JPH0745741B2 - Excavation depth control device for hydraulic shovel - Google Patents

Description

The present invention relates to an excavation depth control device for a hydraulic excavator.

(Prior Art) Conventionally, as a means for controlling excavation depth in a hydraulic excavator, for example, one disclosed in Japanese Patent Publication No. 58-36135 is known. This control means sets the excavation depth from the ground, provides angle detectors at the rotating parts of the boom, arm, and bucket to detect the respective rotation angles, and based on each rotation angle, the tip of the bucket from the ground. Is calculated, and the operation of the boom and the arm is controlled so that the difference between the set excavation depth and the distance from the ground to the tip of the bucket is zero.

In the above-mentioned conventional control means, since the excavation depth is set and the bucket tip position is calculated with reference to the ground,
When the ground is tilted with respect to the horizontal plane, the car body is also tilted and accurate excavation control cannot be performed. Especially when the car body is tilted forward, excavate more than the set excavation depth. become. Moreover, in order to detect the angle of the bucket, it is necessary to provide an angle detector at the pivotal support for the tip of the arm of the bucket, and the environment in which this bucket angle detector is used is poor, and the shock, vibration, and the like during excavation and dumping by the bucket, There is a problem that a special and expensive detector is required in consideration of waterproofing, and that the detector is liable to fail, there is a risk that it will lose control, and the reliability is poor.

(Object of the invention) The present invention has been made in order to solve such a problem, regardless of the inclination of the ground, the excavation depth can be appropriately controlled, and the failure of the detector is small. The present invention provides an excavation depth control device for a hydraulic excavator, which enables highly reliable control.

(Structure of the Invention) The structure of the present invention will be described with reference to the functional block diagram of FIG. 1 (including the means of the embodiment).

The present invention relates to a setting means 10 for setting a function fixed point O at the front part of a traveling body of a hydraulic excavator, a setting means 11 for setting a digging depth H to a target digging surface based on the function fixed point O, and a vehicle body inclination. Detection means 12 for detecting the angle α, detection means 13 for detecting the rotation angle β of the boom, detection means 14 for detecting the rotation angle γ of the arm, the setting means 10, 11 and the detection means 12, 1
Calculate the working inclination angle η of the reference straight line connecting the boom foot and the arm point based on the output signals from 3,14 and the height from the ground to the boom foot, the boom length, the arm length, and the bucket turning radius. A calculation means 22, a calculation means 23 for calculating the maximum excavation depth I based on the boom foot according to the work inclination angle η, and a set excavation depth H from the function fixed point O to the target excavation surface are boomed. Calculation means 24 for calculating the target excavation depth J based on the foot, comparison means 25 for comparing the maximum excavation depth I with the target excavation depth J, and the maximum excavation depth I for the target excavation depth J Control means 29, 30 are provided to prevent the boom and the arm from operating in a direction in which the vertical distance between the arm point and the target excavation surface becomes smaller than the bucket rotation radius when the arm angle becomes J. Is characterized by Than it is.

With this configuration, the operator only needs to set the function fixed point O on the front part of the traveling body and the excavation depth H based on the function fixed point O according to the situation of the work site, and the set value and the inclination angle α of the vehicle body. , The rotation angle γ of the boom and the rotation angle δ of the arm are detected and controlled so that the distance from the target excavation surface to the arm point corresponding to the target excavation depth does not become smaller than the bucket rotation radius. It is possible to reliably prevent the target excavation surface from being excavated by the tip.

(Embodiment) FIG. 2 shows an example of a hydraulic excavator equipped with the device of the present invention, and shows each element of setting, detection, and calculation for its control. This hydraulic excavator is for traveling body 1
A boom 3 is rotatably provided on a revolving structure 2 provided at an upper part of the arm 3, an arm 4 is rotatably provided at a tip of the boom 3, and a bucket 5 is rotatably provided at a tip of the arm 4, The boom 3, the arm 4, and the bucket 5 are rotated by the boom cylinder 6, the arm cylinder 7, and the bucket cylinder 8.

In the above hydraulic excavator, reference points, dimensions and angles of each part are determined as follows.

