US 4,463,727 A · Diesel engine fuel injection system

Abstract

A Diesel engine distributor-type injection pump has a vane pump (3) providing fuel under pressure to an injection pump system formed by two pistons (17) pressed towards each other by a cam track (26) to provide fuel under injection pressure to fuel injection plug connectors (28, 29) when the radial position of a duct (27) in the bore of the rotating shaft (2) matches a connecting duct (28) of a respective injection outlet. To provide for precise timing of fuel being injected, pressurized fuel is drained under control of a slider valve (FIG. 1: 38, 39; FIG. 2: 72, 74) connected through a communicating duct (32, 42, 71) to the slider valve. The slider valve is operated by a piezoelectric positioning element (FIG. 1: 61; FIG. 2: 76) which moves the spool (74, 39) of the slider valve; in one embodiment (FIG. 1), the piezoelectric element operates a piston (53) having a substantially larger diameter than the end faces of the spool (39) to provide for excursion amplification; in another embodiment (FIGS. 2, 4-8), the piezoelectric elements are bending elements and thus provide for larger excursion.

Claims30

Dependent claims

Piezoelectric hydraulic control unit (35) in combination with a fuel injection pump (2, 22);

wherein the fuel injection pump (2, 11) has a pump chamber (20) within which fuel under injection pressure is provided;
and a pressure inlet (42) is connected to be in fluid communication (30, 31, 32) with said injection pressure pump chamber,
comprising, in accordance with the invention,
a spool valve having a spool cylinder (38) and a valve spool (39) slidable in the cylinder;
said valve spool (39) having a section (43) of reduced diameter;
a drain connection duct means (30, 32, 38, 44, 45, 46) terminating in said spool valve cylinder (38) for selective communication of the pressure inlet (42) with the drain line or blocking of said communication in dependence on the position of the valve spool;
a hydraulic housing (37) defining a fluid chamber;
a piston (53) separating said chamber into two pressure chambers (55, 56);
a piezoelectric driver element (61) coupled to said piston (53) to move the piston in the chamber and change the relative volume of the pressure chambers;
and wherein the valve spool (39) is positioned in the spool cylinder (38) to subdivide the cylinder and form two cylinder portions, each of which is in communication with a respective one of said pressure chambers (55, 56) to provide for amplified movement of the spool in the spool cylinder upon small excursions of the piston (53), under piezoelectric control by the piezoelectric element (61), and hence control the position of the spool for, selectively, blocking or drainage of fluid therefrom.

7 more elements

Fuel injection system for an internal combustion engine in which fuel is to be injected at a predetermined time instant in relation to an operating parameter of the engine, particularly for a Diesel engine, having

a fuel injection pump (2, 11, 17, 20, 25, 26);
and means controlling the quantity of injected fuel including
a piezoelectric hydraulic control unit (59) comprising,
a spool valve having a spool cylinder (38) and a valve spool (39) slidable in the cylinder;
said valve spool (39) having a section (43) of reduced diameter;
a drain connection duct means (30, 32, 38, 44, 45, 46) terminating in spool valve cylinder (38) for selective communication of a pressure inlet (42) with the drain line or blocking of said communication in dependence on the position of the valve spool;
a hydraulic housing (37) defining a fluid chamber;
a piston (53) separating said chamber into two pressure chambers (55, 56);
a piezoelectric driver element (61) coupled to said piston (53) to move the piston in the chamber and change the relative volume of the pressure chambers;
and wherein the valve spool (39) is positioned in the spool cylinder (38) to subdivide the cylinder and form two cylinder portions, each of which is in communication with a respective one of said pressure chambers (55, 56) to provide for amplified movement of the spool in the spool cylinder upon small excursions of the piston (53), under piezoelectric control by the piezoelectric element (61), and hence control the position of the spool for, selectively, blocking or drainage of fluid therefrom.

7 more elements

a fuel injection pump (2, 11, 17, 20, 25, 26);
and means controlling the quantity of injected fuel including
a piezoelectric hydraulic control unit (59) comprising
a housing (69)
a spool valve having a spool cylinder (72) and a valve spool (74) slidable in the cylinder;
said valve spool having a section (75) of reduced diameter;
a drain connection (73);
duct means (71) terminating in said spool valve cylinder (72) for selective communication of a pressure inlet (71) with the drain line or blocking said communication in dependence on the position of the spool;
and further comprising a plurality of piezoelectric bending positioning elements (76) coupled to said valve spool (74).

6 more elements

Dependencies are inferred from the claim text.

Diesel engine fuel injection system

Life of this patent

Diesel engine fuel injection system

Life of this patent

Abstract

Claims30