Engine droop governor and method

• US 8,175,790 B2
• Filed: 02/05/2009
• Issued: 05/08/2012
• Est. Priority Date: 02/05/2009
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Stemler, Eric D., Mowers, Matthew, Jacobson, Evan E.
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US12/366,477
• Publication Number:
  US 20100192907A1
• Time in Patent Office: 1,188 Days
• Field of Search: 123/349, 123/350, 123/352, 123/357, 123/361, 123/376, 123/402, 123/403, 123/478, 123/480, 123/492, 123/493, 123500-502, 701/50, 701/54, 701101-105, 701/110, 701/114, 701/115
• US Class Current: 701/110
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: F02D 41/0205 using an auxiliary engine speed control engine speed control per se F02D31/00
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18

Abstract

A machine (100) has an internal combustion engine (104) operating in response to a control signal provided by an engine governor (216). The engine (104) provides a torque output to a machine system providing a machine function. An electronic controller (214) determines a current operating state of the engine (104) and a torque utilization of the machine system, and compares the current operating state of the engine (104) with the torque utilization in an engine droop function (302). A change to an engine speed (308) setting of the engine (104) is instructed in response to a change in the torque signal. Such change is to increase the engine speed (308) setting when the torque utilization is increasing, and to decrease the engine speed (308) setting when the torque utilization is decreasing.

Claims

1. A machine including an engine disposed to operate in response to a control signal provided by an engine governor, the engine further disposed to provide a torque output to at least one machine system operating to utilize at least a portion of the torque output to provide a machine function, the machine comprising:

an electronic controller in operable communication with the engine governor and the at least one machine system, the electronic controller disposed to;

determine a current operating state of the engine;

determine a torque utilization of the at least one machine system;

compare the current operating state of the engine with the torque utilization in an engine droop function;

increase the engine speed setting when the torque utilization is increasing; and

decrease the engine speed setting when the torque utilization is decreasing.

2. The machine of claim 1, wherein the at least one machine system is a propel system of the machine utilizing a portion of the torque output of the engine, wherein the machine further includes an implement system disposed to utilize an additional portion of the torque output of the engine, and wherein the electronic controller is disposed to determine the torque utilization of the propel system and the implement system.

3. The machine of claim 1, further including an operator control device providing a command signal that influences the torque utilization of the at least one machine system, wherein the electronic controller is further disposed to determine an expected change in the torque utilization of the at least one machine system based on the command signal.

4. The machine of claim 1, wherein the engine droop function is expressed by the following equation:

5. The machine of claim 1, the engine droop function includes a range of increasing engine speed and increasing engine torque output, which when plotted on a graph having the engine speed plotted along a horizontal axis and engine torque output plotted along a vertical axis approaches a first function having a positive slope within a band of ±

10% around the first function, such that the engine speed increases when the engine torque output increases above a high torque setting.

6. The machine of claim 5, wherein the first function has at least one of a linear, exponential, parabolic, logarithmic, and polynomial shape.

7. The machine of claim 5, wherein the engine droop function further includes a range of decreasing engine speed and decreasing engine torque output, which when plotted on a graph having the engine speed plotted along a horizontal axis and engine torque output plotted along a vertical axis approaches a second function having a positive slope within a band of ±

10% around the second function, such that the engine speed decreases when the engine torque output decreases below a low torque setting.

8. The machine of claim 7, wherein the engine droop function further includes a range of constant engine speed, which when plotted on a graph having the engine speed plotted along a horizontal axis and engine torque output plotted along a vertical axis approaches a linear function extending vertically with respect to the horizontal axis within a band of ±

10% around the linear function, such that the engine speed setting remains constant when the engine torque output is between the low torque setting and the high torque setting of the engine.

9. A method of operating an engine associated with a machine, the engine connected to at least one machine system and disposed to operate at an engine speed setting in response to a control signal provided by an engine governor, the engine further disposed to provide a torque output to the at least one machine system, the method comprising:

determining an operating state of the engine;

determining a torque utilization of the at least one machine system;

determining a change in the torque utilization of the machine;

combining the torque utilization and the change in the torque utilization into a torque signal, and providing the torque signal to the engine governor;

providing the control signal governing the engine speed setting based on the torque signal and the operating state of the engine, such that;

an increase in the torque signal causes the engine speed setting to increase; and

a decrease in the torque signal causes the engine speed setting to decrease.

10. The method of claim 9, wherein the operating state of the engine includes a parameter indicative of the engine speed and an additional parameter indicative of engine torque output.

11. The method of claim 9, wherein the change in the torque signal includes at least one of a change in the torque utilization of the at least one machine system and an expected change in the torque utilization of the at least one machine system.

12. The method of claim 11, further including determining the expected change in the torque utilization based on, at least in part, a change in a position of an operator control device.

13. The method of claim 9, wherein the control signal provided based on the torque signal and the operating state of the engine is performed by an engine droop function, which function includes a predetermined relationship between the engine speed and engine torque output.

14. The method of claim 13, wherein the engine droop function, when plotted on engine map having the engine speed plotted along the horizontal axis and the engine torque output plotted against the vertical axis, includes a range of increasing engine speed and increasing engine torque output, which approximates a line, within a band of ±

10%, the line having a positive slope within a band of ±

10% on the engine map, and a range of decreasing engine speed and decreasing engine torque output, which approximates a line, within a band of ±

10%, the line having a positive slope on the engine map.

15. The method of claim 13, wherein the engine droop function is expressed by the following equation:

16. A computer-readable medium having thereon computer-executable instructions for controlling a speed of an engine providing a torque output to at least one system within a machine, the computer-executable instructions comprising:

instructions for determining an operating state of the engine;

instructions for determining a torque utilization of the at least one system;

instructions for determining a change in the torque utilization of the machine;

instructions for providing a torque signal based on the torque utilization and the change in the torque utilization; and

instructions for governing the speed of the engine based on the torque signal, which causes the speed of the engine to increase when the torque signal increases and the speed of the engine to decrease when the torque signal decreases.

17. The computer-readable medium of claim 16, wherein the speed of the engine is positively correlated with the torque signal in at least one of a linear, parabolic, exponential, logarithmic, and polynomial relationship.

18. The computer-readable medium of claim 16, wherein the instruction for determining a change in the torque utilization further include instructions for quantifying an imminent change in the torque utilization based on a command signal that is provided by an operator control device that is disposed to influence the torque utilization of the at least one system.

19. The computer-readable medium of claim 16, wherein the instructions for determining the operating state of the engine include instructions for determining an operating speed of the engine and instructions for determining an engine torque output of the engine, and wherein the computer-readable medium further includes instructions for providing the operating speed and the engine torque output to an engine map.

20. The computer-readable medium of claim 16, further including instructions for increasing the speed of the engine in anticipation of an increase in the torque utilization.