Construction machinery

Abstract

To provide a construction machine capable of suppressing reduction of efficiency of excavation work while suppressing excavation resistance during the excavation work from becoming larger.SOLUTION: A controller 50 of a work machine 10 comprises: an accommodation state determination section 53 determining an accommodation state of sediment accommodated in a bucket 6; and work device control sections 55, 56 outputting a resistance reducing command signal of a command signal to move a work device 3 so as that a bucket 6 shifts in resistance reducing directions D2, D3, D4 which are directions capable of reducing excavation resistance acting on the bucket 6, in accordance with a determination result by the accommodation state determination section 53.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to construction machines such as hydraulic excavators. [Background technology]

[0002] Patent Document 1 discloses a hydraulic excavator that measures the magnitude of the excavation reaction force that the bucket receives from the ground when the bucket advances underground to excavate the ground, changes the boom's rotation position according to the magnitude of the measured excavation reaction force, and, if the measured excavation force is large, causes the boom to deflect the bucket's traveling direction upward.

[0003] Patent Document 2 discloses a work machine control device for a power shovel. This work machine control device includes first detection means for detecting the angles of the bucket, arm, and boom of the power shovel, storage means for storing the movement trajectory of the bucket cutting edge that results in low digging resistance and an excavation state close to full capacity, first control means for controlling the bucket attitude based on the angle information of the bucket, arm, and boom detected by the detection means and the movement trajectory information of the bucket cutting edge read from the storage means, second detection means for detecting when the excavation resistance of the bucket exceeds a set value, and means for correcting the movement trajectory information of the bucket cutting edge read from the storage means in a direction that reduces the excavation resistance based on the output of the second detection means.

[0004] The construction machines of Patent Documents 1 and 2 detect the excavation reaction force (excavation resistance) that the bucket receives from the ground during excavation work, and when the detected excavation reaction force (excavation resistance) is large, correct the bucket's direction of travel upward so that the excavation resistance becomes smaller. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-81977 [Patent Document 2] Japanese Patent Publication No. 160325 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0006] In the construction machines of Patent Documents 1 and 2, as described above, the decision on whether to reduce the excavation resistance during excavation work is based solely on the excavation reaction force, so the efficiency of excavation work is not necessarily good. Specifically, for example, if the resistance (penetration resistance) when the bucket teeth penetrate the ground is high, the bucket's forward direction is corrected upward to reduce the excavation resistance. In this case, the amount of soil in the bucket when the bucket completes excavation may be significantly less than the bucket's capacity. On the other hand, even if the amount of soil in the bucket reaches the bucket's capacity, if the bucket's excavation resistance does not reach the set value due to, for example, the soil quality, the bucket's forward direction is maintained as is. In this case, the bucket continues to excavate deep underground even though there is a sufficient amount of soil in the bucket, resulting in unnecessary energy consumption. Therefore, the construction machines of Patent Documents 1 and 2 do not necessarily perform excavation work efficiently.

[0007] The present disclosure has been made in light of the above-mentioned problems, and aims to provide a construction machine that can suppress an increase in excavation resistance during excavation work while suppressing a decrease in the efficiency of excavation work. [Means for solving the problem]

[0008] The construction machine to be provided includes a work device including a machine body, a boom supported on the machine body so as to be able to be raised and lowered, an arm rotatably supported on the boom, and a bucket supported on the arm, the bucket having a bucket base end which is a base end rotatably attached to the arm and a bucket tip end which is a tip end on the opposite side thereof, and an inner surface defining an accommodation space which is a space capable of accommodating earth and sand; and a bucket in an attitude in which the bucket base end is positioned higher than the bucket tip end, and in which at least the portion including the bucket tip end is positioned forward when the bucket is in an excavation attitude in which the bucket base end is positioned higher than the bucket tip end and is capable of excavating earth and sand in the ground. The excavation equipment includes at least one operating device for operating the work equipment so that excavation work is performed by displacing the bucket relative to the ground while maintaining contact with the ground, and a controller, and the controller has a storage state determination unit that determines the storage state of the soil and sand stored in the bucket, and a work equipment control unit that outputs a resistance reduction command signal, which is a command signal for operating the work equipment so that the bucket is displaced in a resistance reduction direction that can reduce the excavation resistance acting on the bucket, in accordance with the result of the determination by the storage state determination unit.

[0009] In this construction machine, a determination as to whether to perform control to reduce excavation resistance during excavation work is made based on the state of soil contained in the bucket. This makes it possible to prevent an increase in excavation resistance during excavation work while also preventing a decrease in excavation efficiency. Specifically, as the amount of soil in the bucket increases, the excavation resistance during excavation work tends to increase. Therefore, the state of soil contained in the bucket is highly correlated with the magnitude of excavation resistance during excavation work. Therefore, the state of soil contained in the bucket can serve as an indicator for determining whether to perform control to reduce excavation resistance during excavation work. In this construction machine, a determination as to whether to perform control to reduce excavation resistance during excavation work is made based on the state of soil contained in the bucket. Therefore, when the amount of soil in the bucket increases and excavation resistance increases, or when excavation resistance tends to increase, the bucket can be displaced in a resistance-reducing direction to reduce excavation resistance. Furthermore, even if excavation resistance does not increase during excavation work, when the amount of soil in the bucket increases, the bucket is displaced in a resistance-reducing direction to further reduce excavation resistance, thereby preventing unnecessary energy consumption. This makes it possible to prevent the excavation resistance during the excavation work from increasing, while also preventing the efficiency of the excavation work from decreasing.

[0010] Preferably, the storage state determination unit is a contact state determination unit that determines the contact state between the specific upper region of the inner surface of the bucket, which is the upper portion of the bucket in the digging position, and the soil, and the work implement control unit outputs the resistance reduction command signal in response to the determination result by the contact state determination unit. In this configuration, the storage state of the soil stored in the bucket is determined by determining the contact state between the specific upper region of the bucket's inner surface and the soil. That is, in this configuration, a determination is made as to whether to perform control to reduce excavation resistance during excavation work based on the contact state between the specific upper region and the soil. This prevents an increase in excavation resistance during excavation work while suppressing a decrease in excavation work efficiency. Specifically, the specific upper region, which is the upper portion of the inner surface of the bucket in the digging position, does not contact the soil when the amount of soil in the bucket is small during excavation work, but contacts the soil when the amount of soil in the bucket increases during excavation work. Furthermore, as described above, an increase in the amount of soil in the bucket tends to increase the excavation resistance during excavation work. Therefore, the contact state between the specific upper region and the soil is highly correlated with the magnitude of excavation resistance during excavation work. Therefore, the contact state between the specific upper region and the soil can be an indicator for determining whether to perform control to reduce excavation resistance during excavation work. In this construction machine, the determination of whether to perform control to reduce excavation resistance during excavation work is made based on the contact state between the specific upper region and the soil. Therefore, when the amount of soil in the bucket increases and excavation resistance increases, or when excavation resistance is tending to increase, the bucket can be displaced in a resistance-reducing direction to reduce excavation resistance. Furthermore, even if excavation resistance does not increase during excavation work, when the amount of soil in the bucket increases, the bucket can be displaced in a resistance-reducing direction to further reduce excavation resistance, thereby suppressing wasted energy consumption. This prevents excavation resistance from increasing during excavation work while also suppressing a decrease in excavation work efficiency.

[0011] Preferably, the work implement control unit outputs the resistance reduction command signal when the contact condition determination unit determines that soil is in contact with the specific upper region of the bucket. With this configuration, when soil in the bucket is in contact with the specific upper region, the bucket is displaced in a resistance-reducing direction to reduce excavation resistance, thereby ensuring a sufficient amount of soil in the bucket during excavation work.

[0012] Preferably, the work implement control unit outputs the resistance reduction command signal when the contact condition determination unit determines that soil is not contacting the specific upper region of the bucket and the amount of soil stored in the storage space of the bucket is greater than a predetermined soil amount threshold. With this configuration, if the amount of soil in the bucket exceeds the soil amount threshold during excavation work even when the soil in the bucket is not contacting the specific upper region, the resistance reduction command signal is output. Therefore, the bucket can be displaced in a resistance-reducing direction to reduce excavation resistance before the soil in the bucket contacts the specific upper region and increases excavation resistance. This further reduces wasted energy consumption.

[0013] In the construction machine, the work implement control unit may output the resistance reduction command signal when the contact condition determination unit determines that soil is not in contact with the specific upper region of the bucket and when an excavation reaction force, which is a reaction force the bucket receives from the ground during the excavation operation, is greater than a predetermined reaction force threshold. In this configuration, the reaction force threshold is preferably set to a value that can prevent a significant decrease in bucket operation speed due to an increase in the excavation reaction force. A significant decrease in bucket operation speed reduces the efficiency of the excavation operation. In this configuration, even if soil in the bucket is not in contact with the specific upper region, if the excavation reaction force is greater than the reaction force threshold, the bucket is displaced in the resistance-reducing direction to reduce excavation resistance, thereby further preventing a decrease in excavation efficiency.

