JP6851701B2 - Excavator - Google Patents

Description

The present invention relates to excavators.

The excavator includes a traveling body called a crawler, an upper swivel body, a swivel device that rotates the upper swivel body with respect to the traveling body, and an attachment attached to the upper swivel body. The attachment includes a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder for driving them. Each cylinder can be controlled by lever operation by the driver (operator).

When the operator suddenly moves the boom shaft, arm shaft, bucket shaft, or swivel shaft while the bucket contains a load such as earth and sand or rubble, the load spills out of the bucket (called sediment overflow). Sediment overflow is a factor that deteriorates work efficiency because it requires rework.

Japanese Unexamined Patent Publication No. 2008-267760

However, the conventional prevention of sediment overflow is such as suppressing sudden changes in turning torque, limiting turning acceleration based on the operator's settings, and gently stopping the turning axis so that the impact of the attachment is reduced. Although it was effective against the sediment overflow that accompanies it, there was room for improvement because no consideration was given to the sediment overflow due to the operation of the attachment.

Further, the prior art is based on the bucket angle constant control that automatically keeps the bucket posture horizontal with respect to the ground, and does not consider the mechanical movement of the bucket.

The present invention has been made in view of the above problems, and one of the exemplary purposes of the present invention is to provide a shovel capable of suppressing sediment overflow.

1. 1. Some aspects of the invention relate to excavators. The excavator has a crawler, an upper swivel body, a swivel device that rotates the upper swivel body with respect to the crawler, a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder, and is an attachment attached to the upper swivel body. And a controller that limits the movement of at least one of the attachment and the upper swing body so that the force applied to the load in the bucket during the operation of the attachment does not exceed the stable threshold of the load.

According to this aspect, the overflow of earth and sand can be suppressed by considering the force applied to the load during the operation of the attachment.

The controller may consider the resultant force of the force generated by the operation of the attachment and the force generated by the operation of the swivel device. As a result, it is possible to suppress the overflow of earth and sand when the turning motion and the bending / stretching motion of the attachment are performed at the same time.

The controller may suppress the acceleration of at least one of the swivel shaft, the boom shaft, the arm shaft, and the bucket shaft.

The controller may suppress the acceleration of all the swivel shafts, boom shafts, arm shafts, and bucket shafts.

The controller may preferentially suppress the acceleration of the axis that predominantly acts in the direction in which the load overflows the bucket.

The controller may suppress the speed of at least one of the swivel shaft, the boom shaft, the arm shaft, and the bucket shaft.

The controller may suppress jerk on at least one of a swivel axis, a boom axis, an arm axis, and a bucket axis.

The threshold value may depend on the attitude of the attachment.

2. Some aspects of the invention relate to excavators. The excavator has a crawler, an upper swivel body, a swivel device that rotates the upper swivel body with respect to the crawler, a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder, and is an attachment attached to the upper swivel body. And a controller that tilts the bucket in a direction in which the reference plane of the bucket approaches the acceleration direction generated on the load in the bucket and the plane perpendicular to the plane when the bucket is moved.

Another aspect of the invention is also an excavator. This excavator has a crawler, an upper swivel body, a swivel device for rotating the upper swivel body with respect to the crawler, a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder, and is attached to the upper swivel body. It comprises an attachment and a controller that tilts the bucket so that the normal force of the load in the bucket increases while the swivel device and at least one of the attachments are in motion.

Yet another aspect of the invention is also an excavator. This excavator has a crawler, an upper swivel body, a swivel device for rotating the upper swivel body with respect to the crawler, a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder, and is attached to the upper swivel body. It includes an attachment and a controller that tilts the bucket so that the force acting parallel to the reference plane of the bucket is small with respect to the load in the bucket while the swivel device and at least one of the attachments are in motion.

It should be noted that any combination of the above components or components and expressions of the present invention that are mutually replaced between methods, devices, systems, and the like are also effective as aspects of the present invention.

According to the present invention, sediment overflow can be suppressed.

It is a perspective view which shows the appearance of the excavator which is an example of the construction machine which concerns on embodiment. It is a figure which shows typically the coordinate system of an excavator. It is a block diagram of one Example of the excavator which concerns on 1st Embodiment. It is a block diagram of one Example of the excavator which concerns on 1st Embodiment. It is a block diagram of one Example of the excavator which concerns on 1st Embodiment. It is a block diagram of one Example of the excavator which concerns on 1st Embodiment. It is a figure which shows typically the bucket and the load. It is a figure which shows the operation of the excavator in the 1st use form. It is a figure which shows the operation of the excavator in the 2nd use form. It is a block diagram of a controller. It is a block diagram of one Example of the excavator which concerns on 2nd Embodiment. It is a figure which shows typically the bucket and the load. 13 (a) and 13 (b) are diagrams schematically showing bucket angle control by a controller. 14 (a) and 14 (b) are diagrams showing a first usage mode of a shovel in which bucket angle control is effective. It is a figure which shows the 2nd use form of the excavator which bucket angle control is effective. It is a block diagram of a controller. It is a block diagram of the electric system and the hydraulic system of the excavator which concerns on the 1st modification. It is a block diagram of the electric system and the hydraulic system of the excavator which concerns on the 2nd modification.

Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and redundant description will be omitted as appropriate. Further, the embodiment is not limited to the invention but is an example, and all the features and combinations thereof described in the embodiment are not necessarily essential to the invention.

