Transmission control system and method
AssigneeCaterpillar Inc.
InventorF. Paul Lutgen
Life of this patent
Estimating the term…
Abstract
A method and system for controlling a transmission in a work machine is provided. The output of a hydrostatic transmission having a source of pressurized fluid is combined with the output of a mechanical transmission having at least one engaged clutch. An operational speed of an engine that provides an input to both the hydrostatic transmission and the mechanical transmission is sensed. The at least one clutch of the mechanical transmission is disengaged and the displacement of the source of pressurized fluid is modified when the operational speed of the engine drops below a stall limit. The disengagement of the at least one clutch and the modification of the displacement of the source of pressurized fluid allow the operational speed of the engine to rise above the stall limit.
Claims20
A method of controlling a transmission in a work machine, comprising:
- combining the output of a hydrostatic transmission having a source of pressurized fluid with the output of a mechanical transmission having at least one engaged clutch;
- sensing an operational speed of an engine that provides an input to both the hydrostatic transmission and the mechanical transmission;
- and
- disengaging the at least one clutch of the mechanical transmission and modifying the displacement of the source of pressurized fluid when the operational speed of the engine drops below a stall limit, the disengagement of the at least one clutch and the modification of the displacement of the source of pressurized fluid allowing the operational speed of the engine to rise above the stall limit.
A control system for a transmission combining a mechanical transmission having at least one clutch and a hydrostatic transmission having a source of pressurized fluid, comprising:
- a sensor configured to sense the operational speed of an engine providing an input to the transmission;
- and
- a control configured to disengage the at least one clutch and to modify the displacement of the source of pressurized fluid when the operational speed of the engine drops below a stall limit, the disengagement of the at least one clutch and the modification of the displacement of the source of pressurized fluid allowing the speed of the engine to increase above the stall limit.
A transmission, comprising:
- a mechanical transmission component having at least one clutch;
- a hydrostatic transmission component having a source of pressurized fluid;
- a summing gear assembly operatively joining the mechanical transmission component and the hydrostatic transmission component;
- a sensor configured to sense the operational speed of an engine providing an input to the mechanical and hydrostatic transmission components;
- and
- a control system configured to disengage the at least one clutch and to modify the displacement of the source of pressurized fluid when the operational speed of the engine drops below a stall limit, the disengagement of the at least one clutch and the modification of the displacement of the source of pressurized fluid allowing the speed of the engine to increase above the stall limit.
A work machine comprising:
- an engine having a rated speed, the engine operable to rotate an engine shaft;
- a transmission operatively connected to the engine shaft and including a mechanical transmission component having at least one clutch operable to engage the mechanical transmission component, a hydrostatic transmission component having a source of pressurized fluid operable to displace a pressurized fluid, and a summing gear arrangement configured to combine the outputs of the mechanical transmission component and the hydrostatic transmission component into a drive speed;
- a sensor disposed adjacent the engine shaft and configured to sense the speed of the engine;
- and
- a control system configured to disengage the at least one clutch and to modify the displacement of the source of pressurized fluid when the speed of the engine drops below a predetermined percentage of the rated speed of the engine, the disengagement of the at least one clutch and the modification of the displacement of the source of pressurized fluid allowing the speed of the engine to substantially return to the rated speed.
Dependencies are inferred from the claim text.