WO2022149586A1

WO2022149586A1 - Construction machine

Info

Publication number: WO2022149586A1
Application number: PCT/JP2022/000155
Authority: WO
Inventors: 明渡辺; 泰典太田; 勇佑今井; 春樹杉山; 学矢野
Original assignee: 日立建機株式会社
Priority date: 2021-01-06
Filing date: 2022-01-06
Publication date: 2022-07-14
Also published as: JPWO2022149586A1; JP7429309B2

Abstract

A hydraulic shovel 1 comprises a main pump 4 that is driven by an engine 2, an operation device 12 that operates a hydraulic actuator, a generator 16 that receives power from the engine 2 to generate electric power, a hybrid battery 15 that stores the electric power generated by the generator 16, an electric motor 3 that receives electric power supply from the hybrid battery 15 to assist the driving of the engine 2, and a vehicle body controller 13. When the vehicle body controller 13 determines that the engine speed needs to be increased in order to reach a required engine speed, the vehicle body controller 13 stops the generator 16 or reduces the amount of electric power generated by the generator 16, and outputs electric power from the hybrid battery 15.

Description

Construction machinery

The present invention relates to construction machinery.
This application claims priority based on Japanese Patent Application No. 2021-000692 filed on January 6, 2021, and the contents thereof are incorporated herein by reference.

In recent years, electrified construction machines have been developed for the purpose of considering the environment and improving fuel efficiency, and hybrid hydraulic excavators that drive the main pump with two types of power, an engine and an electric motor, are attracting particular attention.

As a hybrid hydraulic excavator, for example, as described in Patent Document 1, an engine, a generator driven by the engine, a battery charged by the generator, and assisted in driving the engine while being driven by the electric power of the battery. It is known to be equipped with an electric motor. In such a hybrid hydraulic excavator, electric power is output from the battery when the controller is started or the engine is driven, and the generator receives the power of the engine to generate electricity and charge the battery.

Japanese Patent No. 5085734

However, the hybrid hydraulic excavator described in Patent Document 1 has the following problems. In other words, if the generator assists to accelerate the engine with the electric motor while the generator continues to generate electricity, the electric motor will return the power of the engine converted to electricity by the electric motor. , The efficiency of the electric motor and the generator will be lost, and the fuel consumption of the hydraulic excavator will increase. In addition, since the generator applies braking torque to the engine when generating electricity, it hinders the attempt to increase the engine speed. As a result, the responsiveness when increasing the engine speed is deteriorated, and the operational responsiveness of the hydraulic excavator is impaired.

An object of the present invention is to provide a construction machine capable of reducing fuel consumption and improving operational responsiveness.

The construction machine according to the present invention includes an engine, a variable displacement hydraulic pump driven by the engine, a hydraulic actuator driven by pressure oil supplied from the hydraulic pump, and an operating device for operating the hydraulic actuator. A generator that receives power from the engine to generate power, a power storage device that stores the power generated by the generator, an engine control dial that sets a target engine rotation speed of the engine, and controls the generator. A controller is provided, and the controller calculates a required hydraulic output value based on the operation amount of the operating device and a target engine rotation speed set in the engine control dial, and the controller calculates a required hydraulic output value based on the calculated required hydraulic output value. When the required engine rotation speed is obtained and it is determined that the engine rotation speed needs to be increased in order to reach the required required engine rotation speed, the generator is stopped or the power generation amount of the generator is reduced to store the electricity. It is characterized by outputting power from the device.

In the construction machine according to the present invention, when the controller determines that it is necessary to increase the engine rotation speed in order to reach the required required engine rotation speed, the generator is stopped or the generator power generation amount is reduced to store electricity. Since the power is output from the device, the fuel consumption of the construction machine can be reduced. Moreover, since the responsiveness when increasing the engine speed is improved, the operation responsiveness can be improved.

According to the present invention, fuel consumption can be reduced and operational responsiveness can be improved.

