System and method for engine driveline disconnect during regeneration in hybrid vehicles

Patent metadata

Field	Value
Publication number	US-9738272-B2
Application number	US-201514838393-A
Country	US
Kind code	B2
Filing date	Aug 28, 2015
Priority date	Mar 14, 2013
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A system and method for operating a hybrid vehicle having an engine and an eMachine coupled by a clutch using a hybrid controller is presented. The method determines an idle fuel rate of the engine, determines a hybrid efficiency index for the hybrid vehicle, determines an expected energy storage rate increase for an operating condition where the engine is decoupled from a vehicle transmission using said clutch, multiplies the expected energy storage rate increase by the hybrid efficiency index to determine an expected fuel rate reduction of the engine in the operating condition; and decouples the engine from the vehicle transmission using the clutch if the expected fuel rate reduction is greater than the idle fuel rate.

First claim

The invention claimed is:

1. A method for operating a hybrid vehicle having an eMachine and an engine using a hybrid controller, comprising:
determining an expected fuel rate reduction of the engine at a first time between a first operating condition occurring when the engine is coupled to a vehicle transmission by a clutch, and a second operating condition occurring when the engine is decoupled from the vehicle transmission by the clutch; and
decoupling the engine from the vehicle transmission from the first operating condition to the second operating condition using the clutch at a second time after the first time if the expected fuel rate reduction is greater than an idle fuel rate of the engine;
wherein said determining expected fuel rate reduction comprises determining an expected energy storage rate increase due to a transition from the first to the second operating condition; and
multiplying said expected energy storage rate increase by a hybrid efficiency index.

2. The method of claim 1 , wherein said hybrid efficiency index during a time period T is defined as:

∫
T

⁢

fuelRate
propulsion

-

fuelRate
engine

∫
T

⁢
EnergyStorageDischargeRate

where: fuelRate propulsion =a fuel rate required for the engine to produce a propulsion torque being currently produced by a combination of the engine and the eMachine;
fuelRate engine =a current fuel rate of the engine with the eMachine assisting in the propulsion of the vehicle, and
EnergyStorageDischargeRate=an energy storage discharge rate of an energy storage system of the hybrid vehicle.

3. The method of claim 2 , wherein the hybrid controller adaptively determines said hybrid efficiency index over the time period T.

4. The method of claim 2 , wherein said determining said expected energy storage rate increase comprises:
determining a decoupled energy storage rate, said decoupled energy storage rate representing the energy storage rate when the engine is decoupled from the transmission; and
determining a coupled energy storage rate, said coupled energy storage rate representing the energy storage rate when the engine is coupled to the transmission.

5. The method of claim 4 , wherein said decoupled energy storage rate accounts for the physical limitations of at least one of the eMachine and the energy storage system.

6. The method of claim 4 wherein said decoupled energy storage rate accounts for a current state of charge of the energy storage system.

7. The method of claim 6 , wherein the hybrid controller causes the engine to remain connected to the transmission by the clutch if the current state of charge of the energy storage system is above a predetermined threshold.

8. The method of claim 4 , wherein said decoupled energy storage rate accounts for a maximum energy storage rate limit of the energy storage system.

9. The method of claim 4 , wherein said coupled energy storage rate accounts for a braking effect of the engine when coupled to the transmission.

10. The method claim 1 , wherein the idle fuel rate is determined by the hybrid controller by monitoring an amount of fuel being consumed by the engine when the engine is in an idle operating condition.

11. The method of claim 10 , wherein the idle fuel rate is determined as an average of a fuel rate of the engine measured over a defined period of time.

12. The method of claim 1 , wherein said first and second operating conditions occur during a throttle lift condition.

13. The method of claim 1 , further comprising:
maintaining the engine in an idle condition if the engine is decoupled from the vehicle transmission.

14. A hybrid system, comprising:
an engine;
an eMachine;
a transmission operatively coupled to the eMachine;
a clutch operatively coupling the engine to the transmission; and
a hybrid controller, said hybrid controller configured to:
determine an expected fuel rate reduction of the engine at a first time between a first operating condition occurring when the engine is coupled to the transmission by the clutch and a second operating condition occurring when the engine is decoupled from the transmission by the clutch;
decouple the engine from the vehicle transmission from the first operating condition to the second operating condition using the clutch at a second time after the first time if the expected fuel rate reduction is greater than an idle fuel rate of the engine;
determine an expected energy storage rate increase due to a transition from the first to the second operating condition; and
multiply said expected energy storage rate increase by a hybrid efficiency index to determine the expected fuel reduction rate.

15. The system of claim 14 , wherein said hybrid efficiency index during a time period T is defined as:

∫
T

⁢

fuelRate
propulsion

-

fuelRate
engine

∫
T

⁢
EnergyStorageDischargeRate

where: fuelRate propulsion =a fuel rate required for the engine to produce the same propulsion torque being currently produced by a combination of the engine and the eMachine;
fuelRate engine =a current fuel rate of the engine with the eMachine assisting in the propulsion of the vehicle, and

EnergyStorageDischargeRate=an energy storage discharge rate of the energy storage system.

16. The system of claim 15 , wherein said determining said expected energy storage rate increase stage comprises:
determining a decoupled energy storage rate, said decoupled energy storage rate representing the energy storage rate when the engine is decoupled from the transmission; and
determining a coupled energy storage rate, said coupled energy storage rate representing the energy storage rate when the engine is coupled to the transmission.

17. The system of claim 16 , wherein said decoupled energy storage rate accounts for the physical limitations of at least one of the eMachine and the energy storage system.

18. The system of claim 16 , wherein said decoupled energy storage rate accounts for a current state of charge of the energy storage system.

19. The system of claim 18 , wherein the hybrid controller causes the engine to remain connected to the transmission by the clutch if the current state of charge of the energy storage system is above a predetermined threshold.

20. The system of claim 16 , wherein said decoupled energy storage rate accounts for a maximum energy storage rate limit of the energy storage system.

Assignees

• Allison Transm Inc

Inventors

• West Stephen T
• Rues Aaron

Classifications

• B60W2520/00

  Input parameters relating to overall vehicle dynamics · CPC title

• Y02T10/84

  Data processing systems or methods, management, administration · CPC title

• B60W20/11

  using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance {(utilising navigation and traffic information in the control strategy B60W20/12)} · CPC title

• B60W2530/00

  Input parameters relating to vehicle conditions or values, not covered by groups B60W2510/00 or B60W2520/00 · CPC title

• B60W50/0097

  Predicting future conditions · CPC title