Fuel injection apparatus for internal combustion engines

Claim 2

A fuel injection pump-and-nozzle assembly forming part of a fuel injection apparatus serving an internal combusTion engine, said assembly being of the type that has (a) a pump piston executing alternating delivery strokes and return or charging strokes, (b) a pump work chamber bounded by said pump piston, (c) a servo piston connected to said pump piston to drive the latter, said servo piston having a diameter greater than that of said pump piston, (d) a pressure source externally of said assembly for delivering fuel under pressure to said assembly, (e) first supply conduit means extending from said pressure source to said pump work chamber, (f) a supply valve disposed in said first supply conduit means, (g) a servo pressure chamber bounded by said servo piston, (h) second supply conduit means extending from said pressure source to said servo pressure chamber, (i) discharge conduit means extending from said servo pressure chamber, (j) a housing including a bore, and (k) a valve plunger disposed within said bore for controlling said second supply conduit means and said discharge conduit means, said valve plunger being adapted to assume a first switching position for admitting pressurized fuel from said pressure source to said servo pressure chamber for effecting said delivery strokes and a second switching position for establishing communication between said servo pressure chamber and said discharge conduit means for effecting said return strokes, the improvement comprising, A. a control pressure chamber formed within said bore and bounded by said valve plunger, B. third supply conduit means extending from said pressure source to said control pressure chamber, C. a solenoid valve disposed in and forming part of said third supply conduit means at a location immediately adjacent said valve plunger for intermittent energization in phase with the operation of the engine, so that pressurized fuel is admitted through said third supply conduit to said control chamber to move said valve plunger from one of its switching positions to the other, and D. a throttle member for affecting the speed of said return strokes, said throttle member being disposed in said first supply conduit means between said supply valve and said pressure source, said throttle member including means defining a permanently set flow passage section so dimensioned as to substantially lengthen said charging period with respect to the injection period during which fuel is injected into the engine from said pump work chamber.

Claim 3

An improvement as defined in claim 1, wherein the maximum permissible fuel injection quantity is determined by the maximum stroke of said pump piston.

Claim 4

An improvement as defined in claim 1, wherein said flow passage section of said throttle member is so dimensioned that for the maximum permissible engine rpm each charging period during which fuel is supplied to said work chamber from said pressure source extends to the entire period between the terminal moment of the injection period of one work cycle and the starting moment of the injection period of the successive work cycle.

Claim 5

An improvement as defined in claim 1, wherein said solenoid valve is an electromagnetically operated, pressure-equalized 3/2-way valve having a sphere as its movable valve member.

Claim 6

An improvement as defined in claim 1, including means for varying the pressure of fuel prevailing in said second conduit means as a function of at least one engine parameter.

Claim 7

An improvement as defined in claim 6, wherein said engine parameter is the engine rpm.

Claim 8

An improvement as defined in claim 5, wherein said engine parameter is the engine load.

Claim 9

An improvement as defined in claim 1, wherein said first, second and third supply conduit means intersect said bore.

Claim 10

An improvement as defined in claim 1, wherein said bore is disposed substantially transverse to the direction of injection.

Claim 11

A fuel injection pump-and-nozzle assembly forming part of a fuel injection apparatus serving an internal combustion engine, said assembly being of the type that has (a) a pump pistOn executing alternating delivery strokes and return or charging strokes, (b) a pump work chamber bounded by said pump piston, (c) a servo piston connected to said pump piston to drive the latter, said servo piston having a diameter greater than that of said pump piston, (d) a pressure source externally of said assembly for delivering fuel under pressure to said assembly, (e) first supply conduit means extending from said pressure source to said pump work chamber, (f) a supply valve disposed in said first supply conduit means, (g) a servo pressure chamber bounded by said servo piston, (h) second supply conduit means extending from said pressure source to said servo pressure chamber, said second supply conduit means having a bore forming a part thereof which opens into said servo pressure chamber, said servo piston having an extension rigidly affixed to said servo piston and projecting axially outwardly from that face of said servo piston that bounds said servo pressure chamber, said extension projecting into said bore and defining therewith a variable flow passage section, the magnitude of which is a function of the momentary axial position of said servo piston, (i) discharge conduit means extending from said servo pressure chamber, (j) a housing including a bore, and (k) a valve plunger disposed within said bore for controlling said second supply conduit means and said discharge conduit means, said valve plunger being adapted to assume a first switching position for admitting pressurized fuel from said pressure source to said servo pressure chamber for effecting said delivery strokes and a second switching position for establishing communication between said servo pressure chamber and said discharge conduit means for effecting said return strokes, the improvement comprising: A. a control pressure chamber formed within said bore and bounded by said valve plunger; B. third supply conduit means extending from said pressure source to said control pressure chamber; C. a solenoid valve disposed in and forming part of said third supply conduit means at a location immediately adjacent said valve plunger for intermittent energization in phase with the operation of the engine, so that pressurized fuel is admitted through said third supply conduit to said control chamber to move said valve plunger from one of its switching positions to the other; and D. a throttle member for affecting the speed of said return strokes, said throttle member being disposed in said first supply conduit means between said supply valve and said pressure source, said throttle member including means defining a permanently set flow passage section so dimensioned as to substantially lengthen said charging period with respect to the injection period during which fuel is injected into the engine from said pump work chamber.

Claim 12

A fuel injection pump-and-nozzle assembly forming part of a fuel injection apparatus serving an internal combustion engine, said assembly being of the type that has (a) a pump pistOn executing alternating delivery strokes and return or charging strokes, (b) a pump work chamber bounded by said pump piston, (c) a servo piston connected to said pump piston to drive the latter, said servo piston having a diameter greater than that of said pump piston, (d) a pressure source externally of said assembly for delivering fuel under pressure to said assembly, (e) first supply conduit means extending from said pressure source to said pump work chamber, (f) a supply valve disposed in said first supply conduit means, (g) a servo pressure chamber bounded by said servo piston, (h) second supply conduit means extending from said pressure source to said servo pressure chamber, said second supply conduit means having a bore forming a part thereof which opens into said servo pressure chamber, said servo piston having an extension rigidly affixed to said servo piston and projecting axially outwardly from that face of said servo piston that bounds said servo pressure chamber, said extension projecting into said bore and defining therewith a variable flow passage section, the magnitude of which is a function of the momentary axial position of said servo piston, (i) discharge conduit means extending from said servo pressure chamber, (j) a housing including a bore, and (k) a valve plunger disposed within said bore for controlling said second supply conduit means and said discharge conduit means, said valve plunger being adapted to assume a first switching position for admitting pressurized fuel from said pressure source to said servo pressure chamber for effecting said delivery strokes and a second switching position for establishing communication between said servo pressure chamber and said discharge conduit means for effecting said return strokes, the improvement comprising: A. a control pressure chamber formed within said bore and bounded by said valve plunger; B. third supply conduit means extending from said pressure source to said control pressure chamber; C. a solenoid valve disposed in and forming part of said third supply conduit means at a location immediately adjacent said valve plunger for intermittent energization in phase with the operation of the engine, so that pressurized fuel is admitted through said third supply conduit to said control chamber to move said valve plunger from one of its switching positions to the other; and D. a throttle member for affecting the speed of said return strokes, said throttle member being disposed in said first supply conduit means between said supply valve and said pressure source, said throttle member including means defining a permanently set flow passage section so dimensioned as to substantially lengthen said charging period with respect to the injection period during which fuel is injected into the engine from said pump work chamber.