Method for controlling work machine, control system for work machine, and work machine

Abstract

To prevent decline in efficiency of a particular process in which a tree is fed in the longitudinal direction.SOLUTION: The work machine drives a hydraulic pump by means of a prime mover, and supplies hydraulic oil, distributed to a plurality of actuators incorporated in an attachment for performing tree felling work, thereby driving the plurality of actuators. Among the plurality of processes constituting the felling work, the actuators include a specific actuator that performs a specific process in which a tree cut and held by the attachment is fed in the longitudinal direction. The control method of the work machine comprises, when the specific actuator carries out the specific process, increasing the discharge flow rate of hydraulic oil discharged from the hydraulic pump beyond a rated flow rate discharged when the hydraulic pump is driven at the rated speed of the prime mover.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a control method for a work machine, a control system for a work machine, and a work machine. [Background technology]

[0002] BACKGROUND ART Conventionally, forestry machines have been known that perform tree felling work by attaching a harvester to the tip of a hydraulic excavator working machine (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-21943 Summary of the Invention [Problem to be solved by the invention]

[0004] Tree felling operations include multiple processes, such as gripping, cutting, feeding (prune), and turning the tree. Of these multiple processes, the process of feeding the gripped tree lengthwise is referred to as a specific process. Furthermore, an actuator (e.g., a feed motor) required to execute the specific process is referred to as a specific actuator. The supply flow rate (required flow rate) of hydraulic oil required to drive the specific actuator is larger than the supply flow rate of hydraulic oil required to drive other actuators. For this reason, if the flow rate of hydraulic oil supplied to the specific actuator is low when the hydraulic pump is driven at the rated rotation speed of the prime mover, for example, the drive speed of the specific actuator may decrease, potentially reducing the work efficiency of the specific process.

[0005] The present invention has been made to solve the above-mentioned problems, and its object is to provide a work machine control method, a work machine control system, and a work machine that can avoid a decrease in work efficiency in the specific process of feeding trees in the length direction. [Means for solving the problem]

[0006] A control method for a work machine according to one aspect of the present invention is a control method for a work machine that drives a hydraulic pump using a prime mover to drive a plurality of actuators included in an attachment that performs tree felling work by distributing and supplying hydraulic oil to the plurality of actuators, wherein the plurality of actuators include a specific actuator that performs a specific process of feeding the tree cut and gripped by the attachment in the lengthwise direction from among a plurality of processes included in the tree felling work, and the control method includes, when the specific actuator performs the specific process, increasing the discharge flow rate of the hydraulic oil discharged from the hydraulic pump above the rated flow rate discharged when the hydraulic pump is driven at the rated rotational speed of the prime mover.

[0007] Another aspect of the present invention relates to a work machine control system that drives a hydraulic pump using a prime mover to drive a plurality of actuators included in an attachment that performs tree felling work by distributing and supplying hydraulic oil to the plurality of actuators, wherein the plurality of actuators include a specific actuator that performs a specific process of feeding the tree cut and gripped by the attachment in the lengthwise direction out of a plurality of processes included in the tree felling work, and the system is equipped with a control unit that, when the specific actuator performs the specific process, increases the discharge flow rate of the hydraulic oil discharged from the hydraulic pump above the rated flow rate discharged when the hydraulic pump is driven at the rated rotational speed of the prime mover.

[0008] A work machine according to yet another aspect of the present invention includes the above-described control system. [Effects of the Invention]

[0009] This avoids a decrease in the efficiency of the specific process of feeding trees lengthwise. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a side view showing a schematic configuration of a hydraulic excavator, which is an example of a work machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram schematically illustrating the configuration of a control system provided in the hydraulic excavator. [Figure 3] FIG. 2 is a block diagram showing a detailed configuration of a harvester actuator provided in the control system. [Figure 4] FIG. 10 is an explanatory diagram schematically illustrating a state in which the harvester attached to the hydraulic excavator performs a feeding process. [Figure 5] FIG. 10 is an explanatory diagram illustrating the harvester performing another feeding process. [Figure 6] FIG. 2 is an explanatory diagram illustrating a schematic view of the harvester performing a cutting process. [Figure 7] FIG. 10 is an explanatory diagram illustrating the harvester performing another cutting process. [Figure 8] FIG. 2 is an explanatory diagram illustrating a schematic view of the harvester performing a rotation process. [Figure 9] 4 is a graph showing an example of the relationship between the pump pressure of a hydraulic pump and the flow rate of hydraulic oil supplied by the hydraulic pump to a harvester actuator. [Figure 10] 4 is a graph schematically showing the relationship between the engine speed and the flow rate required by the actuator under flow rate suppression control. [Figure 11] FIG. 4 is an explanatory diagram schematically illustrating an example of setting the discharge flow rate of the hydraulic pump. [Figure 12] 10A and 10B are explanatory diagrams schematically illustrating other examples of setting the discharge flow rate. [Figure 13] FIG. 10 is an explanatory diagram schematically showing yet another setting example of the discharge flow rate. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes an embodiment of the present invention with reference to the drawings.

[0012] [1. Work Machinery] 1 is a side view showing a schematic configuration of a hydraulic excavator 1, which is an example of a work machine according to this embodiment. The hydraulic excavator 1 includes a lower traveling structure 2, a work implement 3, and an upper rotating structure 4.

