JP6072452B2 - Booster for aerial work vehicle - Google Patents

Description

  The present invention relates to a pressure booster for an aerial work vehicle. More particularly, the present invention relates to a pressure intensifying device that supplies high-pressure oil to a hydraulic tool in an aerial work vehicle in which a hydraulic outlet for connecting the hydraulic tool is provided in a bucket.

  For example, an aerial work vehicle for power distribution work is provided with a hydraulic outlet in the bucket, and a hydraulic crimping tool for crimping a sleeve for electrical wiring can be connected to the hydraulic outlet. Since a hydraulic tool such as a hydraulic crimping tool requires high-pressure oil, such an aerial work vehicle is provided with a pressure increasing device that supplies high-pressure oil necessary for the hydraulic tool (for example, Patent Document 1). ).

  As shown in FIG. 7, a conventional pressure booster 100 includes a drive cylinder 101, a pressure boost cylinder 102, a hydraulic pump 103, a tank 104, two directional control valves 105, 106, a low pressure relief valve 107, It has. The drive cylinder 101 has a forward drive side oil chamber 101a and a reverse drive side oil chamber 101b. The rod of the drive cylinder 101 and the rod of the pressure increasing cylinder 102 are connected to each other, and the pressure increasing cylinder 102 has a pressure increasing oil chamber 102c whose volume decreases by the forward movement of the rod and increases by the backward movement. . Further, the pressure-increasing cylinder 102 has a check valve 102e that normally allows only the inflow of hydraulic oil from the oil chamber 102d to the pressure-increasing oil chamber 102c and allows backflow only at the end of the backward movement. The forward drive side oil chamber 101a and the reverse drive side oil chamber 101b of the drive cylinder 101 are connected to the hydraulic pump 103 and the tank 104 via the direction control valve 105. It is configured to be able to switch back and forth. A low pressure relief valve 107 is interposed in the return oil path 111 that connects the direction control valve 105 and the tank 104. The oil chamber 102d of the pressure increasing cylinder 102 is selectively connected to the return oil path 111 or the tank 104 in the preceding stage of the low pressure relief valve 107 via the direction control valve 106. The crimping tool T can be connected to the take-out oil passage 112 connected to the pressure-increasing oil chamber 102c of the pressure-increasing cylinder 102.

When the directional control valve 106 is switched to the II position and the oil chamber 102d of the pressure-increasing cylinder 102 is connected to the return oil passage 111 upstream of the low pressure relief valve 107, the hydraulic oil whose hydraulic pressure is controlled by the low pressure relief valve 107 is reversed. The pressure-increasing oil chamber 102c flows into the pressure-increasing oil chamber 102c through the stop valve 102e, and the pressure-bonding tool T can be preloaded by this hydraulic pressure. By this preload, the crimping tool T is driven at a low pressure until the crimping portion contacts the sleeve, and the sleeve is gripped at a low pressure (temporary gripping operation).
When the directional control valve 105 is switched to the I position and the pressure increasing cylinder 101 is driven forward, the volume of the pressure increasing oil chamber 102c decreases, and the cross sectional area of the forward driving side oil chamber 101a with respect to the cross sectional area of the pressure increasing oil chamber 102c is reduced. The high pressure oil whose pressure has been increased by the area ratio is supplied to the crimping tool T. The crimping tool T is crimped and driven by this high pressure oil (main compression operation).
When the direction control valve 105 is switched to the III position and the pressure increasing cylinder 101 is double-actuated, the volume of the pressure increasing oil chamber 102c increases, and the hydraulic oil supplied to the crimping tool T returns to the pressure increasing oil chamber 102c. Thereby, the crimping part of the crimping tool T is opened (returning operation).

