JP6784070B2 - Pressure booster for aerial work platforms - Google Patents

Description

The present invention relates to a pressure booster. More specifically, the present invention relates to a pressure booster for aerial work platforms that supplies boosted hydraulic oil to hydraulic tools.

Conventionally, aerial work platforms are known in which a bucket on which an operator is boarded is provided at the tip of a telescopic boom. The aerial work platform is configured so that hydraulic oil can be supplied to hydraulic equipment such as hydraulic tools in the bucket. The aerial work platform for electrical wiring work is configured to be able to supply hydraulic oil to a hydraulic crimping tool, which is a hydraulic tool that connects power lines by crimping a sleeve for electrical wiring. In the aerial work platform configured in this way, a pressure boosting device for supplying the pressure boosted hydraulic oil is provided. For example, as described in Patent Document 1.

The pressure booster for aerial work platforms described in Patent Document 1 controls the pressure boosting cylinder by switching between the directional control valve on the upstream side and the directional control valve on the downstream side to boost the oil pressure of the hydraulic oil. In the pressure booster, a downstream directional control valve is connected in series to an upstream directional control valve to which hydraulic oil is supplied from a hydraulic pump. The directional control valve on the upstream side selectively supplies hydraulic oil to the rod side oil chamber of the booster cylinder to perform a return operation of the hydraulic crimping tool, and a state of supplying hydraulic oil to the directional control valve on the downstream side. It is configured to switch. The directional control valve on the downstream side supplies the hydraulic oil to the hydraulic crimping tool without boosting the pressure to temporarily hold the hydraulic crimping tool, and supplies the hydraulic oil to the oil chamber on the head side of the boosting cylinder. It is configured to selectively switch to the state where the hydraulic oil is increased and the main compression operation of the hydraulic crimping tool is performed.

In the pressure booster for aerial work platforms described in Patent Document 1, a pressure switch is connected to the pressure boosting oil chamber of the pressure boosting cylinder, and whether or not the oil pressure in the pressure boosting oil chamber exceeds a predetermined pressure is determined. Can be detected. The pressure switch and the directional control valve are connected to the control means, and are configured to be switched to a state in which a return operation is performed when the pressure switch detects that the pressure exceeds a predetermined pressure.

Japanese Unexamined Patent Publication No. 2014-20543

When performing caulking work in the pressure boosting chamber (pressure boosting oil chamber) of the pressure booster for aerial work platforms and the state where hydraulic oil remains in the hydraulic tool (state where there is pressure), the hydraulic cylinder of the hydraulic tool It was sometimes difficult to grip the sleeve because it was not fully contracted. Therefore, when the pressure booster is started, the directional control valve is switched so as to discharge the hydraulic oil of the pressure booster chamber and the hydraulic tool to release the pressure.

However, the pressure switch of the pressure booster for aerial work platforms described in Patent Document 1 can only determine whether or not the pressure in the pressure boosting chamber has reached a specified pressure. Therefore, even if an attempt is made to discharge the hydraulic oil of the pressure boosting chamber and the hydraulic tool before the caulking work, the pressure in the pressure boosting chamber cannot be detected, so whether the hydraulic oil of the pressure boosting chamber and the hydraulic tool is completely discharged. I did not understand.
Therefore, an object of the present invention is to provide a pressure booster for an aerial work platform capable of starting work in a state where hydraulic oil of a pressure booster chamber and a hydraulic tool is discharged.

The problem to be solved by the present invention is as described above, and next, the means for solving this problem will be described.

That is, the pressure booster for the high-altitude work vehicle is a pressure booster for the high-altitude work vehicle that supplies the hydraulic oil boosted by the pressure-increasing cylinder to the flood control tool. A supply oil passage connecting the hydraulic tool, an electromagnetic switching valve for preloading hydraulic oil to the supply oil passage, a pressure increasing state for supplying hydraulic oil to the head side oil chamber of the pressure increasing cylinder, and the above. An electromagnetic switching valve for main pressure that can be selectively switched between a depressurized state in which hydraulic oil is supplied to the oil chamber on the rod side of the pressure boosting cylinder and the hydraulic oil in the supply oil passage is discharged, and the pressure boosting chamber. A pressure detecting means for detecting the pressure of the above, and a control device for controlling the operation of the electromagnetic switching valve for preload and the electromagnetic switching valve for main pressure based on the detection value of the pressure detecting means. When the detected value of the pressure detecting means exceeds the reference pressure before the work with the tool is performed, the control device switches the electromagnetic switching valve for the main pressure to the reduced pressure state so that the detected value becomes the reference pressure. ..

In the pressure booster for aerial work platforms , the control device detects a failure based on the detection value of the pressure detecting means after the solenoid valve for main pressure is depressurized.

Pressure booster for aerial vehicle, said control device connected to the alarm unit further comprises to said control device, when detecting the failure, generating an alarm by using the alarm means.

In the pressure boosting device for aerial work platforms , when the detection value of the pressure detecting means before the work with the hydraulic tool exceeds the reference value, the control device is said to be said during the work of the hydraulic tool. It is configured to prolong the time of the decompressed state.

According to the present invention, smooth work can be realized by starting the work in a state where the hydraulic oil of the pressure boosting chamber and the hydraulic tool is discharged.

The side view which shows the whole structure of the aerial work platform which concerns on this invention. The figure which shows the hydraulic circuit of the pressure booster for the aerial work platform which concerns on this invention. The figure which shows the control structure of the pressure booster for aerial work platforms which concerns on this invention. The figure which shows the operation mode of the hydraulic tool connected to the pressure booster for the aerial work platform which concerns on this invention. The figure which shows the operation mode of the hydraulic circuit at the time of the temporary holding operation in the pressure booster for aerial work platforms which concerns on this invention. The figure which shows the operation mode of the hydraulic circuit of the preload stage at the time of this compression operation in the pressure booster for aerial work platforms which concerns on this invention. The figure which shows the operation mode of the hydraulic circuit of the main pressure stage at the time of this compression operation in the pressure booster for aerial work platforms which concerns on this invention. The figure which shows the operation mode of the hydraulic circuit at the time of the return operation in the pressure booster for aerial work platforms which concerns on this invention. FIG. 5 is a flowchart showing a control mode of releasing the pressure of hydraulic oil in the supply oil passage before caulking in the pressure booster for aerial work platforms according to the present invention. FIG. 5 is a flowchart showing a control mode of releasing the pressure of hydraulic oil in the supply oil passage before caulking work in the pressure booster for aerial work platforms according to the present invention. FIG. 5 is a flowchart showing a control mode of caulking work after pressure release in the pressure booster for aerial work platforms according to the present invention.

