JP2018091131A - Shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shovel having a floating suppressing mechanism dynamically corresponding to a use state.SOLUTION: A shovel 1 has a traveling body, an upper turning body turnably provided on the traveling body, and an attachment 12. The attachment 12 has a boom, an arm and a bucket, and is mounted on the upper turning body. A floating suppressing portion 600 corrects movement of the attachment 12 so as to suppress floating the traveling body. A control condition in the floating suppressing portion 600 is set based on information acquired at the moment at which the traveling body floats.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an excavator.

  The excavator mainly includes a traveling body (also referred to as a crawler or a lower), an upper swing body, and an attachment. The upper swing body is rotatably attached to the traveling body, and its position is controlled by a swing motor. The attachment is attached to the upper swing body and is used during work.

  The operator controls the boom, arm, and bucket of the attachment according to the work content, and at this time, the vehicle body (that is, the traveling body and the upper swing body) receives a reaction force from the attachment. Depending on the direction in which the reaction force is applied, the posture of the vehicle body, and the situation of the ground, the excavator body may rise.

  Patent Document 1 discloses a technique for preventing the vehicle body from being lifted and thus toppling over by suppressing the pressure on the contraction side (rod side) of the boom cylinder.

JP 2014-122510 A

  In order to prevent the shovel from lifting, position information of the excavator's overturning fulcrum is required. The overturning fulcrum changes according to the rotation angle (direction) of the upper-part turning body and the ground condition. On the other hand, in the conventional shovel, a fixed overturning fulcrum is determined in consideration of versatility, and the control for preventing the lift is always performed using the same control conditions regardless of the use state of the shovel.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and one of the exemplary purposes of an aspect thereof is to provide a shovel including a lifting suppression mechanism that dynamically responds to the use state of the shovel.

  One embodiment of the present invention relates to an excavator. The excavator has a traveling body, an upper revolving body that is rotatably provided on the traveling body, a boom, an arm, and a bucket, and an attachment attached to the upper revolving body, and lifting of the traveling body is suppressed. And a floating suppression unit that corrects the operation of the attachment. The control condition in the lifting suppression unit is set based on information acquired at the moment of lifting of the traveling body.

  The moment of lifting can be approximated as a balance between the force with which the attachment tries to tilt the vehicle and the gravity against it. Therefore, by detecting the moment of lifting and monitoring the state of the excavator at that time, it is possible to adaptively set the control conditions for suppressing the lifting, and the lifting can be appropriately suppressed under various usage conditions.

  The lift suppression unit may acquire the position information of the falling fulcrum based on the information acquired at the moment of lifting of the traveling body, and may define the control condition based on the position information.

The information acquired at the moment of lifting of the traveling body may include a force F _{1_INIT} that the boom cylinder exerts on the upper swing body.

  The shovel may further include an acceleration sensor attached to the traveling body or the upper swing body and a rotation sensor that acquires rotation information in the pitch direction. The lifting suppression unit may acquire the position information of the falling fulcrum based on the output of the acceleration sensor and the output of the rotation sensor.

  The floating suppression unit may remove the influence of gravitational acceleration from the output of the acceleration sensor.

  The rotation sensor may be an angular velocity sensor. At least one of when the output of the angular velocity sensor exceeds a predetermined value and when the differential value of the output of the angular velocity sensor exceeds a predetermined value may be set as the moment of lifting of the traveling body.

Another embodiment of the present invention is also an excavator. This excavator has a traveling body, an upper revolving body that is rotatably provided on the traveling body, a boom, an arm, and a bucket, and an attachment attached to the upper revolving body, and lifting of the traveling body is suppressed. And a floating suppression unit that corrects the operation of the attachment. The lift suppression unit obtains the force F _{1_INIT} at the moment of lifting when the sensor detects the moment of lifting of the traveling body and the force F ₁ that the boom cylinder exerts on the upper swing body, and based on the force F _{1_INIT} , A condition setting unit that acquires a parameter related to the position of the falling fulcrum and sets a control condition based on the parameter, and a correction unit that corrects the operation of the attachment based on the control condition are included.

The distance between the center of gravity of the excavator body and the overturning fulcrum of the traveling body is D _A , the distance between the connecting point between the boom cylinder and the upper swing body and the overturning fulcrum is D _B , the body weight is M, and the gravitational acceleration is g. When the condition setting unit
D _B F _{1_INIT} = D _A Mg
Is obtained by obtaining the distances D _A and D _B ,
D _B F ₁ <D _A Mg
May be set as a control condition.

Condition setting unit, when the posture of the attachment changes may change the D _B included in the control condition.

