KR20180020253A - Boom lifting devices and boom sprayers - Google Patents

Abstract

The boom lifting device includes a platform 3 capable of lifting and lowering with respect to the vehicle body 91, a boom 4 supported by the platform, a lifting cylinder 40 interposed between the body and the platform, An accumulator 61 connected to the elevating cylinder, an opening / closing valve 63 for opening / closing a passage for communicating the elevating cylinder and the accumulator, and an open / close valve 63 for controlling the opening / And a controller 70 for controlling the motor. The controller closes the open / close valve when detecting an operation of raising and lowering the boom by the operator.

Description

Boom lifting devices and boom sprayers

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boom sprayer and a boom lifting device for lifting and lowering a boom of a boom sprayer.

JP2013-102A has a link arm mounted on a vehicle body, a boom supported at one end of the link arm, a cylinder interposed between the vehicle body and the link arm, and a boom lifting and lowering device for raising and lowering the boom by supplying hydraulic oil to the cylinder A boom sprayer is provided.

Further, in the boom sprayer disclosed in JP2013-102A, an accumulator for absorbing pressure fluctuations in the cylinder is connected to the cylinder in order to suppress the transmission of the vibration of the vehicle body to the boom. The pressure in the accumulator is usually equal to the pressure in the piston chamber of the cylinder. The pressure of the piston chamber is a pressure required to maintain the boom at a predetermined height with respect to the vehicle body, that is, a pressure corresponding to the weight of a member such as a link arm or a boom supported by the cylinder.

In the boom sprayer described in JP2013-102A, an inertial force is applied to the boom when an attempt is made to raise the boom in a stationary state by extending to the left and right of the vehicle body. Therefore, in order to rapidly raise the boom against the vehicle body, in addition to the load supporting the boom, a load exceeding the inertial force acting on the boom must be generated in the cylinder. That is, it is necessary to increase the pressure of the piston chamber of the cylinder by the amount corresponding to the inertial force acting on the boom, from the pressure when the boom is held in the stopped state.

In the boom sprayer disclosed in JP2013-102A, the piston chamber and the accumulator communicate with each other. As a result, even if the operating oil is supplied from the pump and the pressure of the piston chamber is raised, the operating oil flows into the oil chamber of the accumulator communicating with the piston chamber, thereby shrinking the spring chamber of the accumulator. As the pressure of the accumulator rises due to the contraction of the spring seal, the pressure in the piston chamber gradually rises. When the pressure of the piston chamber rises by an amount corresponding to the inertial force acting on the boom, the cylinder extends to raise the boom against the vehicle body.

As described above, in the boom sprayer having the above-described configuration, the boom does not rise unless the pressure of the accumulator rises. Therefore, even if the operator raises the boom, the boom may not rise quickly.

An object of the present invention is to improve the responsiveness of the boom sprayer to the operation of lifting the boom.

According to one aspect of the present invention, there is provided an elevating apparatus comprising: a lift member capable of being raised and lowered with respect to a vehicle body; a boom having one end supported by the elevation member and the other end provided as a free end for spraying liquid; A working fluid supply and discharge device for supplying a working fluid to the hydraulic cylinder and raising and lowering the boom with respect to the vehicle body; an accumulator connected to the hydraulic cylinder and storing the pressurized working fluid; And an opening / closing valve for opening / closing a passage for communicating the accumulator, and a control unit for controlling the opening / closing valve in accordance with an operation of a worker, wherein when the operator detects an operation of raising and lowering the boom, A boom lifting device for closing a valve is provided.

1 is a plan view of a boom sprayer according to a first embodiment of the present invention.
2 is a side view of a hydraulic circuit diagram and a boom sprayer of a boom lifting device.
3 is a flowchart of the boom lifting / lowering process executed by the control unit of the boom sprayer according to the first embodiment of the present invention.
4 is a flowchart of a modified example of the boom lifting / lowering process executed by the control unit of the boom sprayer according to the first embodiment of the present invention.
5 is a side view of a hydraulic circuit diagram and a boom sprayer of a boom lift apparatus according to a second embodiment of the present invention.
6 is a flowchart of the boom-up / down process executed by the control unit of the boom sprayer according to the second embodiment of the present invention.
7 is a flowchart of a modified example of the boom lifting / lowering process executed by the control unit of the boom sprayer according to the second embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, three axes of X, Y, and Z orthogonal to each other are set on the accompanying drawings, and the X axis is set in the front-rear direction (substantially horizontal longitudinal direction) of the vehicle, the Y axis is set in the horizontal direction An embodiment will be described in which the vehicle is extended in the vertical direction (substantially the vertical direction) of the vehicle, the rotation direction about the X axis is the roll direction, and the rotation direction about the Z axis is the yaw direction.

≪ First Embodiment >

First, a boom sprayer 100 according to a first embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.

The boom sprayer 100 shown in Fig. 1 is an agricultural working machine mounted on the front side of a work vehicle 90 running on a package, and spraying a chemical solution such as a cleaning liquid or a liquid fertilizer from the work car 90. Fig.

The boom sprayer (100) has a pair of booms (4) extending laterally from the work vehicle (90). The boom 4 is provided with a nozzle (not shown) for spraying a chemical liquid. During operation of the boom sprayer (100), the chemical liquid is sprayed from the nozzle of the boom (4) as the work vehicle (90) travels through the package.

The boom sprayer 100 includes a pair of link arms 2 provided on a vehicle body 91 of a work vehicle 90 and a pair of link arms 2 which are vertically movable with respect to the vehicle body 91 by a link arm 2, (Left and right) side (Y-axis direction) of the vehicle body 91 from the roll stand 5, and a pair of right and left rails 5, which are rotatably supported on the platform 3 in the roll direction And a boom 4 extending left and right.

The proximal end 4a of the boom 4 is cantilevered by the proximal end 4a of the boom 4 so as to be rotatable in the yaw direction (around the Z axis) via a hinge (not shown) do. The boom 4 is supported on the base end side frame 15 having the base end portion 4a in such a manner that the forward end side frame 16 having the tip end portion 4b is retractable.

Fig. 1 shows a deployed state in which the left and right booms 4 extend in the left and right horizontal directions of the vehicle body 91. Fig. When the boom 4 is retracted, the boom 4 retracts the distal end side frame 16 from the deployed state shown in Fig. 1 and stores it in the proximal end side frame 15, then rotates rearward through the retention hinge do. As a result, the boom 4 is folded so as to extend in the longitudinal direction along the side of the vehicle body 91 and stored.

