JP2023139914A - Construction machine - Google Patents

Abstract

To provide a construction machine which appropriately controls charging rate of a power storage device to suppress deterioration of the power storage device.SOLUTION: In a construction machine with a work device driven by pressure oil to be discharged from a hydraulic pump driven by an electric motor, it comprises: a power storage device which stores power; an external power supply device which supplies power from the outside of the construction machine; and a power converter which performs at least one of a power storage device operation for driving the electric motor by the power stored in the power storage device and an external power supply operation for driving the electric motor by the power to be supplied via the external power supply device, drives the electric motor by the power storage device operation or the external power supply operation when charging rate of the power storage device is a preset value or more, and drives the electric motor only by the external power supply operation when the charging rate of the power storage device is the preset value or less in a state in which supply of external power by the external power supply device is allowed.SELECTED DRAWING: Figure 4

Description

The present invention relates to construction machinery.

In recent years, there has been a call for global countermeasures against natural disasters such as sea level rise and abnormal weather caused by global warming caused by carbon gas emitted by human production activities.

One of the countermeasures is to replace internal combustion engines that generate power by burning fossil fuels with electric motors that use electricity as a power source, thereby reducing carbon dioxide emissions and, in turn, curbing global warming. It's progressing rapidly.

Construction machinery such as crawler excavators and wheel loaders are also required to eliminate internal combustion engines, and as a measure to achieve this, construction machinery products equipped with electric motors as a power source are being introduced into the market.

In conventional construction machinery, a hydraulic pump is driven by the power generated by burning fuel in the engine, and the hydraulic oil discharged from the hydraulic pump is distributed to each hydraulic device by a control valve to drive the vehicle body operation. It has been realized. In such construction machinery, an electric construction machine is one in which the engine that drives the hydraulic pump or each hydraulic device itself is replaced with an electric motor, electric actuator, or the like that is driven by electricity.

Types of electric construction machinery include those that operate using electricity stored in an on-board storage battery by charging in advance, those that operate while being powered by cables from power equipment attached to facilities, and those that operate using both. There are also known ones that correspond to different operating methods.

For example, Patent Document 1 describes a power supply controller that is connected to an AC power source and supplies AC power from the AC power source, a battery that outputs DC power, and an AC-DC converter that converts AC power to DC power. and an inverter unit that converts DC power into AC power having an arbitrary frequency, the AC-DC conversion unit and the inverter unit are connected in series, and the AC power converted by the inverter unit is applied to an AC motor. an electric motor drive device to be supplied; a power supply switching device capable of selecting either connecting the power supply controller to the AC-DC conversion unit or connecting the battery to the inverter unit; and the power supply switching device. A power supply system is disclosed having a system controller for controlling a device.

Japanese Patent Application Publication No. 2007-228715

By the way, while automobiles are used for moving and transporting from one destination to another, construction machines are used for tasks such as digging and shaping soil, and dismantling structures, with no or limited movement. In many cases, it is only within the specified range. In addition, since there are many environments where it is easy to maintain power supply equipment, such as inside a mine shaft such as in tunnel construction or indoor work such as a demolition factory, vehicles that can be operated using power supply cables from external power supply equipment are required. is being operated at a certain rate. However, except when the operation location is fixed to a fixed location, considering the versatility of being able to operate in any work environment, in addition to external power supply operation using a power supply cable, it is also possible to operate the power storage device by supplying power from the power storage device. Many vehicles are compatible with both.

Today, lithium-ion batteries are widely used in portable electronic devices and mobile devices due to their high volumetric density in terms of energy output and energy capacity, as well as the absence of the memory effect caused by recharging that occurs with lead-acid and nickel-metal hydride batteries. It has been widely adopted in large-scale plants such as electric power equipment, and has also begun to be used as a power storage device in construction machinery. However, even in lithium ion batteries, there are deterioration modes such as a decrease in charge/discharge capacity and a decrease in output due to an increase in battery internal resistance, so it is important to operate and store the battery to prevent the deterioration from progressing.

