FR3053409A1 - FUEL INJECTOR - Google Patents

Abstract

A fuel injector (10) extending along a longitudinal axis (X) comprising: a nozzle assembly (12) comprising a movable needle (14) disposed in a nozzle body (16); an actuator assembly (22) comprising an actuator (23) arranged in an actuator body (24) which is provided with an external male thread (32); a control valve assembly (18) comprising a valve member (19) arranged in a valve body (20) between the nozzle body (20) and the actuator body (24); a piston guide (27) arranged between the nozzle assembly (12) and the valve assembly (18); a nut (28) having three different diameters and provided with an internal female thread (30). The nut (28) integrally holds the nozzle assembly (12), the valve assembly (19) and the actuator assembly (22) against a shoulder (34) of the nozzle body and screwing on the actuator body (24).

Description

Holder (s): DELPHI INTERNATIONAL OPERATIONS LUXEMBOURG S.A R.L. Limited liability company.

Extension request (s)

Agent (s): DELPHI FRANCE SAS Simplified joint-stock company.

(04) FUEL INJECTOR.

FR 3 053 409 - A1 (57) fuel injector (10) extending along a longitudinal axis (X) comprising:

a nozzle assembly (12) comprising a movable needle (14) arranged in a nozzle body (16);

- an actuator assembly (22) comprising an actuator (23) arranged in an actuator body (24) which is provided with an external male thread (32);

a control valve assembly (18) comprising a valve member (19) arranged in a valve body (20) included between the nozzle body (20) and the actuator body (24);

a piston guide (27) arranged between the nozzle assembly (12) and the valve assembly (18);

a nut (28) having three different diameters and provided with an internal female thread (30). The nut (28) securely holds the nozzle assembly (12), the valve assembly (19) and the actuator assembly (22) by resting on a shoulder (34) of the nozzle body and screwing on the actuator body (24).

DP-322895

FUEL INJECTOR

TECHNICAL AREA

The invention relates to a fuel injector provided with a device for aligning the components of the injector.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

A fuel injector conventionally comprises a movable needle sliding under the influence of a pressure differential between a control chamber and the nozzle of the injector. In the control chamber, the pressure varies under the influence of the displacement of a solenoid valve comprising an armature-rod assembly attracted by the magnetic field of a coil or else repelled by a valve spring. The needle and the armature-rod assembly are movable sliding in the body of the injector, itself comprising several elements including an actuator body, a valve body, a high guide and a nozzle body. These elements of the injector body are secured to each other by an injector nut which bears on a shoulder of the nozzle body is screwed to the actuator body by compressing the valve body therebetween. To align the elements of the body which must be kept coaxial, it is common to use between two neighboring elements, two cylindrical pins partially inserted in complementary blind holes provided in each of the elements of the body. Thus two eccentric and almost diametrically opposite pins align the top guide, the valve body or the nozzle body. Likewise, two other pins align the valve body and the actuator body. This alignment by pins is dependent on manufacturing tolerances and in fact is not perfect and the result of these tolerances is a small misalignment which is no longer acceptable given the increasing quality, the required performance and the increasing pressures. high demands on injectors.

The object of the present invention is to provide a solution which overcomes these drawbacks.

SUMMARY OF THE INVENTION

The present invention proposes to solve these problems with the aid of a nut which ensures coaxiality of the components of the injector. The internal combustion engine fuel injector extends along a longitudinal axis. The injector includes a nozzle assembly comprising a movable needle arranged in a nozzle body, an actuator assembly comprising an actuator arranged in an actuator body defining an outer wall. The outer wall of the actuator body is provided with an external male thread. In addition, the injector includes a control valve assembly comprising a valve member arranged in a valve body. The valve body is arranged between the nozzle body and the actuator body. In addition, the injector may also include a high guide arranged between the nozzle assembly and the valve assembly. The injector also includes a nut having at least three different diameters and provided with an internal female thread. The nut securely holds the nozzle assembly, the valve assembly and the actuator assembly by resting on a shoulder of the nozzle body and screwing onto the actuator body. The valve body is thus compressed between the nozzle body and the actuator body.