The roll base 5 is rotatably supported on the platform 3 via a support shaft 6 in the roll direction. A cylindrical pin member is used for the support shaft 6.

Between the platform 3 and the roll 5 is disposed a fluid pressure cylinder 30 extending and retracted in association with the rotation of the boom 4 in the left and right roll directions and a fluid pressure cylinder 30 30, and is provided with a metal spring 32 that extends and retracts in conjunction with the rotation of the boom 4 in the right and left roll directions. The fluid pressure cylinder 30 and the metal spring 32 suppress the vibration in the roll direction in which the boom 4 rotates in the left and right roll directions. Thus, the vibration of the distal end portion 4b of the boom 4 in the vertical direction is suppressed, and the distal end portion 4b is prevented from coming into contact with the crops of the package or the like.

Next, a mechanism for raising and lowering the boom 4 relative to the vehicle body 91 will be described with reference to Fig. 2 is a side view of the boom sprayer 100. FIG.

The link arm 2 has an upper link 21 and a lower link 22 extending in parallel with each other. The upper link 21 has its base end rotatably connected to the vehicle body 91 via the pin 12 and the tip end thereof is rotatably connected to the platform 3 via the pin 11. The lower link 22 has its base end rotatably connected to the vehicle body 91 via a pin 14 and its tip end is rotatably connected to the platform 3 via a pin 13.

On both right and left sides of the vehicle body 91, a pair of lifting cylinders 40 as hydraulic cylinders are provided. Each lift cylinder 40 is interposed between the vehicle body 91 and the upper link 21 and is expanded and contracted in synchronization with each other to raise and lower the platform 3 and the boom 4.

The lifting cylinder 40 includes a cylinder tube 41 sealed with working fluid as a working fluid, a piston rod 42 inserted and retractably inserted into the cylinder tube 41, (43). The lift cylinder 40 has a base end portion of the cylinder tube 41 rotatably connected to the vehicle body 91 through the pillow ball 46 and a tip end portion of the piston rod 42 is connected to the upper link (Not shown). The pillow balls 46, 47 are constituted by, for example, ball and spherical bearings. The connecting portion of the lifting cylinder 40 is prevented from being twisted by the pillow balls 46, 47.

The inside of the cylinder tube 41 is partitioned by the piston 43 into the piston chamber 44 and the rod chamber 45. [ The piston 43 is provided with a flow passage 43a for allowing a sense of the operating oil to flow between the piston chamber 44 and the rod chamber 45. The working fluid is fed by the working fluid feed-in device 50 to the piston chamber 44 and the up-and-down cylinder 40 is expanded and contracted in accordance with the working fluid. Thus, in the present embodiment, the lifting cylinder 40 is a single acting fluid pressure cylinder. It is also possible to use a double acting fluid pressure cylinder in which the working oil is fed to both the piston side chamber 44 and the rod side chamber 45 as the lifting cylinder 40. [

As described above, each lifting cylinder 40 expands and contracts, and the platform 3 and the boom 4 are lifted and lowered by the rotation of each link arm 2. Instead of this configuration, a guide rail extending in the Z-axis direction may be provided in the front portion of the vehicle body 91, and the platform 3 may be supported so as to be able to move up and down in the Z-axis direction. In this case, each lifting cylinder 40 is interposed between the vehicle body 91 and the platform 3 and is expanded and contracted to change the height of the platform 3 relative to the vehicle body 91.

The working fluid supply device 50 includes a tank T in which hydraulic oil is stored and a hydraulic pump 51 as a hydraulic pump that is driven by an electric motor (not shown) and supplies hydraulic oil in the tank T to the piston chamber 44 A supply and discharge passage 56 communicating with the piston chamber 44 of the pair of lifting cylinders 40; an operation check valve 53 interposed in the supply and discharge passages 56; And a direction switching valve 52 serving as a switching valve for switching the communication between the hydraulic pump 51 and the tank T with respect to each other.

The directional control valve 52 is provided with a supply passage 55 for guiding the hydraulic oil discharged from the hydraulic pump 51, a discharge passage 57 for returning the hydraulic oil to the tank T, an operation check valve 53, An operating passage 59 communicating with the pilot pressure chamber of the piston chamber 44 and a cylinder passage 56 communicating with the piston chamber 44 are connected. The relief passage 58 connecting the supply passage 55 and the discharge passage 57 is provided with a relief valve 54 that opens when the hydraulic pressure in the supply passage 55 exceeds the set pressure.

The directional control valve 52 is provided with an extension position 52a as an operating position for extending the lift cylinder 40, a contracting position 52b as an operation position for contracting the lift cylinder 40, Stopping position 52c for stopping the valve. The position of the directional control valve 52 is appropriately changed so that the height of the boom 4 relative to the vehicle body 91 becomes a desired height.

When the directional control valve 52 is switched to the extension position 52a, the discharge passage 57 and the operation passage 59 are communicated with each other, and the delivery passage 56 and the supply passage 55 are communicated with each other. The hydraulic fluid discharged from the hydraulic pump 51 flows into the piston chamber 44 of the pair of lifting cylinders 40 through the supply passage 55 and the delivery passage 56. As a result, the pair of lifting cylinders 40 are stretched synchronously, the link arm 2 is rotated upward, and the boom 4 is raised with respect to the vehicle body 91 together with the link arm 2.

When the directional control valve 52 is switched to the contracted position 52b, the supply passage 55 communicates with the operation passage 59 and the delivery passage 56 communicates with the discharge passage 57. The discharge pressure of the hydraulic pump 51 is guided as pilot pressure to the operation check valve 53 through the operation port 59 so that the operation check valve 53 is opened and the operating oil of the piston chamber 44 Is returned to the tank (T) through the delivery passage (56) and the discharge passage (57). As a result, the pair of lifting cylinders 40 are contracted synchronously, the link arm 2 is rotated downward, and the boom 4 descends with respect to the vehicle body 91 together with the link arm 2.

