JP2008089104A - Power actuator driving control device of hydraulic working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power actuator driving control device of a hydraulic working machine which can easily adds to compact construction machines such as a mini-shovel, a high function such as automatic excavation and working area control, and can make the drive of a power actuator finely follow the operation of an operation lever despite the increase in working load. <P>SOLUTION: The power actuator driving control device of a hydraulic working machine is equipped with a direction control valve (38x) for controlling supply/discharge of pressure oil with respect to a power actuator (36x), a direct acting valve actuator (56) for switching and actuating the direction control valve (38x), a lever unit (74) for converting the control input of an operation lever (76) into an electric control input signal S<SB>L</SB>for outputting and a controller (72) for generating a drive signal S<SB>D</SB>to the valve actuator (56) on the basis of the control input signal S<SB>L</SB>from the lever unit (74). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power actuator drive control device for a hydraulic work machine applied to a high-function construction machine capable of automatic excavation, work area control, and the like, and in particular, a hydraulic pressure suitable for a high-function and small-sized construction machine. The present invention relates to a power actuator drive control device for a work machine.

In the above-described high-function construction machine, an electric lever device is often used for operating the hydraulic working machine. This electric lever device outputs the operation amount of the operation lever by replacing it with an electric operation signal, whereby the operation of the hydraulic working machine, that is, the driving of its power actuator (specifically, hydraulic cylinder) is performed. Can be electrically controlled.
More specifically, in the case of a general construction machine, the power actuator is driven by the switching operation of a pilot-type directional control valve so that the pressure oil is supplied from the hydraulic pump. It is used to control the switching of an electromagnetic proportional control valve that produces a pilot pressure signal to the valve (Patent Document 1).
Japanese Patent Laid-Open No. 2003-194005

  The electrical lever type hydraulic working machine described above requires a pilot pressure circuit such as a pilot pump, pilot piping, pilot filter, and pilot relief valve that are the source of the pilot pressure signal. It is applied to a machine, and it is difficult to apply to a small construction machine such as a mini excavator from the viewpoint of the space required by the pilot pressure circuit and the manufacturing cost.

  The present invention has been made based on the above-mentioned circumstances, and even if it is a small construction machine such as a mini excavator, it can easily add high functions such as automatic excavation and work area control. An object of the present invention is to provide a power actuator drive control device for a hydraulic working machine capable of closely following the operation of an operation lever regardless of the work load.

  In order to achieve the above object, the present invention comprises a work arm comprising a plurality of arm portions connected via a joint, a base end pivotally supported by an upper swing body, and a work attachment attached to the front end of the work arm. And a plurality of power actuators for driving each arm portion and work attachment of the work arm, and a hydraulic pump for supplying pressure oil toward the power actuator. Has a directional control valve that is inserted in a hydraulic path connecting the hydraulic pump and the power actuator, controls the supply of pressure oil to the power actuator, and an operation lever for switching the directional control valve. A lever unit that replaces the operation amount of the operation lever with an electrical operation signal and a direct connection to the directional control valve are provided. Based on the operation signal from the bets, and a motorized type valve actuator for actuating switch the directional control valve (claim 1).

According to the drive control device described above, when the operation lever of the lever unit is operated, an electrical operation signal is output from the lever unit. This operation signal switches and operates the direction control valve via the electric valve actuator, whereby the power actuator is driven according to the operation of the operation lever.
Preferably, the drive control device according to the present invention further includes a controller that controls a switching operation amount of the direction control valve according to a working state of the hydraulic working machine when the direction control valve is switched by an operation of an operation lever. In this case, the controller can adjust the operation signal from the lever unit in accordance with the work status of the hydraulic working machine (claim 3).

