Working vehicle

Abstract

There is provided a working vehicle with increased safety by preventing deterioration of a battery due to over-discharge of the battery caused by an operator not noticing occurrence of a malfunction in driving by connected to an external power source. The working vehicle includes a charger, the battery, a sensor, a drive unit, a controller, a display unit, a battery management system, and a switch, in which the battery management system is configured to control the working vehicle to be switched to the driving by connected to the external power source when the switch is turned on after the charger is connected to an external power source and a valid signal for driving by connected to the external power source is received.

Claims

1. A working vehicle comprising: a charger that is connectable to an external power source; a battery; a sensor detecting charging current to the battery; a drive unit hydraulically operated by electric power supplied from at least one of the charger and the battery; a controller; a display unit; a battery management system monitoring both of the charger and the battery in a state of driving by connection to the external power source after receiving a valid signal for driving by connection to the external power source from the controller, the valid signal indicating that the external power source can be used; and a switch connection to the external power source for operation of the working vehicle, wherein the battery management system is configured to control the working vehicle to be switched to the driving by connection to the external power source when the switch is turned on after the charger is connected to the external power source and the valid signal for driving by connected to the external power source is received from the controller, and the battery management system is configured to control the working vehicle to be switched to the driving by connection to the external power source when the charger is connected to the external power source after the switch is turned on and the valid signal for driving by connection to the external power source is received from the controller.

2. The working vehicle according to claim 1, wherein the battery management system is configured to output a warning signal to the controller when an output from the charger is stopped in the state of the driving by connection to the external power source.

3. The working vehicle according to claim 1, wherein the battery management system is configured to output a warning signal to the controller when a state-of-charge of the battery becomes a lower limit in the state of the driving by connection to the external power source.

4. The working vehicle according to claim 3, wherein the battery management system is adapted to control discharging power discharged from the battery to be suppressed to be equal to or lower than charging power charged to the battery when the state-of-charge of the battery becomes the lower limit in the state of the driving by connected to the external power source.

5. The working vehicle according to claim 1, wherein the battery management system is configured to control the state-of-charge of the battery not to exceed an upper limit when the battery is fully charged in the state of the driving by connection to the external power source.

6. The working vehicle according to claim 1, wherein the battery management system is configured to be returned to a state before the working vehicle was switched to the driving by connection to the external power source by turning off the switch and by stopping the charger.

7. The working vehicle according to claim 1, further comprising: a first-relay and a second-relay, wherein the battery management system is configured to connect the charger to the battery by performing on-control of the first-relay, configured to connect the battery to the drive unit by performing on-control of the second-relay, and configured to connect the charger, the battery, and the drive unit by processing on-control of the first-relay and the second-relay.

8. The working vehicle according to claim 1, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

9. The working vehicle according to claim 2, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

10. The working vehicle according to claim 3, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

11. The working vehicle according to claim 4, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

12. The working vehicle according to claim 5, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

13. The working vehicle according to claim 6, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

14. The working vehicle according to claim 7, wherein the battery is a lithium-ion rechargeable battery, a lead-acid battery supplying power to the battery management system when the switch is turned on and a third-relay present, and the battery management system is configured to connect the lithium-ion rechargeable battery to the controller by processing on-control of the third-relay.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic circuit diagram showing a configuration of a working vehicle according to an embodiment.

(2) FIG. 2 is a flowchart showing an operation procedure of a battery management system in the working vehicle according to the embodiment.

(3) FIG. 3 is a schematic external view showing the working vehicle according to the embodiment.

DESCRIPTION OF EMBODIMENTS

(4) Hereinafter, an embodiment of the present invention will be explained in detail with reference to the drawings. A working vehicle 1 to which the embodiment is applied is a battery-type working vehicle such as a power shovel, a skid-steer loader, a carrier or other known vehicles as shown in FIG. 3 as an example. A drive unit 2 of the working vehicle 1 is a hydraulic drive mechanism such as an electric actuator like an electric motor or other known mechanisms. The drive unit 2 is operated by electric power supplied from either or both of a charger 8 and a battery 9 and is drive-controlled by a controller 3. A battery management system 5 is configured to monitor a state-of-charge of the battery 9 based on a detection signal from a sensor 7 detecting charging current to the battery 9 and is also configured to monitor the charger 8 based on the detection signal from the sensor 7 detecting charging current to the battery 9. The battery management system 5 may be denoted by a BMS 5 in the following description. Note that the same signs and numerals are assigned to components having the same functions and repeated explanation thereof may be omitted in all drawings for explaining the embodiment.

