CN114032979A

CN114032979A - Excavator

Info

Publication number: CN114032979A
Application number: CN202111520278.8A
Authority: CN
Inventors: 阪田亘只
Original assignee: Sumitomo SHI Construction Machinery Co Ltd
Current assignee: Sumitomo SHI Construction Machinery Co Ltd
Priority date: 2016-10-28
Filing date: 2017-10-30
Publication date: 2022-02-11
Also published as: CN108005139B; CN108005139A; JP2018071434A; JP6752686B2

Abstract

The invention provides an excavator capable of improving oil consumption efficiency of an engine. The excavator of the present invention includes: an engine; a hydraulic pump driven by the engine; a hydraulic driver driven by the hydraulic oil supplied from the hydraulic pump; a working device driven by the hydraulic actuator; an operation device that operates the working device; and a control unit that controls a rotation speed of the engine, wherein the control unit estimates an operation intention of an operator based on an operation state of the operation device, and increases the rotation speed of the engine based on the estimation result.

Description

Excavator

The application is a divisional application with the application number of 201711038166.2, the application date of 2017, 10 and 30 and the invention name of 'excavator'.

Technical Field

The present application claims priority based on 2016 in Japanese patent application No. 2016-. The entire contents of this Japanese application are incorporated by reference into this specification.

The present invention relates to an excavator.

Background

The following structures are disclosed: when an arbitrary operation mode is selected from a plurality of operation modes by operating the throttle capacity valve, the rotation speed of the engine is controlled to be constant in accordance with the set rotation speed corresponding to the selected operation mode (for example, refer to patent document 1).

Patent document 1: japanese patent laid-open publication No. 2004-324511

However, since the work load changes in the work process of the excavator, there is a possibility that a mismatch occurs between the selected work mode and the work load. For example, when selecting a work mode in which the set engine speed is high and the work speed is prioritized, the engine speed is maintained in a relatively high state even when the work load is relatively small, which is not preferable from the viewpoint of fuel efficiency of the engine.

Disclosure of Invention

In view of the above problems, an excavator capable of improving fuel efficiency of an engine is provided.

In order to achieve the above object, according to one embodiment, there is provided a shovel including:

an engine;

a hydraulic pump driven by the engine;

a hydraulic driver driven by the hydraulic oil supplied from the hydraulic pump;

a working device driven by the hydraulic actuator;

an operation device that operates the working device; and

a control unit for controlling the rotational speed of the engine,

the control unit estimates an operation intention of an operator based on an operation state of the operation device, and increases the rotation speed of the engine based on the estimation result.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above embodiment, a shovel capable of improving fuel efficiency of an engine can be provided.

Drawings

Fig. 1 is a side view showing an example of a shovel.

Fig. 2 is a configuration diagram showing an example of a configuration of a hydraulic system of the excavator.

Fig. 3 is a diagram illustrating a series of work flows of the excavator.

Fig. 4 is a diagram showing a relationship between discharge pressure and flow rate of the main pump.

Fig. 5 is a flowchart schematically showing an example of the engine speed increasing process by the controller.

Fig. 6 is a flowchart schematically showing an example of the engine rotation speed reduction process by the controller.

Fig. 7 is a flowchart schematically showing another example of the engine speed raising process by the controller.

Fig. 8 is a flowchart schematically showing another example of the engine rotation speed reduction process by the controller.

Fig. 9 is a flowchart schematically showing a modification of the engine speed increasing process by the controller.

Fig. 10 is a timing chart showing an example of temporal changes in the engine rotation speed and output according to the control processing by the controller.

Description of the symbols

4-boom (working device), 5-arm (working device), 6-bucket (working device), 7-boom cylinder (hydraulic actuator), 8-arm cylinder (hydraulic actuator), 9-bucket cylinder (hydraulic actuator), 11-engine, 12L, 12R-main pump (hydraulic pump), 16-operation device, 16A-boom operation lever, 16B-arm operation lever, 16C-bucket operation lever, 30-controller (control section).

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

First, the structure of the shovel according to the present embodiment will be described with reference to fig. 1 and 2.

Fig. 1 is a side view showing a shovel according to an embodiment of the present invention.

The shovel according to the present embodiment includes: a lower traveling body 1; an upper revolving structure 3 mounted on the lower traveling structure 1 so as to be revolvable via a revolving mechanism 2; a boom 4, an arm 5, and a bucket 6 as a working device; and a cab 10 for an operator to board.

The lower traveling body 1 includes, for example, left and right 1 pair of crawler belts, and the excavator travels by being hydraulically driven by traveling

hydraulic motors

20L and 20R (see fig. 2) for each crawler belt.

The upper slewing body 3 is driven by a slewing hydraulic motor 21 (see fig. 2) to slew with respect to the lower traveling body 1.

The boom 4 is pivotally supported in a front center of the upper revolving structure 3 so as to be tiltable, an arm 5 is pivotally supported at a tip end of the boom 4 so as to be vertically pivotable, and a bucket 6 is pivotally supported at a tip end of the arm 5 so as to be vertically pivotable. The boom 4, the arm 5, and the bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively.

Cab 10 is mounted on the front left side of upper revolving unit 3.

Fig. 2 is a schematic diagram showing an example of the configuration of a hydraulic system and a control system of the excavator according to the present embodiment.

In the figure, the mechanical power system is indicated by a double line, the high-pressure hydraulic line is indicated by a solid line, the pilot line is indicated by a broken line, and the electric drive/control system is indicated by a dotted line.

The hydraulic drive system in the hydraulic system of the excavator according to the present embodiment includes an engine 11, a main pump 12, a regulator 13, a center bypass oil passage 40(40L, 40R), a parallel oil passage 41(41L, 41R), a straight traveling valve 150, and flow rate control valves 151 to 158. The hydraulic drive system in the hydraulic system of the excavator according to the present embodiment includes traveling hydraulic motors 20(20L, 20R), a turning hydraulic motor 21, a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, which are hydraulic actuators that drive the lower traveling structure 1, the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6, respectively.