[0014] Preferably, the construction machine further includes a work implement attitude information acquirer that acquires work implement attitude information, which is information related to the attitude of the work implement, and a sediment information acquirer that acquires sediment information, which is information related to the attitude of the work implement, and a sediment information acquirer that acquires sediment information, which is information related to the sediment stored in the storage space of the bucket, the controller further includes a bucket attitude calculation unit that calculates a bucket attitude, which is the attitude of the bucket, using the work implement attitude information, and a deposition state calculation unit that calculates a sediment deposition state in the storage space of the bucket using the bucket attitude and the sediment information, and the contact state determination unit determines the contact state between the specific upper area and the sediment based on the deposition state. With this configuration, the contact state between the specific upper area and the sediment can be determined based on the actual deposition state of the sediment in the bucket.

[0015] The construction machine may further include a load detector disposed in the specific upper area and capable of detecting a sediment load, which is a load from the sediment stored in the storage space of the bucket, and the contact condition determination unit may determine the contact condition between the specific upper area and the sediment based on the sediment load detected by the load detector. In this configuration, the contact condition between the specific upper area and the sediment is determined based on the sediment load detected by the load detector, so that the processing load on the controller can be reduced compared to when the contact condition is determined based on image processing data, for example.

[0016] The controller preferably further includes a tilt calculation unit that calculates a tilt index value, which is an index value corresponding to the tilt of the specific upper region relative to a predetermined reference plane, and the work implement control unit preferably does not output the resistance reduction command signal when the tilt index value calculated by the tilt calculation unit is greater than a predetermined tilt threshold. The bucket posture during excavation work is highly correlated with the magnitude of excavation resistance during excavation work. Specifically, for example, when the tilt of the specific upper region relative to a horizontal plane (an example of a reference plane) is large, excavation resistance tends to be small, and when the tilt of the specific upper region relative to the horizontal plane is small, excavation resistance tends to be large. Therefore, when the tilt index value is greater than the tilt threshold, it is highly likely that control to reduce excavation resistance during excavation work is not necessary, and in this case, the resistance reduction command signal is not output. This reduces the processing load on the controller. [Effects of the Invention]

[0017] According to the present disclosure, a construction machine is provided that can suppress an increase in excavation resistance during excavation work while suppressing a decrease in the efficiency of the excavation work. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a side view showing a hydraulic excavator according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of a controller of the hydraulic excavator and its input / output signals. [Figure 3] 4 is a cross-sectional view showing a bucket of the hydraulic excavator, illustrating an example of a resistance reducing operation of the bucket. FIG. [Figure 4] 5 is a cross-sectional view showing the bucket of the hydraulic excavator, illustrating another example of the resistance reducing operation of the bucket. FIG. [Figure 5] FIG. 10 is a cross-sectional view showing the bucket of the hydraulic excavator, illustrating yet another example of the resistance reducing operation of the bucket. [Figure 6] FIG. 2 is a cross-sectional view showing a bucket of the hydraulic excavator. [Figure 7] 4 is a flowchart showing the calculation and control operation of the controller. [Figure 8] 10 is a flowchart showing another example of the arithmetic control operation of the controller. [Figure 9] FIG. 10 is a block diagram showing the functional configuration of a controller of a hydraulic excavator according to a modified example of the embodiment and its input / output signals. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a side view showing a hydraulic excavator 10 according to this embodiment. As shown in FIG. 1, the hydraulic excavator 10 includes a lower traveling body 1 capable of traveling on ground G, an upper rotating body 2 supported on the lower traveling body 1 so as to be rotatable about a rotation center axis Z facing in the vertical direction, and a working device 3 supported on the upper rotating body 2. The lower traveling body 1 and the upper rotating body 2 are examples of a machine body. Note that "front" and "rear" in the drawings are directions based on the orientation of the upper rotating body 2.

[0020] The lower traveling body 1 includes a pair of crawler traveling devices and a lower frame connecting the traveling devices. The upper rotating body 2 includes an upper frame rotatably supported on the lower frame, a cabin supported on the front part of the upper frame, and a counterweight supported on the rear part of the upper frame. In this embodiment, the working device 3 includes a boom 4, an arm 5, and a bucket 6.

[0021] The boom 4 is supported by the upper frame of the upper rotating body 2 so as to be able to rise and fall relative to the upper frame. Specifically, the boom 4 has a boom base end, which is a base end attached to the upper frame so as to be able to rotate upward and downward about a horizontal axis A1, and a boom tip end, which is a tip end on the opposite side.

[0022] The arm 5 is supported by the boom 4 so as to be rotatable relative to the boom 4. Specifically, the arm 5 has an arm base end which is a base end attached to the boom tip so as to be rotatable in both an arm retracting direction and an arm pushing direction about a horizontal axis A2, and an arm tip which is a tip end on the opposite side. The arm retracting direction is a rotation direction in which the arm tip of the arm 5 approaches the machine body, and the arm pushing direction is a rotation direction opposite to the arm retracting direction.

[0023] Bucket 6 is supported by arm 5 so as to be rotatable relative to arm 5. Specifically, bucket 6 has bucket base end 61, which is a base end attached to the tip of the arm so as to be rotatable in both a bucket pulling direction and a bucket pushing direction about horizontal axis A3, and bucket tip 62, which is the tip end on the opposite side. The bucket pulling direction is the rotation direction in which bucket tip 62 approaches the machine body when bucket 6 performs an excavation operation, as shown in FIG. 1, for example, and the bucket pushing direction is the rotation direction opposite to the bucket pulling direction.

[0024] The bucket 6 has a bucket body 6A including a bucket base end 61, and a plurality of teeth 6B (a plurality of claws). The bucket body 6A forms the container portion of the bucket 6 and has a storage space that is a space capable of storing earth and sand. The bucket body 6A has an inner surface that defines the storage space. The plurality of teeth 6B form the bucket tip portion 62 of the bucket 6 and are fixed to the end of the bucket body 6A so as to be aligned along the width direction of the bucket body 6A. The width direction of the bucket body 6A is a direction parallel to the horizontal axis A3, that is, the left-right direction. Each of the plurality of teeth 6B protrudes from the end of the bucket body 6A in a direction perpendicular to the width direction.

[0025] The bucket pulling direction and bucket pushing direction can each be defined using, for example, the angle of the bucket 6 relative to the arm 5. The angle formed by a line L1 passing through horizontal axis A2, which is the rotation center of the arm base end, and horizontal axis A3, which is the rotation center of the bucket base end, and a line L2 passing through horizontal axis A3 and the tip of the bucket 6 (tips of teeth 6B), is defined as the bucket angle θ. In this case, the bucket pulling direction is the rotation direction in which the bucket angle θ decreases, and the bucket pushing direction is the rotation direction in which the bucket angle θ increases.

[0026] The hydraulic excavator 10 further includes a plurality of hydraulic actuators for hydraulically moving the work implement 3. The plurality of hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, and a swing motor 11.

[0027] Each of the cylinders 7, 8, and 9 is composed of a hydraulic cylinder that extends and retracts when supplied with hydraulic oil. The boom cylinder 7 is attached to the upper rotating body 2 and the boom 4 so that the boom 4 rises and falls as the boom cylinder 7 extends and retracts, i.e., so that the boom 4 rotates in the boom-up direction and the boom-down direction, respectively. The arm cylinder 8 is attached to the boom 4 and the arm 5 so that the arm 5 rotates in the arm-pushing direction and the arm-pushing direction as the arm cylinder 8 extends and retracts. The bucket cylinder 9 is attached to the arm 5 and the bucket 6 so that the bucket 6 rotates in the bucket-pushing direction and the bucket-pushing direction as the bucket cylinder 9 extends and retracts.

[0028] The swing motor 11 is a hydraulic motor for hydraulically swinging the upper swing body 2 relative to the lower traveling body 1. The swing motor 11 has an output shaft, which is connected to the upper frame of the upper swing body 2 via a reduction gear (not shown). When supplied with hydraulic oil, the swing motor 11 operates so that the output shaft rotates in a direction corresponding to the direction of the supply of hydraulic oil, thereby enabling the upper swing body 2 to swing in both the left swing direction and the right swing direction.

[0029] As shown in FIG. 2, the hydraulic excavator 10 further includes a plurality of operating devices, a plurality of sensors, and a controller 50.

[0030] The multiple operating devices are devices that can operate the work device 3 so that the bucket 6 is in an excavation position and excavation work is performed to excavate soil and sand in the ground G by displacing the bucket 6 relative to the ground G while maintaining a state in which at least a portion including the bucket tip 62 is in contact with the ground G.

[0031] The multiple operating devices include a boom operating device 21, an arm operating device 22, and a bucket operating device 23. Each of these operating devices 21, 22, 23 is equipped with an operating lever, and is configured as an electric lever device that inputs a lever signal, which is an electric signal corresponding to an operation, to the controller 50 when an operator operates the operating lever to operate the work implement 3. Specifically, this is as follows.

