JP2004345856A - Leveling device for high lift work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leveling device for a high lift work vehicle capable of holding a work base horizontally when storing a boom. <P>SOLUTION: This leveling device 20 for the high lift work vehicle 1 has a vehicle body 2 capable of running, a swivel base 4 provided on the vehicle body 2, the boom 5 connected pivotally with the swivel base 4, and the work base 7 attached to a tip part of the boom 5. A rising control valve SV<SB>2</SB>controlling supply and discharge of hydraulic fluid and a leveling cylinder 53 arranged between the swivel base 4 and the boom 5 to hold the rising cylinder 52 and the work base 7 horizontally are connected in series through a first oil passage 61, a second oil passage 62, and a third oil passage 63. This leveling device has a boom storage detection actuator 56 detecting that the boom 5 is loaded on a boom receiver 9 and is stored and a third pilot check valve 91 opening a fourth oil passage 64 when detecting the storage of the boom 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aerial work vehicle having a boom mounted on a vehicle body of an aerial work vehicle, and a work table mounted on a tip portion of the boom, and horizontally holding the work table according to the up-and-down movement of the boom. A leveling device.

  The aerial work vehicle equipped with the leveling device as described above is provided with a swivel base that can swing with respect to the vehicle body on a vehicle body of a vehicle that can travel, and the swivel base can freely move up and down by the expansion and contraction operation of an up-and-down cylinder. A leveling member having a vertical post that can swing within the elevation angle plane of the boom by the expansion and contraction operation of the leveling cylinder is connected to the tip of the boom, and a workbench is attached to the vertical post. It is configured. The vertical post part is leveled and controlled by the leveling cylinder to swing the workbench up and down according to the boom up and down so that the workbench always keeps its horizontal position with respect to the vehicle body. Therefore, the floor of the workbench is always kept horizontal. Further, a boom receiver that supports the boom by contacting the lower surface of the boom that protrudes upward and falls down in a fully contracted state is provided, and a jack device that lifts and supports the body is provided on both front and rear sides of the body.

  In order to prevent the jack device from operating while the boom is operating or the boom from operating while the jack device is operating, an interface that restricts the simultaneous operation of the boom and the jack device is provided on the aerial platforms as described above. In order to perform interlock control to start the retracting operation of the jack device when the boom is in the retracted state, for example, the boom receiver is mounted on the boom receiver and stored in the boom receiver. Is installed.

  Such a boom storage detection device is configured to include, for example, a limit switch and a storage detection circuit, and when the lower surface of the boom comes into contact with the switch portion of the limit switch and the limit switch is operated when the boom is lowered or raised. The storage detection circuit electrically detects that the boom is stored in the storage device.

In addition, there are various types of leveling devices for aerial work vehicles as described above, and one of them is a so-called undulating cylinder-linked leveling device in which an undulating cylinder and a leveling cylinder are connected by a series hydraulic circuit. is there. This leveling device has a boom 105 pivotally connected to a swivel table 104 so as to be able to swing up and down, as shown in FIG. 7 showing a schematic configuration of a leveling mechanism, and FIG. 8 showing a main hydraulic circuit diagram of the leveling device. An up-and-down cylinder 152 stretched between the swivel base 104 and the boom 105 to raise and lower the boom; a leveling member 106 having a vertical post portion pivotally connected to the tip of the boom 105 so as to be able to swing up and down; A worktable 107 horizontally pivotally mounted on the post, an extendable leveling cylinder 153 stretched between the boom 105 and the leveling member 106, and a boom operation for switching the flow of hydraulic oil from the hydraulic pump P and a control valve _{SV 102.}

These hydraulic devices connect a first oil passage 161 connecting the boom operation control valve SV ₁₀₂ to the bottom oil chamber of the up-and-down cylinder 152, and connect a rod-side oil chamber of the up-and-down cylinder 152 to a bottom-side oil chamber of the leveling cylinder 153. second oil passage 162, other third oil passage 163 connecting the rod side oil chamber and the boom actuation control valves _{SV 102} of the leveling cylinder 153, the hydraulic circuit is configured to have a pump oil passage 160 and the tank fluid passage 167 Have been.

The undulating holding valve 171 that opens and closes the first oil passage 161 in accordance with the operating oil pressure of the third oil passage 163 supplied through the fourth oil passage 164 is connected to the first oil passage when the boom operation control valve SV ₁₀₂ is closed. The path 161 is shut off to keep the boom 5 from falling freely, and when the boom 5 is to be moved down, the valve is opened and the up / down cylinder 152 is contracted.

