JPH061392U - Leveling equipment for aerial work vehicles - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a leveling device capable of avoiding a delay in the leveling control of a work table at the beginning of the boom hoisting operation in a high-altitude work vehicle. [Structure] The leveling device 20 operates from the start of operation of a hydraulic pump 31 that discharges pressure oil supplied to a boom 35,
The boom 35 of the pressure oil discharged by the hydraulic pump 31
The pressure increase permitting means 25 is provided for restricting the supply to the inside of the leveling oil passages 23 and 24 while connecting the lower leveling cylinder 21 and the upper leveling cylinder 22. Further, this boosting permission means 2
When the hydraulic pressure in the leveling oil passages 23 and 24 reaches a predetermined pressure by 5, the supply regulation of the pressure oil to the boom 35 by the pressurizing allowance means 25 is released, while the pressure to the leveling oil passages 23 and 24 is released. Also provided is a pressure increasing stop means 27 for stopping the oil supply.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a leveling device for keeping a work platform horizontal in response to a boom undulation operation in an aerial work vehicle.

[0002]

[Prior art]

 The boom of the aerial work vehicle has a boom that can be freely moved up and down and extended, and a workbench is attached to the tip of the boom. In addition, it is necessary to keep the work platform horizontal so that the worker can be stably placed on the work table regardless of the boom erection operation. For this reason, a lower leveling cylinder that is expanded and contracted by the hoisting operation of the boom is installed between the vehicle body and the boom, and the work table is swung up and down by the expansion and contraction operation between the boom and the work table. An upper leveling cylinder that keeps this horizontal (hereinafter referred to as leveling control) is installed.

The oil chambers of both of these leveling cylinders are connected to one of the oil chambers of the opposite leveling cylinders via a leveling oil passage formed by a hydraulic hose or the like, and the boom is raised and lowered. The pressure oil discharged from the compression-side oil chamber of the expanding and contracting lower leveling cylinder flows into the expanding-side oil chamber of the upper leveling cylinder, whereby the upper leveling cylinder is expanded and contracted. The upper leveling cylinder supports the weight (moment) of the workbench and swings the workbench up and down. Especially, when the workbench is swung upward against its weight. The upper leveling cylinder requires a high hydraulic pressure supply.

[0004]

[Problems to be solved by the device]

 However, oil, which is an incompressible fluid, is sealed for a long time in the oil chamber of the lower leveling cylinder and the leveling oil passage connected to this oil chamber, the volume of which can easily fluctuate due to boom vibration or the like. Is difficult. Therefore, for example, when an aerial work vehicle arrives at the work site and tries to raise and lower the boom from the retracted state, the hydraulic pressure in the oil chamber of the lower leveling cylinder and the oil passage for leveling becomes almost zero. It often becomes. Therefore, even if the boom is raised and lowered as it is, work will continue until the lower leveling cylinder extends and the hydraulic pressure in the leveling oil passage rises to the high pressure required to operate the upper leveling cylinder. The platform leveling control may not be started and the work platform may not be kept horizontal.

The present invention has been made in view of the above problems, and provides a leveling device for an aerial work vehicle capable of avoiding a delay in the leveling control of the work table at the beginning of the boom hoisting operation. The purpose is to do.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the leveling device of the present invention regulates the supply of the pressure oil discharged by the hydraulic pump to the boom from the start of the operation of the hydraulic pump that discharges the pressure oil supplied to the boom. On the other hand, it is provided with a pressurization permitting means for permitting supply to the inside of the leveling oil passage connecting the lower leveling cylinder and the upper leveling cylinder. Further, when the hydraulic pressure in the leveling oil passage reaches a predetermined pressure by the boost permitting means, the supply regulation of the pressure oil to the boom by the boost permitting means is released, while the pressure oil is supplied to the leveling oil passage. It also has a step-up stopping means for stopping.

[0007]

[Action]

 In such a leveling device, for example, when an aerial work vehicle arrives at the work site and starts the hydraulic pump to start the work, first, the pressure allowing means supplies the pressure oil to the boom. Is regulated. On the other hand, pressure oil is supplied into the leveling oil passage to increase the oil pressure in the leveling oil passage. Then, when the hydraulic pressure in the leveling oil passage reaches a predetermined high pressure, the pressurization stopping means stops the supply of the pressure oil to the leveling oil passage, while removing the regulation of the supply of the pressure oil to the boom. The boom can be raised. In this way, by setting the high-pressure inside the leveling oil passage before allowing the boom to stand up, the leveling control can be started without delaying the boom stand up operation.