It is a side view which shows the hydraulic excavator which concerns on embodiment. It is a block diagram which shows the hydraulic excavator which concerns on embodiment. It is a figure for demonstrating the flow of electric power before starting an engine. It is a figure for demonstrating the flow of electric power after starting an engine (the lock lever is locked state). It is a figure for demonstrating the flow of electric power at the time of engine acceleration. It is a fuel consumption diagram of an engine. It is a fuel consumption diagram of an engine. It is a flowchart which shows the control process of the body controller of a hydraulic excavator.

Hereinafter, embodiments of the construction machine according to the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. Further, in the following, an example of a hydraulic excavator will be described as a construction machine, but the present invention is not limited to the hydraulic excavator and is also applied to construction machines other than the hydraulic excavator.

FIG. 1 is a side view showing a hydraulic excavator according to an embodiment, and FIG. 2 is a configuration diagram showing a hydraulic excavator according to an embodiment. The hydraulic excavator 1 according to the present embodiment is a hybrid hydraulic excavator in which a variable displacement main pump (hydraulic pump) 4 is driven by an engine 2 and an electric motor 3 to control an engine variable speed. In the hydraulic excavator 1, the pressure oil supplied from the main pump 4 is distributed by the control valve 5, and the distributed pressure oil is distributed to a plurality of hydraulic actuators (bucket cylinder 6, arm cylinder 7, boom cylinder 8, swivel motor 9, traveling). By being supplied to each of the motors 10), an excavation operation, a turning operation, and a traveling operation are performed.

The control valve 5 is a flow rate control valve that controls the flow rate of the pressure oil supplied from the main pump 4 to each hydraulic actuator. The bucket cylinder 6 is a hydraulic actuator for driving the bucket 26, and is driven by the pressure oil supplied from the main pump 4. The arm cylinder 7 is a hydraulic actuator for driving the arm 27, and is driven by the pressure oil supplied from the main pump 4. The boom cylinder 8 is a hydraulic actuator for driving the boom 28, and is driven by the pressure oil supplied from the main pump 4.

The swivel motor 9 is a hydraulic actuator for swiveling the swivel body 29 with respect to the traveling body 30, and is driven by the pressure oil supplied from the main pump 4. The traveling motor 10 is a hydraulic actuator for moving the traveling body 30 forward or backward, and is driven by the pressure oil supplied from the main pump 4. The hydraulic actuator, the main pump 4, and the control valve 5 are each controlled by the vehicle body controller 13, which will be described later.

Further, the hydraulic excavator 1 includes a vehicle body controller 13 that monitors and controls the state of the vehicle body, operations of each electric device, and the like, and an ECU (engine control unit) 22 that monitors and controls the state of the engine 2. There is. The vehicle body controller 13 and the ECU 22 are electrically connected to the lead battery 14 by the first electric system 17. Therefore, the vehicle body controller 13 and the ECU 22 can operate by receiving the electric power supply from the lead battery 14.

Further, the hydraulic excavator 1 is equipped with a cabin 11 on which the operator is boarded. The cabin 11 is provided with an operating device 12, a lock lever 23, and an engine control dial 24. The operating device 12 is a device for the operator to operate each hydraulic actuator, and is configured by, for example, an operating lever. When the operating lever is operated by the operator, the control valve 5 is driven, whereby the pressure oil in the bucket cylinder 6, the arm cylinder 7, the boom cylinder 8, the swivel motor 9, and the traveling motor 10 is controlled, so that the bucket 26 is controlled. , Arm 27, boom 28, swivel body 29 and traveling body 30, respectively. As a result, the excavation operation, the turning operation, and the traveling operation of the hydraulic excavator 1 are realized.

The lock lever 23 is a device having a function of suppressing the operation of the hydraulic excavator 1 by locking (prohibiting) the operation by the operating device 12 when the operator does not operate the hydraulic excavator 1 or leaves the cabin 11. The engine control dial 24 is a device for setting a target rotation speed of the engine 2.

The electric motor 3 receives electric power from the hybrid battery 15 which is a power storage device, and assists the drive of the engine 2. As shown in FIG. 2, the electric motor 3 is coaxially connected to the engine 2 and the main pump 4. By doing so, the main pump 4 is driven by two types of power, such as the engine 2 and the electric motor 3. The electric motor 3 is controlled by the vehicle body controller 13 via the PCU (power control unit) 31.

