WO2020065915A1 - Chargeuse montée sur roues - Google Patents

Chargeuse montée sur roues Download PDF

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Publication number
WO2020065915A1
WO2020065915A1 PCT/JP2018/036237 JP2018036237W WO2020065915A1 WO 2020065915 A1 WO2020065915 A1 WO 2020065915A1 JP 2018036237 W JP2018036237 W JP 2018036237W WO 2020065915 A1 WO2020065915 A1 WO 2020065915A1
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WO
WIPO (PCT)
Prior art keywords
vehicle body
lift arm
wheel loader
detector
angle
Prior art date
Application number
PCT/JP2018/036237
Other languages
English (en)
Japanese (ja)
Inventor
幸次 兵藤
正規 吉川
山下　将司
田中　哲二
祐樹 抜井
Original Assignee
日立建機株式会社
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 日立建機株式会社 filed Critical 日立建機株式会社
Priority to JP2020547792A priority Critical patent/JP7169361B2/ja
Priority to PCT/JP2018/036237 priority patent/WO2020065915A1/fr
Publication of WO2020065915A1 publication Critical patent/WO2020065915A1/fr

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Classifications

    • 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
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/4008—Control of circuit pressure

Definitions

  • the present invention relates to a wheel loader that performs a cargo handling operation.
  • the balance between the traction force (running driving force) and the excavating force of the front working machine becomes important. . If the traction force is too large for the digging force of the front work machine, the wheels slip when the bucket is pushed into the digging object and the lift arm is operated to lift the bucket upward. On the contrary, the traction force becomes small, and it becomes difficult for a load such as earth and sand to enter the bucket. Further, in this case, when the bucket is pushed into the object to be excavated, the reaction force acting on the lift arm increases, and the reaction force acts as a resistance, so that the bucket or the lift arm may not be lifted upward.
  • Patent Literature 1 discloses, as a traveling hydraulic circuit, a variable displacement traveling hydraulic pump driven by an engine and a variable displacement traveling hydraulic motor driven by pressure oil from the hydraulic pump.
  • a wheel loader using an HST circuit in which a traveling hydraulic pump and a traveling hydraulic motor are connected in a closed circuit by a pair of main pipelines is disclosed.
  • the maximum traction force of the HST motor is set to the upper limit value so that the maximum traction force reaches the upper limit. This makes it possible to take in sufficient load into the bucket.
  • the maximum tilting of the HST motor is limited to about 50 to 70% of the upper limit value, so that the traction force becomes too large. In this way, the balance between the lifting operation force of the lift arm (the digging force of the front working machine) and the traction force is favorably maintained, and the lifting operation of the loaded bucket is facilitated.
  • the operator switches the manual switch to limit the maximum tilt of the HST motor during the excavation operation in the L mode, the N mode, and the P mode according to the type of the ground and the road surface condition. Adjustment can be made in three stages.
  • ⁇ ⁇ Excavation work by a wheel loader may be performed while climbing up the ground in addition to the case where the vehicle body is installed on a flat ground. Specifically, the wheel loader moves forward on a steep slope while operating the lift arm in the upward direction, excavates the slope, and discharges the load to the top of the ground. While the wheel loader is climbing a hill, a force corresponding to (weight of vehicle body ⁇ sin ⁇ ) acts on the vehicle body toward the rear of the slope. Therefore, when the excavation operation is performed on a slope, the tractive force is reduced by (the weight of the vehicle body ⁇ sin ⁇ ) as compared with the case where the excavation operation is performed while the vehicle body is installed on a flat ground.
  • the wheel loader described in Patent Literature 1 is based on the premise that an excavation operation is performed in a state where a vehicle body is installed on a flat ground. Therefore, when the wheel loader performs an excavation operation while climbing the ground, a tractive force is applied. Is insufficient, and it is not possible to climb the hill while operating the lift arm upward. It is conceivable that the traction force is increased by switching to the P mode in which the maximum tilt limit value of the HST motor at the time of the excavation operation is the largest by a manual switch. It is necessary to switch the manual switch to the P mode.
  • an object of the present invention is to provide a wheel loader capable of improving work efficiency even when performing an excavation operation while climbing a hill.
  • the present invention provides an engine, a variable displacement traveling hydraulic pump driven by the engine, and a driving force of the engine connected to the traveling hydraulic pump in a closed circuit.
  • a front working machine having a lift arm provided at the front of the vehicle body and rotatable in a vertical direction, and driven by the engine to the front working machine.
  • the vehicle loader further includes an inclination state detector for detecting an inclination state of the vehicle body, wherein the controller is configured to control a traveling state detected by the traveling state detector, and to raise the lift arm detected by the operation amount detector. Based on the operation amount and the tilt state detected by the tilt state detector, it is determined whether or not a specific condition for specifying that the vehicle body is in an excavation state while climbing a slope is satisfied, and the specific condition is satisfied. , Wherein the maximum traction force of the vehicle body is set to be higher than the maximum traction force when the vehicle body is installed on a flat ground and is in an excavation state.
  • the work efficiency can be improved even when the digging operation is performed while climbing a hill.
  • FIG. 2 is a diagram illustrating a hydraulic circuit and an electric circuit related to a traveling drive of the wheel loader according to the first embodiment of the present invention.
  • 5 is a graph showing a relationship between an accelerator pedal depression amount and a target engine rotation speed.
  • FIG. 3 is a functional block diagram illustrating functions of a controller according to the first embodiment.
  • 6 is a flowchart illustrating a flow of a process executed by the controller according to the first embodiment.
  • FIG. 9 is a diagram illustrating a hydraulic circuit and an electric circuit related to traveling drive of the wheel loader according to the second embodiment. It is a flow chart which shows a flow of processing performed by a controller concerning a 2nd embodiment. It is a graph which shows the relation between the discharge pressure of the hydraulic pump for work equipment and the maximum displacement of the HST motor in the second embodiment. It is a flow chart which shows a flow of processing performed by a controller concerning a 3rd embodiment. It is a graph which shows the relation between the discharge pressure of the hydraulic pump for work equipment and the maximum displacement of the HST motor in the third embodiment.
