JP2013249197A - Hydraulic circuit of vehicle for high lift work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit of a vehicle for high lift work, capable of eliminating operation backlash of a work platform upon the start of the operation, even when the vehicle is stored while the work platform is positioned at a high position.SOLUTION: A hydraulic circuit for a vehicle for high lift work comprises: an opening and closing switching valve 43 opening and closing a first pump hydraulic passage L1; a first branch hydraulic passage L3 branched from the first pump hydraulic passage L1 and connected to a tank hydraulic passage L2; a first throttle 44 limiting a flow rate of working oil flowing through the first branch hydraulic passage L3; and a pressure setting check valve CV provided at a position at an oil tank T side rather than a connection point with the first branch hydraulic passage L3 in the tank hydraulic passage L2. The opening and closing switching valve 43 is constituted so as to be positioned at an opening position allowing the flow of the working oil by opening the first pump hydraulic passage L1 when a first hydraulic pump P1 is started.

Description

The present invention relates to a hydraulic circuit for an aerial work vehicle constructed by attaching a work table for boarding an operator to the tip of a boom provided on a traveling body.

In such an aerial work vehicle, the boom is freely provided on the traveling body so that it can be raised, retracted (or bent), turned, etc., and its operation control is performed on the work table or on the traveling body. It is comprised so that it can carry out with an apparatus. In addition, the workbench is rotatably attached to a vertical post that is provided at the tip of the boom and is always held almost vertically.
The work table is configured to be able to swing around a vertical post by hydraulically driving a swing motor (hydraulic motor) built in the work table (see, for example, Patent Document 1). The operator who has boarded the work table operates the operation device provided on the work table to perform not only hoisting, expanding and contracting and turning operations of the boom, but also swinging the work table as desired. The posture can be adjusted to make it easy to perform work at a high place.

Japanese Patent Laid-Open No. 2001-316088

An example of an aerial work platform with such a configuration is a self-propelled aerial work vehicle. This self-propelled aerial work vehicle raises the work platform due to storage (parking) space problems after work is completed. There is a case where the vehicle is stored in a state where it is located at a certain position. In such a case, the volume of the hydraulic oil contracts due to the cooling of the hydraulic oil, or the temperature of the supply oil passage connected to the hydraulic actuator at the upper part of the boom (temperature (
A space where no hydraulic oil is present in the supply oil passage may be formed by expansion due to a high temperature due to a change in the temperature. If there is a space in which such hydraulic oil does not exist, there is a risk that the working table may be loose at the start of operation due to this space.

The present invention has been made in view of such problems, and the vehicle is stored in a state where the work bench is located at a high position, and there is hydraulic oil in the supply oil passage that leads to the hydraulic actuator at the top of the boom. It is an object of the present invention to provide a hydraulic circuit for an aerial work vehicle that can eliminate the backlash of the work table at the start of operation even when there is a non-performing space.

In order to solve the above-described problems, a hydraulic circuit for an aerial work vehicle according to the present invention includes a traveling body, a boom that can be raised and lowered on the traveling body, and a work table that is attached to a tip portion of the boom. And a working device (e.g., a vertical post 32 in the embodiment) provided on an upper portion of the boom, and the working device that is supplied with hydraulic oil. A hydraulic actuator (for example, a swing motor 42 in the embodiment) for operating
A control valve (for example, swing motor control in the embodiment) that performs control to supply hydraulic oil supplied from a hydraulic supply source (for example, the first hydraulic pump P1 in the embodiment) provided in the traveling body to the hydraulic actuator. Valve 64) and operating means (for example, a swing operation lever 54 in the embodiment) for controlling the operation of the control valve, and the control valve is a P port that receives hydraulic oil supply, and discharges hydraulic oil. A T port to perform, and A and B ports for supplying and discharging hydraulic oil to and from the hydraulic actuator, and when the operating means is in a neutral position, the P port is closed and the A and B ports are connected to the T port. When the operating means is operated from the neutral position, the P port is set to the A port according to the operating direction. Configured to connect the T port to the other causes connected to one of the fine B port. A supply oil passage (for example, the first pump oil passage L1 in the embodiment) that connects the hydraulic supply source to the P port, and a discharge oil passage (for example, the tank oil passage in the embodiment) that connects the T port to an oil tank. L2), a supply oil passage opening / closing valve (for example, an opening / closing switching valve 43 in the embodiment) provided in the supply oil passage to open and close the supply oil passage, and the supply oil passage opening / closing valve in the supply oil passage The first branch oil passage (for example, the first branch oil passage L3 in the embodiment) branched from the position on the control valve side and connected to the exhaust oil passage, and the first branch oil passage provided in the first branch oil passage. Provided at a position closer to the oil tank than a connection point between the first throttle for restricting the flow rate of the hydraulic oil flowing through the branch oil passage and the first branch oil passage in the discharge oil passage, Is preset A pressure setting check valve that is opened when the cracking pressure is exceeded and permits the flow of hydraulic oil in a direction from the connection point side toward the oil tank side, and when the hydraulic supply source is started, the supply The oil passage opening and closing valve is configured to be located at an open position that opens the supply oil passage and allows the flow of hydraulic oil.

In the hydraulic circuit for an aerial work vehicle having the above-described configuration, the hydraulic supply source is a variable displacement type hydraulic pump (for example, the first hydraulic pump P1 ′ in the embodiment), and the control valve and the supply oil path open / close A second branch oil passage (for example, the second branch oil in the embodiment) branched from an oil passage between the valve and the first throttle and connected to a position closer to the oil tank than the pressure setting check valve in the discharge oil passage. Path L7) and the second branch oil path and the second branch
A second throttle restricting the flow rate of the hydraulic oil flowing through the branch oil passage; and provided at a position closer to the discharge oil passage than the second throttle in the second branch oil passage, and when the operating means is in a neutral position, When the second branch oil passage is opened and switched to a position allowing the flow of hydraulic oil, and the operation means is operated from the neutral position, the hydraulic oil in the direction from the second throttle side toward the discharge oil passage side An oil flow direction restriction switching valve that is switched to a position that inhibits the flow, and further using this oil pressure between the second throttle and the oil flow direction restriction switching valve in the second branch oil passage. A pump displacement control means (for example, the swash plate control actuator 45 and the discharge pressure control oil passage L8 in the embodiment) that controls the displacement of the hydraulic pump so that the pump discharge pressure corresponds to It may be. Alternatively, in place of the pump capacity control means, a pump discharge pressure corresponding to the oil pressure is obtained by using the oil pressure between the second throttle and the oil flow direction restriction switching valve in the second branch oil passage. A pump discharge pressure adjusting valve that adjusts the discharge pressure may be provided.

