Patent Description:
Patent Literature <NUM> discloses a system that automatically controls and causes a hydraulic excavator to discharge soil to a transporter vehicle stopped at a loading position. In Patent Literature <NUM>, automatic soil discharge is executed while detecting a position of a loading bed of a transporter vehicle from an image captured by a camera.

However, when only the bucket is rotated at the time of discharging a transport object (such as soil and sand), there occurs a variation in the position where the transport object is loaded on a loading target (a loading bed of a transporter vehicle or the like). For example, in accordance with soil properties of the soil and sand, the soil and sand are discharged at an early stage of the rotational move, or the soil and sand are discharged at a late stage of the rotational move, so that the loading position of the soil and sand varies. Therefore, it is preferable that the transport object can be loaded at a fixed point of the loading target.

An object of the present invention is to provide a work machine capable of loading a transport object at a fixed point of a loading target.

The present invention includes: a machine body; a boom attached to the machine body to be rotatable in an up-and-down direction; an arm attached to the boom to be rotatable in the up-and-down direction; a bucket attached to the arm to be rotatable in a front-and-rear direction; and a controller that causes the boom, the arm, and the bucket to automatically perform an operation of discharging a transport object held by the bucket by driving the boom, the arm, and the bucket, based on a target loading point set above a loading target, wherein after the controller causes the bucket to rotate such that an opening surface of the bucket becomes vertical at the target loading point, the controller drives the boom, the arm, and the bucket such that the opening surface of the bucket faces downward while maintaining a position, with respect to the machine body, of a leading end of the bucket in the front-and-rear direction.

According to the present invention, after the bucket is rotated such that the opening surface of the bucket becomes vertical at the target loading point, the boom, the arm, and the bucket are driven such that the opening surface of the bucket faces downward while the position, with respect to the machine body, of the leading end of the bucket in the front-and-rear direction is maintained. By causing the opening surface of the bucket to face downward while maintaining the position, with respect to the machine body, of the leading end of the bucket, the position where the transport object is discharged can be made substantially the same from the early stage to the late stage of the rotation of the bucket. As a result, the transport object can be loaded at the fixed point of the loading target.

In the following, a preferred embodiment of the present invention will be described with reference to the drawings.

A work machine according to an embodiment of the present invention automatically performs an operation of discharging a transport object held by a bucket. As illustrated in <FIG>, which is a side view of a work machine <NUM>, the work machine <NUM> is a machine that performs work with an attachment <NUM>, and is, for example, a hydraulic excavator. The work machine <NUM> has: a machine body <NUM> including a lower travelling body <NUM> and an upper slewing body <NUM>; the attachment <NUM>; and cylinders <NUM>.

The lower travelling body <NUM> is a portion that causes the work machine <NUM> to travel, and includes, for example, a crawler. The upper slewing body <NUM> is slewably attached to an upper part of the lower travelling body <NUM> via a slewing device <NUM>. A cab (driver's cabin) <NUM> is located at a front part of the upper slewing body <NUM>.

The attachment <NUM> is attached to the upper slewing body <NUM> to be rotatable in an up-and-down direction. The attachment <NUM> includes a boom <NUM>, an arm <NUM>, and a bucket <NUM>. The boom <NUM> is attached to the upper slewing body <NUM> to be rotatable in an up-and-down direction (capable of rising and contracting). The arm <NUM> is attached to the boom <NUM> to be rotatable in an up-and-down direction. The bucket <NUM> is attached to the arm <NUM> so as to be rotatable in a front-and-rear direction. The bucket <NUM> is a portion that performs work including excavation, leveling, and scooping of soil and sand (transport object). However, the transport object is not limited to soil and sand, and may be a stone or a waste (industrial waste or the like).

The cylinders <NUM> can hydraulically move the attachment <NUM> rotationally. The cylinders <NUM> are hydraulic telescopic cylinders. The cylinders <NUM> include a boom cylinder <NUM>, an arm cylinder <NUM>, and a bucket cylinder <NUM>.

