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EP-4737649-A1 - ELECTRIC WORK MACHINE AND METHOD FOR CONTROLLING ELECTRIC WORK MACHINE

EP4737649A1EP 4737649 A1EP4737649 A1EP 4737649A1EP-4737649-A1

Abstract

To achieve, in an electric working machine, both shortening a charging time and holding down increases in the temperature of a battery according to the purpose of use. An electric working machine (1) includes a battery assembly (30), an electric actuator (9) to be actuated by electricity supplied by the battery assembly, a working device (20) to be actuated by the electric actuator being driven, a temperature detector (31b, 31c, 31d, 32b, 32c, 32d) to detect a temperature of the battery assembly, and a controller (7) configured or programmed to control, according to the temperature of the battery assembly, a first upper limit (I_th1) which is an upper limit of a charging current supplied to the battery assembly. The controller is configured or programmed to switch between (i) a first mode (M1) in which the controller controls the charging current based on a first correspondence relationship in which temperatures of the battery assembly and first upper limits are associated with each other, and (ii) a second mode (M2) in which the controller controls the charging current based on a second correspondence relationship in which the first upper limits are lower than in the first correspondence relationship at one or more of the temperatures.

Inventors

  • ITO, JUNKI

Assignees

  • KUBOTA CORPORATION

Dates

Publication Date
20260506
Application Date
20240521

Claims (9)

  1. An electric working machine comprising: a battery assembly; an electric actuator to be actuated by electricity supplied by the battery assembly; a working device to be actuated by the electric actuator being driven; a temperature detector to detect a temperature of the battery assembly; and a controller configured or programmed to control, according to the temperature of the battery assembly, a first upper limit which is an upper limit of a charging current supplied to the battery assembly; wherein the controller is configured or programmed to switch between (i) a first mode in which the controller controls the charging current based on a first correspondence relationship in which temperatures of the battery assembly and first upper limits are associated with each other, and (ii) a second mode in which the controller controls the charging current based on a second correspondence relationship in which the first upper limits are lower than in the first correspondence relationship at one or more of the temperatures.
  2. The electric working machine according to claim 1, wherein the controller is configured or programmed to lower the first upper limit as the temperature of the battery assembly increases in each of the first mode and the second mode.
  3. The electric working machine according to claim 1, wherein the first upper limits of the second mode are: lower than the first upper limits of the first mode in a first temperature range of the temperatures of the battery assembly; and equal to or substantially equal to the first upper limits of the first mode in a second temperature range in which the temperatures of the battery assembly are higher than in the first temperature range.
  4. The electric working machine according to claim 3, wherein the first upper limits in the first temperature range are constant with respect to the temperatures of the battery assembly in at least one of the first mode or the second mode.
  5. The electric working machine according to claim 1, wherein the controller is configured or programmed to control an output of the working device according to the temperature of the battery assembly.
  6. The electric working machine according to claim 1, wherein the controller is configured or programmed to control a second upper limit which is an upper limit of a discharge current supplied from the battery assembly to the electric actuator according to the temperature of the battery assembly.
  7. The electric working machine according to claim 6, wherein the controller is configured or programmed to lower the second upper limit as the temperature of the battery assembly increases.
  8. The electric working machine according to claim 1, further comprising a switch to switch between the first mode and the second mode.
  9. A method of controlling an electric working machine, the electric working machine including: a battery assembly; an electric actuator to be actuated by electricity supplied by the battery assembly; a working device to be actuated by the electric actuator being driven; a temperature detector to detect a temperature of the battery assembly; and a controller configured or programmed to control charging of the battery assembly; the method comprising: a first step including selecting a first mode or a second mode; and a second step including controlling a first upper limit that is an upper limit of a charging current supplied to the battery assembly according to the first mode or the second mode selected in the first step and the temperature of the battery assembly; wherein the second step includes, when the first mode is selected, controlling the charging current based on a first correspondence relationship in which temperatures of the battery assembly and first upper limits are associated with each other, and, when the second mode is selected, controlling the charging current based on a second correspondence relationship in which the first upper limits are lower than in the first correspondence relationship at one or more of the temperatures.

Description

Technical Field The present invention relates to electric working machines each actuated by electricity of a battery assembly and methods of controlling electric working machines. Background Art Patent Literature 1 discloses an electric working machine including an electric motor, a battery assembly to supply electricity to the electric motor, a hydraulic pump driven by the electric motor to deliver hydraulic fluid, a hydraulic device driven by the hydraulic fluid, and a working device actuated by the hydraulic device. The electric working machine, when the battery assembly is running low, may perform fast charging using an external charger. Citation List Patent Literature PTL 1: Japanese Unexamined Patent Application Publication No. 2021-80703 Summary of Invention Technical Problem However, the battery assembly may generate heat both during charging and discharging, and the high temperature may result in an increased possibility of deterioration. In particular, when performing the fast charging of the battery assembly using a fast charger, large current (for example, about 125 amperes at maximum) flows through the battery assembly. This makes it possible to charge the battery assembly in a relatively short time, but causes a significant increase in the temperature of the battery assembly. Furthermore, in the case of a working machine having the function to restrict performance when the temperature of the battery assembly is equal to or higher than a predetermined value, although the working machine can charge the battery assembly in a relatively short time by performing the fast charging, the working machine may restrict its performance until the temperature of the battery assembly decreases. The present invention was made to solve the above issues in the related art, and it is an object of the present invention is to, in an electric working machine, achieve both shortening a charging time and holding down increases in the temperature of the battery, according to the purpose of use. Solution to Problem An electric working machine according to an example embodiment of the present invention includes a battery assembly, an electric actuator to be actuated by electricity supplied by the battery assembly, a working device to be actuated by the electric actuator being driven, a temperature detector to detect a temperature of the battery assembly, and a controller configured or programmed to control, according to the temperature of the battery assembly, a first upper limit which is an upper limit of a charging current supplied to the battery assembly, wherein the controller is configured or programmed to switch between (i) a first mode in which the controller controls the charging current based on a first correspondence relationship in which temperatures of the battery assembly and first upper limits are associated with each other, and (ii) a second mode in which the controller controls the charging current based on a second correspondence relationship in which the first upper limits are lower than in the first correspondence relationship at one or more of the temperatures. The controller may be configured or programmed to lower the first upper limit as the temperature of the battery assembly increases in each of the first mode and the second mode. The first upper limits of the second mode may be lower than the first upper limits of the first mode in a first temperature range of the temperatures of the battery assembly, and equal to or substantially equal to the first upper limits of the first mode in a second temperature range in which the temperatures of the battery assembly are higher than in the first temperature range. The first upper limits in the first temperature range may be constant with respect to the temperatures of the battery assembly in at least one of the first mode or the second mode. The controller may be configured or programmed to control an output of the working device according to the temperature of the battery assembly. The controller may be configured or programmed to control a second upper limit which is an upper limit of a discharge current supplied from the battery assembly to the electric actuator according to the temperature of the battery assembly. The controller may be configured or programmed to lower the second upper limit as the temperature of the battery assembly increases. The electric working machine may further include a switch to switch between the first mode and the second mode. A method of controlling an electric working machine, the electric working machine including a battery assembly, an electric actuator to be actuated by electricity supplied by the battery assembly, a working device to be actuated by the electric actuator being driven, a temperature detector to detect a temperature of the battery assembly, and a controller configured or programmed to control charging of the battery assembly, the method including a first step including selecting a first mode or a secon