In the present specification, the "state in which the member A is connected to the member B" means that the member A and the member B are physically directly connected, and that the member A and the member B are electrically connected to each other. It also includes the case of being indirectly connected via other members, which does not substantially affect the connection state, or does not impair the functions and effects performed by the combination thereof.

FIG. 1 is a perspective view showing the appearance of the excavator 1, which is an example of the construction machine according to the embodiment. The excavator 1 mainly includes a crawler (also referred to as a traveling mechanism) 2 and an upper swivel body (hereinafter, also simply referred to as a swivel body) 4 rotatably mounted on the crawler 2 via a swivel device 3. There is.

The swing body 4 is attached with a boom 5, an arm 6 linked to the tip of the boom 5, and a bucket 10 linked to the tip of the arm 6. The bucket 10 is a facility for capturing suspended loads such as earth and sand and steel materials. The boom 5, arm 6, and bucket 10 are collectively referred to as an attachment 12, and are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively. Further, the swivel body 4 is provided with a power source such as a driver's cab 4a for accommodating a driver who operates a position of a bucket 10, an excitation operation and a release operation, and an engine 11 for generating flood control. The engine 11 is composed of, for example, a diesel engine.

FIG. 2 is a diagram schematically showing the coordinate system of the excavator 1. _{In the excavator 1, angular coordinates θ 1 to θ 3} indicating the positions of the boom 5, the arm 6, and the bucket 10 are defined. θ ₁ is the positional relationship between the boom and the swivel body 4, θ ₂ is the positional relationship between the boom 5 and the arm 6, and θ ₃ is the positional relationship between the arm 6 and the bucket 10. How are they defined? It doesn't matter. The combination of θ _{1 to θ 3} is simply indicated as θ, and the position (posture) of the entire attachment 12 is indicated.

Further, φ indicates the turning angle of the turning device 3. R (θ ₁ , θ ₂ , θ ₃ ) is the distance between the origin O of the attachment 12 and the reference position X of the bucket 10. R is represented by a function based on the mechanism of the attachment 12, and can be calculated from the _{position information θ 1 to θ 3.} R (θ ₁ , θ ₂ , θ ₃ ) is also simply referred to as R (θ). Further, the origin of the attachment 12 and the reference position of the bucket 10 may be appropriately determined.

(First Embodiment)
3 to 6 are block diagrams of an electric system, a hydraulic system, and the like of the excavator 1 according to the first embodiment. In FIGS. 3 to 6, the system for mechanically transmitting power is shown by a double line, the hydraulic system is shown by a thick solid line, the flight control system is shown by a broken line, and the electric system is shown by a thin solid line. Although the hydraulic excavator will be described here, the present invention can also be applied to a hybrid excavator that uses an electric motor for turning.

The engine 11 as a mechanical drive unit is connected to the main pump 14 and the pilot pump 15 as a hydraulic pump. A control valve 17 is connected to the main pump 14 via a high-pressure hydraulic line 16. In addition, two hydraulic circuits for supplying hydraulic pressure to the hydraulic actuator may be provided, in which case the main pump 14 includes two hydraulic pumps. In this specification, for the sake of facilitation of understanding, the case where the main pump is one system will be described.

The control valve 17 is a device that controls the hydraulic system in the excavator 1. In addition to the traveling hydraulic motors 2A and 2B for driving the crawler 2 shown in FIG. 1, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 are connected to the control valve 17 via a high-pressure hydraulic line. , The control valve 17 controls the hydraulic pressure supplied to them according to the operation input of the driver.

Further, a swivel hydraulic motor 21 for driving the swivel device 3 is connected to the control valve 17. The swivel hydraulic motor 21 is connected to the control valve 17 via the hydraulic circuit of the swivel controller, but the hydraulic circuit of the swivel controller is not shown in FIG. 3 and the like, which is simplified.

An operating device 26 (operating means) is connected to the pilot pump 15 via a pilot line 25. The operating device 26 is an operating device for operating the crawler 2, the swivel device 3, the boom 5, the arm 6, and the bucket 10, and is operated by the driver. The control valve 17 is connected to the operating device 26 via the hydraulic line 27, and the pressure sensor 29 is connected via the hydraulic line 28.

The operating device 26 converts the flood control supplied through the pilot line 25 (primary-side flood control) into a flood control (secondary-side flood control) according to the amount of operation by the driver and outputs the output. The secondary side oil pressure output from the operating device 26 is supplied to the control valve 17 through the hydraulic line 27 and is detected by the pressure sensor 29. Although the hydraulic line 27 is drawn as one in FIG. 3 and the like, there are actually a left traveling hydraulic motor, a right traveling hydraulic motor, and a hydraulic line with control command values for turning.

The operating device 26 includes three input devices 26A to 26C. The input devices 26A to 26C are pedals or levers, and the input devices 26A to 26C are connected to the control valve 17 and the pressure sensor 29 via the hydraulic lines 27 and 28, respectively. The pressure sensor 29 is connected to a controller 30 that controls the drive of the electrical system. In the present embodiment, the input device 26A functions as a turning operation lever, and the input device 26B functions as an attachment operation lever. The input device 26C is a traveling lever or pedal.

The controller 30 is a main control unit that controls the drive of the excavator. The controller 30 is composed of a CPU (Central Processing Unit) and an arithmetic processing device including an internal memory, and is realized by the CPU executing a drive control program stored in the memory.