Further, only the leveling cylinder 153 to extend and retract operation by feeding to the fifth oil passage 165 or the sixth oil passage 166 to supply and discharge controlling hydraulic oil discharged from the hydraulic pump by leveling adjustment valve SV _103, the platform 107 vertically And leveling adjustment can be performed so that the posture becomes horizontal.

  Here, the amount of change in the undulation angle of the boom 105 raised by the extension operation of the undulation cylinder 152 and the undulation of the leveling member 106 that is lowered by the leveling cylinder 153 extended by the hydraulic oil discharged from the undulation cylinder 152. The angle change is set to be the same. For this reason, the vertical post of the leveling member 106 is always held vertically regardless of the elevation angle of the boom 105, and the workbench 107 is kept horizontal. This leveling control also functions in the case of the boom 105 falling down.

However, in the above-described leveling device interlocking with the up-and-down cylinder, if the boom is operated so that the boom 105 moves up and down (presses against the boom receiver) while the boom 105 is placed and stored in the boom receiver, Since the boom 105 is already stored, the up-and-down cylinder 152 does not perform the contraction operation. However, since the boom operation control valve SV ₁₀₂ is opened to the side where the hydraulic oil is supplied to the rod-side oil chamber of the leveling cylinder 153, the leveling is performed. Hydraulic oil flows into the rod-side oil chamber of the cylinder 153, and the leveling cylinder 153 is slightly reduced so as to compress the hydraulic oil in the bottom-side oil chamber of the leveling cylinder 153, whereby the work table 107 is tilted. That is, when the boom 105 is placed and stored in the boom receiver, the up-and-down cylinder 152 does not operate in conjunction with the movement of the leveling cylinder 153, and only the leveling cylinder 153 operates. There is a problem that the leveling state is deviated by tilting from the position.

  In addition, if time elapses after the boom 105 is stored in the boom receiver, the leveling cylinder may also change due to a temporal change such as contraction of the oil path due to a decrease in the oil temperature of the hydraulic oil in the rod-side oil path of the leveling cylinder 153 or leakage of the hydraulic oil. There is a problem that only the work 153 is reduced and the worktable 107 is tilted and the leveling state is deviated.

  Further, in a state where the boom is placed and stored in the boom receiver, only the leveling cylinder 153 is operated and the workbench is tilted from a horizontal state. There is also a problem that the workbench may interfere with the bodywork / structure provided in the vehicle.

  In view of the above problems, in the present invention, when a boom is placed and stored in a boom receiver, the boom storage detection device includes a boom storage detection device that holds the work table horizontally without causing a disorder in the leveling state. An object of the present invention is to provide a leveling device for a work vehicle.

In order to solve the above-mentioned problems, a leveling device for an aerial work vehicle according to the present invention includes a movable vehicle body, a swivel provided on the vehicle body so as to be able to swing, and a pivotally connected to the swivel so as to be able to move up and down. A boom, an up-and-down cylinder arranged between the swivel table and the boom for raising and lowering the boom, a worktable attached to a tip end of the boom so as to swing up and down, and a boom mounted on a vehicle body. A boom receiver for placing and storing, a leveling cylinder that swings the worktable up and down in response to the boom up and down movement to hold the worktable horizontally, and an oil chamber and a leveling cylinder on one side of the up and down cylinder Supply / discharge of hydraulic oil to / from a communication oil path (for example, the second oil path 62 in the embodiment) connecting the oil chamber on one side of the hydraulic cylinder to the oil chamber on the other side of the undulating cylinder and the oil chamber on the other side of the leveling cylinder. Control valve for controlling Stage (e.g., relief control valve SV 2 in the _embodiment) configured to have a hydraulic supply means for supplying hydraulic fluid to the control valve means (e.g., hydraulic pump P in the embodiment) and a. Then, when the boom provided on the boom receiver is placed and stored in the boom receiver, the boom is pressed by the boom and can move in the boom falling direction (for example, the boom storage detection in the embodiment). A leveling-side oil passage (for example, a second oil passage in the embodiment) connecting the rod portion 56a of the actuator 56 or the boom storage detection lever 57) to the control valve means and the other oil chamber of the leveling cylinder in accordance with the movement of the boom contact portion. Oil path opening means (for example, the third pilot check valve 91 or the shut-off valve 94 in the embodiment) for opening the third oil path 63) to the tank.

