Patent Grant
11668069
The present invention relates to a construction machine such as a hydraulic excavator.
In recent years, to respond to a need for computerized work, there are some construction machines including hydraulic excavators have a function of machine guidance, by which a position or posture of a work mechanism, such as a boom, an arm, and a bucket, is displayed for an operator and a function of machine control, by which the position of the work mechanism is controlled such that the work mechanism moves along a target work surface. Known techniques representing the foregoing functions include one displaying a bucket distal end position and a bucket angle of the hydraulic excavator on a display and one limiting movement of the bucket distal end as the bucket distal end approaches the target work surface so as not to allow the bucket distal end to advance further.
In construction work, compaction work (also known as “bumping work”) is performed as a finishing step following leveling work, in which the ground is compacted by a bucket back surface bumping against the ground. Known techniques supporting the compaction work are disclosed in, for example, Patent Documents 1 and 2.
Patent Document 1 discloses a technique, in which control is changed between the leveling work and the compaction work on the basis of an operation signal from an operation member (e.g., an operation lever) for operating a work implement and, during the compaction work, a velocity of the work implement advancing toward the design terrain profile is limited according to a distance between the work implement and the design terrain profile.
Patent Document 2 discloses a technique, in which a reach of a front work implement is detected and control to vary a pump flow rate or an opening angle of a control valve is performed according to the magnitude of the reach, to thereby make constant a relation between a lever operation amount and a bucket (attachment) movement regardless of changes in the reach.
In the compaction work, strength (depressing force) with which the bucket back surface is bumped against the ground is a factor determining a level of workmanship of a finished surface. This is because variations in the depressing force exerted by the bucket back surface result in irregularities on the finished surface. Thus, to produce a finished surface with high quality, how to maintain a uniform depressing force is a major challenge to be addressed. The depressing force is defined as a product of the bucket velocity and inertia of the front work implement (front inertia) and the front inertia varies according to posture of the front work implement.
Against the foregoing background, with the technique disclosed in Patent Document 1, although the bucket velocity is limited to a constant level or lower depending on the distance between the work implement and the design terrain profile during the compaction work, the front inertia is varied with the posture of the front work implement, resulting in the depressing force fluctuating. With the technique disclosed in Patent Document 2, while the bucket velocity with respect to the boom operation amount remains constant regardless of the reach of the front work implement, the operator needs to adjust the boom operation amount according to the posture of the front work implement in order to make the depressing force uniform, and a high level of expertise is, therefore, required to make the depressing force uniform.
The present invention has been made in view of the foregoing situation and it is an object of the present invention to provide a construction machine that can make a depressing force of a bucket uniform during compaction work without requesting an operator to perform a complicated operation.
To achieve the foregoing object, an aspect of the present invention provides a construction machine that includes: a machine body; an articulated front work implement disposed anterior to the machine body and including a boom, an arm, and a bucket; a plurality of hydraulic actuators including a boom cylinder that drives the boom, an arm cylinder that drives the arm, and a bucket cylinder that drives the bucket; an operation device that is operated by an operator to instruct an operation of each of the boom, the arm, and the bucket; a boom posture sensor that senses posture of the boom; an arm posture sensor that senses posture of the arm; a bucket posture sensor that senses posture of the bucket; and a controller that controls drive of the hydraulic actuators in response to an operation of the operation device, the controller setting a leveling target surface, determining target velocities of the boom, the arm, and the bucket such that the bucket does not advance further down the leveling target surface, and, during leveling work, notifying the operator of details of an operation of the operation device for achieving the target velocities of the arm and the bucket or controlling drive of the hydraulic actuators so as to achieve the target velocities of the arm and the bucket. In the construction machine, the controller determines whether or not compaction work is in progress, calculates a front distance that represents a distance between a rotational pivot of the boom and a predetermined position in a back surface of the bucket, determines the target velocity of the bucket such that a velocity with which the bucket approaches the leveling target surface decreases with increasing values of the front distance, and, during the compaction work, notifies the operator of details of an operation of the operation device, the details being used for achieving the target velocity of the bucket, or controls drive of the hydraulic actuators so as to achieve the target velocity of the bucket.