Further, in the hydraulic circuit for an aerial work vehicle having the above-described configuration, the working device is supported by a tip end portion of the boom so as to be swingable up and down, and is always kept substantially vertical regardless of the boom undulation angle. The work table may be attached to the vertical post so as to be swingable, and the hydraulic actuator may be configured to swing the work table around the vertical post. Alternatively, the working device includes a vertical post supported at the tip of the boom so as to be swingable up and down, the work table is attached to the vertical post, and the hydraulic actuator moves the vertical post to the boom undulation angle. However, it may be configured to swing up and down so as to be almost vertical at all times. Alternatively, the working device includes a bending / extending arm attached to the tip of the boom so as to swing up and down, the work table is attached to the tip of the bending / extending arm, and the hydraulic actuator attaches the bending / extending arm to the boom. You may comprise so that it may rock | fluctuate vertically with respect to.

According to the hydraulic circuit for an aerial work vehicle according to the present invention, a supply oil passage opening / closing valve for opening and closing the supply oil passage, a supply oil passage opening / closing valve, and a supply oil passage connecting the hydraulic supply source to the P port of the control valve A first branch oil passage branched from a position on the control valve side than the valve and connected to the discharge oil passage is provided, and a first throttle for restricting the flow rate of the working oil is provided in the first branch oil passage; The hydraulic oil flows in a direction from the connection point side toward the oil tank side at a position closer to the oil tank than the connection point with the first branch oil passage in the discharge oil passage, and the hydraulic pressure exceeds a preset cracking pressure. A pressure setting check valve is provided to allow for the case. When the hydraulic pressure supply source is started, the supply oil passage opening / closing valve is located at an open position that opens the supply oil passage and allows the flow of hydraulic oil. According to such a configuration, the vehicle is stored with the work bench positioned at a high position, and there is hydraulic oil in the supply oil path due to contraction of the hydraulic oil due to temperature change or expansion of the supply oil path. Even when there is a space not to be closed, when the hydraulic pressure supply source is started, the hydraulic oil discharged from the hydraulic pressure supply source is in the open position, the supply oil path opening / closing valve, the first branch oil path, and the first The hydraulic oil corresponding to the cracking pressure of the pressure setting check valve is supplied to the oil passage that connects the hydraulic actuator and the control valve via the discharge oil passage and the control valve. The space that did not exist is filled with hydraulic oil. For this reason, even when the work table is positioned at a high position and the vehicle is stored, the operation play of the work table at the start of operation can be eliminated.

1 is a hydraulic circuit diagram showing a first embodiment of a hydraulic circuit according to the present invention. It is a side view of an aerial work vehicle provided with a hydraulic circuit according to the present invention. It is a block diagram which shows the control system of the said aerial work vehicle. It is a hydraulic circuit diagram which shows 2nd Embodiment of the hydraulic circuit which concerns on this invention. It is a hydraulic circuit diagram which shows the modification of the hydraulic circuit which concerns on the said 2nd Embodiment. It is a hydraulic circuit diagram which shows another modification of the hydraulic circuit which concerns on the said 2nd Embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows an aerial work vehicle 1 equipped with a hydraulic circuit according to the present invention. The aerial work vehicle 1 includes a traveling body 10 having a pair of left and right front wheels 11 and a rear wheel 12, a revolving body 20 provided on the traveling body 10, and a revolving body 2
A boom 30 attached to the upper portion of 0 by a foot pin 21 so as to be swingable up and down, and a boom 3
And a work board 40 for boarding an operator, which is attached to the front end portion of zero.

In the traveling body 10, left and right rear wheels 12 are connected to a rotating shaft of a traveling motor 14 (hydraulic motor) provided in the traveling body 10, and the hydraulic power supply to the traveling motor 14 is controlled to control the left and right rear wheels. By controlling the rotation of the wheel 12, the traveling body 10 can be started, stopped, and adjusted for speed during traveling. The left and right front wheels 11 are connected to a steering cylinder 15 (hydraulic cylinder) provided in the traveling body 10 via a link mechanism and a rod (not shown), and the steering cylinder 15 is hydraulically driven to drive the left and right front wheels. 11, the traveling body 10 can be steered by changing the direction of 11.

The revolving unit 20 is attached to the traveling unit 10 so as to be rotatable 360 degrees around a vertical axis, and the revolving unit 20 is hydraulically driven by driving a revolving motor 13 (hydraulic motor) provided in the traveling unit 10. It is comprised so that turning operation | movement can be carried out within a horizontal surface. The boom 30 has a plurality of boom members assembled in a nested manner. The boom 30 is moved in the longitudinal direction by supplying pressure oil to an extendable cylinder 31 (hydraulic cylinder) provided in the boom 30 and driving a piston. It is configured so that it can be expanded and contracted. Further, a hoisting cylinder 22 (hydraulic cylinder) is provided between the swing body 20 and the boom 30, and the hoisting operation can be performed in the upper and lower surfaces by hydraulically driving the hoisting cylinder 22. It has become.

A vertical post 32 is provided at the tip of the boom 30. The vertical post 32 is supported at the tip of the boom 30 so as to be swingable up and down, and is configured so that a substantially vertical posture is always maintained by a leveling device (not shown) regardless of the undulation angle of the boom 30. The work table 40 is rotatably attached to the vertical post 32 via a work table holding portion (bracket) 41, and a swing motor 41 (hydraulic motor) provided in the work table holding portion 41 is hydraulically operated. By being driven, the work table 40 can be swung around the vertical post 32.

