Power supply mechanism of electric work machine

Abstract

To provide a power supply mechanism of an electric work machine that can suitably prevent malfunction of a machine body during charging.SOLUTION: A power supply mechanism of an electric work machine comprises rechargeable power supply devices 11, 12 that store electricity by charging from an external power source and supply power to onboard device, and automatically detects that charging from the external power source is performed and prohibits power supply to some of the onboard device. The power supply mechanism of an electric work machine is configured so that electricity is supplied to devices downstream of a starter switch 18 by operating the starter switch 18 from a standby state when the power is off, and comprises switching devices A to D that disable the supply of electricity from the starter switch 18 to the downstream side on the condition that charging operation from the external power source is detected.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a mechanism for controlling the power supply to onboard equipment during charging in an electrically operated work machine. [Background technology]

[0002] In recent years, electrically driven motor vehicles (EVs) have become increasingly popular, partially replacing fossil fuel-powered engine vehicles. A similar trend is also occurring in the field of work machinery such as excavators and crawler carriers, with various companies developing and putting into practical use electric vehicles that use electricity to run their running bodies and to drive other equipment (see, for example, Patent Documents 1 and 2 listed below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-279 [Patent Document 2] Japanese Patent Application Publication No. 2023-160539 Summary of the Invention [Problem to be solved by the invention]

[0004] In electric work machines such as those described above (hereinafter referred to as "electric work machines" in this specification), when the power is off, a power supply device, which is a rechargeable battery pack, is connected to an external power source to charge the power supply device. During charging, it is not necessary to turn off the power to all onboard devices; instead, some devices, such as a monitor installed in the driver's seat and the power supply device's control device (BMS), must be left on. The monitor must be running so that the operator can monitor the charging status, and the BMS must be running to manage the charging of the power supply device from the external power source.

[0005] In this way, if you want to keep some of the devices running while charging, you can consider a configuration in which, for example, a path is provided in the electrical circuit for power supply that passes current only between the power supply device and the devices you want to keep running while charging, and the path is closed by operating a starter switch provided along the path. A starter switch provided on an electric work machine is designed to switch between a power-off state and a running state depending on the angle by inserting and rotating a starter key, for example, and a charging mode in which current is passed only to some of the devices is provided as one of the modes selectable by such a starter switch.

[0006] However, if this switching method is adopted, it is possible that the device may start up due to an accidental operation of the starter switch while charging, and if another accidental operation is performed, the device may start moving.When charging, the device is connected to an external power source via a power cable, and if the device starts moving in this state, there is a risk of damage to the connected equipment or other problems.

[0007] One possible way to prevent this is to provide a separate physical switch for blocking the path in the part of the electrical circuit that is responsible for operational input, separate from the starter switch, and turn off the physical switch during charging to disable operational input. However, even with such a mechanism, the operator may forget to turn off the physical switch, so this is not foolproof in terms of preventing malfunctions.

[0008] SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a power supply mechanism for an electric working machine that can suitably prevent malfunction of the machine during charging. [Means for solving the problem]

[0009] The present invention relates to a power supply mechanism for an electric work machine, which is characterized by having a rechargeable power supply device that stores electricity by charging from an external power source and supplies power to onboard equipment, and is configured to automatically detect when charging from the external power source has been performed and prohibit power supply to some of the onboard equipment.

[0010] The power supply mechanism of the electric work machine of the present invention is configured to supply current to equipment downstream of a starter switch by operating the starter switch from a standby state when the power is off, and can be equipped with a switching device that disables the supply of current from the starter switch to the downstream side on the condition that it detects that a charging operation from the external power source has been performed.

[0011] In the power supply mechanism of the electric work machine of the present invention, the switching device can be configured to allow electricity to be supplied to some of the mounted equipment on the condition that it detects that a charging operation has been performed from the external power source. [Effects of the Invention]

