Method and system for boost pressure control

Patent metadata

Field	Value
Publication number	US-10502122-B2
Application number	US-201815894752-A
Country	US
Kind code	B2
Filing date	Feb 12, 2018
Priority date	May 20, 2016
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

Methods and systems are provided for controlling boost pressure in a staged engine system comprising a turbocharger and an upstream electric supercharger. In one example, a method may include accelerating an electric supercharger to choke the flow of air to the engine in the event of turbocharger overboost.

First claim

The invention claimed is:

1. A method for operating a vehicle system, comprising:
bypassing a first, upstream compressor and providing a flow of compressed air to a direct injection piston engine via a second, downstream compressor, at least one of the compressors driven by an electric motor electrically coupled with a battery;
in response to a boost pressure overshoot, adjusting speed of the first compressor; and
in response to an indication of degradation of a compressor bypass valve, adjusting an actuator with a default tuning.

2. The method of claim 1 , further comprising, accelerating the first compressor while maintaining an intake throttle open until an airflow through the second compressor is below a threshold, and then decelerating the first compressor.

3. The method of claim 2 , wherein the first compressor is driven by the electric motor and the second compressor is driven by an exhaust turbine, and wherein adjusting the speed of the first compressor includes spinning the motor at a motor speed based on the airflow.

4. The method of claim 3 , wherein the bypassing the first compressor is responsive to a turbine speed being higher than a threshold speed.

5. The method of claim 1 , wherein the boost pressure overshoot includes a boost error between a desired boost pressure and an actual boost pressure, and wherein accelerating the first compressor includes estimating a desired pressure ratio across the second compressor based on the boost error, determining a desired airflow into the second compressor based on the desired pressure ratio, and then operating the first compressor at a compressor speed that lowers an airflow into the second compressor to the desired airflow.

6. The method of claim 5 , wherein the compressor speed of the first compressor is further adjusted based on a position of an intake throttle located upstream of the first compressor.

7. The method of claim 5 , further comprising, in response to the boost pressure overshoot, opening one or more of an exhaust wastegate valve positioned in a wastegate coupled across the exhaust turbine, and a compressor recirculation valve positioned in a recirculation passage coupled across the second compressor.

8. The method of claim 7 , wherein opening the exhaust wastegate valve includes adjusting a degree of opening of the wastegate valve responsive to the boost error with a higher than default tuning, and resuming the default tuning in response to one or more of boost error being less than a threshold and boosted engine component degradation.

9. A method for a boosted engine, comprising:
responsive to a first increase in driver demand, accelerating a first, upstream compressor to increase airflow through a second, downstream compressor;
responsive to a second increase in driver demand, adjusting speed of the first, upstream compressor to decrease airflow through the second, downstream compressor; and
adjusting operation of the first compressor based on an altitude of vehicle operation of a vehicle in which the boosted engine is positioned.

10. The method of claim 9 , wherein the engine is a direct injection engine.

11. The method of claim 10 , wherein an actuator of a turbine coupled to the second compressor is coupled to a vacuum source, and wherein the accelerating of the first compressor is continued until a vacuum level in the vacuum source is above a threshold.

12. The method of claim 11 , wherein the threshold is based on the altitude of vehicle operation, the threshold lowered as the altitude increases.

13. The method of claim 12 , wherein the first increase in driver demand includes a tip-in event from closed pedal, and wherein the second increase in driver demand includes a tip-in event from partial pedal depression.

14. The method of claim 12 , wherein during the first increase in driver demand, airflow through the second compressor is below a threshold flow, and wherein during the second increase in driver demand, airflow through the second compressor is above the threshold flow.

15. The method of claim 12 , wherein during the first increase in driver demand, accelerating the first compressor includes spinning the first compressor at a first speed based on the first increase in driver demand, and wherein during the second increase in driver demand, accelerating the first compressor includes spinning the first compressor at a second speed based on a current airflow into the second compressor relative to a desired compressor pressure ratio, the desired compressor pressure ratio based on the second increase in driver demand.

16. The method of claim 12 , wherein the first compressor is a supercharger compressor driven by an electric motor, and wherein the second compressor is a turbocharger compressor driven by an exhaust turbine.

17. The method of claim 16 , wherein during the first increase in driver demand, a turbine speed is lower than a threshold turbine speed and the first compressor is not spinning, and wherein during the second increase in driver demand, the turbine speed is higher than the threshold turbine speed and the first compressor is spinning.

18. The method of claim 16 , further comprising, during the first increase in driver demand, increasing an opening of a bypass valve coupled in a bypass across the first compressor, and during the second increase in driver demand, increasing an opening of one or more of a wastegate valve coupled in a wastegate passage across the exhaust turbine and a recirculation valve in coupled in a recirculation passage across the second compressor.

19. The method of claim 18 , further comprising, during the first increase in driver demand, operating the bypass valve with a higher than default gain tuning and the wastegate valve with a default gain tuning, and during the second increase in driver demand, operating the bypass valve with the default gain tuning and the wastegate valve with the higher than default gain tuning.

20. An engine system, comprising:
a direct injection engine having an intake;
a first intake compressor driven by an electric motor, the motor powered by a battery;
a second intake compressor driven by an exhaust turbine, the second compressor positioned downstream of the first compressor along the intake;
a bypass including a bypass valve coupled across the first compressor;
a wastegate including a wastegate valve coupled across the exhaust turbine; and
a controller with computer readable instructions stored on non-transitory memory for:
in response to an operator pedal tip-in while the second compressor is spinning,
closing the wastegate valve to adjust a speed of the second compressor; and
concurrently adjusting a speed of the first compressor to limit airflow into the second compressor, wherein operation of the first compressor is further adjusted based on an altitude of operation of the engine system.

Assignees

• Ford Global Tech Llc

Inventors

• Xiao Baitao
• Ossareh Hamid-Reza
• Banker Adam Nathan

Classifications

• F02B37/14

  {Control} of the alternation between {or the operation of} exhaust drive and other drive of a pump, e.g. dependent on speed · CPC title

• F02B37/162 Primary

  by bypassing, e.g. partially, intake air from pump inlet to pump outlet · CPC title

• F02B37/16

  by bypassing charging air · CPC title

• F02D2200/602

  Pedal position · CPC title

• F02B2037/122

  Control of rotational speed of the pump · CPC title