  Another embodiment of the present invention is also an excavator. The excavator has a traveling body, an upper revolving body that is rotatably provided on the traveling body, a boom, an arm, and a bucket, an attachment attached to the upper revolving body, and a control condition according to the position of the overturning fulcrum. And a lift suppression unit that corrects the operation of the attachment so that the lift of the traveling body is suppressed based on the set control conditions.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  Furthermore, the description of the means for solving this problem does not explain all the indispensable features, and therefore the sub-combination of these features described can also be the present invention.

  According to the present invention, lifting of the excavator traveling body can be suppressed.

It is a perspective view which shows the external appearance of the shovel which is an example of the construction machine which concerns on 1st Embodiment. It is a figure which shows the mechanical model of the shovel relevant to the front lifting. It is a figure explaining an example of the back lifting which generate | occur | produces during the work of the shovel. It is a figure which shows the dynamic model of the shovel relevant to back lifting. It is a block diagram of the electric system and hydraulic system of an excavator. 6A to 6C are diagrams showing the relationship between the falling fulcrum P and the orientation θ of the revolving structure. It is a figure which shows the relationship between the fall fulcrum P and the state of the ground. It is a control block diagram of a floating suppression part. It is a flowchart explaining operation | movement of a floating suppression part. It is a block diagram of the floating suppression part of the shovel which concerns on a 1st structural example, and its periphery. It is a block diagram of the floating suppression part of the shovel which concerns on a 2nd structural example, and its periphery. It is a figure which shows the shovel which concerns on 2nd Embodiment. It is a figure explaining the principle of position acquisition of a fall fulcrum. It is a block diagram which shows the process for obtaining position information.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

1. First Embodiment FIG. 1 is a perspective view showing an appearance of an excavator 1 which is an example of a construction machine according to a first embodiment. The excavator 1 mainly includes a traveling body (also referred to as a lower or a crawler) 2 and an upper revolving body 4 that is rotatably mounted on the upper portion of the traveling body 2 via a revolving device 3.

  An attachment 12 is attached to the upper swing body 4. The attachment 12 is provided 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 means for capturing suspended loads such as earth and sand and steel materials. The boom 5, the arm 6 and the bucket 10 are hydraulically driven by the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9, respectively. Further, the upper swing body 4 is provided with a power source such as a cab 4a for accommodating an operator (driver) for operating the position of the bucket 10, excitation operation and release operation, and an engine 11 for generating hydraulic pressure. It has been.

  Next, the lifting of the excavator 1 will be described.

FIG. 2 is a diagram showing a mechanical model of an excavator related to front lifting.
For example, the excavator 1 is excavating the ground 50. When the boom 5 is fixed and the arm closing operation (or bucket closing operation) is performed, a force for pulling up the rod of the boom cylinder 7 is generated as a reaction force, and the front of the vehicle body is pulled up via the boom cylinder 7. Force is generated. F ₁ represents the force that the boom cylinder 7 exerts on the upper swing body 4.

D ₁ represents the distance between the vehicle body center of gravity P ₃ of the excavator and the falling support point P ₁ behind the traveling body 2. The overturning fulcrum P ₁ can be regarded as the rearmost end in the direction in which the attachment 12 extends (the direction of the revolving body 4) in the effective ground contact area 52 of the traveling body 2. The _{D 3} has an extension line _{l 2} of the boom cylinder 7, represents the distance between the tipping fulcrum _{P 1.} M is the weight of the vehicle body and g is the acceleration of gravity. At this time, the torque tau ₁ to attempt to lift the front of the vehicle body around the tipping fulcrum P ₁ is expressed by the formula (1).
τ ₁ = D ₃ × F ₁ (1)

On the other hand, the torque τ _{2 at which} gravity tries to hold the vehicle body around the fall fulcrum P ₁ is expressed by equation (2).
τ ₂ = D ₁ Mg (2)

The condition that the front of the car body is stable without rising is
τ ₁ <τ ₂ (3)
If the equations (1) and (2) are substituted, the inequality (4) is obtained as a stability condition.
D ₃ F ₁ <D ₁ Mg (4)
It becomes. That is, if the operation of the attachment 12 is corrected so that the inequality (4) is established as the control condition, the front lifting can be prevented.

Depending on the work, the back of the excavator may be lifted. FIG. 3 is a diagram for explaining an example of rear lifting that occurs during the work of the excavator. The shovel 1 is excavating the ground 50. A force F ₂ is generated so that the bucket 10 digs the slope 51, and a force F ₃ is generated so that the boom 5 holds the bucket 10 against the slope 51. In this case the force F ₁ to raise the rod of the boom cylinder ₇ is generated, the force F ₁ is a vehicle body of the excavator 1 (traveling body 2, the turning device 3, the swing body 4) serves to tilt the. The force F ₁ is above the force (torque) that you try to suppress the vehicle body based on the gravity on the ground, thus raised is the rear of the vehicle body.