[0013] Here, directions are defined as follows: The direction in which the operator (operator, driver) seated in the driver's seat 41a of the upper rotating body 4 faces forward is defined as the forward direction, and the opposite direction is defined as the rearward direction. Therefore, when the upper rotating body 4 is not rotating relative to the undercarriage 2 (swing angle 0°), the fore-and-aft direction of the upper rotating body 4 coincides with the direction in which the undercarriage 2 moves forward and backward. Also, the left side as seen from the operator seated in the driver's seat 41a is defined as the "left," and the right side is defined as the "right." Furthermore, the direction of gravity, which is perpendicular to the fore-and-aft direction and the left-and-right direction, is defined as the up-and-down direction, with the upstream side of the direction of gravity defined as the "up" and the downstream side as the "down." In the drawings, the hydraulic excavator 1 is shown in a state in which the upper rotating body 4 is not rotating relative to the undercarriage 2. Also, in the drawings, the forward direction is indicated by the symbol "F," the rearward by the symbol "B," the upward direction by the symbol "U," and the downward direction by the symbol "D."

[0014] The lower traveling structure 2 includes a pair of left and right crawlers 21 and a pair of left and right traveling motors 22. Each traveling motor 22 is a hydraulic motor. The left and right traveling motors 22 drive the left and right crawlers 21, respectively, to move the hydraulic excavator 1 forward and backward. The lower traveling structure 2 further includes a blade 23 for performing ground leveling work, and a blade cylinder 23a for rotating the blade 23 in the up and down direction. The blade cylinder 23a is formed by a hydraulic cylinder.

[0015] The work implement 3 includes a boom 31, an arm 32, and a harvester 50. The harvester 50 is a forestry attachment used to fell trees. When necessary (for example, when felling trees), the harvester 50 is attached to the end of the arm 32 in place of a bucket (not shown). A hydraulic hose 51 on the harvester 50 side is connected to a PTO connection part 34 on the work implement 3 side, and by driving a hydraulic pump P0 (see FIG. 2) mounted on the upper rotating body 4, hydraulic oil is supplied to each actuator (details of which will be described later) of the harvester 50. This drives the harvester 50.

[0016] The boom 31 and the arm 32 are driven by a boom cylinder 31a and an arm cylinder 32a, respectively. When a bucket is attached to the tip of the arm 32, the bucket is driven by a bucket cylinder 33a. The boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a are each composed of a hydraulic cylinder.

[0017] The base end of the boom 31, i.e., the end of the boom 31 opposite the end connected to the arm 32, is swingably connected to the tip of the revolving frame 42 via a bracket 35. In other words, the hydraulic excavator 1 of this embodiment has a boom swing function in which the boom 31 swings left and right from the tip end as a starting point. A swing cylinder (not shown) for swinging the boom 31 is provided on the revolving frame 42.

[0018] The boom 31 has a shape bent at an obtuse angle and is rotated up and down by extension and retraction of the boom cylinder 31a. The boom cylinder 31a has a base end supported by the tip of the upper rotating body 4, and an end opposite the base end connected to a bent portion of the boom 31, allowing it to move telescopically. The arm 32 is rotatably connected to the tip of the boom 31. The arm 32 is rotated up and down by extension and retraction of the arm cylinder 32a. The arm cylinder 32a has a base end supported by the boom 31, and an end opposite the base end connected to the base end of the arm 32, allowing it to move telescopically. When a bucket is used, the bucket is connected to the tip of the arm 32 and the link mechanism 36, and is rotated up and down by extension and retraction of the bucket cylinder 33a. The bucket cylinder 33a has a base end supported by the arm 32, and an end opposite the base end connected to the link mechanism 36. When the harvester 50 is used instead of a bucket, the harvester 50 is connected to the tip of the arm 32 and the link mechanism 36 in the same manner as the bucket.

[0019] The upper rotating body 4 is located above the lower traveling body 2 and is rotatable relative to the lower traveling body 2. A driving unit 41, a rotating frame 42, a rotating motor 43, and a machine room 44 are arranged on the upper rotating body 4. The upper rotating body 4 rotates via a rotating bearing (not shown) by driving the rotating motor 43, which is a hydraulic motor. In addition to an engine 40 that provides power to each part, multiple hydraulic pumps P0 (see FIG. 2) are arranged at the rear of the upper rotating body 4.

[0020] Each hydraulic pump P0 supplies hydraulic oil (pressurized oil) to a hydraulic motor (for example, the left and right travel motors 22, the swing motor 43) and a hydraulic cylinder (for example, the blade cylinder 23a, the boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a). The above-mentioned hydraulic motors and hydraulic cylinders that are driven by the supply of hydraulic oil from any hydraulic pump P0 are collectively referred to as hydraulic actuators.

[0021] A driver's seat 41a is arranged in the driver's section 41. Operating levers 41b including various operating levers are arranged around the driver's seat 41a. When an operator sits on the driver's seat 41a and operates the operating levers 41b, a predetermined hydraulic actuator is driven.

[0022] [2. Hydraulic excavator control system] 2 is an explanatory diagram that schematically shows the configuration of the control system 100 of the hydraulic excavator 1. In the figure, for the sake of convenience, the path through which an electrical signal flows is shown by a dot-dash line, the path through which pressure oil supplied from the hydraulic pump P0 flows is shown by a solid line, and the path through which pilot oil flows is shown by a dashed line.

[0023] The hydraulic excavator 1 includes a control system 100. The control system 100 includes a plurality of hydraulic pumps P0. In FIG. 2, only one hydraulic pump P0 is illustrated as an example. The plurality of hydraulic pumps P0 include a variable displacement pump and a fixed displacement pump. Each hydraulic pump P0 is driven by the engine 40, and pumps hydraulic oil to a hydraulic actuator. The drive and rotation speed of the engine 40 are controlled based on a control signal (rotation speed command) from a system controller 70, which will be described later.