When the directional control valve 52 is switched to the stop position 52c, the supply passage 55, the discharge passage 57, the operation passage 59 and the delivery passage 56 are closed. As a result, the hydraulic oil flowing into the piston chamber 44 is blocked through the delivery passage 56 and the operation check valve 53 is closed. Therefore, the movement of each piston 43 in the pair of lifting cylinders 40 is stopped, and the height of the boom 4 relative to the vehicle body 91 is maintained. Thus, the boom sprayer 100 can adjust the height of the boom 4 with respect to the vehicle body 91, that is, the height of the boom 4 with respect to the crop of the packaging, by expanding and contracting the lifting cylinder 40.

In the boom sprayer 100 constructed as described above, the vibration in the vertical direction of the vehicle body 91 is transmitted to the link arm 2 and the boom 4 through the lifting cylinder 40. In order to suppress this, the boom sprayer 100 further includes a boom vibration damping device 60.

The boom damping device 60 includes an accumulator 61 connected to the piston chamber 44 of the lifting cylinder 40 and a damping valve 61 for imparting resistance to the hydraulic oil flowing between the piston chamber 44 and the accumulator 61. [ (62).

The interior of the accumulator 61 has an oil chamber 61a connected to the piston chamber 44 for supporting the link arm 2 and a spring chamber 61b for applying pressure to the oil chamber 61a.

The spring chamber 61b is a gas chamber in which a gas such as pressurized nitrogen is sealed, and applies a gas pressure to a liquid surface which is an interface with the oil chamber 61a. Further, a free piston for partitioning the oil chamber 61a and the spring chamber 61b may be accommodated and stored in the accumulator 61. A free piston for partitioning the oil chamber 61a and the spring chamber 61b may be housed in the accumulator 61 and a spring may be housed in the spring chamber 61b. That is, instead of the pressurized gas, a pressure may be applied to the oil chamber 61a by using a spring.

The characteristics of the accumulator 61 are set by adjusting the gas pressure in the spring chamber 61b, the volume of the accumulator 61, and the like.

The oil chamber 61a is connected to the branch passage 64 branched from the piston chamber 44 in the delivery passage 56 and the operation check valve 53. [ That is, the oil chamber 61a and the piston chamber 44 are connected through the delivery passage 56 and the branch passage 64. The branch passage 64 is provided with an attenuation valve 62 and an opening and closing valve 63 for opening and closing the branch passage 64 is provided adjacent to the damping valve 62.

The opening and closing valve 63 has a communication position 63a for allowing the communication between the piston chamber 44 and the accumulator 61 and a blocking position 63b for blocking the communication between the piston chamber 44 and the accumulator 61 Closing valve.

Normally, the opening / closing valve 63 is in the communicating position 63a, and the piston chamber 44 is in communication with the accumulator 61. In this state, when the vehicle body 91 vibrates up and down to vibrate the lifting cylinder 40, the operating oil flows between the piston chamber 44 and the oil chamber 61a of the accumulator 61. The operating oil introduced into the oil chamber 61a is returned to the piston chamber 44 by the gas pressure of the spring chamber 61b. Thus, the flow of the hydraulic fluid between the piston chamber 44 and the oil chamber 61a is imparted with a resistance by the damping valve 62. Thereby, a damping force is generated, and the vibration of the lifting cylinder 40 can be prevented from being transmitted to the boom 4.

When it is not necessary to reduce the vibration of the boom 4 when the boom 4 is running while the vehicle is running on a low vibration surface, the opening / closing valve 63 is closed by the operator at the blocking position 63b ).

The oil chamber 61a and the piston chamber 44 may be directly connected to each other by a passage independent of the supply passage 56. [ In this case, the damping valve 62 and the opening / closing valve 63 are provided in the independent passage.

The boom sprayer 100 further includes a controller 70 as a control unit for controlling the direction switching valve 52 and the opening / closing valve 63. The controller 70 is a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). A control program or the like executed in the central processing unit is stored in advance in the read-only memory, and data in the processing of the central processing unit is stored in the random access memory. The I / O interface is used for inputting / outputting information to / from an apparatus connected to the controller 70. A signal from an operation panel 71 operated by an operator is input to the controller 70. [

The operation panel 71 is provided with a boom up switch (not shown) operated when raising the boom 4 relative to the vehicle body 91 and a boom down switch operated when the boom 4 is lowered to the vehicle body 91 do. These switches may be a button type that is turned on and off, or a toggle type. A stop switch for stopping the operation of the boom 4 may be provided separately from the boom up switch and the boom down switch. Alternatively, it may be a lever type for operating the rise and fall of the boom 4. In the case of the lever type, the controller 70 determines that the up switch has been turned on when the lever has fallen to one side, determines that the down switch has been turned on when the lever has fallen to the other side, It is determined that the switch is turned off. In the controller 70, control described later is executed based on a signal from the operation panel 71, and the positions of the direction switching valve 52 and the opening / closing valve 63 are switched by the controller 70. [

The controller 70 is not limited to a microcomputer and may have any structure as long as it is capable of appropriately switching the positions of the directional control valve 52 and the open / close valve 63 in response to an operator's operation. For example, it may be a combination of relays or electronic timers. Further, the operation panel 71 may be incorporated in the controller 70.

In the boom sprayer 100 having the above-described configuration, when the boom 4 is raised with respect to the vehicle body 91, an inertial force is temporarily applied to the boom 4. For this reason, in order to quickly raise the boom 4, in addition to the load supporting the boom 4 in the stopped state, a load exceeding the inertial force acting on the boom 4 should be generated by the lifting cylinder 40 do. That is, it is necessary to increase the pressure of the piston chamber 44 of the lifting cylinder 40 by an amount corresponding to the inertial force acting on the boom 4.

Here, in the boom sprayer 100, the piston chamber 44 and the oil chamber 61a of the accumulator 61 are normally communicated. The operating oil flows into the oil chamber 61a of the accumulator 61 communicating with the piston chamber 44 even when the operating oil is supplied from the hydraulic pump 51 to raise the pressure of the piston chamber 44, The spring chamber 61b of the spring 61 is contracted. As the pressure of the accumulator 61 rises as the spring chamber 61b contracts, the pressure in the piston chamber 44 gradually rises. When the pressure of the piston chamber 44 rises by an amount corresponding to the inertial force acting on the boom 4, the lift cylinder 40 is extended and the boom 4 rises with respect to the vehicle body 91.

As described above, the elevating cylinder 40 does not extend unless the pressure of the accumulator 61 rises. Thereby, there is a possibility that the boom 4 may not rise quickly even if the operator performs an operation of raising the boom 4.

