EP3204631A1

EP3204631A1 - Fuel injector

Info

Publication number: EP3204631A1
Application number: EP15775186.8A
Authority: EP
Inventors: Ludovic Sauvetre
Original assignee: Delphi International Operations Luxembourg SARL
Current assignee: Delphi International Operations Luxembourg SARL
Priority date: 2014-10-08
Filing date: 2015-10-02
Publication date: 2017-08-16
Also published as: JP6806674B2; FR3027068A1; JP2017534794A; WO2016055385A1; FR3027068B1

Abstract

The invention relates to an injector comprising an actuator, a valve (26) and a nozzle. The actuator body (22), the valve body (50) and the nozzle body are rigidly interconnected in a coaxial stack by means of an injector nut. The injector also comprises a device (92) for coaxially positioning the actuator body (22) and the valve body (50). The positioning device (92) comprises a radial positioning means (94) which prevents the actuator body (22) and the valve body (50) from moving out of alignment, and an angular positioning means (96) which prevents the same two bodies (20, 50) from rotating relative to one another, the two positioning means (94, 96) being separate from and independent of one another.

Description

FUEL INJECTOR TECHNICAL FIELD

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

BACKGROUND OF THE INVENTION

A fuel injector conventionally comprises a sliding mobile needle 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 a frame-rod assembly attracted by the magnetic field of a coil or pushed by a valve spring. The needle and the armature-rod assembly are slidably movable in the injector body, itself consisting of a plurality of elements including an actuator body, a valve body, 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 between them the valve body.

To align the body elements to be held coaxial it is known to use between two adjacent elements, two cylindrical pins partially inserted into complementary blind holes provided in each of the body elements. So two pins eccentric and almost

diametrically opposite align the injector body and the valve body and likewise two other pins align the valve body and the nozzle body.

This pin alignment is dependent on manufacturing tolerances and fact is not perfect and it results from these tolerances a small misalignment that are no longer acceptable given the increasing quality and pressure increasingly high demand injectors.

SUMMARY OF THE INVENTION

The present invention proposes to solve at least partially problems by proposing a fuel injector extending along a longitudinal axis and comprising an actuator, a valve and a nozzle. The actuator comprises a body extending from a head to a lower face and is provided with a bore opening into said lower face, the coil of an electromagnet being fixed in the bore;

the valve comprises a body extending along the longitudinal axis from an upper face to a lower face and is provided with a housing forming a large low pressure chamber of the center of the bottom of which extends axially a hydraulic distributor bore . The valve further comprises a rod-armature moving assembly, the thick disk-shaped magnetic armature moving in the low-pressure chamber and the cylindrical rod sliding in the dispensing bore; the nozzle comprises a stepped spindle body extending from an upper face to a closed end forming an injection nozzle. The nozzle further comprises a needle arranged axially sliding in the body.

The body of the actuator, the valve body and the nozzle body are secured in a stack coaxial along the longitudinal axis by an injector nut bearing on an outer shoulder of the nozzle body, wrapping the valve and screwing on the actuator body, the injector further comprising a coaxial positioning device of the actuator body and the valve body.

The positioning device further comprises a positioning means preventing the actuator body and the valve body from being offset radially and, an angular positioning means preventing the same two bodies from rotating relative to one another, the two positioning means being distinct and independent.

The radial positioning means comprises a cylindrical ring of revolution mounted partly in a positioning bore provided in the valve body and partly in a complementary positioning bore provided in the actuator body.

In addition, the positioning bore provided in the valve body is a countersink forming the periphery of the low pressure chamber and the positioning bore provided in the body of the actuator forms the periphery of the bore opening into the chamber. lower face of said actuator body.

The positioning bore formed in the valve body is connected with the low pressure chamber in a circular shoulder against which is support the cylindrical ring.

In addition, the cylindrical ring forms a restriction of the bore opening into the underside of the actuator body.

The coil is arranged in the bore of the actuator body bearing against the circular wafer of the ring so that the coil is driven into said bore and the low pressure chamber extends into the actuator body, the armature magnetic moving inside the actuator body.