Further, the hydraulic excavator 1 further includes a generator 16 that receives power from the engine 2 to generate electricity and outputs electric power to an electric device such as an air conditioner compressor 20 to charge the hybrid battery 15. The generator 16 is a motor that operates by converting direct current into three-phase alternating current with, for example, a PCU (inverter) 25 and controlling the three-phase alternating current, and is controlled by a vehicle body controller 13 via the PCU 25. The generator 16 is electrically connected to the hybrid battery 15, the air conditioner compressor 20, and the engine fan 21 via a second electric system 18.

Further, a DC / DC converter 19 is provided between the first electric system 17 and the second electric system 18. The DC / DC converter 19 performs voltage conversion from the second electric system 18 to the first electric system 17 and outputs electric power to the first electric system 17. By doing so, the electric power generated by the generator 16 is voltage-converted to the DC / DC converter 19 and then output to the first electric system 17. Therefore, the lead battery 14 is charged and the electric power is supplied to the vehicle body controller 13 and the ECU 22.

The vehicle body controller 13 corresponds to the "controller" described in the claim range, for example, a CPU (Central Processing Unit) that executes an operation and a ROM (secondary storage device) that stores a program for the operation. It is composed of a microcomputer consisting of a combination of a Ready Only Memory) and a RAM (Random Access Memory) as a temporary storage device for storing the progress of operations and temporary control variables, and by executing the stored program. It monitors and controls the condition of the vehicle body and controls the operation of each electric device.

For example, the vehicle body controller 13 determines the discharge amount of the pressure oil of the main pump 4 and the distribution destination of the control valve 5 based on the operation amount of the operation device 12. Further, the vehicle body controller 13 calculates the required hydraulic pressure output value of the engine 2 based on the operation amount of the operating device 12 and the target engine rotation speed set in the engine control dial 24, and is based on the calculated required hydraulic pressure output value. Find the required engine speed. Further, the vehicle body controller 13 needs to determine whether or not it is necessary to increase the rotation speed of the engine 2 (in other words, accelerate the engine 2) in order to reach the required required engine rotation speed, and increase the rotation speed. When it is determined that there is, the generator 16 is stopped or the amount of power generated by the generator 16 is reduced, and power is output from the hybrid battery 15 to an electric device such as an electric motor 3.

Hereinafter, the flow of electric power from before the engine is started to after the engine is started will be described with reference to FIGS. 3 to 5.

First, the flow of electric power before starting the engine will be explained based on FIG. When the hydraulic excavator 1 receives the start command, the lead battery 14 is connected to the vehicle body controller 13, the ECU 22, and the first electric system 17 via the first electric system 17, as shown by the arrow F1 in FIG. Outputs power (ie, power supply) to other connected electrical equipment (not shown). At this time, as shown by the arrow F2 in FIG. 3, the hybrid battery 15 outputs electric power to the air conditioner compressor 20, the engine fan 21, the

PCU

25, 31, etc. via the second electric system 18 (that is, the electric power). supply).

After that, when the hydraulic excavator 1 receives the command to start the engine, the vehicle body controller 13 operates the electric motor 3 via the PCU 31. At this time, the electric motor 3 receives electric power from the hybrid battery 15 and rotates to start the engine 2.

Next, the flow of electric power after the engine is started (the lock lever is locked) will be described with reference to FIG. After the engine is started, the generator 16 generates electricity by receiving the power of the engine 2. The generated power is voltage-converted by the DC / DC converter 19 and then output to the lead battery 14, the vehicle body controller 13, the ECU 22 and the like via the first electric system 17 (see the arrow F3 in FIG. 4). .. The lead battery 14 receives the electric power output from the generator 16 and charges the lead battery 14.

At this time, the electric power generated by the generator 16 is output to the air conditioner compressor 20, the engine fan 21, and the hybrid battery 15 via the second electric system 18 (see the arrow F4 in FIG. 4). The hybrid battery 15 receives the electric power output from the generator 16 and charges the battery. Then, when the engine 2 is operating, the generator 16 basically continues to generate electricity.

