METHOD FOR PRODUCING A COMBINED FILTRATION AND CALIBRATION ASSEMBLY

Description

TECHNICAL FIELD

[0001] The present invention relates to a fuel injector and in particular a fuel injector intended for direct injection of gasoline into the combustion chamber of an internal combustion engine. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Direct-injection gasoline engines require fuel injectors to operate under extreme temperature and pressure conditions. Furthermore, the fuel injector must open and close very rapidly to provide the multi-pulse injection cycles necessary for fuel efficiency and low emissions.

[0003] Current direct injection fuel injectors use either inward-opening valves (nozzle or multi-hole type) in conjunction with solenoid actuation or outward-opening valves using piezoelectric actuation. The piezoelectrically actuated outward-opening injector has demonstrated the greatest potential for reducing fuel consumption, but the cost of the driver's piezoelectric actuator is prohibitive for high-volume applications.

[0004] The piezoelectric actuator can provide a high opening force to overcome the needle return spring required to keep the valve closed and the high hydraulic forces generated during high-pressure operation of the injector. The piezoelectric actuator also provides rapid valve opening and can implement a variable valve timing system. However, piezoelectric fuel injectors are very expensive to produce compared to solenoid-operated injectors and require complex and costly control systems for the piezoelectric actuator to operate.

[0005] In contrast, solenoid-operated fuel injectors such as those described in EP1783356 are much less expensive to produce. However, known solenoid-operated fuel injectors cannot provide the same level of performance as piezoelectrically actuated devices, primarily due to the lower opening force achievable by electromagnetic solenoid actuators and the slower force increase over time.

[0006] JP 2010167351A, DE102015226528 A1 and EP3279462A1 relate to a method for carrying out a combined filtration and calibration assembly.

[0007] Solenoid-operated fuel injectors use an armature spring to return the injector to its rest position, i.e., the injector is closed. The armature spring is a return spring positioned above an armature. However, the armature spring's position is not optimized because it reduces the air gap between the armature and the pole piece, thus reducing the magnetic force available to attract the armature.

[0008] As described in the figures 1 And 2 From an existing injector 10, the injector 10 comprises an electromagnetic actuator 12, a body 14, a needle 16 including an integral ball 18, a calibration spring 20, and an armature spring 22. The electromagnetic actuator 12 comprises a fixed coil 24, a pole piece 26, and an armature 28. The operating method of the injector 10 not shown comprises: A resting stage in which the actuator 12 is not powered, the assembly consisting of the needle 16 and the ball 18 is in contact with a seat, and the injector 10 is closed. There is no fuel injection. A pre-opening stage in which the actuator 12 is powered, the pole piece 26 attracts the armature 28, the calibration spring 20 and the armature spring 22 are compressed. The armature 28 drives the needle 16 and the ball 18 upwards, the needle 16 and the ball 18 being away from the seat, and the injector 10 is open. There is fuel injection. An opening stage in which the actuator 12 is powered, the armature 28 continues to move towards the pole piece 26, the calibration spring 20 and the armature spring 22 continue to be compressed. a closing step in which the actuator 12 is not powered, the assembly consisting of the needle 16 and the ball 18 is in contact with the seat and the injector 10 is closed.There is no fuel injection.

[0009] The injector 10 also includes a retaining ring 30, a calibration sleeve 32, and a filter 34. Assembling the various parts of the injector 10 during production is complex and generates scrap during assembly, particularly of the retaining ring 30. Furthermore, the insertion of the retaining ring 30 and the calibration sleeve 32 generates particles that can degrade the injection process during operation. The filter 34 is made of plastic or stainless steel mesh. Moreover, the filter 34 is mounted at the end of the injector 10 assembly line, and therefore the generation of particles upstream cannot be prevented.

[0010] The object of the present invention is to provide a solution that will mitigate the problem mentioned above. SUMMARY OF THE INVENTION

[0011] The present invention aims to overcome the aforementioned drawbacks by providing a simple and economical solution that reduces the number of assembled parts by creating a single piece that integrates the calibration sleeve, the stop ring, and the filter. The invention consists of a method for implementing a combined filtration and calibration assembly according to claims 1 and 2.