[0024] The hydraulic actuators include a main machine actuator M-AC and a harvester actuator H-AC. The main machine actuator M-AC includes actuators other than the actuators included in the harvester 50 shown in FIG. 1. Specifically, the main machine actuator M-AC includes the boom cylinder 31a, arm cylinder 32a, bucket cylinder 33a, travel motor 22, blade cylinder 23a, swing motor 43, etc. shown in FIG. 1. Therefore, by driving the main machine actuator M-AC, it is possible to perform travel of the lower traveling body 2, excavation work by the work implement 3 (when a bucket is attached), swing of the upper swing body 4, etc.

[0025] The harvester actuator H-AC is an actuator (forestry actuator) included in the harvester 50. Details of the harvester actuator H-AC will be described later.

[0026] The control system 100 includes a main machine control valve M-CV and a harvester control valve H-CV. The main machine control valve M-CV is a pilot-operated directional control valve that can switch the flow direction and volume of pressure oil pumped from the hydraulic pump P0. The main machine control valve M-CV includes multiple directional control valves provided corresponding to each hydraulic actuator included in the main machine actuator M-AC.

[0027] The harvester control valve H-CV is an electromagnetic directional control valve capable of switching the direction and flow rate of pressure oil pumped from the hydraulic pump P0. The control system 100 (hydraulic excavator 1) is provided with an operating unit 60 that is operated by the operator when driving a specific actuator of the harvester 50. The operating unit 60 is composed of a lever, a switch, and the like. When the operator operates the operating unit 60, an operating signal is output from the operating unit 60 to the system controller 70. In response to this, the system controller 70 outputs an operating command corresponding to the operation of the operating unit 60 to the harvester control valve H-CV. The harvester control valve H-CV switches the flow direction and flow rate of the pressure oil based on the operating command. The harvester control valve H-CV includes a plurality of directional control valves provided corresponding to the hydraulic actuators included in the harvester actuator H-AC.

[0028] The harvester control valve H-CV may be configured as a pilot-operated directional control valve, similar to the main machine control valve M-CV.

[0029] The control system 100 includes a pilot pump PP. The pilot pump PP discharges pilot oil, which serves as an input command to the main control valve M-CV. The pilot pump PP, driven by the engine 40, discharges pressure oil to generate pilot pressure in the pilot oil passage.

[0030] The above-mentioned operating lever 41b (see Figure 1) has a remote control valve RV for switching the direction and pressure of the pressurized oil supplied to the main control valve M-CV. The remote control valve RV is supplied with pressurized oil discharged from the pilot pump PP. The remote control valve RV generates pilot pressure (secondary pressure) according to the direction and amount of operation of the operating lever 41b.

[0031] An electromagnetic proportional pressure reducing valve SV is provided in an oil passage branching from the oil passage between the pilot pump PP and the remote control valve RV. The electromagnetic proportional pressure reducing valve SV adjusts the pilot pressure in response to a flow rate command from the system controller 70. The regulator RE adjusts the tilt angle of the swash plate of the hydraulic pump P0 (variable displacement pump) in response to the adjusted pilot pressure. This makes it possible to change the displacement (volume) of the hydraulic pump P0. That is, in this embodiment, the pilot pressure (pilot signal) is used as a means for changing the displacement of the hydraulic pump P0.

[0032] The system controller 70 is configured by, for example, an electronic control unit called an ECU (Electronic Control Unit), and controls the operation of each part of the control system 100. That is, the control system 100 of this embodiment includes the system controller 70 as a control unit.

[0033] [3. Details of the Harvester Actuator] 3 is a block diagram showing a detailed configuration of the harvester actuator H-AC described above. The harvester actuator H-AC includes a specific actuator AC-1 and a non-specific actuator AC-2. The specific actuator AC-1 is an actuator that executes a specific process among multiple processes included in the felling operation performed by the harvester 50. The non-specific actuator AC-2 is an actuator that executes a non-specific process among the multiple processes.

[0034] Here, the specific process refers to a process in which the harvester 50, which is an attachment, cuts and grips a tree and feeds it lengthwise. Therefore, the specific actuator AC-1 that executes the specific process includes, for example, a feed motor a1. Figure 4 shows a schematic diagram of the harvester 50 executing the feeding process, which is a specific process. With a tree T gripped by the left and right gripping crawlers CR, the feed motor a1 is driven to cause the gripping crawlers CR to travel (rotate) in a circular direction, thereby allowing the gripping crawlers CR to feed the tree T in one direction.

[0035] FIG. 5 is a schematic diagram showing how the harvester 50 performs pruning work. Pruning refers to the work of cutting off branches BR from a tree T (particularly the trunk). As in FIG. 4, when the tree T is gripped by the left and right gripping crawlers CR, the feed motor a1 is driven to feed the tree T in one direction with the gripping crawlers CR, and the branches BR are cut off from the trunk by the front cutter FC of the harvester 50. Therefore, the pruning work of driving the feed motor a1 to feed the tree T in one direction is also included in the specific process (feed process).

[0036] On the other hand, the non-specific process refers to a process other than the specific process among the multiple processes included in the felling operation. Such non-specific processes include, for example, a cutting process, a rotating process, a gripping process, etc. Therefore, as shown in Figure 3, the non-specific actuator AC-2 that executes the non-specific process includes, for example, a saw motor b1, a saw feed cylinder b2, a rotator b3, a tilt cylinder b4, a hold cylinder b5, etc.