[0032] The boom operation device 21 includes a boom operation lever to which the operator applies boom operation, which is an operation for operating the boom 4, and a boom operation signal generation unit that generates a boom operation signal, which is a lever signal corresponding to the boom operation applied to the boom operation lever, and inputs the signal to the controller 50.

[0033] The arm operating device 22 includes an arm operating lever to which an operator applies an arm operation, which is an operation for operating the arm 5, and an arm operating signal generating unit that generates an arm operating signal, which is a lever signal corresponding to the arm operation applied to the arm operating lever, and inputs the signal to the controller 50.

[0034] The bucket operating device 23 includes a bucket operating lever through which a bucket operation, which is an operation for operating the bucket 6, is given by an operator, and a bucket operation signal generating unit that generates a bucket operation signal, which is a lever signal corresponding to the bucket operation given to the bucket operating lever, and inputs the signal to the controller 50.

[0035] Each of the multiple sensors detects information necessary to enable the controller 50 to control the operation of the work implement 3, and inputs a detection signal, which is an electrical signal corresponding to the information, to the controller 50. The multiple sensors include a boom angle sensor 31, an arm angle sensor 32, a bucket angle sensor 33, multiple cylinder pressure sensors 35, an image acquisition sensor 80 (image acquirer), and a machine body tilt angle sensor 34.

[0036] The boom angle sensor 31, the arm angle sensor 32, and the bucket angle sensor 33 are examples of a work implement attitude information acquirer that acquires work implement attitude information, which is information about the attitude of the work implement 3. The image acquisition sensor 80 is an example of a sediment information acquirer that acquires sediment information, which is information about the sediment stored in the storage space of the bucket 6.

[0037] The boom angle sensor 31 detects the boom angle, which is the angle of the boom 4 relative to the upper rotating body 2, and inputs a boom attitude detection signal, which is a detection signal corresponding to the detected boom angle, to the controller 50. The boom angle sensor 31 is disposed at the boom base end of the boom 4, for example, as shown in FIG. 1.

[0038] The arm angle sensor 32 detects the arm angle, which is the angle of the arm 5 relative to the boom 4, and inputs an arm posture detection signal, which is a detection signal corresponding to the detected arm angle, to the controller 50. The arm angle sensor 32 is disposed at the arm base end of the arm 5, for example, as shown in FIG.

[0039] The bucket angle sensor 33 detects a bucket angle θ, which is the angle of the bucket 6 with respect to the arm 5, and inputs a bucket attitude detection signal, which is a detection signal corresponding to the detected bucket angle θ, to the controller 50. The bucket angle sensor 33 is disposed at the bucket base end 61 of the bucket 6, for example, as shown in FIG.

[0040] Each of the boom angle sensor 31, the arm angle sensor 32, and the bucket angle sensor 33 may be, for example, a resolver, a rotary encoder, a potentiometer, an IMU (Inertial Measurement Unit), or another sensor.

[0041] The vehicle body inclination angle sensor 34 is a sensor for detecting the inclination angle of the vehicle body. The vehicle body inclination angle sensor 34 is disposed, for example, on the upper rotating body 2, detects the inclination angle of the vehicle body relative to the horizontal plane, and inputs a detection signal corresponding to the detected inclination angle to the controller 50. The vehicle body inclination angle sensor 34 may be configured, for example, by an IMU.

[0042] The multiple cylinder pressure sensors 35 include at least one cylinder pressure sensor that detects the pressure of the boom cylinder 7, at least one cylinder pressure sensor that detects the pressure of the arm cylinder 8, and at least one cylinder pressure sensor that detects the pressure of the bucket cylinder 9. Specifically, in this embodiment, the multiple cylinder pressure sensors 35 include a cylinder pressure sensor that detects the pressure of the head side chamber of the boom cylinder 7, a cylinder pressure sensor that detects the pressure of the rod side chamber of the boom cylinder 7, a cylinder pressure sensor that detects the pressure of the head side chamber of the arm cylinder 8, a cylinder pressure sensor that detects the pressure of the rod side chamber of the arm cylinder 8, a cylinder pressure sensor that detects the pressure of the head side chamber of the bucket cylinder 9, and a cylinder pressure sensor that detects the pressure of the rod side chamber of the bucket cylinder 9. Each of the multiple cylinder pressure sensors 35 inputs a pressure detection signal that is a detection signal corresponding to the detected pressure to the controller 50.

[0043] The image acquisition sensor 80 acquires sediment information, which is information related to the soil and sand stored in the storage space of the bucket 6, and inputs the sediment information to the controller 50. The image acquisition sensor 80 is capable of measuring shape data of the inner surface of the bucket 6 and the soil and sand stored in the bucket 6 (for example, initial image information and image information during excavation, which will be described later). The image acquisition sensor 80 may be configured, for example, by a distance measurement sensor that measures measurement data indicating the distance to an object. The distance measurement sensor may be, for example, a LiDAR (Light Detection and Ranging). LiDAR can measure the distance to an object by irradiating the object with light such as near-infrared light, visible light, or ultraviolet light and capturing the reflected light with an optical sensor. The distance measurement sensor may be a sensor capable of measuring depth in units of multiple pixels, such as a TOF (Time of Flight) sensor or a stereo camera.

[0044] The image acquisition sensor 80 is disposed in a position where it can acquire sediment information about the sediment stored in the storage space of the bucket 6 during excavation work. During excavation work, the bucket 6 moves, for example, as shown in FIG. 1 , in the following order: a pre-start position P1, which is a position before the start of excavation work; an in-work position P2, which is a position during excavation work; and an end position P3, which is a position at the end of the excavation work. In this embodiment, the image acquisition sensor 80 is disposed in the cabin of the upper rotating body 2 as shown in FIG. 1 , and has a field of view (for example, a field of view within the range indicated by the two-dot chain line in FIG. 1 ) that can capture images of the inner surface of the bucket 6 and the sediment stored in the bucket 6 when the bucket 6 is in a range that includes the in-work position P2 and the end position P3. The image acquisition sensor 80 may be disposed on the underside of the boom 4 or on the inner surface of the arm 5. The underside of the boom 4 is the surface of the boom 4 that faces the ground G in FIG. 1 , and the inner surface of the arm 5 is the surface of the arm 5 that faces rearward in FIG. 1 .

[0045] The controller 50 controls the operation of the working device 3 based on operation signals input from a plurality of operating devices and detection signals input from a plurality of sensors. The controller 50 includes a computer including a CPU and a memory.

[0046] The controller 50 includes a bucket attitude calculation unit 51, an earth and sand volume calculation unit 52, a contact state determination unit 53, an excavation reaction force calculation unit 54, a bucket travel direction determination unit 55, and a bucket travel direction control unit 56.

[0047] The bucket attitude calculation unit 51 uses the work implement attitude information to calculate the bucket attitude, which is the attitude of the bucket 6. Specifically, the bucket attitude calculation unit 51 calculates the bucket attitude based on the boom attitude detection signal input from the boom angle sensor 31, the arm attitude detection signal input from the arm angle sensor 32, and the bucket attitude detection signal input from the bucket angle sensor 33.

[0048] The sediment amount calculation unit 52 uses the bucket attitude and the sediment information to calculate the sediment accumulation state in the accommodation space of the bucket 6. The sediment amount calculation unit 52 is an example of an accumulation state calculation unit.

[0049] The contact state determination unit 53 determines the contact state between the specific upper region 64 on the inner surface of the bucket 6 and the sediment. In this embodiment, the contact state determination unit 53 determines the contact state based on the accumulation state calculated by the sediment amount calculation unit 52. The contact state determination unit 53 stores data representing the result of the contact state determination in a predetermined area (flag) of memory. The contact state determination unit 53 is an example of a storage state determination unit.

[0050] The specific upper region 64 is a portion of the inner surface of the bucket 6 that is located at the top in the excavation posture. As shown in Fig. 1, the excavation posture is a posture of the bucket 6 in which the bucket base end 61 is positioned higher than the bucket tip end 62, and is a posture in which the opening of the bucket 6 faces rearward, as when the bucket 6 is positioned at the working position P2 and the final position P3, allowing the bucket 6 to excavate earth and sand in the ground G.