Hereinafter, the aerial work platform 1 according to the embodiment of the aerial work platform will be described with reference to FIG.

As shown in FIG. 1, the aerial work platform 1 is an aerial work platform for electrical wiring work in which the sleeve S is crimped using a hydraulic crimping tool 100 (see FIG. 2), which is a hydraulic tool, to connect power lines to each other. Is. The aerial work platform 1 has a vehicle 2 and an aerial work platform 6.

The vehicle 2 conveys the aerial work platform 6. The vehicle 2 is provided with a driver's cab 2b and a plurality of wheels 3 in a frame 2a, and is equipped with an engine 4 (see FIG. 2) as a power source. The vehicle 2 is configured to travel by transmitting the driving force of the engine 4 to the plurality of wheels 3 according to the operation from the driver's cab 2b. The vehicle 2 is provided with an outrigger 5. The outrigger 5 is composed of an overhang beam that can be extended by hydraulic pressure on both sides of the vehicle 2 in the width direction and a hydraulic jack cylinder that can be extended in a direction perpendicular to the ground. The vehicle 2 can expand the workable range of the aerial work platform 1 by extending the outrigger 5 in the width direction of the vehicle 2 and grounding the jack cylinder.

The aerial work platform 6 lifts the bucket 9 on which the worker is boarding to a high place. The aerial work platform 6 includes a swivel base 7, a telescopic boom 8, a bucket 9, an undulating cylinder 10, and an operating device 11.

The swivel base 7 swivels the aerial work platform 6. The swivel base 7 is provided on the frame 2a of the vehicle 2 via an annular bearing. The annular bearing is arranged so that its center of rotation is perpendicular to the installation surface of the vehicle 2. The swivel base 7 is rotatably configured with the center of the annular bearing as the center of rotation. Further, the swivel base 7 is configured to be rotated by a hydraulic swivel motor (not shown).

The telescopic boom 8 supports the bucket 9. The telescopic boom 8 is composed of a plurality of boom members. Each boom member is formed in a hollow cylindrical shape having polygonal cross sections similar to each other. Each boom member is formed in a size that can be inserted into the boom member in the order of the size of the cross-sectional area. The telescopic boom 8 is configured so that each boom member can move in the axial direction. That is, the telescopic boom 8 is configured to be telescopic by moving each boom member with a telescopic cylinder or the like (not shown). The telescopic boom 8 is provided so that the base end of the boom member can swing on the swivel base 7. Further, the telescopic boom 8 is configured to swing around the base end of the boom member with respect to the swivel base 7.

The bucket 9 is for securing a working space for an operator. The bucket 9 is configured so that an operator can get inside. The bucket 9 is supported by the tip of the telescopic boom 8 via a support mechanism 9a. The support mechanism 9a swings the bucket 9 in the elevation and horizontal directions by a hydraulic actuator (not shown).

The undulating cylinder 10 raises and lays down the telescopic boom 8 to maintain the posture of the telescopic boom 8. The undulating cylinder 10 is composed of a hydraulic cylinder. The base of the undulating cylinder 10 is oscillatingly connected to the swivel base 7, and the rod tip is oscillatingly connected to the telescopic boom 8. The undulating cylinder 10 erects or undulates the telescopic boom 8 by expanding and contracting the rod.

The operating device 11 operates the swivel base 7, the telescopic boom 8, the bucket 9, and the like. The operating device 11 is provided inside the vehicle 2 and the bucket 9. The operation device 11 is provided with a swivel expansion / contraction operation tool for swiveling the swivel base 7, an expansion / contraction operation for the telescopic boom 8, an undulation operation tool for performing the undulation operation of the telescopic boom 8, an engine start switch, and the like. Further, the operating device 11 is provided with a hydraulic switching operating tool 11a (see FIG. 3) for switching the hydraulic pressure of the hydraulic oil supplied to the hydraulic crimping tool 100. The hydraulic switching operating tool 11a switches to a state in which increased pressure hydraulic oil can be supplied to the hydraulic crimping tool 100, and discharges hydraulic oil from the hydraulic crimping tool 100.

The aerial work platform 1 configured in this way can move the aerial work platform 6 to an arbitrary position by running the vehicle 2. Further, in the aerial work platform 1, the telescopic boom 8 is erected at an arbitrary undulating angle by the undulating cylinder 10, the telescopic boom 8 is extended to an arbitrary boom length, and the moving range of the bucket 9 of the aerial work platform 6 is extended. Can be expanded.

Hereinafter, the pressure booster 12 included in the aerial work platform 1 will be described with reference to FIGS. 2 and 3.

As shown in FIG. 2, the pressure booster 12 boosts the hydraulic pressure of the hydraulic oil supplied to the hydraulic crimping tool 100. The pressure boosting device 12 includes a pressure boosting cylinder 13, a pressure sensor 14, a preload electromagnetic switching valve (preload switching valve 17) which is a directional control valve, a relief valve 21, and a main pressure electromagnetic switching valve (direction control valve). It includes a main pressure switching valve 24), a pilot check valve 27, a hydraulic pump 28, and a control device 31 (see FIG. 3).

The pressure boosting cylinder 13 boosts the hydraulic pressure of the hydraulic oil. The pressure boosting cylinder 13 is composed of a hydraulic cylinder provided with a bottomed cylindrical pressure boosting chamber 13a provided on the rod side. The pressure boosting cylinder 13 is configured so that the inner diameter of the pressure boosting chamber 13a is smaller than the inner diameter of the hydraulic cylinder. A large-diameter piston 13d to which the rod 13f is connected is slidably inserted inside the hydraulic cylinder. Inside the hydraulic cylinder, a rod-side oil chamber 13b and a head-side oil chamber 13c are configured. A small-diameter piston 13e is slidably inserted inside the pressure boosting chamber 13a. In the pressure boosting cylinder 13, the small diameter piston 13e in the pressure boosting chamber 13a and the large diameter piston 13d in the hydraulic cylinder are connected via a rod 13f. When hydraulic oil is supplied to the oil chamber 13c on the head side of the hydraulic cylinder, the pressure boosting cylinder 13 transmits the force generated in the large diameter piston 13d by the hydraulic pressure of the hydraulic oil to the small diameter piston 13e in the pressure boosting chamber 13a. As a result, the pressure boosting cylinder 13 pressurizes the hydraulic oil in the pressure boosting chamber 13a by the force boosted by the area ratio of the large diameter piston 13d and the small diameter piston 13e.