As shown in FIG. 3, when the bucket 10 is in contact with the ground or an object and is caught or stuck, the boom 5 does not move even if force is applied to the boom 5, and therefore the rod of the boom cylinder 7 does not move. Does not displace. As the pressure in the rod side oil chamber increases, the force F ₁ for lifting the boom cylinder 7 itself, that is, the force for tilting the vehicle body forward increases.

  Such a case may occur in deep digging where the bucket 10 is positioned below the vehicle body (the traveling body 2) or leveling work on the front slope as shown in FIG. Moreover, it may occur not only when the boom itself is operated but also when an arm or bucket is operated.

FIG. 4 is a diagram illustrating a mechanical model of an excavator related to rearward lifting.
D ₂ represents the distance between the vehicle body center of gravity P ₃ of the shovel and the tipping fulcrum P _{1 in} front of the traveling body 2. The overturning fulcrum P ₁ can be regarded as the forefront in the direction in which the attachment 12 extends (the direction of the turning body 4) in the effective grounding region 52 of the traveling body 2. The _{D 4} is an extension _{l 2} of the boom cylinder 7, represents the distance between the tipping fulcrum _{P 1.} F ₁ is the force exerted by the boom cylinder 7 on the upper swing body 4, M is the weight of the vehicle body, and g is the acceleration of gravity. At this time, the torque tau ₁ to be incline the vehicle body forwardly around the tipping fulcrum P ₁ is expressed by Equation (5).
τ ₁ = D ₄ × F ₁ (5)

On the other hand, the torque τ _{2 at which} the gravity tries to hold the vehicle body to the ground around the overturning fulcrum P ₁ is expressed by Expression (6).
τ ₂ = D ₂ Mg (6)

The condition that the rear of the car body is stable without lifting up is
τ ₁ <τ ₂ (7)
If the equations (5) and (6) are substituted, the inequality (8) is obtained as a stability condition.
D ₄ F ₁ <D ₂ Mg (8)
It becomes. That is, if the operation of the attachment 12 is corrected so that the inequality (8) is established as the control condition, the rear lifting can be prevented.

Note the distance _D 1, _{D 2 D A,} the distance _D 2, _{D 4} at the _{D B,} if replaced with each other tipping fulcrum _{P 1} before and after the control condition of the front lift and rear lift, as follows Can be summarized.
D _B F ₁ <D _A Mg

  Next, a specific configuration of the excavator 1 capable of suppressing the front or rear lifting will be described. FIG. 5 is a block diagram of an electric system and a hydraulic system of the excavator 1. In FIG. 5, the mechanical power transmission system is indicated by a double line, the hydraulic system is indicated by a thick solid line, the steering system is indicated by a broken line, and the electrical system is indicated by a thin solid line. Although a hydraulic excavator will be described here, the present invention is also applicable to a hybrid excavator that uses an electric motor for turning.

  The engine 11 is connected to the main pump 14 and the pilot pump 15. A control valve 17 is connected to the main pump 14 via a high pressure hydraulic line 16. Two hydraulic circuits for supplying hydraulic pressure to the hydraulic actuator may be provided. In that case, the main pump 14 includes two hydraulic pumps. In this specification, the case where the main pump is one system will be described for easy understanding.

  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 traveling body 2 shown in FIG. 1, a boom cylinder 7, an arm cylinder 8 and a bucket cylinder 9 are connected to the control valve 17 via a high pressure hydraulic line. The control valve 17 controls the hydraulic pressure (control pressure) supplied to them according to the operation input of the operator.

  A swing hydraulic motor 21 for driving the swing device 3 is connected to the control valve 17. The swing hydraulic motor 21 is connected to the control valve 17 via the hydraulic circuit of the swing controller, but the hydraulic circuit of the swing controller is not shown in FIG. 5 and is simplified.

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

  For example, the operating device 26 includes hydraulic pilot type operating levers 26A to 26D. The operation levers 26A to 26D are operation levers corresponding to the boom axis, the arm axis, the bucket axis, and the turning axis, respectively. Actually, two operation levers are provided, and two axes are assigned in the vertical and horizontal directions of one operation lever, and the remaining two axes are assigned in the vertical and horizontal directions of the remaining operation levers. The operation device 26 includes a pedal (not shown) for controlling the travel axis.