Specifically, the controller includes setting means for setting a work impossible area where entry of the work attachment is prohibited, work position detecting means for detecting the actual work position of the work attachment with respect to the base, and actual positions from the work position detecting means. Restriction means for calculating a restriction amount for the operation signal based on a deviation between the work position and the work disabling region can be included.
According to the above-described controller, when the work attachment of the hydraulic working machine is activated in response to the operation of the operation lever, the closer the actual work position of the work attachment is to the work impossible area, that is, the above-described deviation can be reduced. The restriction means increases the restriction amount with respect to the operation signal from the lever unit.

Therefore, regardless of the operation signal, the switching operation amount of the directional control valve, that is, the operation amount of the power actuator is reduced, and the work attachment does not enter the work impossible area.
The operation of the controller described above implements work area control of the hydraulic work machine, and such work area control is one of the functions indispensable for realizing the automation of the hydraulic work machine.

On the other hand, the controller detects the pressure of the pressure oil supplied to the power actuator and outputs a pressure signal corresponding to the pressure, and an adjustment amount for the operation signal based on the pressure signal from the pressure sensor. It is also possible to include adjusting means for calculating (claim 5).
Specifically, the adjustment means increases the operation signal from the lever unit in the increasing direction as the pressure of the pressure oil supplied to the power actuator, that is, the load pressure of the power actuator becomes higher than the reference pressure. Adjustment is made to correct, and the switching operation amount of the direction control valve, that is, the supply flow rate of pressure oil to the power actuator is increased.

The function of the controller described above associates the supply amount of the pressure oil supplied to the power actuator through the direction control valve with the operation amount of the operation lever, regardless of the load pressure of the power actuator.
Further, the valve actuator may include a stepping motor (Claim 6), in which case the rotation angle of the stepping motor determines the switching operation amount of the direction control valve.

  The power actuator drive control device for a hydraulic working machine according to claim 1 replaces the operation amount of the operation lever with an electric operation signal, and switches the direction control valve via the electric valve actuator based on the operation signal. As a result, the drive of the power actuator can be electrically controlled. Therefore, advanced functions such as automatic excavation and work area control can be easily added to the hydraulic working machine.

The drive control device according to any one of claims 2 to 5 realizes work area control for the work attachment of the hydraulic work machine because the operation signal from the lever unit is controlled by the controller according to the work situation of the hydraulic work machine, The response of the power actuator is greatly improved by making the drive of the power actuator follow the operation of the operation lever quickly.
The drive control apparatus according to the sixth aspect provides an inexpensive valve actuator that switches the direction control valve with high accuracy in response to the operation signal.

FIG. 1 shows a mini excavator as a construction machine.
The mini excavator includes a crawler-type lower traveling body 2 and an upper revolving body 4 provided on the upper side of the lower traveling body 2. A driver's seat 6 is disposed on the upper swing body 4, and the driver's seat 6 is covered from above by a canopy 8.
A working arm 10 of a hydraulic working machine extends from the front of the upper swing body 4, and the work arm 10 includes a boom 12 and an arm 14 from the upper swing body 4 side. The base end of the boom 12 is supported by an upper swing body 4 as a base via a pivot pin 12p, and the boom 12 can be raised and lowered around the pivot pin 12p in the vertical direction. The arm 14 is connected to the tip of the boom 12 via a joint, that is, an arm pin 14p, and is rotatable up and down around the arm pin 14p.

Further, a bucket 16 is attached to the tip of the arm 14 via a bucket pin 16a as a joint. This bucket 16 is one of the work attachments in the hydraulic working machine, and is vertically moved around the bucket pin 16a. It is freely rotatable.
Each of the boom 12, the arm 14, and the bucket 16 described above is raised or lowered when the corresponding boom cylinder 18, arm cylinder 20 and bucket cylinder 22 are expanded or contracted, and the expansion and contraction operations of these cylinders 18 to 22 are operated. It is possible from seat 6. That is, the lever consoles 24 are respectively arranged on the left and right sides of the driver's seat 6, and the cylinders 18 to 22 are expanded and contracted independently by operation of the lever consoles 24.

