MXPA96006148A - Combusti injector - Google Patents

Abstract

A fuel injector for use on an internal combustion engine including a tubular injector body defining an axial fuel conduit. Placed inside the injector body is an armature, a solenoid assembly which includes a reel-type coil with a continuous central hole and a coil of wound wire. A pole piece includes a tubular cylindrical pole having, at its terminal end, a work surface. The cylindrical pole is configured for axial positioning within the central continuous bore of the coil so that it is positioned within the working surface in the middle of the ends of the wire coil. An axially extending non-magnetic cylindrical tube has a first end received around the terminal end of the cylindrical pole and has a second end, positioned axially downwardly of the working surface of the pole and the central continuous hole of the coil inside the duct of axial fuel from the tubular injector body. The tubular member is configured to receive the armature and includes an annular bearing surface extending radially inward positioned in the middle of the first and second ends for a slidable support circumjacent said armature therein. The second end of the non-magnetic tubular member can cooperate with the tubular injector body to form a seal against the fuel inlet inside the wound wire coil of the solenoid actuator.

Description

FUEL DB INJECTOR TECHNICAL FIELD The invention relates to fuel injectors for delivering fuel to the fuel intake system of an internal combustion engine.

BACKGROUND OF THE INVENTION In electromagnetic fuel injectors for internal combustion engines it is preferable that the coil windings in the solenoid actuator are protected from excessive fuel exposure in order to ensure reliable operation. The chemical constituents in the fuel degrade the insulation and metal of the coils that can, over time, result in a degraded injector operation.

The use of elastomeric seals between the injector components and a fuel resistant coil material is attempted to prevent the passage of fuel to the coil windings. It is known to extend the upper pole piece to a place below that of the coil assembly where it can be used to establish a seal with the injector body. Such a design may be effective for sealing the coil assembly of the fuel supply, however, the efficiency of the magnetic circuit is not optimized due to the placement of the working air gap below the coil assembly. The non-optimal placement of the working air gap can result in an excess of magnetic flux leakage between the parallel injector body and pole piece surfaces that reduces the flow acting through the working air gap to move the armor SYNTHESIS OF THE INVENTION It is therefore an object of the present invention to provide a fuel injector, for use in an internal combustion engine, having an actuator assembly which seals the coil against fuel exposure while optimizing the location of the separation of working air in relation to the coil.

A feature of the invention is to provide a pole piece having its lower work surface positioned in the middle of the ends of the scroll coil. A non-magnetic tubular extension member is fixed to the lower pole piece, on one side of the work surface and extends the workpiece beyond the coil for sealing. A seal is established between the non-magnetic extension and the injector body, against the entry of the fuel inside the coil assembly.

A further feature of the invention may be to provide an annular region of reduced diameter in the middle of the ends of the tubular extension of a pole piece. The annular region can function as a bearing surface for an armature placed for a reciprocal movement relative to the working surface of the pole piece.

An embodiment of the present invention is described below, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view of a fuel injector involving features of the present invention; Figure 2 is a cross section of the fuel injector of Figure 1, taken along line 2-2 of Figure 1; Figure 3 is an enlarged view of a part of Figure 2; Figure 4 is an enlarged view of a part of Figure 2, with parts removed for descriptive purposes; Figure 5A is a sectional view of a non-magnetic cylindrical tube guide tube involving features of the present invention; Figure 5B is an enlarged view of a portion of the cylindrical tube guide of Figure 5A; Figure 6A is a sectional view of a second embodiment of a non-magnetic cylindrical tube guide tube involving features of the present invention; Y Figure 6B is an enlarged view of a portion of the cylindrical tube guide of Figure 6A.

DESCRIPTION OF THE PREFERRED MODALITY Referring to Figures 1 and 2, an electromagnetic fuel injector, designated generally with the numeral 10, includes as its main components a body 12, a nozzle assembly 14, a valve member 16 and a used solenoid driver assembly 18. to control the movement of the valve member 16.

In the illustrated construction, the body 12 is of a hollow cylindrical tubular configuration and is of an external shape such as to allow the direct insertion, if desired, of the injector 10 into a socket provided for this purpose in a manifold socket. motor not shown.