  • FIG. 1 is a side view showing the appearance of the wheel loader 1 according to each embodiment of the present invention.
  • the wheel loader 1 includes a vehicle body including a front frame 1A and a rear frame 1B, and a front work machine 2 provided at a front portion of the vehicle body.
  • the wheel loader 1 is an articulated work vehicle that is steered by turning a vehicle body near the center.
  • the front frame 1A and the rear frame 1B are rotatably connected in the left and right direction by a center joint 10, and the front frame 1A is bent in the left and right direction with respect to the rear frame 1B.
  • FIG. 1 shows only the left front wheel 11A and the rear wheel 11B of the pair of left and right front wheels 11A and the rear wheels 11B.
  • the “front wheel 11A and the rear wheel 11B” may be simply referred to as “wheels 11A and 11B”.
  • a counter weight 14 are provided.
  • the operator cab 12 is disposed at the front
  • the counterweight 14 is disposed at the rear
  • the machine room 13 is disposed between the operator cab 12 and the counterweight 14.
  • the front working machine 2 includes a lift arm 21 attached to the front frame 1A, a pair of lift arm cylinders 22 that expand and contract to rotate the lift arm 21 in the vertical direction with respect to the front frame 1A, A bucket 23 attached to the tip end, a bucket cylinder 24 that expands and contracts to rotate the bucket 23 in the vertical direction with respect to the lift arm 21, and a bucket 23 and the bucket cylinder that are rotatably connected to the lift arm 21. 24, and a plurality of pipes (not shown) for guiding pressure oil to a pair of lift arm cylinders 22 and bucket cylinders 24.
  • FIG. 1 only the lift arm cylinder 22 arranged on the left side of the pair of lift arm cylinders 22 is shown by a broken line.
  • the lift arm 21 rotates upward when the rod 220 of each lift arm cylinder 22 extends, and rotates downward when each rod 220 contracts.
  • the bucket 23 tilts (rotates upward with respect to the lift arm 21) when the rod 240 of the bucket cylinder 24 extends, and dumps (rotates downward with respect to the lift arm 21) when the rod 240 contracts. I do.
  • the wheel loader 1 is a loading / unloading vehicle for performing a loading / unloading operation, for example, in an open pit mine or the like, for excavating earth and sand, minerals, and the like, and loading the dumped truck and the like.
  • the wheel loader 1 In the excavation work, in addition to the case where the bucket 23 rushes into the object to be excavated to excavate earth and sand, minerals, and the like in a state where the vehicle body is installed on a flat ground, the wheel loader 1 travels forward on the slope of the object to be excavated. In some cases, the bucket 23 excavates the slope.
  • the case where the wheel loader 1 performs the excavation operation while climbing a hill is referred to as “scraping work”.
  • the "pick-up work" will be specifically described with reference to FIGS.
  • FIG. 2A is an explanatory view for explaining the lifting operation of the wheel loader 1
  • FIG. 2B is an explanatory diagram for explaining the operation of the lift arm 21 during the lifting operation.
  • FIG. 3A is a graph showing a relationship between the detected body tilt angle and the converted value of the vehicle body tilt angle
  • FIG. 3B is a graph showing a relationship between the detected angle of the lift arm and the converted value of the vehicle body tilt angle. .
  • the wheel loader 1 travels on a flat ground toward the ground 100 to be excavated, and operates the front work machine 2 while climbing the ground 100 as it is to cut the slope. Excavate. Then, the earth and sand, minerals, and the like that have been excavated and piled in the bucket 23 are discharged on the top of the ground 100, and then the wheel loader 1 returns to the original place on the slope while moving backward.
  • the operator operates to lift the lift arm 21 upward as it goes up the slope.
  • the lift arm 21 When the wheel loader 1 is traveling on level ground (state (X) shown in FIG. 2A), the lift arm 21 is at the lowest position in the movable range in the vertical direction (the position shown in FIG. 2B). (X)), when the wheel loader 1 starts climbing the ground 100 (state (Y) shown in FIG. 2A), the lift arm 21 is in the horizontal posture (the position shown in FIG. 2B). (Y), just before the wheel loader 1 discharges the load in the bucket 23 to the top of the ground 100 (state (Z) shown in FIG. 2A), the lift arm 21 is lifted upward. It is at the cut position, that is, the highest position (the position (Z) shown in FIG. 2B) in the vertical movable range.
  • the position of the lift arm 21 does not need to be exactly the horizontal position, but may be a position slightly lower than the accurate horizontal position as shown in the position (Y) in FIG. That is, the “horizontal posture” of the lift arm 21 includes an error in the vertical direction from the accurate horizontal position.
  • Whether or not the wheel loader 1 is climbing a slope can be determined by using a traveling state detector that detects the traveling state of the vehicle body and an inclination state detector that detects the inclination of the vehicle body.
  • a traveling state detector that detects the traveling state of the vehicle body
  • an inclination state detector that detects the inclination of the vehicle body.
  • a vehicle body tilt angle sensor 130 as a vehicle body tilt angle detector that detects a vehicle body tilt angle ⁇
  • a lift as a lift arm angle detector that detects the angle ⁇ of the lift arm 21
  • An arm angle sensor 211 is used.
  • the body tilt angle sensor 130 is attached to the rear frame 1B as shown in FIG. 2A, and the lift arm angle sensor 211 is attached to the base of the lift arm 21 as shown in FIG. I have.
  • the lift arm When excavating in a state where the vehicle body is installed on a flat ground, only the bucket 23 is tilted. However, when performing a lifting operation, as described above, in addition to the tilt operation of the bucket 23, the lift arm is used. In order to move the vehicle body 21 upward, the inclination state of the vehicle body can also be detected by detecting the angle ⁇ of the lift arm 21. In a work vehicle such as the wheel loader 1, it is necessary to use a strong vehicle body inclination angle sensor 130 having a strong seismic resistance, which is relatively expensive. Is installed as a standard, it is possible to use the lift arm angle sensor 211 without increasing the cost.
