High pressure fuel injection system

Claim 2

A fuel injection system for providing a controllable residual fuel pressure within a fuel injector between injections, characterized by: a fuel injection pump connected to a fuel supply; at least one fuel injector for periodically injecting fuel into an engine; conduit means connecting said fuel injection pump with said fuel injector for delivery of fuel thereto; a check valve disposed between said fuel injection pump and said conduit means to prevent fuel back flow to said fuel injection pump; fuel return means for returning leakage fuel from said injector to said fuel supply; pressure influencing means disposed within said fuel return means for controlling fuel pressure within said fuel return means in accordance with engine load, an increase in pressure within said fuel return means producing a corresponding increase in residual pressure within said injector and said conduit means, said pressure influencing means comprising a variable orifice valve.

Claim 3

The invention as claimed in claim 1, including means in said injector for enhancing the response of said pressure influencing means.

Claim 4

The invention as claimed in claim 2, wherein said injector comprises an injector plunger slidably disposed in close fitting relation within the injector body, and wherein said means for enhancing the response of said pressure influencing means comprises an increased clearance between said injector plunger and body to increase the flow of leakage fuel therebetween.

Claim 5

The invention as claimed in claim 1, wherein said means for enhancing the response of said pressure influencing means comprises a bleed orifice between said conduit means and said fuel return means.

Claim 6

The invention as claimed in claim 2, wherein said variable orifice valve comprises a piston-cylinder type valve wherein a piston divides a closed cylinder into first and second chambers, said first chamber communicating with said fuel supply, a port in said first chamber connected to said fuel return means, a valve seat associated with said port and a valve element carried by said piston for regulating leakage fuel flow through said port in accordance with the piston position in said cylinder, said second chamber being connected with a source of regulated presssurized fuel, and means for regulating said source of regulated pressurized fuel in accordance with engine load.

Claim 7

The invention as claimed in claim 5, wherein said latter means comprises a pressure regulating valve linked to the control rack of said injection pump.

Claim 8

The invention as claimed in claim 5, wherein said fuel injection pump comprises a fuel supply pump, and wherein said source of pressurized fuel comprises said fuel supply pump.

Claim 9

The invention as claimed in claim 1, including means for sensing engine speed, and means for controlling said variable orifice valve as a function of engine speed.

Claim 10

The invention as claimed in claim 5, including means for sensing engine speed, and means for controlling said pressure regulating valve as a function of engine speed.

Claim 11

A fuel injection system for selectively controlling the residual fuel pressure within a fuel injector and associated high pressure fuel conduits between injections to thereby selectively increase the fuel injection pressure produced by the injector, characterized by: a fuel injection pump connected to a fuel supply; at least one leakless fuel injector for periodically injecting fuel into an engine; conduit means connecting said fuel injection pump with said fuel injector for delivery of fuel thereto; a check valve disposed between said fuel injection pump and said conduit means, said check valve having a zero retraction volume to prevent fuel back flow to said injection pump between injections; a leak-off passage for receiving leakage fuel from said injector; pressure influencing means disposed within said injector for controlling fuel pressure within said leak-off passage, said pressure influencing means comprising a pressure amplifying variable orifice valve responsive to a regulated supply fuel pressure; and a pressure regulating valve connected with a source of fuel at a constant supply pressure, said regulating valve being controlled by engine manifold pressure to provide a regulated fuel pressure to said pressure influencing means which is substantially inversely proportional to engine load, whereby said pressure influencing means selectively raises the leak-off pressure in said leak-off passage and the residual fuel pressure within said injector between injections in inverse relation to engine load with a consequent increase in fuel injection pressure.

