Fuel pump for a direct injection system

A valve assembly (7) for a fuel pump (1) and comprising:

• a one-way outlet closing valve (8), which only allows fuel to flow out;
• a one-way pressure relief valve (9), which only allows fuel to flow in;
• a connector (11), which has a housing (13) on the inside;
• and
• a valve disc (14), which engages the housing (13) of the connector (11) and has a plurality of through outlet holes (18), which are part of the outlet closing valve (8) and are each provided with a corresponding first valve seat (19) obtained in the area of a first wall (16) of the valve disc (14), and a through relief hole (20), which is part of the pressure relief valve (9) and is provided with a second valve seat (21) obtained in the area of a second wall (15) of the valve disc (14) parallel to and opposite the first wall (16);
• wherein the outlet closing valve (8) comprises a first shutter, which engages the first valve seats (19) of the outlet holes (18) and is movable so as to detach itself from the first valve seats (19), when the fuel pressure downstream of the valve disc (14) is sufficiently smaller than the fuel pressure upstream of the valve disc (14);
• wherein the pressure relief valve (9) comprises a second shutter (29), which engages the second valve seat (21) of the relief hole (20) and is movable so as to detach itself from the second valve seat (21), when the difference between the fuel pressure downstream of the valve disc (14) and the fuel pressure upstream of the valve disc (14) exceeds a predetermined intervention threshold;
• wherein the first shutter consists of a flexible sheet (22), which is fixed to the valve disc (14) and comprises a plurality of shutting portions (23), each having a circular shape, being arranged in the area of the corresponding valve seat (19) of the corresponding outlet hole (18) and being configured to prevent fuel from flowing through the corresponding outlet hole (18), when the outlet closing valve (8) is closed;
• a peripheral mounting portion (25) with an annular shape, which is arranged along the outer edge of the valve disc (14);
• and a plurality of outer connection portions (26), each connecting the peripheral mounting portion (25) to a corresponding shutting portion (23);
• wherein the sheet (22) comprises a corresponding outer connection portion (26) for each shutting portion (23) so that each shutting portion (23) is always connected to one and only one outer connection portion (26), and vice versa, that is, each outer connection portion (26) is always connected to one and only one shutting portion (23);
• wherein the sheet (22) comprises a central mounting portion (24) which is arranged at the center of the shutting portions (23);
• wherein the sheet (22) comprises a plurality of inner connection portions (27), each connecting the central mounting portion (24) to a corresponding shutting portion (23) so that each shutting portion (23) is connected to one and only one inner connection portion (27), and vice versa, that is, each inner connection portion (27) is always connected to one and only one shutting portion (23);
• wherein each shutting portion (23) is supported exclusively by a single outer connection portion (26) and a single inner connection portion (27) and has no other connection than the corresponding outer connection portion (26) and the corresponding inner connection portion (27);
• and
• wherein each shutting portion (23) is in no way directly connected to another shutting portion (23).