Patent Application
20220355678
The present specification relates to a battery charging device for an electric excavator.
In general, an excavator refers to a construction machine having various working functions such as excavation work for digging or reclaiming the ground during construction and civil engineering work, breaker work for changing soil or breaking bedrock, compactor work for compacting soil, and crusher work such as cutting.
The excavator is typically equipped with an engine such as a diesel engine in order to obtain driving power. The excavator operates a hydraulic pump by using power of the engine and supplies a working fluid, which is discharged from the hydraulic pump, to a hydraulic motor or a hydraulic actuator such as a hydraulic cylinder, thereby rotating a traveling crawler or tire or operating working parts such as a boom, an arm, and a bucket.
Since the well-known excavator is equipped with the engine such as a diesel engine, the excavator may freely work without restriction on work sites.
However, because light oil, which is fossil fuel, becomes depleted and causes air pollution, there is an acute need for environmentally friendly alternative energy. Further, the fossil fuel is expensive, and the excavator has distinct characteristics of heavy equipment and thus consumes a large amount of fuel, which causes an increase in operating costs. As a solution for solving the above-mentioned problems, an electric excavator using electrical energy has been proposed.
The electric excavator requires a method of improving efficiency of a battery capacity. In addition, because a battery is inevitably provided in a limited volume in the electric excavator, there is a need to optimize the battery capacity and improve efficiency.
The present disclosure provides a power supply device for an electric excavator, which provides a method capable of enabling both high-speed charging and low-speed charging, as a method of improving efficiency in using a battery.
An embodiment of the present disclosure provides a power supply device for an electric excavator, the power supply device including: a power supply unit configured to supply power of a battery to an electric motor unit; a first charging port connected to the power supply unit and configured to supply first external power to the battery; an on-board charger (OBC) connected to the power supply unit and configured to convert alternating current into direct current when alternating current power is inputted; and a second charging port connected to the OBC and configured to supply second external power to the OBC.
The power supply unit may supply charging power of the OBC or supply the charging power of the OBC and power of the battery power to the electric motor unit on the basis of the amount of required power of the electric motor unit and the amount of charging power of the OBC.
The first charging port may be a high-speed charging port, and the second charging port may be a low-speed charging port.
The power supply unit may compare the amount of required power of the electric motor unit with the amount of charging power of the OBC, the power supply unit may supply the charging power of the OBC and the power of the battery to the electric motor unit when the amount of required power is larger than the amount of charging power of the OBC, and the power supply unit may supply the charging power of the OBC to the electric motor unit and store, in the battery, the charging power of the OBC remaining after the supply of the charging power when the amount of required power is equal to or smaller than the amount of charging power of the OBC.
The power supply device may further include a battery management system (BMS) configured to check whether the excavator is turned on and block connection from the first charging port to the power supply unit in a state in which the excavator is turned on.
The first charging port may be disposed at a lateral side of a cabin of the excavator, and the second charging port may be disposed at a rear side of a cabin of the excavator.
The electric motor unit may include a first inverter and a first motor, and the first motor may be connected to a hydraulic pump.
The electric motor unit may further include a second inverter and a second motor, and the second motor may be connected to a turning speed reducer.
The power supply device may further include: a fan motor; and a converter connected between the fan motor and the power supply unit.
The power supply unit may compare a sum of the amount of required power of the fan motor and the amount of required power of the electric motor unit with the amount of charging power of the OBC, the power supply unit may supply the charging power of the OBC and the power of the battery to the electric motor unit and the fan motor when the sum of both the amount of required power of the fan motor and the amount of required power of the electric motor unit is larger than the amount of charging power of the OBC, and the power supply unit may supply the charging power of the OBC to the electric motor unit and the fan motor and store, in the battery, the charging power of the OBC remaining after the supply of the charging power when the sum of the amount of required power of the fan motor and the amount of required power of the electric motor unit is equal to or smaller than the amount of charging power of the OBC.
Another embodiment of the present disclosure provides a power supply device for an electric excavator, the power supply device including: a power supply unit configured to supply power of a battery to an electric motor unit; a first charging port connected to the power supply unit and configured to supply first external power to the battery; an on-board charger (OBC) connected to the power supply unit and configured to convert alternating current into direct current when alternating current power is inputted; and a second charging port connected to the OBC and configured to supply second external power to the OBC, in which the first charging port is a high-speed charging port, and the second charging port is a low-speed charging port, in which the power supply unit compares the amount of required power of the electric motor unit with the amount of charging power of the OBC, in which the power supply unit supplies charging power of the OBC and power of the battery to the electric motor unit when the amount of required power is larger than the amount of charging power of the OBC, in which the power supply unit supplies the charging power of the OBC to the electric motor unit and stores, in the battery, the charging power of the OBC remaining after the supply of the charging power when the amount of required power is equal to or smaller than the amount of charging power of the OBC, in which the electric motor unit includes a first inverter, a second inverter, a first motor, and a second motor, and in which the first motor is connected to a hydraulic pump, and the second motor is connected to a turning speed reducer.
