noted that this maximum value can be adjusted, thereby allowing the maximum speed of descent of the arm to be set.
• a bypass valve (41) is actuated so that it bypasses the reducer (40), and therefore allows the possible overpressure delivered by the manipulator in the floating position to act on appropriately on the distributor (31).
• This bypass valve (41) is made inactive when the selector indicates an operation in lifting mode.
• a non-return valve (42) is provided in combination with a solenoid valve (43) in order to allow the release of the safety valve when the manipulator (20) is moving in the direction of descent of the arm, or when the machine is equipped with a hydraulic suspension of the work equipment.
• the machine according to the invention allows both to benefit from operation with a floating bucket in loader mode, while ensuring optimum safety in lifting mode, since in the latter case, the floating position is neutralized.

Landscapes

• 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)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34610755

Family Applications (1)

Country Status (4)

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Family Cites Families (5)

• 2003
  • 2003-12-16 FR FR0351076A patent/FR2863634A1/fr active Pending
• 2004
  • 2004-12-09 WO PCT/FR2004/050672 patent/WO2005059258A1/fr not_active Application Discontinuation
  • 2004-12-09 EP EP04816526A patent/EP1697595A1/de not_active Withdrawn
• 2006
  • 2006-06-16 US US11/424,771 patent/US7603856B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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