More specifically, the outer face of the coil is provided with a diameter restriction forming a collar and a connecting shoulder, said collar being engaged inside the cylindrical ring so that the coil is flush with the lower face of the body actuator, the magnetic armature moving inside the valve body.

The cylindrical ring can be made of a non-magnetic material.

Furthermore, the angular positioning means comprises a male member extending in part in a housing provided in the actuator body and opening into the lower face of said actuator body at a location peripheral to the bore in which is arranged the coil and, for other part in a housing formed in the valve body and opening into the upper face of said valve body at a location peripheral to the low pressure chamber.

In particular, the male member is a pin and the two housings are two aligned bores, the pin being inserted partly into one and partly into the other.

DESCRIPTION OF THE FIGURES

One embodiment of the invention is now described by means of the following figures:

Figure 1 is an axial sectional view of an injector provided with alignment means according to the invention.

FIG. 2 is a magnified detail in axial section of the region of the injector comprising said means produced according to a first embodiment.

FIG. 3 is a magnified detail in axial section of the region of the injector comprising said means produced according to a second embodiment. DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is an axial section of a fuel injector 10 which extends along a longitudinal axis Al from an injector head 12, drawn at the top of the figure, to an injection nozzle 14, drawn in FIG. bottom of the figure.

For the sake of clarity of the description, the arbitrary orientation of FIG. 1 will also be used, terms such as "up, down, above, below, above or below" may be used without this being limit neither the description nor the scope of the invention.

The injector 10 comprises the head 12 in which are arranged a high pressure inlet mouth 16 and partially visible only, a low pressure outlet mouth 18. The injector head 12 is integral with an actuator 20 having an actuator body 22, itself secured by an injector nut 24 to a control valve 26 and to the body 28 of the injection nozzle 14.

The actuator body 22 is generally cylindrical with a revolution of longitudinal axis A1 and extends from the head 12 to a lower face 30. It is further provided, on its outer cylindrical face, in the vicinity of said lower face. 30, a male thread 32 provided for further engagement by screwing the female thread 34 of the injector nut 24. It is further provided with a cylindrical inner bore 36 extending along a second axis A2, parallel to the longitudinal axis Al but slightly offset from it. The bore 36 opens into the lower face 30 and, in the bore 36 is arranged fixed the coil 38 of an electromagnet 40. From the coil 38 depart in the direction of the injector head 12 of the electrical connection means 42, such cables that extend in a specific conduit to a connector 44 provided with terminals for connecting the coil 38 to an external control unit not shown. The coil 38 is itself provided with a central bore 46 in which a valve spring 48 is arranged.

The control valve 26 comprises a cylindrical valve body 50 of longitudinal axis revolution Al extending between an upper face 52 and a lower face 54 and provided with an axial bore 56 comprising two coaxial sections along the second axis A2. The first section, opening into said upper face 52, is a wide and shallow countersink forming a low pressure chamber 58, the center of the bottom 60 of which extends towards the lower face 54 the second section forming a hydraulic distributor bore 62. In this boring bore 62, axially blind, several arrivals of channels open laterally.

Moreover, the injector represented in FIG. 1 and on which this description is based is only a non-limiting example and, many alternatives of constructions exist and will be mentioned however, the alternatives that would be omitted can not be for excluded from the scope of the claims. For example, it has just been specified that the longitudinal axis A1 and the second axis A2 are distinct and parallel. This offset, introduced in patent EP1693563, has many advantages but is not imperative and injectors in which the two axes are confused exist and can easily benefit from the teachings of the present invention.

The control valve 26 further comprises a rod-armature assembly 64 arranged movably in the axial bore 54. The assembly comprises a magnetic armature 66 and a valve stem 68, the armature 66 having the general shape of a disk thick which is placed in the low pressure chamber 58 and the valve stem 68 is a cylindrical shaft comprising sections of different diameters. One end of the rod 68 is encased and crimped in the center of the armature 66 and thus secured, the valve stem 68 extends perpendicular to the armature 66 and coalesces into a fair-slip fit in the bore distributor 62. The valve stem 68 is slidable directly into the dispensing bore 62 as shown in FIG. 2 or, alternatively, not shown in a cylindrical sleeve radially pierced with a plurality of radial holes, the sleeve being inserted in the dispensing bore 62.