[0037] 6 is a schematic diagram showing how the harvester 50 performs a cutting process, which is a non-specific process. When cutting a tree T in its standing state, the harvester 50 stands upright and grips the tree T with the left and right gripping crawlers CR. Then, the saw motor b1 is driven to rotate the chainsaw CS, and the saw feed cylinder b2 is driven to push the chainsaw CS in the cutting direction of the tree T. In this way, the tree T can be cut.

[0038] FIG. 7 shows a schematic diagram of the harvester 50 performing the cutting process on a tree T that has already been cut from a standing tree and laid down (on its side). As in FIG. 6, the tree T is gripped by the left and right gripping crawlers CR, and the saw motor b1 and saw feed cylinder b2 are driven to cut the tree T with the chainsaw CS.

[0039] FIG. 8 schematically shows how the harvester 50 performs a rotation process, which is a non-specific process. With a tree T gripped by the left and right gripping crawlers CR of the harvester 50, the orientation of the harvester 50 can be changed by driving at least one of the rotator b3 and the tilt cylinder b4. This allows the tree T gripped by the gripping crawlers CR to be rotated (including tilted). For example, a tree T that has been cut from a standing tree can be rotated to face sideways.

[0040] The hold cylinder b5 is driven when the left and right gripping crawlers CR grip (grab) the tree T. That is, the hold cylinder b5 is driven when a gripping process for gripping the tree T is executed. The gripping process may be executed alone as a non-specific process, or may be executed in combination with a specific process or another non-specific process as shown in FIGS. 4 to 8.

[0041] [4. Pump flow rate control in specific processes] When felling trees using the harvester 50, the control system 100 of this embodiment drives the hydraulic pump P0 using the engine 40 as a prime mover, and distributes and supplies hydraulic oil to the multiple actuators (specific actuator AC-1, non-specific actuator AC-2) included in the harvester 50 (see FIG. 1 ). This drives the multiple actuators.

[0042] 9 is a graph showing an example of the relationship between the pump pressure (load pressure) of the hydraulic pump P0 and the supply flow rate (discharge flow rate) of hydraulic oil to the harvester actuator H-AC by the hydraulic pump P0. In the figure, the solid line graph shows the above relationship when the hydraulic pump P0 is driven at the rated rotation speed of the engine 40, and the dashed line graph shows the above relationship when the hydraulic pump P0 is driven by increasing the target rotation speed of the engine 40 to a rotation speed higher than the rated rotation speed (but not exceeding the upper limit rotation speed).

[0043] The flow rate (required flow rate) of hydraulic oil required to drive the specific actuator AC-1 at a given pump pressure is defined as Va (L / min). It is known that the required flow rate Va is greater than the flow rate of hydraulic oil required to drive other non-specific actuators AC-2. For this reason, for example, when the hydraulic pump P0 is driven at the rated speed of the engine 40, if the flow rate of hydraulic oil supplied to the specific actuator AC-1 (defined as rated flow rate V1 (L / min)) is less than the required flow rate Va, the drive speed of the specific actuator AC-1 decreases. For example, when pruning is performed by driving the feed motor a1 (see FIG. 3), which is the specific actuator AC-1, the decrease in the drive speed of the feed motor a1 reduces the feed speed of the tree T. As a result, the front cutter FC may not be able to cut the branches BR forcefully, and the feed of the tree T may stop. This reduces the work efficiency of the specific process.

[0044] Therefore, in this embodiment, when an operator uses the operation unit 60 (see FIG. 2) to instruct the specific actuator AC-1 to execute a specific process, the system controller 70 performs the following control. That is, when the specific actuator AC-1 executes the specific process, the system controller 70 as a control unit increases the discharge flow rate of hydraulic oil discharged from the hydraulic pump P0 (the supply flow rate to the harvester actuator H-AC) above the rated flow rate V1 discharged when the hydraulic pump P0 is driven at the rated rotation speed of the engine 40, which is the prime mover. At least one of the following first and second methods can be adopted as a method for increasing the discharge flow rate of the hydraulic pump P0 at this time.

[0045] The first method is to set the target rotation speed of the engine 40 to a value higher than the rated rotation speed. For example, the system controller 70 outputs a rotation speed command to the engine 40 to rotate the engine 40 at a rotation speed higher than the rated rotation speed, thereby setting the target rotation speed of the engine 40 to a value higher than the rated rotation speed.

[0046] When the target rotation speed of engine 40 is increased above the rated rotation speed, the discharge flow rate of hydraulic oil supplied to specific actuator AC-1 at a predetermined pump pressure P (MPa) can be set to V2 (L / min), which is greater than the required flow rate Va of specific actuator AC-1, as shown by the dashed line graph in Figure 9. This eliminates the shortage of hydraulic oil supply to specific actuator AC-1, avoiding a decrease in the drive speed of specific actuator AC-1 and preventing a decrease in the work efficiency of the specific process.

[0047] The second method is to make the discharge flow rate of the hydraulic pump P0 approach or match the maximum value. This discharge flow rate control can be performed, for example, by the system controller 70 controlling the electromagnetic proportional pressure reducing valve SV based on the operation signal from the operation unit 60, and adjusting the tilt angle of the swash plate of the hydraulic pump P0 using the regulator RE.