The body 12, figure 3, includes an enlarged upper solenoid cover part 20 and a lower end nozzle cover part 22 of reduced internal and external diameter relative to the solenoid portion 20. An internal cylindrical cavity is formed in the body 12 by a stepped orifice therethrough which is virtually coaxial with the axis 26 of the body. In the construction shown, the cavity 24 includes a cylindrical top wall 28, a cylindrical intermediate wall 30 and a cylindrical bottom wall 32. The wall 30 is of reduced diameter relative to the upper and lower wall portions 28 and 32 respectively.

The solenoid assembly 18 is positioned within the enlarged upper solenoid cover part 20 and includes the spool type tubular coil 34 holding a coiled wire solenoid coil 36. The solenoid assembly 18 is positioned within the upper cover 20 on one side of the shoulder 38 extending between the cylindrical upper wall 28 and the intermediate wall 30. A resilient sealing member such as an O-ring 40 is positioned between a cylindrical extension oriented downward (as seen in FIG. FIGS. 42 are located around the inner diameter of the tubular coil 34 and the seal shoulder 44 on the cylindrical intermediate wall 30. The coil 34 is provided with a central continuous opening 46 configured to surround the lower reduced diameter portion 48 of the pole piece 50. A pair of terminal wires 52, FIG. 1, are operatively connected at one end (not shown) to the solenoid coil 36 and each of such cables has its second end extending upwards through an outer molded cover 54, described in further detail below, to terminate in a terminal socket 56, for the connection of the fuel injector to a suitable source of electrical power in a very well known in art.

The pole piece 50 includes an upper cylindrical portion 58, a centrally located circular radial flange portion 60 and the lower reduced diameter cylindrical pole 48. The circular radial flange portion 60 is slidably received at its outer peripheral edge within the wall cylindrical top 28 of the body 12 to thereby close the enlarged upper solenoid cover part 20 of the body 12 and retain the solenoid assembly 18 there. The pole piece 50 is retained axially within the upper cylindrical part of the body 12 as by having its flange portion welded or otherwise properly joined to the shoulder 62 along the upper open wall end 28.

The lower cylindrical pole 48 is integrally formed with the pole piece 50 and extends downward from the flange portion 60. The lower pole 48 is of an outer diameter suitable to be slidably received in the central continuous hole 46 extending continuously through the scroll coil 34 and of a suitable axial length to extend the work surface 66 to an optimum location between the ends of the central continuous bore hole 46. The location of the work surface 66 of the pole piece 48 centrally of the axial spool length is important to maximize the magnetic efficiency. A cylindrical tube 64 received around the lower end of the lower cylindrical pole 48 of the pole piece 50 of non-magnetic material such as stamped or stamped stainless steel or other suitable material, figures 3 and 4. The tube can be welded, joined or otherwise sealed to the lower pole piece 48 as to prevent penetration of the fuel to the joint between the tube 64 and the pole. The tube 64 extends axially downwardly beyond the lower end, or the work surface 66 of the lower cylindrical pole 48 to a location virtually down the pole. At its terminal end, the outer surface 68 of the non-magnetic tube 64 interconnects with the elastic sealing member 40, sealed between the lower end of the coil extension 42 and the seal shoulder 44 of the body 12, thereby establishing a seal between the central fuel conduit 70 extending to the length of the fuel injector 10 and the solenoid assembly 18. The cylindrical non-magnetic tube 64 operates to extend the pole piece 48 down the spool 36 to establish an efficient seal with the body of the injector 12 while providing an efficient magnetic circuit designed by allowing the work surface 66 to be located optimally within the continuous bore hole 46. The pole piece 50 combines with the non-magnetic cylindrical tube 64 and the injector body. 12 to define the dry coil design that effectively isolates coil windings 36 from exposure to fuel. In the case of fuel run-off past the seal member 40, fuel is prevented from escaping from the injector body, such as by a soldered seal 63 in the interface of the pole piece flange 60 and the shoulder 62 of the top cover part of injector body 20.

The pole piece 50, in the illustrated construction, is also provided with an upwardly extending cylindrical protrusion 58. The protrusion 58 is configured to receive a deep drawn axially extending fuel inlet tube 74. The tube inlet has a first inlet end 76 having a flanged end portion 78 extending from the upper end thereof. The deep drawn fuel inlet pipe is preferably formed using a sheet supply resulting in a final product having a nominal wall thickness. The fuel inlet pipe 74 is fixed to the pole piece 50 and is overmoulded to define the upper case 54, using a suitable encapsulating material which, as described above, also includes an integral terminal socket 56 with wires 52. The encapsulant allows the inner diameter of the fuel inlet tube to be tightly controlled while the outer diameter of the upper case part of the injector 10 is controlled during molding of the encapsulant. A top seal shoulder 86 formed in the overshoot box 54 is axially spaced from the tube flange 78 to define an annular seal groove 88 configured to carry an elastic seal member such as the O-ring 90 for free clamping. runoff to a pressurized fuel source, not shown.