As shown, the coil 38, its central bore 46, the valve spring

48, the axial bore 56 of the valve body, the magnetic armature 66 and the valve stem 68 are coaxial extending along the second axis A2. The valve spring 48, compressed between the bottom of the central bore 46 of the coil and the valve stem 68 whose head is flush with the center of the armature 66, continuously urges the armature-rod assembly 64 to a position away from the coil 38.

The injection nozzle 14 comprises the nozzle body 28, a needle 70 and a needle spring 72.

The nozzle body 28 is cylindrical with a longitudinal axis A1 and is in a spindle with a plurality of stages extending downwardly from an upper face 76 into a first wide section 78 and a narrower second section 80 closing at a point at its lower end, where a plurality of injection holes are made to allow the fuel to be pressurized. The outer faces of the two sections 78, 80 are connected in a transverse disc face 82 against which the injector nut 24 bears.

As shown in FIG. 1, the upper face 76 of the nozzle body is in sealed surface contact against the lower face 54 of the valve body and likewise the upper face 52 of the valve body is in surface sealing contact against the face lower 30 of the actuator body. The integral and impermeable stack is made possible thanks to the injector nut 24 which, threaded around the second narrow section 80 of the nozzle body bears against the disc face 82 of the same nozzle body and extends axially according to the invention. longitudinal axis A1 so as to enclose the control valve 26 and screw on the actuator body 22 through the complementary threads 32, 34, previously described. The surface seals are ensured on the one hand by the mirror quality of the state of the surfaces in contact and on the other hand by the sufficiently large tightening torque of the nut 24 which generates a strong compression between the lower part of the body. actuator, the valve body and the nozzle body.

The needle 70 of the exemplary injector is guided in the nozzle body between a top guide and a bottom guide integrated into the nozzle body. Alternatively, there are injectors whose top guide is a part independent of the nozzle body and, in the compressed stack of these injectors, the top guide is interposed between the valve and the nozzle body.

In order to be aligned coaxially along the longitudinal axis

Al the actuator body 22 and the valve body 50, and this, prior to tightening the nut 24 which may misalign the parts, the injector 10 is provided with a positioning device 92 comprising a positioning means radial 94 preventing the misalignment of the two bodies 22, 50, and an angular positioning means 96 preventing the rotation of one body relative to the other.

A first embodiment of the positioning device 92 is now described with reference to FIG.

The radial positioning means 94 comprises a cylindrical ring 98 having an inner diameter greater than the outer diameter of the magnetic armature 66 and an outer diameter equal to the diameter of the bore 36 of the actuator body.

As can be seen in the figure, the perimeter of the low pressure chamber 58 is provided with a counterbore 100 whose outside diameter is equal to the diameter of the bore 36 of the actuator body and also to the outside diameter of the ring. 98, the countersink 100 extending along the second axis A2 to a shoulder 102 against which the cylindrical ring 98 is supported. The ring 98 has a height greater than the depth of the counterbore 100, the depth at which the shoulder 102 lies relative to the upper face 52 of the valve body, and thus arranged the ring 98 protrudes from the upper face 52 of the body of the valve. valve forming a cylinder having axis of revolution the second axis A2.

Furthermore, the lateral outer face of the coil 38 is provided at its low end close to the valve, with a small diameter section forming a collar 104 with a diameter slightly smaller than the inside diameter of the ring 100 and a smaller diameter. longer than the emerging portion of the ring 98, said collar 104 connecting to the side face of the body of the coil 38 by another shoulder.

The ring 98 thus set up aligns with its outer cylindrical face and along the second axis A2 the countersink 100 of the valve body 50 and the bore 36 of the actuator body. The magnetic armature 66 moves in the low pressure chamber 58 in the center of the ring 98 and the collar 104 of the coil is engaged in the ring 98 so that the underside of the coil is flush with the lower face 30 of the body actuator.

