Method for controlling electric working machine

Abstract

To enable battery maintenance to be performed at an appropriate time.SOLUTION: A method for controlling an electric working machine including a battery that is charged with power from an external power source and supplies power to an electric motor includes storing and outputting an operating time of the battery.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control method for an electric working machine. [Background technology]

[0002] Conventionally, a maintenance timing notification device for a construction machine has been disclosed. For example, the notification device of Patent Document 1 is configured to notify the driver or manager that the actual operation time of the engine has reached the maintenance timing for each maintenance item. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-262806 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, in addition to hydraulic excavators that use engine power to drive hydraulic actuators, hydraulic excavators that use battery power to drive hydraulic actuators (electric excavators) have also come into widespread use. In electric excavators, an electric motor is driven by battery power to rotate a hydraulic pump, which supplies pressure oil to the hydraulic actuator to drive it.

[0005] In an electric excavator, since the hydraulic pump is driven by the electric motor as described above, the operation time of the electric motor can be regarded as the operation time of the hydraulic pump. Therefore, by managing the operation time of the electric motor, the timing of maintenance of the hydraulic system including the hydraulic pump can be managed, and thus maintenance of the hydraulic system can be performed at an appropriate timing.

[0006] On the other hand, the battery deteriorates not only while it is discharging, i.e. while the electric motor is operating, but also while it is charging. For this reason, if the timing of maintenance for the battery is managed based on the operating time of the electric motor, as is the case with hydraulic systems, it is not possible to perform maintenance at an appropriate time that takes into account the deterioration of the battery while it is charging.

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to provide a control method for an electric working machine that is capable of performing battery maintenance at an appropriate timing. [Means for solving the problem]

[0008] A control method for an electric work machine according to one aspect of the present invention is a control method for a work machine that has a battery that is charged with power from an external power source and supplies power to an electric motor, the method including storing and outputting the operating time of the battery. Effect of the Invention

[0009] According to the above configuration, battery maintenance can be performed at an appropriate time. [Brief description of the drawings]

[0010] [Figure 1] 1 is a side view showing a schematic configuration of a hydraulic excavator, which is an example of an electric working machine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a schematic configuration of a control system and a hydraulic system of the hydraulic excavator. [Diagram 3] FIG. 4 is an explanatory diagram showing an example of a display on a display unit of the hydraulic excavator. [Figure 4] 11 is an explanatory diagram showing another example of the display on the display unit. FIG. [Diagram 5] 5A and 5B are explanatory diagrams illustrating an example of a current-carrying state of a relay, an operating state of an electric motor, an operating state of a charger, and an operating state of a battery in a charging mode and a battery mode, respectively. [Figure 6] 5A to 5C are explanatory diagrams each showing an example of a current-carrying state of a relay, an operating state of an electric motor, an operating state of a charger, and an operating state of a battery in a charging mode, a battery mode, and a combined power source mode, respectively; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0012] [1. Electric working machines] 1 is a side view showing a schematic configuration of a hydraulic excavator 1 constituting an electric shovel which is an example of an electric working machine according to the present embodiment. The hydraulic excavator 1 includes a lower traveling structure 2, a working machine 3, and an upper rotating structure 4.

[0013] Here, directions in FIG. 1 are defined as follows. First, the direction in which the lower traveling body 2 moves straight is the fore-aft direction, one side of which is the "front" and the other side is the "rear". In FIG. 1, as an example, the traveling motor 22 side with respect to the blade 23 is shown as the "front". Also, the lateral direction perpendicular to the fore-aft direction is the left-right direction. In this case, the left side as seen from the operator (pilot, driver) sitting in the cockpit 41a is the "left" and the right side is the "right". Furthermore, the direction of gravity perpendicular to the fore-aft and left-right directions is the up-down direction, and the upstream side of the gravity direction is the "up" and the downstream side is the "down".

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

[0015] The work machine 3 includes a boom 31, an arm 32, and a bucket 33. By independently driving the boom 31, the arm 32, and the bucket 33, it is possible to perform work of excavating earth and sand, for example.

[0016] The boom 31 is rotated by a boom cylinder 31a. A base end of the boom cylinder 31a is supported on the front part of the upper rotating body 4 and is movable so as to be telescopic. The arm 32 is rotated by an arm cylinder 32a. A base end of the arm cylinder 32a is supported on the tip part of the boom 31 and is movable so as to be telescopic. The bucket 33 is rotated by a bucket cylinder 33a. A base end of the bucket cylinder 33a is supported on the tip part of the arm 32 and is movable so as to be telescopic. The boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a are constituted by hydraulic cylinders.

