Method for controlling an electric drive machine

• US 7,350,611 B2
• Filed: 06/15/2004
• Issued: 04/01/2008
• Est. Priority Date: 06/15/2004
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Liang, Chih Chieh, Garnett, Stephen Carl, Betz, Michael Donald
• Primary Examiner(s): COOLMAN, VAUGHN
• Application Number:
  US10/866,992
• Publication Number:
  US 20050274555A1
• Time in Patent Office: 1,386 Days
• Field of Search: 180/65.1, 180/65.3, 180/65.4, 180/69.3, 180/170, 701/101, 701/102, 701/50
• US Class Current: 180/69.3
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2520/06 Direction of travel
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60Y 2200/411 Bulldozers, Graders
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A method is provided for controlling an electric drive work machine including an engine and an electric motor that provides power to enable the work machine to travel across a surface terrain at certain ground speeds. In one embodiment, the method may include detecting a reverse directional shift of the work machine causing the work machine to travel in a reverse direction. Further, the method may include performing an engine speed reduction process that reduces a current speed of the engine based on the detected reverse directional shift without reducing a ground speed of the work machine while traveling in the reverse direction.

Claims

1. A system for controlling an electric drive work machine, comprising:

an engine;

an electric motor that provides power to a travel mechanism that allows the work machine to travel across a terrain surface at certain ground speeds;

an engine control system that is configured to;

determine when the work machine experiences a reverse directional shift causing the work machine to travel in a reverse direction,

determine whether a ground speed of the work machine while traveling in the reverse direction is above a predetermined threshold value, and

send an engine control signal to the engine that reduces the speed of the engine from a current engine speed to an adjusted engine speed based on the detected directional shift and when the ground speed of the work machine while traveling in the reverse direction is above the predetermined threshold value.

2. The system of claim 1, wherein the engine control system does not send the engine control signal to the engine when the work machine experiences a load event white traveling in the reverse direction.

3. The system of claim 2, wherein the load event represents at least one of (i) a condition where the work machine is manipulating a load while traveling in the reverse direction and (ii) a condition where the work machine is traversing a sloped terrain surface while traveling in the reverse direction.

4. The system of claim 3, wherein manipulating the load includes at least one of pulling a load, pushing a load, and carrying a load.

5. The system of claim 1, wherein the engine control system includes a memory device storing a performance map and the engine control system is configured to:

determine the adjusted engine speed based on information stored in the performance map.

6. The system of claim 1, wherein the engine control system is further configured to send the engine control signal when the work machine is not experiencing a load while traveling in the reverse direction.

7. The system of claim 6, wherein the experienced load is a load produced by the work machine performing at least one of:

pushing a load,

pulling a load, and

carrying a load.

8. The system of claim 6, wherein the experienced load is a load produced by the work machine traversing a sloped terrain surface while traveling in the reverse direction.

9. The system of claim 1, further including:

a sensor that generates a sensor signal reflecting when the work machine is experiencing the reverse directional shift,

wherein the engine control system determines that the work machine is experiencing a reverse directional shift based on the sensor signal.

10. A system for controlling an electric drive work machine including an engine and an electric motor that provides power to enable the work machine to travel across a surface terrain at certain ground speeds, the system comprising:

means for detecting a reverse directional shift of the work machine causing the work machine to travel in a reverse direction;

means for determining whether a ground speed of the work machine while traveling in the reverse direction is above a predetermined threshold value;

means for sending an engine control signal to the engine that reduces the speed of the engine from a current engine speed to an adjusted engine speed based on the detected directional shift and when the ground speed of the work machine while traveling in the reverse direction is above the predetermined threshold value; and

means for performing an engine speed reduction process that reduces a current speed of the engine based on the detected reverse directional shift without reducing a ground speed of the work machine while traveling in the reverse direction.