JPH0657781A - Power shovel, and straight-line excavation therewith - Google Patents

Abstract

PURPOSE:To carry out highly accurate horizontal excavation according to normal work command given by an operator. CONSTITUTION:Pilot pressure for boom hoisting operation produced by a boom operating lever 48a is inputted directly into a main boom operating valve 74, and pilot pressure for boom lowering operation is inputted into the main boom operating valve 74 through a solenoid valve 68 for controlling the boom lowering. Pilot pressure for excavation operation produced by an arm operating lever 48b is inputted into a main arm operating valve 84 through a solenoid valve 70 for controlling the arm in excavation operation, and pilot pressure for dump operation is inputted directly into the main arm operating valve 84. A controller 60 obtains excavation depth for a bucket 38, based on detection signals outputted from a boom angle sensor 28, an arm angle sensor 36 and the like, and controls so that the excavation can be stopped with the solenoid valves 68 and 70 cut off when the excavation depth exceeds a specified value, and also controls so that warnings can be given to an operator when the excavation depth becomes shallower than the specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic excavator, and more particularly to a linear excavation method and a power excavator suitable for horizontal excavation such as scraping work by an operator.

[0002]

2. Description of the Related Art In recent years, with the development of electronic control technology, it has been proposed to automatically perform a scraping operation (horizontal excavation) for moving a bucket of a power shovel along a straight line designated in advance. .

[0003]

Therefore, when automatic horizontal excavation is performed, an electric command device such as an electric joystick is provided as a work command unit, and the electric signal is decoded to output a hydraulic command to the hydraulic actuator. In general, the above hydraulic actuators are provided on all work implement operating shafts for operating the bucket. Further, in order to put the control device capable of automatic horizontal excavation into practical use, the hydraulic pressure in the hydraulic actuator unit is detected, and this is fed back to the control unit to compensate for the hydraulic pressure to improve the automatic control accuracy. It is necessary to plan. Therefore, the conventional power shovel capable of automatic horizontal excavation has many components constituting a control device as compared with a general power shovel, and considering the accuracy and failure of each component, the reliability as an automatic control device is high. descend. Moreover, it is extremely difficult for the operator to perform high-precision horizontal excavation by a normal work command performed by operating the lever.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a straight excavation method for a power shovel capable of highly accurate horizontal excavation in accordance with a normal work instruction from an operator. It is also an object of the present invention to provide a power shovel capable of easily implementing the straight excavation method.

[0005]

In order to achieve the above object, a straight excavating method for a power shovel according to the present invention is provided.
A bucket provided on the revolving structure via the boom and arm,
In a linear excavation method for a power shovel in which a boom operating lever and an arm operating lever are operated to move along a predetermined straight line, a vertical position of the bucket with respect to the straight line is obtained, and the bucket position is a predetermined allowable value. The feature is that when the upper and lower limits of the range are reached, the operator is notified of that fact.

[0006] The fact that the bucket position has reached the lower limit of the allowable range can be notified to the operator by preventing the bucket from moving in the deeper direction.

Further, the power shovel according to the present invention comprises a bucket provided on a revolving structure via a boom and an arm, a boom operating lever for operating the boom, an arm operating lever for operating the arm, Based on a plurality of sensor units that detect the operation amount of the boom and the arm, a straight line setting unit that sets a reference straight line for linearly moving the bucket, and a detection signal of the plurality of sensor units, While calculating the position of the bucket, the vertical distance to the reference straight line of the obtained bucket position is obtained, when this distance reaches the upper and lower limits of the predetermined allowable range,
The control device outputs a signal notifying the operator to that effect.

[0008]

The linear excavation method of the present invention configured as described above is
When the operator operates the boom operation lever and the arm operation lever to move the bucket along a predetermined reference straight line for excavation and the bucket is separated from the reference straight line by a predetermined amount or more in the vertical direction, The operator is informed of the effect. Therefore, the operator can know that the excavation level by the bucket deviates from the target value,
Operate the boom operation lever and arm operation lever to
The excavation level can be easily corrected to the target value. As a result, it is possible to perform straight line excavation such as high-precision skive excavation in accordance with a normal work command from the operator.
In addition, the number of actuators for automatic control can be reduced and reliability can be improved as compared with the conventional power shovel capable of horizontal automatic excavation.