[0017] The upper rotating body 4 is configured to be rotatable via a swivel bearing (not shown) relative to the lower traveling body 2. A control section 41, a swivel base 42, a swivel motor 43, an engine room 44, etc. are arranged on the upper rotating body 4. The upper rotating body 4 rotates via the swivel bearing by driving the swivel motor 43, which is a hydraulic motor.

[0018] A plurality of hydraulic pumps 71 (see FIG. 2) are disposed on the upper rotating body 4. Each hydraulic pump 71 is driven by an electric motor 61 (see FIG. 2) inside the engine room 44. Each hydraulic pump 71 supplies hydraulic oil (pressurized oil) to hydraulic motors (e.g., the left and right travel motors 22, the swing motor 43) and hydraulic cylinders (e.g., the blade cylinder 23a, the boom cylinder 31a, the arm cylinder 32a, the bucket cylinder 33a). The hydraulic motors and hydraulic cylinders that are driven by the supply of hydraulic oil from any of the hydraulic pumps 71 are collectively referred to as hydraulic actuators 73 (see FIG. 2).

[0019] A control seat 41a is disposed in the control section 41. Various levers 41b are disposed around the control seat 41a. An operator sits in the control seat 41a and operates the levers 41b to drive the hydraulic actuator 73. This allows the lower traveling body 2 to travel, the blade 23 to perform ground leveling work, the work machine 3 to perform excavation work, the upper rotating body 4 to rotate, and the like.

[0020] A battery 53 is attached to the upper rotating body 4. The battery 53 is formed of, for example, a lithium ion battery that outputs high voltage, and is used to drive the electric motor 61. In addition, a power feed port (not shown) is provided on the upper rotating body 4. The power feed port and the external power source 51 are connected via a power feed cable 52. This makes it possible to charge the battery 53.

[0021] When the lower traveling body 2, the work machine 3, and the upper rotating body 4 are collectively defined as the machine body BA, the machine body BA may be driven by a combination of electrically driven equipment and hydraulic equipment. In other words, the machine body BA may include an electric travel motor, an electric cylinder, an electric swing motor, etc., in addition to hydraulic equipment such as the hydraulic actuator 73.

[0022] [2. Control and hydraulic system configuration] 2 is a block diagram showing a schematic configuration of a control system and a hydraulic system of the hydraulic excavator 1. In FIG. 2, dashed arrows indicate transmission paths for detection signals. Solid arrows indicate transmission paths for control signals (commands). The hydraulic excavator 1 includes an electric motor 61. The electric motor 61 is driven by power supplied from a battery 53.

[0023] The rotation speed of the electric motor 61 is detected by a rotation speed detection sensor 61a. That is, the hydraulic excavator 1 is provided with the rotation speed detection sensor 61a that detects the rotation speed of the electric motor 61. Information on the rotation speed of the electric motor 61 detected by the rotation speed detection sensor 61a is input to the ECU 80, which will be described later.

[0024] The hydraulic excavator 1 is equipped with a charger 62. The charger 62 converts AC voltage supplied from the external power source 51 via the power supply cable 52 (see FIG. 1) into DC voltage. The DC voltage (electricity) output from the charger 62 is supplied to the battery 53. The battery 53 is charged by supplying power from the external power source 51 to the battery 53 via the charger 62. In other words, the hydraulic excavator 1 is equipped with the charger 62 that supplies power from the external power source 51 to the battery 53 to charge the battery 53.

[0025] The hydraulic excavator 1 includes an inverter 63. The inverter 63 converts a DC voltage supplied from the battery 53 into an AC voltage and supplies the AC voltage to the electric motor 61. This causes the electric motor 61 to rotate. The supply of the AC voltage (current) from the inverter 63 to the electric motor 61 is performed based on a rotation command (control signal) output from the ECU 80.

[0026] Electric power supplied from the battery 53 to the electric motor 61 passes through the first electric circuit E1. The inverter 63 described above is located between the battery 53 and the electric motor 61 in the first electric circuit E1. Electric power supplied from the charger 62 to the battery 53 passes through the second electric circuit E2. The second electric circuit E2 joins the first electric circuit E1 at a junction Ec located between the battery 53 and the inverter 63. Therefore, the electric power output from the charger 62 is supplied to the battery 53 via the second electric circuit E2 and the junction Ec. That is, the hydraulic excavator 1 includes the first electric circuit E1 that supplies electric power from the battery 53 to the electric motor 61, and the second electric circuit E2 that is connected to the charger 62 and joins with the first electric circuit E1 at the junction Ec.

