Fill metered hydraulically actuated fuel injection system and method of fuel injection

Claim 2

A hydraulically actuated fuel injector comprising: an injector body having an actuation fluid cavity that opens to an actuation fluid inlet, an actuation fluid drain and a piston bore, and having a plunger bore that opens to a fuel supply passage and a nozzle chamber, and said nozzle chamber opens to a nozzle outlet; a control valve mounted in said injector body and being movable between a fixed first position that opens said actuation fluid inlet and closes said actuation fluid drain, and a fixed second position that closes said actuation fluid inlet and opens said actuation fluid drain; an intensifier piston positioned to reciprocate in said piston bore between an upper position and a lower position; a plunger having a side surface extending between a contact end and a pressure face end being positioned to reciprocate in said plunger bore between an advanced position and a retracted position; a portion of said plunger bore and said pressure face of said plunger defining a fuel pressurization chamber that opens to said nozzle chamber; a check valve positioned in said fuel supply passage and being operable to prevent flow of fuel from said fuel pressurization chamber back into said fuel supply passage; a needle check positioned to reciprocate in said nozzle chamber between a closed position that closes said nozzle outlet and an open position that opens said nozzle outlet, said needle check including a hydraulic lift surface exposed to said nozzle chamber; means, within said injector body, for biasing said needle check toward said closed position; said intensifier piston having a single hydraulic actuation surface, and said hydraulic actuation surface being exposed to said actuation fluid cavity; and means for closing said actuation fluid cavity to said actuation fluid drain to stop said plunger at a metered position between said retracted position and said advanced position when said plunger is retracting from said advanced position.

Claim 3

The fuel injector of claim 1 further comprising means, including a spring within said injector body, for biasing said intensifier piston away from said upper position, and said spring having insufficient strength to compress fuel in said fuel pressurization chamber above a valve opening pressure that would overcome said means for biasing said needle check.

Claim 4

The fuel injector of claim 1, wherein said injector body includes a fuel return passage that is substantially free of obstructions and opens into said plunger bore; said plunger includes a pressure relief passage that opens on one end through said pressure face end and opens on its other end through said side surface; and said pressure relief passage opens said fuel pressurization chamber to said fuel return passage when said plunger approaches said advanced position.

Claim 5

The fuel injector of claim 1, wherein said actuation fluid inlet is connected to a source of high pressure actuation fluid; said fuel supply passage is connected to a source of fuel fluid that is different from said actuation fluid; said actuation fluid drain is connected to a low pressure actuation fluid reservoir via a drain return passage that is substantially free of restrictions.

Claim 6

The fuel injector of claim 1, wherein said control valve has a fixed third position in which said actuation fluid drain and said actuation fluid inlet are closed.

Claim 7

The fuel injector of claim 1, further comprising means, within said injector body, for biasing said plunger toward said retracted position.

Claim 10

The method of claim 7, wherein said step of stopping said plunger includes a step of: opening said actuation fluid inlet when said desired amount of said fuel fluid has flowed into said injector body.

Claim 11

The method of claim 7, wherein said injector body includes a fuel return passage, and the method further comprising the step of: opening said nozzle chamber to said fuel return passage after said step of opening said actuation fluid inlet but before said step of retracting said plunger.

Claim 12

The method of claim 7, wherein said step of stopping said plunger is accomplished by the step of: opening said actuation fluid inlet to flow of high pressure actuation fluid to initiate a subsequent injection event; and closing said actuation fluid drain.

Claim 13

The method of claim 10, wherein said injector body includes a fuel return passage, and the method further comprising the step of: opening said nozzle chamber to said fuel return passage after said step of opening said actuation fluid inlet but before said step of retracting said plunger.

Claim 14

The method of claim 7, wherein said step of retracting said plunger occurs over a time period, and said time period is controlled by the step of: regulating the pressure of said fuel fluid.

Claim 15

The method of claim 12, wherein said step of closing said actuation fluid inlet is carried out when the time to a subsequent injection event is about equal to said time period.

Claim 16

The method of claim 7, wherein said step of retracting said plunger is accomplished by the steps of: pressurizing said fuel fluid to a pressure greater than the pressure in said actuation fluid drain; and hydraulically pushing said plunger in a retracting direction opposite to said forward direction using said fuel fluid.

Claim 17

The method of claim 7, wherein said step of retracting said plunger is accomplished by the step of: biasing said plunger in a retracting direction opposite to said forward direction.

