JP2004125094A - Hydraulic system of work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic system in a work vehicle for recovering turning system energy and work machine system energy for improving energy recovery efficiency and for recovering both energy in a simple configuration of one apparatus. <P>SOLUTION: A hydraulic system of a work vehicle has an energy recovery apparatus. The hydraulic system of the maintenance vehicle comprises a cancellation cylinder that is provided in parallel with a hydraulic cylinder for operating the work machine up and down and cancels the weight of the work machine; a turning motor for turning a revolving superstructure while becoming a displacement volume according to the amount of operation; and an accumulator that supplies pressure oil to the turning motor when rotating a cancellation cylinder and/or the revolving superstructure when moving the work machine in an upper direction, and recovers the pressure oil in the cancellation cylinder when operating the work machine in a lower direction and/or the pressure oil when stopping the turning motor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic system for a working vehicle, and more particularly to a hydraulic system used for construction machines such as a hydraulic shovel and a wheel loader, and industrial vehicles such as a hydraulic crane and a forklift.
[0002]
[Prior art]
In general, a work vehicle performs a predetermined work by driving a hydraulic pump with an engine and driving a work machine with hydraulic oil from the hydraulic pump. In this work vehicle, pressure oil at the time of braking of the actuator is collected in an accumulator and used for driving. (For example, refer to Patent Document 1).
According to the document, an electric motor also serving as a generator is attached to a hydraulic pump, and the electric motor performs a power generation operation and an assist operation by switching control of a controller. A swing pump motor that drives the swing body by operating the motor with pressure oil supplied from the accumulator is provided. The pump is operated during braking of the swing system by switching control of the swing controller to regenerate rotational energy.
[0003]
A second electric motor also serving as a generator is attached to the swirl pump motor, and the power generation operation and the assist operation are performed by switching control of the swirl controller. Further, in the hydraulic drive unit, when the actual rotation speed is lower than the rotation speed input value detected by the input detection means, the rotation pump motor operates the rotation pump motor to increase the speed, When the actual rotation speed is higher than the rotation speed input value detected by the input detection means, the rotation pump motor is rotated so as to be decelerated by operating the motor.
At this time, the slewing pump motor converts the kinetic energy of the pressure oil supplied from the accumulator to rotational energy to rotate the slewing body at an increased speed, and conversely, converts the slewing system rotational energy to pressure energy to the accumulator. It is described that the revolving structure is decelerated while accumulating pressure.
[0004]
[Patent Document 1]
JP-A-10-103112
[0005]
[Problems to be solved by the invention]
However, in Patent Literature 1, in order to recover the energy of the turning system, control is performed using a turning pump motor, an electric motor also serving as a generator, a turning controller, a second electric motor also serving as a generator, input detection means, and the like. However, the number of components increases, the structure becomes complicated, and the software for controlling becomes complicated, resulting in high cost.
Further, since only the rotational energy of the turning system is converted into the pressure energy, there is a problem in that the energy recovery is inefficient and the working machine as a whole is inefficient.
[0006]
The present invention has been made in view of the above problems, and relates to a hydraulic system of a work vehicle, and in particular, recovers energy of a turning system and a work machine system to improve energy recovery efficiency, and combines both energy into one. It is an object of the present invention to provide a hydraulic system for a work vehicle that recovers with a simple configuration of the device.
[0007]
Means for Solving the Problems, Functions and Effects
In order to achieve the above object, in the invention of the hydraulic system for a work vehicle according to the present invention, the hydraulic system for the work vehicle is provided in parallel with a hydraulic cylinder that operates the work machine in a vertical direction to cancel the weight of the work machine. A canceling cylinder, a turning motor for turning the revolving unit with a displacement volume corresponding to the operation amount, and a canceling cylinder for operating the work implement in an upward direction, and / or a revolving motor for rotating the revolving unit. And accumulator for collecting and accumulating the pressurized oil of the cancel cylinder when the work machine is operated downward and / or the pressurized oil for stopping the turning motor, and accumulates the accumulator. It is configured to include a charge pump that supplies pressure oil.
[0008]
In this case, the accumulator is configured to have an oil amount equal to or more than that required for rotating the rotation motor by a predetermined angle and raising the cancel cylinder by the maximum stroke.
Further, it is preferable that the swing motor be either a swing-type hydraulic motor that outputs a torque that rotates in a clockwise direction and a counterclockwise direction, or two swing-type hydraulic motors that are combined so as to output in both directions.