The sensor 530 detects the position information θ of the attachment 23. Specifically, the position information θ includes the detected values of the _{angular coordinates θ 1 to θ 3} indicating the positions of the boom 5, the arm 6, and the bucket 10. The sensor 530 can be composed of a link angle sensor or a sensor that detects the displacement amount of the cylinder. Further, the position information may be angle information [rad], angular velocity information [rad / s], or angular acceleration information [rad / s ² ].

The controller 30 operates at least one of the attachment 12 and the upper swing body 4 so that the force F applied to the load in the bucket 10 during the operation of the attachment 12 does not exceed the stable threshold value T of the load. Restrict. The limit control by the controller 30 will be described later.

FIG. 7 is a diagram schematically showing the bucket 10 and the load 40. In a certain usage pattern, sediment overflow occurs when the force F applied to the load 40 exceeds the maximum static friction force μN. Therefore, the threshold value T can be calculated in consideration of the coefficient of static friction μ, the normal force N, and the mass m of the load 40.

Specifically, the threshold can be calculated approximately by modeling the load and the bucket 10. Let δ be the angle formed by the bucket 10 with the horizontal plane (ground). In the stationary state of the bucket 10, the normal force N is N = mg × cos δ. Also in the cargo 40 spilled to the direction x is worked component _F G = mg × _sinδ gravity. Thus relation F _{G <[mu]} N is a condition that does not cause overflow sediment.

When the attachment 12 or the swivel device 3 is moved, in addition to the gravity component, a force F _|| caused by the operation of the attachment 12 or the swivel device 3 is applied to the load 40. At this time, a condition for equation F _|| + F G _<μN no overflow occurs sediment. By transforming this, it is possible to obtain the following equation, the right side mu _N -F _G is the threshold T.
_{F ||} <μN-F _{G
T = μN-F G = μmg} × cosδ-mg × sinδ
= Mg (μcosδ-sinδ)
That is, since the threshold value T is a function of the bucket angle δ, it is desirable to lower the threshold value T when the bucket angle δ is in a range where it is likely to overflow. The normal force N also changes by moving the attachment 12 and the swivel device 3, but the effect is ignored.

As the threshold value T, typical δ, μ, and m are assumed in the design stage of the excavator 1, and a predetermined value calculated based on these may be used. Alternatively, the driver of the excavator 1 may be able to set it.

Alternatively, the calculation formula of the threshold value T may be described in the program (or hardware) executed by the controller 30, and the threshold value T may be calculated adaptively. For example, the angle δ may be calculated from the posture of the attachment 12, and the threshold value T may be calculated as appropriate. If the mass m of the load 40 is measurable, the mass m may be reflected in the threshold value T.

In more advanced models, changes in normal force N due to the operation of the attachment 12 and swivel device 3 may be considered.

It can be empirically found that the easiness of overflow differs depending on the shape of the load 40. Therefore, the shape of the load may be detected by a camera or the like, and the threshold value T may be dynamically and adaptively changed according to the shape.

It is desirable that the operation of the attachment 12 and the swivel body 4 by the controller 30 is restricted only in the state of carrying the load in the bucket 10, and not restricted in other cases, for example, during excavation or excavation. .. Since overflow of earth and sand does not matter during excavation and excavation operations, it is possible to prevent a decrease in work efficiency by removing the restriction. For the determination of whether the soil is being excavated or excavated, for example, the technique described in Japanese Patent Application No. 2006-182504 can be used.

Subsequently, the operation limitation of the attachment 12 and the swivel body 4 by the controller 30 will be described in relation to some usage patterns of the excavator 1.

FIG. 8 is a diagram showing the operation of the excavator 1 in the first usage mode. FIG. 8 shows a swivel lifting operation. The swivel lifting operation, the force _{F A} acting on the cargo 40 in the bucket formula (1a), represented by (1b).
_{F A = m × α A ...} (1a)
α _A = (y ₁₁ + y ₁₂ + y ₁₃ + y ₁₄ )… (1b)
m: Mass of the load α _A : Acceleration of the load y ₁₁ : Centrifugal force generated by the operation of the attachment 12 y ₁₂ : Centrifugal force generated by the operation of the swivel device 3 y ₁₃ : The attachment 12 is the load generated by the operation of the swivel device 3. Force exerted on 40 y ₁₄ : Force exerted by the attachment 12 on the load 40 due to the operation of the attachment 12.

That this use form, the resultant force _{F A} force _{y 12, y 13} occurring with the operation of the power _{y 11, y 14} and turning device 3 for generating with the operation of the attachment 12 is taken into account. It should be noted that the turning holding and lowering operation can be considered in the same manner.

The centrifugal force y ₁₁ is a centrifugal force around the origin O in the plane including the attachment 12 due to the displacement of the boom shaft, the arm shaft, and the bucket shaft, and y ₁₁ = R (θ) · (θ ₁ '+ θ ₂ '. + Θ ₃ ') Represented by ^2. "'" Represents the time derivative d / dt.

y ₁₂ is a centrifugal force generated by the rotation of the swivel shaft, and is represented by, for example, y ₁₂ = R (θ) · φ ′ ² .

y ₁₃ is a force exerted by the attachment 12 on the load 40 due to the rotation of the swivel shaft, and is represented by, for example, y ₁₃ = R (θ) · φ ″. ^{“''” Represents the second} derivative (d / dt) 2 of time.

y ₁₄ is the force exerted by the attachment 12 on the load 40 due to the displacement of the boom shaft, arm shaft, and bucket shaft. For example, y ₁₄ = R (θ) · (θ ₁ '' + θ ₂ '' + θ ₃ '' ).