The ring 98 and therefore any displacement by radial displacement of the actuator body 22 and the valve body 50. By cons it does not prevent their relative rotation along the second axis A2 and to do this, it is provided with the positioning means angular 96 which comprises a pin 106 inserted into a bore 108 provided in the injector body 22 and press fit into a complementary bore 110 provided in the valve body 50. It is also eccentric outside the valve body 50. ring 98, periphery of the actuator body 22 and valve 50. Thus placed, the two bodies 22, 50, being already radially held by the ring 98 are further prevented by the pin 106 eccentric of turn relative to each other.

A second embodiment is now described by way of differences with the previous mode and with reference to FIG.

The main difference is related to the radial positioning means 94 and resides in that the coil 38 has no collar 104. The ring 98 thus fits into the bore 36 of the actuator body and restricts its diameter. so that the coil 38 is seated in said bore 36 and bears against the top of the ring 98. The coil 38 is therefore not flush with the underside 30 of the actuator body.

As can be seen in FIG. 3, the low pressure chamber 58 occupies a space extending partly into the valve body 50 and partly into said bore 36 of the actuator body.

The coil 38 being moved back inside the bore 36, the valve stem 68 is elongate with respect to the rod of the first embodiment so that the magnetic armature 66 is always as close as possible to the coil 68, in the portion of the low pressure chamber 58 which extends into the injector body.

Whatever the embodiment, the cylindrical ring 98 may be made of a non-magnetic metal in order to help maximize the magnetic forces of the coil on the frame.

The coaxial positioning of the actuator body and the valve body produced by the cooperation of the separate and complementary radial and angular positioning means can also be used to perfectly align the valve body and the nozzle body, or even in the alternative mentioned, the valve body and the top guide.

The injector 10 is further provided with internal channels and ducts comprising complementary sections between the elements of the injector, these channels and ducts form a high pressure circuit 112 and a low pressure return circuit 114 in which, in use of the fuel circulates.

The general operation of the injector 10 and the different displacements of the moving parts is now briefly described.

At first the coil 38, is not electrically powered, it does not create a magnetic field and therefore does not attract the magnetic armature 66. The valve spring 48 pushes the armature-rod assembly 64 in a position in which the valve stem 68 closes the hydraulic communication between the axial bore 56 and the low pressure chamber 58 and thus prevents the fuel from joining the return circuit 114. The high-pressure fuel entering permanently into the injector, no evacuation possible, the pressure increases in the control chamber 90 and pushes the needle 70 down, in a position prohibiting any injection of fuel.

In a second step, the coil 38 is electrically powered, it then generates a magnetic field which attracts the armature 66 which, despite the solicitation of the valve spring 48, rises and approaches the coil 38 in a position opening the communication of fluid between the control chamber and the low pressure chamber. The fuel previously trapped in the control chamber 90 can thus be evacuated to the low pressure chamber 58 and the return circuit 114. This rapid evacuation creates a depression in the control chamber 90 which draws the needle 70 towards the high in a position for fuel injection.

The following references were used in the description.

10 fuel injector

12 injector head

14 injection nozzle

16 high pressure inlet mouth

18 low pressure outlet

20 actuator

22 actuator body

24 injector nut

26 control valve

28 nozzle body

30 underside of the actuator body

32 male thread of the actuator body

34 female thread of the injector nut

36 bore actuator body

38 reel

40 electromagnet 42 electrical connection means

44 connector

46 central bore of the spool

48 valve spring

50 valve bodies

52 upper side of the valve body

54 underside of the valve body

56 axial bore in the valve body

58 low pressure room

60 bottom of the low pressure chamber

62 bore hydraulic distributor

64 armature-rod assembly

66 magnetic armature

68 valve stem

70 injector needle

72 needle spring

76 upper side of the nozzle body

78 first wide stretch

80 second narrow section

82 transverse disc face of the nozzle body

90 control room

92 positioning device

94 radial positioning means

96 angular positioning means

98 cylindrical ring

100 countersink around the low pressure chamber

102 shoulder at the bottom of the counterbore

104 collar

106 pin

108 bore in the actuator body

110 bore in the valve body

112 high pressure circuit

114 low pressure return circuit longitudinal axis second axis

Claims

A fuel injector (10) extending along a longitudinal axis (A1) and comprising an actuator (20), a valve (26) and a nozzle (14),

