US 4,628,881 A · Pressure-controlled fuel injection for internal combustion engines

Abstract

An electronically controlled fuel supply system for an internal combustion engine. The timing of the commencement of fuel injection into each combustion chamber is not fixed relative to the rotational position of the camshaft or other engine components. A unit injector assembly associated with each combustion chamber includes a control module and an accumulator type injector module. The control module contains a solenoid valve and, in some embodiments, a hydraulic pressure intensifier. The accumulator type injector module contains an injector nozzle, a hydraulic accumulator, and a non-return valve for admitting liquid fuel under pressure into the accumulator. In operation, an electrical control system supplies an electrical signal to the control module an appreciable portion of the engine cycle in advance of the time when fuel injection is to be initiated in the particular combustion chamber. In response to that electrical signal, the solenoid valve admits liquid fuel under pressure into the hydraulic pressure intensifier. The output of the intensifier provides a metering and intensifying chamber in which the pressure of the fuel continues to increase until near the time when fuel injection is to commence. As pressure builds up, fuel flows through the non-return valve into the accumulator. Under control of the electrical signal the solenoid valve then shuts off the flow of liquid fuel into the intensifier. The transfer of fuel under high pressure from the intensifier chamber to the accumulator is discontinued due to the non-return valve, and the injector nozzle then fires. Alternatively, the solenoid valve admits liquid fuel under pressure directly through the non-return valve into the accumulator, with the turn-off of the solenoid valve causing the injector nozzle to fire. The control system may be utilized for operating the engine in a modified engine cycle in which firing cycles are selectively eliminated. The control system may also be utilized for controlling different cylinders of an engine differently from each other. The control of engine power is accomplished by either electrical or hydraulic means, or a combination thereof, and does not involve any mechanical adjustments within the unit injector assemblies.

Claims68

Dependent claims

The method of injecting fuel into a combustion chamber of an internal combustion engine, comprising the steps of:

(a) selecting an accumulator type fuel injector having a fuel input, and characterized by the fact that the withdrawal of applied pressure from its input initiates the injection of a fuel charge;
(b) placing said fuel injector in operative relation to the combustion chamber;
(c) selecting an electronically controlled three-way valve for selectively admitting fuel into said accumulator type fuel injector;
(d) coupling said valve to said injector;
(e) coupling a source of liquid diesel fuel to said valve;
and
(f) whenever it is desired to inject a fuel charge into the combustion chamber, applying an electronic control signal to said valve to open said valve for a selected period of time;
whereby at the end of said selected period of time when said valve closes to pressure and opens to vent, said accumulator type injector causes the injection of the fuel charge into the combustion chamber to be initiated;
the termination of injection of the fuel charge being controlled by said accumulator type fuel injector and not by said valve or said electronic control signal.

6 more elements

Fuel injection apparatus for a diesel engine comprising, in combination:

(a) a source of liquid fuel at a predetermined common supply pressure;
(b) a separate unit injector assembly associated with each combustion chamber of the engine;
(c) means for supplying one electronic control signal per engine cycle to each of said unit injector assemblies in order to control the repetitive injection of a prescribed fuel charge into the combustion chamber of the associated cylinder;
(d) each of said unit injector assemblies including a pressure intensifier, a solenoid valve for controlling the admission of a fuel charge to said pressure intensifier, an accumulator type injector, and a non-return valve coupling the output of said pressure intensifier to said accumulator injector;
(e) said control signal being operative once in each engine cycle to open said solenoid valve an appreciable portion of said cycle in advance of the injection of the fuel charge, said control signal also being operative to close said solenoid valve at the time when the fuel charge is to be injected;
(f) said pressure intensifier being operative to raise the pressure of the fuel charge received therein to at least several times the pressure level of said source, the closing of said solenoid valve being operative to relieve the pressure in said intensifier;
(g) said non-return valve opening in response to the opening of said solenoid valve when the fuel pressure produced by said pressure intensifier exceeds the residual pressure in said accumulator injector so that fuel at the intensified pressure is transferred to said accumulator injector, and closing in response to the closing of said solenoid valve;
(h) said accumulator injector being responsive to the closing of said non-return valve and the release of pressure in said intensifier for causing the injection of the fuel charge, the injection of the fuel charge being then powered by the differential pressure between the intensified fuel pressure in said accumulator injector and the pressure in the combustion chamber;
and
(i) means for adjusting at least one of the pressure level of said common supply pressure, and the time interval during which said solenoid valve is open, in order to correspondingly adjust the magnitude of the fuel charge to be injected into said cylinder.