When the boom 4 is lowered, the load acting on the lifting cylinder 40 from the boom 4 side is temporally lowered by the inertia as compared with the stopped state. Therefore, when the piston chamber 44 communicates with the oil chamber 61a of the accumulator 61, the hydraulic oil in the oil chamber 61a having a pressure higher than that of the piston chamber 44 is discharged. This causes the elevating cylinder 40 to start to contract after the pressure of the accumulator 61 drops and consequently the boom 4 may not descend quickly even if the operator operates the boom 4 to descend .

On the other hand, in the boom sprayer 100 according to the first embodiment, when the boom up switch or the boom down switch is turned on by the operator, the controller 70 controls the opening / closing valve 63 so that the piston chamber 44 And the oil chamber 61a of the accumulator 61 is blocked. This prevents the hydraulic oil from flowing into the oil chamber 61a when the boom 4 is lifted and prevents the hydraulic oil from flowing out from the oil chamber 61a when the boom 4 is lowered. As a result, it is possible to rapidly raise and lower the boom 4 relative to the vehicle body 91 in accordance with the operation of the operator.

Hereinafter, the processing procedure of the controller 70, which is executed when an operator lifts the boom 4 is performed, will be described in detail. The controller 70 controls the opening / closing valve 63 and the direction switching valve 52 in accordance with the procedure shown in the flowchart of Fig. The flow chart of Fig. 3 shows a processing procedure when the boom 4 is raised.

First, in step S101, the controller 70 detects whether or not the operator has operated the up switch from OFF to ON. The operation panel 71 outputs a signal corresponding to the operation to the controller 70 when the operator operates the up switch.

The controller 70 switches the open / close valve 63 to the shutoff position 63b to stop the operation of the piston chamber 44 and the accumulator (not shown) 61) of the oil chamber (61a). At the same time, the controller 70 switches the directional control valve 52 to the extension position 52a, and makes the piston side chamber 44 and the hydraulic pump 51 communicate with each other.

The communication between the piston chamber 44 and the accumulator 61 is interrupted and the piston chamber 44 and the hydraulic pump 51 are communicated with each other so that the hydraulic fluid discharged from the hydraulic pump 51 is discharged to the oil chamber 61a of the accumulator 61 And flows into the piston chamber 44 without flowing into the piston chamber 44. As a result, the lifting cylinder 40 is rapidly extended against the operation of the operator, and as a result, the response to the lifting operation of the boom 4 can be improved.

Subsequently, in step S103, the controller 70 detects whether or not the operator has operated the up switch from ON to OFF.

The controller 70 switches the directional control valve 52 to the stop position 52c so as to stop the operation of the hydraulic pressure control valve 44 The communication of the pump 51 is cut off. The supply of the hydraulic oil from the hydraulic pump 51 to the piston chamber 44 is stopped and the reverse flow from the piston chamber 44 to the hydraulic pump 51 is blocked by the operation check valve 53, ) Is filled with a predetermined amount of working oil.

The pressure in the piston chamber 44 is lower than the pressure which is equal to the weight of the platform 3 and the boom 4 supported by the lift cylinder 40 from the pressure increased by the amount corresponding to the inertia force, The pressure is gradually lowered until it becomes the pressure before the rising. Further, even if the pressure in the piston chamber 44 decreases, the amount of hydraulic oil charged does not change, so that the amount of extension of the lifting cylinder 40 does not change, and consequently the height of the boom 4 is maintained.

If the communication between the piston chamber 44 and the oil chamber 61a of the accumulator 61 is permitted before the pressure in the piston chamber 44 returns to the pressure before raising the boom 4, The operating oil in the piston chamber 44 moves to the oil chamber 61a because the pressure in the chamber 44 is high. As a result, there is a possibility that the lifting cylinder 40 temporarily shrinks slightly or the operating oil seeps between the piston chamber 44 and the oil chamber 61a, thereby making the lifting amount of the lifting cylinder 40 unstable.

Therefore, a predetermined first retention time t1 for inhibiting the switching valve 63 from switching from the stop position 52c to the communicating position 63a is set. The first retention time t1 is set to a time until the pressure in the piston chamber 44 is returned to the pressure before the boom 4 is raised after the directional control valve 52 is switched to the stop position 52c do.

In step S105, it is determined whether or not the first retention time t1 set in this way has passed since the execution of the step S104.

If it is determined that the first retention time t1 has elapsed, the controller 70 switches the open / close valve 63 to the communicating position 63a in step S106.

The above processing is performed by the controller 70, so that the boom 4 is raised to a desired height.

The lowering of the boom 4 differs from that in the above-described process only in that the direction switching valve 52 is switched to the contracting position 52b instead of the extending position 52a. Therefore, the description thereof will be omitted.

As described above, while the boom 4 is being lifted and lowered, the communication between the piston side chamber 44 and the oil chamber 61a is cut off, whereby the influence of the inertial force acting on the boom 4 can be reliably eliminated. As a result, the responsiveness of the boom 4 to the operation of the operator can be improved.

The communication between the piston chamber 44 and the oil chamber 61a of the accumulator 61 is permitted after a sufficient time has elapsed so that the pressure in the piston chamber 44 returns to the pressure before the boom 4 is raised and lowered . The operating oil is supplied to the piston chamber 44 and the oil chamber 61a due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a after the switching valve 63 is switched to the communication position 63a, ) Is prevented. As a result, after the boom 4 is stopped from being raised or lowered, the elevating cylinder 40 is prevented from elongating or contracting.

The directional control valve 52 is not limited to the type in which the position is switched by the electromagnetic force, and the position may be manually switched. In this case, the operator operates the lever or the like interlocking with the directional control valve 52 to switch to the extension position 52a when the boom 4 is lifted, and when the boom 4 is lowered, When the boom 4 is to be stopped, the operation mode is switched to the stop position 52c. The controller 70 detects the position of the direction switching valve 52 operated by the operator and controls the opening / closing valve 63 based on the detection result. Specifically, the controller 70 switches the open / close valve 63 to the shutoff position 63b when the direction switch valve 52 is operated by the operator to the extension position 52a or the contract position 52b. When the direction switch valve 52 is operated by the operator from the extension position 52a or the retraction position 52b to the stop position 52c after the first retention time t1 has elapsed, The valve 63 is switched to the communicating position 63a.