An operation box 50 is provided on the work table 40. As shown in FIG. 3, the operation box 50 includes a raising / lowering operation lever 51 for performing the raising / lowering operation of the boom 30, an expansion / contraction operation lever 52 for performing the expansion / contraction operation of the boom 30, and the boom 30 (revolving body 20). A swing operation lever 53 for performing the swing operation of the work table 40, and a swing operation lever 5 for performing the swing operation of the work table 40.
4 are provided. Here, if the hoisting operation lever 51 is tilted in the front-rear direction, an operation command signal for extending and retracting the hoisting cylinder 22 is output accordingly, and the telescopic operation lever 52 is operated.
Is tilted in the front-rear direction, an operation command signal for extending and retracting the telescopic cylinder 31 is output accordingly. Further, when the turning operation lever 53 is tilted in the left-right direction, an operation command signal for rotating the turning motor 13 in the forward / reverse direction is output accordingly, and the swing operation lever 5
When the 4 is tilted in the left / right direction, an operation command signal for rotating the swing motor 42 in the forward / reverse direction is output accordingly. Each of these operation command signals is input to the work table movement control unit 71 of the controller 70.

The operation box 50 includes a traveling operation lever 55 for performing a traveling operation (starting, stopping, and speed adjusting operation during traveling) of the traveling body 10 and a steering operation lever 56 for performing a steering operation of the traveling body 10. And are provided. Here, when the traveling operation lever 55 is tilted in the front-rear direction, an operation command signal for rotating the traveling motor 14 in the forward / reverse direction is output accordingly, and when the steering operation lever 56 is tilted in the left-right direction, the operation command signal is output accordingly. Steering cylinder 1
An operation command signal for operating 5 is output. These operation signals are input to the travel control unit 72 of the controller 70. Furthermore, the operation box 50 includes
An engine start switch 57 for starting the engine E provided in the traveling body 10;
An engine stop switch 58 for stopping the engine E is provided, and operation signals of these switches 57 and 58 are input to the engine control unit 73 of the controller 70.

The controller 70 includes a work table movement control unit 71, a travel control unit 72, an engine control unit 73,
A position calculation unit 74 and a storage unit 75 are included. The engine control unit 73 starts the engine E in response to the engine start switch 57 being operated, and stops the engine E in response to the engine stop switch 58 being operated. When the engine E is started, the first and second hydraulic pumps P1, P2 are driven by the engine E, and hydraulic oil is discharged from both the hydraulic pumps P1, P2. The hydraulic oil discharged from the first hydraulic pump P1 into the first pump oil passage L1 passes through the hoisting cylinder control valve 61, the telescopic cylinder control valve 62, the swing motor control valve 63, and the swing motor control valve 64. 22, telescopic cylinder 31,
It is supplied to the turning motor 13 and the swing motor 42, respectively. 2nd hydraulic pump P2 to 2nd
The hydraulic oil discharged into the pump oil passage L11 is supplied to the travel motor 14 and the steering cylinder 15 via the travel motor control valve 65 and the steering cylinder control valve 66, respectively.

The work table movement control unit 71 includes operation levers 51 to 54 by the worker M who has boarded the work table 40.
The control valves 61 to 64 are electromagnetically driven in accordance with the respective operation command signals output by the operation of the above, whereby the undulation cylinder 22, the telescopic cylinder 31, the swing motor 13 and the swing motor 42 are in the first state. The hydraulic oil from the hydraulic pump P1 is supplied, and each actuator operates according to the operation of the corresponding operation lever. The traveling control unit 72 electromagnetically drives the control valves 65 and 66 in accordance with each operation command signal output by the operation of the operation levers 55 and 56 by the worker M, whereby the traveling motor 14 and the steering are controlled. The cylinder 15 is supplied with hydraulic oil from the second hydraulic pump P2, and the motors 14 and 15 operate according to the operation of the corresponding operation lever. Therefore, the worker M who has boarded the work table 40 operates the boom 30 by operating the operation levers 51 to 54 of the operation box 50.
Can be operated at a desired height by moving up and down, extending and contracting, turning, or swinging the work table 40, and the travel operation lever 55 and the steering operation lever 56 can be operated.
It is possible to freely travel and move the traveling body 10 by the above operation.

Further, as shown in FIG. 2, a boom 30 is provided with a undulation angle detector 81 that detects the undulation angle of the boom 30 and a length detector 82 that detects the length of the boom 30. 1
A turning angle detector 83 for detecting a turning angle of the boom 30 (the turning body 20) with respect to the traveling body 10 is provided in the vicinity of the turning motor 13 in 0. These detectors 81-83
Information on the undulation angle, length, and turning angle of the boom 30 detected by the above is input to the position calculation unit 74 of the controller 70 (see FIG. 3).

The position calculation unit 74 calculates the position of the work table 40 with respect to the traveling body 10 based on the input information on the undulation angle, length, and turning angle of the boom 30. Storage unit 7 of controller 70
5 stores in advance data on the work table 40 allowable movement area, that is, the movement area of the work table 40 in which the work table 40 can be moved within a range in which the traveling body 10 does not fall. The work table movement control unit 71 compares the position of the work table 40 calculated by the position calculation unit 74 with the data of the allowable movement area stored in the storage unit 75 and causes the work table 40 to deviate from the allowable movement area. Such operation command signals from the respective operation levers are invalidated. For this reason, the turning operation of the revolving body 20 and the raising and lowering and extending / retracting operations of the boom 30 are not performed so that the work table 40 deviates from the allowable movement region. The operation can be performed.

Next, a hydraulic circuit according to the present invention provided in the aerial work vehicle 1 will be described with reference to FIG. As described above, the hydraulic oil discharged from the first hydraulic pump P1 into the first pump oil passage L1 reaches the swing motor control valve 64 via the open / close switching valve 43 (not shown in FIG. 3). The swing motor 42 is supplied to the swing motor 42 via the swing motor control valve 64. Here, the open / close switching valve 43 is provided below the boom 30, that is, on the traveling body 10 side, and the swing motor control valve 64 is above the boom 30, that is, the work table 40.
On the side.

The swing motor control valve 64 has a P port (pump port) connected to the first pump oil passage L1, a T port (tank port) connected to the tank oil passage L2, and A and B ports connected to the swing motor 42. When the spool is in the neutral position (position shown in FIG. 1), the P port is blocked and the A and B ports are connected to the T port. When the spool is in the switching position moved to the right, the P port is An ABT connection type in which the A port is connected to the A port, the B port is connected to the T port, and the P port is connected to the B port and the A port is connected to the T port when the spool is in the left-shifted position. This is an electromagnetically driven three-position switching valve.