7 more elements

In a fuel injection system for an internal combustion engine wherein fuel supplied at substantially constant pressure is converted to a series of metered charges at a pressure much greater than the supply pressure, an injector module comprising, in combination:

an elongated housing having an entry port at one end thereof and a spray tip at its other end;
an elongated needle valve member disposed within said housing, one end of said needle valve member having a transverse flat surface which is exposed to said entry port, the other end of said needle valve member having a valve face normally engaging a valve seat formed within the lower end of said housing adjacent said spray tip;
a spring separator disposed within and secured to said housing intermediate the two ends thereof, but located closer to said entry port than to said spray tip;
said needle valve member having an annular shoulder formed therein intermediate its ends;
a first helical spring extending between said shoulder of said needle valve member and one side of said spring separator for urging said needle valve member against said valve seat, said first spring having a comparatively high spring force;
a valve member having a circular opening, said valve member being disposed within said housing with said one end of said needle valve member extending through said circular opening thereof;
both said valve member and said needle valve member being normally exposed to said entry port;
and
a second helical spring extending between said valve member and said spring separator for urging said valve member towards said entry port, said second spring having a low spring force compared to said first spring.

6 more elements

The method of injecting liquid fuel charges into a combustion chamber of an internal combustion engine, comprising the steps of:

(a) providing a source of liquid fuel under controllable pressure;
(b) selecting a pressure intensifier having an intensifier piston and having a pressure intensifying chamber with a selected volume;
(c) selecting an accumulator type fuel injector having an accumulator chamber with a selected volume;
(d) admitting fuel from said source to fill said intensifying chamber;
(e) once during each firing cycle of said engine, constraining the fuel in said intensifying chamber against returning to said source, so that the fuel in said intensifying chamber may be compressed;
(f) then, commencing an appreciable portion of the engine operating cycle in advance of the time when injection is to be accomplished, and throughout an interval whose duration is longer than the time required for injection, drawing a quantity of fuel from said source and utilizing its pressure to gradually reduce the volume of said intensifying chamber until a selected pressure level of said fuel in said intensifying chamber is reached which is higher than the nozzle tip valve closing pressure of said injector;
(g) placing said pressure intensifying chamber in fluid communication through a non-return valve with said accumulator type fuel injector;
(h) transferring fuel from said intensifying chamber into the accumulator chamber of said accumulator type fuel injector at said selected pressure level;
and
(i) when injection is to be initiated, then releasing the pressure within said intensifying chamber by reversing the direction of motion of the intensifier piston, so that the non-return valve immediately closes off the fluid communication between said intensifying chamber and said accumulator chamber of said accumulator type fuel injector, and such release of pressure from within said intensifying chamber causes the nozzle tip valve to open;
whereupon said injector then discharges into the combustion chamber a fuel charge whose mass is determined in part by the fixed volume of the accumulator chamber and is linearly related to the difference between said predetermined pressure level and said tip valve closing pressure.

