Granted Patent B2

US 8,718,878 · App. 11/696,414 · Granted May 6, 2014

Abstract

Claims (27)

1. A control assembly for a power machine having an engine comprising:

a control mode input device including a power management selection to select a power management control mode and a no power management selection to select a no power management control mode;

a user input device to input a commanded pump stroke or displacement for a hydrostatic drive assembly; and

a controller assembly configured to receive the commanded pump stroke or displacement input from the user input device and to receive one of the power management selection and no power management selection from the control mode input device to provide one of the power management control mode or no power management control mode wherein in the power management control mode the controller assembly determines, based on feedback from an engine speed sensing device whether the engine is experiencing a high demand condition, wherein the high demand condition is indicated by a drop in engine speed, wherein when the high demand condition is indicated, the controller assembly provides an output pump stroke or displacement that is reduced below the output pump stroke or displacement for the commanded stroke or displacement responsive to the feedback from the engine speed sensing device to prevent stalling of the engine and when the high demand condition is not detected, the output pump stroke or displacement is not reduced below the output pump stroke or displacement for the commanded stroke or displacement responsive to the feedback from the engine speed sensor device; and

in the no power management control mode, the controller assembly utilizes the commanded pump stroke or displacement from the user input device to provide the output pump stroke or displacement without utilizing the feedback from the engine speed sensing device, wherein the output pump stroke or displacement is not reduced below the output pump stroke or displacement for the commanded pump stroke or displacement.

2. The control assembly of claim 1 wherein the control mode input device includes a selector including indicia for the power management selection and indicia for the no power management selection.

3. The control assembly of claim 1 wherein the control mode input device includes a speed control mode selection to select a speed control mode and in the speed control mode the controller assembly uses the feedback from the engine speed sensing device to provide the output pump stroke or displacement to maintain a set speed.

4. The control assembly of claim 3 wherein the control mode input device includes a selector having indicia to select the power management control mode, indicia to select the no power management control mode and indicia to select the speed control mode.

5. The control assembly of claim 1 wherein the controller assembly utilizes control methods and characteristics stored in system memory to reduce the commanded pump stroke or displacement responsive to the feedback from the engine speed sensing device in the power management control mode.

6. The control assembly of claim 5 wherein the control methods and characteristics include at least one control curve or data that correlates different engine speeds relative to different pump strokes or displacements and the output pump stroke or displacement is provided based upon the engine speed from the engine speed sensing device using the at least one control curve or data that correlates the different engine speeds relative to the different pump strokes or displacements.

7. The control assembly of claim 5 wherein the controller assembly receives feedback from a throttle position sensor and processes the feedback from the throttle position sensor and the engine speed sensing device to provide the output pump stroke or displacement where the output stroke or displacement is reduced below the output pump stroke or displacement for the commanded pump stroke or displacement based upon the engine speed feedback from the engine speed sensing device compared to a demand engine speed provided from the throttle position sensor using the control method and characteristics.

8. The control assembly of claim 5 wherein in the power management control mode, the controller assembly receives a demand engine speed from a throttle position sensor and the control methods and characteristics include a plurality of control curves that correlate different pump strokes or displacements for different engine speeds for a plurality of different demand engine speeds and the controller assembly uses the engine speed feedback from the engine speed sensing device to determine the reduced pump stroke or displacement in the power management control mode.

9. The control assembly of claim 8 wherein the plurality of control curves include a low, medium and high control curves corresponding to low, medium and high demand engine speeds provided from the throttle position sensor and the low, medium and high control curves provide different output pump strokes or displacements for the same engine speed.

10. The control assembly of claim 1 wherein the hydrostatic drive assembly comprises a variable displacement pump and the controller assembly is configured to interface with control methods or characteristics stored in system memory to determine the reduced pump stroke or displacement in the power management control mode.

11. The control assembly of claim 10 wherein the controller assembly receives feedback from a throttle position sensor and the control methods or characteristics include a plurality of control curves or data for a plurality of demand engine speeds where each of the plurality of control curves correlate engine speeds relative to pump strokes or displacements for one of the plurality of demand engine speeds and the controller assembly utilizes the feedback from the throttle position sensor to provide the demand engine speed to designate one of the plurality of control curves and the controller assembly utilizes the designated control curve and the feedback from the engine speed sensing device to determine the reduced pump stroke or displacement in the power management control mode.

12. The control assembly of claim 11 wherein the plurality of demand engine speeds includes a low, medium and high demand engine speeds provided from the throttle position sensor.

13. The control assembly of claim 1 wherein the user input device comprises a joystick device to input the commanded pump stroke or displacement.

14. A control assembly for controlling a drive pump in a hydrostatic drive system in a power machine having an engine that provides power to the hydrostatic drive system, comprising:

an engine speed sensing device configured to provide engine speed feedback;

a controller assembly configured to receive a commanded pump stroke or displacement input from a pump stoke or displacement input device and provide an output pump stroke or displacement to the drive pump; and

a user interface including a power management selection to select a power management control mode and a no power management selection to select a no power management control mode; and

wherein when the power management control mode is selected, the controller assembly determines whether a high demand condition exists by utilizing the feedback from the engine speed sensing device to sense a drop in engine speed such that when the high demand condition exists, the controller assembly reduces the output pump stroke or displacement below the commanded pump stroke or displacement and if the high demand condition does not exist, the controller assembly utilizes the commanded pump stroke or displacement to provide the output pump stroke or displacement without any reduction in response to the engine speed feedback; and

wherein when the no power management mode is selected, the controller assembly utilizes the commanded pump stroke or displacement to provide the output pump stroke or displacement and the output pump stroke or displacement is not reduced below the commanded pump stroke or displacement.

15. The control assembly of claim 14 including a throttle position sensor and the controller assembly processes feedback from the throttle position sensor and the feedback from the engine speed sensing device to reduce the output pump stroke or displacement below the commanded pump stroke or displacement according to the feedback from the throttle position sensor compared to the feedback from the engine speed sensing device in the power management control mode.

16. The control assembly of claim 14 wherein the user interface includes a rotatable dial including indicia for selecting the power management control mode and the no power management control mode.

17. The control assembly of claim 14 wherein the user interface includes a toggle switch including indicia for selecting the power management control mode and the no power management control mode.

18. The control assembly of claim 15 wherein the throttle position sensor detects a low, medium and high throttle position and the controller assembly uses control methods or characteristics having control curves corresponding to the low, medium or high throttle positions wherein the low control curve provides a different output pump stroke or displacement for an engine speed than the medium control curve for the same engine speed and the medium curve provides a different output pump stroke or displacement than the high control curve for the same engine speed and the controller assembly utilizes the feedback from the throttle position sensor to designate one of the control curves and utilizes the designated control curve to reduce the output pump stroke of displacement below the commanded pump stroke or displacement utilizing the feedback from the engine speed sensing device.

Assignments (15)