A pressure sensor 14 is connected to the pressure boosting chamber 13a of the pressure boosting cylinder 13. The pressure sensor 14 can detect the oil pressure of the hydraulic oil in the pressure boosting chamber 13a in real time. The pressure sensor 14 is connected to the control device 31. Further, a supply oil passage 15 is connected to the pressure boosting chamber 13a of the pressure boosting cylinder 13. The supply oil passage 15 is provided with a joint 16 to which the hydraulic crimping tool 100 can be connected. As a result, the pressure boosting device 12 is configured to be able to supply the hydraulic oil boosted in the pressure boosting chamber 13a of the pressure boosting cylinder 13 to the hydraulic crimping tool 100 connected to the joint 16 through the supply oil passage 15. ..

The preload electromagnetic switching valve (hereinafter, simply referred to as “preload switching valve 17”), which is a directional control valve, is a supply in which the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 are connected to each other. It switches the direction of the hydraulic oil supplied to the oil passage 15. A supply oil passage 15 is connected to one port of the preload switching valve 17 via a low pressure oil passage 18. A supply oil passage 15 is connected to the other port of the preload switching valve 17 via a preload oil passage 19. A hydraulic pump 28 is connected to the supply port of the preload switching valve 17 via a discharge oil passage 20. That is, the hydraulic oil is supplied to the preload switching valve 17 at the discharge pressure of the hydraulic pump 28 (hereinafter, simply referred to as “preload”). In the preload switching valve 17, one of one port and the other port is communicated with the supply port by moving a spool (not shown) by an electromagnet.

A relief valve 21 that controls the hydraulic pressure of the hydraulic oil to a set value or less is connected to the low-pressure oil passage 18 connected to one port of the preload switching valve 17. In the relief valve 21, a branch oil passage branched from the low pressure oil passage 18 is connected to the inlet port, and a hydraulic oil tank 30 is connected to the outlet port. Further, the low pressure oil passage 18 is provided with a throttle 22 on the upstream side of the branch oil passage of the relief valve 21, and a check valve 23 on the downstream side. When the oil pressure of the hydraulic oil flowing through the low-pressure oil passage 18 reaches a set value, the relief valve 21 returns a part of the hydraulic oil flowing through the low-pressure oil passage 18 to the hydraulic oil tank 30 through the branch oil passage. That is, the hydraulic pressure of the hydraulic oil flowing through the low pressure oil passage 18 is controlled by the relief valve 21 to a relief pressure lower than the preload (hereinafter, simply referred to as "low pressure"). Further, the flow rate of hydraulic oil flowing through the low-pressure oil passage 18 is limited to the relief flow rate of the relief valve 21 or less by the throttle 22. A check valve 23 is provided in the preload oil passage 19. The preload switching valve 17 is connected to the control device 31.

The preload switching valve 17 is in a state in which the low pressure oil passage 18 and the preload oil passage 19 are connected to the hydraulic oil tank 30 when the electromagnet is not excited (when the operation signal is not received from the control device 31). The spool is moved to position II. That is, the preload switching valve 17 is switched to a state in which the hydraulic oil discharged from the hydraulic pump 28 is not supplied to the supply oil passage 15. As a result, the pressure booster 12 does not supply hydraulic oil to the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 through the oil supply passage 15.

The preload switching valve 17 has a low-pressure oil passage when an electromagnet is excited so that one port and a supply port communicate with each other (when an operation signal for supplying low-pressure hydraulic oil is received from the control device 31). The spool is moved to the I position where 18 is connected to the discharge oil passage 20 and the preload oil passage 19 is connected to the hydraulic oil tank 30. That is, the preload switching valve 17 is switched to a state in which hydraulic oil is supplied to the supply oil passage 15 through the low pressure oil passage 18. As a result, the pressure booster 12 supplies the low pressure hydraulic oil to the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 through the supply oil passage 15. At this time, the flow rate of the hydraulic oil supplied to the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 is limited by the throttle 22 of the low pressure oil passage 18.

The preload switching valve 17 has a preload oil passage when the electromagnet is excited so that the other port and the supply port communicate with each other (when an operation signal for supplying the preload hydraulic oil is received from the control device 31). The spool is moved to position III in which 19 is connected to the discharge oil passage 20 and the low pressure oil passage 18 is connected to the hydraulic oil tank 30. That is, the preload switching valve 17 is switched to a state in which hydraulic oil is supplied to the supply oil passage 15 through the preload oil passage 19. As a result, the pressure booster 12 supplies the hydraulic oil of the preload to the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 through the supply oil passage 15.

The main pressure electromagnetic switching valve (hereinafter, simply referred to as “main pressure switching valve 24”), which is a directional control valve, switches the direction of the hydraulic oil supplied to the pressure boosting cylinder 13. A rod-side oil chamber 13b of the pressure boosting cylinder 13 is connected to one port of the main pressure switching valve 24 via a pressure reducing oil passage 25. The head side oil chamber 13c of the pressure boosting cylinder 13 is connected to the other port of the main pressure switching valve 24 via the pressure boosting oil passage 26. A hydraulic pump 28 is connected to the supply port of the main pressure switching valve 24 via a discharge oil passage 20. That is, hydraulic oil is supplied to the main pressure switching valve 24 with a preload. In the main pressure switching valve 24, one of one port and the other port is communicated with the supply port by moving a spool (not shown) by an electromagnet. The main pressure switching valve 24 is connected to the control device 31.

The main pressure switching valve 24 is in a state where the decompression oil passage 25 and the pressure boosting oil passage 26 are connected to the hydraulic oil tank 30 when the electromagnet is not excited (when the operation signal is not received from the control device 31). The spool is moved to a certain II position. In other words, the switching for the pressure valve 24 is switched to hydraulic oil discharged from the hydraulic pump 28 in a state that does not supply the pressure intensifying cylinder 13. As a result, the pressure boosting device 12 does not boost the hydraulic pressure of the hydraulic oil by the pressure boosting cylinder 13.