Note F _A but is a three-dimensional vector, as shown in FIG. 7, acting on the overflow sediment is parallel to the bucket 10 component F _{||. Therefore, the parallel component F ||} may be calculated in consideration of the posture of the attachment 12. Or as the norm of the force F _A (absolute value) are all contribute to overflow sediment, | F A _| may be approximated with ≒ F _||.

The controller 30, based on the coordinates theta ₁ through? ₃ and φ for each axis, calculates a force _{F A.} Force F _A as described above, it is understood as a function of theta ₁ through? ₃ and phi. The controller 30, when the stable may thresholds cargo 40 during pivoting lifting operation written as T _A, limits the operation of at least one of the attachment 12 and the turning device 3 so as to satisfy the relational expression (2).
_{T A> F A ... (2} )

Here, it can be approximated as the threshold value T _A is mainly governed by a frictional force, thus proportional to the mass of the cargo 40. A proportionality coefficient and _{S A,} threshold value _{T A} is represented by the formula (3).
_{T A = m × S A ...} (3)

From the equations (1) to (3), the relational expression (4) which does not depend on the mass m of the load 40 is obtained. The controller 30 may limit at least one of _{the accelerations y 11} , y ₁₂ , y ₁₃ and y ₁₄ of the plurality of axes so as to satisfy the relational expression (4).
_{S A> (y 11 + y} 12 + y 13 + y 14) ... (4)

FIG. 9 is a diagram showing the operation of the excavator 1 in the second usage mode. FIG. 9 shows a lifting operation. In the lifting operation, the bucket 10 is pulled toward the front while being lifted upward. This lifting operation, the force _{F B} acting on the cargo 40 in the bucket is represented by the formula (5a), (5b).
_{F B = m × α B ...} (5a)
α _B = y ₁₁ … (5b)
y ₁₁ : Centrifugal force generated by the operation of the attachment 12 In this usage pattern, y ₁₄ may be taken into consideration.

In this usage mode, the centrifugal force y ₁₁ is applied in a direction in which the load 40 overflows from both sides of the bucket 10 toward the back side of the arm 6.

The controller 30, based on the coordinates theta ₁ through? ₃ for each axis, calculates a force _{F B.} The controller 30, when the lifting steady may thresholds cargo 40 during operation written as T _B, limits the operation of at least one of the attachment 12 and the turning device 3 so as to satisfy the equation (6). Threshold _{T B} may be set to a different value as the threshold value _{T A.
T B> F B ... (6} )
Threshold _{T B} is represented by the formula (7) using the proportionality factor _{S B.
T B = m × S B ...} (7)

From the equations (5) to (7), the relational expression (8) which does not depend on the mass m of the load 40 is obtained. The controller 30 may limit at least one of _{the accelerations y 11} and y ₁₄ associated with the arm shaft, boom shaft, and bucket shaft so as to satisfy the relational expression (8).
_{S B> y 11 ... (8} )

In the first, second usage pattern, in order to suppress the force F _A and F _B, the controller 30 can perform the following control.

Control 1. Suppression controller 30 of acceleration, by limiting the acceleration (angular acceleration) of at least one axis, it is possible to reduce the force F _A, F _B.

Control 1A. For example, the controller 30 may maintain the relational expression (4) or (8) by suppressing the acceleration of all axes. Suppression of acceleration on all axes can be realized by (i) reducing the change in the flow rate of the pilot pressure, or (ii) limiting the amount of change (time change rate) in the pump output torque. The change in the flow rate of the pilot pressure may be realized by adding an electromagnetic diaphragm on the pilot line 25.

Specifically, in the excavator 1 of FIG. 3, a flow rate adjusting valve 18 is provided on the path of the hydraulic line 27. The controller 30 can suppress the acceleration of all axes by controlling the flow rate adjusting valve 18.

Further, in the excavator 1 of FIG. 4, the controller 30 controls the main pump 14, so that the amount of change in the output torque of the main pump 14 can be suppressed.

By suppressing the acceleration of all axes, the direct term of y ₁₃ and y ₁₄ are suppressed. Further, since the subsequent speed is reduced by suppressing the acceleration, _{the terms y 11} and y ₁₂ are also indirectly suppressed. As a result, decreases the force _F A, is _{F B,} Equation (4), are satisfied (8), it can be suppressed overflow sediment. In addition, control can be simplified by uniformly suppressing all axes.

The controller 30 may suppress the acceleration when S <α, and may further suppress the acceleration when S <α. Alternatively, the controller 30 may suppress the acceleration based on the ratio K = α / S of S and α. For example, the acceleration may not be suppressed in a predetermined range 0 <K <0.8, and the acceleration may be suppressed in a certain predetermined range 0 <K <0.8. As K becomes larger, the degree of suppressing acceleration may be increased. There are various variations in how to reduce the acceleration in order to satisfy the equations (4) and (8), and the variations are also included in the scope of the present invention.

Control 1B. Alternatively, the controller 30 may limit the acceleration of some axes and not suppress the acceleration of the remaining axes. For example, with respect to the _{bucket axis θ 3 , the influence on the force y 14} may not be so large as compared with other axes. In this case, the acceleration may be limited for the three axes of _{θ 1} , θ ₂ , and φ without limiting the acceleration of _{θ 3.} By appropriately selecting an axis that does not limit acceleration, it is possible to prevent deterioration of responsiveness and deterioration of operability.