Further, when the bucket reaches the lower limit of the allowable range, if the bucket is prevented from moving in the deeper direction, it is possible to eliminate the trouble of having to dig too deep and backfill. , The excavation work can be speeded up.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a straight excavation method for a power shovel and a power shovel of the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 is a schematic side view of the power shovel according to the embodiment of the present invention.

In FIG. 2, a hydraulic power shovel 1
In No. 0, the upper revolving structure 18 is provided above the lower traveling structure 12 via the revolving device 14. A boom 20 is attached to the upper swing body 18. Boom 20 is the first
It is composed of a boom 22 and a second boom 24, is bent in a substantially L shape, and the base end portion of the first boom 22 is rotatably attached to the upper swing body 18 via a boom foot pin. Thus, it can rotate about the fulcrum O as shown by an arrow 26. A boom angle sensor 28 for detecting the amount of rotation of the first boom 22 is provided at the base end of the first boom 22.

The tip of the boom 20, that is, the second boom 2
An arm 32 is attached to the tip of 4 via a bracket 30.
It is provided so as to be rotatable about a rotation fulcrum D as shown by an arrow 34. An arm angle sensor 36 for detecting the rotation angle of the arm 32 is attached to the rotation fulcrum D. Further, a bucket 38 is provided at the tip of the arm 32 so as to be rotatable about a fulcrum E as shown by an arrow 40. At the fulcrum E, the bucket 3
8 excavation angle (tilt of bucket 38 with respect to arm 32)
A bucket angle sensor (not shown in the figure) for detecting is attached.

The second boom 24 is provided with a bucket 38.
Is offset from the center line of the upper swing body 18, and can be rotated about the fulcrum B with respect to the first boom 22 in a direction orthogonal to the paper surface of FIG. 2, that is, as indicated by an arrow 42 in FIG. It is like this. An offset angle sensor 44 for detecting the offset angle, which is the rotation amount of the second boom 24, is attached to the fulcrum B. The bracket 30 is pivotally supported by the second boom 24 at the fulcrum C, and when the second boom 24 rotates with respect to the first boom 22, the bucket 38 is moved to the upper swing body 18 as shown in FIG. It is designed so that it can always be maintained parallel to.

A plurality of operating levers 48 for operating the boom 20, the arm 32, and the bucket 38 are provided in the operator's cab 46 which constitutes the upper swing body 18. That is, as shown in FIG. 1, a boom cylinder 50 for moving the boom 20 up and down is provided between the upper swing body 18 and the first boom 22, and an arm 32 is provided between the boom 20 and the arm 32 for excavation operation. Alternatively, an arm cylinder 52 for performing a dump operation, a bucket cylinder 54 for adjusting an excavation angle of the bucket 38 are provided between the arm 32 and the bucket 38, and between the first boom 22 and the second boom 24. An offset cylinder (not shown) for rotating the second boom 24 is provided, and these cylinders can be driven by a plurality of operation levers 48 provided in the cab 46.

Further, in the operator's cab 46, a control device 60 is provided together with various kinds of indicators not shown (see FIG. 1). As shown in FIG. 4, the control device 60 receives the detection signals of the boom angle sensor 28, the arm angle sensor 36, and the offset angle sensor 44, and the bucket 38.
The detection signals of the bucket angle sensor 62 for detecting the angle (digging angle) with respect to the arm 32 are input, and the position of the bucket 38 can be obtained based on the detection signals of these sensors as described later. You can do it. Further, the control device 60 includes an excavation level setter 6 for setting a target excavation level for horizontal excavation.
4 and an alarm device 66 for notifying an operator (not shown) of the fact that the obtained position of the bucket 38 is separated from the upper and lower limits of the allowable range of the excavation level. In addition, the control device 60 includes a boom lowering control solenoid valve 68,
An arm excavation control solenoid valve 70 and an offset control solenoid valve 72 are connected, and control signals are output to the exciting coils of these solenoid valves.