When the spool is in the neutral position (position shown in FIG. 1), the open / close switching valve 43 closes the first pump oil passage L1 to cut off the flow of hydraulic oil, and is positioned at the switching position where the spool moves to the left. In this case, the electromagnetically driven two-position switching valve opens the first pump oil passage L1 to allow the flow of hydraulic oil. When the first hydraulic pump P1 is driven by the engine E, the opening / closing switching valve 43 is electromagnetically driven by the work table movement control unit 71 and is positioned at a switching position where the spool is moved to the left.

Pilot check valves PCV1 and PCV2 are provided in the two oil passages L5 and L6 that connect the swing motor control valve 64 and the swing motor 42, respectively. These pilot check valves PCV1 and PCV2 constitute a double pilot check valve DPCV that receives the pilot pressure from the counterpart oil passage (L5 or L6) and opens its own oil passage. These pilot check valves PCV1, PCV2 are provided with a swing control valve 64.
The hydraulic oil flow in the direction from the side toward the swing motor 42 is allowed when the hydraulic pressure exceeds a preset cracking pressure, and the swing control valve 6 from the swing motor 42 side is allowed.
The flow of hydraulic oil in the direction toward the 4 side is prohibited. The pilot check valves PCV1 and PCV2 close their own oil passage when the other oil passage is not acting, so when the oil passage located closer to the oil tank T than the double pilot check valve DPCV is damaged, The swing motor 42 is fixed (hydraulic lock) to the posture at that time.

A first branch oil passage L3 is provided which branches from the position on the swing motor control valve 64 side of the opening / closing switching valve 43 in the first pump oil passage L1 and is connected to the tank oil passage L2. The first branch oil passage L3 is provided with a first throttle 44 that restricts the flow rate of the hydraulic oil flowing through the first branch oil passage L3.

A pressure setting check valve CV is provided at a position closer to the oil tank T than the connection point S with the first branch oil passage L3 in the tank oil passage L2. This pressure setting check valve CV is opened when the hydraulic pressure on the connection point S side exceeds a preset (own) cracking pressure,
While allowing the flow of hydraulic oil in the direction from the connection point S side to the oil tank T side,
The flow of hydraulic oil in the direction from the side toward the connection point S is prohibited. Here, the cracking pressure of the pressure setting check valve CV is equal to the double pilot check valve DP.
It is adjusted to be larger than the cracking pressure of the two pilot check valves PCV1, PCV2 constituting the CV.

There is a relief oil passage L4 that branches from a position on the first hydraulic pump P1 side relative to the opening / closing switching valve 43 in the first pump oil passage L1 and that leads to a position on the oil tank T side relative to the pressure setting check valve CV in the tank oil passage L2. Is provided. The relief oil passage L4 has a relief valve that opens the relief oil passage L4 to the oil tank T via the tank oil passage L2 when the hydraulic pressure in the first pump oil passage L1 reaches a predetermined pressure (relief set pressure). R is provided.

In the hydraulic circuit having such a configuration, when the engine E is started and the first hydraulic pump P1 is driven by the engine E, the switching of the spool of the open / close switching valve 43 is moved to the left from the neutral position by the worktable controller 71. Is switched to the position, the first pump oil passage L1 is opened to allow the flow of hydraulic oil, and the hydraulic oil discharged from the first hydraulic pump P1 to the first pump oil passage L1 is supplied to the swing motor control valve 64. It reaches. Here, when the first hydraulic pump P1 is started from the stopped state and the open / close switching valve 43 is switched from the neutral position to the switched position, the spool of the swing motor control valve 64 is in the neutral position. The P port of the swing motor control valve 64 is blocked and the A, B, and T ports are in communication. Until the first hydraulic pump P1 is started from the stop state and a predetermined time (a time until a space where no hydraulic oil, which will be described later exists) is filled with the hydraulic oil, the neck is operated by the operation of the swing operation lever 54. Even when an operation command signal for electromagnetically driving the swing motor control valve 64 is output, the worktable control unit 71 disables the operation command signal and holds the swing motor control valve 64 in the neutral position. The swing motor control valve 64 is configured to be neutral when not operated. Generally, since the swing operation is rarely performed immediately after the engine is started, this control may not be performed.

Thus, in the state where the spool of the open / close switching valve 43 is switched from the neutral position to the switching position moved to the left and the spool of the swing motor control valve 64 is positioned at the neutral position, the first
The hydraulic fluid discharged from the hydraulic pump P1 to the first pump oil passage L1 reaches the tank oil passage L2 via the first throttle 44 from the first branch oil passage L3. Here, since the pressure setting check valve CV is provided at a position on the oil tank T side of the connection point S with the first branch oil passage L3 in the tank oil passage L2, the cracking pressure of the pressure setting check valve CV is set. The corresponding hydraulic pressure is connected to the swing motor 42 from the tank oil path L2 through the swing motor control valve 64, and the oil paths L5, L6.
To be supplied. Therefore, the work platform 1 is stored for a long time (for example, overnight) with the hoisting cylinder 22 extended so that the boom 30 is at a high hoisting angle and the work table 40 is positioned at a high position. The hydraulic oil in the passages L5 and L6 is cooled, so that the volume of the hydraulic oil shrinks or the oil passage L
5, L6 becomes high temperature due to temperature (air temperature) change and expands, so that the oil passage L5
Even if there is a space where no hydraulic oil exists in L6, the hydraulic oil is supplied to the oil passages L5 and L6 as described above when the first hydraulic pump P1 is started. The space where no oil was present is filled with hydraulic oil. For this reason, even when the work table 40 is located at a high position and the vehicle is stored, the operation play of the work table 40 at the start of operation can be eliminated.

When the spool of the swing motor control valve 64 is switched from the neutral position to the right-hand or left-hand switching position according to the operation of the swing operation lever 54, the first hydraulic pump P1 The hydraulic oil discharged to the first pump oil passage L1 drives the swing motor 42 via the swing motor control valve 64, and then the swing motor control valve 6
4 returns to the oil tank T via the tank oil passage L2. Here, since the first throttle 44 for restricting the flow rate of the hydraulic oil is provided in the first branch oil passage L3, most of the hydraulic oil discharged from the first hydraulic pump P1 is swung to the motor control valve 64. , And can be supplied to the swing motor 42. Thus, the hydraulic oil discharged from the first hydraulic pump P1 is supplied to the swing motor 42 via the ABT connection type swing motor control valve 64. By switching the spool from the neutral position to the switching position moved to the right or left, the work table 40 can be swung in either the forward or reverse direction (left or right).