Within the fuel inlet pipe 74, the dimples extending radially inwardly 92 are positioned to make contact with the flanged part 94 of the injector fuel filter assembly 96. The dimples 92 inhibit an undesirable downward translation of the assembly. of felt 96 in the fuel inlet pipe 74.

The nozzle assembly 14 includes a nozzle body 98 having a cup-shaped tubular configuration with a stepped upper shoulder 100 for receiving a sealing member such as an O-ring 102. The sealing member 102 is positioned between the shoulder 100 on the outer surface of the nozzle body 98 and, the shoulder 106 which extends between the intermediate wall 30 and the lower wall 32 of the lower end nozzle cover part 22 of the body 12, thereby establishing a seal against of the run-off at the interface of the nozzle assembly 14 and the body 12. The nozzle body 98 includes a series of external threads 108 which engage corresponding internal threads 110 in the bottom wall 32 of the body 12 providing axial adjustability of the body nozzle inside the injector body. An internal cylindrical cavity 112 in the nozzle body 98 is defined by an internal cylindrical wall 114 which extends from the open upper end of the nozzle body to terminate in an annular frustoconical valve seat 116 positioned around a discharge opening of the nozzle body. axially aligned fuel 118 at the lower end thereof. The cylindrical cavity 112 operates as a fuel supply reservoir within the nozzle assembly 12.

On the exterior of the lower end 120 of the nozzle body 98 is located a fuel spray guide plate 122. The driver plate 122 is formed of a thin sheet supply and includes the fuel directing openings 124 extending from the side upstream 126 to the downstream side 128. The fuel that passes through the fuel discharge opening 118 in the valve seat 116 is delivered to the upstream side, or to the face 126 of the director plate 122 where it is provided. distributes through the face to the face openings 124. The openings 124 are oriented in a predetermined configuration that will generate, in the discharged fuel, a desired spray pattern.

A cylindrical retention sleeve 130 is also engaged on the lower end of the nozzle body 98. The retainer includes an upper annular shoulder 132 which defines, with the shoulder 134 of the body 12, an annular groove 136 for the positioning of the elastic sealing member 138. The lower downward end 140 of the retaining sleeve 130 extends beyond the downstream side 128 of the director plate 122 and functions to protect the guide plate 122 from contact with the surfaces that could damage the plate by altering the precise alignment of the orifices directing the fuel 124. The cylindrical holding sleeve 130 is preferably constructed of a durable and temperature resistant plastic. as nylon and is pressurized on the lower end nozzle cover part 22 of the body 12 where a small annular rim 142 on the cylindrical wall of the cylindrical retainer sleeve 130 makes contact with a corresponding groove 141 on the outer wall of the nozzle cover part 22 for fixing the retainer sleeve against the axial movement of the nyector 10 Referring now to the valve member 16, this includes a tubular armature 146 and a valve member 148, the latter made of, for example, a spherical ball having a predetermined radius, which is welded to the lower annular end 150 of the armature tubular 146. The radius of the valve member 148 is chosen for a seating contact with the valve seat 116. The tubular frame 146 is formed with a predetermined outside diameter such as to slide loosely into the non-magnetic cylindrical tube 64 received around it. and extending from the lower pole piece 48. The tube 64 includes an inner cylindrical wall 154 which extends coaxially with the axis 26 of the injector 10 along which the valve member 16 is aligned for a reciprocal movement. An armature bearing 156 which extends radially inwardly to contact the outer surface of the tubular armature 146 in a supporting relationship circumjacent therewith is located between the ends of the tube 64. Figures 5A, 5B and 6A, 6B illustrate two embodiments of the tube 64 and an armature bearing 156. The bearing can be defined by a region of increased thickness 158 in the tube 64 ', as illustrated in Figures 6A and 6B, or by a mechanically reduced diameter part 160, as illustrated in Figures 5A, 5B. In any configuration, the armature tube bearing 156, 156 'is formed as a radius WRM so that the axially intermediate part of the bearing 156 has the smallest internal diameter. The bearing surface with radius prevents the tubular armature 146 from resting on or moving through a bearing edge which would most likely cause premature wear and binding of the valve member 16 while accommodating some misalignment between the tubular extension 64 and tubular armor 146.