[0051] As shown in FIG. 1 , the bucket 6 has an upper plate 65 located at an upper position in the digging position, a lower plate 66 located at a lower position in the digging position, a bottom plate 68 curved to connect the upper plate 65 and the lower plate 66, a right plate (not shown) connected to the right edge of the upper plate 65, the right edge of the bottom plate 68, and the right edge of the lower plate 66, and a left plate 67 connected to the left edge of the upper plate 65, the left edge of the bottom plate 68, and the left edge of the lower plate 66. The inner surface of the bucket 6 includes the inner surfaces of the upper plate 65, the inner surface of the bottom plate 68, and the inner surface of the lower plate 66, but does not include the inner surfaces of the right plate and the left plate. The specific upper region 64 is a portion of the inner surface of the bucket 6 located above a boundary portion PS of the bucket 6, as shown in the upper view of FIG. 3 , for example. In this embodiment, the boundary portion PS is the foremost portion of the inner surface of the bucket 6 in the digging position. Therefore, the boundary portion PS is a portion that changes depending on the posture of the bucket 6. The contact state determination unit 53 can calculate the position of the boundary portion PS based on the bucket attitude calculated by the bucket attitude calculation unit 51. The boundary portion PS may be a predetermined specific portion (fixed portion) rather than a portion that changes depending on the attitude of the bucket 6. If the boundary portion PS is a fixed portion, the boundary portion PS may be, for example, the portion (bottom portion) that is located lowest when the opening of the bucket 6 is placed parallel to a horizontal plane. Furthermore, the boundary portion PS may be set on the inner surface of the bucket 6 on a horizontal line parallel to the width direction of the bucket 6 from the left end to the right end of the inner surface, or may be set for each of multiple regions in the width direction so that the height of each region is different. The boundary portion PS does not necessarily have to be set from the left end to the right end of the inner surface, but may be set in only a partial region in the width direction.

[0052] The excavation reaction force calculation unit 54 calculates the excavation reaction force based on the inclination angle of the machine body (attitude of the upper rotating body 2) detected by the machine body inclination angle sensor 34, the attitude of the work implement 3 (attitude of the boom 4, attitude of the arm 5, and attitude of the bucket 6) detected by the boom angle sensor 31, the arm angle sensor 32, and the bucket angle sensor 33, the pressure of the boom cylinder 7, the pressure of the arm cylinder 8, and the pressure of the bucket cylinder 9 detected by multiple cylinder pressure sensors 35, and dimensional information related to the dimensions between the links of the work implement 3. The dimensions between the links are stored in advance in the memory unit of the controller 50 and include, for example, the distance between the horizontal axis A1 and the horizontal axis A2 and the distance between the horizontal axis A2 and the horizontal axis A3. The machine body inclination angle sensor 34, the boom angle sensor 31, the arm angle sensor 32, the bucket angle sensor 33, and the multiple cylinder pressure sensors 35 are examples of an excavation reaction force measurement device.

[0053] The bucket traveling direction determination unit 55 and the bucket traveling direction control unit 56 are one example of a work implement control unit. The work implement control unit outputs a resistance reduction command signal, which is a command signal for operating the work implement 3 so that the bucket 6 is displaced in a resistance reduction direction, which is a direction that can reduce the excavation resistance acting on the bucket 6, in accordance with the result of the determination by the contact condition determination unit 53. Specifically, this is as follows.

[0054] The bucket traveling direction determination unit 55 determines whether or not it is necessary to reduce the excavation resistance acting on the bucket 6 by controlling the traveling direction of the bucket 6. In the present embodiment, the bucket traveling direction determination unit 55 determines whether or not it is necessary to reduce the excavation resistance acting on the bucket 6, based on the result of the determination (determination flag) by the contact state determination unit 53, the bucket attitude calculated by the bucket attitude calculation unit 51, and the excavation reaction force calculated by the excavation reaction force calculation unit 54.

[0055] Bucket traveling direction control unit 56 outputs a command signal for operating the working implement 3 based on the lever signals input from each of the multiple operation devices and the result of the determination by bucket traveling direction determination unit 55. In other words, bucket traveling direction control unit 56 outputs a command signal for operating the working implement 3 based on the boom operation signal input from boom operation device 21, the arm operation signal input from arm operation device 22, the bucket operation signal input from bucket operation device 23, and the result of the determination by bucket traveling direction determination unit 55.

[0056] If the bucket travel direction determination unit 55 determines that there is no need to reduce the excavation resistance acting on the bucket 6, the bucket travel direction control unit 56 outputs command signals corresponding to the boom operation signal, the arm operation signal, and the bucket operation signal to the work implement drive unit. On the other hand, if the bucket travel direction determination unit 55 determines that there is a need to reduce the excavation resistance acting on the bucket 6, the bucket travel direction control unit 56 outputs a resistance reduction command signal to the work implement drive unit, which is a command signal for operating the work implement 3 so that the bucket 6 is displaced in a resistance reduction direction, which is a direction that can reduce the excavation resistance acting on the bucket 6. The resistance reduction command signal includes a modified command signal obtained by modifying at least one of the command signals corresponding to the boom operation signal, the arm operation signal, and the bucket operation signal.

[0057] The work implement drive section includes a plurality of proportional valves and a control valve unit 77. The plurality of proportional valves include a pair of boom proportional valves 71, 72, a pair of arm proportional valves 73, 74, and a pair of bucket proportional valves 75, 76. Each of the proportional valves 71 to 76 is configured, for example, by an electromagnetic proportional valve. The control valve unit 77 includes a boom control valve, an arm control valve, and a bucket control valve.

[0058] The control valve unit 77 is interposed between a hydraulic pump (not shown) and a plurality of hydraulic actuators, and adjusts the flow rate and supply direction of hydraulic oil supplied to each of the plurality of hydraulic actuators.

[0059] Specifically, the control valve unit 77 includes a boom control valve that adjusts the flow rate and supply direction of hydraulic oil supplied to the boom cylinder 7, an arm control valve that adjusts the flow rate and supply direction of hydraulic oil supplied to the arm cylinder 8, and a bucket control valve that adjusts the flow rate and supply direction of hydraulic oil supplied to the bucket cylinder 9.

[0060] When bucket traveling direction determination unit 55 determines that there is no need to reduce the excavation resistance acting on bucket 6, bucket traveling direction control unit 56 outputs command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal to multiple proportional valves 71 to 76 of the working implement drive unit. Specifically, this is as follows.

[0061] When the boom operation signal is input from the boom operation device 21, the bucket travel direction control unit 56 inputs a boom command signal, which is a command signal corresponding to the boom operation signal, to one of the pair of boom proportional valves 71, 72 that corresponds to the operation direction of the boom operation. As a result, the pilot pressure reduced in the boom proportional valve in response to the boom command signal is input to one of the pair of pilot ports of the boom control valve. As a result, hydraulic oil from the hydraulic pump is supplied to either the head-side chamber or the rod-side chamber of the boom cylinder 7 that corresponds to the boom command signal at a flow rate corresponding to the boom command signal, and the boom 4 rotates in the direction corresponding to the boom command signal at a speed corresponding to the boom command signal.

[0062] When the arm operation signal is input from the arm operating device 22, the bucket travel direction control unit 56 inputs an arm command signal, which is a command signal corresponding to the arm operation signal, to one of the pair of arm proportional valves 73, 74 that corresponds to the operation direction of the arm operation. As a result, the pilot pressure reduced in the arm proportional valve in accordance with the arm command signal is input to one of the pair of pilot ports of the arm control valve. As a result, hydraulic oil from the hydraulic pump is supplied to either the head side chamber or the rod side chamber of the arm cylinder 8 that corresponds to the arm command signal at a flow rate in accordance with the arm command signal, and the arm 5 rotates in the direction in accordance with the arm command signal at a speed in accordance with the arm command signal.

[0063] When the bucket operation signal is input from the bucket operation device 23, the bucket travel direction control unit 56 inputs a bucket command signal, which is a command signal corresponding to the bucket operation signal, to one of the pair of bucket proportional valves 75, 76 that corresponds to the operation direction of the bucket operation. As a result, the pilot pressure reduced in the bucket proportional valve in accordance with the bucket command signal is input to one of the pair of pilot ports of the bucket control valve. As a result, hydraulic oil from the hydraulic pump is supplied to either the head side chamber or the rod side chamber of the bucket cylinder 9 that corresponds to the bucket command signal at a flow rate corresponding to the bucket command signal, and the bucket 6 rotates in the direction corresponding to the bucket command signal at a speed corresponding to the bucket command signal.

[0064] On the other hand, when the bucket travel direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced, the bucket travel direction control unit 56 outputs a resistance reduction command signal to the work implement drive unit, which is a command signal for operating the work implement 3 so that the bucket 6 is displaced in a resistance reduction direction, which is a direction in which the excavation resistance acting on the bucket 6 can be reduced.

[0065] Fig. 3 shows one example of the resistance reducing operation of the bucket 6, Fig. 4 shows another example of the resistance reducing operation of the bucket 6, and Fig. 5 shows yet another example of the resistance reducing operation of the bucket 6. The resistance reducing operations shown in Figs. 3, 4 and 5 are common in that the traveling direction of the bucket 6 is corrected upward. Note that the cross section of the bucket 6 in Figs. 3 to 5 is a cross section parallel to the vertical direction.

[0066] First, the resistance reduction operation shown in Fig. 3 will be described. The upper diagram in Fig. 3 shows a state in which the bucket 6 is moving in a first direction D1, which is, for example, a direction close to horizontal, during excavation work. In this state, if the bucket travel direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced, the bucket travel direction control unit 56 outputs a resistance reduction command signal to the work implement drive unit, which is a command signal for operating the work implement 3 so that the travel direction of the bucket 6 changes from the first direction D1 to a second direction D2. The second direction D2 is a diagonally upward direction in which the proportion of the upward component is increased compared to the first direction D1.