The engine 11 is a drive power source of the excavator, and drives main pumps 12(12L, 12R) and a pilot pump 14. Engine 11 is a diesel engine using diesel fuel, for example, and is mounted on the rear portion of upper revolving unit 3.

As described above, the main pump 12 is driven by the engine 11 and supplies the hydraulic actuator with the hydraulic oil. The main pump 12 includes

main pumps

12L, 12R. The main pump 12L discharges hydraulic oil sucked from a hydraulic oil tank (not shown) to the center bypass oil passage 40L, and circulates the hydraulic oil to the hydraulic oil tank through the center bypass oil passage 40L. The main pump 12R discharges the hydraulic oil sucked from the hydraulic oil tank to the center bypass oil passage 40R, and circulates the hydraulic oil to the hydraulic oil tank through the center bypass oil passage 40R.

The regulator 13 adjusts the inclination angle of the swash plate of the main pump 12 in accordance with the discharge pressure of the main pump 12 under the control (for example, total horsepower control, negative control (negative control), or the like) of the controller 30, and controls the discharge rate of the main pump 12. Specifically, as will be described later, the regulator 13 adjusts the inclination angle of the swash plate of the main pump 12 in accordance with the pressure of the hydraulic oil introduced from the pressure reducing valve 50 controlled by the controller 30. The regulator 13 includes regulators 13L, 13R corresponding to the

main pumps

12L, 12R, respectively.

The center bypass oil passage 40 includes center

bypass oil passages

40L, 40R. The center bypass oil passage 40L communicates with the flow

rate control valves

151, 153, 155, 157 and is connected to a hydraulic oil tank. The center bypass oil passage 40R communicates with the straight traveling valve 150 and the

flow control valves

152, 154, 156, and 158, and is connected to the hydraulic oil tank.

The parallel oil passages 41 include

parallel oil passages

41L, 41R. The parallel oil passage 41L branches from the center bypass oil passage 40L upstream of the flow control valve 151 (on the side where the main pump 12L is disposed), and supplies the working oil to the

flow control valves

151, 153, 155, and 157 in parallel. The parallel oil passage 41R branches from the center bypass oil passage 40R upstream of the straight traveling valve 150 (on the side where the main pump 12R is disposed), and supplies the working oil to the flow

rate control valves

152, 154, 156, and 158 in parallel.

The straight traveling valve 150 is a spool valve for ensuring the straight traveling property of the lower traveling body 1 during the combined operation (specifically, during simultaneous operation of the lower traveling body 1 and operation of the working device). The straight traveling valve 150 normally performs only an operation of discharging the hydraulic oil in the parallel oil passage 41L and the center bypass oil passage 40R to the downstream side. On the other hand, in the combined operation, the straight traveling valve 150 introduces the working oil downstream of the flow rate control valve 151 in the parallel oil passage 41L into the center bypass oil passage 40R upstream of the flow

rate control valves

152, 154, 156, 158, and introduces the working oil upstream of the flow

rate control valves

152, 154, 156, 158 in the center bypass oil passage 40R into the parallel oil passage 41L upstream of the flow

rate control valves

153, 155, 157. Thus, during the combined operation, the hydraulic oil is supplied from the main pump 12L to both of the flow

rate control valves

151 and 152 that control the traveling

hydraulic motors

20L and 20R, and therefore the straight traveling property of the lower traveling structure 1 is ensured.

The flow

rate control valves

151 and 152 are spool valves that supply the hydraulic oil discharged from the main pumps 14L and 14R to the traveling

hydraulic motors

20L and 20R, respectively, and discharge the hydraulic oil in the traveling

hydraulic motors

20L and 20R to a hydraulic oil tank. The slide shaft moves by a pilot pressure supplied from a joystick or a pedal (not shown) for a walking operation provided in the cab 10. The

flow control valves

151 and 152 control the flow rate and the flow direction of the hydraulic oil supplied to and discharged from the traveling

hydraulic motors

20L and 20R in accordance with the position of the spool.

The

flow control valves

153 and 154 are spool valves that supply the boom cylinder 7 with hydraulic oil discharged from the main pumps 14L and 14R and discharge the hydraulic oil in the boom cylinder 7 to a hydraulic oil tank. The slide shaft moves by a pilot pressure supplied from a boom operation lever 16A provided in the cab 10. The

flow control valves

153 and 154 control the flow rate and the flow direction of the hydraulic oil supplied to the boom cylinder 7 according to the position of the spool.

The flow

rate control valves

155 and 156 are spool valves that supply the hydraulic oil discharged from the main pumps 14L and 14R to the arm cylinder 8 and discharge the hydraulic oil in the arm cylinder 8 to a hydraulic oil tank. The slide shaft moves by the pilot pressure supplied from the arm lever 16B provided in the cab 10. The

flow control valves

155 and 156 control the flow rate and the flow direction of the hydraulic oil supplied to the arm cylinder 8 according to the position of the spool.

The flow control valve 157 is a spool valve that circulates the hydraulic oil discharged from the main pump 12L by the turning hydraulic motor 21. The slide shaft is moved by a pilot pressure supplied from a joystick (not shown) for turning operation provided in the cab 10. The flow control valve 157 controls the flow rate and the flow direction of the hydraulic oil supplied to and discharged from the slewing hydraulic motor 21 in accordance with the position of the spool.

The flow rate control valve 158 is a spool valve for supplying the hydraulic oil discharged from the main pump 12R to the bucket cylinder 9 and discharging the hydraulic oil in the bucket cylinder 9 to a hydraulic oil tank. The slide shaft moves by a pilot pressure supplied from a bucket lever 16C provided in the cab 10. The flow control valve 158 controls the flow rate and the flow direction of the hydraulic oil supplied to the bucket cylinder 9 according to the position of the spool.

The hydraulic pilot system in the hydraulic system of the excavator according to the present embodiment includes the pilot pump 14, the operation device 16, and the pressure reducing valve 50.