The boom cylinder 18, the arm cylinder 20, and the bucket cylinder 22 are power actuators for realizing the operation of the hydraulic working machine, and are each composed of a double-acting hydraulic cylinder. In FIG. 1, reference numeral 26 indicates a soil discharge blade, and the soil discharge blade 26 projects forward from the lower traveling body 2.
FIG. 2 schematically shows an open center type hydraulic circuit 28 of the hydraulic working machine.

This hydraulic circuit includes a variable displacement hydraulic pump 30, and this hydraulic pump 30 is connected to a prime mover 32 such as a mini excavator engine or an electric motor. When the hydraulic pump 30 is driven by the prime mover 32, the hydraulic pump 30 supplies the pressure oil sucked from the hydraulic tank 34 toward the power actuator 36x.
Here, the subscript “x” of the power actuator 36 x represents any one of the boom cylinder 18, the arm cylinder 20, and the bucket cylinder 22 described above, and will be used in the same meaning below.

Direction control valves 38x are respectively arranged in the hydraulic pipe lines connecting the hydraulic pump 30 and the power actuator 36x. As is apparent from FIG. 2, the direction control valve 38x is a 6-port 3-position direction switching valve that controls the supply direction and supply amount of pressure oil from the hydraulic pump 30 to the power actuator 36x.
FIG. 3 shows the directional control valve 38x more specifically.

  The direction control valve 38 x has a valve spool 40, and the valve spool 40 is slidably disposed in the valve body 42. Both ends of the valve spool 40 protrude from the valve body 42, and the right end of the valve spool 40 is surrounded by a cup-shaped spring cover 44 as viewed in FIG. The spring cover 44 is attached to the valve body 42 via a stopper plate 46, and the right end of the valve spool 40 passes through the stopper plate 46.

  A pair of springs 50 a and 50 b are attached to the right end of the valve spool 40 via bolt-shaped spring seat retainers 48, and the spring seats 50 a and 50 b are separated from each other in the axial direction of the valve spool 40. The spring seats 50a and 50b sandwich and hold a center spring 52 as a return spring therebetween, and the center spring 52 presses and urges the spring seats 50a and 50b in a direction away from each other. When the center spring 52 is in the state shown in the drawing, the center spring 52 presses the sleeve 50a against the stopper plate 46, while pressing the spring seat 50b against the bottom wall of the spring cover 44, the valve spool 40, ie, the direction The control valve 38x is positioned at the neutral position N shown in FIG. When the direction control valve 38x is in the neutral position, the pressure oil discharged from the hydraulic pump 30 is simply returned to the hydraulic tank 34 through the center bypass passage of the direction control valve 38x.

  However, when the valve spool 40 is moved to the left from the state shown in FIG. 3, this movement is accompanied by compression of the center spring 52 only by the spring seat 50b, whereas the valve spool 40 is moved to the right. The movement here involves the compression of the center spring 52 only by the spring seat 50a. Therefore, even if the valve spool 40 moves in the left or right direction from the state shown in FIG. 3, the valve spool 40 is moved against the urging force of the center spring 52.

  When the valve spool 40 is moved in one direction and the direction control valve 38x is switched from the neutral position N to the left switching position A in FIG. 2, the pressure oil discharged from the hydraulic pump 30 is powered through the direction control valve 38x. While being supplied to the bottom chamber of the actuator 36x, the pressure oil in the rod chamber is returned to the hydraulic tank 34 through the direction control valve 38x, and the power actuator 36x extends the rod.

  On the other hand, when the valve spool 40 is moved in the other direction and the direction control valve 38x is switched from the neutral position N to the switching position B to the right side, the pressure oil discharged from the hydraulic pump 30 is powered through the direction control valve 38x. While being supplied to the rod chamber of the actuator 36x, the pressure oil in the bottom chamber is returned to the hydraulic tank 34 through the direction control valve 38x, and the power actuator 36x contracts the rod.