When the conventional pressure booster 100 is provided in an aerial work vehicle, in general, since the hydraulic pump 103 is driven by an engine or the like mounted on the vehicle, most of the pressure booster 100 is provided on the vehicle side. Only the hydraulic hose constituting 112 is guided through the boom to the bucket. Further, a quick joint is provided at the tip of the hydraulic hose constituting the take-out oil passage 112 so that it can be connected to various hydraulic tools T.
In such an aerial work vehicle, a worker on the bucket may attach and change the hydraulic tool T at a high place. In this case, the tip of the hydraulic hose constituting the take-out oil passage 112 has a negative pressure because it is high, and when the hydraulic tool T is connected to the quick joint at the tip of the hydraulic hose, air is taken into the take-out oil passage 112. May be inhaled.

In a state where air is in the take-out oil passage 112, even if high-pressure oil is supplied from the pressure-increasing cylinder 101, the air is only compressed, and the necessary hydraulic pressure may not be supplied to the hydraulic tool T.
If the hydraulic oil is caused to flow into the pressure-increasing oil chamber 102c by the temporary gripping operation, the air that has entered the extraction oil passage 112 is compressed in advance, so that the hydraulic pressure necessary for the next main compression operation can be supplied to the hydraulic tool T. The above problems do not occur. However, depending on the worker, there is a case where the main compression operation is performed without going through the temporary gripping operation. In this case, there is a problem that the hydraulic tool T does not exert a normal force and the worker feels uncomfortable.

JP 10-54403 A

  In view of the above circumstances, an object of the present invention is to provide a pressure increase device for an aerial work vehicle that does not cause poor supply of high-pressure oil and does not cause an operator to feel uncomfortable in operation.

A booster for an aerial work vehicle according to a first aspect of the invention is a booster that supplies high-pressure oil to a hydraulic tool, and includes a hydraulic source, a forward drive side oil chamber, a reverse drive side oil chamber, a pressure intensifying cylinder having an increasing pressure oil chamber volume by the backward movement the volume is reduced by the forward movement of the rod increases, is connected to the boosted pressure oil chamber, and the extraction fluid channel that can be connected to the hydraulic tool, the A first directional control valve for selectively switching a supply destination of hydraulic oil from a hydraulic source between the take-out oil passage and the forward drive side oil chamber; and a supply destination of hydraulic oil from the hydraulic source. A second directional control valve that selectively switches between the first directional control valve and the backward drive side oil chamber, and oil that connects the first directional control valve and the second directional control valve A return oil passage branched from the passage and connected to the tank, a low-pressure relief valve provided in the return oil passage, and a first oil passage for opening and closing the return oil passage. The first directional control valve connects the hydraulic pressure source and the extraction oil passage when the oil pressure of the extraction oil passage is in a low pressure state, and the oil pressure of the extraction oil passage is high. In the state, the hydraulic pressure source and the forward drive side oil chamber are connected, and the low pressure relief valve operates at a pressure lower than the hydraulic pressure at which the first directional control valve is switched .
The pressure increasing device for an aerial work vehicle according to a second aspect of the present invention switches the second direction control valve and the third control valve based on a signal input from the operating means of the hydraulic tool in the first aspect. A control means, wherein the hydraulic tool has at least a state of supplying low-pressure oil and a state of supplying high-pressure oil, and the control means is switched to a state of supplying low-pressure oil by the operation means The second directional control valve is brought into a state where the hydraulic pressure source and the first directional control valve are connected, and the third control valve is brought into a state where the return oil passage is opened. When switched to a state of supplying high-pressure oil, the second directional control valve is brought into a state of connecting the hydraulic power source and the first directional control valve, and the third control valve is returned to the return. characterized in that a state of closing an oil passage To.

According to the present invention, since the high-pressure oil is supplied to the take-out oil passage after the hydraulic oil from the hydraulic source is directly supplied to the take-out oil passage, the oil pressure source can be supplied even if air enters the take-out oil passage. Since the air is pre-compressed by the hydraulic oil from the high pressure oil, poor supply of high pressure oil does not occur, and the operator does not feel uncomfortable in operation .