[0027] The hydraulic excavator 1 also includes a relay 64. The relay 64 is located in the first electric circuit E1 between the junction Ec and the battery 53. The relay 64 switches the first electric circuit E1 between a connected state (electrically connecting the battery 53 and the inverter 63) and a disconnected state (electrically disconnecting the battery 53 and the inverter 63) based on the control of the ECU 80. The relay 64 detects the connected state or the disconnected state, and outputs a detection signal to the ECU 80. This allows the ECU 80 to manage the connected time or disconnected time of the relay 64 based on the detection signal.

[0028] The hydraulic excavator 1 also includes a hydraulic system 70. The hydraulic system 70 includes a hydraulic pump 71, a control valve 72, and a hydraulic actuator 73.

[0029] The hydraulic pump 71 is connected to a rotating shaft (output shaft) of the electric motor 61, and is driven by the rotation of the electric motor 61. The hydraulic pump 71 is, for example, a variable displacement pump, but may be a fixed displacement pump. As described above, a plurality of hydraulic pumps 71 are provided, but FIG. 2 illustrates only one hydraulic pump 71 as an example. The hydraulic pump 71 supplies hydraulic oil in a hydraulic oil tank (not shown) as pressurized oil to the hydraulic actuator 73 via the control valve 72. This drives the hydraulic actuator 73. The control valve 72 is a directional switching valve that controls the flow direction and flow rate of the pressurized oil supplied from the hydraulic pump 71 to the hydraulic actuator 73, and is provided corresponding to each hydraulic actuator 73.

[0030] Thus, the hydraulic excavator 1 is equipped with a hydraulic system 70 including the hydraulic pump 71 driven by the electric motor 61 and the hydraulic actuator 73 to which pressure oil is supplied by the hydraulic pump 71 .

[0031] The hydraulic excavator 1 further includes an ECU (Electronic Control Unit) 80. The ECU 80 is a control unit that controls each part of the hydraulic excavator 1, and is configured to include, for example, a CPU (Central Processing Unit), a storage unit, etc. The ECU 80 generates a rotation command for the electric motor 61 and supplies the command to the inverter 63.

[0032] Furthermore, detection signals from each part of the hydraulic excavator 1 are input to the ECU 80. For example, the electric motor 61, the charger 62, the inverter 63, and the battery 53 each have a built-in sensor (not shown) that detects the operating state of the electric motor 61, the charger 62, the inverter 63, and the battery 53, including the presence or absence of an abnormality, and detection signals from these sensors are input to the ECU 80. This allows the ECU 80 to recognize the operating states of the electric motor 61, the charger 62, the inverter 63, and the battery 53, respectively, based on the above detection signals.

[0033] For example, based on a detection signal from a sensor built into the electric motor 61, the ECU 80 can recognize the time during which the electric motor 61 is driven as the operation time of the electric motor 61. Also, based on a detection signal from a sensor built into the charger 62, the ECU 80 can recognize the time during which the charger 62 is operating (e.g., the charging time of the battery 53). Furthermore, based on a detection signal from a sensor built into the battery 53, the ECU 80 can recognize the time during which the battery 53 is operating (e.g., the charging time and discharging time of the battery 53), and can also recognize the remaining capacity (charge amount) of the battery 53.

[0034] The ECU 80 stores and manages the first operation information and the second operation information in a storage unit within the ECU 80. The first operation information is information on a physical quantity indicating the operation state of the electric motor 61, and includes, for example, the operation time of the electric motor 61 described above. The first operation information may include information on the rotation speed of the electric motor 61 detected by the rotation speed detection sensor 61a. On the other hand, the second operation information is information on a physical quantity indicating the operation state of the battery 53, and includes, for example, the operation time (charge time+discharge time) of the battery 53 described above. The second operation information may include the remaining capacity of the battery 53.

[0035] In this way, the hydraulic excavator 1 is equipped with the ECU 80 as a control unit that manages physical quantities indicating the operating state of the electric motor 61 as first operating information based on the output signal of the electric motor 61, and manages physical quantities indicating the operating state including charging and discharging of the battery 53 as second operating information based on the output signal of the battery 53.

[0036] The hydraulic excavator 1 further includes an output unit 90. The output unit 90 outputs the first operation information and the second operation information managed by the ECU 80. The output unit 90 includes a display unit 91 and a communication unit 92.