O: Fixed point X: Boom foot (Center of rotation of boom 3) Y: Boom point (Center of rotation of arm 4) Z: Arm point (Center of rotation of bucket 5) V: Tip of bucket 5 W: Boom foot X to ground The line that goes vertically to 9 is the ground 9
A: Boom foot X height from the ground B: Boom length (distance between boom foot X and boom point Y) C: Arm length (distance between boom point Y and arm point Z) D: Bucket turning radius (turning radius of bucket tip P around arm point Z) E: Distance from point W to fixed point O H: Set excavation depth I: Maximum excavation depth J: Target excavation depth K: Target excavation surface α: Tilt angle of vehicle body with respect to horizontal plane (angle formed by ground and horizontal plane) β: Rotation angle of boom 3 (angle with respect to horizontal line) γ: Rotation angle of arm 4 (angle with respect to horizontal line) Of the above dimensions and angles, The height A, the boom length B, the arm length C, and the bucket turning radius D are known constants determined by the model. Further, the distance E from the point W to the function fixed point O and the set excavation depth H are arbitrarily set by the operator according to the situation of the excavation site. On the other hand, the vehicle body inclination angle α, the boom rotation angle β, and the arm rotation angle γ are detected by the angle detector.

Now, in FIG. 2, the angle formed by the boom 3 and the arm 4 ∠XY
If Z is ε, ε is the boom rotation angle β and the arm rotation angle γ.
Is calculated by using ε = 2π−γ− (π−β) = π−γ + β.

In addition, the distance between the boom foot X and the arm point Z is G
Then, G is calculated from ΔXYZ using the known boom length B and arm length C and the angle ε as follows.

Next, with the boom foot X as the center, the boom point Y
Let θ be the angle ∠YXZ formed by
Is calculated from ΔXYZ using the arm length C, the angle ε and the distance G obtained by the above equations as follows.

C / sinθ = G / sinε ∴θ = sin ^-1 [(C / G) sinε] Here, a straight line connecting the boom foot X and the arm point Z is defined as a reference straight line a, and the boom foot X of this reference straight line a is If the inclination angle with respect to the reference horizontal line is the work inclination angle η, the work inclination angle η is calculated as follows.

η = β + θ Further, the work inclination angle η changes depending on the work situation, and the maximum excavable depth of the shovel according to the work inclination angle η is I based on the boom foot X. Expressing it, I is calculated as follows using G and the work inclination angle η and the bucket turning radius D.

I = Gsinη + D .. Thus, the maximum excavation depth I of the shovel according to the work inclination angle η with respect to the boom foot X is the known boom length B, arm length C, and bucket rotation from the above formulas. It can be calculated using the radius D and the detected values of the boom rotation angle β and the arm rotation angle γ.

On the other hand, the distance between the boom foot X and the function fixed point O is F, and the angle between the boom foot X and the function fixed point O and the ground 9 is ∠XO
When W is δ, F and δ are calculated from ΔXOW using the vehicle body height A and the set distance E as follows.

δ = tan ⁻¹ (A / E) …… Next, when the target excavation depth of the shovel is represented by J with the boom foot X as the reference, the target excavation depth J is the set excavation depth with reference to the function fixed point O. The height H, the distance F obtained by the above equation, the vehicle body inclination angle α which is a detected value, and the δ obtained by the above equation are used to calculate as follows.

J = H + Fsin (α + δ) ...... Thus, the target excavation depth J of the shovel based on the boom foot X is the known vehicle height A from the above formulas.
Can be calculated using the set distance E, the set excavation depth H, and the detected vehicle body inclination angle α and boom rotation angle β.

Then, the maximum excavation depth I corresponding to the work inclination angle η,
By comparing with the target excavation depth J, it is possible to know whether the arm point Z is in the safe area or the dangerous area.

That is, when the maximum excavation depth I is smaller than the target excavation depth J (I <J), the arm point Z is in a region away from the target excavation surface K by a distance equal to or greater than the bucket rotation radius D, and is in the safety region. It can be said that there is. Therefore, even if the bucket 5 is rotated in the scraping direction at that position, there is no risk that the bucket tip P bites into the target excavation surface K, and the boom 3, the arm 4, and the bucket 5 can be freely operated.

However, when the maximum excavation depth I is greater than or equal to the target excavation depth J (I
≧ J) is when the distance between the arm point Z and the target excavation surface K is less than or equal to the bucket turning radius D, and when the bucket 5 is rotated at this position, the bucket tip P may bite into the target excavation surface K. Therefore, it can be said that this is a dangerous area.

In such a case, the following determination is made based on the value of the arm rotation angle γ.

When γ <(π / 2): Stop pulling in the arm and lowering the boom. When γ> (π / 2): Stop pushing out the arm and lowering the boom. When γ = (π / 2): Lower the arm. By this, the arm point Z is prevented from approaching the target excavation surface K side, and the arm point Z and the target excavation surface K are prevented.
Is prevented from becoming smaller than the bucket rotation radius D, and the bucket tip P is prevented from biting into the target excavation surface K.

Next, the above calculation and control will be described with reference to the functional block diagram of FIG.