[0048] For example, in the hydraulic excavator 1, the system controller 70 may perform flow rate suppression control. Flow rate suppression control refers to control that suppresses the discharge flow rate of the hydraulic pump P0 to a value smaller than the maximum value when the engine 40 is driven at a low rotation speed. Flow rate suppression control reduces imbalances in the drive speeds of the actuators when the actuators are operated in a combined manner while the engine rotation speed is low. For example, in a combined operation, when the boom 31 is rotated while the swing motor 43 is rotated, imbalances in the operation such as the swing motor rotating at a high speed while the boom 31 is rotating at a relatively low speed are reduced.

[0049] Fig. 10 is a graph showing a relationship between the engine speed and the required flow rate of the actuator under flow rate suppression control. Fig. 10 shows an example in which, when the engine 40 is driven at the rated speed, the flow rate supplied to the actuator of the hydraulic excavator 1 is suppressed to Q% (i.e., Q<100), with the maximum value being 100%.

[0050] When the specific process is performed, the system controller 70 releases the above-described flow rate suppression control. This releases the restriction on the discharge flow rate of the hydraulic pump P0, making it possible to make the discharge flow rate of the hydraulic pump P0 approach or match the maximum value (100%) while maintaining the target rotation speed of the engine 40 at the rated rotation speed. Therefore, the discharge flow rate of the hydraulic pump P0 is set to a flow rate greater than the required flow rate Va, thereby eliminating the shortage of hydraulic oil supplied to the specific actuator AC-1. As a result, even with the second method, it is possible to avoid a decrease in the drive speed of the specific actuator AC-1 and a decrease in the work efficiency of the specific process.

[0051] The first method and the second method may be performed simultaneously. For example, the system controller 70 may cancel the flow rate suppression control when performing the first method. In this case, the target rotation speed of the engine 40 increases above the rated rotation speed, and the discharge flow rate of the hydraulic pump P0 approaches or matches the maximum value (100%).

[0052] As described above, the control method of this embodiment includes increasing the discharge flow rate of the hydraulic pump P0 above the rated flow rate V1 when a specific process is being executed. This makes it possible to avoid a decrease in the drive speed of the specific actuator AC-1 due to an insufficient flow rate of hydraulic oil, even when the required flow rate Va of hydraulic oil required to drive the specific actuator AC-1 that is executing the specific process is large. Therefore, it is possible to avoid a decrease in the work efficiency of the specific process performed by the specific actuator AC-1.

[0053] The discharge flow rate needs only to be greater than the rated flow rate V1. For example, even if the discharge flow rate is greater than the rated flow rate V1 and equal to or less than the required flow rate Va, the drive speed of the specific actuator AC-1 can be increased and the work efficiency of the specific process can be improved compared to, for example, a configuration that does not implement the first method or the second method. However, from the perspective of further improving the drive speed of the specific actuator AC-1 and the work efficiency of the specific process, it is desirable that the discharge flow rate of the hydraulic pump P0 be greater than the required flow rate Va required to drive the specific actuator AC-1.

[0054] The first method described above may be executed to increase the discharge flow rate above the rated flow rate V1. That is, in the control method of this embodiment, increasing the discharge flow rate above the rated flow rate V1 may include setting the target rotation speed of the engine 40 to a value higher than the rated rotation speed.

[0055] In order to increase the discharge flow rate above the rated flow rate V1, a second method may be executed separately from or simultaneously with the first method. That is, in the control method of this embodiment, increasing the discharge flow rate above the rated flow rate V1 may include bringing the discharge flow rate closer to or equal to a maximum value.

[0056] Here, the flow rate of hydraulic oil required to drive the specific actuator AC-1 is defined as the first required flow rate. Also, the flow rate of hydraulic oil required to drive the non-specific actuator AC-2 is defined as the second required flow rate. The first required flow rate is equal to the above-mentioned required flow rate Va. The second required flow rate is set in accordance with each of the non-specific actuators AC-2. Here, each of the multiple second required flow rates set in accordance with each of the non-specific actuators AC-2 is defined as Vb (L / min).

[0057] In this embodiment, the first required flow rate (=required flow rate Va) is greater than the second required flow rate Vb (of any non-specific actuator AC-2). Therefore, during execution of the specific process, the discharge flow rate of the hydraulic pump P0 is increased above the rated flow rate V1 to bring the discharge flow rate closer to the first required flow rate or to make the discharge flow rate exceed the first required flow rate, thereby effectively preventing a decrease in the work efficiency of the specific actuator AC-1.

[0058] [5. Pump flow control in non-specific processes] Next, the pump flow rate control in the non-specific process performed by the non-specific actuator AC-2 will be described.

[0059] FIG. 11 is an explanatory diagram schematically illustrating an example of setting the discharge flow rate of the hydraulic pump P0 when driving each of three types of non-specific actuators AC-2. Similar to FIG. 9, the solid line graph in FIG. 11 indicates the relationship between the pump pressure and the supply flow rate of hydraulic oil when the hydraulic pump P0 is driven at the rated rotation speed of the engine 40. The three types of non-specific actuators AC-2 are considered here as non-specific actuators X1, X2, and X3. The non-specific actuators X1 to X3 can be any of the saw motor b1, saw feed cylinder b2, rotator b3, tilt cylinder b4, and hold cylinder b5 shown in FIG. 3. Here, as an example, the non-specific actuator X1 is the tilt cylinder b4, the non-specific actuator X2 is the rotator b3, and the non-specific actuator X3 is the hold cylinder b5.