The main pressure switching valve 24 has a pressure reducing oil passage when an electromagnet is excited so that one port and a supply port communicate with each other (when an operation signal for reducing the hydraulic pressure of hydraulic oil is received from the control device 31). The spool is moved to the I position where 25 is connected to the discharge oil passage 20 and the pressure boosting oil passage 26 is connected to the hydraulic oil tank 30 (decompression state). That is, the main pressure switching valve 24 is switched to a state in which hydraulic oil is supplied to the rod side oil chamber 13b of the pressure increasing cylinder 13 through the pressure reducing oil passage 25. As a result, the pressure boosting device 12 moves the small diameter piston 13e in the direction in which the volume of the pressure boosting chamber 13a increases to reduce the hydraulic pressure of the hydraulic oil.

The main pressure switching valve 24 is used when the electromagnet is excited so that the other port and the supply port communicate with each other (when an operation signal for increasing the hydraulic pressure of the hydraulic oil is received from the control device 31). The spool is moved to the III position where the passage 26 is connected to the discharge oil passage 20 and the decompression oil passage 25 is connected to the hydraulic oil tank 30 (pressure increasing state). That is, the main pressure switching valve 24 is switched to a state in which hydraulic oil is supplied to the head side oil chamber 13c of the pressure boosting cylinder 13 through the pressure boosting oil passage 26. As a result, the pressure booster 12 moves the small diameter piston 13e in the direction in which the volume of the pressure boosting chamber 13a decreases to increase the hydraulic pressure of the hydraulic oil.

The pilot check valve 27 opens the oil passage. In the pilot type check valve 27, the supply oil passage 15 is connected to the inlet port, and the hydraulic oil tank 30 is connected to the outlet port. Further, the pilot type check valve 27 is configured so that the pilot hydraulic oil is supplied from the pressure reducing oil passage 25. When the main pressure switching valve 24 is switched to a state of supplying hydraulic oil to the rod side oil chamber 13b of the boosting cylinder 13, the pilot type check valve 27 is opened by supplying hydraulic oil for pilot from the decompression oil passage 25. To speak. The hydraulic oil in the pressure boosting chamber 13a connected to the supply oil passage 15 and the hydraulic oil in the hydraulic crimping tool 100 are returned to the hydraulic oil tank 30 through the pilot check valve 27. As a result, the pressure booster 12 is configured to be able to quickly discharge the hydraulic oil in the pressure boosting chamber 13a and the hydraulic oil in the hydraulic crimping tool 100.

The hydraulic pump 28 discharges hydraulic oil at a predetermined discharge pressure. The hydraulic pump 28 is driven by the engine 4. A preload switching valve 17 and a main pressure switching valve 24 are connected in parallel to the hydraulic pump 28. The hydraulic oil discharged from the hydraulic pump 28 is supplied to the preload switching valve 17 and the main pressure switching valve 24 through the discharge oil passage 20, respectively. A relief valve 29 for a hydraulic pump is provided in the discharge oil passage 20. The relief valve 29 for a hydraulic pump controls the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump 28 to a set value or less.

As shown in FIG. 3, the control device 31 controls the operation of the preload switching valve 17 and the main pressure switching valve 24 of the pressure boosting device 12. The control device 31 may actually have a configuration in which a CPU, ROM, RAM, HDD, etc. are connected by a bus, or may have a configuration including a one-chip LSI or the like. The control device 31 stores various programs and data for controlling the operation of the preload switching valve 17 and the main pressure switching valve 24. The control device 31 is provided in the vehicle 2.

The control device 31 is connected to the hydraulic switching operating tool 11a, and can acquire an operation signal from the hydraulic switching operating tool 11a.

The control device 31 is connected to the pressure sensor 14 of the pressure boosting chamber 13a, and can acquire the detected value of the hydraulic pressure of the hydraulic oil in the pressure boosting chamber 13a detected by the pressure sensor 14.

The control device 31 is connected to the preload switching valve 17, and can selectively excite the electromagnet of the preload switching valve 17 to change the position of the spool of the preload switching valve 17.

The control device 31 is connected to the main pressure switching valve 24, and can selectively excite the electromagnet of the main pressure switching valve 24 to change the position of the spool of the main pressure switching valve 24.

The control device 31 is connected to the tool operating tool 100c of the hydraulic crimping tool 100 via the connector 31a, and can acquire an operation signal from the hydraulic crimping tool 100.

The control device 31 is connected to an alarm device 32 provided as an alarm means. When the alarm device 32 detects a failure of the pressure booster 12 or the like, the alarm device 32 notifies the operator by issuing an alarm display or an alarm sound. The alarm device 32 is not limited to being composed of an alarm display or an alarm sound, as long as it can notify the operator of a failure of the pressure boosting device 12 or the like.

In this way, the pressure booster 12 of the aerial work platform 1 is configured as an oil passage in which the low-pressure oil passage 18 whose hydraulic pressure is controlled by the relief valve 21 and the preload oil passage 19 in which the relief valve 21 is not provided are independent of each other. Has been done. That is, the pressure booster 12 can set the oil pressure and the flow rate of the hydraulic oil flowing through the low pressure oil passage 18 and the hydraulic oil flowing through the preload oil passage 19 to different values. As a result, the pressure booster 12 does not provide a directional control valve for the relief valve 21 for hydraulic pressure switching, and only supplies the hydraulic oil controlled to a hydraulic pressure equal to or lower than a predetermined value by the action of the relief valve 21. It can be suppressed. That is, the pressure booster 12 can supply the boosted hydraulic oil to the hydraulic crimping tool 100 without limiting the flow rate.

In the present embodiment, the pressure boosting cylinder 13 of the pressure booster 12 of the aerial work platform 1, the preload switching valve 17, the relief valve 21, the main pressure switching valve 24, the pilot check valve 27, the hydraulic pump 28 and the control The device 31 is provided on the vehicle 2 of the aerial work platform 1. In the pressure booster 12, the hydraulic hoses constituting the supply oil passage 15 are piped to the bucket 9 via the telescopic boom 8. A joint 16 for connecting a hydraulic crimping tool or the like is provided at the tip of the hydraulic hose.

Next, the operation mode of the pressure booster 12 in the caulking work of the sleeve S for electrical wiring by the hydraulic crimping tool 100 will be described with reference to FIGS. 2 and 4 to 8. In the present embodiment, the pressure booster 12 has a hydraulic crimping tool 100 connected to the joint 16 and a tool operating tool 100c of the hydraulic crimping tool 100 connected to the control device 31 via a connector 31a. To do.