The operating device 26 converts the hydraulic pressure (primary hydraulic pressure) supplied through the pilot line 25 into a hydraulic pressure (secondary hydraulic pressure) corresponding to the operation amount of the operator and outputs the converted hydraulic pressure. The secondary hydraulic pressure (control 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. That is, the detected value of the pressure sensor 29 indicates the operator's operation input θ _CNT for each of the operation levers 26A to 26D. In FIG. 5, one hydraulic line 27 is drawn, but actually there are hydraulic lines for control command values for the left traveling hydraulic motor, the right traveling hydraulic motor, and the turning.

  The controller 30 is a main control unit that performs drive control of the shovel. The controller 30 includes an arithmetic processing unit including a CPU (Central Processing Unit) and an internal memory, and is realized by the CPU executing a drive control program loaded in the memory.

  Further, the excavator 1 includes a lifting suppression unit 600. The lift suppression unit 600 corrects the operation of the attachment 12 so that the front and / or rear lift of the traveling body 2 is suppressed. The main part of the floating suppression unit 600 can be configured as a part of the controller 30.

As described above, the control conditions under which the front lifting and the rear lifting do not occur are inequalities (4) and (8). Inequalities (4) and (8) use the distances D ₁ , D ₂ , D ₃ , and D ₄ as parameters, and these distances depend on the falling support point P ₁ .

Tipping fulcrum P ₁ is moved in accordance with the state of the orientation or the ground of the swing body 4. FIG 6 (a) ~ (c) are diagrams showing the relationship between tipping fulcrum P ₁ and the orientation of the swing body (turning angle theta). Here, the fall fulcrum is assumed to be located in front of the vehicle body in consideration of the rear lifting. l ₁ represents a line that is orthogonal to the direction in which the attachment extends (the direction of the swivel 4) and passes through the forefront in the direction in which the attachment 12 extends in the effective ground region 52. The overturning fulcrum P ₁ is located on this line l ₁ . As shown in FIG. 6 (a) ~ (c) , when the tipping fulcrum _{P 1} is moved, the distance _{D 2} is also changed. Similarly, the distance D ₄ also varies with the movement of the tipping fulcrum P _1.

Figure 7 is a diagram showing the relationship between the state of the tipping fulcrum P ₁ and the ground (working field). The solid line represents the hard ground 50, and the alternate long and short dash line represents the soft ground 50 '. Than on the hard ground 50, tipping fulcrum P ₁ is present in the solid line position triangle. On the soft ground 50 ′, the falling fulcrum P ₁ ′ can exist at a triangular position of a one-dot chain line. In addition, or not exist rigid obstacles close to the tipping fulcrum P _1, when the running body 2 is or riding on obstacles, tipping fulcrum P ₁ may be moved further.

The movement of the overturning fulcrum P ₁ affects the distances D _{1 to} D ₄ , and thus affects the mechanical stability condition in which the vehicle body does not overturn. So lifting suppressing unit 600 sets the control conditions corresponding to the position of the tipping fulcrum P _1, the lifting of the running body on the basis of the set control conditions as to suppress, to correct the operation of the attachment 12.

  Hereinafter, the control in the floating suppression unit 600 will be described. The lift suppression unit 600 monitors the posture of the traveling body and detects the moment when the front (or rear) of the traveling body 2 is lifted. Then, the control conditions for correcting the operation of the attachment 12 (the above-described stability conditions, for example, the inequalities (4) and (8) as an example) are dynamically changed based on the state of the excavator 1 at the moment when the traveling body 2 is lifted. Let

The moment of lifting can be approximated to a state in which the force (torque τ ₁ ) that causes the attachment 12 to tilt the vehicle body and the gravity (torque τ ₂ ) that resists the balance. Therefore, by detecting the moment of lifting and monitoring the state of the excavator 1, control conditions for suppressing lifting can be set adaptively, and lifting can be appropriately suppressed under various usage conditions.

FIG. 8 is a control block diagram of the floating suppression unit 600.
The floating suppression unit 600 includes a sensor 610, a condition setting unit 620, and a correction unit 630. The sensor 610 detects the moment when the traveling body is lifted. As the sensor 610, an attitude sensor, a gyro sensor, or an acceleration sensor can be used, and rotation around the pitch axis may be detected.

  When the forward angular acceleration (or angular velocity) is detected by the sensor 610, a control condition for suppressing rearward lifting is set. On the other hand, when a rearward angular acceleration (or angular velocity) is detected, a control condition for suppressing forward lifting is set.