[0060] For example, when the non-specific actuator 1 is driven alone to execute a non-specific process based on operation of the operating unit 60, at the rated rotational speed of the engine 40, hydraulic oil is supplied to the non-specific actuator X1 at a maximum flow rate Vb4max (L / min) for a predetermined pump pressure P1 (MPa) of the hydraulic pump P0. Therefore, if the second required flow rate Vb4 (L / min), which is the flow rate required to drive the non-specific actuator X1, is much smaller than the maximum flow rate Vb4max, hydraulic oil is relieved by the flow rate difference (Vb4max-Vb4) and returned to a hydraulic oil tank (not shown). The relieved hydraulic oil is not used to drive the non-specific actuator X1 and is therefore wasted.

[0061] To reduce such waste, in this embodiment, the system controller 70 executes the following control. That is, when a non-specific process is executed by the non-specific actuator AC-2, the system controller 70 reduces the discharge flow rate of the hydraulic pump P0 from the maximum discharge flow rate based on the second required flow rate of the non-specific actuator AC-2. For example, when one non-specific process is executed by one non-specific actuator X1, the system controller 70 sets the discharge flow rate of the hydraulic pump P0 to the second required flow rate Vb4 required to drive the non-specific actuator X1. The system controller 70 can set the discharge flow rate of the hydraulic pump P0 in this manner by controlling the electromagnetic proportional pressure reducing valve SV based on an operation signal from the operation unit 60 and adjusting the tilt angle of the swash plate of the hydraulic pump P0 using the regulator RE.

[0062] Note that the same control as above can be performed even when the other non-specific actuators X2 and X3 are driven independently. That is, when one non-specific process is executed by one non-specific actuator X2, the system controller 70 sets the discharge flow rate of the hydraulic pump P0 to the second required flow rate Vb3 required to drive the non-specific actuator X2. Also, when one non-specific process is executed by one non-specific actuator X3, the system controller 70 sets the discharge flow rate of the hydraulic pump P0 to the second required flow rate Vb5 required to drive the non-specific actuator X3.

[0063] In this type of control, when a non-specific process is executed, the discharge flow rate of the hydraulic pump P0 is reduced below the maximum discharge flow rate, thereby reducing the load on the engine 40 that drives the hydraulic pump P0. This improves the fuel efficiency of the engine 40. Furthermore, the reduction in the discharge flow rate of the hydraulic pump P0 and the load on the engine 40 reduces heat generation in the hydraulic pump P0 and the engine 40. This improves the heat balance in the hydraulic excavator 1. This reduces deterioration of the electrical equipment provided in the hydraulic excavator 1, and prevents a shortened lifespan of the electrical equipment.

[0064] In particular, by setting the discharge flow rate of the hydraulic pump P0 to the second required flow rate, the non-specific actuator AC-2 is driven with the minimum required discharge flow rate of the hydraulic pump P0. This reliably improves fuel economy and heat balance. The discharge flow rate of the hydraulic pump P0 may be greater than the second required flow rate. However, it is desirable to set the discharge flow rate to the second required flow rate, as this reduces the amount of hydraulic oil relieved to zero and maximizes the utilization efficiency of the hydraulic oil.

[0065] 12 is an explanatory diagram schematically showing another example of setting the discharge flow rate of the hydraulic pump P0. In FIG. 12, the solid line graph and the second required flow rates of the non-specific actuators X1 to X3 are the same as those in FIG.

[0066] When a plurality of non-specific processes are executed simultaneously by a plurality of non-specific actuators X1-X3, that is, when a composite operation is performed by a plurality of non-specific actuators X1-X3, the system controller 70 may set the discharge flow rate of the hydraulic pump P0 based on a total value Tv of the second required flow rates of hydraulic oil required to drive the individual non-specific actuators X1-X3. For example, the system controller 70 may set the discharge flow rate of the hydraulic pump P0 to the total value Tv (= Vb4 + Vb3 + Vb5). The same considerations as above can be applied whether the number of simultaneously driven non-specific actuators is two or four or more.

[0067] With the above settings, when multiple non-specific processes are executed simultaneously, the hydraulic oil is distributed to the individual non-specific actuators X1-X3 at required flow rates Vb4, Vb3, and Vb5, allowing the individual non-specific actuators X1-X3 to be driven simultaneously. In other words, even when multiple non-specific actuators X1-X3 are driven simultaneously, each can be driven at the minimum required flow rate. This reduces the load on the engine 40, improves fuel efficiency, improves heat balance, and prevents a shortened lifespan of electrical equipment compared to, for example, when hydraulic oil is discharged from the hydraulic pump P0 at the maximum discharge flow rate when driving the multiple non-specific actuators X1-X3.

[0068] In particular, if the discharge flow rate of the hydraulic pump P0 is set to the combined value Tv, the plurality of non-specific actuators X1 to X3 can be simultaneously driven with the minimum necessary discharge flow rate of the hydraulic pump P0, thereby reliably achieving the above-mentioned effects of improving fuel efficiency and heat balance. Note that the discharge flow rate of the hydraulic pump P0 may be a value greater than the combined value Tv. However, it is desirable to set the discharge flow rate to the combined value Tv, as this will result in zero amount of hydraulic oil being relieved when the hydraulic pumps are simultaneously driven, thereby maximizing the utilization efficiency of the hydraulic oil.

[0069] Fig. 13 is an explanatory diagram schematically showing yet another setting example of the discharge flow rate of the hydraulic pump P0. In Fig. 13, the solid line graph and the second required flow rates of the non-specific actuators X1 to X3 are the same as in Figs. 11 and 12.