Further, it is preferable to provide an auxiliary swing motor driven by the auxiliary pump and the auxiliary control valve in parallel with the swing motor.
[0009]
According to the above configuration, energy is recovered with a simple configuration including the swing motor, the cancel cylinder, the charge pump, and the accumulator, and the energy of the swing system is recovered from the swing motor and the energy of the working system from the cancel cylinder. Therefore, high energy recovery efficiency can be obtained, and the apparatus can be inexpensive.
Further, since the accumulator has a total oil amount equal to or more than the sum of the turning oil amount at a predetermined angle at which the turning motor rotates and the working oil amount at which the cancel cylinder rises by the maximum stroke, the turning motor and The pressurized oil can be supplied from one accumulator to the cancel cylinder, which simplifies the configuration and reduces the number of failures because no controller or computer is used. Further, the engine for driving the charge pump for supplying the pressurized oil to the accumulator can be reduced in size, so that energy can be saved and the cost can be reduced.
[0010]
Since the swivel motor is configured to obtain a displacement volume according to the operation amount, the starting torque can be increased by increasing the operation amount at the time of starting, and the operation amount according to the stop angle is operated in the opposite direction at the time of stopping. As a result, the vehicle can be stopped at a desired position, and the operation can be easily performed to meet the driver's operational feeling, thereby reducing fatigue.
In addition, the swing motor can be combined so as to output in both directions by using two pulsating types, and it is possible to adopt a conventionally used hydraulic motor, thereby ensuring durability and increasing reliability. I have.
[0011]
Further, by providing the auxiliary swing motor, the swing body can be reliably stopped at a desired position even on a steeply inclined surface, so that the operation can be facilitated, fatigue can be reduced, and work can be facilitated.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a hydraulic system for a work vehicle according to the present invention will be described with reference to the drawings.
First, a hydraulic system 1 for a working vehicle according to a first embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram of a hydraulic system 1 of a work vehicle.
[0013]
In FIG. 1, a variable displacement pump 4 (hereinafter, referred to as a variable pump 4) driven by an engine 3 sucks oil from a tank 5 and pressurizes it into pressure oil, and the pressure oil passes from a check valve 6 through a pipe 7. The pressure is accumulated in the accumulator 9. The variable pump 4 acts as a charge pump, and supplies and accumulates pressure oil when the pressure oil in the accumulator 9 is insufficient.
The pressure oil discharged from the variable pump 4 is guided to the unload valve 11 through the pipe 7 on the accumulator 9 side. When the pressure of the accumulator 9 becomes equal to or higher than a predetermined pressure, the pressure oil is unloaded and returned to the tank 5, and is returned to the tank 5. 4 is reduced.
[0014]
The variable pump 4 has a displacement volume (cm ³ / Rev) is variable, and when the amount of oil accumulated in the accumulator 9 is small, the displacement volume of the variable pump 4 is increased to replenish the oil quickly, and when the amount of oil accumulated in the accumulator 9 is full, the displacement is eliminated. The drive torque is reduced by making the volume almost zero.
Accordingly, the amount of oil stored in the accumulator 9 is not interrupted when the hydraulic shovel 20, which is a working vehicle as shown in FIG. The supply of pressure oil to the cylinder 21 and the cancel cylinder 23 is stabilized, and when the oil amount of the accumulator 9 is large, the displacement volume is reduced to save energy.
[0015]
The pipe 7 is branched into a turning pipe 15 and a working pipe 17. The turning pipe 15 is connected in parallel to the turning motor 21, and the working pipe 17 is connected in parallel to the cancel cylinder 23.
The swing motor 21 is constituted by a swing type hydraulic motor, and the swash plate 21a is tilted in both directions from a neutral point to rotate the output shaft clockwise and counterclockwise. The swash plate 21a is connected to the turning operation lever 25, and makes the tilt angle variable according to the operation amount of the turning operation lever 25. Thereby, the turning motor 21 changes the displacement volume according to the operation amount of the turning operation lever 25, and changes the rotation speed and output torque of the output shaft.
[0016]
The revolving motor 21 has a revolving body 26 connected to an output shaft of the revolving body 26 via a gear (not shown) or the like. The revolving operation lever 25 is operated by receiving the pressurized oil from the accumulator 9 and operating the revolving operation lever 25. The displacement becomes a displacement volume corresponding to the operation amount of 25, and the rotating body 26 is rotating at a predetermined rotation speed while generating a rotating torque.