1 is a hydraulic circuit of a pressure booster according to a first embodiment of the present invention. It is a hydraulic circuit in the temporary holding | grip operation | movement of the same pressure increasing device. It is a hydraulic circuit in the first half of the main compression operation of the pressure booster. It is a hydraulic circuit in the second half of the main compression operation of the pressure booster. It is a hydraulic circuit in return operation | movement of the same pressure booster. It is a hydraulic circuit of the pressure booster which concerns on 2nd Embodiment of this invention. It is a hydraulic circuit of the conventional pressure booster.

Next, an embodiment of the present invention will be described with reference to the drawings.
The pressure booster according to the present invention is a device that is provided in, for example, an aerial work vehicle for power distribution work and supplies high-pressure oil to a connected hydraulic tool. Examples of the hydraulic tool include, but are not limited to, a crimping tool for crimping a sleeve for electrical wiring and a cutter for cutting an electric wire. Hereinafter, a crimping tool will be described as an example of the hydraulic tool.

(First embodiment)
As shown in FIG. 1, a pressure increasing device 1 according to the first embodiment of the present invention includes a hydraulic pump 11, a pressure increasing cylinder 12, a take-out oil passage 13 that can be connected to a hydraulic tool T, and three direction controls. Valves 21, 22, and 23 are provided.

The hydraulic pump 11 is driven by a driving engine such as a traveling engine for an aerial work vehicle, a working engine provided separately from the traveling engine, and a motor, and sucks hydraulic oil stored in the tank 30. The hydraulic oil is discharged to the pump oil passage 31. The pump oil passage 31 is bifurcated, and one of the tributaries is connected to the tank 30 via a relief valve 24. The relief valve 24 controls the hydraulic pressure in the pump oil passage 31.
The hydraulic pump 11 corresponds to the hydraulic power source described in the claims.

  The pressure-increasing cylinder 12 is a known pressure-increasing cylinder, and a rod in which a large-diameter rod and a small-diameter rod are connected is provided inside a cylinder in which a large-diameter cylinder and a small-diameter cylinder are connected so as to be able to reciprocate. Yes. In this specification, the oil chamber on the cap side of the large diameter cylinder is referred to as the forward drive side oil chamber 12a, the oil chamber on the head side of the large diameter cylinder is referred to as the backward drive side oil chamber 12b, and the oil in the small diameter cylinder The chamber is referred to as a pressurized oil chamber 12c. When the operating pressure is supplied to the forward drive side oil chamber 12a, the pressure increasing cylinder 12 moves forward, the volume of the pressure increasing oil chamber 12c decreases, and the forward drive side oil with respect to the cross-sectional area of the pressure increasing oil chamber 12c. The high pressure oil whose pressure has been increased by the area ratio of the cross-sectional area of the chamber 12a is discharged from the pressure increasing oil chamber 12c. Further, when the hydraulic oil is supplied to the backward drive side oil chamber 12b, the rod moves backward to increase the volume of the pressurized oil chamber 12c, and the hydraulic oil returns to the pressurized oil chamber 12c. A take-out oil passage 13 is connected to the pressure-increasing oil chamber 12c through an oil passage 37.

  The directional control valve 21 is a four-port, three-position electromagnetic switching valve. The P port is connected to the other branch of the pump oil passage 31, and the T port is connected to the tank 30 via the return oil passage 32. . Of the control ports of the directional control valve 21, the A port is connected to the P port of the directional control valve 22 through the oil passage 33, and the B port is connected to the return drive side of the pressure increasing cylinder 12 through the oil passage 34. It is connected to the oil chamber 12b.

When the direction control valve 21 is switched to the I position, the P port and the A port are connected, the hydraulic oil from the hydraulic pump 11 is supplied to the P port of the direction control valve 22, and the T port and the B port are connected. The backward drive side oil chamber 12 b of the pressure increasing cylinder 12 is connected to the tank 30 via the oil passage 34 and the return oil passage 32. When the directional control valve 21 is switched to the II position (neutral position), the P port is closed and the T port, the A port, and the B port are connected. When the direction control valve 21 is switched to the III position, the P port and the B port are connected, and the hydraulic oil from the hydraulic pump 11 is supplied to the backward drive side oil chamber 12b of the pressure increasing cylinder 12 through the oil passage 34. At the same time, the T port and the A port are connected. Thus, the direction control valve 21 can selectively switch the supply destination of the hydraulic oil from the hydraulic pump 11 between the direction control valve 22 and the backward drive side oil chamber 12b.
The direction control valve 21 corresponds to a second direction control valve described in the claims.

