Method for limiting fuel leakage from an injector after stoppage of the engine by means of forced cooling of the injection rail

Patent metadata

Field	Value
Publication number	US-10132280-B2
Application number	US-201715488579-A
Country	US
Kind code	B2
Filing date	Apr 17, 2017
Priority date	Apr 25, 2016
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

Disclosed is a method for limiting fuel leakage from at least one injector in an engine of a motor vehicle, the engine being stopped and the motor vehicle ignition circuit being switched off, the injector being supplied with fuel via a fuel rail which is pressurized during operation, the pressurization persisting for a certain period when the engine has been stopped and the ignition circuit switched off, leading to leakage of fuel through the injector. The injection rail is subjected to forced cooling following the stoppage of the engine with the motor vehicle ignition circuit switched off, which is sufficient to reduce the pressure, the forced cooling continuing until the pressure in the rail is close to atmospheric pressure.

First claim

The invention claimed is:

1. Method for limiting fuel leakage from at least one injector in an internal combustion engine of a motor vehicle, the engine being stopped and the motor vehicle ignition circuit being switched off, said at least one injector being supplied with fuel via a fuel rail which is pressurized during operation, the pressurization persisting for a certain period when the engine has been stopped and the ignition circuit switched off, leading to fuel leakage from the injector, wherein the injection rail is subjected to forced cooling following the stoppage of the engine with the motor vehicle ignition circuit switched off, which is sufficient to reduce the rail temperature (Trail), the forced cooling continuing until the pressure (Prail or Pcarb) in the rail is close to atmospheric pressure.

2. Method according to claim 1 , wherein a temperature (Trail_stop) prevailing in the injection rail after stoppage of the engine is estimated or measured, and when this measured or estimated temperature (Trail_stop) of the injection rail is significantly higher than the ambient temperature (Tamb), the forced cooling consists of a ventilation of air approximately at ambient temperature (Tamb) towards the injection rail, or when this measured or estimated temperature (Trail_stop) of the injection rail is not significantly higher than the ambient temperature (Tamb), the forced cooling consists of an exchange of heat between the injection rail and a refrigerant fluid derived from a cooling loop when such a loop is present in the motor vehicle, where applicable combined with forced cooling by air ventilation.

3. Method according to claim 2 , wherein, when the temperature (Trail_stop) prevailing in the injection rail is estimated after stoppage of the engine, the temperature of the injection rail (Trail_stop) is estimated from the temperature of a cooling fluid (TCO_stop) circulating in a cooling system of the internal combustion engine of the vehicle after stoppage of the engine.

4. Method according to claim 2 , wherein a temperature is predefined which is as a function of the fuel pressure (TPcarb_stop) on stoppage of the engine, and
when the difference between the measured or estimated temperature (Trail_stop or TCO_stop) of the injection rail and the ambient temperature (Tamb) at a given instant, following stoppage of the engine with the ignition circuit switched off, is greater than the predefined temperature as a function of the fuel pressure on stoppage (TPcarb_stop), said forced cooling is carried out by ventilation of air approximately at ambient temperature (Tamb) towards the cooling rail, whereas
when the difference between the measured or estimated temperature (Trail_stop or TCO_stop) of the injection rail and the ambient temperature (Tamb) at this given instant is less than the predefined temperature as a function of the fuel pressure on stoppage (TPcarb_stop), said forced cooling is carried out by refrigerant fluid derived from the cooling loop, when such a loop is present.

5. Method according to claim 2 , wherein a threshold pressure for stoppage of cooling (PS_arr_refr) is defined, and when the pressure difference between the rail pressure (Prail or Pcarb) and the atmospheric pressure (Patmo) at a given instant, after stoppage of the engine with the ignition circuit switched off, is less than or equal to the threshold pressure for stoppage of cooling (PS_arr_refr), the cooling is stopped.