  • the vehicle body inclination angle sensor 130 When the vehicle body inclination angle sensor 130 is used, as shown in FIG. 3A, when the vehicle body inclination detection angle ⁇ detected by the vehicle body inclination angle sensor 130 is 0 or more and less than a predetermined angle threshold ⁇ s, (0 ⁇ ⁇ ⁇ s) The converted vehicle body tilt angle value is set to 0, and when the detected vehicle body tilt angle ⁇ becomes equal to or larger than a predetermined angle threshold ⁇ s ( ⁇ ⁇ ⁇ s), the converted vehicle body tilt angle value increases from 0 in a positive direction.
  • the lift arm angle sensor 211 When the lift arm angle sensor 211 is used, as shown in FIG. 3B, if the lift arm detection angle ⁇ detected by the lift arm angle sensor 211 is equal to or greater than 0 and less than a predetermined angle threshold ⁇ s, (0 ⁇ ⁇ ⁇ s) The vehicle body inclination angle conversion value is set to 0, and when the lift arm detection angle ⁇ becomes equal to or larger than a predetermined angle threshold ⁇ s ( ⁇ ⁇ ⁇ s), the vehicle body inclination angle conversion value increases from 0 in a positive direction.
  • the “predetermined angle thresholds ⁇ s, ⁇ s” are angles corresponding to when the front wheel 11A approaches the slope of the ground 100, respectively. Therefore, when the vehicle body inclination detection angle ⁇ is equal to or greater than 0 and less than a predetermined angle threshold ⁇ s (0 ⁇ ⁇ ⁇ s), and when the lift arm detection angle ⁇ is equal to or greater than 0 and less than a predetermined angle threshold ⁇ s ( 0 ⁇ ⁇ ⁇ s) is the state (X) shown in FIGS. 2A and 2B, respectively.
  • the “first angle thresholds ⁇ 1, ⁇ 1” are angles corresponding to when the wheel loader 1 starts climbing the ground 100, that is, when the lift arm 21 takes a horizontal posture.
  • the vehicle body inclination angle sensor 130 When the vehicle body inclination angle sensor 130 is used, as shown in FIG. 3A, it is also possible to detect the vehicle body inclination angle when the wheel loader 1 is moving down the slope while moving backward. is there.
  • the inclination angle ⁇ of the ground 100 is, for example, 15 ° to 25 °, and the slope of the ground 100 is relatively steep.
  • a traction force (driving driving force) required when performing an excavation operation in a state where the vehicle body is installed on a flat ground is F
  • the traction force when performing an excavation operation on a slope such as a lifting work is (F ⁇ W sin ⁇ )
  • the traction force is reduced by W sin ⁇ as compared with the case where the excavation operation is performed in a state where the vehicle body is installed on a flat ground.
  • FIG. 4 is a diagram showing a hydraulic circuit and an electric circuit of the wheel loader 1 according to the first embodiment.
  • FIG. 5 is a graph showing the relationship between the accelerator pedal depression amount and the target engine speed.
  • 6A is a graph showing the relationship between the engine rotation speed and the displacement of the HST pump 41
  • FIG. 6B is a graph showing the relationship between the engine rotation speed and the input torque of the HST pump 41
  • FIG. 4 is a graph showing the relationship between the engine rotation speed and the discharge flow rate of the HST pump 41.
  • the wheel loader 1 includes an HST-type traveling drive device having a closed-circuit hydraulic circuit.
  • the HST-type traveling drive device stores the engine 3 and hydraulic oil.
  • a hydraulic oil tank 40 an HST pump 41 as a traveling hydraulic pump driven by the engine 3, an HST charge pump 41A for replenishing pressure oil for controlling the HST pump 41, and a pair of HST pumps 41
  • An HST motor 42 as a traveling hydraulic motor connected to the HST pump 41 in a closed circuit via 400L and 400R, a forward / reverse switching valve 43 for switching the forward / backward movement of the vehicle body, and an HST pump 41, an HST motor 42, and the like. It has a controller 5 for controlling each device.
  • the HST pump 41 is a swash plate type or oblique axis type variable displacement hydraulic pump whose displacement is controlled according to the tilt angle.
  • the tilt angle is adjusted by a tilt cylinder 44 driven by the action of pressure oil discharged from the HST charge pump 41A.
  • the HST motor 42 is a swash plate type or oblique axis type variable displacement hydraulic motor whose displacement is controlled according to the tilt angle, and transmits the driving force of the engine 3 to the wheels 11A and 11B.
  • the tilt angle is adjusted by the regulator 420 according to the command signal output from the controller 5.
  • the HST type traveling drive device first, when an operator depresses an accelerator pedal 61 provided in the cab 12, the engine 3 rotates, and the HST pump 41 is driven by the driving force of the engine 3.
  • the HST charge pump 41A is also driven by the driving force of the engine 3, and the pressure oil discharged from the HST charge pump 41A is guided to the tilt cylinder 44 via the forward / reverse switching valve 43.
  • the forward / reverse switching valve 43 is provided between the HST charge pump 41A and the tilt cylinder 44.
  • the forward / reverse switching valve 43 is connected to a discharge line 800 connected to the discharge side of the HST charge pump 41A by a pair of main lines 800A and 800B. Further, the forward / reverse switching valve 43 is connected to left and right oil chambers 44L, 44R of the tilt cylinder 44 by a pair of pilot lines 800L, 800R.
  • the forward / reverse switching valve 43 has a forward position 43A for moving the vehicle forward, a reverse position 43B for moving the vehicle backward, and a neutral position 43N for stopping the vehicle, and a forward / backward switching lever provided in the cab 12. 62 is operated.
  • the forward / reverse switching valve 43 switches to the forward position 43A
  • the upstream pressure of the throttle 401 acts on the oil chamber 44L on the left side of the tilt cylinder 44, and the downstream side of the throttle 401 on the right oil chamber 44R. Pressure acts.
  • the rod of the tilting cylinder 44 operates rightward in FIG. 4 due to the pressure difference generated between the left and right oil chambers 44L and 44R.