Positioned within the cylindrical cavity 112 of the nozzle body 98, on one side of the valve seat 116, is an annular valve guide 164. The guide valve 164 has a centrally located guide opening 165 that extends around the member. valve ball 148 and is operable to guide the members by reciprocating movement in and out of contact with valve seat 116. Fuel openings 166 extend through valve guide 164 at circumferentially spaced locations around the valve seat. ring to allow the fuel to move freely from the internal cylindrical fuel collecting cavity 112 to the valve seat 116.

The armature bearing 156 in the tube 64 and the annular valve guide 164 cooperate to control the movement of the valve member 16 in the longitudinal direction, inside the injector 10. The member of the valve member 148 of the valve member 16 is normally pressed to a contact seated and closed with the valve seat 116 by a pressure member such as a valve return spring 168 of a predetermined spring force which is inserted into the upstream end of the tubular frame 146. The first end of the spring 168 sits against the shoulder 172 which is located in the middle of the ends of the armature tube while the second of the spring 178 sits against the lower end 176 of the calibration sleeve 178 inserted into the central continuous hole 51 of the pole piece 50. The calibration sleeve is moved axially towards the valve seat to increase the preload of the spring exerted on the valve member 16 in the direction of the valve seat 116. Removal of the calibration sleeve 178 decreases the spring preload of the valve member 16. The calibration sleeve 178 is fixed in position within the pole piece. 50 through the application of a stacking process in which a mechanical stacking tool (not shown) is inserted into the openings 182 in the overmoulded box 54. Once the desired spring preload is achieved through movement axially of the calibration sleeve 178, the stacking tool moves to deform the upper cylindrical portion 58, FIG. 2, of the pole piece radially inwardly of the sleeve 178 thereby securing the sleeve of axial movement.

A working air gap 184 is defined between the work surface 186 at the upper end of the armature tube 146 of the valve member 16 and the work surface 66 at the lower end of the pole piece 50. When the assembly is activated of solenoid 18, tubular armature 146 and associated valve element 148 is pulled upwardly, out of valve seat 116, by the action of the magnetic flux field operating through the working air gap operating against the pressure of the spring member 168 to close the working air separation 184. The location of the working air separation between the ends of the coil 36, as described herein, maximizes the flow directed through the air separation of work, which in turn, improves the efficiency of the solenoid actuator and, consequently, the operation of the injector 10. The fuel enters the injector 10 from the pressurized source, through the first inlet end 76 of the fuel inlet tube 74 where it passes through the filter element 188 of the filter assembly 96. The fuel flows through the length of the tube 74, the pole piece 50, the sleeve of calibration 178 and the tubular armature 146 and inside the fuel chamber 112 in the nozzle body 98 through the circumferentially spaced openings 192 at the second end of the armature tube 146. As described above, the fuel passes to through the openings 166 in the valve guide 164 and out of the valve body 98 through the opening 118 in the valve seat 116. The fuel exiting the valve seat 116 is distributed on the upstream side 126 of the fuel director plate 122 where it is distributed to the fuel directing orifices 124 passing through the plate, for discharge from the fuel injector 10. The de-energization of the fuel The solenoid assembly 18 allows the field within the magnetic circuit defined by the pole piece 50, the body 12, and the frame 146 to collapse thereby allowing the valve member to return to the closed position against the valve seat 116. under the pressure of the spring member 168 to stop the flow of fuel therethrough.

The above description of the preferred embodiment of the invention has been presented for the purpose of illustration and description. The one that is exhaustive is not intended, nor is it intended to limit the invention to the precise form described. It will be evident to those skilled in the art that the described modalities can be modified in light of the teachings given above. The described modalities were chosen to provide an illustration of the principles of the invention and their practical application to thereby enable a person with ordinary skill in the art to use the invention in various embodiments and with various modifications as appropriate to the use of the invention. particular contemplated. Therefore, the above description is considered exemplary, rather than limiting, and the true scope of the invention is that described in the following clauses:

Claims (8)

R E I V I N D I C A C I ON E S

1. A fuel injector comprising a tubular injector body defining an axial fuel conduit, a solenoid assembly positioned in said injector body and including a reel type spool with a central continuous orifice and a coil of wound wire held on the same, a piece of pole including a tubular cylindrical pole having, at its terminal end, a work surface, said cylindrical pole configured for an axial arrangement inside said central continuous hole of said coil to therefore place said work surface in means of the coil of wire, and a non-magnetic cylindrical tube extending axially having a first end received around the terminal end of said cylindrical pole and a second end axially positioned of said working surface and the central continuous hole of said coil, inside said axial fuel conduit of said tubular injector body, and a seal or, placed between said second end of said non-magnetic cylindrical tube and said tubular injector body to define a seal against the entry of fuel into said wire coil.