In general, there are two types of deterioration in lithium-ion batteries: cycle deterioration, which increases with the number of charging and discharging cycles, and storage deterioration, which increases over time even if left uncharged and discharged. It is known that there is deterioration. In both types of deterioration, the degree of deterioration increases as the battery temperature increases, and in storage deterioration, the degree of deterioration increases as the SOC increases. In order to operate lithium ion batteries efficiently, it is important to know how to reduce deterioration.

Regarding the installation of the power storage device, in EVs and hybrid vehicles, it has become mainstream to mount the power storage device in the space within the frame under the vehicle seat. As a result, the effects of outside temperature of the vehicle and radiant heat from onboard equipment such as the engine are limited, and the air-conditioning atmosphere in the passenger cabin can be used to cool and heat the power storage device as needed. It can be said that the temperature environment is excellent. On the other hand, construction machinery is mainly mounted inside or outside the upper revolving structure, rather than inside the cab where the operator appears, and is exposed to sunlight, outside air, and radiant heat from the engine and other mounted equipment inside the revolving structure. The major difference is that the temperature environment for the power storage device is poor.

In addition, regarding operation, the usage and operating conditions of construction machinery vary greatly depending on the place and purpose in which it is used, and the construction period is often long, ranging from several months to several years. There are many ways to use it over a long period of time.

In this characteristic way of using construction machinery, conventional construction machines that are compatible with both external power supply operation and power storage device operation have to electrically disconnect the power storage device and bring it to a stopped state when external power supply operation is in operation. After that, it was left in the vehicle and left unattended. For this reason, in conventional vehicles, when operating external power supply, the battery is maintained in the state it was in when the power storage device was electrically disconnected, so if the charging rate of the storage battery at that time is high, that state is when external power supply is operating. It will be maintained.

As mentioned earlier, the degree of storage deterioration of lithium-ion batteries tends to increase as the charging rate increases. During this period, storage deterioration of lithium-ion batteries progresses rapidly.

Although lithium-ion batteries have become commonplace, they are expensive to replace. Therefore, if a degraded lithium ion battery is continued to be used without replacing it, the usability of the construction machinery vehicle will decrease, such as shortening the battery operating time and not being able to produce a large output.

The present invention has been made in view of the above, and an object of the present invention is to provide a construction machine that can suppress deterioration of the power storage device by appropriately controlling the charging rate of the power storage device.

The present application includes a plurality of means for solving the above problems, and one example thereof includes a hydraulic pump driven by an electric motor and a working device driven by pressure oil discharged from the hydraulic pump. In a construction machine, there is provided a power storage device that stores power, an external power supply device that supplies power from outside the construction machine, an operation of the power storage device that drives the electric motor with the power stored in the power storage device, and the external power supply device. The controller includes a power converter that performs at least one of an external power supply operation for driving the electric motor with the power supplied via the power supply device, and the controller is configured to perform external power supply operation by the external power supply device. In a possible state, if the charging rate of the power storage device is equal to or higher than a preset value, the electric motor is driven by the power storage device operation or the external power supply operation, and the charging rate of the power storage device is set in advance. If the electric motor is smaller than the specified value, the electric motor is driven only by the external power supply operation.

According to the present invention, deterioration of the power storage device can be suppressed by appropriately controlling the charging rate of the power storage device.

1 is a side view schematically showing the appearance of an electric crawler excavator that is an example of a construction machine. FIG. 2 is a diagram schematically showing a configuration related to power supply of an electric crawler excavator along with related configurations. FIG. 2 is a diagram schematically showing the configuration of a power storage device. 7 is a flowchart illustrating processing details of mode determination of the power storage device. FIG. 3 is a diagram showing a time chart of operation mode switching control, and shows a case where the charging rate SOC of the power storage device is higher than the SOC reduction determination threshold. FIG. 3 is a diagram showing a time chart of operation mode switching control, and shows a case where the charging rate SOC of the power storage device is lower than the SOC reduction determination threshold. 5 is a flowchart showing the processing details of power storage device maintenance when external power supply is in operation in FIG. 4. FIG. 5 is a time chart of power storage device maintenance control when external power supply is in operation.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In this embodiment, an electric crawler excavator will be described as an example of a construction machine, but the present invention can also be applied to other electric construction machines such as an electric wheel loader.