[0037] The display unit 91 is configured, for example, by a liquid crystal display device, and displays the first operation information and the second operation information under the control of the ECU 80. That is, the output unit 90 includes the display unit 91 that displays the first operation information and the second operation information. The communication unit 92 is an interface for communicating with an external terminal, and is configured to include an antenna, a transmission / reception circuit, etc.

[0038] Although not shown, the hydraulic excavator 1 is provided with a hydraulic oil temperature sensor that detects the temperature of the above-mentioned hydraulic oil, and a cooling water temperature sensor that detects the temperature of the cooling water flowing through a cooling system for cooling the electric motor 61, etc.

[0039] FIG. 3 shows an example of a display on the display unit 91. As shown in the figure, the display unit 91 displays information 101-103, including the hydraulic oil temperature detected by the hydraulic oil temperature sensor, the remaining charge of the battery 53, and the coolant temperature detected by the coolant temperature sensor. Additionally, the display unit 91 displays the operation time T1 of the electric motor 61 as first operation information together with an icon M1 indicating the electric motor 61, and displays the operation time T2 of the battery 53 as second operation information together with an icon M2 indicating the battery 53. In the example shown in the figure, the operation time T1 is shown to be "300H" and the operation time T2 is shown to be "500H". Note that "H" indicates time (Hour) (the same applies below).

[0040] As in this embodiment, the ECU 80 manages a physical quantity indicating the operating state of the electric motor 61 (for example, the operating time T1 of the electric motor 61) as the first operating information, and manages a physical quantity indicating the operating state including charging and discharging of the battery 53 (for example, the operating time T2=charging time+discharging time) as the second operating information. In this case, the output unit 90 outputs the first operating information, so that an operator or the like (an operator, a worker in the vicinity, a system manager, or the like) can perform maintenance (maintenance inspection) of the hydraulic system 70 (for example, the hydraulic pump 71) at an appropriate timing based on the output first operating information. Furthermore, the output unit 90 outputs the second operating information, so that an operator or the like can perform maintenance of the battery 53 at an appropriate timing that takes into consideration not only deterioration during discharging of the battery 53 but also deterioration during charging, that is, at an appropriate timing independent of the timing of maintenance of the hydraulic system 70, based on the second operating information, and can also replace the battery 53 as necessary.

[0041] In particular, the physical quantity indicating the operation state of the electric motor 61 includes the operation time T1 of the electric motor 61. Because the hydraulic pump 71 is driven by the electric motor 61, the operation time of the hydraulic system 70 including the hydraulic pump 71 is considered to be substantially the same as the operation time of the electric motor 61. Therefore, by the ECU 80 managing the operation time T1 of the electric motor 61 as the first operation information, when the output unit 90 outputs the first operation information, an operator or the like can perform maintenance of the hydraulic system 70 at an appropriate timing based on the first operation information, that is, the operation time of the electric motor 61.

[0042] Furthermore, the physical quantity indicating the operation state of the battery 53 includes the sum of the charging time and discharging time of the battery 53. In this case, when the output unit 90 outputs the second operation information, the operator or the like can perform maintenance of the battery 53 at an appropriate timing based on the sum of the charging time and discharging time of the battery 53. In other words, maintenance of the battery 53 can be performed at an appropriate timing that takes into consideration not only deterioration of the battery 53 during discharging but also deterioration during charging.

[0043] The physical quantity indicating the operating state of the battery 53 is not limited to the sum of the charging time and discharging time of the battery 53. For example, the sum of a total charge amount (absolute value) obtained by integrating the charge amount of the battery 53 for a predetermined period for each of the predetermined periods and a total discharge amount (absolute value) obtained by integrating the discharge amount of the battery 53 for each of the predetermined periods may be treated as the physical quantity indicating the operating state of the battery 53. Even in this case, when the output unit 90 outputs the second operation information, an operator or the like can perform maintenance of the battery 53 at an appropriate timing that takes into consideration not only deterioration due to discharging of the battery 53 but also deterioration due to charging, based on the output second operation information, that is, the sum of the total charge amount and the total discharge amount of the battery 53.

[0044] In this embodiment, the output unit 90 includes a display unit 91 that displays the first operation information and the second operation information. This allows, for example, an operator to easily determine the timing to perform maintenance on the hydraulic system 70 by looking at the first operation information (e.g., operation time T1) displayed on the display unit 91, and also to easily determine the timing to perform maintenance on the battery 53 by looking at the second operation information (e.g., operation time T2) displayed on the display unit 91.