A force F ₁ exerted by the boom cylinder on the upper swing body is assumed. The condition setting unit 620 acquires the force F _{1_INIT} at the moment of lifting detected by the sensor 610, acquires a parameter related to the position of the falling fulcrum P ₁ based on the acquired force F _{1_INIT,} and based on the parameter. Set the control conditions.

As a control condition to suppress the front lifting,
D ₃ F ₁ <D ₁ Mg (4)
Is used. Assume that backward pitching is detected by the sensor 610. Since the torques τ ₁ and τ ₂ balance at the moment of lifting,
_{D 3 F 1_INIT = D 1 Mg} ... (9)
Holds. Since F 1 _—INIT and Mg are known, Expression (9) is a relational expression that should be satisfied by D ₁ and D ₃ in the current usage state of the excavator 1.

If Expression (9) is known, the distances D ₁ and D ₃ are uniquely determined geometrically. Therefore, the condition setting unit 620 acquires the current distances D _{1_DET} and D _{3_DET} based on Expression (9) and the posture of the attachment 12. Note that to obtain the distance D ₁ is equivalent to acquiring the position information of the tipping fulcrum P _1. Because, since the position of the vehicle body gravity center P ₃ is unchanged, if the distance D ₁ is determined, the position of the tipping fulcrum P ₁ is because uniquely determined. Then, the subsequent control conditions are set to D _{3_DET} F ₁ <D _{1_DET} Mg. The correcting unit 630 corrects the operation of the attachment 12 based on the set control condition.

Once the distance D ₁ obtained does not change the direction of the rotary body 4, also as long as the ground situation does not change, it is possible to use the same value. On the other hand, the distance D ₃ raises the boom 5, varies according to the lowering. Therefore, the condition setting unit 620, the angle of the boom 5 is changed, by changing the distance D ₃ accordingly, to be reflected in the control condition.

The same control is performed for rear lifting. It is assumed that the inequality (8) is used as a control condition for suppressing the rear lifting.
D ₄ F ₁ <D ₂ Mg (8)
It is assumed that forward pitching is detected by the sensor 610. Since the torques τ ₁ and τ ₂ balance at the moment of lifting,
D ₄ F 1 _—INIT = D ₂ Mg (10)
Holds. Since F 1 _—INIT and Mg are already known, Expression (10) is a relational expression that D ₂ and D ₄ should satisfy in the current usage state of the excavator 1.

The condition setting unit 620 may obtain the current distances D _{2_DET} and D _{4_DET} based on Expression (10) and the posture of the attachment 12. Incidentally comprises obtaining the distance D _2, it is equivalent to acquiring the position information of the tipping fulcrum P _1. Then, the subsequent control conditions are set to D _{2_DET} F ₁ <D _{4_DET} Mg. The correcting unit 630 corrects the operation of the attachment 12 based on the set control condition.

The distance D ₂ acquired once does not change the direction of the rotary body 4, also as long as the ground situation does not change, it is possible to use the same value. On the other hand, the distance D ₄ is raised boom 5, varies according to the lowering. Therefore, the condition setting unit 620, the angle of the boom 5 is changed, by changing the distance D ₄ accordingly, to be reflected in the control condition.

  FIG. 9 is a flowchart for explaining the operation of the floating suppression unit 600. First, it is determined whether or not excavation work using the attachment 12 is in progress (S100). The condition for determining that the excavation work using the attachment 12 is in progress is, for example, that the pressure is applied to at least one of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 of the attachment 12, not traveling or turning. It may be standing. If excavation work is not in progress (N in S100), the process returns to the original. Excavation work includes leveling work and backfilling work.

When it is determined that excavation work is in progress (Y in S100), the lift is monitored by the sensor 610 (S102). When lifting is detected (Y in S102), the state of the shovel at the moment of lifting is acquired (S104). The state of the excavator is, for example, the force F _{1_INIT} described above. Based on the state of the excavator acquired in step S104, parameters (for example, D _{1 to} D ₄ ) corresponding to the overturning fulcrum P ₁ are calculated, and control conditions are set (S106). Thereafter, the operation of the attachment 12 is corrected by the correction unit 630 based on the set control condition.

When a change in the boom posture is detected (Y in S108), the distances D ₃ and D ₄ change, so that the control condition is corrected (S110). If the work has not been completed (N in S112), the boom posture is continuously monitored. If the work has been completed (Y in S112), the process returns to the start.

  In step S102 before setting the control conditions, the vehicle body is lifted for a moment. If an appropriate combination of processor and software program is used, control conditions are set in a very short time after the lift is detected and before the first lift in step S102 develops a large body tilt, and the operation of the attachment 12 is performed. Correction can be started.