When the lock lever 23 is not in the locked state and the hydraulic excavator 1 is not immediately operated, the engine 2 is as efficient as possible regardless of the target engine speed set in the engine control dial 24. The idling operation is performed at a certain number of revolutions. At this time, the vehicle body controller 13 determines the number of revolutions to be actually operated so that the efficiency of the engine 2 is as good as possible, based on the isofuel consumption diagram (see FIG. 6) of the engine stored inside.

FIG. 6 schematically shows an isofuel consumption diagram showing the fuel consumption of the engine 2 by the torque on the vertical axis and the rotation speed on the horizontal axis. In FIG. 6, the iso-output line is shown by a broken line, and the iso-fuel consumption line is shown by a solid line. The vehicle body controller 13 uses an efficiency map based on this isofuel consumption diagram. Further, in the present embodiment, since the engine 2 is directly connected to the shaft of the main pump 4, the rotation speeds of both are substantially the same. Therefore, by adding the torque of the electric motor 3 to the engine torque shown on the vertical axis, the torque becomes substantially the same as the torque of the main pump 4. Further, the tilt angle of the main pump 4 at that time can be obtained from the torque of the main pump 4.

In FIG. 6, the required output of the engine 2 during idling operation is shown by a straight line L1. Then, looking for the most efficient engine speed on the straight line L1, it is when the engine speed is 1200 rpm, which is close to the fuel consumption line with less fuel consumption. Therefore, the vehicle body controller 13 can improve the efficiency of the engine 2 by operating the engine 2 at a rotation speed of 1200 rpm regardless of the setting of the engine control dial 24 in idling operation.

Next, the flow of electric power during engine acceleration will be described with reference to FIG. When the operator of the hydraulic excavator 1 operates the operation device 12, the vehicle body controller 13 acquires the operation amount of the operation device 12 via the operation amount detection sensor (not shown), and according to the operation content of the operation device 12. While controlling the engine 2 and the main pump 4, the control valve 5 is controlled so as to produce the required hydraulic output, and the hydraulic output is distributed to each hydraulic actuator.

At this time, the vehicle body controller 13 calculates the required hydraulic pressure output value of the engine 2 based on the operation amount of the operating device 12 and the target engine rotation speed set in the engine control dial 24. Further, the vehicle body controller 13 uses the above-mentioned efficiency map of the engine 2 based on the calculated required hydraulic pressure output value to obtain the highest efficiency of the engine 2 (that is, the required engine rotation speed) and the main pump 4. The combination with the tilt angle is obtained, and the main pump 4, the engine 2, the electric motor 3 and the generator 16 are controlled based on the obtained results.

Further, in the present embodiment, when the engine 2 is accelerated by increasing the number of revolutions, the vehicle body controller 13 assists the acceleration of the engine 2 with the electric motor 3 while stopping the power generation of the generator 16 or reducing the amount of power generation. The electric motor 3 and the generator 16 are controlled so as to reduce the number. While the generator 16 is stopped or the amount of electric power is reduced, the vehicle body controller 13 uses the hybrid battery 15 to output electric power to the PCU 31, the electric motor 3, the engine fan 21, and the air conditioner compressor 20, and further DC / DC. Power is output to the lead battery 14, the vehicle body controller 13, the ECU 22 and the like via the converter 19 and the first electric system 17 (see the arrow F5 in FIG. 5). Then, when the acceleration of the engine 2 is completed and the rotation speed of the engine 2 becomes stable, the generator 16 starts power generation again.

Hereinafter, the control process of the vehicle body controller 13 will be described with reference to FIG.

First, in step S11, the vehicle body controller 13 calculates the required hydraulic pressure output value. At this time, as described above, the vehicle body controller 13 calculates the required hydraulic pressure output value based on the operation amount of the operating device 12 and the target engine rotation speed set in the engine control dial 24.