The pilot pump 14 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 as described above. The pilot pump 14 supplies the hydraulic oil to the operation device 16, the pressure reducing valve 50, and the like through a pilot line.

The operation device 16 is an operation input mechanism for operating various operational elements of the excavator including the lower traveling structure 1, the upper revolving structure 3, the working mechanism (the boom 4, the arm 5, and the bucket 6), and the like. The operation device 16 includes a boom lever 16A, an arm lever 16B, and a bucket lever 16C.

The boom operation lever 16A is an operation input mechanism for raising and lowering the boom 4. The boom control lever 16A generates a hydraulic pressure (pressure signal) according to the lever operation amount by the hydraulic oil discharged from the pilot pump 14, and acts on one of the left and right pilot ports of the flow control valve 154.

Arm lever 16B is an operation input mechanism for opening and closing arm 5. The arm control lever 16B generates a hydraulic pressure (pressure signal) according to the lever operation amount by the hydraulic oil discharged from the pilot pump 14, and acts on one of the left and right pilot ports of the flow control valve 155.

The bucket lever 16C is an operation input mechanism for opening and closing the bucket 6. The bucket control lever 16C generates a hydraulic pressure (pressure signal) according to the lever operation amount by the hydraulic oil discharged from the pilot pump 14, and acts on one of the left and right pilot ports of the flow control valve 158.

The pressure reducing valve 50 includes

pressure reducing valves

50L, 50R corresponding to the regulators 13L, 13R. The pressure reducing valve 50L reduces the pressure of the hydraulic oil discharged from the pilot pump 14 to a desired pressure (set pressure) under the control of the controller 30, and acts on the regulator 13L. Similarly, the pressure reducing valve 50R reduces the pressure of the hydraulic oil discharged from the pilot pump 14 to a desired pressure (set pressure) under the control of the controller 30, and acts on the regulator 13R. Thus, the controller 30 can control the pressure acting on the regulators 13L, 13R by the

pressure reducing valves

50L, 50R, and adjust the swash plate inclination angles of the

main pumps

12L, 12R. The

pressure reducing valves

50L, 50R reduce the discharge amounts of the

main pumps

12L, 12R so that the pump horsepower indicated by the product of the discharge pressure and the discharge amount does not exceed the horsepower of the engine 11 when the discharge pressures of the

main pumps

12L, 12R become equal to or higher than a predetermined value in accordance with a control command from the controller 30 (total horsepower control).

Further, the pressure reducing valve 50(50L, 50R) may be an electromagnetic proportional valve.

The control system of the excavator according to the present embodiment includes the pressure sensor 17, the boom cylinder pressure sensor 18a, the discharge pressure sensor 18b, the controller 30, the ECM60, the mode adjustment knob 70, and the like.

The pressure sensor 17 detects the pressure of the hydraulic oil output from the operation device 16, that is, the pressure of the hydraulic oil corresponding to the operation amount in the operation device 16. The pressure sensor 17 includes

pressure sensors

17A, 17B, and 17C corresponding to the boom lever 16A, the arm lever 16B, and the bucket lever 16C, respectively.

The pressure sensor 17A detects the pressure of the hydraulic oil corresponding to the operation amount of the boom raising operation of the boom operation lever 16A among the hydraulic oil output from the boom operation lever 16A, and transmits a detection signal (detection value) to the controller 30.

The pressure sensor 17A may be configured to be able to detect the pressure of the hydraulic oil corresponding to the operation amount of the boom lowering operation of the boom control lever 16A, among the hydraulic oil output from the boom control lever 16A.

The pressure sensor 17B detects the pressure of the hydraulic oil corresponding to the operation amount of the arm closing operation of the arm control lever 16B, among the hydraulic oil output from the arm control lever 16B, and transmits a detection signal (detection value) to the controller 30.

The pressure sensor 17B may be configured to be able to detect the pressure of the hydraulic oil output from the arm control lever 16B in accordance with the amount of operation of the arm opening operation of the arm control lever 16B.

The pressure sensor 17C detects the pressure of the hydraulic oil output from the bucket lever 16C corresponding to the operation amount of the bucket closing operation of the bucket lever 16C, and sends a detection signal (detection value) to the controller 30.

Further, the pressure sensor 17C may detect the pressure of the hydraulic oil corresponding to the operation amount of the bucket opening operation of the bucket lever 16C among the hydraulic oil output from the bucket lever 16C.

The boom cylinder pressure sensor 18a detects the pressure of the bottom side of the boom cylinder, and sends a detection signal (detection value) to the controller 30.

The discharge pressure sensors 18b are 2, detect the discharge pressures of the

main pumps

12L and 12R, and transmit detection signals (detection values) to the controller 30.

The controller 30 performs various control processes of a control system of the shovel. The functions of the controller 30 may be realized by any hardware, software, or a combination thereof, and for example, the controller is configured to be centered on a microcomputer including a CPU, a RAM, a ROM, and an I/O. For example, the controller 30 transmits a control command to the

pressure reducing valves

50L and 50R based on a detection value of the discharge pressure of the

main pumps

12L and 12R received from the discharge pressure sensor 18b and a detection value of the negative control pressure received from a negative control pressure sensor (not shown), and performs total horsepower control and negative control of the

main pumps

12L and 12R. Then, for example, the controller 30 transmits a control command to the ECM70 that performs the operation control of the engine 11 in accordance with the operation state of the operation device 16 and the operation mode selected by the mode adjustment knob 70, and performs control (constant speed control) to maintain the rotation speed of the engine 11 constant in accordance with the set rotation speed NEset. Specifically, when the operation device 16 does not operate (at the time of operation) the lower traveling structure 1, the upper slewing structure 3, the working mechanism (the boom 4, the arm 5, the bucket 6), or the like, the controller 30 sets the set rotation speed NEset of the engine 11 to a relatively high predetermined rotation speed NE _ H or an intermediate predetermined rotation speed NE _ M (< NE _ H). On the other hand, when the operation device 16 operates (at the time of non-operation) the lower traveling structure 1, the upper slewing structure 3, the working mechanism (the boom 4, the arm 5, the bucket 6), and the like, the controller 30 sets the set rotation speed NEset of the engine 11 to a relatively low predetermined rotation speed NE _ L (fuel saving control). The control of the rotation speed of the engine 11 by the controller 30 will be described in detail later.