[0012] The power supply mechanism for an electric working machine of the present invention can provide the excellent effect of suitably preventing malfunction of the machine during charging. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a side view showing an example of the configuration of an electric working machine (shovel) to which the present invention is applied. [Figure 2] 2 is a simplified diagram showing an example of an electric circuit provided in the electric operating machine of FIG. 1. FIG. [Figure 3] 3 is a diagram showing a current-carrying state of the circuit shown in FIG. 2 when not charging. [Figure 4] 3 is a diagram showing a current-carrying state during charging of the circuit shown in FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0015] FIG. 1 shows an example of a configuration of an excavator as an electric work machine to which the present invention is applicable. The excavator 1 has a crawler-type running body 3 attached to the bottom of a vehicle body 2, and a frame 4 constituting the vehicle body 2 is rotatably attached to the running body 3 via a swivel 5. A driver's seat 6 is provided at the top of the vehicle body 2, and an arm 7, which serves as a working unit (a part that performs the functions of an electric work machine, such as excavating, crushing, and transporting), is attached to the front. Power supplies (main power supply unit 11 and secondary power supply unit 12, described below; not shown in FIG. 1 ) are housed at appropriate positions on the vehicle body 2 and supply power to a motor (not shown in FIG. 1 ) that drives a hydraulic pump (not shown) and other onboard equipment. The hydraulic pump pumps oil to a hydraulic circuit (not shown) that operates the arm 7, drives the running body 3, and rotates the vehicle body 2 using the swivel 5.

[0016] Fig. 2 shows a circuit for supplying power to each device in the shovel 1. Note that the circuit shown in Fig. 2 shows a schematic configuration of the circuit for the purpose of explaining this embodiment, and is not an accurate circuit diagram. The same applies to Figs. 3 and 4.

[0017] The excavator 1 is equipped with a high-voltage main power supply unit 11 and a low-voltage secondary power supply unit 12 as power supply units. Both the main power supply unit 11 and the secondary power supply unit 12 are rechargeable batteries that store electricity using power supplied from an external power source, and the main power supply unit 11 is configured as a battery with a higher voltage and larger capacity than the secondary power supply unit 12, and is capable of supplying power to the motor 15, which requires a high voltage for operation, and other devices among the onboard equipment of the excavator 1. The secondary power supply unit 12 has a lower voltage and smaller capacity than the main power supply unit 11, and is configured to supply power as needed to the onboard equipment other than the motor 15 that operates at a low voltage.

[0018] Here, the terms "high voltage" and "low voltage" used in this specification are not defined by specific values ​​such as a certain volts or more or less than a certain volts, but are merely terms that relatively describe the difference in voltage between the power supply devices when there is a mechanism such as the electric work machine 1 that is equipped with multiple power supply devices with different supply voltages. In other words, a high-voltage power supply device is a power supply device that can supply power at a higher voltage than other power supply devices, and a low-voltage power supply device is a power supply device that can supply power at a lower voltage than high-voltage power supply devices.

[0019] The main power supply unit 11 is connected to a power inlet 8, which is a connection point to an external power source, via a charger 9, and is charged through the power inlet 8. A converter 13, which is a step-down converter, is provided between the main power supply unit 11 and the secondary power supply unit 12, and current is supplied from the main power supply unit 11 to the secondary power supply unit 12 via the converter 13, allowing the main power supply unit 11 to charge the secondary power supply unit 12. In this way, the secondary power supply unit 12 receives power indirectly from an external power source via the main power supply unit 11 and stores the power.

[0020] A high-voltage, large-capacity main power supply 11 is connected to an electric motor 15 via an inverter 14. The motor 15 is connected to the hydraulic pump (not shown) for driving the running body 3 and arm 7 of the excavator 1; that is, the main power supply 11 supplies the motor 15 with power for driving the running body 3, swivel base 5, and arm 7. In addition, low-voltage power is supplied from the main power supply 11 to other devices (control device 16 and operating device 17) via a converter 13.

[0021] The control device 16 is a controller that monitors and controls the operation of each device mounted on the excavator 1, including the motor 15. In the present embodiment, the control device 16 is equipped with a display (display unit 16a) that is installed in the driver's seat 6, and the operating status of each device and the like grasped by the control device 16 are displayed appropriately on the display unit 16a.

[0022] In this specification, the term "operation system devices" is a convenient general term for multiple devices mounted on the electric work machine 1, other than devices such as the motor 15 and the control device 16. The operation system devices 17 include devices such as a controller for operating devices such as the arm 7, and a controller for operating the motor 15 (that is, for convenience, two boxes are shown as the operation system devices 17 in FIG. 2, but each box may include multiple devices that fall under the category of operation system devices). In addition, the electric work machine 1 is equipped with devices (not shown) such as lighting devices such as work lights and warning lights, and fans and pumps for cooling devices such as the motor 15.