In a first embodiment, the nut is formed in one piece and comprises a longitudinal tubular part extending along the longitudinal axis from a first end to a second end. In addition, the nut comprises a transverse annular member extending radially inwards from the second end provided with a central opening, and an annular groove around the longitudinal axis arranged in the tubular part opposite the body. actuator.

In a second embodiment the nut comprises a first longitudinal tubular positioning piece extending along the longitudinal axis from a first end to a second end and having at least the three different diameters and a second tubular piece longitudinal tightening including internal female thread. The first part is fixed to the nozzle body, valve body and to the actuator body by means of a stop joint included between a first positioning groove of the first positioning part and a second positioning groove of the second clamping piece. The first positioning piece is inserted into the second clamping piece. In addition, the nut has the first internal diameter complementary to the external diameter of a first stage of the nozzle body and the third internal diameter complementary to the external diameter of the actuator body. The nut also has the second internal diameter complementary to the external diameter of a valve body and the third internal diameter complementary to the external diameter of the actuator body.

In addition, the nut can be provided with an internal female thread arranged proximal to the first end, which is screwed onto the external male thread of the actuator body. In a third embodiment, the valve assembly and the nozzle assembly are angularly oriented relative to each other. The angular orientation is moreover ensured by a positioning of a key arranged in a longitudinal groove defined by at least three portions arranged in external walls of the high guide and of the valve and actuator bodies. In addition, the nut comprises at least one longitudinal groove arranged on an internal wall of the nut to allow fuel leaks to pass at the interfaces of the components of the injector.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics, objects and advantages of the invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of non-limiting example and in which:

Figure 1 is an axial section of the injector according to the invention.

Figure 2 is an enlarged section of the invention according to a first embodiment.

Figure 3 is an enlarged section of the invention according to a second embodiment.

Figure 4 is an enlarged isometric section of the invention according to a third embodiment.

Figure 5 is a top view of the nut.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

To facilitate and clarify the following description, the orientation from top to bottom is chosen arbitrarily and, words and expressions such as above, below, above, below, top, bottom ... can be used without any intention of limit the invention.

According to Figure 1, is described the invention relating to a fuel injector 10 for internal combustion engine, here a diesel injector although the invention is fully transposable to a gasoline or other fuel injector. The description will detail the elements of the invention and will remain more succinct and general as to the surrounding elements.

According to Figure 1, the injector 10 extends along a longitudinal axis X and comprises a nozzle assembly 12 comprising a movable needle 14 arranged in a nozzle body 16 and a top guide 27, a valve assembly control 18 comprising a valve member 19 arranged in a valve body 20, an actuator assembly 22 comprising an actuator 23, for example a coil 23 arranged in an actuator body 24 defining an external wall 26 and a nut 28 provided with an internal female thread 30. The external wall 26 of the actuator body is provided with an external male thread 32. The nut 28 securely holds the top guide 27 and the nozzle bodies 16, valve body 20 and body actuator 24 by pressing on a transverse disc face 34 forming a shoulder 34 of the nozzle body and screwing onto the actuator body 24.

The nozzle body 16 is cylindrical extending along the longitudinal axis X. The nozzle body 16 is triangular in spindle shape extending downwards from a first upper face 36 into a wide first stage 38 , a second stage 40 narrower below the first stage 38, a third stage 42 below the second stage 40 and a fourth stage 44 closing in a point at its lower end 46 where a plurality of injection holes 48 are arranged allowing pressurized fuel to be sprayed out of injector 10.

External faces 50, 52 of the third and fourth stages 42, 44 are connected according to the shoulder 34 of the nozzle body against which the nut 28 bears.

The control valve body 20 is cylindrical in shape and it includes an upper face 56 of the valve body and a lower face 58 of the valve body and an outer wall 57. In addition, the valve body 20 comprises a high fuel channel pressure (not shown) and a control chamber 62 where an armature-rod assembly 64 is arranged.

