Fuel injection pump for an internal combustion engine

Claim 2

A fuel injection pump for an internal combustion engine provided with a fuel injection valve, comprising: (a) a rotary distributor rotating in synchronism with engine revolution; (b) a cam ring encircling the rotary distributor and having an inner surface formed with two or more cam protrusions; and (c) two or more plungers equal in number to the cam protrusions and mounted on the rotary distributor for rotation in accordance with rotation of the rotary distributor, the plungers defining a common pumping chamber and engaging the inner surface of the cam ring for reciprocation in the radial direction with respect to the rotary distributor to pump fuel out of said common pumping chamber into the injection valve; at least one of the cam protrusions having a cam lift profile different from those of the other cam protrusions so that the sum of the cam lift profiles of the cam protrusions determining fuel injection rate differs in shape from each of the cam lift characteristics, wherein: said plungers are arranged radially, said cam protrusions are arranged around said cam ring, and said difference in cam lift profile includes a slight uneven angular offset of one of said cam protrusions with respect to the other cam protrusions; and said offset cam protrusion engages one of said plungers before the other cam protrusions engage the other plungers, and said offset cam protrusion has less angular extent that said other cam protrusions.

Claim 3

The fuel injection pump of claim 1, wherein each of said cam protrusions has a single peak and the timings of engagement between each set of plunger and cam protrusion are so offset that the trace of the volume of said common pumping chamber with respect to the relative angular position of said plungers and said cam ring has two peaks.

Claim 4

The fuel injection pump of claim 1, wherein said offset cam protrusion has less radial extent than said other cam protrusions.

Claim 5

A fuel injection pump for an internal combustion engine provided with a fuel injection valve, comprising: (a) a rotary distributor rotating in synchronism with engine revolution; (b) a cam ring encircling the rotary distributor and having an inner surface formed with two or more cam protrusions; and (c) two or more plungers equal in number to the cam protrusions and mounted on the rotary distributor for rotation in accordance with rotation of the rotary distributor, the plungers defining a common pumping chamber and engaging the inner surface of the cam ring for reciprocation in the radial direction with respect to the rotary distributor to pump fuel out of said common pumping chamber into the injection valve; at least one of the cam protrusions having a cam lift profile different from those of the other cam protrusions so that the sum of the cam lift profiles of the cam protrusions determining fuel injection rate differs in shape from each of the cam lift characteristics, wherein: said plungers are arranged radially, said cam protrusions are arranged around said cam ring, and said difference in cam lift profile includes a slight uneven angular offset of one of said cam protrusions with respect to the other cam protrusions; and said offset cam protrusion engages one of said plungers before the other cam protrusions engage the other plungers, said inner surface of the cam ring defines an outermost base circle, and said offset cam protrusion has a radial dimension with respect to the base circle less than the corresponding radial dimensions of said other cam protrusions.

Claim 6

A fuel injection pump for an internal combustion engine provided with a fuel injection valve, comprising: (a) a rotary distributor rotating in synchronism with engine revolution; (b) a cam ring encircling the rotary distributor and having an inner surface formed with two or more cam protrusions; and (c) two or more plungers equal in number to the cam protrusions and mounted on the rotary distributor for rotation in accordance with rotation of the rotary distributor, the plungers defining a common pumping chamber and engaging the inner surface of the cam ring for reciprocation in the radial direction with respect to the rotary distributor to pump fuel out of said common pumping chamber into the injection valve; at least one of the cam protrusions having a cam lift profile different from those of the other cam protrusions so that the sum of the cam lift profiles of the cam protrusions determining fuel injection rate differs in shape from each of the cam lift characteristics, wherein: said plungers are arranged radially, said cam protrusions are arranged around said cam ring, and said difference in cam lift profile includes a slight uneven angular offset of one of said cam protrusions with respect to the other cam protrusions; and said offset cam protrusion engages one of said plungers before the other cam protrusions engage the other plungers, said inner surface of the cam ring defines an outermost base circle, and said offset cam protrusion has a radial dimension with respect to the base circle less than the corresponding radial dimensions of said other cam protrusions.

Claim 7

The fuel injection pump of claim 4, wherein said offset cam protrusion has less angular extent than said other cam protrusions.

Claim 8

A fuel injection pump for an internal combustion engine having a rotatable crankshaft and a combustion chamber, the injection pump comprising: (a) a cam ring with an internal surface having inwardly projecting lobes defining first and second cam protrusions; (b) a rotary distributor (c) first and second movable plungers arranged in said rotary distributor defining a common pumping chamber, the volume of which varies in accordance with the position of each of the plungers, the first and second plungers alternately engaging with the first and second cam protrusions and thereby reciprocating the first and second plungers in synchronism with rotation of the crankshaft; (d) means for supplying fuel to the pumping chamber as the pumping chamber expands; (e) means for directing the fuel out of the pumping chamber toward the combustion chamber as the pumping chamber contracts; and (f) means for offsetting the timing of engagement of one of the plungers with one of the cam protrusions and the timing of engagement of the other plunger with the other cam protrusion by a preset angular interval with respect to rotation of the crankshaft, wherein the preset angular interval is chosen so that the fuel supplied to the combustion chamber by engagement of one of the plungers with one of the cam protrusions is continuous with fuel supplied to the combustion chamber by engagement of the other plunger with the other cam protrusion; the fuel supplied to the combustion chamber by engagement of the first cam protrusion with one of the first and second plungers is always in advance of fuel supplied to the combustion chamber by engagement of the second cam protrusion with the other plunger in each combined continuous fuel supply stroke; and the first cam protrusion is angularly smaller than the second cam protrusion so that said first cam protrusion engages said movable plungers more briefly than said second cam protrusion engages said movable plungers.

Claim 9

A fuel injection pump for an internal combustion engine having a rotatable crankshaft and a combustion chamber, the injection pump comprising: (a) a cam ring with an internal surface having inwardly projecting lobes defining first and second cam protrusions; (b) a rotary distributor (c) first and second movable plungers arranged in said rotary distributor defining a common pumping chamber, the volume of which varies in accordance with the position of each of the plungers, the first and second plungers alternately engaging with the first and second cam protrusions and thereby reciprocating the first and second plungers in synchronism with rotation of the crankshaft; (d) means for supplying fuel to the pumping chamber as the pumping chamber expands; (e) means for directing the fuel out of the pumping chamber toward the combustion chamber as the pumping chamber contracts; and (f) means for offsetting the timing of engagement of one of the plungers with one of the cam protrusions and the timing of engagement of the other plunger with the other cam protrusion by a preset angular interval with respect to rotation of the crankshaft, wherein the preset angular interval is chosen so that the fuel supplied to the combustion chamber by engagement of one of the plungers with one of the cam protrusions is continuous with fuel supplied to the combustion chamber by engagement of the other plunger with the other cam protrusion; the fuel supplied to the combustion chamber by engagement of the first cam protrusion with one of the first and second plungers is always in advance of fuel supplied to the combustion chamber by engagement of the second cam protrusion with the other plunger in each combined continuous fuel supply stroke; and the first cam protrusion is angularly smaller than the second cam protrusion so that said first cam protrusion engages said movable plungers more briefly than said second cam protrusion engages said movable plungers.

Claim 10

The fuel injection pump of claim 6, wherein the first cam protrusion is smaller than the second cam protrusion in dimension effective to displace the first and second plungers.