JPH0424494B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bucket angle control method for preventing earth and sand loaded on a bucket of a loading hydraulic excavator from falling.

To prevent the loaded earth and sand from falling when lifting the boom of a loading hydraulic excavator,
During the operation of the boom or arm, it is necessary to keep the angle of the bucket from the horizontal plane, that is, the absolute bucket angle, constant, and such operations require advanced technology and a great deal of effort. In order to solve this problem, the absolute bucket angle can be automatically kept constant without the need for bucket operation.There are three methods for this: a link method, a hydraulic method, and an electrical method. Several methods have been proposed.

In these proposals, as the value of the absolute bucket angle to be kept constant, there are some that always take a pre-given constant value, and others that take the absolute bucket angle at the time when the operation of the boom or arm is started as a constant value.

However, in the former case, the bucket absolute angle remains a certain value regardless of the operator's will, so it is not possible to change the bucket absolute angle depending on the soil loading status of the bucket, and the bucket cannot be adjusted while the boom is being raised. There are drawbacks such as the inability to carry out raking and excavation by operation, which is not preferable in terms of operability.

In the latter case, the defect of the former can be compensated for by adding a bucket operation to correct the absolute bucket angle, but if the excavation ends when the bucket is near or below the ground surface, When the bucket is triggered, the bucket cannot be raised sufficiently due to link constraints. Therefore, maintaining the absolute angle of the bucket has the disadvantage that the bucket tilts too far forward. Further, even if only the boom or arm is operated during excavation, the bucket angle control is performed, which deteriorates the operability for excavation.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and provides for controlling the bucket angle in accordance with the will of the operator and when the height of the bucket from the reference surface exceeds a predetermined value. purpose.

In order to achieve this object, the present invention includes a boom that is pivotally connected to a main body and is moved up and down by a boom cylinder, an arm that is pivotally connected to the tip of this boom and is swung by an arm cylinder, and In a bucket angle control method for a loading shovel having a bucket which is pivotally connected and rotated by a bucket cylinder, the height of the bucket from a reference plane is set in advance in consideration of preventing a loaded object from falling from the bucket. is greater than the set value, and when a condition is established in which at least one of the boom operation lever and the arm operation lever is operated and the bucket operation lever is not operated, the bucket cylinder is operated using the absolute bucket angle signal at that time as the target value. It is configured to control the operation.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a diagram showing the front part of a loading hydraulic excavator. In the figure, 1 is the main body of a hydraulic excavator, 2 is a boom pivotally connected to the main body 1, 3 is an arm pivotally connected to the tip of the boom 2, 4 is a bucket pivotally attached to the tip of the arm 3, and 5 is the boom 2. A boom cylinder that looks upward; 6 is an arm cylinder that swings the arm 3; 7 is a bucket cylinder that rotates the bucket 4; 8 detects the angle of the boom 2 with respect to the main body 1, that is, the boom angle, and generates a boom angle signal α.
An angle meter 9 detects the angle of the arm 3 with respect to the boom 2, that is, the arm angle, and outputs an arm angle signal β; 10 detects the angle of the bucket 4 with respect to the arm 3, that is, the bucket angle; It is an angle meter that outputs a signal γ.