[0023] Among the devices provided on the electric work machine 1, the control device 16, operating device 17, and other devices not shown in the figure that do not require high voltage for operation can be supplied with power from the secondary power supply device 12.

[0024] In addition, the secondary power supply 12 can supply power to a BMS (battery management system; shown together with the main power supply 11 in Figure 2) connected to the main power supply 11, and when the motor 15 is started, the BMS is controlled using power supplied from the secondary power supply 12, and the necessary power is supplied to the motor 15 from the main power supply 11 via the inverter 14.

[0025] A starter switch 18 is provided along the path from the main power supply unit 11 and the secondary power supply unit 12 to the operating system devices 17. By inserting a starter key into this starter switch 18 and turning it, the power supply mode for each of the above-mentioned devices can be switched and these devices can be turned on and off.

[0026] The configuration of the above circuit will now be described in more detail.

[0027] As described above, the main power supply 11 is connected to the motor 15 via the inverter 14, and high-voltage power is supplied from the main power supply 11 to the motor 15. The main power supply 11 is also connected to the low-voltage secondary power supply 12 via the converter 13, and the downstream path of the secondary power supply 12 is connected to the BMS of the main power supply 11 as well as to the control device 16 and the operating device 17, so that power can be supplied to these devices from the secondary power supply 12. Low-voltage power can also be supplied from the main power supply 11 via the converter 13 to these devices.

[0028] The power supply path from the power supplies (main power supply 11, secondary power supply 12) to each device branches downstream of the secondary power supply 12 into a path 21 that passes through the starter switch 18 and a path 22 that does not pass through the starter switch 18. The path 21 that passes through the starter switch 18 connects the secondary power supply 12 to the BMS of the main power supply 11 and is also connected to part of the operating device 17. When the electric work machine 1 is started, operation of the starter switch 18 first starts the BMS of the main power supply 11 from the secondary power supply 12, which then starts supplying electricity from the main power supply 11 to the motor 15 via the inverter 14. Path 22, which does not pass through starter switch 18, is connected to another part of control device 16 and operating system device 17, so that power can be supplied to these devices as needed even when electric work machine 1 is in a standby state where it is not started (note that of operating system device 17, which is made up of multiple devices, some are connected only to path 21 or path 22, and another part is connected to both path 21 and path 22).

[0029] Paths 21 and 22 branch off appropriately from the positions of secondary power supply device 12 and starter switch 18, which are located upstream, and are connected to devices located downstream of these devices. The portion of path 21 that reaches the BMS of main power supply device 11 is connected midway to a portion of path 22 that reaches control device 16 (this portion is conveniently referred to as connection path 23). The portion of path 22 that reaches control device 16 is connected to connection path 23 upstream of control device 16, and connection path 23 merges midway with the portion of path 21 that reaches the BMS of main power supply device 11. The portion of path 22 that reaches control device 16 branches off upstream of the branch point to connection path 23 (this portion is conveniently referred to as branch path 22a), and branch path 22a is connected to charger connection detection unit 19. This charger connection detection unit 19 is a pin that detects when a connection cable to an external power source is connected to the power feed port 8 and notifies this to the control device 16 (the function of this charger connection detection unit 19 will be described later).

[0030] Furthermore, the portion of the path 22 that leads to the control device 16 is connected to the power feed port 8 by another path upstream of the branch path 22a (this portion is referred to as a power feed detection path 24).

[0031] The circuit is further provided with switching devices A to H for appropriately switching the energized state depending on whether the electric operating machine 1 is being charged from an external power source or not and depending on the operation of the starter switch 18.

[0032] Switching device A is a relay coil provided in power supply detection path 24, and is excited by the passage of current through power supply detection path 24. Switching device B is a relay contact provided in the portion of path 22 connected to control device 16, between the connection point of power supply detection path 24 and the branch point to branch path 22a, and is configured to close the contact when switching device A is excited.

[0033] The switching device C is a relay coil provided in the branch path 22a, and is excited by the passage of current through the branch path 22a. The switching device D is a relay contact provided on the upstream side of the starter switch 18 in the path 21, and is opened by the excitation of the switching device C.

[0034] Switching device E is a relay coil connected midway along path 21, and is excited by the passage of current through path 21. Switching device F is a relay contact provided midway along a branch path (referred to as branch path 22b) that branches off from the middle of path 22, and the contact is closed by the excitation of switching device E. Switching device G is a relay coil connected to branch path 22b, and is excited by the passage of current through path 22.