[0012] Furthermore, according to the invention, a fuel injector conforming to claim 3 is presented. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other features, purposes, and advantages of the invention will become apparent from the detailed description that follows, and with reference to the accompanying drawings, given by way of non-limiting example and on which: There figure 1 is a cross-sectional view of a prior art injector. The figure 2 is a cross-sectional view of a prior art injector. figure 3 is a cross-sectional view of an injector according to the invention. figure 4 is a cross-sectional view of a combined filtration and calibration assembly according to the invention. figure 5 is a cross-sectional view of an injector named GDI M14 according to the invention. figure 6 is a cross-sectional view of an injector named GDI M12 according to the invention. figure 7 is a cross-sectional view of the step-by-step realization of the combined filtration and calibration assembly according to the invention. DESCRIPTION OF PREFERRED IMPLEMENTATION METHODS

[0014] The invention is now described with reference to the figures and, for the sake of clarity and conciseness, in a top-to-bottom orientation according to the direction of the figure 3 will be used without any intention of limiting the scope of protection, particularly with regard to the different installations of an injector in a vehicle. Words such as "up, down, below, above, vertical, ascend, descend..." will be used without limitation.

[0015] As depicted in the figure 3 The invention relates to a fuel injector 110 for an internal combustion engine; in this case, injector 110 is a gasoline injector. The description will detail the elements of the invention and remain more succinct and general regarding surrounding elements.

[0016] According to the figure 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 attached to the needle 116, a calibration spring 120 and an armature spring 122, and a combined filtration and calibration assembly 130.

[0017] The body 114 of the injector 110 comprises an open upper end and a lower end fitted with an injection nozzle. The body 114 extends along the X-axis.

[0018] The electromagnetic actuator 112 comprises a fixed annular 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 guided to slide axially.

[0019] The needle 116 is axially movable within the body 114 between a closed 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 near the pole piece 126.

[0020] The armature spring 122 is attached 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 coils joined at its ends. The armature spring 122 is a return spring.

[0021] As described in the figures 3 And 4The combined filtration and calibration assembly 130 of the injector 110 extends along the longitudinal axis X. The combined filtration and calibration assembly 130 further includes a lower face 132 and an upper face 134. The lower face 132 and upper face 134 can be used as adjustment faces for the calibration spring 120. The combined filtration and calibration assembly 130 includes a calibration sleeve having a longitudinal bore and numerous 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 with a calibrated hole in its center 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 includes a filter section 140 comprising the filter holes 136 laser-drilled into the body of a stamped part. In the . figure 4 shown are a fuel flow 144 which indicates the direction of fuel flow in the injector 110 known as type GDI M14 and a fuel flow 146 indicating the fuel flow in the injector 110 known as type GDI M16.

[0022] In the figure 5 the injector 110 designated GDI M14. The combined filtration and calibration assembly 130 is mounted with its lower face 132 oriented downwards and positioned against the calibration spring 120, while its upper face 134 is oriented upwards. The combined filtration and calibration assembly 130 is tightly mounted in the upper part of the injector 110. In the figure 6 , the injector 110 designated GDI M12 or GDI M16. The combined filtration and calibration assembly 130 is mounted in reverse relative to the mounting of injector 110 described in the figure 5 In the figure 6 The upper face 134 is arranged against the calibration spring 120 while the lower face 132 is arranged in the upper 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 side of the calibration spring 120.

[0023] In an alternative not shown of the invention described in the figures 5 et 6 The filter section 140, which includes laser-drilled filter holes 136, can be adjusted to an equivalent calibrated orifice size 138. The calibrated orifice 138 manages fuel flow by controlling pressure drop and pressure waves. The diameter of the filter hole 136 is between 20 µm and 25 µm, and the number of filter holes 136 required for the calibrated orifice 138 is between 600 and 2800, equivalent to a diameter of 0.7 mm. The calibrated orifice 138 can be an added component or an integrated feature created from a restriction 142 in the body of the combined filter and calibration assembly 130. The advantage is that a holding volume is created for particle retention, thus minimizing the risk of fouling of the filter 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 seizing when inserted into the injector 110. The main advantages expected from the invention are: . simple basic components that can be adjusted such as the filter section 140, the expected cost reduction, the protection against particles from the assembly process during the mounting and calibration of the injector 110, the particle retention volume in both mounting positions, the fuel injector 110 is calibrated with the calibrated orifice 138 reducing the error when using an orifice plate after calibration.