[0045] Moreover, in this embodiment, the output unit 90 includes a communication unit 92. In this configuration, the ECU 80 outputs the first operation information and the second operation information to an external terminal via the communication unit 92, and allows a system administrator who handles the terminal to recognize the first operation information and the second operation information. This allows the administrator to appropriately manage the timing of maintenance of the hydraulic system 70 based on the first operation information, and further allows the administrator to appropriately manage the timing of maintenance taking into account deterioration due to discharging and charging of the battery 53 based on the second operation information.

[0046] Meanwhile, the ECU 80 may determine whether or not at least one of the physical quantity managed as the first operation information and the physical quantity managed as the second operation information has reached a specified value, and when the specified value has been reached, cause the display unit 91 to display that the specified value has been reached. For example, FIG. 4 shows another example of display on the display unit 91. In the figure, when the operation time T1 of the electric motor 61 reaches a first specified value (e.g., 600 H), the operation time T1 is displayed in a blinking manner on the display unit 91 to notify that the operation time T1 has reached the first specified value. In addition, in the figure, when the operation time T2 of the battery 53 reaches a second specified value (e.g., 1000 H), the operation time T2 is displayed in a blinking manner on the display unit 91 to notify that the operation time T2 has reached the second specified value.

[0047] In this way, by ECU 80 controlling the display on display unit 91, the operator can see on display unit 91 and immediately know that the physical quantity managed as the first operation information or the second operation information has reached a specified value, and can easily recognize that it is time to perform maintenance on at least one of hydraulic system 70 and battery 53. This enables the operator to quickly perform appropriate maintenance, such as inspecting hydraulic pump 71 or replacing battery 53.

[0048] 4 shows an example in which the operation times T1 and T2 of the electric motor 61 reach their respective specified values ​​(first specified value, second specified value) at the same time, but they do not necessarily reach the same value at the same time. In other words, when at least one of the operation times T1 and T2 reaches the specified value, the ECU 80 may notify the user that the specified value has been reached by causing the display unit 91 to flash the operation time that has reached the specified value.

[0049] Incidentally, it is preferable that the ECU 80 manages, as the first operation information, a physical quantity indicating the operation state of the electric motor 61 in a state in which the rotation speed of the electric motor 61 detected by the rotation speed detection sensor 61a exceeds a predetermined value (for example, 10 rotations / min). In this case, the ECU 80 displays, on the display screen of the display unit 91 shown in Fig. 3 and Fig. 4, the time during which the electric motor 61 is operating in a state in which the rotation speed of the electric motor 61 exceeds the predetermined value, as the operation time T1 of the electric motor 61.

[0050] By the ECU 80 managing the first operation information as described above, for example, the operation time during which the electric motor 61 is rotating at a rotation speed equal to or lower than the predetermined value (for example, a very low speed) and cannot be regarded as substantially operating can be excluded from the first operation information of the electric motor 61, and the operation time during which the electric motor 61 is regarded as substantially rotating at a rotation speed exceeding the predetermined value can be managed as the first operation information. This makes it possible to improve the accuracy of management of the timing of maintenance of the electric motor 61 based on the first operation information.

[0051] [3. How to obtain physical quantities indicating the operating status of the battery] The drive modes of the hydraulic excavator 1 in this embodiment include a charge mode and a battery mode. The charge mode is an operation mode in which the battery 53 is charged by the charger 62. On the other hand, the battery mode is an operation mode in which the electric motor 61 is driven by the power of the battery 53.

[0052] 5 shows an example of the state (connected state / disconnected state) of the relay 64, the operating state of the electric motor 61, the operating state of the charger 62, and the operating state of the battery 53 in each of the charge mode and the battery mode. When the hydraulic excavator 1 is driven in two drive modes, the charge mode and the battery mode, in the charge mode, the battery 53 is charged by the operation of the charger 62, so that the operating time (2) of the charger 62 is the same as the charging time (3) of the battery 53. On the other hand, in the battery mode, the battery 53 is discharged by the operation of the electric motor 61, so that the operating time (1) of the electric motor 61 is the same as the discharging time (4) of the battery 53. Therefore, the sum of the charging time (3) and the discharging time (4) of the battery 53 is equal to the sum of the operating time (2) of the charger 62 and the operating time (1) of the electric motor 61. In other words, the physical quantity indicating the operating state including charging and discharging of the battery 53 (charging time (3) of the battery 53 + discharging time (4) of the battery 53) is the sum of the operating time (2) of the charger 62 and the operating time (1) of the electric motor 61.