  Further, in the leveling device for an aerial work vehicle having the above-described configuration, the pilot pressure generation that operates in response to the movement of the boom contact portion (for example, the rod portion 56a of the boom storage detection actuator 56 in the embodiment) and outputs the pilot pressure. Means (for example, the boom storage detection actuator 56 in the embodiment), and the oil passage opening means (for example, the third pilot check valve 91 in the embodiment) receives the pilot pressure to open the leveling-side oil passage. Preferably.

  Further, in the leveling device for an aerial work vehicle having the above-described configuration, the oil passage opening means (for example, the shut-off valve 94 in the embodiment) is used to move the boom contact portion (for example, the boom storage detection lever 57 in the embodiment). It may be configured to operate in response to opening the leveling-side oil passage.

  As described above, according to the leveling device for an aerial work vehicle according to the present invention, when the boom is placed and stored in the boom receiver, the leveling-side oil passage is opened and the hydraulic oil is discharged. When the boom is raised and lowered in this state, the hydraulic oil from the hydraulic pump does not flow into the leveling cylinder and is discharged to the tank, preventing the leveling cylinder alone from contracting and causing an irregular leveling state. There is no. Moreover, since the hydraulic oil in the leveling-side oil passage is discharged immediately after the storage of the boom, the hydraulic oil hardly leaks from the oil passage on the rod side of the leveling cylinder even after a lapse of time immediately after the storage of the boom. It is possible to prevent the leveling state from being disordered due to a change over time.

  Also, for example, if a boom storage detection actuator provided on a boom receiver is used, the tip of the rod portion (boom contact portion) of the boom storage detection actuator contacts the lower surface of the boom, and then, for example, the bottom side of the boom storage detection actuator The elastic force of the biasing means provided and the hydraulic pressure of the bottom oil chamber of the boom storage detection actuator act in a direction to move the rod portion of the boom storage detection actuator upward against the boom lowering / lowering operation. . For this reason, the tip of the rod portion does not move below the same surface as the abutment surface of the boom receiver, and the boom does not stop in the state where the boom floats from the boom receiver, and the boom does not move. There is no risk of damaging the boom receiver because the receiver is not pressed.

  Further, when the boom storage detection lever is used, when the boom is placed and stored in the boom receiver, the boom abutment portion is pressed by the boom mounted on the boom receiver and the valve means is activated. Then, the oil passage opening means opens the oil passage on the leveling side. Then, when the boom is raised and lowered in this state, the hydraulic oil from the hydraulic supply means passes through the oil passage opening means and is directly discharged to the tank. For this reason, the hydraulic oil does not flow into the rod-side oil chamber of the leveling cylinder, so that only the leveling cylinder can be prevented from contracting and the leveling state does not change.

  In any of the above-mentioned inventions, only the leveling cylinder operates and the work table does not tilt from a horizontal state in a state where the boom is placed and stored in the boom receiver. It is possible to safely perform high-altitude work without fear of the work table interfering with a bodywork / structure provided on the vehicle body and near the work table.

  Hereinafter, a preferred embodiment of a leveling device for an aerial work vehicle according to the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 shows an example of an aerial work vehicle provided with a leveling device for an aerial work vehicle according to the present invention. The aerial work vehicle 1 can travel with front and rear wheels 3a and 3b on the front and rear and left and right sides of a vehicle body 2, and is configured based on a truck vehicle having a driving cabin 2a at a front portion of the vehicle body 2. A swivel base 4 that is driven by a swivel motor 51 and is configured to be able to turn horizontally is disposed on the body 2 of the truck vehicle. A boom 5 is attached to the swivel base 4 by pivotally connecting a base end thereof, and the boom 5 is raised and lowered by a lifting cylinder 52. The boom 5 is configured such that the base boom 5a, the intermediate boom 5b, and the distal boom 5c are nested and combined, and the entire boom 5 can be extended and contracted in the longitudinal axis direction by a built-in telescopic cylinder 54.

  The tip boom 5c has a boom head 5d at the tip, and a vertical post member 6 is pivotally connected to the boom head 5d and is vertically swingably mounted. The vertical post member 6 is controlled by a leveling cylinder 53, which will be described later, disposed between the end of the tip boom 5c or the end of the boom head 5d and the vertical post member 6, to thereby control the swinging of the boom 5. Regardless of the above, the vertical post member 6 is controlled to swing so that the vertical post member 6 always extends vertically. The work table 7 is attached to the vertical post member 6 which is always held vertically in such a manner as to be horizontally swivelable (swingable) by a swing motor (not shown), and the work table 7 is always horizontal regardless of the up-and-down movement of the boom 5. Is held.