  The directional control valve 22 is a 4-port 2-position hydraulic pilot switching valve, and its P port is connected to the A port of the directional control valve 21 via an oil passage 33, and the T port is an oil passage 35 and a return oil passage 32. It is connected to the tank 30 via. Of the control ports of the directional control valve 22, the A port is connected to the take-out oil passage 13 via the oil passage 36 and the oil passage 37, and the B port is connected to the forward drive side oil chamber 12 a of the pressure increasing cylinder 12. Has been. The oil passage 36 is provided with a check valve 25 that allows only hydraulic oil to flow from the direction control valve 22 side to the take-out oil passage 13 side.

  The direction control valve 22 detects the pilot pressure via the pilot pipe line 33p connected to the oil path 33, and the I position and the II position are switched by the pilot pressure. More specifically, when the pilot pressure is lower than the predetermined pressure, the direction control valve 22 is switched to the I position. Then, the P port and the A port are connected, the A port of the directional control valve 21 and the take-out oil passage 13 are connected, and the T port and the B port are connected, and the forward drive side oil chamber 12a of the pressure increasing cylinder 12 is connected. Is connected to the tank 30. When the pilot pressure is higher than the predetermined pressure, the direction control valve 22 is switched to the II position. Then, the P port and the B port are connected, the A port of the direction control valve 21 and the forward drive side oil chamber 12a of the pressure increasing cylinder 12 are connected, and the T port and the A port are connected. Therefore, when the directional control valve 21 is in the I position, the directional control valve 22 selectively removes the hydraulic oil supply destination from the hydraulic pump 11 between the extraction oil passage 13 and the forward drive side oil chamber 12a. Can be switched.

When the directional control valve 22 is in the I position, the pilot pipe line 33p is connected to the take-out oil path 13 via the oil path 33, the oil path 36, and the oil path 37. 13 oil pressures can be detected. Therefore, when the directional control valve 21 is in the I position, the directional control valve 22 connects the hydraulic pump 11 and the extraction oil passage 13 when the oil pressure of the extraction oil passage 13 is in a low pressure state, and the oil pressure of the extraction oil passage 13. When the pressure reaches a high pressure state, the hydraulic pump 11 and the forward drive side oil chamber 12a are connected. Thus, the directional control valve 22 is not limited to directly detecting the pilot pressure of the extraction oil passage 13, and may be configured to detect indirectly.
The direction control valve 22 corresponds to the first direction control valve described in the claims.

The oil passage 33 and the oil passage 35 are branched from the middle, and are connected to the direction control valve 23. The direction control valve 23 is a 4-port 2-position electromagnetic switching valve, and its P port is connected to the oil passage 33, and the T port is connected to the tank 30 via the oil passage 35 and the return oil passage 32. Of the control ports of the direction control valve 23, the A port is connected to the return oil passage 32 via the return oil passage 38, and the B port is closed. A low pressure relief valve 26 is interposed in the return oil passage 38.
The return oil passage 38 corresponds to the return oil passage described in the claims.

When the direction control valve 23 is switched to the I position, the P port and the A port are connected, the oil passage 33 and the return oil passage 38 are connected, the T port and the B port are connected, and the oil passage 35 is closed. When the direction control valve 23 is switched to the II position, the P port and the B port are connected, the oil passage 33 is closed, the T port and the A port are connected, and the oil passage 35 and the return oil passage 38 are connected. Low-pressure relief valve 26, the directional control valve 22 is operated at a lower pressure than the off changeover Waru pressure to II position to permit flow from the directional control valve 23 of the hydraulic oil to the tank 30.
The direction control valve 23 corresponds to a third control valve described in the claims.