(5) As shown in FIG. 1, the working vehicle 1 includes the charger 8 operated by being connected to an external power source 21, the battery 9 connected to the charger 8, the drive unit 2 operated by the electric power being supplied from either or both of the charger 8 and the battery 9, the controller 3 controlling the drive unit 2, a display unit 4 connected to the controller 3, the BMS 5 monitoring both of the charger 8 and the battery 9 in a state of driving by connected to the external power source after receiving a valid signal for driving by connected to the external power source from the controller 3, and a switch 6 for starting the BMS 5. The switch 6 is a key switch or a start switch as an example, which can adopt a known structure. The display unit 4 is configured to display, for example, operating information of the drive unit 2, operating information of the charger 8, start-of-charge information of the battery 9, and other known vehicle information, displaying a warning on a display screen when an abnormity occurs as well as giving an alarm from a speaker when an abnormity occurs.

(6) In the example of FIG. 1, a first-relay 11, a second-relay 12, and a third-relay 13 which are operated by control of the BMS 5 are provided. A fourth-relay 14 which is operated when the charger 8 is connected to the external power source 21 is also provided. The first-relay 11, the second-relay 12, and the third-relay 13 are connected to the BMS 5, or the first-relay 11, the second-relay 12, and the third-relay 13 are attached to the BSM 5. The fourth-relay 14 is built in the charger 8 or attached to the charger 8.

(7) In the example of FIG. 1, a lead-acid battery 22 supplying the power to the battery management system 5 when the switch 6 is turned on is provided. The BMS 5 performs on-control of the third-relay 13 to thereby connect the lithium-ion rechargeable battery 9 to the controller 3 through a converter 16. That is, the power outputted from the lithium-ion rechargeable battery 9 is stepped down in the converter 16 and supplied to the controller 3 in a state where the third-relay 13 is operated. Note that a configuration in which the converter 16 is not provided may be adopted. It is also possible to output a voltage compatible to a power source voltage of the controller 3 which is previously set from the lithium-ion rechargeable battery 9 and supply the voltage to the controller 3 as an example.

(8) In the example of FIG. 1, the BMS 5 is configured to connect the charger 8 to the lithium-ion rechargeable battery 9 by performing on-control of the first-relay 11. That is, the power outputted from the charger 8 is charged in the lithium-ion rechargeable battery 9 in a state where the first-relay 11 is operated. Moreover, the BMS 5 is configured to connect the lithium-ion rechargeable battery 9 to the drive unit 2 by performing on-control of the second-relay 12. That is, the power outputted from the lithium-ion rechargeable battery 9 is supplied to the drive unit 2 in a state where the second-relay 12 is operated. Then, the BMS 5 is configured to connect the charger 8, the lithium-ion rechargeable battery 9, and the drive unit 2 by performing on-control of the first-relay 11 and the second-relay 12. That is, the power outputted from either or both of the charger 8 and the lithium-ion rechargeable battery 9 is supplied to the drive unit 2 in the state where the first-relay 11 is operated as well as in the state where the second-relay 12 is operated.

(9) In the example of FIG. 1, the charger 8 includes the fourth-relay 14. The charger 8 is started and the fourth-relay 14 is operated when the charger 8 is connected to the external power source 21, then, the lead-acid battery 22 and the BMS 5 are connected. That is, the power is supplied from the lead-acid battery 22 to the BMS 5 in a state where the fourth-relay 14 is operated.

(10) In the example of FIG. 1, the charger 8 is operated and is capable of supplying DC power to the drive unit 2 as well as to the battery 9 when connected to the external power source 21 such as a commercial power source. The charger 8 is mounted on the vehicle. The BMS 5 is configured to be connected to the lead-acid battery 22 through the switch 6 as an example. That is, the power is supplied to the BMS 5 from the lead-acid battery 22 in a state where the switch 6 is ON. According to the example, the power is supplied to the BMS 5 in two systems of the lead-acid battery 22 and the charger 8; therefore, the safe and stable working vehicle 1 can be realized.

(11) The output current of the charger 8 at the time of operation is set to a fixed value as an example. The battery 9 is a lithium-ion rechargeable battery as an example, which is configured by connecting a number of cells. The converter 16 is a DC-DC converter, having a function of stepping down DC voltage to be outputted. A contact type relay such as an electromagnetic switch, or a non-contact type relay such as a MOS-FET relay or a solid-state relay is adopted as the first-relay 11, the second-relay 12, the third-relay 13, and the fourth-relay 14, respectively. The working vehicle 1 is provided with the sensor 7 for detecting charging current of the battery 9. The sensor 7 is a current sensor as an example, having a function of detecting the charging current of the battery 9. The sensor 7 is also capable of detecting discharging current from the battery 9.

(12) FIG. 2 is a flowchart showing an operation procedure of the BMS 5 in the working vehicle 1 according to the embodiment. The operation procedure of the BMS 5 in the working vehicle 1 will be continuously explained below.

