Method of using feedforward compensation based on pressure feedback for controlling swash plate angle in a hydrostatic power unit of a continuously variable transmission

Patent metadata

Field	Value
Publication number	US-9550490-B2
Application number	US-201214239929-A
Country	US
Kind code	B2
Filing date	Aug 27, 2012
Priority date	Aug 25, 2011
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A swash plate angle for a hydrostatic power unit of a continuously variable hydromechanical transmission is determined using a feedforward compensation term, to reduce reliance on closed loop control. The feedforward term is based on knowledge of the hydrostatic power unit determined as a function of knowledge of certain parameters, including, but not limited to, hydrostatic power unit pressure, swash plate angle, desired hydrostatic power unit ratio, and pump speed.

First claim

What is claimed is:

1. A method for automatically controlling an angle of a swash plate of a hydrostatic power unit of a continuously variable hydro-mechanical transmission, the method comprising:
determining, with a processor-based controller, a desired hydrostatic reciprocal ratio of the hydrostatic drive unit based on a desired transmission reciprocal ratio for the transmission;
determining, with the processor-based controller, a feedforward control term based on the desired hydrostatic reciprocal ratio of the hydrostatic power unit, a pump speed for the hydrostatic power unit, and a pressure for the hydrostatic power unit;
determining, with the processor-based controller, a closed-loop control term based on an error calculated as a function of the desired hydrostatic reciprocal ratio;
calculating, with the processor-based controller, a swash plate command based on the feedforward control term and the closed-loop control term; and
transmitting, with the processor-based controller, the swash plate command for adjusting the angle of the swash plate.

2. The method of claim 1 , wherein the pressure corresponds to an estimated pressure for the hydrostatic power unit, the estimated pressure being determined as a function of at least a calculated driveline torque for the transmission, and the pump speed.

3. The method of claim 1 , wherein the close-loop control term is determined by the processor-based controller implementing a PID control loop.

4. The method of claim 1 , wherein the desired hydrostatic reciprocal ratio is defined as a motor speed for the hydrostatic power unit divided by the pump speed.

5. A method for automatically controlling an angle of a swash plate of a hydrostatic power unit of a continuously variable hydro-mechanical transmission, the method comprising:
determining, with a processor-based controller, a desired hydrostatic reciprocal ratio of the hydrostatic drive unit based on a desired transmission reciprocal ratio for the transmission;
determining, with the processor-based controller, a feedforward control term based on the desired hydrostatic reciprocal ratio and an estimated pressure for the hydrostatic power unit;
determining, with the processor-based controller, a closed-loop control term based on an error calculated as a function of the desired hydrostatic reciprocal ratio;
calculating, with the processor-based controller, a swash plate command based on the feedforward control term and the closed-loop control term; and
transmitting, with the processor-based controller, the swash plate command for adjusting the angle of the swash plate.

6. The method of claim 5 , wherein the feedforward term is additionally determined as a function of a pump speed for the hydrostatic power unit.

7. The method of claim 5 , wherein the estimated pressure of the hydrostatic power unit is determined as a function of at least a calculated driveline torque value for the transmission, and a pump speed for the hydrostatic power unit.

8. The method of claim 5 , wherein the desired hydrostatic reciprocal ratio is defined as a motor speed for the hydrostatic power unit divided by a pump speed for the hydrostatic power unit.

Assignees

• Guo Haibo
• Dix Peter J
• Bulgrien Garth H
• Hartman Brian A
• Prasse Robert C
• Weeramantry Cecil A
• Felsing Brian E
• Cnh Ind America Llc

Inventors

• Guo Haibo
• Dix Peter J
• Bulgrien Garth H
• Hartman Brian A
• Prasse Robert C
• Weeramantry Cecil A
• Felsing Brian E

Classifications

• F16H2059/6861

  the pressures, e.g. high, low or differential pressures · CPC title

• F16H61/462

  for achieving a target speed ratio · CPC title

• F16H2059/6853

  the state of the transmission units, i.e. motor or pump capacity, e.g. for controlled shifting of range gear · CPC title

• F16H2059/6869

  the pump speed · CPC title

• B60W10/30 Primary

  including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps · CPC title