In accordance with the aspect of the present invention having configurations as described above, during the compaction work, the target velocity of the bucket is determined such that the velocity with which the bucket approaches the leveling target surface decreases with increasing values of the front distance and the operator is notified of details of the operation of the operation device for achieving the target velocity of the bucket or the hydraulic actuators are controlled so as to achieve the target velocity of the bucket. The operator thereby can make the depressing force of the bucket uniform during the compaction work without the need to perform a complicated operation.
The present invention enables the depressing force of the bucket to be uniform during the compaction work without requesting the operator to perform a complicated operation.
Embodiments of the present invention will be described below with reference to the accompanying drawings and using a hydraulic excavator including, as a work device, a bucket at a distal end of a front implement (front work implement), as a construction machine according to the embodiments of the present invention. In the drawings, like or corresponding parts are identified by identical reference characters and descriptions for those parts will be omitted as appropriate.
In
The boom 4, the arm 5, and the bucket 6 operate on a single plane (hereinafter referred to as an operating plane). The operating plane is orthogonal to a rotational axis of each of the boom 4, the arm 5, and the bucket 6. The operating plane can be set so as to pass through a center in a width direction of the boom 4, the arm 5, and the bucket 6.
A cab 9, in which an operator rides, is provided with left and right operation lever devices (operation devices) 9a and 9b, which output operation signals for operating the hydraulic actuators 2a to 6a. The left and right operation lever devices 9a and 9b each include an operation lever and a sensor. The operation lever can be tilted in a fore-aft direction and a left-right direction. The sensor electrically senses an operation signal that corresponds to an inclination amount of the operation lever (lever operation amount). The left and right operation lever devices 9a and 9b each output the lever operation amount sensed by the sensor to a controller 18 (depicted in
Operation control for the boom cylinder 4a, the arm cylinder 5a, the bucket cylinder 6a, the swing motor 2a, and the left and right track motors 3a is performed through control with a control valve 8 of directions and flow rates of hydraulic fluid to be supplied to the respective hydraulic actuators 2a to 6a from a hydraulic pump unit 7, which is driven by a prime mover such as an engine and an electric motor not depicted. The control of the control valve 8 is performed through a drive signal (pilot pressure) output from a pilot pump not depicted via a solenoid proportional valve. The solenoid proportional valve is controlled by the controller 18 on the basis of the operation signal from the left and right operation lever devices 9a and 9b. The operation of each of the hydraulic actuators 2a to 6a is thereby controlled.
It is noted that the left and right operation lever devices 9a and 9b may be operated as a hydraulic pilot operated system and a pilot pressure corresponding to a direction in which, and an amount over which, the operation lever is operated by the operator is supplied as a drive signal to the control valve 8 to thereby drive the corresponding one of the hydraulic actuators 2a to 6a.
IMUs (Inertial Measurement Units) 12 and 14 to 16, as posture sensors, are disposed in the upper swing structure 2, the boom 4, the arm 5, and the bucket 6, respectively. The inertial measurement units may, in the following, be referred to specifically as a machine body inertial measurement unit 12, a boom inertial measurement unit 14, an arm inertial measurement unit 15, and a bucket inertial measurement unit 16, when one is to be differentiated from another.
The inertial measurement units 12 and 14 to 16 measure angular velocity and acceleration. Consider a condition in which the upper swing structure 2, and the driven members 4 to 6, in which the inertial measurement units 12 and 14 to 16 are disposed, are stationary. An orientation (posture: posture angle θ to be described later) of each of the upper swing structure 2, and the driven members 4 to 6 can be sensed on the basis of a direction of gravitational acceleration (specifically, a vertical downward direction) in an IMU coordinate system set for each of the inertial measurement units 12 and 14 to 16 and a mounting condition of each of the inertial measurement units 12 and 14 to 16 (specifically, positional relations of the inertial measurement units 12 and 14 to 16 relative to the upper swing structure 2, and the driven members 4 to 6, respectively). It is here noted that the boom inertial measurement unit 14 constitutes a boom posture sensor that senses information on the posture of the boom 4 (hereinafter referred to as posture information), the arm inertial measurement unit 15 constitutes an arm posture sensor that senses posture information of the arm 5, and the bucket inertial measurement unit 16 constitutes a bucket posture sensor that senses posture information of the bucket 6.