  • the tilt angle of the HST pump 41 increases, and the hydraulic oil from the HST pump 41 is guided to the HST motor 42 through the pipeline 400L, and the HST motor 42 rotates forward to move the vehicle forward.
  • the forward / reverse switching valve 43 when the forward / reverse switching valve 43 is switched to the reverse position 43B, the downstream pressure of the throttle 401 acts on the oil chamber 44L on the left side of the tilt cylinder 44, and the upstream side of the throttle 401 on the oil chamber 44R on the right side. Pressure acts. Then, the rod of the tilt cylinder 44 operates to the left in FIG. 4 due to the pressure difference generated between the left and right oil chambers 44L and 44R. As a result, the tilt angle of the HST pump 41 increases, and the hydraulic oil from the HST pump 41 is guided to the HST motor 42 through the pipeline 400R, and the HST motor 42 reverses and the vehicle moves backward.
  • the output torque from the HST motor 42 is transmitted to the front wheel 11A and the rear wheel 11B via the axle 15, and the wheel loader 1 To run. Therefore, the output torque of the HST motor 42 becomes a driving force for driving the wheel loader 1, that is, a traction force of the vehicle body.
  • the rotation speed of the engine 3 is adjusted by the amount of depression of the accelerator pedal 61, and the discharge amount of the HST charge pump 41A connected to the engine 3 is proportional to the rotation speed of the engine 3. Therefore, the differential pressure across the throttle 401 is proportional to the rotation speed of the engine 3, and the tilt angle of the HST pump 41 is also proportional to the rotation speed of the engine 3.
  • the depression amount of the accelerator pedal 61 is detected by a depression amount sensor 610 attached to the accelerator pedal 61.
  • the number of revolutions of the engine 3 is controlled in accordance with the target engine speed in accordance with the stepping amount detected by the stepping amount sensor 610.
  • the depression amount of the accelerator pedal 61 is proportional to the target engine rotation speed, and the target engine rotation speed increases as the depression amount of the accelerator pedal 61 increases. Then, when the depression amount of the accelerator pedal 61 becomes S2, the target engine rotation speed becomes the maximum rotation speed Nmax1.
  • the range of the depression amount of the accelerator pedal 61 in the range of 0 to S1 is the target engine rotation speed at the predetermined minimum rotation speed Nmin regardless of the depression amount of the accelerator pedal 61. It is set as a fixed dead zone.
  • the target engine rotation speed is maintained at the maximum target engine rotation speed Nmax regardless of the depression amount of the accelerator pedal 61. Is set to These ranges can be arbitrarily set and changed.
  • the rotation speed N of the engine 3 is proportional to the displacement q of the HST pump 41, and the rotation speed of the engine 3 is N1.
  • the displacement increases from 0 to a predetermined value qc.
  • the displacement of the HST pump 41 is constant at a predetermined value qc regardless of the engine speed.
  • input torque displacement volume ⁇ discharge pressure
  • the rotation speed N of the engine 3 is proportional to the input torque T of the HST pump 41, and the rotation speed of the engine 3 is N1.
  • the input torque increases from 0 to a predetermined value Tc as the speed increases from 0 to N2.
  • the input torque of the HST pump 41 is constant at a predetermined value Tc regardless of the engine speed.
  • the rotation speed N of the engine 3 increases, the discharge flow rate Q of the HST pump 41 increases, and the flow rate of the pressure oil flowing from the HST pump 41 into the HST motor 42 increases, so that the rotation speed of the HST motor 42 increases and the vehicle speed increases. Is faster.
  • the vehicle speed is detected by the motor rotation speed sensor 72 as the rotation speed of the HST motor 42 (see FIG. 4).
  • the wheel loader 1 can smoothly start and stop with less impact. Become.
  • the pressure oil discharged from the HST charge pump 41A is also guided to the pipelines 400L and 400R through the throttle 401 and the check valves 402A and 402B.
  • the downstream pressure of the throttle 401 is limited by a charge relief valve 403 provided on a pipe connecting the forward / reverse switching valve 43 and the hydraulic oil tank 40, and the maximum pressure of the pipes 400 ⁇ / b> L and 400 ⁇ / b> R is limited by a relief valve 404. Is done.
  • the HST traveling drive device is provided with a high-pressure selection valve 405 that selects the higher one of the pipeline pressures of the pipelines 400L and 400R that guide the hydraulic oil from the HST pump 41 to the HST motor 42.
  • the pressure selected by the high-pressure selection valve 405 is input to the controller 5.
  • the vehicle body tilt angle sensor 130 is used as a tilt state detector that detects the vehicle body tilt state, and the vehicle body tilt detection angle ⁇ detected by the vehicle body tilt angle sensor 130 is input to the controller 5. .
  • FIG. 7 is a diagram illustrating a hydraulic circuit related to driving of the front work machine 2.
  • FIG. 8 is a graph showing the relationship between the discharge pressure of the working machine hydraulic pump 45 and the opening area of the spool.
  • the wheel loader 1 includes a working machine hydraulic pump 45 driven by the engine 3 to supply hydraulic oil to the front working machine 2, and each of the lift arm cylinder 22 and the bucket cylinder 24. Operate the lift arm 21 and a control valve 46 provided between the work machine hydraulic pump 45 and controlling the flow of pressurized oil supplied from the work machine hydraulic pump 45 to the lift arm cylinder 22 and the bucket cylinder 24, respectively. And a bucket operation lever 230 for operating the bucket 23.
  • a fixed hydraulic pump is used as the working machine hydraulic pump 45, and is connected to the control valve 46 via a first conduit 801 as shown in FIG.
  • the discharge pressure from the working machine hydraulic pump 45 is detected by a discharge pressure sensor 75 provided on the first conduit 801, and a signal related to the detected discharge pressure is input to the controller 5.
  • the discharge pressure sensor 75 is an example of a discharge pressure detector that detects the discharge pressure of the working machine hydraulic pump 45.
  • the lift arm operating lever 210 and the bucket operating lever 230 are both modes of an operating device for operating the front work machine 2, and are provided in the cab 12 (see FIG. 1). For example, when the operator operates the lift arm operation lever 210, a pilot pressure proportional to the operation amount is generated as an operation signal.