FIG. 2 is a diagram showing a control device for carrying out the bucket angle control method for a loading shovel according to the present invention. In the figure, 11 is a hydraulic pump, 12 is an electromagnetic control valve provided between the hydraulic pump 11 and the bucket cylinder 7, 13, 14, and 15 are respectively a boom operating lever, an arm operating lever, and a bucket operating lever, and 16 is an angle. An adder 17 calculates the total value of the signals α, β, and γ, that is, the bucket absolute angle signal θ, and 17 stores the output signal of the adder 16 when the switch 18 is turned on, that is, the bucket absolute angle signal θ, as a target value θ ₀ . 19 is an adder/subtractor that calculates the difference between the output signal θ ₀ of the storage device 17 and the output signal θ of the adder 16, that is, an angular deviation signal Δγ; 20 is a signal obtained by multiplying the output signal of the adder/subtractor 19 by a coefficient; a coefficient unit that outputs kΔγ; 21 is a switch provided between the coefficient unit 20 and the adder/subtractor 25;
22 is a manual operation device that outputs a manual operation signal according to the amount of operation of the bucket operation lever 15; 23 is an adder that calculates the sum of the boom angle signal α and the arm angle signal β; 24 is the output signal α+β of the adder 23; 25 is the output signal of the coefficient multiplier 20.
An adder for calculating the difference between kΔγ and the output signal α〓+β〓≡−γ〓 of the differentiator 24, 26 an adder for calculating the sum of the output signal of the adder/subtractor 25 and the output signal of the manual operating device 22, 27 a A switch 28 provided between the adder/subtractor 25 and the adder 26 is an amplifier for amplifying and compensating the output signal of the adder 26 and controlling the electromagnetic control valve 12 to provide the speed of the bucket cylinder 7. ,
29, 30, 31 are operating levers 13, 1, respectively.
4 and 15 are lever operation detectors that detect whether or not the operation levers 13 and 15 are operated, respectively.
When 14 and 15 are operated, operation detection signals a, b,
Output c. 32 is a height calculator which inputs the angle signals α, β, and γ and calculates the height of the bucket 4 from the reference value; for example, as shown in FIG.
The distance between the main body 1 pivot point P ₀ and the boom 2 pivot point P ₁ of the arm 3 is l ₁ , the distance between the pivot point P ₁ and the arm pivot point P ₂ of bucket 4 is l ₂ , the pivot point P ₂ and bucket tip point
If the distance of P ₃ is l ₃ and the height of pivot point P ₀ from G/L is h ₀ , then the height h ₃ of bucket tip point P ₃ is: h ₃ = h ₀ + l ₁ sin α − l ₂ sin It is expressed as (α+β) +l ₃ sin (α+β+γ), and the height h ₂ of pivot point P ₂ can be calculated as h ₂ =h ₀ +l ₁ sin α−l ₂ sin (α+β).

33 is the signal a of the lever operation detectors 13 to 15;
This is a control command device that inputs signals b, c and the output signal h of the height calculator 32, and outputs control signals T and S for the switches 18, 21, and 27.

The control signal T is generated when at least one of the boom operation lever 13 and the arm operation lever 14 is operated and the bucket height h (for example, the height h ₃ of the bucket tip point P ₃ ) is larger than the set value h _c is output,
The control signal S is output when the control signal T is output and the bucket operating lever 15 is not operated. That is, if expressed as a logical formula, T=(a+b)·(h>h _c ) S=T·=(a+b)··(h>h _c ).

When the control signal T is output, the switch 27 is turned on, and when the control signal S is output, the switch 1 is turned on.
8 and 21 are turned on.

In the above-mentioned control device, only the bucket operating lever is operated or the bucket height h
is less than the set value h _c and when at least one of the boom operation lever 13 and the arm operation lever 14 and the bucket operation lever 15 are operated simultaneously, the control signals T and S from the control command device 33
is not output, so switches 18, 21, 27
are both off, the electromagnetic control valve 12 is switched in response to the manual operation signal of the bucket operation lever 15, and the speed of the bucket cylinder 7, that is, the angular velocity of the bucket 4, has a value corresponding to the amount of operation of the bucket operation lever 15. .

Also, if the bucket height h is greater than the set value h _c ,
If at least one of the boom operation lever 13 and the arm operation lever 14 is operated and the bucket operation lever 15 is not operated, the control signals T and S are output from the control command device 33, so the switch 1
8, 21, and 27 are all turned on. Therefore, the speed of the bucket cylinder 7, that is, the angular velocity of the bucket 4, has a value corresponding to the output γ〓 _r +kΔγ of the adder 26.

By the way, the absolute angle Θ (see FIG. 1) of the bucket belt 4 is expressed by the following equation, where A, B, and Υ are the boom angle, arm angle, and bucket angle, respectively.

Θ=A+B+Υ+C Here, C is a constant value determined by the shape of the bucket 4, etc. Therefore, since the bucket absolute angle signal = α + β + γ has a value according to the bucket absolute angle Θ, in order to keep the bucket absolute angle Θ constant, it is sufficient to keep the bucket absolute angle signal θ constant.

When the bucket absolute angle Θ is constant, that is, when the absolute angle signal θ is constant,
Differentiating this equation gives the following equation.