As shown in FIG. 1, the boom lowering control solenoid valve 68 has an output side connected to a boom main operation valve 74 for driving the boom cylinder 50 via a conduit 73, and an input side connected to a conduit 76. Via the boom operating lever 48a
Connected to. The boom operating lever 48a is a so-called PPC system that can operate the pilot pressure of the boom main operating valve 74, and is connected to a hydraulic pump 78 on the input side to lower the boom 20 output by the boom operating lever 48a. The pilot pressure is transmitted to the boom main operating valve 74 via the boom lowering control solenoid valve 68, and the pilot pressure for raising the boom 20 can be directly transmitted to the boom main operating valve 74 via the conduit 80. Therefore, the operation amount of the boom operation lever 48a directly represents the speed of the boom 20.

On the other hand, the arm excavation control solenoid valve 70 has an output side connected to an arm main operation valve 84 for driving the arm cylinder 52 via a pipe line 82, and an input side connected to an arm operation lever via a pipe line 86. It is connected to 48b.
This arm operating lever 48b is also a boom operating lever 48a.
Similarly to the above, the lever is a PPC system, and the hydraulic pump 78 is connected to the input side. Then, the pilot pressure of the arm main operation valve 84 output by the arm operation lever 48b during the dump operation of the arm 32 is directly transmitted to the arm main operation valve 84 via the pipe line 88, and the excavation operation is performed. The pilot pressure of the arm main operation valve 84 is transmitted to the arm main operation valve 84 via the arm excavation control solenoid valve 70.

The operation of the embodiment configured as described above will be described below by taking horizontal excavation as an example. First, the operator
A target excavation depth for horizontal excavation and a permissible error (permissible excavation range) for the target excavation depth are set in the excavation level setter 64. This target excavation depth is
When the X axis is in the front direction of 8, the Y axis is above the upper swing body 18, and the Z axis is in the horizontal direction, they are given as Y coordinates.
Therefore, when the excavation depth (excavation level) is constant, the excavation level setter 64

## EQU1 ## A linear equation such as y = constant (= target excavation depth Y ₀ ) and an excavation allowable range Y ₀ ± Δy ₀ for this target excavation depth Y ₀ are set. The target excavation depth Y ₀ and the excavation allowable range Y ₀ ± Δy ₀ thus set are displayed by the control device 60 on a display device (not shown) in the cab 46. In the case of horizontal excavation, the bucket 38
The Z coordinate of represents the offset amount of the bucket 38.

Next, the operator operates the bucket cylinder 5
The digging angle of the bucket 38 is set to a predetermined angle by a lever for operating 4, and the digging angle is maintained. After that, the operator operates the boom operation lever 48a and the arm operation lever 4
When the excavation is started by operating the 8b and the second boom operation lever, the boom angle sensor 28, the arm angle sensor 36, the offset angle sensor 44, and the bucket angle sensor 62 each input a detection signal to the control device 60.

That is, the boom angle sensor 28 is the boom 2
Detecting the inclination angle theta ₁ 0 of the base end upper swing structure 18 with respect to the horizontal direction inputted to the control unit 60, the arm angle sensor 36 is inclined angle theta ₂ to the second boom 24 of the arm 32
Is detected and input to the control device 60, the offset angle sensor 44 detects the rotation angle θ ₃ of the second boom 24 with respect to the first boom 22, and inputs the rotation angle θ ₃ to the control device 60, and the bucket angle sensor 62 detects the bucket angle of the bucket 38. The rotation angle β with respect to the arm 32 is detected and input to the control device 60. And the control device 1
0 indicates the tip position of the bucket 38 on the basis of the detection signals of these sensors in the X, Y, Z coordinate positions (x, y, z).
Calculate as.

For example, assuming that the fulcrum O is the origin, the front of the power shovel 10 is in the X direction, and the vertically upper side of the power shovel 10 is in the Y direction, the bending point of the boom 20 is A, and the bending angle of the boom 20 is α. The rotation fulcrum E of the bucket 38 at the tip of the arm 32 can be simplified as shown in FIG. However, L ₁ in FIG.
The distance from the turning fulcrum O of 0 to the bending point A of the boom 20, L
₂ is the distance from the bending point A to the pivot fulcrum D of the arm 32,
L ₃ is the distance from the rotation fulcrum D to the rotation fulcrum E of the bucket 38.

Therefore, E, which is the fulcrum of rotation of the bucket 38,
The X coordinate x _{E of the} point is

## EQU00002 ## x _E = x ₁ + x ₂ + x ₃ = L ₁ cos θ ₁ + L ₂ cos δ + L ₃ sin γ.

By the way, as is clear from FIG.