  An oil passage 37 connected to the pressure increasing oil chamber 12 c of the pressure increasing cylinder 12 is connected to the tank 30 via a pilot check valve 27. The pilot check valve 27 normally suppresses the inflow of hydraulic oil from the take-out oil passage 13 to the tank 30 and allows the inflow of hydraulic oil from the take-out oil passage 13 to the tank 30 when the oil passage 34 is in a high pressure state.

A pressure switch 28 is connected to the pressure-increasing oil chamber 12c of the pressure-increasing cylinder 12, so that it can be detected whether or not the oil pressure in the pressure-increasing oil chamber 12c exceeds a predetermined pressure.
The pressure switch 28 and the directional control valves 21 and 23 are connected to a control means (not shown). An operation switch provided on the crimping tool T or the like is also connected to the control means. The control means receives the operation switch and the pressure switch, and operates the pressure increasing device 1 by switching the direction control valves 21 and 23 based on the signal.

  In general, the take-out oil passage 13 is constituted by a hydraulic hose. Most of the pressure booster 1 is provided on the vehicle side of the aerial work vehicle, and only the hydraulic hose constituting the take-out oil passage 13 is guided to the bucket through the boom. A quick joint 29 is provided at the tip of the hydraulic hose constituting the take-out oil passage 13 and can be connected to various hydraulic tools T.

Next, the operation of the pressure booster 1 will be described.
The crimping tool T has (1) a stopped state in which the crimping portion for crimping the sleeve is not operated, (2) a temporary gripping operation for gripping the sleeve by driving the crimping portion at low pressure, and (3) driving the crimping portion at high pressure. Thus, the main compression operation for crimping the sleeve and (4) the return operation for opening the crimping portion can be performed. In hydraulic tools other than the crimping tool, (1) a state in which no hydraulic oil is supplied, (2) a state in which low-pressure oil is supplied, (3) a state in which high-pressure oil is supplied, and (4) hydraulic oil Although there are discharge states, these are the same as the stop state of the crimping tool, the temporary gripping operation, the main compression operation, and the returning operation, and therefore, the crimping tool will be described below as an example.

(1) Stop State As shown in FIG. 1, in the stop state, the control means sets the direction control valve 21 to the II position (neutral position) and sets the direction control valve 23 to the I position. The oil passage 33 is in a low pressure state without being supplied with hydraulic oil from the hydraulic pump 11, and the direction control valve 22 is in the I position. Further, the rod of the pressure increasing cylinder 12 is located at the end of the backward movement.
In the stop state, the hydraulic oil from the hydraulic pump 11 returns to the tank 30 via the relief valve 24. The crimping tool T stops operating in a state where the hydraulic oil is not supplied and the crimping portion is opened.

(2) Temporary gripping operation When switched to the temporary gripping operation by an operation switch or the like, the control means switches the direction control valve 21 to the I position as shown in FIG. The direction control valve 23 remains in the I position.
In the temporary gripping operation, the oil pressure in the oil passage 33 is maintained at a low pressure state by the low pressure relief valve 26, so the direction control valve 22 remains in the I position. The hydraulic oil from the hydraulic pump 11 is supplied to the extraction oil passage 13, and the hydraulic oil is supplied from the extraction oil passage 13 to the crimping tool T. Since the hydraulic pressure supplied to the crimping tool T is controlled by the low-pressure relief valve 26, the sleeve can be gripped by driving the crimping portion of the crimping tool T with the low-pressure oil determined by the low-pressure relief valve 26.

(3) Main compression operation When switched to the main compression operation by an operation switch or the like, as shown in FIG. 3, the control means switches the direction control valve 23 to the II position. The direction control valve 21 remains in the I position.
At the initial stage of the compression operation, the pilot pressure of the directional control valve 22, that is, the hydraulic pressure of the take-out oil passage 13 is in a low pressure state, and the directional control valve 22 remains in the I position. In this case, the hydraulic oil from the hydraulic pump 11 is supplied to the extraction oil passage 13, and the hydraulic oil is supplied from the extraction oil passage 13 to the crimping tool T. That is, the flow of hydraulic oil is the same as that of the temporary gripping operation.