FIG. 1 is a side view schematically showing the appearance of an electric crawler excavator that is an example of a construction machine according to the present embodiment.

In FIG. 1, an electric crawler excavator 100 (construction machine) includes a self-propelled crawler type undercarriage 109, a swing device 10 provided on the undercarriage 109, and a swing device 10 provided on the undercarriage 109. The rotating upper body 110 is rotatably mounted on the rotating upper body 110, and a working device 100A having a multi-joint structure is provided on the front side of the rotating upper body 110 and performs excavation work, etc.

The working device 100A includes a boom 111, an arm 112, and a bucket 113 as a working tool, which are pin-coupled to each other, a boom cylinder 11 for driving these, an arm cylinder 12, and a bucket cylinder 13 as a working tool actuator. It consists of

Further, on the rear side of the upper part of the upper revolving body 110, a connector 2 is provided for connecting a power cable that supplies power from a commercial power source 1 (described later) to the electric crawler excavator 100.

FIG. 2 is a diagram schematically showing a configuration related to power supply of the electric crawler excavator along with related configurations.

In FIG. 2, the electric crawler excavator 100 is driven by the mechanical power of an electric motor 5, and includes a hydraulic pump 6 that sucks hydraulic oil stored in a hydraulic oil tank 8 and discharges it at a predetermined pressure; Hydraulic oil discharged from the hydraulic actuators 9, swivel 10, boom cylinder 11, arm cylinder 12, and bucket cylinder 13, and the hydraulic pump 6, which are hydraulic actuators, are driven by hydraulic oil. A hydraulic control valve 7 that distributes to the actuators 9 to 13) and a harness connected to a commercial power source 1, which is an external power source of the electric crawler excavator 100, are removably provided. a connector 2 that supplies power from outside, an AC/DC converter 3 that converts the AC power supplied from the commercial power supply 1 through the connector 2 into DC power, and the DC power supplied via the AC/DC converter 3. The charger 14 charges the power storage device 17 with electric power via the charging relay 15, and the DC power supplied from the AC/DC converter 3 or the DC power supplied from the power storage device 17 via the discharge relay 16 is converted into AC power. AC/AC/ Controls the DC converter 3, inverter 4, hydraulic control valve 7, charger 14, charging relay 15, discharge relay 16, cooling device (cooling fan) 18 that cools the power storage device 17, and the power storage device 17, and controls the power storage device 17. A main controller 20 that monitors the thermistor 19 that measures the case temperature (ambient temperature), a switch panel that inputs and outputs (displays) various information and settings to the main controller 20, and inputs such as a keyboard, mouse, and display. It has a console 20a which is an output device. Here, the connector 2 and the AC/DC converter 3 constitute an external power supply device.

In the main controller 20, an operator or the like sets, for example, a power supply mode that specifies the source of power supply to the electric crawler excavator 100 via the console 20a. The power supply mode mainly includes an external power supply operation that instructs the electric motor 5 to be driven by the power supplied from the commercial power supply 1 via the connector 2 and the AC/DC converter 3 (external power supply device). It is possible to enable (ON) or disable (OFF) driving by power supply. Note that when the external power supply operation is disabled (OFF), the power storage device operation is set, which instructs the electric motor 5 to be driven mainly by the electric power stored in the power storage device 17. Furthermore, the external power supply operation may be set by providing a setting switch on the console 20a of the driver's seat of the vehicle, and observing the state of the switch when starting the vehicle to determine whether or not the external power supply operation is set. .

FIG. 3 is a diagram schematically showing the configuration of the power storage device.

In FIG. 3, the power storage device 17 measures a lithium ion secondary battery 30 configured of a plurality of lithium ion batteries (battery cells) connected in series and in parallel, and the charging/discharging current of the lithium ion secondary battery 30. A battery controller (BCU) 32 that performs state determination, state estimation, and control of the lithium ion secondary battery 30 based on the current sensor 31 and the voltage, temperature, and current values of the lithium ion secondary battery 30 measured by the current sensor 31; A relay 33 is connected to the positive electrode side of the charging relay 15 and the discharging relay 16 and connects and disconnects between the positive electrode of the lithium ion secondary battery 30 and the DC side positive electrode of the inverter 4; The relay 34 is connected to the negative electrode side and is configured to connect and disconnect between the negative electrode of the lithium ion secondary battery 30 and the DC side negative electrode of the inverter 4.