The boom cylinder <NUM> rotationally moves the boom <NUM> with respect to the upper slewing body <NUM>. The boom cylinder <NUM> has a base end part rotatably attached to the upper slewing body <NUM>. The boom cylinder <NUM> has a leading end part rotatably attached to the boom <NUM>.

The arm cylinder <NUM> rotationally moves the arm <NUM> with respect to the boom <NUM>. The arm cylinder <NUM> has a base end part rotatably attached to the boom <NUM>. The arm cylinder <NUM> has a leading end part rotatably attached to the arm <NUM>.

The bucket cylinder <NUM> rotationally moves the bucket <NUM> with respect to the arm <NUM>. The bucket cylinder <NUM> has a base end part rotatably attached to the arm <NUM>. The bucket cylinder <NUM> has a leading end part rotatably attached to a link member <NUM> rotatably attached to the bucket <NUM>.

The work machine <NUM> further includes an angle sensor <NUM>, and inclination angle sensors <NUM>.

The angle sensor <NUM> detects a slewing angle of the upper slewing body <NUM> with respect to the lower travelling body <NUM>. The angle sensor <NUM> is, for example, an encoder, a resolver, or a gyro sensor. In the present embodiment, the slewing angle of the upper slewing body <NUM> when a front side of the upper slewing body <NUM> coincides with a front side of the lower travelling body <NUM> is <NUM>°.

The inclination angle sensors <NUM> detect an orientation of the attachment <NUM>. The inclination angle sensors <NUM> includes a boom inclination angle sensor <NUM>, an arm inclination angle sensor <NUM>, and a bucket inclination angle sensor <NUM>.

The boom inclination angle sensor <NUM> is attached to the boom <NUM> and detects an attitude of the boom <NUM>. The boom inclination angle sensor <NUM> may be a sensor that acquires an inclination angle of the boom <NUM> with respect to the horizontal line, and may be, for example, an inclination (acceleration) sensor or the like. Note that the boom inclination angle sensor <NUM> may be a rotation angle sensor that detects a rotation angle of a boom foot pin (a base end of the boom) or a stroke sensor that detects a stroke amount of the boom cylinder <NUM>.

The arm inclination angle sensor <NUM> is attached to the arm <NUM> to detect an orientation of the arm <NUM>. The arm inclination angle sensor <NUM> may be a sensor that acquires an inclination angle of the arm <NUM> with respect to the horizontal line, and may be, for example, an inclination (acceleration) sensor or the like. Note that the arm inclination angle sensor <NUM> may be a rotation angle sensor that detects a rotation angle of an arm connection pin (a base end of the arm) or a stroke sensor that detects a stroke amount of the arm cylinder <NUM>.

The bucket inclination angle sensor <NUM> is attached to the link member <NUM> to detect an orientation of the bucket <NUM>. The bucket inclination angle sensor <NUM> may be a sensor that acquires an inclination angle of the bucket <NUM> with respect to the horizontal line, and may be, for example, an inclination (acceleration) sensor or the like. Note that the bucket inclination angle sensor <NUM> may be a rotation angle sensor that detects a rotation angle of a bucket connection pin (base end of the bucket) or a stroke sensor that detects a stroke amount of the bucket cylinder <NUM>.

As illustrated in <FIG>, which is a side view of the transport vehicle <NUM>, the transport vehicle <NUM> is a vehicle having a loading bed <NUM>, which is the loading target. The transport vehicle <NUM> is a vehicle for transporting soil and sand (load) loaded by the work machine <NUM>, and may be a dump truck or a truck.

The transport vehicle <NUM> includes a main body <NUM> and a loading bed <NUM>. The main body <NUM> can travel and supports the loading bed <NUM>. The main body <NUM> includes a driver's cabin <NUM>. The loading bed <NUM> is disposed on the rear side of the transport vehicle <NUM> with respect to the driver's cabin <NUM>.