[0035] The main power supply 11 is connected to the inverter 14 and also to the secondary power supply 12 via the converter 13, but the path 25 from the main power supply 11 to the converter 13 branches off midway (this is referred to as a branch path 25a) and is connected to the inverter 14. The switching device H is a relay contact provided midway along the branch path 25a, and the contact is closed when the switching device G is energized.

[0036] Using these switching devices A to D, the electrical circuit shown in Fig. 2 provided in the excavator 1 is configured to automatically detect when a charging operation from an external power source has been performed and to prohibit power supply to some of the onboard equipment. Furthermore, the electrical circuit shown in Fig. 2 is also configured such that, when an operation to start the motor 15 is input to the starter switch 18 while the excavator is in a standby state where the power is off and not charging, switching devices E to H start the motor 15 by supplying power from the main power supply 11 to the inverter 14. While the example shown here illustrates a case where switching device A detects that a charging operation has been performed by detecting the flow of current through the power supply detection path 24, any mechanism for detecting that a charging operation has been performed may be used. For example, a sensor that detects the connection of a power supply cable to the power inlet 8 or a sensor that detects voltage or current at an appropriate position on the circuit may be provided.

[0037] In addition, various other devices and mechanisms (not shown) may be connected to or incorporated into the circuit as needed, but parts that are not directly related to the gist of the present invention have been omitted from the illustration as appropriate.

[0038] The operation of the above-described embodiment will now be described.

[0039] Figures 3 and 4 show the current-carrying states of the circuit shown in Figure 2 when not charging and when charging, respectively. In each state, paths through which current can flow are shown by solid lines, and paths through which current is cut off are shown by dashed lines.

[0040] When the power cable is not connected to the power inlet 8 and charging is not in progress ( FIG. 3 ), the contacts of the switching device D located upstream of the starter switch 18 are closed, allowing the electric work machine 1 to be turned on and off by operating the starter switch 18. When the starter key is inserted into the starter switch 18 to start the electric work machine 1 from a standby state in which the power is off and charging is not in progress, power is supplied from the secondary power supply 12 via path 21 to the control device 16, some operating devices 17, and the BMS of the main power supply 11, which are connected downstream of the starter switch 18. The inverter 14 and the motor 15 are started by the power supply from the main power supply 11. At this time, the motor 15 is started by the sequential operation of the switching devices E to H. That is, when the downstream path 21 is energized by operating the starter switch 18, the switching device E, which is a relay coil connected to path 21, is excited, and the contacts of the switching device F, which is a relay contact provided midway through the branch path 22b of path 22, are closed. When switching device F is closed, switching device G, which is a relay coil connected to branch path 22b, is excited, and the contact of switching device H, which is a relay contact provided in branch path 25a, is closed. Power is supplied from main power supply 11 to inverter 14 through path 25 and branch path 25a, starting inverter 14 and enabling motor 15 to operate.

[0041] When the power supply is off and a power cable is connected to the power inlet 8 (FIG. 4), current flows through the power supply detection path 24, which excites switching device A, a relay coil on the power supply detection path 24. The excited switching device A closes the contact of switching device B, a relay contact on path 22. When the contact of switching device B closes, current flows from the secondary power supply device 12 to path 22 and branch path 22a, exciting switching device C, a relay coil on branch path 22a. The excited switching device C opens the contact of switching device D, a relay contact on path 21. When the contact of switching device D opens, no current flows through path 21 downstream from the starter switch 18, preventing the inverter 14 and some of the operating devices 17 from starting. Operating the starter switch 18 in this state prevents these devices from starting, and the electric work machine 1 cannot operate, at least via the motor 15.

[0042] A portion of path 22 in which switching device B is located is connected to control device 16, and when the contacts of switching device B are closed, power is supplied to control device 16. In addition, the downstream side of path 22 in which switching device B is located branches into branch path 22a, and when the contacts of switching device B are closed, current is passed through charger connection detection unit 19 connected to branch path 22a. When current is passed through, charger connection detection unit 19 inputs a signal to control device 16, and in response to this signal, control device 16 inputs a command signal to the BMS of main power supply device 11 to permit charging. In response to this, the BMS supplies power to main power supply device 11 from power feed port 8. A display unit 16a provided on control device 16 can display the charging status of main power supply device 11, etc.