As shown in FIG. 4, the hydraulic crimping tool 100 connected to the pressure booster 12 grips and crimps the sleeve S for electrical wiring. The hydraulic crimping tool 100 is configured such that the movable portion 100a moves toward the receiving portion 100b by the hydraulic oil supplied from the pressure boosting device 12. In the hydraulic crimping tool 100, the movable portion 100a is stopped in the stopped state s0 by the operation of the tool operating tool 100c, the movable portion 100a is moved toward the receiving portion 100b, and the sleeve S is moved to the movable portion 100a and the receiving portion 100b. The temporary holding operation s1 to be gripped by the above, the preloading step s2 of the main compression operation in which the movable portion 100a is pressed by a predetermined force to preload the sleeve S, and the movable portion 100a is pressed by a predetermined force to press the sleeve S. The main pressure step s3 of the main compression operation of caulking and the return operation s4 in which the movable portion 100a is moved away from the receiving portion 100b to release the sleeve S can be performed.

As shown in FIG. 2, when the operation mode of the hydraulic crimping tool 100 is switched to the stopped state by the operation of the tool operating tool 100c, the control device 31 sets the spool position of the preload switching valve 17 to the low pressure oil passage 18 And the preload oil passage 19 are moved to the II position where the hydraulic oil tank 30 is connected. At the same time, the control device 31 moves the spool position of the main pressure switching valve 24 to the position II in which the pressure reducing oil passage 25 and the pressure increasing oil passage 26 are connected to the hydraulic oil tank 30. That is, the pressure booster 12 does not supply hydraulic oil to the hydraulic crimping tool 100. As a result, the hydraulic crimping tool 100 stops in a state where the movable portion 100a is separated from the receiving portion 100b (a state in which the sleeve S is released).

As shown in FIG. 5, when the operation mode of the hydraulic crimping tool 100 is switched to the temporary holding operation s1 by the operation of the tool operating tool 100c, the control device 31 sets the spool position of the preload switching valve 17 to low pressure oil. The passage 18 is connected to the discharge oil passage 20, and the preload oil passage 19 is moved to the I position where it is connected to the hydraulic oil tank 30. At the same time, the control device 31 moves the spool position of the main pressure switching valve 24 to the position II in which the pressure reducing oil passage 25 and the pressure increasing oil passage 26 are connected to the hydraulic oil tank 30. That is, in the pressure boosting device 12, the hydraulic oil is controlled to a low pressure by the relief valve 21 and the flow rate is controlled to be equal to or lower than the relief flow rate by the throttle 22. (See the light ink part). As a result, in the hydraulic crimping tool 100, the movable portion 100a is moved toward the receiving portion 100b, and the sleeve S is gripped by the movable portion 100a and the receiving portion 100b (see the black arrow). At the same time, the pressure booster 12 discharges air in the pressure boosting chamber 13a, the hydraulic crimping tool 100, and the supply oil passage 15 by supplying low-pressure hydraulic oil.

As shown in FIG. 6, when the operation mode of the hydraulic crimping tool 100 is switched to the present compression operation by the operation of the tool operating tool 100c, the control device 31 sets the spool position of the preload switching valve 17 to the preload oil passage. 19 is connected to the discharge oil passage 20, and the low pressure oil passage 18 is moved to the position III in which it is connected to the hydraulic oil tank 30. At the same time, the control device 31 moves the spool position of the main pressure switching valve 24 to the position II in which the pressure reducing oil passage 25 and the pressure increasing oil passage 26 are connected to the hydraulic oil tank 30. That is, the pressure booster 12 supplies the hydraulic oil of the preload, which is the discharge pressure of the hydraulic pump 28, to the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 (see the light ink portion). As a result, in the hydraulic crimping tool 100, as the preload step s2 of the main compression operation, the movable portion 100a is pressed by a predetermined force by the hydraulic oil of the preload that is not boosted, and the preload is applied to the sleeve S (black arrow). reference). At the same time, the pressure booster 12 discharges the air in the pressure boosting chamber 13a, the hydraulic crimping tool 100, and the supply oil passage 15 by supplying the hydraulic oil of the preload.

As shown in FIG. 7, when the detected value of the pressure sensor 14 reaches the preload reference value in the preload step s2 of this compression operation, the control device 31 sets the spool position of the preload switching valve 17 to the low pressure oil passage 18. The preload oil passage 19 is moved to the II position where it is connected to the hydraulic oil tank 30. At the same time, the control device 31 sets the spool position of the main pressure switching valve 24 to the position III in which the boosting oil passage 26 is connected to the discharge oil passage 20 and the pressure reducing oil passage 25 is connected to the hydraulic oil tank 30. Move. That is, the pressure boosting device 12 reduces the volume of the pressure boosting chamber 13a of the pressure boosting cylinder 13 to increase the hydraulic pressure of the hydraulic oil in the pressure boosting chamber 13a and supplies it to the hydraulic crimping tool 100 (see the light ink portion). .. As a result, in the hydraulic crimping tool 100, as the main pressure step s3 of the main compression operation, the movable portion 100a is pressed by the hydraulic oil boosted by the pressure boosting cylinder 13 with a predetermined force to crimp the sleeve S (black). See painted arrow).

As shown in FIG. 8, when the operation mode of the hydraulic crimping tool 100 is switched to the return operation s4 by the operation of the tool operating tool 100c, or when the detected value of the pressure sensor 14 reaches the main pressure reference value. The control device 31 moves the spool position of the preload switching valve 17 to the position II in which the low pressure oil passage 18 and the preload oil passage 19 are connected to the hydraulic oil tank 30. At the same time, the control device 31 sets the spool position of the main pressure switching valve 24 to the I position where the pressure reducing oil passage 25 is connected to the discharge oil passage 20 and the pressure increasing oil passage 26 is connected to the hydraulic oil tank 30. Move. That is, the pressure boosting device 12 increases the volume of the pressure boosting chamber 13a of the pressure boosting cylinder 13 to reduce the oil pressure of the hydraulic oil in the pressure boosting chamber 13a, and opens the pilot check valve 27 to increase the pressure chamber. The hydraulic oil in 13a and the hydraulic oil in the hydraulic crimping tool 100 are discharged to the hydraulic oil tank 30 (see the light ink portion). As a result, in the hydraulic crimping tool 100, the movable portion 100a is moved in the direction away from the receiving portion 100b, and the sleeve S is released from the movable portion 100a and the receiving portion 100b (see the black arrow).