γ〓=−α〓−β〓 Therefore, if the angular velocity of the bucket 4 is set as a value according to the bucket control speed signal −α〓−β〓≡γ〓 _r ,
The bucket absolute angle Θ becomes a constant value. And the influence of disturbances, for example, bucket 4 hits an impact object,
When the absolute angle Θ fluctuates from the start of operation of the operating lever 13 or 14 due to the characteristics of the electromagnetic control valve 12 or changes in the viscosity, temperature, or pressure of the pressure oil, kΔr is adjusted according to the amount of variation. The angular velocity of the bucket 4 is corrected by the speed, and the absolute angle Θ of the bucket 4 is kept constant.

Next, when the bucket control lever 15 is also operated in this state, a control signal T is sent from the control command device 33.
Since only the signal is output, the switches 18 and 21 are turned off. Therefore, since the bucket 4 rotates at an angular velocity according to the signal obtained by adding the bucket manual operation signal, which is the output signal of the manual operation device 22, to the control speed signal γ〓 _r , the absolute angle Θ of the bucket 4 is determined by the bucket operation. Correction can be made at a speed corresponding to the amount of operation of the lever 15.

Furthermore, when the bucket control lever 15 is returned to the neutral position in this state, the control signal S is output from the control command device 33 and the switches 18 and 21 are turned on. θ is stored as the target value θ ₀ and the bucket 4 holds the absolute angle Θ corresponding to this target value θ ₀ from then on.

Generally, during excavation, the bucket height h is smaller than the set value _hc , so the control command signals T and S are not output from the control command device 33, so the bucket angle is not controlled, and the operability during excavation is good.

When excavation is finished in this state and the bucket 4 is raised to load earth and sand, the bucket height h below the ground surface is still smaller than the set value h _c . Then, from this state, the boom is raised, the bucket height h increases, and the bucket absolute angle Θ also increases, h
>h _c , the bucket absolute angle signal θ at that point is stored in the storage device 17 as the target value θ ₀ , and from then on, the bucket absolute angle Θ is controlled to be constant according to this target value θ ₀ . be done. Note that the setting value h _c preset in the control command device 33 described above
is set in accordance with a preferable bucket absolute angle Θ that prevents the earth and sand loaded on the bucket 4 from falling.

Furthermore, if the absolute angle Θ of the bucket is corrected using the bucket operating lever 15 at the time when h>h _c , the corrected bucket absolute angle signal θ is set to the target value θ ₀ , so that the loading of earth and sand is It can be corrected to the optimal bucket absolute angle Θ according to the situation.

According to the present invention described above, the following effects can be achieved.

(1) After excavation, the bucket can be raised below the ground surface to load earth and sand, and even when the boom or arm is raised, a preferable angle of the bucket can be maintained so that the earth and sand will not fall.

(2) Even when raising the boom or arm, manual correction of the bucket angle using the bucket control lever is easy and provides a good operating feel.

(3) Bucket angle control is not performed during normal excavation, improving operability during excavation.

[Brief explanation of drawings]

1 to 3 relate to an embodiment of the present invention, FIG. 1 is a diagram showing the front part of a loading hydraulic shovel, and FIG. 2 is a control device for implementing a bucket angle control method for a loading shovel. FIG. 3 is a diagram for explaining the calculation of bucket height. 1... Loading shovel body, 2... Boom, 3... Arm, 4... Bucket, 5... Boom cylinder, 6... Arm cylinder, 7... Bucket cylinder, 8, 9, 10... Angle meter, 12...
... Solenoid control valve, 13 ... Boom operation lever, 14
...Arm operating lever, 15...Bucket operating lever, 16...Adder for calculating the bucket absolute angle signal θ, 17...Storage device (memorizes the target value θ ₀ of the bucket absolute angle signal θ), 18, 21, 27...
Switch, 22... Manual operating device, 24... Differentiator, 32... Height calculator, 33... Control command device.

Claims (1)

[Claims] 1. A boom that is pivotally attached to the main body and is moved up and down by a boom cylinder, an arm that is pivoted to the tip of this boom and swung by an arm cylinder, and an arm that is pivoted to the tip of this arm and rotated by a bucket cylinder. In a method for controlling a bucket angle of a loading shovel having a bucket, the height of the bucket from a reference surface is greater than or equal to a preset value that is set in consideration of preventing a loaded object from falling from the bucket,
Further, when a condition is established in which at least one of the boom operating lever and the arm operating lever is operated and the bucket operating lever is not operated, the bucket absolute angle signal at that time is used as a target value to control the operation of the bucket cylinder. A loading shovel bucket angle control method.