8 more elements

The method of injecting fuel into an internal combustion engine having at least one cylinder with an associated combustion chamber, and of controlling both the quantity and the timing of each fuel charge that is injected into the combustion chamber so as to thereby control the engine operation, comprising the steps of:

(a) providing a source of liquid fuel under a predetermined pressure;
(b) selecting a unit injector assembly having
(1) a pressure intensifier including a larger and a smaller diameter piston having the capability of raising said fuel source pressure to a desired injection pressure,
(2) an electrically actuated control valve capable of being energized for a variably substantial part of an engine operating cycle to allow said intensifier to generate said injection pressure prior to the injection event;
and
(3) an accumulator storage chamber capable of storing liquid fuel under an elevated pressure level, which pressure level determines the fuel charge to be injected;
(c) coupling said fuel source to said control valve of said injector assembly;
(d) turning said control valve on and off once during each power operating cycle of said engine so that whenever said valve is turned on, a chamber adjacent to said larger intensifier piston is pressurized, thus causing the movement of said smaller piston through a distance sufficient to displace said fuel charge into said storage chamber under a selected injection pressure;
the movement of said smaller piston when the valve is energized being controlled by a balance of forces resulting from the pressure level of said fuel source, the pressure level on said intensifier pistons and the time interval during which said valve is energized;
(e) de-energizing said solenoid to open said control valve to a vent line and close said valve coupled to said source, thus initiating injection of said fuel charge into said combustion chamber;
and
(f) simultaneously with the turning off of said control valve, causing
(1) said chamber adjacent to said larger piston, previously connected to said pressurized fuel source, to be connected to said vent line, said vent line leading to a fuel reservoir supplying said pressurized source and having a minimum flow resistance in order to allow said piston to return to the same fixed point at the end of each venting stroke, and
(2) the discharge from said storage chamber of said fuel charge into said combustion chamber;
the instant of time each said fuel charge begins its injection into said combustion chamber being determined by the time when said control valve is opened to vent;
so as to selectively determine the power and acceleration of said engine.

13 more elements

The method of controlling the mass of liquid fuel charges injected into a combustion chamber of an internal combustion engine, comprising the steps of:

(a) providing a source of liquid fuel at a selected pressure level which is normally constant but selectively variable;
(b) providing a pressure intensifying means whose pressure multiplying movement is a function of said source pressure and the compressibility and density properties of the liquid fuel;
(c) establishing a minimum pressure level at which the fuel may be injected into the combustion chamber;
(d) periodically selecting a quantity of liquid fuel from said source;
(e) using said intensifying means to multiply the pressure level of each such selected fuel quantity by a fixed multiple such that its pressure level then exceeds said minimum pressure level;
(f) forcing said selected fuel quantity into an accumulator type storage chamber;
and
(g) in response to and under the control of each such selected fuel quantity whose selected pressure has been thus multiplied, injecting into the combustion chamber a charge of liquid fuel whose mass is a direct function of the volume of said chamber in which the selected fuel quantity has been stored and of the difference between said multiplied source pressure and said minimum pressure level.

5 more elements

An accumulator type fuel injection system for an internal combustion engine comprising, in combination:

(a) a unit injector for each combustion chamber of said engine;
(b) a three-way valve incorporated in each said unit injector and actuated by a corresponding separate solenoid;
(c) a fuel reservoir with passages leading to each of said three-way valves;
(d) a pump means to draw fuel from said reservoir in order to raise the fuel to a predetermined source rail supply pressure and having passages leading to each of said three-way valves;
(e) an accumulator chamber of predetermined volume in each said unit injector having an inlet check valve and an outlet needle valve;
(f) control means to control the level of fuel pressure generated by said pump means and to actuate each of said solenoids;
(g) passages controlled by each said three-way valve to pressurize or depressurize said corresponding inlet check valve as required;
(h) said check valve being in the form of a T-valve having a spring biasing means acting on one end, to serve both as said inlet check valve to said accumulator chamber and as a bushing for said needle valve;
and
(i) said needle valve having an upper stem which slideably operates within said T-valve bushing, and having a lower end which abuts a seat adjacent to a nozzle orifice leading into a combustion chamber of said engine;
whereby when said solenoid is energized by said control means the liquid fuel in said accumulator chamber is thereby compressed to both meter and store in said accumulator chamber a fuel charge to be injected whose mass is a function of the volume of said accumulator chamber, the compressibility and density of the fuel, and the pressure in said accumulator chamber;
and
whereby when said solenoid is de-energized by said control means the pressure above said T-valve and said upper stem of said needle valve is reduced, and said needle valve is triggered to lift off of said seat causing the injection of said fuel charge into said combustion chamber through said nozzle orifice using the energy of the compressed fuel in said accumulator chamber to accomplish the injection process.