  • the generated pilot pressure is guided to a pair of pilot lines 64L and 64R connected to a pair of pressure receiving chambers of the control valve 46, and acts on the control valve 46.
  • the spool in the control valve 46 strokes according to the pilot pressure, and the direction and the flow rate of the hydraulic oil are determined.
  • the control valve 46 is connected to a bottom chamber of the lift arm cylinder 22 by a second pipe 802, and connected to a rod chamber of the lift arm cylinder 22 by a third pipe 803.
  • Hydraulic oil discharged from the working machine hydraulic pump 45 is guided to the first pipeline 801 and is guided to the second pipeline 802 or the third pipeline 803 via the control valve 46.
  • the hydraulic oil is led to the second conduit 802
  • it flows into the bottom chamber of the lift arm cylinder 22, whereby the rod 220 of the lift arm cylinder 22 is extended and the lift arm 21 is raised.
  • the hydraulic oil is guided to the third conduit 803, it flows into the rod chamber of the lift arm cylinder 22, the rod 220 of the lift arm cylinder 22 contracts, and the lift arm 21 descends.
  • each of the lift arm operation lever 210 and the bucket operation lever 230 is a hydraulic lever, but an electric lever may be used.
  • a current value corresponding to the operation amount is used as an operation signal. Is generated as
  • the pilot pressure is detected by a pilot pressure sensor 76 as an operation signal sensor for detecting an operation signal according to the lift operation amount of the lift arm 21.
  • the pilot pressure sensor 76 is provided on a pilot line (the pilot line 64R in FIG. 7) corresponding to the lifting operation of the lift arm 21.
  • the pilot pressure sensor 76 is an embodiment of an operation signal detector that detects an operation signal from a lift arm operation lever 210 as an operation device.
  • the lifting operation amount of the lift arm operation lever 210 and the opening area of the spool of the control valve 46 are in a proportional relationship, and the opening area of the spool increases as the lifting operation amount of the lift arm operation lever 210 increases.
  • the lift arm operation lever 210 is largely operated in the direction in which the lift arm 21 is raised, the amount of hydraulic oil flowing into the lift arm cylinder 22 increases, and the rod 220 elongates quickly. That is, as the operation amount of the lift arm operation lever 210 increases, the operation speed of the lift arm 21 increases.
  • the range of 0 to 10% of the lifting operation amount of the lift arm operation lever 210 is set as a dead zone where the spool does not open even when the lift arm operation lever 210 is operated and the opening area is 0%.
  • the opening area of the spool is constant at 100%, and the full lever operation state is maintained. Note that these setting ranges can be arbitrarily changed.
  • both the discharge pressure sensor 75 and the pilot pressure sensor 76 This is an embodiment of an operation amount detector that detects the amount of operation of raising the lift arm 21 by the arm operation lever 210.
  • the controller 5 determines the lifting operation of the lift arm 21 using the discharge pressure Pa detected by the discharge pressure sensor 75.
  • the pilot opening generated according to the operation amount of the bucket operation lever 230 acts on the control valve 46, so that the opening area of the spool of the control valve 46 is controlled. Then, the amount of hydraulic oil flowing into and out of the bucket cylinder 24 is adjusted.
  • sensors and the like for detecting the operation of the bucket 23 are also provided on each pipeline of the hydraulic circuit.
  • FIG. 9 is a functional block diagram illustrating functions of the controller 5 according to the first embodiment.
  • the controller 5 includes a CPU, a RAM, a ROM, a HDD, an input I / F, and an output I / F connected to each other via a bus.
  • Various operating devices such as a forward / reverse switching lever 62 and various sensors such as a discharge pressure sensor 75, a stepping amount sensor 610, and a vehicle body tilt angle sensor 130 are connected to an input I / F, and a regulator 420 of the HST motor 42 is connected. Are connected to the output I / F.
  • the CPU reads an arithmetic program (software) stored in a recording medium such as a ROM, an HDD, or an optical disk, expands the arithmetic program on a RAM, and executes the expanded arithmetic program to execute arithmetic processing.
  • arithmetic program software stored in a recording medium such as a ROM, an HDD, or an optical disk
  • expands the arithmetic program on a RAM and executes the expanded arithmetic program to execute arithmetic processing.
  • the program and the hardware cooperate to realize the function of the controller 5.
  • the configuration of the controller 5 is described by a combination of software and hardware.
  • the present invention is not limited to this, and an integrated circuit that realizes the function of an arithmetic program executed on the wheel loader 1 side may be used. You may comprise using it.
  • the controller 5 includes a data acquisition unit 51, a specific condition determination unit 52, a motor control unit 53, and a storage unit 54.
  • the data acquisition unit 51 outputs a forward / reverse forward / backward switching signal output from the forward / backward switching lever 62, a depression amount of the accelerator pedal 61 detected by the depression amount sensor 610, and a working machine detected by the discharge pressure sensor 75.
  • Data on the discharge pressure Pa of the hydraulic pump 45 and data on the vehicle body inclination detection angle ⁇ (the amount of inclination) detected by the vehicle body inclination angle sensor 130 are acquired.
  • the specific condition determination unit 52 determines whether or not a specific condition for specifying that the wheel loader 1 is in an excavation state while climbing a slope is based on the signal and each data acquired by the data acquisition unit 51.
  • the specific condition determination unit 52 determines the forward traveling of the wheel loader 1 based on the forward / reverse switching signal and the amount of depression of the accelerator pedal 61, and determines the front based on the discharge pressure Pa of the hydraulic pump 45 for work equipment. A determination on the excavation operation of the work implement 2 and a determination on the tilt state of the vehicle body based on the vehicle body tilt detection angle ⁇ are performed. The specific condition determination unit 52 determines whether or not the specific condition is satisfied by performing the determination on these three conditions.
  • each of the forward / reverse switching lever 62 and the depression amount sensor 610 is one mode of a traveling state detector that detects the traveling state of the vehicle body of the wheel loader 1.