[Formula 3] δ = θ ₁ + α−π

(4) γ = θ ₁ + α + θ ₂ + (1/2) π−2π = θ ₁ + α + θ ₂ − (3/2) π.

Therefore,

[Expression 5] x _E = L ₁ cos θ ₁ −L ₂ cos (θ ₁ + α) + L ₃ cos (θ ₁ + θ ₂ + α) Similarly, the Y coordinate y of point E
_E is

[Equation 6] y _E = L ₁ sin θ ₁ −L ₂ sin (θ ₁ + α) + L ₃ sin (θ ₁ + θ ₂ + α)

However, the second boom 24 is replaced by the first boom 22.
When the bucket 38 is horizontally rotated with respect to the horizontal direction and the position of the bucket 38 is horizontally displaced from the center line of the upper swing body 18 to cause an offset, L ₂ is as shown in FIG.

## EQU00007 ## L ₂ = L ₂₁ + L ₂₄ + L ₂₃ = L ₂₁ + L ₂₂ cos θ ₃ + L ₂₃ . Here, L ₂₁ is second from the bending point A of the boom 20.
The distance to the rotation fulcrum B of the boom 24, L ₂₂ is the distance between the rotation fulcrums B and C which is the length of the second boom 24, and L ₂₃ is the rotation fulcrum D of the arm 32 from the rotation fulcrum C of the bracket 30. And θ ₃ is the offset angle of the second boom 24. The position z _E of the bucket 38 in the Z direction is the offset amount of the bucket 38,

## EQU8 ## It can be obtained as z _E = L ₂₂ sin θ ₃ .

Therefore, the excavation depth y _d represented by the y coordinate of the tip position of the bucket 38 is represented by the bucket radius r (see FIG. 2).

Y _d = L ₁ sin θ ₁ −L ₂ sin (θ ₁ + α) + L ₃ sin (θ ₁ + θ ₂ + α) −r However, the excavation angle of the bucket 38 is zero, that is, the angle formed by the bucket 38 and the arm 32 is zero.

The excavation depth y thus obtained
_{The d} is output to the display by the control device 60, and is displayed together with the target excavation depth Y ₀ and the excavation allowable range Y ₀ ± Δy ₀ . Then, as shown in FIG. 7A, the control device 60 determines that the excavation depth y _d is within the excavation allowable range Y ₀ ± Δy ₀ , that is, the obtained tip position y _d of the bucket 38 is

When Y ₀ −Δy ₀ <y _d <Y ₀ + Δy ₀ is satisfied, the boom lowering control solenoid valve 68 and the arm excavation control solenoid valve 70 are held open, and the operator operates the boom operation lever. The boom 20 can be lowered by 48a, and the arm 32 can be moved by the arm operating lever 48b. The same applies to the offset operation lever.

On the other hand, the controller 60 causes the tip position of the bucket 38 to reach the lower limit of the allowable excavation range, as shown in FIG.

When y _d ≦ Y ₀ −Δy ₀ , the excavation position y _d is displayed on the display and
The boom lowering control solenoid valve 68 and the arm excavation control solenoid valve 70 are controlled to reduce or block the hydraulic pressure of the boom cylinder 50 and the arm cylinder 52 to prevent the boom 20 from further descending, and the arm 32 excavates. By disabling the operation, excavation below the lower limit of the excavation allowable range is prevented. This makes it possible to avoid excavating deeper than necessary. At this time, a voice or a buzzer may be emitted from the alarm device 66 to notify the operator that the position of the bucket 38 has reached the excavation lower limit.

When the operator is prevented from moving the bucket 38 further downward as described above, the excavation depth y _d
Is reached to the lower limit, the boom operation lever 48a is operated to raise the boom 20. As shown in FIG. 1, the pilot pressure due to the boom raising operation by the boom operation lever 48a directly causes the boom main operation valve 74
Therefore, the bucket 38 can be returned from the lower limit position Y ₀ −Δy _{0 of the} allowable excavation range to the target excavation level Y ₀ . Then, when the excavation depth y _d of the bucket 38 becomes Y ₀ , the control device 10 outputs a signal to the boom lowering control solenoid valve 68 and the arm excavation control solenoid valve 70, and again lowers the boom 20. It enables the excavation operation of the arm 32.

