Method for producing a combined filtration and calibration assembly

Abstract

A combined assembly for filtering and calibrating a fuel injector arranged in an internal combustion engine, the combined filtration and calibration assembly extending along a longitudinal axis and comprising a calibration sleeve provided with a longitudinal bore and defining a multitude of filtration holes. The combined filtration and calibration assembly has a calibrated opening in the bore.

Claims

1. A method for producing a combined filtration and calibration assembly of a fuel injector arranged in an internal combustion engine, the combined filtration and calibration assembly extending along a longitudinal axis and comprising a single calibration sleeve provided with a longitudinal bore and defining a multitude of filtration holes, the combined filtration and calibration assembly having a calibrated orifice in the bore, said method comprising, in the following order, the steps of: rolling up a tube made of stainless steel to form said calibration sleeve with said longitudinal bore; inserting a circular plate into the tube, said calibrated orifice being provided at a center of said circular plate with a calibrated hole opening on both sides of said circular plate; crimping the circular plate; and then subsequent to the steps of rolling up the tube, inserting the circular plate into the tube, and crimping the circular plate, performing the step of drilling the filtration holes using a laser.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIG. 1 is a cross-sectional view of an injector of the prior art.

(3) FIG. 2 is a cross-sectional view of an injector of the prior art.

(4) FIG. 3 is a cross-sectional view of an injector according to the invention.

(5) FIG. 4 is a cross-sectional view of a combined filtration and calibration assembly according to the invention.

(6) FIG. 5 is a cross-sectional view of an injector named GDI M14 according to the invention.

(7) FIG. 6 is a cross-sectional view of an injector named GDI M12 according to the invention.

(8) FIG. 7 is a cross-sectional view of the production of the combined filtration and calibration assembly according to the invention on step-by-step basis.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) 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 FIG. 3 will be used without any limiting intention as to the extent of the protection, in particular with regard to the various installations of an injector in a vehicle. Words such as up, down, below, above, vertical, move up, move down . . . will be used without limiting intent.

(10) As shown in FIG. 3, the invention relates to a fuel injector 110 for an internal combustion engine, here the injector 110 is a gasoline injector. The description will detail the elements of the invention and will remain more succinct and general as to the surrounding elements.

(11) According to FIG. 3, the injector 110 extends along a longitudinal axis X. The injector 110 is a gasoline injector for an internal combustion engine. The injector 110 comprises an electromagnetic actuator 112, a body 114, a needle 116 with a ball 118 integral with the needle 116, a calibration spring 120 and an armature spring 122 and a combined filtration and calibration assembly 130.

(12) 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.

(13) 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.

(14) 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.

(15) 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.

(16) As described in FIGS. 3 and 4, the combined filtration and calibration assembly 130 of the injector 110 extends along the longitudinal axis X. The combined filtration and calibration assembly 130 additionally comprises a lower face 132 and an upper face 134. The lower 132 and upper 134 faces can be used as an adjustment face of the calibration spring 120. The combined filtration and calibration assembly 130 comprises a calibration sleeve provided with a longitudinal bore and provided with a multitude of filtration holes 136. The combined filtration and calibration assembly 130 has a calibrated orifice 138 in the bore. The calibrated orifice 138 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 130. The combined filtration and calibration assembly 130 comprises a filtering section 140 comprising the filtration holes 136 laser drilled in the body of a deep-drawn part. In FIG. 4 are shown a fuel stream 144 which indicates the flow direction of the fuel in the injector 110 of GDI M14 type and a fuel stream 146 indicating the flow of fuel in the injector 110 of GDI M16 type.

(17) In FIG. 5 the injector 110 named GDI M14. The combined filtration and calibration assembly 130 is mounted with the lower face 132 oriented downward and arranged against the calibration spring 120 while the upper face 134 is oriented upward. The combined filtration and calibration assembly 130 is mounted tightly in an upper part of the injector 110. In FIG. 6, the injector 110 named GDI M12 or GDI M16. The combined filtration and calibration assembly 130 is mounted upside down with respect to the mounting of the injector 110 described in FIG. 5. In FIG. 6, the upper face 134 is arranged against the calibration spring 120 while the lower face 132 is arranged in the top part of the injector 110. The combined filtration and calibration assembly 130 is mounted tightly in a lower part of the injector 130, on the calibration spring 120 side.

(18) In a not shown alternative of the invention described in FIGS. 5 and 6, the filtering section 140 comprising the laser-drilled filtration holes 136 can be set to an equivalent calibrated orifice size 138. The calibrated orifice 138 serves for the fuel stream by managing the pressure drop and the pressure waves. The diameter of the filtration hole 136 is comprised between 20 m and 25 m and the number of filtration holes is comprised between 600 and 2800 filtration holes 136 required for the calibrated orifice 138 equivalent to 0.7 mm in diameter. The calibrated orifice 138 may be an add-on part or an integrated feature created from a restriction 142 of the body of the combined filtration and calibration assembly 130. The advantage is that a resting volume is created for the retention of particles, thus minimizing the risk of clogging of the filtering section 140. The body of the combined filtration and calibration assembly 130 should be made of stainless steel with the possibility of adding a surface hardening process to strengthen the component but also to prevent seizures during its insertion into the injector 110.

(19) The main advantages expected by the invention are: simple basic components that can be adjusted like the filtering section 140, the expected reduction in costs, the protection against particles of the assembly process during the mounting and the calibration of the injector 110, the retention volume of the particles in the two mounting positions, the fuel injector 110 is standardized with the calibrated orifice 138 reducing the error in case of use of an orifice plate after standardization.

(20) According to FIG. 7, the method for producing the combined filtration and calibration assembly 130 of the invention as described above comprises the production steps which are: step A: roll up a tube or deform a plate into a tube, step C: laminate the calibrated orifice 138, drill the filtration holes 136 using a laser

(21) An alternative to the method for producing the combined filtration and calibration assembly 130 is described below with reference to FIG. 7 and in which the steps of production are: step A: roll up a tube, step B: insert a circular plate into the tube and crimp the circular plate, drill filtration holes 136 using a laser.

(22) An alternative to drilling holes with a laser by electrochemical dissolution of the material or by electroforming (electroforming or photoetching).

LIST OF REFERENCES USED

(23) 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