It is noted that the posture information sensor is not limited to the inertial measurement unit and an inclination angle sensor may, for example, be used. Alternatively, a potentiometer may be disposed at a connection portion of each of the driven members 4 to 6 and relative orientations (posture information) of the upper swing structure 2 and each of the driven members 4 to 6 are sensed. The posture of each of the driven members 4 to 6 may then be found from sensing results. Alternatively, a stroke sensor may be disposed in each of the boom cylinder 4a, the arm cylinder 5a, and the bucket cylinder 6a. The relative orientation (posture information) in each connection portion of the upper swing structure 2, and the driven members 4 to 6 is then calculated from a stroke change amount and the posture of each of the driven members 4 to 6 (posture angle θ) is found from calculation results.
In
The compaction work support control section 18a calculates, on the basis of the sensing results from the inertial measurement units 12 and 14 to 16 and an input from the leveling target surface setting section 18d (to be described later), a front distance (reach) that represents a distance between a boom foot pin as a rotational center for the boom 4 and a predetermined position in a back surface of the bucket 6 and a bucket position in a machine body coordinate system. Additionally, a target velocity of the bucket 6 for compaction work is calculated on the basis of machine body information including the front distance and the bucket position. Detailed calculations will be described later.
The operation instruction display control section 18b controls display on a monitor not depicted disposed in the cab 9 and voice of a speaker not depicted. On the basis of the posture information of the front work implement 1 and the bucket target velocity which are calculated by the compaction work support control section 18a, the operation instruction display control section 18b calculates instruction details for operation support to be given to the operator and displays the instructions on the monitor in the cab 9 or notifies the operator of the instructions by voice.
Specifically, the operation instruction display control section 18b performs parts of functions as a machine guidance system that aids the operator in performing operations by, for example, displaying on the monitor the posture of the front work implement 1, which includes the driven members including the boom 4, the arm 5, and the bucket 6, and the distal end position, angle, and velocity of the bucket 6.
The hydraulic system control section 18c controls a hydraulic system of the hydraulic excavator 100, including the hydraulic pump unit 7, the control valve 8, and the hydraulic actuators 2a to 6a. On the basis of the posture information of the front work implement 1 and the bucket target velocity which are calculated by the compaction work support control section 18a, the hydraulic system control section 18c calculates an operation of the front work implement 1 and controls the hydraulic system of the hydraulic excavator 100 so as to achieve the operation. Specifically, the hydraulic system control section 18c performs parts of functions as a machine control system that controls to limit the operation of the front work implement 1 so as not, for example, to allow the back surface of the bucket 6 to hit against the leveling target surface with an excessive force or to allow any part of the bucket 6 other than the back surface to contact the leveling target surface.
The leveling target surface setting section 18d calculates a leveling target surface that defines a target geometry of an object to be leveled on the basis of design terrain profile data 17, which includes three-dimensional work drawings previously stored by a construction administrator in a storage device not depicted.
The hydraulic excavator 100 according to a first embodiment of the present invention will be described with reference to
In
The bucket position calculation section 18a1 calculates coordinates of the predetermined position in the back surface of the bucket 6 and the front distance (reach) to correspond to the output from each of the posture sensors of the boom 4, the arm 5, and the bucket 6 (specifically, each of the inertial measurement units 14 to 16).
A method for calculating the predetermined position in the back surface of the bucket 6 and the front distance will be described with reference to
The bucket position calculation section 18a1 calculates the coordinates of a predetermined position B in the back surface of the bucket 6 using a position O of the boom foot pin as a rotational pivot of the boom 4 as a coordinate origin. It is noted that the predetermined position B in the back surface may be set at any position on the bucket back surface in contact with the leveling target surface during the compaction work.
Let a boom length Lbm denote a distance between the position O of the boom foot pin and a rotational pivot of the arm 5 (a connection portion between the boom 4 and the arm 5), let an arm length Lam denote a distance between the rotational pivot of the arm 5 and a rotational pivot of the bucket 6 (a connection portion between the arm 5 and the bucket 6), and let a bucket length Lbk denote a distance between the rotational pivot of the bucket 6 and the predetermined position B in the back surface of the bucket 6. Then, coordinate values (x, y) in a front coordinate system of the predetermined position B in the back surface of the bucket 6 can be obtained with expressions (1) and (2) given below, where θbm, θam, and θbk denote angles (posture angles) of the boom 4, the arm 5, and the bucket 6 (to be more precise, orientations of the boom length Lbm, the arm length Lam, and the bucket length Lbk) relative to a horizontal direction, respectively.