That is, the direction control valve 38x controls the expansion and contraction of the power actuator 36x according to the switching direction from the neutral position N, and the amount of pressure oil supplied to the power actuator 36x is set to the stroke of the valve spool 40 in the switching direction, that is, The valve opening can be controlled.
Specifically, when the movement amount of the valve spool 40 is increased during the switching operation of the direction control valve 38x, the opening of the center bypass passage in the direction control valve 38x is reduced, while the supply of pressure oil to the power actuator 36x is performed. The opening degree of the exhaust valve passage is increased. That is, the flow rate of pressure oil that escapes from the hydraulic pump 30 to the hydraulic tank 34 through the direction control valve 38x (bleed-off flow rate) decreases, and at the same time, the flow rate of pressure oil that is supplied from the hydraulic pump 30 to the power actuator 36x through the direction control valve 38x. As a result, the power actuator 36x is expanded and contracted at a speed corresponding to the operation amount of the operation lever 76.

  In order to perform the switching operation of the directional control valve 38x described above, an electric valve actuator 56 is directly connected to the other end of the valve spool 40. The valve actuator 56 includes a stepping motor 60 that can rotate forward and reverse, a change mechanism (not shown) that converts the rotation of the stepping motor 60 into a linear motion of the linear motion shaft 58, and the linear motion shaft 58 that is connected to the valve spool 40. The stepping motor 60 is fixed to a frame (not shown) of the upper swing body 4 via an L-shaped bracket 62.

On the other hand, the link 54 has an H shape as apparent from FIG. 4 and is connected to the other end of the valve spool 40 via a connecting pin 64, while being connected to the linear motion shaft 58 of the valve actuator 56 via a connecting pin 66. It is connected.
When the stepping motor 60 is driven to rotate, the linear movement shaft 58 of the valve actuator 56 moves forward or backward with respect to the valve spool 40 and moves the valve spool 40 in the axial direction via the link 54. Here, the moving direction of the valve spool 40 is determined by the rotational direction of the stepping motor 60.

  4 is used not only for the directional control valve in which the valve body 42 described above is combined with each of the boom cylinder 18, the arm cylinder 20 and the bucket cylinder 22 described above, but also for the directional control valve combined with other power actuators. The directional control valves other than the directional control valve 38x described above are represented by “a” to “h” in FIG.

Other power actuators include left and right traveling motors (not shown) of the lower traveling body 2, a turning motor (not shown) of the upper swinging body 4, and a vertical movement cylinder 68 (see FIG. 1) of the soil discharging blade 26, A power actuator (not shown) for an optional function is included.
As is apparent from FIG. 2, the stepping motor 60 of the valve actuator 56 is electrically connected to a motor driver 70. Furthermore, the motor driver 70 is electrically connected to the lever unit 74 of the lever console 24 described above via a controller 72. Connected.

The lever unit 74 includes an operation lever 76 operated by an operator seated in the driver's seat 6 and an operation amount sensor 78x. The operation amount sensor 78x detects an operation amount of the operation lever 76 in a corresponding direction, It converts the detected operation amount to the electrical manipulation signal S _L outputs. Specifically, a potentiometer or a rotary encoder that detects the operation angle of the operation lever 76 can be used as the operation amount sensor 78x. In this embodiment, the operation amount sensor 78x is a potentiometer.

On the other hand, the controller 72 includes an operation signal input unit 80 for receiving an operation signal S _L from the operation amount sensor 78x, and a calculation unit 82 for calculating a drive signal S _D of the motor driver 70 on the basis of the operation signal S _L, the driving The signal _SD is transmitted from the output unit 84 of the controller 72 to the motor driver 70.
Therefore, when the operating lever 76 is operated, wherein the operation amount of the is converted into an electrical operational signal S _L by the operation amount sensor 78x, and the operation signal S _L is as the drive signal S _D by the arithmetic unit 82 It is supplied to the motor driver 70. Upon receiving the drive signal _SD , the motor driver 70 drives the stepping motor 60 of the valve actuator 56 by a predetermined direction and rotational speed based on the drive signal _SD , whereby the direction control valve 38x is moved from its neutral position N. Switching is made toward a switching position corresponding to the operation direction of the operation lever 76, and at this switching position, the valve is opened with a valve opening degree corresponding to the operation amount of the operation lever 76.