The operation of this embodiment configured as above will be explained.

FIG. 4 is a flowchart illustrating the process of determining the mode of the power storage device.

As shown in FIG. 4, when the starting device (starting key) of the electric crawler excavator 100 is turned on (KEY-ON), the main controller 20 first enters the starting state (step S100).

Subsequently, in response to the activation signal from the main controller 20, the battery controller (BCU) 32 is activated and the power storage device 17 is activated (step S110), which performs failure diagnosis, measurement of the open circuit voltage (OCV) of the installed battery, and A cell balancing execution decision is made based on the measured open circuit voltage (OCV). At this time, if the cell balancing implementation determination is determined to be performed, cell balancing is started.

Here, cell balancing is a process of keeping the voltages of a plurality of battery cells mounted on the power storage device 17 within a certain voltage range to make the state and performance of each battery cell uniform. In this embodiment, the battery cell with the lowest voltage is used as a reference, and by connecting a resistor to the battery cell with a higher voltage, the discharge time is controlled according to the voltage difference with the battery cell with the lowest voltage. By doing so, variations in the voltage of each battery cell are adjusted to within a certain voltage difference.

Note that the decision to perform cell balancing may be made in the case where the function is already implemented in the battery controller (BCU) 32 installed in the power storage device 17, or in the case where the function is separately implemented. Here, it is assumed that the battery controller (BCU) 32 is equipped with a cell balancing implementation determination function and a cell balancing function in advance.

When the process of step S110 is completed, it is then determined whether the power supply cable is connected (step S120). The main controller 20 determines whether or not the power supply cable is connected based on the state of the connector 2 .

Here, the determination method will be explained. First, terminals for connection determination (for example, terminal a and terminal b) are provided in the socket on the electric crawler excavator 100 side (vehicle side) and the plug on the commercial power source 1 side (power supply cable side) of the connector 2, respectively. When the connector 2 is in the connected state (that is, when the plug is connected to the socket), terminal a of the socket and terminal a of the plug are connected and conductive, and terminal b of the socket and terminal b of the plug are connected. are connected and conductive.

Here, connect terminal a and terminal b in the plug of connector 2 with wiring to establish electrical continuity, apply an arbitrary voltage to terminal a provided in the socket of connector 2, and connect terminal b to the main controller. Connect to the input terminal of In this state, when a plug is connected to the socket, any voltage applied to terminal a of the socket is input to the main controller 20 via terminal a, terminal b of the plug, and terminal b of the socket, and power is supplied. Cable connection detected. Further, if a plug is not connected to the socket, terminal b of the socket remains open, no voltage is input to the main controller 20, and disconnection of the power supply cable is detected.

In this embodiment, the main controller 20 determines whether or not the power supply cable is connected, but the AC/DC converter 3 makes the determination, and the main controller 20 receives the result information to connect the power supply cable. Judgment and state transition may be managed.

If the determination result in step S120 is NO, that is, if it is determined that the power supply cable is not connected, the vehicle is operated with the power storage device in operation (step S121), and the process ends.

Further, if the determination result in step S120 is YES, that is, if it is determined that the power supply cable is connected, then it is determined whether external power supply operation is set (step S130).

If the determination result in step S130 is NO, that is, if the external power supply operation is set to be disabled (OFF), the power storage device 17 is charged (step S131), and the process ends. The power storage device 17 is charged when the voltage of at least one electronic cell among the plurality of battery cells constituting the power storage device 17 reaches a preset battery cell charging end threshold (voltage V2). Terminate charging. Here, the charging rate may be calculated from the threshold voltage for terminating charging, and the charging rate may be compared with the charging rate of the battery cell with the highest voltage to determine the end of charging.

If the determination result in step S130 is YES, that is, if the external power supply operation setting is valid (ON), then it is determined whether long-term external power supply operation is set (step S140) .