[0008]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows an aerial work vehicle 10 equipped with a leveling device according to the present invention. A swivel base 12 is attached to a front portion of a vehicle body 11 of the aerial work vehicle 10 such that the swivel base 12 can freely swivel horizontally with respect to the vehicle body 11. Then, a boom 13 configured to be telescopically extendable is attached to the upper portion of the swivel base 12. Each operation of the swivel base 12 and the boom 13 is performed using hydraulic pressure. A workbench 16 is attached to the tip of the boom 13 via a vertical post 14 and a support arm 15 extending horizontally from the vertical post 14. An operator M can board the work table 16 and move to any desired height through the operation of the swivel base 12 and the boom 13.

By the way, the workbench 16 needs to be maintained horizontally corresponding to the undulating operation of the boom 13 so that the worker M can be stably boarded. For this reason, the aerial work vehicle 10 is provided with the leveling device 20 according to the present invention. This leveling device 20 includes a lower leveling cylinder 21 mounted between the upper part of the swivel base 12 (vehicle body) and the lower surface of the base end part of the boom 13, and a lower part than the pivot part of the vertical post 14 at the tip part of the boom 13. And an upper leveling cylinder 22 mounted between the leveling arms 14a (workbench) protruding rightward from the vertical post 14.

As shown in FIG. 2, the rod-side oil chamber 21 a of the lower leveling cylinder 21 and the rod-side oil chamber 22 a of the upper leveling cylinder 22 are connected via a rod-side hydraulic hose (oil passage for leveling) 23. (Hereinafter, these are collectively referred to as the rod side hydraulic system.) The bottom side oil chamber 21b of the lower leveling cylinder 21 and the bottom side oil chamber 22b of the upper leveling cylinder 22 are connected via a bottom side hydraulic hose (oil passage for leveling) 24 (hereinafter, these will be summarized. It is called the bottom side hydraulic system.)

When the boom 13 is erected, the lower leveling cylinder 21 extends while discharging pressure oil from the rod side oil chamber 21a. The discharged pressure oil flows into the rod-side oil chamber 21a of the upper leveling cylinder 22 via the rod-side hydraulic hose 23, and causes the upper leveling cylinder 22 to contract. As a result, the support arm 15 and the workbench 16 are swung upward with respect to the boom 13 and are horizontally leveled. On the other hand, when the boom 13 falls down, the lower leveling cylinder 21 contracts while discharging pressure oil from the bottom oil chamber 22b. The discharged pressure oil flows into the bottom side oil chamber 22b of the upper leveling cylinder 22 via the bottom side hydraulic hose 24, and extends the upper leveling cylinder 22. As a result, the support arm 15 and the workbench 16 are swung downward with respect to the boom 13 and are horizontally leveled.

A double pilot check valve 25 is provided between the hydraulic hoses 23, 24 and the oil chambers 22 a, 22 b of the upper leveling cylinder 22 to reduce the hydraulic pressure in the hydraulic hoses 23, 24. Even when the work is done, the work table 16 is held horizontally.

Here, as shown in FIG. 1, since the upper leveling cylinder 22 is pulled in the extending direction by the moment B generated by the weight of the workbench 16, the hydraulic pressure on the rod side is reduced when the upper leveling cylinder 22 is contracted. High hydraulic pressure is required in the system (21a, 23, 22a). However, as shown by the chain line in FIG. 1, when the work vehicle 10 is run with the boom 13 stored in the vehicle body 11, the vibration of the boom 13 at that time causes the oil on the rod side of the lower leveling cylinder 21 to vibrate. The volume of the chamber 21a fluctuates, and the hydraulic pressure of the rod side hydraulic system (21a, 23, 22a) decreases. Therefore, when the boom 13 in the retracted state is erected, a considerable amount of pressure oil is discharged from the rod side oil chamber 21a of the lower leveling cylinder 21, and the rod side oil pressure system (21a, 23, 22a) is discharged. The start of the leveling control will be delayed until the hydraulic pressure in the system rises to the required pressure.