First, the operator determines a function fixed point O according to the work situation at the site, sets the distance E from the point W to the function fixed point O in the function fixed point setting means 10 on the basis of the function fixed point O, and also sets the function fixed point 0. The set excavation depth H based on is set in the excavation depth setting means 11. On the other hand, the vehicle body tilt angle detection means 12
The vehicle body inclination angle α is detected by the boom rotation angle detection means.
Beam rotation angle β by 13 and arm rotation angle detection means 14
And the arm rotation angle γ is detected. In this case, as the vehicle body inclination angle detecting means 12, a detector such as a gyroscope or a pendulum provided on the vehicle body is used. For the boom rotation angle detection means 13 and the arm rotation angle detection means 14, detectors such as potentiometers provided at the boom foot X and the boom point Y are used. However, since the actual detected values by the rotation angle detecting means 13 and 14 are based on the vehicle body and the boom point Y, they are corrected by a correction means (not shown) to a numerical value based on the horizontal line.

Then, the setting means 10, 11 and the detection means 12, 13, 1
The output signals E, H and α, β, γ from 4 are controlled by the controller 20.
Input to the work inclination angle calculation means 22 via the input / output device 21.
And the maximum excavation depth calculation means 23 and the target excavation depth calculation means 24. Here, the maximum excavation depth I (above equation) corresponding to the work inclination angle η is calculated by the calculation means 22 and 23, and the target excavation depth J is calculated by the calculation means 24.
(Above-formula) is calculated.

Next, the comparing means 25 compares the maximum excavation depth I with the target excavation depth J, and the determining means 26 determines the maximum excavation depth I.
Is smaller than the target excavation depth J (I <J), and when I <J, the arm point Z is in the safe area, and therefore the boom control means 29 and the arm are controlled via the signal generating means 28. A free activation signal is sent to each control means 30.

On the other hand, when I ≧ J, since the arm point Z is in the dangerous area, the next arm rotation angle determination means 28 outputs a control signal corresponding to the above-mentioned a to c based on the value of the arm rotation angle γ. It is sent to the boom control means 29 and the arm control means 30 via 28. The machine can move to the safe side.

Next, a boom and arm hydraulic circuit for performing the above control will be described with reference to FIG.

In FIG. 4, when the arm lever (not shown) is operated, the variable pressure reducing valves 31a, 31b provided on the arm operation valve 31 are operated.
The secondary pressures Pa ₁ and Pa ₂ are introduced to the secondary side of the
The arm directional control valve 32 is switched to the left or right by a ₁ and Pa ₂ , the supply and discharge of pressure oil from the main pump 33 to the arm cylinder 7 is controlled, and the arm cylinder 7 is expanded and contracted to perform arm pushing or drawing. Be seen. When a boom lever (not shown) is operated, the secondary pressures Pb ₁ and Pb are applied to the secondary side of the variable pressure reducing valves 34a and 34b provided on the boom operation valve 34.
b ₂ is introduced, and the secondary pressures Pb ₁ and Pb ₂ switch the boom directional control valve 35 to the left or right, and the main pump
The supply and discharge of pressure oil to and from the boom cylinder 6 is controlled from 36, and the boom cylinder 6 is expanded and contracted to raise or lower the boom.

In the hydraulic circuit, the variable pressure reducing valve 31a for pushing out the arm is used.
Solenoid valves 37, 38, 39 are respectively provided in the secondary side circuit and the secondary side circuit of the arm retracting variable pressure reducing valve 31b and the secondary circuit of the boom lowering variable pressure reducing valve 34b.

Now, when the arm push-out variable pressure reducing valve 31a is operated to switch the arm directional control valve 32 to the left position by the secondary pressure Pa ₁ , the arm cylinder 7 is extended and the arm push-out valve is operated. When is turned on, the secondary pressure is not sent from the variable pressure reducing valve 31a to the directional control valve 32, the directional control valve 32 is returned to the neutral position, the arm cylinder 7 is stopped, and the arm extrusion is stopped. Also, if the solenoid valves 38, 39 are turned on during the work of retracting the arm and lowering the boom,
These operations are stopped by the same operation as above. However, raising the boom is always on the safe side, so
It is not necessary to perform the above control.

The solenoid valves 37, 38, 39 are ON / OFF controlled by a signal from the controller 20, and the controller 20 has the functions shown in FIG. 1, the vehicle body inclination angle α, the boom rotation angle β, and the arm. The rotation angle γ, the set distance E, and the set excavation depth H are input, and ON-OFF signals for the solenoid valves 37, 38, 39 are output based on these input signals.

In this way, the secondary pressure for switching the arm directional control valve 32 and the boom directional control valve 35 is turned on and off by the solenoid valves 37, 38, 39 operated by the signal from the controller 20 to prevent malfunction. , The reliability of control is improved.

Next, the control by the controller 20 will be described with reference to the flowchart of FIG.