[Expression 1]
X=Lbm cos θbm+Lam cos θam+Lbk cos θbk (1)
[Expression 2]
y=Lbm sin θbm+Lam sin θam+Lbk sin θbk (2)
A front distance R represents a distance between the position O of the boom foot pin and the predetermined position B in the back surface of the bucket 6 and can be obtained with expression (3) given below.
[Expression 3]
R=√{square root over (x2+y2)} (3)
When a machine body grounding surface of the hydraulic excavator 100 and the leveling target surface exist in an identical plane as depicted in
The bucket target velocity determination section 18a2 calculates the target velocity of the bucket 6 during the compaction work on the basis of the front distance R calculated by the bucket position calculation section 18a1. The bucket target velocity is defined so as to take a positive value when the bucket 6 approaches the leveling target surface.
An example of calculation performed by the bucket target velocity determination section 18a2 will be described with reference to
The front distance R relative to the front inertia depicted in
The bucket target velocity determination section 18a2 is characterized by decreasing the bucket target velocity with increasing values of the front distance R, specifically, with increasing the front inertia, to thereby make constant the depressing force that is represented by a unit of a physical quantity representing a product of the front inertia and the bucket velocity regardless of the front distance R.
The control changeover section 18a3 enables or disables the present control according to an output from a compaction work determination section 18f, which determines whether or not compaction work is in progress. The compaction work determination section 18f may enable the control at any timing through an operation by the operator or may determine the changeover automatically using a specific work condition. Another possible configuration is such that a signal of a leveling work support control section 18e is enabled when the compaction work support is terminated (placing the control changeover section 18a3 in a disabled position).
The leveling work support control section 18e includes a front target velocity determination section 18e1. The front target velocity determination section 18e1 determines the target velocity of each of the boom 4, the arm 5, and the bucket 6 such that the predetermined position (e.g., claw tip position) of the bucket 6 obtained by the bucket position calculation section 18a1 does not reach below the leveling target surface obtained by the leveling target surface setting section 18d. Details of the front target velocity determination section 18e1 fall outside the scope of the present invention and descriptions therefor will be omitted.
The operation instruction display control section 18b includes an operation instruction determination section 18b1 and an operation instruction display section 18b2.
The operation instruction determination section 18b1 calculates, during leveling work, a lever operation that achieves each of the target velocities of the boom 4, the arm 5, and the bucket 6 determined by the front target velocity determination section 18e1. During compaction work, the operation instruction determination section 18b1 calculates a lever operation that achieves the bucket target velocity calculated by the bucket target velocity determination section 18a2.
The operation instruction display section 18b2 performs information processing for displaying on the monitor in the cab 9 the details of the operation (e.g., lever operation amount) determined by the operation instruction determination section 18b1 and transmitting the instruction by voice through a speaker in the cab 9.
The hydraulic system control section 18c includes a control amount determination section 18c1 and a work implement velocity adjustment section 18c2.
During the leveling work, the control amount determination section 18c1 calculates target values of target velocities of the cylinders 4a to 6a such that the target velocities of the boom 4, the arm 5, and the bucket 6 determined by the front target velocity determination section 18e1 are achieved, and target values of amounts of hydraulic fluid to be supplied to the cylinders 4a and the like for achieving the cylinder target velocities. During the compaction work, the control amount determination section 18c1 calculates target values of target velocities of the cylinders 4a to 6a such that the bucket target velocity calculated by the bucket target velocity determination section 18a2 is achieved, and target values of amounts of hydraulic fluid to be supplied to the cylinders for achieving the cylinder target velocities.
The work implement velocity adjustment section 18c2 controls the hydraulic pump unit 7 and the control valve 8 to thereby achieve the target values of the amounts of hydraulic fluid to be supplied to the cylinders 4a to 6a calculated by the control amount determination section 18c1.
The hydraulic system control section 18c enables any desired bucket target velocity to be achieved regardless of the lever operation amount by the operator.
Effects achieved by the hydraulic excavator 100 according to the present embodiment, having configurations as described above, will be described through a comparison with the known art.