According to FIG. 2, the actuator body 24 is cylindrical in shape and extending along the longitudinal axis X. The actuator body 24 is provided with the external wall 26 where the external male thread 32 is arranged. actuator body 24 has an outside diameter DE24. The external male thread 32 is located in a lower part 68 of the external face of the actuator body. The external male thread 32 is provided for complementary engagement by screwing the internal female thread 30 of the injector nut. The actuator body 24 is arranged above the valve body 20.

As shown in FIG. 2, the upper face 36 of the nozzle body is in sealed surface contact against the lower face 29 of the high guide 27, the upper face 31 of the high guide 27 is in sealed surface contact against the lower face 58 of the valve body, the upper face 56 of the valve body is in sealed surface contact against the lower face 70 of the actuator body. Other injector assemblies can also be produced without the high guide 27 with the nozzle body 16 in contact with the valve body 20. The integral and sealed stack of the actuator assembly 22, valve assembly 18 and nozzle assembly 12 is made possible by the injector nut 28. The nut 28 threaded around the narrow second stage 40 of the nozzle body bears against the shoulder 34 of the same nozzle body. The nut 28 extends axially along the longitudinal axis X so as to enclose the control valve body 20 and screw onto the actuator body 24 thanks to the complementary threads 30, 32 previously described. The surface seals are ensured on the one hand thanks to the mirror quality of the state of the surfaces in contact and on the other hand thanks to the sufficiently large tightening torque of the nut 28 which generates a strong compression between the bottom of the body d actuator 24, valve body 20 and nozzle body 16.

In a first embodiment of the invention and according to FIG. 2, the nut 28 is designed in one piece and of cylindrical shape with a longitudinal axis X.

Thus the nut 28 is formed in one piece. The nozzle 16, valve 20 and actuator 24 bodies are axisymmetric with respect to the longitudinal axis X. The nut 28 comprises a longitudinal tubular part 72 extending along the longitudinal axis X from a first end 74 to a second end

76, a transverse annular member 78 extending radially inwards from the second end 76 provided with a central opening 80, and an annular groove 82 around the longitudinal axis X arranged in the tubular part 72 facing the body actuator 24. The nut 28 comprises, starting from below and going upwards in FIG. 2, a first section 84 having a first internal diameter DI84 adjusting to an external diameter DE16 of the nozzle body 16, a second section 86 having a second internal diameter DI86 adjusting to an external diameter DE20 of the valve body 20, a third portion 88 having a third internal diameter DI88 adjusting to the external diameter DE24 of the actuator body 24. The nut 28 is provided with female thread 30 near the first end 74 of the tubular part 72 of the nut. Other alternatives are possible with at least three internal diameters. The nut 28 is screwed onto the external male thread 32 of the actuator body 24. The tolerance of the different diameters DI84, DI86, DI88 of the nut 28 is tight, for example of the order of plus or minus 10 micrometers. The annular groove 82 makes it possible to reduce hyperstatism and can be arranged either in an internal wall 90 of the tubular part 72 of the nut as shown in FIG. 2 but can also be in an external wall 92 of the tubular part 72 of the nut. The annular groove 82 around the longitudinal axis X is arranged in the third section 88 of the nut opposite the actuator body 24. The first section 84 of the nut is provided with a transverse annular shoulder 54 which s 'extends inwards and arranged in addition to the shoulder 34 of the nozzle body. The nut 28 is provided with the internal female thread 30 arranged proximal to the first end 74 which is screwed onto the external male thread 32 of the actuator body 24.

In a second embodiment of the invention and according to FIG. 3, the nut 28 is formed of a first positioning part 94 and of a second clamping part 96. The first positioning part 94 is of tubular shape longitudinal positioning extending along the longitudinal axis X from the first end 74 to the second end 76 and having the three different diameters DI84 / DI86 / DI88. The second part 96 is of longitudinal tubular clamping shape comprising the internal female thread 30. The nozzle bodies 16, of valve 20 and of actuator 24 are axisymmetric in this embodiment. The first positioning piece 94 is fixed to the nozzle body 16, valve body 20 and to the actuator body 24 by means of a stop joint 98 comprised between a first groove 100 for positioning the first positioning piece and a second groove 102 for positioning the second clamping part. The first positioning piece 94 is inserted into the second clamping piece 96. In addition, the nut 28 comprises a sealing element 104 such as a seal 104, for example an O-ring 104, arranged between a first annular groove 106 in an external wall 95 of the first part 94 and a second groove 108 annular in an internal wall 97 of the second part 96.

