GB2564653A

GB2564653A - Fuel injection equipment

Info

Publication number: GB2564653A
Application number: GB1711454.7A
Authority: GB
Inventors: Harper Mark
Original assignee: Delphi International Operations Luxembourg SARL
Current assignee: Delphi International Operations Luxembourg SARL
Priority date: 2017-07-17
Filing date: 2017-07-17
Publication date: 2019-01-23
Also published as: GB201711454D0

Abstract

A diesel fuel injector comprising a piezoelectric unit pump 36 and a needle valve within a nozzle assembly 24, where low pressure fuel enters the unit pump and is compressed before entering the nozzle assembly where it passes through the needle valve to be injected into the cylinder of the engine. There may be a high pressure chamber 22 disposed between the pump compression chamber 34 and the nozzle. The fuel injectors may be linked on a common low pressure fuel line, known as a daisy chain, the fuel injectors may also be supplied from a low pressure fuel tank. There may be a diesel engine provided with the fuel injectors. Also claimed is a control method which links received signals to power and torque requirements of the engine and which controls fuel flow through the injectors based on the signals received. Also claimed is an ECU which may run the control method for injectors as disclosed.

Description

FUEL INJECTION EQUIPMENT

TECHNICAL FIELD

The present invention relates to a diesel fuel injector having a piezoelectric unit-pump and a nozzle assembly and also, to an injection equipment having such fuel injector.

BACKGROUND OF THE INVENTION

The standard architecture of a fuel injection equipment is complex. It typically comprises a pump, a high pressure common rail to which several fuel injectors are connected in parallel. Said architecture has been a subject of attention since long in an attempt to develop simpler and lower cost rail-less systems still having nowadays performances, or improved performances.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing a diesel fuel injector for an internal combustion engine fuel injection equipment, said injector comprising a unit-pump cooperating with a nozzle assembly, so that in use, low pressure fuel entering the unit-pump is pressurised therein and is delivered to the nozzle assembly. In said nozzle assembly a needle valve member moves between a closed position preventing fuel injection and, an open position enabling fuel injection. Advantageously, said unitpump is a piezohydraulic pump assembly.

Also, in use, fuel at low pressure enters an inlet receiving space defined in the unit-pump body, then is pressurised in a compression chamber by a piezoelectric stack and then is kept under pressure in an outlet high pressure chamber wherefrom it is delivered to the nozzle.

The injector further comprises a first low pressure opening and a second low pressure opening both joining an inlet low pressure conduit defining said inlet receiving space.

The invention extends to a fuel injection equipment (FIE) for a diesel internal combustion engine, the FIE comprising a plurality of fuel injectors as set above. Said injectors are connected in-line forming a daisy chain, the first low pressure (LP) opening of an injector joining the second low pressure (LP) opening of the next inline injector.

Also, low pressure fuel stored in a tank is pumped and delivered to the injectors flowing from one injector to the other.

The invention extends to a diesel internal combustion engine provided with such a fuel injection equipment.

The invention extends to a control method of such a fuel injection equipment, said control method being uploadable in an command unit and comprising the steps of:

- computing signals received and relevant to the torque and power needs of said engine;

- determining the fuel quantity required to be sprayed in each of the engine cylinders in order to meet said engine needs;

- computing a command signal for each of the injector of the equipment;

- delivering said command signal to the injectors.

The invention extends to an electronic command unit (ECU) adapted to control a fuel injection equipment as described above to when executing such a control method.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

Figure 1 is a view of the fuel injection equipment as per the invention.

Figure 2 is a view of a fuel injector as per the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In reference to the figures is disclosed a fuel injection equipment 10 controlled by an electronic command unit (ECU) 12 wherein, fuel stored in a low pressure tank 14 is sucked by a feed pump 16 and is directly delivered to fuel injectors 18, six being on the represented example of figure 1. Said injectors 18 are connected in series, or in-line, forming a daisy chain, the low pressure fuel flowing from the first injector in the line to the last by successively going from one to the next via inter-connecting pipes. Each injector 18 has two fuel entries, the last injector 18 of the chain, the sixth in the figure having one of said entries closed.