The setting for long-term external power supply operation is set to valid (ON) when the vehicle is planned to be operated with external power supply for a long period of time. In this way, if there is no external power supply for a long period of time, that is, if the power storage device is scheduled to operate from the next day and it is not desired to lower the charging rate of the power storage device 17 in order to save charging time, etc., By setting the long-term external power supply operation setting to ON, the vehicle can be operated by operating the power storage device without performing operation (discharging) to lower the charging rate of the power storage device 17. Note that the setting for long-term external power supply operation can be made by inputting settings to the console 20a or operating a dedicated switch, similar to the setting for external power supply operation, and the main controller 20 can switch to long-term external power supply operation from these settings. The presence or absence of the setting can be determined.

If the determination result in step S140 is YES, then the charging rate SOC of the power storage device 17 calculated from the average voltage value of all the battery cells of the power storage device 17 is equal to or higher than the preset SOC reduction determination threshold V1. It is determined whether or not (step S150).

If the determination result in step S150 is YES, then the vehicle operation is started by operating the power storage device (step S160).

Subsequently, it is determined whether the charging rate SOC of power storage device 17 is smaller than SOC reduction determination threshold V1 (step S170). If the determination result in step S170 is NO, the process returns to step S160.

Further, if the determination result in step S170 is YES, the power storage device 17 is stopped to stop power supply to the electric crawler excavator 100 (step S180), and the vehicle starts moving with external power supply operation (step S190). ), the process ends.

Further, if the determination result in steps S140 and S150 is NO, the process advances to step S180.

Here, the processing in steps S150 to S190 indicated by the broken line in FIG. 4 is referred to as operation mode switching control.

When the processes of steps S121, S131, and S190 are completed and the vehicle KEY is turned off, maintenance control is ended and the vehicle is stopped.

5 and 6 are diagrams showing time charts of operation mode switching control.

5 and 6 show the transition of the state of each device from the vehicle KEY-ON, the comparative determination of the charging rate of the power storage device, and the transition of the vehicle operating mode according to the results over time.

FIG. 5 is a time chart showing a case where the charging rate SOC of the power storage device 17 is higher than the SOC reduction determination threshold V1.

When the vehicle KEY is turned ON, the main controller 20 is activated (ON), and the power storage device is activated (ON) by the activation signal from the main controller 20, and the power storage device 17 is fault diagnosed, OCV measurement (SOC estimation), and cell balancing is performed. Implementation decisions are implemented. After that, the status of the power supply cable connection, external power supply operation setting, and long-term external power supply operation setting is determined, and if all the determination results are Yes, the charging rate of the power storage device (power storage device SOC) and the state set in advance are determined. A comparison is made with the SOC reduction determination threshold V1. Since the power storage device SOC is higher than the SOC reduction determination threshold V1, the vehicle operation mode is changed to power storage device operation, and the vehicle is operated by power supply from the power storage device 17. After that, when the vehicle is operated, the charging rate of the power storage device 17 (power storage device SOC) decreases and falls below the SOC reduction determination threshold V1, the vehicle operation mode is transitioned to external power supply operation, and the external power supply The state transition of the vehicle operation mode in which the vehicle is operated by power supply from the vehicle is shown in chronological order.

FIG. 6 is a time chart showing a case where the charging rate SOC of power storage device 17 is lower than SOC reduction determination threshold V1.

The transition is similar to that shown in FIG. 5 until the charging rate of the power storage device 17 (power storage device SOC) is compared with the preset SOC reduction determination threshold V1, and the power storage device SOC is lower than the SOC reduction determination threshold V1. Since the power consumption is low, the vehicle operation mode is set to external power supply operation, and the state transition of the vehicle operation mode in which the vehicle is operated by external power supply is shown in chronological order.

FIG. 7 is a flowchart showing the processing details of the power storage device maintenance during the external power supply operation in FIG. 4.