6. Method according to claim 2 , wherein a first maximum cooling time (tps_max 1 ) associated with said forced cooling by air ventilation, and a second maximum cooling time (tps_max 2 ) associated with said forced cooling by refrigerant fluid are defined, and if an active forced cooling time (trefr), counting from the start of cooling up to a given instant, is greater than the first maximum cooling time (tps_max 1 ) or the second maximum cooling time (tps_max 2 ), the forced cooling by air ventilation or by refrigerant fluid respectively is stopped.

7. Method according to claim 1 , which is controlled by a computer on board the vehicle, the computer being kept in operation on stoppage of the engine with the ignition circuit switched off in the vehicle in order to supervise said forced cooling, the computer being kept in operation until the forced cooling ceases.

8. Motor vehicle comprising a power unit comprising an internal combustion engine with at least one cylinder, an injector being associated with the cylinder for supplying fuel to said at least one cylinder, the fuel being delivered to the injector by an injection rail which is pressurized during operation, wherein when the engine is stopped and the ignition circuit switched off in the vehicle, the injection rail is subjected to a forced cooling by first cooling means comprising one or more ducts for ventilation of air towards the injection rail, and/or second cooling means comprising a branch for circulation of a refrigerant fluid towards the injection rail, the forced cooling being controlled by a computer on board the motor vehicle and operated according to a method according to claim 1 .

9. Motor vehicle according to claim 8 which is fitted with a motorized fan assembly equipped with one or more fans for cooling the fluid circulating in a cooling system of the internal combustion engine, one or more of the air ventilation ducts of the first cooling means directing air from the fan or fans of the motorized fan assembly towards the injection rail, the air ventilation duct or ducts being equipped with a passage valve which closes or opens the circulation of air in the ducts, the passage valve being controlled by the computer.

10. Motor vehicle according to claim 8 which is fitted with a cab air conditioning system using a refrigerant fluid, at least one branch derived from the system taking the refrigerant fluid from the system for cooling the injection rail, said at least one branch comprising a passage valve controlled by the computer.

11. Method according to claim 3 , wherein a temperature is predefined which is as a function of the fuel pressure on stoppage of the engine, and
when the difference between the measured or estimated temperature of the injection rail and the ambient temperature at a given instant, following stoppage of the engine with the ignition circuit switched off, is greater than the predefined temperature as a function of the fuel pressure on stoppage, said forced cooling is carried out by ventilation of air approximately at ambient temperature towards the cooling rail, whereas when the difference between the measured or estimated temperature of the injection rail and the ambient temperature at this given instant is less than the predefined temperature as a function of the fuel pressure on stoppage, said forced cooling is carried out by refrigerant fluid derived from the cooling loop, when such a loop is present.

12. Method according to claim 3 , wherein a threshold pressure for stoppage of cooling is defined, and when the pressure difference between the rail pressure (Prail or Pcarb) and the atmospheric pressure at a given instant, after stoppage of the engine with the ignition circuit switched off, is less than or equal to the threshold pressure for stoppage of cooling, the cooling is stopped.

13. Method according to claim 4 , wherein a threshold pressure for stoppage of cooling is defined, and when the pressure difference between the rail pressure (Prail or Pcarb) and the atmospheric pressure at a given instant, after stoppage of the engine with the ignition circuit switched off, is less than or equal to the threshold pressure for stoppage of cooling, the cooling is stopped.

1

Assignees

• Continental Automotive France
• Continental Automotive Gmbh

Inventors

• Serrecchia Philippe

Classifications

• F02M55/02

  Conduits between injection pumps and injectors {, e.g. conduits between pump and common-rail or conduits between common-rail and injectors} · CPC title

• F02M53/00 Primary

  Fuel-injection apparatus characterised by having heating, cooling or thermally-insulating means · CPC title

• F01P7/16

  by thermostatic control · CPC title

• F01P2060/10

  Fuel manifold · CPC title

• F01P7/026

  Thermostatic control · CPC title