At this time, the accumulator 9 has a volume that allows the revolving motor 26 to rotate the revolving superstructure 26 by a predetermined angle within the working range. A return pipe 27 is connected to the swing motor 21 to return return oil to the tank 5. Although the swash plate 21a is connected to the turning operation lever 25 by a rod, it may be connected to the turning operation lever 25 via a servo valve, an actuator, or the like.
The swing motor 21 is provided with a shaft brake (not shown). When the engine 3 is stopped, the shaft brake (not shown) is activated to fix the shaft of the swing motor 21 so as not to rotate. The position is fixed so that it does not move. Further, for example, when the revolving body 26 is stopped so as not to turn while the engine 3 is operating on a slope such as a slope, the operator operates the turning operation lever 25 to turn the turning motor 21 on the slope. By adjusting the position of the plate, a rotational torque in a direction against the rotational force generated by the slope is generated, so that the revolving body 26 does not move.
[0017]
As shown in FIG. 2, the cancel cylinder 23 has one end 23a rotatably connected to a working machine 29 such as a boom and an arm and the other end 23b rotatably connected to a revolving body 26. , The predetermined holding oil pressure Pd is generated in the bottom chamber 23d. The bottom chamber 23d is connected to the accumulator 9 via the working pipe 17 and the pipe 7, and receives the pressurized oil from the accumulator 9 when the cancel cylinder 23 is extended, and returns the pressurized oil to the accumulator 9 when contracted. . At this time, the accumulator 9 has a capacity larger than the capacity when the cancel cylinder 23 performs the maximum stroke.
A hydraulic cylinder 31 for a working machine (hereinafter referred to as a working cylinder 31) is arranged in parallel between the working machine 29 and the revolving unit 26, and one end 31a is connected to the working machine 29 such as a boom and the other end. The portion 31b is rotatably attached to the swing body 26.
[0018]
The working cylinder 31 is connected to a working machine hydraulic pump 35 (hereinafter, referred to as a working pump 35) via a direction control valve 33. When the direction control valve 33 is switched by operating the operation lever 37 for the work machine, the work pump 35 supplies the pressurized oil to the bottom chamber 31d to extend the work cylinder 31 and supply it to the head chamber 31e. Thereby, the working cylinder 31 is contracted, and the working machine 29 is raised and lowered.
At the time of extension, the working cylinder 31 raises the work implement 29 with a small push-up force by adding the extension force by the predetermined holding oil pressure Pd of the cancel cylinder 23. In this manner, the cancel cylinder 23 receives the weight of the work machine 29 and cancels the weight acting on the work cylinder 31 to reduce the work cylinder 31. At this time, when the cancel cylinder 23 makes the maximum stroke, the working cylinder 31 also makes the maximum stroke.
[0019]
The accumulator 9 has an oil amount equal to or more than that required for the swing motor 21 to swing the swing body 26 by a predetermined angle and to raise the cancel cylinder 23 by the maximum stroke.
The pressure Pa stored in the accumulator 9 is set by a maximum pressure Prmax that generates a starting force or the like generated when the revolving body 26 is turned by a predetermined angle, a maximum pressure Psmax that is generated when the working cylinder 31 is raised, and the like. ing. A safety valve 38 is provided between the accumulator 9 and the rotation motor 21 and the cancel cylinder 23 to protect the circuit.
[0020]
For example, when the hydraulic system 1 of the work vehicle is used for the hydraulic excavator 20 as shown in FIG. 2, the total oil amount Av of the accumulator 9 is at least the turning oil amount Rv that rotates the revolving unit 26 by an angle of 90 degrees. And a working oil amount Sv sufficient to cause the boom of the work machine 29 to make a maximum stroke.
Further, the pressure Pa stored in the accumulator 9 is such that the vehicle body is kept at the maximum inclination angle during the work, and the work equipment 29 is pushed up along the inclination angle when the load is loaded on the work equipment 29 at the maximum when starting up. The maximum pressure Prmax is set at this time, and the cancel cylinder 23 is set so that the work implement 29 can be held by the maximum pressure Prmax at the time of turning without loading a load on the work implement 29.
That is, the safety valve 38 is set to a holding pressure capable of holding the work implement 29, and the accumulator 9 is accumulated at the holding pressure. The unload valve 11 unloads at a predetermined pressure lower than the set pressure of the safety valve 38.
[0021]
Next, the operation of the hydraulic system 1 of the work vehicle will be described for a case where the hydraulic system 1 is used for the hydraulic excavator 20.