The predetermined rotation speed NE _ H, NE _ M, NE _ L differs depending on the operation mode selected by the mode adjustment knob 70.

The ECM60 controls the operation of the engine 11 by, for example, sending a control command to a fuel injection device or the like.

The mode adjustment knob 70 is an operation mechanism for selecting a work mode of the excavator corresponding to the set rotation speed NEset of the engine 11. The work modes of the excavator include a Super Power (SP) mode in which the set rotation speed NEset of the engine 11 is high and the work speed is prioritized, a Heavy (H) mode in which the set rotation speed NEset of the engine 11 is intermediate and the work load is high, an Auto (Auto) mode in which the set rotation speed NEset of the engine 11 is low and the work is performed in a wide range, and the like.

Further, between the a mode and the idle mode, the mode adjustment knob 70 can also select the set rotation speed NEset lower than the a mode.

Next, the operation of the excavator will be described with reference to fig. 3.

Fig. 3 is a diagram showing an example of a working process of the excavator, and specifically, a diagram showing a working process in a deep excavation and loading operation. Specifically, fig. 3(a) to 3(D) show an excavation operation section, fig. 3(E) shows a boom raising operation section, fig. 3(F) shows a dumping operation section, and fig. 3(G) shows a boom lowering operation section.

First, as shown in fig. 3 a, the operator positions the front end of the bucket 6 so that the front end of the bucket 6 is at a desired height position to be excavated within the working area N of the working device (the boom 4, the arm 5, and the bucket 6). Then, as shown in fig. 3(B), in a state where the bucket 6 is opened, the operator starts the excavation operation by gradually raising the boom 4 and closing the arm 5. Hereinafter, the operation states of fig. 3(a) and 3(B) are referred to as the first half of the excavation operation in the excavation operation section.

Next, as shown in fig. 3(C), the operator gradually lifts the boom 4 further from the state of fig. 3(B) and closes the arm 5, thereby fully storing the excavated soil in the bucket 6. Then, as shown in fig. 3(D), the operator closes the bucket 6 while further closing the arm 5, thereby raising the bucket 6 accommodating the excavated soil into the air. Hereinafter, the operation states of fig. 3(C) and 3(D) will be referred to as the second half of the excavation operation in the excavation operation section.

In the excavation operation interval, the excavator is in a light load state in which the work load (i.e., the discharge pressure of the

main pumps

12L, 12R) is relatively low in the first half of the excavation operation. On the other hand, in the latter half of the excavation operation, since the force input to the bucket 6 from the ground (excavation) is increased, high horsepower is required, and the work load of the excavator becomes a relatively high load state.

Next, as shown in fig. 3(E), the operator lifts the boom 4 to a desired height from the ground at the bottom of the bucket 6. The desired height refers for example to a position above the level of tipping. Subsequently, or simultaneously, the operator turns the upper turning body 3 as shown by an arrow AR1 and moves the bucket 6 to the position for discharging soil. In the initial stage of the raising operation of the boom 4, high horsepower is required, the work load of the excavator is in a relatively high load state, the required horsepower gradually decreases as the boom 4 is raised (including a combined operation with the swing operation), and the excavator transitions to a light load state in which the work load is relatively low.

Next, as shown in fig. 3(F), the operator opens arm 5 and bucket 6 to discharge the soil in bucket 6. The operator can open only the bucket 6 to perform the dumping. In the dumping operation interval, the required horsepower is low, and the work load of the excavator is in a relatively low light load state.

Next, as shown in fig. 3(G), the operator turns the upper turning body 3 as indicated by an arrow AR2, and moves the bucket 6 to a position directly above the excavation position. At this time, the operator lowers the boom 4 while performing the turning, lowers the bucket 6 to a desired height from the excavation target, and performs the excavation operation again. In the boom-down swing operation section, the required horsepower is lower than that in the dumping operation section, and the excavator is in a light load state where the work load is very low.

The operator advances the deep excavation and loading operations while repeating the excavation operation, the boom raising operation, the dumping operation, and the boom lowering operation for 1 cycle.

Next, referring to fig. 4, an outline of control of the engine 11 on the premise of the operation process of the excavator of fig. 3 will be described.

Fig. 4 is a diagram (P-Q diagram) showing a relationship between a pressure (discharge pressure) P and a flow rate (discharge rate) Q of the main pump 12(12L, 12R).

In the figure, a curve L1 shows a relationship between the discharge pressure P and the discharge rate Q when the set rotation speed NEset of the engine 11 is the predetermined rotation speed NE _ H, and a curve L2 shows a relationship between the discharge pressure P and the discharge rate Q when the set rotation speed NEset of the engine 11 is the predetermined rotation speed NE _ M. In the figure, the predetermined pressure P2 is smaller than the predetermined pressure P1, which is the discharge pressure P corresponding to the boundary between the light load state and the high load state of the main pump 12 in the curve L1, and the discharge pressure P exceeds the predetermined pressure P1 and is the discharge pressure P in the light load state before the main pump 12 reaches the high load state.

Conventionally, when the operation mode is set by the mode adjustment knob 70, the engine 11 is controlled based on the constant set rotation speed NEset corresponding to the operation mode. At this time, since the low load state and the high load state exist in the working process of the excavator, the set rotation speed NEset at which the horsepower required in the high load state can be output from the main pump 12 (that is, the set rotation speed NEset corresponding to the predetermined rotation speed NE _ H) is set to be relatively high as described above. Therefore, in the light load state, the suction horsepower of the main pump 12 becomes larger than necessary, and therefore the discharge rate of the main pump 12 becomes large, and the speed of the working equipment becomes high, whereby the operability deteriorates, or the fuel efficiency of the engine 11 deteriorates.