  The workbench 7 is provided with a boom operating device 11 for performing an operation for operating the boom 5, and an operator riding on the workbench 7 operates the operating lever of the boom operating device 11 to operate the boom 5. The work table 7 can be freely rotated, raised and lowered, extended and contracted, and the work table 7 can be moved to an arbitrary high position.

  A jack device 8 is provided at four front, rear, left, and right sides of the vehicle body 2 so as to widen the vehicle body 2 in the left-right direction and expand and contract below the vehicle body 2. The vehicle body 2 can be stably lifted and supported by widening to the left and right and extending and extending downward. A boom receiver 9 is provided at the center of the vehicle body 2 and projects upward and abuts against the lower surface of the boom 5 that has fallen down in a fully contracted state and stores and supports the boom 5.

First embodiment

  Here, a first embodiment using the leveling device 20 for an aerial work vehicle according to the present invention will be described with reference to FIGS. 2 and 3. In this embodiment, a boom storage detection actuator 56 which is attached to the boom receiver 9 on the vehicle body 2 and receives the pressing force of the boom 5 to output the pilot pressure when the boom 5 is placed and stored in the boom receiver 9. And a control unit 30 that receives an operation signal output from the boom operating device 11 and outputs a command signal to the hydraulic unit 40 to control the operation of the boom 5 and the like. A hydraulic unit 40 that controls supply and discharge of hydraulic oil to and from the cylinder 52 is provided.

Hydraulic unit 40 and the swivel control valve SV ₁ for controlling the pivotal movement of the swing motor 51, the relief control valve SV ₂ that controls the expansion and contraction motion of the derricking cylinder 52 and the leveling cylinder 53, and a leveling cylinder 53 to extend and retract the dynamic leveling adjustment a leveling adjustment valve SV ₃ for performing a telescopic control valve SV ₄ for controlling the expansion and contraction movement of the telescopic cylinder 54, a third pilot check valve 91 which operates by receiving a pilot pressure outputted from the boom storage detection actuator 56 Having. Each control valve SV ₁ , SV ₂ , SV ₃ , SV ₄ is an electromagnetic control valve whose opening is controlled by the control unit 30, and the operation of each cylinder and the like is for driving a pump (not shown) disposed on the vehicle body 2. each control valve _SV 1 the hydraulic oil discharged from the hydraulic pump P _{driven, SV 2, SV 3, SV} 4 is carried out by supply and discharge control by the engine.

Relief control valves SV ₂ for controlling the undulating movement of the boom 5 is an electromagnetic proportional control valve of four-port three-position of the neutral return type, the valve spool in the movement direction and the movement amount corresponding to the command signal from the control unit 30 Displaced to control the flow of hydraulic oil between the four ports (A, B, P, T ports) of the valve body.

Of the four ports of the relief control valve SV _2, the P port and the hydraulic pump P is connected via a pump oil passage 60, the hydraulic oil discharged from the hydraulic pump P is supplied. Further, T port is connected to the tank T through the tank fluid passage 80, the operating oil returning from the A or B port undulating control valve SV ₂ is discharged to the tank T.

  A first oil passage 61 and a third oil passage 63 are connected to the A port and the B port, respectively. The first oil passage 61 extends toward the up / down cylinder 52 and is connected to the bottom oil chamber 52a of the up / down cylinder. On the other hand, the third oil passage 63 extends toward the leveling cylinder 53 and is connected to a rod-side oil chamber 53b of the leveling cylinder. As described above, the rod-side oil chamber 52b of the undulating cylinder and the bottom-side oil chamber 53a of the leveling cylinder are connected by the second oil passage 62, and a series circuit is formed.

Relief control valves SV ₂ and derricking cylinder 52 and undulations holding valve 71 disposed on the first oil passage 61 connecting is an external pilot type valves, relief holding the second oil passage 62 through the seventh oil passage 67 The first oil passage 61 is opened and closed according to the operating oil pressure supplied to the valve 71 pilot port.