As a result, the pressure oil discharged from the hydraulic pump 30 is supplied to the power actuator 36x through the direction control valve 38x, and the power actuator 36x is expanded or contracted, thereby operating the hydraulic working machine.
As is clear from the above description, the directional control valve 38x is a direct acting switching type that is switched by the valve actuator 56. Therefore, the switching control of the directional control valve 38x does not require a pilot pressure circuit including a pilot pump or the like. The hydraulic circuit of the work machine is suitable for a small construction machine such as a mini excavator from the viewpoint of arrangement space and cost.

Further, since the operation amount of the operation lever 76 is converted into an electrical operational signal S _L, it enables automatic excavation hydraulic working machine, even in a mini excavator, possible to easily realize the high functionality Can do.
Furthermore, even if the electrical system of the hydraulic circuit fails and the operation control of the valve actuator 56 becomes impossible, the center spring 52 of the direction control valve 38x returns the valve spool 40 to the neutral state, and the direction control valve 38x is brought to the neutral position. Since the power actuator 36x is not expanded and contracted undesirably, the safety in operation of the hydraulic working machine is sufficiently ensured.

Controller 72 of this embodiment in accordance with the working conditions of the hydraulic working machine, and also a function of increasing and decreasing the operation signal S _L mentioned above, one example is explained below.
As shown in FIG. 2, angle sensors 86x are assigned to the power actuators 36x, and these angle sensors 86x are used for hydraulic work on the upper swing body 4 when the hydraulic working machine is actuated by expansion and contraction of the power actuator 36x. The actual work position of the bucket 16 of the machine is detected.

Specifically, the angle sensor 86x detects a rotation angle of the movable element is rotated from the power actuator 36x, and outputs the detected angle signal S _A. As the angle sensor 86x, either a potentiometer or a rotary encoder can be used. In this embodiment, the angle sensor 86x is a rotary encoder.
The movable element includes the boom 12 and the arm 14 constituting the working arm of the hydraulic working machine, and the bucket 16 as the work attachment, and the angle sensor 86x detects the rotation angle of the corresponding movable element. The movable element is attached to pins (12p, 14p, 16p) that rotatably support the movable element.

Angle signal S _A from the angle sensor 86x, sent to the angle signal input unit 88 of the controller 72, and arithmetic unit 82 from the angle signal input unit 88, i.e., calculator arithmetic unit 82 as shown in FIG. 5 90. Based on this calculator 90, the angle signal S _A, calculates the actual working position P of the bucket 16 from the upper rotating body 4, the actual work position P is represented by three-dimensional coordinates.

  More specifically, since the lengths and shapes of the boom 12 and the arm 14 and the size of the bucket 16 are known, if the rotation angles of the boom 12, the arm 14 and the bucket 16 are detected, the upper swing body is detected. 4 can be calculated as the actual work position P. Since the actual work position P of the bucket 16 can be estimated from the tip position of the arm 14, the rotation angle of the bucket 16 is not indispensable for calculating the actual work position P.

On the other hand, the calculation unit 82 includes a memory 92 in which work disabled areas of the bucket 16 are stored in advance. The work disabling region is a three-dimensional coordinate representation of the allowable proximity position of the bucket 16 with respect to the lower traveling body 2 and the upper revolving body 4, and is represented by a boundary surface 94 of a one-dot chain line in FIG. Yes.
As shown in FIG. 5, the actual work position P from the calculator 90 and the work impossible area from the memory 92 are respectively supplied to the subtractor 96, and the subtractor 96 is connected to the work impossible area (boundary surface) from the actual work position P. 94) and the deviation ΔD is supplied to the gain calculator 98. The gain calculator 98 has a gain map shown in FIG. 6, and calculates a regulation gain K1 (regulation amount) from the gain map based on the deviation ΔD.