In contrast, in the present embodiment, a predetermined rotation speed NE _ M as the set rotation speed NEset corresponding to the light load state of the shovel and a predetermined rotation speed NE _ H (> NE _ M) as the set rotation speed NEset corresponding to the high load state of the shovel are provided. Accordingly, the suction horsepower of the main pump 12 is suppressed in the light load state, so that the operability can be prevented from being deteriorated, and the set rotation speed NEset of the engine 11 can be set to be smaller than that in the high load state, so that the fuel efficiency of the engine 11 can be improved.

Specifically, as shown by a curve L2 in fig. 4, in a state where the set rotation speed NEset is set to the predetermined rotation speed NE _ M, the controller 30 controls the regulator 13 to maintain the discharge amount Q constant with respect to an increase in the discharge pressure P in a light load state where the discharge pressure P is equal to or lower than the predetermined pressure P1. On the other hand, in a high load state where the discharge pressure P exceeds the predetermined pressure P1, the controller 30 gradually decreases the discharge rate Q with respect to an increase in the discharge pressure P so that the suction horsepower of the main pump 12, which is expressed by the product of the discharge pressure P and the discharge rate Q, does not exceed the output of the engine 11. That is, the predetermined pressure P1 of the curve L2 corresponds to the boundary (inflection point) between the state where the discharge amount Q is constant (light-load state of the main pump 12) and the state where the discharge amount Q is reduced (high-load state of the main pump 12) with respect to the increase in the discharge pressure P, and corresponds to the inflection point of the curve P-Q diagram. At this time, when the discharge pressure P of the main pump 12 is increased to or above the predetermined pressure P2, which is lower than the predetermined pressure P1, in the light load state, the controller 30 determines that the shovel is highly likely to transition to the high load state. At the same time, if it can be determined from the operation state of the operation device 16 that the operation by the operator corresponding to the excavation operation or the boom raising/turning operation section is being performed, the controller 30 determines that there is a high possibility that the shovel is transitioning to the high-load state. That is, the controller 30 determines that the shovel has transitioned from the low load state to the high load state based on the discharge pressure of the main pump 12 and the operating state of the operating device 16, and raises the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ M to the predetermined rotation speed NE _ H. Thus, the relationship between the discharge pressure P and the discharge amount Q of the main pump 12 (P-Q diagram) transitions from the curve L2 to the curve L1, and the discharge amount Q increases for the same discharge pressure P as the output of the engine 11 increases. Therefore, the excavator can appropriately perform the work (the second half of the excavation operation, the boom raising and turning operation) corresponding to the high load state.

Next, details of a specific control process of the controller 30 will be described with reference to fig. 5 to 9.

First, fig. 5 is a flowchart schematically showing an example of a process (engine rotation speed increasing process) in which the controller 30 increases the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ M to the predetermined rotation speed NE _ H. When the set rotation speed NEset is set to the predetermined rotation speed NE _ M during the operation of the excavator, the process according to the flowchart is repeatedly executed.

When the operator starts the operation of the excavator using the operation device 16, the controller 30 first increases the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ L corresponding to the fuel saving control to the predetermined rotation speed NE _ M.

In step S102, the controller 30 determines whether or not the arm closing operation amount of the arm control lever 16B is maximum (operation amount of the full stroke) based on the detection value of the pressure sensor 17B. When the boom closing operation amount is the maximum, the controller 30 proceeds to step S104, and if this is not the case, ends the present process.

In the process of step S102, it is sufficient if it can be determined whether or not the operation of the operation device 16 by the operator is in a direction in which the work load of the work implement increases. Therefore, the controller 30 does not necessarily need to determine whether or not the arm closing operation amount is the maximum, and may determine whether or not the operation amount is a relatively large operation amount (for example, at least 80% or more of the full stroke).

In step S104, the controller 30 determines whether or not at least one of a case where the boom raising operation amount of the boom control lever 16A corresponds to the intermediate region and a case where the bucket closing operation of the bucket control lever 16C is being performed is established, based on the detection values of the

pressure sensors

17A and 17C. The intermediate region is a predetermined range (for example, a range between 30% and 70% of the full stroke) around the middle between zero and the maximum operation amount. If the determination condition is satisfied, the controller 30 proceeds to step S106, and if not, ends the present process. That is, when the determination conditions in steps S102 and S104 are satisfied, the controller 30 determines that the operator is performing the operation intended for the excavation operation, and proceeds to step S106.

In step S106, the controller 30 determines whether or not the discharge pressure P of the main pump 12 is equal to or higher than a predetermined pressure P2, based on the detection value of the discharge pressure sensor 18 b. At this time, the controller 30 may determine whether the discharge pressure P of both the

main pumps

12L, 12R is equal to or higher than the predetermined pressure P2, and the controller 30 may determine whether at least one of the discharge pressures is equal to or higher than the predetermined pressure P2, and may select which one is appropriately determined. When the discharge pressure P of the main pump 12 is equal to or higher than the predetermined pressure P2, the controller 30 determines that there is a possibility that the shovel will transition from the low-load state to the high-load state, and proceeds to step S108, and if this is not the case, the process ends this time.

That is, in steps S102 to S106, controller 30 estimates the operation of the work implement (boom 4, arm 5, and bucket 6) toward the high load state by the operator using operation device 16. Specifically, controller 30 determines whether or not the operation of operation device 16 by the operator is in a direction in which the work load of the work implement increases (for example, the raising direction of boom 4, the closing direction of arm 5, and the closing direction of bucket 6) (steps S102 and S104). If the controller 30 determines that the operator has operated the operation device 16 in the direction in which the work load of the work implement is increasing (yes in step S102 and yes in step S104), it is determined that there is a possibility that the excavator will transition from the low-load state to the high-load state if the discharge pressure P of the main pump 12 is equal to or higher than the predetermined pressure P2 during the operation (yes in step S106). As described above, as a result of estimating the operation intention of the operator on the operation device 16, the controller 30 determines whether or not the operation performed on the operation device 16 is in a direction in which the workload of the work machine increases. In particular, in the present example, the controller 30 determines whether the operation intention of the operator on the operation device 16 corresponds to the process in the latter half of the excavation operation of the excavator.