When the operation mode of the hydraulic crimping tool 100 is switched to the return operation s4, or when the detected value of the pressure sensor 14 reaches the main pressure reference value, the preload switching valve 17 of the preload switching valve 17 is used for a preset time. By switching the spool position to the II position, switching the spool position of the main pressure switching valve 24 to the I position, and opening the pilot check valve 27, the hydraulic oil in the pressure boosting chamber 13a and the operation in the hydraulic crimping tool 100 are operated. It is configured to discharge the oil to the hydraulic oil tank 30.

Further, when the hydraulic switching operation tool 11a of the aerial work platform 1 is operated, the control device 31 sets the spool position of the preload switching valve 17 to the low pressure oil passage 18 and the preload oil regardless of the detected value of the pressure sensor 14. The road 19 is moved to the II position where it is connected to the hydraulic oil tank 30. At the same time, the control device 31 sets the spool position of the main pressure switching valve 24 to the I position where the pressure reducing oil passage 25 is connected to the discharge oil passage 20 and the pressure increasing oil passage 26 is connected to the hydraulic oil tank 30. Move. That is, the pressure boosting device 12 increases the volume of the pressure boosting chamber 13a to reduce the oil pressure of the hydraulic oil in the pressure boosting chamber 13a, and opens the pilot check valve 27 to open the hydraulic oil in the pressure boosting chamber 13a. And the hydraulic oil in the hydraulic crimping tool 100 are discharged to the hydraulic oil tank 30. As a result, in the hydraulic crimping tool 100, the movable portion 100a is moved in the direction away from the receiving portion 100b, and the sleeve S is released from the movable portion 100a and the receiving portion 100b.

With this configuration, when the pressure booster 12 controls the hydraulic pressure of the hydraulic oil at the time of the temporary holding operation s1 by the relief valve 21, the low pressure oil passage 18 is operated without providing the directional control valve for the relief valve 21. The hydraulic oil is supplied with only the oil flow rate limited to the relief flow rate or less. That is, the pressure boosting device 12 does not limit the flow rate of the hydraulic oil supplied to the pressure boosting cylinder 13 through the pressure boosting oil passage 26 during this compression operation. Therefore, in the hydraulic crimping tool 100, the speed at the time of this compression operation is not affected by the relief flow rate of the relief valve 21. Further, the pressure booster 12 switches between the preload switching valve 17 and the main pressure switching valve 24 based on at least one signal of the operation signal from the hydraulic crimping tool 100 and the detected value of the pressure sensor 14. .. That is, the pressure booster 12 can selectively supply the hydraulic oil of low pressure or preload to the supply oil passage 15 at different flow rates. As a result, the pressure booster 12 can supply the hydraulic oil to the hydraulic tool without limiting the flow rate of the hydraulic oil at the time of pressure boosting without providing a directional control valve for the relief valve.

With reference to FIGS. 9 and 10, the release of the check and pressure of the pressure of hydraulic fluid supplied to the hydraulic crimping tool 100 crimping before the oil supply passage 15 by (increasing chamber 13a and the hydraulic crimping tool 100) Will be described.

The control device 31 is configured to be able to determine whether or not the value detected by the pressure sensor 14 before the caulking operation by the hydraulic crimping tool 100 is larger than the reference pressure. When it is determined that the detected value of the pressure sensor 14 is larger than the reference pressure, the operation mode of the hydraulic crimping tool 100 is switched to the return operation s4.

The control device 31 determines the time or the number of return operations s4 based on the detected value of the pressure sensor 14. The control device 31 is configured to be able to determine whether or not the detected value of the pressure sensor 14 is larger than the reference pressure after the return operation s4 is performed for the time or the number of times. When it is determined that the detected value of the pressure sensor 14 is larger than the reference pressure, it is detected as a failure of the pressure increasing device 12 such as the hydraulic pump 28 and the pressure sensor 14, and the operator is notified.

The first embodiment of the pressure increasing device 12 in confirming the pressure of the hydraulic oil supplied to the supply oil passage 15 and releasing the pressure before the caulking operation will be described with reference to FIG.

In step S110, the control device 31 determines whether or not the pressure booster 12 is in the state before the caulking operation. Specifically, the hydraulic pressure switching operation tool 11a determines whether or not the pressure booster 12 is activated. When the hydraulic switching operating tool 11a is switched to a state in which the hydraulic oil boosted pressure can be supplied to the hydraulic crimping tool 100, the pressure boosting device 12 is determined to be at the start, and the process proceeds to step S120.

In step S120, the control device 31 determines whether or not the spool position of the preload switching valve 17 is fixed at the II position and the spool position of the main pressure switching valve 24 is fixed at the II position. Here, the fact that the spool position is fixed to the II position means a state in which the spool position cannot be moved to a position other than the II position. The state in which the spool position is fixed to the II position is a state in which a failure of the pressure booster 12 described later is detected. Therefore, even before the caulking operation, the pressure of the hydraulic oil supplied to the supply oil passage 15 is not confirmed and the pressure is not released. When it is determined that the spool position of the preload switching valve 17 is fixed at the II position and the spool position of the main pressure switching valve 24 is fixed at the II position, the process ends. If the spool position of the preload switching valve 17 is not fixed to the II position and the spool position of the main pressure switching valve 24 is not fixed to the II position, the process proceeds to step S130.

In step S130, the control device 31 determines whether or not the detected value of the pressure sensor 14 at the time of starting the pressure boosting device 12 is larger than the reference pressure. If it is determined in step S130 that the detected value of the pressure sensor 14 is larger than the reference pressure, the process proceeds to step S140. In step S 130, if the detected value of the pressure sensor 14 is not greater than the reference pressure, ends.

In step S140, the control device 31 determines the time of the return operation s4 based on the detected value of the pressure sensor 14. That is, the time of the return operation s4 is determined so that the detected value of the pressure sensor 14 becomes the reference pressure. When the time of the return operation s4 is determined, the process proceeds to step S150.

In step S150, the control device 31 switches the operation mode of the hydraulic crimping tool 100 to the return operation s4, and shifts to step S160. The spool position of the pressure switching valve 24 is moved in I position, pilot-check valve 27 is opened, and discharge the working oil supply passage 15 to the hydraulic oil tank 30.

In step S160, the control device 31 determines whether or not the time (predetermined time) set in step S140 has elapsed after switching the operation mode of the hydraulic crimping tool 100 to the return operation s4. After a lapse of a predetermined time, the process proceeds to step S170.