As shown in FIG. 7, when power storage device maintenance is started in the state of external power supply operation (see step S190 in FIG. 4), first, an arbitrarily set time has elapsed since the vehicle KEY-ON or the previous determination in step S200. It is determined whether or not more than (for example, 24 hours) has elapsed (step S200). The purpose of the set time here is to accurately measure the open circuit voltage (OCV) of the battery cell. A necessary condition is a resting state (power storage device stopped state) necessary to eliminate polarization inside the battery or increase in internal resistance caused by charging and discharging, and this is determined by the characteristics of the battery cells installed. .

If the determination result in step S200 is NO, the process advances to step S260.

Further, if the determination result in step S200 is YES, power storage device 17 is activated (step S210). At this time, in the power storage device 17, a failure diagnosis, measurement of battery open circuit voltage (OCV), determination of whether to perform cell balancing based on the measured open circuit voltage (OCV), and cell balancing at the time of determination of implementation are performed. Ru.

When the process in step S210 is completed, it is subsequently determined whether supplementary charging is being performed (step S220).

If the determination result in step S220 is NO (auxiliary charging is not being performed), the voltage of the lowest battery cell of the power storage device 17 (hereinafter referred to as the lowest voltage) is lower than the predetermined auxiliary charging start threshold V3. It is determined whether or not the value is also larger (step S221).

If the determination result in step S221 is YES (the lowest voltage is greater than the supplementary charging start threshold V3), the process proceeds to step S260.

Further, if the determination result in step S221 is NO (the lowest voltage is below the supplementary charge start threshold V3), supplementary charge is started (step S222), and the process proceeds to step S260. Here, the current value at the time of supplementary charging may be any value that completes charging within the time set in step S200 (next activation of the power storage device).

Further, if the determination result in step S220 is YES (supplementary charging is being performed), it is determined whether the lowest battery cell voltage (minimum voltage) is greater than a predetermined supplementary charging end threshold V4 ( Step S230).

If the determination result in step S230 is NO (the lowest voltage is below the supplementary charge end threshold V4), supplementary charging is continued (step S231), and the process proceeds to step S260.

Further, if the determination result in step S230 is YES (the lowest voltage is higher than the supplementary charge end threshold V4), supplementary charging is stopped (step S240), and power storage device 17 is stopped (step S250).

Note that the magnitude relationship between the auxiliary charge start threshold V3 and the auxiliary charge end threshold V4 is set so that V3<V4.

Here, in this embodiment, the configuration is such that charging is performed based on the lowest value of the voltage of the battery cell of the power storage device 17, but the configuration may be such that charging is performed based on the charging rate of the power storage device.

When the process in step S250 is completed, it is then determined whether the cooling device 18 is in operation (ON) (step S260).

If the determination result in step S260 is NO (cooling device 18 is stopped), it is determined whether the measured power storage device ambient temperature is smaller than a predetermined power storage device cooling start threshold T1 (step S261 ).

If the determination result in step S261 is YES (less than power storage device cooling start threshold T1), the process proceeds to step S290.

Further, if the determination result in step S261 is NO (power storage device cooling start threshold T1 or more), the cooling device 18 is operated to start cooling (step S262), and the process proceeds to step S290.

Further, if the determination result in step S260 is YES (cooling device 18 is in operation), it is then determined whether the ambient temperature of power storage device 17 is lower than a predetermined power storage device cooling end threshold T2. is determined (step S270).

If the determination result in step S270 is NO (the ambient temperature is equal to or higher than the power storage device cooling end threshold T2), cooling of the power storage device 17 is continued (step S271), and the process proceeds to step S290.

Further, if the determination result in step S270 is YES (the ambient temperature is lower than the power storage device cooling end threshold T2), cooling of the power storage device 17 is finished and the cooling device 18 is stopped (step S280), The process advances to step S290.

Note that the magnitude relationship between the power storage device cooling start threshold T1 and the power storage device cooling end threshold T2 is set so that T1>T2.

Here, the temperature of the power storage device 17 used for the cooling determination is determined by a measured value monitored by a higher-level or other controller than the battery controller (BCU) in the power storage device 17 (such as the temperature of the power storage device casing or the power storage device casing temperature). Any temperature that allows the temperature status of the power storage device to be grasped, such as internal body temperature or specific battery cell temperature, may be used.