Alternatively, the controller 30 may suppress only the acceleration of the turning shaft φ. This control should not be confused with the prior art. _{Conventionally, the forces y 11} and y ₁₄ generated by the movement of the attachment are not taken into consideration.

Control 2. Suppression controller 30 of the speed, by limiting the rate of at least one axis (angular velocity), it is possible to reduce the force F _A, F _B.

Control 2A. The controller 30 may maintain the relational expression (2) by limiting the speed of all axes. Suppression of the speed of all axes can be achieved by (i) reducing the output torque of the pump, (ii) reducing the pilot pressure, or (iii) reducing the engine speed.

In the excavator 1 of FIG. 4, the controller 30 can limit the speed by reducing the output torque of the main pump 14 by controlling the main pump 14.

The excavator 1 of FIG. 5 is provided with a proportional valve 19 on the hydraulic line 27. The controller 30 can limit the speed by reducing the pilot pressure by controlling the proportional valve 19.

In the excavator 1 of FIG. 6, the controller 30 can limit the speed by reducing the rotation speed of the engine 11.

The controller 30 may suppress the speed of all axes when S <α, and may further suppress the speed when S <F. Alternatively, the controller 30 may suppress the speed based on the ratio K = α / S of S and α. For example, in a certain predetermined range 0 <K <0.8, the speed may not be suppressed, and in 0.8 <K, the speed may be suppressed. As K becomes larger, the degree of suppressing the speed may be increased.

By thus suppressing the rate of all axes, term term y ₁₁ and y ₁₂ of the centrifugal force is suppressed. As a result, decreases the force _F A, is _{F B,} Equation (4), are satisfied (8), it can be suppressed overflow sediment. In addition, control can be simplified by uniformly suppressing all axes.

Control 2B. The controller 30 may limit the speed of some axes and not suppress the speed of the remaining axes. By appropriately selecting an axis that does not limit acceleration, it is possible to prevent deterioration of responsiveness and deterioration of operability.

Control 3. Acceleration and speed suppression controller 30 may use both acceleration suppression control and speed suppression control. In this _{case, y 11, y 12, y} 13, y 14 , all terms are limited by the force _F A, is _{F B} decreases. For example, (i) suppress both acceleration and velocity for all axes, (ii) suppress both acceleration and velocity for some selected axes, and (iii) suppress acceleration for some axes. However, the velocity may be suppressed for some of the remaining axes.

Control 4. Suppression controller 30 of the jerk, by limiting the jerk (jerk) of at least one axis, it is possible to reduce the force F _A, F _B. Jerk suppression may be combined with acceleration or velocity suppression.

By suppressing the acceleration, velocity, and jerk in this way, it is possible to realize control so that the force F does not exceed the threshold value T.

Subsequently, control of a plurality of axes will be described. The controller 30 may preferentially suppress the acceleration, velocity or jerk of the axis that predominantly acts in the direction in which the load 40 overflows the bucket 10.
S> K ₁・ y ₁₁ + K ₂・ y ₁₂ + K ₃・ y ₁₃ + K ₄・ y ₁₄ … (9)
K ₁ , K ₂ , K ₃ , and K ₄ are the gains of each axis, and the controller 30 _{weights K 1} , K ₂ , K ₃ , and K ₄ to suppress sediment overflow without impairing the operability. it can.

The controller 30, K ₁ , K ₂ , K ₃ , and K ₄ may be dynamically and adaptively changed based on the shape of the earth and sand, the posture of the bucket, and the like. Depending on the shape of the earth and sand and the posture of the bucket, the ease of overflow and the direction in which the earth and sand are likely to overflow may differ. Therefore, in consideration of these, _{by changing K 1} , K ₂ , K ₃ , and K ₄ , it is possible to suppress the sediment overflow without impairing the operation feeling of the shaft which is not related to the sediment overflow.

FIG. 10 is a block diagram of the controller 30. The controller 30 includes a threshold value acquisition unit 32, a force calculation unit 34, and a limit unit 36. The controller 30 can be realized by a combination of hardware and a program such as a CPU, a microcontroller, and a DSP (Digital Signal Processor). Therefore, the threshold value acquisition unit 32, the force calculation unit 34, and the restriction unit 36 are CPU in terms of hardware. And is grasped as a part of DSP.

The threshold value acquisition unit 32 acquires the threshold value T. The threshold value T may be calculated as described above, or a predetermined value may be used. Alternatively, the threshold value T may be obtained by multiplying a predetermined value by a variable coefficient according to the angle δ of the bucket and the shape of the load 40. The threshold value T may be represented by S having an acceleration dimension as described above.

The force calculation unit 34 receives information θ _{1 to θ 3} indicating the position of the attachment 12 and information φ indicating the state of the swivel device 3, and calculates the force F. The force F may be represented by α having the dimension of acceleration.

The limiting unit 36 limits the operation of at least one axis of the attachment 12 and the swivel device 3 based on the relationship between the acceleration α and the threshold value S. As described above, the limiting unit 36 can limit acceleration, velocity, and jerk, and there may be various variations in the limiting axis.

The first embodiment has been described above. This embodiment is an example, and it will be understood by those skilled in the art that various modifications are possible for each of these components and combinations of each processing process, and that such modifications are also within the scope of the present invention. is there. Hereinafter, such a modification will be described.

(Modified example of the first embodiment)
The model shown in FIG. 7 regarding the determination of the threshold value T is only an example, and the threshold value T may be determined based on another model.