In step S170, the control device 31 again determines whether or not the detected value of the pressure sensor 14 is larger than the reference pressure. If it is determined in step S170 that the detected value of the pressure sensor 14 is larger than the reference pressure, the process proceeds to step S180. If it is determined in step S170 that the detected value of the pressure sensor 14 is not larger than the reference pressure, the pressure of the hydraulic oil in the supply oil passage 15 is released, and the process ends.

In step S180, the control device 31 detects the failure of the pressure boosting device 12, and notifies the operator of the failure by the alarm device 32 to shift to step S190.

In step S190, the control device 31 ends when the spool position of the preload switching valve 17 is fixed at the II position and the spool position of the main pressure switching valve 24 is fixed at the II position.

As described above, by checking the pressure of the hydraulic oil supplied to the supply oil passage 15 before the caulking operation and performing the return operation s4 only when there is pressure, it is possible to eliminate the unnecessary return operation s4. it can. Further, when there is pressure, the movable portion 100a of the hydraulic crimping tool 100 is settled in a predetermined position by performing the return operation s4, and the movable portion 100a does not interfere with gripping the sleeve S and is smoothly crimped. You can work.

Further, even though the pressure is released for a predetermined time so that the detected value of the pressure sensor 14 becomes the reference value, it is determined in step S170 that the detected value of the pressure sensor 14 is larger than the reference pressure. ing. That is, a situation in which pressure remains in the pressure boosting chamber 13a of the pressure boosting cylinder 13 and the hydraulic crimping tool 100 side due to a failure of the pressure boosting device 12 such as the hydraulic pump 28, the preload switching valve 17, and the main pressure switching valve 24. It is conceivable that there is pressure in the pressure boosting chamber of the pressure boosting cylinder 13 and the pressure on the side of the hydraulic crimping tool 100 due to the failure of the pressure sensor 14. Therefore, the operator is notified as a failure of the pressure booster 12. As described above, by making it possible to detect the failure of the pressure booster 12 before performing the caulking operation, it is possible to prevent the sleeve S from being caulked by an inappropriate force.

In the above embodiment, the return operation is performed so that the detected value of the pressure sensor 14 becomes the reference pressure, but the present invention is not limited to this. For example, the detection value of the pressure sensor 14 may be configured to perform the returning operation such that the pressure value of a degree that does not interfere to grip the sleeve S (slightly larger pressure value than the reference pressure).

Further, in step S110, it is determined whether or not it is before the caulking operation by determining whether or not the pressure boosting device 12 is activated, but the present invention is not limited to this. For example, after crimping the sleeve S using the hydraulic crimping tool 100, that is, when the operation mode of the hydraulic crimping tool 100 is switched from the return operation s4 to the stopped state (standby before crimping the next sleeve S). It may be determined whether or not it is in the state) and whether or not it is before the caulking operation.

Further, in step S140, the control device 31 sets the time of the return operation s4 according to the detected value of the pressure sensor 14 so that the detected value of the pressure sensor 14 becomes the reference pressure, but the present invention is not limited to this.

In step S190, in the control device 31, the spool position of the preload switching valve 17 is fixed to the II position, and the spool position of the main pressure switching valve 24 is fixed to the II position, so that the operator can perform the pressure boosting device 12. Even if the alarm device 32 does not recognize the failure, the failure of the control device 31 can be recognized because the crimping operation of the hydraulic crimping tool 100 cannot be performed.

A second embodiment of the pressure booster 12 in confirming the pressure of the hydraulic oil supplied to the supply oil passage 15 and releasing the pressure before the caulking operation will be described with reference to FIG. In the second embodiment of FIG. 10, the time of the return operation s4 is set in advance regardless of the value detected by the pressure sensor 14. In the second embodiment of FIG. 10, since steps S110 to S130 of FIG. 9 are the same steps, the description starts from step S130.

In step S130, the control device 31 determines whether or not the detected value of the pressure sensor 14 at the time of starting the pressure boosting device 12 is larger than the reference pressure. If it is determined in step S130 that the detected value of the pressure sensor 14 is larger than the reference pressure, the process proceeds to step S240. In step S 130, if the detected value of the pressure sensor 14 is not greater than the reference pressure, ends.

In step S240, the control device 31 determines the number of return operations s4 based on the detected value of the pressure sensor 14. The time of the return operation s4 is set in advance regardless of the detection value of the pressure sensor 14, and the number of return operations s4 is determined so that the detection value of the pressure sensor 14 becomes the reference pressure. When the number of return operations s4 is determined, the process proceeds to step S250.

In step S250, the control device 31 switches the operation mode of the hydraulic crimping tool 100 to the return operation s4, and shifts to step S260. By moving the spool position of the main pressure switching valve 24 to the I position, the pilot type check valve 27 is opened and the hydraulic oil in the supply oil passage 15 is discharged to the hydraulic oil tank 30.

In step S260, the control device 31 determines whether or not the operation mode of the hydraulic crimping tool 100 has been switched to the return operation s4 by the number of times (predetermined number of times) set in step S240. After a lapse of a predetermined number of times, the process proceeds to step S270.

In step S270, the control device 31 again determines whether or not the detected value of the pressure sensor 14 is larger than the reference pressure. If it is determined in step S270 that the detected value of the pressure sensor 14 is larger than the reference pressure, the process proceeds to step S280. If it is determined in step S270 that the detected value of the pressure sensor 14 is not larger than the reference pressure, the pressure of the hydraulic oil in the supply oil passage 15 is released, and the process ends.

In step S280, the control device 31 detects as a failure of the pressure boosting device 12, notifies the operator of the failure by the alarm device 32, and shifts to step S290.

In step S290, the control device 31 ends when the spool position of the preload switching valve 17 is fixed at the II position and the spool position of the main pressure switching valve 24 is fixed at the II position.

As described above, it is sufficient that the return operation (release the pressure) can be performed according to the detected value of the pressure sensor 14 so that the detected value of the pressure sensor 14 becomes the reference pressure, and the return operation s4 sets the time in advance. Alternatively, the time may be set according to the detected value of the pressure sensor 14. Further, in the above, in order to improve the detection accuracy of the failure of the pressure booster 12, the time or the number of return operations s4 is determined so that the detected value of the pressure sensor 14 becomes the reference pressure, but the present invention is not limited to this. .. For example, regardless of the detection value of the pressure sensor 14, the time of the return operation s4 may be set in advance, or the number of times of the return operation s4 may be set in advance.