According to the first embodiment described above, the following effects are exhibited.

The controller 70 switches the open / close valve 63 to the shutoff position 63b to move the boom 4 between the piston chambers 44 and the boom sprayer 100. In the boom sprayer 100, The communication of the oil chamber 61a of the accumulator 61 is cut off. Thus, when raising the boom 4, the hydraulic oil is supplied only to the lifting cylinder 40, and hydraulic oil is prevented from flowing into the oil chamber 61a. Further, when the boom 4 is lowered, the hydraulic oil flows out only from the lifting cylinder 40, and hydraulic oil is prevented from flowing out from the oil chamber 61a. As a result, the responsiveness of the boom 4 to the operation of the operator can be improved.

In the boom sprayer 100, when an operation for stopping the boom 4 is performed by the operator, the controller 70 switches the direction switching valve 52 to the stop position 52c, After the one hold time t1 elapses, the open / close valve 63 is switched to the communicating position 63a. The piston chamber 44 communicates with the oil chamber 61a of the accumulator 61 after a sufficient time has elapsed for the pressure in the piston chamber 44 to return to the pressure before the boom 4 is raised and lowered. The operating oil is supplied to the piston chamber 44 and the oil chamber 61a due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a after the switching valve 63 is switched to the communication position 63a, ) Is prevented. As a result, after the boom 4 is stopped from moving up and down, the lifting cylinder 40 is prevented from expanding and contracting, and the height of the boom 4 relative to the vehicle body 91 can be stabilized.

Hereinafter, a modified example of the boom sprayer 100 according to the first embodiment of the present invention will be described with reference to FIG.

The operation for stopping the boom 4 is performed by the operator and the direction switching valve 52 is switched to the stop position 52c in the first embodiment, And when the predetermined first retention time t1 has elapsed. The operation of raising and lowering the boom 4 is carried out by the operator and the direction switching valve 52 is operated to the extension position 52a or the contracting position 52b ), And may be performed when a predetermined second retention time t2 has elapsed.

As described above, if the communication between the piston chamber 44 and the oil chamber 61a of the accumulator 61 is permitted before the pressure in the piston chamber 44 returns to the pressure before raising the boom 4, the oil chamber 61a The operating oil in the piston chamber 44 moves to the oil chamber 61a because the pressure of the piston chamber 44 is higher than the pressure in the piston chamber 44. [ As a result, there is a possibility that the lifting cylinder 40 temporarily shrinks slightly or the operating oil seeps between the piston chamber 44 and the oil chamber 61a, thereby making the lifting amount of the lifting cylinder 40 unstable.

Here, the pressure in the piston chamber 44 becomes higher than the pressure before raising the boom 4 due to the influence of the inertial force acting on the boom 4. This inertial force acts when the boom 4 is performing the acceleration motion as when the boom 4 is lifted from the stopped state. That is, the boom 4 does not act when the entire boom 4 is raised to a constant speed. This prevents the inertial force from acting on the entire boom 4 when a certain amount of time has elapsed since the boom 4 started to rise so that the pressure in the piston chamber 44 is lower than the pressure before the boom 4 is raised And returned to the pressure.

Therefore, in the modified example, the switching to the communication position 63a of the opening / closing valve 63 is performed after switching the direction switching valve 52 to the extension position 52a or the contracting position 52b, 63 is switched to the cutoff position 63b after the predetermined second hold time t2 has elapsed.

Hereinafter, in the modified example, the processing procedure of the controller 70 executed when the operator moves the boom 4 up and down is described in detail. The controller 70 controls the opening / closing valve 63 and the direction switching valve 52 in accordance with the procedure shown in the flowchart of Fig. In the flowchart of Fig. 4, the processing procedure when the boom 4 is raised is shown.

Steps S111 and S112 are the same as steps S101 and S102 in the first embodiment, and a description thereof will be omitted.

In step S113, it is determined whether or not the second hold time t2 has elapsed since the execution of step S112. The second retention time t2 is a state in which the entire boom 4 is raised to a constant speed after the directional control valve 52 is switched to the extension position 52a and the pressure in the piston chamber 44 is maintained at the boom 4 ) Is raised to the pressure before the pressure is raised.

If it is determined that the second retention time t2 has elapsed, the controller 70 switches the opening / closing valve 63 to the communicating position 63a in step S114.

When the operator turns off the lift switch before the second retention time t2 elapses, the controller 70 switches the directional control valve 52 to the stop position 52c, The communication of the hydraulic pump 51 is cut off. However, the switching of the switching valve 63 to the communication position 63a is not performed until the second holding time t2 elapses, regardless of whether the up switch is turned off. That is, although not shown in the flowchart of Fig. 4, when the controller 70 detects that the up switch is turned off by the operator regardless of whether the second hold time t2 has elapsed, The valve 52 is switched to the stop position 52c and the communication between the piston chamber 44 and the hydraulic pump 51 is cut off.

The lowering of the boom 4 differs from that in the above-described process only in that the direction switching valve 52 is switched to the contracting position 52b instead of the extending position 52a. Therefore, the description thereof will be omitted.

In this modified example, the controller 70 detects the operation of raising and lowering the boom 4 by the operator, switches the open / close valve 63 to the shutoff position 63b, and then the predetermined second hold time t2 is The on-off valve 63 is switched to the communicating position 63a. That is, the communication between the piston chamber 44 and the oil chamber 61a of the accumulator 61 is allowed after a sufficient time has elapsed so that the pressure in the piston chamber 44 returns to the pressure before the boom 4 is raised and lowered . Even if the open / close valve 63 is switched to the communicating position 63a, the operating oil is supplied to the piston chamber 44 and the oil chamber 61a due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a 61a.

The communication between the piston chamber 44 and the oil chamber 61a is permitted without waiting for an operator to stop the operation of raising and lowering the boom 4. As a result, the function of the boom vibration damping device 60 is quickly restored, and the vibration of the vehicle body 91 can be prevented from being transmitted to the boom 4. As a result, the lifting operation of the boom 4 can be performed smoothly without being influenced by the inertia force acting on the boom 4 and the vibration of the vehicle body 91.