10 more elements

Apparatus for injecting fuel into a combustion chamber of an internal combustion engine, comprising, in combination:

(a) an accumulator type fuel injector having a fuel input, said fuel injector being positioned in operative relation to the combustion chamber and characterized by the fact that the withdrawal of pressure from its input initiates the injection of a fuel charge;
(b) an electronically controlled three-way solenoid valve having fuel supply and vent inputs, and a common port which is normally closed to supply and open to vent.
(c) a source of liquid fuel at a predetermined common supply pressure, coupled to said fuel supply input of said valve;
(d) means coupling said common port of said valve directly to said fuel input of said injector;
(e) means for supplying energizing current to said solenoid valve a substantial portion of an engine cycle in advance of the time when injection is to commence, so as to open said common port to supply and close it to vent;
(f) means for interrupting said energizing current immediately prior to the time when injection is to commence, thereby closing said valve to source pressure and opening it to vent so that said fuel injector then initiates the injection of the fuel charge;
and
(g) means for adjusting at least one of the pressure level of said common supply pressure, and the time interval during which said solenoid valve is open, in order to correspondingly adjust the magnitude of the fuel charge to be injected into said cylinder;
the termination of injection of the fuel charge being controlled by said accumulator type fuel injector and not by said valve, and the quantity of fuel to be injected being controlled by the peak pressure of the accumulator chamber and the inherent closing pressure of said accumulator type fuel injector.

6 more elements

In a diesel fuel injection system, a unit injector assembly comprising, in combination:

a pressure intensifier having an intensifier piston, an input end with a low pressure chamber, and an output end with a high pressure chamber;
means for supplying liquid fuel from an adjustable common rail pressure source through a check valve to said high pressure chamber;
a three-way solenoid valve having a fuel inlet adapted to be coupled to said common rail pressure source, a common outlet coupled to said low pressure chamber of said intensifier, and a drain output, said solenoid valve normally being open to the drain output;
electrical control means for selectively energizing said solenoid valve so as to open said valve to its fuel inlet and close said valve to drain, and hence to apply pressure through said hydraulic intensifier to said high pressure chamber so that said fuel supply check valve becomes closed;
an accumulator type fuel injector having an accumulator chamber and an outlet valve;
a non-return valve coupling said high pressure chamber of said hydraulic intensifier to said accumulator chamber;
said electrical control means being operable for keeping said solenoid valve open throughout a time interval which is longer than the duration of an injection event, so that the fuel pressure in said high pressure chamber of said hydraulic intensifier increases exponentially towards a selected multiple of said common rail pressure, and is at the same time transmitted through said non-return valve into said accumulator injector;
and
said electrical control means also being operable, whenever a fuel charge is to be injected, for closing said solenoid valve to inlet and opening it to drain, thereby reversing the direction of said intensifier piston, relieving the pressure in said high pressure chamber, and causing said non-return valve to close;
whereby said outlet valve opens and the injection of the fuel charge is then initiated by said accumulator injector and continues until terminated by the spring closing action of the injector, with the result that the mass of the injected fuel charge bears a linear relationship to the then existing pressure level of said common rail pressure.

7 more elements

Dependencies are inferred from the claim text.

Pressure-controlled fuel injection for internal combustion engines

Life of this patent

Pressure-controlled fuel injection for internal combustion engines

Life of this patent

Abstract

Claims68