Battery operated industrial truck

• US 20060043914A1
• Filed: 08/10/2005
• Published: 03/02/2006
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Jungheinrich AG
• Original Assignee: Jungheinrich AG
• Inventors: Langlotz, Martin
• Granted Patent: US 7,145,301 B2
• Time in Patent Office: Days
• US Class Current: 318/139
• CPC Class Codes: B60L 2200/44 Industrial trucks or floor conveyors
• CPC Class Codes: B60L 7/003 Dynamic electric braking by short circuiting the motor
• CPC Class Codes: B66F 9/24 Electrical devices or systems
• CPC Class Codes: Y02P 90/60 Electric or hybrid propulsion means for production processes

Abstract

A battery operated industrial truck with at least one first motor and at least one second motor, which are operated by one electric control or regulation device for each motor, which are realised such that the motors can be operated as generators in order to feed back electric energy into the battery, characterised in that a device for switching excess voltage is provided, which in the generator mode of one of the motors temporarily connects the respective other motor to it as a load when a measuring device measures a condition in which an excess voltage occurs or may occur.

Claims

1. A battery operated industrial truck with at least one first motor and at least one second motor, which are operated by one electric control or regulation device for each motor, which are realised such that the motors can be operated as generators in order to feed back electric energy into the battery, characterised in that a device for switching excess voltage (28, 28a) is provided, which in the generator mode of one of the motors (20, 22) temporarily connects the respective other motor (22, 20) to it as a load when a measuring device (29) measures a condition in which an excess voltage occurs or may occur.

2. An industrial truck according to claim 1, characterised in that the control or regulation devices of the motors (20, 22) each have power electronics and that the device for switching excess voltage is constituted by the power electronics.

3. Industrial truck according to claim 1, characterised in that the measuring device measures the generator voltage or the battery voltage or the course (gradient) thereof.

4. Industrial truck according to claim 1, characterised in that the connection of the respective other motor (22, 20) is ended when the voltage applied on the battery takes a value which is below a threshold value (34) for the excess voltage (30).

5. Industrial truck according to claim 1, characterised in that in the case of excess voltage a pump, driven by the respective other motor (20, 22), is switched to unpressurized operation.

6. Industrial truck according to claim 1, characterised in that a field-oriented regulation is provided for the motors (20, 22) and that the regulation generates a high magnetizing current for the respective other motor (22, 20) in the case of excess voltage.

7. Industrial truck according to claim 1, characterised in that in the control or regulation device of the respective other motor (22, 20), a direct current for the other motor (22, 20) is generated.