[0024] According to the figure 7The method for implementing the combined filtration and calibration assembly 130 of the invention, as described above, comprises the following implementation steps: Step A: Roll a tube or deform a plate into a tube, Step C: Laminate the calibrated orifice 138, drill the filtration holes 136 using a laser An alternative to the method for implementing the combined filtration and calibration assembly 130 is described below, based on the figure 7 and in which the implementation stages are: Step A: roll a tube, Step B: insert a circular plate into the tube and crimp the circular plate, drill 136 filtration holes using a laser. LIST OF REFERENCES USED

[0025] 10 injector 12 actuator 14 body 16 needle 18 ball 20 calibration spring 22 coil armature spring 24 fixed 26 pole piece 28 armature 30 retaining ring 32 calibration sleeve 34 filter 110 injector 112 actuator 114 body 116 needle 118 ball 120 calibration spring 122 coil armature spring 124 fixed 126 pole piece 128 armature 130 combined filtration and calibration assembly 132 bottom face 134 top face 136 filtration holes 138 calibrated orifice 140 filtration section 142 restriction 144 fuel direction for injector designated GDI M14 146 fuel direction for injector designated GDI M16 X Longitudinal axis Roll a tube or deform a plate into a tube Insert a circular plate into the tube and Crimp the circular plate. Seal the calibrated orifice.

Claims

1. A method for producing a combined filtration and calibration assembly (130) of a fuel injector (110) arranged in an internal combustion engine, the combined filtration and calibration assembly (130) extending along a longitudinal axis (X) and comprising a calibration sleeve provided with a longitudinal bore and provided with a multitude of filtration holes (136), the combined filtration and calibration assembly (130) having a calibrated orifice (138) in the bore wherein the production steps are: - roll up a stainless steel tube so as to form the calibration sleeve provided with longitudinal bore; - insert a circular plate into the tube, the calibrated orifice (138) being formed by a calibrated hole opening on both sides of the calibration plate, in its centre; - crimp the circular plate; - drill filtration holes using a laser.

2. Method for producing a combined filtration and calibration assembly (130) of a fuel injector (110) arranged in an internal combustion engine, the combined filtration and calibration assembly (130) extending along a longitudinal axis (X) and comprising a calibration sleeve provided with a longitudinal bore and provided with a multitude of filtration holes (136), the combined filtration and calibration assembly (130) having a calibrated orifice (138) in the bore wherein the production steps are: - roll up a stainless steel tube so as to form the calibration sleeve provided with longitudinal bore; - produce the calibrated orifice (138) by rolling; - drill filtration holes using a laser.

3. Fuel injector (110) for an internal combustion engine comprising an electromagnetic actuator (112), a body (114), a needle (116) with a ball being part of the needle (116), a calibration spring (120) and a frame needle (122) and a combined filtration and calibration assembly (130); the body (114) of the injector extending along a longitudinal axis (X) and comprising an opened upper end and lower end providing the injection nozzle, the needle being axially mobile in the body between a closed position and an opened position of the injection nozzle; the combined filtration and calibration assembly (130) extending in the body (114) along the longitudinal axis from a lower face (132) and on an upper face (134), and comprising a stainless steel calibration sleeve providing a longitudinal bore and providing a multitude of filtration holes (136), the combined filtration and calibration assembly (130) having a calibrated orifice (138), wherein - the calibrated orifice is produced by rolling the sleeve, or - the calibrated orifice is produced by a calibration plate inserted and crimped in the sleeve, the calibrated orifice (138) being formed by a calibrated hole opening on both sides of the calibration plate, in its center; and wherein the upper face (132) or the lower face (134) is in contact with the calibration spring (120) for the adjustment thereof.