Next, a second embodiment of the hydraulic circuit according to the present invention will be described with reference to FIG. The aerial work vehicle to which the hydraulic circuit shown here is applied is the same as the aerial work vehicle 1 described above, and the description thereof is omitted. In addition, the same components as those in the above hydraulic circuit are denoted by the same reference numerals, and the description thereof is omitted. In the hydraulic circuit according to the second embodiment, the first hydraulic pump P1 is a swash plate type variable displacement type hydraulic pump, and the tilt angle of the swash plate is controlled by a swash plate control actuator 45 so that the pump displacement ( The discharge amount is variably controlled. The hydraulic fluid discharged from the first hydraulic pump P1 ′ into the first pump oil passage L1 reaches the swing motor control valve 64 via the open / close switching valve 43, as in the hydraulic circuit described above. It is supplied to the swing motor 42 via the motor control valve 64.

A second branch oil passage branched from the oil passage between the swing motor control valve 64, the open / close switching valve 43 and the first throttle 44 and connected to a position closer to the oil tank T than the pressure setting check valve CV in the tank oil passage L2. L7 is provided. In FIG. 4, the second branch oil passage L7 is branched from the first branch oil passage L3, but may be branched from the first pump oil passage L1. In this second branch oil passage L7, a second throttle 4 that restricts the flow rate of hydraulic oil flowing through the second branch oil passage L7.
6 is provided. Here, the second throttle 46 so that the flow rate flowing through the second throttle 46 to the tank oil passage L2 is smaller than the flow rate flowing through the first throttle 44 into the tank oil passage L2.
Has been adjusted.

An oil flow direction restriction switching valve 47 is provided at a position closer to the tank oil passage L2 than the second throttle 46 in the second branch oil passage L7. The oil flow direction restriction switching valve 47 opens the second branch oil passage L7 when the spool is in the neutral position (position shown in FIG. 4) and allows the hydraulic oil to flow, and the spool moves up. This is an electromagnetically driven two-position switching valve that prohibits the flow of hydraulic oil in the direction from the second throttle 46 side toward the tank oil passage L2 when it is in the switching position. The oil flow direction regulation switching valve 47 is moved by the work table movement control unit 71 by the swing motor control valve 64.
And when the spool of the swing motor control valve 64 is in the neutral position, the spool of the oil flow direction regulation switching valve 47 is in the neutral position, and the swing motor When the spool of the control valve 64 is positioned at the switching position where the spool is moved to the right or left, the spool of the oil flow direction regulation switching valve 47 is positioned at the switching position where the spool is moved up.

A discharge pressure control oil path L8 is provided that branches from a position between the second throttle 46 and the oil flow direction restriction switching valve 47 in the second branch oil path L7 and guides the hydraulic pressure to the swash plate control actuator 45. The swash plate control actuator 45 uses the hydraulic pressure guided by the discharge pressure control oil passage L8 to provide a pump discharge pressure corresponding to this hydraulic pressure (added with a predetermined set pressure). The swash plate tilt angle (pump capacity) is controlled to control the discharge amount of the first hydraulic pump P1 '(load sensing control is performed).

In the hydraulic circuit having such a configuration, when the engine E is started and the first hydraulic pump P1 ′ is driven by the engine E, the spool of the open / close switching valve 43 is moved to the left from the neutral position by the work table controller 71. When switched to the switching position, the first pump oil passage L1 is opened to allow the flow of hydraulic oil, and the hydraulic oil discharged from the first hydraulic pump P1 ′ to the first pump oil passage L1 is the swing motor control valve. 64. Here, when the first hydraulic pump P1 ′ is started from the stopped state and the open / close switching valve 43 is switched from the neutral position to the switching position moved to the left, the spool of the swing motor control valve 64 is positioned at the neutral position. The P port of the swing motor control valve 64 is blocked and the A, B, and T ports are in communication. At this time, the spool of the oil flow direction restriction switching valve 47 is located at the neutral position, and the second branch oil passage L7 is opened to allow the flow of hydraulic oil.

Thus, in the state where the spool of the open / close switching valve 43 is switched from the neutral position to the switching position moved to the left and the spool of the swing motor control valve 64 is positioned at the neutral position, the first
The hydraulic oil discharged from the hydraulic pump P1 ′ to the first pump oil passage L1 reaches the tank oil passage L2 through the first throttle 44 from the first branch oil passage L3. Here, the first throttle 44 is provided in the second branch oil passage L7.
Since the second throttle 46 that restricts the flow rate to be less than that of the first hydraulic pump P1 ′ is provided.
Most of the hydraulic oil discharged from the tank passes through the first throttle 44 from the first branch oil passage L3 and reaches the tank oil passage L.
2 flows. And since the pressure setting check valve CV is provided at a position closer to the oil tank T than the connection point S with the first branch oil passage L3 in the tank oil passage L2, according to the cracking pressure of the pressure setting check valve CV. The hydraulic pressure is supplied from the tank oil passage L2 to the oil passages L5 and L6 connected to the swing motor 42 through the swing motor control valve 64. Accordingly, the work vehicle 1 is stored for a long time (for example, overnight) with the work table 40 positioned at a high position, and the hydraulic oil in the oil passages L5 and L6 cools down to reduce the volume of the hydraulic oil. Shrink or oil path L5, L6
The first hydraulic pump P1 ′ is started even when there is a space in which no hydraulic oil exists in the oil passages L5 and L6 due to the expansion due to the temperature (air temperature) changing to a high temperature. Occasionally, hydraulic fluid is supplied to the oil passages L5 and L6 as described above, so that the space where hydraulic fluid does not exist is filled with hydraulic fluid. For this reason, even when the work table 40 is located at a high position and the vehicle is stored, the operation play of the work table 40 at the start of operation can be eliminated.