[0053] Therefore, when the hydraulic excavator 1 is operated in the charging mode or the battery mode as described above, the ECU 80 can easily acquire and manage the physical quantity (charging time (3) + discharging time (4)) indicating the operating state of the battery 53 by managing the sum of the operating time (2) of the charger 62 and the operating time (1) of the electric motor 61.

[0054] [4. Other methods for acquiring physical quantities indicating the operating status of a battery] The drive modes of the hydraulic excavator 1 may include a power supply combination mode in addition to the above-mentioned charging mode and battery mode. The power supply combination mode is a mode in which the electric motor 61 is driven by power supplied from at least one of the external power supply 51 and the battery 53.

[0055] 6 shows an example of the state (connected state / disconnected state) of the relay 64, the operating state of the electric motor 61, the operating state of the charger 62, and the operating state of the battery 53 in each of the charge mode, the battery mode, and the combined power source mode. When the hydraulic excavator 1 is driven in the three drive modes of the charge mode, the battery mode, and the combined power source mode, the physical quantity indicating the operating state including the charging and discharging of the battery 53 (charging time (D) of the battery 53+discharging time (E) of the battery 53) is not the sum of the operating time (C) of the charger 62 and the operating time (B) of the electric motor 61, and the same relationship as in FIG. 5 cannot be obtained.

[0056] However, in the charge mode, battery mode, and power supply combination mode, battery 53 is charged or discharged, and both charging and discharging are performed with relay 64 connected. Therefore, the sum of the charging time (D) and discharging time (E) of battery 53 is equal to the connection time (A) of relay 64. In other words, the physical quantity indicating the operating state including charging and discharging of battery 53 (charging time (D) of battery 53+discharging time (E) of battery 53) is the connection time (A) of relay 64.

[0057] Therefore, when the hydraulic excavator 1 is driven in the charging mode, battery mode or combined power source mode as described above, the ECU 80 can easily acquire and manage the physical quantity (charging time (D) + discharging time (E)) indicating the operating state of the battery 53 by managing the connection time (A) of the relay 64.

[0058] The relationship in which the charge time (D)+discharge time (E) of the battery 53 is equal to the connection time (A) of the relay 64 can also be seen in Fig. 5. In other words, when the hydraulic excavator 1 is driven in two drive modes, the charge mode and the battery mode, the relay 64 is in a connected state in both the charge mode and the discharge mode, and therefore in Fig. 5, the sum of the charge time (3) and the discharge time (4) of the battery 53 becomes equal to the connection time (5) of the relay 64. Therefore, the above-mentioned effect that the ECU 80 can easily obtain and manage the physical quantity indicating the operating state of the battery 53 by managing the connection time of the relay 64 can be obtained even when the hydraulic excavator 1 is driven in two drive modes (the charge mode or the battery mode) as shown in Fig. 5.

[0059] In the above, a hydraulic excavator, which is a construction machine, has been used as an example of an electrically powered work machine, but the work machine is not limited to a hydraulic excavator and may be other construction machines such as a wheel loader, or agricultural machines such as a combine harvester or a tractor.

[0060] Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0061] The present invention can be used in work machines such as construction machines and agricultural machines. [Explanation of symbols]

[0062] 1. Hydraulic excavator (electric work machine) 51 External power supply 53 Battery 61 Electric Motor 62 Charger 61a Rotational speed detection sensor 64 Relay 70 Hydraulic System 71 Hydraulic Pump 73 Hydraulic Actuator 80 ECU (control unit) 90 Output Department 91 Display Department E1 Circuit 1 E2 2nd Circuit Ec confluence

Claims

1. A control method for a work machine including a battery that is charged with power from an external power source and supplies power to an electric motor, comprising the steps of: and storing and outputting the operating time of the battery.

2. The method for controlling a work machine according to claim 1 , wherein the operating time of the battery is the sum of a charging time and a discharging time of the battery.

3. 3. The method for controlling a work machine according to claim 1, further comprising the step of displaying the operating time of the battery together with the remaining charge of the battery on a display unit of a display device.

4. The method for controlling a work machine according to claim 3, wherein the operating time of the battery is displayed alongside the remaining charge of the battery.

5. The method of controlling a work machine according to claim 4 , wherein the battery operating time is displayed along a side edge of the display.

6. The electric motor drives a hydraulic pump; The method for controlling a work machine according to claim 1 , further comprising storing a driving time of the electric motor.

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