More precisely, each fuel injector 16 has an elongated shape comprising the coaxial assembly of a unit-pump 20, a hydraulic accumulator 22 and an injection nozzle 24.

In a body 26, the unit pump 20 defines a low pressure conduit 28 opening at both ends to form said two entries or two fuel inlets 30 and, between said inlets 30 internally connects, from said conduit 28, a line 32 enabling fuel to downwardly flow toward a compression chamber 34 wherein fuel is pressurised by a piezoelectric stack 36 that cyclically varies the volume of said chamber 34.

Said piezoelectric stack 36 is electrically connected to the pins of a connector 38 arranged atop the unit-pump body 26 and adapted to inter-connect the ECU 12 to the stack 36.

When exiting the compression chamber, compressed fuel is delivered to the hydraulic accumulator 22 therein defining a high pressure chamber adapted to withstand a pressure of several thousands of bars. From said accumulator 22, high pressure fuel flows to the injection nozzle 24 wherein a needle valve member cyclically opens and closes injection holes through which fuel is sprayed in the cylinders of an internal compression engine.

Thanks to this arrangement wherein each injector 18 comprises its own unit-pump 20 controlled by the ECU 12, a controlled method 100 strategy of the equipment 10 can be implemented, said strategy individualising the fuel quantity to be pressurised and injected in each of the engine cylinder. Furthermore, the fuel injection equipment has a simplified architecture eliminating the high pressure pump, the common rail, the HP valve and HP sensor.

LIST OF REFERENCES fuel injection equipment electronic command unit - ECU tank pump fuel injector unit-pump hydraulic accumulator injection nozzle body low pressure conduit fuel inlet line compression chamber piezoelectric stack electric connector

100 control method

110 computing step

120 determining step

130 computing command signal

140 delivering step

Claims

CLAIMS:

1. Diesel fuel injector (18)for an internal combustion engine fuel injection equipment (10), said injector (18) comprising a unit-pump (20) cooperating with a nozzle assembly (24), so that in use, low pressure fuel entering the unit-pump (20) is pressurised therein and is delivered to the nozzle assembly (24) wherein a needle valve member moves between a closed position preventing fuel injection and, an open position enabling fuel injection and wherein, said unit-pump (20) is a piezohydraulic pump assembly.

2. Diesel fuel injector (18) as claimed in the preceding claim wherein, in use, fuel at low pressure enters an inlet receiving space defined in the unit-pump body (26), then is pressurised in a compression chamber (34) by a piezoelectric stack (36) and then is kept under pressure in an outlet high pressure chamber (22) wherefrom it is delivered to the nozzle (24).

3. Diesel fuel injector (18) as claimed in claim 2 further comprising a first low pressure opening (30) and a second low pressure opening (30) both joining an inlet low pressure conduit (28) defining said inlet receiving space.

4. Diesel fuel injection equipment (FIE - 10) for a diesel internal combustion engine, the FIE (10) comprising a plurality of fuel injectors (18) as claimed in any of the preceding claims.

5. Diesel fuel injection equipment (10) as claimed in claim 4 wherein the injectors (18) are as claimed in claim 3 and wherein said injectors (18) are connected in-line forming a daisy chain, the first LP opening (30) of an injector joining the second LP opening (30) of the next inline injector.

6. Diesel fuel injection equipment (10) as claimed in claim 5 wherein low pressure fuel stored in a tank (14) is pumped and delivered to the injectors (18) flowing from one injector to the other.

7. Diesel internal combustion engine provided with a fuel injection equipment (10) as claimed in any of the claims 4 to 6.

8. Control method (100) of a fuel injection equipment (10) as claimed in

5 any of the claims 4 to 6, said control method (100) being uploadable in an command unit and comprising the steps of:

(110) computing signals received and relevant to the torque and power needs of said engine;

(120) determining the fuel quantity required to be sprayed in each of the

10 engine cylinders in order to meet said engine needs;

(130) computing a command signal for each of the injector (18) of the equipment (10);

(140) delivering said command signal to the injectors (18).

15

9. Electronic command unit (ECU 12) adapted to control a fuel injection equipment (10) as claimed in any of the claims 4 to 6 when executing a control method (100) as claimed in claim 8.