Further, as shown in FIG. 7C, the control device 10 causes the excavation depth y _d of the bucket 38 to reach the upper limit of the excavation allowable range,

[Formula 12] When y _d ≧ Y ₀ + Δy ₀ , the fact that the excavation depth y _d has reached the upper limit Y ₀ + Δy ₀ of the excavation allowable range by a sound or a buzzer from the alarm device 66,
Alternatively, the operator is notified that Y ₀ + Δy ₀ is exceeded. This allows the operator to move the boom operation lever 48
The boom 20 is lowered by operating a so that the excavation depth y _d becomes the target excavation depth Y ₀ .

As described above, in the embodiment, when the excavation depth y _d reaches the upper limit and the lower limit of the permissible excavation range Y ₀ ± Δy ₀ , the operator is notified of that fact. In the excavation work based on the work command, horizontal excavation along the target excavation level can be easily performed with high accuracy. Further, in the embodiment, when the excavation depth y _d reaches the lower limit, the bucket 38 is prevented from going further downward, so that it is necessary to perform an operation such as excavation too deep and backfilling later. There is no need for quick horizontal excavation. Moreover, as compared with a conventional power shovel capable of horizontal automatic excavation, the number of actuators for automatic control and solenoid valves can be reduced, and reliability can be improved.

In the above embodiment, horizontal excavation with a constant excavation depth was described, but it goes without saying that so-called linear excavation in which the excavation surface is inclined can be applied.

[0033]

As described above, according to the present invention, when the operator operates the boom operation lever and the arm operation lever to excavate, the excavation depth deviates from the set reference depth. And, since the operator is informed of that fact, the operator can easily correct the excavation depth to the standard depth, and can perform highly accurate horizontal excavation according to the operator's normal work command. it can.

Further, when the excavation depth reaches the lower limit of the excavation allowable range, the bucket is prevented from excavating further deeply. Therefore, the labor of excavating too deeply and backfilling can be saved, and excavation can be omitted. Work can be done quickly.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a hydraulic circuit of a power shovel according to an embodiment of the present invention.

FIG. 2 is a schematic side view of a hydraulic power shovel according to an embodiment of the present invention.

FIG. 3 is a schematic plan view of a hydraulic power shovel according to an embodiment.

FIG. 4 is a schematic explanatory diagram of a control system according to the embodiment.

FIG. 5 is an explanatory diagram of a method for obtaining an excavation depth by the control device of the embodiment.

FIG. 6 is an explanatory diagram of how to obtain a bucket position when the bucket position of the embodiment is offset with respect to the upper swing body.

FIG. 7 is an explanatory diagram of a straight line excavating method for a power shovel according to an embodiment.

[Explanation of symbols]

10 Power Shovel 84 Arm Main Control Valve 20 Boom 28 Boom Angle Sensor 32 Arm 36 Arm Angle Sensor 38 Bucket 48a Boom Control Lever 48b Arm Control Lever 50 Boom Cylinder 52 Arm Cylinder 54 Bucket Cylinder 60 Bucket Position Calculator (Control Device) 68 Boom Solenoid valve for lowering control 70 Solenoid valve for arm excavation control 74 Boom main operation valve

Claims (3)

[Claims] 1. A straight line excavating method for a power shovel, wherein a bucket provided on a revolving structure via a boom and an arm is moved along a predetermined straight line by operating a boom operating lever and an arm operating lever, A straight line excavating method for a power shovel, wherein the vertical position of the bucket with respect to the straight line is obtained, and when the bucket position reaches the upper and lower limits of a predetermined allowable range, the fact is notified to the operator. 2. The notification to the operator that the bucket position has reached the lower limit of the allowable range is the prevention of the movement of the bucket in the deeper direction. Excavator straight excavation method. 3. A bucket provided on a revolving structure via a boom and an arm, a boom operating lever for operating the boom, an arm operating lever for operating the arm, and an operation amount of the boom and the arm. A plurality of sensor units for detecting, a straight line setting unit for setting a reference straight line for linearly moving the bucket, and based on detection signals of the plurality of sensor units, calculate the position of the bucket, And a controller for outputting a signal informing the operator of the distance of the obtained bucket position in the vertical direction with respect to the reference straight line, and when the distance reaches the upper and lower limits of a predetermined allowable range. Characteristic power shovel.