The present invention relates to a fuel injector and in particular to a fuel injector intended for a direct injection of gasoline into the combustion chamber of an internal combustion engine.
The direct injection gasoline engines require the fuel injectors to operate under extreme conditions of temperature and pressure. In addition, the fuel injector must open and close very quickly in order to provide multi-pulse injection cycles necessary for the energy efficiency and the low emissions.
The current direct injection fuel injectors use either inward opening valves (nozzle or multi-hole type) in conjunction with the actuation of the solenoid or of the outward opening valves using the piezoelectric actuation. The outward opening piezoelectrically-actuated injector has demonstrated the greatest potential for reducing the fuel consumption, but the cost of the conductor's piezoelectric actuator is prohibitive for the high volume applications.
The piezoelectric actuator can provide a high opening force to overcome the return spring of the needle required to keep the valve closed and the high hydraulic forces generated during high pressure operation of the injector. The piezoelectric actuator also provides a rapid opening of the valve and can create a variable valve. However, the piezoelectric fuel injectors are very expensive to make compared to the solenoid-actuated injectors and require complex and expensive control systems for the operation of the piezoelectric actuator.
In contrast, the solenoid-actuated fuel injectors as described in EP1783356 are much cheaper to make. However, the known solenoid-actuated fuel injectors cannot provide the same level of performance as the devices actuated by piezoelectric apparatuses, mainly due to the lower opening force achievable by the electromagnetic solenoid actuators and the slower increase of the force over time.
The known solenoid-actuated fuel injectors use an armature spring to ensure its return to its rest position, that is, the closure of the injector. The armature spring is a return spring which is arranged above an armature. However, the position of the armature spring is not optimized because it reduces the air gap between the armature and the pole piece and thus reduces the magnetic force available to attract the armature.
As described in
The injector 10 further comprises a stop ring 30, a calibration sleeve 32 and a filter 34. The assembly of the various pieces of the injector 10 in production is complex and generates rejects during the mounting, in particular of a stop ring 30. In addition, the insertion of the stop ring 30 and of the calibration sleeve 32 generates particles which are sources of degradation of the injection in operation. The filter 34 is made of plastic or of stainless steel mesh. In addition, the filter 34 is mounted at the end of the assembly line of the injector 10 and therefore the generation of particles upstream cannot be prevented.
The object of the present invention is to provide a solution which will alleviate the above-mentioned problem.
The present invention aims to overcome the drawbacks mentioned above by proposing a simple and economical solution which aims to reduce the number of assembled pieces by producing a single piece which incorporates the calibration sleeve, the stop ring and the filter. The invention consists of a combined filtration and calibration assembly of a fuel injector arranged in an internal combustion engine. The combined filtration and calibration assembly extends along a longitudinal axis. The combined filtration and calibration assembly comprises a calibration sleeve provided with a longitudinal bore as well as a multitude of filtration holes. The combined filtration and calibration assembly has a calibrated orifice in the bore. In addition, the calibrated orifice is produced by lamination. Alternatively, the calibrated orifice is a circular plate provided at its center with a calibrated hole opening on both sides. The circular plate is arranged in the bore of the combined filtration and calibration assembly. In addition, according to the invention, a method for producing a combined filtration and calibration assembly comprises the following production steps:
According to the alternative to the invention, a production method comprises the following production steps:
Furthermore, according to the invention, a fuel injector comprises a combined filtration and calibration assembly as described above.
Other characteristics, aims and advantages of the invention will become apparent on reading the detailed description which follows, and with reference to the appended drawings, given by way of non-limiting example and in which:
The invention is now described with reference to the figures and for the sake of clarity and conciseness of the description, an orientation from top to bottom according to the direction of
As shown in
According to
The body 114 of the injector 110 comprises an open upper end and a lower end provided with an injection nozzle. The body 114 extends along the X axis.
The electromagnetic actuator 112 comprises an annular fixed coil 124, a fixed pole piece 126 and an armature 128. The movable armature 128 is provided with an axial hole inside which the needle 116 is axially slidably guided.
The needle 116 is axially movable in the body 114 between a closed position and an open position of the injection nozzle. The needle 116 comprises a first end arranged with the ball 118 and a second end arranged close to the pole piece 126.
The armature spring 122 is fixed at one end to the armature 128 and at the other end to the needle 116. The armature spring 122 is a tension spring with contiguous turns at ends thereof. The armature spring 122 is a return spring.
As described in
In
In a not shown alternative of the invention described in
The main advantages expected by the invention are:
According to
An alternative to the method for producing the combined filtration and calibration assembly 130 is described below with reference to
An alternative to drilling holes with a laser by electrochemical dissolution of the material or by electroforming (electroforming or “photoetching”).
10 injector
12 actuator
14 body
16 needle
18 ball
20 calibration spring
22 armature spring
24 fixed coil
26 pole piece
28 armature
30 stop ring
32 calibration sleeve
34 filter
110 injector
112 actuator
114 body
116 needle
118 ball
120 calibration spring
122 armature spring
124 fixed coil
126 pole piece
128 armature
130 combined filtration and calibration assembly
132 lower face
134 upper face
136 filtration holes
138 calibrated orifice
140 filtering section
142 restriction
144 fuel direction for injector named GDI M14
146 fuel direction for injector named GDI M16
X longitudinal axis
A roll up a tube or deform a plate into a tube
B insert a circular plate into the tube and crimp the circular plate
C laminate the calibrated orifice
Number | Date | Country | Kind |
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FR1908332 | Jul 2019 | FR | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2020/070650 | 7/22/2020 | WO |