According to the present disclosure, the high-speed charging or the low-speed charging may be selectively used to charge the electric excavator, as necessary, which makes it possible to improve efficiency in using the battery.
Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings.
When describing the embodiments, a description of technical contents, which are well known in the technical field to which the present application pertains but are not directly related to the present application, will be omitted. This is to more clearly describe the subject matter of the present application without obscuring the subject matter by omitting any unnecessary description.
Similarly, in the accompanying drawings, some constituent elements are illustrated in an exaggerated or schematic form or are omitted. In addition, a size of each constituent element does not entirely reflect an actual size. Like reference numerals designate like or corresponding elements in the drawings.
As illustrated in
The battery unit 110 is used as a power source and may include a battery 111 charged by an external charging device C, and a battery management system (BMS) 112 configured to check for a state of charge of the battery.
For example, the battery 110 may be, but not limited to, a lithium-ion battery. For example, the lithium-ion battery has a capacity that enables the electric excavator to continuously perform high-load work for about 4 hours.
The battery 110 is connected to the power supply unit 120.
The BMS 112 may detect a power storage amount, i.e., electric potential by using various methods such as a method of estimating electric potential by detecting internal resistance that varies depending on a remaining capacity (state of charge (SOC)) and a temperature.
The power supply unit 120 includes a busbar, a relay, a fuse, a switch, and the like and has a plurality of charging ports. The respective ports of the power supply unit 120 are connected to the OBC 130, the first charging port 140, the second charging port 150, the electric motor unit 160 and the converter 180.
A power supply operation of the power supply unit 120 will be described below in detail.
The OBC 130 is connected between the power supply unit 120 and the second charging port 150. For example, the OBC 130 refers to a converter configured to convert alternating current, which enables low-speed charging, into direct current. The OBC 130 converts external power (e.g., power of 220 V and 380 V ac) into predetermined voltage (e.g., 48 V dc).
The first charging port 140 may be a high-speed charging port, and the second charging port 150 is a low-speed charging port. An external power source connected to the first charging port 140 outputs higher electric current than an external power source connected to the second charging port 150.
In addition, the BMS 112 checks whether the electric excavator is turned on. In a state in which the electric excavator is turned on, the BMS 112 cuts off a supply of power from the first charging port 140 to the power supply unit 120. To this end, the BMS 112 may be connected to others component of the electric excavator and transmit or receive signals to or from the components.
The electric excavator is charged when the external power source and the second charging port 150 are connected by means of a cable, and the electric excavator may work in a state in which the cable is connected during the charging process. Therefore, as illustrated in
The electric excavator consistently may supply energy to the battery by performing the low-speed charging while working, thereby increasing working time.
In contrast, since the first charging port 140 performs the charging in the state in which the electric excavator is turned off, the position of the first charging port 140 is less restricted than that of the second charging port 150. Therefore, the first charging port 140 may be disposed at a lateral side P1 of the cabin C of the excavator, which is a position with which the user is familiar, e.g., at which a refueling port was disposed in the related art.
The high-speed charging supplies higher power than the low-speed charging. Therefore, when a position (height) at which the first charging port 140 is disposed is higher than a position at which a charging port of an external charger is disposed, a distance from the external charger increases, and the cable is lengthened. A thickness of the cable needs to increase when the cable is lengthened. Therefore, the first charging port 140 may be disposed at a height at which a connection length between the first charging port 140 and the external charger is minimized. For example, the position (height) at which the first charging port 140 is disposed may be a height of a driver seat. In this case, the height means a length perpendicular to the ground surface.
The electric motor unit 160 is connected between the power supply unit 120 and the hydraulic system and includes an inverter 161 and a motor 162. The electric motor unit 160 is supplied with power from the power supply unit 120 through the inverter 161 and operates the motor 162. The inverter 161 converts direct current power, which is supplied from the power supply unit 120, into alternating current power. Therefore, the motor 162 is supplied with power in the form of alternating current power through the inverter 161.
The hydraulic system 200 may include a hydraulic pump 210, a hydraulic control valve 220, one or more cylinders 230 configured to operate the boom, the arm, the bucket, and the like, a traveling motor 240 for allowing the excavator to travel and a turning motor 250 configured to operate a turning driver.
The hydraulic control valve 220 is connected to the hydraulic pump 210. A working fluid discharged by the hydraulic pump 210 selectively operates the one or more cylinder 230, the traveling motor 240 and the turning motor 250 depending on the control order of the hydraulic control valve 220.
For example, the one or more cylinders 230 include a boom cylinder, an arm cylinder, a bucket cylinder, and the like.
The fan motor 170 is connected to the power supply unit 120 through the converter 180 and supplied with power from the power supply unit 120. The fan motor 170 may operate depending on a temperature of the working fluid. For example, the fan motor 170 may be designed such that the fan motor 170 operates a maximum RPM (revolution per minute) when the temperature of the working fluid is equal to or higher than a preset temperature (e.g., 60° C.). In another modified example, the fan motor 170 may be designed such that the RPM of the fan motor 170 is linearly controlled depending on the temperature of the working fluid.