In step S108, the controller 30 sets the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ M to the predetermined rotation speed NE _ H to increase the rotation speed of the engine 11, thereby ending the present process.

Next, fig. 6 is a flowchart schematically showing an example of a process (engine rotation speed reduction process) in which the controller 30 reduces the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M. Specifically, the processing of fig. 5 is a processing for reducing the set rotation speed NEset set to the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M. When the set rotation speed NEset of the engine 11 is set to the predetermined rotation speed NE _ H by the process of fig. 5 during the operation of the excavator, the process according to the present flowchart is repeatedly executed.

In step S202, the controller 30 determines whether or not the arm closing operation amount of the arm control lever 16B is equal to or greater than a predetermined amount (for example, 50% of the full stroke) of the intermediate range (that is, equal to or greater than the half stroke) based on the detection value of the pressure sensor 17B. When the arm closing operation amount is not equal to or greater than the half stroke, the controller 30 determines that the excavation operation of the excavator is ended, and proceeds to step S204, and when the arm closing operation amount is equal to or greater than the half stroke, the controller 30 determines that the excavation operation of the excavator is continued, and ends this processing.

In step S204, the controller 30 sets the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M, decreases the rotation speed of the engine 11, and ends the present process.

Next, fig. 7 is a diagram showing another example of the engine speed increasing process by the controller 30. As in the case of fig. 5, when the set rotation speed NEset is set to the predetermined rotation speed NE _ M during the operation of the excavator, the process according to the present flowchart is repeatedly executed.

In step S302, the controller 30 determines whether or not the boom raising operation amount of the boom manipulating lever 16A is maximum (operation amount of the full stroke) based on the detection value of the pressure sensor 17A. When the boom raising operation amount is the maximum, the controller 30 determines that the boom raising operation is being performed, and proceeds to step S304, and if this is not the case, the process ends.

In the processing of step S302, it is sufficient if it can be determined whether or not the operation of the operation device 16 by the operator is in a direction in which the work load of the work device increases. Therefore, the controller 30 does not necessarily determine whether or not the boom raising operation amount is the maximum, and can determine whether or not the operation amount is a relatively large operation amount (for example, at least 80% or more of the full stroke).

In step S304, the controller 30 determines whether or not the discharge pressure P of the main pump 12 is equal to or higher than a predetermined pressure P2, based on the detection value of the discharge pressure sensor 18 b. In this case, as in the case of step S106 in fig. 5, the controller 30 may determine whether the discharge pressure P of both the

main pumps

12L, 12R is equal to or higher than the predetermined pressure P2, and the controller 30 may determine whether at least one of the discharge pressures is equal to or higher than the predetermined pressure P2, and may select which one is appropriately determined. When the discharge pressure P of the main pump 12 is equal to or higher than the predetermined pressure P2, the controller 30 determines that there is a possibility that the shovel will transition from the low-load state to the high-load state, and proceeds to step S306, and if this is not the case, the process ends this time.

That is, in steps S302 and S304, controller 30 estimates the operation of the work implement (boom 4, arm 5, and bucket 6) toward the high load state by the operator using operation device 16. Specifically, controller 30 determines whether or not the operation of operation device 16 by the operator is in a direction in which the work load of the work implement increases (for example, the lifting direction of boom 4) (step S302). If the controller 30 determines that the operator has operated the operation device 16 in the direction in which the work load of the work implement is increasing (yes in step S302), it determines that there is a possibility that the shovel will transition from the low-load state to the high-load state if the discharge pressure P of the main pump 12 is equal to or higher than the predetermined pressure P2 during the operation (yes in step S304). As described above, as in the case of fig. 5, the controller 30 determines whether or not the operation performed on the operation device 16 is in a direction in which the workload of the work implement increases as a result of estimating the operation intention of the operator on the operation device 16. In particular, in the present example, the controller 30 determines whether or not the operation intention of the operator on the operation device 16 corresponds to the step of the boom raising operation of the excavator.

In the process of step S304, if the pressure value is lower than the predetermined pressure P1 and it is possible to determine whether the discharge pressure P exceeds the predetermined pressure P1 and the high load state is transitioning, the controller 30 may perform the determination process using a pressure value different from the predetermined pressure P2. The controller 30 may determine whether there is a possibility of the shovel transitioning from the low load state to the high load state based on the detection value of the boom cylinder pressure sensor 18 a. Also, the process of step S304 may be omitted. This is because, in general, when the boom raising operation amount is the largest, a transition of the shovel from the low load state to the high load state is obvious.

In step S306, the controller 30 sets the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ M to the predetermined rotation speed NE _ H to increase the rotation speed of the engine 11, thereby ending the present process.

Next, fig. 8 is a flowchart schematically showing another example of a process (engine rotation speed reduction process) in which the controller 30 reduces the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M. Specifically, the processing of fig. 7 is processing for reducing the set rotation speed NEset set to the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M. When the set rotation speed NEset of the engine 11 is set to the predetermined rotation speed NE _ H by the process of fig. 5 during the operation of the excavator, the process according to the present flowchart is repeatedly executed.

In step S402, the controller 30 determines whether or not the operation amount of the boom manipulating lever 16A is maximum (operation amount of the full stroke) based on the detection value of the pressure sensor 17A. If the boom raising operation amount is not the maximum, the controller 30 determines that the boom raising operation is ended, and proceeds to step S404, and if this is not the case, the controller 30 determines that the boom raising operation is continued, and ends the process this time.

In the processing of step S402, it is sufficient if it can be determined whether or not the operation of the operation device 16 by the operator is in a direction in which the work load of the work device increases. Therefore, the controller 30 does not necessarily determine whether or not the boom raising operation amount is the maximum, and can determine whether or not the operation amount is a relatively large operation amount (for example, at least 80% or more of the full stroke).