≪ Second Embodiment >

A boom sprayer 200 according to a second embodiment of the present invention will be described with reference to Fig. Hereinafter, different points from the first embodiment will be mainly described, and the same components as those of the boom sprayer 100 of the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

The basic configuration of the boom sprayer 200 is the same as that of the boom sprayer 100 according to the first embodiment. In the boom sprayer 100 according to the first embodiment, the switching to the communication position 63a of the opening / closing valve 63 is performed after a predetermined holding time has elapsed, whereas in the boom sprayer 200, The switching to the communication position 63a of the opening and closing valve 63 is performed on the basis of the pressure difference? P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a of the accumulator 61. [

The boom sprayer 200 includes a first pressure sensor 72 installed in the delivery passage 56 for detecting the pressure in the piston chamber 44 and a second pressure sensor 72 provided in the branch passage 64, A second pressure sensor 73 for detecting the pressure in the oil chamber 61a and a differential pressure detector 74 for detecting the difference between the detection value of the first pressure sensor 72 and the detection value of the second pressure sensor 73 Respectively. The differential pressure detector 74 outputs the detected differential pressure DELTA P to the controller 70. [

Here, as described above, when the pressure in the piston chamber 44 allows the piston chamber 44 to communicate with the oil chamber 61a of the accumulator 61 before returning to the pressure before the boom 4 is raised, The operating oil in the piston chamber 44 moves to the oil chamber 61a because the pressure of the piston chamber 44 is higher than that of the oil chamber 61a. As a result, there is a possibility that the lifting cylinder 40 temporarily shrinks slightly or the operating oil seeps between the piston chamber 44 and the oil chamber 61a, thereby making the lifting amount of the lifting cylinder 40 unstable.

In other words, when the pressure in the piston chamber 44 becomes equal to the pressure in the oil chamber 61a, that is, the inertia force does not act on the entire boom 4, The boom 4 can be smoothly continued to rise and the boom 4 can be stably stopped if the piston chamber 44 and the oil chamber 61a are allowed to communicate with each other have.

In the boom sprayer 200, therefore, the switching of the open / close valve 63 to the communicating position 63a is controlled such that the pressure difference? P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a becomes equal to or less than a predetermined threshold value? , That is, when the pressure in the piston chamber 44 and the pressure in the oil chamber 61a become substantially equal to each other.

Hereinafter, the processing procedure of the controller 70 executed when the operator performs the operation of raising and lowering the boom 4 will be described in detail in the second embodiment. The controller 70 controls the opening / closing valve 63 and the direction switching valve 52 in accordance with the procedure shown in the flowchart of Fig. The flow chart of Fig. 6 shows a processing procedure when the boom 4 is raised.

Steps S201 to S204 are the same as steps S101 to S104 in the first embodiment, and a description thereof will be omitted.

In step S205, the controller 70 determines whether or not the pressure difference? P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a input from the differential pressure detector 74 is equal to or less than a predetermined threshold?. The predetermined threshold value a is set to a value at which the operating oil does not substantially go between the piston chamber 44 and the oil chamber 61a and the extension amount of the lifting cylinder 40 is maintained even when the piston chamber 44 communicates with the oil chamber 61a .

If it is determined that the differential pressure DELTA P is equal to or smaller than the threshold value alpha, the controller 70 switches the open / close valve 63 to the communication position 63a in step S206.

The above processing is performed by the controller 70, so that the boom 4 is raised to a desired height.

The lowering of the boom 4 differs from that in the above-described process only in that the direction switching valve 52 is switched to the contracting position 52b instead of the extending position 52a. Therefore, the description thereof will be omitted.

The pressure difference DELTA P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a may be obtained by a differential pressure sensor for detecting the pressure difference between the front and rear of the open / close valve 63. [ Further, the differential pressure detector 74 may be incorporated in the controller 70.

According to the above-described second embodiment, in addition to the operation effect of the first embodiment, the following effects are exhibited.

In the boom sprayer 200, when an operation for stopping the boom 4 is performed by the operator, the controller 70 switches the directional control valve 52 to the stop position 52c, Closing valve 63 to the communicating position 63a when the pressure difference? P between the pressure in the oil chamber 61a and the pressure in the oil chamber 61a becomes equal to or smaller than the predetermined threshold?. The pressure in the piston chamber 44 is returned to the pressure before the boom 4 is raised and lowered and becomes equal to the pressure in the oil chamber 61a and the oil chamber 61a of the piston chamber 44 and the accumulator 61, . Due to this, due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a after the switching valve 63 is switched to the communicating position 63a, the operating oil flows into the piston chamber 44 and the oil chamber 61a.

As in the first embodiment, when it is not necessary to wait for the elapse of the predetermined first retention time t1 and the pressure difference? P is not more than the predetermined threshold?, The piston chamber 44 and the oil chamber 61a ) Are immediately communicated. As a result, the function of the boom damping device 60 is quickly restored, and the vibration of the vehicle body 91 is prevented from being transmitted to the boom 4. As a result, after the elevation of the boom 4 is stopped, the elevation cylinder 40 is prevented from expanding and contracting due to the pressure difference DELTA P, and the vibration of the vehicle body 91 is suppressed from being transmitted to the boom 4 , The height of the boom 4 relative to the vehicle body 91 can be stabilized.

Hereinafter, a modified example of the boom sprayer 200 according to the second embodiment of the present invention will be described with reference to Fig.

The operation for stopping the boom 4 is performed by the operator and the directional control valve 52 is switched to the stop position 52c in the second embodiment in order to switch the open / close valve 63 to the communication position 63a And then, based on the pressure difference? P. The operation of raising and lowering the boom 4 is carried out by the operator and the direction switching valve 52 is operated to the extension position 52a or the contracting position 52b ), And then, based on the pressure difference? P.

Hereinafter, in the modified example, the processing procedure of the controller 70 executed when the operator moves the boom 4 up and down is described in detail. The controller 70 controls the opening / closing valve 63 and the direction switching valve 52 in accordance with the procedure shown in the flowchart of Fig. In the flowchart of Fig. 7, the processing procedure when the boom 4 is raised is shown.

Step S211 and step S212 are the same as steps S201 and S202 in the second embodiment, and a description thereof will be omitted.

In step S213, the controller 70 determines whether or not the pressure difference? P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a input from the differential pressure detector 74 is less than or equal to a predetermined threshold?.

If it is determined that the differential pressure DELTA P is equal to or smaller than the threshold value alpha, the controller 70 switches the open / close valve 63 to the communication position 63a in step S214.

