Lift Truck With Hybrid Power Source

• US 20070090808A1
• Filed: 10/19/2006
• Published: 04/26/2007
• Est. Priority Date: 10/19/2005
• Status: Active Grant

• Current Assignee: The Raymond Corporation (Toyota Motor Corporation)
• Original Assignee: The Raymond Corporation (Toyota Motor Corporation)
• Inventors: Day, Richard, McCabe, Paul, Gregory, Bryce
• Granted Patent: US 7,730,981 B2
• Time in Patent Office: Days
• US Class Current: 320/137
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 1/20 Energy regeneration from auxiliary equipment
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: B60L 58/30 for monitoring or controlling fuel cells
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: B66F 9/07531 Battery compartments
• CPC Class Codes: B66F 9/07572 Propulsion arrangements
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A lift truck power source includes a hybrid power supply including a storage battery, a capacitor bank, and optionally a fuel cell. The capacitor bank stores power produced during regeneration by either the truck traction system or the lift system and delivers current when current demand exceeds that delivered by the fuel cell. The storage battery or fuel cell acts as a main power supply to deliver current at a rate sufficient to power the lift truck. When the fuel cell is the main power supply, the storage battery stores power during times when current demand is less than that delivered by the fuel cell and delivers current at times when current demand is greater than that delivered by the fuel cell. When the storage battery is the main power supply, the fuel cell supplements the power delivered by the storage battery, and can also recharge the storage battery.

Claims

1. A power source for a lift truck which comprises:

a DC bus connected to supply current to a lift system and a traction system on the lift truck;

a fuel cell mounted on the lift truck and being operable to produce a supply of DC current from a supply of hydrogen;

a storage battery mounted on the lift truck and coupled to the fuel cell;

a capacitor bank mounted on the lift truck and connected to the DC bus; and

a switch connected between the DC bus and the fuel cell and the storage battery, the switch being operable to connect the fuel cell and storage battery directly to the DC bus when the lift truck requires DC current and the capacitor bank is discharged.

2. The power source of claim 1, wherein the switch is operable to connect the capacitor bank to the DC bus to store energy when either of the lift system or the traction system regenerates current to the DC bus and to supply DC current to the DC bus when the capacitor bank is charged and current is demanded by the truck.

3. The power source of claim 1, wherein the capacitor bank comprises supercapacitors.

4. The power source of claim 1, wherein the fuel cell is selectively connected to the storage battery through a switching circuit.

5. The power source of claim 1, wherein the capacitor bank comprises at least one supercapacitor.

6. A lift truck which comprises:

an operator compartment;

a mast, coupled to the operator compartment;

a fork carriage supported on the mast;

a lift system for driving the fork carriage on the mast

a traction system coupled to the operator compartment for propelling the lift truck; and

a power source for supplying power to the lift system and the traction system, the power source comprising;

a DC bus connected to supply current to a lift system and a traction system on the lift truck;

a storage battery mounted on the lift truck and coupled to the DC bus, the storage battery being operable to supply current to the DC bus;

a capacitor bank mounted on the lift truck and coupled to the DC bus, the capacitor bank being operable to store energy when either of the lift system or the traction system regenerates current to the DC bus and being operable to supply DC current to the DC bus when the capacitor bank is charged and current is demanded by the truck.

7. The lift truck as recited in claim 6, wherein the capacitor bank comprises at least one supercapacitor.

8. The lift truck as recited in claim 6, further comprising a fuel cell coupled to the DC bus, the fuel cell being operable to supply current to the DC bus.

9. The lift truck as recited in claim 8, further comprising a switch coupled between the fuel cell and the DC bus.

10. A power source for a lift truck which comprises:

a DC bus connected to supply current to a lift system and a traction system on the lift truck;

a fuel cell mounted on the lift truck and being operable to produce a selected supply of DC current from a supply of hydrogen and couple the DC current to the DC bus;

a storage battery mounted on the lift truck and coupled to the DC bus, the storage battery being operable to supply DC current to the DC bus; and

a capacitor bank mounted on the lift truck and coupled to the DC bus, the capacitor bank being operable to store energy when the lift system regenerates current to the DC bus and being operable to supply DC current to the DC bus when the capacitor bank is charged and the current demand of the truck is greater than the selected supply from the fuel cell.

11. The lift truck of claim 10, wherein the storage battery is operable to supply current to the DC bus when the current demand of the lift truck is more than the selected supply from the fuel cell and to store energy when the current demand of the lift truck is less than the selected supply from the fuel cell.

12. The lift truck of claim 10, wherein the capacitor bank is further operable to store energy when the traction system regenerates current to the DC bus.

13. The lift truck of claim 10, wherein the fuel cell is connected to the DC bus through a diode.

14. The lift truck of claim 10, wherein the fuel cell is connected to the DC bus through a switch circuit.

15. A power source for a lift truck which comprises:

a DC bus connected to supply current to a lift system and a traction system on the lift truck;

a storage battery mounted on the lift truck for supplying DC current when charged;

a capacitor bank mounted on the lift truck and connected to the DC bus; and

a switch connected between the DC bus and the storage battery, the switch being operable to connect a primary bus supplied by the storage battery directly to the DC bus when the lift truck requires DC current and the capacitor bank is discharged.

16. The power source as recited in claim 15, further comprising a controller for controlling the switch, the controller being operable to switch the storage battery directly to the DC bus when a voltage on the DC bus is less than a voltage across the storage battery.

17. The power source as recited in claim 16, further comprising a fuel cell coupled to the primary bus through a second switch, the second switch being operable to connect the fuel cell to the primary bus when a voltage across the battery is less than a voltage across the fuel cell.

18. The power source as recited in claim 16, wherein the switch is operable to be opened to allow the capacitor bank to charge when at least one of the lift system and the traction system are regenerating power, and the voltage on the DC bus is less than the voltage on the primary bus.

19. The power source as recited in claim 17, wherein the second switch is a diode.

20. The power source as recited in claim 17, where the capacitors bank comprises at least one supercapacitor.