  • the forward traveling of the vehicle body is determined based on the forward / backward switching signal indicating forward traveling output from the forward / backward switching lever 62 and the depression amount of the accelerator pedal 61 detected by the depression amount sensor 610.
  • the traveling state detected by another traveling state detector mounted on the vehicle body such as, for example, detecting whether the traveling direction of the vehicle body is forward or backward based on the rotation direction of the propeller shaft. Based on this, the forward running of the vehicle body may be determined comprehensively.
  • the motor control unit 53 performs a maximum displacement volume qs (hereinafter, referred to as a “displacement volume”) when the excavation operation is performed by the front work machine 2 in a state where the vehicle body is installed on a flat ground.
  • a command signal based on a maximum displacement larger than “maximum displacement qs at the time of flat ground excavation operation” is output to the regulator 420 of the HST motor 42, and the maximum displacement qmax of the HST motor 42 is set at the maximum during the flat land excavation operation. The displacement is increased above the displacement volume qs.
  • the motor control unit 53 outputs a command signal based on the maximum displacement qs during the flat ground excavation operation to the HST. Output to the regulator 420 of the motor 42 to limit the maximum displacement qmax of the HST motor 42 to the maximum displacement qs at the time of level ground excavation operation.
  • the storage unit 54 stores a discharge pressure Ps (a discharge pressure of a hydraulic pressure source for extending the lift arm cylinder 22) of the work machine hydraulic pump 45 necessary for the excavation operation, a first angle threshold ⁇ 1 that is a threshold related to a vehicle body inclination angle, and a second angle threshold.
  • the angle threshold value ⁇ 2 and the maximum displacement qs at the time of the flat ground excavation operation are stored.
  • FIG. 10 is a flowchart showing a flow of processing executed by the controller 5 according to the first embodiment.
  • FIG. 11 is a graph showing the relationship between the discharge pressure Pa of the working machine hydraulic pump 45 and the maximum displacement qmax of the HST motor 42 in the first embodiment.
  • the data acquisition unit 51 acquires the depression amount of the accelerator pedal 61 output from the depression amount sensor 610 and the forward / reverse switching signal output from the forward / reverse switching lever 62 (step S501).
  • the specific condition determination unit 52 determines whether or not the wheel loader 1 is traveling forward based on the stepping amount and the forward / reverse switching signal acquired in step S501 (step S502).
  • step S502 When it is determined in step S502 that the wheel loader 1 is traveling forward (step S502 / YES), the data acquiring unit 51 determines the discharge pressure Pa of the working machine hydraulic pump 45 output from the discharge pressure sensor 75. It is acquired (step S503).
  • the specific condition determination unit 52 determines whether or not the discharge pressure Pa is equal to or higher than the discharge pressure Ps of the working machine hydraulic pump 45 necessary for the excavation operation, based on the discharge pressure Pa acquired in step S503. (Step S504).
  • step S504 determines whether the discharge pressure Pa is equal to or higher than the discharge pressure Ps of the work equipment hydraulic pump 45 required for the excavation operation (Pa ⁇ Ps) (step S504 / YES). If it is determined in step S504 that the discharge pressure Pa is equal to or higher than the discharge pressure Ps of the work equipment hydraulic pump 45 required for the excavation operation (Pa ⁇ Ps) (step S504 / YES), the data acquisition unit 51 determines whether the vehicle body tilt The vehicle body inclination detection angle ⁇ output from the angle sensor 130 is obtained (step S505).
  • the specific condition determination unit 52 determines whether or not the vehicle body inclination detection angle ⁇ is equal to or greater than 0 and less than the first angle threshold ⁇ 1 based on the vehicle body inclination detection angle ⁇ acquired in step S505. (Step S506).
  • step S506 If it is determined in step S506 that the vehicle body inclination detection angle ⁇ is equal to or greater than 0 and less than the first angle threshold ⁇ 1 (0 ⁇ ⁇ ⁇ 1) (step S506 / YES), the vehicle body is not climbing a hill.
  • the motor control unit 53 limits the maximum displacement qmax of the HST motor 42 to the maximum displacement qs at the time of the flatland excavation operation (step S507).
  • step S506 If it is determined in step S506 that the vehicle body inclination detection angle ⁇ is equal to or greater than 0 and is not less than the first angle threshold ⁇ 1 (step S506 / NO), the specific condition determination unit 52 then proceeds to step S506. It is determined whether the angle is equal to or more than the first angle threshold ⁇ 1 and less than the second angle threshold ⁇ 2 (step S508).
  • step S508 If it is determined in step S508 that the vehicle body inclination detection angle ⁇ is equal to or larger than the first angle threshold ⁇ 1 and smaller than the second angle threshold ⁇ 2 ( ⁇ 1 ⁇ ⁇ ⁇ 2) (step S508 / YES), the specific condition is satisfied. Therefore, the motor control unit 53 limits the maximum displacement qmax of the HST motor 42 to a first maximum displacement q1 (> qs) that is larger than the maximum displacement qs at the time of level digging operation (step S509). That is, in step S509, the motor control unit 53 raises the maximum displacement qmax of the HST motor 42 to be larger than the maximum displacement qs during the level ground excavation operation.
  • step S508 When it is determined in step S508 that the vehicle body inclination detection angle ⁇ is equal to or greater than the first angle threshold ⁇ 1 and not less than the second angle threshold ⁇ 2 (step S508 / NO), the specific condition determination unit 52 subsequently performs the vehicle body inclination detection It is determined whether or not the angle ⁇ is the second angle threshold ⁇ 2 (step S510).
  • step S503 the discharge pressure Pa is less than the discharge pressure Ps of the work machine hydraulic pump 45 required for the excavation operation (Pa ⁇ Ps) in step S504.
  • Step S504 / NO the discharge pressure Ps of the work machine hydraulic pump 45 required for the excavation operation
  • step S510 / NO the processing in the controller 5 ends.