When the operator turns off the lift switch before the differential pressure? P becomes equal to or less than the threshold?, The controller 70 switches the directional control valve 52 to the stop position 52c, The communication of the hydraulic pump 51 is cut off. However, the switching to the communication position 63a of the opening / closing valve 63 is not performed until the differential pressure? P becomes equal to or smaller than the threshold value? Irrespective of whether the up switch is turned off. 7, when the controller 70 detects that the lift switch has been turned off by the operator regardless of whether the differential pressure? P is equal to or smaller than the threshold?, The controller 70 determines whether or not the direction The switching valve 52 is switched to the stop position 52c and the communication between the piston chamber 44 and the hydraulic pump 51 is cut off.

The lowering of the boom 4 differs from that in the above-described process only in that the direction switching valve 52 is switched to the contracting position 52b instead of the extending position 52a. Therefore, the description thereof will be omitted.

The controller 70 detects the operation of raising and lowering the boom 4 by the operator to switch the open / close valve 63 to the shutoff position 63b, Off valve 63 to the communicating position 63a when the pressure difference? P of the pressure in the pressure chamber 61a becomes equal to or smaller than the threshold?. The pressure in the piston chamber 44 is returned to the pressure before the boom 4 is raised and lowered and becomes equal to the pressure in the oil chamber 61a and the oil chamber 61a of the piston chamber 44 and the accumulator 61, . Even if the open / close valve 63 is switched to the communication position 63a, the operating oil is supplied to the piston chamber 44 and the oil chamber 61a due to the pressure difference between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a ) Is prevented.

The communication between the piston chamber 44 and the oil chamber 61a is permitted without waiting for an operator to stop the operation of raising and lowering the boom 4. As a result, the function of the boom vibration damping device 60 is quickly restored, and the vibration of the vehicle body 91 can be prevented from being transmitted to the boom 4. As a result, the lifting operation of the boom 4 can be performed smoothly without being influenced by the inertia force acting on the boom 4 and the vibration of the vehicle body 91.

Hereinafter, the structure, action, and effect of the embodiment of the present invention will be summarized.

The boom lifting device comprises a platform 3 capable of lifting and lowering with respect to the vehicle body 91, a boom 4 having one end supported by the platform 3 and the other end provided as a free end for spraying the chemical liquid, A working fluid delivery device 50 for supplying the working fluid to the elevating cylinder 40 and raising and lowering the boom 4 relative to the vehicle body 91, An accumulator 61 connected to the elevating cylinder 40 for storing the pressurized hydraulic fluid and an opening and closing valve 63 for opening and closing a passage for communicating the elevating cylinder 40 and the accumulator 61, And a controller 70 for controlling the opening and closing valve 63. The controller 70 is characterized in that it closes the opening and closing valve 63 when detecting an operation of raising or lowering the boom 4 by the operator .

The controller 70 switches the open / close valve 63 to the shutoff position 63b to move the piston chamber 44 and the accumulator 61 to the closed position 63b, Thereby preventing the communication of the oil chamber 61a. Thus, when raising the boom 4, the hydraulic fluid is supplied only to the lifting cylinder 40, and hydraulic fluid is prevented from flowing into the accumulator 61. [ Further, when the boom 4 is lowered, the hydraulic oil flows out only from the lifting cylinder 40, and hydraulic oil is prevented from flowing out from the oil chamber 61a. As a result, the responsiveness of the boom 4 to the operation of the operator can be improved.

The working fluid power feeding device 50 includes a hydraulic pump 51 for supplying working fluid to the elevating cylinder 40, a tank T for guiding the working fluid discharged from the elevating cylinder 40, And the direction switching valve 52 for switching the connecting state of the hydraulic pump 51 and the connecting state of the elevating cylinder 40 and the tank T respectively and the direction switching valve 52 is connected to the elevating cylinder 40 The controller 70 has an operating position for operating the boom 4 and a position for stopping the elevating cylinder 40. The controller 70 detects the operation for raising and lowering the boom 4 by the operator The switching valve 63 is closed and the direction switching valve 52 is switched to the extension position 52a or the contracting position 52b.

The controller 70 switches the open / close valve 63 to the shutoff position 63b to move the piston chamber 44 and the accumulator 61 to the closed position 63b, Thereby preventing the communication of the oil chamber 61a. The controller 70 also switches the directional control valve 52 to the extended position 52a or the retracted position 52b. Thus, when raising the boom 4, the hydraulic fluid is supplied only to the lifting cylinder 40, and hydraulic fluid is prevented from flowing into the accumulator 61. [ Further, when the boom 4 is lowered, the hydraulic oil flows out only from the lifting cylinder 40, and the hydraulic oil is prevented from flowing out from the oil chamber 61a. As a result, the responsiveness of the boom 4 to the operation of the operator can be improved.

The controller 70 is configured to open the on-off valve 63 after a predetermined first retention time t1 elapses after detection of an operation for stopping the elevation of the boom 4 by the operator .

In this configuration, when an operation for stopping the boom 4 is performed by the operator, the controller 70 switches the directional control valve 52 to the stop position 52c, and when the predetermined first retention time t1 elapses The on-off valve 63 is switched to the communicating position 63a. The piston chamber 44 and the oil chamber 61a of the accumulator 61 are communicated with each other after a sufficient time has elapsed for the pressure in the piston chamber 44 to return to the pressure before the boom 4 is raised and lowered. Due to this, due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a after the switching valve 63 is switched to the communicating position 63a, the operating oil flows into the piston chamber 44 and the oil chamber 61a. As a result, after the boom 4 is stopped from moving up and down, the lifting cylinder 40 is prevented from expanding and contracting, and the height of the boom 4 relative to the vehicle body 91 can be stabilized.

The boom elevating apparatus further includes a differential pressure detecting section 74 for detecting a differential pressure between the pressure of the elevating cylinder 40 and the pressure of the accumulator 61. The controller 70 controls the boom 4 by the operator, Closing valve (63) is opened when the pressure difference detected by the differential pressure detector (74) becomes equal to or less than a predetermined threshold alpha after the detection.