When the processes in steps S262, S271, and S280 are completed, the state of the vehicle KEY (starting ON or stopping OFF) is subsequently checked to determine whether or not it is in the KEY-OFF state (step S290).

If the determination result in step S290 is NO (KEY-ON state), the process returns to step S200 and the power storage device maintenance process is repeated.

Further, if the determination result in step S290 is YES (KEY-OFF state), control of external power supply operation (see step S190 in FIG. 4) is ended.

Next, the operation in power storage device maintenance control will be explained.

FIG. 8 is a time chart of power storage device maintenance control during external power supply operation.

In FIG. 8, when the vehicle KEY is turned ON at time t0, the main controller 20 is activated and determines whether 24 hours have elapsed since the vehicle KEY was turned ON or the last confirmation (steps in FIG. 7). (See S200).

At time t1, since it has just been started, the power storage device is started (see step S210 in FIG. 7), and then it is determined whether supplementary charging is being performed (see step S220 in FIG. 7). Since auxiliary charging has not been performed here, it is subsequently determined whether the lowest battery cell voltage of power storage device 17 is greater than auxiliary charging start threshold V3 (see step S221 in FIG. 7). Here, since the lowest battery cell voltage of the power storage device is smaller than the supplementary charge start threshold V3, supplementary charge is started (see step S222 in FIG. 7). As a result, the lowest battery cell voltage of power storage device 17 starts to rise.

At time t2, it is determined whether the lowest battery cell voltage is greater than the supplementary charge end threshold V4 (see step S230 in FIG. 7). Here, since the lowest battery cell voltage is higher than the auxiliary charge end threshold V4, the auxiliary charge is ended (see step S240 in FIG. 7), and then the power storage device is stopped (see step S250 in FIG. 7).

At time t3, the operating status of the cooling device 18 is confirmed (see step S260 in FIG. 7). Here, since the cooling device 18 is stopped, it is subsequently determined whether the ambient temperature of the power storage device 17 is lower than a predetermined power storage device cooling start threshold T1 (see step S261 in FIG. 7). ). Here, since the ambient temperature of power storage device 17 is higher than power storage device cooling start threshold T1, the cooling device is operated (step S262 in FIG. 7). As a result, the ambient temperature of the power storage device begins to decrease.

At time t4, it is determined whether the ambient temperature of the power storage device is lower than the power storage device cooling end threshold T2 (see step S270 in FIG. 7). Here, since the ambient temperature of power storage device 17 is lower than power storage device cooling end threshold T2, cooling device 18 is stopped (see step S280 in FIG. 7).

As described above, when the vehicle is operating with external power supply for a long period of time, by operating the vehicle with the charging rate of the power storage device at a low state, it is possible to maintain the charging rate of the power storage device at a high state during operation. As a result, storage deterioration of the power storage device can be reduced.

In addition, it is even more difficult to operate in high-temperature environments such as under the scorching sun in summer, indoors without air conditioning equipment, or in high-temperature environments caused by radiant heat from other on-board equipment, which is a characteristic of how construction machinery is used. Although there is a concern that storage deterioration will increase, in this embodiment, when the power storage device is not in use (external power supply is operating) and the ambient temperature of the power storage device is high (the power storage device is exposed to high temperature), In addition, by operating the cooling mechanism of the vehicle to lower the ambient temperature of the power storage device, the influence of temperature on storage deterioration of the power storage device can be reduced.

In addition, if the vehicle continues to operate with external power supply for a long period of time, the power storage device will not be started during that time, so it is necessary to take precautions against self-discharge of the battery cells (adjustment of cell voltage variations, prevention of over-discharge, etc.) during startup. Since supplementary charging cannot be performed, it is necessary to periodically start the vehicle and perform maintenance work on the power storage device, which poses problems in terms of maintainability. However, in this embodiment, external power supply is not possible. During operation (when the power storage device is stopped), maintenance is improved by automatically determining and implementing cell balancing adjustments due to natural discharge of the power storage device battery cells, and automatically monitoring and supplementary charging for voltage drops. , and it is possible to prevent the risk of the power storage device becoming unusable due to forgetting the same task.