Hereinafter, as for the directions related to the transport vehicle <NUM>, the side from the driver's cabin <NUM> toward the loading bed <NUM> is referred to as a "transport vehicle rear side", and a side from the loading bed <NUM> toward the driver's cabin <NUM> is referred to as a "transport vehicle front side".

The loading bed <NUM> has no lid, and has, for example, a box shape. The loading bed <NUM> includes a floor surface 56a, a drop tailgate surface 56b, side drop panel surfaces 56c on the right and left sides, and a cab protector surface 56d. The floor surface 56a is a bottom surface (lower surface) of the loading bed <NUM>. The drop tailgate surface 56b is a surface of the loading bed <NUM> on the transport vehicle rear side, and protrudes upward from a part of the floor surface 56a on the transport vehicle rear side. The side drop panel surfaces 56c are right and left surfaces of the loading bed <NUM>, and protrude upward from right and left end parts of the floor surface 56a. The cab protector surface 56d is a surface of the loading bed <NUM> on the front side of the transport vehicle, and protrudes upward from a part of the floor surface 56a on the transport vehicle front side. The cab protector surface 56d protrudes higher than the side drop panel surfaces 56c and protrudes higher than the drop tailgate surface 56b.

The loading bed <NUM> stores soil and sand (load). The loading bed <NUM> may be movable with respect to the main body <NUM> or may be fixed to the main body <NUM>. Note that the loading target on which the work machine <NUM> performs a loading work (soil discharging work) need not be the loading bed <NUM> of the transport vehicle <NUM>, and may be, for example, a container directly placed on the ground or the like.

As shown in <FIG>, a mobile terminal <NUM> is a terminal operated by a worker at a work site, and is, for example, a tablet terminal. The mobile terminal <NUM> is mutually communicable with the work machine <NUM>. Note that the mobile terminal <NUM> may be a smartphone or the like.

As shown in <FIG>, which is circuit diagrams of the work machine <NUM> and the mobile terminal <NUM>, the work machine <NUM> includes a controller <NUM>, a work machine side communication device <NUM>, and a storage <NUM>.

The controller <NUM> automatically controls the work machine <NUM>. The controller <NUM> causes the work machine <NUM> to automatically perform a series of operations from excavation of soil and sand to soil discharging. In other words, the work machine <NUM> is automatically operated. Specifically, the controller <NUM> automatically operates the slewing device <NUM> and the attachment <NUM> based on detection values by the angle sensor <NUM> and the inclination angle sensors <NUM>.

The work machine side communication device <NUM> is communicable with a mobile terminal side communication device <NUM> to be described later of the mobile terminal <NUM>. The storage <NUM> can store a target loading point to be described later.

The mobile terminal <NUM> includes a mobile terminal side controller <NUM>, the mobile terminal side communication device <NUM>, a display <NUM>, and a touch panel <NUM>.

The mobile terminal side communication device <NUM> can communicate with the work machine side communication device <NUM> of the work machine <NUM>. The mobile terminal side controller <NUM> receives information on a position of the leading end of the arm <NUM> (a base end of the bucket <NUM>) from the work machine <NUM> via the mobile terminal side communication device <NUM>.

Here, as illustrated in <FIG>, which is a top view of the work machine <NUM> and the transport vehicle <NUM>, a series of operations from excavation of soil and sand to soil discharging is performed in a state where the transport vehicle <NUM> is disposed such that the longitudinal direction of the transport vehicle <NUM> is along the slewing direction of the upper slewing body <NUM> of the work machine <NUM> and the transport vehicle <NUM> is stopped. That is, after the bucket <NUM> scoops soil and sand from a soil-and-sand storage place <NUM>, the controller <NUM> causes the upper slewing body <NUM> to slew so as to position the bucket <NUM> above the loading bed <NUM> of the transport vehicle <NUM>. Then, after soil is discharged into the loading bed <NUM>, the controller <NUM> causes the upper slewing body <NUM> to slew in the direction opposite to the above direction so as to position the bucket <NUM> above the soil-and-sand storage place <NUM>. The controller <NUM> causes these operations to be automatically repeated. The soil-and-sand storage place <NUM> is a soil-and-sand pit or a soil-and-sand mound.