First, step S ₁ in the configuration digging depth H is read in, Step S ₂ at a set distance E is read in by the function fixed point O from the point W, the vehicle body inclination angle α is read in at Step S _3, step
The boom rotation angle β is read in S ₄ , and the arm rotation angle γ is read in step S ₅ . Next, in step S ₆ , the maximum excavation depth I corresponding to the work inclination angle η with the boom foot X as a reference.
Is calculated and the target excavation depth J based on the boom foot X is calculated in step S ₇ , and then it is determined in step S ₈ whether I <J. If YES in step S _8, the process returns to the start.

When Step S ₈ NO of (I ≧ J) the arm rotational angle gamma is in the next step _{S 9, γ <(π /} 2) , it is determined whether. If YES in step S ₉ proceeds to step S _11, after the signal to turn ON the solenoid valve 38 of the arm retraction stop ie Figure 3 is outputted, the process proceeds to step S _13. In step S ₁₀ when the NO gamma =
(Π / 2) whether it is discriminated, if YES then the process proceeds to step S _13, when the NO is output a signal to turn ON the solenoid valve 37 of the arm extrusion stop ie Figure 3 in step S _12, step S
Proceed to ₁₃ . Then, the boom-down stop or signal to turn ON the solenoid valve 39 of FIG. 3 is output in step S _13, then the end whether it is discriminated in step S _14, when the NO is returned to the start, the YES When time ends control ends.

As a result, the distance from the target excavation surface K to the arm point Z is controlled so as not to be smaller than the bucket rotation radius D, and the bucket excavation tip P is prevented from excavating the target excavation surface K.

(Effects of the Invention) As described above, according to the present invention, the operator only sets the function fixed point O on the front part of the traveling body and the excavation depth H based on the function fixed point O, and the set value and the inclination angle α of the vehicle body are set. , The rotation angle β of the boom and the rotation angle γ of the arm can be controlled so that the distance from the target excavation surface to the arm point is not smaller than the bucket rotation radius, and the target excavation surface is excavated by the bucket tip. Can be reliably prevented,
Accurate drilling depth control is possible. Moreover, even when the ground is inclined, by setting the function fixed point and the target excavation depth according to the situation of the work site, optimum control is always performed and the control accuracy can be improved. The work safety and the versatility of the device can be improved. further,
Since it is not necessary to provide an angle detector on the pivot portion of the bucket, the number of detectors can be reduced as compared with the conventional device, and the number of failures is small and highly reliable control can be performed.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the device of the present invention, FIG. 2 is a side view showing an example of a hydraulic excavator equipped with the device of the present invention, and FIG. 3 is a hydraulic circuit diagram of a boom and an arm in the device of the present invention. FIG. 4 is a control flowchart. 1 ... traveling body, 3 ... boom, 4 ... arm, 5 ... bucket,
10 ... Function fixed point setting means, 11 ... Excavation depth setting means, 12 ... Vehicle inclination angle setting means, 13 ... Boom rotation angle detecting means, 14 ... Arm rotation angle detecting means, 20 ... Controller, 22 ... Work inclination angle calculating means , 23 ... Maximum excavation depth calculation means, 24 ... Target excavation depth calculation means, 25 ... Comparison means, 26 ... Discrimination means, 27 ... Arm rotation angle discrimination means, 28 ... Signal generation means, 29 ... Boom control means, 30 ... Arm control means, 37, 38, 39 ... Solenoid valve, α ... Vehicle body tilt angle, β ... Boom rotation angle, γ ... Arm rotation angle, O ...
Function fixed point, E ... set distance, η ... work inclination angle, I ... maximum excavation depth, J ... target excavation depth.

Claims (1)

[Claims] 1. A setting means for setting a function fixed point on a front part of a traveling body of a hydraulic excavator, a setting means for setting a digging depth up to a target digging surface with reference to the function fixed point, and detecting an inclination angle of a vehicle body. Detecting means, detecting means for detecting the rotation angle of the boom, detecting means for detecting the rotation angle of the arm, output signals from the setting means and the detecting means, height from the ground to the boom foot, boom length Based on the arm length and the bucket turning radius, the work inclination angle of the reference straight line connecting the boom foot and the arm point is calculated, and the maximum excavation depth based on the boom foot is calculated according to the work inclination angle. A calculating means for calculating, a calculating means for calculating the set excavation depth from the function fixed point to the target excavation surface to a target excavation depth based on the boom foot, and a ratio of the maximum excavation depth to the target excavation depth. And the boom and the arm in the direction in which the vertical distance between the arm point and the target excavation surface becomes smaller than the bucket rotation radius according to the arm rotation angle when the maximum excavation depth reaches the target excavation depth. An excavation depth control device for a hydraulic excavator, which is provided with a control means for preventing operation.