With the technique disclosed in Patent Document 2, having the predetermined lever operation amount allows the bucket lowering velocity to remain constant regardless of the front distance R. The depressing force is defined as the product of the bucket lowering velocity and the front inertia. Because the front inertia increases according to the front distance R, the depressing force increases with increasing values of the front distance R when the bucket lowering velocity remains constant. Thus, with the technique disclosed in Patent Document 2, the operator needs to adjust the lever operation amount according to the front distance R in order to make the depressing force uniform, and a high level of expertise is, therefore, required to make the depressing force uniform.
In contrast, with the hydraulic excavator 100 in the present embodiment, during the compaction work, the bucket target velocity is determined such that the velocity with which the bucket 6 approaches the leveling target surface decreases with increasing values of the front distance R and the operator is notified of details of the operations of the operation lever devices 9a and 9b for achieving the bucket target velocity or drive of the hydraulic actuators 4a to 6a is controlled so as to achieve the bucket target velocity. The operator thereby can make the depressing force of the bucket 6 uniform during the compaction work without the need to perform complicated operations.
A hydraulic excavator 100 according to a second embodiment of the present invention will be described with reference to
When a front work implement 1 is jerked on an unsteady site, as on soft earth, a machine body (an upper swing structure 2 and a lower track structure 3) of the hydraulic excavator 100 oscillates in a pitch direction as the front work implement 1 rotates.
Changes in the depressing force when the machine body oscillates in the pitch direction will be described with reference to
Because the machine body anterior portion has a velocity acting in the direction of leaving the ground at a time A, the final depressing force is smaller than the depressing force by the front work implement 1. At a time B, the machine body is stationary and the depressing force by the front work implement 1 is directly the final depressing force. At a time C, because the machine body anterior portion has a velocity acting in the direction in which the machine body anterior portion approaches the ground, the final depressing force is greater than the depressing force by the front work implement 1.
In the first embodiment, the depressing force of the bucket 6 may be non-uniform when the compaction work is performed under a condition in which the machine body oscillates in the pitch direction. The present embodiment provides a solution to the foregoing problem.
An example of calculation performed by the bucket target velocity determination section 18a2 according to the present embodiment will be described with reference to
At the time t1, the front inertia is small and the machine body is stationary. The bucket target velocity calculated at this time is denoted as vb1 and a comparison is made among the bucket target velocities at different times.
At the time t2, the front inertia remains the same, unchanged from the time t1. Because the machine body anterior portion has a velocity in the direction in which the machine body anterior portion is raised from the ground, however, the depressing force is maintained by making the bucket target velocity greater than vb1.
At the time t3, the front inertia remains the same, unchanged from the time t1. Because the machine body anterior portion has a velocity in the direction in which the machine body anterior portion approaches the ground, however, the depressing force is maintained by making the bucket target velocity smaller than vb1.
At the time t4, the machine body is stationary although the front inertia is greater than at the time t1. Thus, the depressing force is maintained by setting the bucket target velocity to vb2, which is smaller than vb1.
At the time t5, the machine body anterior portion has a velocity in the direction in which the machine body anterior portion is raised from the ground, although the front inertia remains the same, unchanged from the time t4. Thus, the depressing force is maintained by making the bucket target velocity greater than vb2. It is noted that, although the bucket target velocity is smaller than vb1 at the time t5 in
At the time t6, the machine body anterior portion has a velocity in the direction in which the machine body anterior portion approaches the ground, although the front inertia remains the same, unchanged from the time t4. Thus, the depressing force is maintained by making the bucket target velocity smaller than vb2. The bucket target velocity is the smallest with a combination of the time t6.
While
A large depressing force is generated particularly when a cycle of the machine body pitch velocity is synchronized with the bucket velocity. This is effective for obtaining the depressing force in posture that yields small front inertia.
It should, however, be noted that synchronizing the cycle of the machine body pitch velocity with the bucket velocity in posture that yields large front inertia generates an excessive depressing force. In this case, the equivalent depressing force may not be able to be generated even when the bucket velocity is maximized in the posture yielding the small front inertia. Thus, when the front distance R is great, preferably the bucket target velocity is determined so as not to allow the cycle of the machine body pitch velocity to be synchronized with the bucket velocity.
The cycle of the machine body pitch velocity can be determined by recording sensed values of the machine body velocity sensor 12 for a predetermined period of time and analyzing the recorded data.