Further, in step S130, the control device 31 is configured to end when it is determined that the detected value of the pressure sensor 14 is not larger than the reference pressure, but the control device 31 is not limited to this. For example, in step S130, when the control device 31 determines that the detected value of the pressure sensor 14 is not larger than the reference pressure, the control device 31 may perform the return operation s4 in a time shorter than a preset time.

An operation mode of the caulking operation performed after the pressure is released will be described with reference to FIG. In FIG. 11, there is a pressure of the hydraulic oil in the supply oil passage 15 before the caulking operation, and the description starts from the time when the pressure is released (step S170 in FIG. 9). Further, steps S180 and S190 are omitted because they are described in FIG.

When the control device 31 determines that the detected value of the pressure sensor 14 at the time of starting the pressure boosting device 12 is larger than the reference pressure, the control device 31 performs the return operation s4 during the caulking operation based on the detected value of the pressure sensor 14. It is configured to increase the time.

In step S170, the control device 31 again determines whether or not the detected value of the pressure sensor 14 is larger than the reference pressure. If it is determined in step S170 that the detected value of the pressure sensor 14 is larger than the reference pressure, the process proceeds to step S180. If it is determined in step S170 that the detected value of the pressure sensor 14 is not larger than the reference pressure, the pressure of the hydraulic oil in the supply oil passage 15 is released, and the process proceeds to step S310.

In step S310, the control device 31 determines whether or not the operation mode of the hydraulic crimping tool 100 has been switched to the temporary holding operation s1. When the operation mode of the hydraulic crimping tool 100 is switched to the temporary holding operation s1, the process proceeds to step S320.

In step S320, the control device 31 moves the spool position of the preload switching valve 17 to the I position, moves the spool position of the main pressure switching valve 24 to the II position, and shifts to step S330.

In step S330, the control device 31 determines whether or not the operation mode of the hydraulic crimping tool 100 has been switched to the main compression operation. When the operation mode of the hydraulic crimping tool 100 is switched to the present compression operation, the process proceeds to step S340.

In step S340, the control device 31 moves the spool position of the preload switching valve 17 to the III position, moves the spool position of the main pressure switching valve 24 to the II position, and shifts to step S350.

In step S350, the control device 31 determines whether or not the detected value of the pressure sensor 14 is the preload reference value. When the detected value of the pressure sensor 14 is the preload reference value, the process proceeds to step S360.

In step S360, the control device 31 moves the spool position of the preload switching valve 17 to the II position, moves the spool position of the main pressure switching valve 24 to the III position, and shifts to step S370.

In step S370, the control device 31 determines whether or not the detected value of the pressure sensor 14 is the main pressure reference value. When the detected value of the pressure sensor 14 is the main pressure reference value, the process proceeds to step S380.

In step S380, the control device 31 moves the spool position of the preload switching valve 17 to the II position, moves the spool position of the main pressure switching valve 24 to the I position, and ends when a predetermined time elapses. That is, the operation mode of the hydraulic crimping tool 100 is switched to the return operation s4, and the operation ends when a predetermined time elapses. The predetermined time at this time is set longer than the preset time. Specifically, it is the time obtained by adding the time determined based on the detection value of the pressure sensor 14 in step S130 (see FIG. 9) to the preset time.

When it is determined in step S130 that the detected value of the pressure sensor 14 is larger than the reference pressure, the previous caulking operation (if the pressure booster 12 is activated, the caulking performed at the previous activation of the pressure booster 12). When the operation mode of the hydraulic crimping tool 100 in (work) was the return operation s4, the time for opening the pilot check valve 27 was short, so that the hydraulic oil in the supply oil passage 15 could not be completely discharged to the hydraulic oil tank 30. It is possible that the situation is not. Therefore, the control device 31 is configured to lengthen the time of the return operation s4 in the caulking operation (the time for opening the pilot check valve 27), so that the control device 31 is supplied at the end of the caulking operation by the hydraulic crimping tool 100. The hydraulic oil can be discharged without remaining in the oil passage 15. Therefore, smooth work can be realized when caulking work is continuously performed.

Although the operation mode of the caulking operation shown in FIG. 11 has been described using the first embodiment shown in FIG. 9, it can be similarly applied to the second embodiment shown in FIG.

1 Aerial work platform 13 Pressure boosting cylinder 14 Pressure sensor 13a Pressure boosting chamber 15 Supply oil passage 17 Preload switching valve 18 Low pressure oil passage 19 Preload circuit 21 Relief valve 25 Decompression oil passage 26 Pressure boosting oil passage 31 Control device 32 Alarm device

Claims (4)

A pressure booster for aerial work platforms that supplies hydraulic oil boosted by a pressure boost cylinder to hydraulic tools.
A supply oil passage connecting the pressure boosting chamber of the pressure boosting cylinder and the hydraulic tool, and
An electromagnetic switching valve for preload that supplies hydraulic oil to the supply oil passage,
A pressure-increasing state in which hydraulic oil is supplied to the head-side oil chamber of the pressure-increasing cylinder and a depressurized state in which hydraulic oil is supplied to the rod-side oil chamber of the pressure-increasing cylinder and the hydraulic oil in the supply oil passage is discharged. An electromagnetic switching valve for main pressure that can be selectively switched,
A pressure detecting means for detecting the pressure in the pressure boosting chamber and
A control device that controls the operation of the electromagnetic switching valve for preload and the electromagnetic switching valve for main pressure based on the detection value of the pressure detecting means.
Equipped with
When the detection value of the pressure detecting means exceeds the reference pressure before the work with the hydraulic tool is performed, the control device depressurizes the electromagnetic switching valve for the main pressure so that the detected value becomes the reference pressure. A pressure booster for aerial work platforms that switches to. The control device is
The pressure booster for an aerial work platform according to claim 1, wherein a failure is detected based on a value detected by the pressure detecting means after the solenoid valve for main pressure is depressurized. Further equipped with an alarm means connected to the control device,
The control device is
The pressure boosting device for aerial work platforms according to claim 2, wherein when the failure is detected, an alarm is issued by using the alarm means. The control device is
From claim 1, when the detection value of the pressure detecting means before the work with the hydraulic tool exceeds the reference value, the time of the decompression state during the work of the hydraulic tool is lengthened. The pressure booster for aerial work platforms according to any one of 3.

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