A fuel delivery system for a vehicle engine and a method are provided. A first valve in parallel with a first fuel pump fluidly couples a fuel line to a fuel tank. A second valve in parallel with a second fuel pump fluidly couples a fuel rail to the fuel line. A controller opens the first and second valves during a vehicle key-off state to relieve pressure in the fuel rail and drain fuel into the fuel tank. A vehicle is provided with a fuel tank, and a valve fluidly coupling a fuel rail and a fuel tank. A controller opens the valve during a vehicle key-off state to drain fuel from the fuel rail into the fuel tank and relieve pressure in the fuel rail, and closes the valve in response to a predicted key-on event during the vehicle key-off state.

Examples are provided for switching an engine fuel supply. One example system includes a direct-injection engine including a cylinder, an LPG tank for storing a LPG fuel, a CNG tank for storing a CNG fuel, a gas switching valve, a high-pressure pump connected between the LPG tank and the gas switching valve, a pressure-limiting valve connected between the CNG tank and the gas switching valve, a fuel distributor configured to be supplied with one or more of the LPG fuel and the CNG fuel via the gas switching valve, an LPG injection valve coupled to the cylinder, a CNG injection valve coupled to the cylinder, the LPG injection valve and the CNG injection valve configured to be supplied with fuel via the fuel distributor; and a controller configured to control the gas switching valve depending on an aggregate state of the fuel disposed in the fuel distributor.

The invention relates to a fuel-pumping device (1) for a fuel injection device of an internal combustion engine with a large high-pressure pump (16) and a small high-pressure pump (14) arranged in parallel, wherein fuel can be pumped by the large high-pressure pump (16) and by the small high-pressure pump (14) from a low-pressure region (13) into a high-pressure region (18). The high-pressure region (18) is connected to at least one injector (21). A control device (30) is provided, which can be used to conduct the entire pump output of the large high-pressure pump (16) or the small high-pressure pump (14) into the low-pressure region (13) via a discharge line (15).

A fuel supply system, having a low-pressure region, a high-pressure region, a pumping device, a low-pressure pump, and a high-pressure pump A pressure accumulator system is provided between the pumping device and injectors and has distributor units. Between the low-pressure pump and the high-pressure pump, a fuel distributor block is provided, which has a fuel leakage collection line for fuel leakage supplied to the fuel distributor block that has a choke and a bypass around the choke and a leakage sensor in the bypass. The choke is dimensioned such that all fuel leakage flows through the choke if the fuel leakage conducted via the fuel leakage collection line is less than a limit value, and fuel leakage flows through the bypass and across the leakage sensor if the fuel leakage conducted via the fuel leakage collection line is greater than the limit value.

The invention relates to a fuel-pumping device (1) for a fuel injection device of an internal combustion engine with a large high-pressure pump (16) and a small high-pressure pump (14) arranged in parallel, wherein fuel can be pumped by the large high-pressure pump (16) and by the small high-pressure pump (14) from a low-pressure region (13) into a high-pressure region (18). The high-pressure region (18) is connected to at least one injector (21). A control device (30) is provided, which can be used to conduct the entire pump output of the large high-pressure pump (16) or the small high-pressure pump (14) into the low-pressure region (13) via a discharge line (15).

A gasoline fuel supply system includes a feed pump part, an inline pump part, and a high-pressure pump part. The feed pump part includes a non-positive displacement electric pump, and pumps a gasoline fuel from a fuel tank and discharges at a feed pressure. The inline pump part includes a non-positive displacement mechanical pump, and pressurizes the gasoline fuel discharged from the feed pump part and discharges at a middle pressure. The high-pressure pump part includes a positive displacement mechanical pump, and pressurizes the gasoline fuel discharged from the inline pump part and discharges at a supply pressure to a fuel injection valve.

A fuel pump for conveying fuel includes a conveying unit having a cylinder, a plunger received in the cylinder, a pump spring received in the cylinder, an inner sleeve connected to the plunger, an outer sleeve in contact with the pump spring and in contact with a roller of a cam mechanism, and a locking bolt configured to detachably connect the inner and outer sleeves.

A gasoline fuel supply system includes a feed pump part, an inline pump part, and a high-pressure pump part. The feed pump part includes a non-positive displacement electric pump, and pumps a gasoline fuel from a fuel tank and discharges at a feed pressure. The inline pump part includes a non-positive displacement mechanical pump, and pressurizes the gasoline fuel discharged from the feed pump part and discharges at a middle pressure. The high-pressure pump part includes a positive displacement mechanical pump, and pressurizes the gasoline fuel discharged from the inline pump part and discharges at a supply pressure to a fuel injection valve.

Examples are provided for switching an engine fuel supply. One example system includes a direct-injection engine including a cylinder, an LPG tank for storing a LPG fuel, a CNG tank for storing a CNG fuel, a gas switching valve, a high-pressure pump connected between the LPG tank and the gas switching valve, a pressure-limiting valve connected between the CNG tank and the gas switching valve, a fuel distributor configured to be supplied with one or more of the LPG fuel and the CNG fuel via the gas switching valve, an LPG injection valve coupled to the cylinder, a CNG injection valve coupled to the cylinder, the LPG injection valve and the CNG injection valve configured to be supplied with fuel via the fuel distributor; and a controller configured to control the gas switching valve depending on an aggregate state of the fuel disposed in the fuel distributor.

In a high pressure pump in a system for fuel injection in a combustion engine, determining whether a predetermined partial load operating condition prevails in the combustion engine, at which one single of several pump elements (10) in the high pressure pump is capable of alone delivering a fuel pressure requested in an accumulator tank (6), according to a first reference value, and to achieve a reproducible increase of the fuel pressure to a second reference value. If applicable, the high pressure pump's pump elements are controlled so that one single pump element alone delivers the fuel pressure in the accumulator tank according to the first reference value, whereupon this reference value is changed to the second reference value, and the actual development of the pressure in the accumulator tank as a function of time is determined, and compared with stored values of similar developments for the determination of information regarding the pump element's performance ability.