Vehicle system with hydromechanical transmission and power management strategy
Methods and systems for a hydromechanical transmission. In one example, a vehicle system includes a hydromechanical transmission with a power-take off (PTO) that is designed to rotationally couple to an implement. The vehicle system further includes an engine coupled to the hydromechanical transmission and a power-management control unit configured to, during a drive or coast condition, cause the power-management control unit to: determine a net available power for the hydromechanical transmission and manage a power flow between the hydromechanical transmission, a drive axle, and the implement based on the net available power.
1. A transmission system, comprising:
a hydromechanical transmission configured to rotationally couple to a motive power source;
a power-take off (PTO) configured to rotationally couple to an implement; and
a power-management control unit in electronic communication with a vehicle control unit (VCU), an engine control unit (ECU), and an implements control unit (ICU) and including instructions that when executed, during a drive condition or a coast condition, cause the power-management control unit to:
receive power data from the VCU, the ECU, and the ICU;
determine a net available power for the hydromechanical transmission based on the power data; and
manage a power flow between the hydromechanical transmission, a drive axle, and the implement based on the net available power, a transmission power limit, an implement power limit, and a priority value;
wherein the priority value is a portion of the net available power to which the hydromechanical transmission is constrained;
wherein the transmission power limit and the implement power limit are adjusted based on a transmission traction request condition, an implement request condition, and a mixed transmission traction request and implement request condition; and
wherein during the mixed transmission traction request and implement request condition, the implement power limit is reduced based on the priority value and increased based on a proportional integral (PI) controller term.
2. The transmission system of claim 1 , wherein the motive power source is an engine.
3. The transmission system of claim 2 , wherein the hydromechanical transmission includes two forward drive clutches and a reverse drive clutch.
4. The transmission system of claim 2 , wherein the engine is a compression ignition engine.
5. The transmission system of claim 1 , wherein the hydromechanical transmission includes a hydrostatic assembly with a hydraulic pump and a hydraulic motor.
6. The transmission system of claim 1 , wherein the net available power includes a net positive available power value and a net negative available power value.
7. The transmission system of claim 1 , wherein the hydromechanical transmission is a hydromechanical variable transmission (HVT).
8. The transmission system of claim 7 , wherein the HVT has an asymmetric number of forward drive ranges and reverse drive ranges.
9. A method for managing power in a vehicle system, comprising:
at a power-management control unit, receiving power data from one or more of an engine control unit (ECU), a vehicle control unit (VCU), and an implement control unit (ICU);
determining a net available power for a hydromechanical transmission based on the power data; and
managing a power flow between the hydromechanical transmission, a drive axle, and an implement based on the net available power, a transmission power limit, an implement power limit, and a priority value;
wherein the priority value is a portion of the net available power to which the hydromechanical transmission is constrained;
wherein the transmission power limit and the implement power limit are adjusted based on a transmission traction request condition, an implement request condition, and a mixed transmission traction request and implement request condition; and
wherein during the transmission traction request condition the implement power limit is reduced based on the priority value.
10. The method of claim 9 , wherein during the implement request condition the transmission power limit is equal to the priority value.
11. The method of claim 9 , wherein during the mixed transmission traction request and implement request condition the implement power limit is reduced based on the priority value and increased based on a proportional integral (PI) controller term.
12. The method of claim 9 , wherein the priority value is adjustable.
13. A transmission system, comprising:
a hydromechanical variable transmission (HVT) configured to rotationally couple to an internal combustion engine;
a power-take off (PTO) configured to rotationally couple to an implement; and
a power-management control unit in electronic communication with a vehicle control unit (VCU), an engine control unit (ECU), and an implement control unit (ICU) and including instructions that when executed, during a drive condition or a coast condition, cause the power-management control unit to:
receive power data from the VCU, the ECU, and the ICU;
determine a net available power for the HVT based on the power data; and
manage a power flow between the HVT, a drive axle, and the implement based on the net available power, a transmission power limit, an implement power limit, and a priority value;
wherein the priority value is a portion of the net available power to which the HVT is constrained;
wherein the transmission power limit and the implement power limit are adjusted based on a transmission traction request condition, an implement request condition, and a mixed transmission traction request and implement request condition; and
wherein during the transmission traction request condition the implement power limit is reduced based on the priority value.
14. The transmission system of claim 13 , wherein during the implement request condition the transmission power limit is equal to the priority value.
15. The transmission system of claim 13 , wherein during the mixed transmission traction request and implement request condition, the implement power limit is reduced based on the priority value and increased based on a proportional integral (PI) controller term.
16. The transmission system of claim 13 , wherein the priority value is adjustable.