A method for operating a fuel feed pump, the fuel feed pump having a pump system and an electrically commutated electric motor, the pump system being drivable by the electric motor, includes: detecting fluctuation in circular motion of the pump system over a rotational speed of the pump system to obtain a value of the fluctuation; standardizing the detected value of the fluctuation to obtain a standardized valise; and in a case in which a predefinable limit is exceeded by the standardized value, limiting a gradient of change in the rotational speed of the pump system.

The present invention relates to a fuel pump (1) which comprises a pump housing (2), a delivery element (3) for delivering fuel, a heat-generating actuator (4) for actuating the delivery element (3), a first fuel path (5) which leads from an inlet (20) to a delivery space (7), and a second fuel path (6) which leads from the inlet (20) past the heat-generating actuator (4) to a first housing opening (21), wherein the first housing opening (21) is arranged above the inlet (20) in the vertical direction (V). The present invention also relates to a fuel pump arrangement which comprises a fuel pump (1) according to the invention and a fuel tank (10) in which the fuel pump (1) is at least partially and preferably entirely arranged. The present invention also relates to a method for operating a fuel pump (1).

The present invention relates to a fuel pump (1) which comprises a pump housing (2), a delivery element (3) for delivering fuel, a heat-generating actuator (4) for actuating the delivery element (3), a first fuel path (5) which leads from an inlet (20) to a delivery space (7), and a second fuel path (6) which leads from the inlet (20) past the heat-generating actuator (4) to a first housing opening (21), wherein the first housing opening (21) is arranged above the inlet (20) in the vertical direction (V). The present invention also relates to a fuel pump arrangement which comprises a fuel pump (1) according to the invention and a fuel tank (10) in which the fuel pump (1) is at least partially and preferably entirely arranged. The present invention also relates to a method for operating a fuel pump (1).

The present invention relates to a fuel pump for pumping fuel, comprising a piston (2) and a diaphragm seal element (3), which seals on an inner annular seal seat (4) and an outer annular seal seat (5), wherein the following equation is satisfied: (Ra.sup.2ra.sup.2)/(ri+L).sup.2=ra/ri, where ri is the inner radius of the inner seal seat (4), ra is the inner radius of the outer seal seat (5), Ra is the outer diameter of the piston (2) and L is a difference between an outer radius (Ria) of the inner seal seat (4) and the inner radius (ri) of the inner seal seat (4). The invention further relates to a method for operating a fuel pump.

The present invention relates to a fuel pump for pumping fuel, comprising a piston (2) and a diaphragm seal element (3), which seals on an inner annular seal seat (4) and an outer annular seal seat (5), wherein the following equation is satisfied: (Ra.sup.2ra.sup.2)/(ri+L).sup.2=ra/ri, where ri is the inner radius of the inner seal seat (4), ra is the inner radius of the outer seal seat (5), Ra is the outer diameter of the piston (2) and L is a difference between an outer radius (Ria) of the inner seal seat (4) and the inner radius (ri) of the inner seal seat (4). The invention further relates to a method for operating a fuel pump.

An energy-storing-type high-pressure electric fuel pump comprises an electromagnetic driving apparatus and a plunger sleeve cylinder component. The plunger sleeve cylinder component comprises a high-pressure volume, a plunger sleeve having a plunger hole, and a plunger capable of sliding within the plunger hole. A clearance volume of the plunger in the plunger hole is a high-pressure fuel chamber. A clearance volume between the electromagnetic driving apparatus and the plunger sleeve cylinder component forms a low-pressure fuel chamber. Under the action of the electromagnetic driving apparatus, the plunger sleeve cylinder component sucks a fuel in the low-pressure fuel chamber into the high-pressure fuel chamber and pressure-feeds the fuel into the high-pressure volume. The electromagnetic driving apparatus comprises an energy storage apparatus, a movable part, and a still part.

An energy-storing-type high-pressure electric fuel pump comprises an electromagnetic driving apparatus and a plunger sleeve cylinder component. The plunger sleeve cylinder component comprises a high-pressure volume, a plunger sleeve having a plunger hole, and a plunger capable of sliding within the plunger hole. A clearance volume of the plunger in the plunger hole is a high-pressure fuel chamber. A clearance volume between the electromagnetic driving apparatus and the plunger sleeve cylinder component forms a low-pressure fuel chamber. Under the action of the electromagnetic driving apparatus, the plunger sleeve cylinder component sucks a fuel in the low-pressure fuel chamber into the high-pressure fuel chamber and pressure-feeds the fuel into the high-pressure volume. The electromagnetic driving apparatus comprises an energy storage apparatus, a movable part, and a still part.

Provided is a two-stroke internal combustion engine, including: a fuel injection valve configured to supply a fuel to a crank chamber; an intake passage configured to allow only air to be sucked thereinto under a negative pressure generated when a piston is actuated; and a scavenging passage that allows communication between the crank chamber and a combustion chamber. The intake passage is branched into a first intake passage and a second intake passage. The first intake passage communicates with the crank chamber. The second intake passage communicates with the scavenging passage. The fuel injection valve is configured to inject the fuel toward at least one of the first intake passage or the crank chamber. Further, air stagnant in the scavenging passage at end of air suction serves as leading air to contribute to scavenging.

Provided is a two-stroke internal combustion engine, including: a fuel injection valve configured to supply a fuel to a crank chamber; an intake passage configured to allow only air to be sucked thereinto under a negative pressure generated when a piston is actuated; and a scavenging passage that allows communication between the crank chamber and a combustion chamber. The intake passage is branched into a first intake passage and a second intake passage. The first intake passage communicates with the crank chamber. The second intake passage communicates with the scavenging passage. The fuel injection valve is configured to inject the fuel toward at least one of the first intake passage or the crank chamber. Further, air stagnant in the scavenging passage at end of air suction serves as leading air to contribute to scavenging.

An energy-storing-type high-pressure electric fuel pump includes an electromagnetic driving apparatus and a plunger sleeve cylinder component. The plunger sleeve cylinder component includes a high-pressure volume, a plunger sleeve having a plunger hole, and a plunger capable of sliding within the plunger hole. A clearance volume of the plunger in the plunger hole is a high-pressure fuel chamber. A clearance volume between the electromagnetic driving apparatus and the plunger sleeve cylinder component forms a low-pressure fuel chamber. Under the action of the electromagnetic driving apparatus, the plunger sleeve cylinder component sucks a fuel in the low-pressure fuel chamber into the high-pressure fuel chamber and pressure-feeds the fuel into the high-pressure volume. The electromagnetic driving apparatus includes an energy storage apparatus, a movable part, and a still part.