The undulations holding valve 71, relief control valve SV ₂ is held to the oil pressure of the bottom-side oil chamber 52a of blocking the first oil passage 61 derricking cylinder when it is closed, so that the boom 5 does not free fall When the boom 5 is lowered and operated, the boom 5 is opened and the up-and-down holding valve 71 is opened in accordance with the operating oil pressure supplied to the pilot port of the up-and-down holding valve 71 from the second oil passage 62 to reduce the up-and-down cylinder 52.

Further, when the relief control valve SV ₂ is closed, the first oil passage 61 by the first pilot check valve 72, the second pilot check valve 74 and the third oil passage 63 is cut off together, the bottom side oil derricking cylinder The pressure of the chamber 52a and the pressure of the rod-side oil chamber 53b of the leveling cylinder are both held, and the angle of the undulating cylinder 52 and the leveling cylinder 53 is held. On the other hand, when the relief control valve SV ₂ hydraulic oil to the first oil passage 61 or the third oil passage 63 is supplied open, hydraulic oil supplied to the derricking cylinder 52 or the leveling cylinder 53 through the pilot check valve of the supply line-side At the same time, the pilot check valve on the other side is opened through the pilot line (the eighth oil passage 68 or the ninth oil passage 69), and the up-and-down cylinder 52 and the leveling cylinder 53 are extended and contracted.

  A double holding valve 73 is provided in the second oil passage 62 and the third oil passage 63 with the leveling cylinder 53 interposed therebetween. This valve is a valve in which two counterbalance valves having the same function as the undulating holding valve 71 are incorporated in an integrated valve body, and serves as an external pilot of a valve provided on the second oil passage 62 side. The supply pressure of the second oil passage 62 is used as an external pilot of a valve provided on the third oil passage 63 side.

Therefore, when the relief control valve SV ₂ is closed, the second oil passage 62 and the third oil passage 63 is blocked together by a double holding valve 73, the leveling cylinder bottom-side oil chamber 53a and the rod side oil chamber 53b The pressure is held together, and the leveling angle position of the leveling cylinder 53 is held. On the other hand, when the relief control valve SV ₂ hydraulic oil in the second oil passage or the third oil passage is supplied open, with the hydraulic fluid is supplied to the leveling cylinder 53 through the check valve of the supply line-side valve, pilot The valve on the other side is opened through the line, and the leveling cylinder 53 is extended and retracted.

Further, the second oil passage 62 is a fifth oil passage 65, the third oil passage 63 is connected to No. 6 oil passage 66, the leveling adjustment valve SV ₃ for performing these oil paths leveling adjustment Through to the hydraulic pump P and the tank T. During the leveling adjustment, the leveling adjustment valve SV ₃ is moved upward or downward in FIG. 3 by the movement amount corresponding to a command signal from the control unit 30, the bottom side of the leveling cylinder hydraulic oil in the tank through the leveling adjustment valve SV ₃ The leveling cylinder 53 is supplied to the oil chamber 53a or the rod-side oil chamber 53b to expand and contract. By such an operation, only the leveling cylinder 53 can be expanded and contracted in accordance with the leveling adjustment operation, and the worktable 7 can be swung up and down to perform leveling adjustment so that the posture becomes horizontal.

Further, the sixth oil passage 66 between the third oil passage 63 and the leveling adjustment valve SV ₃ have been connected to the fourth oil passage 64, the third pilot check valve which can be opened and closed on the fourth oil passage 64 91 (oil passage opening means) is provided. The third pilot check valve 91 receives the pilot pressure from the boom storage detection actuator 56 which extends from the boom storage detection actuator 56 and is transmitted through the first pilot oil passage Pi ₁ connected to the third pilot check valve 91. It operates to open the fourth oil passage 64.

Here, as shown in FIG. 4, to describe the structure of the third pilot check valve 91, the third pilot check valve 91, respectively, the tank T, a third oil passage 63, the second pilot oil passage Pi ₂ or No. It is composed of a port communicating with the three pilot oil passage Pi ₃ and the first pilot oil passage Pi ₁ , a spring 91 a, a check ball 91 b, a spool 91 c including a rod portion 91 d and a piston 91 e.

  In the state where the third pilot check valve 91 is closed, the check ball 91b is closed by the downward biasing force of the spring 91a in the drawing, so that the port communicating with the tank T and the third oil passage 63 is shut off. Therefore, hydraulic oil does not flow into the tank T from the third oil passage 63 (leveling-side oil passage).