Claim 12

A fuel injection system for selectively controlling the residual fuel pressure within a fuel injector and associated high pressure fuel conduits between injections to thereby selectively increase the fuel injection pressure produced by the injector, characterized by: a fuel injection pump connected to a fuel supply; at least one leakless fuel injector for periodically injecting fuel into an engine; conduit means connecting said fuel injection pump with said fuel injector for delivery of fuel thereto; a check valve disposed between said fuel injection pump and said conduit means, said check valve having a zero retraction volume to prevent fuel back flow to said injection pump between injections; a leak-off passage for receiving leakage fuel from said injector; pressure influencing means disposed within said injector for controlling fuel pressure within said leak-off passage, said pressure influencing means comprising a pressure amplifying variable orifice valve responsive to a regulated supply fuel pressure; and a pressure regulating valve connected with a source of fuel at a constant supply pressure, said regulating valve being controlled by engine manifold pressure to provide a regulated fuel pressure to said pressure influencing means which is substantially inversely proportional to engine load, whereby said pressure influencing means selectively raises the leak-off pressure in said leak-off passage and the residual fuel pressure within said injector between injections in inverse relation to engine load with a consequent increase in fuel injection pressure.

Claim 13

The invention as claimed in claim 10, including speed responsive means for controlling said regulating valve.

Claim 14

The invention as claimed in claim 10, wherein fuel passing through said variable orifice valve passes into said pressure regulated supply fuel.

Claim 15

The invention as claimed in claim 10, wherein said amplifying valve comprises a diaphragm valve, and wherein said regulated fuel pressure acts on said diaphragm to urge said valve toward a closed position.

Claim 16

A fuel injection system for selectively controlling the residual fuel pressure within a fuel injector and associated high pressure fuel conduits between injections to thereby selectively increase the fuel injection pressure produced by the injector, characterized by: a fuel injection pump connected to a fuel supply; at least one leakless fuel injector for periodically injecting fuel into an engine; conduit means connecting said fuel injection pump with said fuel injector for delivery of fuel thereto; a check valve disposed between said fuel injection pump and said conduit means, said check valve having a zero retraction volume to prevent fuel back flow to said injection pump between injections; pressure influencing means connected with said conduit means for controlling fuel pressure within said conduit means and injector, said pressure influencing means comprising a pressure amplifying variable orifice valve responsive to a regulated supply fuel pressure; and a pressure regulating valve connected with a source of fuel at a constant supply pressure, said regulating valve being controlled by engine manifold pressure to provide a regulated fuel pressure to said pressure influencing means which is substantially inversely proportional to engine load, whereby said pressure influencing means selectively raises the residual fuel pressure within said injector and said conduit means between injections in inverse relation to engine load with a consequent increase in fuel injection pressure.

Claim 17

A fuel injection system for selectively controlling the residual fuel pressure within a fuel injector and associated high pressure fuel conduits between injections to thereby selectively increase the fuel injection pressure produced by the injector, characterized by: a fuel injection pump connected to a fuel supply; at least one leakless fuel injector for periodically injecting fuel into an engine; conduit means connecting said fuel injection pump with said fuel injector for delivery of fuel thereto; a check valve disposed between said fuel injection pump and said conduit means, said check valve having a zero retraction volume to prevent fuel back flow to said injection pump between injections; pressure influencing means connected with said conduit means for controlling fuel pressure within said conduit means and injector, said pressure influencing means comprising a pressure amplifying variable orifice valve responsive to a regulated supply fuel pressure; and a pressure regulating valve connected with a source of fuel at a constant supply pressure, said regulating valve being controlled by engine manifold pressure to provide a regulated fuel pressure to said pressure influencing means which is substantially inversely proportional to engine load, whereby said pressure influencing means selectively raises the residual fuel pressure within said injector and said conduit means between injections in inverse relation to engine load with a consequent increase in fuel injection pressure.

Claim 18

The invention as claimed in claim 14, including speed responsive means for controlling said regulating valve.

Claim 19

The invention as claimed in claim 14, wherein fuel passing through said variable orifice valve passes into said pressure regulated supply fuel.

Claim 20

The invention as claimed in claim 14, wherein said amplifying valve comprises a diaphragm valve, and wherein said regulated fuel pressure acts on said diaphragm to urge said valve toward a closed position.