Further, the bottom side hydraulic system (21b, 24, 22b) also needs to have a higher hydraulic pressure to some extent, though not to the extent of the rod side oil chamber 22a. Therefore, the leveling device 20 can increase the pressure in the rod-side hydraulic system (21a, 23, 22a) and the bottom-side hydraulic system (21b, 24, 22b) in which the pressure has dropped to a predetermined high pressure state. , A boost permitting circuit 25.

The boost permission circuit 25 includes a boom interlock valve 25a and a boost interlock valve 25b. The boom interlock valve 25a is a two-position type electromagnetic switching valve, which is located at the down position when the solenoid is not excited and swings the discharge line 32 connected to the discharge port of the hydraulic pump 31. It is connected to a boom hydraulic circuit 35 that controls the supply of pressure oil to the platform 12 and the boom 13. On the other hand, when the solenoid is excited, the discharge line 32 is cut off at the upper position.

Here, as shown in FIG. 1, the hydraulic pump 31 is built in the front portion of the vehicle body 11 and is driven by the output of the traveling engine 41 taken out by the power take-off mechanism 42. The power take-off mechanism 42 can be freely switched on and off. When the hydraulic pump 31 is driven by the output of the running engine 41, the power take-off mechanism 42 is turned on, and when the drive wheels 45 are driven, the power take-off mechanism 42 is turned off. Done

The boost interlock valve 25 b is provided on a boost line 26 that branches from the discharge line 32 and connects to the rod side hydraulic hose 23 and the bottom side hydraulic hose 24. The boosting interlock valve 25b is a two-position type electromagnetic switching valve, and when the solenoid is not excited, it is located in the down position and shuts off the boosting line 26. On the other hand, when the solenoid is excited, the booster line 26 is opened at the upper position. The booster line 26 is branched into two downstream from the booster interlock valve 25b, the first branch passage 26a is connected to the rod side hydraulic hose 23, and the second branch passage 26b is connected to the bottom side hydraulic line. It is connected to the hose 24. A check valve 26c is mounted on the first branch path 26a and the second branch path 26b. The check valve 26c allows the rod side hydraulic system (21a, 23, 22a) and the bottom side hydraulic system ( 21b, 24, 22b) to prevent the pressure oil from flowing back into the respective branch passages 26a, 26b.

Further, the leveling device 20 also includes a boost stop circuit 27. The boosting stop circuit 27 is composed of two pressure sensors 27a and 27b and a residual pressure release valve 27c. The pressure sensors 27a and 27b are mounted upstream of the check valves 26c in the first branch path 26a and the second branch path 26b of the booster line 26, and the hydraulic pressure in the branch paths 26a and 26b, that is, A detection signal is output when the hydraulic pressure in the rod side hydraulic system (21a, 23, 22a) and the bottom side hydraulic system (21b, 24, 22b) rises to a predetermined pressure set for each system.

The residual pressure release valve 27c is a two-position type solenoid operated directional control valve, which is located in the left-hand position when the solenoid is not excited, and branches from the middle portion of the booster line 26 to the oil tank T. The connected drain line 28 is cut off. On the other hand, when the solenoid is excited, the drain line 28 is opened at the right movement position.

The boom interlock valve 25a and the boost interlock valve 25b in the boost allowance circuit 25, and the residual pressure release valve 27c in the boost stop circuit 26 are controlled by the controller 29. The control of these valves by the controller 29 will be described below when the boom 13 is raised from the retracted state.

The controller 29 first detects whether or not the power take-off mechanism 42 has been turned on through the operation detector 29 a attached to the power take-off mechanism 42. When it is detected that the switch has been turned on, the solenoids of the boom interlock valve 25a and the boost interlock valve 25b are excited to move them upward. As a result, the pressure oil discharged from the hydraulic pump 31 whose driving by the traveling engine 41 is started is not supplied to the boom hydraulic circuit 35, but is supplied to the rod side hydraulic pressure in the leveling device 20 through the pressure rising line 26. It flows into the system (21a, 23, 22a) and the bottom side hydraulic system (21b, 24, 22b). Therefore, the boom 13 cannot be erected at this point.