On the other hand, if via the first pilot oil path Pi ₁ receives a pilot pressure from the boom storage detection actuator 56, against the bias of the piston 91e spring 91a moves upward in FIG. 4 by the pilot pressure, the check ball 91b is Be released. Therefore, the port communicating with the tank T and the third oil passage 63 communicates with each other, and the hydraulic oil can be discharged from the third oil passage 63 to the tank T.

When the leveling adjustment valve SV ₃ in FIG. 3 is closed, the fifth oil passage 65 and the sixth oil passage 66 are both blocked by the fourth pilot check valve 92 and the fifth pilot check valve 93, respectively. Meanwhile, when opening the leveling adjustment valve SV ₃ by supplying hydraulic oil to the fifth oil passage 65 or the sixth oil passage 66 performs leveling adjustment bottom-side oil chamber of the leveling cylinder through the pilot check valve of the supply line-side The hydraulic oil is supplied to 53a or the rod-side oil chamber 53b, and the pilot check valve on the other side is opened through the pilot line (the tenth oil passage 81 or the eleventh oil passage 82).

The fifth third pilot check from the sixth oil passage 66 between the oil passage 65 and the leveling adjustment valve SV ₃ and the 5 pilot check valve 93 between the leveling adjustment valve SV ₃ and the fourth pilot check valve 92 the second pilot oil path Pi ₂ and the third pilot oil path Pi ₃ each valve 91 is connected.

The second pilot oil path Pi ₂ and the third pilot oil path Pi _3, when performing the leveling adjustment in a state in which the boom 5 is stored is placed on the receiving boom 9, the pilot pressure from the leveling adjustment valve SV ₃ To the third pilot check valve 91. And by the pilot pressure to close the third pilot check valve 91 against the pilot pressure which tends to open the third pilot check valve 91 which is transmitted through the first pilot oil path Pi ₁ from the boom storage detection actuator 56 By blocking the fourth oil passage 64, leveling adjustment with the boom 5 stored is enabled.

The operation of the third pilot check valve 91 at this time will be described with reference to FIG. 4. The pilot pressure from the boom storage detection actuator 56 moves the piston 91 e upward in the figure to release the check ball 91 b. anti to the piston 91e by the pilot pressure from the second pilot oil path Pi ₂ or third pilot oil path Pi ₃ is subjected to pressure downward. Since the piston 91e does not move upward to balance with the pressure for moving the piston 91e upward, and the check ball 91b is not opened, the ports communicating with the tank T and the third oil passage 63 do not communicate with each other. . Therefore, the hydraulic oil is not discharged from the third oil passage 63 (the oil passage on the leveling side) to the tank T, and the leveling can be adjusted.

In the leveling device 20 for an aerial work vehicle having the above-described configuration, when the boom 5 is placed and stored in the boom receiver 9, the rod portion 56 a of the boom storage detection actuator 56 contacts the boom 5 and It pushed down by, for outputting a pilot pressure to the first pilot oil path Pi _1. The third pilot check valve 91 which has received the transmitted pilot pressure through a first pilot oil path Pi ₁ opens the fourth oil passage 64.

When the boom 5 (the boom 5 so press the boom receive 9) to operate laid down operates the boom operating device 11 in this state, hydraulic oil flowing out from the relief control valve SV ₂ in the third oil passage 63 is Instead of flowing into the rod-side oil chamber 53b of the leveling cylinder, it is discharged to the tank through the fourth oil passage 64, the leveling cylinder 53 does not operate, and the worktable 7 remains horizontal.

When raising the boom 5, the boom operating device 11 is operated in the raising / lowering direction of the boom 5 to move the valve spool of the lifting / lowering control valve SV <b> ₂ rightward in the drawing, and the pump oil passage 60 and the first oil passage 61, the tank oil passage 80 and the third oil passage 63 are respectively connected. Hydraulic oil supplied from the hydraulic pump P passes through a first pilot check valve 72 on the first oil passage 61 and a check valve in the undulating holding valve 71 and is supplied to the bottom-side oil chamber 52a of the undulating cylinder. The piston 52 moves upward, and the hydraulic oil in the rod-side oil chamber 52b of the undulating cylinder flows through the second oil passage 62 into the bottom-side oil chamber 53a of the leveling cylinder. Hydraulic oil is supplied to the pilot port of the second pilot check valve 74 via an eighth oil passage 68 connected to the first oil passage 61, and the check valve 74 is opened to open the check valve 74, and the rod-side oil chamber 53b of the leveling cylinder is opened. , The hydraulic oil is discharged to the tank T.