  Next, the correction of the attachment 12 by the lift suppression unit 600 will be described.

1.1 First Configuration Example FIG. 10 is a block diagram of the lifting suppression unit 600 and its surroundings of the excavator 1 according to the first configuration example. Each pressure sensor 510 and 512, the rod-side oil chamber of the pressure (rod pressure) of the boom cylinder 7 _{P R,} measuring the pressure (bottom pressure) _{P B} of the bottom-side oil chamber. The measured pressures P _R and P _B are input to the floating suppression unit 600 (controller 30).

The controller 30 includes a force estimation unit 602, a sensor 610, a condition setting unit 620, and a correction unit 630.
The force F ₁ is expressed by a function f (P _R , P _B ) of the pressures P _R , P _B.
F ₁ = f (P _R , P _B ) (5)
Force estimation unit 602, based on the rod pressure _{P R} and bottom pressure _{P B,} calculates a force _{F 1} to the boom cylinder 7 on the rotary body 4.

As an example, when the pressure receiving area on the rod side of A _R, the pressure receiving area of the bottom side and A _B,
F ₁ = A _R · P _R −A _B · P _B
It can be expressed as. The force estimation unit 602 may calculate or estimate the force F ₁ based on this equation.

The condition setting unit 620 receives the output of the sensor 610 and detects the lifting timing. Based on the force F ₁ at the lifting timing, parameters D ₁ and D ₃ (or D ₂ and D ₄ ) are calculated and control conditions are set. The condition setting unit 620 may receive information on the boom angle from the boom angle sensor 514 and reflect the information on the control conditions (parameters D ₂ and D ₄ ). Correcting unit 630, the force F ₁ is to satisfy the control condition, to correct the operation of the attachment 12.

For example, the lifting suppression unit 600 controls the pressure of the boom cylinder 7. In this configuration example, the correction unit 630 adjusts the rod pressure R _R of the boom cylinder 7 such that the control condition is satisfied.

The electromagnetic proportional relief valve 520 is provided between the bottom oil chamber of the boom cylinder 7 and the tank. The correction unit 630 controls the electromagnetic proportional relief valve 520 so as to satisfy the control condition, and relieves the cylinder pressure of the boom cylinder 7. Thereby the rod pressure P _R is reduced, thus F ₁ is reduced, it is possible to suppress lifting of the front or rear.

  The state of the spool of the control valve 17 that controls the boom cylinder 7, in other words, the direction of the pressure oil supplied from the main pump 14 to the boom cylinder 7 is not particularly limited, depending on the state of the attachment 12 (work contents). Instead of the forward direction as in FIG.

1.2 Second Configuration Example FIG. 11 is a block diagram of the lifting suppression unit 600 of the excavator 1 according to the second configuration example and its surroundings. The excavator 1 in FIG. 11 includes an electromagnetic proportional control valve 530 instead of the electromagnetic proportional relief valve 520 of the excavator 1 in FIG. The electromagnetic proportional control valve 530 is provided on the pilot line 27A from the operation lever 26A to the control valve 17. The floating suppression unit 600 changes the control signal to the electromagnetic proportional control valve 530 so as to satisfy the control condition, and changes the pressure to the control valve 17, thereby the pressure on the bottom chamber side of the boom cylinder 7 and the rod side oil. Vary the chamber pressure.

  In the above, this invention was demonstrated based on the Example. It is understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, and various modifications are possible, and such modifications are within the scope of the present invention. It is a place. Hereinafter, such modifications will be described.

Modification 1.1
In the embodiment, the distances D _{1 to} D ₄ are calculated and the control conditions are defined, but the present invention is not limited to this. When the inequalities (4) and (8) are transformed, the following inequalities are obtained.
F ₁ <D ₁ / D ₃ × Mg (4 ′)
F ₁ <D ₂ / D ₄ × Mg (8 ′)

At the moment of lifting,
F _{1_INIT} = D ₁ / D ₃ × Mg
F _{1_INIT} = D ₂ / D ₄ × Mg
Holds. Therefore, the condition setting unit 620 acquires the force F _{1_INIT} at the moment of lifting, and sets the control conditions after that as
F ₁ <F _{1_INIT}
May be set. It should be noted that although the position information of the correct fall support point P ₁ is reflected in this control condition, the distances D _{1 to} D ₄ or the position of the fall support point P ₁ are not explicitly calculated.

Modification 1.2
In the embodiment, the force F ₁ is explicitly included in the control condition for preventing the lifting, but the present invention is not limited thereto. Instead of the force F _1, using a different force correlated with the force F _1, it may define the control condition.