The electric excavator according to the embodiment of the present disclosure has both the high-speed charging port and the low-speed charging port and may efficiently charge the battery. For example, the electric excavator may be charged by the high-speed charging within a short period of time such as lunch time while the electric excavator idles during the work process, and the electric excavator may be charged by the low-speed charging after work. In addition, when the battery is quickly discharged while the electric excavator performs high-load work, the electric excavator may work while being charged by the low-speed charging. As described above, the operator may selectively use the high-speed charging or the low-speed charging, as necessary. As a result, the electric excavator may work for a long period of time by using the battery having a limited capacity. Therefore, the efficiency and continuity in using the excavator are improved.
Referring to
The battery unit 110 is used as a power source and may include a battery 111 charged by an external charging device C, and a battery management system (BMS) 112 configured to check for a state of charge of the battery.
The battery 110 is connected to the power supply unit 120.
The power supply unit 120 includes a plurality of charging ports. The respective ports are connected to the OBC 130, the first charging port 140, the second charging port 150, the electric motor unit 1160 and the converter 180.
A power supply operation of the power supply unit 120 will be described below in detail.
The OBC 130 is connected between the power supply unit 120 and the second charging port 150.
The electric motor unit 1160 is connected between the power supply unit 120 and the hydraulic system 1200 and includes a first electric motor unit 1160-1 including a first inverter 161 and a first motor 162 and a second electric motor unit 1160-2 including a second inverter 163 and a second motor 164.
The first electric motor unit 1160-1 is supplied with power from the power supply unit 120 through the first inverter 161 and operates the first motor 162. The first inverter 161 converts direct current power, which is supplied from the power supply unit 120, into alternating current power. Therefore, the first motor 162 is supplied with power in the form of alternating current power through the first inverter 161.
The hydraulic system 1200 may include a hydraulic pump 210, a hydraulic control valve 220, one or more cylinders 230 and a traveling motor 240.
The hydraulic control valve 220 is connected to the hydraulic pump 210. A working fluid discharged by the hydraulic pump 210 selectively operates the one or more cylinder 230 and the traveling motor 240 depending on the control order of the hydraulic control valve 220.
For example, the one or more cylinders 230 include a boom cylinder, an arm cylinder, a bucket cylinder, and the like.
The second electric motor unit 1160-2 is supplied with power from the power supply unit 120 through the second inverter 163 and operates the second motor 164. The second inverter 163 converts direct current power, which is supplied from the power supply unit 120, into alternating current power. Therefore, the second motor 164 is supplied with power in the form of alternating current power through the second inverter 163.
The second motor 164 is connected to a turning speed reducer 1250.
According to another embodiment of the present disclosure described above, the electric motor unit 1160 includes the first motor 162 connected to the hydraulic pump 210 and the second motor 164 connected to the turning speed reducer 1250. Therefore, in comparison with the first embodiment, maximum required power of the hydraulic pump 210 may be reduced, which makes it possible to lower the specifications of the hydraulic pump 210. In addition, since the maximum required power of the hydraulic pump 210 may be reduced, the battery capacity may be reduced.
The fan motor 170 is connected to the power supply unit 120 through the converter 180 and supplied with power from the power supply unit 120.
The power supply unit 120 compares the amount of required power of the fan motor 170 and the amount of required power of the electric motor unit 160 or 1160 with the amount of charging power of the OBC 130 (S110).
When the comparison result indicates that the amount of required power of the fan motor 170 and the amount of required power of the electric motor unit 160 or 1160 are larger than the amount of charging power of the OBC 130, charging power of the OBC 130 and power of the battery are supplied to the electric motor unit 160 or 1160 (S120).
When the comparison result indicates that the amount of required power of the fan motor 170 and the amount of required power of the electric motor unit 160 or 1160 are equal to or smaller than the amount of charging power of the OBC 130, the charging power of the OBC 130 is supplied to the fan motor 170 and the electric motor unit 160 or 1160 (S130).
The remaining charging power of the OBC 130, which remains after the charging power of the OBC 130 is supplied to the required power of the fan motor 170 and the electric motor unit 160 or 1160, is stored in the battery 110.
The embodiments disclosed in the present specification have been described above with reference to the accompanying drawings. The embodiments illustrated in the respective drawings should not be interpreted as being restrictive, and the embodiments may be combined with one another by those skilled in the art, who understand the contents disclosed in the present specification. It can be interpreted that some components can be omitted in the case in which the embodiments are combined.
Here, terms or words used in the present specification and the claims should not be interpreted as being limited to a general or dictionary meaning and should be interpreted as a meaning and a concept which conform to the technical spirit disclosed in the present specification.
Therefore, the embodiments disclosed in the present specification and the configurations illustrated in the drawings are just the embodiments disclosed in the present specification and do not represent all the technical spirit disclosed in the present specification. Accordingly, it should be appreciated that various equivalents and modified examples capable of substituting the embodiments may be made at the time of filing the present application.
The power supply device for an electric excavator according to the present disclosure may improve efficiency in using the battery, thereby improving technologies in the fields of excavators.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2019-0112356 | Sep 2019 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2020/012258 | 9/10/2020 | WO |