The Figure 8 of the excavator 1, the force _F A, _{F B} acting on the cargo 40 in the use configuration of FIG. 9 is not limited to Equation (1) and (5). For example, one term may be omitted or another term may be considered.

(Second Embodiment)
FIG. 11 is a block diagram of an electric system, a hydraulic system, and the like of the excavator 1 according to the second embodiment.

Although the controller 30 will be described in detail later, the controller 30 prevents sediment overflow by controlling the inclination of the bucket 10. For example, if the control valve 17 is electronically controllable, the controller 30 may directly electrically drive a valve that controls the bucket cylinder 9 or other cylinders 7, 8. The above is the entire block diagram of the excavator 1.

Next, the mechanism of sediment overflow will be explained. FIG. 12 is a diagram schematically showing the bucket 10 and the load 40. In a certain usage pattern, it is considered that sediment overflow occurs when the force F applied to the load 40 exceeds the threshold value T corresponding to the maximum static friction force μN. Therefore, the threshold value T can be calculated in consideration of the coefficient of static friction μ, the normal force N, and the mass m of the load 40.

Specifically, the threshold value T can be approximately calculated by modeling the load and the bucket 10. The angle (hereinafter referred to as the bucket angle) formed by the reference plane of the bucket 10 with the horizontal plane (ground) is defined as δ. The reference surface 41 can be defined parallel to the bottom surface or the top surface of the bucket. In the stationary state of the bucket 10, the normal force N is N = mg × cos δ. g represents the gravitational acceleration. Also in the cargo 40 spilled to the direction x is worked component _F G = mg × _sinδ gravity. Thus relation F _{G <[mu]} N is a condition that does not cause overflow sediment. In a conventional bucket angle constant control, by approximating the δ to zero, closer to F _G to zero, by increasing the normal force N, it is grasped as to prevent overflow sediment.

Moving the attachment 12 or the turning device 3, in addition to the components F _G of gravity, the force F _|| due to operation of the attachment 12 and the turning device 3 is applied to the cargo 40. At this time, a condition for equation F _|| + F G _<μN no overflow occurs sediment. The force F _|| may include the acceleration due to the operation of the attachment 12, the centrifugal acceleration, the acceleration due to the operation of the swivel device 3, and the centrifugal acceleration.

Subsequently, the control for preventing the overflow of earth and sand of the excavator 1 according to the present embodiment will be described. 13 (a) and 13 (b) are diagrams schematically showing bucket angle control by the controller 30. The load 40 can be considered separately as an overflowing upper portion 40a and a lower portion 40b housed in the bucket 10, and the lower portion 40b can be regarded as one with the bucket 10.

Now, consider accelerating the bucket 10 in the direction of the arrow in the figure, that is, in the horizontal direction of the ground (X-axis direction) with acceleration α. Note that FIGS. 13 (a) to 13 (c) show the force as a dimension of acceleration. FIG. 13A shows a control for keeping the bucket angle δ at 0 degrees as in the conventional case. Assuming that the mass of the upper portion 40a is m, the normal force N is mg, and the maximum static friction force is μmg. Applying a force of acceleration α to the lower portion 40b in the arrow direction X is equivalent to applying a force of acceleration α to the upper portion 40a in the direction opposite to the arrow X. Therefore,
mα> μmg
When holds, then α> μg… (1)
When is satisfied, the upper portion 40a overflows in the direction opposite to the X-axis.

FIG. 13B shows bucket angle control by the controller 30 in the present embodiment. When accelerating the bucket 10 with the acceleration α, the controller 30 moves the bucket 10 in a direction in which the reference surface 41 approaches the acceleration direction (X direction) generated on the load 40 and the vertical surface 42. Tilt to. The bucket angle δ may be controlled only by controlling _{the bucket axis θ 3} , or may be controlled by combining the control of _{the boom axis θ 1} and the arm axis θ _2.

Similar to FIG. 13A, a force of acceleration α is applied to the upper portion 40a in the direction opposite to the arrow X, and a gravitational acceleration g is applied in the vertical direction. The normal force at this time is the sum of the _{component α ||} perpendicular to the reference plane 41 of the acceleration α _{and the component g ||} perpendicular to the reference plane 41 of the gravitational acceleration g.
g × cos δ ＋ α × sin δ
Will be. Therefore, the maximum static friction force is
μ × (g × cos δ + α × sin δ)
Will be.

On the other hand, the force for sliding the upper portion 40a in the horizontal direction with the reference surface 41 is the sum of the _{component α || parallel to the reference surface 41 of the acceleration α and the component g ||} parallel to the reference surface 41 of the gravity acceleration g. And
α × cos δ-g × sin δ
Will be. Note that α _|| and g _|| are in opposite directions.

Therefore, when the relational expression (2) holds, the upper portion 40a overflows in the X-axis direction or the opposite direction.
| Α × cos δ-g × sin δ |> μ × (g × cos δ + α × sin δ)… (2)

By comparing the relational expressions (1) and (2), the advantage of the bucket angle control according to the embodiment becomes clear. The left side of each of the relational expressions (1) and (2) is the force that tries to overflow the upper part 40a, and by appropriately selecting δ,
α ＞ ｜ α × cos δ-g × sin δ ｜
Is established. On the other hand, comparing the maximum static friction forces on the right side of each of the relational expressions (1) and (2), by appropriately selecting δ,
μg <μ × (g × cos δ + α × sin δ)
Is established. That is, comparing the relational expressions (1) and (2), it can be seen that the relational expression (2) is more difficult to hold.