In FIG. 1, when turning the hydraulic excavator 20, the turning operation lever 25 is operated by a maximum amount in the turning direction. As a result, the swash plate 21a of the turning motor 21 is tilted to the maximum angle and becomes the maximum displacement volume. The swing motor 21 is activated by receiving the pressure Pa stored in the accumulator 9 and starts rotating the swing body 26.
When the swing body 26 starts rotating, the swing operation lever 25 is returned to the neutral side so as to obtain a desired rotation speed. As a result, the swing motor 21 tilts the swash plate 21a to the angle returned from the maximum amount angle, and becomes a displacement volume at which a desired rotation speed is obtained. The revolving body 26 is rotated at a desired rotation speed by the pressure oil of the accumulator 9. Turn with.
[0022]
When the swing body 26 swings and reaches a position near the front side from a desired stop position, the swing operation lever 25 is operated in a direction opposite to the rotation direction. The swash plate 21a of the swing motor 21 tilts in the opposite direction to function as a hydraulic pump, and the swing motor 21 receives the reverse driving force from the swing body 26 to raise the pressure oil from the accumulator 9 and push it back to the accumulator 9.
As a result, the revolving body 26 is stopped by receiving the braking torque, and the revolving motor 21 functions as a hydraulic pump to collect the pressure oil in the accumulator 9 so that the revolving motor 21 can be revolved next time and the working cylinder 31 can be extended. Sometimes we are prepared.
That is, when the brake is stopped by the turning motor 21, the turning operation lever 25 is operated in the direction opposite to the turning direction by an operation amount corresponding to the stop angle, and the set pressure of the safety valve 38 and the turning motor By generating a braking force determined by the capacity of the swash plate 21, the vehicle can be stopped at a desired position.
[0023]
When the work machine 29 of the hydraulic shovel 20 is operated to excavate the work machine 29 and move the work machine 29 up and down, the work operation lever 37 is operated in one of the up and down directions. Thereby, the direction control valve 33 is switched, and the discharge oil of the working machine pump 35 is supplied to either the bottom chamber 31d or the head chamber 31e to expand and contract the working cylinder 31 and move the working machine 29 up and down.
As the work machine 29 moves up and down, the cancel cylinder 23 expands and contracts together with the work cylinder 31 that moves the work machine 29 up and down.
[0024]
When the working cylinder 31 extends, the cancel cylinder 23 extends by receiving the pressure oil from the accumulator 9, cancels and reduces the weight of the working machine 29 acting on the working cylinder 31, and The working machine 29 is extended by reducing the operating oil pressure.
Conversely, when the working cylinder 31 contracts, the cancel cylinder 23 receives the weight of the work implement 29 to generate pressure oil, and contracts while returning this pressure oil to the accumulator 9. As a result, the cancel cylinder 23 recovers energy by lowering the work machine 29, and prepares for the next rotation of the rotation motor 21 and the extension of the work cylinder 31.
[0025]
When the excavated object is excavated by the hydraulic excavator 20 and the excavated object is loaded on a dump truck or the like, the boom of the work machine 29 is raised while rotating the revolving body 26.
In this case, the turning operation lever 25 is operated in the turning direction, and the work implement operation lever 37 is operated in the ascending direction of the work implement 29. By operating the turning operation lever 25, as described above, the turning motor 21 has a displacement volume corresponding to the operation amount, and rotates the revolving body 26 at a predetermined rotation speed after being started by receiving the pressurized oil from the accumulator 9. Moving.
[0026]
At the same time, the operation control lever 37 is operated to switch the direction control valve 33 so that the pressure oil discharged from the work machine pump 35 is supplied to the work cylinder 31 and the work machine 29 is raised. Along with this, the cancel cylinder 23 receives the pressure oil from the accumulator 9 and extends together with the working cylinder 31 to raise the working machine 29.
As described above, the turning motor 21 and the working cylinder 31 operate by receiving the pressure oil from the same accumulator 9, but the accumulator 9 has a pressure equal to or higher than the maximum pressure acting on the turning motor 21 as described above, Since the revolving body 26 and the working machine 29 have an oil amount equal to or more than the total oil amount Av required to operate, the revolving body 26 and the working machine 29 can be operated by the same accumulator 9.
[0027]
Next, when the swing body 26 reaches the predetermined position, the swing operation lever 25 is operated in the direction opposite to the rotation direction, and the swing motor 21 functions as a hydraulic pump. Under the force, the pressure oil from the accumulator 9 rises and is pushed back to the accumulator 9 to accumulate the pressure oil in the accumulator 9 and supply the pressure oil to the cancel cylinder 23. In this way, the swing body 26 stops at the predetermined position, and the work implement 29 reaches the predetermined rising position.