The hydraulic excavator 100 according to the present embodiment, having configurations as described above, can achieve effects similar to the effects achieved by the first embodiment.
Additionally, the target velocity of the bucket 6, which is established to correspond to the front distance R, is corrected according to the machine body pitch velocity. Thus, the depressing force of the bucket 6 can be made uniform even when the compaction work is performed while the machine body oscillates in the pitch direction.
A hydraulic excavator 100 according to a third embodiment of the present invention will be described with reference to
An extension/contraction velocity of each of cylinders 4a to 6a of the hydraulic excavator 100 has an upper limit. The bucket velocity thus has a physical upper limit. The second embodiment does not consider this upper limit value in calculating the bucket target velocity. The present embodiment enables support for effective compaction work in which the upper limit value of the bucket velocity is taken into consideration.
A controller 18 according to the present embodiment has a configuration identical to the configuration in the second embodiment (depicted in
An example of calculation performed by the bucket target velocity determination section 18a2 according to the present embodiment will be described with reference to
At a time t7, behavior is indicated in which the front inertia is a maximum Imax and the velocity with which the machine body anterior portion approaches the ground is a maximum Mmin (“min” because of a negative value). The depressing force achieved at this time is denoted as F1.
At a time t8, behavior is indicated in which the front inertia is a minimum Imin and the velocity with which the machine body anterior portion approaches the ground is the maximum Mmin. Under the foregoing condition, the depressing force F1 can be maintained only when the bucket velocity is greater than at the time t7. Thus, the depressing force F1 is maintained by setting the bucket target velocity at the time t8 to a maximum value vmax of the bucket velocity to be achieved by the front work implement 1.
At times t9 and t10, the front inertia is a minimum Imin and the machine body is stationary or the machine body anterior portion has a velocity in the direction in which the machine body anterior portion is raised from the ground. Thus, the bucket target velocity required for achieving the depressing force F1 is greater than the maximum value vmax. The front work implement 1 is, however, unable to achieve the bucket velocity greater than the maximum value vmax and thus the depressing force F1 cannot be achieved at the times t9 and t10.
When the bucket target velocity required for achieving the depressing force F1 is greater than the maximum value vmax of the bucket velocity achieved by the front work implement 1 as described above, preferably an operation instruction display control section 18b notifies the operator of the deficiency in the depressing force or prompts the operator to increase the number of hits against the ground.
Alternatively, the bucket target velocity may be set to vmin so as to achieve only a minimum depressing force F2, as at a time t11, at which the front inertia and the machine body pitch velocity are identical to those at the time t7. A caution is, however, needed in this case for an increased number of hits against the ground due to the insufficient depressing force, though a satisfactory level of workmanship of a finished surface can be achieved.
To bring the details of the control illustrated in
In Step FC1, the depressing force F2 when the machine body pitch velocity is 0 is set. While
In Step FC2, the depressing force F1 generated when the bucket velocity is synchronized with the machine body pitch velocity is calculated using the front distance calculated by a bucket position calculation section 18a1 and the machine body pitch velocity measured by a machine body velocity sensor 12.
In Step FC3, a difference is found between the depressing forces F1 and F2 calculated in Steps FC1 and FC2, respectively, and an increment Δv in the bucket velocity required for compensating for the difference is calculated.
In Step FC4, a comparison is made between the maximum velocity vmax and a bucket target velocity v2 calculated when the front posture is a minimum distance, specifically, when the front inertia is Imin, under a characteristic that the machine body pitch velocity is 0, specifically, the depressing force F2 is generated, to which the velocity increment Δv calculated in Step FC3 is added (v2+Δv).
When “v2+Δv≤vmax,” the depressing force F1 can be achieved and Step FC5 is performed and synchronization is enabled between a bucket approaching velocity and the machine body pitch velocity.
When “v2+Δv>vmax,” the depressing force F1 cannot be achieved due to the velocity upper limit. Step FC6 is then performed and the synchronization is not enabled between the bucket approaching velocity and the machine body pitch velocity.
The foregoing control is performed for every arithmetic operation cycle of the controller 18.
The hydraulic excavator 100 according to the present embodiment, having configurations as described above, can achieve effects similar to the effects achieved by the second embodiment.