[0067] When the traveling direction of the bucket 6 is changed as shown in FIG. 3 , in this embodiment, the bucket traveling direction control unit 56 outputs an arm command signal corresponding to the arm operation signal as is (outputs it without correction), and outputs resistance reduction command signals obtained by correcting the boom command signal corresponding to the boom operation signal and the bucket command signal corresponding to the bucket operation signal. That is, in this embodiment, when the bucket traveling direction determination unit 55 determines that it is necessary to reduce the excavation resistance acting on the bucket 6 in the state shown in the upper diagram of FIG. 3 , the bucket traveling direction control unit 56 outputs command signals to the multiple proportional valves 71-76 so that the arm 5 operates in accordance with the arm operation by the operator, the boom 4 operates in the boom-raising direction further than the operation in accordance with the boom operation rather than a rotation operation in accordance with the boom operation by the operator, and the bucket 6 operates in the bucket-pulling direction further than the operation in accordance with the bucket operation rather than a movement in accordance with the bucket operation by the operator. As a result, the traveling direction of the bucket 6 changes from the first direction D1 to the second direction D2, and the excavation resistance acting on the bucket 6 can be reduced.

[0068] Next, the resistance reduction operation shown in Fig. 4 will be described. The left diagram in Fig. 4 shows a state in which the bucket 6 is moving in a first direction D1, which is, for example, a direction close to horizontal, during excavation work. In this state, if the bucket travel direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced, the bucket travel direction control unit 56 outputs a resistance reduction command signal to the work implement drive unit, which is a command signal for operating the work implement 3 so that the travel direction of the bucket 6 changes from the first direction D1 to a third direction D3. The third direction D3 is a direction in which the proportion of the upward component is increased compared to the first direction D1, and is the upward direction in the center diagram in Fig. 4.

[0069] When the traveling direction of the bucket 6 is changed from the left diagram to the center diagram in FIG. 4 , in this embodiment, the bucket traveling direction control unit 56 outputs an arm command signal corresponding to the arm operation signal and a bucket command signal corresponding to the bucket operation signal as they are (outputs them without modification), and outputs a resistance reduction command signal obtained by modifying the boom command signal corresponding to the boom operation signal. That is, in this embodiment, when the bucket traveling direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced in the state shown in the left diagram in FIG. 4 , the bucket traveling direction control unit 56 outputs command signals to the multiple proportional valves 71-76 so that the arm 5 and the bucket 6 perform operations corresponding to the arm operation and bucket operation by the operator, respectively, and so that the boom 4 does not rotate in response to the boom operation by the operator, but moves further in the boom-raising direction than in response to the boom operation. As a result, the traveling direction of the bucket 6 changes from the first direction D1 to the third direction D3, thereby reducing the excavation resistance acting on the bucket 6.

[0070] When a predetermined condition is satisfied, the bucket traveling direction control unit 56 outputs a boom command signal corresponding to the boom operation signal, an arm command signal corresponding to the arm operation signal, and a bucket command signal corresponding to the bucket operation signal, respectively. As a result, the boom 4, the arm 5, and the bucket 6 perform operations in accordance with the boom operation, arm operation, and bucket operation by the operator, respectively, and the traveling direction of the bucket 6 changes from the third direction D3 to the first direction D1 or a direction close to the first direction D1, as shown in the right diagram of FIG. 4 . The predetermined condition may be, for example, a predetermined time that has elapsed since the traveling direction of the bucket 6 changed from the first direction D1 to the third direction D3. Another predetermined condition may be, for example, a predetermined distance that has been traveled in the third direction D3 since the traveling direction of the bucket 6 changed from the first direction D1 to the third direction D3. Furthermore, the predetermined condition may be, for example, that the rotation angle of the boom 4 reaches a predetermined angle from the point at which the traveling direction of the bucket 6 changes from the first direction D1 to the third direction D3.

[0071] Next, the resistance reduction operation shown in FIG. 5 will be described. The upper diagram in FIG. 5 shows a state in which the bucket 6 is moving in a first direction D1, which is, for example, a direction close to horizontal, during excavation work. In this state, if the bucket travel direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced, the bucket travel direction control unit 56 outputs a resistance reduction command signal to the work implement drive unit, which is a signal for operating the work implement 3 so as to complete the excavation work. Specifically, the bucket travel direction control unit 56 outputs a resistance reduction command signal to the work implement drive unit, which is a command signal for operating the work implement 3 so as to change the travel direction of the bucket 6 from the first direction D1 to a fourth direction D4. The fourth direction D4 is a direction in which the proportion of the upward component is increased compared to the first direction D1, and in the lower diagram in FIG. 5, it is an upward or diagonally upward direction away from the ground G.

[0072] When the traveling direction of the bucket 6 is changed from the upper diagram to the lower diagram in FIG. 5 , in this embodiment, the bucket traveling direction control unit 56 outputs resistance reduction command signals obtained by correcting each of the boom command signal corresponding to the boom operation signal, the arm command signal corresponding to the arm operation signal, and the bucket command signal corresponding to the bucket operation signal. That is, in this embodiment, when the bucket traveling direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced in the state shown in the upper diagram in FIG. 5 , the bucket traveling direction control unit 56 outputs command signals to the plurality of proportional valves 71-76 so that the boom 4, the arm 5, and the bucket 6 do not rotate in accordance with the boom operation, arm operation, and bucket operation by the operator, but rather the bucket 6 moves in a direction away from the ground G. As a result, the traveling direction of the bucket 6 changes from the first direction D1 to the fourth direction D4, and the excavation resistance acting on the bucket 6 can be reduced.

[0073] In this embodiment, the bucket attitude calculation unit 51 includes an inclination calculation unit. The inclination calculation unit calculates an inclination index value, which is an index value corresponding to the inclination of the specific upper region 64 with respect to a predetermined reference plane H, as shown in FIG. 6 . In this embodiment, the reference plane H is a horizontal plane, and the inclination index value is the angle θ1 of the upper plate 65 of the bucket 6 with respect to the reference plane H. In this embodiment, a portion of the upper plate 65 is flat (linear in the cross section of FIG. 6 ), so the angle between the flat portion of the upper plate 65 and the reference plane H can be set to θ1. However, the upper plate 65 may be curved as a whole. When the upper plate 65 has a curved shape, the inclination index value may be, for example, the angle between a tangent to a predetermined portion of the upper plate 65 and the reference plane H.

[0074] The work implement control unit does not output the resistance reduction command signal when the angle θ1 of the upper plate 65 calculated by the tilt calculation unit is greater than a predetermined tilt threshold. The attitude of the bucket 6 during excavation work is highly correlated with the magnitude of the excavation resistance during excavation work. Specifically, for example, when the tilt of the specific upper region 64 with respect to the horizontal plane H is large, the excavation resistance tends to be small, and when the tilt of the specific upper region 64 with respect to the horizontal plane H is small, the excavation resistance tends to be large. Therefore, when the angle θ1 of the upper plate 65 is greater than the tilt threshold, it is likely that control to reduce the excavation resistance during excavation work is not necessary, and in this case, the work implement control unit does not output the resistance reduction command signal. This reduces the processing load on the controller 50.

[0075] 7 is a flowchart showing the arithmetic and control operation of the controller 50. The controller 50 receives input of lever signals from each of the plurality of operating devices 21 to 23 (step S11). The controller 50 also receives input of earth and sand information from the image acquisition sensor 80, pressure detection signals from the plurality of cylinder pressure sensors 35, and attitude detection signals from the angle sensors 31 to 34.

[0076] Next, bucket attitude calculation unit 51 calculates the bucket attitude based on the boom attitude detection signal, arm attitude detection signal, and bucket attitude detection signal (step S12). Also, the tilt calculation unit of bucket attitude calculation unit 51 calculates angle θ1 of upper plate 65 of bucket 6 with respect to reference plane H based on the boom attitude detection signal, arm attitude detection signal, and bucket attitude detection signal (step S12).

[0077] Next, the sediment amount calculation unit 52 calculates the state of sediment accumulation in the accommodation space of the bucket 6 using the bucket attitude and the sediment information (step S13).

[0078] Next, the bucket travel direction determination unit 55 determines whether or not the angle θ1 of the upper plate 65 of the bucket 6 is smaller than a predetermined inclination threshold value (step S14).

[0079] If angle θ1 of upper plate 65 is equal to or greater than the tilt threshold value (NO in step S14), bucket traveling direction determination unit 55 determines that there is no need to reduce the excavation resistance acting on bucket 6, and bucket traveling direction control unit 56 does not modify the command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal (step S19). In this case, bucket traveling direction control unit 56 outputs command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal to the work device drive unit (step S17).

[0080] On the other hand, if the angle θ1 of the upper plate 65 is smaller than the inclination threshold value (YES in step S14), the contact state determination unit 53 determines the contact state based on the accumulation state calculated by the sediment amount calculation unit 52 (step S15).