Modification 1.3
In the embodiment, the lift is suppressed by controlling the pressure of the boom cylinder 7, but in addition, the pressure of the arm cylinder and the bucket cylinder may be controlled.

2. Second Embodiment FIG. 12 is a diagram illustrating an excavator according to a second embodiment. The shovel 1 includes an acceleration sensor 40, a rotation sensor 42, and a lift suppression unit 50. The acceleration sensor 40 and the rotation sensor 42 are attached to the swing body 4. The acceleration sensor 40 and the rotation sensor 42 may be attached to the traveling body 2. The acceleration sensor 40 detects accelerations A _x and A _z in the longitudinal direction (X-axis direction) and the vertical direction (Z-axis direction) of the vehicle body. The rotation sensor 42 acquires rotation information in the pitch direction.

For example, the rotation sensor 42 can use an angular velocity sensor such as a gyro sensor. In this case, the output of the rotation sensor 42 is an angular velocity ω _p around the pitch axis. A commercially available sensor in which the acceleration sensor 40 and the rotation sensor 42 are integrated may be used.

  The lift suppression unit 50 acquires the position information of the falling fulcrum based on the output of the acceleration sensor 40 and the output of the rotation sensor 42 acquired at the moment of lifting of the traveling body 2.

The lift suppression unit 50 may determine that the lift occurs when the angular velocity ω _p that is the output of the rotation sensor 42 exceeds a predetermined threshold. Alternatively, the lift suppression unit 50 may determine that the lift occurs when the angular acceleration ω _p ′ obtained by differentiating the angular velocity ω _p that is the output of the rotation sensor 42 exceeds a predetermined threshold. .

FIG. 13 is a diagram for explaining the principle of acquiring the position of the falling fulcrum. The distance of tipping fulcrum _{P 1} and the acceleration sensor 40 and L. Falling excavator 1 can be regarded as rotational motion about tipping fulcrum P _1. The acceleration in the rotational direction at that time is L (ω _p ) ′, and the angular acceleration in the centrifugal force direction is Lω _p ² . Note that L = √ (x ² + z ² ). 'Represents time derivative.

By utilizing the output of the acceleration sensor 40, it is possible to obtain the acceleration A _theta, A _r direction of rotation and centrifugal force direction (radial direction). Then
A _θ = L (ω _p ) ′
A _r = Lω _p ²
Therefore, L can be calculated. A _θ, from A _r influence of gravitational acceleration has been removed. Since z is the height at which the acceleration sensor 40 is attached, z is a known parameter, and if L is obtained, x, that is, position information of the falling fulcrum P ₁ can be obtained.

  In one embodiment, the position information may be acquired by the following method.

When the acceleration sensor 40 is provided at the position shown in FIG. 13, Equation (11) is obtained.

The first term on the right side is a formula that holds for rotational motion, and the second term on the right side is a term that indicates the influence of gravity. A _x and A _z are outputs of the acceleration sensor 40. θ _p represents a rotation angle, θ _p ′ represents a rotation angular velocity, and θ _p ″ represents a rotation angular acceleration. When a gyro sensor is used, the output ω _{p of the} gyro sensor can be used as θ _p ′. The differential value of the output ω _p of the gyro sensor can be used as the rotational angular acceleration θ _p ″, and the integrated value of the output ω _p of the gyro sensor can be used as the rotational angle θ _p .

By solving Equation (11) with x as an unknown, the position information of the fall fulcrum P ₁ can be obtained.

It should be noted that the determinant (11) is redundant with respect to a single variable x, including the expression on the first line in the x direction and the expression on the second line in the z direction. Therefore, if only one of A _x and A _z is measured, x can be calculated.

  Alternatively, the determinant (11) may be solved as a simultaneous equation with x and z as variables.

  FIG. 14 is a block diagram illustrating a process for obtaining position information. In the figure, each element described as a functional block for performing various processes can be configured with a CPU, a memory, and other LSIs in terms of hardware, and loaded into the memory in terms of software. Realized by programs. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof, and is not limited to any one.

The output ω _{p of the} angular velocity sensor is integrated by the integrator 60, and the rotation angle θ _p is calculated. Then, a rotation matrix R (θ _p ) 62 based on the rotation angle θ _p is generated, and the multiplier 64 multiplies the rotation matrix R (θ _p ) by the gravitational acceleration g, whereby the second term on the right side of the equation (11) is Calculated. Then, the subtractor 66 subtracts the output of the multiplier 64 from the accelerations A _x and A _z obtained by the acceleration sensor 40, thereby removing the influence of gravity.