The above is the principle of bucket angle control by the controller 30. According to the excavator 1 according to the embodiment as described above, when the bucket 10 is moved, the bucket 10 is moved in a direction in which the reference surface 41 approaches the acceleration direction (X direction) generated on the load 40 and the vertical surface 42. By tilting to, the overflow of earth and sand can be suppressed.

As described above, when comparing the right-hand sides of the relational expressions (1) and (2), the right-hand side of the relational expression (2) is larger. That is, when the present embodiment is viewed from another viewpoint, the controller 30 is maximally stationary with respect to the load 40 (upper portion 40a) while at least one of the swivel device 3 and the attachment 12 is moving (that is, the bucket 10 is moving). It can be understood that the control is performed so that the bucket 10 is tilted so that the frictional force becomes large, in other words, the normal force becomes large.

Further, as described above, when the left sides of the relational expressions (1) and (2) are compared with each other, the left side of the relational expression (2) is smaller. That is, when the present embodiment is viewed from another viewpoint, the controller 30 acts on the load 40 (upper portion 40a) in parallel with the reference plane while moving at least one of the swivel device 3 and the attachment 12. It can be grasped that the control of tilting the bucket 10 is performed so that

It is desirable that the bucket angle control by the controller 30 is performed only in the state where the load 40 in the bucket 10 is being carried, and in other cases, for example, during soil removal or excavation, the bucket angle control is not performed. Since overflow of earth and sand does not matter during excavation and excavation operations, it is possible to prevent a decrease in work efficiency by removing the restriction. For the determination of whether the soil is being excavated or excavated, for example, the technique described in Japanese Patent Application No. 2006-182504 can be used.

14 (a) and 14 (b) are views showing the first usage mode of the excavator 1 in which the bucket angle control is effective. The first usage mode shows a swivel operation in which the attachment 12 is fixed and the swivel device 3 is swiveled. During the turning operation, the centrifugal acceleration Rφ ' ² and the turning acceleration Rφ'' act on the load 40.

Since the bucket 10 is movable in the plane including the boom 5 and the arm 6, it cannot be tilted in the direction facing the turning acceleration rφ''. Therefore, the controller 30 considers the force acting on the load 40 in the plane including the boom 5 and the arm 6, and tilts the reference plane of the bucket in a direction approaching the vertical plane of the acceleration in this plane. Just do it. Specifically, during the turning operation, the controller 30 tilts the bucket 10 in a direction in which the reference surface 41 approaches the vertical surface 42 of the ^{centrifugal acceleration Rφ '2.}

FIG. 15 is a diagram showing a second usage mode of the excavator 1 in which bucket angle control is effective. The second usage mode shows an operation of fixing the swivel shaft φ and lifting (or lowering) the load 40 by the attachment 12. During the lifting operation, and a ² act 'centrifugal acceleration R.theta and' acceleration R.theta 'the cargo 40. The controller 30 tilts the bucket 10 so that the reference surface 41 approaches the vertical surface of either the acceleration Rθ'' or the centrifugal force acceleration Rθ ' ^2.

Alternatively the controller 30 'and the centrifugal force acceleration R.theta' acceleration R.theta ^'2 to vector synthesis, the bucket 10, the reference surface 41 may be inclined so as to approach the vertical face of the acceleration synthesized.

In addition to the usage embodiments shown in FIGS. 14 and 15, the bucket angle control according to the embodiment is also effective for the swivel lifting operation (swivel lifting operation) which is a combination thereof. During this swivel lifting operation, acceleration Rθ ″, centrifugal force acceleration Rθ ′ ² , centrifugal force acceleration Rφ ′ ² , and swivel acceleration Rφ ″ act on the load 40. The controller 30 can control the bucket angle based on any one of the acceleration Rθ ″, the centrifugal force acceleration Rθ ′ ² , the centrifugal force acceleration Rφ ′ ^{2, or some combination thereof.}

FIG. 16 is a block diagram of the controller 30. The controller 30 of FIG. 16 includes an acceleration direction acquisition unit 32, a bucket angle calculation unit 34, and an inverse kinematics calculation unit 36. The controller 30 can be realized by a combination of hardware and a program such as a CPU, a microcontroller, and a DSP (Digital Signal Processor). Therefore, the acceleration direction acquisition unit 32 and the bucket angle calculation unit 34 are one of the CPU and DSP in terms of hardware. It is grasped as a department.

The acceleration direction acquisition unit 32 acquires the acceleration direction generated in the load 40 in the bucket 10 when the bucket 10 is moved. The acceleration direction acquisition unit 32 may calculate the acceleration direction based on the _{position information θ 1 to θ 3 and φ (or velocity information).} Alternatively, a _{map (table) that associates the position information θ 1 to θ 3} and φ (or velocity information) with the acceleration direction may be held, and the acceleration direction may be acquired by referring to the table. The map may be prepared for each usage pattern (lifting operation, turning operation, turning lifting operation).

The bucket angle calculation unit 34 determines the bucket angle δ by calculation or table reference so as to approach the vertical plane in the acceleration direction obtained by the acceleration direction acquisition unit 32. The inverse kinematics calculation unit 36 calculates the command values of the _{link angles θ 1 to θ 3} so that the bucket angle δ can be obtained.