[0043] When the power supply from the external power source is stopped in this state (see FIG. 3), the power supply to the power supply detection path 24 stops, the switching device A is demagnetized, and the contact of the switching device B opens. The power supply from the secondary power supply device 12 to the downstream side of the path 22 where the switching device B is located is cut off, and the power supply to the branch path 22a also stops, so the switching device C is demagnetized and the contact of the switching device D closes. In this way, the electric work machine 1 can be started again by operating the starter switch 18.

[0044] When the power supply to branch path 22a is stopped, the power supply to charger connection detection unit 19 is stopped, and the input of signals from charger connection detection unit 19 to control device 16 is stopped. In response to this, control device 16 permits operation of inverter 14, enabling power supply from main power supply device 11 to motor 15. In addition, the BMS of main power supply device 11 turns off charging of main power supply device 11 from charger 9.

[0045] As described above, the electric work machine 1 of this embodiment has a simple configuration in which switching devices A to D are provided in the electrical circuit. This allows power to be supplied to some necessary devices (such as the control device 16, display unit 16a, and BMS of the main power supply device 11) while cutting off power to the motor 15 and other devices during charging. Furthermore, when not charging, power is allowed to be supplied to the motor 15 and other devices on the condition that the device is in a non-charging state (no current is flowing through the power supply detection path 24), and the electric work machine 1 can be started by operating the starter switch 18. Thus, the electric work machine 1 is designed so that the motor 15 and other devices do not malfunction even if the starter switch 18 is operated during charging. Instead of providing a physical switch or the like that cuts off power supply to devices when operated by an operator during charging, the electric work machine 1 automatically detects whether or not power is being supplied to the power inlet 8, and automatically cuts off power supply to some devices accordingly. This eliminates the need to worry about forgetting to operate the physical switch, and more reliably prevents malfunctions.

[0046] As described above, the power supply mechanism of the electric work machine of this embodiment is equipped with rechargeable power supply devices 11, 12 that store electricity by charging from an external power source and supply power to the onboard equipment, and is configured to automatically detect when charging from an external power source has been performed and prohibit power supply to some of the onboard equipment. This makes it possible to more reliably prevent malfunctions compared to conventional technology that provides a physical switch or the like that can be operated by an operator to cut off power supply to equipment during charging.

[0047] The power supply mechanism of the electric working machine of this embodiment is configured to supply current to devices downstream of the starter switch 18 when the starter switch 18 is operated from a standby state when the power is off, and is equipped with switching devices A to D that disable the supply of current from the starter switch 18 to the downstream side on the condition that it detects that charging from the external power source has been performed. In this way, the above-mentioned operational effects can be obtained with a simple configuration in the electric working machine 1 that is started by operating the starter switch 18.

[0048] In the power supply mechanism of the electric operating machine of this embodiment, the switching devices A to D are configured to allow the supply of electricity to some of the onboard equipment on the condition that charging operation from the external power source is detected. In this way, while the supply of electricity to some of the onboard equipment is prohibited during charging, the supply of electricity to other onboard equipment that needs to operate during charging can be performed.

[0049] Therefore, according to the present embodiment, malfunction of the device during charging can be suitably prevented.

[0050] The power supply mechanism for an electric working machine of the present invention is not limited to the above-described embodiment. For example, in the above embodiment, a swing-type shovel is used as an example of an electric working machine, but the present invention is not limited to this and can be applied to various types of electric working machines. Of course, various modifications can be made to the present invention without departing from the scope of the present invention. [Explanation of symbols]

[0051] 11 Power supply (main power supply) 12 Power supply (sub power supply) 18 Starter switch A Switching Device B Switching Device C Switching Device D Switching Device

Claims

1. It is equipped with a rechargeable power supply that stores electricity by charging from an external power source and supplies power to onboard equipment. It is configured to automatically detect when charging from an external power source is performed and prohibit power supply to some of the onboard equipment. A power supply mechanism for an electric work machine characterized by the above.

2. The system is configured to energize devices downstream of a starter switch by operating the starter switch from a standby state when the power is off, and A switching device is provided that disables the flow of electricity from the starter switch to the downstream side when it detects that charging has been performed from the external power source.

2. The power supply mechanism for an electric operating machine according to claim 1.

3. The switching device is configured to allow power to be supplied to some of the onboard equipment on the condition that it detects that a charging operation from the external power source has been performed.

3. The power supply mechanism for an electric operating machine according to claim 2.

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