[0081] Specifically, in step S13, the sediment amount calculation unit 52 (deposition state calculation unit) can calculate the deposition state of sediment in the storage space of the bucket 6 using, for example, the bucket attitude and the sediment information, as follows: That is, the sediment amount calculation unit 52 compares information on an initial image (initial image information), which is an image of the inside of the bucket 6 in an unaccommodated state, in which no objects such as sediment are accommodated in the storage space of the bucket 6, with information on an image of the inside of the bucket 6 acquired by an image acquisition sensor 80 such as a LiDAR during excavation work (in-excavation image information), thereby calculating the position of a portion PA (intersection PA in the cross-sectional view of FIG. 3 ) where the inner surface of the bucket 6 intersects with the upper surface of the sediment, as shown in FIG. 3 . For example, the sediment amount calculation unit 52 can compare the initial image information with the in-excavation image information by converting the initial image information so that it corresponds to the bucket attitude at the time the in-excavation image information was acquired. Then, the contact state determination unit 53 can determine the contact state by determining whether the calculated portion PA is within the range of a specific upper region 64 of the inner surface of the bucket 6. The initial image information may be stored in advance in the memory of the controller 50. Alternatively, the initial image information may be acquired by the image acquisition sensor 80 before or at the start of excavation work.

[0082] The sediment amount calculation unit 52 may calculate the position of the portion PA where the inner surface of the bucket 6 and the upper surface of the sediment intersect at a predetermined specific widthwise position, such as the center of the widthwise direction of the inner surface of the bucket 6. A distance measurement sensor such as LiDAR can acquire data corresponding to the portion PA where the inner surface of the bucket 6 and the upper surface of the sediment intersect at multiple widthwise positions. In this case, the contact condition determination unit 53 may calculate an average value of the positions of the portion PA where the inner surface of the bucket 6 and the upper surface of the sediment intersect at the multiple widthwise positions, and determine the contact condition using this average value. The contact condition determination unit 53 may also calculate a minimum or maximum value of the positions of the portion PA where the inner surface of the bucket 6 and the upper surface of the sediment intersect at the multiple widthwise positions, and determine the contact condition using this minimum or maximum value.

[0083] If the contact condition determination unit 53 determines that soil is in contact with the specific upper region 64 of the bucket 6 (the upper surface of the bucket 6) (YES in step S15), the bucket traveling direction determination unit 55 determines that the excavation resistance acting on the bucket 6 needs to be reduced, and the bucket traveling direction control unit 56 modifies at least one of the command signals corresponding to the boom operation signal, the arm operation signal, and the bucket operation signal (step S16).

[0084] The command signal may be modified according to a preset movement pattern (target route) of the bucket 6 that corresponds to the resistance reducing operation performed by the bucket 6. For example, the hydraulic excavator 10 may be provided with an input device that allows the operator to select, at the start of excavation work, a resistance reducing operation to be performed by the bucket 6 during excavation work from among the resistance reducing operations shown in FIGS. 3, 4, and 5. In this case, in step S16, the bucket traveling direction control unit 56 modifies at least one of the command signals corresponding to the boom operation signal, the arm operation signal, and the bucket operation signal so that the bucket 6 is displaced along a predetermined movement pattern that corresponds to the resistance reducing operation selected by the operator (step S16), and outputs command signals including the modified resistance reduction command signal to the plurality of proportional valves 71-76 (step S17). As a result, the bucket 6 is displaced in a resistance reducing direction that is a direction in which the excavation resistance acting on the bucket 6 can be reduced.

[0085] On the other hand, if the contact condition determination unit 53 determines that soil is not in contact with the specific upper area 64 of the bucket 6 (NO in step S15), the excavation reaction force calculation unit 54 calculates the excavation reaction force based on the detection signal input from the machine body inclination angle sensor 34, the detection signals input from the boom angle sensor 31, the arm angle sensor 32 and the bucket angle sensor 33, the pressure detection signals input from the multiple cylinder pressure sensors 35, and the dimensional information regarding the dimensions between the links in the work device 3, and the bucket travel direction determination unit 55 determines whether the calculated excavation reaction force is greater than a reaction force threshold, which is a predetermined threshold value (step S18).

[0086] If the excavation reaction force is greater than the reaction force threshold value (YES in step S18), bucket travel direction determination unit 55 determines that the excavation resistance acting on bucket 6 needs to be reduced, and bucket travel direction control unit 56 corrects at least one of the command signals corresponding to the boom operation signal, the arm operation signal, and the bucket operation signal (step S16), and outputs command signals including the resistance reduction command signal that is the corrected command signal to the plurality of proportional valves 71-76 (step S17). As a result, bucket 6 is displaced in a resistance reduction direction, which is a direction in which the excavation resistance acting on bucket 6 can be reduced.

[0087] On the other hand, if the excavation reaction force is equal to or less than the reaction force threshold value (NO in step S18), bucket traveling direction determination unit 55 determines that there is no need to reduce the excavation resistance acting on bucket 6, and bucket traveling direction control unit 56 does not modify the command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal (step S19). In this case, bucket traveling direction control unit 56 outputs command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal to the work device drive unit (step S17).

[0088] Figure 8 is a flowchart showing another example of the arithmetic and control operation of the controller 50. The processing of steps S31 to S33 in Figure 8 is similar to the processing of steps S11 to S13 in Figure 7, and the processing of steps S34 to S36 and S38 in Figure 8 is similar to the processing of steps S15 to S17 and S19 in Figure 7, so detailed explanations of these processes will be omitted. Furthermore, the arithmetic and control operation shown in Figure 8 omits the processing of steps S14 and S18 in Figure 7, but includes the processing of step S37. Therefore, the following will mainly explain the contents related to step S37.

[0089] 8, if the contact state determination unit 53 determines that no sediment is contacting the specific upper region 64 of the bucket 6 (the upper surface of the bucket 6) (NO in step S34), the bucket traveling direction determination unit 55 determines whether the amount of sediment in the bucket 6 is greater than a predetermined sediment amount threshold (step S37). The bucket traveling direction determination unit 55 can determine (calculate) the amount of sediment in the bucket 6, for example, based on the intersection part PA (the intersection point PA) calculated by the sediment amount calculation unit 52. Specifically, for example, the controller 50 stores in advance a map that indicates the relationship between the position of the intersection part PA (the intersection point PA) and the amount of sediment in the bucket 6, and the bucket traveling direction determination unit 55 can calculate the amount of sediment in the bucket 6 based on the intersection part PA (the intersection point PA) calculated by the sediment amount calculation unit 52 and the map. The sediment volume threshold may be set to a value that, for example, prevents the amount of sediment in the bucket at the completion of excavation from being significantly less than the bucket's capacity, while also preventing unnecessary energy consumption.

[0090] If the amount of sediment is greater than the sediment amount threshold (YES in step S37), bucket traveling direction determination unit 55 determines that the excavation resistance acting on bucket 6 needs to be reduced, and bucket traveling direction control unit 56 corrects at least one of the command signals corresponding to the boom operation signal, the arm operation signal, and the bucket operation signal (step S35), and outputs command signals including the resistance reduction command signal that is the corrected command signal to multiple proportional valves 71-76 (step S36). As a result, bucket 6 is displaced in a resistance reduction direction, which is a direction in which the excavation resistance acting on bucket 6 can be reduced.

[0091] On the other hand, if the amount of sediment is equal to or less than the sediment amount threshold value (NO in step S37), bucket traveling direction determination unit 55 determines that there is no need to reduce the excavation resistance acting on bucket 6, and bucket traveling direction control unit 56 does not modify the command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal (step S38). In this case, bucket traveling direction control unit 56 outputs command signals corresponding to the boom operation signal, arm operation signal, and bucket operation signal to the work device drive unit (step S36).

[0092] 9 is a block diagram showing the functional configuration of the controller 50 of the hydraulic excavator 10 according to a modified example of the present embodiment and its input / output signals. The hydraulic excavator 10 according to this modified example is equipped with a load detector 82 instead of the image acquisition sensor 80 shown in the block diagram of FIG. 2. This load detector 82 is another example of a sediment information acquirer that acquires sediment information, which is information related to the sediment stored in the storage space of the bucket 6.

[0093] The load detector 82 is a sensor that is disposed in the specific upper region 64 of the inner surface of the bucket 6 and is capable of detecting the sediment load, which is the load received from the sediment contained in the storage space of the bucket 6. Specifically, the load detector 82 is attached to at least a portion of the specific upper region 64. For example, a strain gauge, a pressure sensor, a load cell, or the like can be used as the load detector 82. The load detector 82 inputs a load detection signal, which is a detection signal corresponding to the detected sediment load, to the controller 50.