Further, when the boom 5 is separated from the boom receiver 9, the rod portion 56a of the boom storage detection actuator 56 that has been in contact with the lower surface of the boom 5 is released from the pressing force of the boom 5, and the rod portion is moved to the boom storage detection actuator. It moves upward due to the restoring force of the spring attached in 56. The pilot pressure is not output to the first pilot oil path Pi ₁ from the boom storage detection actuator 56, a third pilot check valve 91 is closed. For this reason, the fourth oil passage 64 is shut off, and the hydraulic oil is not discharged from the fourth oil passage 64 to the tank, and the up-and-down cylinder 52 and the leveling cylinder 53 are extended and operated in conjunction with each other, so that the normal leveling of the worktable 7 is performed. Control becomes possible. For this reason, even when the boom 5 is caused to fall down, the third pilot check valve 91 is closed and the fourth oil passage 64 is disconnected until the lower surface of the boom 5 contacts the rod portion 56a of the boom storage detection actuator 56 and pushes it down. No hydraulic oil is discharged to the tank, and normal leveling control of the worktable 7 can be performed.

On the other hand, when performing the leveling adjustment is in a state of storing the boom 5 the boom receiving 9, for example, the contract the leveling cylinders 53, to move the valve spool of the leveling adjustment valve SV ₃ upward in FIG. 3. At this time the hydraulic fluid supplied through the third pilot oil passage Pi ₃ causes the closing of the third pilot check valve 91 is supplied to the pilot port of the third pilot check valve 91. For this reason, the hydraulic oil that has passed through the fifth pilot check valve 93 is supplied to the rod-side oil chamber 53b of the leveling cylinder without returning to the tank T because the third pilot check valve 91 is closed as described above. Then, the leveling cylinder 53 is contracted to enable leveling adjustment in a state where the boom 5 is placed and stored in the boom receiver 9.

Second embodiment

Next, a second embodiment using the leveling device 20 for an aerial work vehicle according to the present invention will be described with reference to FIGS. In the present embodiment, a boom storage detection lever 57 is used, and is operated to open the oil passage opening means. As shown in FIG. 6, the hydraulic circuit configuration of the leveling device 20 according to the present embodiment is substantially the same as that of the first embodiment, but a pilot check valve 73 is provided in the third oil passage 63. instead, on the fourth oil passage 64 that connects the relief control valve SV ₂ and the first oil passage 61 between the first pilot check valve 72 and a third oil passage 63, open or cut off the fourth oil passage 64 A shut-off valve 94 is provided.

  The shut-off valve 94 has a boom storage detection lever 57 that is attached to the boom receiver 9, extends from the valve spool, and is movable by being pressed against the lower surface of the boom 5, and is not pressed by the boom 5. This is a neutral return type valve which is sometimes in a neutral state (the state shown in FIG. 10). When the boom storage detection lever 57 abuts against the boom 5 and is pressed, the valve spool in the shut-off valve 94 moves downward in the figure as the boom storage detection lever 57 moves below the vehicle body 2. Thus, the flow of hydraulic oil between the two ports (C and D ports) of the valve body is controlled.

  In the leveling device 20 configured as described above, when the boom 5 is placed and stored in the boom receiver 9, the lower surface of the boom 5 contacts and presses the boom storage detection lever 57. Therefore, the valve spool of the shut-off valve 94 moves downward in the figure from the neutral state, the shut-off valve 94 is opened, and the C port and the D port are electrically connected.

In this case, even when operating the boom operating device 11 in the undulating down direction of the boom 5, the hydraulic fluid discharged from the pump P flows out from the B port of the relief control valve SV ₂ in the third oil passage 63, the fourth oil passage passes through the shut-off valve 94 which is opened to flow into the 64, to be discharged to the tank T back again to the relief control valve SV ₂ since the beginning of the first oil passage 61, the leveling cylinder rod side oil chamber 53b Does not flow into For this reason, the leveling cylinder 53 does not slightly shrink to compress the hydraulic oil in the bottom-side oil chamber 53a of the leveling cylinder, and the worktable 7 does not tilt, so that the leveling state does not change.

  On the other hand, when the boom 5 is floating from the boom receiver 9, the lower surface of the boom 5 is not in contact with the boom storage detection lever 57, and the shut-off valve 94 is in a neutral state (the state shown in FIG. 10). At this time, the C port and the D port of the shutoff valve 94 are both closed, and the fourth oil passage 64 is shut off.