Then, in response to the operation of the swing operation lever 54, the worktable control unit 71 switches the spool of the swing motor control valve 64 from the neutral position to the switching position in which the spool moves to the right or left, and in conjunction with this, the oil flow direction When the spool of the restriction switching valve 47 is switched to the switching position in which the spool is moved upward, the hydraulic oil discharged from the first hydraulic pump P1 ′ to the first pump oil passage L1 passes through the head motor control valve 64 to the neck. After driving the swing motor 42, the swing motor control valve 64 returns to the oil tank T through the tank oil passage L2. Here, since the first throttle 44 is provided in the first branch oil passage L3 and the second throttle is provided in the second branch oil passage L7, the hydraulic oil discharged from the first hydraulic pump P1 ' The majority can be supplied to the swing motor 42 via the swing motor control valve 64. At this time, the discharge amount of the first hydraulic pump P 1 ′ is controlled by the swash plate control actuator 45 so as to be a discharge amount corresponding to the load pressure of the swing motor 42. The hydraulic fluid discharged from the first hydraulic pump P1 ′ in this way is supplied to the swing motor 42 via the ABT connection type swing motor control valve 64. The swing motor control valve 64 The working table 40 can be swung in either the forward or reverse direction (left and right) by switching the spool from the neutral position to the switching position moved to the right or left.

FIG. 5 is a modification of the hydraulic circuit according to the second embodiment described above. The first hydraulic pump P1 is a fixed displacement type hydraulic pump, and relief oil is used instead of the relief valve R and the swash plate control actuator 45 described above. A pump discharge pressure adjusting valve 48 is provided in the path L4. A discharge pressure control oil passage L8 ′ branched from a position between the second throttle 46 and the oil flow direction restriction switching valve 47 in the second branch oil passage L7 is provided so as to guide the hydraulic pressure to the pump discharge pressure adjustment valve 48. Yes. The pump discharge pressure adjusting valve 48 uses the oil pressure guided by the discharge pressure control oil passage L8 ′ to set the relief oil passage L4 to the tank oil so that this oil pressure (with a predetermined set pressure added) becomes the pump discharge pressure. The discharge amount of the first hydraulic pump P1 is controlled by opening to the oil tank T via the path L2 (load sensing control is performed). Even in the hydraulic circuit having such a configuration, the same effect as in the above-described embodiment can be obtained.

FIG. 6 shows another modification of the hydraulic circuit according to the second embodiment described above, in which the swinging motor 42 and the undulating cylinder 22 are interlocked using the hydraulic oil discharged from the first hydraulic pump P1 ′. is there. The hydraulic oil discharged from the first hydraulic pump P1 into the first pump oil passage L1 is
The undulation is made via the supply amount control valve 67 and the undulation cylinder control valve 61 via the branch pump oil passage L1 ′ branched from the position on the first hydraulic pump P1 ′ side with respect to the opening / closing switching valve 43 in the first pump oil passage L1. The cylinder 22 is supplied.

The hoisting cylinder control valve 61 includes a P port (pump port) connected to the branch pump oil passage L1 ', a T port (tank port) connected to the branch tank oil passage L2', and the hoisting cylinder 22.
A and B ports are connected to each other. When the spool is in the neutral position (position shown in FIG. 6), all the ports are blocked. When the spool is in the switching position moved to the right, the P port is Electromagnetic three-position switching that connects the A port and the B port to the T port, and connects the P port to the B port and connects the A port to the T port when the spool is in the left-shifted position. It is a valve. The branch tank oil passage L2 ′ is branched from a position closer to the oil tank T than the connection point with the second branch oil passage L7 in the tank oil passage L2, and is connected to the T port of the undulation cylinder control valve 61. .

The supply amount control valve 67 prohibits the flow of hydraulic oil in the direction from the first hydraulic pump P1 ′ side to the hoisting cylinder control valve 61 side when the spool is in the neutral position (position shown in FIG. 6). This is an electromagnetically driven proportional flow rate control valve that proportionally controls the flow rate of hydraulic oil when the spool is located at the switching position where it is moved to the left. The supply amount control valve 67 is provided with the hoisting operation lever 5.
1 is electromagnetically driven together with the hoisting cylinder control valve 61 by the work table movement control unit 71 according to the operation of 1.

The undulating cylinder control valve 6 rather than the supply amount control valve 67 in the branch pump oil passage L1 ′.
1st branch oil path L3 which branches from the position of 1 side rather than the 2nd throttle 46 in the 2nd branch oil path L7
A third branch oil passage L9 connected to the position on the side is provided. This third branch oil passage L9 has a check valve CV4 that allows the flow of hydraulic oil in the direction from the branch pump oil passage L1 ′ to the second branch oil passage L7 and prohibits the reverse flow of hydraulic oil. Is provided.

A double pilot check valve DPC having the above-described pilot check valves PCV1 and PCV2 in the two oil passages connecting the hoisting cylinder control valve 61 and the hoisting cylinder 22
V is provided. When the oil path located closer to the oil tank T than the check valve DPCV is damaged by the double pilot check valve DPCV, the hoisting cylinder 2
2 is fixed to the posture at that time (hydraulic lock).

The first hydraulic pump P1 'discharges to the open / close switching valve 43 (swing motor 42) at a position between the branch point of the open / close switching valve 43 and the branch pump oil passage L1' in the first pump oil path L1. A third throttle 49 is provided for limiting the flow rate of the flowing hydraulic oil. First branch oil passage L
3 at a position closer to the first pump oil passage L1 than the branch point with the second branch oil passage L7 in the direction of operation from the first pump oil passage L1 to the branch point with the second branch oil passage L7. Allow oil flow,
A check valve CV3 that prohibits the flow of hydraulic oil in the reverse direction is provided.

In the hydraulic circuit having such a configuration, when the engine E is started and the first hydraulic pump P1 ′ is driven by the engine E, the spool of the open / close switching valve 43 is moved to the left from the neutral position by the work table controller 71. When switched to the switching position, the first pump oil passage L1 is opened to allow the flow of hydraulic oil, and the hydraulic oil discharged from the first hydraulic pump P1 ′ to the first pump oil passage L1 is the swing motor control valve. 64. Here, when the first hydraulic pump P1 ′ is started from the stopped state and the open / close switching valve 43 is switched from the neutral position to the switched position, the spool of the swing motor control valve 64 is positioned at the neutral position. The P port of the swing motor control valve 64 is blocked and the A, B, and T ports are in communication. At this time, the spool of the oil flow direction restriction switching valve 47 is located at the neutral position, and the second branch oil passage L7 is opened to allow the flow of hydraulic oil,
The spool of the supply amount control valve 67 is located at the neutral position, and the flow of hydraulic oil in the direction from the first hydraulic pump P1 'side toward the hoisting cylinder control valve 61 side is prohibited.