In step S404, the controller 30 sets the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M, decreases the rotation speed of the engine 11, and ends the present process.

Next, fig. 9 is a flowchart schematically showing a modification of the engine speed increasing process by the controller 30. Specifically, the processing of step S302 in the engine rotation speed increasing processing shown in fig. 7 is replaced with the processing of step S502. As in the case of fig. 5 and 7, when the set rotation speed NEset is set to the predetermined rotation speed NE _ M during the operation of the excavator, the process according to the present flowchart is repeatedly executed.

In step S502, the controller 30 determines whether or not the boom raising operation speed of the boom manipulating lever 16A is equal to or higher than a predetermined threshold value, based on the detection value of the pressure sensor 17A. The predetermined threshold value is predetermined as a value that can be determined that the excavator is performing the boom raising operation. If the boom raising operation speed is equal to or higher than the predetermined threshold value, the controller 30 determines that the boom raising operation is being performed, and proceeds to step S504, and if this is not the case, the process ends this time.

In step S504, the controller 30 determines whether or not the discharge pressure P of the main pump 12 is equal to or higher than a predetermined pressure P2, based on the detection value of the discharge pressure sensor 18b, as in step S304. When the discharge pressure P of the main pump 12 is equal to or higher than the predetermined pressure P2, the controller 30 determines that there is a possibility that the shovel may transit from the low-load state to the high-load state, and proceeds to step S506, and if this is not the case, the process ends.

That is, in steps S502 and S504, the controller 30 estimates the operation of the working implement (the boom 4, the arm 5, and the bucket 6) toward the high load state by the operator using the operation device 16, as in the case of steps S302 and S304. Specifically, controller 30 determines whether or not the operation of operation device 16 by the operator is in a direction in which the work load of the work implement increases (for example, the lifting direction of boom 4) (step S502). If the controller 30 determines that the operator has operated the operation device 16 in the direction in which the work load of the work implement is increasing (yes in step S502), it is determined that there is a possibility that the shovel will transition from the low-load state to the high-load state if the discharge pressure P of the main pump 12 is equal to or higher than the predetermined pressure P2 during the operation (yes in step S504). As described above, as in the case of fig. 5 and 7, the controller 30 determines whether or not the operation performed on the operation device 16 is in the direction in which the work load of the work device increases as the estimation result of estimating the operation intention of the operator on the operation device 16. In particular, in the present example, as in the case of fig. 7, the controller 30 determines whether or not the operation intention of the operator on the operation device 16 corresponds to the step of the boom raising operation of the excavator.

In the process of step S504, if the pressure value is lower than the predetermined pressure P1 and it is possible to determine whether the discharge pressure P exceeds the predetermined pressure P1 and the high load state is transitioning, the controller 30 may perform the determination process using a pressure value different from the predetermined pressure P2. Further, as in step S304, the controller 30 may determine whether there is a possibility of the shovel transitioning from the low load state to the high load state based on the detection value of the boom cylinder pressure sensor 18 a. Also, like step S304, the process of step S504 may be omitted.

In step S506, the controller 30 sets the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ M to the predetermined rotation speed NE _ H to increase the rotation speed of the engine 11, and ends the present process, as in step S306.

Both of the combinations of fig. 5 and 6 and the combinations of fig. 7 (or fig. 9) and 8 described above may be used, or either one may be used. In the case of both, the processing of fig. 5 and 7 (or fig. 9) is executed in parallel.

Next, referring to fig. 10, a description will be given of temporal changes in the rotation speed and output (horsepower W) of the engine 11 according to the processing of fig. 5 to 8 by the controller 30 or the processing of fig. 5, 6, 8, and 9.

Fig. 10 is a timing chart showing an example of temporal changes in the rotation speed and output of the engine 11 according to the control processing by the controller 30. Specifically, the time change of the rotation speed and the output of the engine 11 when the excavator starts the deep excavation and loading operation from the non-operation state is shown.

In the figure, horsepower W _ L, W _ M, W _ H is the output (horsepower) of the engine 11 corresponding to the predetermined rotation speed NE _ L, NE _ M, NE _ H, respectively. Horsepower W _ H, W _ M corresponds to curves L1 and L2 in fig. 4(P-Q diagram), respectively. The switching between the first half of the excavation operation and the second half of the excavation operation is performed at a timing when the discharge pressure P of the main pump 12 becomes equal to or higher than the predetermined pressure P2.

As shown in fig. 10, when the shovel is not operated, the controller 30 performs the fuel saving control as described above, and thus the set rotation speed NEset of the engine 11 is set to the predetermined rotation speed NE _ L. Therefore, the rotation speed of the engine 11 is substantially maintained at the predetermined rotation speed NE _ L, and the output of the engine 11 is also maintained at relatively low horsepower W _ L corresponding to the predetermined rotation speed NE _ L.

Thereafter, when the operator starts the operation from the non-operation state and shifts to the first half of the excavation operation, the controller 30 sets the set rotation speed NEset of the engine 11 from the predetermined rotation speed NE _ L to the predetermined rotation speed NE _ M as described above. In the first half of the excavation operation, the excavation operation is determined from the processing of steps S102 and 104 in fig. 5, but the discharge pressure P of the main pump 12 does not reach the predetermined pressure P2 or more (no in step S106), and the condition for increasing the set rotation speed NEset of the engine 11 to the predetermined rotation speed NE _ H in the processing in fig. 5 is not satisfied. Therefore, when the first half of the excavation operation is started, the rotation speed of the engine 11 is increased from the predetermined rotation speed NE _ L to the predetermined rotation speed NE _ M and is maintained at the predetermined rotation speed NE _ M. The output of the engine 11 is also increased from the relatively low horsepower W _ L to the intermediate horsepower W _ M corresponding to the predetermined rotational speed NE _ M, and is substantially maintained at the horsepower W _ M.