When regulating the gain K1 as is clear from Figure 6 that the deviation ΔD is in the critical distance D ₀ or more, a maximum value 1.0, the deviation ΔD is gradually decreases is smaller than the critical distance D _0, and, When the deviation ΔD becomes 0, that is, when the actual work position P of the bucket 16 reaches the work impossible area (boundary surface 94), it becomes 0.
The regulation gain K1 is supplied to the computing unit 100 together with the operation signal S _L from the lever unit 74 (operation amount sensor 78x) described above, and the computing unit 100 multiplies the operation signal S _L by the regulation gain K1 to thereby operate the operation signal S. _L is regulated, and thereafter, the drive signal _SD described above is calculated based on the regulated operation signal S _1L , and this drive signal _SD is transmitted from the computing unit 82 to the motor driver 70 through the output unit 84.

According to the control configuration shown in FIG. 5, in response to operation of the operating lever 76 as described above, when the hydraulic working machine is operated with a telescopic power actuator 36x, the angle signal S _A from the angle sensor 86x actual working position P of the bucket 16 is obtained in a hydraulic working machine based on and restricted gain K1 for operation signal S _L from the actual working position P is determined.

If the actual work position P of the bucket 16 is in a work area that is more than the critical distance D ₀ from the work impossible area described above, the regulation gain K1 is maintained at 1.0, so the operation signal _SL is substantially regulated. The hydraulic working machine operates according to the operation of the operation lever 76.
However, if the proximity to the work area incapable actual work position P exceeds the critical distance D ₀ of the bucket 16 (interface 94), regulating the gain K1 is also the actual working position P As the reduction of the deviation ΔD is 1.0 The control signal _S1L after the regulation is gradually reduced. Therefore, since the drive signal _SD to the motor driver 70 is also reduced, the amount of movement of the valve spool 40 in the direction control valve 38x is reduced, the expansion / contraction speed of the power actuator 36x is reduced, and the operator operates the operation lever 76. Regardless of this, since the movement of the bucket 16 is delayed, it is possible to recognize that the bucket 16 is close to the work-impossible area.

When the actual work position P of the bucket 16 reaches the work disabling region (boundary surface 94), the regulation gain K1 becomes 0, so that the calculation unit 82 is operated by the motor driver despite the operation lever 76 being operated. The drive signal _SD is not output to 70. Therefore, the direction control valve 38x is returned to the neutral position N, and the expansion and contraction of the power actuator 36x is prohibited. As a result, the bucket 16 is reliably prevented from entering the work impossible area, and the bucket 16 does not undesirably collide with the lower traveling body 2 or the upper swing body 4 during the excavation work.

The work area control for the bucket 16 described above is also effective in carrying out automatic excavation of a mini excavator.
Next, a modified example of the present invention will be described.
For modification, the controller 72 as a working condition of a hydraulic working machine, also taking into account the pressure of the hydraulic fluid supplied to the power actuator 36x, adjusts the operation signal S _L. Therefore, as shown in FIG. 2, a pressure sensor 102x is disposed in the vicinity of the directional control valve 38x, the pressure sensor 102x detects the pressure supplied to the power actuator 36x, the detected pressure signal S _P Output.

Pressure signal S _P is supplied to the arithmetic unit 82 via the pressure signal input unit 104 of the controller 72, the details of the computation unit 82 in this case is shown in FIG.
7 further includes a gain calculator 106 to which the pressure signal _SP is supplied. The gain calculator 106 has a gain map shown in FIG. 8, and calculates the adjustment gain K2 (adjustment amount) on the basis of the gain map to a pressure signal S _P.