Thus, in the state where the spool of the open / close switching valve 43 is switched from the neutral position to the switching position moved to the left and the spool of the swing motor control valve 64 is positioned at the neutral position, the first
The hydraulic oil discharged from the hydraulic pump P1 ′ to the first pump oil passage L1 reaches the tank oil passage L2 through the first throttle 44 from the first branch oil passage L3. And since the pressure setting check valve CV is provided at a position closer to the oil tank T than the connection point S with the first branch oil passage L3 in the tank oil passage L2, according to the cracking pressure of the pressure setting check valve CV. The oil paths L5, L connected to the swing motor 42 through the swing motor control valve 64 from the tank oil path L2.
6 is supplied. Therefore, the same effect as that of the above-described embodiment can be obtained.

Then, in response to the operation of the swing operation lever 54, the worktable control unit 71 switches the spool of the swing motor control valve 64 from the neutral position to the switching position in which the spool moves to the right or left, and in conjunction with this, the oil flow direction When the spool of the restriction switching valve 47 is switched to the switching position in which the spool is moved upward, the hydraulic oil discharged from the first hydraulic pump P1 ′ to the first pump oil passage L1 passes through the head motor control valve 64 to the neck. After driving the swing motor 42, the swing motor control valve 64 returns to the oil tank T through the tank oil passage L2. Thus, the first hydraulic pump P1 ′
The hydraulic oil discharged from the pump is supplied to the swing motor 42 via the ABT connection type swing motor control valve 64, and the spool of the swing motor control valve 64 is moved rightward from the neutral position. Switching the work table 40 forward and backward by switching to the switching position moved to the left (
Left and right) The head can be swung in either direction.

Further, in response to the operation of the hoisting operation lever 51, the worktable control unit 71 switches the spool of the hoisting cylinder control valve 64 from the neutral position to the switching position in which the spool moves to the right or left, and in conjunction with this, the supply amount control valve 67 Is driven from the neutral position, the hydraulic oil discharged from the first hydraulic pump P1 ′ to the first pump oil passage L1 is supplied from the branch pump oil passage L1 ′ to the supply amount control valve 67 and the undulating cylinder control valve 61. After driving the hoisting cylinder 22 through the hoisting cylinder control valve 61, the branch tank oil passage L2 'and the tank oil passage L are driven.
2 and return to the oil tank T. Here, since the branch tank oil passage L2 'is connected to the oil tank T side from the pressure setting check valve CV in the tank oil passage L2, the hoisting cylinder 22
Since the cracking pressure of the pressure setting check valve CV does not act on the hydraulic oil returning from the oil tank T to the oil tank T, the pressure loss in the undulation operation can be reduced. Thus, the hydraulic oil discharged from the first hydraulic pump P1 ′ is supplied to the hoisting cylinder 22 via the supply amount control valve 67 and the hoisting cylinder control valve 61, and the spool of the hoisting cylinder control valve 61 is supplied. Is switched from the neutral position to the switching position moved to the right or left, and the spool of the supply amount control valve 67 is driven from the neutral position to move the boom 3.
0 can be raised and lowered with respect to the traveling body 10.

Although the embodiment according to the present invention has been described so far, the scope of the present invention is not limited to that shown in the above-described embodiment. For example, in the above-described embodiment, the case where the hydraulic circuit according to the present invention is applied to the swing motor 42 has been described. However, the vertical post 32 is moved up and down so that the vertical post 32 is always in a substantially vertical position regardless of the undulation angle of the boom 30. The hydraulic circuit according to the present invention may be applied to a leveling cylinder to be moved (leveling cylinder control valve, leveling adjustment operation lever). Alternatively, the boom 30 includes a bending / extending arm provided at the tip of the boom 30 so as to freely swing up and down (bend / extend) within the undulation surface, and the work table 40 is attached to the tip of the bending / extending arm. A bending / extending cylinder that swings up and down (bending / extending operation) with respect to the boom 30
The hydraulic circuit according to the present invention may be applied to a bending / extending cylinder control valve and a bending / extending operation lever.

In the above-described embodiment, the swing motor control valve 64, the open / close switching valve 43, and the oil flow direction regulation switching valve 47 are configured to electromagnetically drive the spool, but this is an example, and hydraulic drive or manual operation is possible. May be configured to be mechanically driven. Further, the first hydraulic pump P1 (P1 ′) is driven by the engine E, but may be driven by an electric motor using battery power.

The hydraulic actuator that swings the work table 40 around the vertical post 32 is:
In the above-described embodiment, the angle limit type actuator is used, but this may be a rotary hydraulic motor or a hydraulic cylinder. Further, although the swing motor control valve 64 has been described as being located above the boom 30 (that is, the work table 40 side) in the above-described embodiment, it is located below the boom 30 (that is, the traveling body 10 side). You may comprise. Also,
Although the first branch oil passage L3, the first throttle 44, and the pressure setting check valve CV have been described as being located below the boom 30 (the traveling body 10 side) in the above-described embodiment, the boom 30
You may comprise so that it may be located above (work bench 40 side). Further, in the above-described embodiment, the double pilot check valve DPCV having the pilot check valves PCV1 and PCV2 is provided in the two oil passages L5 and L6 that connect the swing motor control valve 64 and the swing motor 42. However, this double pilot check valve is not necessarily provided.

In the above-described embodiment shown in FIG. 6, the branch tank oil passage L2 ′ is connected to a position closer to the oil tank T than the pressure setting check valve CV in the tank oil passage L2, but the pressure setting check valve CV Alternatively, it may be connected to a position closer to the swing motor control valve 64 side.
In addition, similarly to the swing motor control valve 64, the undulating cylinder control valve 61 is used.
Is configured as an ABT connection type switching valve in which the A, B, and T ports communicate with each other in the neutral position, whereby the backlash of the hoisting cylinder 22 can be prevented, and such a hydraulic circuit configuration may be employed. Moreover, it is good also as a hydraulic circuit structure which can prevent the backlash of not only the raising / lowering cylinder 22 but another hydraulic actuator similarly to this. However, since no load is applied to the oscillating motor 42 that is stopped, an operation rattle is likely to occur, but there are many other hydraulic actuators such as a hoisting cylinder that are subjected to a load even when stopped. With a simple hydraulic actuator, it is difficult for play to occur.