  • the maximum displacement qmax of the HST motor 42 is automatically increased as shown in FIG. Since the maximum traction force of the vehicle body is higher than the maximum traction force at the time of level ground excavation operation by raising the vehicle body, the traction force of Wsin ⁇ , which has been reduced as compared with the level at the time of level ground excavation, can be compensated. This improves the work efficiency not only in the case of performing the excavation operation in a state where the vehicle body is installed on a flat ground, but also in the case of the lifting operation in which the vehicle body performs the excavation operation while traveling forward (uphill) on a steep slope. I can do it.
  • the controller 5 sets the maximum of the HST motor 42 to the maximum. While the displacement qmax is increased from the maximum displacement qs during the flat terrain excavation operation to the first maximum displacement q1 (from the two-dot chain line shown in FIG. 11 to the one-dot chain line shown in FIG. 11), the vehicle body inclination detection angle ⁇ becomes the second displacement.
  • the maximum displacement qmax of the HST motor 42 is increased from the maximum displacement qs during the flat terrain operation to the second maximum displacement q2 (> q1) (see FIG. 11). From the two-dot chain line to the solid line shown). That is, the larger the vehicle body inclination detection angle ⁇ is, the larger the rate of increase of the maximum displacement of the HST motor 42 is. For this reason, the maximum traction force of the vehicle body can be more accurately controlled according to the angle of the slope of the ground 100.
  • FIG. 12 is a diagram illustrating a hydraulic circuit and an electric circuit related to traveling drive of the wheel loader 1 according to the second embodiment.
  • FIG. 13 is a flowchart illustrating a flow of a process executed by the controller 5A according to the second embodiment.
  • FIG. 14 is a graph showing the relationship between the discharge pressure Pa of the working machine hydraulic pump 45 and the maximum displacement qmax of the HST motor 42 in the second embodiment.
  • the wheel loader 1 has a vehicle body during an excavation operation according to the hardness and specific gravity of earth and sand, minerals, and the like forming the ground 100, the state of the road surface at the work site, and the like.
  • the mode switch 60 is a manual switch, and is provided in the cab 12 (see FIG. 1).
  • the mode switching signal output from the mode switch 60 is input to the controller 5A.
  • the P mode is a mode in which the maximum traction force is minimized
  • the N mode is a case in which the maximum traction force is larger than that in the P mode
  • the L mode is a case in which the maximum traction force is larger than that in the N mode. This is the case.
  • the operator can perform the excavation work efficiently according to the environment of the site by switching the mode changeover switch 60 and selecting the optimum mode.
  • a lift arm angle sensor 211 (lift arm angle detector) for detecting the angle of the lift arm 21 is used for the tilt state detector for detecting the tilt state of the vehicle body. Therefore, in the controller 5A, the specific condition determination unit 52 determines the tilt state of the vehicle body based on the lift arm detection angle ⁇ output from the lift arm angle sensor 211.
  • the controller 5A is different from the controller 5 according to the first embodiment in how to increase the maximum traction force when specific conditions are satisfied. Specifically, as the lift arm detection angle ⁇ detected by the lift arm angle sensor 211 increases, the controller 5A determines that the discharge pressure Pa () of the working machine hydraulic pump 45 at the time of starting to limit the maximum traction force of the vehicle body. The value of the lift operation amount of the lift arm 21) is increased.
  • step S504 when it is determined in step S504 that the discharge pressure Pa is equal to or higher than the discharge pressure Ps of the work machine hydraulic pump 45 required for the excavation operation (Pa ⁇ Ps) (step S504 / YES), The acquisition unit 51 acquires the lift arm detection angle ⁇ (Step S505A).
  • the specific condition determination unit 52 determines whether or not the lift arm detection angle ⁇ is equal to or larger than 0 and smaller than the first angle threshold ⁇ 1 based on the lift arm detection angle ⁇ acquired in step S505A ( Step S506A).
  • step S506A If it is determined in step S506A that the lift arm detection angle ⁇ is equal to or greater than 0 and less than the first angle threshold ⁇ 1 (0 ⁇ ⁇ ⁇ 1) (step S506A / YES), the motor control unit 53 determines in step S503.
  • the maximum displacement qmax is limited to any of qP, qN, and qL (step S507A).
  • step S506A When it is determined in step S506A that the lift arm detection angle ⁇ is equal to or greater than 0 and is not less than the first angle threshold ⁇ 1 (step S506A / NO), subsequently, the specific condition determination unit 52 determines that the lift arm detection angle ⁇ It is determined whether or not the angle is equal to or larger than the first angle threshold ⁇ 1 and smaller than the second angle threshold ⁇ 2 (step S508A).
  • the limit value qP is set when the P mode is selected by the mode changeover switch 60
  • the limit value qN is set when the N mode is selected by the mode changeover switch 60
  • the limit value qL is set by the mode changeover switch 60. This is a limit value relating to the maximum displacement volume qmax of the HST motor 42 when the L mode is selected.
  • step S508A When it is determined in step S508A that the lift arm detection angle ⁇ is equal to or greater than the first angle threshold ⁇ 1 and is not less than the second angle threshold ⁇ 2 (step S508A / NO), the specific condition determination unit 52 subsequently performs lift arm detection. It is determined whether the angle ⁇ is the second angle threshold ⁇ 2 (step S510A).
  • the maximum displacement qmax is limited to any of qP, qN, and qL (step). S511A).
  • the maximum displacement qmax of the HST motor 42 is reduced.
  • the discharge pressure Pa when the limitation of the maximum traction force of the vehicle body is started be equal to or higher than the discharge pressure when the lift arm 21 takes a horizontal posture.
  • this corresponds to the first pressure threshold value P1, which is the discharge pressure at the time when the limitation of the maximum traction force of the vehicle body is started when the lift arm detection angle ⁇ reaches the first angle threshold value ⁇ 1.
  • the maximum towing force of the vehicle body can be controlled more accurately according to the angle of the slope of the ground 100 in the same manner as in the first embodiment. Improvement can be achieved.
  • FIGS. 15 and 16 the same components as those described for the wheel loader 1 according to the first embodiment and the second embodiment are denoted by the same reference numerals, and description thereof is omitted.