[0028]
After the revolving superstructure 26 reaches a predetermined position and stops, the work machine 29 is operated by the oil discharged from the work pump 35, and the excavated object is loaded on the dump truck. After the loading, the revolving body 26 returns to the original excavation position for excavation again. At this time, the rotation of the revolving motor 21 and the lowering of the boom of the work implement 29 are performed simultaneously.
The turning motor 21 receives the pressure oil from the accumulator 9 at the time of start to turn and starts, and then turns at a desired speed. The work machine 29 is compressed while returning the pressurized oil to the accumulator 9 with the cancel cylinder 23 receiving the weight of the work machine 29 as the boom is lowered. At this time, the accumulator 9 supplies the pressurized oil to the swivel motor 21 to turn the swivel motor 21 and returns the pressurized oil from the cancel cylinder 23 to accumulate the pressure. It is possible to do.
[0029]
When the swing body 26 reaches the original excavation position, the swing operation lever 25 is operated in the direction opposite to the rotation direction, and the swing motor 21 functions as a hydraulic pump as described above, and raises the pressure oil from the accumulator 9. To return to the accumulator 9 and accumulate pressure oil in the accumulator 9 to prepare for the next turning of the turning motor 21 and / or the extension of the working cylinder 31.
The pressurized oil is supplied from the accumulator 9 connected in parallel to the swing motor 21 and / or the cancel cylinder 23, and the pressurized oil is returned from the swing motor 21 and / or the cancel cylinder 23 to the accumulator 9 for one cycle. Working. At this time, if the pressure oil in the accumulator 9 is insufficient, the pressure oil is quickly replenished from the variable pump 4 so that the turning motor 21 and the cancel cylinder 23 are not stopped.
[0030]
Next, a hydraulic system 1A for a working vehicle according to a second embodiment will be described with reference to FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
In the hydraulic system 1 of the work vehicle shown in FIG. 1, the swing motor 21 uses one double swing hydraulic motor. In the second embodiment shown in FIG. 3, two swing swing hydraulic motors are used as swing motors. The swing motors are two swinging swing motors 40A and 40B.
[0031]
In FIG. 3, two pulsating type swing motors 40A and 40B are connected to an accumulator 9 via a first swing pipe 15A and a second swing pipe 15B branched from the swing pipe 15, and each of them is an accumulator. It receives pressure oil from 9.
One of the two pulsating swing motors 40A and 40B outputs right rotation and the other outputs left rotation, and each of the single swing motors 40A and 40B outputs a turning operation lever 25 via a link lever 41. It is connected to.
[0032]
In the above configuration, for example, when the turning operation lever 25 is operated in the downward direction R, the swash plate of the pulsating type turning motor 40 </ b> A tilts according to the operation amount via the link lever 41, and according to the operation amount. The displacement volume.
At this time, the oscillating type swing motor 40B on the opposite side is free to rotate since the swash plate is kept at the neutral position, and there is no movement of the piston because there is no movement of the piston. It is shut off by the mold turning motor 40B. As a result, the accumulator 9 supplies pressure oil only to the operated one-sided swing motor 40A side, and operates the one-sided swing motor 40A to rotate rightward.
The supply of the pressurized oil from the accumulator 9 and the collection of the pressurized oil to the accumulator 9 are the same as those in the first embodiment, and thus the description thereof is omitted.
In the above example, the two swinging type swing motors 40A and 40B are connected to and operated by the swing operation lever via the link lever 41, but are controlled using a servo valve, an actuator or a pressure proportional pressure reducing valve. Is also good.
[0033]
Next, a hydraulic system 1B for a working vehicle according to a third embodiment will be described with reference to FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
In the hydraulic system 1 of the work vehicle shown in FIG. 1, one swing motor is used as the swing motor 21. However, in the third embodiment shown in FIG. The auxiliary swing motor 21AM is additionally used in parallel. Thus, the swing body 26 can be rotated by the auxiliary swing motor 21AM.
[0034]
In FIG. 4, the auxiliary turning motor 21AM is connected to a turning hydraulic pump 35S (hereinafter referred to as a turning pump 35S) as an auxiliary pump via a turning direction control valve 33S as an auxiliary control valve. When the turning direction control valve 33S is switched by operating the turning operation lever 37S, the turning pump 35S rotates the turning body 26 by supplying the pressure oil to the auxiliary turning motor 21AM.