In step S12 following step S11, the vehicle body controller 13 uses the above-mentioned efficiency map of the engine 2 based on the calculated required hydraulic pressure output value to obtain the most efficient rotation speed of the engine 2 (that is, the required engine rotation speed). And the combination with the tilt angle of the main pump 4 is obtained. Specifically, for example, in the case of the 95 kW iso-output line L2 shown in FIG. 7, since the required hydraulic pressure output value becomes the required engine output value, the vehicle body controller 13 has the highest efficiency of the engine 2 on the iso-output line L2. Since the rotation speed is often accelerated at a point and when the hydraulic output becomes high, the vehicle body controller 13 selects a point where the efficiency of the engine 2 is high and the rotation speed is high. As a result, the required engine speed and the required engine torque are obtained. Further, the vehicle body controller 13 obtains a tilt angle based on the obtained required engine torque.

In step S13 following step S12, the vehicle body controller 13 determines whether or not the required engine rotation speed is larger than the sum of the current engine rotation speed and the default value α. The default value α is set in consideration of an error in determining that the engine speed is stable. The current engine speed is detected by, for example, a speed detection sensor (not shown) and output to the vehicle body controller 13.

Then, when it is determined that the required engine rotation speed is equal to or less than the sum of the current engine rotation speed and the default value α, the control process proceeds to step S14. In step S14, the vehicle body controller 13 controls the generator 16 so as to start power generation.

On the other hand, if it is determined that the required engine speed is larger than the sum of the current engine speed and the default value α, the control process proceeds to step S15. In step S15, the vehicle body controller 13 determines whether or not the remaining battery level of the hybrid battery 15 is equal to or greater than the first threshold value. The first threshold value here means the capacity at which power generation can be stopped, and even if the generator 16 is stopped, only the remaining amount of the hybrid battery 15 is enough for the PCU 31, the electric motor 3, the engine fan 21, the air conditioner compressor 20, and the vehicle body controller 13. And the capacity that can guarantee the power supply to the ECU 22. The remaining battery level of the hybrid battery 15 can be obtained, for example, via the battery management unit inside the hybrid battery 15.

Then, when it is determined that the remaining battery level of the hybrid battery 15 is equal to or higher than the first threshold value, the control process proceeds to step S16. In step S16, the vehicle body controller 13 stops the generator 16. On the other hand, if it is determined that the remaining battery level of the hybrid battery 15 is smaller than the first threshold value, the control process proceeds to step S17.

In step S17, the vehicle body controller 13 determines whether or not the remaining battery level of the hybrid battery 15 is equal to or greater than the second threshold value. The second threshold value here means a capacity that can maintain the operation, and is set smaller than the first threshold value. The operation-sustainable capacity is a capacity that can maintain the operation of the PCU 31, the electric motor 3, the engine fan 21, the air conditioner compressor 20, the vehicle body controller 13, and the ECU 22 even if the amount of power generated by the generator is reduced. The capacity that can maintain this operation is determined by the difference between the required engine speed and the current engine speed, and the power generation stop time (or the amount of power generation is reduced) is determined. It is a capacity that can maintain the operation of the air conditioner compressor 20, the vehicle body controller 13, and the ECU 22, and is determined based on the results of experiments.

Then, when it is determined that the remaining battery level of the hybrid battery 15 is smaller than the second threshold value, the control process proceeds to step S14, and the power generation of the generator 16 is started. On the other hand, when it is determined that the remaining battery level of the hybrid battery 15 is equal to or higher than the second threshold value, the control process proceeds to step S18. In step S18, the vehicle body controller 13 controls the generator 16 so as to reduce the amount of power generated by the generator 16.

As a method of reducing the amount of power generation, if the generator is composed of a PCU and a motor, reducing the brake torque can be mentioned. In addition, as a method of stopping the generator to eliminate the amount of power generation, when the generator is composed of a PCU and a motor, eliminating the brake torque (so-called free run) is mentioned, and the generator is an alternator. In some cases, the power connection of the engine may be disconnected by an electromagnetic clutch or the like.

In step S19 following step S14, step S16 or step S18, the vehicle body controller 13 generates a command for the engine 2, the main pump 4 and the electric motor 3, and the generated command is used for the engine 2, the main pump 4 and the electric motor 3. Output to each. This ends a series of control processes.