In the above-described embodiment, the self-propelled aerial work vehicle 1 is described as an aerial work vehicle including the hydraulic circuit according to the present invention. However, the hydraulic circuit according to the present invention uses a truck vehicle as a base of a traveling body. It can also be applied to an aerial work vehicle.

DESCRIPTION OF SYMBOLS 1 Aerial work vehicle 10 Traveling body 30 Boom 32 Vertical post 40 Work table 42 Swing motor (swing hydraulic actuator)
43 Open / close switching valve (supply oil passage open / close valve)
44 First diaphragm 45 Swash plate control actuator (pump capacity control means)
46 Second throttle 47 Oil flow direction restriction switching valve 48 Pump discharge pressure adjusting valve 54 Swing operation lever (swing operation means)
64 Swing motor control valve (swing control valve)
L1 First pump oil passage (supply oil passage)
L2 Tank oil passage (discharge oil passage)
L3 First branch oil passage L7 Second branch oil passage L8 Discharge pressure control oil passage (pump capacity control means)
P1, P1 '1st hydraulic pump (hydraulic supply source)
CV Pressure setting check valve T Oil tank

Claims (6)

A hydraulic circuit for an aerial work vehicle comprising: a traveling body; a boom provided on the traveling body so as to freely move up and down; and a workbench attached to a tip of the boom.
A working device provided at the top of the boom;
A hydraulic actuator for operating the working device in response to supply of hydraulic oil;
A control valve that performs control to supply hydraulic oil supplied from a hydraulic supply source provided in the traveling body to the hydraulic actuator;
Operating means for performing operation control of the control valve,
The control valve has a P port for receiving hydraulic oil supply, a T port for discharging hydraulic oil, and A and B ports for supplying and discharging hydraulic oil to and from the hydraulic actuator, and when the operating means is in a neutral position The P port is closed and the A and B ports are connected to the T port. When the operating means is operated from the neutral position, the P port is connected to the A and B ports according to the operating direction. It is configured to connect to either one and to connect the T port to the other,
A supply oil passage connecting the hydraulic supply source to the P port;
An oil discharge passage connecting the T port to an oil tank;
A supply oil passage opening / closing valve provided in the supply oil passage for opening and closing the supply oil passage;
A first branch oil passage branched from the position on the control valve side than the supply oil passage opening and closing valve in the supply oil passage and connected to the discharge oil passage;
A first restriction that is provided in the first branch oil passage and restricts a flow rate of the hydraulic oil flowing through the first branch oil passage.
Aperture,
It is provided at a position closer to the oil tank than the connection point with the first branch oil passage in the discharge oil passage, and is opened when the hydraulic pressure on the connection point side exceeds a preset cracking pressure. A pressure setting check valve that allows a flow of hydraulic oil in a direction from the side toward the oil tank,
Work at height, characterized in that when the hydraulic supply source is started, the supply oil passage opening / closing valve is located at an open position that opens the supply oil passage and allows the flow of hydraulic oil Car hydraulic circuit. The hydraulic supply source is a variable displacement hydraulic pump,
A second branch oil passage branched from an oil passage between the control valve, the supply oil passage opening / closing valve and the first throttle and connected to a position closer to the oil tank than the pressure setting check valve in the discharge oil passage; ,
A second flow rate that is provided in the second branch oil passage and restricts the flow rate of the hydraulic oil flowing through the second branch oil passage.
Aperture,
The second branch oil passage is provided at a position closer to the discharge oil passage than the second throttle, and when the operating means is in a neutral position, the second branch oil passage is opened to allow a flow of hydraulic oil. An oil flow direction restriction switching valve that is switched to a position that prohibits the flow of hydraulic oil in the direction from the second throttle side toward the exhaust oil path when the operation means is operated from a neutral position;
Pump capacity control means for controlling the capacity of the hydraulic pump so as to obtain a pump discharge pressure corresponding to the hydraulic pressure using the hydraulic pressure between the second throttle and the oil flow direction restriction switching valve in the second branch oil passage. The hydraulic circuit for an aerial work vehicle according to claim 1, further comprising: A second branch oil passage branched from the oil passage between the control valve, the supply oil passage opening / closing switching valve and the first throttle and connected to a position closer to the oil tank than the pressure setting check valve in the discharge oil passage When,
A second flow rate that is provided in the second branch oil passage and restricts the flow rate of the hydraulic oil flowing through the second branch oil passage.
Aperture,
The second branch oil passage is provided at a position closer to the discharge oil passage than the second throttle, and when the operating means is in a neutral position, the second branch oil passage is opened to allow a flow of hydraulic oil. An oil flow direction restriction switching valve that is switched to a position that prohibits the flow of hydraulic oil in the direction from the second throttle side toward the exhaust oil path when the operation means is operated from a neutral position;
A pump discharge pressure adjusting valve that adjusts a pump discharge pressure so as to obtain a pump discharge pressure corresponding to the hydraulic pressure using a hydraulic pressure between the second throttle and the oil flow direction restriction switching valve in the second branch oil passage; The hydraulic circuit for an aerial work vehicle according to claim 1, further comprising: The working device includes a vertical post that is supported at the tip of the boom so as to be swingable up and down, and is always kept substantially vertical regardless of the boom angle.
The work table is swingably attached to the vertical post,
The hydraulic circuit for an aerial work vehicle according to any one of claims 1 to 3, wherein the hydraulic actuator swings the work table around the vertical post. The working device includes a vertical post supported at the tip of the boom so as to be swingable up and down,
The workbench is attached to the vertical post;
The hydraulic actuator for an aerial work platform according to any one of claims 1 to 3, wherein the hydraulic actuator swings the vertical post up and down so that the vertical post is always substantially vertical regardless of the boom undulation angle. circuit. The working device includes a bending / extending arm attached to the tip of the boom so as to be swingable up and down,
The work table is attached to the tip of the bending / extending arm,
The hydraulic circuit for an aerial work vehicle according to any one of claims 1 to 3, wherein the hydraulic actuator swings the bending and extending arm up and down with respect to the boom.

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