As apparent from FIG. 8, while in the following pressure signal S _P0 indicating the standard load pressure pressure signal S _P is applied to the power actuator 36x, adjusting gain K2 is kept constant at 1.0, and the pressure signal S _P is brought into rises above the _{S P0,} adjusting gain K2 is gradually increased from 1.0. In FIG. 8, _SPR is a pressure signal indicating the relief pressure of the hydraulic circuit.
The adjustment gain K2 is supplied to the multiplier 108 together with the above-described restriction gain K1, and the multiplier 108 multiplies the restriction gain K1 by the adjustment gain K2 to obtain an integrated gain K (= K1 × K2). This integrated gain K is supplied to the aforementioned arithmetic unit 100 together with the operation signal S _L and is used for the calculation of the drive signal _SD .

As described above, since the adjustment gain K2 is taken into consideration in the calculation of the drive signal _SD , when the expansion / contraction operation of the power actuator 36x is performed in a region below the standard load pressure (that is, the pressure signal _SP is S). _{When P0} or less), the adjustment gain K2 is maintained at a constant value of 1.0, and the adjustment gain K2 does not affect the integrated gain K, that is, the operation signal S _L or S _1L .

However, expansion and contraction of the power actuator 36x has been made in the area beyond the standard load pressure, the pressure signal S _P is the greater than S _P0, adjusting gain K2 increases from 1.0. For this reason, the value of the integrated gain K described above is increased, and the operation signal S _L or S _1L , that is, the drive signal _SD is adjusted in the increasing direction.
Therefore, when the bucket 16 is in the work area and the power actuator 36x is expanded or contracted to an area exceeding the standard load pressure, the calculation unit 82 supplies the drive signal _SD corrected for increase to the motor driver 70, The valve spool 40 of the direction control valve 38x is moved excessively. As a result, the supply flow rate of the pressure oil supplied to the power actuator 36x through the direction control valve 38x and the operation amount of the operation lever 76 correspond to the case where the power actuator 36x is expanded and contracted below the standard load pressure. Thus, the hydraulic working machine operates accurately following the operation of the operation lever 76, and fine operation control of the hydraulic working machine becomes possible.

  More specifically, in the above-described open center type hydraulic circuit, when the directional control valve 38x is switched, the aforementioned read-off flow rate that passes through the directional control valve 38x is the load of the power actuator 36x. Since the pressure changes depending on the pressure, the supply amount of the pressure oil to the power actuator 36x supplied through the direction control valve 38x as shown in FIG. 9A also changes. That is, even when the movement amount of the valve spool 40 in the direction control valve 38x is the same during the switching operation, the supply flow rate of the pressure oil to the power actuator 36x depends on the load pressure, and is shown in FIG. 9B. Thus, as the load pressure increases, the supply flow rate of the pressure oil decreases.

However, when the stretch operating in areas where the power actuator 36x as described above exceeds the standard load pressure, i.e., when the actual pressure signal S _PA is larger than S _P0, as shown in FIG. 10, the direction control The amount of movement of the valve spool 40 in the valve 38x is increased from the broken line to the solid line, and the supply flow rate of pressure oil to the power actuator 36x is increased from Q1 to Q2 by that amount, as in the region below the standard load pressure. The operation amount of the operation lever 76 and the supply amount of pressure oil from the power actuator 36x can be associated with each other.

The supply flow rate Q2 is a supply flow rate in a normal state where the power actuator 36x is at a standard load pressure and the movement amount of the valve spool 40 is not corrected.
The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made.
For example, although regulation gain K1 and adjusting gain K2 is used to regulate or adjust the operation signal S _L, the drive signal S _D may be regulated or adjusted by a gain K1, K2.

Further, the valve actuator 56 may use a linear motor instead of the stepping motor 60.
Furthermore, it goes without saying that the present invention is not limited to mini-excavators and can be similarly applied to various small construction machines.