[0094] The contact state determination unit 53 determines the contact state between the specific upper region 64 and the soil based on the soil load detected by the load detector 82. Specifically, the contact state determination unit 53 may determine that soil is in contact with the specific upper region, for example, when the soil load detected by the load detector 82 is equal to or greater than a predetermined load threshold. In this modification, the contact state between the specific upper region 64 and the soil is determined based on the soil load detected by the load detector 82, so that the processing load on the controller 50 can be reduced compared to when the contact state is determined based on image processing data (point cloud data) using the image acquisition sensor 80, such as LiDAR, in the block diagram shown in FIG. 2 .

[0095] As described above, in the hydraulic excavator 10 according to this embodiment, the decision as to whether or not to perform control to reduce excavation resistance during excavation work is made based on the state of contact between the specific upper region 64 on the inner surface of the bucket 6 and the soil and sand, so that it is possible to prevent the excavation resistance during excavation work from increasing while also preventing a decrease in the efficiency of the excavation work.

[0096] If the sediment information acquirer is a sensor that directly detects the load received from sediment in contact with the inner surface of the bucket 6 (for example, a sensor such as the load detector 82 described above), the contact state determination unit 53 can directly determine the contact state between the specific upper region 64 and the sediment based on the detection signal input from the sensor to the controller 50. Also, if the sediment information acquirer is a sensor such as the image acquisition sensor 80 described above, the contact state determination unit 53 can indirectly determine the contact state between the specific upper region 64 and the sediment (estimate the contact state) based on sediment information such as image information input from the sensor to the controller 50.

[0097] In this embodiment, when the contact condition determination unit 53 determines that soil is in contact with the specific upper region 64 of the bucket 6, the work device control unit outputs the resistance reduction command signal and displaces the bucket 6 in the resistance reduction direction to reduce the excavation resistance, thereby ensuring a sufficient amount of soil in the bucket 6 during excavation work.

[0098] In this embodiment, the work device control unit outputs the resistance decrease command signal when the contact condition determination unit 53 determines that earth and sand is not in contact with the specific upper region 64 of the bucket 6 and the amount of earth and sand contained in the storage space of the bucket 6 is greater than a predetermined threshold value, that is, a sediment amount threshold. If the amount of earth and sand in the bucket 6 becomes greater than the sediment amount threshold during excavation work, even if the earth and sand in the bucket 6 is not in contact with the specific upper region 64, a resistance decrease command signal is output, so that the bucket 6 can be displaced in the resistance decrease direction to decrease the excavation resistance before the earth and sand in the bucket 6 comes into contact with the specific upper region 64 and the excavation resistance increases. This makes it possible to suppress unnecessary energy consumption.

[0099] In this embodiment, the work implement control unit outputs the resistance reduction command signal when the contact condition determination unit determines that earth and sand is not in contact with the specific upper region 64 of the bucket 6 and the excavation reaction force is greater than the reaction force threshold. In this embodiment, the reaction force threshold is set to a value that can prevent a significant decrease in the operating speed of the bucket 6 due to an increase in the excavation reaction force. A significant decrease in the operating speed of the bucket 6 reduces the efficiency of excavation work. In this embodiment, even if earth and sand in the bucket 6 is not in contact with the specific upper region 64, if the excavation reaction force is greater than the reaction force threshold, the bucket 6 is displaced in the resistance reduction direction to reduce the excavation resistance, thereby further preventing a decrease in the efficiency of excavation work.

[0100] In this embodiment, the contact state determination unit 53 determines the contact state between the specific upper region 64 and the sediment based on the accumulation state calculated by the sediment amount calculation unit 52, which is an example of an accumulation state calculation unit. That is, in this embodiment, the contact state between the specific upper region 64 and the sediment can be determined based on the actual accumulation state of the sediment in the bucket 6.

[0101] In a modified example of this embodiment, the contact state determination unit 53 determines the contact state between the specific upper region 64 and the soil based on the soil load detected by the load detector 82, thereby preventing the processing load on the controller 50 from becoming too large compared to when the contact state is determined based on image processing data, for example.

[0102] In this embodiment, the work implement control unit does not output the resistance decrease command signal when the tilt index value calculated by the tilt calculation unit of the bucket attitude calculation unit 51 is greater than the tilt threshold. When the tilt index value is greater than the tilt threshold, it is highly likely that control to reduce excavation resistance during excavation work is not necessary, and in this case, the resistance decrease command signal is not output. This makes it possible to reduce the processing load on the controller 50.

[0103] [Variations] Although the construction machine according to the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and includes, for example, the following modified examples.

[0104] (A) Operating device In the above embodiment, each of the multiple operating devices (operating devices 21, 22, 23) is configured as an electric lever device, but this is not limited to this configuration. Each of the multiple operating devices may be an operating device including an operating lever and a remote control valve. In this case, the remote control valve of each of the multiple operating devices is interposed between a pilot pump (not shown) and a pair of pilot ports of a control valve corresponding to the remote control valve. The remote control valve operates to supply pilot pressure corresponding to the operation amount of the operating lever to the pilot port corresponding to the operation direction of the operating lever. This adjusts the flow rate and supply direction of hydraulic oil supplied to the cylinder corresponding to the operating device. In this case, each of the proportional valves 71 to 76 may be disposed so as to be interposed between the remote control valve corresponding to the proportional valve and the pilot port of the control valve.

[0105] (B) Work equipment attitude information acquisition device The work implement attitude information acquirer may be, for example, a plurality of stroke sensors. The plurality of stroke sensors include a boom cylinder stroke sensor that detects the cylinder length of the boom cylinder 7, an arm cylinder stroke sensor that detects the cylinder length of the arm cylinder 8, and a bucket cylinder stroke sensor that detects the cylinder length of the bucket cylinder 9. Each of the plurality of stroke sensors inputs a detection signal corresponding to the detected cylinder length to the controller 50. The controller 50 pre-stores dimensional information regarding the dimensions between the links of the work implement 3 and the mounting position of each cylinder. The dimensions between the links include, for example, the distance between the horizontal axis A1 and the horizontal axis A2 and the distance between the horizontal axis A2 and the horizontal axis A3. From the cylinder lengths of the plurality of stroke sensors and the dimensional information, the relative angle between the machine body and the boom 4, the relative angle between the boom 4 and the arm 5, the relative angle between the arm 5 and the bucket 6, the attitude of the work implement 3, and the like can be geometrically calculated. Therefore, the bucket attitude calculation unit 51 can geometrically calculate the attitude of the bucket 6 based on the detection signals and the dimensional information input from the plurality of stroke sensors.

[0106] (C) The construction machinery disclosed herein can also be applied, for example, to (1) cases where machine control is performed to assist the operator in excavation work, (2) cases where the operator remotely controls the excavation work by the hydraulic excavator 10, and (3) cases where the hydraulic excavator 10 is operated automatically (e.g., fully automatically).

[0107] (1) Machine Control When machine control is performed in which controller 50 automatically controls the operation of working implement 3 so that bucket 6 is displaced along a target excavation surface for bucket 6 for excavation work that is pre-stored in the memory of controller 50, at least one operating device for operating the working implement to perform excavation work may be an operating device such as an operating switch that is located in the cabin and can be operated by the operator, or may be any operating device of the plurality of operating devices (e.g., an arm operating device). In this case, when an input operation from the operator is input to the operating device, controller 50 executes machine control to operate working implement 3 so that excavation work is performed to excavate the ground at the work site into a shape that corresponds to the target excavation surface. During excavation work by this machine control, the working implement control unit outputs a resistance reduction command signal for operating the working implement so that the bucket is displaced in the resistance reducing direction, in accordance with the result of the determination by the contact condition determination unit.

[0108] Actual site conditions include a variety of situations that cannot be grasped by those involved in the work before the work begins, so in the above-described machine control, efficient excavation work may not necessarily be possible simply by having controller 50 automatically control the operation of work implement 3 so that bucket 6 displaces along a pre-stored target excavation surface. Even in such cases, by performing control such that the work implement control unit outputs a resistance reduction command signal in accordance with the results of the determination by the contact condition determination unit, it is possible to operate bucket 6 in accordance with the actual site conditions, thereby enabling efficient excavation work.

[0109] (2) Remote control When an operator remotely controls the excavation work by the hydraulic excavator 10, the construction machine includes a construction machine main body constituted by the hydraulic excavator 10 and a remote control device located in a remote location away from the hydraulic excavator 10. The remote control device includes a boom remote control device, an arm remote control device, and a bucket remote control device (not shown) corresponding to the boom operation device 21, the arm operation device 22, and the bucket operation device 23 in the cabin of the hydraulic excavator 10. When the operator operates the operation levers of the boom remote control device, the arm remote control device, and the bucket remote control device, corresponding operation signals are input to the controller 50 of the hydraulic excavator 10 via wireless or wired communication, and the working implement 3 performs an operation corresponding to the operation signal. In this case, at least one operation device for operating the working implement to perform excavation work includes the boom remote control device, the arm remote control device, and the bucket remote control device. Even in this excavation work by remote control, the working implement control unit outputs a resistance reduction command signal for operating the working implement so that the bucket is displaced in the resistance-reducing direction, depending on the result of the determination by the contact condition determination unit. Furthermore, machine control such as that described above may be performed during this remote operation. In this case, at least one operating device for operating the work equipment to perform excavation work may be an operating device such as an operating switch that is located at a remote location and that can be operated by an operator, or may be an operating device for any of the boom remote operating device, the arm remote operating device, and the bucket remote operating device that are located at a remote location.