Actuator (20) comprising a body (22) extending from a head (12) to a lower face (30) and being provided with a bore (36) opening into said lower face (30), the coil (38) an electromagnet (40) being fixed in the bore (36);

the valve (26) comprising a body (50) extending along the longitudinal axis (A1) from an upper face (52) to a lower face (54) and being provided with a housing forming a wide low chamber pressure (58) of the center of the bottom (60) of which extends axially a hydraulic distributor bore (62), the valve (26) further comprising a rod-armature moving assembly (64), the magnetic armature (66) a thick disc shape moving in the low pressure chamber (58) and the cylindrical rod (68) sliding in the dispensing bore (62); the nozzle (14) comprising a stepped spindle body (28) extending from an upper face (76) to a closed end forming an injection nozzle, the nozzle further comprising an axially arranged needle (70) (Al slidable in the body (28);

the body of the actuator (22), the valve body (50) and the nozzle body (28) being secured in a stack coaxial along the longitudinal axis (Al) by an injector nut (24) bearing on an outer shoulder of the nozzle body, wrapping the valve (26) and screwing on the actuator body (22), the injector (10) further comprising a coaxial positioning device (92) actuator (22) and the valve body (50), characterized in that

the positioning device (92) comprises a means of

radial positioning (94) preventing the actuator body (22) and the valve body (50) from being misaligned and an angular positioning means (96) preventing the same two bodies (20, 50) from rotating one relative to the other, the two positioning means (94, 96) being separate and independent.

2. Injector (10) according to the preceding claim wherein the radial positioning means (94) comprises a cylindrical ring (98) of revolution partially mounted in a positioning bore (100) provided in the valve body and partly in a complementary positioning bore (36) provided in the actuator body.

Injector (10) according to claim 2 wherein the positioning bore (100) provided in the valve body is a countersink (100) forming the periphery of the low pressure chamber (58) and, the positioning bore (36) provided in the body of the actuator forms the periphery of the bore (36) opening into the lower face (30) of said actuator body.

4. Injector (10) according to claim 3 wherein the positioning bore (100) formed in the valve body is connected with the low pressure chamber (58) according to a shoulder (102) circular against which bears the ring cylindrical (98).

5. Injector (10) according to claim 4 wherein the cylindrical ring (98) forms a restriction of the bore (36) opening into the underside (30) of the actuator body.

Injector (10) according to claim 5 wherein the coil (38) is arranged in the bore (36) of the actuator body bearing against the circular edge of the ring (98) so that the coil (38) ) is pressed into said bore (36) and the low pressure chamber (58) extends into the actuator body (22), the magnetic armature (66) moving within the actuator body (22). ).

Injector (10) according to claim 5 wherein the outer face of the coil (38) is provided with a collar-like diameter restriction (104) and a connecting shoulder, said collar (104) being engaged to the inside the cylindrical ring (98) so that the coil (38) is flush with the underside (30) of the actuator body, the magnetic armature (66) moving within the valve body (50) .

8. Injector (10) according to any one of claims 2 to 7 wherein the cylindrical ring (98) is made of a non-magnetic material.

An injector (10) according to any one of the preceding claims wherein the angular positioning means (96) comprises a male member (106) extending into a housing (108) provided in the actuator body and opening in the lower face (30) of said actuator body at a location peripheral to the bore (36) in which the coil (38) is arranged and, in other part in a housing (110) formed in the valve body (50) and opening into the upper face (52) of said valve body (50) at a location peripheral to the low pressure chamber (58).

Injector (10) according to claim 9 wherein the male member is a pin (106) and the two housings (108, 110) are two aligned bores, the pin (106) being inserted partly into the one and partly in the other.