In the hydraulic excavator 1 according to the present embodiment, when the vehicle body controller 13 determines that it is necessary to increase the rotation speed of the engine 2 in order to reach the required required engine rotation speed, the generator 16 is stopped or the generator 16 is generated. The amount of power generated by the hybrid battery 15 is reduced and power is output from the hybrid battery 15. That is, when it is determined that it is necessary to increase the rotation speed to accelerate the engine 2, the vehicle body controller 13 stops the power generation of the generator 16 or reduces the power generation amount of the generator 16. As a result, the engine power converted into electricity by the generator as in the conventional case can be prevented from being returned to the engine power by the electric motor, so that the loss of the electric motor 3 can be reduced and the hydraulic excavator can be used. The fuel consumption of 1 can be reduced.

Further, by stopping the power generation of the generator 16 or reducing the amount of power generated by the generator 16, the braking torque to the engine 2 due to the power generation can be reduced, so that the responsiveness when increasing the rotation speed of the engine 2 can be reduced. Will improve. As a result, the operation responsiveness can be improved.

In the present embodiment, it has been described that the generator 16 is a motor that operates by converting direct current into three-phase alternating current with a PCU (inverter) and controlling three-phase alternating current. For example, the engine 2 and an electromagnetic clutch are described. It may be composed of an alternator connected via the above, and in this case, the power generation can be stopped by disengaging the electromagnetic clutch.

Further, in the present embodiment, the configuration in which the electric motor 3 assists when accelerating the rotation speed of the engine 2 has been described, but even if the hydraulic excavator has a configuration without the electric motor 3, the rotation speed of the engine 2 is accelerated. By stopping the generator 16 at that time, the braking torque given to the engine 2 by the generator 16 is eliminated, so that the acceleration responsiveness of the rotation speed of the engine 2 is improved, and the effect of improving the operation responsiveness is expected. can.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs are designed without departing from the spirit of the present invention described in the claims. You can make changes.

1 Hydraulic excavator 2 Engine 3 Electric motor 4 Main pump (hydraulic pump)
5 Control valve 6 Bucket cylinder 7 Arm cylinder 8 Boom cylinder 9 Swing motor 10 Travel motor 11 Cabin 12 Operating device 13 Body controller 14 Lead battery 15 Hybrid battery 16 Generator 17 First electric system 18 Second electric system 19 DC / DC converter 20 Air conditioner compressor 21 Engine fan 22 ECU
23 Lock lever 24

Engine control dial

25, 31 PCU
26 Bucket 27 Arm 28 Boom 29 Swing body 30 Traveling body

Claims

With the engine
A variable displacement hydraulic pump driven by the engine,
A hydraulic actuator driven by the pressure oil supplied from the hydraulic pump, and
An operating device that operates the hydraulic actuator and
A generator that receives power from the engine to generate electricity,
A power storage device that stores the power generated by the generator,
The engine control dial that sets the target engine speed of the engine,
The controller that controls the generator and
Equipped with
The controller
The required hydraulic pressure output value is calculated based on the operation amount of the operating device and the target engine rotation speed set on the engine control dial, and the required engine rotation speed is obtained based on the calculated required hydraulic pressure output value. When it is determined that it is necessary to increase the engine speed in order to reach the engine speed, the generator is stopped or the amount of power generated by the generator is reduced to output power from the power storage device. Construction machinery.
Further equipped with an electric motor that receives electric power from the power storage device and assists in driving the engine.
When the controller determines that it is necessary to increase the rotation speed of the engine, the generator is stopped or the amount of power generated by the generator is reduced to output power from the power storage device to the electric motor. Construction machinery described in.
The first aspect of the present invention is to control the generator to stop when the remaining battery level of the power storage device is equal to or higher than the first threshold value when it is determined that the engine rotation speed needs to be increased. Described construction machinery.
When it is determined that it is necessary to increase the rotation speed of the engine, the controller determines that the remaining battery level of the power storage device is smaller than the first threshold value and equal to or higher than the second threshold value, and the power generation amount of the generator is increased. The construction machine according to claim 3, which is controlled to reduce the amount of power generation.