Therefore, when operating the boom operating device 11 this time in the relief-down direction of the boom 5, the opening degree of the relief control valve SV ₂ in response to the operation signal from the boom operating unit 11 is adjusted, it is discharged from the hydraulic pump P operated oil flows from the B port of the relief control valve SV ₂ in the third oil passage 63, the leveling cylinder 53 by flowing through the rod-side oil chamber 53b of the leveling cylinder without flowing in the fourth oil passage 64 is contracted operation Is possible. When the leveling cylinder 53 contracts and receives hydraulic pressure from the bottom-side oil chamber 53a of the leveling cylinder 53, the up-down cylinder 52 contracts and the boom 5 falls down.

Third embodiment

  Further, here, the aerial work vehicle equipped with the leveling device according to the present invention is not necessarily limited to the aerial work vehicle as shown in FIG. Equipped with a bending / extension boom, only the bending / extension arm can be bent to move the worktable to a predetermined work position, and high-place work such as wiring work can be performed while running the vehicle at low speed without overhanging the jack device. It may be configured as such.

1 is an overall perspective view of an aerial work vehicle equipped with an aerial work vehicle leveling device according to the present invention. It is a block diagram for explaining operation of a 1st embodiment of the above-mentioned work platform. FIG. 2 is a hydraulic circuit diagram illustrating an example of a main hydraulic circuit configuration in the first embodiment of the leveling device. FIG. 3 is a cross-sectional view illustrating a structure of a third pilot check valve according to the first embodiment. It is a block diagram for explaining operation in a 2nd embodiment of the above-mentioned work platform. FIG. 9 is a hydraulic circuit diagram showing a main hydraulic circuit configuration in a second embodiment of the leveling device. FIG. 2 is a schematic configuration diagram of a boom device for describing a configuration of a leveling device. FIG. 9 is a hydraulic circuit diagram showing a main hydraulic circuit configuration in a conventional leveling device for an aerial work vehicle.

Explanation of reference numerals

Reference Signs List 1 aerial work platform 2 body 4 turning table 5 boom 5a base end boom (boom)
5b Intermediate boom (boom)
5c Tip boom (boom)
7 work table 9 boom receiver 20 leveling device 52 undulating cylinder 53 leveling cylinder 56 boom storage detection actuator (pilot pressure generating means)
56a Rod part (boom contact part)
57 Boom storage detection lever (boom contact part)
62 Second oil passage (communication oil passage)
63 Third oil path (leveling side oil path)
91 3rd pilot check valve (oil passage opening means)
94 Shut-off valve (oil passage opening means)
SV ₂ undulation control valve (control valve means)
P hydraulic pump (hydraulic supply means)

Claims (3)

A vehicle body capable of traveling, a swivel provided to be able to swing on the vehicle body, a boom pivotally connected to the swivel so as to be able to move up and down, and the boom is provided between the swivel and the boom. An up-and-down cylinder for raising and lowering the boom, a worktable attached to the tip end of the boom so as to be able to swing up and down, a boom receiver mounted on the vehicle body for placing and storing the boom, A leveling cylinder that swings the work table up and down in response to the up and down movement of the boom to hold the work table horizontally, an oil chamber on one side of the up and down cylinder and an oil chamber on one side of the leveling cylinder. A communication oil passage to be connected, control valve means for controlling supply / discharge of hydraulic oil to an oil chamber on the other side of the undulating cylinder and an oil chamber on the other side of the leveling cylinder, and supply hydraulic oil to the control valve means Hydraulic supply In the leveling device of aerial platforms constructed and means,
When the boom is provided on the boom receiver and is placed and stored in the boom receiver, the boom is pressed by the boom and can move in the falling direction of the boom.
Oil passage opening means for opening a leveling-side oil passage connecting the control valve means and the oil chamber on the other side of the leveling cylinder to a tank in response to movement of the boom contact portion. Work vehicle leveling device. Having a pilot pressure generating means that operates in accordance with the movement of the boom contact portion and outputs a pilot pressure,
The leveling device for an aerial work vehicle according to claim 1, wherein the oil passage opening means is configured to open the leveling-side oil passage in response to the pilot pressure. 2. The aerial work vehicle according to claim 1, wherein the oil passage opening unit is configured to operate in response to the movement of the boom contact portion to open the leveling-side oil passage. 3. Leveling device.

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