  • FIG. 15 is a flowchart showing the flow of processing executed by the controller 5B according to the third embodiment.
  • FIG. 16 is a graph showing the relationship between the discharge pressure Pa of the working machine hydraulic pump 45 and the maximum displacement qmax of the HST motor 42 in the third embodiment.
  • the controller 5B according to the present embodiment is different from the controller 5 according to the first embodiment and the controller 5A according to the second embodiment in how to increase the maximum traction force when specific conditions are satisfied. Specifically, as the lift arm detection angle ⁇ detected by the lift arm angle sensor 211 increases, the controller 5B increases the rate of increase of the discharge pressure Pa of the working machine hydraulic pump 45 with respect to the maximum amount of traction of the vehicle body. I'm making it big.
  • step S506A when it is determined in step S506A that the lift arm detection angle ⁇ is equal to or larger than 0 and smaller than the first angle threshold ⁇ 1 (0 ⁇ ⁇ ⁇ 1) (step S506A / YES), the motor control is performed.
  • the unit 53 increases the discharge pressure Pa of the working machine hydraulic pump 45 from a discharge pressure Ps necessary for excavation operation to a fourth pressure threshold P4 (> Ps) larger than the discharge pressure Ps.
  • the maximum displacement qmax of the HST motor 42 is gradually limited from 100% to any one of qP, qN, qL (step S507B).
  • step S508A when it is determined in step S508A that the lift arm detection angle ⁇ is equal to or larger than the first angle threshold ⁇ 1 and smaller than the second angle threshold ⁇ 2 ( ⁇ 1 ⁇ ⁇ ⁇ 2) (step S508A). / YES), as shown in FIG. 16, the motor control unit 53 determines that the discharge pressure Pa of the working machine hydraulic pump 45 is greater than the fourth pressure threshold P4 from the discharge pressure Ps required for the excavation operation. As it increases to P5 (> P4), the maximum displacement qmax of the HST motor 42 is gradually limited from 100% to any of qP, qN, and qL (step S509B).
  • the discharge pressure Pa of the working machine hydraulic pump 45 increases from the discharge pressure Ps required for excavation operation to a sixth pressure threshold P6 (> P5) larger than the fifth pressure threshold P5, as shown in FIG.
  • the maximum displacement qmax of 42 is gradually limited from 100% to any of qP, qN, qL (step S511B).
  • the maximum traction force of the vehicle body can be controlled more accurately in accordance with the angle of the slope of the ground 100 as in the first embodiment and the second embodiment.
  • the work efficiency during the scraping operation can be improved.
  • the working machine hydraulic pump 45 is a fixed displacement hydraulic pump, but is not limited thereto, and a variable displacement hydraulic pump may be used.
  • the maximum displacement of the wheel loader 1 is controlled by adjusting the maximum displacement qmax of the HST motor 42.
  • the present invention is not limited to this.
  • the displacement of the HST pump 41 is adjusted.
  • the maximum traction force of the wheel loader 1 may be controlled.
  • Wheel loader 2 Front work machine 3: Engine 5, 5A, 5B: Controller 11A: Front wheel (wheel) 11B: rear wheel (wheel) 21: Lift arm 41: HST pump (hydraulic pump for traveling) 42: HST motor (hydraulic motor for traveling) 45: Hydraulic pump for work equipment 62: Forward / backward switching lever (running state detector) 75: Discharge pressure sensor (operating amount detector) 76: Pilot pressure sensor (operation signal detector, operation amount detector) 130: Body tilt angle sensor (body tilt angle detector, body tilt state detector) 211: Lift arm angle sensor (lift arm angle detector, body tilt state detector) 610: Depressed amount sensor (running state detector)

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

Abstract

L'invention concerne une chargeuse montée sur roues qui peut améliorer l'efficacité de travail même lors de la réalisation d'opérations de creusement tout en montant une pente. La chargeuse montée sur roues d'entraînement de déplacement du type HST (1) est dotée d'un dispositif de commande (5, 5A, 5B) qui, pendant des opérations de creusement par une machine de travail avant (2), réalise une commande permettant de régler le moteur HST (42) et de limiter la traction maximale du corps de véhicule. Le dispositif de commande (5, 5A, 5B) détermine si oui ou non une condition spécifique est remplie, qui spécifie une opération de creusement de la machine de travail avant (2) réalisée pendant que le véhicule monte une pente, et si la condition spécifique est remplie, la traction maximale du véhicule est alors augmentée à une valeur supérieure à la traction maximale dans le cas de la réalisation d'une opération de creusement par la machine de travail avant (2) dans un état dans lequel le véhicule est placé sur un sol plat.
PCT/JP2018/036237 2018-09-28 2018-09-28 Chargeuse montée sur roues WO2020065915A1 (fr)

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JP2020547792A JP7169361B2 (ja) 2018-09-28 2018-09-28 ホイールローダ
PCT/JP2018/036237 WO2020065915A1 (fr) 2018-09-28 2018-09-28 Chargeuse montée sur roues

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PCT/JP2018/036237 WO2020065915A1 (fr) 2018-09-28 2018-09-28 Chargeuse montée sur roues

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JP2016130030A (ja) * 2013-04-26 2016-07-21 日立建機株式会社 ハイブリッド式作業車両

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JP2008144942A (ja) * 2006-12-13 2008-06-26 Komatsu Ltd 建設車両の牽引力制御装置
JP2011184886A (ja) * 2010-03-05 2011-09-22 Komatsu Ltd 作業車両及び作業車両の制御方法
JP5092071B1 (ja) * 2012-03-30 2012-12-05 株式会社小松製作所 ホイールローダ及びホイールローダの制御方法
JP5092070B1 (ja) * 2012-03-30 2012-12-05 株式会社小松製作所 ホイールローダ及びホイールローダの制御方法
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JP2016130030A (ja) * 2013-04-26 2016-07-21 日立建機株式会社 ハイブリッド式作業車両
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CN114371020B (zh) * 2021-12-24 2024-05-24 雷沃工程机械集团有限公司 一种装载机行走动力性测试方法

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