[0070] The plurality of non-specific actuators AC-2 may include a first non-specific actuator AC-21 and a plurality of second non-specific actuators AC-22. In this case, the first non-specific actuator AC-21 is the actuator for which the second required flow rate of hydraulic oil required for driving is the largest among the plurality of non-specific actuators AC-2. Here, the first non-specific actuator AC-21 is, for example, a saw motor b1 (non-specific actuator X4). The second non-specific actuators AC-22 are, for example, a tilt cylinder b4, a rotator b3, and a hold cylinder b5.

[0071] The discharge flow rate of the hydraulic pump P0 may be set to a fixed value. The fixed value is set within a range that is equal to or less than the second required flow rate of the first non-specific actuator AC-21 and greater than the total value Tv of the second required flow rates of the individual second non-specific actuators AC-22. For example, the second required flow rate of the saw motor b1 as the first non-specific actuator AC-21 is set to Vb1 (L / min), and the second required flow rates of the tilt cylinder b4, rotator b3, and hold cylinder b5 as the second non-specific actuators AC-22 are set to Vb4 (L / min), Vb3 (L / min), and Vb5 (L / min), respectively. In this case, the fixed value Fv (L / min) is set to a value that is less than Tv. <Fv≦Vb1となる。ただし、Tv=Vb4+Vb3+Vb5、である。

[0072] By setting the discharge flow rate of the hydraulic pump P0 to a fixed value Fv, it is not necessary to perform a calculation to add up the required flow rates of the individual second non-specific actuators AC-22 each time a second non-specific actuator AC-22 to be simultaneously driven is designated. This makes it possible to obtain the effect of improving fuel efficiency and heat balance with simple control.

[0073] The fixed value may be set within a range that is smaller than the second required flow rate of the first non-specific actuator AC-21 and larger than the total value Tv of the second required flow rates of the individual second non-specific actuators AC-22. However, in this case, when a command to drive the first non-specific actuator AC-21 is issued, it is necessary to supply hydraulic oil to the first non-specific actuator AC-21 with a required flow rate greater than the fixed value, and therefore it is necessary to cancel the setting of the fixed value.

[0074] [6. Supplementary Information] In this embodiment, a hydraulic excavator 1 equipped with an engine 40 as a prime mover has been described, but the control described in this embodiment can also be applied when an electric motor is used as a prime mover instead of the engine 40.

[0075] [7. Notes] The control method, control system, and hydraulic excavator 1 described in this embodiment can also be expressed as a control method, control system, and work machine described in the following supplementary notes.

[0076] The control method for the work machine in Appendix (1) is as follows: A control method for a work machine in which a prime mover drives a hydraulic pump to distribute and supply hydraulic oil to a plurality of actuators included in an attachment that performs tree felling work, the method comprising: the plurality of actuators include a specific actuator that executes a specific process of feeding the tree cut and gripped by the attachment in a lengthwise direction among a plurality of processes included in the felling operation, The control method includes increasing the discharge flow rate of the hydraulic oil discharged from the hydraulic pump when the specific actuator executes the specific process, above the rated flow rate discharged when the hydraulic pump is driven at a rated rotation speed of the prime mover.

[0077] A control method for a work machine according to supplementary note (2) is the control method according to supplementary note (1), The discharge flow rate is greater than the required flow rate required to drive the specific actuator.

[0078] The control method for a work machine according to supplementary note (3) is the control method according to supplementary note (1) or (2), Increasing the discharge flow rate above the rated flow rate includes setting the target rotation speed of the prime mover to a value higher than the rated rotation speed.

[0079] A control method for a work machine according to supplementary note (4) is a control method according to any one of supplementary notes (1) to (3), Increasing the discharge flow rate above the rated flow rate includes bringing the discharge flow rate closer to or to a maximum value.

[0080] A control method for a work machine according to supplementary note (5) is a control method according to any one of supplementary notes (1) to (4), the plurality of actuators includes a non-specific actuator that executes a non-specific process other than the specific process, When the flow rate of the hydraulic oil required to drive the specific actuator is defined as a first required flow rate and the flow rate of the hydraulic oil required to drive the non-specific actuator is defined as a second required flow rate, The first required flow rate is greater than the second required flow rate.

[0081] A control method for a work machine according to supplementary note (6) is the control method according to supplementary note (5), When the non-specified process is executed by the non-specified actuator, the delivery flow rate of the hydraulic pump is reduced from a maximum delivery flow rate based on the second required flow rate.

[0082] A control method for a work machine according to supplementary note (7) is the control method according to supplementary note (6), When one of the non-specified processes is executed by one of the non-specified actuators, the delivery flow rate of the hydraulic pump is set to the second required flow rate required to drive the non-specified actuator.

[0083] A control method for a work machine according to supplementary note (8) is the control method according to supplementary note (6), When a plurality of the non-specific processes are executed simultaneously by a plurality of the non-specific actuators, the discharge flow rate of the hydraulic pump is set based on the sum of the second required flow rates of the hydraulic oil required to drive each of the non-specific actuators.

[0084] A control method for a work machine according to supplementary note (9) is the control method according to supplementary note (8), The discharge flow rate of the hydraulic pump is set to the total value.