The swash plate 21a of the turning motor 21 is controlled by the controller 21C. When the turning operation lever 37S is operated, a lever operation amount signal of the operation amount of the turning operation lever 37S detected by the lever operation amount sensor 37Sa, and The tilt angle is made variable according to a rotation signal including the rotation speed and the rotation direction of the revolving body 26 detected by the revolving rotation sensor 26a. Accordingly, the turning motor 21 changes the displacement volume in accordance with the operation amount of the turning operation lever 37S, and changes the rotation speed and output torque of the output shaft.
[0035]
In the above configuration, for example, when the excavator 20 is working on a steep slope, the swing operation lever 37S is operated to rotate the swing motor 21, and the swing body 26 is rotated to a desired position. Then, when the turning operation lever 37S is returned to the neutral position, the rotating body 26 and the working machine 29 generate their own weight by the slope, so that a rotating force is generated in the rotating body 26 toward the lower side of the slope. May try to rotate without stopping at the desired position. In this case, the turning direction control valve 33S is at the neutral position, and the turning force of the inclined surface of the turning body 26 is held by the auxiliary turning motor 21AM. In this manner, the revolving unit 26 can be reliably stopped at a desired position against the rotational force caused by the slope.
[0036]
In the above embodiment, the working cylinder 31 and the cancel cylinder 23 are mounted on the revolving superstructure, but may be arranged between the working machine 29 and the vehicle body according to the vehicle body to be configured. Further, the example in which the rotary motor rotates the revolving body has been described, but the rotary motor may be used when rotating a link such as a boom or an arm of the work implement.
In the above example, one revolving superstructure and one work machine are operated by the accumulator.However, two or more revolving superstructures and work machines, or one revolving superstructure and two or more work machines are operated by the accumulator. You may make it do. Further, although the accumulator is shown as one accumulator, two accumulators may be installed in parallel to operate in order to increase the capacity.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a hydraulic system for a working vehicle according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a hydraulic excavator.
FIG. 3 is a circuit diagram showing a part of a hydraulic system for a work vehicle according to a second embodiment of the present invention.
FIG. 4 is a circuit diagram showing a part of a hydraulic system for a working vehicle according to a third embodiment of the present invention.
[Explanation of symbols]
1, 1A: hydraulic system of work vehicle, 3: engine, 4: variable displacement pump (charge pump), 5: tank, 6: check valve, 9: accumulator, 11: unload valve, 21: swing motor, 21AM ... Auxiliary swing motor, 23 ... Cancel cylinder, 25 ... Swing operation lever, 26 ... Slewing body, 29 ... Work machine, 31 ... Hydraulic cylinder for work machine, 33 ... Direction control valve, 33S ... Swing direction control valve, 35 ... Hydraulic pump for working machine, 35S ... Hydraulic pump for turning (swing pump), 37 ... Operating lever for working machine, 37S ... Operating lever for turning, 40A, 40B ... Single swing type turning motor.

Claims (4)

A hydraulic system for a work vehicle,
A cancel cylinder that is provided in parallel with a hydraulic cylinder that operates the work machine in a vertical direction and cancels the weight of the work machine;
A swing motor that swings the swing body as a displacement volume according to the operation amount,
Supplying hydraulic oil to the cancel cylinder when operating the work implement in the upward direction and / or to the swing motor when rotating the revolving structure, and supplying hydraulic oil of the cancel cylinder when operating the work implement in the downward direction; and And / or an accumulator that collects and accumulates pressure oil when stopping the swing motor,
A hydraulic system for a working vehicle, comprising a charge pump for supplying pressure oil to accumulate pressure in an accumulator. The hydraulic system for a work vehicle according to claim 1,
A hydraulic system for a work vehicle, wherein the accumulator has an oil amount that is equal to or more than an oil amount necessary for turning the turning motor by a predetermined angle and raising the cancel cylinder by a maximum stroke. The hydraulic system for a work vehicle according to claim 1 or 2,
A work vehicle, comprising: a swing-type hydraulic motor that outputs torque in which a swing motor rotates in a clockwise direction and a counterclockwise direction, or two pulsating-type hydraulic motors that are combined to output in both directions. Hydraulic system. In the hydraulic system for a working vehicle according to claim 1, claim 2 or claim 3,
A hydraulic system for a work vehicle, wherein an auxiliary swing motor driven by an auxiliary pump and an auxiliary control valve is provided in parallel with the swing motor.

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