The controller <NUM> of the work machine <NUM> sets a target loading point P above the loading bed <NUM>. The target loading point P is a target position at which the work machine <NUM> performs loading work (soil discharging work) on the transport vehicle <NUM>. The loading work is work of discharging soil and sand held by the bucket <NUM> to the loading bed <NUM>. The target loading point P is set by socalled teaching.

The teaching is performed as follows. First, the leading end of the arm <NUM> (the base end of the bucket <NUM>) is disposed above the loading bed <NUM> by a manual operation by an operator. When the operator carrying the mobile terminal <NUM> checks the position of the leading end of the arm <NUM> at this time and determines that there is no problem, the operator operates the touch panel <NUM> to establish the position. Information on the position is transmitted to the controller <NUM> of the work machine <NUM>, and the position of the leading end of the arm <NUM> at this time is set as the target loading point P and stored in the storage <NUM>.

A plurality of target loading points P may be set in the longitudinal direction of the loading bed <NUM> by teaching. The target loading point P is set at the central part of the width of the loading bed <NUM> in a direction orthogonal to each of the longitudinal direction and the vertical direction of the loading bed <NUM> (in other words, a transverse direction).

The controller <NUM> controls the loading work based on the set target loading point P. At this time, after the controller <NUM> rotates the bucket <NUM> such that the opening surface of the bucket <NUM> becomes vertical at the target loading point P, the controller <NUM> drives the boom <NUM>, the arm <NUM>, and the bucket <NUM> such that the opening surface of the bucket <NUM> faces downward while maintaining the position, with respect to the machine body <NUM>, of the leading end of the bucket <NUM> in the front-and-rear direction.

Specifically, as illustrated in <FIG>, which are side views of the arm <NUM> and the bucket <NUM>, the boom <NUM>, the arm <NUM>, and the bucket <NUM> are driven. First, as illustrated in <FIG>, when the leading end of the arm <NUM> is disposed at the target loading point P in a state where the bucket <NUM> holds soil and sand, the controller <NUM> stops the boom <NUM>, the arm <NUM>, and the bucket <NUM> in that state. At this time, the opening surface of the bucket <NUM> is horizontal.

Next, as illustrated in <FIG>, the controller <NUM> rotates the bucket <NUM> such that the opening surface of the bucket <NUM> becomes vertical. As a result, a part of the soil and sand held by the bucket <NUM> falls onto the loading bed <NUM>.

Next, as illustrated in <FIG>, the controller <NUM> drives the boom <NUM>, the arm <NUM>, and the bucket <NUM> such that the opening surface of the bucket <NUM> faces downward while maintaining a position T, with respect to the machine body <NUM>, of the leading end of the bucket <NUM> in the front-and-rear direction. Specifically, the boom <NUM> rotates and, at the same time, the arm <NUM> moves toward the upper slewing body <NUM> (an arm pulling operation is performed), so that the opening surface of the bucket <NUM> faces downward. With the rotation of the boom <NUM>, soil and sand in the bucket <NUM> fall onto the loading bed <NUM>.

As a result, as illustrated in <FIG>, the opening surface of the bucket <NUM> is directed downward, and almost all of the soil and sand held by the bucket <NUM> falls onto the loading bed <NUM>.

In the present embodiment, by directing the opening surface of the bucket <NUM> downward while maintaining the position T of the leading end of the bucket <NUM> with respect to the machine body <NUM>, the position at which the soil and sand are discharged can be kept substantially the same from the initial stage to the late stage of the rotation of the bucket <NUM>. As a result, soil and sand can be loaded onto the fixed point of the loading bed <NUM>.