Additionally, the synchronization between the bucket approaching velocity and the machine body pitch velocity is enabled only when the depressing force F1 can be achieved uniformly over an entire range of the front distance R. Thus, the bucket depressing force can be made uniform even when the compaction work is performed with the front distance R being varied from the minimum distance to the maximum distance.
A hydraulic excavator according to a fourth embodiment of the present invention will be described with reference to
When the machine body grounding surface of the hydraulic excavator 100 differs from the leveling target surface as illustrated in
A bucket position calculation section 18a1 in the present embodiment calculates coordinates of a predetermined position B in a back surface of a bucket 6, including an inclination of the machine body sensed by the machine body angle sensor. More specifically, a rotation matrix considering a machine body angle θbody is applied to the coordinates calculated with the expressions (1) and (2).
The bucket position calculation section 18a1 also calculates the angle θsurf (hereinafter referred to as the target surface angle) formed between a straight line that connects the rotational pivot of the boom 4 and the arm 5 with the rotational pivot of the arm 5 and the bucket 6 (the longitudinal direction of the arm 5) and a normal direction to the leveling target surface. The target surface angle θsurf is as indicated in
A bucket target velocity determination section 18a2 in the present embodiment is characterized by using the target surface angle θsurf for calculating the bucket target velocity.
Changes in the depressing force caused by the target surface angle θsurf will be first described with reference to
On the basis of the foregoing, details of arithmetic operations performed by the bucket target velocity determination section 18a2 according to the present embodiment will be described with reference to
At a time t12, the front inertia is small and the target surface angle is large. The following described how the bucket target velocity varies from times t13 to t17 with reference to a bucket target velocity vb3 at this time.
At a time t13, the front inertia remains the same as that at the time t12; however, the absolute value of the target surface angle is smaller than at the time t12, and the bucket target velocity is, therefore, smaller than vb3. The target surface angle is further smaller at a time t14 than at the time t13 and the bucket target velocity is also smaller than at the time t13.
At a time t15, while the target surface angle remains the same as that at the time t12, the front inertia is greater than at the time t12. In this case, in accordance with the control of the first embodiment, the bucket target velocity is smaller to correspond to the increment of the front inertia.
At times t16 and t17, only the target surface angle changes, while the front inertia remains the same as that at the time t15. When the front inertia is large, too, the bucket target velocity increases with decreasing target surface angles.
To bring the details of the control illustrated in
The hydraulic excavator 100 according to the present embodiment, having configurations as described above, can achieve effects similar to the effects achieved by the first embodiment.
Additionally, the target velocity of the bucket 6 determined according to the front distance R is corrected such that the velocity at which the bucket 6 approaches the leveling target surface decreases with the angle (target surface angle) θsurf formed between the longitudinal direction of the arm 5 and the normal direction to the leveling target surface approaching 0. The foregoing approach enables the depressing force of the bucket 6 to be uniform even when the compaction work is performed through changing the target surface angle θsurf greatly.
It should be noted that the present invention is not limited to the above-described embodiments and may include various modifications. For example, the entire detailed configuration of the embodiments described above for ease of understanding of the present invention is not always necessary to embody the present invention. The configuration of each embodiment may additionally include another configuration, or part of the configuration may be deleted or replaced with another.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2017-218071 | Nov 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/041499 | 11/8/2018 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2019/093424 | 5/16/2019 | WO | A |
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| 5735065 | Yamagata | Apr 1998 | A |
| 11001985 | Ito | May 2021 | B2 |
| 20170268204 | Shimano | Sep 2017 | A1 |
| 20190249391 | Kikuchi et al. | Aug 2019 | A1 |
| Number | Date | Country |
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| 2007-9432 | Jan 2007 | JP |
| 2012-112108 | Jun 2012 | JP |
| 2012-225084 | Nov 2012 | JP |
| 2017-166308 | Sep 2017 | JP |
| 2016125916 | Aug 2016 | WO |
| 2018179577 | Oct 2018 | WO |
| Entry |
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| International Preliminary Report on Patentability received in corresponding International Application No. PCT/JP2018/041499 dated May 28, 2020. |
| International Search Report PCT/JP2018/041499 dated Dec. 25, 2018. |
| Number | Date | Country | |
|---|---|---|---|
| 20210040705 A1 | Feb 2021 | US |