  When the pilot pressure of the direction control valve 22, that is, the oil pressure of the take-out oil passage 13 obtained through the oil passage 33, the oil passage 36, and the oil passage 37 becomes a high pressure state, as shown in FIG. Switch to position. In this case, the hydraulic oil from the hydraulic pump 11 is supplied to the forward drive side oil chamber 12 a of the pressure increasing cylinder 12. Then, the rod of the pressure increasing cylinder 12 moves forward, and the high pressure oil is discharged from the pressure increasing oil chamber 12c. High-pressure oil from the pressure-increasing oil chamber 12 c is supplied to the take-out oil passage 13 and is supplied from the take-out oil passage 13 to the crimping tool T. The crimping tool T can drive the crimping portion at a high pressure to crimp the sleeve.

  As described above, also in the main compression operation, the directional control valve 22 is switched based on the pilot pressure so that the hydraulic oil from the hydraulic pump 11 is directly supplied to the take-out oil passage 13 and then the pressure increasing cylinder. The sequence in which the high pressure oil from 12 is supplied to the take-out oil passage 13 is performed. For example, even if the main compression operation is suddenly performed without going through the temporary gripping operation, the high-pressure oil is always discharged after the extraction oil passage 13 is in a high pressure state through the same flow of hydraulic oil as in the temporary gripping operation. To be supplied. Therefore, even if air enters the take-out oil passage 13, the air is compressed in advance by the hydraulic oil from the hydraulic pump 11, so that supply failure of the high-pressure oil does not occur, and the operator feels uncomfortable in operation. There is no.

Further, when hydraulic fluid is supplied to the crimping tool T via the pressure-increasing cylinder 12, the operating speed of the crimping tool T is reduced by the pressure-increasing ratio, but the pressure-intensifying device 1 according to the present embodiment operates from the hydraulic pump 11. Since oil is taken out and supplied directly to the oil passage 13, the operation speed of the crimping tool T can be increased accordingly.
Furthermore, since the hydraulic oil from the hydraulic pump 11 is directly supplied to the take-out oil passage 13 and then the high-pressure oil from the pressure-increasing cylinder 12 is supplied to the oil-out passage 13, the amount of hydraulic oil supplied by the pressure-increasing cylinder 12 is reduced. Less. Therefore, a small pressure increasing cylinder 12 can be used.

(4) Returning operation When the pressure switch 28 detects that the pressure exceeds a predetermined pressure, for example, a specified pressure, or when the pressure switch 28 is switched to the returning operation by an operation switch or the like, as shown in FIG. Switch to the III position and switch the directional control valve 23 to the I position.
In the returning operation, since the oil passage 33 is connected to the tank 30 and is in a low pressure state, the direction control valve 22 is switched to the I position. The hydraulic oil from the hydraulic pump 11 is supplied to the backward drive side oil chamber 12 b of the pressure-increasing cylinder 12 through the oil passage 34. Then, the rod of the pressure-increasing cylinder 12 moves backward so that the working oil in the crimping tool T returns to the pressure-increasing oil chamber 12c, and the working oil in the forward drive side oil chamber 12a is discharged to the tank 30. Further, since the oil passage 34 is in a high pressure state and the pilot check valve 27 is opened, surplus hydraulic oil that does not fit in the pressure-increasing oil chamber 12 c is discharged to the tank 30. Thereby, pressure is released and the crimping | compression-bonding part can open the crimping | compression-bonding tool T. FIG.

  As described above, by temporarily switching the directional control valve 21 between the I position and the III position, the temporary gripping operation and the main compression operation for supplying hydraulic oil to the crimping tool T and the return operation for discharging the hydraulic oil from the crimping tool T are performed. And can be switched.