(13) [Driving by Connected to External Power Source: A]

(14) After turning on the switch 6 first, an operator connects the charger 8 to the external power source 21. The BMS 5 is started when the switch 6 is turned on, and the process proceeds to Step S1A where ON of the switch 6 is confirmed. As the switch 6 is in ON-state, the process proceeds to Step S2A where the second-relay 12 is turned on. Subsequently, the process proceeds to Step S3A where connection between the charger 8 and the external power source 21 is confirmed. As the charger 8 and the external power source 21 are connected at this time, the process proceeds to Step S4A where validity of the driving by connected to the external power source is judged. When the valid signal for driving by connected to the external power source is received from the controller 3, it is determined that the driving by connected to the external power source is valid, and the process proceeds to Step S5A where the first-relay is turned on. According to the configuration, the BMS 5 judges whether switching to the driving by connected to the external power source is possible or not in the state where the charger 8 is operated; therefore, it is possible to prevent occurrence of a malfunction such that connection between the charger and the external power source is lost at the time of switching to the driving by connected to the external power source.

(15) [Driving by Connected to External Power Source: B]

(16) After connecting the charger 8 to the external power source 21 first, the operator turns on the switch 6. When the charger 8 is connected to the external power source 21, the BMS 5 is started, and the process proceeds to Step S1A where ON of the switch 6 is confirmed. As the switch is not in ON-state, the process proceeds to Step S1B where the connection between the charger 8 and the external power supply 21 is confirmed. As the charger 8 is connected to the external power source 21, the process proceeds to Step S2B where the first-relay 11 is turned on, then, proceed to Step S3B where ON of the switch 6 is confirmed. As the switch 6 is in ON-state at this time, the process proceeds to Step S4B where validity of the driving by connected to the external power source is determined. When the valid signal for driving by connected to the external power source is received from the controller 3, it is determined that the driving by connected to the external power source is valid, and the process proceeds to Step S5B where the second-relay is turned on. According to the configuration, the BMS 5 judges whether switching to the driving by connected to the external power source is possible or not in the state where the charger 8 is operated; therefore, it is possible to prevent occurrence of a malfunction such that connection between the charger and the external power source is lost at the time of switching to the driving by connected to the external power source.

(17) [Judge of Abnormity in Driving by Connected to External Power Source]

(18) After Step S5A, or Step S5B, the BMS 5 proceeds to Step S6 where an abnormity in the driving by connected to the external power source is judged. The BMS 5 judges that the driving by connected to the external power source is in an abnormal state when the output from the charger 8 is stopped in the state of the driving by connected to the external power source. The BMS 5 judges that the driving by connected to the external power source is in the abnormal state when the state-of-charge of the lithium-ion rechargeable battery 9 becomes a lower limit in the state of the driving by connected to the external power source as an example. Then, the BMS 5 proceeds to Step S7 where a warning signal is outputted to the controller 3 when the abnormity in the driving by connected to the external power source is determined. The controller 3 receiving the warning signal performs control so that the abnormity is notified to the operator by either or both of the warning and the alarm. Either or both of the warning and the alarm is transmitted to the operator by the speaker or the screen attached to the display unit 4. Therefore, the operator can instantly notice the abnormity in the driving by connected to the external power source.

(19) Here, the BMS 5 is configured to perform control so that discharging power discharged from the lithium-ion rechargeable battery 9 is suppressed to be equal to or lower than charging power charged in the lithium-ion rechargeable battery 9 when the state-of-charge of the lithium-ion rechargeable battery 9 becomes the lower limit in the state of the driving by connected to the external power source. According to the configuration, the lithium-ion rechargeable battery 9 is positively charged not only in the state of charging but also in the state of the driving by connected to the external power source; therefore, it is possible to prevent the battery from being over-discharged.

(20) Here, the BMS 5 is configured to control the state-of-charge of the lithium-ion rechargeable battery 9 not to exceed an upper limit when the lithium-ion rechargeable battery 9 is fully charged in the state of the driving by connected to the external power source. According to the configuration, it is possible to prevent the lithium-ion rechargeable battery 9 from being over-discharged in the state of the driving by connected to the external power source.

(21) [End of Driving by Connected to External Power Source]

(22) When the warning signal is outputted and the operator notices the abnormity in the state of the driving by connected to the external power source, or when the driving by connected to the external power source is not valid, the operator turns off the switch 6.

(23) Here, the BMS 5 is configured to be reset to a state before the working vehicle is switched to the driving by connected to the external power source by turning off the switch 6 and by stopping the charger 8. According to the configuration, the BMS 5 is reset to the state before the working vehicle is switched to the driving by connected to the external power source by releasing the driving by connected to the external power source and stopping the charger 8. The battery management system is restarted when the operator turns on the switch 6 again in the reset state. That is, the BMS 5 judges whether switching to the driving by connected to the external power source is possible or not after being restarted in the state where the charger 8 is operated; therefore, it is possible to prevent occurrence of an unexpected malfunction such that the connection between the charger 8 and the external power source 21 is lost at the time of switching to the driving by connected to the external power source even after the BMS 5 is restarted.

(24) The above working vehicle 1 may change specifications appropriately in accordance with specifications and so on. The present invention is not limited to the above-described embodiment and various alternations may occur within a scope not departing from the present invention.