<Additional notes>
Note that the present invention is not limited to the above-described embodiments, and includes various modifications and combinations within the scope of the invention. Furthermore, the present invention is not limited to having all the configurations described in the above embodiments, but also includes configurations in which some of the configurations are deleted. Moreover, each of the above-mentioned configurations, functions, etc. may be realized in part or in whole by, for example, designing an integrated circuit. Furthermore, each of the above configurations, functions, etc. may be realized by software by a processor interpreting and executing a program for realizing each function.

1... Commercial power supply, 2... Connector, 3... AC/DC converter, 4... Inverter, 5... Electric motor, 6... Hydraulic pump, 7... Hydraulic control valve, 8... Hydraulic oil tank, 9... Hydraulic motor for travel, 10 ...Swivel device, 11...Hydraulic actuator, 11...Boom cylinder, 12...Arm cylinder, 13...Bucket cylinder, 14...Charger, 15...Charging relay, 16...Discharge relay, 17...Power storage device, 18...Cooling device (cooling) fan), 19... thermistor, 20... main controller, 20a... console, 21... current sensor, 30... lithium ion secondary battery, 31... current sensor, 32... battery controller (BCU), 33... relay, 34... relay, DESCRIPTION OF SYMBOLS 100... Electric crawler excavator, 100A... Working device, 109... Lower traveling body, 110... Upper rotating body, 111... Boom, 112... Arm, 113... Bucket

Claims (6)

a hydraulic pump driven by an electric motor;
A construction machine equipped with a working device driven by pressure oil discharged from the hydraulic pump,
A power storage device that stores electricity;
an external power supply device that supplies power from outside the construction machine;
a power converter that performs at least one of operating a power storage device to drive the electric motor using power stored in the power storage device and operating an external power supply to drive the electric motor using power supplied via the external power supply device; ,
Equipped with a controller,
The controller includes:
In a state where external power can be supplied by the external power supply device,
If the charging rate of the power storage device is equal to or higher than a preset value, driving the electric motor by operating the power storage device or operating the external power supply;
A construction machine characterized in that when the charging rate of the power storage device is smaller than a preset value, the electric motor is driven only by the external power supply operation. The construction machine according to claim 1,
comprising a setting device for presetting the driving method of the electric motor to either the power storage device operation or the external power supply operation,
The controller includes:
In the case where the external power supply operation is set in advance, if the charging rate of the power storage device is equal to or higher than the preset value, the power storage device is operated before driving the electric motor in the external power supply operation. A construction machine characterized in that the charging rate of the power storage device is lowered to a preset value or less by driving the electric motor, and then the electric motor is driven by external power supply operation. The construction machine according to claim 1,
The controller includes:
When the electric motor is driven by the external power supply operation, if the voltage of at least one battery cell among the plurality of battery cells constituting the power storage device falls below a preset supplementary charge determination threshold, the power storage device A construction machine characterized in that the power storage device is charged until a battery cell voltage reaches a preset supplementary charge end threshold. The construction machine according to claim 1,
The controller includes:
When the electric motor is driven by the external power supply operation, when the charging rate of the power storage device decreases below a preset supplementary charging determination threshold, the charging rate of the power storage device becomes larger than a preset supplementary charging end threshold. A construction machine characterized in that the power storage device is charged until the power storage device is charged. The construction machine according to claim 1,
The controller includes:
When the electric motor is driven by the external power supply operation, if the voltage difference between the plurality of battery cells constituting the power storage device increases to a preset threshold value or more, each battery cell is individually discharged, and the plurality of battery cells are individually discharged. A construction machine characterized by performing balancing so that a voltage difference between battery cells is reduced to a voltage difference smaller than a preset value. The construction machine according to claim 1,
The controller includes:
When the electric motor is driven by the external power supply operation, the ambient temperature, the casing temperature, the internal casing temperature of the power storage device, or the temperature of the battery cells constituting the power storage device are equal to or higher than a preset cooling start threshold. temperature, the cooling device is operated to cool the power storage device until the ambient temperature, casing temperature, casing internal temperature, or temperature of the battery cell becomes a temperature equal to or lower than a preset cooling end threshold. A construction machine characterized by:

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