(Second Embodiment)
Although the pressure increasing device 1 according to the first embodiment is configured to switch the direction control valve 22 by the pilot pressure, it may be configured to be switched by a signal such as a pressure switch.
As shown in FIG. 6, the pressure booster 2 according to the second embodiment of the present invention uses an electromagnetic switching valve as the direction control valve 22 in the pressure booster 1 according to the first embodiment, The pressure switch 40 is provided to detect whether or not the hydraulic pressure exceeds a predetermined pressure. These directional control valve 22 and pressure switch 40 are connected to the control means. In the main compression operation, when the pressure switch 40 is in the non-detection state, the control means connects the hydraulic pump 11 and the extraction oil passage 13 with the direction control valve 22 set to the I position, and controls the direction when the pressure switch 40 enters the detection state. Control is performed so that the hydraulic pump 11 and the forward drive side oil chamber 12a of the pressure-increasing cylinder 12 are connected with the valve 22 in the II position. Since the rest of the configuration is the same as that of the pressure booster 1 according to the first embodiment, the same reference numerals are assigned to the same members, and descriptions thereof are omitted .

  Also in the present embodiment, in the main compression operation, after the directional control valve 22 is switched based on the signal of the pressure switch 40, the hydraulic oil from the hydraulic pump 11 is directly supplied to the extraction oil passage 13. The sequence in which the high-pressure oil from the pressure-increasing cylinder 12 is supplied to the take-out oil passage 13 is performed. Therefore, even if air enters the take-out oil passage 13, the air is compressed in advance by the hydraulic oil from the hydraulic pump 11, so that supply failure of the high-pressure oil does not occur, and the operator feels uncomfortable in operation. There is no.

DESCRIPTION OF SYMBOLS 1, 2 Pressure increase device 11 Hydraulic pump 12 Pressure increase cylinder 12a Forward drive side oil chamber 12b Reverse drive side oil chamber 12c Pressure increase oil chamber 13 Extraction oil path 21 Direction control valve 22 Direction control valve 23 Direction control valve T Pressure bonding tool

Claims (2)

A pressure increasing device for supplying high pressure oil to a hydraulic tool,
A hydraulic source;
A pressure-increasing cylinder having a forward drive side oil chamber, a reverse drive side oil chamber, and a pressure increase oil chamber whose volume is reduced by the forward movement of the rod and increased by the backward movement ;
A take-out oil passage connected to the pressure increasing oil chamber and connectable to the hydraulic tool;
A first directional control valve that selectively switches a supply destination of hydraulic oil from the hydraulic source between the take-out oil passage and the forward drive side oil chamber;
A second directional control valve that selectively switches a supply destination of hydraulic oil from the hydraulic source between the first directional control valve and the backward drive side oil chamber;
A return oil passage branched from an oil passage connecting the first directional control valve and the second directional control valve and connected to the tank;
A low-pressure relief valve provided in the return oil passage;
A third control valve for opening and closing the return oil path,
The first directional control valve connects the hydraulic source and the take-out oil passage when the oil pressure of the take-out oil passage is in a low pressure state, and the hydraulic power source when the oil pressure of the take-out oil passage is in a high pressure state. Connecting the forward drive side oil chamber,
The pressure increasing device for an aerial work vehicle , wherein the low pressure relief valve operates at a pressure lower than a hydraulic pressure at which the first directional control valve is switched . Control means for switching the second directional control valve and the third control valve based on a signal input from the operating means of the hydraulic tool;
The hydraulic tool has at least a state of supplying low-pressure oil and a state of supplying high-pressure oil,
The control means includes
When the operation means switches to a state in which low-pressure oil is supplied, the second direction control valve is brought into a state of connecting the hydraulic power source and the first direction control valve, and the third control The valve is in a state of opening the return oil passage,
When the operation means switches to a state in which high-pressure oil is supplied, the second direction control valve is brought into a state in which the hydraulic power source and the first direction control valve are connected, and the third control The pressure increasing device for an aerial work platform according to claim 1 , wherein the valve is in a state of closing the return oil passage .

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