Engine cooling system motor driven vacuum pump

#The present disclosure relates to a vehicle fuel system.

#Vehicles may be fitted with evaporative emission control systems to reduce the release of fuel vapors to the atmosphere. For example, vaporized hydrocarbons (HCs) from a fuel tank may be stored in a fuel vapor canister packed with an adsorbent which adsorbs and stores the vapors. At a later time, when the engine is in operation, the evaporative emission control system allows the vapors to be purged into the engine intake manifold for use as fuel. However, leaks in the emissions control system can inadvertently allow fuel vapors to escape to the atmosphere. Thus, various approaches are used to identify such leaks.

#One such approach for leak detection includes sealing off the fuel tank, canister, and various conduits from atmosphere and applying pressure to the sealed off system, via a vacuum pump for example. Once a threshold pressure has been reached in the system, the pump may be shut off and leaks may be detected based on a rate of bleed-up or bleed-down of the pressure. However, the vacuum pump utilizes a separate motor, thus consuming additional energy and reducing fuel economy.

#FIG. 1 shows a schematic depiction of a vehicle including an engine, a fuel system, and a vacuum pump.

#FIG. 2 is a flow chart illustrating a method for performing a fuel system leak detection test according to an embodiment of the present disclosure.

#FIG. 3 is a diagram illustrating example engine operating parameters during the execution of the method of FIG. 2.

#An existing engine motor, such as a motor to operate an engine cooling fan or cooling pump, may include a clutch coupling the motor to a vacuum pump. When the clutch is engaged, the vacuum pump may be driven by the motor. The vacuum pump may be used to apply negative pressure to a fuel system in order to detect leaks, for example. FIG. 1 is a vehicle including a fuel system and a controller configured to carry out the method of FIG. 2. FIGS. 3 and 4 illustrate various parameters of the leak detection test carried out in FIG. 2.

#FIG. 1 shows a schematic depiction of a vehicle system 6 that can derive propulsion power from engine system 8. Vehicle system 6 may be a conventional vehicle powered solely through combustion, or it may be a hybrid vehicle system that can derive propulsion power from engine system 8 and/or an on-board energy storage device (not shown), such as a battery system. An energy conversion device, such as a generator (not shown), may be operated to absorb energy from vehicle motion and/or engine operation, and then convert the absorbed energy to an energy form suitable for storage by the energy storage device.

#Engine system 8 may include an engine 10 having a plurality of cylinders 30. Engine 10 includes an engine intake 23 and an engine exhaust 25. Engine intake 23 includes an air intake throttle 62 fluidly coupled to the engine intake manifold 44 via an intake passage 42. Air may enter intake passage 42 via air filter 52. Engine exhaust 25 includes an exhaust manifold 48 leading to an exhaust passage 35 that routes exhaust gas to the atmosphere. Engine exhaust 25 may include one or more emission control devices 70 mounted in a close-coupled position. The one or more emission control devices may include a three-way catalyst, lean NOx trap, diesel particulate filter, oxidation catalyst, etc. It will be appreciated that other components may be included in the engine such as a variety of valves and sensors, as further elaborated in herein. In some embodiments, wherein engine system 8 is a boosted engine system, the engine system may further include a boosting device, such as a turbocharger (not shown).