[0110] In the above-described remote operation, the operator operates the hydraulic excavator 10 while viewing a monitor from a remote location, which can make it difficult for the operator to grasp the actual site conditions in detail, and as a result, the operator may not be able to perform excavation work efficiently. Even in such cases, the work implement control unit can perform control such that it outputs a resistance reduction command signal in accordance with the result of the determination by the contact state determination unit, thereby making it possible to operate the bucket 6 in accordance with the actual site conditions and perform excavation work efficiently.

[0111] (3) About autonomous driving When automatic operation is performed in which the controller 50 automatically controls the operation of the working implement 3 so that the bucket 6 is displaced along a target path for the bucket 6 during excavation work that is stored in advance in the memory of the controller 50, at least one operating device for operating the working implement to perform excavation work may be, for example, an information terminal that an operator can input to. Such an information terminal may be, for example, a personal computer, a mobile information terminal such as a tablet, or another information terminal. When the operator performs an input operation on the information terminal, the information terminal outputs a start command that is a command for instructing the controller 50 to start automatic operation of the hydraulic excavator 10, and the output start command is input to the controller 50 via wireless or wired communication. The operator may perform an input operation on the information terminal outside the hydraulic excavator 10, or may perform an input operation on the information terminal inside the cabin of the hydraulic excavator 10. Even during excavation work performed by this automatic operation (e.g., fully automatic operation), the working implement control unit outputs a resistance reduction command signal for operating the working implement so that the bucket is displaced in the resistance reduction direction, depending on the result of the determination by the contact condition determination unit.

[0112] The automatic operation will be described in more detail as follows. In this automatic operation, the controller 50 determines, for example, whether or not the teeth of the bucket 6 have reached the excavation start position. When it is detected that the teeth have reached the excavation start position, the controller 50 starts the excavation work. In this excavation work, the work implement control unit outputs a target-corresponding command signal, which is a command signal corresponding to the target path, to control the operation of the work implement 3, but if, for example, the contact state determination unit 53 determines that earth and sand is in contact with the specific upper region 64 of the bucket 6, the work implement control unit outputs a resistance reduction command signal (a signal obtained by modifying the target-corresponding command signal) to operate the work implement so as to displace the bucket in the resistance reduction direction.

[0113] Actual site conditions include a variety of situations that cannot be grasped by those involved in the work before the work begins, and therefore, in the above-described automatic operation, efficient excavation work may not necessarily be performed simply by having controller 50 automatically control the operation of work implement 3 so that bucket 6 is displaced along a pre-stored target path for bucket 6 in excavation work. Even in such cases, by performing control such that the work implement control unit outputs a resistance reduction command signal in accordance with the result of determination by the contact condition determination unit, bucket 6 can be operated to suit the actual site conditions, enabling efficient excavation work.

[0114] (D) Containment Status Determination Unit In the above embodiment, the storage state determination unit is a contact state determination unit 53 that determines the contact state between the specific upper region 64 and the earth and sand, and the work implement control unit outputs the resistance decrease command signal in accordance with the result of determination by the contact state determination unit 53. However, the storage state determination unit need only be capable of determining the storage state of the earth and sand stored in the bucket during excavation work, and does not necessarily have to determine the contact state between the specific upper region 64 and the earth and sand as in the above embodiment. In this case, the work implement control unit outputs the resistance decrease command signal in accordance with the result of determination by the storage state determination unit.

[0115] Specifically, the storage state determination unit may be, for example, a sediment amount determination unit that determines whether a predetermined amount of sediment has entered the bucket during excavation work, and in this case, the work device control unit outputs the resistance reduction command signal in accordance with the result of the determination by the sediment amount determination unit. The sediment amount determination unit may determine whether a predetermined amount of sediment has entered the bucket based on a detection signal input to controller 50 from a sensor that can detect the amount of sediment (volume or weight of sediment) in the bucket. Also, if sediment amount calculation unit 52 (accumulation state calculation unit) calculates the amount of sediment (e.g., sediment volume) in the bucket by comparing the initial image information with the image information during excavation, the sediment amount determination unit may determine whether a predetermined amount of sediment has entered the bucket based on the amount of sediment in the bucket calculated by sediment amount calculation unit 52. [Explanation of symbols]

[0116] 3: Work equipment 4: Boom 5: Arm 6: Bucket 61: Bucket base end 62: Bucket tip 64:Specific upper area 65: Bucket top plate 9: Bucket cylinder 10: Hydraulic excavator (construction machinery) 21: Boom operation device 22: Arm operating device 23: Bucket operating device 31: Boom angle sensor (working equipment attitude information acquisition device) 32: Arm angle sensor (working device posture information acquisition device) 33: Bucket angle sensor (working equipment attitude information acquisition device) 34: Aircraft tilt angle sensor 35: Cylinder pressure sensor 50: Controller 51: Bucket attitude calculation unit 52: Sediment volume calculation unit 53: Contact state determination unit (accommodation state determination unit) 54: Excavation reaction force calculation unit 55: Bucket travel direction determination unit (work device control unit) 56: Bucket travel direction control unit (working device control unit) 80: Image acquisition sensor (earth and sand information acquisition device) 82: Load detector (earth and sand information acquisition device) D2: 2nd direction (resistance decreasing direction) D3: 3rd direction (resistance decreasing direction) D4: 4th direction (resistance decreasing direction) H:Horizontal plane (reference plane) θ1: Angle of the top plate of the bucket relative to the horizontal plane (inclination index value)

Claims

1. A construction machine, The aircraft and a working device including a boom supported on the machine body so as to be able to be raised and lowered, an arm rotatably supported on the boom, and a bucket supported on the arm, the bucket having a bucket base end which is a base end rotatably attached to the arm and a bucket tip end which is a tip end on the opposite side thereof, and having an inner surface which defines a storage space which is a space capable of storing earth and sand; at least one operating device for operating the working device so as to perform an excavation operation of excavating earth and sand from the ground by displacing the bucket relative to the ground while maintaining a state in which at least a portion including the tip of the bucket is in contact with the ground in an excavation attitude in which the bucket base end is positioned higher than the tip of the bucket and is capable of excavating earth and sand from the ground; and a controller; The controller a storage state determination unit that determines the storage state of the earth and sand stored in the bucket; a work device control unit that outputs a resistance reduction command signal, which is a command signal for operating the work device so that the bucket is displaced in a resistance reduction direction that is a direction that can reduce the excavation resistance acting on the bucket, in accordance with the result of the determination by the storage state determination unit, the storage state determination unit is a contact state determination unit that determines a contact state between a specific upper region, which is a portion of the inner surface of the bucket that is located at an upper portion in the excavation posture, and the soil, The work device control unit outputs the resistance reduction command signal in accordance with the result of the determination by the contact state determination unit.

2. The construction machine according to claim 1, The work implement control unit outputs the resistance reduction command signal when the contact state determination unit determines that earth and sand is in contact with the specific upper region of the bucket.

3. 3. The construction machine according to claim 1 or 2, The work device control unit outputs the resistance reduction command signal when the contact state determination unit determines that soil is not in contact with the specific upper region of the bucket and the amount of soil stored in the storage space of the bucket is greater than a predetermined soil amount threshold.

4. A construction machine according to any one of claims 1 to 3, The work device control unit outputs the resistance reduction command signal when the contact condition determination unit determines that soil is not in contact with the specific upper region of the bucket and when the excavation reaction force, which is the reaction force that the bucket receives from the ground during the excavation work, is greater than a reaction force threshold, which is a predetermined threshold value.

5. A construction machine according to any one of claims 1 to 4, a work tool attitude information acquirer that acquires work tool attitude information that is information regarding the attitude of the work tool; a sediment information acquirer for acquiring sediment information, which is information about the sediment stored in the storage space of the bucket; The controller a bucket attitude calculation unit that calculates a bucket attitude, which is the attitude of the bucket, using the work implement attitude information; a deposition state calculation unit that calculates a deposition state of sediment in the storage space of the bucket using the bucket posture and the sediment information, The contact state determination unit determines the contact state between the specific upper area and the earth and sand based on the accumulation state.

6. A construction machine according to any one of claims 1 to 4, a load detector disposed in the specific upper region and capable of detecting a sediment load, which is a load received from the sediment stored in the storage space of the bucket; The contact state determination unit determines the contact state between the specific upper area and the earth and sand based on the earth and sand load detected by the load detector.

7. A construction machine according to any one of claims 1 to 4, the controller further includes a gradient calculation unit that calculates a gradient index value that is an index value corresponding to a gradient of the specific upper region with respect to a predetermined reference plane; When the tilt index value calculated by the tilt calculation unit is greater than a tilt threshold value that is a predetermined threshold value, the work device control unit does not output the resistance decrease command signal.

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