In this configuration, when an operation for stopping the boom 4 is performed by the operator, the controller 70 switches the directional control valve 52 to the stop position 52c, Closing valve 63 is switched to the communication position 63a when the pressure difference? P of the pressure in the oil chamber 61a becomes equal to or less than the predetermined threshold?. The pressure in the piston chamber 44 is returned to the pressure before the boom 4 is raised and lowered and becomes equal to the pressure in the oil chamber 61a and the oil chamber 61a of the piston chamber 44 and the accumulator 61, . Due to this, due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a after the switching valve 63 is switched to the communicating position 63a, the operating oil flows into the piston chamber 44 and the oil chamber 61a. As a result, after the boom 4 is stopped from moving up and down, the lifting cylinder 40 is prevented from expanding and contracting, and the height of the boom 4 relative to the vehicle body 91 can be stabilized.

The controller 70 detects the operation of raising and lowering the boom 4 by the operator and closes the on-off valve 63. After the predetermined second retention time t2 elapses, the on- .

In this configuration, the controller 70 detects the operation of raising and lowering the boom 4 by the operator regardless of whether or not there is an operation for stopping the boom 4, and sets the opening / closing valve 63 to the shutoff position 63b The switching valve 63 is switched to the communication position 63a after a predetermined second retention time t2 has elapsed after the switching. That is, the communication between the piston chamber 44 and the oil chamber 61a of the accumulator 61 is allowed after a sufficient time has elapsed so that the pressure in the piston chamber 44 returns to the pressure before the boom 4 is raised and lowered . Even if the open / close valve 63 is switched to the communicating position 63a, the operating oil is supplied to the piston chamber 44 and the oil chamber 61a due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a 61a. As a result, the boom 4 can be smoothly lifted and lowered without being influenced by the inertia force acting on the boom 4.

The boom elevating apparatus further includes a differential pressure detecting section 74 for detecting a differential pressure between the pressure of the elevating cylinder 40 and the pressure of the accumulator 61. The controller 70 controls the boom 4 by the operator, Off valve 63 is closed when the pressure difference detected by the differential pressure detector 74 reaches a predetermined threshold value alpha or less.

In this configuration, the controller 70 detects the operation of raising and lowering the boom 4 by the operator regardless of whether or not there is an operation for stopping the boom 4, and sets the opening / closing valve 63 to the shutoff position 63b The switching valve 63 is switched to the communication position 63a when the pressure difference? P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a becomes equal to or smaller than the threshold?. The pressure in the piston chamber 44 is returned to the pressure before the boom 4 is raised and lowered and becomes equal to the pressure in the oil chamber 61a and the oil chamber 61a of the piston chamber 44 and the accumulator 61, . Even if the open / close valve 63 is switched to the communicating position 63a, the operating oil is supplied to the piston chamber 44 and the oil chamber 61a due to the pressure difference between the pressure of the piston chamber 44 and the pressure of the oil chamber 61a 61a. As a result, the boom 4 can be smoothly lifted and lowered without being influenced by the inertia force acting on the boom 4.

The boom sprayers (100, 200) are provided with the boom lifting device.

With this configuration, the boom lifting / lowering device can be provided so that the boom 4 can be moved up and down with respect to the vehicle body 91 in response to an operator's operation.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments.

For example, different control may be employed in the case of raising and lowering the boom 4. For example, when the boom 4 is raised, when the shutoff valve 63 is switched to the communication position 63a and the boom 4 is lowered after a predetermined time has elapsed after the stop operation is performed, The on-off valve 63 may be switched to the communicating position 63a after a predetermined time has elapsed after the start of the descending operation regardless of the stop operation. When the boom 4 is raised, the open / close valve 63 is switched to the communication position 63a based on the pressure difference? P between the pressure in the piston chamber 44 and the pressure in the oil chamber 61a, 4), the on-off valve 63 may be switched to the communicating position 63a based on the elapsed time.

The present application claims priority based on Japanese Patent Application No. 2015-144245 filed on July 21, 2015, the entire contents of which are incorporated herein by reference.

Claims (7)

An elevating member capable of elevating with respect to the vehicle body,
A boom having one end supported by the lifting member and the other end provided as a free end to spray liquid,
A hydraulic pressure cylinder interposed between the vehicle body and the elevation member,
A working fluid dispensing device for supplying a working fluid to the hydraulic cylinder and raising and lowering the boom with respect to the vehicle body;
An accumulator connected to the hydraulic cylinder and storing the pressurized working fluid;
An opening / closing valve for opening / closing a passage for communicating the hydraulic cylinder and the accumulator,
And a control unit for controlling said open / close valve in accordance with an operation of an operator,
Wherein the control unit closes the opening / closing valve when detecting an operation of raising / lowering the boom by an operator. The method according to claim 1,
The working fluid delivery device may include:
A hydraulic pump for supplying working fluid to the hydraulic cylinder,
A tank in which a working fluid discharged from the hydraulic cylinder is guided,
A switching valve for switching between a connection state of the hydraulic cylinder and the hydraulic pump and a connection state of the hydraulic cylinder and the tank,
The switching valve has an operating position for operating the hydraulic cylinder and a stop position for stopping the hydraulic cylinder,
Wherein the control unit closes the on-off valve and switches the switching valve to the operating position when detecting an operation of raising and lowering the boom by the operator. 3. The method according to claim 1 or 2,
Wherein the control section opens the opening / closing valve after a predetermined first holding time has elapsed after detection of an operation for stopping the elevation of the boom by the operator. 3. The method according to claim 1 or 2,
Further comprising a differential pressure detector for detecting a pressure difference between the pressure of the hydraulic cylinder and the pressure of the accumulator,
Wherein the control unit opens the opening / closing valve when an operation for stopping the elevation of the boom by the operator is detected, and after the detection, the pressure difference detected by the differential pressure detection unit becomes a predetermined threshold value or less. 3. The method according to claim 1 or 2,
Wherein the control unit detects an operation of raising and lowering the boom by the operator and closes the on-off valve, and then opens the on-off valve after a predetermined second retention time has elapsed. 3. The method according to claim 1 or 2,
Further comprising a differential pressure detector for detecting a pressure difference between the pressure of the hydraulic cylinder and the pressure of the accumulator,
The boom elevating apparatus according to any one of claims 1 to 3, wherein the control unit detects an operation of raising and lowering the boom by an operator and closes the opening / closing valve, then opens the opening / closing valve when the pressure difference detected by the differential pressure detecting unit becomes a predetermined threshold value or less . A boom sprayer comprising the boom lifting device according to claim 1 or 2.

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