[0085] A control method for a work machine according to supplementary note (10) is the control method according to supplementary note (8), the plurality of non-specific actuators include a first non-specific actuator and a plurality of second non-specific actuators; the first non-specific actuator is an actuator for which the second required flow rate of the hydraulic oil required for driving is the largest among the plurality of non-specific actuators, The discharge flow rate of the hydraulic pump is set to a fixed value, The fixed value is set within a range that is equal to or less than the second required flow rate of the first non-specified actuator and is greater than the sum of the second required flow rates of the individual second non-specified actuators.

[0086] The control system of the work machine of appendix (11) A control system for a work machine that drives a plurality of actuators included in an attachment that performs tree felling work by driving a hydraulic pump using a prime mover and distributing and supplying hydraulic oil to the plurality of actuators, the plurality of actuators include a specific actuator that executes a specific process of feeding the tree cut and gripped by the attachment in a lengthwise direction among a plurality of processes included in the felling operation, The hydraulic pump is provided with a control unit that increases the discharge flow rate of the hydraulic oil discharged from the hydraulic pump when the specific actuator executes the specific process, above the rated flow rate discharged when the hydraulic pump is driven at the rated rotation speed of the prime mover.

[0087] The work machine of appendix (12) is equipped with the control system described in appendix (11).

[0088] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0089] The present invention can be used in a work machine to which, for example, a forestry attachment can be attached to perform felling work. [Explanation of symbols]

[0090] 1. Hydraulic excavator (work machine) 40 Engine (prime mover) 50 Harvester (Attachment) 60 Control section 70 System Controller 100 Control System AC-1 Specific Actuator AC-2 Non-specific actuator AC-21 1st non-specific actuator AC-22 Second non-specific actuator H-AC Harvester Actuator H-CV Harvester Control Valve M-AC Main Actuator M-CV Main control valve P0 Hydraulic pump T tree Tv total value Fv fixed value V1 Rated flow rate V2 Discharge flow rate Va required flow rate (1st required flow rate) Vb 2nd required flow rate a1 Feed motor (specific actuator) b1 Saw motor (non-specific actuator) b2 Saw feed cylinder (non-specific actuator) b3 Rotator (non-specific actuator) b4 Tilt cylinder (non-specific actuator) b5 Hold cylinder (non-specific actuator)

Claims

1. A control method for a work machine in which a prime mover drives a hydraulic pump to distribute and supply hydraulic oil to a plurality of actuators included in an attachment that performs tree felling work, the method comprising: the plurality of actuators include a specific actuator that executes a specific process of feeding the tree cut and gripped by the attachment in a lengthwise direction among a plurality of processes included in the felling operation, The control method includes increasing a discharge flow rate of the hydraulic oil discharged from the hydraulic pump when the specific actuator executes the specific process, above a rated flow rate discharged when the hydraulic pump is driven at a rated rotation speed of the prime mover.

2. 2. The control method for a work machine according to claim 1, wherein the discharge flow rate is greater than a required flow rate necessary to drive the specific actuator.

3. 2. The control method for a work machine according to claim 1, wherein increasing the discharge flow rate above the rated flow rate includes setting a target rotation speed of the prime mover to a value higher than a rated rotation speed.

4. 2. The method for controlling a work machine according to claim 1, wherein increasing the discharge flow rate above the rated flow rate includes bringing the discharge flow rate closer to or equal to a maximum value.

5. the plurality of actuators includes a non-specific actuator that executes a non-specific process other than the specific process, When the flow rate of the hydraulic oil required to drive the specific actuator is defined as a first required flow rate and the flow rate of the hydraulic oil required to drive the non-specific actuator is defined as a second required flow rate, The method for controlling a work machine according to claim 1 , wherein the first required flow rate is greater than the second required flow rate.

6. 6. The method for controlling a work machine according to claim 5, further comprising: reducing a discharge flow rate of the hydraulic pump from a maximum discharge flow rate based on the second required flow rate when the non-specified process is executed by the non-specified actuator.

7. 7. The method for controlling a work machine according to claim 6, wherein when one of the non-specified processes is performed by one of the non-specified actuators, the delivery flow rate of the hydraulic pump is set to the second required flow rate required to drive the non-specified actuator.

8. 7. The control method for a work machine according to claim 6, wherein when a plurality of the non-specified processes are executed simultaneously by a plurality of the non-specified actuators, the discharge flow rate of the hydraulic pump is set based on a total value of the second required flow rates of the hydraulic oil required to drive each of the non-specified actuators.

9. The method for controlling a work machine according to claim 8, wherein the discharge flow rate of the hydraulic pump is set to the total value.

10. the plurality of non-specific actuators include a first non-specific actuator and a plurality of second non-specific actuators; the first non-specific actuator is an actuator for which the second required flow rate of the hydraulic oil required for driving is the largest among the plurality of non-specific actuators, The discharge flow rate of the hydraulic pump is set to a fixed value, 9. The control method for a work machine according to claim 8, wherein the fixed value is set within a range that is equal to or less than the second required flow rate of the first non-specified actuator and is greater than a sum of the second required flow rates of the individual second non-specified actuators.

11. A control system for a work machine that drives a plurality of actuators included in an attachment that performs tree felling work by driving a hydraulic pump using a prime mover and distributing and supplying hydraulic oil to the plurality of actuators, the plurality of actuators include a specific actuator that executes a specific process of feeding the tree cut and gripped by the attachment in a lengthwise direction among a plurality of processes included in the felling operation, a control unit that increases the discharge flow rate of the hydraulic oil discharged from the hydraulic pump when the specific actuator is executing the specific process, above the rated flow rate discharged when the hydraulic pump is driven at the rated rotational speed of the prime mover.

12. A work machine comprising the control system of claim 11.

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