The two annular grooves 106, 108 are located above the stop joint 98 as shown in FIG. 2. The nut 28 is provided with the internal female thread 30 arranged proximal to the first end 74 screwing onto the male thread 32 external of the actuator body.

In a third embodiment of the invention and according to FIG. 4, the valve assembly 18, the actuator assembly 22 and the top guide 27 are asymmetrical with respect to the longitudinal axis X but any other asymmetry can be considered in this mode of invention. The valve 18 and actuator 22 assemblies as well as the top guide 27 are angularly oriented relative to one another. The angular orientation is ensured by the positioning of a key 110 arranged in a longitudinal groove 112. The groove 112 is defined by three portions 114, 116, 118 arranged in the external walls 60, 57, 26 of the top guide 27 and of the valve body 20 and of the actuator 22. There is asymmetry for example when the valve body 20 has a leakage return channel which eliminates the axisymmetry with respect to the longitudinal axis X. In this third embodiment, the nut 28 can either be produced in two pieces 94, 96 as described in the second embodiment. embodiment or the nut 28 can be made in one piece as described in the first embodiment. In addition, when the nut 28 is in one piece and when the components of the injector are asymmetrical or axisymmetric, the nut 28 comprises at least one longitudinal groove 128. According to FIG. 5, the nut comprises six longitudinal grooves 128 so as to allow the fuel leak to escape to the various components.

During the final assembly of the components of the injector 10, the alignment of the nozzle 16, valve 18 and actuator 22 assemblies is carried out using the key 110. According to FIG. 4, the groove 112 is arranged to receive the key 110. The three portions 114, 116, 118 must be aligned longitudinally so that the key 110 can be mounted longitudinally in the groove 112. The width L of the key 110 is less than the depth P of the groove 112 so that the key 110 cannot protrude from groove 112. Thus the nut 28 can be threaded onto the nozzle 16, valve 20 and actuator 24 bodies and the nut 28 can then be screwed onto the actuator body 24 .

In this part we will describe the operation of the injector 10. As described in Figure 1, the injector 10 is provided with a fuel circulation circuit (not shown) which makes it possible to supply high pressure fuel via a circuit high pressure from an inlet (not shown) arranged in an upper part of the injector 10 to the injection holes 48 arranged in a lower part of the injector 10. As described in FIG. 1, when the actuator 23 is electrically powered, it attracts an armature-rod assembly 64 fixed together, which opens the evacuation channel (not shown) and allows the fuel enclosed in a control chamber 62 to evacuate towards a low pressure circuit (not shown). Then the pressure decreases in the control chamber 62 and the needle 14 moves in a bore 122 of the nozzle body 16 towards an open position in which a lower end of the needle 14 moves away from a seat 118 of the body nozzle. Consequently, an upper end of the needle 14, according to FIG. 1, comes into contact with the lower face 58 of the valve body.

When the actuator assembly 22 is not supplied, the rod-armature assembly 64 is pushed back by a valve spring 124 to a position which prevents fuel from flowing to the exhaust channel which is closed, which retains high pressure fuel arriving there. Then the pressure in the control chamber 62 rises and the needle 14 is pushed down by a needle spring 126 and the lower end of the needle 14 is in contact with the nozzle seat 118 and the end upper of the needle 14 is remote from the lower face 58 of the valve body.