2. A fuel injector comprising a tubular injector body having a stepped axial continuous bore comprising a first cylindrical wall and an intermediate cylindrical wall, a solenoid assembly positioned in said stepped axial continuous bore of said injector body to one side of the first cylindrical wall and including a spool-type coil with a central continuous hole defining a fuel conduit, and a coil of coiled wire supported thereon, a pole piece including a tubular cylindrical pole having a flange portion extending radially and, at its terminal end, a work surface, said cylindrical pole is configured for an axial disposition within said central continuous orifice of said coil to thereby place said working surface in the middle of the wire spool and to close said first cylindrical wall of said axial continuous hole of said injector body, and a non-magnetic cylindrical tube extending axially having a first end received around said terminal end of said cylindrical pole and a second axially located end of said working surface and said central continuous hole of said coil, adjacent said intermediate cylindrical wall, said second end of said cylindrical tube defines a seal with said intermediate cylindrical wall against the entry of the fuel to said wire coil.

3. A fuel injector comprising an injector body, an armature, a solenoid assembly operable to reciprocate said armature reciprocably within said injector body, a pole piece including a tubular cylindrical pole configured to be placed within said solenoid assembly, and a cylindrical tube having a first end in communication with said cylindrical pole and a second end configured to receive said reinforcement there, said cylindrical tube includes an annular bearing surface extending radially inward positioned in the middle of the first and second ends for a circumjacent sliding support of said reinforcement there.

4. A fuel injector as claimed in clause 3, characterized in that said annular bearing surface has an axially extending radius configuration.

5. A fuel injector as claimed in clause 3, characterized in that said annular bearing surface has a radial configuration extending axially such that the axially intermediate part of said bearing surface defines a minimum internal diameter of said tube cylindrical.

6. A fuel injector comprising a tubular injector body defining an axial fuel conduit, an armature, a set of solenoid placed in said injector body, which can be operated to move said reciprocating armature inside the injector body, and including a reel-type coil with a continuous central hole and a coil of wound wire held there, a piece of pole including a tubular cylindrical pole having, at its terminal end, a work surface, said cylindrical pole configured for an axial positioning inside said central continuous orifice of said coil to therefore place said work surface in the middle of the wire coil, and a non-magnetic cylindrical tube extending axially having a first end received around said terminal end of said cylindrical pole and a second end, axially positioned of said working surface, and said continuous hole of said coil within of said axial fuel conduit of said tubular injector body, configured to receive di Here, said cylindrical tube includes an annular bearing surface extending radially inward positioned in the middle of said first and second ends for a slidable support circumjacent said armature therein.

7. A fuel injector as claimed in clause 6, characterized in that it also includes a seal member, placed between said second end of said non-magnetic cylindrical tube and said tubular injector body to define a seal against the entry of fuel to said coil of wire.

8. A fuel injector as claimed in clause 6, characterized in that said annular bearing surface has a radial configuration extending axially such that the axially intermediate part of said bearing surface defines a minimum internal diameter of said cylinder . SUMMARY A fuel injector for use on an internal combustion engine including a tubular injector body defining an axial fuel conduit. Placed inside the injector body is an armature, a solenoid assembly which includes a spool-type coil with a central continuous bore and a coil of wound wire. A pole piece includes a tubular cylindrical pole having, at its terminal end, a work surface. The cylindrical pole is configured for axial positioning within the central continuous bore of the coil so that it is placed within the working surface in the middle of the ends of the wire coil. An axially extending non-magnetic cylindrical tube has a first end received around the terminal end of the cylindrical pole and has a second end, positioned axially downwardly of the working surface of the pole and the central continuous hole of the coil inside the duct of axial fuel from the tubular injector body. The tubular member is configured to receive the armature and includes an annular bearing surface extending radially inward positioned in the middle of the first and second ends for a slidable support circumjacent said armature therein. The second end of the non-magnetic tubular member can cooperate with the tubular injector body to form a seal against the fuel inlet inside the wound wire coil of the solenoid actuator.