In this way, when the hydraulic pressures in the rod side hydraulic system (21a, 23, 22a) and the bottom side hydraulic system (21b, 24, 22b) respectively rise to predetermined pressures, the pressure sensors 27a, 27b cause the controller 29 to operate. A detection signal is output to. The controller 29, which receives the detection signals from both the pressure sensors 27a and 27b, stops the excitation of the solenoids of the boom interlock valve 25a and the boost interlock valve 25b and moves them downward. As a result, the pressure oil discharged from the hydraulic pump 31 is supplied to the boom hydraulic circuit 35 in place of the booster line 26, and the standing operation of the boom 13 is permitted for the first time. When the stand-up operation of the boom 13 is started, the hydraulic pressures in the rod side hydraulic system (21a, 23, 22a) and the bottom side hydraulic system (21b, 24, 22b) have already been used to extend the upper leveling cylinder 22. Since the required high pressure is reached, the leveling control of the workbench 16 is also started almost at the same time. Therefore, the workbench 16 is surely kept horizontal from the beginning of the stand-up operation of the boom 13, and the worker M on the workbench 16 can be stably moved to a high place.

At the same time as stopping the excitation of the solenoids of the boom interlock valve 25a and the boost interlock valve 25b, the controller 29 excites the solenoid of the residual pressure release valve 27c and moves it to the right. As a result, the high pressure oil remaining in the boosting line 26 is drained to the oil tank T, and the pressure switches 27a and 27b also return to the undetected state. The residual pressure release valve 27c is held in the right moving position for a predetermined time, and then the solenoid is deenergized to return to the left moving position.

When the boom 13 is moved upright to move the workbench 16 to a high place, the boom 13 is stopped and the workbench 16 is kept at the high place for a while. There is. In this case, since it is not necessary to discharge the pressure oil from the hydraulic pump 31, the traveling engine 41 is often stopped to save fuel (however, the power take-off mechanism 42 is not turned on). Up to.). When the running engine 41 is temporarily stopped in this way, when the running engine 41 is started next time, the controller 29 detects that the power take-off mechanism 42 is in the on-operation, and the boom 29 The solenoids of the interlock valve 25a and the boost interlock valve 25b are not excited. Therefore, when the traveling engine 41 is next started, the boom 13 and the like can be immediately actuated, and in this case, the inside of the rod side hydraulic system (21a, 23, 22a) and the bottom side hydraulic system are activated. Since the hydraulic pressure drop of (21b, 24, 22b) does not become so large, the leveling control of the workbench 16 is started without delay.

[0025]

[Effect of device]

 As described above, according to the leveling device of the present invention, immediately after the hydraulic pump is started, the hydraulic pressure in the leveling oil passage and each leveling cylinder communicating therewith is automatically increased to a predetermined high pressure. On the other hand, the undulating operation of the boom is restricted until the increase of the hydraulic pressure is completed. As a result, when the boom stored in the vehicle body is erected, the work platform leveling control can be started without delaying the boom erection operation. Therefore, the worker can board the workbench in a stable state from the beginning of the stand-up operation of the boom, and can safely move to a high place.

[Brief description of drawings]

FIG. 1 is a side view of an aerial work vehicle equipped with a leveling device according to the present invention.

FIG. 2 is a configuration diagram of the leveling device.

[Explanation of symbols]

 13 boom 16 workbench 20 leveling device 21 lower leveling cylinder 22 upper leveling cylinder 23, 24 hydraulic hose (oil passage for leveling) 25 booster permitting circuit 27 booster stopping circuit 29 controller

Claims (1)

[Scope of utility model registration request] 1. An aerial work vehicle, comprising a boom mounted on a vehicle body, which is undulated by the supply of pressure oil, and a workbench is attached to a tip of the boom. The boom is mounted between the vehicle body and the boom. The lower leveling cylinder that is expanded and contracted by the boom undulation operation, and the work that is installed between the boom and the workbench and is expanded and contracted by receiving the supply of the pressure oil discharged from the expanded and contracted lower leveling cylinder. A leveling device for an aerial work vehicle, comprising: an upper leveling cylinder that swings the platform up and down to maintain the horizontal position, from the start of operation of a hydraulic pump that discharges pressure oil supplied to the boom. While restricting the supply of the pressure oil discharged by this hydraulic pump to the boom, the lower leveling cylinder and the upper level of the pressure oil are regulated. A pressure-increasing permitting means for permitting supply to the leveling oil passage connecting between the ring cylinders, and when the hydraulic pressure in the leveling oil passage is increased to a predetermined pressure by the pressure-increasing permitting means, the pressure oil is increased by the pressure-increasing permitting means. A leveling device for an aerial work vehicle, comprising: a supply restriction for the boom and a pressurization stop means for stopping the supply of pressure oil to the leveling oil passage.