Transmission shifting with speed dither and torque dither
First Claim
1. A method of engaging a transmission of a series hydraulic hybrid system having at least one pump/motor selectively connectable to an output drive shaft of the transmission, the method comprising the steps of:
- calculating a desired speed of an output shaft of the at least one pump/motor;
operating the at least one pump/motor at a target speed that is the desired output shaft speed plus a desired speed dither; and
engaging the output shaft of the pump/motor with the output shaft of the transmission when the target speed is reached within a prescribed speed error threshold;
wherein the operating includes regulating the flow of fluid to and from an accumulator to the pump/motor to achieve the target speed.
1 Assignment
0 Petitions
Accused Products
Abstract
A system and method of dithering speed and/or torque for shifting a transmission of a vehicle having an engine, a reversible, variable displacement hydraulic motor/pump which can be driven by the engine, a hydraulic accumulator supplied by said motor/pump, and at least one reversible hydraulic driving motor for propelling the vehicle supplied with fluid by the hydraulic accumulator and/or by said motor/pump operating as a pump. A transmission unit connects the engine with the variable displacement hydraulic motor/pump during a first mode of operation (city mode) and connects the engine to a vehicle drive wheel during a second mode of operation. The system utilizes stored hydraulic energy to dither the output of the driving motor in order to achieve quick and smooth shifts between city and highway mode, or between various ranges within the city mode.
45 Citations
5 Claims
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1. A method of engaging a transmission of a series hydraulic hybrid system having at least one pump/motor selectively connectable to an output drive shaft of the transmission, the method comprising the steps of:
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calculating a desired speed of an output shaft of the at least one pump/motor; operating the at least one pump/motor at a target speed that is the desired output shaft speed plus a desired speed dither; and engaging the output shaft of the pump/motor with the output shaft of the transmission when the target speed is reached within a prescribed speed error threshold; wherein the operating includes regulating the flow of fluid to and from an accumulator to the pump/motor to achieve the target speed. - View Dependent Claims (2, 3, 4, 5)
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Specification