Thereafter, when the transition is made from the first half of the excavation operation to the second half of the excavation operation, the discharge pressure P of the main pump 12 becomes equal to or higher than the predetermined pressure P2 (yes in step S106), and the condition for increasing the set rotation speed NEset of the engine 11 to the predetermined rotation speed NE _ H is satisfied in the processing of fig. 5. Therefore, when the transition is made to the second half of the excavation operation, the rotation speed of the engine 11 is increased from the predetermined rotation speed NE _ M to the predetermined rotation speed NE _ H and is maintained at the predetermined rotation speed NE _ H. The output of the engine 11 is also increased from the intermediate horsepower W _ M to a relatively high horsepower W _ H corresponding to the predetermined rotational speed NE _ H, and is maintained at substantially the horsepower W _ H.

Thereafter, when the transition from the second half of the excavation operation to the boom raising and turning operation is made, the end of the excavation operation is determined from the processing of step S202 in the processing of fig. 6, and the set rotation speed NEset of the engine 11 is set and changed to the predetermined rotation speed NE _ M. Immediately after that, in the processing of fig. 7 (or fig. 9), since the boom raising operation is determined from the processing of step S302 (or S502) and the state in which the discharge pressure P of the main pump 12 is also equal to or higher than the predetermined pressure P2 is continuously maintained (yes at steps S304 and S504), the set rotation speed NEset of the engine 11 is set to be changed to the predetermined rotation speed NE _ H again. Therefore, when the boom raising operation is transitioned, the rotation speed of the engine 11 is maintained at the predetermined rotation speed NE _ H from the excavation second-half step, and the output of the engine 11 is also maintained at the relatively high horsepower W _ H corresponding to the predetermined rotation speed NE _ H.

Thereafter, as described above, in the boom raising and turning operation, as the boom 4 is raised, the required horsepower decreases, and the operation amount of the boom operation lever 16A also decreases. Therefore, in the second half of the boom raising and turning operation, the set rotation speed NEset of the engine 11 is set to be changed to the predetermined rotation speed NE _ M in the processing of fig. 8. Therefore, in the latter half of the boom raising and turning operation, the rotation speed of the engine 11 is reduced from the predetermined rotation speed NE _ H to the predetermined rotation speed NE _ M and maintained at the predetermined rotation speed NE _ M. The output of the engine 11 is also reduced from the relatively high horsepower W _ H to the intermediate horsepower W _ M, and is maintained at the horsepower W _ M.

Thereafter, during the dumping operation and the boom lowering swing operation, the condition for increasing the set rotation speed NEset to the predetermined rotation speed NE _ H is not satisfied by the processing of fig. 5 and 7 (or fig. 9), and therefore the set rotation speed NEset of the engine 11 is maintained at the predetermined rotation speed NE _ M. Therefore, during the dumping operation and the boom lowering swing operation, the rotation speed of the engine 11 is maintained at the predetermined rotation speed NE _ M, and the output of the engine 11 is also maintained at the intermediate horsepower W _ M corresponding to the predetermined rotation speed NE _ M.

As described above, in the present embodiment, the controller 30 estimates the operation intention of the operator from the operation state of the operation device 16 on the premise of controlling the rotation speed (the predetermined rotation speed NE _ M) at which the engine 11 is maintained at an intermediate level, and increases the rotation speed of the engine 11 to the predetermined rotation speed NE _ H based on the estimation result. Specifically, the controller 30 increases the rotation speed of the engine 11 when determining that the main pump 12 is transitioning from the light load state to the high load state. At this time, as a result of the estimation of the operation intention of the operator, the controller 30 determines that the operation device 16 is operated in a direction in which the work load of the work device increases. In a light load state where the discharge pressure P of the main pump 12 is equal to or lower than the predetermined pressure P1, when the discharge pressure P is equal to or higher than the predetermined pressure P2, which is lower than the predetermined pressure P1, the controller 30 increases the rotation speed of the engine 11 in accordance with the estimation result of the operation intention of the operator. Accordingly, in the light load state, the rotation speed of the engine 11 can be suppressed to the intermediate predetermined rotation speed NE _ M, and therefore, the deterioration of the operability of the excavator due to the excessive output can be suppressed, and the fuel efficiency of the engine 11 can be improved. In addition, in the high load state, the rotation speed of the engine 11 is increased to the relatively high predetermined rotation speed NE _ H according to the estimation result of the operation intention of the operator, and therefore the excavator can be caused to perform an appropriate operation according to the high load state.

While the embodiments for carrying out the present invention have been described in detail, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention described in the claims.

Claims

1. A shovel is provided with:

a driving force source;

a hydraulic pump driven by the driving force source;

a working device driven by the hydraulic actuator;

an operation device that operates the working device; and

a control portion that controls an output of the driving force source,

when the excavation work is performed, the control unit estimates the operation intention of the operator based on the operation state of the operation device, and increases the output of the drive power source when it is determined that the operation state corresponds to the second half of the excavation operation interval based on the estimation result.

2. A shovel is provided with:

a driving force source;

a hydraulic pump driven by the driving force source;

a working device driven by the hydraulic actuator;

an operation device that operates the working device; and

a control portion that controls an output of the driving force source,

the control unit performs an excavation operation including a boom raising step after the excavation soil is accommodated in the working device.

3. The shovel of claim 1 or 2, wherein,

the control unit increases the output of the drive power source when it is determined that the hydraulic pump is transitioning from a light load state to a high load state.

4. The shovel of claim 3,

the control unit determines, as the estimation result, that the operation device is operated in a direction in which a workload of the operation device increases.

5. The shovel of claim 1 or 2, wherein,

in a light load state in which the discharge pressure of the hydraulic pump is equal to or lower than a predetermined 1 st pressure, the control unit increases the output of the drive force source based on the estimation result when the discharge pressure is equal to or higher than a 2 nd pressure lower than the 1 st pressure.

6. The shovel of claim 1 or 2, wherein,

the control portion maintains the output of the raised driving force source after the hydraulic pump transitions to a high load state.

7. The shovel of claim 1 or 2, wherein,

the control unit estimates whether the operation intention corresponds to a rear half of the excavation operation interval or a boom raising process.