US 4,649,886 AGranted

Fuel injection system for an internal combustion engine

AssigneeNippon Soken, Inc.

InventorsToshihiko Igashira, Taro Tanaka, Yasuyuki Sakakibara

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Abstract

A fuel injection system for an internal combustion engine includes sensors for sensing the reference rotational position of the engine, a unit injector for compressing the fuel and injecting a predetermined amount of the fuel, and an electronic control device. The unit injector includes an actuator such as a piezoelectric actuator, a piston, and an injection valve. The piezoelectric actuator comprises a columnar laminated body of disk-shaped piezoelectric elements. The laminated body is expanded or compressed in the axial direction of the column according to the application of a positive or a negative high voltage. The electronic control device controls the frequency of the voltage supplied to the actuator during the period from the timing of a reference rotational position and controls, accordingly, the amount of fuel injection in accordance with the frequency of the voltage supplied to the actuator.

Claims14

Dependent claims

A fuel injection system for an internal combustion engine of the type including at least one combustion chamber, said system comprising:

load sensing means for sensing engine load;
position sensor means for sensing a reference rotational position of the engine;
a unit injector, connected to a source of fuel, for compressing fuel and for injecting a predetermined amount of the compressed fuel into said engine combustion chamber, said unit injector including an actuator adapted to be selectively expanded and compressed in response to electrical driving voltages, a pump chamber, piston means operatively coupled to said actuator for delivering fuel to the pump chamber and for compressing said delivered fuel, and an injection valve for injecting said compressed fuel within the pump chamber into the combustion chamber;
and
electronic control means for selectively applying driving voltage to said actuator, for controlling the number of applications of the driving voltage during the period of each rotation of said engine in response to the sensing of engine rotational position by said position sensing means and for controlling the quantity of fuel injected into said combustion chamber on the basis of the number of drivings of said actuator so as to carry out at least three fuel injections n, where n is proportional to the load on the engine sensed by said load sensing means, for each combustion within said combustion chamber, said electronic control means being adapted to control said driving voltage of said actuator so as to reduce the interval between two successive injections of fuel into said combustion chamber as the rotational speed of the engine increases, said electronic control means, at least at low rotational speeds, also reducing the interval between two successive injections occurring later in each particular combustion as compared to the interval between two successive injections occurring earlier in each particular combustion.

2 more elements

A fuel injection system for an internal combustion engine of the type including at least one combustion chamber and a crankshaft, said system comprising:

angular position sensor means for sensing the rotational position of the engine crankshaft;
fuel injection means, connected to a source of fuel, for compressing fuel and for injecting a predetermined amount of the compressed fuel into said engine combustion chamber, said injection means including piezoelectric actuator means for selectively expanding and compressing in response to a driving signal, a pump chamber, means coupled to said actuator means for delivering fuel to said pump chamber and compressing said delivered fuel, and injection valve means for injecting a quantity of said compressed fuel from said pump chamber into the combustion chamber;
and
electronic control means for selectively applying driving signals to said actuator means, for controlling the number of applications of the driving signal during a period over which said rotation sensing means senses a predetermined reference engine rotational displacement, and for controlling the quantity of fuel injected into said combustion chamber by said actuator means,
said injector means comprising a substantially cylindrical upper casing, a nozzle body including means defining a nozzle, a needle valve arranged slidably in said nozzle body and a distance piece disposed between said nozzle body and said upper casing, said actuator means and said piston means being disposed in said upper casing, the closing force for said needle valve being exerted by the pressure of the fuel at said fuel source, the opening force for said needle valve being exerted by the pressure of the compressed fuel within said pump chamber, and further including menas defining a first fuel path formed in said upper casing and means defining a second path connected to said fuel path formed in said distance piece for supplying fuel from said fuel source to said pump chamber, a check valve provided in said second path formed in said distance piece, said check value including a ball, and a projection means, formed on said piston means, for regulating the position of said ball.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/549,372Filed 7 Nov 1983
Priority: JP 57-19815010 Nov 1982
Granted: 17 Mar 1987
Term ends: Not estimatedThe source records don’t support an estimate.

Classification16 codes

H02P 6/12
Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position;…:…
F02D 41/2096
Output circuits, e.g. for controlling currents in command coils: for controlling piezoelectric injectors
F02D 41/40
Of the high pressure type: with means for controlling injection timing or duration
F02D 41/402
With means for controlling injection timing or duration: multiple injections