The following references have been used in the description:

injector nozzle assembly needle body control valve assembly valve member valve body valve assembly actuator actuator actuator body external wall high guide nut lower face of high guide female thread upper face of high guide male thread shoulder upper face of body nozzle first stage second stage third stage fourth stage lower end injection hole external face of the second section external face of the third section shoulder of the nut upper face of valve body external wall of valve body lower face of valve body wall outside of the upper guide control chamber rod-armature assembly lower part of the external face of the actuator body lower face of actuator body tubular part first end second end annular member central opening annular groove first section second section third section wall i internal of the tubular part external wall of the tubular part first part external wall of the first part second part internal wall of the second part stop joint first positioning groove second positioning groove sealing element first groove second groove keyway first groove portion on the top guide second groove portion on the valve body third groove portion of the actuator body bore of the nozzle body seat valve spring needle spring longitudinal groove of nut

Longitudinal axis first inside diameter of the nut second inside diameter of the nut third inside diameter of the nut outside diameter of the nozzle body outside diameter of the valve body outside diameter of the actuator body il

Claims (8)

1. Fuel injector (10) for internal combustion engine, injector (10) extending along a longitudinal axis (X) and comprising: a nozzle assembly (12) comprising a movable needle (14) arranged in a nozzle body (16); - an actuator assembly (22) comprising an actuator (23) arranged in an actuator body (24) defining an external wall (26), the external wall (26) of the actuator body (24) being provided with a external male thread (32); -a control valve assembly (18) comprising a valve member (19) arranged in a valve body (20); the valve body (20) being arranged between the nozzle body (20) and the actuator body (24); a high guide (27) arranged between the nozzle assembly (12) and the valve assembly (18) -a nut (28) having three different diameters DI84 / DI86 / DI88 and provided with an internal female thread (30), the nut (28) holding the nozzle assembly (12) together, the valve assembly ( 19) and the actuator assembly (22) by resting on a shoulder (34) of the nozzle body and by screwing onto the actuator body (24), the valve body (20) being compressed between the body nozzle (16) and the actuator body (24); 2. Injector (10) according to the preceding claim in which the nut (28) is formed in one piece and comprises a tubular longitudinal part (72) extending along the longitudinal axis (X) from a first end ( 74) to a second end (76), a transverse annular member (78) extending radially inward from the second end (78) provided with a central opening (80), and an annular groove (82 ) around the longitudinal axis (X) arranged in the tubular part (72) opposite the actuator body (24). 3. Injector (10) according to claim 1 wherein the nut (28) comprises a first piece (94) longitudinal tubular positioning extending along the longitudinal axis (X) from a first end (74) to a second end (76) and having at least the three different diameters DI84 / DI86 / DI88 and a second longitudinal tubular clamping part (96) comprising the internal female thread (30), the first part (94) fixed to the nozzle bodies (16), valve body (20) and to the actuator body (24) by means of a stop joint (98) comprised between a first groove (100) for positioning the first positioning part and a second groove (102) for positioning the second clamping piece, the first positioning piece (94) being inserted in the second clamping piece (96). 4. Injector (10) according to any one of claims 2 to 3 wherein the nut (28) has the first internal diameter (DI84) complementary to the external diameter (DE 16) of a first stage (38) of the nozzle body and the third internal diameter (DI88) complementary to the external diameter (DE24) of the actuator body. 5. Injector (10) according to any one of claims 2 to 4 in which the nut (28) has the second internal diameter (DI86) complementary to the external diameter (DE20) of a valve body and the third internal diameter (DI88) complementary to the outside diameter (DE24) of the actuator body. 6. Injector (10) according to any one of claims 2 to 5 in which the nut (28) is provided with the internal female thread (30) arranged proximal to the first end (74) screwing onto the external male thread ( 32) of the actuator body. 7. Injector (10) according to any one of the preceding claims in which the valve assembly (18), the nozzle assembly (12) and the actuator assembly (22) are angularly oriented relative to each other , the angular orientation being ensured by an installation of a key (110) arranged in a longitudinal groove (112) defined by three portions (114,116,118) arranged in external walls (60,57, 26) of the high guide ( 27) and valve bodies (20) and actuator (24). 8. Injector (10) according to claim 7 wherein the nut (28) comprises a longitudinal groove (128) arranged on an inner wall (90) of the nut (28). 1/4 | X 2/4 3/4 4/4 Z