In addition, by performing the operation of discharging soil and sand at the target loading point P set at the central part of the loading bed <NUM> in the transverse direction of the loading bed <NUM>, it is possible to suppress soil and sand from spilling from the loading bed <NUM>.

On the other hand, it can be considered to drive the boom <NUM>, the arm <NUM>, and the bucket <NUM> so as to maintain the position T of the leading end of the bucket <NUM> from the state where the opening surface of the bucket <NUM> is horizontal (the state illustrated in <FIG>) to the state where the opening surface of the bucket <NUM> faces downward (the state illustrated in <FIG>). However, in this case, because the leading end of the bucket <NUM> is closer to the upper slewing body <NUM> than the leading end of the arm <NUM> is, there is a possibility that, when the bucket <NUM> is rotated, the bucket <NUM> protrudes from the loading bed <NUM> in the region between the upper slewing body <NUM> and the loading bed <NUM> in plan view and soil and sand spill outside the loading bed <NUM>. To address this issue, it can be considered to position the leading end of the bucket <NUM> at the target loading point P so that the bucket <NUM> does not protrude from the loading bed <NUM>. However, in this case, there is a possibility that the leading end of the arm <NUM> is too distant from the upper slewing body <NUM> that the opening surface of the bucket <NUM> cannot be maintained to be horizontal due to the structure of the attachment <NUM>.

In the present embodiment, the following operation makes it possible to maintain the opening surface of the bucket <NUM> to be horizontal and to prevent the bucket <NUM> from protruding from the loading bed <NUM>. The leading end of the arm <NUM> is positioned at the target loading point P in the state where the opening surface of the bucket <NUM> is horizontal, and after the opening surface of the bucket <NUM> is made vertical, the bucket <NUM> is rotated while maintaining the position T of the leading end of the bucket <NUM> with respect to the machine body <NUM>.

As described above, in the work machine <NUM> according to the present embodiment, after the bucket <NUM> is rotated such that the opening surface of the bucket <NUM> becomes vertical at the target loading point P, the boom <NUM>, the arm <NUM>, and the bucket <NUM> are driven such that the opening surface of the bucket <NUM> faces downward while the position T, with respect to the machine body <NUM>, of the leading end of the bucket <NUM> in the front-and-rear direction is maintained. By directing the opening surface of the bucket <NUM> downward while maintaining the position of the leading end of the bucket <NUM> with respect to the machine body <NUM>, the position where the soil and sand are discharged can be kept substantially the same from the initial stage to the late stage of the rotation of the bucket <NUM>. As a result, soil and sand can be loaded onto the fixed point of the loading bed <NUM>.

In addition, the target loading point P is set at the central part of the loading bed <NUM> in the direction orthogonal to each of the longitudinal direction and the vertical direction of the loading bed <NUM>. By performing the operation of discharging soil and sand at such a target loading point P, it is possible to suppress soil and sand from spilling from the loading bed <NUM>.

Claim 1:
A work machine (<NUM>) comprising
a machine body (<NUM>);
a boom (<NUM>) attached to the machine body to be rotatable in an up-and-down direction;
an arm (<NUM>) attached to the boom to be rotatable in the up-and-down direction;
a bucket (<NUM>) attached to the arm to be rotatable in a front-and-rear direction; and
a controller (<NUM>) that causes the boom, the arm, and the bucket to automatically perform an operation of discharging a transport object held by the bucket by driving the boom, the arm, and the bucket, based on a target loading point (P) set above a loading target,
characterised in that
after the controller causes the bucket to rotate such that an opening surface of the bucket becomes vertical at the target loading point, the controller drives the boom, the arm, and the bucket such that the opening surface of the bucket faces downward while maintaining a position, with respect to the machine body, of a leading end of the bucket in the front-and-rear direction.