Fuel supply system for internal combustion engine

Claim 2

In an internal combustion engine of the type in which the air is supplied substantially in proportion to the engine speed and the opening degree of a throttle valve and the fuel to be mixed with said air is injected through a fuel injection nozzle, a fuel supply system comprising a. pump means which discharges the fuel in proportion to the engine speed, said pump means including: a gear type governor pump driven at a speed in proportion to the speed of the engine, a gear type fuel injection pump the suction port of which is hydraulically connected to the discharge port of said governor pump, which is driven at a speed in proportion to the speed of said engine, and which has the discharge rate half as much as that of said governor pump, and a recirculation line hydraulically interconnecting between the suction and discharge ports of said governor pump and having therein disposed a governor nozzle the diameter of the nozzle hole of which is equal to that of said fuel injection nozzle; and b. a fuel shunt device for supplying a part of the fuel supplied from said pump means to said fuel injection nozzle while recirculating the remaining fuel to said pump means, said fuel shunt device having first valve means for automatically controlling the area of the opening of a passage hydraulically connecting said fuel shunt device to said fuel injection nozzle in proportion to the discharge rate of said pump means, and second valve means for automatically controlling the area of the opening of a return line hydraulically connecting said fuel shunt device to said pump means in inverse proportion to the opening degree of said throttle valve, whereby the air-fuel mixture with a substantially constant air-fuel ratio independently of the speed and load of the engine may be charged into said engine.

Claim 3

In an internal combustion engine of the type in which the air is supplied substantially in proportion to the engine speed and the opening degree of a throttle valve and the fuel to be mixed with said air is injected through a fuel injection nozzle, a fuel supply system comprising a. pump means which discharges the fuel in proportion to the engine speed, and b. a fuel shunt device for supplying a part of the fuel supplied from said pump means to said fuel injection nozzle while recirculating the remaining fuel to said pump means, said fuel shunt device having means for automatically controlling the area of the opening of a passage hydraulically connecting said fuel shunt device to said fuel injection nozzle in proportion to the discharge rate of said pump means, and means for automatically controlling the area of the opening of a return line hydraulically connecting said fuel shunt device to said pump means in inverse proportion to the opening degree of said throttle valve, said controlling means comprising: a cylinder block having a first and a second cylinder bores formed through said cylinder block in the axial direction thereof, a casing fitted over said cylinder block coaxially thereof so as to define with said cylinder block an inlet chamber in communication with the discharge side of said pump means and to define with the top of said cylinder block a discharge chamber in communication with the suction side of said pump means, a control piston slidably fitted into said first cylinder bore, an acceleration piston slidably fitted into said second cylinder bore, a control chamber defined within said first cylinder bore below the lower end of said control piston and normally hydraulically communicated with said fuel injection nozzle, the space in said second cylinder bore above the top end of said acceleration piston being normally hydraulically communicated with said discharge chamber, a plurality of metering holes for intercommunicating hydraulically between said control chamber and said inlet chamber, said metering holes having the same diameter and being in the axial direction of said first cylinder bore spaced apart from each other in a predetermined relation, a plurality of return holes for intercommunicating hydraulically between said space in said second cylinder bore above the top end of said acceleration piston and said inlet chamber, said return holes having the same diameter and being in the axial direction of the second cylinder bore equidistantly spaced apart from each other, said control piston being normally biased downward by spring means and being displaced in response to the pressure in said control chamber, thereby opening or closing said metering holes, the number of said metering holes opened being controlled in accordance with the displacement of said control piston, and said acceleration piston being operatively coupled to said throttle valve in such a way that the number of said return holes opened by the stroke of said acceleration piston may be in inverse porportion to the opening degree of said throttle valve, whereby the air-fuel mixture with a substantially constant air-fuel ratio independently of the speed and load of the engine may be charged into said engine.

Claim 4

In an internal combustion engine of the type in which the air is supplied substantially in proportion to the engine speed and the opening degree of a throttle valve and the fuel to be mixed with said air is injected through a fuel injection nozzle, a fuel supply system comprising a. pump means which discharges the fuel in proportion to the engine speed, and b. a fuel shunt device for supplying a part of the fuel supplied from said pump means to said fuel injection nozzle while recirculating the remaining fuel to said pump means, said fuel shunt device having means for automatically controlling the area of the opening of a passage hydraulically connecting said fuel shunt device to said fuel injection nozzle in proportion to the discharge rate of said pump means, and means for automatically controlling the area of the opening of a return line hydraulically connecting said fuel shunt device to said pump means in inverse proportion to the opening degree of said throttle valve, said controlling means comprising: a cylinder block having a first and a second cylinder bores formed through said cylinder block in the axial direction thereof, a casing fitted over said cylinder block coaxially thereof so as to define with said cylinder block an inlet chamber in communication with the discharge side of said pump means and to define with the top of said cylinder block a discharge chamber in communication with the suction side of said pump means, a control piston slidably fitted into said first cylinder bore, an acceleration piston slidably fitted into said second cylinder bore, a control chamber defined within said first cylinder bore below the lower end of said control piston and normally hydraulically communicated with said fuel injection nozzle, the space in said second cylinder bore above the top end of said acceleration piston being normally hydraulically communicated with said discharge chamber, a plurality of metering holes for intercommunicating hydraulically between said control chamber and said inlet chamber, said metering holes having the same diameter and being in the axial direction of said first cylinder bore spaced apart from each other in a predetermined relation, a plurality of return holes for intercommunicating hydraulically between said space in said second cylinder bore above the top end of said acceleration piston and said inlet chamber, said return holes having the same diameter and being in the axial direction of the second cylinder bore equidistantly spaced apart from each other, said control piston being normally biased downward by spring means and being displaced in response to the pressure in said control chamber, thereby opening or closing said metering holes, the number of said metering holes opened being controlled in accordance with the displacement of said control piston, and said acceleration piston being operatively coupled to said throttle valve in such a way that the number of said return holes opened by the stroke of said acceleration piston may be in inverse porportion to the opening degree of said throttle valve, whereby the air-fuel mixture with a substantially constant air-fuel ratio independently of the speed and load of the engine may be charged into said engine.

Claim 5

A fuel supply system as set forth in claim 2 wherein the spacing between the adjacent metering holes between said control chamber and said inlet chamber is reduced as the position of said metering holes becomes lower, and the force of said spring means for biasing said control piston changes linearly, in response to the displacement of said control piston.

Claim 6

A fuel supply system as set forth in claim 2 wherein the space in said first cylinder bore above the top end of said control piston is normally communicated with said discharge chamber and is hydraulicaly communicated with said inlet chamber through a compensating hole which is in the axial direction of said first cylinder bore spaced apart from the uppermost metering hole by a suitable distance, and said control piston has an annular groove formed around the side surface thereof and hydraulically communicated with said space in said first cylinder above the top end of said control piston through a passage formed through said control piston, whereby when said control piston is raised by a predetermined stroke against said biase spring means as the pressure in said control chamber increases to a predetermined level, said annular groove coincides with said compensating hole to hydraulically intercommunicate between said inlet and discharge chambers.

Claim 7

A fuel supply system as set forth in claim 2 wherein the space in said second cylinder bore below the lower end of said acceleration piston is normally hydraulically communicated with said control chamber in said first cylinder bore and further hydraulically communicated with said inlet chamber through a plurality of over-driving holes which are formed through said cylinder block said over-driving holes being in the axial direction of said second cylinder bore equidistantly spaced apart from each other, whereby when said acceleration piston is displaced beyond the full load position at which a predetermined number of said return holes are closed, said over-driving holes are opened one by one depending upon the stroke of said acceleration piston.