Claim 18

A fuel injection system comprising: a source of high pressure actuation fluid; a low pressure actuation fluid reservoir; a source of fuel fluid different from said actuation fluid; a hydraulically actuated fuel injector comprising: an injector body having an actuation fluid cavity that opens to an actuation fluid inlet, an actuation fluid drain and a piston bore, and having a plunger bore that opens to a nozzle chamber and a fuel supply passage, and said nozzle chamber opens to a nozzle outlet; an intensifier piston positioned to reciprocate in said piston bore between an upper position and a lower position; a plunger having a side surface extending between a contact end and a pressure face end, and being positioned to reciprocate in said plunger bore between and advanced position and a retracted position; a portion of said plunger bore and said pressure face end of said plunger defining a fuel pressurization chamber that opens to said nozzle chamber; a needle check positioned to reciprocate in said nozzle chamber between a closed position that closes said nozzle outlet and an open position that opens said nozzle outlet, said needle check including a hydraulic lift surface exposed to said nozzle chamber; means, within said injector body, for biasing said needle check toward said closed position; means for stopping said plunger at a metered position between said retracted position and said advanced position; a first supply passage connecting said actuation fluid inlet to said source of high pressure actuation fluid; a second supply passage connecting said fuel supply passage to said source of fuel fluid different from said actuation fluid; a drain passage that is substantially free of obstructions connecting said actuation fluid drain to said low pressure actuation fluid reservoir; a control valve positioned in said actuation fluid cavity and having the ability to move between a first position in which said actuation fluid inlet is open and said actuation fluid drain is closed, and a second position in which said actuation fluid inlet is closed and said actuation fluid drain is open; and a computer in communication with and capable of controlling said control valve.

Claim 19

A fuel injection system comprising: a source of high pressure actuation fluid; a low pressure actuation fluid reservoir; a source of fuel fluid different from said actuation fluid; a hydraulically actuated fuel injector comprising: an injector body having an actuation fluid cavity that opens to an actuation fluid inlet, an actuation fluid drain and a piston bore, and having a plunger bore that opens to a nozzle chamber and a fuel supply passage, and said nozzle chamber opens to a nozzle outlet; an intensifier piston positioned to reciprocate in said piston bore between an upper position and a lower position; a plunger having a side surface extending between a contact end and a pressure face end, and being positioned to reciprocate in said plunger bore between and advanced position and a retracted position; a portion of said plunger bore and said pressure face end of said plunger defining a fuel pressurization chamber that opens to said nozzle chamber; a needle check positioned to reciprocate in said nozzle chamber between a closed position that closes said nozzle outlet and an open position that opens said nozzle outlet, said needle check including a hydraulic lift surface exposed to said nozzle chamber; means, within said injector body, for biasing said needle check toward said closed position; means for stopping said plunger at a metered position between said retracted position and said advanced position; a first supply passage connecting said actuation fluid inlet to said source of high pressure actuation fluid; a second supply passage connecting said fuel supply passage to said source of fuel fluid different from said actuation fluid; a drain passage that is substantially free of obstructions connecting said actuation fluid drain to said low pressure actuation fluid reservoir; a control valve positioned in said actuation fluid cavity and having the ability to move between a first position in which said actuation fluid inlet is open and said actuation fluid drain is closed, and a second position in which said actuation fluid inlet is closed and said actuation fluid drain is open; and a computer in communication with and capable of controlling said control valve.

Claim 20

The fuel injection system of claim 16, wherein said control valve has fixed third position in which said actuation fluid inlet is closed and said actuation fluid drain is closed.

Claim 21

The fuel injection system of claim 16, wherein said intensifier piston has a single hydraulic actuation surface, and said hydraulic actuation surface is exposed to said actuation fluid cavity.

Claim 22

The fuel injection system of claim 16 further comprising means, including a spring within said injector body, for biasing said intensifier piston away from said upper position, and said spring having insufficient strength to compress fuel in said fuel pressurization chamber above a valve opening pressure that would overcome said means for biasing said needle check.

Claim 23

The fuel injection system of claim 16, further comprising: said injector body including a fuel return passage that is substantially free of obstructions and opens into said plunger bore; a fuel return line connected to said fuel return passage; said plunger includes a pressure relief passage that opens on one end through said pressure face and opens on its other end through said side surface; and said pressure relief passage opens said fuel pressurization chamber to said fuel return passage when said plunger approaches said advanced position.

Claim 24

The fuel injection system of claim 16, further comprising: means, attached to said second supply passage, for regulating the pressure of said fuel fluid.

Claim 25

The fuel injection system of claim 16 further comprising means, within said injector body, for biasing said plunger toward said retracted position.