In FIG. 16, the bucket angle δ is determined by two-step signal processing of the acceleration direction acquisition unit 32 and the bucket angle calculation unit 34, but the present invention is not limited thereto. For example, a _{map (table) that directly associates the position information θ 1 to θ 3} and φ (or velocity information) with the bucket angle δ may be prepared, and the bucket angle δ may be determined by referring to the table. In this case as well, the map may be prepared for each usage mode (lifting operation, turning operation, turning lifting operation).

The bucket angle δ may be adaptively changed according to the magnitude of acceleration and the type of operation of the excavator 1. Alternatively, if a constant value is set for each excavator operation and the operation of the excavator is determined, a constant value corresponding to the value may be used.

Further, the bucket angle control according to the embodiment is naturally effective when decelerating the bucket.

Subsequently, another embodiment of bucket control by the controller 30 will be described. FIG. 17 is a block diagram of an electric system, a hydraulic system, and the like of the excavator according to the first modification. In order to control the bucket angle, the excavator 1 is provided with a switching valve 18 and a proportional valve 19. If the control valve 17 is electrically uncontrollable with respect to the bucket shaft or other shaft, the controller 30 may control the switching valve 18 and the proportional valve 19, control the pressure on the control valve 17, and control the bucket angle. Good.

FIG. 18 is a block diagram of an electric system, a hydraulic system, and the like of the excavator according to the second modification. The excavator 1 includes a flow rate adjusting valve 20 instead of the switching valve 18 and the proportional valve 19 shown in FIG. The controller 30 may control the bucket angle by changing the flow rate of the pressure oil supplied to the control valve 17 by controlling the flow rate adjusting valve 20.

The present invention has been described using specific terms and phrases based on some embodiments, but the embodiments merely indicate the principles and applications of the present invention, and the embodiments are claimed. Many modifications and arrangement changes are permitted within the range not departing from the idea of the present invention defined in the scope.

1 ... Excavator, 2 ... Crawler, 2A, 2B ... Running hydraulic motor, 3 ... Swivel device, 4 ... Swivel body, 4a ... Driver's cab, 5 ... Boom, 6 ... Arm, 7 ... Boom cylinder, 8 ... Arm cylinder, 9 ... bucket cylinder, 10 ... bucket, 11 ... engine, 12 ... attachment, 14 ... main pump, 15 ... pilot pump, 16 ... high pressure hydraulic line, 17 ... control valve, 18 ... switching valve, 19 ... proportional valve, 20 ... flow rate Adjusting valve, 21 ... Swing hydraulic motor, 25 ... Pilot line, 26 ... Operating device, 27, 28 ... Hydraulic line, 29 ... Pressure sensor, 30 ... Controller, 32 ... Acceleration direction acquisition unit, 34 ... Bucket angle calculation unit, 36 ... Reverse kinematics calculation unit, 40 ... Load, 40a ... Upper part, 40b ... Lower part, 530 ... Sensor.

The present invention can be used in industrial vehicles.

Claims (11)

With the crawler
With the upper swivel body,
A swivel device that rotates the upper swivel body with respect to the crawler,
An attachment having a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder and attached to the upper swing body,
A controller forces arising in the loading of the operation thus the bucket of the attachment, so as not to exceed the stable may thresholds of the cargo, which limits the operation of at least one of said attachment and said upper swing structure ,
Excavator characterized by being equipped with. The excavator according to claim 1, wherein the controller considers a resultant force of a force generated by the operation of the attachment and a force generated by the operation of the swivel device. The excavator according to claim 1 or 2, wherein the controller suppresses acceleration of at least one of a swivel shaft, a boom shaft, an arm shaft, and a bucket shaft. The excavator according to claim 3, wherein the controller suppresses acceleration of all axes of a swivel shaft, a boom shaft, an arm shaft, and a bucket shaft. The excavator according to claim 3, wherein the controller preferentially suppresses acceleration of an axis that predominantly acts in a direction in which the load overflows from the bucket. The excavator according to any one of claims 1 to 5, wherein the controller suppresses the speed of at least one of a swivel shaft, a boom shaft, an arm shaft, and a bucket shaft. The excavator according to any one of claims 1 to 6, wherein the controller suppresses jerk of at least one of a swivel shaft, a boom shaft, an arm shaft, and a bucket shaft. The excavator according to any one of claims 1 to 7, wherein the threshold value depends on the posture of the attachment. With the crawler
With the upper swivel body,
A swivel device that rotates the upper swivel body with respect to the crawler,
An attachment having a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder and attached to the upper swing body,
When the bucket is moved, a controller that tilts the bucket in a direction in which the reference plane of the bucket approaches the acceleration direction generated on the load in the bucket and the vertical plane
Excavator characterized by being equipped with. With the crawler
With the upper swivel body,
A swivel device that rotates the upper swivel body with respect to the crawler,
An attachment having a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder and attached to the upper swing body,
A controller that tilts the bucket so that the normal force of the load in the bucket increases while the swivel device and at least one of the attachments are in motion.
Excavator characterized by being equipped with. With the crawler
With the upper swivel body,
A swivel device that rotates the upper swivel body with respect to the crawler,
An attachment having a boom, an arm, a bucket and a boom cylinder, an arm cylinder, and a bucket cylinder and attached to the upper swing body,
A controller that tilts the bucket so that the force acting parallel to the reference plane of the bucket is small with respect to the load in the bucket while moving at least one of the swivel device and the attachment.
Excavator characterized by being equipped with.

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