It is a side view of a mini excavator provided with a hydraulic working machine. It is the schematic which showed the hydraulic circuit of the hydraulic working machine. FIG. 5 is a side view showing the directional control valve partly broken along the line III-III in FIG. 4. It is the top view which showed the whole valve assembly containing the direction control valve of FIG. FIG. 3 is a control block diagram illustrating details of a calculation unit in FIG. 2 and illustrating drive control of the power actuator of one embodiment. It is the graph which showed the gain map for calculating a regulation gain. FIG. 5 is a control block diagram illustrating details of a calculation unit in FIG. 2 and illustrating drive control of a power actuator according to a modification. 6 is a graph showing a gain map for calculating an adjustment gain. It is a graph showing the supply flow rate characteristic of a directional control valve, Comprising: (a) is a graph which shows that the relationship between the movement amount of a valve spool and supply flow changes with the magnitude of the load pressure of a power actuator, (b) is power It is a graph which shows that the relationship between the load pressure of an actuator and a supply flow rate changes with the magnitude | size of the movement amount of a valve spool. It is a graph which shows that the movement amount of a valve spool is correct | amended when the load pressure of a power actuator exceeds standard load pressure.

Explanation of symbols

4 Upper swing body (base)
10 Working arm 12 Boom (arm part)
14 Arm (arm)
16 bucket (work attachment)
30 Hydraulic pump 36x Power actuator 38x Directional control valve 56 Valve actuator 60 Stepping motor 72 Controller 74 Lever unit 76 Operation lever 78x Operation amount sensor 82 Calculation unit 86x Angle sensor (working position detection means)
90 Calculator (working position detection means)
92 Memory (setting means)
94 Boundary surface (work impossible area)
96 Subtractor (regulation means)
98 Gain calculator (regulatory means)
102x pressure sensor 106 gain calculator (adjustment means)
108 Multiplier (Adjustment means)

Claims (6)

A work arm composed of a plurality of arms connected through joints, the base end of which is pivotally supported by the upper swing body,
A work attachment attached to the tip of the work arm;
A plurality of power actuators for respectively driving the arm portions and the work attachment of the work arm;
In a hydraulic working machine including a hydraulic pump that supplies pressure oil toward the power actuator,
A directional control valve that is inserted in a hydraulic path connecting the hydraulic pump and the power actuator, and controls the supply of pressure oil to the power actuator;
A lever unit that has an operation lever for switching the direction control valve, and replaces the operation amount of the operation lever with an electrical operation signal;
A power actuator for a hydraulic working machine, comprising: an electrically operated valve actuator that is directly connected to the direction control valve and switches the direction control valve based on the operation signal from the lever unit. Drive control device.   The controller further comprises a controller for controlling a switching operation amount of the directional control valve according to a working condition of the hydraulic working machine when the directional control valve is switched by an operation of the operation lever. 2. A power actuator drive control device for a hydraulic working machine according to 1.   The power actuator drive control device for a hydraulic working machine according to claim 2, wherein the controller adjusts the operation signal from the lever unit in accordance with a working situation of the hydraulic working machine. The controller is
Setting means for setting a work impossible area where entry of the work attachment is prohibited;
Work position detecting means for detecting an actual work position of the work attachment with respect to the base;
4. The hydraulic pressure according to claim 3, further comprising: a regulation unit that calculates a regulation amount for the operation signal based on a deviation between the actual work position and the work impossible area from the work position detection unit. Power actuator drive control device for work equipment. The controller is
A pressure sensor that detects the pressure of the pressure oil supplied toward the power actuator and outputs a pressure signal corresponding to the pressure;
5. The power actuator drive control device for a hydraulic working machine according to claim 3, further comprising an adjusting unit that calculates an adjustment amount for the operation signal based on the pressure signal from the pressure sensor.   The power actuator drive control device for a hydraulic working machine according to claim 1, wherein the valve actuator includes a stepping motor.

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