Methods and systems for port fuel injection control

Patent metadata

Field	Value
Publication number	US-2016377019-A1
Application number	US-201615135308-A
Country	US
Kind code	A1
Filing date	Apr 21, 2016
Priority date	Jun 29, 2015
Publication date	Dec 29, 2016
Grant date	—

Abstract

Methods and systems are provided for reducing hot fuel vapor formation in a port injection fuel rail. In one example, a method may include operating a dual fuel injection system with at least a calibrated minimum amount of port fuel injection over a wide range of engine operating conditions, even as conditions change. A direct fuel injection amount is adjusted in accordance.

First claim

1 . An engine method, comprising:
during a non-degradation mode of a fuel system,
pressurizing fuel in each of a port injection fuel rail and a direct injection fuel rail via an engine-driven high pressure fuel pump; and
fueling the engine with at least a calibrated minimum amount greater than zero of port injected fuel for every combustion event.

2 . The method of claim 1 , wherein the fueling with at least a calibrated minimum amount is performed independent of a measured fuel temperature of the port injection fuel rail and over any and every warmed-up operating condition while in the non-degradation mode.

3 . The method of claim 1 , wherein the fueling includes maintaining port fuel injection at the calibrated minimum amount as engine speed and load conditions change within a first range of engine speed-load conditions, the first range including engine speed above a first threshold speed and engine load above a first threshold load.

4 . The method of claim 3 , further comprising, transitioning port fuel injection from the calibrated minimum amount to a first amount responsive to a change in engine speed and load conditions from the first range to a second range, the second range including engine load below the first threshold load, and engine speed above a second threshold speed, higher than the first threshold speed, the first amount higher than the calibrated minimum amount, wherein the transitioning includes delivering an amount of fuel via port injection, the amount linearly extrapolated between the calibrated minimum amount of the first range and the first amount of the second range.

5 . The method of claim 4 , further comprising, transitioning port fuel injection from the calibrated minimum amount to a second amount responsive to a change in engine speed and load conditions from the first range to a third range, the third range including engine load above a second threshold load, higher than the first threshold load, and engine speed above a third threshold speed, higher than the second threshold speed, the second amount lower than the first amount and higher than the calibrated minimum amount.

6 . The method of claim 5 , further comprising, transitioning from fueling the engine with the calibrated minimum amount of port injected fuel to fueling the engine with fuel delivered via port injection only in a fourth range, the fourth range including engine speed below the second threshold speed and engine load below a third threshold load, lower than the first threshold load.

7 . The method of claim 1 , wherein the calibrated minimum amount of port injected fuel is based on a modeled fuel temperature of the port injection fuel rail and determined independent of a measured fuel temperature of the port injection fuel rail.

8 . The method of claim 1 , further comprising, during a degradation mode of the fuel system, operating the engine with only port injected fuel and engine torque limited to a first level when the degradation mode is responsive to direct injector degradation, and operating the engine with only direct injected fuel and engine torque limited to a second level, higher than the first level, when the degradation mode is responsive to port injector degradation.

9 . The method of claim 1 , further comprising, delivering a remainder of a total fuel injection amount via direct injection and changing a ratio of fuel delivered via port fuel injection relative to direct fuel injection at a given engine speed, as engine load increases from a minimum load to a maximum load, while maintaining the port fuel injection at least at the minimum calibrated amount.

10 . The method of claim 1 , further comprising, in response to deceleration fuel shut-off conditions being met, stopping fuel injection via each of a port injector coupled to the port injection fuel rail, and a direct injector coupled to the direct injection fuel rail, and re-enabling cylinder combustion based on a driver demand increase during a first condition, and during a second condition, re-enabling combustion in response to an estimated fuel rail temperature, without a driver demand increase.

11 . A method for a dual fuel injection system, comprising:
during conditions when fuel is requested via direct injection only; overriding the fuel request and delivering fuel as a first calibrated minimum amount of port injected fuel and a second, remaining amount of direct injected fuel.

12 . The method of claim 11 , further comprising, changing a ratio of the first amount relative to the second amount at a given engine speed, as engine load increases from a minimum load to a maximum load, while maintaining the first calibrated minimum amount of port injected fuel.

13 . The method of claim 12 , wherein the changing includes changing from a first ratio at the given engine speed and the minimum load to a second, different ratio at the given engine speed and the maximum load, each of the first ratio and the second ratio including at least the first calibrated minimum amount of port injected fuel.

14 . The method of claim 11 , further comprising, changing a ratio of the first amount relative to the second amount at a given engine load, as engine speed increases from a minimum speed to a maximum speed, while maintaining the port fuel injection at least at the first calibrated minimum amount of port injected fuel.

15 . The method of claim 14 , wherein the changing includes changing from a first ratio at the given engine load and the minimum speed to a second, different ratio at the given engine load and the maximum speed, each of the first ratio and the second ratio including at least the first calibrated minimum amount of port injected fuel.

16 . The method of claim 11 , wherein the conditions include a non-degradation mode of the fuel injection system and the engine being warmed up.

17 . The method of claim 11 , further comprising:
modeling a fuel temperature of the port injection fuel rail; and estimating the calibrated minimum amount of port injected fuel based on the modeled fuel temperature.

18 . A method for a dual fuel injection enabled engine, comprising:
over any and every engine non-starting operating condition, fueling the engine with at least a calibrated minimum amount of port injected fuel; and only partially fueling the engine with direct injected fuel over engine operating conditions.

19 . The method of claim 18 , further comprising: in response to an engine speed-load transition,
fueling the engine with more than the calibrated minimum amount of port injected fuel; and correspondingly decreasing fueling of the engine via direct injection.

20 . The method of claim 19 , wherein fueling the engine with more than the calibrated minimum amount of port injected fuel includes:
fueling the engine with only port injected fuel; and not fueling the engine with direct injected fuel.

Assignees

• Ford Global Tech Llc

Inventors

• Russ Stephen George
• Thomas Joseph Lyle
• Lehto Scott Allan
• Woodring Christopher Arnold
• Wei Jeanne
• Shelley David

Classifications

• F02M35/104

  Intake manifolds · CPC title

• F02D2041/3881

  with multiple common rails, e.g. one rail per cylinder bank, or a high pressure rail and a low pressure rail · CPC title

• F02D41/221

  relating to the failure of actuators or electrically driven elements · CPC title

• F02D41/38 Primary

  of the high pressure type · CPC title

• F02D41/3094 Primary

  the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder · CPC title