The differentiator 68 differentiates the output ω _{p of the} angular velocity sensor to generate an angular acceleration θ _p ″. The angular velocity ω _p (θ _p ′) and the angular acceleration θ _p ″ are input to the calculator 70. The computing unit 70 calculates the coordinates x (and z) based on a predetermined calculation formula.

Note that θ _p ″ is easily affected by noise because it is obtained by differential operation. Therefore, the two equations included in the equation (11) are expressed by using z as a known value and x and θ _p ″ as variables. May be solved as simultaneous equations.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Excavator, 2 ... Traveling body, 2A, 2B ... Traveling hydraulic motor, 3 ... Turning apparatus, 4 ... Turning body, 4a ... Driver's cab, 5 ... Boom, 6 ... Arm, 7 ... Boom cylinder, 8 ... Arm cylinder, DESCRIPTION OF SYMBOLS 9 ... Bucket cylinder, 10 ... Bucket, 11 ... Engine, 12 ... Attachment, 14 ... Main pump, 15 ... Pilot pump, 17 ... Control valve, 21 ... Swing hydraulic motor, 26 ... Operating device, 27 ... Pilot line, 30 ... Controller: 600 ... Lifting suppression unit, 602 ... Force estimation unit, 610 ... Sensor, 620 ... Condition setting unit, 630 ... Correction unit, 510, 512 ... Pressure sensor, 520 ... Electromagnetic proportional relief valve, 530 ... Electromagnetic proportional control valve.

Claims (10)

An excavator,
A traveling body,
An upper swing body provided rotatably on the traveling body;
An attachment having a boom, an arm, and a bucket, and attached to the upper swing body;
A lift suppression unit that corrects the operation of the attachment such that the lift of the traveling body is suppressed; and
With
The excavator characterized in that the control condition in the lifting suppression unit is set based on information acquired at the moment of lifting of the traveling body.   The lift control unit acquires position information of a fall fulcrum based on the information acquired at the moment of lifting of the traveling body, and defines the control condition based on the position information. Item 2. The excavator according to Item 1. The excavator according to claim 1 or 2, wherein the information acquired at the moment when the traveling body is lifted includes a force _{F1_INIT} that a boom cylinder exerts on the upper swing body. An acceleration sensor attached to the traveling body or the upper swing body and a rotation sensor for acquiring rotation information in the pitch direction;
The excavator according to claim 2, wherein the lift suppression unit acquires position information of the fall fulcrum based on an output of the acceleration sensor and an output of the rotation sensor.   The shovel according to claim 4, wherein the lift suppression unit removes the influence of gravitational acceleration from the output of the acceleration sensor. The rotation sensor is an angular velocity sensor;
The at least one of when the output of the angular velocity sensor exceeds a predetermined value and when the differential value of the output of the angular velocity sensor exceeds a predetermined value is defined as the moment of lifting of the traveling body. The excavator according to 4 or 5. An excavator,
A traveling body,
An upper swing body provided rotatably on the traveling body;
An attachment having a boom, an arm, and a bucket, and attached to the upper swing body;
A lift suppression unit that corrects the operation of the attachment such that the lift of the traveling body is suppressed; and
With
The floating suppression part is
A sensor for detecting the moment of lifting of the traveling body;
When the force F ₁ exerted by the boom cylinder on the upper swing body is obtained, the force F _{1_INIT} at the moment of lifting is obtained, and the parameter related to the position of the overturning fulcrum is obtained based on the force F _{1_INIT.} A condition setting unit for setting a control condition based on
A correction unit that corrects the operation of the attachment based on the control condition;
Excavator characterized by including. The distance between the center of gravity of the vehicle body of the excavator and the overturning fulcrum of the traveling body is D _A , the distance between the connection point between the boom cylinder and the upper swing body and the overturning fulcrum is D _B , the weight of the vehicle body is M, gravity when the acceleration is g, the condition setting section, the moment of the lifting _{D B} F _{1_INIT} = D a Mg
The distances D _A and D _B are acquired as follows.
D _B F ₁ <D _A Mg
The excavator according to claim 5, wherein the control condition is set. The condition setting unit, when the posture of the attachment is changed, shovel according to claim 6, characterized in that varying the D _B included in the control condition. An excavator,
A traveling body,
An upper swing body provided rotatably on the traveling body;
An attachment having a boom, an arm, and a bucket, and attached to the upper swing body;
A control condition according to the position of the falling fulcrum, and a lift suppression unit that corrects the operation of the attachment so that the lift of the traveling body is suppressed based on the set control condition;
An excavator characterized by comprising:

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